Development and validation of an HPLC method for the determination of dibenzoylmethane in rat plasma and its application to the pharmacokinetic study.

PubMed

Shen, Guoxiang; Hong, Jin-Liern; Kong, Ah-Ng Tony

2007-06-01

A highly sensitive and simple high-performance liquid chromatographic (HPLC) assay has been developed and validated for the quantification of dibenzoylmethane (DBM) in rat plasma. DBM and internal standard (I.S.) 1-(5-chloro-2-hydroxy-4-methylphenyl)-3-phenyl-1,3-propanedione (CHMPP) were extracted from rat plasma by ethyl acetate/methanol (95:5, v/v) and analyzed using reverse-phase gradient elution with a Phenomenex Gemini C18 5-mum column. A gradient of mobile phase (mobile phase A: water/methanol (80:20, v/v) with 0.1% TFA and mobile phase B: acetonitrile with 0.1% TFA) at a flow rate of 0.2 mL/min, and ultraviolet (UV) detection at 335 nm were utilized. The lower limit of quantification (LLOQ) using 50 microL rat plasma was 0.05 microg/mL. The calibration curve was linear over a concentration range of 0.05-20 microg/mL. The mean recoveries were 80.6+/-5.7, 83.4+/-1.6 and 77.1+/-3.4% with quality control (QC) level of 0.05, 1 and 20 microg/mL, respectively. Intra- and inter-day assay accuracy and precision fulfilled US FDA guidance for industry bioanalytical method validation. Stability studies showed that DBM was stable in rat plasma after 4h incubation at room temperature, one month storage at -80 degrees C and three freeze/thaw cycles, as well as in reconstitute buffer for 48 h at 4 degrees C. The utility of the assay was confirmed by the successful analysis of plasma samples from DBM pharmacokinetics studies in the rats after oral and intravenous administrations.

Simultaneous Quantification of Dexpanthenol and Resorcinol from Hair Care Formulation Using Liquid Chromatography: Method Development and Validation.

PubMed

De, Amit Kumar; Chowdhury, Partha Pratim; Chattapadhyay, Shyamaprasad

2016-01-01

The current study presents the simultaneous quantification of dexpanthenol and resorcinol from marketed hair care formulation. Dexpanthenol is often present as an active ingredient in personal care products for its beautifying and invigorating properties and restorative and smoothing properties. On the other hand resorcinol is mainly prescribed for the treatment of seborrheic dermatitis of scalp. The toxic side effects of resorcinol limit its use in dermatological preparations. Therefore an accurate quantification technique for the simultaneous estimation of these two components can be helpful for the formulation industries for the accurate analysis of their product quality. In the current study a high performance liquid chromatographic technique has been developed using a C18 column and a mobile phase consisting of phosphate buffer of pH = 2.8 following a gradient elution. The mobile phase flow rate was 0.6 mL per minute and the detection wavelength was 210 nm for dexpanthenol and 280 nm for resorcinol. The linearity study was carried out using five solutions having concentrations ranging between 10.34 μg·mL(-1) and 82.69 μg·mL(-1) (r (2) = 0.999) for resorcinol and 10.44 μg·mL(-1) and 83.50 μg·mL(-1) (r (2) = 0.998) for dexpanthenol. The method has been validated as per ICH Q2(R1) guidelines. The ease of single step sample preparation, accuracy, and precision (intraday and interday) study presents the method suitable for the simultaneous quantification of dexpanthenol and resorcinol from any personal care product and dermatological preparations containing these two ingredients.

Simultaneous Quantification of Dexpanthenol and Resorcinol from Hair Care Formulation Using Liquid Chromatography: Method Development and Validation

PubMed Central

De, Amit Kumar; Chowdhury, Partha Pratim; Chattapadhyay, Shyamaprasad

2016-01-01

The current study presents the simultaneous quantification of dexpanthenol and resorcinol from marketed hair care formulation. Dexpanthenol is often present as an active ingredient in personal care products for its beautifying and invigorating properties and restorative and smoothing properties. On the other hand resorcinol is mainly prescribed for the treatment of seborrheic dermatitis of scalp. The toxic side effects of resorcinol limit its use in dermatological preparations. Therefore an accurate quantification technique for the simultaneous estimation of these two components can be helpful for the formulation industries for the accurate analysis of their product quality. In the current study a high performance liquid chromatographic technique has been developed using a C18 column and a mobile phase consisting of phosphate buffer of pH = 2.8 following a gradient elution. The mobile phase flow rate was 0.6 mL per minute and the detection wavelength was 210 nm for dexpanthenol and 280 nm for resorcinol. The linearity study was carried out using five solutions having concentrations ranging between 10.34 μg·mL−1 and 82.69 μg·mL−1 (r 2 = 0.999) for resorcinol and 10.44 μg·mL−1 and 83.50 μg·mL−1 (r 2 = 0.998) for dexpanthenol. The method has been validated as per ICH Q2(R1) guidelines. The ease of single step sample preparation, accuracy, and precision (intraday and interday) study presents the method suitable for the simultaneous quantification of dexpanthenol and resorcinol from any personal care product and dermatological preparations containing these two ingredients. PMID:27042377

Improved LC-MS/MS method for the quantification of hepcidin-25 in clinical samples.

PubMed

Abbas, Ioana M; Hoffmann, Holger; Montes-Bayón, María; Weller, Michael G

2018-06-01

Mass spectrometry-based methods play a crucial role in the quantification of the main iron metabolism regulator hepcidin by singling out the bioactive 25-residue peptide from the other naturally occurring N-truncated isoforms (hepcidin-20, -22, -24), which seem to be inactive in iron homeostasis. However, several difficulties arise in the MS analysis of hepcidin due to the "sticky" character of the peptide and the lack of suitable standards. Here, we propose the use of amino- and fluoro-silanized autosampler vials to reduce hepcidin interaction to laboratory glassware surfaces after testing several types of vials for the preparation of stock solutions and serum samples for isotope dilution liquid chromatography-tandem mass spectrometry (ID-LC-MS/MS). Furthermore, we have investigated two sample preparation strategies and two chromatographic separation conditions with the aim of developing a LC-MS/MS method for the sensitive and reliable quantification of hepcidin-25 in serum samples. A chromatographic separation based on usual acidic mobile phases was compared with a novel approach involving the separation of hepcidin-25 with solvents at high pH containing 0.1% of ammonia. Both methods were applied to clinical samples in an intra-laboratory comparison of two LC-MS/MS methods using the same hepcidin-25 calibrators with good correlation of the results. Finally, we recommend a LC-MS/MS-based quantification method with a dynamic range of 0.5-40 μg/L for the assessment of hepcidin-25 in human serum that uses TFA-based mobile phases and silanized glass vials. Graphical abstract Structure of hepcidin-25 (Protein Data Bank, PDB ID 2KEF).

Rapid quantification of resveratrol in mouse plasma by ultra high pressure liquid chromatography (UPLC) coupled to tandem mass spectrometry.

PubMed

Castillo-Pichardo, Linette; Dharmawardhane, Suranganie; Rodríguez-Orengo, José F

2014-12-01

The objective of this study was to develop a rapid and sensitive method for the quantification of resveratrol, a polyphenolic compound with multiple health beneficial effects, in mouse plasma. We used reversed-phase ultra high pressure-liquid chromatography with tandem mass spectrometry detection for the determination of resveratrol levels in mouse plasma. An Agilent Zorbax Eclipse Plus C18 column (2.1 mm x 50 mm, 1.8 μm) was used as the stationary phase. The mobile phase consisted of a gradient formed using 1 mM ammonium fluoride and methanol. Using this improved method, we obtained a retention time of 2.2 min and a total run time of 5 min, for resveratrol. The calibration curve for resveratrol showed a linear range from 0.5 to 100 ng/mL. The average coefficient of variation was 6% for interday variation and 4% for intraday variation. The recovery for resveratrol in mouse plasma was 85 ± 10% (mean ± standard deviation). The method presented herein allows a rapid and very sensitive quantification of resveratrol in mouse plasma at concentrations as low as 500 ppt.

Enantiomeric separation and quantification of R/S-amphetamine in urine by ultra-high performance supercritical fluid chromatography tandem mass spectrometry.

PubMed

Hegstad, S; Havnen, H; Helland, A; Spigset, O; Frost, J

2018-03-01

To distinguish between legal and illegal consumption of amphetamine reliable analytical methods for chiral separation of the R- and S-enantiomers of amphetamine in biological specimens are required. In this regard, supercritical fluid chromatography (SFC) has several potential advantages over liquid chromatography, including rapid separation of enantiomers due to low viscosity and high diffusivity of supercritical carbon dioxide, the main component in the SFC mobile phase. A method for enantiomeric separation and quantification of R- and S-amphetamine in urine was developed and validated using ultra-high performance supercritical fluid chromatography-tandem mass spectrometry (UHPSFC-MS/MS). Sample preparation prior to UHPSFC-MS/MS analysis was a semi-automatic solid phase extraction method. The UHPSFC-MS/MS method used a Chiralpak AD-3 column with a mobile phase consisting of CO 2 and 0.2% cyclohexylamine in 2-propanol. The injection volume was 2 μL and run-time was 6 min. MS/MS detection was performed with positive electrospray ionization and two multiple reaction monitoring transitions (m/z 136.1 > 119.0 and m/z 136.1 > 91.0). The calibration range was 50-10,000 ng/mL for each enantiomer. The between-assay relative standard deviations were in the range of 3.7-7.6%. Recovery was 92-93% and matrix effects ranged from 100 to 104% corrected with internal standard. After development and validation, the method has been successfully implemented in routine use at our laboratory for both separation and quantification of R/S-amphetamine, and has proved to be a reliable and useful tool for distinguishing intake of R- and S-amphetamine in authentic patient samples. Copyright © 2018 Elsevier B.V. All rights reserved.

Rapid quantification of imidazolium-based ionic liquids by hydrophilic interaction liquid chromatography: Methodology and an investigation of the retention mechanisms.

PubMed

Hawkins, Cory A; Rud, Anna; Guthrie, Margaret L; Dietz, Mark L

2015-06-26

The separation of nine N,N'-dialkylimidazolium-based ionic liquids (ILs) by an isocratic hydrophilic interaction high-performance liquid chromatographic method using an unmodified silica column was investigated. The chosen analytical conditions using a 90:10 acetonitrile-ammonium formate buffer mobile phase on a high-purity, unmodified silica column were found to be efficient, robust, and sensitive for the determination of ILs in a variety of solutions. The retention window (k' = 2-11) was narrower than that of previous methods, resulting in a 7-min runtime for the nine IL homologues. The lower limit of quantification of the method, 2-3 μmol L(-1), was significantly lower than those reported previously for HPLC-UV methods. The effects of systematically modifying the IL cation alkyl chain length, column temperature, and mobile-phase water and buffer content on solute retention were examined. Cation exchange was identified as the dominant retention mechanism for most of the solutes, with a distinct (single methylene group) transition to a dominant partitioning mode at the highest solute polarity. Copyright © 2015 Elsevier B.V. All rights reserved.

Simultaneous determination of atorvastatin calcium and olmesartan medoxomil in a pharmaceutical formulation by reversed phase high-performance liquid chromatography, high-performance thin-layer chromatography, and UV spectrophotometric methods.

PubMed

Soni, Hiral; Kothari, Charmy; Khatri, Deepak; Mehta, Priti

2014-01-01

Validated RP-HPLC, HPTLC, and UV spectrophotometric methods have been developed for the simultaneous determination of atorvastatin calcium (ATV) and olmesartan medoxomil (OLM) in a pharmaceutical formulation. The RP-HPLC separation was achieved on a Kromasil C18 column (250 x 4.6 mm, 5 microm particle size) using 0.01 M potassium dihydrogen o-phosphate (pH 4 adjusted with o-phosphoric acid)-acetonitrile (50 + 50, v/v) as the mobile phase at a flow rate of 1.5 mL/min. Quantification was achieved by UV detection at 276 nm. The HPTLC separation was achieved on precoated silica gel 60F254 plates using chloroform-methanol-acetonitrile (4 + 2+ 4, v/v/v) mobile phase. Quantification was achieved with UV detection at 276 nm. The UV-Vis spectrophotometric method was based on the simultaneous equation method that involves measurement of absorbance at two wavelengths, i.e., 255 nm (lambda max of OLM) and 246.2 nm (lambda max of ATV) in methanol. All three methods were validated as per International Conference on Harmonization guidelines. The proposed methods were simple, precise, accurate, and applicable for the simultaneous determination of ATV and OLM in a marketed formulation. The results obtained by applying the proposed methods were statistically analyzed and were found satisfactory.

Industrial application of green chromatography--I. Separation and analysis of niacinamide in skincare creams using pure water as the mobile phase.

PubMed

Yang, Yu; Strickland, Zackary; Kapalavavi, Brahmam; Marple, Ronita; Gamsky, Chris

2011-03-15

In this work, chromatographic separation of niacin and niacinamide using pure water as the sole component in the mobile phase has been investigated. The separation and analysis of niacinamide have been optimized using three columns at different temperatures and various flow rates. Our results clearly demonstrate that separation and analysis of niacinamide from skincare products can be achieved using pure water as the eluent at 60°C on a Waters XTerra MS C18 column, a Waters XBridge C18 column, or at 80°C on a Hamilton PRP-1 column. The separation efficiency, quantification quality, and analysis time of this new method are at least comparable with those of the traditional HPLC methods. Compared with traditional HPLC, the major advantage of this newly developed green chromatography technique is the elimination of organic solvents required in the HPLC mobile phase. In addition, the pure water chromatography separations described in this work can be directly applied in industrial plant settings without further modification of the existing HPLC equipment. Copyright © 2011 Elsevier B.V. All rights reserved.

Development and validation of stability indicating the RP-HPLC method for the estimation of related compounds of guaifenesin in pharmaceutical dosage forms.

PubMed

Reddy, Sunil Pingili; Babu, K Sudhakar; Kumar, Navneet; Sekhar, Y V V Sasi

2011-10-01

A stability-indicating gradient reverse phase liquid chromatographic (RP-LC) method was developed for the quantitative determination of related substances of guaifenesin in pharmaceutical formulations. The baseline separation for guaifenesin and all impurities was achieved by utilizing a Water Symmetry C18 (150 mm × 4.6 mm) 5 μm column particle size and a gradient elution method. The mobile phase A contains a mixture of 0.02 M KH2PO4 (pH 3.2) and methanol in the ratio of 90:10 v/v, while the mobile phase B contains 0.02 M KH2PO4 (pH 3.2) and methanol in the ratio of 10:90 v/v, respectively. The flow rate of the mobile phase was 0.8 ml/min with a column temperature of 25°C and detection wavelength at 273 nm. Guaifenesin was subjected to the stress conditions of oxidative, acid, base, hydrolytic, thermal, and photolytic degradation. The developed method was validated as per ICH guidelines with respect to specificity, linearity, limit of detection and quantification, accuracy, precision, and robustness.

Development and validation of stability indicating the RP-HPLC method for the estimation of related compounds of guaifenesin in pharmaceutical dosage forms

PubMed Central

Reddy, Sunil Pingili; Babu, K. Sudhakar; Kumar, Navneet; Sekhar, Y. V. V. Sasi

2011-01-01

Aim and background: A stability-indicating gradient reverse phase liquid chromatographic (RP-LC) method was developed for the quantitative determination of related substances of guaifenesin in pharmaceutical formulations. Materials and methods: The baseline separation for guaifenesin and all impurities was achieved by utilizing a Water Symmetry C18 (150 mm × 4.6 mm) 5 μm column particle size and a gradient elution method. The mobile phase A contains a mixture of 0.02 M KH2PO4 (pH 3.2) and methanol in the ratio of 90:10 v/v, while the mobile phase B contains 0.02 M KH2PO4 (pH 3.2) and methanol in the ratio of 10:90 v/v, respectively. The flow rate of the mobile phase was 0.8 ml/min with a column temperature of 25°C and detection wavelength at 273 nm. Results: Guaifenesin was subjected to the stress conditions of oxidative, acid, base, hydrolytic, thermal, and photolytic degradation. Conclusion: The developed method was validated as per ICH guidelines with respect to specificity, linearity, limit of detection and quantification, accuracy, precision, and robustness. PMID:23781462

Standardization of HPTLC method for the estimation of oxytocin in edibles.

PubMed

Rani, Roopa; Medhe, Sharad; Raj, Kumar Rohit; Srivastava, Manmohan

2013-12-01

Adulteration in food stuff has been regarded as a major social evil and is a mind-boggling problem in society. In this study, a rapid, reliable and cost effective High Performance thin layer Chromatography (HPTLC) has been established for the estimation of oxytocin (adulterant) in vegetables, fruits and milk samples. Oxytocin is one of the most frequently used adulterant added in vegetables and fruits for increasing the growth rate and also to enhance milk production from lactating animals. The standardization of the method was based on simulation parameters of mobile phase, stationary phase and saturation time. The mobile phase used was MeOH: Ammonia (pH 6.8), optimized stationary phase was silica gel and saturation time of 5 min. The method was validated by testing its linearity, accuracy, precision, repeatability and limits of detection and quantification. Thus, the proposed method is simple, rapid and specific and was successfully employed for quality and quantity monitoring of oxytocin content in edible products.

SDS-PAGE Electrophoretic Property of Human Chorionic Gonadotropin (hCG) and its β-subunit

PubMed Central

2005-01-01

The microheterogeneity property of hCG with regards to its sialic acid contents resulted in variable mobility of the glycoprotein in SDS-PAGE. The intact hCG molecule is composed of two dissimilar subunits, namely α- and β-subunits. The identification of hCG bands in SDS-PAGE was accomplished by the immunoblotting experiment, whereby the antibody directed toward the specific region of β-subunit of hCG was used. The data shows that the different mobility of intact hCG was attributed to the different degree of desialylation of the glycoprotein. Nevertheless, unlike the intact hCG, the mobility of its β-subunit was not affected by its variety sialic acid content. This characteristic of β-hCG is beneficial when semi-quantification of total hCG is required. Quantification of hCG using the HPLC-reversed phase C18 analytical column is not possible as the glycoprotein was eluted in multiple fractions at different retention times. The identification of denatured hCG (HPLC eluted fractions) was carried out by immunoblotting experiment whilst immunoassay technique failed to detect its presence in any fraction. PMID:16094462

Quantification of Sulfur in Mobility Fuels

DTIC Science & Technology

2017-04-20

during combustion. Any discrepancy between actual measured SO2 and expected SO2 based on the “full conversion” assumption could likely be accounted for...phase analysis, electrochemical SO2measurements, and optical SO2 measurements . Much of the work focused on SO2 as a single analyte that could be produced...sulfur compounds typically found in liquid fuels. Cermet (ceramic-metallic) sensor measurements showed promise in terms of response and sensitivity to

RP-HPLC×HILIC chromatography for quantifying ertapenem sodium with a look at green chemistry.

PubMed

Pedroso, Tahisa M; Medeiros, Ana C D; Salgado, Herida R N

2016-11-01

Ertapenem sodium is a polar and ionizable compound; therefore, it has little retention on traditional C18 columns in reverse-phase high-performance liquid chromatography, even using a highly-aqueous mobile phase that can result in dewetting in the stationary phase. Thus, the most coherent process for ERTM is to develop a method for Hydrophilic Interaction Chromatography. However, for the traditional methods in HILIC, the use of a highly organic mobile phase is necessary; usually an amount exceeding 80% acetonitrile is necessary. On the other hand, the RP-HPLC mode is considered for the analysis technique, which is more often used for quantification of substances, and new columns are often introduced to analyze different groups of compounds. Two new analytical methods have been developed for routine analysis. The proposed chromatographic method was adequate and advantageous by presenting simplicity, linearity, precision, accuracy, robustness, detection limits, and satisfactory quantification. Analytical methods are constantly undergoing changes and improvements. Researchers worldwide are rapidly adopting Green Chemistry. The development of new pharmaceutical methods based in Green chemistry has been encouraged by universities and the pharmaceutical industry. Issues related to green chemistry are in evidence and they have been featured in international journals of high impact. The methods described here have economic advantages and they feature an eco-friendly focus, which is discussed in this work. This work was developed with an environmental conscience, always looking to minimize the possible generated organic waste. Therefore, discussion on this aspect is included. Copyright © 2016 Elsevier B.V. All rights reserved.

Optimization of a new mobile phase to know the complex and real polyphenolic composition: towards a total phenolic index using high-performance liquid chromatography.

PubMed

Tsao, Rong; Yang, Raymond

2003-11-07

An HPLC method is reported for the separation and quantification of five major polyphenolic groups found in fruits and related products: single ring phenolic acids (hydroxybenzoic acid and hydroxycinnamic acid derivatives), flavan-3-ols, flavonols, anthocyanins, and dihydrochalcones. A binary mobile phase consisting of 6% acetic acid in 2 mM sodium acetate aqueous solution (v/v, final pH 2.55) (solvent A) and acetonitrile (solvent B) was used. The use of sodium acetate was new and key to the near baseline separation of 25 phenolics commonly found in fruits. A photodiode array detector was used and data were collected at four wavelengths (280, 320, 360, and 520 nm). This method was sensitive and gave good separation of polyphenolics in apple, cherry, strawberry, blackberry, grape, apple juice, and a processing by-product. The improved separation has led to better understanding of the polyphenolic profiles of these fruits. Individual as well as total phenolic content was obtained, and the latter was close to and correlated well with that obtained by the Folin-Ciocalteu method (FC). The HPLC data can be used as a total phenolic index (TPI) for quantification of fruit phenolics, which is advantageous over the FC because it has more information on individual compounds.

Peptide-based, two-fluorophore, ratiometric probe for quantifying mobile zinc in biological solutions.

PubMed

Zhang, Daniel Y; Azrad, Maria; Demark-Wahnefried, Wendy; Frederickson, Christopher J; Lippard, Stephen J; Radford, Robert J

2015-02-20

Small-molecule fluorescent sensors are versatile agents for detecting mobile zinc in biology. Capitalizing on the abundance of validated mobile zinc probes, we devised a strategy for repurposing existing intensity-based sensors for quantitative applications. Using solid-phase peptide synthesis, we conjugated a zinc-sensitive Zinpyr-1 derivative and a zinc-insensitive 7-hydroxycoumarin derivative onto opposite ends of a rigid P9K peptide scaffold to create HcZ9, a ratiometric fluorescent probe for mobile zinc. A plate reader-based assay using HcZ9 was developed, the accuracy of which is comparable to that of atomic absorption spectroscopy. We investigated zinc accumulation in prostatic cells and zinc levels in human seminal fluid. When normal and tumorigenic cells are bathed in zinc-enriched media, cellular mobile zinc is buffered and changes slightly, but total zinc levels increase significantly. Quantification of mobile and total zinc levels in human seminal plasma revealed that the two are positively correlated with a Pearson's coefficient of 0.73.

Simultaneous determination of sibutramine and its active metabolites in human plasma by LC-MS/MS and its application to a pharmacokinetic study.

PubMed

Bae, Jung-Woo; Choi, Chang-Ik; Jang, Choon-Gon; Lee, Seok-Yong

2011-11-01

A simple and sensitive liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) technique was developed and validated for the determination of sibutramine and its N-desmethyl metabolites (M1 and M2) in human plasma. After extraction with methyl t-butyl ether, chromatographic separation of analytes in human plasma was performed using a reverse-phase Luna C18 column with a mobile phase of acetonitrile-10 mm ammonium formate buffer (50:50, v/v) and quantified by ESI-MS/MS detection in positive ion mode. The flow rate of the mobile phase was 200 μL/min and the retention times of sibutramine, M1, M2 and internal standard (chlorpheniramine) were 1.5, 1.4, 1.3 and 0.9 min, respectively. The calibration curves were linear over the range 0.05-20 ng/mL, for sibutramine, M1 and M2. The lower limit of quantification was 0.05 ng/mL using 500 μL of human plasma. The mean accuracy and the precision in the intra- and inter-day validation for sibutramine, M1 and M2 were acceptable. This LC-MS/MS method showed improved sensitivity and a short run time for the quantification of sibutramine and its two active metabolites in plasma. The validated method was successfully applied to a pharmacokinetic study in human. Copyright © 2011 John Wiley & Sons, Ltd.

Simultaneous quantification of eleven cannabinoids and metabolites in human urine by liquid chromatography tandem mass spectrometry using WAX-S tips

PubMed Central

Andersson, Maria; Scheidweiler, Karl B.; Sempio, Cristina; Barnes, Allan; Huestis, Marilyn A.

2016-01-01

A comprehensive cannabinoids urine quantification method may improve clinical and forensic results interpretation and is necessary to support our clinical research. A liquid chromatography tandem mass spectrometry quantification method for Δ9-tetrahydrocannabinol (THC), 11-hydroxy-THC (11-OH-THC), 11-nor-9-carboxy-THC (THCCOOH), Δ9-tetrahydrocannabinolic acid (THCAA), cannabinol (CBN), cannabidiol (CBD), cannabigerol (CBG), Δ9-tetrahydrocannabivarin (THCV), 11-nor-9-carboxy-THCV (THCVCOOH), THC-glucuronide (THC-gluc) and THCCOOH-gluc (THCCOOH-gluc) in urine was developed and validated according to the Scientific Working Group on Toxicology guidelines. Sample preparation consisted of disposable pipette extraction (WAX-S) of 200μL urine. Separation was achieved on a Kinetex C18 column using gradient elution with flow rate 0.5 mL/min, mobile phase A (10 mM ammonium acetate in water) and mobile phase B (15% methanol in acetonitrile). Total run time was 14 min. Analytes were monitored in both positive and negative ionization modes by scheduled multiple reaction monitoring. Linear ranges were 0.5–100 μg/L for THC and THCCOOH, 0.5–50 μg/L for 11-OH-THC, CBD, CBN, THCAA and THC-gluc, 1–100 μg/L for CBG, THCV and THCVCOOH and 5–500 μg/L for THCCOOH-gluc (R2>0.99). Analytical biases were 88.3–113.7%, imprecisions 3.3–14.3%, extraction efficiencies 42.4–81.5% and matrix effect −10 to 32.5%. We developed and validated a comprehensive, simple and rapid LC-MS/MS cannabinoid urine method for quantification of 11 cannabinoids and metabolites. This method is being used in a controlled cannabis administration study, investigating urine cannabinoid markers documenting recent cannabis use, chronic frequent smoking or route of drug administration and potentially improving urine cannabinoid result interpretation. PMID:27422645

Determination of flubendiamide in honey at trace levels by using solid phase extraction and liquid chromatography coupled to quadrupole time-of-flight mass spectrometry.

PubMed

Ares, Ana M; Valverde, Silvia; Bernal, José L; Toribio, Laura; Nozal, María J; Bernal, José

2017-10-01

In this study, a new method has been developed to determine flubendiamide in honey using liquid chromatography coupled to a selective mass spectrometry detector (quadrupole-time-of-flight). An efficient sample treatment involving a solid phase extraction with a C 18 sorbent was proposed (average analyte recoveries were between 94 and 104%). Chromatographic analysis (9min) was performed on a C 18 column (Gemini C 18 , 50×2.0mm, 3µm, 110Å). The mobile phase consisted of water and acetonitrile, with a flow rate of 0.5mL/min in gradient elution mode. The method was fully validated in terms of selectivity, limits of detection and quantification, matrix effect, linearity, trueness and precision. Low limits of detection and quantification were obtained, ranging from 0.1 to 0.2µg/kg and 0.4 to 0.6µg/kg, respectively. The method was applied to analyze flubendiamide in honey from different botanic origins (multifloral, rosemary and heather). Copyright © 2017 Elsevier Ltd. All rights reserved.

Simultaneous quantification of flavonoids and triterpenoids in licorice using HPLC.

PubMed

Wang, Yuan-Chuen; Yang, Yi-Shan

2007-05-01

Numerous bioactive compounds are present in licorice (Glycyrrhizae Radix), including flavonoids and triterpenoids. In this study, a reversed-phase high-performance liquid chromatography (HPLC) method for simultaneous quantification of three flavonoids (liquiritin, liquiritigenin and isoliquiritigenin) and four triterpenoids (glycyrrhizin, 18alpha-glycyrrhetinic acid, 18beta-glycyrrhetinic acid and 18beta-glycyrrhetinic acid methyl ester) from licorice was developed, and further, to quantify these 7 compounds from 20 different licorice samples. Specifically, the reverse-phase HPLC was performed with a gradient mobile phase composed of 25 mM phosphate buffer (pH 2.5)-acetonitrile featuring gradient elution steps as follows: 0 min, 100:0; 10 min, 80:20; 50 min, 70:30; 73 min, 50:50; 110 min, 50:50; 125 min, 20:80; 140 min, 20:80, and peaks were detected at 254 nm. By using our technique, a rather good specificity was obtained regarding to the separation of these seven compounds. The regression coefficient for the linear equations for the seven compounds lay between 0.9978 and 0.9992. The limits of detection and quantification lay in the range of 0.044-0.084 and 0.13-0.25 microg/ml, respectively. The relative recovery rates for the seven compounds lay between 96.63+/-2.43 and 103.55+/-2.77%. Coefficient variation for intra-day and inter-day precisions lay in the range of 0.20-1.84 and 0.28-1.86%, respectively. Based upon our validation results, this analytical technique is a convenient method to simultaneous quantify numerous bioactive compounds derived from licorice, featuring good quantification parameters, accuracy and precision.

Concurrent estimation of amlodipine besylate, hydrochlorothiazide and valsartan by RP-HPLC, HPTLC and UV-spectrophotometry.

PubMed

Sharma, Manish; Kothari, Charmy; Sherikar, Omkar; Mehta, Priti

2014-01-01

Accurate, sensitive and reproducible reversed-phase high-performance liquid chromatography (RP-HPLC), high-performance thin-layer chromatography (HPTLC) and ultraviolet (UV) spectrophopometric methods were developed for the concurrent estimation of amlodipine besylate (AMLO), hydrochlorothiazide (HCTZ) and valsartan (VALS) in bulk and combined tablet dosage forms. For the RP-HPLC method, separation was achieved on a C18 column using potassium dihydrogen orthophosphate buffer (50 mM, pH 3.7) with 0.2% triethylamine as the modifier and acetonitrile in the ratio of 56:44 (v/v) as the mobile phase. Quantification was achieved using a photodiode array detector at 232 nm over a concentration range of 2-25 µg/mL for AMLO, 5-45 µg/mL for HCTZ and 20-150 µg/mL for VALS. For the HPTLC method, the drugs were separated by using ethyl acetate-methanol-toluene-ammonia (7.5:3:2:0.8, v/v/v/v) as the mobile phase. Quantification was achieved using UV detection at 242 nm over a concentration range of 100-600 ng/spot for AMLO, 150-900 ng/spot for HCTZ and 1,200-3,200 ng/spot for VALS. The UV-spectrophotometric simultaneous equation method was based on the measurement of absorbance at three wavelengths; i.e., at 237.6 nm (λmax of AMLO), 270.2 nm (λmax of HCTZ) and 249.2 nm (λmax of VALS) in methanol. Quantification was achieved over the concentration range of 2-20 µg/mL for AMLO, 5-25 µg/mL HCTZ and 10-50 µg/mL for VALS. All methods were validated according to International Conference on Harmonization guidelines and successfully applied to marketed pharmaceutical formulations. Additionally, the three methods were compared statistically by an analysis of variance test, which revealed no significant difference between the proposed methods with respect to accuracy and precision.

Isocratic RP-HPLC method for rutin determination in solid oral dosage forms.

PubMed

Kuntić, Vesna; Pejić, Natasa; Ivković, Branka; Vujić, Zorica; Ilić, Katarina; Mićić, Svetlana; Vukojević, Vladana

2007-01-17

A rapid and sensitive assay for quantitative determination of rutin in oral dosage forms based on isocratic reversed phase high performance liquid chromatography (RP-HPLC) was developed and validated. Using a C(18) reverse-phase analytical column, the following conditions were chosen as optimal: mobile phase methanol-water 1:1 (v/v), pH 2.8 (adjusted with phosphoric acid), flow rate=1 mL min(-1) and temperature T=40.0 degrees C. Linearity was observed in the concentration range 8-120 microg mL(-1) with a correlation coefficient of 0.99982 and the limit of detection (LOD)=2.6 microg mL(-1), and limit of quantification (LOQ)=8.0 microg mL(-1). Intra- and inter-day precision were within acceptable limits. Robustness test indicated that the mobile phase composition and pH influence mainly the separation. The proposed method allowed direct determination of rutin in pharmaceutical dosage forms in the presence of excipients, but is not suitable for preparations where compounds structurally/chemically related to rutin may be present.

Reduction of Solvent Effect in Reverse Phase Gradient Elution LC-ICP-MS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sullivan, Patrick Allen

2005-12-17

Quantification in liquid chromatography (LC) is becoming very important as more researchers are using LC, not as an analytical tool itself, but as a sample introduction system for other analytical instruments. The ability of LC instrumentation to quickly separate a wide variety of compounds makes it ideal for analysis of complex mixtures. For elemental speciation, LC is joined with inductively coupled plasma mass spectrometry (ICP-MS) to separate and detect metal-containing, organic compounds in complex mixtures, such as biological samples. Often, the solvent gradients required to perform complex separations will cause matrix effects within the plasma. This limits the sensitivity ofmore » the ICP-MS and the quantification methods available for use in such analyses. Traditionally, isotope dilution has been the method of choice for LC-ICP-MS quantification. The use of naturally abundant isotopes of a single element in quantification corrects for most of the effects that LC solvent gradients produce within the plasma. However, not all elements of interest in speciation studies have multiple naturally occurring isotopes; and polyatomic interferences for a given isotope can develop within the plasma, depending on the solvent matrix. This is the case for reverse phase LC separations, where increasing amounts of organic solvent are required. For such separations, an alternative to isotope dilution for quantification would be is needed. To this end, a new method was developed using the Apex-Q desolvation system (ESI, Omaha, NE) to couple LC instrumentation with an ICP-MS device. The desolvation power of the system allowed greater concentrations of methanol to be introduced to the plasma prior to destabilization than with direct methanol injection into the plasma. Studies were performed, using simulated and actual linear methanol gradients, to find analyte-internal standard (AIS) pairs whose ratio remains consistent (deviations {+-} 10%) over methanol concentration ranges of 5%-35% (simulated) and 8%-32% (actual). Quadrupole (low resolution) and sector field (high resolution) ICP-MS instrumentation were utilized in these studies. Once an AIS pair is determined, quantification studies can be performed. First, an analysis is performed by adding both elements of the AIS pair post-column while performing the gradient elution without sample injection. A comparison of the ratio of the measured intensities to the atomic ratio of the two standards is used to determine a correction factor that can be used to account for the matrix effects caused by the mobile phase. Then, organic and/or biological molecules containing one of the two elements in the AIS pair are injected into the LC column. A gradient method is used to vary the methanol-water mixture in the mobile phase and to separate out the compounds in a given sample. A standard solution of the second ion in the AIS pair is added continuously post-column. By comparing the ratio of the measured intensities to the atomic ratio of the eluting compound and internal standard, the concentration of the injected compound can be determined.« less

Rapid Development and Validation of Improved Reversed-Phase High-performance Liquid Chromatography Method for the Quantification of Mangiferin, a Polyphenol Xanthone Glycoside in Mangifera indica

PubMed Central

Naveen, P.; Lingaraju, H. B.; Prasad, K. Shyam

2017-01-01

Mangiferin, a polyphenolic xanthone glycoside from Mangifera indica, is used as traditional medicine for the treatment of numerous diseases. The present study was aimed to develop and validate a reversed-phase high-performance liquid chromatography (RP-HPLC) method for the quantification of mangiferin from the bark extract of M. indica. RP-HPLC analysis was performed by isocratic elution with a low-pressure gradient using 0.1% formic acid: acetonitrile (87:13) as a mobile phase with a flow rate of 1.5 ml/min. The separation was done at 26°C using a Kinetex XB-C18 column as stationary phase and the detection wavelength at 256 nm. The proposed method was validated for linearity, precision, accuracy, limit of detection, limit of quantification, and robustness by the International Conference on Harmonisation guidelines. In linearity, the excellent correlation coefficient more than 0.999 indicated good fitting of the curve and also good linearity. The intra- and inter-day precision showed < 1% of relative standard deviation of peak area indicated high reliability and reproducibility of the method. The recovery values at three different levels (50%, 100%, and 150%) of spiked samples were found to be 100.47, 100.89, and 100.99, respectively, and low standard deviation value < 1% shows high accuracy of the method. In robustness, the results remain unaffected by small variation in the analytical parameters, which shows the robustness of the method. Liquid chromatography–mass spectrometry analysis confirmed the presence of mangiferin with M/Z value of 421. The assay developed by HPLC method is a simple, rapid, and reliable for the determination of mangiferin from M. indica. SUMMARY The present study was intended to develop and validate an RP-HPLC method for the quantification of mangiferin from the bark extract of M. indica. The developed method was validated for linearity, precision, accuracy, limit of detection, limit of quantification and robustness by International Conference on Harmonization guidelines. This study proved that the developed assay by HPLC method is a simple, rapid and reliable for the quantification of the mangiferin from M. indica. Abbreviations Used: M. indica: Mangifera indica, RP-HPLC: Reversed-phase high-performance liquid chromatography, M/Z: Mass to charge ratio, ICH: International conference on harmonization, % RSD: Percentage of relative standard deviation, ppm: Parts per million, LOD: Limit of detection, LOQ: Limit of quantification. PMID:28539748

Rapid Development and Validation of Improved Reversed-Phase High-performance Liquid Chromatography Method for the Quantification of Mangiferin, a Polyphenol Xanthone Glycoside in Mangifera indica.

PubMed

Naveen, P; Lingaraju, H B; Prasad, K Shyam

2017-01-01

Mangiferin, a polyphenolic xanthone glycoside from Mangifera indica , is used as traditional medicine for the treatment of numerous diseases. The present study was aimed to develop and validate a reversed-phase high-performance liquid chromatography (RP-HPLC) method for the quantification of mangiferin from the bark extract of M. indica . RP-HPLC analysis was performed by isocratic elution with a low-pressure gradient using 0.1% formic acid: acetonitrile (87:13) as a mobile phase with a flow rate of 1.5 ml/min. The separation was done at 26°C using a Kinetex XB-C18 column as stationary phase and the detection wavelength at 256 nm. The proposed method was validated for linearity, precision, accuracy, limit of detection, limit of quantification, and robustness by the International Conference on Harmonisation guidelines. In linearity, the excellent correlation coefficient more than 0.999 indicated good fitting of the curve and also good linearity. The intra- and inter-day precision showed < 1% of relative standard deviation of peak area indicated high reliability and reproducibility of the method. The recovery values at three different levels (50%, 100%, and 150%) of spiked samples were found to be 100.47, 100.89, and 100.99, respectively, and low standard deviation value < 1% shows high accuracy of the method. In robustness, the results remain unaffected by small variation in the analytical parameters, which shows the robustness of the method. Liquid chromatography-mass spectrometry analysis confirmed the presence of mangiferin with M/Z value of 421. The assay developed by HPLC method is a simple, rapid, and reliable for the determination of mangiferin from M. indica . The present study was intended to develop and validate an RP-HPLC method for the quantification of mangiferin from the bark extract of M. indica . The developed method was validated for linearity, precision, accuracy, limit of detection, limit of quantification and robustness by International Conference on Harmonization guidelines. This study proved that the developed assay by HPLC method is a simple, rapid and reliable for the quantification of the mangiferin from M. indica . Abbreviations Used: M. indica : Mangifera indica , RP-HPLC: Reversed-phase high-performance liquid chromatography, M/Z: Mass to charge ratio, ICH: International conference on harmonization, % RSD: Percentage of relative standard deviation, ppm: Parts per million, LOD: Limit of detection, LOQ: Limit of quantification.

QUANTIFICATION OF GLYCYRRHIZIN BIOMARKER IN GLYCYRRHIZA GLABRA RHIZOME AND BABY HERBAL FORMULATIONS BY VALIDATED RP-HPTLC METHODS

PubMed Central

Alam, Prawez; Foudah, Ahmed I.; Zaatout, Hala H.; T, Kamal Y; Abdel-Kader, Maged S.

2017-01-01

Background: A simple and sensitive thin-layer chromatographic method has been established for quantification of glycyrrhizin in Glycyrrhiza glabra rhizome and baby herbal formulations by validated Reverse Phase HPTLC method. Materials and Methods: RP-HPTLC Method was carried out using glass coated with RP-18 silica gel 60 F254S HPTLC plates using methanol-water (7: 3 v/v) as mobile phase. Results: The developed plate was scanned and quantified densitometrically at 256 nm. Glycyrrhizin peaks from Glycyrrhiza glabra rhizome and baby herbal formulations were identified by comparing their single spot at Rf = 0.63 ± 0.01. Linear regression analysis revealed a good linear relationship between peak area and amount of glycyrrhizin in the range of 2000-7000 ng/band. Conclusion: The method was validated, in accordance with ICH guidelines for precision, accuracy, and robustness. The proposed method will be useful to enumerate the therapeutic dose of glycyrrhizin in herbal formulations as well as in bulk drug. PMID:28573236

Method for the quantification of vanadyl porphyrins in fractions of crude oils by High Performance Liquid Chromatography-Flow Injection-Inductively Coupled Plasma Mass Spectrometry

NASA Astrophysics Data System (ADS)

Wandekoken, Flávia G.; Duyck, Christiane B.; Fonseca, Teresa C. O.; Saint'Pierre, Tatiana D.

2016-05-01

High performance liquid chromatography hyphenated by flow injection to inductively coupled plasma mass spectrometry (HPLC-FI-ICP-MS) was used to investigate V linked to porphyrins present in fractions of crude oil. First, the crude oil sample was submitted to fractionation by preparative liquid chromatography with UV detection, at the porphyrin Soret band wavelength (400 nm). The obtained porphyrin fractions were then separated in a 250 mm single column, in the HPLC, and eluted with different mobile phases (methanol or methanol:toluene (80:20; v:v)). The quantification of V-porphyrins in the fractions eluted from HPLC was carried out by online measuring the 51V isotope in the ICP-MS, against vanadyl octaethylporphine standard solutions (VO-OEP), prepared in the same solvent as the mobile phase, and injected post-column directly into the plasma. A 20 μg L- 1 Ge in methanol was used as internal standard for minimizing non-spectral interference, such as short-term variations due to injection. The mathematical treatment of the signal based on Fast Fourier Transform smoothing algorithm was employed to improve the precision. The concentrations of V as V-porphyrins were between 2.7 and 11 mg kg- 1 in the fractions, which were close to the total concentration of V in the porphyrin fractions of the studied crude oil.

A high pressure liquid chromatography method for separation of prolactin forms.

PubMed

Bell, Damon A; Hoad, Kirsten; Leong, Lillian; Bakar, Juwaini Abu; Sheehan, Paul; Vasikaran, Samuel D

2012-05-01

Prolactin has multiple forms and macroprolactin, which is thought not to be bioavailable, can cause a raised serum prolactin concentration. Gel filtration chromatography (GFC) is currently the gold standard method for separating macroprolactin, but is labour-intensive. Polyethylene glycol (PEG) precipitation is suitable for routine use but may not always be accurate. We developed a high pressure liquid chromatography (HPLC) assay for macroprolactin measurement. Chromatography was carried out using an Agilent Zorbax GF-250 (9.4 × 250 mm, 4 μm) size exclusion column and 50 mmol/L Tris buffer with 0.15 mmol/L NaCl at pH 7.2 as mobile phase, with a flow rate of 1 mL/min. Serum or plasma was diluted 1:1 with mobile phase and filtered and 100 μL injected. Fractions of 155 μL were collected for prolactin measurement and elution profile plotted. The area under the curve of each prolactin peak was calculated to quantify each prolactin form, and compared with GFC. Clear separation of monomeric-, big- and macroprolactin forms was achieved. Quantification was comparable to GFC and precision was acceptable. Total time from injection to collection of the final fraction was 16 min. We have developed an HPLC method for quantification of macroprolactin, which is rapid and easy to perform and therefore can be used for routine measurement.

Confirmation of diosmetin 3-O-glucuronide as major metabolite of diosmin in humans, using micro-liquid-chromatography-mass spectrometry and ion mobility mass spectrometry.

PubMed

Silvestro, Luigi; Tarcomnicu, Isabela; Dulea, Constanta; Attili, Nageswara Rao B N; Ciuca, Valentin; Peru, Dan; Rizea Savu, Simona

2013-10-01

Diosmin is a flavonoid often administered in the treatment of chronic venous insufficiency, hemorrhoids, and related affections. Diosmin is rapidly hydrolized in the intestine to its aglicone, diosmetin, which is further metabolized to conjugates. In this study, the development and validations of three new methods for the determination of diosmetin, free and after enzymatic deconjugation, and of its potential glucuronide metabolites, diosmetin-3-O-glucuronide, diosmetin-7-O-glucuronide, and diosmetin-3,7-O-glucuronide from human plasma and urine are presented. First, the quantification of diosmetin, free and after deconjugation, was carried out by high-performance liquid chromatography coupled with tandem mass spectrometry, on an Ascentis RP-Amide column (150 × 2.1 mm, 5 μm), in reversed-phase conditions, after enzymatic digestion. Then glucuronide metabolites from plasma were separated by micro-liquid chromatography coupled with tandem mass spectrometry on a HALO C18 (50 × 0.3 mm, 2.7 μm, 90 Å) column, after solid-phase extraction. Finally, glucuronides from urine were measured using a Discovery HSF5 (100 × 2.1 mm, 5 μm) column, after simple dilution with mobile phase. The methods were validated by assessing linearity, accuracy, precision, low limit of quantification, selectivity, extraction recovery, stability, and matrix effects; results in agreement with regulatory (Food and Drug Administration and European Medicines Agency) guidelines acceptance criteria were obtained in all cases. The methods were applied to a pharmacokinetic study with diosmin (450 mg orally administered tablets). The mean C max of diosmetin in plasma was 6,049.3 ± 5,548.6 pg/mL. A very good correlation between measured diosmetin and glucuronide metabolites concentrations was obtained. Diosmetin-3-O-glucuronide was identified as a major circulating metabolite of diosmetin in plasma and in urine, and this finding was confirmed by supplementary experiments with differential ion-mobility mass spectrometry.

Quantification of astaxanthin in shrimp waste hydrolysate by HPLC.

PubMed

López-Cervantes, J; Sánchez-Machado, D I; Gutiérrez-Coronado, M A; Ríos-Vázquez, N J

2006-10-01

In the present study, a simple and rapid reversed-phase HPLC method for the determination of astaxanthin in shrimp waste hydrolysate has been developed and validated. The analytical procedure involves the direct extraction of astaxanthin from the lipid fraction with methanol. The analytical column, SS Exil ODS, was operated at 25C. The mobile phase consisted of a mixture of water:methanol:dichloromethane:acetonitrile (4.5:28:22:45.5 v/v/v/v) at a flow rate of 1.0 mL/min. Detection and identification were performed using a photodiode array detector (lambda(detection) = 476 nm). The proposed HPLC method showed adequate linearity, repeatability and accuracy.

Simultaneous quantification of withanolides in Withania somnifera by a validated high-performance thin-layer chromatographic method.

PubMed

Srivastava, Pooja; Tiwari, Neerja; Yadav, Akhilesh K; Kumar, Vijendra; Shanker, Karuna; Verma, Ram K; Gupta, Madan M; Gupta, Anil K; Khanuja, Suman P S

2008-01-01

This paper describes a sensitive, selective, specific, robust, and validated densitometric high-performance thin-layer chromatographic (HPTLC) method for the simultaneous determination of 3 key withanolides, namely, withaferin-A, 12-deoxywithastramonolide, and withanolide-A, in Ashwagandha (Withania somnifera) plant samples. The separation was performed on aluminum-backed silica gel 60F254 HPTLC plates using dichloromethane-methanol-acetone-diethyl ether (15 + 1 + 1 + 1, v/v/v/v) as the mobile phase. The withanolides were quantified by densitometry in the reflection/absorption mode at 230 nm. Precise and accurate quantification could be performed in the linear working concentration range of 66-330 ng/band with good correlation (r2 = 0.997, 0.999, and 0.996, respectively). The method was validated for recovery, precision, accuracy, robustness, limit of detection, limit of quantitation, and specificity according to International Conference on Harmonization guidelines. Specificity of quantification was confirmed using retention factor (Rf) values, UV-Vis spectral correlation, and electrospray ionization mass spectra of marker compounds in sample tracks.

A HPLC method for the quantification of butyramide and acetamide at ppb levels in hydrogeothermal waters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gracy Elias; Earl D. Mattson; Jessica E. Little

A quantitative analytical method to determine butyramide and acetamide concentrations at the low ppb levels in geothermal waters has been developed. The analytes are concentrated in a preparation step by evaporation and analyzed using HPLC-UV. Chromatographic separation is achieved isocratically with a RP C-18 column using a 30 mM phosphate buffer solution with 5 mM heptane sulfonic acid and methanol (98:2 ratio) as the mobile phase. Absorbance is measured at 200 nm. The limit of detection (LOD) for BA and AA were 2.0 {mu}g L{sup -1} and 2.5 {mu}g L{sup -1}, respectively. The limit of quantification (LOQ) for BA andmore » AA were 5.7 {mu}g L{sup -1} and 7.7 {mu}g L{sup -1}, respectively, at the detection wavelength of 200 nm. Attaining these levels of quantification better allows these amides to be used as thermally reactive tracers in low-temperature hydrogeothermal systems.« less

Occurrence of ivermectin in bovine milk from the Brazilian retail market.

PubMed

Lobato, V; Rath, S; Reyes, F G R

2006-07-01

High-performance liquid chromatography (HPLC) with fluorescence detection was used for the quantification of ivermectin residues in bovine milk intended for human consumption. After liquid-liquid extraction of ivermectin and purification of the extract, the compound was derivatized with 1-methylimidazol in N,N-dimethyl formamide to form a fluorescent derivative, which was separated by HPLC, using reversed-phase C18, with methanol : water (96 : 4 v/v) mobile phase at a flow rate 0.7 ml min-1. The excitation and emission wavelengths of the fluorescence detector were adjusted at 360 and 470 nm, respectively. The linearity of the method was in the range 10-100 ng ivermectin ml-1. Based on a sample of 5.0 ml, the limit of detection and the limit of quantification for ivermectin in milk were 0.6 and 2 ng ml-1, respectively. The recovery rate varied from 76.4 to 87.2%, with an average of 77.9 +/- 3.2%, at four fortification levels. The inter-day precision of the method was 13% (n = 5). Of 168 samples analysed, 17.8% contained ivermectin above the limit of quantification. Nevertheless, none of the samples contained ivermectin above the maximum residue limit (10 ng ml-1) established by the Brazilian Ministry of Agriculture.

Electrochemical characterization of repaglinide and its determination in human plasma using liquid chromatography with dual-channel coulometric detection.

PubMed

Jirovský, David; Bartošová, Zdenka; Skopalová, Jana; Maier, Vítezslav

2010-12-01

A simple, fast and sensitive HPLC method employing dual-channel coulometric detection for the determination of repaglinide in human plasma is presented. The assay involved extraction of repaglinide by ethyl acetate and isocratic reversed-phase liquid chromatography with dual-channel coulometric detection. The mobile phase composition was 50mM disodium hydrogen phosphate/acetonitrile (60:40, v/v), pH of the mobile phase 7.5 set up with phosphoric acid. For all analyses, the first cell working potential was +380mV, the second was +750mV (vs. Pd/H(2)). Calibration curve was linear over the concentration range of 5-500nmolL(-1). Rosiglitazone was used as an internal standard. The limit of detection (LOD) was established at 2.8nmolL(-1), and the lower limit of quantification (LLOQ) at 8.5nmolL(-1). The developed method was applied to human plasma samples spiked with repaglinide at therapeutical concentrations. It was confirmed that the method is suitable for pharmacokinetic studies or therapeutic monitoring. Copyright © 2010 Elsevier B.V. All rights reserved.

A direct HPLC method for the resolution and quantitation of the R-(-)- and S-(+)-enantiomers of vigabatrin (gamma-vinyl-GABA) in pharmaceutical dosage forms using teicoplanin aglycone chiral stationary phase.

PubMed

Al-Majed, Abdulrahman A

2009-08-15

A direct chiral high-performance liquid chromatography (HPLC) method was developed and validated for the resolution and quantification of antiepileptic drug enantiomers, R-(-)- and S-(+)-vigabatrin (gamma-vinyl-gamma-aminobutyric acid) in pharmaceutical products. The separation was optimized on a macrocyclic glycopeptide antibiotic chiral stationary phase (CSP) based on teicoplanin aglycone, chirobiotic (TAG), using a mobile phase system containing ethanol-water (80:20, v/v), at a flow rate of 0.4ml/min and UV detection set at 210nm. The stability of vigabatrin enantiomers under different degrees of temperature was also studied. The enantiomers of vigabatrin were separated from each other. The calibration curves were linear over a range of 100-1600microg/ml (r=0.999) for both enantiomers. The overall recoveries of R-(-)- and S-(+)-vigabatrin enantiomers from pharmaceutical products were in the range of 98.3-99.8% with %RSD ranged from 0.48 to 0.52%. The limit of quantification (LOQ) and limit of detection (LOD) for each enantiomer were 100 and 25microg/ml, respectively. No interferences were found from commonly co-formulated excipients.

Quantification of melamine in drinking water and wastewater by micellar liquid chromatography.

PubMed

Beltrán-Martinavarro, Beatriz; Peris-Vicente, Juan; Rambla-Alegre, Maria; Marco-Peiró, Sergio; Esteve-Romero, Josep; Carda-Broch, Samuel

2013-01-01

Because of the large potential health impact caused by deliberate contamination with the synthetic chemical melamine of different products for human and animal consumption, the World Health Organization and the Food and Agriculture Organization of the United Nations provided a range of recommendations in order to facilitate obtaining needed data, among which was the determination of the background levels of melamine in drinking water and wastewater (December 4, 2008). A chromatographic procedure using a C18 column, a micellar mobile phase consisting of sodium dodecyl sulfate (0.1 M), and 1-propanol (7.5%) buffered at pH 3, and detection by absorbance at 210 nm is reported in this paper for the quantification of melamine in drinking water and wastewater. Samples were filtered and directly injected into the chromatographic system, thus avoiding an extraction procedure. The optimal mobile phase composition was obtained by a chemometrics approach that considered the retention factor, efficiency, and peak shape. Melamine was eluted in about 6.2 min without interferences. Validation was performed following U.S. Food and Drug Administration guidelines. The analytical parameters studied were linearity (0.03-5 microg/mL, R2 = 0.998), LOD (13 nglmL), intraday and interday accuracy (between 4.1 and 12.2%), intraday and interday precision (less than 14.8%), and robustness (RSD < 5.1% for retention time and <9.0% for area). The proposed methodology was successfully applied for analysis of local wastewater and drinking water, in which no melamine was found.

Rapid and sensitive ultra-high-pressure liquid chromatography method for quantification of antichagasic benznidazole in plasma: application in a preclinical pharmacokinetic study.

PubMed

Davanço, Marcelo Gomes; de Campos, Michel Leandro; Peccinini, Rosângela Gonçalves

2015-07-01

Benznidazole (BNZ) and nifurtimox are the only drugs available for treating Chagas disease. In this work, we validated a bioanalytical method for the quantification of BNZ in plasma aimed at improving sensitivity and time of analysis compared with the assays already published. Furthermore, we demonstrated the application of the method in a preclinical pharmacokinetic study after administration of a single oral dose of BNZ in Wistar rats. A Waters® Acquity UHPLC system equipped with a UV-vis detector was employed. The method was established using an Acquity® UHPLC HSS SB C18 protected by an Acquity® UHPLC HSS SB C18 VanGuard guard column and detection at 324 nm. The mobile phase consisted of ultrapure water-acetonitrile (65:35), and elution was isocratic. The mobile phase flow rate was 0.55 mL/min, the volume of injection was 1 μL, and the run time was just 2 min. The samples were kept at 25°C until injection and the column at 45°C for the chromatographic separation. The sample preparation was performed by a rapid protein precipitation with acetonitrile. The linear concentration range was 0.15-20 µg/mL. The pharmacokinetic parameters of BNZ in rats were determined and the method was considered sensitive, fast and suitable for application in pharmacokinetic studies. Copyright © 2014 John Wiley & Sons, Ltd.

Rapid ion-pair liquid chromatographic method for the determination of fenbendazole marker residue in fermented dairy products.

PubMed

Vousdouka, Venetia I; Papapanagiotou, Elias P; Angelidis, Apostolos S; Fletouris, Dimitrios J

2017-04-15

A simple, rapid and sensitive liquid chromatographic method that allows for the quantitative determination of fenbendazole residues in fermented dairy products is described. Samples were extracted with a mixture of acetonitrile-phosphoric acid and the extracts were defatted with hexane to be further partitioned into ethyl acetate. The organic layer was evaporated to dryness and the residue was reconstituted in mobile phase. Separation of fenbendazole and its sulphoxide, sulphone, and p-hydroxylated metabolites was carried out isocratically with a mobile phase containing both positively and negatively charged pairing ions. Overall recoveries ranged from 79.8 to 88.8%, while precision data, based on within and between days variations, suggested an overall relative standard deviation of 6.3-11.0%. The detection and quantification limits were lower than 9 and 21μg/kg, respectively. The method has been successfully applied to quantitate fenbendazole residues in Feta cheese and yoghurt made from spiked and incurred ovine milk. Copyright © 2016 Elsevier Ltd. All rights reserved.

Simultaneous Determination of Potassium Sorbate, Sodium Benzoate, Quinoline Yellow and Sunset Yellow in Lemonades and Lemon Sauces by HPLC Using Experimental Design.

PubMed

Dinç Zor, Şule; Aşçı, Bürge; Aksu Dönmez, Özlem; Yıldırım Küçükkaraca, Dilek

2016-07-01

In this study, development and validation of a HPLC method was described for simultaneous determination of potassium sorbate, sodium benzoate, quinoline yellow and sunset yellow. A Box-Behnken design using three variables at three levels was employed to determine the optimum conditions of chromatographic separation: pH of mobile phase, 6.0-7.0; flow rate, 0.8-1.2 mL min(-1) and the ratio of mobile phase composed of a 0.025 M sodium acetate/acetic acid buffer, 80-90%. Resolution was chosen as a response. The optimized method was validated for linearity, the limits of detection and quantification, accuracy, precision and stability. All the validation parameters were within the acceptance range. The applicability of the developed method to the determination of these food additives in commercial lemonade and lemon sauce samples was successfully demonstrated. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Analysis of iodinated quorum sensing peptides by LC-UV/ESI ion trap mass spectrometry.

PubMed

Janssens, Yorick; Verbeke, Frederick; Debunne, Nathan; Wynendaele, Evelien; Peremans, Kathelijne; De Spiegeleer, Bart

2018-02-01

Five different quorum sensing peptides (QSP) were iodinated using different iodination techniques. These iodinated peptides were analyzed using a C 18 reversed phase HPLC system, applying a linear gradient of water and acetonitrile containing 0.1% (m/v) formic acid as mobile phase. Electrospray ionization (ESI) ion trap mass spectrometry was used for the identification of the modified peptides, while semi-quantification was performed using total ion current (TIC) spectra. Non-iodinated peptides and mono- and di-iodinated peptides (NIP, MIP and DIP respectively) were well separated and eluted in that order. Depending on the used iodination method, iodination yields varied from low (2%) to high (57%).

A validated chiral liquid chromatographic method for the enantiomeric separation of safinamide mesilate, a new anti-Parkinson drug.

PubMed

Zhang, Kai; Xue, Na; Shi, Xiaowei; Liu, Weina; Meng, Jing; Du, Yumin

2011-04-28

A enantioselective reversed-phase high performance liquid chromatographic method was developed for the enantiomeric resolution of safinamide mesilate, 2(S)-[4-(3-fluorobenzyloxy)benzylamino] propionamide methanesulfonate, a neuroprotectant with antiparkinsonian and anticonvulsant activity for the treatment of Parkinson disease. The enantiomers of safinamide mesilate were baseline resolved on a Chiralcel OD-RH (150mm×4.6mm, 5μm) column using a mobile phase system containing 300mM sodium di-hydrogen phosphate buffer (pH 3.0):methanol:acetonitrile (65:25:10, v/v/v). The resolution between the enantiomers was not less than 3.0. The pH value of buffer solution in the mobile phase has played a key role in enhancing chromatographic efficiency and resolution between the enantiomers. The developed method was validated and proved to be robust. The limit of detection and limit of quantification of (R)-enantiomer were found to be 15 and 50ng/mL, respectively, for 20μL injection volume. The percentage recovery of (R)-enantiomer was ranged from 94.2 to 103.7 in bulk drug samples of safinamide mesilate. The sample solution and mobile phase were found to be stable at least for 48h. The final optimized method was successfully applied to separate (R)-enantiomer from safinamide mesilate and was proven to be reproducible and accurate for the quantitative determination of (R)-enantiomer in bulk drugs. Copyright © 2010 Elsevier B.V. All rights reserved.

Rapid Isocratic Liquid Chromatographic Separation and Quantification of Tryptophan and Six kynurenine Metabolites in Biological Samples with Ultraviolet and Fluorimetric Detection

PubMed Central

Badawy, Abdulla A-B; Morgan, Christopher J

2010-01-01

A simple, rapid isocratic liquid chromatographic procedure with ultraviolet and fluorimetric detection is described for the separation and quantification of L-tryptophan (Trp) and six of its kynurenine metabolites (kynurenine, 3-hydroxykynurenine, and 3-hydroxyanthranilic, kynurenic, xanthurenic and anthranilic acids). Using the Perkin Elmer LC 200 system, a reverse phase Synergi 4 μ fusion-RP80 A column (250 × 4.6 mm) (Phenomenex), and a mobile phase of 10 mM sodium dihydrogen phosphate: methanol (73:27, by vol) at pH 2.8 and a flow rate of 1.0–1.2 ml/min at 37 °C, a run took ∼13 min. The run took <7 min at 40 °C and a 1.4 ml/min flow rate. Limits of detection of all 7 analytes were 5–72 nM and their recoveries from human plasma and rat serum and liver varied between 62% and 111%. This simple method is suitable for high throughput work and can be further developed to include quinolinic acid and other Trp metabolites. PMID:22084598

Fast analysis of capsaicinoids in Naga Jolokia extracts (Capsicum chinense) by high-performance liquid chromatography using fused core columns.

PubMed

Stipcovich, Tea; Barbero, Gerardo F; Ferreiro-González, Marta; Palma, Miguel; Barroso, Carmelo G

2018-01-15

A rapid high-performance liquid chromatography method with a C18 reverse-phase fused-core column has been developed for the determination and quantification of the main capsaicinoids (nornordihydrocapsaicin, nordihydrocapsaicin, capsaicin, dihydrocapsaicin, homocapsaicin and homodihydrocapsaicin) present in Naga Jolokia peppers. A fused-core Kinetex™ C18 column (50×2.1mm i.d.; 2.6μm) was used for the analysis. The chromatographic separation was obtained with a gradient method in which the mobile phase was water (0.1% acetic acid) as solvent A and acetonitrile (0.1% acetic acid) as solvent B. The separation of all compounds was achieved in less than 3min with a total analysis time (sample-to-sample) of 10min. The robustness of the method was evaluated. The method showed excellent repeatability and intermediate precision expressed as coefficient of variance of less than 2%. The developed method was employed for the quantification of the major capsaicinoids present in different peppers and commercial products containing chilli peppers. Copyright © 2017 Elsevier Ltd. All rights reserved.

Development of a sensitive high-performance liquid chromatographic method with simple extraction for simultaneous determination of huperzine A and huperzine B in the species containing lycopodium alkaloids.

PubMed

Zhang, Yanqing; Xie, Junbo; Chen, Wen-Qian; Zhou, Tian-Yan; Lu, Wei

2009-01-01

A sensitive HPLC method with simple extraction was developed for simultaneous determination of huperzine A (HupA) and huperzine B (HupB) in Huperzia serrata, H. crispata, H. miyoshiana, and Lycopodiastrum casuarinoides. In order to avoid conventional multiple-step and time-consuming sample preparation methods, direct reflux extraction with alkaline chloroform was adopted. The quantitative determination was conducted by reversed-phase HPLC with a photodiode array detector set at 308 nm. Separation was performed on a Luna C18 column (250 x 4.6 mm id, 5 microm) with methanol-0.2% aqueous acetic acid (18 + 82, v/v) mobile phase. The method was validated for accuracy, reproducibility, precision, and limits of detection and quantification. Quantification of the two active compounds in the samples was performed by this newly developed method, and the content of HupA and HupB varied substantially among four different species. The satisfactory results indicated that the developed method can readily be utilized for quality control of the species of Huperziaceae and Lycopodiaceae containing the two compounds.

An Improved LC-MS/MS Method for Simultaneous Determination of the Eleven Bioactive Constituents for Quality Control of Radix Angelicae Pubescentis and Its Related Preparations

PubMed Central

Li, Jin; Zhang, Qiu-Hong; He, Jun; Liu, Er-wei; Gao, Xiu-mei; Chang, Yan-xu

2015-01-01

An improved LC-MS/MS method was developed for simultaneous determination of eleven bioactive constituents of Radix Angelicae Pubescentis and its related preparations. It was the first report on the quantification of bioactive constituents in different preparations of Radix Angelicae Pubescentis by LC-MS/MS analytical method. These samples were separated with an Agilent Zorbax Extend reversed-phase C18 column (1.8 μm, 4.6 × 100 mm) by linear gradient elution using aqueous ammonium acetate and acetonitrile as mobile phase. The flow rate was 0.3 mL min−1. The eleven bioactive constituents showed good regression (R > 0.990) within test ranges and the recoveries were in the range of 87.1–110%. The limit of detections and quantifications for most of the major constituents were less than 0.5 and 1.0 ng mL−1, respectively. All results indicated that the developed method could be readily utilized as a suitable quality control method for Radix Angelicae Pubescentis and related preparations. PMID:26078992

Ultra-Performance Liquid Chromatographic Determination of Tocopherols and Retinol in Human Plasma

PubMed Central

Bell, Edward C.; John, Mathew; Hughes, Rodney J.; Pham, Thu

2014-01-01

A rapid, selective and sensitive ultra-performance liquid chromatography method has been developed for the detection and quantification of tocopherols and retinol in human plasma. Alpha-tocopherol, gamma-tocopherol and retinol are assayed using fluorescence detection. Excitation/emission wavelengths are 295/330 nm and 325/470 nm for the analysis of both tocopherols and retinol, respectively. Retinol acetate is employed as the internal standard. The reversed-phase method incorporates gradient elution with a mobile phase consisting of methanol and acetonitrile. Separation of vitamin compounds is achieved using a bridged ethyl hybrid C18 column. The retention times for retinol, retinol acetate, gamma-tocopherol and alpha-tocopherol are 1.6, 1.8, 3.9 and 4.3 min, respectively. The limits of quantification for retinol, gamma-tocopherol and alpha-tocopherol were 0.02, 0.02 and 0.1 µg/mL, respectively. The assay method is suitable for the analysis of tocopherols and retinol in human plasma. The method may be applied following the ingestion of foods fortified with these fat-soluble vitamins. PMID:24170122

A Simple RP-HPLC Method for Quantitation of Itopride HCl in Tablet Dosage Form.

PubMed

Thiruvengada, Rajan Vs; Mohamed, Saleem Ts; Ramkanth, S; Alagusundaram, M; Ganaprakash, K; Madhusudhana, Chetty C

2010-10-01

An isocratic reversed phase high-performance liquid chromatographic method with ultraviolet detection at 220 nm has been developed for the quantification of itopride hydrochloride in tablet dosage form. The quantification was carried out using C(8) column (250 mm × 4.6 mm), 5-μm particle size SS column. The mobile phase comprised of two solvents (Solvent A: buffer 1.4 mL ortho-phosphoric acid adjusted to pH 3.0 with triethyl amine and Solvent B: acetonitrile). The ratio of Solvent A: Solvent B was 75:25 v/v. The flow rate was 1.0 mL (-1)with UV detection at 220 nm. The method has been validated and proved to be robust. The calibration curve was linear in the concentration range of 80-120% with coefficient of correlation 0.9995. The percentage recovery for itopride HCl was 100.01%. The proposed method was validated for its selectivity, linearity, accuracy, and precision. The method was found to be suitable for the quality control of itopride HCl in tablet dosage formulation.

A Simple RP-HPLC Method for Quantitation of Itopride HCl in Tablet Dosage Form

PubMed Central

Thiruvengada, Rajan VS; Mohamed, Saleem TS; Ramkanth, S; Alagusundaram, M; Ganaprakash, K; Madhusudhana, Chetty C

2010-01-01

An isocratic reversed phase high-performance liquid chromatographic method with ultraviolet detection at 220 nm has been developed for the quantification of itopride hydrochloride in tablet dosage form. The quantification was carried out using C8 column (250 mm × 4.6 mm), 5-μm particle size SS column. The mobile phase comprised of two solvents (Solvent A: buffer 1.4 mL ortho-phosphoric acid adjusted to pH 3.0 with triethyl amine and Solvent B: acetonitrile). The ratio of Solvent A: Solvent B was 75:25 v/v. The flow rate was 1.0 mL -1with UV detection at 220 nm. The method has been validated and proved to be robust. The calibration curve was linear in the concentration range of 80-120% with coefficient of correlation 0.9995. The percentage recovery for itopride HCl was 100.01%. The proposed method was validated for its selectivity, linearity, accuracy, and precision. The method was found to be suitable for the quality control of itopride HCl in tablet dosage formulation. PMID:21264104

Highly sensitive and simple liquid chromatography assay with ion-pairing extraction and visible detection for quantification of gold from nanoparticles.

PubMed

Pallotta, Arnaud; Philippe, Valentin; Boudier, Ariane; Leroy, Pierre; Clarot, Igor

2018-03-01

A simple isocratic HPLC method using visible detection was developed and validated for the quantification of gold in nanoparticles (AuNP). After a first step of oxidation of nanoparticles, an ion-pair between tetrachloroaurate anion and the cationic dye Rhodamine B was formed and extracted from the aqueous media with the help of an organic solvent. The corresponding Rhodamine B was finally quantified by reversed phase liquid chromatography using a Nucleosil C18 (150mm × 4.6mm, 3µm) column and with a mobile phase containing acetonitrile and 0.1% trifluoroacetic acid aqueous solution (25/75, V/V) at 1.0mLmin -1. and at a wavelength of 555nm. The method was validated using methodology described by the International Conference on Harmonization and was shown to be specific, precise (RSD < 11%), accurate and linear in the range of 0.1 - 30.0µM with a lower limit of quantification (LLOQ) of 0.1µM. This method was in a first time applied to AuNP quality control after their synthesis. In a second time, the absence of gold leakage (either as AuNP or gold salt form) from nanostructured multilayered polyelectrolyte films under shear stress was assessed. Copyright © 2017 Elsevier B.V. All rights reserved.

Simultaneous quantification of fentanyl, sufentanil, cefazolin, doxapram and keto-doxapram in plasma using liquid chromatography - tandem mass spectrometry.

PubMed

Flint, Robert B; Bahmany, Soma; van der Nagel, Bart C H; Koch, Birgit C P

2018-05-16

A simple and specific UPLC-MS/MS method was developed and validated for simultaneous quantification of fentanyl, sufentanil, cefazolin, doxapram and its active metabolite keto-doxapram. The internal standard was fentanyl-d5 for all analytes. Chromatographic separation was achieved with a reversed phase Acquity UPLC HSS T3 column with a run-time of only 5.0 minutes per injected sample. Gradient elution was performed with a mobile phase consisting of ammonium acetate, formic acid in Milli-Q ultrapure water or in methanol with a total flow rate of 0.4 mL minute -1 . A plasma volume of only 50 μL was required to achieve both adequate accuracy and precision. Calibration curves of all 5 analytes were linear. All analytes were stable for at least 48 hours in the autosampler. The method was validated according to US Food and Drug Administration guidelines. This method allows quantification of fentanyl, sufentanil, cefazolin, doxapram and keto-doxapram, which serves purposes for research, as well as therapeutic drug monitoring, if applicable. The strength of this method is the combination of a small sample volume, a short run-time, a deuterated internal standard, an easy sample preparation method and the ability to simultaneously quantify all analytes in one run. This article is protected by copyright. All rights reserved.

Analysis of tricyclic antidepressant drugs in plasma by means of solid-phase microextraction-liquid chromatography-mass spectrometry.

PubMed

Alves, Claudete; Santos-Neto, Alvaro J; Fernandes, Christian; Rodrigues, José C; Lanças, Fernando M

2007-10-01

Solid-phase microextraction coupled to liquid chromatography and mass spectrometry (SPME-LC-MS) was used to analyze tricyclic antidepressant drugs desipramine, imipramine, nortriptyline, amitriptyline, and clomipramine (internal standard) in plasma samples. SPME was performed by direct extraction on a PDMS/DVB (60 microm) coated fiber, employing a stirring rate of 1200 rpm for 30 min, pH 11.0, and temperature of 30 degrees C. Drug desorption was carried out by exposing the fiber to the liquid chromatography mobile phase for 20 min, using a labmade SPME-LC interface at 50 degrees C. The main variables experimentally influencing LC-MS response were evaluated and mathematically modeled. A rational optimization with fewer experiments was achieved using a factorial design approach. The constructed empirical models were adjusted with 96-98% of explained deviation allowing an adequate data set comprehension. The chromatographic separation was realized using an RP-18 column (150 mm x 2.1 mm, 5 microm particles) and ammonium acetate buffer (0.01 mol/l, pH 5.50) : acetonitrile (50 : 50 v/v) as mobile phase. Low detection levels were achieved with electrospray interface (0.1 ng/ml). The developed method showed specificity, linearity, precision, and limit of quantification adequate to assay tricyclic antidepressant drugs in plasma.

Validation of an electrospray ionisation LC-MS/MS method for quantitative analysis of telaprevir and its R-diastereomer.

PubMed

Penchala, Sujan Dilly; Tjia, John; El Sherif, Omar; Back, David J; Khoo, Saye H; Else, Laura J

2013-08-01

A sensitive high-performance reverse phase liquid chromatography-positive ion electrospray tandem mass spectrometry method was developed and validated for the quantification of telaprevir and its inactive R-diastereomer (VRT-127394) in human plasma. The analytes and the internal standard (telaprevir-d11) were extracted from plasma by liquid-liquid extraction using tert-Butyl methyl ether (TBME). Chromatographic separation was achieved on a reversed-phase Accucore C18 column with a gradient programme consisting of water:ammonia (25%), 100:0.01 (v/v) (mobile phase A) and ACN:MeOH:ammonia (25%), 15:85:0.01 (v/v/v) (mobile phase B). The MS acquisition was performed with selective reaction monitoring mode using the respective [M+H](+) ions, m/z 680.59→322.42 for telaprevir and VRT-127394, and 691.15→110.13 for telaprevir-d11. The assay exhibited a linear dynamic range of 5-5000ng/mL for telaprevir and VRT-127394. Acceptable precision (%RSD<6.5%) and accuracy (94-108%) were obtained for concentrations over the range of the standard curve. A procedure was established to stabilise the plasma to prevent ex vivo interconversion of the isomers. Copyright © 2013 Elsevier B.V. All rights reserved.

Multiresidue analysis of sulfonamides, quinolones, and tetracyclines in animal tissues by ultra-high performance liquid chromatography-tandem mass spectrometry.

PubMed

Zhang, Zhiwen; Li, Xiaowei; Ding, Shuangyang; Jiang, Haiyang; Shen, Jianzhong; Xia, Xi

2016-08-01

A multiresidue method for the efficient identification and quantification of 38 compounds from 3 different classes of antibiotics (tetracyclines, sulfonamides, and quinolones) in animal tissues has been developed. The method optimization involved the selection of extraction solutions, comparison of different solid-phase extraction cartridges and different mobile phases. As a result, the samples were extracted with Mcllvaine and phosphate buffers, followed by clean-up step based on solid-phase extraction with Oasis HLB cartridge. All compounds were determined by ultra-high performance liquid chromatography-tandem mass spectrometry, in one single injection with a chromatographic run time of only 9min. The method efficiency was evaluated in 5 tissues including muscle, liver, and kidney, and the mean recoveries ranged from 54% to 102%, with inter-day relative standard deviation lower than 14%. The limits of quantification were between 0.5 and 10μg/kg, which were satisfactory to support future surveillance monitoring. The developed method was applied to the analysis of swine liver and chicken samples from local markets, and sulfamethazine was the most commonly detected compound in the animal samples, with the highest residue level of 998μg/kg. Copyright © 2016 Elsevier Ltd. All rights reserved.

Chiral liquid chromatography-mass spectrometry (LC-MS/MS) method development for the detection of salbutamol in urine samples.

PubMed

Chan, Sue Hay; Lee, Warren; Asmawi, Mohd Zaini; Tan, Soo Choon

2016-07-01

A sequential solid-phase extraction (SPE) method was developed and validated using liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) for the detection and quantification of salbutamol enantiomers in porcine urine. Porcine urine samples were hydrolysed with β-glucuronidase/arylsulfatase from Helix pomatia and then subjected to a double solid-phase extraction (SPE) first using the Abs-Elut Nexus SPE and then followed by the Bond Elut Phenylboronic Acid (PBA) SPE. The salbutamol enantiomers were separated using the Astec CHIROBIOTIC™ T HPLC column (3.0mm×100mm; 5μm) maintained at 15°C with a 15min isocratic run at a flow rate of 0.4mL/min. The mobile phase constituted of 5mM ammonium formate in methanol. Salbutamol and salbutamol-tert-butyl-d9 (internal standard, IS) was monitored and quantified with the multiple reaction monitoring (MRM) mode. The method showed good linearity for the range of 0.1-10ng/mL with limit of quantification at 0.3ng/mL. Analysis of the QC samples showed intra- and inter-assay precisions to be less than 5.04%, and recovery ranging from 83.82 to 102.33%. Copyright © 2016 Elsevier B.V. All rights reserved.

Characterization and simultaneous quantification of biological aporphine alkaloids in Litsea cubeba by HPLC with hybrid ion trap time-of-flight mass spectrometry and HPLC with diode array detection.

PubMed

Zhang, Shuiying; Zhang, Qian; Guo, Qiang; Zhao, Yunfang; Gao, Xiaoli; Chai, Xingyun; Tu, Pengfei

2015-08-01

The root and rhizome of Litsea cubeba (Lour) Pers., named 'Dou-chi-jiang' in Chinese, has been traditionally used for treatment of cardiovascular and cerebrovascular diseases, rheumatic arthralgia, and other diseases in China. Aporphine alkaloids are its characteristic ingredients and responsible for its bioactivities, especially anti-inflammatory and analgesic effects. A sensitive and reliable high-performance liquid chromatography with diode array detection-tandem mass spectrometry method was developed for characterization and simultaneous determination of biological aporphine alkaloids in 'Dou-chi-jiang'. The optimized chromatographic conditions were performed on an Eclipse XDB C18 column with a gradient of acetonitrile/water containing 0.1% formic acid as the mass spectrometry mobile phase and acetonitrile/water containing 0.2% diethylamine (pH 3.10, adjusted by acetic acid) as the liquid chromatography mobile phase. The fragmentation pathways by loss of CO, ·CH3 , ·NH3 , and ·NH2 CH3 were detected as characteristic for aporphine alkaloids. Based on these characteristics, total 12 analogues were identified. The quantification method was validated in terms of linearity, precision, and accuracy for six major aporphine alkaloids, which was successfully applied for simultaneous determination in ten batches of samples. The established method is simple, rapid, and specific for characterization and quantitation of aporphine alkaloids in 'Dou-chi-jiang' and other traditional Chinese medicines rich in this kind of ingredient. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Second-tier test for quantification of underivatized amino acids in dry blood spot for metabolic diseases in newborn screening.

PubMed

Wang, Chunyan; Zhu, Hongbin; Zhang, Wenyan; Song, Fengrui; Liu, Zhiqiang; Liu, Shuying

2013-02-01

The quantitative analysis of amino acids (AAs) in single dry blood spot (DBS) samples is an important issue for metabolic diseases as a second-tier test in newborn screening. An analytical method for quantifying underivatized AAs in DBS was developed by using liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). The sample preparation in this method is simple and ion-pairing agent is not used in the mobile phase that could avoid ion suppression, which happens in mass spectrometry and avoids damage to the column. Through chromatographic separation, some isomeric compounds could be identified and quantified, which cannot be solved through only appropriate multiple reactions monitoring transitions by MS/MS. The concentrations of the different AAs were determined using non-deuterated internal standard. All calibration curves showed excellent linearity within test ranges. For most of the amino acids the accuracy of extraction recovery was between 85.3 and 115 %, and the precision of relative standard deviation was <7.0 %. The 35 AAs could be identified in DBS specimens by the developed LC-MS/MS method in 17-19 min, and eventually 24 AAs in DBS were quantified. The results of the present study prove that this method as a second-tier test in newborn screening for metabolic diseases could be performed by the quantification of free AAs in DBS using the LC-MS/MS method. The assay has advantages of high sensitive, specific, and inexpensive merits because non-deuterated internal standard and acetic acid instead of ion-pairing agent in mobile phase are used in this protocol.

Development and validation of an LC-ESI-MS/MS method for the quantification of D-84, reboxetine and citalopram for their use in MS Binding Assays addressing the monoamine transporters hDAT, hSERT and hNET.

PubMed

Neiens, Patrick; De Simone, Angela; Ramershoven, Anna; Höfner, Georg; Allmendinger, Lars; Wanner, Klaus T

2018-03-03

MS Binding Assays represent a label-free alternative to radioligand binding assays. In this study, we present an LC-ESI-MS/MS method for the quantification of (R,R)-4-(2-benzhydryloxyethyl)-1-(4-fluorobenzyl)piperidin-3-ol [(R,R)-D-84, (R,R)-1], (S,S)-reboxetine [(S,S)-2], and (S)-citalopram [(S)-3] employed as highly selective nonlabeled reporter ligands in MS Binding Assays addressing the dopamine [DAT, (R,R)-D-84], norepinephrine [NET, (S,S)-reboxetine] and serotonin transporter [SERT, (S)-citalopram], respectively. The developed LC-ESI-MS/MS method uses a pentafluorphenyl stationary phase in combination with a mobile phase composed of acetonitrile and ammonium formate buffer for chromatography and a triple quadrupole mass spectrometer in the multiple reaction monitoring mode for mass spectrometric detection. Quantification is based on deuterated derivatives of all three analytes serving as internal standards. The established LC-ESI-MS/MS method enables fast, robust, selective and highly sensitive quantification of all three reporter ligands in a single chromatographic run. The method was validated according to the Center for Drug Evaluation and Research (CDER) guideline for bioanalytical method validation regarding selectivity, accuracy, precision, calibration curve and sensitivity. Finally, filtration-based MS Binding Assays were performed for all three monoamine transporters based on this LC-ESI-MS/MS quantification method as read out. The affinities determined in saturation experiments for (R,R)-D-84 toward hDAT, for (S,S)-reboxetine toward hNET, and for (S)-citalopram toward hSERT, respectively, were in good accordance with results from literature, clearly demonstrating that the established MS Binding Assays have the potential to be an efficient alternative to radioligand binding assays widely used for this purpose so far. Copyright © 2018 John Wiley & Sons, Ltd.

Separation and quantification of 15 carotenoids by reversed phase high performance liquid chromatography coupled to diode array detection with isosbestic wavelength approach.

PubMed

Mitrowska, Kamila; Vincent, Ursula; von Holst, Christoph

2012-04-13

The manuscript presents the development of a new reverse phase high performance liquid chromatography (RP-HPLC) photo diode array detection method allowing the separation and quantification of 15 carotenoids (adonirubin, adonixanthin, astaxanthin, astaxanthin dimethyl disuccinate, asteroidenone, beta-apo-8'-carotenal, beta-apo-8'-carotenoic acid ethyl ester, beta-carotene, canthaxanthin, capsanthin, citranaxanthin, echinenone, lutein, lycopene, and zeaxanthin), 10 of which are feed additives authorised within the European Union. The developed method allows for the reliable determination of the total carotenoid content in one run using the corresponding E-isomer as calibration standard while taking into account the E/Z-isomers composition. This is a key criterion for the application of the method, since for most of the analytes included in this study analytical standards are only available for the E-isomers. This goal was achieved by applying the isosbestic concept, in order to identify specific wavelengths, at which the absorption coefficients are identical for all stereoisomers concerned. The second target referred to the optimisation of the LC conditions. By means of an experimental design, an optimised RP-HPLC method was developed allowing for a sufficient chromatographic separation of all carotenoids. The selected method uses a Suplex pKb-100 HPLC column and applying a gradient with a mixture of acetonitrile, tert-butyl-methyl ether and water as mobile phases. The limits of detection and limits of quantification ranged from 0.06 mg L(-1) to 0.14 mg L(-1) and from 0.20 mg L(-1) to 0.48 mg L(-1), respectively. Copyright © 2012 Elsevier B.V. All rights reserved.

Ultra-performance liquid chromatographic determination of tocopherols and retinol in human plasma.

PubMed

Bell, Edward C; John, Mathew; Hughes, Rodney J; Pham, Thu

2014-10-01

A rapid, selective and sensitive ultra-performance liquid chromatography method has been developed for the detection and quantification of tocopherols and retinol in human plasma. Alpha-tocopherol, gamma-tocopherol and retinol are assayed using fluorescence detection. Excitation/emission wavelengths are 295/330 nm and 325/470 nm for the analysis of both tocopherols and retinol, respectively. Retinol acetate is employed as the internal standard. The reversed-phase method incorporates gradient elution with a mobile phase consisting of methanol and acetonitrile. Separation of vitamin compounds is achieved using a bridged ethyl hybrid C18 column. The retention times for retinol, retinol acetate, gamma-tocopherol and alpha-tocopherol are 1.6, 1.8, 3.9 and 4.3 min, respectively. The limits of quantification for retinol, gamma-tocopherol and alpha-tocopherol were 0.02, 0.02 and 0.1 µg/mL, respectively. The assay method is suitable for the analysis of tocopherols and retinol in human plasma. The method may be applied following the ingestion of foods fortified with these fat-soluble vitamins. © The Author [2013]. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Simultaneous and rapid determination of gefitinib, erlotinib and afatinib plasma levels using liquid chromatography/tandem mass spectrometry in patients with non-small-cell lung cancer.

PubMed

Hayashi, Hideki; Kita, Yutaro; Iihara, Hirotoshi; Yanase, Koumei; Ohno, Yasushi; Hirose, Chiemi; Yamada, Maya; Todoroki, Kenichiro; Kitaichi, Kiyoyuki; Minatoguchi, Shinya; Itoh, Yoshinori; Sugiyama, Tadashi

2016-07-01

A simultaneous, selective, sensitive and rapid liquid chromatography/tandem mass spectrometry method was developed and validated for the quantification of gefitinib, erlotinib and afatinib in 250 μL samples of human blood plasma. Diluted plasma samples were extracted using a liquid-phase extraction procedure with tert-butyl methyl ether. The three drugs were separated by high-performance liquid chromatography using a C18 column and an isocratic mobile phase running at a flow rate of 0.2 mL/min for 5 min. The drugs were detected using a tandem mass spectrometer with electrospray ionization using imatinib as an internal standard. Calibration curves were generated over the linear concentration range of 0.05-100 nm in plasma with a lower limit of quantification of 0.01 or 0.05 nm for all compounds. Finally, the validated method was applied to a clinical pharmacokinetic study in patients with nonsmall-cell lung cancer (NSCLC) following the oral administration of afatinib. These results indicate that this method is suitable for assessing the risks and benefits of chemotherapy in patients with NSCLC and is useful for therapeutic drug monitoring for NSCLC treatment. As far as we know, this is the first report on LC-MS/MS method for the simultaneous quantification of NSCLC tyrosine kinase inhibitor plasma concentrations including afatinib. Copyright © 2015 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd.

A validated LC-MS/MS assay for simultaneous quantification of methotrexate and tofacitinib in rat plasma: application to a pharmacokinetic study.

PubMed

Sharma, Kuldeep; Giri, Kalpeshkumar; Dhiman, Vinay; Dixit, Abhishek; Zainuddin, Mohd; Mullangi, Ramesh

2015-05-01

A highly sensitive, specific and rapid LC-ESI-MS/MS method has been developed and validated for simultaneous quantification of methotrexate (MTX) and tofacitinib (TFB) in rat plasma (50 μL) using phenacetin as an internal standard (IS), as per the US Food and Drug Administration guidelines. After a solid-phase extraction procedure, the separation of the analytes and IS was performed on a Chromolith RP₁₈e column using an isocratic mobile phase of 5 m m ammonium acetate (pH 5.0) and acetonitrile at a ratio of 25:75 (v/v) using flow-gradient with a total run time of 3.5 min. The detection was performed in multiple reaction monitoring mode, using the transitions of m/z 455.2 → 308.3, m/z 313.2 → 149.2 and m/z 180.3 → 110.2 for MTX, TFB and IS, respectively. The calibration curves were linear over the range of 0.49-91.0 and 0.40-74.4 ng/mL for MTX and TFB, respectively. The intra- and interday accuracy and precision values for MTX and TFB were <15% at low quality control (QC), medium QC and high QC and <20% at lower limit of quantification. The validated assay was applied to derive the pharmacokinetic parameters for MTX and TFB post-dosing of MTX and TFB orally and intravenously to rats. Copyright © 2014 John Wiley & Sons, Ltd.

Development and validation of LC-MS/MS method for the quantification of oxcarbazepine in human plasma using an experimental design.

PubMed

Srinubabu, Gedela; Ratnam, Bandaru Veera Venkata; Rao, Allam Appa; Rao, Medicherla Narasimha

2008-01-01

A rapid tandem mass spectrometric (MS-MS) method for the quantification of Oxcarbazepine (OXB) in human plasma using imipramine as an internal standard (IS) has been developed and validated. Chromatographic separation was achieved isocratically on a C18 reversed-phase column within 3.0 min, using a mobile phase of acetonitrile-10 mM ammonium formate (90 : 10 v/v) at a flow rate of 0.3 ml/min. Quantitation was achieved using multiple reaction monitoring (MRM) scan at MRM transitions m/z 253>208 and m/z 281>86 for OXB and the IS respectively. Calibration curves were linear over the concentration range of 0.2-16 mug/ml (r>0.999) with a limit of quantification of 0.2 mug/ml. Analytical recoveries of OXB from spiked human plasma were in the range of 74.9 to 76.3%. Plackett-Burman design was applied for screening of chromatographic and mass spectrometric factors; factorial design was applied for optimization of essential factors for the robustness study. A linear model was postulated and a 2(3) full factorial design was employed to estimate the model coefficients for intermediate precision. More specifically, experimental design helps the researcher to verify if changes in factor values produce a statistically significant variation of the observed response. The strategy is most effective if statistical design is used in most or all stages of the screening and optimizing process for future method validation of pharmacokinetic and bioequivalence studies.

Easy-Assessment of Levofloxacin and Minocycline in Relevant Biomimetic Media by HPLC-UV Analysis.

PubMed

Matos, Ana C; Pinto, Rosana V; Bettencourt, Ana F

2017-08-01

Simple, economic and environmental friendly high-performance liquid chromatography methods for levofloxacin and minocycline quantification in biomimetic media were developed and validate including their stability at body temperature, an often neglected evaluation parameter. Both methods are similar only differing in the wavelength setting, i.e., for levofloxacin and minocycline quantification the UV detection was set at 284 and at 273 nm, respectively. The separation of both antibiotics was achieved using a reversed-phase column and a mobile phase consisting of acetonitrile and water (15:85) with 0.6% triethylamine, adjusted to pH 3. As an internal standard for levofloxacin quantification, minocycline was used and vice versa. The calibration curves for both methods were linear (r = 0.99) over a concentration range of 0.3-16 μg/mL and 0.5-16 μg/mL for levofloxacin and minocycline, respectively, with precision, accuracy and recovery in agreement with international guidelines requirement. Levofloxacin revealed stability in all media and conditions, including at 37°C, with exception to freeze-thaw cycle conditions. Minocycline presented a more accentuated degradation profile over prolonged time courses, when compared to levofloxacin. Reported data is of utmost interest for pharma and biomaterials fields regarding the research and development of new local drug-delivery-systems containing either of these two antibiotics, namely when monitoring the in vitro release studies of those systems. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

A simple, sensitive determination of ganciclovir in infant plasma by high-performance liquid chromatography with fluorescence detection.

PubMed

Yoshida, Terumitsu; Takahashi, Ryohei; Imai, Koichi; Uchida, Hiroshi; Arai, Yasutoshi; Oh-ishi, Tsutomu

2010-03-01

This study developed a simple and sensitive method using reversed-phase high-performance liquid chromatography (HPLC) for ganciclovir (GCV) plasma concentrations in cytomegalovirus infectious infants with hearing loss. The method involves a simple protein precipitation procedure that uses no solid-phase or liquid-liquid extraction. The HPLC separation was carried out on a Cadenza CD-C(18) column (3 microm, 4.6 mm x 150 mm) with phosphate buffer (pH 2.5, 25 mM) containing 1% methanol-acetonitrile mixture (4:3, v/v) as a mobile phase at a 0.7 mL/min flow rate. GCV was detected using a fluorescence detection (lambdaex/em: 265/380 nm). The quantification limit was 0.025 microg/mL for 100 microL of plasma sample at which good intra- and inter-assay coefficient of variation values (< 4.96%) and recoveries (94.9-96.5%) were established.

Determination of flunixin residues in bovine muscle tissue by liquid chromatography with UV detection.

PubMed

Asea, P A; Patterson, J R; Korsrud, G O; Dowling, P M; Boison, J O

2001-01-01

A new and sensitive liquid chromatography-ultra violet method with a detection limit of 6 ng/g (ppb) and a limit of quantification of 15 ng/g was developed for the determination of flunixin residues in bovine muscle tissue. Flunixin in homogenized animal tissue was extracted with acetonitrile after enzyme digestion. The tissue digest (extract) was then cleaned up on a solid-phase extraction cartridge and eluted with acidified hexane. After the eluate was evaporated to dryness under nitrogen at 55 degrees C, the residue was reconstituted in 1 mL mobile phase solution and analyzed by reversed-phase gradient chromatography with UV detection at 285 nm. The method was then applied in a survey study of slaughter animals to determine whether flunixin is being used in an off-label manner for veal and beef production in Canada.

Sensitive method for the quantitative determination of bromocriptine in human plasma by liquid chromatography-tandem mass spectrometry.

PubMed

Salvador, Arnaud; Dubreuil, Didier; Denouel, Jannick; Millerioux, L

2005-06-25

A sensitive LC-MS-MS assay for the quantitative determination of bromocriptine has been developed and validated and is described in this work. The assay involved the extraction of the analyte from 1 ml of human plasma using a solid phase extraction on Oasis MCX cartridges. Chromatography was performed on a Symmetry C18 (2.1 mm x 100 mm, 3.5 microm) column using a mobile phase consisting of 25:75:01 acetonitrile-water-formic acid with a flow rate of 250 microl/min. The linearity was within the concentration range of 2-500 pg/ml. The lower limit of quantification was 2 pg/ml. This method has been demonstrated to be an improvement over existing methods due to its greater sensitivity and specificity.

A phase quantification method based on EBSD data for a continuously cooled microalloyed steel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhao, H.; Wynne, B.P.; Palmiere, E.J., E-mail: e.j

2017-01-15

Mechanical properties of steels depend on the phase constitutions of the final microstructures which can be related to the processing parameters. Therefore, accurate quantification of different phases is necessary to investigate the relationships between processing parameters, final microstructures and mechanical properties. Point counting on micrographs observed by optical or scanning electron microscopy is widely used as a phase quantification method, and different phases are discriminated according to their morphological characteristics. However, it is difficult to differentiate some of the phase constituents with similar morphology. Differently, for EBSD based phase quantification methods, besides morphological characteristics, other parameters derived from the orientationmore » information can also be used for discrimination. In this research, a phase quantification method based on EBSD data in the unit of grains was proposed to identify and quantify the complex phase constitutions of a microalloyed steel subjected to accelerated coolings. Characteristics of polygonal ferrite/quasi-polygonal ferrite, acicular ferrite and bainitic ferrite on grain averaged misorientation angles, aspect ratios, high angle grain boundary fractions and grain sizes were analysed and used to develop the identification criteria for each phase. Comparing the results obtained by this EBSD based method and point counting, it was found that this EBSD based method can provide accurate and reliable phase quantification results for microstructures with relatively slow cooling rates. - Highlights: •A phase quantification method based on EBSD data in the unit of grains was proposed. •The critical grain area above which GAM angles are valid parameters was obtained. •Grain size and grain boundary misorientation were used to identify acicular ferrite. •High cooling rates deteriorate the accuracy of this EBSD based method.« less

Simple Quantification of Pentosidine in Human Urine and Plasma by High-Performance Liquid Chromatography

PubMed Central

Lee, Ji Sang; Chung, Yoon-Sok; Chang, Sun Young

2017-01-01

Pentosidine is an advanced glycation end-product (AGE) and fluorescent cross-link compound. A simple high-performance liquid chromatographic (HPLC) method was developed for the detection and quantification of pentosidine in human urine and plasma. The mobile phase used a gradient system to improve separation of pentosidine from endogenous peaks, and chromatograms were monitored by fluorescent detector set at excitation and emission wavelengths of 328 and 378 nm, respectively. The retention time for pentosidine was 24.3 min and the lower limits of quantification (LLOQ) in human urine and plasma were 1 nM. The intraday assay precisions (coefficients of variation) were generally low and found to be in the range of 5.19–7.49% and 4.96–8.78% for human urine and plasma, respectively. The corresponding values of the interday assay precisions were 9.45% and 4.27%. Accuracies (relative errors) ranged from 87.9% to 115%. Pentosidine was stable in a range of pH solutions, human urine, and plasma. In summary, this HPLC method can be applied in future preclinical and clinical evaluation of pentosidine in the diabetic patients. PMID:29181026

The Development and Validation of Novel, Simple High-Performance Liquid Chromatographic Method with Refractive Index Detector for Quantification of Memantine Hydrochloride in Dissolution Samples.

PubMed

Sawant, Tukaram B; Wakchaure, Vikas S; Rakibe, Udyakumar K; Musmade, Prashant B; Chaudhari, Bhata R; Mane, Dhananjay V

2017-07-01

The present study was aimed to develop an analytical method for quantification of memantine (MEM) hydrochloride in dissolution samples using high-performance liquid chromatography with refractive index (RI) detector. The chromatographic separation was achieved on C18 (250 × 4.5 mm, 5 μm) column using isocratic mobile phase comprises of buffer (pH 5.2):methanol (40:60 v/v) pumped at a flow rate of 1.0 mL/min. The column effluents were monitored using RI detector. The retention time of MEM was found to be ~6.5 ± 0.3 min. The developed chromatographic method was validated and found to be linear over the concentration range of 5.0-45.0 μg/mL for MEM. Mean recovery of MEM was found to be 99.2 ± 0.5% (w/w). The method was found to be simple, fast, precise and accurate, which can be utilized for the quantification of MEM in dissolution samples. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Simultaneous determination of flurbiprofen and its hydroxy metabolite in human plasma by liquid chromatography-tandem mass spectrometry for clinical application.

PubMed

Lee, Hye-In; Choi, Chang-Ik; Byeon, Ji-Yeong; Lee, Jung-Eun; Park, So-Young; Kim, Young-Hoon; Kim, Se-Hyung; Lee, Yun-Jeong; Jang, Choon-Gon; Lee, Seok-Yong

2014-11-15

Flurbiprofen (FLB) is one of the phenylalkanoic acid derivatives of non-steroidal anti-inflammatory drugs used for the management of pain and inflammation in patients with arthritis. We developed and validated a rapid and sensitive high-performance liquid chromatography analytical method utilizing tandem mass spectrometry (HPLC-MS/MS) for the simultaneous determination of FLB and its major metabolite, 4'-hydroxyflurbiprofen (4'-OH-FLB), in human plasma. Probenecid was used as an internal standard (IS). After liquid-liquid extraction with methyl t-butyl ether, chromatographic separation of the two analytes was achieved using a reversed-phase Luna C18 column (2.0mm×50mm, 5μm particles) with a mobile phase of 10mM ammonium formate buffer (pH 3.5)-methanol (15:85, v/v) and quantified by MS/MS detection in ESI negative ion mode. The flow rate of the mobile phase was 250μl/min and the retention times of FLB, 4'-OH-FLB, and IS were 1.1, 0.8, and 0.9min, respectively. The calibration curves were linear over a range of 0.01-10μg/ml for FLB and 0.01-1μg/ml for 4'-OH-FLB. The lower limit of quantifications using 100μl of human plasma was 0.01μg/ml for both analytes. The mean accuracy and precision for intra- and inter-run validation of FLB and 4'-OH-FLB were all within acceptable limits. The present HPLC-MS/MS method showed improved sensitivity for quantification of the FLB and its major metabolite in human plasma compared with previously described analytical methods. The validated method was successfully applied to a pharmacokinetic study in humans. Copyright © 2014 Elsevier B.V. All rights reserved.

On-line high-performance liquid chromatography-ultraviolet-nuclear magnetic resonance method of the markers of nerve agents for verification of the Chemical Weapons Convention.

PubMed

Mazumder, Avik; Gupta, Hemendra K; Garg, Prabhat; Jain, Rajeev; Dubey, Devendra K

2009-07-03

This paper details an on-flow liquid chromatography-ultraviolet-nuclear magnetic resonance (LC-UV-NMR) method for the retrospective detection and identification of alkyl alkylphosphonic acids (AAPAs) and alkylphosphonic acids (APAs), the markers of the toxic nerve agents for verification of the Chemical Weapons Convention (CWC). Initially, the LC-UV-NMR parameters were optimized for benzyl derivatives of the APAs and AAPAs. The optimized parameters include stationary phase C(18), mobile phase methanol:water 78:22 (v/v), UV detection at 268nm and (1)H NMR acquisition conditions. The protocol described herein allowed the detection of analytes through acquisition of high quality NMR spectra from the aqueous solution of the APAs and AAPAs with high concentrations of interfering background chemicals which have been removed by preceding sample preparation. The reported standard deviation for the quantification is related to the UV detector which showed relative standard deviations (RSDs) for quantification within +/-1.1%, while lower limit of detection upto 16mug (in mug absolute) for the NMR detector. Finally the developed LC-UV-NMR method was applied to identify the APAs and AAPAs in real water samples, consequent to solid phase extraction and derivatization. The method is fast (total experiment time approximately 2h), sensitive, rugged and efficient.

Simultaneous enantioselective determination of six pesticides in aqueous environmental samples by chiral liquid chromatography with tandem mass spectrometry.

PubMed

Zhao, Pengfei; Lei, Shuo; Xing, Mingming; Xiong, Shihang; Guo, Xingjie

2018-03-01

A robust and sensitive method was developed for the enantiomeric analysis of six chiral pesticides (including metalaxyl, epoxiconazole, myclobutanil, hexaconazole, napropamide, and isocarbophos) in aquatic environmental samples. The optimized chromatographic conditions for the quantification of all the 12 enantiomers were performed with Chiralcel OD-RH column using mobile phase consisting of 0.1% aqueous formic acid and acetonitrile operated under reversed-phase conditions and then analyzed using liquid chromatography with tandem mass spectrometry. Twelve enantiomers were detected in multiple reaction monitoring mode. Solid-phase extraction and dispersive liquid-liquid microextraction were employed in this study. Response surface methodology was applied to assist in the dispersive liquid-liquid microextraction optimization. Under the optimum conditions, recoveries of pesticides enantiomers varied from 83.0 to 103.2% at two spiked levels with relative standard deviation less than 11.5%. The concentration factors were up to 1000 times. Method detection and quantification limits varied from 0.11 to 0.48 ng/L and from 0.46 to 1.49 ng/L, respectively. Finally, this method was used to determination of the enantiomers composition of the six pesticides in environmental aqueous matrices, which will help better understand the behavior of individual enantiomer and make accurate risk assessment to ecosystems. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A highly selective nanocomposite based on MIP for curcumin trace levels quantification in food samples and human plasma following optimization by central composite design.

PubMed

Bahrani, Sonia; Ghaedi, Mehrorang; Khoshnood Mansoorkhani, Mohammad Javad; Ostovan, Abbas

2017-01-01

A selective and rapid method was developed for quantification of curcumin in human plasma and food samples using molecularly imprinted magnetic multiwalled carbon nanotubes (MMWCNTs) which was characterized with EDX and FESEM. The role of sorbent mass, volume of eluent and sonication time on response in solid phase microextraction procedure were optimized by central composite design (CCD) combined with response surface methodology (RSM) using Statistica. Preliminary experiments reveal that among different solvents, methanol:dimethyl sulfoxide (4:1V/V) led to efficient and quantitative elution of analyte. A reversed-phase high performance liquid chromatographic technique with UV detection (HPLC-UV) was applied for detection of curcumin content. The assay procedure involves chromatographic separation on analytical Nucleosil C18 column (250×4.6mm I.D., 5μm particle size) at ambient temperature with acetonitrile-water adjusted at pH=4.0 (20:80, v/v) as mobile phase at flow rate of 1.0mLmin -1 , while UV detector was set at 420nm. Under optimized conditions, the method demonstrated linear calibration curve with good detection limit (0.028ngmL -1 ) and R 2 =0.9983. The proposed method was successfully applied to biological fluid and food samples including ginger powder, curry powder, and turmeric powder. Copyright © 2016. Published by Elsevier B.V.

Separation of catechins and methylxanthines in tea samples by capillary electrochromatography.

PubMed

Uysal, Ulku Dilek; Aturki, Zeineb; Raggi, Maria Augusta; Fanali, Salvatore

2009-04-01

In this paper, the simultaneous separation of several polyphenols such as (+)-catechin, (-)-epicatechin, (-)-epigallocatechin, theophylline, caffeine in green and black teas by capillary electrochromatography (CEC) was developed. Several experimental parameters such as stationary phase type, mobile phase composition, buffer and pH, inner diameter of the columns, sample injection, were evaluated to obtain the complete separation of the analysed compounds. Baseline resolution of the studied polyphenols was achieved within 30 min by using a capillary column (id 100 microm) packed with bidentate C(18) particles for 24.5 cm and a mobile phase composed of 5 mM ammonium acetate buffer pH 4 with H(2)O/ACN (80:20, v/v). The applied voltage and the temperature were set at 30 kV and 20 degrees C. Precision, detection and quantification limits, linearity, and accuracy were investigated. A good linearity (R(2) > 0.9992) was achieved over a concentration working range of 2-100 microg/mL for all the analytes. LOD and LOQ were 1 and 2 microg/mL, respectively, for all studied compounds. The CEC method was applied to the analysis of those polyphenols in green and black tea samples after an extraction procedure. Good recovery data from accuracy studies ranged between 90% and 112% for all analytes.

Supercritical fluid chromatography coupled with tandem mass spectrometry: A high-efficiency detection technique to quantify Taxane drugs in whole-blood samples.

PubMed

Jin, Chan; Guan, Jibin; Zhang, Dong; Li, Bing; Liu, Hongzhuo; He, Zhonggui

2017-10-01

We present a technique to rapid determine taxane in blood samples by supercritical fluid chromatography together with mass spectrometry. The aim of this study was to develop a supercritical fluid chromatography with mass spectrometry method for the analysis of paclitaxel, cabazitaxel, and docetaxel in whole-blood samples of rats. Liquid-dry matrix spot extraction was selected in sample preparation procedure. Supercritical fluid chromatography separation of paclitaxel, cabazitaxel, docetaxel, and glyburide (internal standard) was accomplished within 3 min by using the gradient mobile phase consisted of methanol as the compensation solvent and carbon dioxide at a flow rate of 1.0 mL/min. The method was validated regarding specificity, the lower limit of quantification, repeatability, and reproducibility of quantification, extraction recovery, and matrix effects. The lower limit of quantification was found to be 10 ng/mL since it exhibited acceptable precision and accuracy at the corresponding level. All interday accuracies and precisions were within the accepted criteria of ±15% of the nominal value and within ±20% at the lower limit of quantification, implying that the method was reliable and reproducible. In conclusion, this method is a promising tool to support and improve preclinical or clinical pharmacokinetic studies with the taxanes anticancer drugs. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Quantitation of the immunological adjuvants, monophosphoryl lipid A and Quil A in poly (lactic-co-glycolic acid) nanoparticles using high performance liquid chromatography with evaporative light scattering detection.

PubMed

Bobbala, Sharan; McDowell, Arlene; Hook, Sarah

2015-01-15

Monophosphoryl lipid A (MPL) and Quil A are two immunological adjuvants commonly used in vaccines. At present no simple, validated methods for the quantification of Quil A and MPL have been previously reported therefore the aim of the current study was to develop a simple, fast and validated method to quantify MPL and Quil A using high performance liquid chromatography evaporative light scattering detection (HPLC-ELSD). The HPLC-ELSD technique was carried out using a ZORBAX Eclipse XDB-C8 column (2.1×50 mm; particle size, 3.5 μm) in an isocratic elution mode at 25 °C. MPL was eluted at a retention time of 1.8 min with methanol-water as the mobile phase and a detector temperature of 75 °C. Quil A was resolved as three peaks with retention times of 4.1, 5.5 and 6.4 min with a detector temperature of 30 °C and with water-acetonitrile and 0.01% formic acid as the mobile phase. The nebulizer pressure and gain were set at 3.5 bar and 10, respectively. Calibration curves plotted for both the adjuvants had an R(2)>0.997. Accuracy, intra- and inter-day precision were within the accepted limits. The limit of detection for MPL and Quil A were calculated as 1.343 and 2.06 μg/mL, respectively. The limit of quantification was 2.445 for MPL and 8.97 μg/mL for Quil A. This analytical method was used to quantify the entrapment and in vitro release of MPL and Quil A in a poly lactic-co-glycolic acid (PLGA) nanoparticle vaccine. Copyright © 2014 Elsevier B.V. All rights reserved.

Quantitative Imaging with a Mobile Phone Microscope

PubMed Central

Skandarajah, Arunan; Reber, Clay D.; Switz, Neil A.; Fletcher, Daniel A.

2014-01-01

Use of optical imaging for medical and scientific applications requires accurate quantification of features such as object size, color, and brightness. High pixel density cameras available on modern mobile phones have made photography simple and convenient for consumer applications; however, the camera hardware and software that enables this simplicity can present a barrier to accurate quantification of image data. This issue is exacerbated by automated settings, proprietary image processing algorithms, rapid phone evolution, and the diversity of manufacturers. If mobile phone cameras are to live up to their potential to increase access to healthcare in low-resource settings, limitations of mobile phone–based imaging must be fully understood and addressed with procedures that minimize their effects on image quantification. Here we focus on microscopic optical imaging using a custom mobile phone microscope that is compatible with phones from multiple manufacturers. We demonstrate that quantitative microscopy with micron-scale spatial resolution can be carried out with multiple phones and that image linearity, distortion, and color can be corrected as needed. Using all versions of the iPhone and a selection of Android phones released between 2007 and 2012, we show that phones with greater than 5 MP are capable of nearly diffraction-limited resolution over a broad range of magnifications, including those relevant for single cell imaging. We find that automatic focus, exposure, and color gain standard on mobile phones can degrade image resolution and reduce accuracy of color capture if uncorrected, and we devise procedures to avoid these barriers to quantitative imaging. By accommodating the differences between mobile phone cameras and the scientific cameras, mobile phone microscopes can be reliably used to increase access to quantitative imaging for a variety of medical and scientific applications. PMID:24824072

Simultaneous identification and quantification by liquid chromatography of benzethonium chloride, methyl paraben and triclosan in commercial products labeled as grapefruit seed extract.

PubMed

Avula, B; Dentali, S; Khan, I A

2007-08-01

A HPLC method has been developed which permits the quantification of methyl paraben, benzethonium chloride and triclosan in various samples of grapefruit seed extract (GSE). The best results were obtained with a Phenomenex Gemini C18 column using gradient mobile phase of water (0.1% acetic acid) and acetonitrile (0.1% acetic acid) with a flow rate of 1.0 mL per minute. The detection wavelength was 254 nm for methyl paraben, and 275 nm for benzethonium chloride and triclosan. The main synthetic antimicrobial agent identified in commercial GSE samples was benzethonium chloride in concentrations from 0.29-21.84%. Positive ion electrospray MS of a commercial GSE sample showed a molecular ion at m/z 412 [M+], which matched that of a standard of benzethonium chloride. Triclosan was detected in two samples at 0.009 and 1.13%concentrations; while methyl paraben was not detected in the samples analyzed.

Determination of three steroidal saponins from Ophiopogon japonicus (Liliaceae) via high-performance liquid chromatography with mass spectrometry.

PubMed

Wang, Yongyi; Xu, Jinzhong; Qu, Haibin

2013-01-01

A simple and accurate analytical method was developed for simultaneous quantification of three steroidal saponins in the roots of Ophiopogon japonicus via high-performance liquid chromatography (HPLC) with mass spectrometry (MS) in this study. Separation was performed on a Tigerkin C(18) column and detection was performed by mass spectrometry. A mobile phase consisted of 0.02% formic acid in water (v/v) and 0.02% formic acid in acetonitrile (v/v) was used with a flow rate of 0.5 mL min(-1). The quantitative HPLC-MS method was validated for linearity, precision, repeatability, stability, recovery, limits of detection and quantification. This developed method provides good linearity (r >0.9993), intra- and inter-day precisions (RSD <4.18%), repeatability (RSD <5.05%), stability (RSD <2.08%) and recovery (93.82-102.84%) for three steroidal saponins. It could be considered as a suitable quality control method for O. japonicus.

Rapid Quantification of Four Anthocyanins in Red Grape Wine by Hydrophilic Interaction Liquid Chromatography/Triple Quadrupole Linear Ion Trap Mass Spectrometry.

PubMed

Sun, Yongming; Xia, Biqi; Chen, Xiangzhun; Duanmu, Chuansong; Li, Denghao; Han, Chao

2015-01-01

The identification and quantification of four anthocyanins (cyanidin-3-O-glucoside, peonidin-3-O-glucoside, delphinidin-3-O-glucoside, and malvidin-3-O-glucoside) in red grape wine were carried out by hydrophilic interaction liquid chromatography/triple quadrupole linear ion trap MS (HILIC/QTrap-MS/MS). Samples were diluted directly and separated on a Merck ZIC HILIC column with 20 mM ammonium acetate solution-acetonitrile mobile phase. Quantitative data acquisition was carried out in the multiple reaction monitoring mode. Additional identification and confirmation of target compounds were performed using the enhanced product ion mode of the linear ion trap. The LOQs were in the range 0.05-1.0 ng/mL. The average recoveries were in the range 94.6 to 104.5%. The HILIC/QTrap-MS/MS platform offers the best sensitivity and specificity for characterization and quantitative determination of the four anthocyanins in red grape wines and fulfills the quality criteria for routine laboratory application.

Chromatographic determination of Fe chelated by ethylenediamine-N-(o-hydroxyphenylacetic)-N'-(p-hydroxyphenylacetic) acid in commercial EDDHA/Fe3+ fertilizers.

PubMed

García-Marco, Sonia; Torreblanca, Ana; Lucena, Juan J

2006-02-22

EDDHA/Fe3+ chelates are the most common fertilizers used to solve Fe chlorosis in established crops. Commercial products contain two regioisomers, ethylenediamine-N,N'-bis(o-hydroxyphenylacetic) acid (o,o-EDDHA)/Fe3+ and ethylenediamine-N-(o-hydroxyphenylacetic)-N'-(p-hydroxyphenylacetic) acid (o,p-EDDHA)/Fe3+. Although several chromatographic methods exist for the determination of Fe3+ chelated by the o,o-EDDHA isomer, no method has been described for the quantification of Fe3+ chelated by o,p-EDDHA. In this work, factors that affect the behavior of o,p-EDDHA/Fe3+ in ion pair chromatography are reviewed: pH, ion pair reagent, and organic modifier. The best chromatographic performance was obtained with an aqueous mobile phase at pH 6.0 containing 35% acetonitrile and 5 mM tetrabutylammonium hydroxide under isocratic elution conditions. This method was applied to the quantification of commercial samples.

Determination of lansoprazole in human plasma by rapid resolution liquid chromatography-electrospray tandem mass spectrometry: application to a bioequivalence study on Chinese volunteers.

PubMed

Wu, Guo-Lan; Zhou, Hui-Li; Shentu, Jian-Zhong; He, Qiao-Jun; Yang, Bo

2008-12-15

A simple, sensitive and rapid LC/MS/MS method was developed for the quantification of lansoprazole in human plasma. After a simple sample preparation procedure by one-step protein precipitation with acetonitrile, lansoprazole and the internal standard bicalutamide were chromatographed on a Zorbax SB-C(18) (3.0 mm x 150 mm, 3.5 microm, Agilent) column with the mobile phase consisted of methanol-water (70:30, v/v, containing 5 mM ammonium formate, pH was adjusted to 7.85 by 1% ammonia solution). Detection was performed on a triple quadrupole tandem mass spectrometry by multiple reaction monitoring (MRM) mode via negative eletrospray ionization source (ESI(-)). The lower limit of quantification was 5.5 ng/mL, and the assay exhibited a linear range of 5.5-2200.0 ng/mL. The validated method was successfully applied to investigate the bioequivalence between two kinds of preparation (test vs. reference product) in twenty-eight healthy male Chinese volunteers.

Simultaneous separation and determination of six arsenic species in rice by anion-exchange chromatography with inductively coupled plasma mass spectrometry.

PubMed

Ma, Li; Yang, Zhaoguang; Tang, Jie; Wang, Lin

2016-06-01

The simultaneous separation and determination of arsenite As(III), arsenate As(V), monomethylarsonic acid (MMA), dimethylarsinic acid (DMA), arsenobetaine (AsB), and arsenocholine (AsC) in rice samples have been carried out in one single anion-exchange column run by high-performance liquid chromatography with inductively coupled plasma mass spectrometry. To estimate the effect of variables on arsenic (As) speciation, the chromatographic conditions including type of competing anion, ionic strength, pH of elution buffer, and flow rate of mobile phase have been investigated by a univariate approach. Under the optimum chromatographic conditions, baseline separation of six As species has been achieved within 10 min by gradient elution program using 4 mM NH4 HCO3 at pH 8.6 as mobile phase A and 4 mM NH4 HCO3 , 40 mM NH4 NO3 at pH 8.6 as mobile phase B. The method detection limits for As(III), As(V), MMA, DMA, AsB, and AsC were 0.4, 0.9, 0.2, 0.4, 0.5, and 0.3 μg/kg, respectively. The proposed method has been applied to separation and quantification of As species in real rice samples collected from Hunan Province, China. The main As species detected in all samples were As(III), As(V) and DMA, with inorganic As accounting for over 80% of total As in these samples. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A validated ultra high-pressure liquid chromatography method for separation of candesartan cilexetil impurities and its degradents in drug product

PubMed Central

Kumar, Namala Durga Atchuta; Babu, K. Sudhakar; Gosada, Ullas; Sharma, Nitish

2012-01-01

Introduction: A selective, specific, and sensitive “Ultra High-Pressure Liquid Chromatography” (UPLC) method was developed for determination of candesartan cilexetil impurities as well asits degradent in tablet formulation. Materials and Methods: The chromatographic separation was performed on Waters Acquity UPLC system and BEH Shield RP18 column using gradient elution of mobile phase A and B. 0.01 M phosphate buffer adjusted pH 3.0 with Orthophosphoric acid was used as mobile phase A and 95% acetonitrile with 5% Milli Q Water was used as mobile phase B. Ultraviolet (UV) detection was performed at 254 nm and 210 nm, where (CDS-6), (CDS-5), (CDS-7), (Ethyl Candesartan), (Desethyl CCX), (N-Ethyl), (CCX-1), (1 N Ethyl Oxo CCX), (2 N Ethyl Oxo CCX), (2 N Ethyl) and any unknown impurity were monitored at 254 nm wavelength, and two process-related impurities, trityl alcohol and MTE impurity, were estimated at 210 nm. Candesartan cilexetil andimpurities were chromatographed with a total run time of 20 min. Results: Calibration showed that the response of impurity was a linear function of concentration over the range limit of quantification to 2 μg/mL (r2≥0.999) and the method was validated over this range for precision, intermediate precision, accuracy, linearity, and specificity. For the precision study, percentage relative standard deviation of each impurity was <15% (n=6). Conclusion: The method was found to be precise, accurate, linear, and specific. The proposed method was successfully employed for estimation of candesartan cilexetil impurities in pharmaceutical preparations. PMID:23781475

Stability Indicating HPLC Method for the Determination of Chiral Purity of R-(-)-5-[2-aminopropyl]-2-methoxybenzene Sulfonamide.

PubMed

Kasawar, G B; Farooqui, M N

2009-09-01

A chiral reverse phase liquid chromatographic method was developed for the enantiomeric resolution of racemic mixture of (-)-5-[2-aminopropyl]-2-methoxybenzene sulfonamide in bulk drug. The enantiomeric separation of sulfonamide was resolved on a Crownpak CR (+) column using perchloric acid buffer of pH 1.0 as mobile phase and with UV detection at 226 nm. The method is validated and proved to be robust. The limit of detection and quantification of S (-)-(5)-[2-aminopropyl]-2-methoxybenzene sulfonamide] was found to be 0.084 and 0.159 mug/ml, respectively for 20 mul injection volume. The percentage recovery of S (-)-(5)-[2-aminopropyl]-2-methoxybenzene sulfonamide] ranged from 99.57 to 101.88 in bulk drug samples of R (-)-(5)-[2- aminopropyl]-2-methoxybenzene sulfonamide].

Stability Indicating HPLC Method for the Determination of Chiral Purity of R-(-)-5-[2-aminopropyl]-2-methoxybenzene Sulfonamide

PubMed Central

Kasawar, G. B.; Farooqui, M. N.

2009-01-01

A chiral reverse phase liquid chromatographic method was developed for the enantiomeric resolution of racemic mixture of (-)-5-[2-aminopropyl]-2-methoxybenzene sulfonamide in bulk drug. The enantiomeric separation of sulfonamide was resolved on a Crownpak CR (+) column using perchloric acid buffer of pH 1.0 as mobile phase and with UV detection at 226 nm. The method is validated and proved to be robust. The limit of detection and quantification of S (-)-(5)-[2-aminopropyl]-2-methoxybenzene sulfonamide] was found to be 0.084 and 0.159 μg/ml, respectively for 20 μl injection volume. The percentage recovery of S (-)-(5)-[2-aminopropyl]-2-methoxybenzene sulfonamide] ranged from 99.57 to 101.88 in bulk drug samples of R (-)-(5)-[2- aminopropyl]-2-methoxybenzene sulfonamide]. PMID:20502572

Focused microwave-assisted solvent extraction and HPLC determination of effective constituents in Eucommia ulmodies Oliv. (E. ulmodies).

PubMed

Li, Hui; Chen, Bo; Zhang, Zhaohui; Yao, Shouzhuo

2004-06-17

A new focused microwave-assisted solvent extraction method using water as solvent has been developed for leaching geniposidic and chlorogenic acids from Eucommia ulmodies Oliv. The extraction procedures were optimized using a two indexes orthogonal experimental design and graphical analysis, by varying irradiation time, solvent volume, solvent composition and microwave power. The optimum extraction conditions were obtained: for geniposidic acid, 50% micorwave power, 40s irradiation, and 80% (v/v) aqueous methanol as extraction solvent (20mlg(-1) sample); and for chlorogenic acid, 50% micorwave power, 30s irradiation, and 20% aqueous methanol (20mlg(-1) sample). The composition of the extraction solvent was optimized and can be directly used as the mobile phase in the HPLC separation. Quantification of organic acids was done by HPLC at room temperature using Spherigel C(18) chromatographic column (250 mm x4.6 mm , i.d. 5mum), the methanol:water:acetic acid (20:80:1.0, v/v) mobile phase and UV detection at 240nm. The R.S.D. of the extraction process for geniposidic and chlorogenic acid were 3.8 and 4.1%, respectively.

Improved HPLC method with the aid of chemometric strategy: determination of loxoprofen in pharmaceutical formulation.

PubMed

Venkatesan, P; Janardhanan, V Sree; Muralidharan, C; Valliappan, K

2012-06-01

Loxoprofen belongs to a class of Nonsteroidal anti-inflammatory drug acts by inhibiting isoforms of cyclo-oxygenase 1 and 2. In this study an improved RP-HPLC method was developed for the quantification of loxoprofen in pharmaceutical dosage form. For that purpose an experimental design approach was employed. Factors-independent variables (organic modifier, pH of the mobile phase and flow rate) were extracted from the preliminary study and as dependent variables three responses (loxoprofen retention factor, resolution between loxoprofen probenecid and retention time of probenecid) were selected. For the improvement of method development and optimization step, Derringer's desirability function was applied to simultaneously optimize the chosen three responses. The procedure allowed deduction of optimal conditions and the predicted optimum was acetonitrile: water (53:47, v/v), pH of the mobile phase adjusted at to 2.9 with ortho phosphoric acid. The separation was achieved in less than 4minutes. The method was applied in the quality control of commercial tablets. The method showed good agreement between the experimental data and predictive value throughout the studied parameter space. The optimized assay condition was validated according to International conference on harmonisation guidelines to confirm specificity, linearity, accuracy and precision.

Development and Validation of HPLC-DAD and UHPLC-DAD Methods for the Simultaneous Determination of Guanylhydrazone Derivatives Employing a Factorial Design.

PubMed

Azevedo de Brito, Wanessa; Gomes Dantas, Monique; Andrade Nogueira, Fernando Henrique; Ferreira da Silva-Júnior, Edeildo; Xavier de Araújo-Júnior, João; Aquino, Thiago Mendonça de; Adélia Nogueira Ribeiro, Êurica; da Silva Solon, Lilian Grace; Soares Aragão, Cícero Flávio; Barreto Gomes, Ana Paula

2017-08-30

Guanylhydrazones are molecules with great pharmacological potential in various therapeutic areas, including antitumoral activity. Factorial design is an excellent tool in the optimization of a chromatographic method, because it is possible quickly change factors such as temperature, mobile phase composition, mobile phase pH, column length, among others to establish the optimal conditions of analysis. The aim of the present work was to develop and validate a HPLC and UHPLC methods for the simultaneous determination of guanylhydrazones with anticancer activity employing experimental design. Precise, exact, linear and robust HPLC and UHPLC methods were developed and validated for the simultaneous quantification of the guanylhydrazones LQM10, LQM14, and LQM17. The UHPLC method was more economic, with a four times less solvent consumption, and 20 times less injection volume, what allowed better column performance. Comparing the empirical approach employed in the HPLC method development to the DoE approach employed in the UHPLC method development, we can conclude that the factorial design made the method development faster, more practical and rational. This resulted in methods that can be employed in the analysis, evaluation and quality control of these new synthetic guanylhydrazones.

Validated RP-HPLC/DAD Method for the Quantification of Insect Repellent Ethyl 2-Aminobenzoate in Membrane-Moderated Matrix Type Monolithic Polymeric Device.

PubMed

Islam, Johirul; Zaman, Kamaruz; Chakrabarti, Srijita; Sharma Bora, Nilutpal; Mandal, Santa; Pratim Pathak, Manash; Srinivas Raju, Pakalapati; Chattopadhyay, Pronobesh

2017-07-01

A simple, accurate and sensitive reversed-phase high-performance liquid chromatographic (RP-HPLC) method has been developed for the estimation of ethyl 2-aminobenzoate (EAB) in a matrix type monolithic polymeric device and validated as per the International Conference on Harmonization guidelines. The analysis was performed isocratically on a ZORBAX Eclipse plus C18 analytical column (250 × 4.4 mm, 5 μm) and a diode array detector (DAD) using acetonitrile and water (75:25 v/v) as the mobile phase by keeping the flow-rate constant at 1.0 mL/min. Determination of EAB was not interfered in the presence of excipients. Inter- and intra-day relative standard deviations were not higher than 2%. Mean recovery was between 98.7 and 101.3%. Calibration curve was linear in the concentration range of 0.5-10 µg/mL. Limits of detection and quantification were 0.19 and 0.60 µg/mL, respectively. Thus, the present report put forward a novel method for the estimation of EAB, an emerging insect repellent, by using RP-HPLC technique. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Quantification of MDMA and MDA in abusers' hair samples by semi-micro column HPLC with fluorescence detection.

PubMed

Nakamura, Shinichi; Tomita, Mamoru; Wada, Mitsuhiro; Chung, Heesun; Kuroda, Naotaka; Nakashima, Kenichiro

2006-01-01

A sensitive semi-micro column high-performance liquid chromatography with fluorescence detection method was developed for the determination of 3,4-methylenedioxymethamphetamine (MDMA), 3,4-methylenedioxyamphetamine (MDA), methamphetamine (MP) and amphetamine (AP) in human hair. 4-(4,5-Diphenyl-1H-imidazol-2-yl)benzoyl chloride (DIB-Cl) and 1-methyl-3-phenylpropylamine were used as labeling reagent and internal standard, respectively. These drugs were extracted from hair into 5% trifluoroacetic acid in methanol, and fluorescent labeled with DIB-Cl. The separation of DIB-derivatives was achieved on a reversed-phase semi-micro ODS column with an acetonitrile-methanol-water (30:40:30, v/v/v%) mixture as a mobile phase. The limits of detection at a signal-to-noise ratio of 3 for MDMA, MDA, MP and AP were 0.25, 0.15, 0.25 and 0.19 ng/mg, respectively. Precision of intra- and inter-day assay as the relative standard deviation were in the range 1.5-6.8% (n = 5) and 2.7-4.7% (n = 5), respectively. The proposed method was highly sensitive and able to detect MDMA and its related compounds in small amounts of hair sample, and could be applied to quantification of six abusers' hair samples. Copyright 2006 John Wiley & Sons, Ltd.

Development and validation of an LC-UV method for the quantification and purity determination of the novel anticancer agent C1311 and its pharmaceutical dosage form.

PubMed

den Brok, Monique W J; Nuijen, Bastiaan; Hillebrand, Michel J X; Grieshaber, Charles K; Harvey, Michael D; Beijnen, Jos H

2005-09-01

C1311 (5-[[2-(diethylamino)ethyl]amino]-8-hydroxyimidazo [4,5,1-de]-acridin-6-one-dihydrochloride trihydrate) is the lead compound from the group of imidazoacridinones, a novel group of rationally designed anticancer agents. The pharmaceutical development of C1311 necessitated the availability of an assay for the quantification and purity determination of C1311 active pharmaceutical ingredient (API) and its pharmaceutical dosage form. A reversed-phase liquid chromatographic method (RP-LC) with ultraviolet (UV) detection was developed, consisting of separation on a C18 column with phosphate buffer (60 mM; pH 3 with 1 M citric acid)-acetonitrile-triethylamine (83:17:0.05, v/v/v) as the mobile phase and UV-detection at 280 nm. The method was found to be linear over a concentration range of 2.50-100 microg/mL, precise and accurate. Accelerated stress testing showed degradation products, which were well separated from the parent compound, confirming its stability-indicating capacity. Moreover, the use of LC-MS and on-line photo diode array detection enabled us to propose structures for four degradation products. Two of these products were also found as impurities in the API and more abundantly in an impure lot of API.

A simple, sensitive and rapid isocratic reversed-phase high-performance liquid chromatography method for determination and stability study of curcumin in pharmaceutical samples

PubMed Central

Amanolahi, Farjad; Mohammadi, Ali; Kazemi Oskuee, Reza; Nassirli, Hooriyeh; Malaekeh-Nikouei, Bizhan

2017-01-01

Objective: This study was designed to develop and validate a new reversed-phase high-performance liquid chromatography (RP-HPLC) method based on Q2 (R1) International Conference on Harmonization (ICH) guideline for determination of curcumin in pharmaceutical samples. Materials and Methods: The HPLC instrument method was optimized with isocratic elution with acetonitrile: ammonium acetate (45:55, v/v, pH 3.5), C18 column (150 mm×4.6 mm×5 µm particle size) and a flow rate of 1 ml/min in ambient condition and total retention time of 17 min. The volume of injection was set at 20 µl and detection was recorded at 425 nm. The robustness of the method was examined by changing the mobile phase composition, mobile phase pH, and flow rate. Results: The method was validated with respect to precision, accuracy and linearity in a concentration range of 2-100 µg/ml. The limit of detection (LOD) and limit of quantification (LOQ) were 0.25 and 0.5 µg/ml, respectively. The percentage of recovery was 98.9 to 100.5 with relative standard deviation (RSD) < 0.638%. Conclusion: The method was found to be simple, sensitive and rapid for determination of curcumin in pharmaceutical samples and had enough sensitivity to detect degradation product of curcumin produced under photolysis and hydrolysis stress condition. PMID:29062806

Quantifying the Interplay of Natural Organic Matter with Environmental Factors on Nanoparticle Transport in Porous Media

NASA Astrophysics Data System (ADS)

Yang, X.; von der Kammer, F.; Wiesner, M.; Yang, Y.; Hofmann, T.

2016-12-01

Humic acid (HA) is widespread in environment and may interfere with nanoparticle transport in porous media. Quantification of the HA's influence is challenging due to the heterogeneous natural of the organic compounds. Through a series of laboratory and modeling studies, we explored (1) the differential mechanisms operated by the sediment - and solution-phase HA in controlling particle transport; (2) the interplay of the HA with several important environmental factors including solution pH, ionic strength (IS), flow rate, organic & particle concentration, and particle size; (3) modeling tools to quantify the above identified influential mechanisms. Study results suggest that site blocking is the main effect imposed by sediment-phase HA on nanoparticle transport while competitive deposition (with nanoparticles) and continuous site blocking occur simultaneously for the solution-phase HA. Solution pH and IS jointly control the HA's blocking efficiency by varying the adsorbed organic conformation. Conversely, the effect of the adsorbed organic concentration appeared to be insignificant. In addition to the chemical parameters, physical parameters like particle size and flow rate also impact on the organic blockage: the blocking efficiency was stronger on larger particles than on smaller ones; increasing flow rate magnifies the HA's blocking efficiency on larger particles but had insignificant impact on smaller ones. Those mechanistic investigations were supported by a quantification approach and a mathematical model developed in those studies. These results can improve the understanding on particle mobility in heterogeneous natural porous media.

A Fast and Validated Reversed-Phase HPLC Method for Simultaneous Determination of Simvastatin, Atorvastatin, Telmisartan and Irbesartan in Bulk Drugs and Tablet Formulations

PubMed Central

Alhazmi, Hassan A.; Alnami, Ahmed M.; Arishi, Mohammed A. A.; Alameer, Raad K.; Al Bratty, Mohammed; Rehman, Zia ur; Javed, Sadique A.; Arbab, Ismail A.

2017-01-01

The aim of this study was to develop and validate a fast and simple reversed-phase HPLC method for simultaneous determination of four cardiovascular agents—atorvastatin, simvastatin, telmisartan and irbesartan in bulk drugs and tablet oral dosage forms. The chromatographic separation was accomplished by using Symmetry C18 column (75 mm × 4.6 mm; 3.5 μ) with a mobile phase consisting of ammonium acetate buffer (10 mM; pH 4.0) and acetonitrile in a ratio 40:60 v/v. Flow rate was maintained at 1 mL/min up to 3.5 min, and then suddenly changed to 2 mL/min till the end of the run (7.5 min). The data was acquired using ultraviolet detector monitored at 220 nm. The method was validated for linearity, precision, accuracy and specificity. The developed method has shown excellent linearity (R2 > 0.999) over the concentration range of 1–16 µg/mL. The limits of detection (LODs) and limits of quantification (LOQs) were in the range of 0.189–0.190 and 0.603–0.630 µg/mL, respectively. Inter-day and intra-day accuracy and precision data were recorded in the acceptable limits. The new method has successfully been applied for quantification of all four drugs in their tablet dosage forms with percent recovery within 100 ± 2%. PMID:29257120

Simultaneous pharmacokinetics and stability studies of physalins in rat plasma and intestinal bacteria culture media using liquid chromatography with mass spectrometry.

PubMed

Zheng, Yunliang; Lin, Meihua; Hu, Xingjiang; Zhai, You; Zhang, Qiao; Lou, Yan; ShenTu, Jianzhong; Wu, Lihua

2018-04-01

Physalins are the major steroidal constituent of Physalis plants and display a range of biological activities. For this study, a rapid and sensitive high-performance liquid chromatography with triple quadrupole mass spectrometry method was developed for the simultaneous quantification of six physalins. Specifically, it was for the quantification of physalin A, physalin B, physalin D, physalin G, 4,7-didehydroneophysalin B, and isophysalin B in rat plasma and rat intestinal bacteria. After a solid-phase extraction, analytes and internal standards (prednisolone) were separated on a Shield reverse-phase C18 column (measuring 3 mm × 150 mm with an internal diameter of 3.5 μm) and determined using multiple reactions in a monitoring mode with a positive-ion electrospray ionization source. The mobile phase was a mixture of 0.1% formic acid in water (A) and acetonitrile (B) and was used at a flow rate of 0.6 mL/min. The intra- and interday precisions were within 15% with accuracies ranging from 86.2 to 114%. The method was validated and successfully applied to pharmacokinetics and stability studies of six physalins in rat plasma and rat intestinal bacteria, respectively. The results showed that physalin B and isophysalin B could not be absorbed by rats, and rat intestinal bacteria could quickly transform physalins. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Quantification of metronidazole in human plasma using a highly sensitive and rugged LC-MS/MS method for a bioequivalence study.

PubMed

Vanol, Pravin G; Sanyal, Mallika; Shah, Priyanka A; Shrivastav, Pranav S

2018-03-23

A highly sensitive, selective and rugged method has been described for the quantification of metronidazole (MTZ) in human plasma by liquid chromatography-tandem mass spectrometry using metronidazole-d4 as the internal standard (IS). The analyte and the IS were extracted from 100 μL plasma by liquid-liquid extraction. The clear samples obtained were chromatographed on an ACE C 18 (100 × 4.6 mm, 5 μm) column using acetonitrile and 10.0 mm ammonium formate in water, pH 4.00 (80:20, v/v) as the mobile phase. A triple quadrupole mass spectrometer system equipped with turbo ion spray source and operated in multiple reaction monitoring mode was used for the detection and quantification of MTZ. The calibration range was established from 0.01 to 10.0 μg/mL. The results of validation testing for precision and accuracy, selectivity, matrix effects, recovery and stability complied with current bioanalytical guidelines. A run time of 3.0 min permitted analysis of more than 300 samples in a day. The method was applied to a bioequivalence study with 250 mg MTZ tablet formulation in 24 healthy Indian males. Copyright © 2018 John Wiley & Sons, Ltd.

Simultaneous Quantification of Gymnemic Acid as Gymnemagenin and Charantin as β-Sitosterol Using Validated HPTLC Densitometric Method.

PubMed

Ahamad, Javed; Amin, Saima; Mir, Showkat R

2015-08-01

Gymnemic acid and charantin are well-established antidiabetic phytosterols found in Gymnema sylvestre and Momordica charantia, respectively. The fact that these plants are often used together in antidiabetic poly-herbal formulations lured us to develop an HPTLC densitometric method for the simultaneous quantification of their bioactive compounds. Indirect estimation of gymnemic acid as gymnemagenin and charantin as β-sitosterol after hydrolysis has been proposed. Aluminum-backed silica gel 60 F254 plates (20 × 10 cm) were used as stationary phase and toluene-ethyl acetate-methanol-formic acid (60 : 20 : 15 : 5, v/v) as mobile phase. Developed chromatogram was scanned at 550 nm after derivatization with modified vanillin-sulfuric acid reagent. Regression analysis of the calibration data showed an excellent linear relationship between peak area versus concentration of the analytes. Linearity was found to be in the range of 500-2,500 and 100-500 ng/band for gymnemagenin and β-sitosterol, respectively. The suitability of the developed HPTLC method for simultaneous estimation of analytes was established by validating it as per the ICH guidelines. The limits of detection and quantification for gymnemagenin were found to be ≈60 and ≈190 ng/band, and those for β-sitosterol ≈30 and ≈90 ng/band, respectively. The developed method was found to be linear (r(2) = 0.9987 and 0.9943), precise (relative standard deviation <1.5 and <2% for intra- and interday precision) and accurate (mean recovery ranged between 98.43-101.44 and 98.68-100.20%) for gymnemagenin and β-sitosterol, respectively. The proposed method was also found specific and robust for quantification of both the analytes and was successfully applied to herbal drugs and in-house herbal formulation without any interference. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Quantification of VX Nerve Agent in Various Food Matrices by Solid-Phase Extraction Ultra-Performance Liquid ChromatographyTime-of-Flight Mass Spectrometry

DTIC Science & Technology

2016-04-01

QUANTIFICATION OF VX NERVE AGENT IN VARIOUS FOOD MATRICES BY SOLID-PHASE EXTRACTION ULTRA-PERFORMANCE...TITLE AND SUBTITLE Quantification of VX Nerve Agent in Various Food Matrices by Solid-Phase Extraction Ultra-Performance Liquid Chromatography... food matrices. The mixed-mode cation exchange (MCX) sorbent and Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS) methods were used for

Validated LC–MS-MS Method for Multiresidual Analysis of 13 Illicit Phenethylamines in Amniotic Fluid

PubMed Central

Burrai, Lucia; Nieddu, Maria; Carta, Antonio; Trignano, Claudia; Sanna, Raimonda; Boatto, Gianpiero

2016-01-01

A multi-residue analytical method was developed for the determination in amniotic fluid (AF) of 13 illicit phenethylamines, including 12 compounds never investigated in this matrix before. Samples were subject to solid-phase extraction using; hydrophilic–lipophilic balance cartridges which gave good recoveries and low matrix effects on analysis of the extracts. The quantification was performed by liquid chromatography electrospray tandem mass spectrometry. The water–acetonitrile mobile phase containing 0.1% formic acid, used with a C18 reversed phase column, provided adequate separation, resolution and signal-to-noise ratio for the analytes and the internal standard. The final optimized method was validated according to international guidelines. A monitoring campaign to assess fetal exposure to these 13 substances of abuse has been performed on AF test samples obtained from pregnant women. All mothers (n = 194) reported no use of drugs of abuse during pregnancy, and this was confirmed by the analytical data. PMID:26755540

RP-HPLC method with electrochemical detection for the determination of metoclopramide in serum and its use in pharmacokinetic studies.

PubMed

Lamparczyk, H; Chmielewska, A; Konieczna, L; Plenis, A; Zarzycki, P K

2001-12-01

A rapid and sensitive reversed-phase high performance liquid chromatographic method has been developed for the determination of metoclopramide in serum. The assay was performed after single extraction with ethyl ether using methyl parahydroxybenzoate as internal standard. Chromatographic separations were performed on C(18) stationary phase with a mobile phase composed of methanol-phosphate buffer pH 3 (30:70 v/v). Analytes were detected electrochemically. The quantification limit for metoclopramide in serum was 2 ng mL(-1). Linearity of the method was confirmed in the range of 5-120 ng mL(-1) (correlation coefficient 0.9998). Within-day relative standard deviations (RSDs) ranged from 0.3 to 5.5% and between-day RSDs from 0.8 to 6.0%. The analytical method was successfully applied for the determination of pharmacokinetic parameters after ingestion of 10 mg dose of metoclopramide. Studies were performed on 18 healthy volunteers of both sexes. Copyright 2001 John Wiley & Sons, Ltd.

Single column comprehensive analysis of pharmaceutical preparations using dual-injection mixed-mode (ion-exchange and reversed-phase) and hydrophilic interaction liquid chromatography.

PubMed

Kazarian, Artaches A; Taylor, Mark R; Haddad, Paul R; Nesterenko, Pavel N; Paull, Brett

2013-12-01

The comprehensive separation and detection of hydrophobic and hydrophilic active pharmaceutical ingredients (APIs), their counter-ions (organic, inorganic) and excipients, using a single mixed-mode chromatographic column, and a dual injection approach is presented. Using a mixed-mode Thermo Fisher Acclaim Trinity P1 column, APIs, their counter-ions and possible degradants were first separated using a combination of anion-exchange, cation-exchange and hydrophobic interactions, using a mobile phase consisting of a dual organic modifier/salt concentration gradient. A complementary method was also developed using the same column for the separation of hydrophilic bulk excipients, using hydrophilic interaction liquid chromatography (HILIC) under high organic solvent mobile phase conditions. These two methods were then combined within a single gradient run using dual sample injection, with the first injection at the start of the applied gradient (mixed-mode retention of solutes), followed by a second sample injection at the end of the gradient (HILIC retention of solutes). Detection using both ultraviolet absorbance and refractive index enabled the sensitive detection of APIs and UV-absorbing counter-ions, together with quantitative determination of bulk excipients. The developed approach was applied successfully to the analysis of a dry powder inhalers (Flixotide(®), Spiriva(®)), enabling comprehensive quantification of all APIs and excipients in the sample. Copyright © 2013 Elsevier B.V. All rights reserved.

A Rapid Novel HPLC Method for Estimation of Eight Related Compounds in Azilsartan Kamedoxomil and Identification of Degradation Compounds by Using LC-MS.

PubMed

Sreenivasulu, J; Venkata Ramana, P; Sampath Kumar Reddy, G; Nagaraju, Ch V S; Thirumalai Rajan, S; Eswaraiah, S

2015-10-01

A novel, rapid, specific and stability-indicating reverse-phase high-performance liquid chromatography method was developed for the quantitative determination of related compounds, obtained from two different synthetic routes and degradation products of Azilsartan kamedoxomil (AZL). The method was developed by using a YMC-Pack pro C18 (150 × 4.6 mm, 3 µm) column with a mobile phase containing a gradient mobile phase combination. The eluted compounds were measured at wavelength 220 nm. The developed method run time was 25 min, within which AZL and its eight impurities were well separated with minimum 3.0 resolution. The drug substance was subjected to stress conditions of hydrolysis (acid, base and water), oxidation, photolysis, sunlight, 75% relative humidity and thermal degradation as per International Conference on Harmonization (ICH) prescribed stress conditions to ascertain the stability-indicating power of the method. Significant degradation was observed during acid, base, peroxide, water hydrolysis and 75% relative humidity studies. The mass balance of AZL was close to 100% in all the stress condition. The developed method was validated as per the ICH guidelines with respect to specificity, linearity, limit of detection, limit of quantification, accuracy, precision and robustness. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Fully automated method for the liquid chromatographic determination of cyproterone acetate in plasma using restricted access material for sample pre-treatment.

PubMed

Christiaens, B; Chiap, P; Rbeida, O; Cello, D; Crommen, J; Hubert, Ph

2003-09-25

A new fully automated method for the quantitative analysis of an antiandrogenic substance, cyproterone acetate (CPA), in plasma samples has been developed using on-line solid-phase extraction (SPE) prior to the determination by reversed-phase liquid chromatography (LC). The automated method was based on the use of a precolumn packed with an internal-surface reversed-phase packing material (LiChrospher RP-4 ADS) for sample clean-up coupled to LC analysis on an octadecyl stationary phase using a column-switching system. A 200-microL volume of plasma sample was injected directly on the precolumn packed with restricted access material using a mixture of water-acetonitrile (90:10, v/v) as washing liquid. The analyte was then eluted in the back-flush mode with the LC mobile phase which consisted of a mixture of phosphate buffer, pH 7.0-acetonitrile (54:46, v/v). The elution profiles of CPA and blank plasma samples on the precolumn and the time needed for analyte transfer from the precolumn to the analytical column were determined. Different compositions of washing liquid and mobile phase were tested to reduce the interference of plasma endogenous components. UV detection was achieved at 280 nm. Finally, the developed method was validated using a new approach, namely the application of the accuracy profile based on the interval confidence at 90% of the total measurement error (bias+standard deviation). The limit of quantification of cyproterone acetate in plasma was determined at 15 ng mL(-1). The validated method should be applicable to the determination of CPA in patients treated by at least 50 mg day(-1).

Method developments approaches in supercritical fluid chromatography applied to the analysis of cosmetics.

PubMed

Lesellier, E; Mith, D; Dubrulle, I

2015-12-04

Analyses of complex samples of cosmetics, such as creams or lotions, are generally achieved by HPLC. These analyses are often multistep gradients, due to the presence of compounds with a large range of polarity. For instance, the bioactive compounds may be polar, while the matrix contains lipid components that are rather non-polar, thus cosmetic formulations are usually oil-water emulsions. Supercritical fluid chromatography (SFC) uses mobile phases composed of carbon dioxide and organic co-solvents, allowing for good solubility of both the active compounds and the matrix excipients. Moreover, the classical and well-known properties of these mobile phases yield fast analyses and ensure rapid method development. However, due to the large number of stationary phases available for SFC and to the varied additional parameters acting both on retention and separation factors (co-solvent nature and percentage, temperature, backpressure, flow rate, column dimensions and particle size), a simplified approach can be followed to ensure a fast method development. First, suited stationary phases should be carefully selected for an initial screening, and then the other operating parameters can be limited to the co-solvent nature and percentage, maintaining the oven temperature and back-pressure constant. To describe simple method development guidelines in SFC, three sample applications are discussed in this paper: UV-filters (sunscreens) in sunscreen cream, glyceryl caprylate in eye liner and caffeine in eye serum. Firstly, five stationary phases (ACQUITY UPC(2)) are screened with isocratic elution conditions (10% methanol in carbon dioxide). Complementary of the stationary phases is assessed based on our spider diagram classification which compares a large number of stationary phases based on five molecular interactions. Secondly, the one or two best stationary phases are retained for further optimization of mobile phase composition, with isocratic elution conditions or, when necessary, two-step gradient elution. The developed methods were then applied to real cosmetic samples to assess the method specificity, with regards to matrix interferences, and calibration curves were plotted to evaluate quantification. Besides, depending on the matrix and on the studied compounds, the importance of the detector type, UV or ELSD (evaporative light-scattering detection), and of the particle size of the stationary phase is discussed. Copyright © 2015 Elsevier B.V. All rights reserved.

Installation Restoration Program. Phase II: Stage 1 Problem Confirmation Study, Duluth International Airport, Duluth, Minnesota.

DTIC Science & Technology

1984-10-01

8 iii "i t-. Table of Contents (cont.) Section Title Page -APPENDIX A Acronyms, Definitions, Nomenclature and Units of Measure B Scope of Work, Task...Identification/Records Search Phase II - Problem Confirmation and Quantification Phase III - Technology Base Development Phase IV - Corrective Action Only...Problem Identification/Records Search Phase II - Problem Confirmation and Quantification Phase III - Technology Base Development Phase IV - Corrective

Quantification of susceptibility change at high-concentrated SPIO-labeled target by characteristic phase gradient recognition.

PubMed

Zhu, Haitao; Nie, Binbin; Liu, Hua; Guo, Hua; Demachi, Kazuyuki; Sekino, Masaki; Shan, Baoci

2016-05-01

Phase map cross-correlation detection and quantification may produce highlighted signal at superparamagnetic iron oxide nanoparticles, and distinguish them from other hypointensities. The method may quantify susceptibility change by performing least squares analysis between a theoretically generated magnetic field template and an experimentally scanned phase image. Because characteristic phase recognition requires the removal of phase wrap and phase background, additional steps of phase unwrapping and filtering may increase the chance of computing error and enlarge the inconsistence among algorithms. To solve problem, phase gradient cross-correlation and quantification method is developed by recognizing characteristic phase gradient pattern instead of phase image because phase gradient operation inherently includes unwrapping and filtering functions. However, few studies have mentioned the detectable limit of currently used phase gradient calculation algorithms. The limit may lead to an underestimation of large magnetic susceptibility change caused by high-concentrated iron accumulation. In this study, mathematical derivation points out the value of maximum detectable phase gradient calculated by differential chain algorithm in both spatial and Fourier domain. To break through the limit, a modified quantification method is proposed by using unwrapped forward differentiation for phase gradient generation. The method enlarges the detectable range of phase gradient measurement and avoids the underestimation of magnetic susceptibility. Simulation and phantom experiments were used to quantitatively compare different methods. In vivo application performs MRI scanning on nude mice implanted by iron-labeled human cancer cells. Results validate the limit of detectable phase gradient and the consequent susceptibility underestimation. Results also demonstrate the advantage of unwrapped forward differentiation compared with differential chain algorithms for susceptibility quantification at high-concentrated iron accumulation. Copyright © 2015 Elsevier Inc. All rights reserved.

Liquid chromatographic separation and thermodynamic investigation of lorcaserin hydrochloride enantiomers on immobilized amylose-based chiral stationary phase.

PubMed

Wani, Dattatraya V; Rane, Vipul P; Mokale, Santosh N

2018-03-01

A novel liquid chromatographic method was developed for enantiomeric separation of lorcaserin hydrochloride on Chiralpak IA column containing chiral stationary phase immobilized with amylose tris (3.5-dimethylphenylcarbamate) as chiral selector. Baseline separation with resolution greater than 4 was achieved using mobile phase containing mixture of n-hexane/ethanol/methanol/diethylamine (95:2.5:2.5:0.1, v/v/v/v) at a flow rate of 1.2 mL/min. The limit of detection and limit of quantification of the S-enantiomer were found to be 0.45 and 1.5 μg/mL, respectively; the developed method was validated as per ICH guideline. The influence of column oven temperatures studied in the range of 20°C to 50°C on separation was studied; from this, retention, separation, and resolution were investigated. The thermodynamic parameters ΔH°, ΔS°, and ΔG° were evaluated from van't Hoff plots,(Ink' versus 1/T) and used to explain the strength of interaction between enantiomers and immobilized amylose-based chiral stationary phase. © 2017 Wiley Periodicals, Inc.

Simultaneous Quantification of Syringic Acid and Kaempferol in Extracts of Bergenia Species Using Validated High-Performance Thin-Layer Chromatographic-Densitometric Method.

PubMed

Srivastava, Nishi; Srivastava, Amit; Srivastava, Sharad; Rawat, Ajay Kumar Singh; Khan, Abdul Rahman

2016-03-01

A rapid, sensitive, selective and robust quantitative densitometric high-performance thin-layer chromatographic method was developed and validated for separation and quantification of syringic acid (SYA) and kaempferol (KML) in the hydrolyzed extracts of Bergenia ciliata and Bergenia stracheyi. The separation was performed on silica gel 60F254 high-performance thin-layer chromatography plates using toluene : ethyl acetate : formic acid (5 : 4: 1, v/v/v) as the mobile phase. The quantification of SYA and KML was carried out using a densitometric reflection/absorption mode at 290 nm. A dense spot of SYA and KML appeared on the developed plate at a retention factor value of 0.61 ± 0.02 and 0.70 ± 0.01. A precise and accurate quantification was performed using linear regression analysis by plotting the peak area vs concentration 100-600 ng/band (correlation coefficient: r = 0.997, regression coefficient: R(2) = 0.996) for SYA and 100-600 ng/band (correlation coefficient: r = 0.995, regression coefficient: R(2) = 0.991) for KML. The developed method was validated in terms of accuracy, recovery and inter- and intraday study as per International Conference on Harmonisation guidelines. The limit of detection and limit of quantification of SYA and KML were determined, respectively, as 91.63, 142.26 and 277.67, 431.09 ng. The statistical data analysis showed that the method is reproducible and selective for the estimation of SYA and KML in extracts of B. ciliata and B. stracheyi. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

[Development and validation of an HPLC method for the quantification of vitamin A in human milk. Its application to a rural population in Argentina].

PubMed

López, Laura B; Baroni, Andrea V; Rodríguez, Viviana G; Greco, Carola B; de Costa, Sara Macías; de Ferrer, Patricia Ronayne; Rodríguez de Pece, Silvia

2005-06-01

A methodology for the quantification of vitamin A in human milk was developed and validated. Vitamin A levels were assessed in 223 samples corresponding to the 5th, 6th and 7th postpartum months, obtained in the province of Santiago del Estero, Argentina. The samples (500 microL) were saponified with potassium hydroxide/ethanol, extracted with hexane, evaporated to dryness and reconstituted with methanol. A column RP-C18, a mobile phase methanol/water (91:9 v/v) and a fluorescence detector (lambda excitation 330 nm and lambda emition 470 nm) were used for the separation and quantification of vitamin A. The analytical parameters of linearity (r2: 0.9995), detection (0.010 microg/mL) and quantification (0.025 microg/mL) limits, precision of the method (relative standard deviation, RSD = 9.0% within a day and RSD = 8.9% among days) and accuracy (recovery = 83.8%) demonstrate that the developed method allows the quantification of vitamin A in an efficient way. The mean values + standard deviation (SD) obtained for the analyzed samples were 0.60 +/- 0.32; 0.65 +/- 0.33 and 0.61 +/- 0.26 microg/ mL for the 5th, 6th and 7th postpartum months, respectively. There were no significant differences among the three months studied and the values found were similar to those in the literature. Considering the whole population under study, 19.3% showed vitamin A levels less than 0.40 microg/mL, which represents a risk to the children in this group since at least 0.50 microg/mL are necessary to meet the infant daily needs.

Asymmetric flow field-flow fractionation of manufactured silver nanoparticles spiked into soil solution.

PubMed

Koopmans, G F; Hiemstra, T; Regelink, I C; Molleman, B; Comans, R N J

2015-05-01

Manufactured metallic silver nanoparticles (AgNP) are intensively utilized in consumer products and this will inevitably lead to their release to soils. To assess the environmental risks of AgNP in soils, quantification of both their concentration and size in soil solution is essential. We developed a methodology consisting of asymmetric flow field-flow fractionation (AF4) in combination with on-line detection by UV-vis spectroscopy and off-line HR-ICP-MS measurements to quantify the concentration and size of AgNP, coated with either citrate or polyvinylpyrrolidone (PVP), in water extracts of three different soils. The type of mobile phase was a critical factor in the fractionation of AgNP by AF4. In synthetic systems, fractionation of a series of virgin citrate- and PVP-coated AgNP (10-90 nm) with reasonably high recoveries could only be achieved with ultrahigh purity water as a mobile phase. For the soil water extracts, 0.01% (w:v) sodium dodecyl sulfate (SDS) at pH 8 was the key to a successful fractionation of the AgNP. With SDS, the primary size of AgNP in all soil water extracts could be determined by AF4, except for PVP-coated AgNP when clay colloids were present. The PVP-coated AgNP interacted with colloidal clay minerals, leading to an overestimation of their primary size. Similar interactions between PVP-coated AgNP and clay colloids can take place in the environment and facilitate their transport in soils, aquifers, and surface waters. In conclusion, AF4 in combination with UV-vis spectroscopy and HR-ICP-MS measurements is a powerful tool to characterize AgNP in soil solution if the appropriate mobile phase is used. Copyright © 2015 Elsevier B.V. All rights reserved.

Quantification of Acetaminophen and Its Metabolites in Plasma Using UPLC-MS: Doors Open to Therapeutic Drug Monitoring in Special Patient Populations.

PubMed

Flint, Robert B; Mian, Paola; van der Nagel, Bart; Slijkhuis, Nuria; Koch, Birgit C P

2017-04-01

Acetaminophen (APAP, paracetamol) is the most commonly used drug for pain and fever in both the United States and Europe and is considered safe when used at registered dosages. Nevertheless, differences between specific populations lead to remarkable changes in exposure to potentially toxic metabolites. Furthermore, extended knowledge is required on metabolite formation after intoxication, to optimize antidote treatment. Therefore, the authors aimed to develop and validate a quick and easy analytical method for simultaneous quantification of APAP, APAP-glucuronide, APAP-sulfate, APAP-cysteine, APAP-glutathione, APAP-mercapturate, and protein-derived APAP-cysteine in human plasma by ultraperformance liquid chromatography-electrospray ionization-tandem mass spectrometry. The internal standard was APAP-D4 for all analytes. Chromatographic separation was achieved with a reversed-phase Acquity ultraperformance liquid chromatography HSS T3 column with a runtime of only 4.5 minutes per injected sample. Gradient elution was performed with a mobile phase consisting of ammonium acetate, formic acid in Milli-Q ultrapure water or in methanol at flow rate of 0.4 mL/minute. A plasma volume of only 10 μL was required to achieve both adequate accuracy and precision. Calibration curves of all 6 analytes were linear. All analytes were stable for at least 48 hours in the autosampler; the high quality control of APAP-glutathione was stable for 24 hours. The method was validated according to the U.S. Food and Drug Administration guidelines. This method allows quantification of APAP and 6 metabolites, which serves purposes for research, as well as therapeutic drug monitoring. The advantage of this method is the combination of minimal injection volume, a short runtime, an easy sample preparation method, and the ability to quantify APAP and all 6 metabolites.

Simple quantification of phenolic compounds present in the minor fraction of virgin olive oil by LC-DAD-FLD.

PubMed

Godoy-Caballero, M P; Acedo-Valenzuela, M I; Galeano-Díaz, T

2012-11-15

This paper presents the results of the study on the extraction, identification and quantification of a group of important phenolic compounds in virgin olive oil (VOO) samples, obtained from olives of various varieties, by liquid chromatography coupled to UV-vis and fluorescence detection. Sixteen phenolic compounds belonging to different families have been identified and quantified spending a total time of 25 min. The linearity was examined by establishing the external standard calibration curves. Four order linear ranges and limits of detection ranging from 0.02 to 0.6 μg mL(-1) and 0.006 to 0.3 μg mL(-1) were achieved using UV-vis and fluorescence detection, respectively. Regarding the real samples, for the determination of the phenolic compounds in higher concentrations (hydroxytyrosol and tyrosol) a simple liquid-liquid extraction with ethanol was used to make the sample compatible with the mobile phase. Recovery values close to 100% were obtained. However, a previous solid phase extraction with Diol cartridges was necessary to concentrate and separate the minor phenolic compounds of the main interferences. The parameters affecting this step were carefully optimized and, after that, recoveries near 80-100% were obtained for the rest of the studied phenolic compounds. Also, the limits of detection were improved 15 times. Finally, the standard addition method was carried out for each of the analytes and no matrix effect was found, so the quantification of the 16 phenolic compounds from different monovarietal VOO was carried out by using the corresponding external standard calibration plot. Copyright © 2012 Elsevier B.V. All rights reserved.

Direct Determination of Six Cytokinin Nucleotide Monophosphates in Coconut Flesh by Reversed-Phase Liquid Chromatography-Tandem Mass Spectrometry.

PubMed

Cao, Zhao-Yun; Ma, You-Ning; Sun, Li-Hua; Mou, Ren-Xiang; Zhu, Zhi-Wei; Chen, Ming-Xue

2017-11-15

Coconut contains many uncharacterized cytokinins that have important physiological effects in plants and humans. In this work, a method based on liquid chromatography-tandem mass spectrometry was developed for identification and quantification of six cytokinin nucleotide monophosphates in coconut flesh. Excellent separation was achieved using a low-coverage C18 bonded-phase column with an acidic mobile phase, which greatly improved the retention of target compounds. To enable high-throughput analysis, a single-step solid-phase extraction using mixed-mode anion-exchange cartridges was employed for sample preparation. This proved to be an effective method to minimize matrix effects and ensure high selectivity. The limits of detection varied from 0.06 to 0.3 ng/mL, and the limits of quantification ranged from 0.2 to 1.0 ng/mL. The linearity was statistically verified over 2 orders of magnitude, giving a coefficient of determination (R 2 ) greater than 0.9981. The mean recoveries were from 81 to 108%; the intraday precision (n = 6) was less than 11%; and the interday precision (n = 11) was within 14%. The developed method was applied to the determination of cytokinin nucleotide monophosphates in coconut flesh samples, and four of them were successfully identified and quantified. The results showed that trans-zeatin riboside-5'-monophosphate was the dominant cytokinin, with a concentration of 2.7-34.2 ng/g, followed by N 6 -isopentenyladenosine-5'-monophosphate (≤12.9 ng/g), while the concentrations of cis-zeatin riboside-5'-monophosphate and dihydrozeatin riboside-5'-monophosphate were less than 2.2 and 4.9 ng/g, respectively.

Analytical Method Validation of High-Performance Liquid Chromatography and Stability-Indicating Study of Medroxyprogesterone Acetate Intravaginal Sponges

PubMed Central

Batrawi, Nidal; Wahdan, Shorouq; Abualhasan, Murad

2017-01-01

Medroxyprogesterone acetate is widely used in veterinary medicine as intravaginal dosage for the synchronization of breeding cycle in ewes and goats. The main goal of this study was to develop reverse-phase high-performance liquid chromatography method for the quantification of medroxyprogesterone acetate in veterinary vaginal sponges. A single high-performance liquid chromatography/UV isocratic run was used for the analytical assay of the active ingredient medroxyprogesterone. The chromatographic system consisted of a reverse-phase C18 column as the stationary phase and a mixture of 60% acetonitrile and 40% potassium dihydrogen phosphate buffer as the mobile phase; the pH was adjusted to 5.6. The method was validated according to the International Council for Harmonisation (ICH) guidelines. Forced degradation studies were also performed to evaluate the stability-indicating properties and specificity of the method. Medroxyprogesterone was eluted at 5.9 minutes. The linearity of the method was confirmed in the range of 0.0576 to 0.1134 mg/mL (R2 > 0.999). The limit of quantification was shown to be 3.9 µg/mL. Precision and accuracy ranges were found to be %RSD <0.2 and 98% to 102%, respectively. Medroxyprogesterone capacity factor value of 2.1, tailing factor value of 1.03, and resolution value of 3.9 were obtained in accordance with ICH guidelines. Based on the obtained results, a rapid, precise, accurate, sensitive, and cost-effective analysis procedure was proposed for quantitative determination of medroxyprogesterone in vaginal sponges. This analytical method is the only available method to analyse medroxyprogesterone in veterinary intravaginal dosage form. PMID:28469407

Simultaneous determination of ascorbic acid and caffeine in commercial soft drinks using reversed-phase ultraperformance liquid chromatography.

PubMed

Turak, Fatma; Güzel, Remziye; Dinç, Erdal

2017-04-01

A new reversed-phase ultraperformance liquid chromatography method with a photodiode array detector was developed for the quantification of ascorbic acid (AA) and caffeine (CAF) in 11 different commercial drinks consisting of one energy drink and 10 ice tea drinks. Separation of the analyzed AA and CAF with an internal standard, caffeic acid, was performed on a Waters BEH C 18 column (100 mm × 2.1 mm, 1.7 μm i.d.), using a mobile phase consisting of acetonitrile and 0.2M H 3 PO 4 (11:89, v/v) with a flow rate of 0.25 mL/min and an injection volume of 1.0 μL. Calibration graphs for AA and CAF were computed from the peak area ratio of AA/internal standard and CAF/internal standard detected at 244.0 nm and 273.6 nm, respectively. The developed reversed-phase ultraperformance liquid chromatography method was validated by analyzing standard addition samples. The proposed reversed-phase ultraperformance liquid chromatography method gave us successful results for the quantitative analysis of commercial drinks containing AA and CAF substances. Copyright © 2016. Published by Elsevier B.V.

[Simultaneous determination of 7 arsenic species in chicken muscle and chicken liver with high performance liquid chromatography-inductively coupled plasma mass spectrometry].

PubMed

Yang, Lijun; Hu, Qiaoru; Guo, Wei; Liu, Yumin; Song, Xiaohua; Zhang, Pengcheng

2011-05-01

A method for the simultaneous determination of 7 arsenic species was developed with high performance liquid chromatography and inductively coupled plasma mass spectrometry (HPLC-ICP-MS). The sample was extracted with artificial gastric juice. The HPLC separation was performed on an anion analytical column utilizing a gradient elution program of ammonium carbonate and water as the mobile phase. Identification and quantification were achieved by ICP-MS. Good linearities of 7 arsenic species were observed in the range from 1 microg/kg to 50 microg/kg with the correlation coefficients greater than 0.999. The average recoveries of 7 arsenic species spiked at the three levels of 1, 2 and 10 microg/kg ranged from 84.3% to 106.6% with the relative standard deviations of 1.4%-4.2%. The quantification limits of 7 arsenic species were 1 microg/kg. The method was proved to be good reproducibility, high sensitivity and simple preprocessing. This method is suitable for the simultaneous determination of 7 arsenic species in chicken muscle and chicken liver.

Separation and quantification of monoclonal-antibody aggregates by hollow-fiber-flow field-flow fractionation.

PubMed

Fukuda, Jun; Iwura, Takafumi; Yanagihara, Shigehiro; Kano, Kenji

2014-10-01

Hollow-fiber-flow field-flow fractionation (HF5) separates protein molecules on the basis of the difference in the diffusion coefficient, and can evaluate the aggregation ratio of proteins. However, HF5 is still a minor technique because information on the separation conditions is limited. We examined in detail the effect of different settings, including the main-flow rate, the cross-flow rate, the focus point, the injection amount, and the ionic strength of the mobile phase, on fractographic characteristics. On the basis of the results, we proposed optimized conditions of the HF5 method for quantification of monoclonal antibody in sample solutions. The HF5 method was qualified regarding the precision, accuracy, linearity of the main peak, and quantitation limit. In addition, the HF5 method was applied to non-heated Mab A and heat-induced-antibody-aggregate-containing samples to evaluate the aggregation ratio and the distribution extent. The separation performance was comparable with or better than that of conventional methods including analytical ultracentrifugation-sedimentation velocity and asymmetric-flow field-flow fractionation.

Development and validation of a liquid chromatography-isotope dilution tandem mass spectrometry for determination of olanzapine in human plasma and its application to bioavailability study.

PubMed

Zhang, Meng-Qi; Jia, Jing-Ying; Lu, Chuan; Liu, Gang-Yi; Yu, Cheng-Yin; Gui, Yu-Zhou; Liu, Yun; Liu, Yan-Mei; Wang, Wei; Li, Shui-Jun; Yu, Chen

2010-06-01

A simple, reliable and sensitive liquid chromatography-isotope dilution mass spectrometry (LC-ID/MS) was developed and validated for quantification of olanzapine in human plasma. Plasma samples (50 microL) were extracted with tert-butyl methyl ether and isotope-labeled internal standard (olanzapine-D3) was used. The chromatographic separation was performed on XBridge Shield RP 18 (100 mm x 2.1 mm, 3.5 microm, Waters). An isocratic program was used at a flow rate of 0.4 m x min(-1) with mobile phase consisting of acetonitrile and ammonium buffer (pH 8). The protonated ions of analytes were detected in positive ionization by multiple reactions monitoring (MRM) mode. The plasma method, with a lower limit of quantification (LLOQ) of 0.1 ng x mL(-1), demonstrated good linearity over a range of 0.1 - 30 ng x mL(-1) of olanzapine. Specificity, linearity, accuracy, precision, recovery, matrix effect and stability were evaluated during method validation. The validated method was successfully applied to analyzing human plasma samples in bioavailability study.

Novel HPLC Analysis of Hydrocortisone in Conventional and Controlled-Release Pharmaceutical Preparations.

PubMed

Adi-Dako, Ofosua; Oppong Bekoe, Samuel; Ofori-Kwakye, Kwabena; Appiah, Enoch; Peprah, Paul

2017-01-01

An isocratic sensitive and precise reverse phase high-performance liquid chromatography (RP-HPLC) method was developed and validated for the determination and quantification of hydrocortisone in controlled-release and conventional (tablets and injections) pharmaceutical preparations. Chromatographic separation was achieved on an ODS (C18), 5  μ m, 4.6 × 150 mm, with an isocratic elution using a freshly prepared mobile phase of composition methanol : water : acetic acid (60 : 30 : 10, v/v/v) at a flow rate of 1.0 ml/min. The detection of the drug was successfully achieved at a wavelength of 254 nm. The retention time obtained for the drug was 2.26 min. The proposed method produced linear detectable responses in the concentration range of 0.02 to 0.4 mg/ml of hydrocortisone. High recoveries of 98-101% were attained at concentration levels of 80%, 100%, and 120%. The intraday and interday precision (RSD) were 0.19-0.55% and 0.33-0.71%, respectively. A comparison of hydrocortisone analyses data from the developed method and the official USP method showed no significant difference ( p > 0.05) at a 95% confidence interval. The method was successfully applied to the determination and quantification of hydrocortisone in six controlled-release and fifteen conventional release pharmaceutical preparations.

Novel HPLC Analysis of Hydrocortisone in Conventional and Controlled-Release Pharmaceutical Preparations

PubMed Central

Oppong Bekoe, Samuel; Appiah, Enoch; Peprah, Paul

2017-01-01

An isocratic sensitive and precise reverse phase high-performance liquid chromatography (RP-HPLC) method was developed and validated for the determination and quantification of hydrocortisone in controlled-release and conventional (tablets and injections) pharmaceutical preparations. Chromatographic separation was achieved on an ODS (C18), 5 μm, 4.6 × 150 mm, with an isocratic elution using a freshly prepared mobile phase of composition methanol : water : acetic acid (60 : 30 : 10, v/v/v) at a flow rate of 1.0 ml/min. The detection of the drug was successfully achieved at a wavelength of 254 nm. The retention time obtained for the drug was 2.26 min. The proposed method produced linear detectable responses in the concentration range of 0.02 to 0.4 mg/ml of hydrocortisone. High recoveries of 98–101% were attained at concentration levels of 80%, 100%, and 120%. The intraday and interday precision (RSD) were 0.19–0.55% and 0.33–0.71%, respectively. A comparison of hydrocortisone analyses data from the developed method and the official USP method showed no significant difference (p > 0.05) at a 95% confidence interval. The method was successfully applied to the determination and quantification of hydrocortisone in six controlled-release and fifteen conventional release pharmaceutical preparations. PMID:28660092

Quantification and characterization of alkaloids from roots of Rauwolfia serpentina using ultra-high performance liquid chromatography-photo diode array-mass spectrometry.

PubMed

Sagi, Satyanarayanaraju; Avula, Bharathi; Wang, Yan-Hong; Khan, Ikhlas A

2016-01-01

A new UHPLC-UV method has been developed for the simultaneous analysis of seven alkaloids [ajmaline (1), yohimbine (2), corynanthine (3), ajmalicine (4), serpentine (5), serpentinine (6), and reserpine (7)] from the root samples of Rauwolfia serpentina (L.) Benth. ex Kurz. The chromatographic separation was achieved using a reversed phase C18 column with a mobile phase of water and acetonitrile, both containing 0.05% formic acid. The seven compounds were completely separated within 8 min at a flow rate of 0.2 mL/min with a 2-μL injection volume. The method is validated for linearity, accuracy, repeatability, limits of detection (LOD), and limits of quantification (LOQ). Seven plant samples and 21 dietary supplements claiming to contain Rauwolfia roots were analyzed and content of total alkaloids (1-7) varied, namely, 1.57-12.1 mg/g dry plant material and 0.0-4.5 mg/day, respectively. The results indicated that commercial products are of variable quality. The developed analytical method is simple, economic, fast, and suitable for quality control analysis of Rauwolfia samples and commercial products. The UHPLC-QToF-mass spectrometry with electrospray ionization (ESI) interface method is described for the confirmation and characterization of alkaloids from plant samples. This method involved the detection of [M + H](+) or M(+) ions in the positive mode.

[Influences of ion-suppressors on retention behaviors of nine food additives in reversed-phase high performance liquid chromatographic separation].

PubMed

Zhao, Yonggang; Chen, Xiaohong; Li, Xiaoping; Yao, Shanshan; Jin, Micong

2011-10-01

The influences of ion-suppressors on retention behaviors of nine food additives, i.e., acesulfame, saccharin, caffeine, aspartame, benzoic acid, sorbic acid, stevioside, dehydroacetic acid and neotame in reversed-phase high performance liquid chromatographic (RP-HPLC) separation were investigated. The organic modification effects of acids, i. e. , trifluoroacetic acid (TFA) and buffer salts, i. e. , TFA-ammonium acetate (AmAc) were studied emphatically. The relationships between retention factors of solutes and volume percentages of ion-suppressors in the mobile phase systems of acetonitrile-TFA aqueous solution and acetonitrile-TFA-AmAc aqueous solution were quantitatively established, separately. The separation of nine food additives was completed by a gradient elution with acetonitrile-TFA (0.01%, v/v)-AmAc (2. 5 mmol/L) aqueous solution as the mobile phases. An RP-HPLC method was established for the simultaneous determination of nine food additives in red wine. In the range of 10. 0 - 100. 0 mg/L, nine food additives showed good linearity with the correlation coefficients ( r2 ) larger than 0. 999 1. The limits of detection (LODs) were in the range of 0. 33 - 2. 36 mg/L and the limits of quantification (LOQs) were in the range of 1. 11 - 7. 80 mg/L. The spiked recoveries were between 87. 61% and 108. 4% with the relative standard deviations (RSDs) of 2. 2% -9. 4%. These results are of referential significance for the rapid establishment and accu- rate optimization of RP-HPLC separation for the simultaneous determination of food additives in other foods.

Analysis of nine food additives in red wine by ion-suppression reversed-phase high-performance liquid chromatography using trifluoroacetic acid and ammonium acetate as ion-suppressors.

PubMed

Zhao, Yong-Gang; Chen, Xiao-Hong; Yao, Shan-Shan; Pan, Sheng-Dong; Li, Xiao-Ping; Jin, Mi-Cong

2012-01-01

A reversed-phase high-performance liquid chromatography (RP-HPLC) method was developed for the simultaneous determination of nine food additives, i.e., acesulfame, saccharin, caffeine, aspartame, benzoic acid, sorbic acid, stevioside, dehydroacetic acid and neotame in red wine. The effects of ion-suppressors, i.e., trifluoroacetic acid (TFA) and ammonium acetate (AmAc) on retention behavior of nine food additives in RP-HPLC separation were discussed in detail. The relationships between retention factors of solutes and volume percent of ion-suppressors in the mobile-phase systems of acetonitrile-TFA aqueous solution and acetonitrile-TFA-AmAc aqueous solution were quantitatively established, respectively. The results showed that the ion suppressors had not only an ion suppression effect, but also an organic modification effect on the acidic analytes. The baseline separation of nine food additives was completed by a gradient elution with acetonitrile-TFA(0.01%, v/v)-AmAc(2.5 mmol L(-1)) aqueous solution as the mobile phase. The recoveries were between 80.2 - 99.5% for all analytes with RSDs in the range of 1.5 - 8.9%. The linearities were in the range of 0.2 - 100.0 mg L(-1) with determination coefficients (r(2)) higher than 0.9991 for all analytes. The limits of quantification (LOQs) were between 0.53 - 0.99 mg L(-1). The applicability of the proposed method to detect and quantify food additives has been demonstrated in the analysis of 30 real samples.

Simultaneous quantification of voriconazole and posaconazole in human plasma by high-performance liquid chromatography with ultra-violet detection.

PubMed

Chhun, Stéphanie; Rey, Elisabeth; Tran, Agnes; Lortholary, Olivier; Pons, Gérard; Jullien, Vincent

2007-06-01

A sensitive and selective high-performance liquid chromatographic (HPLC) method with ultra-violet detection has been developed and validated for the simultaneous determination of posaconazole and voriconazole, two systemic anti-fungal agents. An internal standard diazepam was added to 100 microL of human plasma followed by 3 mL of hexane-methylene chloride (70:30, v/v). The organic layer was evaporated to dryness and the residue was reconstituted with 100 microL of mobile phase before being injected in the chromatographic system. The compounds were separated on a C8 column using sodium potassium phosphate buffer (0.04 M, pH 6.0): acetonitrile:ultrapure water (45:52.5:2.5, v/v/v) as mobile phase. All compounds were detected at a wavelength of 255 nm. The assay was linear and validated over the range 0.2-10.0 mg/L for voriconazole and 0.05-10.0 mg/L for posaconazole. The biases were comprised between -3 and 5% for voriconazole and -2 and 8% for posaconazole. The intra- and inter-day precisions of the method were lower than 8% for the routine quality control (QC). The mean recovery was 98% for voriconazole and 108% for posaconazole. This method provides a useful tool for therapeutic drug monitoring.

Liquid chromatography-mass spectrometry method for the quantification of tamoxifen and its metabolite 4-hydroxytamoxifen in rat plasma: application to interaction study with biochanin A (an isoflavone).

PubMed

Singh, Sheelendra Pratap; Wahajuddin; Ali, Mushir M; Kohli, Kanchan; Jain, Girish Kumar

2011-10-01

Tamoxifen is the agent of choice for the treatment of estrogen receptor-positive breast cancer. Tamoxifen is a substrate of P-glycoprotein (P-gp) and microsomal cytochrome P450 (CYP) 3A, and biochanin A (BCA) is an inhibitor of P-gp and CYP3A. Hence, it could be expected that BCA would affect the pharmacokinetics of tamoxifen. In the present study we have developed and validated a simple, sensitive and specific LC-ESI-MS/MS method for the simultaneous quantification of tamoxifen and its metabolite 4-hydroxytamoxifen with 100 μL rat plasma using centchroman as an internal standard (IS). Tamoxifen, 4-hydroxytamoxifen and IS were separated on a Supelco Discovery C18 (4.6 mm × 50 mm, 5.0 μm) column under isocratic condition using 0.0 1M ammonium acetate (pH 4.5):acetonitrile (10:90, v/v) as a mobile phase. The mobile phase was delivered at a flow rate of 0.8 mL/min. The method was proved to be accurate and precise at linearity range of 0.78-200 ng/mL with a correlation coefficient (r) of ≥ 0.996. The intra- and inter-day assay precision ranged from 1.89 to 8.54% and 3.97 to 10.26%, respectively; and intra- and inter-day assay accuracy was between 87.63 and 109.06% and 96 and 103.89%, respectively for both the analytes. The method was successfully applied to study the effect of oral co-administration of BCA (an isoflavone) on the pharmacokinetics of tamoxifen and 4-hydroxytamoxifen in female rats. The coadministration of BCA caused no significant changes in the pharmacokinetics of tamoxifen and 4-hydroxytamoxifen. However, the peak plasma concentration (C(max)) of 4-hydroxytamoxifen in BCA pretreated rats was significantly (P<0.05) lower than those from control group. Copyright © 2011 Elsevier B.V. All rights reserved.

Validated UPLC/MS/MS assay for quantitative bioanalysis of elbasvir in rat plasma and application to pharmacokinetic study.

PubMed

Liu, Haiyan; Xu, Hongjiang; Song, Wei; Zhang, Yinsheng; Yu, Sen; Huang, Xin

2016-03-15

Rapid, sensitive, selective and accurate ultra performance liquid chromatography with tandem mass spectrometry (UPLC-MS/MS) method was developed and validated for the quantification of elbasvir (ELB) in rat plasma with deuterated elbasvir (ELB-D6) as internal standard (IS).Sample preparation was done by protein precipitation using acetonitrile containing 50 ng/mL IS. Chromatographic separation was achieved by an UPLC BEH C18 column (2.1 mm × 50 mm, 1.7 μm) column with a gradient mobile phase consisting of acetonitrile-water (containing 5.0mM ammonium acetate with 0.01% acetic acid, pH 4.5) as mobile phase at a flow rate of 0.3 mL/min for 3 min. ELB was monitored using positive electrospray triple quadrupole mass spectrometer (Waters Xevo TQ-S) via multiple reaction monitoring (MRM) mode. The monitored transitions were set at m/z 882.51→656.42 and m/z 888.49→662.43 for ELB and ELB-D6, respectively. The achieved lower limit of quantification was 1.0 ng/mL. The validated method had an excellent linearity in the range of 1.0-2000 ng/mL (r(2)>0.996). Recovery efficiency at three levels QC concentrations of 2.0 (low), 160 (medium) and 1600 (high) ng/mLwas in the range of 98.29-106.40% for ELB. Matrix effect was found to be minimal. The intra- and inter-day precisions were less than 7.01%. The intra- and inter-day accuracies were determined to be within ±6.23% for all accuracy measurements. The validated simple and rapid UPLC-MS/MS method was successfully used to the pharmacokinetics study of ELB in rats, providing its applicability in relevant preclinical studies. Copyright © 2016 Elsevier B.V. All rights reserved.

Simultaneous determination of atorvastatin calcium and ramipril in capsule dosage forms by high-performance liquid chromatography and high-performance thin layer chromatography.

PubMed

Panchal, Hiral J; Suhagia, Bhanubhai N

2010-01-01

Two simple and accurate methods to determine atorvastatin calcium and ramipril in capsule dosage forms were developed and validated using HPLC and HPTLC. The HPLC separation was achieved on a Phenomenex Luna C18 column (250 x 4.6 mm id, 5 microm) in the isocratic mode using 0.1% phosphoric acid-acetonitrile (38 + 62, v/v), pH 3.5 +/- 0.05, mobile phase at a flow rate of 1 ml/min. The retention times were 6.42 and 2.86 min for atorvastatin calcium and ramipril, respectively. Quantification was achieved with a photodiode array detector set at 210 nm over the concentration range of 0.5-5 microg/mL for each, with mean recoveries (at three concentration levels) of 100.06 +/- 0.49% and 99.95 +/- 0.63% RSD for atorvastatin calcium and ramipril, respectively. The HPTLC separation was achieved on silica gel 60 F254 HPTLC plates using methanol-benzene-glacial acetic acid (19.6 + 80.0 + 0.4, v/v/v) as the mobile phase. The Rf values were 0.40 and 0.20 for atorvastatin calcium and ramipril, respectively. Quantification was achieved with UV densitometry at 210 nm over the concentration range of 50-500 ng/spot for each, with mean recoveries (at three concentration levels) of 99.98 +/- 0.75% and 99.87 +/- 0.83% RSD for atorvastatin calcium and ramipril, respectively. Both methods were validated according to International Conference on Harmonization guidelines and found to be simple, specific, accurate, precise, and robust. The mean assay percentages for atorvastatin calcium and ramipril were 99.90 and 99.55% for HPLC and 99.91 and 99.47% for HPTLC, respectively. The methods were successfully applied for the determination of atorvastatin calcium and ramipril in capsule dosage forms without any interference from common excipients.

Development and Validation of a Reversed Phase HPLC Method for Determination of Anacardic Acids in Cashew (Anacardium occidentale) Nut Shell Liquid.

PubMed

Oiram Filho, Francisco; Alcântra, Daniel Barbosa; Rodrigues, Tigressa Helena Soares; Alexandre E Silva, Lorena Mara; de Oliveira Silva, Ebenezer; Zocolo, Guilherme Julião; de Brito, Edy Sousa

2018-04-01

Cashew nut shell liquid (CNSL) contains phenolic lipids with aliphatic chains that are of commercial interest. In this work, a chromatographic method was developed to monitor and quantify anacardic acids (AnAc) in CNSL. Samples containing AnAc were analyzed on a high-performance liquid chromatograph coupled to a diode array detector, equipped with a reversed phase C18 (150 × 4.6 mm × 5 μm) column using acetonitrile and water as the mobile phase both acidified with acetic acid to pH 3.0 in an isocratic mode (80:20:1). The chromatographic method showed adequate selectivity, as it could clearly separate the different AnAc. To validate this method, AnAc triene was used as an external standard at seven different concentrations varying from 50 to 1,000 μg mL-1. The Student's t-test and F-test were applied to ensure high confidence for the obtained data from the analytical calibration curve. The results were satisfactory with respect to intra-day (relative standard deviation (RSD) = 0.60%) and inter-day (RSD = 0.67%) precision, linearity (y = 2,670.8x - 26,949, r2 > 0.9998), system suitability for retention time (RSD = 1.02%), area under the curve (RSD = 0.24%), selectivity and limits of detection (19.8 μg mg-1) and quantification (60.2 μg mg-1). The developed chromatographic method was applied for the analysis of different CNSL samples, and it was deemed suitable for the quantification of AnAc.

[Determination of 11 anabolic hormones in fish tissue by multi-function impurity adsorption solid-phase extraction-ultrafast liquid chromatography-tandem mass spectrometry].

PubMed

Yao, Shanshan; Zhao, Yonggang; Li, Xiaoping; Chen, Xiaohong; Jin, Micong

2012-06-01

A method was developed for the determination of 11 anabolic hormones (boldenone, androstenedione, nandrolone, methandrostenolone, methyltestosterone, testosterone, testosterone acetate, trenbolone, testosterone propionate, stanozolol, fluoxymesterone) in fish by multi-function impurity adsorption solid-phase extraction-ultrafast liquid chromatography-tandem mass spectrometry. After the sample was extracted by methanol, the extract was cleaned-up quickly by C18 adsorbent, neutral alumina adsorbent and amino-functionalized nano-adsorbent. The separation was performed on a Shim-Pack XR-ODS II column (100 mm x 2.0 mm, 2.2 microm) using the mobile phases of 0.1% (v/v) formic acid in acetonitrile and 0.1% (v/v) formic acid solution in a gradient elution mode. The identification and quantification were achieved by using electrospray ionization in positive ion mode (ESI+) in multiple reaction monitoring (MRM) mode. The matrix-matched external standard calibration curves were used for quantitative determination. The results showed that the calibration curves were in good linearity for the eleven analytes with the correlation coefficients (r) more than 0.999. The limits of detection (LODs, S/N > 3) for the 11 anabolic hormones were from 0.03 microg/kg to 0.4 microg/kg and the limits of quantification (LOQs, S/N > 10) were from 0.1 microg/kg to 1.5 microg/kg. The average recoveries ranged from 80.9% to 98.1% with the relative standard deviations between 5.2% and 11.5%. The method is simple, rapid, sensitive, accurate and suitable for the quantitative determination and confirmation of the 11 anabolic hormones in fish.

[Analysis of sulfonamide residues in pork and chicken by high performance liquid chromatography coupled with solid-phase extraction using multiwalled carbon nanotubes as adsorbent].

PubMed

Zhao, Haixiang; Liu, Haiping; Yan, Zaoying

2014-03-01

A multi-residue analytical method based on solid-phase extraction (SPE) with multiwalled carbon nanotubes (MWCNTs) as sorbent was developed. The determination of the sulfonamides (SAs) in pork and chicken was carried out by high performance liquid chromatography-ultraviolet detection (HPLC-UV). The clean-up conditions were optimized. The analytes were extracted by acetonitril and cleaned-up by MWCNTs SPE cartridge. The extract was redissolved with the Na2HPO4 buffer (pH 5.5-6.0) for loading, and was washed with acetone-hexane (5:95, v/v), then eluted with acetone-dichloromethane (1:1, v/v) from the column. The mobile phase used in the chromatographic separation consisted of a binary mixture of acetonitrile and 50 mmol/L NaH2PO4 with the volume ratio of 7:3. A wide linear range was 0.01-1.00 mg/L with the correlation coefficients above 0.998. The limits of detection (S/N = 3) were 0.003 mg/L, and the limits of quantification (S/N = 10) were 0.01 mg/L. The average recoveries were over 70% for the nine SAs in the spiked range of 0.02-0.2 mg/kg, with the relative standard deviations (RSDs) lower than 8%. This study indicated that the MWCNTs SPE cartridge is efficient for the clean-up of the SAs in animal tissues or products, and the method is simple, accurate and suitable for the quantification of the SAs residues.

Validated method for determination of bromopride in human plasma by liquid chromatography--electrospray tandem mass spectrometry: application to the bioequivalence study.

PubMed

Nazare, P; Massaroti, P; Duarte, L F; Campos, D R; Marchioretto, M A M; Bernasconi, G; Calafatti, S; Barros, F A P; Meurer, E C; Pedrazzoli, J; Moraes, L A B

2005-09-01

A simple, sensitive and specific liquid chromatography-tandem mass spectrometry method for the quantification of bromopride I in human plasma is presented. Sample preparation consisted of the addition of procainamide II as the internal standard, liquid-liquid extraction in alkaline conditions using hexane-ethyl acetate (1 : 1, v/v) as the extracting solvent, followed by centrifugation, evaporation of the solvent and sample reconstitution in acetonitrile. Both I and II (internal standard, IS) were analyzed using a C18 column and the mobile-phase acetonitrile-water (formic acid 0.1%). The eluted compounds were monitored using electrospray tandem mass spectrometry. The analyses were carried out by multiple reaction monitoring (MRM) using the parent-to-daughter combinations of m/z 344.20 > 271.00 and m/z 236.30 > 163.10. The areas of peaks from analyte and IS were used for quantification of I. The achieved limit of quantification was 1.0 ng/ml and the assay exhibited a linear dynamic range of 1-100.0 ng/ml and gave a correlation coefficient (r) of 0.995 or better. Validation results on linearity, specificity, accuracy, precision and stability, as well as application to the analysis of samples taken up to 24 h after oral administration of 10 mg of I in healthy volunteers demonstrated the applicability to bioequivalence studies.

A RP-HPLC method for quantification of diclofenac sodium released from biological macromolecules.

PubMed

Bhattacharya, Shiv Sankar; Banerjee, Subham; Ghosh, Ashoke Kumar; Chattopadhyay, Pronobesh; Verma, Anurag; Ghosh, Amitava

2013-07-01

Interpenetrating network (IPN) microbeads of sodium carboxymethyl locust bean gum (SCMLBG) and sodium carboxymethyl cellulose (SCMC) containing diclofenac sodium (DS), a nonsteroidal anti-inflammatory drug, were prepared by single water-in-water (w/w) emulsion gelation process using AlCl3 as cross-linking agent in a complete aqueous environment. Pharmacokinetic study of these IPN microbeads was then carried out by a simple and feasible high-performance liquid chromatographic method with UV detection which was developed and validated for the quantification of diclofenac sodium in rabbit plasma. The chromatographic separation was carried out in a Hypersil BDS, C18 column (250 mm × 4.6 mm; 5 m). The mobile phase was a mixture of acetonitrile and methanol (70:30, v/v) at a flow rate of 1.0 ml/min. The UV detection was set at 276 nm. The extraction recovery of diclofenac sodium in plasma of three quality control (QC) samples was ranged from 81.52% to 95.29%. The calibration curve was linear in the concentration range of 20-1000 ng/ml with the correlation coefficient (r(2)) above 0.9951. The method was specific and sensitive with the limit of quantification of 20 ng/ml. In stability tests, diclofenac sodium in rabbit plasma was stable during storage and assay procedure. Copyright © 2013. Published by Elsevier B.V.

Overcoming the response plateau in multiple myeloma: a novel bortezomib-based strategy for secondary induction and high-yield CD34+ stem cell mobilization.

PubMed

Niesvizky, Ruben; Mark, Tomer M; Ward, Maureen; Jayabalan, David S; Pearse, Roger N; Manco, Megan; Stern, Jessica; Christos, Paul J; Mathews, Lena; Shore, Tsiporah B; Zafar, Faiza; Pekle, Karen; Xiang, Zhaoying; Ely, Scott; Skerret, Donna; Chen-Kiang, Selina; Coleman, Morton; Lane, Maureen E

2013-03-15

This phase II study evaluated bortezomib-based secondary induction and stem cell mobilization in 38 transplant-eligible patients with myeloma who had an incomplete and stalled response to, or had relapsed after, previous immunomodulatory drug-based induction. Patients received up to six 21-day cycles of bortezomib plus dexamethasone, with added liposomal doxorubicin for patients not achieving partial response or better by cycle 2 or very good partial response or better (≥VGPR) by cycle 4 (DoVeD), followed by bortezomib, high-dose cyclophosphamide, and filgrastim mobilization. Gene expression/signaling pathway analyses were conducted in purified CD34+ cells after bortezomib-based mobilization and compared against patients who received only filgrastim ± cyclophosphamide. Plasma samples were similarly analyzed for quantification of associated protein markers. The response rate to DoVeD relative to the pre-DoVeD baseline was 61%, including 39% ≥ VGPR. Deeper responses were achieved in 10 of 27 patients who received bortezomib-based mobilization; postmobilization response rate was 96%, including 48% ≥ VGPR, relative to the pre-DoVeD baseline. Median CD34+ cell yield was 23.2 × 10(6) cells/kg (median of 1 apheresis session). After a median follow-up of 46.6 months, median progression-free survival was 47.1 months from DoVeD initiation; 5-year overall survival rate was 76.4%. Grade ≥ 3 adverse events included thrombocytopenia (13%), hand-foot syndrome (11%), peripheral neuropathy (8%), and neutropenia (5%). Bortezomib-based mobilization was associated with modulated expression of genes involved in stem cell migration. Bortezomib-based secondary induction and mobilization could represent an alternative strategy for elimination of tumor burden in immunomodulatory drug-resistant patients that does not impact stem cell yield.

Predicting ESI/MS Signal Change for Anions in Different Solvents.

PubMed

Kruve, Anneli; Kaupmees, Karl

2017-05-02

LC/ESI/MS is a technique widely used for qualitative and quantitative analysis in various fields. However, quantification is currently possible only for compounds for which the standard substances are available, as the ionization efficiency of different compounds in ESI source differs by orders of magnitude. In this paper we present an approach for quantitative LC/ESI/MS analysis without standard substances. This approach relies on accurately predicting the ionization efficiencies in ESI source based on a model, which uses physicochemical parameters of analytes. Furthermore, the model has been made transferable between different mobile phases and instrument setups by using a suitable set of calibration compounds. This approach has been validated both in flow injection and chromatographic mode with gradient elution.

Installation Restoration Program. Phase II--Confirmation/Quantification. Stage 1.

DTIC Science & Technology

1985-03-01

four phases. Phase I, Initial Assessment/ Records Search, is designed to identify possible hazardous waste contami- nated sites and potential...7 71 -. - - IL’ -, 1% 33 AihlIII Is 33 n~iL t iiC UII! ii CL C LU 1-3, Phase II, Confirmation and Quantification, is designed to confirm the...additional monitoring data upon which design of mitigative actions are based. In Phase III, Technology Base Development, appropriate technology is selected and

HPLC separation of acetaminophen and its impurities using a mixed-mode reversed-phase/cation exchange stationary phase.

PubMed

Călinescu, Octavian; Badea, Irinel A; Vlădescu, Luminiţa; Meltzer, Viorica; Pincu, Elena

2012-04-01

Determination of acetaminophen and its main impurities: 4-nitrophenol, 4'-chloroacetanilide, as well as 4-aminophenol and its degradation products, p-benzoquinone and hydroquinone has been developed and validated by a new high-performance liquid chromatography method. Chromatographic separation has been obtained on a Hypersil Duet C18/SCX column, using gradient elution, with a mixture of phosphate buffer (pH = 4.88) and methanol as a mobile phase. Analysis time did not exceed 14.5 min and good resolutions, peak shapes and asymmetries have resulted. The linearity of the method has been tested in the range of 5.0-60 µg/mL for acetaminophen and 0.5-6 µg/mL for the other compounds. The limits of detection and quantification have been also established to be lower than 0.1 µg/mL and 0.5 µg/mL, respectively. The method has been successfully applied for the analysis of commercial acetaminophen preparations. © The Author [2012]. Published by Oxford University Press. All rights reserved.

Validated LC-MS-MS Method for Multiresidual Analysis of 13 Illicit Phenethylamines in Amniotic Fluid.

PubMed

Burrai, Lucia; Nieddu, Maria; Carta, Antonio; Trignano, Claudia; Sanna, Raimonda; Boatto, Gianpiero

2016-04-01

A multi-residue analytical method was developed for the determination in amniotic fluid (AF) of 13 illicit phenethylamines, including 12 compounds never investigated in this matrix before. Samples were subject to solid-phase extraction using; hydrophilic-lipophilic balance cartridges which gave good recoveries and low matrix effects on analysis of the extracts. The quantification was performed by liquid chromatography electrospray tandem mass spectrometry. The water-acetonitrile mobile phase containing 0.1% formic acid, used with a C18 reversed phase column, provided adequate separation, resolution and signal-to-noise ratio for the analytes and the internal standard. The final optimized method was validated according to international guidelines. A monitoring campaign to assess fetal exposure to these 13 substances of abuse has been performed on AF test samples obtained from pregnant women. All mothers (n = 194) reported no use of drugs of abuse during pregnancy, and this was confirmed by the analytical data. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

ICH guidance in practice: validated reversed-phase HPLC method for the determination of active mangiferin from extracts of Mangifera indica Linn.

PubMed

Gowda, Nagaraj; Kumar, Pradeep; Panghal, Surender; Rajshree, Mashru

2010-02-01

This study presents the development and validation of a reversed-phase liquid chromatographic method for the determination of mangiferin (MGN) in alcoholic extracts of mangifera indica. A Lichrospher 100 C(18)-ODS (250 x 4.6 mm, 5 microm size) (Merck, Whitehouse Station, NJ) prepacked column and a mobile phase of potassium dihydrogen orthophosphate (0.01M) pH 2.7 +/- 0.2-acetonitrile (15:85, v/v) with the flow rate of 1 mL/min was used. MGN detection was achieved at a wavelength monitored at 254 nm with SPD-M 10A vp PDA detector or SPD 10AD vp UV detector in combination with class LC 10A software. The proposed method was validated as prescribed by International Conference on Harmonization (ICH) with respect to linearity, specificity, accuracy, precision, stability, and quantification. The method validation was realized using alcoholic extracts and raw materials of leaves and barks. All the validation parameters were within the acceptable limits, and the developed analytical method can successfully be applied for MGN determination.

Installation Restoration Program. Confirmation/Quantification Stage 1. Phase 2

DTIC Science & Technology

1985-03-07

INSTALLATION RESTORATION PROGRAM i0 PHASE II - CONFIRMATION/QUANTIFICATION 0STAGE 1 KIRTLAND AFB KIRTLAND AFB, NEW MEXICO 87117 IIl PREPARED BY SCIENCE...APPLICATIONS INTERNATIONAL CORPORATION 505 MARQUETTE NW, SUITE 1200 ALBUQUERQUE, NEW MEXICO 871021 5MARCH 1985 FINAL REPORT FROM FEB 1983 TO MAR 1985...QUANTIFICATION STAGE 1 i FINAL REPORT FOR IKIRTLAND AFB KIRTLAND AFB, NEW MEXICO 87117U HEADQUARTERS MILITARY AIRLIFT COMMAND COMMAND SURGEON’S OFFICE (HQ MAC

Simultaneous quantification by HPLC of the phenolic compounds for the crude drug of Prunus serotina subsp. capuli.

PubMed

Rivero-Cruz, Blanca

2014-08-01

Prunus serotina Ehrenb. subsp. capuli (Cav.) McVaugh (Rosaceae), commonly known as "capulin", is a native North American tree, commercialized and used in folk medicine for the treatment of the hypertension, gastrointestinal illnesses, and cough. This work developed a suitable HPLC method for quantifying the major active constituents of the infusion of P. serotina, the most important preparation consumed by populations around the world. The analytical method was performed using a Fortis-RP column (150 mm × 4.6 mm; film thickness 5 µm). The mobile phase consisted of an isocratic acetate buffer solution (pH 2.7; A) and methanol (B) (65:35 v/v) at a flow rate of 1.0 mL min(-1). The proposed method was applied to the quantification of 1-3 in several samples of the leaves of P. serotina. The results indicated that amounts of 1-3 in the samples analyzed are uniform, and greater amounts of chlorogenic acid (2; 479.9 ± 33.6 µg g(-1), dry matter) along with hyperoside (1; 185.7 ± 55.3 µg g(-1), dry matter) were present. On the other hand, benzaldehyde (3; 118.2 ± 12.1 µg g(-1) dry matter) was found to be in lower concentration. A simple, sensitive, precise, and reproducible HPLC method for the simultaneous quantification of 1-3 in P. serotina was developed and validated. This is the first report on the quantification of 1-3 as active principles, and compound 1 was selected as a marker of P. serotina, which could be useful to guarantee the quality of the crude drug and herbal products.

Quantification of 4'-geranyloxyferulic acid, a new natural colon cancer chemopreventive agent, by HPLC-DAD in grapefruit skin extract.

PubMed

Genovese, S; Epifano, F; Carlucci, G; Marcotullio, M C; Curini, M; Locatelli, M

2010-10-10

Oxyprenylated natural products (isopentenyloxy-, geranyloxy- and the less spread farnesyloxy-compounds and their biosynthetic derivatives) represent a family of secondary metabolites that have been consider for years merely as biosynthetic intermediates of the most abundant C-prenylated derivatives. Many of the isolated oxyprenylated natural products were shown to exert in vitro and in vivo remarkable anti-cancer and anti-inflammatory effects. 4'-Geranyloxyferulic acid [3-(4'-geranyloxy-3'-methoxyphenyl)-2-trans-propenoic] has been discovered as a valuable chemopreventive agent of several types of cancer. After development of a high yield and "eco-friendly" synthetic scheme of this secondary metabolite, starting from cheap and non-toxic reagents and substrates, we developed a new HPLC-DAD method for its quantification in grapefruit skin extract. A preliminary study on C18 column showed the separation between GOFA and boropinic acid (having the same core but with an isopentenyloxy side chain), used as internal standard. The tested column were thermostated at 28+/-1 degrees C and the separation was achieved in gradient condition at a flow rate of 1 mL/min with a starting mobile phase of H(2)O:methanol (40:60, v/v, 1% formic acid). The limit of detection (LOD, S/N=3) was 0.5 microg/mL and the limit of quantification (LOQ, S/N=10) was 1 microg/mL. Matrix-matched standard curves showed linearity up to 75 microg/mL. In the analytical range the precision (RSD%) values were

Simultaneous quantification of selective serotonin reuptake inhibitors and metabolites in human plasma by liquid chromatography-electrospray mass spectrometry for therapeutic drug monitoring.

PubMed

Ansermot, Nicolas; Brawand-Amey, Marlyse; Eap, Chin B

2012-02-15

A simple and sensitive liquid chromatography-electrospray ionization mass spectrometry method was developed for the simultaneous quantification in human plasma of all selective serotonin reuptake inhibitors (citalopram, fluoxetine, fluvoxamine, paroxetine and sertraline) and their main active metabolites (desmethyl-citalopram and norfluoxetine). A stable isotope-labeled internal standard was used for each analyte to compensate for the global method variability, including extraction and ionization variations. After sample (250μl) pre-treatment with acetonitrile (500μl) to precipitate proteins, a fast solid-phase extraction procedure was performed using mixed mode Oasis MCX 96-well plate. Chromatographic separation was achieved in less than 9.0min on a XBridge C18 column (2.1×100mm; 3.5μm) using a gradient of ammonium acetate (pH 8.1; 50mM) and acetonitrile as mobile phase at a flow rate of 0.3ml/min. The method was fully validated according to Société Française des Sciences et Techniques Pharmaceutiques protocols and the latest Food and Drug Administration guidelines. Six point calibration curves were used to cover a large concentration range of 1-500ng/ml for citalopram, desmethyl-citalopram, paroxetine and sertraline, 1-1000ng/ml for fluoxetine and fluvoxamine, and 2-1000ng/ml for norfluoxetine. Good quantitative performances were achieved in terms of trueness (84.2-109.6%), repeatability (0.9-14.6%) and intermediate precision (1.8-18.0%) in the entire assay range including the lower limit of quantification. Internal standard-normalized matrix effects were lower than 13%. The accuracy profiles (total error) were mainly included in the acceptance limits of ±30% for biological samples. The method was successfully applied for routine therapeutic drug monitoring of more than 1600 patient plasma samples over 9 months. The β-expectation tolerance intervals determined during the validation phase were coherent with the results of quality control samples analyzed during routine use. This method is therefore precise and suitable both for therapeutic drug monitoring and pharmacokinetic studies in most clinical laboratories. Copyright © 2012 Elsevier B.V. All rights reserved.

Near-source mobile methane emission estimates using EPA Method33a and a novel probabilistic approach as a basis for leak quantification in urban areas

EPA Science Inventory

Methane emissions from underground pipeline leaks remain an ongoing issue in the development of accurate methane emission inventories for the natural gas supply chain. Application of mobile methods during routine street surveys would help address this issue, but there are large ...

Development of a green chromatographic method for determination of fat-soluble vitamins in food and pharmaceutical supplement.

PubMed

Kienen, Vanessa; Costa, Willian F; Visentainer, Jesuí V; Souza, Nilson E; Oliveira, Cláudio C

2008-03-15

A green chromatographic analytical method for determination of fat-soluble vitamins (A, E, D3 and K1) in food and pharmaceutical supplement samples is proposed. The method is based on the modification of a C18 column with a 3.00% (w/v) sodium dodecyl sulphate (SDS) aqueous solution at pH 7 (0.02 mol L(-1) phosphate buffer solution) and in the usage of the same surfactant solution as mobile phase with the presence of 15.0% (v/v) butyl alcohol as an organic solvent modifier. After the separation process, the vitamins are detected at 230 nm (K1, D3 and E), 280 nm (A, E, D3 and K1) and 300 nm (K1, D3 and E). The chromatographic procedure yielded precise results (better than 5%) and is able to run one sample in 25 min, consuming 1.5 g of SDS, 90 mg of phosphate and 7.5 mL of butyl alcohol. When the flow rate of the mobile phase is 2 mL min(-1) the retention times are 4.0, 9.6, 13.0 and 22.7 min for D3, A, E and K1 vitamins, respectively; and all peak resolutions are higher than 2. The analytical curves present the following linear equations: area=6290+34852 (vitamin A), R2=0.9998; area=4092+36333 (vitamin E), R2=0.9997; area=-794+30382 (vitamin D3) R2=0.9998 and area=-7175+82621 (vitamin K1), R2=0.9996. The limits of detection and quantification for vitamins A, E, D(3) and K(1) were estimated for a test pharmaceutical vitamin supplement sample as 0.81, 1.12, 0.91 and 0.83 mg L(-1) and 2.43, 3.36, 2.73 and 2.49, respectively. When the proposed method was applied to food and pharmaceutical sample analysis, precise results were obtained (R.S.D.<5% and n=3) and in agreement with those obtained by using the classical chromatographic method that uses methanol and acetonitrile as mobile phase. Here, the traditional usage of toxic organic solvent as mobile phase is avoided, which permits to classify the present method as green.

Development and Validation of an HPLC Method for Karanjin in Pongamia pinnata linn. Leaves.

PubMed

Katekhaye, S; Kale, M S; Laddha, K S

2012-01-01

A rapid, simple and specific reversed-phase HPLC method has been developed for analysis of karanjin in Pongamia pinnata Linn. leaves. HPLC analysis was performed on a C(18) column using an 85:13.5:1.5 (v/v) mixtures of methanol, water and acetic acid as isocratic mobile phase at a flow rate of 1 ml/min. UV detection was at 300 nm. The method was validated for accuracy, precision, linearity, specificity. Validation revealed the method is specific, accurate, precise, reliable and reproducible. Good linear correlation coefficients (r(2)>0.997) were obtained for calibration plots in the ranges tested. Limit of detection was 4.35 μg and limit of quantification was 16.56 μg. Intra and inter-day RSD of retention times and peak areas was less than 1.24% and recovery was between 95.05 and 101.05%. The established HPLC method is appropriate enabling efficient quantitative analysis of karanjin in Pongamia pinnata leaves.

Development and Validation of an HPLC Method for Karanjin in Pongamia pinnata linn. Leaves

PubMed Central

Katekhaye, S; Kale, M. S.; Laddha, K. S.

2012-01-01

A rapid, simple and specific reversed-phase HPLC method has been developed for analysis of karanjin in Pongamia pinnata Linn. leaves. HPLC analysis was performed on a C18 column using an 85:13.5:1.5 (v/v) mixtures of methanol, water and acetic acid as isocratic mobile phase at a flow rate of 1 ml/min. UV detection was at 300 nm. The method was validated for accuracy, precision, linearity, specificity. Validation revealed the method is specific, accurate, precise, reliable and reproducible. Good linear correlation coefficients (r2>0.997) were obtained for calibration plots in the ranges tested. Limit of detection was 4.35 μg and limit of quantification was 16.56 μg. Intra and inter-day RSD of retention times and peak areas was less than 1.24% and recovery was between 95.05 and 101.05%. The established HPLC method is appropriate enabling efficient quantitative analysis of karanjin in Pongamia pinnata leaves. PMID:23204626

Development and validation of RP-UHPLC procedure for estimation of 5-amino salicyclic acid in 5-amino salicyclic acid rectal suppositories

NASA Astrophysics Data System (ADS)

Balaji, Jayagopal; Shivashankar, Murugesh

2017-11-01

The present study describes a simple and robust reverse phase ultra performance liquid chromatography (RP-UPLC) method for the quantification of 5-amino salicyclic acid in 5-amino salicyclic acid rectal capsules. Successful separation of Mesalamine peak from excipient peaks and diluent were achieved on a Acquity C8 (50 × 2.1 mm, 1.7 μm) and UV detector at 254 nm, 0.3 mL/min as a flow rate, and 3 μL as an injection volume. For the RP-UPLC method, phosphate buffer and methanol was used as mobile phases at ratio of 83:17 and the column temperature was 25 °C. Percentage recovery obtained in the range of 98.7 - 99.7 % and the method is linear for Mesalamine for specified concentration range with coefficient of variation (r) not less than 0.99. The proposed RP-UPLC method was found to be specific, linear, precise, accurate and robust.

Simultaneous UHPLC-UV analysis of hydroxychloroquine, minocycline and doxycycline from serum samples for the therapeutic drug monitoring of Q fever and Whipple's disease.

PubMed

Armstrong, Nicholas; Richez, Magali; Raoult, Didier; Chabriere, Eric

2017-08-15

A fast UHPLC-UV method was developed for the simultaneous analysis of Hydroxychloroquine, Minocycline and Doxycycline drugs from 100μL of human serum samples. Serum samples were extracted by liquid-liquid extraction and injected into a phenyl hexyl reverse phase column. Compounds were separated using a mobile phase linear gradient and monitored by UV detection at 343nm. Chloroquine and Oxytetracycline were used as internal standards. Lower and upper limits of quantifications, as well as the other levels of calibration, were validated with acceptable accuracy (<15% deviation) and precision (<15% coefficient of variation) according to the European Medicines Agency guidelines. This new method enables cost and time reduction and was considered suitable for the clinical laboratory. It is the first published assay for the therapeutic drug monitoring of patients diagnosed with Q fever or Whipple's disease. Copyright © 2017 Elsevier B.V. All rights reserved.

Quantitative determination of flavonoids by column high-performance liquid chromatography with mass spectrometry and ultraviolet absorption detection in Artemisia afra and comparative studies with various species of Artemisia plants.

PubMed

Avula, Bharathi; Wang, Yan-Hong; Smillie, Troy J; Mabusela, Wilfred; Vincent, Leszek; Weitz, Frans; Khan, Ikhlas A

2009-01-01

A simple and specific analytical method for the quantitative determination of flavonoids from the aerial parts of the Artemisia afra plant samples was developed. By column high-performance liquid chromatography (HPLC) with UV absorption and mass spectrometry (MS) detection, separation was achieved on a reversed-phase octadecylsilyl (C18) column with water, methanol, and acetonitrile, all containing 0.1% acetic acid, as the mobile phase. These methods were used to analyze various species of Artemisia plant samples. The wavelength used for quantification of flavonoids with the diode array detector was 335 nm. The limits of detection (LOD) by HPLC/MS were found to be 7.5, 7.5, 10, 2.0, and 2.0 ng/mL; and by LC-UV the LODs were 500, 500, 500, 300, and 300 ng/mL for apigenin, chrysoeriol, tamarixetin, acacetin, and genkwanin, respectively. The HPLC/MS method was found to be 50-150 times more sensitive than the HPLC-UV method. HPLC/MS coupled with an electrospray ionization interface is described for the identification and quantification of flavonoids in various plant samples. This method involved the use of the [M+H]+ ions of the compounds at mass-to-charge ratio of 1.0606, 301.0712, 317.0661, 285.0763, and 285.0763 (calculated mass), respectively, in the positive ion mode with extractive ion monitoring.

Qualitative screening of veterinary anti-microbial agents in tissues, milk, and eggs of food-producing animals using liquid chromatography coupled with tandem mass spectrometry.

PubMed

Chen, Dongmei; Yu, Jie; Tao, Yanfei; Pan, Yuanhu; Xie, Shuyu; Huang, Lingli; Peng, Dapeng; Wang, Xu; Wang, Yulian; Liu, Zhenli; Yuan, Zonghui

2016-04-01

A method for the analysis of 120 drugs in animal derived food was developed using liquid chromatography-tandem mass spectrometry (LC-MS/MS). These analytes belong to 12 families of veterinary anti-microbial agents (quinolones, macrolides, β-lactams, nitroimidazoles, sulfonamides, lincomycines, chloramphenicols, quinoxalines, tetracyclines, polypeptides, and antibacterial synergists) as well as other compounds not assigned to a particular drug family. The animal derived food samples include muscle and liver of swine, bovine, sheep, and chicken, as well as hen eggs and dairy milk. The sample preparation included ultrasound-assisted extraction (UAE) with acetonitrile-water and a final clean-up with auto solid-phase extraction (SPE) on HLB cartridges. The detection and quantification of 120 anti-microbial agents was performed using LC-MS/MS in positive and negative ion mode. The chromatographic separation was performed on a C18 column using acetonitrile and 0.1% formic acid as the mobile phase. The limit of detection (LOD) and limit of quantification (LOQ) of all drugs in food-producing animals were 0.5-3.0μg/kg and 1.5-10.0μg/kg, respectively. The developed method was successfully utilized to monitor real samples, which demonstrated that it is a simple, fast, and robust method, and could be used as a regulatory to screen for the presence of residues from veterinary anti-microbial drugs in animal-derived foods. Copyright © 2016 Elsevier B.V. All rights reserved.

A Method for LC-MS/MS Profiling of Coumarins in Zanthoxylum zanthoxyloides (Lam.) B. Zepernich and Timler Extracts and Essential Oils.

PubMed

Tine, Yoro; Renucci, Franck; Costa, Jean; Wélé, Alassane; Paolini, Julien

2017-01-22

The metabolites from the coumarin class, present in tissues of plants belonging mainly to the Rutaceae and Apiaceae families, included compounds with high chemical diversity such as simple coumarins and furocoumarins. These health-promoting components are recognized for their valuable biological activities in herbal preparations but also for their phototoxic effects. In this work, a targeted liquid chromatography (LC) coupled with tandem mass spectrometry (MS²) was developed for the screening of 39 reference standards of coumarins and furocoumarins in essential oils and plant extracts. Chromatographic separation was accomplished on reversed phase column using water/acetonitrile as the mobile phase and detection was performed on a hybrid QqQ/linear ion trap spectrometer fitted with an atmospheric pressure chemical ionization (APCI) source operating in positive ion mode. This analytical approach was applied to investigate the coumarin compositions of fruit essential oils and methanolic extracts obtained from separated parts (fruit, leaf, stem, trunk, and root) of Zanthoxylum zanthoxyloides . Ten coumarins and six furanocoumarins were reported in this species and data analyses were used to assess the suitability of these compounds to the metabolomics-based differentiation of plant organs. The quantification criteria of the metabolites in extract samples included linearity, limit of quantification, limit of detection, and matrix effect were validated. As reported for other species of the Rutaceae family, the concentration of coumarins was drastically higher in Z. zanthoxyloides fruits than in other plant organs.

Determination of bupropion using liquid chromatography with fluorescence detection in pharmaceutical preparations, human plasma and human urine.

PubMed

Ulu, Sevgi Tatar; Tuncel, Muzaffer

2012-05-01

A novel pre-column derivatization reversed-phase high-performance liquid chromatography with fluorescence detection is described for the determination of bupropion in pharmaceutical preparation, human plasma and human urine using mexiletine as internal standard. The proposed method is based on the reaction of 4-chloro-7-nitrobenzofurazan (NBD-Cl) with bupropion to produce a fluorescent derivative. The derivative formed is monitored on a C18 (150 mm × 4.6 mm i.d., 5 µm) column using a mobile phase consisting of methanol-water 75:25 (v/v), at a flow-rate of 1.2 mL/min and detected fluorimetrically at λ(ex) = 458 and λ(em) = 533 nm. The assay was linear over the concentration ranges of 5-500 and 10-500 ng/mL for plasma and urine, respectively. The limits of detection and quantification were calculated to be 0.24 and 0.72 ng/mL for plasma and urine, respectively (inter-day results). The recoveries obtained for plasma and urine were 97.12% ± 0.45 and 96.00% ± 0.45, respectively. The method presents good performance in terms of precision, accuracy, specificity, linearity, detection and quantification limits and robustness. The proposed method is applied to determine bupropion in commercially available tablets. The results were compared with an ultraviolet spectrophotometry method using t- and F-tests. © The Author [2012]. Published by Oxford University Press. All rights reserved.

Simultaneous determination of triptolide, tripdiolide and tripterine in human urine by high-performance liquid chromatography coupled with ion trap atmospheric-pressure chemical ionization mass spectrometry.

PubMed

Jin, Mi-cong; Chen, Xiao-hong; OuYang, Xiao-kun

2009-03-01

An accurate and selective method for the simultaneous determination of triptolide, tripdiolide and tripterine in human urine using hydrocortisone as an internal standard (IS) by high-performance liquid chromatography coupled with atmospheric-pressure chemical ionization mass spectrometry in negative ion mode has been developed. After triptolide, tripdiolide and tripterine in human urine were extracted with ethyl acetate and cleaned by solid-phase extraction with C(18) cartridges, a satisfactory separation was achieved on an XDB C(18) short column (30 x 2.1 mm i.d., 3 microm) using the mobile phase of acetic acid-ammonium acetate (5 mmol/L, pH = 4.5)-acetonitrile-methanol in gradient elution. Detection was operated by APCI in selected ion monitoring mode. The target ions m/z 359, m/z 375, m/z 449 and m/z 419 were selected for the quantification of triptolide, tripdiolide, tripterine and IS, respectively. The linear range was 1.0-100.0 ng mL(-1), and the limits of quantification in human urine were found to be 0.1-0.5 ng mL(-1) for the three compounds. The precisions (CV%) and accuracies were 6.6-12.9 and 85.1-97.0%, respectively. The developed method could be applied to the determination of triptolide, tripdiolide and tripterine in human urine for diagnosis of the intoxication and for forensic purposes. 2008 John Wiley & Sons, Ltd.

Determination of low-level acrylamide in drinking water by liquid chromatography/tandem mass spectrometry.

PubMed

Lucentini, Luca; Ferretti, Emanuele; Veschetti, Enrico; Achene, Laura; Turrio-Baldassarri, Luigi; Ottaviani, Massimo; Bogialli, Sara

2009-01-01

A simple and sensitive liquid chromatographic-tandem mass spectrometric (LC/MS/MS) method has been developed and validated to confirm and quantify acrylamide monomer (AA) in drinking water using [13C3] acrylamide as internal standard (IS). After a preconcentration by solid-phase extraction with spherical activated carbon, analytes were chromatographed on IonPac ICE-AS1 column (9 x 250 mm) under isocratic conditions using acetonitrile-water-0.1 M formic acid (43 + 52 + 5, v/v/v) as the mobile phase. Analysis was achieved using a triple-quadrupole mass analyzer equipped with a turbo ion spray interface. For confirmation and quantification of the analytes, MS data acquisition was performed in the multireaction monitoring mode, selecting 2 precursor ion to product ion transitions for both AA and IS. The method was validated for linearity, sensitivity, accuracy, precision, extraction efficiency, and matrix effect. Linearity in tap water was observed over the concentration range 0.1-2.0 microg/L. Limits of detection and quantification were 0.02 and 0.1 microg/L, respectively. Interday and intraday assays were performed across 3 validation levels (0.1, 0.5, and 1.5 microg/L). Accuracy (as mean recovery) ranged from 89.3 to 96.2% with relative standard deviation <7.98%. Performance characteristics of this LC/MS/MS method make it suitable for regulatory confirmatory analysis of AA in drinking water in compliance with European Union and U.S. Environmental Protection Agency standards.

Stability Indicating Reverse Phase HPLC Method for Estimation of Rifampicin and Piperine in Pharmaceutical Dosage Form.

PubMed

Shah, Umang; Patel, Shraddha; Raval, Manan

2018-01-01

High performance liquid chromatography is an integral analytical tool in assessing drug product stability. HPLC methods should be able to separate, detect, and quantify the various drug-related degradants that can form on storage or manufacturing, plus detect any drug-related impurities that may be introduced during synthesis. A simple, economic, selective, precise, and stability-indicating HPLC method has been developed and validated for analysis of Rifampicin (RIFA) and Piperine (PIPE) in bulk drug and in the formulation. Reversed-phase chromatography was performed on a C18 column with Buffer (Potassium Dihydrogen Orthophosphate) pH 6.5 and Acetonitrile, 30:70), (%, v/v), as mobile phase at a flow rate of 1 mL min-1. The detection was performed at 341 nm and sharp peaks were obtained for RIFA and PIPE at retention time of 3.3 ± 0.01 min and 5.9 ± 0.01 min, respectively. The detection limits were found to be 2.385 ng/ml and 0.107 ng/ml and quantification limits were found to be 7.228ng/ml and 0.325ng/ml for RIFA and PIPE, respectively. The method was validated for accuracy, precision, reproducibility, specificity, robustness, and detection and quantification limits, in accordance with ICH guidelines. Stress study was performed on RIFA and PIPE and it was found that these degraded sufficiently in all applied chemical and physical conditions. Thus, the developed RP-HPLC method was found to be suitable for the determination of both the drugs in bulk as well as stability samples of capsule containing various excipients. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Simultaneous quantification of six alkaloid components from commercial stemonae radix by solid phase extraction-high-performance liquid chromatography coupled with evaporative light scattering detector

PubMed Central

Zhang, Rong-Rong; Lu, Dan-Yi; Yang, Zhen-Ya; Zhao, Wen; But, Paul Pui-Hay; Shaw, Pang-Chui; Jiang, Ren-Wang; Ma, Zhi-Guo

2015-01-01

Background: Stemonae radix has been applied in traditional Chinese medicine for centuries. Alkaloids are the main active ingredient in stemonae radix, so their composition and concentration levels are directly linked to clinic effects. Objective: The objective was to develop an analytical method with multiple markers for quality survey of commercial stemonae radix. Materials and Methods: A method for simultaneous determination of six compounds in commercial stemonae radix was performed using solid-phase extraction and high-performance liquid chromatography coupled with evaporative light scattering detector. The separation was carried out on an Agilent TC-C18 column with 0.1% acetonitrile solution of triethylamine aqueous solution and acetonitrile as the mobile phase under gradient elution within 70 min. The hierarchical clustering analysis (HCA) was successfully used to classify the samples in accordance with their chemical constituents. Results: Linearity (R2 > 0.9990), intra- and inter-day precision (relative standard deviations <4%), limit of detection (0.011–0.086 μg/mL), limit of quantification (0.033–0.259 μg/mL) of the six alkaloids were determined, and the recoveries were between 96.6% and 103.7%. The method was successfully applied to analysis 36 batches of commercial stemonae radix. All the samples could be classified into five clusters by HCA. Conclusion: This article provides an accurate and simple analytical method for quality survey of commercial stemonae radix. Because of the significant chemical variations, careful selection of Stemona sources with obvious antitussive value but devoid of croomine followed by good agricultural practice and good manufacturing practice process is suggested. PMID:25829776

Rapid determination of chlormequat in meat by dispersive solid-phase extraction and hydrophilic interaction liquid chromatography (HILIC)-electrospray tandem mass spectrometry.

PubMed

Li, Chunmei; Jin, Fen; Yu, Zhiyong; Qi, Yamei; Shi, Xiaomei; Wang, Miao; Shao, Hua; Jin, Maojun; Wang, Jing; Yang, Mingqi

2012-07-11

A rapid method for analyzing trace levels of chlormequat (CQ) in meat samples by hydrophilic interaction liquid chromatography (HILIC)-electrospray tandem mass spectrometry was developed. The samples were extracted with acetonitrile, followed by a rapid cleanup through a dispersive solid-phase extraction (DSPE) technique with octadecyl (C18) DSPE sorbents. The chromatographic separation was achieved within 6 min using a HILIC column with 10 mM ammonium acetate and 0.1% (v/v) formic acid in water/acetonitrile (v/v, 40:60) as the mobile phase. Quantification was performed using a matrix-matched calibration curve, which was linear in the range of the 0.05-100 μg/L. The limit of detection (LOD) was estimated at 0.03 μg/kg for CQ on the basis of a peak to peak signal noise (S/N = 3). The limit of quantification (LOQ) was 0.1 μg/kg on the basis of the lowest spiked concentration with suitable precision and accuracy. The average recovery of CQ in spiked meat samples was 86.4-94.7% at 2, 20, and 200 μg/kg. Finally, this method was applied to determine CQ in the livestock and poultry meats purchased from markets in Beijing in 2011. CQ was detected in all 12 samples, and the concentration was 0.4-636.0 μg/kg. Concentrations in a chicken sample (636.0 μg/kg) and a goat meat sample (486.0 μg/kg) were found to be 15.9 and 2.43 times the corresponding Codex maximum residue limits, respectively.

Application of statistical experimental design to the optimisation of microextraction by packed sorbent for the analysis of nonsteroidal anti-inflammatory drugs in human urine by ultra-high pressure liquid chromatography.

PubMed

Magiera, Sylwia; Gülmez, Şefika; Michalik, Aleksandra; Baranowska, Irena

2013-08-23

A new approach based on microextraction by packed sorbent (MEPS) and a reversed-phase ultra-high pressure liquid chromatography (UHPLC) method was developed and validated for the determination and quantification of nonsteroidal anti-inflammatory drugs (NSAIDs) (acetylsalicylic acid, ketoprofen, diclofenac, naproxen and ibuprofen) in human urine. The important factors that could influence the extraction were previously screened using the Plackett-Burman design approach. The optimal MEPS extraction conditions were obtained using C18 phase as a sorbent, small sample volume (20μL) and a short time period (approximately 5min) for the entire sample preparation step. The analytes were separated on a core-shell column (Poroshell 120 EC-C18; 100mm×3.0mm; 2.7μm) using a binary mobile phase composed of aqueous 0.1% trifluoroacetic acid and acetonitrile in the gradient elution mode (4.5min of analysis time). The analytical method was fully validated based on linearity, limits of detection (LOD), limits of quantification (LOQ), inter- and intra-day precision and accuracy, and extraction yield. Under optimised conditions, excellent linearity (R(2)>0.9991), limits of detection (1.07-16.2ngmL(-1)) and precision (0.503-9.15% RSD) were observed for the target drugs. The average absolute recoveries of the analysed compounds extracted from the urine samples were 89.4-107%. The proposed method was also applied to the analysis of NSAIDs in human urine. The new approach offers an attractive alternative for the analysis of selected drugs from urine samples, providing several advantages including fewer sample preparation steps, faster sample throughput and ease of performance compared to traditional methodologies. Copyright © 2013 Elsevier B.V. All rights reserved.

A novel reverse phase high-performance liquid chromatography method for standardization of Orthosiphon stamineus leaf extracts.

PubMed

Saidan, Noor Hafizoh; Aisha, Abdalrahim F A; Hamil, Mohd Shahrul Ridzuan; Majid, Amin Malik Shah Abdul; Ismail, Zhari

2015-01-01

Orthosiphon stamineus Benth. (Lamiaceae) is a traditional medicinal plant which has been used in treating various ailments such as kidney diseases, bladder inflammation, arthritis and diabetes. The leaves contain high concentration of phenolic compounds, thus, rosmarinic acid (RA), 3'-hydroxy-5, 6, 7, 4'-tetramethoxyflavone (TMF), sinensetin (SIN) and eupatorin (EUP) were chosen as a marker compounds for standardization of various O. stamineus leaf extracts. The aim was to develop and validate a new high-performance liquid chromatography (HPLC) method for quantification of 4 marker compounds (RA, TMF, SIN, EUP) in various O. stamineus leaf extracts. The method was developed and validated using RP-HPLC-diode-array detection at 320 nm for accuracy, precision and limits of detection and was applied for quantification of it markers in five different extracts prepared in solvents with increasing polarity, using a gradient mobile phase 0.1% formic acid: Acetonitrile at a flow rate of 1 ml/min on reverse phase acclaim polar advantage II C18 column (3 μm, 3 × 150 mm) with 18 min separation time. The developed method provided satisfactory precision, and the accuracy of this method was in the range of 90.2% to 105.5%. All of 4 compounds showed good linearity at R2 > 0.999. The developed method is a simple, cost effective with shorter run time (18 min) in comparison to previous methods (30 min) and utilization of environmental-friendly solvents system. Therefore, this method has the potential to replace currently used methods in the routine standardization work of O. stamineus extracts, raw materials and its commercial products.

A novel reverse phase high-performance liquid chromatography method for standardization of Orthosiphon stamineus leaf extracts

PubMed Central

Saidan, Noor Hafizoh; Aisha, Abdalrahim F.A.; Hamil, Mohd Shahrul Ridzuan; Majid, Amin Malik Shah Abdul; Ismail, Zhari

2015-01-01

Background: Orthosiphon stamineus Benth. (Lamiaceae) is a traditional medicinal plant which has been used in treating various ailments such as kidney diseases, bladder inflammation, arthritis and diabetes. The leaves contain high concentration of phenolic compounds, thus, rosmarinic acid (RA), 3’-hydroxy-5, 6, 7, 4’-tetramethoxyflavone (TMF), sinensetin (SIN) and eupatorin (EUP) were chosen as a marker compounds for standardization of various O. stamineus leaf extracts. Objective: The aim was to develop and validate a new high-performance liquid chromatography (HPLC) method for quantification of 4 marker compounds (RA, TMF, SIN, EUP) in various O. stamineus leaf extracts. Materials and Methods: The method was developed and validated using RP-HPLC-diode-array detection at 320 nm for accuracy, precision and limits of detection and was applied for quantification of it markers in five different extracts prepared in solvents with increasing polarity, using a gradient mobile phase 0.1% formic acid: Acetonitrile at a flow rate of 1 ml/min on reverse phase acclaim polar advantage II C18 column (3 μm, 3 × 150 mm) with 18 min separation time. Results: The developed method provided satisfactory precision, and the accuracy of this method was in the range of 90.2% to 105.5%. All of 4 compounds showed good linearity at R2 > 0.999. Conclusion: The developed method is a simple, cost effective with shorter run time (18 min) in comparison to previous methods (30 min) and utilization of environmental-friendly solvents system. Therefore, this method has the potential to replace currently used methods in the routine standardization work of O. stamineus extracts, raw materials and its commercial products. PMID:25598631

Determination of a selection of anti-epileptic drugs and two active metabolites in whole blood by reversed phase UPLC-MS/MS and some examples of application of the method in forensic toxicology cases.

PubMed

Karinen, Ritva; Vindenes, Vigdis; Hasvold, Inger; Olsen, Kirsten Midtbøen; Christophersen, Asbjørg S; Øiestad, Elisabeth

2015-07-01

Quantitative determination of anti-epileptic drug concentrations is of great importance in forensic toxicology cases. Although the drugs are not usually abused, they are important post-mortem cases where the question of both lack of compliance and accidental or deliberate poisoning might be raised. In addition these drugs can be relevant for driving under the influence cases. A reversed phase ultra-performance liquid chromatography-tandem mass spectrometry method has been developed for the quantitative analysis of the anti-epileptic compounds carbamazepine, carbamazepine-10,11-epoxide, gabapentin, lamotrigine, levetiracetam, oxcarbazepine, 10-OH-carbazepine, phenobarbital, phenytoin, pregabalin, and topiramate in whole blood, using 0.1 mL sample volume with methaqualone as internal standard. Sample preparation was a simple protein precipitation with acetonitrile and methanol. The diluted supernatant was directly injected into the chromatographic system. Separation was performed on an Acquity UPLC® BEH Phenyl column with gradient elution and a mildly alkaline mobile phase. The mass spectrometric detection was performed in positive ion mode, except for phenobarbital, and multiple reaction monitoring was used for drug quantification. The limits of quantification for the different anti-epileptic drugs varied from 0.064 to 1.26 mg/L in blood, within-day and day-to-day relative standard deviations from 2.2 to 14.7% except for phenobarbital. Between-day variation for phenobarbital was 20.4% at the concentration level of 3.5 mg/L. The biases for all compounds were within ±17.5%. The recoveries ranged between 85 and 120%. The corrected matrix effects were 88-106% and 84-110% in ante-mortem and post-mortem whole blood samples, respectively. Copyright © 2014 John Wiley & Sons, Ltd.

A specific and sensitive HPLC-MS/MS micromethod for milrinone plasma levels determination after inhalation in cardiac patients.

PubMed

Gavra, Paul; Nguyen, Anne Q-N; Theoret, Yves; Litalien, Catherine; Denault, André Y; Varin, France

2014-10-01

Milrinone administered through inhalation is an emerging method aimed at specifically reducing pulmonary hypertension without affecting systemic pressures. Its administration has been shown to be useful both in patients undergoing cardiac surgery and for persistent pulmonary hypertension of the newborn. These populations are prone to receive many concomitant medications and/or blood sampling may require a low volume quantification method. To address these issues in view of pharmacokinetic studies, this article aims to develop and validate a specific and sensitive analytical assay using high performance liquid chromatography (HPLC) and tandem mass spectrometry (MS/MS) detection for the quantification of milrinone plasma concentrations after inhalation in patients undergoing cardiac surgery. Plasma samples (50 μL) were extracted using ethyl acetate. Milrinone was separated on a C18 analytical column at 50°C. The mobile phase consisted of methanol and 10 mM ammonium acetate (45:55 vol/vol). The electrospray was operated in the negative ionization mode and monitored the following mass transitions: m/z 212.1 → 140.0 at 36 eV for milrinone and m/z 252.1 → 156.1 at 32 eV for olprinone. Calibration curves followed a quadratic regression in the concentration range of 0.3125-640 ng/mL. The lower limit of quantification is 0.3125 ng/mL and is based on a low plasma volume of 50 μL. Mean drug recovery and accuracy were ≥72.3% and 96.0%, respectively. Intraday and interday precision coefficient of variation (%) was ≤7.4% and ≤11.5%, respectively. The specificity allowed milrinone quantification in the multidrug administration conditions of cardiopulmonary bypass. This validated micromethod proved to be highly sensitive and specific while using a low volume of plasma. Its low volume and its lower limit of quantification indicate that this approach is suitable for further characterization of milrinone pharmacokinetics in both adults (inhalation) and neonates.

Extraction Methodological Contributions Toward Ultra-Performance Liquid ChromatographyTime-of-Flight Mass Spectrometry: Quantification of Free GB from Various Food Matrices

DTIC Science & Technology

2016-02-01

SPECTROMETRY: QUANTIFICATION OF FREE GB FROM VARIOUS FOOD MATRICES ECBC-TR-1351 Sue Y. Bae Mark D. Winemiller RESEARCH AND TECHNOLOGY DIRECTORATE...Flight Mass Spectrometry: Quantification of Free GB from Various Food Matrices 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER...methylphosphonofluoridate (sarin, GB) in various food matrices. The development of a solid-phase extraction method using a normal-phase silica gel column for

Determination of aesculin in rat plasma by high performance liquid chromatography method and its application to pharmacokinetics studies.

PubMed

Chen, QiuHong; Hou, ShiXiang; Zheng, Jia; Bi, YueQi; Li, YuanBo; Yang, XiaoJiao; Cai, Zheng; Song, XiangRong

2007-10-15

A sensitive and reproducible high performance liquid chromatography method with UV detection was described for the determination of aesculin in rat plasma. After deproteinization by methanol using metronidazole as internal standard (I.S.), solutes were evaporated to dryness at 40 degrees C under a gentle stream of nitrogen. The residue was reconstituted in 100 microl of mobile phase and a volume of 20 microl was injected into the HPLC for analysis. Solutes were separated on a Diamonsil C18 column (250 mm x 4.6 mm i.d., 5 microm particle size, Dikma) protected by a ODS guard column (10 mm x 4.0 mm i.d., 5 microm particle size), using acetonitrile-0.1% triethylamine solution (adjusted to pH 3.0 using phosphoric acid) (10:90, v/v) as mobile phase (flow-rate 1.0 ml/min), and wavelength of the UV detector was set at 338 nm. No interference from any endogenous substances was observed during the elution of aesculin and internal standard (I.S., metronidazole). The retention times for I.S and aesculin were 10.4 and 12.4 min, respectively. The limit of quantification was evaluated to be 57.4 ng/ml and the limit of detection was 24.0 ng/ml. The method was used in the study of pharmacokinetics of aesculin after intraperitoneal injection (i.p.) administration in rats.

Industrial application of green chromatography - II. Separation and analysis of preservatives in skincare products using subcritical water chromatography.

PubMed

Yang, Y; Kapalavavi, B; Gujjar, L; Hadrous, S; Marple, R; Gamsky, C

2012-10-01

Several high-temperature liquid chromatography (HTLC) and subcritical water chromatography (SBWC) methods have been successfully developed in this study for separation and analysis of preservatives contained in Olay skincare creams. Efficient separation and quantitative analysis of preservatives have been achieved on four commercially available ZirChrom and Waters XBridge columns at temperatures ranging from 100 to 200°C. The quantification results obtained by both HTLC and SBWC methods developed for preservatives analysis are accurate and reproducible. A large number of replicate HTLC and SBWC runs also indicate no significant system building-up or interference for skincare cream analysis. Compared with traditional HPLC separation carried out at ambient temperature, the HTLC methods can save up to 90% methanol required in the HPLC mobile phase. However, the SBWC methods developed in this project completely eliminated the use of toxic organic solvents required in the HPLC mobile phase, thus saving a significant amount of money and making the environment greener. Although both homemade and commercial systems can accomplish SBWC separations, the SBWC methods using the commercial system for preservative analysis are recommended for industrial applications because they can be directly applied in industrial plant settings. © 2012 The Authors ICS © 2012 Society of Cosmetic Scientists and the Société Française de Cosmétologie.

Determination of linsidomine in human plasma by tandem LC-MS with ESI.

PubMed

Sutherland, F C; de Jager, A D; Swart, K J; Hundt, H K; Scanes, T; Hundt, A F

2000-04-01

A sensitive method for the determination of linsidomine in plasma was developed, using high-performance liquid chromatographic (HPLC) separation with tandem mass spectrometric detection. Linsidomine was derivatised with propyl chloroformate and extracted with tert-butyl methyl ether/1,2-dichloroethane (55:45, v/v), back-extracted into HCl (0.01 M) followed by alkalinisation and back-extraction into ether; the final ether extract evaporated, reconstituted in mobile phase and then separated on a Phenomenex Luna C18 (2) 5 micron 2.1 x 150 mm column with a mobile phase consisting of methanol water formic acid (98/100%) (400:600:0.05, v/v/v) at a flow-rate of 0.4 ml min(-1). Detection was achieved by a Finnigan MAT mass spectrometer (LCQ) at unit resolution in the selected reaction monitoring (SRM) mode monitoring the transition of the protonated molecular ion m/z 257.0 to the product ion m/z 86.0. The mean recovery for linsidomine was 51% with a lower limit of quantification of 0.70 ng/ml using 1 ml plasma for extraction. This LC-MS/MS method for the determination of linsidomine in human plasma allows for better specificity and a higher sample throughput than the traditional LC-UV methods. It also demonstrates the profound effect that the composition of acidic modifiers and matrix constituents can have on the electrospray ionisation (ESI) of the analyte.

Rapid determination of letrozole, citalopram and their metabolites by high performance liquid chromatography-fluorescence detection in urine: Method validation and application to real samples.

PubMed

Rodríguez, J; Castañeda, G; Muñoz, L

2013-01-15

This work reports the validation of a high precision and accuracy method for the simultaneous determination of letrozole, citalopram and their metabolites in urine by high performance liquid chromatography with fluorescence detection. Dilution (urine:mobile phase, 1:2, v/v) was the only sample preparation step. The separation was carried out in a Kromasil C(18) (150mm×4.6mm) column, and the mobile phase was phosphate buffer 80mM (pH 3.0) and acetonitrile (65:35, v/v) at a flow rate of 1.0mL/min. The analytes were detected at 295nm after excitation at 230nm. Linearity was observed in the range of 1.0-1000ng/mL for letrozole and its metabolite and 2.5-1000ng/mL for citalopram and their metabolites, with limits of detection and quantification between 0.09-1.0 and 0.27-1.65ng/mL, respectively. The precisions were satisfactory with RSDs between 0.17 and 5.71%. The accuracy was studied by spiking three urines from healthy female volunteers, and the recoveries were from 85 to 103%. The method was applied to urine samples from women under treatment for breast cancer and depression diseases. Copyright © 2012 Elsevier B.V. All rights reserved.

Simultaneous determination of tyramine and tryptamine and their precursor amino acids by micellar liquid chromatography and pulsed amperometric detection in wines.

PubMed

Gil-Agustí, M; Carda-Broch, S; Monferrer-Pons, Ll; Esteve-Romero, J

2007-07-13

Two biogenic amines, tryptamine and tyramine, and their precursors, tryptophan and tyrosine, were determined by a liquid chromatographic procedure. A hybrid micellar mobile phase of sodium dodecyl sulphate (SDS) and 1-propanol, a C18 column and electrochemical detection were used. A pH study in the range of 3-9 was performed and pH 3 was finally selected in accordance with resolution and analysis time. Oxidation potential was also checked in the range 0.6-0.9V: the maximum area obtained in all those potentials was at 0.8V, which was selected to carry out the analysis using a sequence of pulsed amperometric detection waveform. The four compounds were resolved using a mobile phase of 0.15M SDS-5% 1-propanol with an analysis time of 16 min. Repeatabilities and intermediate precision were evaluated at three different concentrations for each compound with RSD values lower than 2.6 and 4.8%, respectively. Limits of detection and quantification were also obtained within the 10-40 and 33-135 ng/ml ranges, respectively. Finally, the applicability of the procedure was tested in several types of wine and no matrix effect was observed. The possibility of direct sample introduction simplifies and greatly expedites the treatments with reduced cost, improving the accuracy of the procedures.

[Determination of gossypol in edible vegetable oil with high performance liquid chromatography-tandem mass spectrometry].

PubMed

Zhang, Wenhua; Huang, Chaoqun; Xie, Wen; Shen, Li

2014-06-01

A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for the determination of gossypol in edible vegetable oil. The sample was extracted with ethyl alcohol by vortex-excited oscillation. The extract was cleaned up by 0.22 microm filter membrane and centrifuged for 5 min at 4 000 r/min after standing in a fridge at 4 degrees C for 30 min. The compound was separated on a C18 column (100 mm x 2.1 mm, 3.5 microm) with acetonitrile and 1% (v/v) formic acid aqueous solution as mobile phase. The detection of gossypol was carried out by LC-MS/MS with positive electrospray ionization under multiple reaction monitoring (MRM) mode using external standard method. The limits of quantification (S/N > 10) of gossypol in edible vegetable oil was 1 mg/kg. The recoveries were from 87.4% to 100% at the spiked levels of 1, 2, 200 mg/kg of gossypol in edible vegetable oil with the relative standard deviations (RSDs) between 3.9% and 12.2%. The method, with high sensitivity, good precision and high recovery, was suitable for the confirmation and quantification of gossypol residue in edible vegetable oil.

A fast and validated method for the determination of malondialdehyde in fish liver using high-performance liquid chromatography with a photodiode array detector.

PubMed

Faizan, Mohammad; Esatbeyoglu, Tuba; Bayram, Banu; Rimbach, Gerald

2014-04-01

Malondialdehyde (MDA) is a biomarker of lipid peroxidation and is present in foods and biological samples such as plasma. A high-performance liquid chromatography (HPLC) method was applied to determine MDA in fish liver samples after derivatization with 2,4-dinitrophenylhydrazine (DNPH) using a ODS2 column (10 cm × 4.6 mm, 3 μm) and a photodiode array detector. The mobile phase consisted of 0.2% acetic acid (v/v) in distilled water and acetonitrile (42:58, v/v). The present method was validated in terms of linearity, lower limit of quantification, lower limit of detection, precision, accuracy, recovery, and stability of MDA according to U.S. Food and Drug Administration (FDA) guidelines. The limit of quantification of MDA was 0.39 μmol/L, which is comparable to other methods. The recovery of the spiked MDA liver samples was in the range of 92.4% to 104.2%. This newly modified HPLC method is specific, sensitive, and accurate and allows the analysis of MDA within 4 min in fish liver but also in other tissues and plasma. © 2014 Institute of Food Technologists®

Current role of liquid chromatography-mass spectrometry in clinical and forensic toxicology.

PubMed

Maurer, Hans H

2007-08-01

This paper reviews multi-analyte single-stage and tandem liquid chromatography-mass spectrometry (LC-MS) procedures using different mass analyzers (quadrupole, ion trap, time-of-flight) for screening, identification, and/or quantification of drugs, poisons, and/or their metabolites in blood, plasma, serum, or urine published after 2004. Basic information about the biosample assayed, work-up, LC column, mobile phase, ionization type, mass spectral detection mode, and validation data of each procedure is summarized in tables. The following analytes are covered: drugs of abuse, analgesics, opioids, sedative-hypnotics, benzodiazepines, antidepressants including selective-serotonin reuptake inhibitors (SSRIs), herbal phenalkylamines (ephedrines), oral antidiabetics, antiarrhythmics and other cardiovascular drugs, antiretroviral drugs, toxic alkaloids, quaternary ammonium drugs and herbicides, and dialkylphosphate pesticides. The pros and cons of the reviewed procedures are critically discussed, particularly, the need for studies on matrix effects, selectivity, analyte stability, and the use of stable-isotope labeled internal standards instead of unlabeled therapeutic drugs. In conclusion, LC-MS will probably become a gold standard for detection of very low concentrations particularly in alternative matrices and for quantification in clinical and forensic toxicology. However, some drawbacks still need to be addressed and finally overcome.

Densitometric HPTLC analysis of 8-gingerol in Zingiber officinale extract and ginger-containing dietary supplements, teas and commercial creams.

PubMed

Alam, Prawez

2013-08-01

To develop and validate a simple, accurate HPTLC method for the analysis of 8-gingerol and to determine the quantity of 8-gingerol in Zingiber officinale extract and ginger-containing dietary supplements, teas and commercial creams. The analysis was performed on 10×20 cm aluminium-backed plates coated with 0.2 mm layers of silica gel 60 F254 (E-Merck, Germany) with n-hexane: ethyl acetate 60: 40 (v/v) as mobile phase. Camag TLC Scanner III was used for the UV densitometric scanning at 569. This system was found to give a compact spot of 8-gingerol at retention factor (Rf) value of (0.39±0.04) and linearity was found in the ranges 50-500 ng/spot (r (2)=0.9987). Limit of detection (12.76 ng/spot), limit of quantification (26.32 ng/spot), accuracy (less than 2 %) and recovery (ranging from 98.22-99.20) were found satisfactory. The HPTLC method developed for quantification of 8-gingerol was found to be simple, accurate, reproducible, sensitive and is applicable to the analysis of 8-gingerol in Zingiber officinale extract and ginger-containing dietary supplements, teas and commercial creams.

Silica-based monolithic column with evaporative light scattering detector for HPLC analysis of bacosides and apigenin in Bacopa monnieri.

PubMed

Bhandari, Pamita; Kumar, Neeraj; Singh, Bikram; Singh, Virendra; Kaur, Inderjeet

2009-08-01

A high performance liquid chromatographic method using a silica-based monolithic column coupled with evaporative light scattering detector (HPLC-ELSD) was developed and validated for simultaneous quantification of bacosides (bacoside A, bacopaside I, bacoside A(3), bacopaside II, bacopaside X, bacopasaponin C) and apigenin in Bacopa monnieri. The chromatographic resolution was achieved on a Chromolith RP-18 (100x4.6 mm) column with acetonitrile/water (30:70) as mobile phase in isocratic elution at a flow rate of 0.7 mL/min. The drift tube temperature of the ELSD was set to 95 degrees C, and the nitrogen flow rate was 2.0 SLM (standard liter per minute). The calibration curves revealed a good linear relationship (r(2) > 0.9988) within the test ranges. The detection limits (S/N = 3) and the quantification limits (S/N = 10) for the compounds were in the range of 0.54-6.06 and 1.61-18.78 microg/mL, respectively. Satisfactory average recovery was observed in the range of 95.8-99.0%. The method showed good reproducibility for the quantification of these compounds in B. monnieri with intra- and inter-day precision of less than 0.69 and 0.67%, respectively. The validated method was successfully applied to quantify analytes in nine accessions of B. monnieri and thus provides a new basis for overall quality assessment of B. monnieri.

Quantitative determination of trigonelline in mouse serum by means of hydrophilic interaction liquid chromatography-MS/MS analysis: Application to a pharmacokinetic study.

PubMed

Szczesny, Damian; Bartosińska, Ewa; Jacyna, Julia; Patejko, Małgorzata; Siluk, Danuta; Kaliszan, Roman

2018-02-01

Trigonelline is a pyridine alkaloid found in fenugreek seeds and coffee beans. Most of the previous studies are concerned with the quantification of trigonelline along with other constituents in coffee herbs or beverages. Only a few have focused on its determination in animal or human tissues by applying different modes of HPLC with UV or MS detection. The aim of the study was to develop and validate a fast and simple method for trigonelline determination in serum by the use of hydrophilic interaction liquid chromatography (HILIC) with ESI-MS/MS detection. Separation of trigonelline was achieved on a Kinetex HILIC column operated at 35°C with acetonitrile-ammonium formate (10 mm, pH = 3) buffer mixture (55:45, v/v) as the mobile phase. The developed method was successfully applied to determine trigonelline concentration in mouse serum after intravenous administration of 10 mg/kg. The developed assay is sensitive (limit of detection = 1.5 ng/mL, limit of quantification = 5.0 ng/mL) and linear in a concentration range from 5.0 to 250.0 ng/mL. Sample preparation is limited to deproteinization, centrifugation and filtration. The application of the HILIC mode of chromatography with MS detection and selection of deuterated trigonelline as internal standard allowed a rapid and precise method of trigonelline quantification to be to developed. Copyright © 2017 John Wiley & Sons, Ltd.

RP-LC and TLC Densitometric Determination of Paracetamol and Pamabrom in Presence of Hazardous Impurity of Paracetamol and Application to Pharmaceuticals

PubMed Central

El-Houssini, Ola Mohamed

2013-01-01

Two simple, accurate and reproducible methods were developed and validated for the simultaneous determination of paracetamol (PARA) and pamabrom (PAMB) in pure form and in tablets. The first method was based on reserved-phase high-performance liquid chromatography, on a Thermo Hypersil ODS column using methanol:0.01 M sodium hexane sulfonate:formic acid (67.5:212.5:1 v/v/v) as the mobile phase. The flow rate was 2 mL/min and the column temperature was adjusted to 35 °C. Quantification was achieved with UV detection at 277 nm over concentration range of 100–600 and 4–24 μg/mL, with mean percentage recoveries were found to be 99.90 ± 0.586 and 99.26 ± 0.901 for PARA and PAMB, respectively. The second method was based on thin-layer chromatography separation of PARA and PAMB followed by densitometric measurement of the spots at 254 nm and 277 nm for PARA and PAMB respectively. Separation was carried out on aluminum sheet of silica gel 60F254 using dichloromethane:methanol:glacial acetic acid (7.5:1:0.5 v/v/v) as the mobile phase over concentration range of 1–10 and 0.32–3.20 μg per spot, with mean percentage recovery of 100.52 ± 1.332 and 99.71 ± 1.478 for PARA and PAMB, respectively. The methods retained their accuracy in presence of up to 50% of P-aminophenol and could be successfully applied in tablets. PMID:24046511

High performance liquid chromatographic and thin layer densitometric methods for the determination of risperidone in the presence of its degradation products in bulk powder and in tablets.

PubMed

El-Sherif, Zeinab A; El-Zeany, Badr; El-Houssini, Ola M

2005-01-04

Two reproducible stability indicating methods were developed for the determination of risperidone (RISP) in presence of its degradation products in pure form and in tablets. The first method was based on reversed phase high performance liquid chromatography (HPLC), on Lichrosorb RP C 18 column (250 mm i.d., 4 mm, 10 microm), using methanol:0.05 M potassium dihydrogen phosphate pH 7 (65:35 (v/v)) as the mobile phase at a flow rate of 1 ml min(-1) at ambient temperature. Quantification was achieved with UV detection at 280 nm over a concentration range of 25-500 microg ml(-1) with mean percentage recovery of 99.87 +/- 1.049. The method retained its accuracy in the presence of up to 90% of RISP degradation products. The second method was based on TLC separation of RISP from its degradation products followed by densitometric measurement of the intact drug spot at 280 nm. The separation was carried out on aluminum sheet of silica gel 60F254 using acetonitrile:methanol:propanol:triethanolamine (8.5:1.2:0.6:0.2 (v/v/v/v)), as the mobile phase, over a concentration range of 2-10 microg per spot and mean percentage recovery of 100.1 +/- 1.18. The two methods were simple, precise, sensitive and could be successfully applied for the determination of pure, laboratory prepared mixtures and tablets. The results obtained were compared with the manufacturer's method.

Simultaneous estimation of lisofylline and pentoxifylline in rat plasma by high performance liquid chromatography-photodiode array detector and its application to pharmacokinetics in rat.

PubMed

Italiya, Kishan S; Sharma, Saurabh; Kothari, Ishit; Chitkara, Deepak; Mittal, Anupama

2017-09-01

Lisofylline (LSF) is an anti-inflammatory and immunomodulatory agent with proven activity in serious infections associated with cancer chemotherapy, hyperoxia-induced acute lung injury, autoimmune disorders including type-1 diabetes (T1DM) and islet rejection after islet transplantation. It is also an active metabolite of another anti-inflammatory agent, Pentoxifylline (PTX). LSF bears immense therapeutic potential in multiple pharmacological activities and hence appropriate and accurate quantification of LSF is very important. Although a number of analytical methods for quantification of LSF and PTX have been reported for pharmacokinetics and metabolic studies, each of these have certain limitations in terms of large sample volume required, complex extraction procedure and/or use of highly sophisticated instruments like LC-MS/MS. The aim of current study is to develop a simple reversed-phase HPLC method in rat plasma for simultaneous determination of LSF and PTX with the major objective of ensuring minimum sample volume, ease of extraction, economy of analysis, selectivity and avoiding use of instruments like LC-MS/MS to ensure a widespread application of the method. A simple liquid-liquid extraction method using methylene chloride as extracting solvent was used for extracting LSF and PTX from rat plasma (200μL). Samples were then evaporated, reconstituted with mobile phase and injected into HPLC coupled with photo-diode detector (PDA). LSF, PTX and 3-isobutyl 1-methyl xanthine (IBMX, internal standard) were separated on Inertsil® ODS (C18) column (250×4.6mm, 5μm) with mobile phase consisting of A-methanol B-water (50:50v/v) run in isocratic mode at flow rate of 1mL/min for 15min and detection at 273nm. The method showed linearity in the concentration range of 50-5000ng/mL with LOD of 10ng/mL and LLOQ of 50ng/mL for both LSF and PTX. Weighted linear regression analysis was also performed on the calibration data. The mean absolute recoveries were found to be 80.47±3.44 and 80.89±3.73% for LSF and PTX respectively. The method was successfully applied for studying the pharmacokinetics of LSF and PTX after IV bolus administration at dose of 25mg/kg in Wistar rat. In conclusion, a simple, sensitive, accurate and precise reversed-phase HPLC-UV method was established for simultaneous determination of LSF and PTX in rat plasma. Copyright © 2017 Elsevier B.V. All rights reserved.

Overcoming the response plateau in multiple myeloma: A novel bortezomib-based strategy for secondary induction and high-yield CD34+ stem cell mobilization

PubMed Central

Niesvizky, Ruben; Mark, Tomer M.; Ward, Maureen; Jayabalan, David S.; Pearse, Roger N.; Manco, Megan; Stern, Jessica; Christos, Paul J.; Mathews, Lena; Shore, Tsiporah B.; Zafar, Faiza; Pekle, Karen; Xiang, Zhaoying; Ely, Scott; Skerret, Donna; Chen-Kiang, Selina; Coleman, Morton; Lane, Maureen E.

2014-01-01

Purpose This phase 2 study evaluated bortezomib-based secondary induction and stem cell mobilization in 38 transplant-eligible myeloma patients who had an incomplete and stalled response to, or had relapsed after, previous immunomodulatory drug-based induction. Experimental design Patients received up to six 21-day cycles of bortezomib plus dexamethasone, with added liposomal doxorubicin for patients not achieving partial response or better by cycle 2 or very good partial response or better (≥VGPR) by cycle 4 (DoVeD), followed by bortezomib, high-dose cyclophosphamide, and filgrastim mobilization. Gene expression/signaling pathway analyses were conducted in purified CD34+ cells post-bortezomib-based mobilization and compared against patients who received only filgrastim ± cyclophosphamide. Plasma samples were similarly analyzed for quantification of associated protein markers. Results The response rate to DoVeD relative to the pre-DoVeD baseline was 61%, including 39% ≥VGPR. Deeper responses were achieved in 10 of 27 patients who received bortezomib-based mobilization; post-mobilization response rate was 96%, including 48% ≥VGPR, relative to the pre-DoVeD baseline. Median CD34+ cell yield was 23.2 × 106 cells/kg (median of 1 apheresis session). After a median follow-up of 46.6 months, median progression-free survival was 47.1 months from DoVeD initiation;5-year overall survival rate was 76.4%. Grade ≥3 adverse events included thrombocytopenia (13%), hand-foot syndrome (11%), peripheral neuropathy (8%), and neutropenia (5%). Bortezomib-based mobilization was associated with modulated expression of genes involved in stem cell migration. Conclusion Bortezomib-based secondary induction and mobilization could represent an alternative strategy for elimination of tumor burden in immunomodulatory drug-resistant patients that does not impact stem cell yield. PMID:23357980

Development and validation of a high performance liquid chromatography quantification method of levo-tetrahydropalmatine and its metabolites in plasma and brain tissues: application to a pharmacokinetic study.

PubMed

Abdallah, Inas A; Huang, Peng; Liu, Jing; Lee, David Y; Liu-Chen, Lee-Yuan; Hassan, Hazem E

2017-04-01

Levo-tetrahydropalmatine (l-THP) is an alkaloid isolated from Chinese medicinal herbs of the Corydalis and Stephania genera. It has been used in China for more than 40 years mainly as an analgesic with sedative/hypnotic effects. Despite its extensive use, its metabolism has not been quantitatively studied, nor there a sensitive reliable bioanalytical method for its quantification simultaneously with its metabolites. As such, the objective of this study was to develop and validate a sensitive and selective HPLC method for simultaneous quantification of l-THP and its desmethyl metabolites l-corydalmine (l-CD) and l-corypalmine (l-CP) in rat plasma and brain tissues. Rat plasma and brain samples were processed by liquid-liquid extraction using ethyl acetate. Chromatographic separation was achieved on a reversed-phase Symmetry® C 18 column (4.6 × 150 mm, 5 μm) at 25°C. The mobile phase consisted of acetonitrile-methanol-10 mm ammonium phosphate (pH 3) (10:30:60, v/v) and was used at a flow rate of 0.8 mL/min. The column eluent was monitored at excitation and emission wavelengths of 230 and 315 nm, respectively. The calibration curves were linear over the concentration range of 1-10,000 ng/mL. The intra- and interday reproducibility studies demonstrated accuracy and precision within the acceptance criteria of bioanalytical guidelines. The validated HPLC method was successfully applied to analyze samples from a pharmacokinetic study of l-THP in rats. Taken together, the developed method can be applied for bioanalysis of l-THP and its metabolites in rodents and potentially can be transferred for bioanalysis of human samples. Copyright © 2016 John Wiley & Sons, Ltd.

Quantification of nicotine, cotinine, trans-3'-hydroxycotinine and varenicline in human plasma by a sensitive and specific UPLC-tandem mass-spectrometry procedure for a clinical study on smoking cessation.

PubMed

Dobrinas, Maria; Choong, Eva; Noetzli, Muriel; Cornuz, Jacques; Ansermot, Nicolas; Eap, Chin B

2011-11-15

A sensitive and specific ultra performance liquid chromatography-tandem mass spectrometry method for the simultaneous quantification of nicotine, its metabolites cotinine and trans-3'-hydroxycotinine and varenicline in human plasma was developed and validated. Sample preparation was realized by solid phase extraction of the target compounds and of the internal standards (nicotine-d4, cotinine-d3, trans-3'-hydroxycotinine-d3 and CP-533,633, a structural analog of varenicline) from 0.5 mL of plasma, using a mixed-mode cation exchange support. Chromatographic separations were performed on a hydrophilic interaction liquid chromatography column (HILIC BEH 2.1×100 mm, 1.7 μm). A gradient program was used, with a 10 mM ammonium formate buffer pH 3/acetonitrile mobile phase at a flow of 0.4 mL/min. The compounds were detected on a triple quadrupole mass spectrometer, operated with an electrospray interface in positive ionization mode and quantification was performed using multiple reaction monitoring. Matrix effects were quantitatively evaluated with success, with coefficients of variation inferior to 8%. The procedure was fully validated according to Food and Drug Administration guidelines and to Société Française des Sciences et Techniques Pharmaceutiques. The concentration range was 2-500 ng/mL for nicotine, 1-1000 ng/mL for cotinine, 2-1000 ng/mL for trans-3'-hydroxycotinine and 1-500 ng/mL for varenicline, according to levels usually measured in plasma. Trueness (86.2-113.6%), repeatability (1.9-12.3%) and intermediate precision (4.4-15.9%) were found to be satisfactory, as well as stability in plasma. The procedure was successfully used to quantify nicotine, its metabolites and varenicline in more than 400 plasma samples from participants in a clinical study on smoking cessation. Copyright © 2011 Elsevier B.V. All rights reserved.

Development of a Stability-Indicating Stereoselective Method for Quantification of the Enantiomer in the Drug Substance and Pharmaceutical Dosage Form of Rosuvastatin Calcium by an Enhanced Approach

PubMed Central

Rajendra Reddy, Gangireddy; Ravindra Reddy, Papammagari; Siva Jyothi, Polisetty

2015-01-01

A novel, simple, precise, and stability-indicating stereoselective method was developed and validated for the accurate quantification of the enantiomer in the drug substance and pharmaceutical dosage forms of Rosuvastatin Calcium. The method is capable of quantifying the enantiomer in the presence of other related substances. The chromatographic separation was achieved with an immobilized cellulose stationary phase (Chiralpak IB) 250 mm x 4.6 mm x 5.0 μm particle size column with a mobile phase containing a mixture of n-hexane, dichloromethane, 2-propanol, and trifluoroacetic acid in the ratio 82:10:8:0.2 (v/v/v/v). The eluted compounds were monitored at 243 nm and the run time was 18 min. Multivariate analysis and statistical tools were used to develop this highly robust method in a short span of time. The stability-indicating power of the method was established by subjecting Rosuvastatin Calcium to the stress conditions (forced degradation) of acid, base, oxidative, thermal, humidity, and photolytic degradation. Major degradation products were identified and found to be well-resolved from the enantiomer peak, proving the stability-indicating power of the method. The developed method was validated as per International Conference on Harmonization (ICH) guidelines with respect to specificity, limit of detection and limit of quantification, precision, linearity, accuracy, and robustness. The method exhibited consistent, high-quality recoveries (100 ± 10%) with a high precision for the enantiomer. Linear regression analysis revealed an excellent correlation between the peak responses and concentrations (r2 value of 0.9977) for the enantiomer. The method is sensitive enough to quantify the enantiomer above 0.04% and detect the enantiomer above 0.015% in Rosuvastatin Calcium. The stability tests were also performed on the drug substances as per ICH norms. PMID:26839815

Development of a validated liquid chromatographic method for quantification of sorafenib tosylate in the presence of stress-induced degradation products and in biological matrix employing analytical quality by design approach.

PubMed

Sharma, Teenu; Khurana, Rajneet Kaur; Jain, Atul; Katare, O P; Singh, Bhupinder

2018-05-01

The current research work envisages an analytical quality by design-enabled development of a simple, rapid, sensitive, specific, robust and cost-effective stability-indicating reversed-phase high-performance liquid chromatographic method for determining stress-induced forced-degradation products of sorafenib tosylate (SFN). An Ishikawa fishbone diagram was constructed to embark upon analytical target profile and critical analytical attributes, i.e. peak area, theoretical plates, retention time and peak tailing. Factor screening using Taguchi orthogonal arrays and quality risk assessment studies carried out using failure mode effect analysis aided the selection of critical method parameters, i.e. mobile phase ratio and flow rate potentially affecting the chosen critical analytical attributes. Systematic optimization using response surface methodology of the chosen critical method parameters was carried out employing a two-factor-three-level-13-run, face-centered cubic design. A method operable design region was earmarked providing optimum method performance using numerical and graphical optimization. The optimum method employed a mobile phase composition consisting of acetonitrile and water (containing orthophosphoric acid, pH 4.1) at 65:35 v/v at a flow rate of 0.8 mL/min with UV detection at 265 nm using a C 18 column. Response surface methodology validation studies confirmed good efficiency and sensitivity of the developed method for analysis of SFN in mobile phase as well as in human plasma matrix. The forced degradation studies were conducted under different recommended stress conditions as per ICH Q1A (R2). Mass spectroscopy studies showed that SFN degrades in strongly acidic, alkaline and oxidative hydrolytic conditions at elevated temperature, while the drug was per se found to be photostable. Oxidative hydrolysis using 30% H 2 O 2 showed maximum degradation with products at retention times of 3.35, 3.65, 4.20 and 5.67 min. The absence of any significant change in the retention time of SFN and degradation products, formed under different stress conditions, ratified selectivity and specificity of the systematically developed method. Copyright © 2017 John Wiley & Sons, Ltd.

Determination of NVP-BEZ235, a dual PI3K and mTOR inhibitor, in human and mouse plasma and in mouse tissue homogenates by reversed-phase high-performance liquid chromatography with fluorescence detection.

PubMed

Lin, Fan; Chandrasekaran, Gayathri; de Gooijer, Mark C; Beijnen, Jos H; van Tellingen, Olaf

2012-07-15

NVP-BEZ235 is a novel dual inhibitor of PI3K/mTOR and currently undergoing phase I/II clinical trials for advanced solid tumors. We developed a sensitive and selective reversed-phase high-performance liquid chromatographic (HPLC) assay with fluorometric detection for quantification of NVP-BEZ235 in biological matrices. Liquid-liquid extraction with tert-butyl methyl ether was used for sample pre-treatment, yielding a recovery of >84%. Chromatographic separation of NVP-BEZ235 and the internal standard (IS) NVP-BBD130 was achieved on a GraceSmart C-18 column by isocratic elution with a mobile phase which consisted of acetonitrile, methanol, and milliQ water adjusted with acetic acid to pH 3.7 (20:36:44, v/v/v). Fluorescence detection using excitation and emission wavelengths of 270 and 425 nm, respectively, provided a selectivity and sensitivity allowing quantification down to 1 ng/ml in human plasma and linear calibration curves within a range of 1-1000 ng/ml. The assay was validated for human plasma, mouse plasma and a range of tissues. The accuracy, within-day and between-day precision for all matrices, was within the generally accepted 15% range. NVP-BEZ235 was stable for 72 h in pretreated samples in reconstitution mixture (acetonitrile-water (30:70, v/v)), but unstable in mouse tissue homogenates upon repeated freeze-thaw cycles or long term storage (≥24 h) at room temperature. A pilot pharmacokinetic study in mice demonstrated the applicability of this method for pharmacokinetic purposes. Overall, this assay is suitable for the pharmacokinetic studies of NVP-BEZ235 in mice and in human plasma. Copyright © 2012 Elsevier B.V. All rights reserved.

Consistency of flow quantifications in tridirectional phase-contrast MRI

NASA Astrophysics Data System (ADS)

Unterhinninghofen, R.; Ley, S.; Dillmann, R.

2009-02-01

Tridirectionally encoded phase-contrast MRI is a technique to non-invasively acquire time-resolved velocity vector fields of blood flow. These may not only be used to analyze pathological flow patterns, but also to quantify flow at arbitrary positions within the acquired volume. In this paper we examine the validity of this approach by analyzing the consistency of related quantifications instead of comparing it with an external reference measurement. Datasets of the thoracic aorta were acquired from 6 pigs, 1 healthy volunteer and 3 patients with artificial aortic valves. Using in-house software an elliptical flow quantification plane was placed manually at 6 positions along the descending aorta where it was rotated to 5 different angles. For each configuration flow was computed based on the original data and data that had been corrected for phase offsets. Results reveal that quantifications are more dependent on changes in position than on changes in angle. Phase offset correction considerably reduces this dependency. Overall consistency is good with a maximum variation coefficient of 9.9% and a mean variation coefficient of 7.2%.

High-performance Thin-layer Chromatographic-densitometric Quantification and Recovery of Bioactive Compounds for Identification of Elite Chemotypes of Gloriosa superba L. Collected from Sikkim Himalayas (India)

PubMed Central

Misra, Ankita; Shukla, Pushpendra Kumar; Kumar, Bhanu; Chand, Jai; Kushwaha, Poonam; Khalid, Md.; Singh Rawat, Ajay Kumar; Srivastava, Sharad

2017-01-01

Background: Gloriosa superba L. (Colchicaceae) is used as adjuvant therapy in gout for its potential antimitotic activity due to high colchicine(s) alkaloids. Objective: This study aimed to develop an easy, cheap, precise, and accurate high-performance thin-layer chromatographic (HPTLC) validated method for simultaneous quantification of bioactive alkaloids (colchicine and gloriosine) in G. superba L. and to identify its elite chemotype(s) from Sikkim Himalayas (India). Methods: The HPTLC chromatographic method was developed using mobile phase of chloroform: acetone: diethyl amine (5:4:1) at λmax of 350 nm. Results: Five germplasms were collected from targeted region, and on morpho-anatomical inspection, no significant variation was observed among them. Quantification data reveal that content of colchicine (Rf: 0.72) and gloriosine (Rf: 0.61) varies from 0.035%–0.150% to 0.006%–0.032% (dry wt. basis). Linearity of method was obtained in the concentration range of 100–400 ng/spot of marker(s), exhibiting regression coefficient of 0.9987 (colchicine) and 0.9983 (gloriosine) with optimum recovery of 97.79 ± 3.86 and 100.023% ± 0.01%, respectively. Limit of detection and limit of quantification were analyzed, respectively, as 6.245, 18.926 and 8.024, 24.316 (ng). Two germplasms, namely NBG-27 and NBG-26, were found to be elite chemotype of both the markers. Conclusion: The developed method is validated in terms of accuracy, recovery, and precision studies as per the ICH guidelines (2005) and can be adopted for the simultaneous quantification of colchicine and gloriosine in phytopharmaceuticals. In addition, this study is relevant to explore the chemotypic variability in metabolite content for commercial and medicinal purposes. SUMMARY An easy, cheap, precise, and accurate high performance thin layer chromatographic (HPTLC) validated method for simultaneous quantification of bioactive alkaloids (colchicine and gloriosine) in G. superba L.Five germplasms were collected from targeted region, and on morpho anatomical inspection, no significant variation was observed among themQuantification data reveal that content of colchicine (Rf: 0.72) and gloriosine (Rf: 0.61) varies from 0.035%–0.150% to 0.006%–0.032% (dry wt. basis)Two germplasms, namely NBG 27 and NBG 26, were found to be elite chemotype of both the markers. PMID:29142436

High-performance Thin-layer Chromatographic-densitometric Quantification and Recovery of Bioactive Compounds for Identification of Elite Chemotypes of Gloriosa superba L. Collected from Sikkim Himalayas (India).

PubMed

Misra, Ankita; Shukla, Pushpendra Kumar; Kumar, Bhanu; Chand, Jai; Kushwaha, Poonam; Khalid, Md; Singh Rawat, Ajay Kumar; Srivastava, Sharad

2017-10-01

Gloriosa superba L. (Colchicaceae) is used as adjuvant therapy in gout for its potential antimitotic activity due to high colchicine(s) alkaloids. This study aimed to develop an easy, cheap, precise, and accurate high-performance thin-layer chromatographic (HPTLC) validated method for simultaneous quantification of bioactive alkaloids (colchicine and gloriosine) in G. superba L. and to identify its elite chemotype(s) from Sikkim Himalayas (India). The HPTLC chromatographic method was developed using mobile phase of chloroform: acetone: diethyl amine (5:4:1) at λ max of 350 nm. Five germplasms were collected from targeted region, and on morpho-anatomical inspection, no significant variation was observed among them. Quantification data reveal that content of colchicine ( R f : 0.72) and gloriosine ( R f : 0.61) varies from 0.035%-0.150% to 0.006%-0.032% (dry wt. basis). Linearity of method was obtained in the concentration range of 100-400 ng/spot of marker(s), exhibiting regression coefficient of 0.9987 (colchicine) and 0.9983 (gloriosine) with optimum recovery of 97.79 ± 3.86 and 100.023% ± 0.01%, respectively. Limit of detection and limit of quantification were analyzed, respectively, as 6.245, 18.926 and 8.024, 24.316 (ng). Two germplasms, namely NBG-27 and NBG-26, were found to be elite chemotype of both the markers. The developed method is validated in terms of accuracy, recovery, and precision studies as per the ICH guidelines (2005) and can be adopted for the simultaneous quantification of colchicine and gloriosine in phytopharmaceuticals. In addition, this study is relevant to explore the chemotypic variability in metabolite content for commercial and medicinal purposes. An easy, cheap, precise, and accurate high performance thin layer chromatographic (HPTLC) validated method for simultaneous quantification of bioactive alkaloids (colchicine and gloriosine) in G. superba L.Five germplasms were collected from targeted region, and on morpho anatomical inspection, no significant variation was observed among themQuantification data reveal that content of colchicine (Rf: 0.72) and gloriosine (Rf: 0.61) varies from 0.035%-0.150% to 0.006%-0.032% (dry wt. basis)Two germplasms, namely NBG 27 and NBG 26, were found to be elite chemotype of both the markers.

Determination of phenolic acids and flavonoids in raw propolis by silica-supported ionic liquid-based matrix solid phase dispersion extraction high performance liquid chromatography-diode array detection.

PubMed

Wang, Zhibing; Sun, Rui; Wang, Yuanpeng; Li, Na; Lei, Lei; Yang, Xiao; Yu, Aimin; Qiu, Fangping; Zhang, Hanqi

2014-10-15

The silica-supported ionic liquid (S-SIL) was prepared by impregnation and used as the dispersion adsorbent of matrix solid phase dispersion (MSPD) for the simultaneous extraction of eight phenolic acids and flavonoids, including caffeic acid, ferulic acid, morin, luteolin, quercetin, apigenin, chrysin, and kaempferide in raw propolis. High performance liquid chromatography with a Zorbax SB-C18 column (150mm×4.6mm, 3.5μm) was used for separation of the analytes. The mobile phase consisted of 0.2% phosphoric acid aqueous solution and acetonitrile and the flow rate of the mobile phase was 0.5mL/min. The experimental conditions for silica-supported ionic liquid-based matrix solid phase dispersion (S-SIL-based MSPD) were optimized. S-SIL containing 10% [C6MIM]Cl was used as dispersant, 20mL of n-hexane as washing solvent and 15mL of methanol as elution solvent. The ratio of S-SIL to sample was selected to be 4:1. The standard curves showed good linear relationship (r>0.9995). The limits of detection and quantification were in the range of 5.8-22.2ngmL(-1) and 19.2-74.0ngmL(-1), respectively. The relative standard deviations (RSDs) of intra-day and inter-day determination were lower than 8.80% and 11.19%, respectively. The recoveries were between 65.51% and 92.32% with RSDs lower than 8.95%. Compared with ultrasound-assisted extraction (UAE) and soxhlet extraction, the present method consumed less sample, organic solvent, and extraction time, although the extraction yields obtained by S-SIL-based MSPD are slightly lower than those obtained by UAE. Copyright © 2014 Elsevier B.V. All rights reserved.

[Simultaneous determination of vitamins A, D3 and E in infant formula and adult nutritions by online two-dimensional liquid chromatography].

PubMed

Zhang, Yanhai; Qibule, Hasi; Jin, Yan; Wang, Jia; Ma, Wenli

2015-03-01

A rapid method for the simultaneous determination of vitamins A, D3 and E in infant formula and adult nutritions has been developed using online two-dimensional liquid chromatography (2D-LC). First of all, C8 and polar embedded C18 columns were chosen as the first and second dimensional column respectively according to hydrophobic-subtraction model, which constituted excellent orthogonal separation system. The detection wavelengths were set at 263 nm for vitamin D3, 296 nm for vitamin E and 325 nm for vitamin A. The purification of vitamin D3 and quantifications of vitamins A and E were completed simultaneously in the first dimensional separation using the left pump of Dual Gradient LC (DGLC) with methanol, acetonitrile and water as mobile phases. The heart-cutting time window of vitamin D3 was confirmed according to the retention time of vitamin D3 in the first dimensional separation. The elute from the first dimensional column (1-D column) which contained vitamin D3 was collected by a 500 µL sample loop and then taken into the second dimensional column (2-D column) by the right pump of DGLC with methanol, acetonitrile and water as mobile phases. The quantification of vitamin D3 was performed in the second dimensional separation with vitamin D2 as internal standard. At last, this method was applied for the analysis of the three vitamins in milk powder, cheese and yogurt. The injected sample solution with no further purification was pre-treated by hot-saponification using 1. 25 kg/L KOH solution and extracted by petroleum ether solvent. The recoveries of vitamin D3 spiked in all samples were 75.50%-85.00%. There was no statistically significant difference for the results between this method and standard method through t-test. The results indicate that vitamins A, D3 and E in infant formula and adult fortified dairy can be determined rapidly and accurately with this method.

A rapid, LC-MS/MS assay for quantification of piperacillin and tazobactam in human plasma and pleural fluid; application to a clinical pharmacokinetic study.

PubMed

Popowicz, Natalia D; O'Halloran, Sean J; Fitzgerald, Deirdre; Lee, Y C Gary; Joyce, David A

2018-04-01

Piperacillin, in combination with tazobactam is a common first-line antibiotic used for the treatment of pleural infection, however its pleural pharmacokinetics and penetration has not previously been reported. The objective of this work was to develop and validate a rapid and sensitive liquid chromatography with tandem mass spectrometry (LC-MS/MS) assay for quantification of piperacillin (PIP) and tazobactam (TAZ). PIP and TAZ were extracted from both human plasma and pleural fluid samples by protein precipitation in methanol containing the internal standards (IS) piperacillin-d 5 (PIP-d 5 ) and sulbactam (SUL). Briefly, 5 μL of sample was mixed with 125 μL of methanol containing IS, vortexed and centrifuged. Supernatant (50 μL) was diluted into 500 μL of mobile phase containing 10 mM of ammonium bicarbonate in LCMS grade water and transferred to the autosampler tray. Electrospray ionization in positive mode and multiple reaction monitoring (MRM) were used for PIP and PIP-d 5 at the transitions m/z 518.2 → 143.2 and m/z 523.2 → 148.2 respectively, and electrospray ionization in negative mode and MRM were used for TAZ and SUL at the transitions m/z 299.1 → 138.1 and m/z 232.4 → 140.1. The chromatographic separation was achieved using an Acquity BEH C-18 column with gradient elution of mobile phase containing 10 mmol/L ammonium bicarbonate in water and methanol. A linear range was observed over the concentration range of 0.25-352 mg/L and 0.25-50.5 mg/L for PIP and TAZ respectively. Complete method validation was performed according to US FDA guidelines for selectivity, specificity, precision and accuracy, LLOQ, matrix effects, recovery and stability, with all results within acceptable limits. This method was successfully applied to two patients with pleural infection and is suitable for further pharmacokinetic studies and therapeutic drug monitoring. Crown Copyright © 2018. Published by Elsevier B.V. All rights reserved.

Dispersive solid-phase extraction followed by high-performance liquid chromatography/tandem mass spectrometry for the determination of ricinine in cooking oil.

PubMed

Cai, Meiqiang; Chen, Xiaohong; Wei, Xiaoqing; Pan, Shengdong; Zhao, Yonggang; Jin, Micong

2014-09-01

A rapid and accurate method by liquid chromatography/tandem mass spectrometry (LC-MS/MS) using positive electrospray was established for the determination of ricinine in cooking oils. The homogenized samples, spiked with (13)C6-labelled ricinine as an internal standard, were extracted using ethanol/water (20:80, v/v) and purified by dispersive solid-phase extraction (dSPE) using primary-secondary amine (PSA) and C18 as adsorbents. The extract was separated in a short C18 reversed-phase column using methanol/water (25:75, v/v) as the mobile phase and detected in multiple reaction monitoring (MRM) mode with the absolute matrix effect of 93.2-102.2%. The alkali-metal adduct ions were discussed and the mass/mass fragmentation pathway was explained. Ricinine showed good linearity in the range of 0.5-50.0 μg/kg with the limit of quantitation 0.5 μg/kg. The recoveries were between 86.0% and 98.3% with the intra- and inter-day RSDs of 2.6-7.0%, 5.5-10.8%, respectively. This method could be applied to the rapid quantification of ricinine in cooking oils. Crown Copyright © 2014. Published by Elsevier Ltd. All rights reserved.

Simultaneous analysis of different classes of phytohormones in coconut (Cocos nucifera L.) water using high-performance liquid chromatography and liquid chromatography-tandem mass spectrometry after solid-phase extraction.

PubMed

Ma, Zhen; Ge, Liya; Lee, Anna S Y; Yong, Jean Wan Hong; Tan, Swee Ngin; Ong, Eng Shi

2008-03-10

Coconut (Cocos nucifera L.) water, which contains many uncharacterized phytohormones is extensively used as a growth promoting supplement in plant tissue culture. In this paper, a high-performance liquid chromatography (HPLC) method was developed for the simultaneous determination of various classes phytohormones, including indole-3-acetic acid (IAA), indole-3-butyric acid (IBA), abscisic acid (ABA), gibberellic acid (GA), zeatin (Z), N(6)-benzyladenine (BA), alpha-naphthaleneacetic acid (NAA) and 2,4-dichlorophenoxyacetic acid (2,4-D) in young coconut water (CW). The analysis was carried out using a reverse-phase HPLC gradient elution, with an aqueous mobile phase (containing 0.1% formic acid, pH adjusted to 3.2 with triethylamine (TEA)) modified by methanol, and solute detection made at 265 nm wavelength. The method was validated for specificity, quantification, accuracy and precision. After preconcentration of putative endogenous phytohormones in CW using C(18) solid-phase extraction (SPE) cartridges, the HPLC method was able to screen for putative endogenous phytohormones present in CW. Finally, the identities of the putative phytohormones present in CW were further confirmed using independent liquid chromatography-tandem mass spectrometry (LC-MS/MS) equipped with an electrospray ionization (ESI) interface.

Ion chromatography in the manufacture of multilayer circuit boards

NASA Astrophysics Data System (ADS)

Smith, Robert E.

1990-01-01

Ion chromatography (IC) has proven useful in analyzing chemical solutions used in the manufacture of multilayer circuit boards. Unlike other chemical quantification techniques, IC provides results on ions not expected in the production solutions. Thus, solution contamination and break-down products can be monitored in every phase of the circuit board manufacturing. During the first phase, epoxy laminates experience an etchback, first in chromic acid, which can be analyzed for trace chloride and sulfate, then in ammonium bifluoride/HCl, which can be analyzed for fluoride and chloride. Following a wet-blasting to roughen up the surface, 20 microinches of copper are deposited using an electroless bath. Again, IC is applicable for monitoring formate, tartarate, and sulfate levels. Next, an acid copper bath is used to electroplate the through holes with 0.001 inches of ductile copper. This bath is analyzed for trace chloride. Photoimaging is then performed, and the organic solvents used can be assayed for trace ionic chloride. Finally, a fluoroboric acid-based tin-lead bath is used to deposit a solderable alloy. This bath is analyzed for fluoroborate, tin, and lead. In addition, mobile phase ion chromatography (MPIC) is used to monitor the nonionic organic brighteners in the baths.

Phospholipid hydrolysis in a pharmaceutical emulsion assessed by physicochemical parameters and a new analytical method.

PubMed

Rabinovich-Guilatt, Laura; Dubernet, Catherine; Gaudin, Karen; Lambert, Gregory; Couvreur, Patrick; Chaminade, Pierre

2005-09-01

The aim of this work was to develop a simple high-performance liquid chromatography (HPLC) technique with evaporative light scattering detection (ELSD) for the separation and quantification of the major phospholipid (PL) and lysophospholipid (LPL) classes contained in a pharmaceutical phospholipid-based emulsion. In the established method, phosphatidylcholine (PC), phosphatidylethanolamine (PE), sphingomyeline (SM), lysophosphatidylcholine (LPC) and lysophosphatidylethanolamine (LPE) were separated with a PVA-Sil stationary phase and a binary gradient from pure chloroform to methanol:water (94:6 v/v) at 3.4%/min. The ELSD detection was enhanced using 0.1% triethylamine and formic acid in each gradient mobile phases. Factors such as stationary phase and ELSD drift tube temperature were optimized, concluding in optimal temperatures of 25 degrees C for separation and 50 degrees C for evaporation. This HPLC-ELSD method was then applied to a PL-emulsion exposed to autoclaving and accelerated thermal conditions at 50 degrees C. Hydrolysis of PC and PE followed first-order kinetics, representing only 45% of the total lipid mass after 3 months. The chemical stability was correlated to commonly measured formulation physical and physico-chemical parameters such as droplet size, emulsion pH and zeta-potential.

43 CFR 11.71 - Quantification phase-service reduction quantification.

Code of Federal Regulations, 2011 CFR

2011-10-01

...-discharge-or-release condition. (c) Contents of the quantification. The following factors should be included...; and (6) Factors identified in the specific guidance in paragraphs (h), (i), (j), (k), and (l) of this section dealing with the different kinds of natural resources. (d) Selection of resources, services, and...

43 CFR 11.71 - Quantification phase-service reduction quantification.

Code of Federal Regulations, 2010 CFR

2010-10-01

...-discharge-or-release condition. (c) Contents of the quantification. The following factors should be included...; and (6) Factors identified in the specific guidance in paragraphs (h), (i), (j), (k), and (l) of this section dealing with the different kinds of natural resources. (d) Selection of resources, services, and...

Procedure for chromatography involving sample solvent with higher elution strength than the mobile phase.

PubMed

Patil, Nitin S; Mendhe, Rakesh B; Sankar, Ajeet A; Iyer, Harish

2008-01-11

In preparative chromatography, often the solubility of the sample in the mobile phase is limited, making the mobile phase unsuitable as a solvent for preparation of load. Generally, solvents that have high solubility for the sample also have higher elution strengths than the mobile phase. Additionally, at high loading volumes, these strong sample solvents are known to adversely affect the band profiles leading to poor chromatographic performance. Here, we show that controlling the mobile phase strength during loading and post-load elution resulted in improved band profiles when the sample solvent was stronger than the mobile phase. Such an approach improves performance in preparative chromatography by allowing either higher sample loading or higher organic content in mobile phase (without loss of yield). Alternately, the approach can be used for improvement in performance by increase in yield or product purity.

30 CFR 77.900 - Low- and medium-voltage circuits serving portable or mobile three-phase alternating current...

Code of Federal Regulations, 2011 CFR

2011-07-01

... portable or mobile three-phase alternating current equipment; circuit breakers. 77.900 Section 77.900... mobile three-phase alternating current equipment; circuit breakers. Low- and medium-voltage circuits supplying power to portable or mobile three-phase alternating current equipment shall be protected by...

Identification and quantification of vinpocetine and picamilon in dietary supplements sold in the United States.

PubMed

Avula, Bharathi; Chittiboyina, Amar G; Sagi, Satyanarayanaraju; Wang, Yan-Hong; Wang, Mei; Khan, Ikhlas A; Cohen, Pieter A

2016-01-01

Vinpocetine and picamilon are drugs prescribed in many countries to treat a variety of cerebrovascular disorders. In the United States, vinpocetine and picamilon have never been approved by the US Food and Drug Administration, but they are both available for sale directly to consumers as dietary supplements. We designed our study to determine the accuracy of supplement labels with regard to the presence and quantity of vinpocetine and picamilon. A validated ultra-high performance liquid chromatography-photodiode-array method was developed for the quantification of vinpocetine and picamilon. The separation was achieved using a reversed phase (C-18) column, photodiode array detection, and water/acetonitrile as the mobile phase. Vinpocetine and picamilon were detected at concentrations as low as 10 and 50 ng/mL, respectively. The presence of vinpocetine and picamilon was confirmed using reference standards. Twenty-three supplements labelled as containing vinpocetine were available for sale at two large supplement retail chains; 17 contained vinpocetine with quantities ranging from 0.3 to 32 mg per recommended daily serving. No vinpocetine was detected in six of the sampled supplements. The supplement label implied that vinpocetine was a constituent of lesser periwinkle in three of the supplements. Of the 31 picamilon supplements available for sale from a variety of retailers: 30 contained picamilon in quantities ranging from 2.7 to 721.5 mg per recommended daily serving. We found that consumers cannot obtain accurate information from supplement labels regarding the presence or quantity of vinpocetine and picamilon. Copyright © 2015 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd.

An on-line coupling of nanofibrous extraction with column-switching high performance liquid chromatography - A case study on the determination of bisphenol A in environmental water samples.

PubMed

Háková, Martina; Chocholoušová Havlíková, Lucie; Chvojka, Jiří; Solich, Petr; Šatínský, Dalibor

2018-02-01

Polyamide 6 nanofiber polymers were used as modern sorbents for on-line solid phase extraction (SPE) coupled with liquid chromatography. The on-line SPE system was tested for the determination of bisphenol A in river water samples. Polyamide nanofibers were prepared using needleless electrospinning, inserted into a mini-column cartridge (5 × 4.6mm) and coupled with HPLC. The effect of column packing and the amount of polyamide 6 on extraction efficiency was tested and the packing process was optimized. The proposed method was performed using a 50-µL sample injection followed by an on-line nanofibrous extraction procedure. The influence of the washing mobile phase on the retention of bisphenol A during the extraction procedure was evaluated. Ascentis ® Express C18 (10cm × 4.6mm) core-shell column was used as an analytical column. Fluorescence detection wavelengths (λ ex = 225nm and λ em = 320nm) were used for identification and quantification of Bisphenol A in river waters. The linearity was tested in the range from 2 to 500µgL -1 (using nine calibration points). The limits of detection and quantification were 0.6 and 2µgL -1 , respectively. The developed method was successfully used for the determination of bisphenol A in various samples of river waters in the Czech Republic (The Ohře, Labe, Nisa, Úpa, and Opava Rivers). Copyright © 2017 Elsevier B.V. All rights reserved.

UPLC-MS/MS determination of ptaquiloside and pterosin B in preserved natural water.

PubMed

Clauson-Kaas, Frederik; Hansen, Hans Christian Bruun; Strobel, Bjarne W

2016-11-01

The naturally occurring carcinogen ptaquiloside and its degradation product pterosin B are found in water leaching from bracken stands. The objective of this work is to present a new sample preservation method and a fast UPLC-MS/MS method for quantification of ptaquiloside and pterosin B in environmental water samples, employing a novel internal standard. A faster, reliable, and efficient method was developed for isolation of high purity ptaquiloside and pterosin B from plant material for use as analytical standards, with purity verified by 1 H-NMR. The chemical analysis was performed by cleanup and preconcentration of samples with solid phase extraction, before analyte quantification with UPLC-MS/MS. By including gradient elution and optimizing the liquid chromatography mobile phase buffer system, a total run cycle of 5 min was achieved, with method detection limits, including preconcentration, of 8 and 4 ng/L for ptaquiloside and pterosin B, respectively. The use of loganin as internal standard improved repeatability of the determination of both analytes, though it could not be employed for sample preparation. Buffering raw water samples in situ with ammonium acetate to pH ∼5.5 decisively increased sample integrity at realistic transportation and storing conditions prior to extraction. Groundwater samples collected in November 2015 at the shallow water table below a Danish bracken stand were preserved and analyzed using the above methods, and PTA concentrations of 3.8 ± 0.24 μg/L (±sd, n = 3) were found, much higher than previously reported. Graphical abstract Workflow overview of ptaquiloside determination.

Improvement and validation of a high-performance liquid chromatography in tandem mass spectrometry method for monitoring of omeprazole in plasma.

PubMed

Wojnicz, Aneta; Gil García, Ana Isabel; Román-Martínez, Manuel; Ochoa-Mazarro, Dolores; Abad-Santos, Francisco; Ruiz-Nuño, Ana

2015-06-01

Omeprazole (OME) is a proton pump inhibitor with a 58% bioavailability after a single oral dose. It is subject to marked interindividual variations and significant drug-drug interactions. The authors developed a simple and rapid method based on liquid chromatography in tandem with mass spectrometry with solid phase extraction and isotope-labeled internal standard to monitor plasma levels of OME in pharmacokinetics and drug-drug interaction studies. OME and its internal standard (OME-D3) were eluted with a Zorbax Extend C-18 rapid resolution column (4.6 × 50 mm, 3.5 μm) at 25°C, under isocratic conditions through a mobile phase consisting of 1 mM ammonium acetate, pH 8.5 (55%), and acetonitrile (45%). The flow rate was 0.8 mL/min, and the chromatogram run time was 1.2 minutes. OME was detected and quantified by liquid chromatography in tandem with mass spectrometry with positive electrospray ionization, which operates in multiple-reaction monitoring mode. The method was linear in the range of 1.5-2000 ng/mL for OME. The validation assays for accuracy and precision, matrix effect, extraction recovery, and stability of the samples for OME did not deviate more than 20% for the lower limit of quantification and no more than 15% for other quality controls. These findings are consistent with the requirements of regulatory agencies. The method enables rapid quantification of OME concentrations and can be used in pharmacokinetic and drug-drug interaction studies.

Simultaneous Determination of Celecoxib, Erlotinib, and its Metabolite Desmethyl-Erlotinib (OSI-420) in Rat Plasma by Liquid chromatography/Tandem Mass Spectrometry with Positive/Negative Ion-Switching Electrospray Ionisation

PubMed Central

Thappali, Satheeshmanikandan R. S.; Varanasi, Kanthikiran; Veeraraghavan, Sridhar; Arla, Rambabu; Chennupati, Sandhya; Rajamanickam, Madheswaran; Vakkalanka, Swaroop; Khagga, Mukkanti

2012-01-01

A new method for the simultaneous determination of celecoxib, erlotinib, and its active metabolite desmethyl-erlotinib (OSI-420) in rat plasma, by liquid chromatography/tandem mass spectrometry with positive/negative ion-switching electrospray ionization mode, was developed and validated. Protein precipitation with methanol was selected as the method for preparing the samples. The analytes were separated on a reverse-phase C18 column (50mm×4.6mm i.d., 3μ) using methanol: 2 mM ammonium acetate buffer, and pH 4.0 as the mobile phase at a flow rate 0.8 mL/min. Sitagliptin and Efervirenz were used as the internal standards for quantification. The determination was carried out on a Theremo Finnigan Quantam ultra triple-quadrupole mass spectrometer, operated in selected reaction monitoring (SRM) mode using the following transitions monitored simultaneously: positive m/z 394.5→278.1 for erlotinib, m/z 380.3→278.1 for desmethyl erlotinib (OSI-420), and negative m/z −380.1→ −316.3 for celecoxib. The limits of quantification (LOQs) were 1.5 ng/mL for Celecoxib, erlotinib, and OSI-420. Within- and between-day accuracy and precision of the validated method were within the acceptable limits of < 15% at all concentrations. The quantitation method was successfully applied for the simultaneous estimation of celecoxib, erlotinib, and desmethyl erlotinib in a pharmacokinetic study in Wistar rats. PMID:23008811

Quantitative determination of dopamine in human plasma by a highly sensitive LC-MS/MS assay: Application in preterm neonates.

PubMed

Zhang, Daping; Wu, Lei; Chow, Diana S-L; Tam, Vincent H; Rios, Danielle R

2016-01-05

The determination of dopamine facilitates better understanding of the complex brain disorders in the central nervous system and the regulation of endocrine system, cardiovascular functions and renal functions in the periphery. The purpose of this study was to develop a highly sensitive and reliable assay for the quantification of dopamine in human neonate plasma. Dopamine was extracted from human plasma by strong cation exchange (SCX) solid phase extraction (SPE), and subsequently derivatized with propionic anhydride. The derivatized analyte was separated by a Waters Acquity UPLC BEH C18 column using gradient elution at 0.4 ml/min with mobile phases A (0.2% formic acid in water [v/v]) and B (MeOH-ACN [v/v, 30:70]). Analysis was performed under positive electrospray ionization tandem mass spectrometer (ESI-MS/MS) in the multiple reaction monitoring (MRM) mode. The stable and relatively non-polar nature of the derivatized analyte enables reliable quantification of dopamine in the range of 10-1000 pg/ml using 200 μl of plasma sample. The method was validated with intra-day and inter-day precision less than 7%, and the intra-day and inter-day accuracy of 91.9-101.9% and 92.3-102.6%, respectively. The validated assay was applied to quantify dopamine levels in two preterm neonate plasma samples. In conclusion, a sensitive and selective LC-MS/MS method has been developed and validated, and successfully used for the determination of plasma dopamine levels in preterm neonates. Copyright © 2015 Elsevier B.V. All rights reserved.

An improved LC-MS/MS method for the quantification of alverine and para hydroxy alverine in human plasma for a bioequivalence study☆.

PubMed

Rathod, Dhiraj M; Patel, Keyur R; Mistri, Hiren N; Jangid, Arvind G; Shrivastav, Pranav S; Sanyal, Mallika

2017-04-01

A highly sensitive and selective high performance liquid chromatography-tandem mass spectrometry method was developed and validated for the quantification of alverine (ALV) and its active metabolite, para hydroxy alverine (PHA), in human plasma. For sample preparation, solid phase extraction of analytes was performed on Phenomenex Strata-X cartridges using alverine-d5 as the internal standard. The analytes were separated on Symmetry Shield RP 18 (150 mm×3.9 mm, 5 µm) column with a mobile phase consisting of acetonitrile and 10 mM ammonium formate (65:35, v/v). Detection and quantitation was done by electrospray ionization mass spectrometry in the positive mode using multiple reaction monitoring. The assay method was fully validated over the concentration range of 15.0-15,000 pg/mL for ALV and 30.0-15,000 pg/mL for PHA. The intra-day and inter-day accuracy and precision (% CV) ranged from 94.00% to 96.00% and 0.48% to 4.15% for both the analytes. The mean recovery obtained for ALV and PHA was 80.59% and 81.26%, respectively. Matrix effect, expressed as IS-normalized matrix factor ranged from 0.982 to 1.009 for both the analytes. The application of the method was demonstrated for the specific analysis of ALV and PHA for a bioequivalence study in 52 healthy subjects using 120 mg ALV capsules. The assay reproducibility was also verified by reanalysis of 175 incurred subject samples.

Multiscale Characterization and Quantification of Arsenic Mobilization and Attenuation During Injection of Treated Coal Seam Gas Coproduced Water into Deep Aquifers

NASA Astrophysics Data System (ADS)

Rathi, Bhasker; Siade, Adam J.; Donn, Michael J.; Helm, Lauren; Morris, Ryan; Davis, James A.; Berg, Michael; Prommer, Henning

2017-12-01

Coal seam gas production involves generation and management of large amounts of co-produced water. One of the most suitable methods of management is injection into deep aquifers. Field injection trials may be used to support the predictions of anticipated hydrological and geochemical impacts of injection. The present work employs reactive transport modeling (RTM) for a comprehensive analysis of data collected from a trial where arsenic mobilization was observed. Arsenic sorption behavior was studied through laboratory experiments, accompanied by the development of a surface complexation model (SCM). A field-scale RTM that incorporated the laboratory-derived SCM was used to simulate the data collected during the field injection trial and then to predict the long-term fate of arsenic. We propose a new practical procedure which integrates laboratory and field-scale models using a Monte Carlo type uncertainty analysis and alleviates a significant proportion of the computational effort required for predictive uncertainty quantification. The results illustrate that both arsenic desorption under alkaline conditions and pyrite oxidation have likely contributed to the arsenic mobilization that was observed during the field trial. The predictive simulations show that arsenic concentrations would likely remain very low if the potential for pyrite oxidation is minimized through complete deoxygenation of the injectant. The proposed modeling and predictive uncertainty quantification method can be implemented for a wide range of groundwater studies that investigate the risks of metal(loid) or radionuclide contamination.

First measurements of a carbon dioxide plume from an industrial source using a ground based mobile differential absorption lidar.

PubMed

Robinson, R A; Gardiner, T D; Innocenti, F; Finlayson, A; Woods, P T; Few, J F M

2014-08-01

The emission of carbon dioxide (CO2) from industrial sources is one of the main anthropogenic contributors to the greenhouse effect. Direct remote sensing of CO2 emissions using optical methods offers the potential for the identification and quantification of CO2 emissions. We report the development and demonstration of a ground based mobile differential absorption lidar (DIAL) able to measure the mass emission rate of CO2 in the plume from a power station. To our knowledge DIAL has not previously been successfully applied to the measurement of emission plumes of CO2 from industrial sources. A significant challenge in observing industrial CO2 emission plumes is the ability to discriminate and observe localised concentrations of CO2 above the locally observed background level. The objectives of the study were to modify our existing mobile infrared DIAL system to enable CO2 measurements and to demonstrate the system at a power plant to assess the feasibility of the technique for the identification and quantification of CO2 emissions. The results of this preliminary study showed very good agreement with the expected emissions calculated by the site. The detection limit obtained from the measurements, however, requires further improvement to provide quantification of smaller emitters of CO2, for example for the detection of fugitive emissions. This study has shown that in principle, remote optical sensing technology will have the potential to provide useful direct data on CO2 mass emission rates.

Selective Distance-Based K+ Quantification on Paper-Based Microfluidics.

PubMed

Gerold, Chase T; Bakker, Eric; Henry, Charles S

2018-04-03

In this study, paper-based microfluidic devices (μPADs) capable of K + quantification in aqueous samples, as well as in human serum, using both colorimetric and distance-based methods are described. A lipophilic phase containing potassium ionophore I (valinomycin) was utilized to achieve highly selective quantification of K + in the presence of Na + , Li + , and Mg 2+ ions. Successful addition of a suspended lipophilic phase to a wax printed paper-based device is described and offers a solution to current approaches that rely on organic solvents, which damage wax barriers. The approach provides an avenue for future alkali/alkaline quantification utilizing μPADs. Colorimetric spot tests allowed for K + quantification from 0.1-5.0 mM using only 3.00 μL of sample solution. Selective distance-based quantification required small sample volumes (6.00 μL) and gave responses sensitive enough to distinguish between 1.0 and 2.5 mM of sample K + . μPADs using distance-based methods were also capable of differentiating between 4.3 and 6.9 mM K + in human serum samples. Distance-based methods required no digital analysis, electronic hardware, or pumps; any steps required for quantification could be carried out using the naked eye.

Analysis of glyoxal and related substances by means of high-performance liquid chromatography with refractive index detection.

PubMed

Zhang, Zhiyong; Zhao, Dishun; Xu, Baoyun

2013-01-01

A simple and rapid method is described for the analysis of glyoxal and related substances by high-performance liquid chromatography with a refractive index detector. The following chromatographic conditions were adopted: Aminex HPX-87H column, mobile phase consisting of 0.01N H2SO4, flow rate of 0.8 mL/min and temperature of 65°C. The application of the analytical technique developed in this study demonstrated that the aqueous reaction mixture produced by the oxidation of acetaldehyde with HNO3 was composed of glyoxal, acetaldehyde, acetic acid, formic acid, glyoxylic acid, oxalic acid, butanedione and glycolic acid. The method was validated by evaluating analytical parameters such as linearity, limits of detection and quantification, precision, recovery and robustness. The proposed methodology was successfully applied to the production of glyoxal.

Performance analysis of jump-gliding locomotion for miniature robotics.

PubMed

Vidyasagar, A; Zufferey, Jean-Christohphe; Floreano, Dario; Kovač, M

2015-03-26

Recent work suggests that jumping locomotion in combination with a gliding phase can be used as an effective mobility principle in robotics. Compared to pure jumping without a gliding phase, the potential benefits of hybrid jump-gliding locomotion includes the ability to extend the distance travelled and reduce the potentially damaging impact forces upon landing. This publication evaluates the performance of jump-gliding locomotion and provides models for the analysis of the relevant dynamics of flight. It also defines a jump-gliding envelope that encompasses the range that can be achieved with jump-gliding robots and that can be used to evaluate the performance and improvement potential of jump-gliding robots. We present first a planar dynamic model and then a simplified closed form model, which allow for quantification of the distance travelled and the impact energy on landing. In order to validate the prediction of these models, we validate the model with experiments using a novel jump-gliding robot, named the 'EPFL jump-glider'. It has a mass of 16.5 g and is able to perform jumps from elevated positions, perform steered gliding flight, land safely and traverse on the ground by repetitive jumping. The experiments indicate that the developed jump-gliding model fits very well with the measured flight data using the EPFL jump-glider, confirming the benefits of jump-gliding locomotion to mobile robotics. The jump-glide envelope considerations indicate that the EPFL jump-glider, when traversing from a 2 m height, reaches 74.3% of optimal jump-gliding distance compared to pure jumping without a gliding phase which only reaches 33.4% of the optimal jump-gliding distance. Methods of further improving flight performance based on the models and inspiration from biological systems are presented providing mechanical design pathways to future jump-gliding robot designs.

Novel Chromatographic Methods for Simultaneous Quantification of Fish and Wheat Germ Oils Mixture in Pharmaceutical Dosage Forms.

PubMed

El-Yazbi, Amira F; El-Hawiet, Amr

2017-05-01

Two simple, direct and environment-friendly chromatographic methods, high-performance liquid chromatography (HPLC) and high-performance thin layer chromatographic (HPTLC), were developed for the determination of a binary mixture of fish oil (FO) and wheat germ oil (WGO), for the first time, in their pharmaceutical dosage forms with no need for any sample pretreatment. The HPLC separation was carried out using C-18 stationary phase with mobile phase of 15% formic acid (pH 6), methanol and acetonitrile through gradient-elution, 1.5 mL min-1 flow-rate and detection at 215 nm for FO and 280 nm for WGO. HPTLC separation was carried out on silica-coated plates using diethyl ether-petroleum ether (0.5:9.5, v/v) as mobile phase. Detection was at 215 nm for FO and 240 nm for WGO. Regression analysis showed good linear relationship with r > 0.999 in the concentration-ranges of 0.2-2 mg mL-1 and 2.5-20 μg band-1 for WGO by HPLC and HPTLC methods, respectively, and 0.4-10 mg mL-1 and 25-200 μg band-1 for FO by HPLC and HPTLC methods, respectively. The methods were validated, showed good analytical performance and were successfully applied for the analysis of pharmaceutical formulations and synthetic mixtures of the analytes with good recoveries. Therefore, the two methods could be conveniently adopted for routine analysis of similar products in quality control laboratories of pharmaceutical industries especially that simultaneous determination of FO-WGO mixture has not been reported previously. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

UPLC and LC-MS studies on degradation behavior of irinotecan hydrochloride and development of a validated stability-indicating ultra-performance liquid chromatographic method for determination of irinotecan hydrochloride and its impurities in pharmaceutical dosage forms.

PubMed

Kumar, Navneet; Sangeetha, Dhanaraj; Reddy, Sunil P

2012-10-01

The objective of the current investigation was to study the degradation behavior of irinotecan hydrochloride under different International Conference on Harmonization (ICH) recommended stress conditions using ultra-performance liquid chromatography and liquid chromatography-mass spectrometry and to establish a validated stability-indicating reverse-phase ultra-performance liquid chromatographic method for the quantitative determination of irinotecan hydrochloride and its seven impurities and degradation products in pharmaceutical dosage forms. Irinotecan hydrochloride was subjected to the stress conditions of oxidative, acid, base, hydrolytic, thermal and photolytic degradation. Irinotecan hydrochloride was found to degrade significantly in oxidative and base hydrolysis and photolytic degradation conditions. The degradation products were well resolved from the main peak and its impurities, thus proving the stability-indicating power of the method. Chromatographic separation was achieved on a Waters Acquity BEH C8 (100 × 2.1 mm) 1.7-µm column with a mobile phase containing a gradient mixture of solvent A (0.02M KH(2)PO(4) buffer, pH 3.4) and solvent B (a mixture of acetonitrile and methanol in the ratio of 62:38 v/v). The mobile phase was delivered at a flow rate of 0.3 mL/min with ultraviolet detection at 220 nm. The run time was 8 min, within which irinotecan and its seven impurities and degradation products were satisfactorily separated. The developed method was validated as per ICH guidelines with respect to specificity, linearity, limit of detection, limit of quantification, accuracy, precision and robustness. This method was also suitable for the assay determination of irinotecan hydrochloride in pharmaceutical dosage forms.

Development and validation of a UPLC method for the determination of duloxetine hydrochloride residues on pharmaceutical manufacturing equipment surfaces

PubMed Central

Kumar, Navneet; Sangeetha, D.; Balakrishna, P.

2011-01-01

Background: In pharmaceutical industries, it is very important to remove drug residues from the equipment and areas used. The cleaning procedure must be validated, so special attention must be devoted to the methods used for analysis of trace amounts of drugs. A rapid, sensitive, and specific reverse phase ultra-performance liquid chromatographic (UPLC) method was developed for the quantitative determination of duloxetine in cleaning validation swab samples. Material and Methods: The method was validated using an Acquity UPLC™ HSS T3 (100 × 2.1 mm2) 1.8 μm column with a isocratic mobile phase containing a mixture of 0.01 M potassium dihydrogen orthophosphate, pH adjusted to 3.0 with orthophosphoric acid and acetonitrile (60:40 v/v). The flow rate of the mobile phase was 0.4 ml/min with a column temperature of 40°C and detection wavelength at 230 nm. Cotton swabs, moisten with extraction solution (90% methanol and 10% water), were used to remove any residue of drug from stainless steel, glass and silica surfaces, and give recoveries >80% at four concentration levels. Results: The precision of the results, reported as the relative standard deviation, were below 1.5%. The calibration curve was linear over a concentration range from 0.02 to 5.0 μg/ml with a correlation coefficient of 0.999. The detection limit and quantitation limit were 0.006 and 0.02 μg/ml, respectively. The method was validated over a concentration range of 0.05–5.0 μg/ml. Conclusion: The developed method was validated with respect to specificity, linearity, limit of detection and quantification, accuracy, precision, and robustness. PMID:23781449

Determination of nifedipine in serum of women in preterm labor by high-performance liquid chromatography with diode array detection.

PubMed

Kowalczuk, Dorota; Wawrzycka, Maria Bozena; Haratym Maj, Agnieszka

2006-01-01

Nifedipine (Nif) is widely used in treating cardiovascular disorders (especially hypertension) and for inhibiting preterm labor. A fully validated selective high-performance liquid chromatographic method with diode array detection, using solid-phase extraction, was developed for the determination of Nif in human serum. To assess specificity, Nif and its degradation products were separated on a Purospher RP-18 (5 microm, 125 x 4 mm) column plus a LiChrospher 100 RP-18 (5 microm, 4 x 4 mm) precolumn with a mobile phase of methanol-10 mM aqueous trifluoroacetic acid, pH 7.3 (57 + 43, v/v); chromatographic separation was followed by UV detection at 238 nm. For toxicological analysis, Nif in the presence of other calcium-channel antagonist drugs was identified under optimum chromatographic conditions. The calibration graph was constructed over the concentration range of 12.5-400 ng/mL in serum with good correlation (r = 0.9956). This method was not subject to interference by other plasma components and was successfully applied to the assay of Nif in spiked human serum and in serum of women in preterm labor after sublingual administration of 30 mg Nif per day divided into 3 equal doses. The mean recovery based on the ratio of the slopes of serum and mobile phase standard curves was 96.5%. The detection and quantification limits of the drug in spiked human serum were found to be 6 and 17.5 ng/mL, respectively. Validation of the method demonstrated good intraday and interday precision, which ranged from 2.18 to 6.67% and from 6.52 to 11.93%, respectively.

A rapid method for the simultaneous determination of L-ascorbic acid and acetylsalicylic acid in aspirin C effervescent tablet by ultra performance liquid chromatography-tandem mass spectrometry

NASA Astrophysics Data System (ADS)

Wabaidur, Saikh Mohammad; Alothman, Zeid Abdullah; Khan, Mohammad Rizwan

2013-05-01

In present study, a rapid and sensitive method using ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was developed for the simultaneous determination of L-ascorbic acid and acetylsalicylic acid in aspirin C effervescent tablet. The optimum chromatographic separation was carried out on a reversed phase Waters® Acquity UPLC BEH C18 column (1.7 μm particle size, 100 mm × 2.1 mm ID) with an isocratic elution profile and mobile phase consisting of 0.1% formic acid in water and acetonitrile (75:25, v/v, pH 3.5) at flow rate of 0.5 mL min-1. The influences of mobile phase composition, flow rate and pH on chromatographic resolution were investigated. The total chromatographic analysis time was as short as 2 min with excellent resolution. Detection and quantification of the target compounds were carried out with a triple quadrupole mass spectrometer using negative electrospray ionization (ESI) and multiple reaction monitoring (MRM) modes. The performance of the method was evaluated and very low limits of detection less than 0.09 μg g-1, excellent coefficient correlation (r2 > 0.999) with liner range over a concentration range of 0.1-1.0 μg g-1 for both L-ascorbic acid and acetylsalicylic acid, and good intraday and interday precisions (relative standard deviations (R.S.D.) <3%), were obtained. Comparison of system performance with traditional liquid chromatography-photo diode array detector (HPLC-PDA) was made with respect to analysis time, sensitivity, linearity and precisions. The proposed UPLC-MS/MS method was found to be reproducible and appropriate for quantitative analysis of L-ascorbic acid and acetylsalicylic acid in aspirin C effervescent tablet.

[Determination of 27 industrial dyes in juice and wine using ultra performance liquid chromatography with electrospray ionization tandem quadrupole mass spectrometry].

PubMed

Zhao, Shan; Zhang, Jing; Yang, Yi; Shao, Bing

2010-04-01

A method for the determination of 27 industrial dyes in juice and wine has been developed using ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/ MS). Acetonitrile was used as extraction solvent, and sodium chloride was added to salt out the analytes from the samples. Chromatographic separation was performed on a C18 column with the gradient elution and the mass spectrometric acquisition was carried out under the mode of multiple reaction monitoring (MRM). Twenty-four of the 27 dyes were detected under positive ionization mode using the mobile phase of acetonitrile and water containing 0.1% formic acid. The other 3 dyes were analyzed under negative ionization mode with the mobile phase of acetonitrile and water. As a result, the average recoveries of 27 dyes spiked in juice ranged from 57.0% to 117.7% with the relative standard deviations (RSDs) of 2.4%-17.7%, and the average recoveries of 27 dyes spiked in wine ranged from 40.8% to 109.4% with the RSDs of 1.6%-17.9%. The limits of quantification (LOQs) of 27 dyes spiked in juice were in the range of 0.1-50 microg/kg, and 0.2-50 microg/kg for those spiked in wine. This method can be applied to rapid detection of illegally added dyes in soft drinks due to its simplicity and high sensitivity.

Carbon nanotubes@silicon dioxide nanohybrids coating for solid-phase microextraction of organophosphorus pesticides followed by gas chromatography-corona discharge ion mobility spectrometric detection.

PubMed

Saraji, Mohammad; Jafari, Mohammad Taghi; Mossaddegh, Mehdi

2016-01-15

A high efficiency solid-phase microextraction (SPME) fiber coated with porous carbon nanotubes-silicon dioxide (CNTs-SiO2) nanohybrids was synthesized and applied for the determination of some organophosphorus pesticides (OPPs) in vegetables, fruits and water samples. Gas chromatography-corona discharge ion mobility spectrometry was used as the detection system. Glucose, as a biocompatible compound, was used for connecting CNT and SiO2 during a hydrothermal process. The electrospinning technique was also applied for the fiber preparation. The parameters affecting the efficiency of extraction, including stirring rate, salt effect, extraction temperature, extraction time, desorption temperature and desorption time, were investigated and optimized. The developed CNTs@SiO2 fiber presented better extraction efficiency than the commercial SPME fibers (PA, PDMS, and PDMS-DVB). The intra- and inter-day relative standard deviations were found to be lower than 6.2 and 9.0%, respectively. For water samples, the limits of detection were in the range of 0.005-0.020 μg L(-1) and the limits of quantification were between 0.010 and 0.050 μg L(-1). The results showed a good linearity in the range of 0.01-3.0 μg L(-1) for the analytes. The spiking recoveries ranged from 79 (± 9) to 99 (± 8). The method was successfully applied for the determination of OPPs in real samples. Copyright © 2015 Elsevier B.V. All rights reserved.

Rapid and sensitive determination of benzo[a]pyrene in black ginseng using fluorescence detector and high performance liquid chromatography-tandem mass spectrometry

NASA Astrophysics Data System (ADS)

Cho, Hyun-jeong; Kim, Hye-jin; Son, Byeong-cheol; Jo, Dong-keun; Cho, Byung-lim

2013-05-01

Black ginseng is produced by steaming a ginseng root followed by drying repeatedly 9 times during the process and it is changed to be black color, so it is known that a black ginseng has more contents of saponins than red ginseng. However a fake black ginseng which is produced to be black color at high temperature in a short period of time generate carcinogenic benzo[a]pyrene(BaP) through the process. In this year, maximum residue level(MRL) for BaP was established to 2 ug/kg in black ginseng and more sensitive method was developed to quantitatively analyze the BaP by high performance liquid chromatography (HPLC) coupling with florescence detector and tandem mass spectrometry (atmospheric pressure chemical ionization-MS/MS). Chromatographic separation was performed on a Supelcosil™ LC-PAH column (3 μm, 3 mm x 50 mm). Mobile phase A was water and mobile phase B was acetonitrile. BaP was exactly separated from other 15 polycyclic aromatic hydrocarbons (PAHs) which have been selected as priority pollutants by the US Environmental Protection Agency (EPA). Linearity of detection was in the range of 0.2~20 μg/kg and limit of detection (LOD) for BaP was lower than 0.1 μg/kg, limit of quantification (LOQ) was 0.2 μg/kg. The recovery of Bap was 92.54%+/-6.3% in black ginseng.

Determination of ambroxol in human plasma by high performance liquid chromatography-electrospray ionization mass spectrometry (HPLC-MS/ESI).

PubMed

Su, Fenli; Wang, Feng; Gao, Wei; Li, Huande

2007-06-15

A rapid, sensitive and specific method to determination of ambroxol in human plasma using high performance liquid chromatography coupled with electrospray ionization mass spectrometry (HPLC-MS/ESI) was described. Ambroxol and the internal standard (I.S.), fentanyl, were extracted from plasma by N-hexane-diethyl ether (1:1, v/v) after alkalinized with ammonia water. A centrifuged upper layer was then evaporated and reconstituted with 100 microl mobile phase. Chromatographic separation was performed on a BDS HYPERSIL C18 column (250 mmx4.6 mm, 5.0 microm, Thermo electron corporation, USA) with the mobile phase consisting of 30 mM ammonium acetate (0.4% formic acid)-acetonitrile (64:36, v/v) at a flow-rate of 1.2 mL min(-1). The total run time was 5.8 min for each sample. Detection and quantitation was performed by the mass spectrometer using selected ion monitoring at m/z 261.9, 263.8 and 265.9 for ambroxol and m/z 337.3 for fentanyl. The calibration curve was linear within the concentration range of 1.0-100.0 ng mL(-1) (r=0.9996). The limit of quantification was 1.0 ng mL(-1). The extraction recovery was above 83.3%. The methodology recovery was higher than 93.8%. The intra- and inter-day precisions were less than 6.0%. The method is accurate, sensitive and simple for the study of the pharmacokinetics and metabolism of ambroxol.

Microfluidic Investigation of Oil Mobilization in Shale Fracture Networks at Reservoir Conditions

NASA Astrophysics Data System (ADS)

Porter, M. L.; Jimenez-Martinez, J.; Carey, J. W.; Viswanathan, H. S.

2015-12-01

Investigations of pore-scale fluid flow and transport phenomena using engineered micromodels has steadily increased in recent years. In these investigations fluid flow is restricted to two-dimensions allowing for real time visualization and quantification of complex flow and reactive transport behavior, which is difficult to obtain in other experimental systems. One drawback to these studies is the use of engineered materials that do not faithfully represent the rock properties (e.g., porosity, wettability, roughness, etc.) encountered in subsurface formations. In this work, we describe a unique high pressure (up to 1500 psi) and temperature (up to 80 °C) microfluidics experimental system in which we investigate fluid flow and transport in geo-material (e.g., shale, Portland cement, etc.) micromodels. The use of geo-material micromodels allows us to better represent fluid-rock interactions including wettability, chemical reactivity, and nano-scale porosity at conditions representative of natural subsurface environments. Here, we present experimental results in fracture systems with applications to hydrocarbon mobility in hydraulically fractured shale. Complex fracture network patterns are derived from 3D x-ray tomography images of actual fractures created in shale rock cores. We use both shale and glass micromodels, allowing for a detailed comparison between flow phenomena in the different materials. We discuss results from two-phase huff-and-puff experiments involving N2 and n-Decane, as well as three-phase displacement experiments involving supercritical CO2, brine, and n-Decane.

Development and validation of a high performance liquid chromatographic method for the separation of exo and endo isomers of granatamine (9-methyl-9-azabicyclo[3.3.1]nonan-3-amine); a key intermediate of granisetron.

PubMed

Krishna, S Radha; Babu, P Suresh; Rao, B M; Rao, N Someswara

2009-12-01

A simple and accurate high-performance liquid chromatographic method was developed for the determination of exo-9-methyl-9-azabicyclo[3.3.1]nonan-3-amine in endo-9-methyl-9-azabicyclo[3.3.1]nonan-3-amine, commercially known as grantamine and used as a key intermediate in the preparation of granisetron bulk drug. Chromatographic separation of the exo and endo isomers of 9-methyl-9-azabicyclo[3.3.1]nonan-3-amine was achieved on an Inertsil C8 column using a mobile phase containing 0.3% trifluoroacetic acid. The resolution between the two isomers was found to be more than 4. The limit of detection (LOD) and limit of quantification (LOQ) of exo isomer were 0.8 and 2.5 microg x mL(-1) respectively, for a 10 microL injection volume. The percentage recovery of exo-isomer ranged from 99 to 102% w/w in the endo-9-methyl-9-azabicyclo[3.3.1]nonan-3-amine sample. The test solution and mobile phase were observed to be stable up to 48 h after preparation. The validated method yielded good results for precision, linearity, accuracy, robustness and ruggedness. The proposed method was found to be suitable and accurate for the quantitative determination of exo-isomer in bulk samples of endo-9-methyl-9-azabicyclo[3.3.1]nonan-3-amine.

Quantification of Paclitaxel and Polyaspartate Paclitaxel Conjugate in Beagle Plasma: Application to a Pharmacokinetic Study.

PubMed

Gao, Yangyang; Chen, Junying; Zhang, Xiqian; Xie, Huiru; Wang, Yanran; Guo, Shuquan

2017-03-01

An LC-MS/MS method for the determination of polyaspartate paclitaxel conjugate (PASP-PTX) and paclitaxel (PTX) in dog plasma with cephalomannine (Internal Standard for PASP-PTX, IS-I) and clopidogrel bisulfate (Internal Standard for PTX, IS-II) as the internal standards was developed and validated. Plasma samples of PASP-PTX were extracted by ethyl acetate following the hydrolysis reaction, while protein precipitation was used for the extraction of PTX using acetonitrile. Analytes were separated by a CAPCELL PAK C18 MG II column using a gradient elution with the mobile phase (A) 5 mM ammonium containing 0.1% formic acid, and (B) acetonitrile. Quantification was performed by monitoring the m/z transitions of 286.2/105.0 for PASP-PTX, 264.2/83.0 for IS-I, 854.4/286.0 for PTX, and 322.1/184.1 for IS-II in the ESI positive mode. This method was validated in terms of specificity, linearity, precision, accuracy, and stability. The lower limit of quantification was 0.15 µg/mL for PASP-PTX and 0.01 µg/mL for PTX, and the calibration curves were linear over 0.15-300 µg/mL for PASP-PTX and over 0.01-10 µg/mL for PTX. The samples were stable under all the tested conditions. The method was successfully applied to study the pharmacokinetic profiles of PASP-PTX and PTX in beagles following intravenous administration of PASP-PTX. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Simultaneous quantification of the major bile acids in artificial Calculus bovis by high-performance liquid chromatography with precolumn derivatization and its application in quality control.

PubMed

Shi, Yan; Xiong, Jing; Sun, Dongmei; Liu, Wei; Wei, Feng; Ma, Shuangcheng; Lin, Ruichao

2015-08-01

An accurate and sensitive high-performance liquid chromatography method coupled with ultralviolet detection and precolumn derivatization was developed for the simultaneous quantification of the major bile acids in Artificial Calculus bovis, including cholic acid, hyodeoxycholic acid, chenodeoxycholic acid, and deoxycholic acid. The extraction, derivatization, chromatographic separation, and detection parameters were fully optimized. The samples were extracted with methanol by ultrasonic extraction. Then, 2-bromine-4'-nitroacetophenone and 18-crown ether-6 were used for derivatization. The chromatographic separation was performed on an Agilent SB-C18 column (250 × 4.6 mm id, 5 μm) at a column temperature of 30°C and liquid flow rate of 1.0 mL/min using water and methanol as the mobile phase with a gradient elution. The detection wavelength was 263 nm. The method was extensively validated by evaluating the linearity (r(2) ≥ 0.9980), recovery (94.24-98.91%), limits of detection (0.25-0.31 ng) and limits of quantification (0.83-1.02 ng). Seventeen samples were analyzed using the developed and validated method. Then, the amounts of bile acids were analyzed by hierarchical agglomerative clustering analysis and principal component analysis. The results of the chemometric analysis showed that the contents of these compounds reflect the intrinsic quality of artificial Calculus bovis, and two compounds (hyodeoxycholic acid and chenodeoxycholic acid) were the most important markers for quality evaluating. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A convenient ultrasound-assisted saponification for the simultaneous determination of vitamin E isomers in vegetable oil by HPLC with fluorescence detection.

PubMed

Yang, Yi; Lu, Dan; Yin, Shuo; Yang, Danni; Chen, Yaling; Li, Yongxin; Sun, Chengjun

2018-04-01

An efficient ultrasound-assisted saponification was developed for simultaneous determination of vitamin E isomers in vegetable oil by high-performance liquid chromatography with fluorescence detection. The samples were saponified ultrasonically with potassium hydroxide solution for only 7 min, then the analytes were extracted with ether. Vitamin E isomers were separated on a C 18 column at 25°C with a mobile phase of methanol/acetonitrile (81:19, v/v) at a flow rate of 0.8 mL/min. Fluorescence detection was operated at 290 nm of excitation wavelength and 327 nm of emission wavelength. Under the optimized conditions, good linearities over the range of 0.001-8.00 μg/mL (r > 0.999) were obtained. Mean recoveries of the method were 88.0-106%, with intra- and interday RSDs less than 11.8 and 12.8%, respectively. The detection limits and quantification limits of the method were 0.30-1.8 and 1.0-6.1 μg/kg, respectively. The recoveries of this method were much higher than that of the quick, easy, cheap, effective, rugged, and safe method and direct dilution method, but were similar to those of hot saponification. This proposed method provides reliable, simple, and rapid quantification of vitamin E isomers in vegetable oils. Five kinds of vegetable oils were analyzed, the quantification results were within the ranges reported by other authors. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Liquid chromatography-mass spectrometry-based quantification of steroidal glycoalkaloids from Solanum xanthocarpum and effect of different extraction methods on their content.

PubMed

Paul, Atish T; Vir, Sanjay; Bhutani, K K

2008-10-24

A new liquid chromatography-mass spectrometry (LC-MS)-based method coupled with pressurized liquid extraction (PLE) as an efficient sample preparation technique has been developed for the quantification and fingerprint analysis of Solanum xanthocarpum. Optimum separations of the samples were achieved on a Waters MSC-18 XTerra column, using 0.5% (v/v) formic acid in water (A) and acetonitrile (ACN):2-propanol:formic acid (94.5:5:0.5, v/v/v) (B) as mobile phase. The separation was carried out using linear gradient elution with a flow rate of 1.0mL/min. The gradient was: 0min, 20% B; 14min, 30% B; 20min, 30% B; 27min, 60% B and the column was re-equilibrated to the initial condition (20% B) for 10min prior to next injection. The steroidal glycoalkaloids (SGAs) which are the major active constituents were isolated as pure compounds from the crude methanolic extract of S. xanthocarpum by preparative LC-MS and after characterization were used as external standards for the development and validation of the method. Extracts prepared by conventional Soxhlet extraction, PLE and ultrasonication were used for analysis. The method was validated for repeatability, precision (intra- and inter-day variation), accuracy (recovery) and sensitivity (limit of detection and limit of quantitation). The purpose of the work was to develop a validated method, which can be used for the quantification of SGAs in commercialized S. xanthocarpum products and the fingerprint analysis for their routine quality control.

Modification and validation of a high-performance liquid chromatography method for quantification of Huperzine A in Huperzia crispata.

PubMed

Yu, Lijun; Shi, Yunfeng; Huang, Jianan; Gong, Yushun; Liu, Zhonghua; Hu, Weixin

2010-01-01

The present study describes a rapid and sensitive HPLC method for the quantification of huperzine A (HupA) in Huperzia crispata (Huperziaceae). The sample extraction and preparation involved a simple, time-saving, single-solvent extraction, with each sample being analyzed within 12 min. The mobile phase was ammonium acetate (0.1 M, pH 6.0)--methanol (64 + 36, v/v) at a flow rate of 1.0 mL/min. Detection was at 308 nm. The calibration curve was linear from 0.049 to 7.84 microg (R2 = 0.9997), with intraday and interday precision RSD of less than 2%. The extraction recovery rate was over 98.49%. Quantification of HupA was performed using this modified method, and the content of HupA was 1.86 times higher in the whole plant of H. crispata (218.17 +/- 1.55 microg/g) than in that of H. serrata (117.03 +/- 2.97 microg/g). In the whole plant of H. crispata, HupA mainly accumulated in the actively growing shoot tips, the apical bud, and the 10 youngest leaves, reaching 455.23 +/- 2.97 microg/g. The content of HupA in the samples from sunshine-sheltered sites was 3.45 times higher than in that from sunshine-abundant sites. The satisfactory results indicate that this modified method can be applied in the quality control of large-scale Huperziaceae plant extracts and that changes should be made in the cultivation of H. crispata so as to maximize the production of HupA.

Quantification of 15 bile acids in lake charr feces by ultra-high performance liquid chromatography–tandem mass spectrometry

USGS Publications Warehouse

Li, Ke; Buchinger, Tyler J.; Bussy, Ugo; Fissette, Skye D.; Johnson, Nicholas; Li, Weiming

2015-01-01

Many fishes are hypothesized to use bile acids (BAs) as chemical cues, yet quantification of BAs in biological samples and the required methods remain limited. Here, we present an UHPLC–MS/MS method for simultaneous, sensitive, and rapid quantification of 15 BAs, including free, taurine, and glycine conjugated BAs, and application of the method to fecal samples from lake charr (Salvelinus namaycush). The analytes were separated on a C18 column with acetonitrile–water (containing 7.5 mM ammonium acetate and 0.1% formic acid) as mobile phase at a flow rate of 0.25 mL/min for 12 min. BAs were monitored with a negative electrospray triple quadrupole mass spectrometer (Xevo TQ-S™). Calibration curves of 15 BAs were linear over the concentration range of 1.00–5,000 ng/mL. Validation revealed that the method was specific, accurate, and precise. The method was applied to quantitative analysis of feces extract of fry lake charr and the food they were eating. The concentrations of analytes CA, TCDCA, TCA, and CDCA were 242.3, 81.2, 60.7, and 36.2 ng/mg, respectively. However, other taurine conjugated BAs, TUDCA, TDCA, and THDCA, were not detected in feces of lake charr. Interestingly, TCA and TCDCA were detected at high concentrations in food pellets, at 71.9 and 38.2 ng/mg, respectively. Application of the method to feces samples from lake charr supported a role of BAs as chemical cues, and will enhance further investigation of BAs as chemical cues in other fish species.

A simple, rapid and sensitive RP-HPLC-UV method for the simultaneous determination of sorafenib & paclitaxel in plasma and pharmaceutical dosage forms: Application to pharmacokinetic study.

PubMed

Khan, Ismail; Iqbal, Zafar; Khan, Abad; Hassan, Muhammad; Nasir, Fazle; Raza, Abida; Ahmad, Lateef; Khan, Amjad; Akhlaq Mughal, Muhammad

2016-10-15

A simple, economical, fast, and sensitive RP-HPLC-UV method has been developed for the simultaneous quantification of Sorafenib and paclitaxel in biological samples and formulations using piroxicam as an internal standard. The experimental conditions were optimized and method was validated according to the standard guidelines. The separation of both the analytes and internal standard was achieved on Discovery HS C18 column (250mm×4.6mm, 5μm) using Acetonitrile and TFA (0.025%) in the ratio of (65:35V/V) as the mobile phase in isocratic mode at a flow rate of 1ml/min, with a wavelength of 245nm and at a column oven temperature of 25°Cin a short run time of 12min. The limits of detection (LLOD) were 5 and 10ng/ml while the limits of quantification (LLOQ) were 10 and 15ng/ml for sorafenib and paclitaxel, respectively. Sorafenib, paclitaxel and piroxicam (IS) were extracted from biological samples by applying acetonitrile as a precipitating and extraction solvent. The method is linear in the range of 15-20,000ng/ml for paclitaxel and 10-5000ng/ml for sorafenib, respectively. The method is sensitive and reliable by considering both of its intra-day and inter-day co-efficient of variance. The method was successfully applied for the quantification of the above mentioned drugs in plasma. The developed method will be applied towards sorafenib and paclitaxel pharmacokinetics studies in animal models. Copyright © 2016 Elsevier B.V. All rights reserved.

Midcarpal instability: a diagnostic role for dynamic ultrasound?

PubMed

Toms, A; Chojnowski, A; Cahir, J

2009-06-01

The aim of this study was to describe the technique of dynamic ultrasound (US) examination of the triquetral clunk, and to illustrate the range of findings in four patients with midcarpal instability (MCI). Four patients were identified (3 men, 1 woman). The case notes, plain radiographs, MRI and dynamic US for each patient were reviewed. Digital video files recording the dynamic US of the triquetral clunks were analysed for the following features of abnormal triquetral mobility: direction and speed of triquetral snap, amount of anteroposterior translocation, and flexion or extension during the snap. Five different triquetral clunks were recorded in 4 patients. In four out of five cases the clunk occurred during ulnar translocation of the wrist, and in one during radial translocation. Anteroposterior translocation was anterior (3.4 - 4.7 mm) in three of the clunks and posterior (1 - 10 mm) in two. The degree of flexion or extension varied between 1 and 16 degrees . The snapping phase of the clunk lasted between 0.17 and 0.25 seconds. Dynamic US can be used to confirm the diagnosis of midcarpal instability by identifying a triquetral catch-up clunk. Quantification of carpal mobility with US may lead to further insights into the mechanics of MCI.

Simultaneous Determination of Withanolide A and Bacoside A in Spansules by High-Performance Thin-Layer Chromatography

PubMed Central

Shinde, P B; Aragade, P D; Agrawal, M R; Deokate, U A; Khadabadi, S S

2011-01-01

The objective of this work was to develop and validate a simple, rapid, precise, and accurate high performance thin layer chromatography method for simultaneous determination of withanolide A and bacoside A in combined dosage form. The stationary phase used was silica gel G60F254. The mobile phase used was mixture of ethyl acetate: methanol: toluene: water (4:1:1:0.5 v/v/v/v). The detection of spots was carried out at 320 nm using absorbance reflectance mode. The method was validated in terms of linearity, accuracy, precision and specificity. The calibration curve was found to be linear between 200 to 800 ng/spot for withanolide A and 50 to 350 ng/spot for bacoside A. The limit of detection and limit of quantification for the withanolide A were found to be 3.05 and 10.06 ng/spot, respectively and for bacoside A 8.3 and 27.39 ng/spot, respectively. The proposed method can be successfully used to determine the drug content of marketed formulation. PMID:22303073

Simultaneous determination of withanolide a and bacoside a in spansules by high-performance thin-layer chromatography.

PubMed

Shinde, P B; Aragade, P D; Agrawal, M R; Deokate, U A; Khadabadi, S S

2011-03-01

The objective of this work was to develop and validate a simple, rapid, precise, and accurate high performance thin layer chromatography method for simultaneous determination of withanolide A and bacoside A in combined dosage form. The stationary phase used was silica gel G60F(254). The mobile phase used was mixture of ethyl acetate: methanol: toluene: water (4:1:1:0.5 v/v/v/v). The detection of spots was carried out at 320 nm using absorbance reflectance mode. The method was validated in terms of linearity, accuracy, precision and specificity. The calibration curve was found to be linear between 200 to 800 ng/spot for withanolide A and 50 to 350 ng/spot for bacoside A. The limit of detection and limit of quantification for the withanolide A were found to be 3.05 and 10.06 ng/spot, respectively and for bacoside A 8.3 and 27.39 ng/spot, respectively. The proposed method can be successfully used to determine the drug content of marketed formulation.

Preliminary investigation on the occurrence of several sulfonamide antibiotics in the Haihe River Basin of China

NASA Astrophysics Data System (ADS)

Zhang, S. L.; Zhang, J.; Wang, Z. G.; Wang, Y. Z.; Liang, S. T.; Liu, C.; Wang, Z.

2017-08-01

Several samples collected from lakes, rivers and reservoirs in Haihe river basin of China were analyzed for 8 sulfonamide antibiotics by using solid-phase extraction and liquid chromatography with tandem mass spectrometry (HPLC-MS/MS). All water samples were enriched with HLB extraction cartridges. The antibiotics were separated by gradient elution with methanol as the mobile phase adding 0.1% formic acid. The eluate was then analyzed by the mode of multiple reaction monitoring (MRM). The limits of detection (LOD) and quantification (LOQ) were 0.4-1.0 ng/L and 1.0-3.0 ng/L respectively. The method was used for the analysis of 13 samples from Haihe river basin in China. The results showed that sulfamethoxazole was present in all water samples with maximum concentration of 107.59 ng/L. Sulfadiazine was also frequently detected, concentrations ranging from 2.81 ng/L to 85.35 ng/L. Other sulfonamide antibiotics were not detected in most water samples, especially for those samples from drinking water resources.

A validated stability-indicating UPLC method for desloratadine and its impurities in pharmaceutical dosage forms.

PubMed

Rao, Dantu Durga; Satyanarayana, N V; Malleswara Reddy, A; Sait, Shakil S; Chakole, Dinesh; Mukkanti, K

2010-02-05

A novel stability-indicating gradient reverse phase ultra-performance liquid chromatographic (RP-UPLC) method was developed for the determination of purity of desloratadine in presence of its impurities and forced degradation products. The method was developed using Waters Aquity BEH C18 column with mobile phase containing a gradient mixture of solvents A and B. The eluted compounds were monitored at 280nm. The run time was 8min within which desloratadine and its five impurities were well separated. Desloratadine was subjected to the stress conditions of oxidative, acid, base, hydrolytic, thermal and photolytic degradation. Desloratadine was found to degrade significantly in oxidative and thermal stress conditions and stable in acid, base, hydrolytic and photolytic degradation conditions. The degradation products were well resolved from main peak and its impurities, thus proved the stability-indicating power of the method. The developed method was validated as per ICH guidelines with respect to specificity, linearity, limit of detection, limit of quantification, accuracy, precision and robustness. This method was also suitable for the assay determination of desloratadine in pharmaceutical dosage forms.

[Determination of dimethyl fumarate in bakery food by d-SPE-HPLC-PDA].

PubMed

Yang, Jie; Luo, Mengtian; Feng, Di; Miao, Hong; Song, Shufeng; Zhao, Yunfeng

2015-05-01

To establish a simple and rapid pretreatment method with dispersive solid phase extraction ( d-SPE) by HPLC for determination of dimethyl fumarate in bakery foods. Dimethyl fumarate in samples was ultrasonically extracted by methanol, and cleaned up with d-SPE. Then, it was separated on C18 chromatographic column (4.6 mm x 25 mm, 5 μm) with a mixture of methanol--0.03 mol/L sodium acetate and 0.008 mol/L tetrabutyl ammonium bromide (40: 60, V/V) as mobile phase. The photodiode array detector was used in the determination under λ = 220 nm. In the linear range of 0.1 -25 μg/ml, the correlation coefficients was r > 0.999, and the average recoveries of the spiked samples were in the range of 82.8% - 107.5% with relative standard deviations (RSD) in the range of 3.30% - 7.30% (n = 6). The limit of detection ( LOD) was 0.4 mg/kg, and the limit of quantification was 1.0 mg/kg. The method is simple, rapid, sensitive and accurate, and suitable for determine dimethyl fumarate in bakery foods.

Rapid determination of protopine, allocryptopine, sanguinarine and chelerythrine in fruits of Macleaya cordata by microwave-assisted solvent extraction and HPLC-ESI/MS.

PubMed

Luo, Xu-Biao; Chen, Bo; Yao, Shou-Zhuo

2006-01-01

An isocratic high-performance liquid chromatographic method coupled with electrospray mass spectrometry was developed to determine protopine, allocryptopine, sanguinarine and chelerythrine in fruits of Macleaya cordata. The sample was extracted with hydrochloric acid aqueous solution using microwave-assisted extraction method. The extracts were separated on a C8 reversed-phase HPLC column with acetonitrile:acetate buffer as mobile phase, and full elution of all analytes was realized isocratically within 10 min. The abundance of pseudomolecule ions was recorded using selected ion recording at m/z 354.4, 370.1, 332.5, 348.5 and 338.5 for protopine, allocryptopine, sanguinarine, chelerythrine and the internal standard, jatrorrhizine, respectively. Internal standard curves were used for the quantification of protopine, allocryptopine, sanguinarine and chelerythrine, which showed a linear range of 0.745-74.5, 0.610-61.0, 0.525-105 and 0.375-75 microg/mL, respectively, with correlation coefficients of 0.9995, 0.9992, 0.9993 and 0.9989, and limits of detection of 3.73, 3.05, 1.60 and 1.11 ng/mL, respectively.

Development and validation of an LC-UV method for the determination of sulfonamides in animal feeds.

PubMed

Kumar, P; Companyó, R

2012-05-01

A simple LC-UV method was developed for the determination of residues of eight sulfonamides (sulfachloropyridazine, sulfadiazine, sulfadimidine, sulfadoxine, sulfamethoxypyridazine, sulfaquinoxaline, sulfamethoxazole, and sulfadimethoxine) in six types of animal feed. C18, Oasis HLB, Plexa and Plexa PCX stationary phases were assessed for the clean-up step and the latter was chosen as it showed greater efficiency in the clean-up of interferences. Feed samples spiked with sulfonamides at 2 mg/kg were used to assess the trueness (recovery %) and precision of the method. Mean recovery values ranged from 47% to 66%, intra-day precision (RSD %) from 4% to 15% and inter-day precision (RSD %) from 7% to 18% in pig feed. Recoveries and intra-day precisions were also evaluated in rabbit, hen, cow, chicken and piglet feed matrices. Calibration curves with standards prepared in mobile phase and matrix-matched calibration curves were compared and the matrix effects were ascertained. The limits of detection and quantification in the feeds ranged from 74 to 265 µg/kg and from 265 to 868 µg/kg, respectively. Copyright © 2011 John Wiley & Sons, Ltd.

Analysis of abamectin residues in avocados by high-performance liquid chromatography with fluorescence detection.

PubMed

Hernández-Borges, Javier; Ravelo-Pérez, Lidia M; Hernández-Suárez, Estrella M; Carnero, Aurelio; Rodríguez-Delgado, Miguel Angel

2007-09-21

In this work an analytical method for the determination of abamectin residues in avocados is developed using high-performance liquid chromatography (HPLC) with fluorescence (FL) detection. A pre-column derivatization with trifluoroacetic anhydride (TFAA) and N-methylimidazole (NMIM) was carried out. The mobile phase consisted of water, methanol and acetonitrile (5:47.5:47.5 v/v/v) and was pumped at a rate of 1 mL/min (isocratic elution). The fluorescence detector was set at an excitation wavelength of 365 nm and an emission wavelength of 470 nm. Homogenized avocado samples were extracted twice with acetonitrile:water 8:2 (v/v) and cleaned using C(18) solid-phase extraction (SPE) cartridges. Recovery values were in the range 87-98% with RSD values lower than 13%. The limits of detection (LODs) and quantification (LOQs) of the whole method were 0.001 and 0.003 mg/kg, respectively. These values are lower than the maximum residue limit (MRL) established by the European Union (EU) and the Spanish legislation in avocado samples.

Rapid tea catechins and caffeine determination by HPLC using microwave-assisted extraction and silica monolithic column.

PubMed

Rahim, A A; Nofrizal, S; Saad, Bahruddin

2014-03-15

A rapid reversed-phase high performance liquid chromatographic method using a monolithic column for the determination of eight catechin monomers and caffeine was developed. Using a mobile phase of water:acetonitrile:methanol (83:6:11) at a flow rate of 1.4 mL min(-1), the catechins and caffeine were isocratically separated in about 7 min. The limits of detection and quantification were in the range of 0.11-0.29 and 0.33-0.87 mg L(-1), respectively. Satisfactory recoveries were obtained (94.2-105.2 ± 1.8%) for all samples when spiked at three concentrations (5, 40 and 70 mg L(-1)). In combination with microwave-assisted extraction (MAE), the method was applied to the determination of the catechins and caffeine in eleven tea samples (6 green, 3 black and 2 oolong teas). Relatively high levels of caffeine were found in black tea, but higher levels of the catechins, especially epigallocatechin gallate (EGCG) were found in green teas. Copyright © 2013 Elsevier Ltd. All rights reserved.

Simultaneous quantification of polymethoxylated flavones and coumarins in Fructus aurantii and Fructus aurantii immaturus using HPLC-ESI-MS/MS.

PubMed

Chen, Hai-Fang; Zhang, Wu-Gang; Yuan, Jin-Bin; Li, Yan-Gang; Yang, Shi-Lin; Yang, Wu-Liang

2012-02-05

The major lipid-soluble constituents in Fructus aurantii (zhiqiao) and Fructus aurantii immaturus (zhishi) are polymethoxylated flavones (PMFs) and coumarins. In the present study, a high-performance liquid chromatography with electrospray ionization tandem mass spectrometry method was developed to quantify PMFs (nobiletin, tangeretin, 5-hydroxy-6,7,8,4'-tetramethoxyflavone, and natsudaidai) and coumarins (marmin, meranzin hydrate, and auraptene) simultaneously. PMFs and coumarins were detected by electrospray ionization tandem mass spectrometry in positive ion mode and quantified with multiple reaction monitor. Samples were separated on a Diamonsil C₁₈ (150 mm × 4.6 mm, 5 μm) column using acetonitrile and formic acid-water solution as a mobile phase in gradient mode with a flow rate at 0.5 mL/min. All calibration curves showed good linearity (r² > 0.9977) within the test ranges. Variations of the intraday and interday precisions were less than 4.07%. The recoveries of the components were within the range of 95.79%-105.04% and the relative standard deviations were less than 3.82%. The method developed was validated with acceptable accuracy, precision, and extraction recoveries and can be applied for the identification and quantification of four PMFs and three coumarins in citrus herbs. Copyright © 2011 Elsevier B.V. All rights reserved.

Simultaneous quantification of multiple components in rat plasma by UPLC-MS/MS and pharmacokinetic study after oral administration of Huangqi decoction.

PubMed

Zeng, Jia-Kai; Li, Yuan-Yuan; Wang, Tian-Ming; Zhong, Jie; Wu, Jia-Sheng; Liu, Ping; Zhang, Hua; Ma, Yue-Ming

2018-05-01

A rapid, sensitive and accurate UPLC-MS/MS method was developed for the simultaneous quantification of components of Huangqi decoction (HQD), such as calycosin-7-O-β-d-glucoside, calycosin-glucuronide, liquiritin, formononetin-glucuronide, isoliquiritin, liquiritigenin, ononin, calycosin, isoliquiritigenin, formononetin, glycyrrhizic acid, astragaloside IV, cycloastragenol, and glycyrrhetinic acid, in rat plasma. After plasma samples were extracted by protein precipitation, chromatographic separation was performed with a C 18 column, using a gradient of methanol and 0.05% acetic acid containing 4mm ammonium acetate as the mobile phase. Multiple reaction monitoring scanning was performed to quantify the analytes, and the electrospray ion source polarity was switched between positive and negative modes in a single run of 10 min. Method validation showed that specificity, linearity, accuracy, precision, extraction recovery, matrix effect and stability for 14 components met the requirements for their quantitation in biological samples. The established method was successfully applied to the pharmacokinetic study of multiple components in rats after intragastric administration of HQD. The results clarified the pharmacokinetic characteristics of multiple components found in HQD. This research provides useful information for understanding the relation between the chemical components of HQD and their therapeutic effects. Copyright © 2017 John Wiley & Sons, Ltd.

A sensitive LC-MS/MS method for the quantification of febuxostat in human plasma and its pharmacokinetic application.

PubMed

Vaka, Venkata Rami Reddy; Inamadugu, Jaswanth Kumar; Pilli, Nageswara Rao; Ramesh, Mullangi; Katreddi, Hussain Reddy

2013-11-01

An improved, simple and highly sensitive LC-MS/MS method has been developed and validated for quantification of febuxostat with 100 μL human plasma using febuxostat-d7 as an internal standard (IS) according to regulatory guidelines. The analyte and IS were extracted from human plasma via liquid-liquid extraction using diethyl ether. The chromatographic separation was achieved on a Zorbax C18 column using a mixture of acetonitrile and 5 mm ammonium formate (60:40, v/v) as the mobile phase at a flow rate of 0.5 mL/min. The total run time was 5.0 min and the elution of febuxostat and IS occurred at 1.0 and 1.5 min, respectively. A linear response function was established for the range of concentrations 1-6000 ng/mL (r > 0.99). The precursor to product ion transitions monitored for febuxostat and IS were m/z 317.1 → 261.1 and 324.2 → 262.1, respectively. The intra- and inter-day precisions (%RSD) were within 1.29-9.19 and 2.85-7.69%, respectively. The proposed method was successfully applied to pharmacokinetic studies in humans. Copyright © 2013 John Wiley & Sons, Ltd.

Development of a LC-MS method for simultaneous determination of amoxicillin and metronidazole in human serum using hydrophilic interaction chromatography (HILIC).

PubMed

Kathriarachchi, Udani L; Vidhate, Sagar S; Al-Tannak, Naser; Thomson, Alison H; da Silva Neto, Michael J J; Watson, David G

2018-07-01

A method was developed for the determination of amoxicillin and metronidazole in human serum. The procedure used was hydrophilic interaction chromatography (HILIC) followed by mass spectrometric (MS) detection. Chromatographic separation was achieved on a ZIC-HILIC column and the mobile phase consisted of a mixture of 0.1% (v/v) formic acid in water and 0.1% (v/v) formic acid in acetonitrile. The method was validated with regard to selectivity, accuracy, precision, calibration, lower limit of quantification (LOQ), extraction recovery and matrix effect. The LOQs were 0.0138 and 0.008 μg/ml for amoxicillin and metronidazole respectively, while for quantification purposes linearity was achieved in the range of 0.1 μg/ml to 6.4 μg/ml for both drugs with correlation coefficients >0.9990. The intraday precision (expressed as %RSD) and the accuracy (expressed as the % deviation from the nominal value) was <15% for both antibiotics at all QC levels. Extraction recoveries for both drugs and internal standards were >80%, while a considerable matrix effect (<60%) was observed for amoxicillin. Finally, the method was applied to the determination of amoxicillin and metronidazole concentrations in serum for 20 patients. Copyright © 2018 Elsevier B.V. All rights reserved.

Stability-Indicating TLC-Densitometric Assay for Methyltestosterone and Quantum Chemical Calculations.

PubMed

Musharraf, Syed Ghulam; Ul Arfeen, Qamar; Ul Haq, Faraz; Khatoon, Aliya; Azher Ali, Rahat

2017-10-01

Methyltestosterone is a synthetic testosterone derivative commonly used for the treatment of testosterone deficiency in males and one the anabolic steroids whose use is banned by World Anti-Doping Agency (WADA). This study presents a simple, cost-effective and rapid stability-indicating assay for densitometric quantification of methyltestosterone in pharmaceutical formulation. The developed method employed pre-coated TLC plates with mobile phase hexane:acetone (6.5:3.5 v/v). Limit of detection and limit of quantitation were found to be 2.06 and 6.24 ng/spot, respectively. Stress degradation study of methyltestosterone was conducted by applying various stress conditions such as hydrolysis under acidic, basic and neutral conditions, heating in anhydrous conditions and exposure to light. Methyltestosterone was found to be susceptible to photodegradation, acidic and basic hydrolysis. Degraded products were well resolved with significantly different Rf values. Acid degraded product was identified as 17,17-dimethyl-18-norandrosta-4,13(14)-dien-3-one through spectroscopic methods. The reactivity of methyltestosterone under applied stress conditions was also explained by quantum chemical calculations. The developed method is found to be repeatable, selective and accurate for quantification of methyltestosterone and can be employed for routine analysis. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Development of an Ion-Pairing Reagent and HPLC-UV Method for the Detection and Quantification of Six Water-Soluble Vitamins in Animal Feed.

PubMed

Kim, Ho Jin

2016-01-01

A novel and simple method for detecting six water-soluble vitamins in animal feed using high performance liquid chromatography equipped with a photodiode array detector (HPLC/PDA) and ion-pairing reagent was developed. The chromatographic peaks of the six water-soluble vitamins were successfully identified by comparing their retention times and UV spectra with reference standards. The mobile phase was composed of buffers A (5 mM PICB-6 in 0.1% CH3COOH) and B (5 mM PICB-6 in 65% methanol). All peaks were detected using a wavelength of 270 nm. Method validation was performed in terms of linearity, sensitivity, selectivity, accuracy, and precision. The limits of detection (LODs) for the instrument employed in these experiments ranged from 25 to 197 μg/kg, and the limits of quantification (LOQs) ranged from 84 to 658 μg/kg. Average recoveries of the six water-soluble vitamins ranged from 82.3% to 98.9%. Method replication resulted in intraday and interday peak area variation of <5.6%. The developed method was specific and reliable and is therefore suitable for the routine analysis of water-soluble vitamins in animal feed.

Quantification of lipoic acid in plasma by high-performance liquid chromatography-electrospray ionization mass spectrometry.

PubMed

Chen, Jun; Jiang, Wenming; Cai, Jia; Tao, Weixing; Gao, Xiaoling; Jiang, Xinguo

2005-09-25

A sensitive and specific liquid chromatography electrospray ionization mass spectrometry (LC-ESI-MS) method has been developed and validated for the identification and quantification of lipoic acid (LA) in human plasma. LA and the internal standard, naproxen, were extracted from a 500 microl plasma sample by one-step deproteination using acetonitrile. Chromatographic separation was performed on a Zorbax SB-C(18) Column (100 mmx3.0mm i.d. with 3.5 microm particle size) with the mobile phase consisting of acetonitrile and 0.1% acetic acid (pH 4, adjusted with ammonia solution) (65:35, v/v), and the flow rate was set at 0.3 ml/min. Detection was performed on a single quadrupole mass spectrometer by selected ion monitoring (SIM) mode via electrospray ionization (ESI) source. The method was linear over the concentration range of 5-10,000 ng/ml for LA. The intra- and inter-day precisions were less than 7% and accuracy ranged from -7.87 to 9.74% at the LA concentrations tested. The present method provides a relatively simple and sensitive assay with short turn-around time. The method has been successfully applied to a clinical pharmacokinetic study of LA in 10 healthy subjects.

Rapid determination of amino acids in biological samples using a monolithic silica column.

PubMed

Song, Yanting; Funatsu, Takashi; Tsunoda, Makoto

2012-05-01

A high-performance liquid chromatography method in which fluorescence detection is used for the simultaneous determination of 21 amino acids is proposed. Amino acids were derivatized with 4-fluoro-7-nitro-2,1,3-benzoxadiazole (NBD-F) and then separated on a monolithic silica column (MonoClad C18-HS, 150 mm×3 mm i.d.). A mixture of 25 mM citrate buffer containing 25 mM sodium perchlorate (pH 5.5) and acetonitrile was used as the mobile phase. We found that the most significant factor in the separation was temperature, and a linear temperature gradient from 30 to 49°C was used to control the column temperature. The limits of detection and quantification for all amino acids ranged from 3.2 to 57.2 fmol and 10.8 to 191 fmol, respectively. The calibration curves for the NBD-amino acid had good linearity within the range of 40 fmol to 40 pmol when 6-aminocaproic acid was used as an internal standard. Using only conventional instruments, the 21 amino acids could be analyzed within 10 min. This method was found to be suitable for the quantification of the contents of amino acids in mouse plasma and adrenal gland samples.

Densitometric HPTLC analysis of 8-gingerol in Zingiber officinale extract and ginger-containing dietary supplements, teas and commercial creams

PubMed Central

Alam, Prawez

2013-01-01

Objective To develop and validate a simple, accurate HPTLC method for the analysis of 8-gingerol and to determine the quantity of 8-gingerol in Zingiber officinale extract and ginger-containing dietary supplements, teas and commercial creams. Methods The analysis was performed on 10×20 cm aluminium-backed plates coated with 0.2 mm layers of silica gel 60 F254 (E-Merck, Germany) with n-hexane: ethyl acetate 60: 40 (v/v) as mobile phase. Camag TLC Scanner III was used for the UV densitometric scanning at 569. Results This system was found to give a compact spot of 8-gingerol at retention factor (Rf) value of (0.39±0.04) and linearity was found in the ranges 50-500 ng/spot (r2=0.9987). Limit of detection (12.76 ng/spot), limit of quantification (26.32 ng/spot), accuracy (less than 2 %) and recovery (ranging from 98.22-99.20) were found satisfactory. Conclusions The HPTLC method developed for quantification of 8-gingerol was found to be simple, accurate, reproducible, sensitive and is applicable to the analysis of 8-gingerol in Zingiber officinale extract and ginger-containing dietary supplements, teas and commercial creams. PMID:23905021

Gradient enhanced-fluidity liquid hydrophilic interaction chromatography of ribonucleic acid nucleosides and nucleotides: A "green" technique.

PubMed

Beilke, Michael C; Beres, Martin J; Olesik, Susan V

2016-03-04

A "green" hydrophilic interaction liquid chromatography (HILIC) technique for separating the components of mixtures with a broad range of polarities is illustrated using enhanced-fluidity liquid mobile phases. Enhanced-fluidity liquid chromatography (EFLC) involves the addition of liquid CO2 to conventional liquid mobile phases. Decreased mobile phase viscosity and increased analyte diffusivity results when a liquefied gas is dissolved in common liquid mobile phases. The impact of CO2 addition to a methanol:water (MeOH:H2O) mobile phase was studied to optimize HILIC gradient conditions. For the first time a fast separation of 16 ribonucleic acid (RNA) nucleosides/nucleotides was achieved (16min) with greater than 1.3 resolution for all analyte pairs. By using a gradient, the analysis time was reduced by over 100% compared to similar separations conducted under isocratic conditions. The optimal separation using MeOH:H2O:CO2 mobile phases was compared to MeOH:H2O and acetonitrile:water (ACN:H2O) mobile phases. Based on chromatographic performance parameters (efficiency, resolution and speed of analysis) and an assessment of the environmental impact of the mobile phase mixtures, MeOH:H2O:CO2 mixtures are preferred over ACN:H2O or MeOH:H2O mobile phases for the separation of mixtures of RNA nucleosides and nucleotides. Copyright © 2016 Elsevier B.V. All rights reserved.

Mixed-mode chromatography/isotope ratio mass spectrometry.

PubMed

McCullagh, James S O

2010-03-15

Liquid chromatography coupled to molecular mass spectrometry (LC/MS) has been a standard technique since the early 1970s but liquid chromatography coupled to high-precision isotope ratio mass spectrometry (LC/IRMS) has only been available commercially since 2004. This development has, for the first time, enabled natural abundance and low enrichment delta(13)C measurements to be applied to individual analytes in aqueous mixtures creating new opportunities for IRMS applications, particularly for the isotopic study of biological molecules. A growing number of applications have been published in a range of areas including amino acid metabolism, carbohydrates studies, quantification of cellular and plasma metabolites, dietary tracer and nucleic acid studies. There is strong potential to extend these to new compounds and complex matrices but several challenges face the development of LC/IRMS methods. To achieve accurate isotopic measurements, HPLC separations must provide baseline-resolution between analyte peaks; however, the design of current liquid interfaces places severe restrictions on compatible flow rates and in particular mobile phase compositions. These create a significant challenge on which reports associated with LC/IRMS have not previously focused. Accordingly, this paper will address aspects of chromatography in the context of LC/IRMS, in particular focusing on mixed-mode separations and their benefits in light of these restrictions. It aims to provide an overview of mixed-mode stationary phases and of ways to improve high aqueous separations through manipulation of parameters such as column length, temperature and mobile phase pH. The results of several practical experiments are given using proteogenic amino acids and nucleosides both of which are of noted importance in the LC/IRMS literature. This communication aims to demonstrate that mixed-mode stationary phases provide a flexible approach given the constraints of LC/IRMS interface design and acts as a practical guide for the development of new chromatographic methods compatible with LC/IRMS applications. Copyright 2010 John Wiley & Sons, Ltd.

Determination of opiates and cocaine in urine by high pH mobile phase reversed phase UPLC-MS/MS.

PubMed

Berg, Thomas; Lundanes, Elsa; Christophersen, Asbjørg S; Strand, Dag Helge

2009-02-01

A fast and selective ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method for the determination of opiates (morphine, codeine, 6-monoacetylmorphine (6-MAM), pholcodine, oxycodone, ethylmorphine), cocaine and benzoylecgonine in urine has been developed and validated. Sample preparation was performed by solid phase extraction (SPE) on a mixed mode cation exchange (MCX) cartridge. For optimized chromatographic performance with repeatable retention times, narrow and symmetrical peaks, and focusing of all analytes at the column inlet at gradient start, a basic mobile phase consisting of 5mM ammonium bicarbonate, pH 10.2, and methanol (MeOH) was chosen. Positive electrospray ionization (ESI(+)) MS/MS detection was performed with a minimum of two multiple reaction monitoring (MRM) transitions for each analyte. Deuterium labelled-internal standards were used for six of the analytes. Between-assay retention time repeatabilities (n=10 series, 225 injections in total) had relative standard deviation (RSD) values within 0.1-0.6%. Limit of detection (LOD) and limit of quantification (LOQ) values were in the range 0.003-0.05 microM (0.001-0.02 microg/mL) and 0.01-0.16 microM (0.003-0.06 microg/mL), respectively. The RSD values of the between-assay repeatabilities of concentrations were

The use of experimental design in the development of an HPLC-ECD method for the analysis of captopril.

PubMed

Khamanga, Sandile M; Walker, Roderick B

2011-01-15

An accurate, sensitive and specific high performance liquid chromatography-electrochemical detection (HPLC-ECD) method that was developed and validated for captopril (CPT) is presented. Separation was achieved using a Phenomenex(®) Luna 5 μm (C(18)) column and a mobile phase comprised of phosphate buffer (adjusted to pH 3.0): acetonitrile in a ratio of 70:30 (v/v). Detection was accomplished using a full scan multi channel ESA Coulometric detector in the "oxidative-screen" mode with the upstream electrode (E(1)) set at +600 mV and the downstream (analytical) electrode (E(2)) set at +950 mV, while the potential of the guard cell was maintained at +1050 mV. The detector gain was set at 300. Experimental design using central composite design (CCD) was used to facilitate method development. Mobile phase pH, molarity and concentration of acetonitrile (ACN) were considered the critical factors to be studied to establish the retention time of CPT and cyclizine (CYC) that was used as the internal standard. Twenty experiments including centre points were undertaken and a quadratic model was derived for the retention time for CPT using the experimental data. The method was validated for linearity, accuracy, precision, limits of quantitation and detection, as per the ICH guidelines. The system was found to produce sharp and well-resolved peaks for CPT and CYC with retention times of 3.08 and 7.56 min, respectively. Linear regression analysis for the calibration curve showed a good linear relationship with a regression coefficient of 0.978 in the concentration range of 2-70 μg/mL. The linear regression equation was y=0.0131x+0.0275. The limits of detection (LOQ) and quantitation (LOD) were found to be 2.27 and 0.6 μg/mL, respectively. The method was used to analyze CPT in tablets. The wide range for linearity, accuracy, sensitivity, short retention time and composition of the mobile phase indicated that this method is better for the quantification of CPT than the pharmacopoeial methods. Copyright © 2010 Elsevier B.V. All rights reserved.

Optimized HPLC method for analysis of polar and nonpolar heterocyclic amines in cooked meat products.

PubMed

Gibis, Monika

2009-01-01

A simple, precise, and specific column high-performance liquid chromatographic (HPLC) method with UV absorption diode array and fluorescence detection has been developed by optimizing a previously described method for the simultaneous quantification of 15 polar and nonpolar heterocyclic amines (HAs) in fried meat products. The HPLC determination could be improved due to the application of a silica-based reversed-phase column with octadecyl groups (TSK-gel Super ODS) and a particle size of 2 microm. The separation of HAs in the complex meat matrix was performed with a 21 min mobile phase gradient. The method was validated for instrumental precision, repeatability, and selectivity and compared with a previously published method. After liquid adsorption of the basic sample mixture on diatomaceous earth, HAs were extracted with ethyl acetate. For cleanup, solid-phase extraction (silica propylsulfonic acid and octadecyl cartridges) and different washing steps were applied. Both nonpolar and polar HAs were determined in one fraction. The calibration curves of all HAs were linear for the applied detection system (correlation coefficient = 0.990-0.995). The recoveries, with the exception of 3-amino-1-methyl-5H-pyrido [4,3-b]indole (Trp-P-2), were between 42 and 98% from meat samples spiked in a range of 1.5 to 3.3 ng/g for fluorescence-active and 4.3 to 8 ng/g for UV-active HAs. For quantification of HAs, the standard addition method was used for adjustment of different characteristics of HAs in the extraction. In fried meat samples (chicken breast and beef patties), 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MelQx), 2-amino-3,4,8-trimethylimidazo[4,5-f] quinoxaline(4,8-DiMelQx), 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), norharmane, and harmane were found in a concentration range of 0.02 to 14.3 ng/g.

Microwave assisted synthesis for A2E and development of LC-ESI-MS method for quantification of ocular bisretinoids in human retina.

PubMed

Kotnala, A; Senthilkumari, S; Halder, N; Kumar, A; Velpandian, T

2018-01-15

To develop a microwave assisted method for the rapid synthesis of A2E and also to develop a method to quantify N-retinylidene-N-retinylethanolamine(A2E), all-trans retinal dimer (ATRD), A2-glycerophospho ethanolamine (A2GPE), dihydropyridine phosphatidyl ethanolamine (A2DHPE) and monofuran A2E (MFA2E) in age matched retina. The development of microwave assisted synthesis of A2E, its purification and characterization for its utility in quantification in human retina. The semi-quantitative method development using LC-ESI-MS, LC-ESI-MS/MS and LC-APCI-MS/MS from pooled macula and peripheral retina for the bisretinoid analysis has been done. Maximum A2E conversion using microwave assisted process took place at 80°C for 45min with a yield of 55.01%. Highly sensitive and specific mass spectrometric method was developed using reverse phase C-18 separation with positive electrospray ionization and positive atmospheric phase chemical ionization of tandom mass spectrometry. A gradient mobile phase separation was achieved using water and methanol with 0.1% TFA. Multiple reaction monitoring acquisition for ESI and APCI was performed at ATRD m/z 551.2/522.2, A2GPE m/z 746.4/729.5, A2DHPEm/z 594.4/576.5, MFA2E m/z 608.2/591.2, A2E m/z 592.4/418.2. Method was validated using LC-ESI-SIM mode to determine selectivity, linearity, sensitivity, precision and accuracy. An attempt towards optimization of the synthetic procedure of A2E was made so as to reduce the lengthy reaction time without compromising the yield. Developed method was capable enough for the detection of low level of bisretinids in retina. Copyright © 2017 Elsevier B.V. All rights reserved.

The Hestia Project: High Spatial Resolution Fossil Fuel Carbon Dioxide Emissions Quantification at Hourly Scale in Indianapolis, USA

NASA Astrophysics Data System (ADS)

Zhou, Y.; Gurney, K. R.

2009-12-01

In order to advance the scientific understanding of carbon exchange with the land surface and contribute to sound, quantitatively-based U.S. climate change policy interests, quantification of greenhouse gases emissions drivers at fine spatial and temporal scales is essential. Quantification of fossil fuel CO2 emissions, the primary greenhouse gases, has become a key component to cost-effective CO2 emissions mitigation options and a carbon trading system. Called the ‘Hestia Project’, this pilot study generated CO2 emissions down to high spatial resolution and hourly scale for the greater Indianapolis region in the USA through the use of air quality and traffic monitoring data, remote sensing, GIS, and building energy modeling. The CO2 emissions were constructed from three data source categories: area, point, and mobile. For the area source emissions, we developed an energy consumption model using DOE/EIA survey data on building characteristics and energy consumption. With the Vulcan Project’s county-level CO2 emissions and simulated building energy consumption, we quantified the CO2 emissions for each individual building by allocating Vulcan emissions to roughly 50,000 structures in Indianapolis. The temporal pattern of CO2 emissions in each individual building was developed based on temporal patterns of energy consumption. The point sources emissions were derived from the EPA National Emissions Inventory data and effluent monitoring of electricity producing facilities. The mobile source CO2 emissions were estimated at the month/county scale using the Mobile6 combustion model and the National Mobile Inventory Model database. The month/county scale mobile source CO2 emissions were downscaled to the “native” spatial resolution of road segments every hour using a GIS road atlas and traffic monitoring data. The result is shown in Figure 1. The resulting urban-scale inventory can serve as a baseline of current CO2 emissions and should be of immediate use to city environmental managers and regional industry as they plan emission mitigation options and project future emission trends. The results obtained here will also be a useful comparison to atmospheric CO2 monitoring efforts from the top-down. Figure 1. Location of the study area, the building level and mobile CO2 emissions, and an enlarged example neighborhood

Mobile Methane Monitoring Surveys of the Pinedale Anticline Development in the Upper Green River Basin of Wyoming

NASA Astrophysics Data System (ADS)

Field, R. A.; Soltis, J.; Murphy, S. M.; Montague, D. C.

2013-12-01

Methane emissions from the oil and gas sector have become part of a wider debate of the magnitude of climate change impacts from different fossil fuels. This debate is contentious, as a wide range of estimates of development area leakage rates have been postulated. Here we present the results of mobile monitoring performed in the Pinedale Anticline, WY (PAPA) development. A 4-hour circuit upwind, downwind and within the development was designed to determine methane distributions relative to background concentrations. The circuit was repeated thirty-two times to assess the influence of meteorology and emission sources upon measured values. Figure 1 is a composite of methane data for the project. This pilot project enabled identification of areas and emission sources for subsequent plume quantification studies planned for 2014. Here we present the finding of the circuits through mapping and site comparisons. Along with the methane measurements, mobile ozone and oxides of nitrogen observations were also performed, thereby facilitating a better understanding of the phenomenon of wintertime ground level ozone. Building upon surveys from 2012, we also carried out canister measurements of VOC at selected sites to demonstrate the importance of relating methane and selected VOC concentrations when identifying variations in the contributions of emission sources to ambient measurements. While methane and C2 to C5 alkanes elevations are widespread and highly correlated, those of higher molecular weight VOC, in particular benzene, toluene and xylene isomers, show the importance of emission sources other than wet gas leakage. We discuss the utility of 3D visualization of methane data for illustrating the distribution of leakage relative to emission sources. The influence of emission sources and meteorology upon the data is explored through a comparative analysis of the circuit data. This assessment sets the foundation for planned plume quantification. Finally we compare the mobile data with 1-minute data from the Wyoming DEQ site at Boulder, WY, to determine how well the site represents conditions in the surrounding area. Effective policy decisions require better coupling of air quality measurements and emission inventories. We outline an approach that links regulatory network site data with mobile monitoring and plume quantification that should reduce uncertainty for determining the magnitude of methane emissions from oil and gas sources. Pinedale Anticline methane concentrations for mobile monitoring circuits 2/12/2013 to 3/8/2013

[Determination of wilforine in honey using solid phase extraction purification and ultra performance liquid chromatography-tanden mas spectrometry].

PubMed

Lei, Meikang; Peng, Fang; Ding, Tao; Zhu, Zitong; Xu, Jiawen; Wu, Xiaoqin

2015-01-01

A method based on solid phase extraction and ultra performance liquid chromatography coupled with tandem mass spectrometry (SPE-UPLC-MS/MS) has been proposed for the determination of wilforine residue in honey. After the sample was dissolved with water, concentrated and purified by an HLB solid phase extraction cartridge, the UPLC separation was performed on a Hypersil GOLD C18 column (50 mm x 2.1 mm, 1.9 microm) utilizing a gradient elution program of methanol (containing 0.15% formic acid) and water as mobile phases at a flow rate of 0. 25 mL/min. The determination was carried out with electrospray ion source in the positive mode (ESI) and multiple reaction monitoring (MRM) mode. The mass concentration of wilforine in the range of 0.01-2 microg/L was linearly correlated with the peak area, and the correlation coefficients was greater than 0.998. The limit of quantification (S/N>10) for wilforine was 0.01 microg/kg. The recoveries were 76.1% to 96.2% in the spiked levels of 0.01, 0.05 and 0.5 microg/kg with the relative standard deviations (RSD, n=6) lower than 10%. The results indicate that the method is rapid, sensitive and accurate, and can be applied for the qualitative and quantitative analysis of wilforine in honey.

[Determination of deoxynivalenol in grain and its products by solid-phase extraction coupled with high performance liquid chromatography-tandem mass spectrometry].

PubMed

Huang, Juan; Chen, Guosong; Zhang, Xiaoyan; Shen, Chongyu; Lü, Chen; Wu, Bin; Liu, Yan; Chen, Huilan; Ding, Tao

2012-11-01

A method was established for the determination of deoxynivalenol (vomitoxin) in grain and its products based on solid-phase extraction coupled with high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The sample was firstly extracted by acetonitrile-water (84:16, v/v). The extract was then cleaned-up by an HLB solid phase extraction cartridge. The separation was carried out on a Phenomenex Kinetex C18 column (100 mm x4. 6 mm, 2.6 microm) with a gradient elution using 0.3% per hundred ammonia solution-acetonitrile as mobile phases. The analysis of deoxynivalenol was performed under electrospray negative ionization mode. The limit of detection (LOD, S/N= 3) and the limit of quantification (LOQ, S/N = 10) were 20 microg/kg and 50 microg/kg, respectively. A good linearity (r > 0.99) was achieved for the target compound over the range of 20-1000 pg/L. The recoveries at the three spiked levels (50, 100, 500 microg/kg) in the blank matrices such as flour, barley, soybean, rice, cornmeal, cassava and wheat, were varied from 75.6% to 111.0% with the relative standard deviations no more than 13. 0%. The method is accurate, efficient, sensitive and practical. The cost of pretreatment is obviously reduced by replacing immunoaffinity columns and Mycosep columns with HLB columns which have the same purification effect.

Phased Arrays of Ground and Airborne Mobile Terminals for Satellite Communications

NASA Technical Reports Server (NTRS)

Huang, John

1996-01-01

Phased array antenna is beginning to play an important in the arena of mobile/satellite communications. Two examples of mobile terminal phased arrays will be shown. Their technical background, challenges, and cost drivers will be discussed. A possible solution to combat some of the deficiencies of the conventional phased array by exploiting the phased reflectarray technology will be briefly presented.

Uranium association with iron-bearing phases in mill tailings from Gunnar, Canada.

PubMed

Othmane, Guillaume; Allard, Thierry; Morin, Guillaume; Sélo, Madeleine; Brest, Jessica; Llorens, Isabelle; Chen, Ning; Bargar, John R; Fayek, Mostafa; Calas, Georges

2013-11-19

The speciation of uranium was studied in the mill tailings of the Gunnar uranium mine (Saskatchewan, Canada), which operated in the 1950s and 1960s. The nature, quantification, and spatial distribution of uranium-bearing phases were investigated by chemical and mineralogical analyses, fission track mapping, electron microscopy, and X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) spectroscopies at the U LIII-edge and Fe K-edge. In addition to uranium-containing phases from the ore, uranium is mostly associated with iron-bearing minerals in all tailing sites. XANES and EXAFS data and transmission electron microscopy analyses of the samples with the highest uranium concentrations (∼400-700 mg kg(-1) of U) demonstrate that uranium primarily occurs as monomeric uranyl ions (UO2(2+)), forming inner-sphere surface complexes bound to ferrihydrite (50-70% of the total U) and to a lesser extent to chlorite (30-40% of the total U). Thus, the stability and mobility of uranium at the Gunnar site are mainly influenced by sorption/desorption processes. In this context, acidic pH or alkaline pH with the presence of UO2(2+)- and/or Fe(3+)-complexing agents (e.g., carbonate) could potentially solubilize U in the tailings pore waters.

Reversed-phase HPLC analysis of levetiracetam in tablets using monolithic and conventional C18 silica columns.

PubMed

Can, Nafiz O; Arli, Goksel

2010-01-01

Development and validation of an RP-HPLC method for determination of levetiracetam in pharmaceutical tablets is described. The separation and quantification of levetiracetam and caffeine (internal standard) were performed using a single analytical procedure with two different types of stationary phases, conventional Phenomenex Gemini C18 (100 x 4.6 mm, 5 microm) and Merck Chromolith Performance RP18e (100 x 4.6 mm, macropore size 2 mm, micropore size 13 nm) monolithic silica. Five-microliter aliquots of samples were injected into the system and eluted using water-acetonitrile (90 + 10, v/v) mobile phase pumped at the rate of 1 mL/min. The analyte peaks were detected at 200 nm using a diode array detector with adequate resolution. Validation studies were performed using the method recommended by the International Conference on Harmonization, the U.S. Pharmacopeia, and AOAC INTERNATIONAL, which includes accuracy, precision, range, limits, robustness, and system suitability parameters. Levetiracetam and caffeine were detected in about 7 min using the conventional column, whereas less than 5 min was required when the monolithic column was used. Calibration plots had r values close to unity in the range of 0.8-8.0 microg/mL. Assay of levetiracetam in a tablet formulation was demonstrated as an application to real samples.

Rapid and Sensitive Reverse-phase High-performance Liquid Chromatography Method for Estimation of Ketorolac in Pharmaceuticals Using Weighted Regression

PubMed Central

Dubey, S. K.; Duddelly, S.; Jangala, H.; Saha, R. N.

2013-01-01

A reliable, rapid and sensitive isocratic reverse phase high-performance liquid chromatography method has been developed and validated for assay of ketorolac tromethamine in tablets and ophthalmic dosage forms using diclofenac sodium as an internal standard. An isocratic separation of ketorolac tromethamine was achieved on Oyster BDS (150×4.6 mm i.d., 5 μm particle size) column using mobile phase of methanol:acetonitrile:sodium dihydrogen phosphate (20 mM; pH 5.5) (50:10:40, %v/v) at a flow rate of 1.0 ml/min. The eluents were monitored at 322 nm for ketorolac and at 282 nm for diclofenac sodium with a photodiode array detector. The retention times of ketorolac and diclofenac sodium were found to be 1.9 min and 4.6 min, respectively. Response was a linear function of drug concentration in the range of 0.01-15 μg/ml (R2=0.994; linear regression model using weighing factor 1/x2) with a limit of detection and quantification of 0.002 μg/ml and 0.007 μg/ml, respectively. The % recovery and % relative standard deviation values indicated the method was accurate and precise. PMID:23901166

Development and validation of a reversed-phase HPLC method for simultaneous estimation of ambroxol hydrochloride and azithromycin in tablet dosage form.

PubMed

Shaikh, K A; Patil, S D; Devkhile, A B

2008-12-15

A simple, precise and accurate reversed-phase liquid chromatographic method has been developed for the simultaneous estimation of ambroxol hydrochloride and azithromycin in tablet formulations. The chromatographic separation was achieved on a Xterra RP18 (250 mm x 4.6 mm, 5 microm) analytical column. A Mixture of acetonitrile-dipotassium phosphate (30 mM) (50:50, v/v) (pH 9.0) was used as the mobile phase, at a flow rate of 1.7 ml/min and detector wavelength at 215 nm. The retention time of ambroxol and azithromycin was found to be 5.0 and 11.5 min, respectively. The validation of the proposed method was carried out for specificity, linearity, accuracy, precision, limit of detection, limit of quantitation and robustness. The linear dynamic ranges were from 30-180 to 250-1500 microg/ml for ambroxol hydrochloride and azithromycin, respectively. The percentage recovery obtained for ambroxol hydrochloride and azithromycin were 99.40 and 99.90%, respectively. Limit of detection and quantification for azithromycin were 0.8 and 2.3 microg/ml, for ambroxol hydrochloride 0.004 and 0.01 microg/ml, respectively. The developed method can be used for routine quality control analysis of titled drugs in combination in tablet formulation.

Utilization of Photochemically Induced Fluorescence Detection for HPLC Determination of Genotoxic Impurities in the Vortioxetine Manufacturing Process.

PubMed

Douša, Michal; Doubský, Jan; Srbek, Jan

2016-07-01

An analytical reversed-phase high-performance liquid chromatography (HPLC) method for the detection and quantitative determination of two genotoxic impurities at ppm level present in the vortioxetine manufacturing process is described. Applying the concept of threshold of toxicological concern, a limit of 75 ppm each for both genotoxic impurities was calculated based on the maximum daily dose of active pharmaceutical ingredients. The novel reversed-phase HPLC method with photochemically induced fluorescence detection was developed on XSELECT Charged Surface Hybrid Phenyl-Hexyl column using the mobile phase consisted a mixture of 10 mM ammonium formate pH 3.0 and acetonitrile. The elution was performed using an isocratic composition of 48:52 (v/v) at a flow rate of 1.0 mL/min. The photochemically induced fluorescence detection is based on the use of UV irradiation at 254 nm through measuring the fluorescence intensity at 300 nm and an excitation wavelength of 272 nm to produce fluorescent derivatives of both genotoxic impurities. The online photochemical conversion and detection is easily accomplished for two expected genotoxic impurities and provides a sufficiently low limit detection and quantification for the target analysis. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Quantitative isomer-specific N-glycan fingerprinting using isotope coded labeling and high performance liquid chromatography-electrospray ionization-mass spectrometry with graphitic carbon stationary phase.

PubMed

Michael, Claudia; Rizzi, Andreas M

2015-02-27

Glycan reductive isotope labeling (GRIL) using (12)C6-/(13)C6-aniline as labeling reagent is reported with the aim of quantitative N-glycan fingerprinting. Porous graphitized carbon (PGC) as stationary phase in capillary scale HPLC coupled to electrospray mass spectrometry with time of flight analyzer was applied for the determination of labeled N-glycans released from glycoproteins. The main benefit of using stable isotope-coding in the context of comparative glycomics lies in the improved accuracy and precision of the quantitative analysis in combined samples and in the potential of correcting for structure-dependent incomplete enzymatic release of oligosaccharides when comparing identical target proteins. The method was validated with respect to mobile phase parameters, reproducibility, accuracy, linearity and limit of detection/quantification (LOD/LOQ) using test glycoproteins. It is shown that the developed method is capable of determining relative amounts of N-glycans (including isomers) comparing two samples in one single HPLC-MS run. The analytical potential and usefulness of GRIL in combination with PGC-ESI-TOF-MS is demonstrated comparing glycosylation in human monoclonal antibodies produced in Chinese hamster ovary cells (CHO) and hybridoma cell lines. Copyright © 2015 Elsevier B.V. All rights reserved.

Simulated molecular-scale interaction of supercritical fluid mobile and stationary phases.

PubMed

Siders, Paul D

2017-12-08

In supercritical fluid chromatography, molecules from the mobile phase adsorb on the stationary phase. Stationary-phase alkylsilane-terminated silica surfaces might adsorb molecules at the silica, among the silanes, on a silane layer, or in pore space between surfaces. Mobile phases of carbon dioxide, pure and modified with methanol, and stationary phases were simulated at the molecular scale. Classical atomistic force fields were used in Gibbs-ensemble hybrid Monte Carlo calculations. Excess adsorption of pure carbon dioxide mobile phase peaked at fluid densities of 0.002-0.003Å -3 . Mobile phase adsorption from 7% methanol in carbon dioxide peaked at lower fluid density. Methanol was preferentially adsorbed from the mixed fluid. Surface silanes prevented direct interaction of fluid-phase molecules with silica. Some adsorbed molecules mixed with tails of bonded silanes; some formed layers above the silanes. Much adsorption occurred by filling the space between surfaces in the stationary-phase model. The distribution in the stationary phase of methanol molecules from a modified fluid phase varied with pressure. Copyright © 2017 Elsevier B.V. All rights reserved.

Detection of Xeljanz enantiomers in diethyl amine active pharmaceutical ingredients and tablets.

PubMed

Wang, Na-Na; Zhang, Dao-Lin; Jiang, Xin-Hui

2015-03-01

A high-performance liquid chromatography (HPLC) method was established to detect Xeljanz enantiomers in active pharmaceutical ingredients (APIs) and tablets. The separation was achieved on a Chiralpak IC column using a mobile phase of hexane-ethanol-diethylamine (65:35:0.1, v/v). The detection wavelength was 289 nm. The peak areas and the enantiomer concentrations in the range of 0.15-2.25 μg•mL(-1) were in high linearity, with correlation coefficients higher than 0.999. The recoveries were 86.44% at the concentrations of 7.5, 18.75, and 37.5 μg•mL(-1) . The limit of detection (LOD) and limit of quantification (LOQ) were 0.042 and 0.14 μg•mL(-1) , respectively. This HPLC method is suitable for detecting the enantiomers of Xeljanz in its APIs and tablets. © 2014 Wiley Periodicals, Inc.

Measurement of Menadione in Urine by HPLC

PubMed Central

Rajabi, Ala Al; Peterson, James; Choi, Sang Woon; Suttie, John; Barakat, Susan; Booth, Sarah L

2010-01-01

Menadione is a metabolite of vitamin K that is excreted in urine. A high performance liquid chromatography (HPLC) method using a C30 column, post-column zinc reduction and fluorescence detection was developed to measure urinary menadione. The mobile phase was composed of 95% methanol with 0.55% aqueous solution and 5% DI H2O. Menaquinone-2 (MK-2) was used as an internal standard. The standard calibration curve was linear with a correlation coefficient (R2) of 0.999 for both menadione and MK-2. The lower limit of quantification (LLOQ) was 0.3 pmole menadione/mL urine. Sample preparation involved hydrolysis of menadiol conjugates and oxidizing the released menadiol to menadione. Using this method, urinary menadione was shown to increase in response to 3 years of phylloquinone supplementation. This HPLC method is a sensitive and reproducible way to detect menadione in urine. Research support: USDA ARS Cooperative Agreement 58-1950-7-707. PMID:20719580

Measurement of menadione in urine by HPLC.

PubMed

Al Rajabi, Ala; Peterson, James; Choi, Sang-Woon; Suttie, John; Barakat, Susan; Booth, Sarah L

2010-09-15

Menadione is a metabolite of vitamin K that is excreted in urine. A high performance liquid chromatography (HPLC) method using a C(30) column, post-column zinc reduction and fluorescence detection was developed to measure urinary menadione. The mobile phase was composed of 95% methanol with 0.55% aqueous solution and 5% DI H(2)O. Menaquinone-2 (MK-2) was used as an internal standard. The standard calibration curve was linear with a correlation coefficient (R(2)) of 0.999 for both menadione and MK-2. The lower limit of quantification (LLOQ) was 0.3pmole menadione/mL urine. Sample preparation involved hydrolysis of menadiol conjugates and oxidizing the released menadiol to menadione. Using this method, urinary menadione was shown to increase in response to 3 years of phylloquinone supplementation. This HPLC method is a sensitive and reproducible way to detect menadione in urine. Copyright (c) 2010 Elsevier B.V. All rights reserved.

High-performance liquid chromatography-electrospray ionization mass spectrometry determination of sodium ferulate in human plasma.

PubMed

Yang, Cheng; Tian, Yuan; Zhang, Zunjian; Xu, Fengguo; Chen, Yun

2007-02-19

A selective and sensitive high-performance liquid chromatography-electrospray ionization mass spectrometry method has been developed for the determination of sodium ferulate in human plasma. The sample preparation was a liquid-liquid extraction and chromatographic separation was achieved with an Agilent ZORBAX SB-C(18) (3.5 microm, 100 mm x 3.0 mm) column, using a mobile phase of methanol-0.05% acetic acid 40:60 (v/v). Standard curves were linear (r(2)=0.9982) over the concentration range of 0.007-4.63 nM/ml and had acceptable accuracy and precision. The within- and between-batch precisions were within 12% relative standard deviation. The lower limit of quantification (LLOQ) was 0.007 nM/ml. The validated HPLC-ESI-MS method has been used successfully to study sodium ferulate pharmacokinetics, bioavailability and bioequivalence in 20 healthy volunteers.

Studies on the electrochemical behavior of thiazolidine and its applications using a flow-through chronoamperometric sensor based on a gold electrode.

PubMed

Wang, Lai-Hao; Li, Wen-Jie

2011-09-06

The electrochemical behaviors of thiazolidine (tetrahydrothiazole) on gold and platinum electrodes were investigated in a Britton-Robinson buffer (pH 2.77-11.61), acetate buffer (pH 4.31), phosphate buffer solutions (pH 2.11 and 6.38) and methanol or acetonitrile containing various supporting electrolytes. Detection was based on a gold wire electrochemical signal obtained with a supporting electrolyte containing 20% methanol-1.0 mM of phosphate buffer (pH 6.87, potassium dihydrogen phosphate and dipotassium hydrogen phosphate) as the mobile phase. Comparison with results obtained with a commercial amperometric detector shows good agreement. Using the chronoamperometric sensor with the current at a constant potential, and measurements with suitable experimental parameters, a linear concentration from 0.05 to 16 mg L-1 was found. The limit of quantification (LOQ) of the method for thiazolidine was found to be 1 ng.

Screening and determination of sibutramine in adulterated herbal slimming supplements by HPTLC-UV densitometry.

PubMed

Mathon, Caroline; Ankli, Anita; Reich, Eike; Bieri, Stefan; Christen, Philippe

2014-01-01

The adulteration of herbal supplements is of growing importance, especially when they contain undeclared compounds like sibutramine that are unsafe drugs. Sibutramine was withdrawn from US and European markets in 2010. In this study, an HPTLC-UV densitometric method was developed for the quantification of sibutramine in herbal diet foods. Sample extracts were directly applied onto HPTLC silica gel plates and separated with a mobile phase made of a toluene-methanol mixture. Sibutramine was quantified at 225 nm and its unequivocal identification was confirmed by MS using a TLC-MS interface. During two surveys, 52 weight loss supplements obtained via the Internet were screened. Half of those were adulterated with sibutramine at amounts reaching up to 35 mg per capsule. The results of this validated HPTLC method were compared with those obtained by HPLC-UV and HPLC-MS/MS. The results were not significantly different with the three methods.

Mass spectrometry based proteomics: existing capabilities and future directions

PubMed Central

Angel, Thomas E.; Aryal, Uma K.; Hengel, Shawna M.; Baker, Erin S.; Kelly, Ryan T.; Robinson, Errol W.; Smith, Richard D.

2012-01-01

Mass spectrometry (MS)-based proteomics is emerging as a broadly effective means for identification, characterization, and quantification of proteins that are integral components of the processes essential for life. Characterization of proteins at the proteome and sub-proteome (e.g., the phosphoproteome, proteoglycome, or degradome/peptidome) levels provides a foundation for understanding fundamental aspects of biology. Emerging technologies such as ion mobility separations coupled with MS and microchip-based-proteome measurements combined with MS instrumentation and chromatographic separation techniques, such as nanoscale reversed phase liquid chromatography and capillary electrophoresis, show great promise for both broad undirected and targeted highly sensitive measurements. MS-based proteomics is increasingly contribute to our understanding of the dynamics, interactions, and roles that proteins and peptides play, advancing our understanding of biology on a systems wide level for a wide range of applications including investigations of microbial communities, bioremediation, and human health. PMID:22498958

Selective identification and quantification of saccharin by liquid chromatography and fluorescence detection.

PubMed

Bruno, Sergio N F; Cardoso, Carlos R; Maciel, Márcia Mosca A; Vokac, Lidmila; da Silva Junior, Ademário I

2014-09-15

High-pressure liquid chromatography with ultra-violet detection (HPLC-UV) is one of the most commonly used methods to identify and quantify saccharin in non-alcoholic beverages. However, due to the wide variety of interfering UV spectra in saccharin-containing beverage matrices, the same method cannot be used to measure this analyte accurately. We have developed a new, highly effective method to identify and quantify saccharin using HPLC with fluorescence detection (HPLC-FLD). The excitation wavelength (250 nm) and emission wavelength (440 nm) chosen increased selectivity for all matrices and ensured few changes were required in the mobile phase or other parameters. The presence of saccharin in non-diet beverages - a fraud commonly used to replace more expensive sucrose - was confirmed by comparing coincident peaks as well as the emission spectra of standards and samples. Copyright © 2014 Elsevier Ltd. All rights reserved.

Systematic Evaluation of Chromatographic Parameters for Isoquinoline Alkaloids on XB-C18 Core-Shell Column Using Different Mobile Phase Compositions

PubMed Central

Sowa, Ireneusz; Zielińska, Sylwia; Sawicki, Jan; Bogucka-Kocka, Anna; Staniak, Michał; Bartusiak-Szcześniak, Ewa; Podolska-Fajks, Maja; Kocjan, Ryszard

2018-01-01

Chelidonium majus L. is a rich source of isoquinoline alkaloids with confirmed anti-inflammatory, choleretic, spasmolytic, antitumor, and antimicrobial activities. However, their chromatographic analysis is difficult because they may exist both in charged and uncharged forms and may result in the irregular peak shape and the decrease in chromatographic system efficacy. In the present work, the separation of main C. majus alkaloids was optimized using a new-generation XB-C18 endcapped core-shell column dedicated for analysis of alkaline compounds. The influence of organic modifier concentration, addition of salts, and pH of eluents on chromatographic parameters such as retention, resolution, chromatographic plate numbers, and peak asymmetry was investigated. The results were applied to elaborate the optimal chromatographic system for simultaneous quantification of seven alkaloids from the root, herb, and fruit of C. majus. PMID:29675288

Liquid chromatography/electrospray ionization tandem mass spectrometry analysis of octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX).

PubMed

Pan, Xiaoping; Zhang, Baohong; Tian, Kang; Jones, Lindsey E; Liu, Jun; Anderson, Todd A; Wang, Jia-Sheng; Cobb, George P

2006-01-01

A quantitative liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS) method was developed for the analysis of the explosive, octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX). In negative ionization mode, HMX forms an acetate adduct ion [M + CH(3)COO](-), m/z 355, in the presence of a small amount of acetic acid in the mobile phase. The ESI collision-induced dissociation (CID) spectrum of m/z 355 was acquired and the transitions m/z 355 --> 147 and m/z 355 --> 174 were chosen for the determination of HMX in samples. Using this quantification technique, the method detection limit was 1.57 microg/L and good linearity was achieved in the range 5-500 microg/L. This method will help to unambiguously analyze environmentally relevant concentrations of HMX. Copyright (c) 2006 John Wiley & Sons, Ltd.

High-performance liquid chromatographic assay for the determination of Aloe Emodin in mouse plasma.

PubMed

Zaffaroni, M; Mucignat, C; Pecere, T; Zagotto, G; Frapolli, R; D'Incalci, M; Zucchetti, M

2003-10-25

An isocratic high-performance liquid chromatography (HPLC) method was developed and validated to determine Aloe Emodin (AE) in mouse plasma. The analysis required 0.3 ml of plasma and involves extraction with dichloromethane. The HPLC separation was carried out on Symmetry Shield RP18, a mobile phase of methanol-water-acetic acid (65:35:0.2) and fluorescence detection at lambda(ex)=410 nm and lambda(em)=510 nm. The retention time of AE was 11.7 min. The assay was linear from 10 to 1,000 ng/ml (r2 > or = 0.999), showed intra- and inter-day precision within 7.8 and 4.7%, and accuracy of 87.3-105.7%. Detection limit (LOD) and quantification limit (LOQ) were 4.5 and 5 ng/ml, respectively. The method was applied to determine for the first time the pharmacokinetic of AE in mice.

Absolute protein quantification of clinically relevant cytochrome P450 enzymes and UDP-glucuronosyltransferases by mass spectrometry-based targeted proteomics.

PubMed

Gröer, C; Busch, D; Patrzyk, M; Beyer, K; Busemann, A; Heidecke, C D; Drozdzik, M; Siegmund, W; Oswald, S

2014-11-01

Cytochrome P450 (CYP) enzymes and UDP-glucuronosyltransferases (UGT) are major determinants in the pharmacokinetics of most drugs on the market. To investigate their impact on intestinal and hepatic drug metabolism, we developed and validated quantification methods for nine CYP (CYP1A2, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6, CYP2E1, CYP3A4 and CYP3A5) and four UGT enzymes (UGT1A1, UGT1A3, UGT2B7 and UGT2B15) that have been shown to be of clinical relevance in human drug metabolism. Protein quantification was performed by targeted proteomics using liquid chromatography with tandem mass spectrometry (LC-MS/MS)-based determination of enzyme specific peptides after tryptic digestion using in each case stable isotope labelled peptides as internal standard. The chromatography of the respective peptides was performed with gradient elution using a reversed phase (C18) column (Ascentis(®) Express Peptide ES-C18, 100mm×2.1mm, 2.7μm) and 0.1% formic acid (FA) as well as acetonitrile with 0.1% FA as mobile phases at a flow rate of 300μl/min. The MS/MS detection of all peptides was done simultaneously with a scheduled multiple reaction monitoring (MRM) method in the positive mode by monitoring in each case three mass transitions per proteospecific peptide and the internal standard. The assays were validated according to current bioanalytical guidelines with respect to specificity, linearity (0.25-50nM), within-day and between-day accuracy and precision, digestion efficiency as well as stability. Finally, the developed method was successfully applied to determine the CYP and UGT protein amount in human liver and intestinal microsomes. The method was shown to possess sufficient specificity, sensitivity, accuracy, precision and stability to quantify clinically relevant human CYP and UGT enzymes. Copyright © 2014 Elsevier B.V. All rights reserved.

In-line micro-matrix solid-phase dispersion extraction for simultaneous separation and extraction of Sudan dyes in different spices.

PubMed

Rajabi, Maryam; Sabzalian, Sedigheh; Barfi, Behruz; Arghavani-Beydokhti, Somayeh; Asghari, Alireza

2015-12-18

A novel, simple, fast, and miniaturized method, termed in-line micro-matrix solid-phase dispersion (in-line MMSPD), coupled with high performance liquid chromatography (HPLC) was developed for the simultaneous extraction and determination of Sudan dyes (i.e. Sudan I-IV, Sudan orange G, Sudan black B, and Sudan red G) with the aid of an experimental design strategy. In this method, a matrix solid-phase dispersion (MSPD) column including a suitable mixture of polar sorbents was inserted in the mobile phase pathway, and while the interfering compounds were retained, the analytes were eluted and entered into the analytical column. In this way, the extraction, elution, and separation of the analytes were performed sequentially. Under the optimal experimental conditions (including the amount of sample, 0.0426g; amount of dispersant phase, 0.0216g of florisil, 0.0227g of silica, 0.0141g of alumina; and blending time, 112s), the limits of detection (LODs), limits of quantification, linear dynamic ranges, and recoveries were obtained to be 0.3-15.3μgkg(-1), 1-50μgkg(-1), 50-28,000μgkg(-1), and 94.5-99.1%, respectively. The results obtained showed that determination of the selected Sudan dyes in food samples using an enough sensitive and a simple analytically validated method like in-line MMSPD may offer a suitable screening method, which could be useful for food analysis and adulteration. Copyright © 2015 Elsevier B.V. All rights reserved.

[Simultaneous determination of seven high risk pesticide residues in royal jelly by high performance liquid chromatography-tandem mass spectrometry].

PubMed

Li, Yinghong; Zhou, Ping; Xu, Quanhua; Zhao, Huan; Shao, Qiaoyun

2018-02-08

A method was developed for the simultaneous determination of seven high risk pesticides in the royal jelly, eg. tau-fluvalinate, triadimenol, coumaphos, haloxyfop, carbendazim, thiophanate-ethyl and thiophanate-methyl by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). First, the royal jelly samples were extracted with acetonitrile under alkaline conditions. After dehydration by anhydrous sodium sulfate, the extracts were enriched and purified through solid-phase extraction (SPE) with Oasis HLB cartridges. Finally, the pesticides were detected by HPLC-MS/MS method. The separation was carried out on a Venusil MP C18 column with gradient elution. Methanol (containing 0.1% (v/v) formic acid) and 0.5 mmol/L ammonium acetate aqueous solution (containing 0.1% (v/v) formic acid) were used as the mobile phases. The detection was achieved using electrospray ionization in positive ion (ESI + ) mode and multiple reaction monitoring (MRM) mode for data collection. Quantification was carried out using internal standard method. The results showed that the seven high risk pesticides were linear in the range of 5-100 μg/kg. The linear correlation coefficients ( r 2 ) were 0.9921-0.9996. The limits of detection (LODs) and limits of quantification (LOQs) of the seven high risk pesticides were 0.5-2.0 μg/kg and 1.0-5.0 μg/kg, respectively. The average recoveries at the three spiked levels were 80.5%-101.3%, and the relative standard deviations were 3.6%-9.4% ( n =3). This method is simple, effective and sensitive, and is suitable for the determination of the pesticide residues in royal jelly.

Development and validation of a hydrophilic interaction liquid chromatography-tandem mass spectrometry method for the quantification of lipid-related extracellular metabolites in Saccharomyces cerevisiae.

PubMed

Sun, Tao; Wetzel, Stephanie J; Johnson, Mitchell E; Surlow, Beth A; Patton-Vogt, Jana

2012-05-15

A highly sensitive hydrophilic interaction liquid chromatography-tandem mass spectrometry (HILIC-MS/MS) method was developed and validated for the quantification of glycerophosphoinositol (GroPIns), glycerophosphocholine (GroPCho), glycerol 3-phosphate (GroP), inositol, and choline in the extracellular medium of Saccharomyces cerevisiae. The media samples were pretreated with a single two-phase liquid extraction. Chromatographic separation was achieved on a Waters Xbridge HILIC (150 mm × 4.6 mm, 5 μm) column under isocratic conditions using a mobile phase composed of acetonitrile/water, 70:30 (v/v) with 10mM ammonium acetate (pH adjusted to 4.5) at a flow-rate of 0.5 mL/min. Using a triple quadrupole tandem mass spectrometer, samples were detected in multiple reaction monitoring (MRM) mode via an electrospray ionization (ESI) source. The calibration curves were linear (r² ≥ 0.995) over the range of 0.5-150 nM, with the lower limit of quantitation validated at 0.5 nM for all analytes. The intra- and inter-day precision (calculated by coefficient of variation, CV%) ranged from 1.24 to 5.88% and 2.46 to 9.77%, respectively, and intra- and inter-day accuracy (calculated by relative error, RE%) was between -8.42 to 8.22% and -9.35 to 6.62%, respectively, at all quality control levels. The extracellular metabolites were stable throughout various storage stability studies. The fully validated method was successfully applied to determine the extracellular levels of phospholipid-related metabolites in S. cerevisiae. Copyright © 2012 Elsevier B.V. All rights reserved.

Simultaneous quantification of T4, T3, rT3, 3,5-T2 and 3,3'-T2 in larval zebrafish (Danio rerio) as a model to study exposure to polychlorinated biphenyls.

PubMed

Chen, Xiaopeng; Walter, Kyla M; Miller, Galen W; Lein, Pamela J; Puschner, Birgit

2018-06-01

Environmental toxicants that interfere with thyroid hormone (TH) signaling can impact growth and development in animals and humans. Zebrafish represent a model to study chemically induced TH disruption, prompting the need for sensitive detection of THs. Simultaneous quantification of 3,3',5-triiodo-l-thyronine (T3), thyroxine (T4), 3,3',5'-triiodo-l-thyronine (rT3), 3,5-diiodo-l-thyronine (3,5-T2) and 3,3'-diiodo-l-thyronine (3,3'-T2) in zebrafish larvae was achieved by ultra-performance liquid chromatography-tandem mass spectrometry in positive ion mode. Solid-phase extraction with SampliQ cartridges and derivatization with 3 m hydrochloric acid in n-butanol reduced matrix effects. Derivatized compounds were separated on an Acquity UPLC BEH C 18 column with mobile phases consisting of 0.1% acetic acid in deionized water and 0.1% acetic acid in methanol. The limits of detection ranged from 0.5 to 0.6 pg injected on column. The method was validated by evaluating recovery (77.1-117.2%), accuracy (87.3-123.9%) and precision (0.5-12.4%) using diluted homogenized zebrafish embryos spiked with all target compounds. This method was then applied to zebrafish larvae collected after 114 h of exposure to polychlorinated biphenyls (PCBs), including PCB 28, PCB 66 and PCB 95, or the technical mixture Aroclor 1254. Exposure to PCB 28 and PCB 95 increased the T4:T3 ratio and decreased the T3:rT3 ratio, demonstrating that this method can effectively detect PCB-induced alterations in THs. Copyright © 2018 John Wiley & Sons, Ltd.

Analysis of oxcarbazepine and the 10-hydroxycarbazepine enantiomers in plasma by LC-MS/MS: application in a pharmacokinetic study.

PubMed

de Jesus Antunes, Natalicia; Wichert-Ana, Lauro; Coelho, Eduardo Barbosa; Della Pasqua, Oscar; Alexandre, Veriano; Takayanagui, Osvaldo Massaiti; Tozatto, Eduardo; Lanchote, Vera Lucia

2013-12-01

Oxcarbazepine is a second-generation antiepileptic drug indicated as monotherapy or adjunctive therapy in the treatment of partial seizures or generalized tonic-clonic seizures in adults and children. It undergoes rapid presystemic reduction with formation of the active metabolite 10-hydroxycarbazepine (MHD), which has a chiral center at position 10, with the enantiomers (S)-(+)- and R-(-)-MHD showing similar antiepileptic effects. This study presents the development and validation of a method of sequential analysis of oxcarbazepine and MHD enantiomers in plasma using liquid chromatography with tandem mass spectrometry (LC-MS/MS). Aliquots of 100 μL of plasma were extracted with a mixture of methyl tert-butyl ether: dichloromethane (2:1). The separation of oxcarbazepine and the MHD enantiomers was obtained on a chiral phase Chiralcel OD-H column, using a mixture of hexane:ethanol:isopropanol (80:15:5, v/v/v) as mobile phase at a flow rate of 1.3 mL/min with a split ratio of 1:5, and quantification was performed by LC-MS/MS. The limit of quantification was 12.5 ng oxcarbazepine and 31.25 ng of each MHD enantiomer/mL of plasma. The method was applied in the study of kinetic disposition of oxcarbazepine and the MHD enantiomers in the steady state after oral administration of 300 mg/12 h oxcarbazepine in a healthy volunteer. The maximum plasma concentration of oxcarbazepine was 1.2 µg/mL at 0.75 h. The kinetic disposition of MHD is enantioselective, with a higher proportion of the S-(+)-MHD enantiomer compared to R-(-)-MHD and an AUC(0-12) S-(+)/R-(-) ratio of 5.44. © 2013 Wiley Periodicals, Inc.

Development of a hydrophilic interaction liquid chromatography-mass spectrometry method for detection and quantification of urea thermal decomposition by-products in emission from diesel engine employing selective catalytic reduction technology.

PubMed

Yassine, Mahmoud M; Dabek-Zlotorzynska, Ewa; Celo, Valbona

2012-03-16

The use of urea based selective catalytic reduction (SCR) technology for the reduction of NOx from the exhaust of diesel-powered vehicles has the potential to emit at least six thermal decomposition by-products, ammonia, and unreacted urea from the tailpipe. These compounds may include: biuret, dicyandiamine, cyanuric acid, ammelide, ammeline and melamine. In the present study, a simple, sensitive and reliable hydrophilic interaction liquid chromatography (HILIC)-electrospray ionization (ESI)/mass spectrometry (MS) method without complex sample pre-treatment was developed for identification and determination of urea decomposition by-products in diesel exhaust. Gradient separation was performed on a SeQuant ZIC-HILIC column with a highly polar zwitterionic stationary phase, and using a mobile phase consisting of acetonitrile (eluent A) and 15 mM ammonium formate (pH 6; eluent B). Detection and quantification were performed using a quadrupole ESI/MS operated simultaneously in negative and positive mode. With 10 μL injection volume, LODs for all target analytes were in the range of 0.2-3 μg/L. The method showed a good inter-day precision of retention time (RSD<0.5%) and peak area (RSD<3%). Satisfactory extraction recoveries from spiked blanks ranged between 96 and 98%. Analyses of samples collected during transient chassis dynamometer tests of a bus engine equipped with a diesel particulate filter (DPF) and urea based SCR technology showed the presence of five target analytes with cyanuric acid and ammelide the most abundant compounds in the exhaust. Crown Copyright © 2012. Published by Elsevier B.V. All rights reserved.

Quantification of 4 antidepressants and a metabolite by LC-MS for therapeutic drug monitoring.

PubMed

Choong, Eva; Rudaz, Serge; Kottelat, Astrid; Haldemann, Sophie; Guillarme, Davy; Veuthey, Jean-Luc; Eap, Chin B

2011-06-01

A liquid chromatography method coupled to mass spectrometry was developed for the quantification of bupropion, its metabolite hydroxy-bupropion, moclobemide, reboxetine and trazodone in human plasma. The validation of the analytical procedure was assessed according to Société Française des Sciences et Techniques Pharmaceutiques and the latest Food and Drug Administration guidelines. The sample preparation was performed with 0.5 mL of plasma extracted on a cation-exchange solid phase 96-well plate. The separation was achieved in 14 min on a C18 XBridge column (2.1 mm×100 mm, 3.5 μm) using a 50 mM ammonium acetate pH 9/acetonitrile mobile phase in gradient mode. The compounds of interest were analysed in the single ion monitoring mode on a single quadrupole mass spectrometer working in positive electrospray ionisation mode. Two ions were selected per molecule to increase the number of identification points and to avoid as much as possible any false positives. Since selectivity is always a critical point for routine therapeutic drug monitoring, more than sixty common comedications for the psychiatric population were tested. For each analyte, the analytical procedure was validated to cover the common range of concentrations measured in plasma samples: 1-400 ng/mL for reboxetine and bupropion, 2-2000 ng/mL for hydroxy-bupropion, moclobemide, and trazodone. For all investigated compounds, reliable performance in terms of accuracy, precision, trueness, recovery, selectivity and stability was obtained. One year after its implementation in a routine process, this method demonstrated a high robustness with accurate values over the wide concentration range commonly observed among a psychiatric population. Copyright © 2011 Elsevier B.V. All rights reserved.

Development and validation of a UHPLC-MS/MS assay for colistin methanesulphonate (CMS) and colistin in human plasma and urine using weak-cation exchange solid-phase extraction.

PubMed

Zhao, Miao; Wu, Xiao-Jie; Fan, Ya-Xin; Guo, Bei-Ning; Zhang, Jing

2016-05-30

A rapid ultra high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) assay method was developed for determination of CMS and formed colistin in human plasma and urine. After extraction on a 96-well SPE Supra-Clean Weak Cation Exchange (WCX) plate, the eluents were mixed and injected into the UHPLC-MS/MS system directly. A Phonomenex Kinetex XB-C18 analytical column was employed with a mobile phase consisting of solution "A" (acetonitrile:methanol, 1:1, v/v) and solution "B" (0.1% formic acid in water, v/v). The flow rate was 0.4 mL/min with gradient elution over 3.5 min. Ions were detected in ESI positive ion mode and the precursor-product ion pairs were m/z 390.7/101.3 for colistin A, m/z 386.0/101.2 for colistin B, and m/z 402.3/101.2 for polymyxin B1 (IS), respectively. The lower limit of quantification (LLOQ) was 0.0130 and 0.0251 mg/L for colistin A and colistin B in both plasma and urine with accuracy (relative error, %) <± 12.6% and precision (relative standard deviation, %) <± 10.8%. Stability of CMS was demonstrated in biological samples before and during sample treatment, and in the extract. This new analytical method provides high-throughput treatment and optimized quantification of CMS and colistin, which offers a highly efficient tool for the analysis of a large number of clinical samples as well as routine therapeutic drug monitoring. Copyright © 2016 Elsevier B.V. All rights reserved.

Mathematical and Computational Foundations of Recurrence Quantifications

NASA Astrophysics Data System (ADS)

Marwan, Norbert; Webber, Charles L.

Real-world systems possess deterministic trajectories, phase singularities and noise. Dynamic trajectories have been studied in temporal and frequency domains, but these are linear approaches. Basic to the field of nonlinear dynamics is the representation of trajectories in phase space. A variety of nonlinear tools such as the Lyapunov exponent, Kolmogorov-Sinai entropy, correlation dimension, etc. have successfully characterized trajectories in phase space, provided the systems studied were stationary in time. Ubiquitous in nature, however, are systems that are nonlinear and nonstationary, existing in noisy environments all of which are assumption breaking to otherwise powerful linear tools. What has been unfolding over the last quarter of a century, however, is the timely discovery and practical demonstration that the recurrences of system trajectories in phase space can provide important clues to the system designs from which they derive. In this chapter we will introduce the basics of recurrence plots (RP) and their quantification analysis (RQA). We will begin by summarizing the concept of phase space reconstructions. Then we will provide the mathematical underpinnings of recurrence plots followed by the details of recurrence quantifications. Finally, we will discuss computational approaches that have been implemented to make recurrence strategies feasible and useful. As computers become faster and computer languages advance, younger generations of researchers will be stimulated and encouraged to capture nonlinear recurrence patterns and quantification in even better formats. This particular branch of nonlinear dynamics remains wide open for the definition of new recurrence variables and new applications untouched to date.

Quantitation of triacylglycerols in edible oils by off-line comprehensive two-dimensional liquid chromatography-atmospheric pressure chemical ionization mass spectrometry using a single column.

PubMed

Wei, Fang; Hu, Na; Lv, Xin; Dong, Xu-Yan; Chen, Hong

2015-07-24

In this investigation, off-line comprehensive two-dimensional liquid chromatography-atmospheric pressure chemical ionization mass spectrometry using a single column has been applied for the identification and quantification of triacylglycerols in edible oils. A novel mixed-mode phenyl-hexyl chromatographic column was employed in this off-line two-dimensional separation system. The phenyl-hexyl column combined the features of traditional C18 and silver-ion columns, which could provide hydrophobic interactions with triacylglycerols under acetonitrile conditions and can offer π-π interactions with triacylglycerols under methanol conditions. When compared with traditional off-line comprehensive two-dimensional liquid chromatography employing two different chromatographic columns (C18 and silver-ion column) and using elution solvents comprised of two phases (reversed-phase/normal-phase) for triacylglycerols separation, the novel off-line comprehensive two-dimensional liquid chromatography using a single column can be achieved by simply altering the mobile phase between acetonitrile and methanol, which exhibited a much higher selectivity for the separation of triacylglycerols with great efficiency and rapid speed. In addition, an approach based on the use of response factor with atmospheric pressure chemical ionization mass spectrometry has been developed for triacylglycerols quantification. Due to the differences between saturated and unsaturated acyl chains, the use of response factors significantly improves the quantitation of triacylglycerols. This two-dimensional liquid chromatography-mass spectrometry system was successfully applied for the profiling of triacylglycerols in soybean oils, peanut oils and lord oils. A total of 68 triacylglycerols including 40 triacylglycerols in soybean oils, 50 triacylglycerols in peanut oils and 44 triacylglycerols in lord oils have been identified and quantified. The liquid chromatography-mass spectrometry data were analyzed using principal component analysis. The results of the principal component analysis enabled a clear identification of different plant oils. By using this two-dimensional liquid chromatography-mass spectrometry system coupled with principal component analysis, adulterated soybean oils with 5% added lord oil and peanut oils with 5% added soybean oil can be clearly identified. Copyright © 2015 Elsevier B.V. All rights reserved.

An efficient analytical method for determination of S-phenylmercapturic acid in urine by HPLC fluorimetric detector to assessing benzene exposure.

PubMed

Mendes, Michele P Rocha; Silveira, Josianne Nicácio; Andre, Leiliane Coelho

2017-09-15

Benzene is an important occupational and environmental contaminant, naturally present in petroleum and as by-product in the steel industry. Toxicological studies showed pronounced myelotoxic action, causing leukemic and others blood cells disorders. Assessing of benzene exposure is performed by biomarkers as trans, trans-muconic acid (AttM) and S-phenylmercapturic acid (S-PMA) in urine. Due to specificity of S-PMA, this biomarker has been proposed to asses lower levels of benzene in air. The aim of this study was to validate an analytical method for the quantification of S-PMA by High-Performance Liquid Chromatography with fluorometric detector. The development of an analytical method of S-PMA in urine was carried out by solid phase extraction (SPE) using C-18 phase. The eluated were submitted to water bath at 75°C and nitrogen to analyte concentration, followed by alkaline hydrolysis and derivatization with monobromobimane. The chromatography conditions were reverse phase C-18 column (240mm, 4mm and 5μm) at 35°C; acetonitrile and 0.5% acetic acid (50:50) as mobile phase with a flow of 0.8mL/min. The limits of detection and quantification were 0.22μg/L and 0.68μg/L, respectively. The linearity was verified by simple linear regression, and the method exhibited good linearity in the range of 10-100μg/L. There was no matrix effect for S-PMA using concentrations of 40, 60, 80 and 100μg/L. The intra- and interassay precision showed coefficient of variation of less than 10% and the recovery ranged from 83.4 to 102.8% with an average of 94.4%. The stability of S-PMA in urine stored at -20°C was of seven weeks. The conclusion is that this method presents satisfactory results per their figures of merit. This proposed method for determining urinary S-PMA showed adequate sensitivity for assessment of occupational and environmental exposure to benzene using S-PMA as biomarker of exposure. Copyright © 2017 Elsevier B.V. All rights reserved.

77 FR 32092 - Mobility Fund Phase I Auction Scheduled for September 27, 2012; Notice and Filing Requirements...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-05-31

... Mobility Fund Phase I support they seek, including any agreements relating to post-auction market structure... FEDERAL COMMUNICATIONS COMMISSION [AU Docket No. 12-25; DA 12-641 and DA 12-721] Mobility Fund... million in one-time Mobility Fund Phase I support scheduled to commence on September 27, 2012. The Bureaus...

Addressing Phase Errors in Fat-Water Imaging Using a Mixed Magnitude/Complex Fitting Method

PubMed Central

Hernando, D.; Hines, C. D. G.; Yu, H.; Reeder, S.B.

2012-01-01

Accurate, noninvasive measurements of liver fat content are needed for the early diagnosis and quantitative staging of nonalcoholic fatty liver disease. Chemical shift-based fat quantification methods acquire images at multiple echo times using a multiecho spoiled gradient echo sequence, and provide fat fraction measurements through postprocessing. However, phase errors, such as those caused by eddy currents, can adversely affect fat quantification. These phase errors are typically most significant at the first echo of the echo train, and introduce bias in complex-based fat quantification techniques. These errors can be overcome using a magnitude-based technique (where the phase of all echoes is discarded), but at the cost of significantly degraded signal-to-noise ratio, particularly for certain choices of echo time combinations. In this work, we develop a reconstruction method that overcomes these phase errors without the signal-to-noise ratio penalty incurred by magnitude fitting. This method discards the phase of the first echo (which is often corrupted) while maintaining the phase of the remaining echoes (where phase is unaltered). We test the proposed method on 104 patient liver datasets (from 52 patients, each scanned twice), where the fat fraction measurements are compared to coregistered spectroscopy measurements. We demonstrate that mixed fitting is able to provide accurate fat fraction measurements with high signal-to-noise ratio and low bias over a wide choice of echo combinations. PMID:21713978

Combined effects of mobile phase composition and temperature on the retention of phenolic antioxidants on an octylsilica polydentate column.

PubMed

Jandera, Pavel; Vyňuchalová, Kateřina; Nečilová, Kateřina

2013-11-22

Combined effects of temperature and mobile-phase composition on retention and separation selectivity of phenolic acids and flavonoid compounds were studied in liquid chromatography on a polydentate Blaze C8 silica based column. The temperature effects on the retention can be described by van't Hoff equation. Good linearity of lnk versus 1/T graphs indicates that the retention is controlled by a single mechanism in the mobile phase and temperature range studied. Enthalpic and entropic contributions to the retention were calculated from the regression lines. Generally, enthalpic contributions control the retention at lower temperatures and in mobile phases with lower concentrations of methanol in water. Semi-empirical retention models describe the simultaneous effects of temperature and the volume fraction of the organic solvent in the mobile phase. Using the linear free energy-retention model, selective dipolarity/polarizability, hydrogen-bond donor, hydrogen-bond acceptor and molecular size contributions to retention were estimated at various mobile phase compositions and temperatures. In addition to mobile phase gradients, temperature programming can be used to reduce separation times. Copyright © 2013 Elsevier B.V. All rights reserved.

Hydrophilic interaction liquid chromatography/positive ion electrospray ionization mass spectrometry method for the quantification of alprazolam and α-hydroxy-alprazolam in human plasma.

PubMed

Kalogria, Eleni; Pistos, Constantinos; Panderi, Irene

2013-12-30

A hydrophilic interaction liquid chromatography/positive ion electrospray-mass spectrometry (HILIC-ESI/MS) has been developed and fully validated for the quantification of alprazolam and its main metabolite, α-hydroxy-alprazolam, in human plasma. The assay is based on 50μL plasma samples, following liquid-liquid extraction. All analytes and the internal standard (tiamulin) were separated by hydrophilic interaction liquid chromatography using an X-Bridge-HILIC analytical column (150.0mm×2.1mm i.d., particle size 3.5μm) under isoscratic elution. The mobile phase was composed of a 7% 10mM ammonium formate water solution in acetonitrile and pumped at a flow rate of 0.20mLmin(-1). Running in positive electrospray ionization and selected ion monitoring (SIM) the mass spectrometer was set to analyze the protonated molecules [M+H](+) at m/z 309, 325 and 494 for alprazolam, α-hydroxy-alprazolam and tiamulin (ISTD) respectively. The assay was linear over the concentration range of 2.5-250ngmL(-1) for alprazolam and 2.5-50ngmL(-1) for α-hydroxy alprazolam. Intermediate precision was less than 4.1% over the tested concentration ranges. The method is the first reported application of HILIC in the analysis benzodiazepines in human plasma. With a small sample size (50μL human plasma) and a run time less than 10.0min for each sample the method can be used to support a wide range of clinical studies concerning alprazolam quantification. Copyright © 2013 Elsevier B.V. All rights reserved.

Simultaneous determination of chromones and coumarins in Radix Saposhnikoviae by high performance liquid chromatography with diode array and tandem mass detectors.

PubMed

Kim, Min Kyung; Yang, Dong-Hyug; Jung, Mihye; Jung, Eun Ha; Eom, Han Young; Suh, Joon Hyuk; Min, Jung Won; Kim, Unyong; Min, Hyeyoung; Kim, Jinwoong; Han, Sang Beom

2011-09-16

Methods using high performance liquid chromatography with diode array detection (HPLC-DAD) and tandem mass spectrometry (HPLC-MS/MS) were developed and validated for the simultaneous determination of 5 chromones and 6 coumarins: prim-O-glucosylcimifugin (1), cimifugin (2), nodakenin (3), 4'-O-β-d-glucosyl-5-O-methylvisamminol (4), sec-O-glucosylhamaudol (5), psoralen (6), bergapten (7), imperatorin (8), phellopterin (9), 3'-O-angeloylhamaudol (10) and anomalin (11), in Radix Saposhnikoviae. The separation conditions for HPLC-DAD were optimized using an Ascentis Express C18 (4.6 mm×100 mm, 2.7 μm particle size) fused-core column. The mobile phase was composed of 10% aqueous acetonitrile (A) and 90% acetonitrile (B) and the elution was performed under a gradient mode at a flow rate of 1.0 mL/min. The detection wavelength was set at 300 nm. The HPLC-DAD method yielded a base line separation of the 11 components in 50% methanol extract of Radix Saposhnikoviae with no interfering peaks detected. The HPLC-DAD method was validated in terms of linearity, accuracy and precision (intra- and inter-day), limit of quantification (LOQ), recovery, and robustness. Specific determination of the 11 components was also accomplished by a triple quadrupole tandem mass spectrometer equipped with an electrospray ionization (ESI) source. This HPLC-MS/MS method was also validated by determining the linearity, limit of quantification, accuracy, and precision. Quantification of the 11 components in 51 commercial Radix Saposhnikoviae samples was successfully performed using the developed HPLC-DAD method. The identity, batch-to-batch consistency, and authenticity of Radix Saposhnikoviae were successfully monitored by the proposed HPLC-DAD and HPLC-MS/MS methods. Copyright © 2011 Elsevier B.V. All rights reserved.

A simple and sensitive liquid chromatography-tandem mass spectrometry method for trans-ε-viniferin quantification in mouse plasma and its application to a pharmacokinetic study in mice.

PubMed

Kim, Jiseon; Min, Jee Sun; Kim, Doyun; Zheng, Yu Fen; Mailar, Karabasappa; Choi, Won Jun; Lee, Choongho; Bae, Soo Kyung

2017-02-05

In this study, a simple and sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the quantification of trans-ε-viniferin in small volumes (10μl) of mouse plasma using chlorpropamide as an internal standard was developed and validated. Plasma samples were precipitated with acetonitrile and separated using an Eclipse Plus C 18 column (100×4.6mm, 1.8-μm) with a mobile phase consisting of 0.1% formic acid in acetonitrile and 0.1% formic acid in water (60:40v/v) at a flow rate of 0.5ml/min. A triple quadrupole mass spectrometer operating in positive ion mode with selected reaction-monitoring mode was used to determine trans-ε-viniferin and chlorpropamide transitions of 455.10→215.05 and 277.00→111.00, respectively. The lower limit of quantification was 5ng/ml with a linear range of 5-2500ng/ml (r≥0.9949). All validation data, including the selectivity, precision, accuracy, recovery, dilution integrity, and stability, conformed to the acceptance requirements. No matrix effects were observed. The developed method was successfully applied to pharmacokinetic studies of trans-ε-viniferin following intravenous (2.5mg/kg), intraperitoneal (2.5, 5 and 10mg/kg), and oral (40mg/kg) administration in mice. This is the first report on the pharmacokinetic properties of trans-ε-viniferin. The results provide a meaningful basis for evaluating the pre-clinical or clinical applications of trans-ε-viniferin. Copyright © 2016 Elsevier B.V. All rights reserved.

Therapeutic drug monitoring of carbamazepine and its metabolite in children from dried blood spots using liquid chromatography and tandem mass spectrometry.

PubMed

Shokry, Engy; Villanelli, Fabio; Malvagia, Sabrina; Rosati, Anna; Forni, Giulia; Funghini, Silvia; Ombrone, Daniela; Della Bona, Maria; Guerrini, Renzo; la Marca, Giancarlo

2015-05-10

Carbamazepine (CBZ) is a first-line drug for the treatment of different forms of epilepsy and the first choice drug for trigeminal neuralgia. CBZ is metabolized in the liver by oxidation into carbamazepine-10,11-epoxide (CBZE), its major metabolite which is equipotent and known to contribute to the pharmacological activity of CBZ. The aim of the present study was to develop and validate a reliable, selective and sensitive liquid chromatography-tandem mass spectrometry method for the simultaneous quantification of CBZ and its active metabolite in dried blood spots (DBS). The extraction process was carried out from DBS using methanol-water-formic acid (80:20:0.1, v/v/v). Chromatographic elution was achieved by using a linear gradient with a mobile phase consisting of acetonitrile-water-0.1% formic acid at a flow rate of 0.50mL/min. The method was linear over the range 1-40mg/L and 0.25-20mg/L for CBZ and CBZE, respectively. The limit of quantification was 0.75mg/L and 0.25mg/L for CBZ and CBZE. Intra-day and inter-day assay precisions were found to be lower than 5.13%, 6.46% and 11.76%, 4.72% with mean percentage accuracies of 102.1%, 97.5% and 99.2%, 97.8% for CBZ and CBZE. We successfully applied the method for determining DBS finger-prick samples in paediatric patients and confirmed the results with concentrations measured in matched plasma samples. This novel approach allows quantification of CBZ and its metabolite from only one 3.2mm DBS disc by LC-MS/MS thus combining advantages of DBS technique and LC-MS/MS in clinical practice. Copyright © 2015 Elsevier B.V. All rights reserved.

A novel LC-MS/MS method for the simultaneous quantification of topiramate and its main metabolites in human plasma.

PubMed

Milosheska, Daniela; Roškar, Robert

2017-05-10

The aim of the present report was to develop and validate simple, sensitive and reliable LC-MS/MS method for quantification of topiramate (TPM) and its main metabolites: 2,3-desisopropylidene TPM, 4,5-desisopropylidene TPM, 10-OH TPM and 9-OH TPM in human plasma samples. The most abundant metabolite 2,3-desisopropylidene TPM was isolated from patients urine, characterized and afterwards used as an authentic standard for method development and validation. Sample preparation method employs 100μL of plasma sample and liquid-liquid extraction with a mixture of ethyl acetate and diethyl ether as extraction solvent. Chromatographic separation was achieved on a 1290 Infinity UHPLC coupled to 6460 Triple Quad Mass Spectrometer operated in negative MRM mode using Kinetex C18 column (50×2.1mm, 2.6μm) by gradient elution using water and methanol as a mobile phase and stable isotope labeled TPM as internal standard. The method showed to be selective, accurate, precise and linear over the concentration ranges of 0.10-20μg/mL for TPM, 0.01-2.0μg/mL for 2,3-desisopropylidene TPM, and 0.001-0.200μg/mL for 4,5-desisopropylidene TPM, 10-OH TPM and 9-OH TPM. The described method is the first fully validated method capable of simultaneous determination of TPM and its main metabolites in plasma over the selected analytical range. The suitability of the method was successfully demonstrated by the quantification of all analytes in plasma samples of patients with epilepsy and can be considered as reliable analytical tool for future investigations of the TPM metabolism. Copyright © 2017 Elsevier B.V. All rights reserved.

Direct analysis of ethylene glycol in human serum on the basis of analyte adduct formation and liquid chromatography-tandem mass spectrometry.

PubMed

Dziadosz, Marek

2018-01-01

The aim of this work was to develop a fast, cost-effective and time-saving liquid chromatography-tandem mass spectrometry (LC-MS/MS) analytical method for the analysis of ethylene glycol (EG) in human serum. For these purposes, the formation/fragmentation of an EG adduct ion with sodium and sodium acetate was applied in the positive electrospray mode for signal detection. Adduct identification was performed with appropriate infusion experiments based on analyte solutions prepared in different concentrations. Corresponding analyte adduct ions and adduct ion fragments could be identified both for EG and the deuterated internal standard (EG-D4). Protein precipitation was used as sample preparation. The analysis of the supernatant was performed with a Luna 5μm C18 (2) 100A, 150mm×2mm analytical column and a mobile phase consisting of 95% A (H 2 O/methanol=95/5, v/v) and 5% B (H 2 O/methanol=3/97, v/v), both with 10mmolL -1 ammonium acetate and 0.1% acetic acid. Method linearity was examined in the range of 100-4000μg/mL and the calculated limit of detection/quantification was 35/98μg/mL. However, on the basis of the signal to noise ratio, quantification was recommended at a limit of 300μg/mL. Additionally, the examined precision, accuracy, stability, selectivity and matrix effect demonstrated that the method is a practicable alternative for EG quantification in human serum. In comparison to other methods based on liquid chromatography, the strategy presented made for the first time the EG analysis without analyte derivatisation possible. Copyright © 2017 Elsevier B.V. All rights reserved.

Quantification of aesculin in rabbit plasma and ocular tissues by high performance liquid chromatography using fluorescent detection: application to a pharmacokinetic study.

PubMed

Chen, QiuHong; Zeng, Ying; Kuang, JianChao; Li, Ye; Li, XiaoHui; Zheng, Yu; Hou, Hua; Hou, ShiXiang

2011-04-28

A simple and sensitive high performance liquid chromatography method with fluorescence detection (HPLC-FD) was described for the determination of aesculin (AL) at low concentrations in rabbit plasma and ocular tissues. After deproteinization by methanol using pazufloxacin mesilate (PM) as an internal standard (I.S.), supernatants were evaporated to dryness at 40°C under a gentle stream of nitrogen. The residue was reconstituted in mobile phase and a volume of 20μL was injected into the HPLC for analysis. Analytes were separated on an Ultimate XB-C18 column (250mm × 4.6mm i.d., 5μm particle size) and protected by a ODS guard column (10mm × 4.0mm i.d., 5μm particle size), using acetonitrile-0.1% triethylamine in water (adjusted to pH 3.0 using phosphoric acid) (12:88, v/v) as mobile phase with a flow rate of 1.0mL/min. The wavelengths of fluorescence detector (FD) were set at 344nm for excitation and 466nm for emission. The lower limit of quantitation (LOQ) for AL was 0.80ng/mL for plasma and vitreous body, 1.59ng/mL for aqueous humor, and 6.55ng/g for iris and 1.66ng/g for retina. The method was used in the study of AL concentrations in plasma and ocular tissues after topical administration of AL eye drops. Crown Copyright © 2011. Published by Elsevier B.V. All rights reserved.

Collision Cross Section (CCS) Database: An Additional Measure to Characterize Steroids.

PubMed

Hernández-Mesa, Maykel; Le Bizec, Bruno; Monteau, Fabrice; García-Campaña, Ana M; Dervilly-Pinel, Gaud

2018-04-03

Ion mobility spectrometry enhances the performance characteristics of liquid chromatography-mass spectrometry workflows intended to steroid profiling by providing a new separation dimension and a novel characterization parameter, the so-called collision cross section (CCS). This work proposes the first CCS database for 300 steroids (i.e., endogenous, including phase I and phase II metabolites, and exogenous synthetic compounds), which involves 1080 ions and covers the CCS of 127 androgens, 84 estrogens, 50 corticosteroids, and 39 progestagens. This large database provides information related to all the ionized species identified for each steroid in positive electrospray ionization mode as well as for estrogens in negative ionization mode. CCS values have been measured using nitrogen as drift gas in the ion mobility cell. Generally, direct correlation exists between mass-to-charge ratio ( m/ z) and CCS because both are related parameters. However, several steroids mainly steroid glucuronides and steroid esters have been characterized as more compact or elongated molecules than expected. In such cases, CCS results in additional relevant information to retention time and mass spectral data for the identification of steroids. Moreover, several isomeric steroid pairs (e.g., 5β-androstane-3,17-dione and 5α-androstane-3,17-dione) have been separated based on their CCS differences. These results indicate that adding the CCS to databases in analytical workflows increases selectivity, thus improving the confidence in steroids analysis. Consequences in terms of identification and quantification are discussed. Quality criteria and a construction of an interlaboratory reproducibility approach are also reported for the obtained CCS values. The CCS database described here is made publicly available.

Halloysite nanotubes-titanium dioxide as a solid-phase microextraction coating combined with negative corona discharge-ion mobility spectrometry for the determination of parathion.

PubMed

Saraji, Mohammad; Jafari, Mohammad Taghi; Mossaddegh, Mehdi

2016-07-05

Halloysite nanotubes-titanium dioxide (HNTs-TiO2) as a biocompatible environmentally friendly solid-phase microextraction (SPME) fiber coating was prepared. HNTs-TiO2 was chemically coated on the surface of a fused-silica fiber using a sol-gel process. Parathion as an organophosphorus pesticide was selected as a model compound to investigate the extraction efficiency of the fiber. The extracted analyte was detected by negative corona discharge-ion mobility spectrometer (NCD-IMS). The effective parameters on the extraction efficiency, such as salt effect, extraction temperature and extraction time were investigated and optimized. The extraction efficiency of HNTs-TiO2 fiber was compared with bare-silica (sol-gel based coating without HNTs-TiO2), HNTs, carbon nanotubes and commercial SPME fibers (PA, PDMS, and PDMS-DVB). The HNTs-TiO2 fiber showed highest extraction efficiency among the studied fibers. The intra- and inter-day relative standard deviations were found to be 4.3 and 6.3%, respectively. The limit of detection and limit of quantification values were 0.03 and 0.1 μg L(-1), respectively. The dynamic range of the method was in the range of 0.1-25 μg L(-1). The spiking recoveries were between 85 (±9) and 97 (±6). The SPME-HNTs-TiO2 combined with NCD-IMS was successfully applied for the determination of parathion in apple, strawberry, celery and water samples. Copyright © 2016 Elsevier B.V. All rights reserved.

Simultaneous determination of 22 phthalate esters in polystyrene food-contact materials by ultra performance convergence chromatography with tandem mass spectrometry.

PubMed

Fan, Ying-Li; Ma, Ming; Cui, He-Zhen; Liu, Shu; Yang, Min-Li; Hou, Xiu-Feng

2018-05-29

A method for the determination of 22 phthalate esters in polystyrene food-contact materials has been established using ultra performance convergence chromatography with tandem mass spectrometry. In this method, 22 phthalate esters were analyzed in less than 3.5 min on an ACQUITY Tours 1-AA column by gradient elution. The mobile phase, the compensation solvent, the flow rate of mobile phase, column temperature and automatic back pressure regulator pressure were optimized, respectively. There was a good linearity of 20 phthalate esters with a range of 0.05-10 mg/L, diisodecyl phthalate and diisononyl phthalate were 0.25-10 mg/L, and the correlation coefficients of all phthalates were higher than 0.99 and those of 16 phthalates were higher than 0.999. The limits of detection and the limits of quantification of 15 phthalates were 0.02 and 0.05 mg/kg, meanwhile diallyl phthalate, diisobutyl phthalate, dimethyl phthalate, di-n-butyl phthalate and di(2-ethylhexyl) phthalate were 0.05 and 0.10 mg/kg, diisodecyl phthalate and diisononyl phthalate were 0.10 and 0.25 mg/kg. The spiked recoveries were 76.26-107.76%, and the relative standard deviations were 1.78-12.10%. Results support this method as an efficient alternative to apply for the simultaneous determination of 22 phthalate esters in common polystyrene food-contact materials. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Headspace solid-phase microextraction and gas chromatographic analysis of low-molecular-weight sulfur volatiles with pulsed flame photometric detection and quantification by a stable isotope dilution assay.

PubMed

Ullrich, Sebastian; Neef, Sylvia K; Schmarr, Hans-Georg

2018-02-01

Low-molecular-weight volatile sulfur compounds such as thiols, sulfides, disulfides as well as thioacetates cause a sulfidic off-flavor in wines even at low concentration levels. The proposed analytical method for quantification of these compounds in wine is based on headspace solid-phase microextraction, followed by gas chromatographic analysis with sulfur-specific detection using a pulsed flame photometric detector. Robust quantification was achieved via a stable isotope dilution assay using commercial and synthesized deuterated isotopic standards. The necessary chromatographic separation of analytes and isotopic standards benefits from the inverse isotope effect realized on an apolar polydimethylsiloxane stationary phase of increased film thickness. Interferences with sulfur-specific detection in wine caused by sulfur dioxide were minimized by addition of propanal. The method provides adequate validation data, with good repeatability and limits of detection and quantification. It suits the requirements of wine quality management, allowing the control of oenological treatments to counteract an eventual formation of excessively high concentration of such malodorous compounds. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Person-generated Data in Self-quantification. A Health Informatics Research Program.

PubMed

Gray, Kathleen; Martin-Sanchez, Fernando J; Lopez-Campos, Guillermo H; Almalki, Manal; Merolli, Mark

2017-01-09

The availability of internet-connected mobile, wearable and ambient consumer technologies, direct-to-consumer e-services and peer-to-peer social media sites far outstrips evidence about the efficiency, effectiveness and efficacy of using them in healthcare applications. The aim of this paper is to describe one approach to build a program of health informatics research, so as to generate rich and robust evidence about health data and information processing in self-quantification and associated healthcare and health outcomes. The paper summarises relevant health informatics research approaches in the literature and presents an example of developing a program of research in the Health and Biomedical Informatics Centre (HaBIC) at the University of Melbourne. The paper describes this program in terms of research infrastructure, conceptual models, research design, research reporting and knowledge sharing. The paper identifies key outcomes from integrative and multiple-angle approaches to investigating the management of information and data generated by use of this Centre's collection of wearable, mobiles and other devices in health self-monitoring experiments. These research results offer lessons for consumers, developers, clinical practitioners and biomedical and health informatics researchers. Health informatics is increasingly called upon to make sense of emerging self-quantification and other digital health phenomena that are well beyond the conventions of healthcare in which the field of informatics originated and consolidated. To make a substantial contribution to optimise the aims, processes and outcomes of health self-quantification needs further work at scale in multi-centre collaborations for this Centre and for health informatics researchers generally.

Rapid determination of benzodiazepines, zolpidem and their metabolites in urine using direct injection liquid chromatography-tandem mass spectrometry.

PubMed

Jeong, Yu-Dong; Kim, Min Kyung; Suh, Sung Ill; In, Moon Kyo; Kim, Jin Young; Paeng, Ki-Jung

2015-12-01

Benzodiazepines and zolpidem are generally prescribed as sedative, hypnotics, anxiolytics or anticonvulsants. These drugs, however, are frequently misused in drug-facilitated crime. Therefore, a rapid and simple liquid chromatography-tandem mass spectrometric (LC-MS/MS) method was developed for identification and quantification of benzodiazepines, zolpidem and their metabolites in urine using deuterium labeled internal standards (IS). Urine samples (120 μL) mixed with 80 μL of the IS solution were centrifuged. An aliquot (5 μL) of the sample solution was directly injected into the LC-MS/MS system for analysis. The mobile phases consisted of water and acetonitrile containing 2mM ammonium trifluoroacetate and 0.2% acetic acid. The analytical column was a Zorbax SB-C18 (100 mm × 2.1 mm i.d., 3.5 μm, Agilent). The separation and detection of 18 analytes were achieved within 10 min. Calibration curves were linear over the concentration ranges of 0.5-20 ng/mL (zolpidem), 1.0-40 ng/mL (flurazepam and temazepam), 2.5-100 ng/mL (7-aminoclonazepam, 1-hydroxymidazolam, midazolam, flunitrazepam and alprazolam), 5.0-200 ng/mL (zolpidem phenyl-4-carboxylic acid, α-hydroxyalprazolam, oxazepam, nordiazepam, triazolam, diazepam and α-hydroxytriazolam), 10-400 ng/mL (lorazepam and desalkylflurazepam) and 10-100 ng/mL (N-desmethylflunitrazepam) with the coefficients of determination (r(2)) above 0.9971. The dilution integrity of the analytes was examined for supplementation of short linear range. Dilution precision and accuracy were tested using two, four and ten-folds dilutions and they ranged from 3.7 to 14.4% and -12.8 to 12.5%, respectively. The process efficiency for this method was 63.0-104.6%. Intra- and inter-day precisions were less than 11.8% and 9.1%, while intra- and inter-day accuracies were less than -10.0 to 8.2%, respectively. The lower limits of quantification were lower than 10 ng/mL for each analyte. The applicability of the developed method was successfully verified with human urine samples from drug users (n=21). Direct urine sample injection and optimized mobile phases were introduced for simple sample preparation and high-sensitivity with the desired separation. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Validated stability-indicating HPLC method for the determination of pridinol mesylate. Kinetics study of its degradation in acid medium.

PubMed

Bianchini, Romina M; Castellano, Patricia M; Kaufman, Teodoro S

2008-12-01

The stability of pridinol mesylate (PRI) was investigated under different stress conditions, including hydrolytic, oxidative, photolytic and thermal, as recommended by the ICH guidelines. Relevant degradation was found to take place under acidic (0.1N HCl) and photolytic (visible and long-wavelength UV-light) conditions, both yielding the product resulting from water elimination (ELI), while submission to an oxidizing environment gave the N-oxidation derivative (NOX). The standards of these degradation products were synthesized and characterized by IR, (1)H and (13)C NMR spectroscopy. A simple, sensitive and specific HPLC method was developed for the quantification of PRI, ELI and NOX in bulk drug, and the conditions were optimized by means of a statistical design strategy. The separation employs a C(18) column and a 51:9:40 (v/v/v) mixture of MeOH, 2-propanol and potassium phosphate solution (50mM, pH 6.0), as mobile phase, delivered at 1.0 ml min(-1); the analytes were detected and quantified at 220 nm. The method was validated, demonstrating to be accurate and precise (repeatability and intermediate precision levels) within the corresponding linear ranges of PRI (0.1-1.5 mg ml(-1); r=0.9983, n=18) and both impurities (0.1-1.3% relative to PRI, r=0.9996 and 0.9995 for ELI and NOX, respectively, n=18). Robustness against small modifications of pH and percentage of the aqueous mobile phase was ascertained and the limits of quantification of the analytes were also determined (0.4 and 0.5 microg ml(-1); 0.04% and 0.05% relative to PRI for ELI and NOX, respectively). Peak purity indices (>0.9997), obtained with the aid of diode-array detection, and satisfactory resolution (R(s)>2.0) between PRI and its impurities established the specificity of the determination, all these results proving the stability-indicating capability of the method. The kinetics of the degradation of PRI in acid medium was also studied, determining that this is a first-order process with regards to drug concentration, with an activation energy of 25.5 Kcal mol(-1) and a t(1/2)=10,830 h, in 0.1N HCl at 38 degrees C.

Charge carrier mobility in a two-phase disordered organic system in the low-carrier concentration regime

NASA Astrophysics Data System (ADS)

Woellner, Cristiano F.; Li, Zi; Freire, José A.; Lu, Gang; Nguyen, Thuc-Quyen

2013-09-01

In this paper we use a three-dimensional Pauli master equation to investigate the charge carrier mobility of a two-phase system which can mimic donor-acceptor and amorphous-crystalline bulk heterojunctions. By taking the energetic disorder of each phase, their energy offset, and domain morphology into consideration, we show that the carrier mobility can have a completely different behavior when compared to a one-phase system. When the energy offset is equal to zero, the mobility is controlled by the more disordered phase. When the energy offset is nonzero, we show that the mobility electric field dependence switches from negative to positive at a threshold field proportional to the energy offset. Additionally, the influence of morphology, through the domain size and volume ratio parameters, on the transport is investigated and an approximate analytical expression for the zero field mobility is provided.

MEASUREMENT OF LOW LEVEL AIR TOXICS WITH MODIFIED UV DOAS

EPA Science Inventory

To further understand near source impacts, EPA is working to develop open-path optical techniques for spatiotemporal-resolved measurement of air pollutants. Of particular interest is near real time quantification of mobile-source generated CO, Nox and hydrocarbons measured in cl...

Simultaneous quantification of five steroid saponins from Dioscorea zingiberensis C.H.Wright in rat plasma by HPLC-MS/MS and its application to the pharmacokinetic studies

PubMed Central

Zhang, Xinxin; Li, Jing; Ito, Yoichiro; Sun, Wenji

2014-01-01

A simple, reliable and sensitive high-performance liquid chromatography tandem mass spectrometry method (HPLC-MS/MS) was established for simultaneous analyses of the following 5 steroid saponins in rat plasma after the single dose administration of total steroid saponins extracted from the rhizome of Dioscorea zingiberensis C.H.Wright for the first time. Protodioscin, huangjiangsu A, zingiberensis new saponin, dioscin, and gracillin were quantified using ginsenoside Rb1 as the internal standard (IS). The plasma samples were pretreated by a single step acetonitrile-mediated protein precipitation. The chromatographic separation was performed on an Inersil ODS-3 C18 column (250 mm × 4.6 mm, 5 μm) with the mobile phase composed of acetonitrile and water containing 0.1% formic acid under a gradient elution mode at 0.2 mL min−1 using a microsplit after the eluent from the HPLC apparatus. The quantification was accomplished on a triple quadrupole tandem mass spectrometer using the multiple reaction monitoring (MRM) in the positive ionization mode. The above five analytes were stable under sample storage and preparation conditions applied in the present study. The linearity, precision, accuracy, and recoveries of the analysis confirmed the requirements for quality-control purposes. After validation, this proposed method was successfully adopted to investigate the pharmacokinetic parameters of these five analytes. PMID:25201262

Identification, Characterization, and Quantification of Impurities of Safinamide Mesilate: Process-Related Impurities and Degradation Products.

PubMed

Zou, Liang; Sun, Lili; Zhang, Hui; Hui, Wenkai; Zou, Qiaogen; Zhu, Zheying

2017-07-01

The characterization of process-related impurities and degradation products of safinamide mesilate (SAFM) in bulk drug and a stability-indicating HPLC method for the separation and quantification of all the impurities were investigated. Four process-related impurities (Imp-B, Imp-C, Imp-D, and Imp-E) were found in the SAFM bulk drug. Five degradation products (Imp-A, Imp-C, Imp-D, Imp-E, and Imp-F) were observed in SAFM under oxidative conditions. Imp-C, Imp-D, and Imp-E were also degradation products and process-related impurities. Remarkably, one new compound, identified as (S)-2-[4-(3-fluoro-benzyloxy) benzamido] propanamide (i.e., Imp-D), is being reported here as an impurity for the first time. Furthermore, the structures of the aforementioned impurities were characterized and confirmed via IR, NMR, and MS techniques, and the most probable formation mechanisms of all impurities proposed according to the synthesis route. Optimum separation was achieved on an Inertsil ODS-3 column (250 × 4.6 mm, 5 μm), using 0.1% formic acid in water (pH adjusted to 5.0) and acetonitrile as the mobile phase in gradient mode. The proposed method was found to be stability-indicating, precise, linear, accurate, sensitive, and robust for the quantitation of SAFM and its process-related substances, including its degradation products.

A simple and robust high-performance liquid chromatography coupled to a diode-array detector method for the analysis of genistein in mouse tissues.

PubMed

Tamames-Tabar, C; Imbuluzqueta, E; Campanero, M A; Horcajada, P; Blanco-Prieto, M J

2013-09-15

A simple liquid-liquid extraction procedure and quantification by high-performance liquid chromatography (HPLC) method coupled to a diode-array detector (DAD) of genistein (GEN) was developed in various mouse biological matrices. 7-ethoxycoumarin was used as internal standard (IS) and peaks were optimally separated using a Kinetex C18 column (2.6μm, 150mm×2.10mm I.D.) at 40°C with an isocratic elution of mobile phase with sodium dihydrogen phosphate 0.01M in water at pH 2.5 and methanol (55:45, v/v), at a flow rate of 0.25mL/min. The injection volume was 10μL. In all cases, the range of GEN recovery was higher than 61%. The low limit of quantification (LLOQ) was 25ng/mL. The linearity of the calibration curves was satisfactory in all cases as shown by correlation coefficients >0.996. The within-day and between-day precisions were <15% and the accuracy ranged in all cases between 90.14% and 106.05%. This method was successfully applied to quantify GEN in liver, spleen, kidney and plasma after intravenous administration of a single dose (30mg/kg) in female BALB/C mice. Copyright © 2013 Elsevier B.V. All rights reserved.

Simultaneous quantitative analysis of dextromethorphan, dextrorphan and chlorphenamine in human plasma by liquid chromatography-electrospray tandem mass spectrometry.

PubMed

Ding, Ying; Huang, Kai; Chen, Lan; Yang, Jie; Xu, Wen-Yan; Xu, Xue-Jiao; Duan, Ru; Zhang, Jing; He, Qing

2014-03-01

A sensitive and accurate HPLC-MS/MS method was developed for the simultaneous determination of dextromethorphan, dextrorphan and chlorphenamine in human plasma. Three analytes were extracted from plasma by liquid-liquid extraction using ethyl acetate and separated on a Kromasil 60-5CN column (3 µm, 2.1 × 150 mm) with mobile phase of acetonitrile-water (containing 0.1% formic acid; 50:50, v/v) at a flow rate of 0.2 mL/min. Quantification was performed on a triple quadrupole tandem mass spectrometer in multiple reaction monitoring mode using positive electrospray ionization. The calibration curve was linear over the range of 0.01-5 ng/mL for dextromethorphan, 0.02-5 ng/mL for dextrorphan and 0.025-20 ng/mL for chlorphenamine. The lower limits of quantification for dextromethorphan, dextrorphan and chlorphenamine were 0.01, 0.02 and 0.025 ng/mL, respectively. The intra- and inter-day precisions were within 11% and accuracies were in the range of 92.9-102.5%. All analytes were proved to be stable during sample storage, preparation and analytic procedures. This method was first applied to the pharmacokinetic study in healthy Chinese volunteers after a single oral dose of the formulation containing dextromethorphan hydrobromide (18 mg) and chlorpheniramine malaeate (8 mg). Copyright © 2013 John Wiley & Sons, Ltd.

A sensitive liquid chromatography-electrospray ionization-mass spectrometry method for the simultaneous determination of pentoxyverine citrate and guaifenesin in human plasma---application to pharmacokinetic and bioequivalence studies.

PubMed

Wen, Jinhua; Zhang, Hong; Xia, Chunhua; Hu, Xiao; Xu, Wenwei; Cheng, Xiaohua; Gao, Jun; Xiong, Yuqing

2010-04-01

A sensitive and specific liquid chromatography-electrospray ionization-mass spectrometry method for the identification and quantification of pentoxyverine citrate and guaifenesin in human plasma has been developed. After extraction from plasma samples by ethyl acetate, the internal standard and analytes were separated by high-performance liquid chromatographic on a Shim-pack VP-ODS C(18) column (150 x 2.0 mm) using a mobile phase consisting of A (methanol) and B (0.4% glacial acetic acid and 4 mmol/L ammonium acetate) (A:B, 43 : 57). Analysis was performed on a Shimadzu LC/MS-2010A in selected ion monitoring mode with a positive electrospray ionization interface. The method was linear in the concentration range of 1.0-640.0 ng/mL for pentoxyverine citrate and 0.025-6.4 microg/mL for guaifenesin. The inter- and intra- precision were all within 12% and accuracy ranged from 85 to 115%.The lower limits of quantification were 1.0 ng/mL for pentoxyverine citrate and 25.0 ng/mL for guaifenesin. The extraction recovery was on average 81.95% for pentoxyverine citrate and 89.03% for guaifenesin. This is the first assay method reported for the simultaneous determination of pentoxyverine citrate and guaifenesin in plasma using one chromatographic run. Copyright (c) 2009 John Wiley & Sons, Ltd.

LC-ESI-MS/MS analysis and pharmacokinetics of 6'-hydroxy justicidin A, a potential antitumor active component isolated from Justicia procumbens, in rats.

PubMed

Qiu, Feng; Zhou, Shujun; Fu, Shujun; Kong, Weijun; Yang, Shihai; Yang, Meihua

2012-11-01

A sensitive and accurate LC-ESI-MS/MS method was developed and validated of for the determination of 6'-hydroxy justicidin A (HJA), a potential antitumor active component isolated from Justicia procumbens in rat plasma using a simple liquid-liquid extraction (LLE) method for sample preparation. Chromatographic separation was achieved on an Agilent Zorbax-C(18) column (2.1 mm × 50 mm, 3.5 μm) using a step gradient program with the mobile phase of 0.1% formic acid aqueous solution and acetonitrile with 0.1% formic acid. HJA and IS (buspirone) were detected using electrospray positive ionization mass spectrometry in the multiple reaction monitoring (MRM) mode. This method demonstrated good linearity and did not show any endogenous interference with the active compound and IS peaks. The lower limit of quantification (LLOQ) of HJA was 0.50 ng/ml in 50 μl rat plasma. The developed and validated method has been successfully applied to the quantification and pharmacokinetic study of HJA in rats after intravenous and oral administration of 0.25 mg/kg HJA. The oral bioavailability (F) of HJA was estimated to be 36.0±13.4% with an elimination half-life (t(1/2)) value of 1.04±0.20 h. Copyright © 2012 Elsevier B.V. All rights reserved.

Simultaneous quantification of six main active constituents in Chinese Angelica by high-performance liquid chromatography with photodiode array detector

PubMed Central

Ying, Li; Si-Wang, Wang; Hong-Hai, Tu; Wei, Cao

2013-01-01

Background: Angelica sinensis is a famous traditional Chinese medicinalherb, which is predominantly used in the treatment of gynecological conditions. It is the first report for the simultaneous determination of six major active components in Chinese Angelica, which is important for quality control. Objective: A validated HPLC-PAD method was first developed to evaluate the quality of crude and processed Radix Angelica through simultaneous determination of six bioactive compounds, namely ferulic acid, senkyunolide I, senkyunolide H, coniferyl ferulate, Z/E-ligustilide and Z/E-butylidenephthalide. Materials and Methods: Samples were separated on a Xtimate™C18 column (250 × 4.6 mm, 5 μm) and detected by PAD. Mobile phase was composed of (A) aqueous phosphoric acid (0.02%, v/v) and (B) acetonitrile (MeCN) (including 10% tetrahydrofuran, v/v) using a gradient elution. Analytes were performed at 30°C with a flow rate of 1.0 mL/min. Results: All calibration curves showed good linear regression (r2 ≥ 0.9963) within the tested ranges, and the recovery of the method was in the range of 91.927–105.859%. Conclusion: The results demonstrate that the developed method is accurate and reproducible and could be readily utilized as a suitable quality control method for the quantification of Radix Angelica. PMID:23772106

Simultaneous determination of carisoprodol and aspirin in human plasma using liquid chromatography-tandem mass spectrometry in polarity switch mode: application to a human pharmacokinetic study.

PubMed

Sreenivasulu, Vudagandla; Ramesh, Mullangi; Kumar, Inamadugu Jaswanth; Babu, Ravi Vasu; Pilli, Nageswara Rao; Krishnaiah, Abburi

2013-02-01

A simple, sensitive and rapid LC-MS/MS-ESI method has been developed and validated for simultaneous quantification of the carisoprodol and aspirin in human plasma. Carisoprodol was detected in positive ion mode, whereas aspirin was detected in negative ion mode. Carbamazepine and furosemide were used as internal standards (IS) for quantification of carisoprodol and aspirin, respectively. The extraction procedure involves a liquid-liquid extraction method with ter-butyl methyl ether. Chromatographic separation was achieved on a Zorbax XDB-Phenyl (4.6 × 75 mm, 3.5 µm) column using an isocratic mobile phase (5 mm ammonium acetate:methanol, 20:80, v/v) at a flow rate of 0.8 mL/min with a total run time of 2.2 min. A detailed method validation was performed as per the FDA guidelines. The standard curves found to be linear in the range of 25.5-4900 and 15.3-3000 ng/mL for carisoprodol and aspirin, respectively. The results met the acceptance criteria. Carisoprodol and aspirin were found to be stable in various stability studies. The validated method was successfully applied to a pharmacokinetic study following co-administration of carisoprodol (250 mg) and aspirin (75 mg) tablets by oral route to human volunteers. Copyright © 2012 John Wiley & Sons, Ltd.

Development and validation of stability indicating method for the quantitative determination of venlafaxine hydrochloride in extended release formulation using high performance liquid chromatography

PubMed Central

Kaur, Jaspreet; Srinivasan, K. K.; Joseph, Alex; Gupta, Abhishek; Singh, Yogendra; Srinivas, Kona S.; Jain, Garima

2010-01-01

Objective: Venlafaxine,hydrochloride is a structurally novel phenethyl bicyclic antidepressant, and is usually categorized as a serotonin–norepinephrine reuptake inhibitor (SNRI) but it has been referred to as a serotonin–norepinephrine–dopamine reuptake inhibitor. It inhibits the reuptake of dopamine. Venlafaxine HCL is widely prescribed in the form of sustained release formulations. In the current article we are reporting the development and validation of a fast and simple stability indicating, isocratic high performance liquid chromatographic (HPLC) method for the determination of venlafaxine hydrochloride in sustained release formulations. Materials and Methods: The quantitative determination of venlafaxine hydrochloride was performed on a Kromasil C18 analytical column (250 × 4.6 mm i.d., 5 μm particle size) with 0.01 M phosphate buffer (pH 4.5): methanol (40: 60) as a mobile phase, at a flow rate of 1.0 ml/min. For HPLC methods, UV detection was made at 225 nm. Results: During method validation, parameters such as precision, linearity, accuracy, stability, limit of quantification and detection and specificity were evaluated, which remained within acceptable limits. Conclusions: The method has been successfully applied for the quantification and dissolution profiling of Venlafaxine HCL in sustained release formulation. The method presents a simple and reliable solution for the routine quantitative analysis of Venlafaxine HCL. PMID:21814426

Quantitative Determination of L-DOPA in Seeds of Mucuna Pruriens Germplasm by High Performance Thin Layer Chromatography

PubMed Central

Raina, Archana P.; Khatri, Renu

2011-01-01

Mucuna pruriens Linn. is an important medicinal plant used for treatment of Parkinson's disease and many others in ancient Indian medical system. L-DOPA extracted from seeds of Mucuna is a constituent of more than 200 indigenous drug formulations and is more effective as drug than the synthetic counterpart. A densitometric high performance thin-layer chromatographic (HPTLC) method was developed for quantification of L-DOPA content present in the seeds extract. The method involves separation of L-DOPA on precoated silica gel 60 GF254 HPTLC plates using a solvent system of n-butanol-acetic-acid-water (4:1:1, v/v) as the mobile phase. Quantification was done at 280 nm using absorbance reflectance mode. Linearity was found in the concentration range of 100 to 1000 ng/spot with the correlation coefficient value of 0.9980. The method was validated for accuracy, precision and repeatability. Mean recovery was 100.89%. The LOD and LOQ for L-DOPA determination were found to be 3.41 ng/spot and 10.35 ng/spot respectively. The proposed HPTLC method was found to be precise, specific and accurate for quantitative determination of L-DOPA. It can be used for rapid screening of large germplasm collections of Mucuna pruriens for L-DOPA content. The method was used to study variation in fifteen accessions of Mucuna germplasm collected from different geographical regions. PMID:22707835

Quantitative Determination of L-DOPA in Seeds of Mucuna Pruriens Germplasm by High Performance Thin Layer Chromatography.

PubMed

Raina, Archana P; Khatri, Renu

2011-07-01

Mucuna pruriens Linn. is an important medicinal plant used for treatment of Parkinson's disease and many others in ancient Indian medical system. L-DOPA extracted from seeds of Mucuna is a constituent of more than 200 indigenous drug formulations and is more effective as drug than the synthetic counterpart. A densitometric high performance thin-layer chromatographic (HPTLC) method was developed for quantification of L-DOPA content present in the seeds extract. The method involves separation of L-DOPA on precoated silica gel 60 GF(254) HPTLC plates using a solvent system of n-butanol-acetic-acid-water (4:1:1, v/v) as the mobile phase. Quantification was done at 280 nm using absorbance reflectance mode. Linearity was found in the concentration range of 100 to 1000 ng/spot with the correlation coefficient value of 0.9980. The method was validated for accuracy, precision and repeatability. Mean recovery was 100.89%. The LOD and LOQ for L-DOPA determination were found to be 3.41 ng/spot and 10.35 ng/spot respectively. The proposed HPTLC method was found to be precise, specific and accurate for quantitative determination of L-DOPA. It can be used for rapid screening of large germplasm collections of Mucuna pruriens for L-DOPA content. The method was used to study variation in fifteen accessions of Mucuna germplasm collected from different geographical regions.

Rapid trace level determination of sulfonamide residues in honey with online extraction using short C-18 column by high-performance liquid chromatography with fluorescence detection.

PubMed

Sajid, Muhammad; Na, Na; Safdar, Muhammad; Lu, Xin; Ma, Lin; He, Lan; Ouyang, Jin

2013-11-01

A sensitive and inexpensive quantification method with online extraction using a short C-18 column for sulfonamide residues in honey by high performance liquid chromatography with fluorescence detector was developed and validated. In sample preparation, acid hydrolysis was used to break the N-glycoside bond between the honey sugar and sulfonamide drugs and derivatization of sulfonamide residues with fluorescamine was conducted at pH 3.5 using a citrate buffer (0.5M) in the honey matrix. The chromatography was carried out on Zorbax Extended C-18 (250mm×4.6mm; 5μm) column, using a mixture of acetonitrile and an acetate buffer (pH 4.50, 20mM) as a mobile phase. A Zorbax Extended C-18 (12mm×4.6mm; 5μm) column was used for online extraction of fifteen sulfonamide residues from honey sample with the help of a two position valve. The limit of quantification of sulfonamide residues in honey was less than 3ngg(-1), and the percentage recovery of study compounds in spiked honey sample was from 80% for sulfacetamide to 100% of sulfachloropyridazine. The developed method has excellent linearity for all studied sulfonamides with a correlation coefficient 0.993. Copyright © 2013 Elsevier B.V. All rights reserved.

Determination of ambroxol in human plasma using LC-MS/MS.

PubMed

Kim, Hohyun; Yoo, Jeong-Yeon; Han, Sang Beom; Lee, Hee Joo; Lee, Kyung Ryul

2003-06-01

A sensitive and selective liquid chromatographic method coupled with tandem mass spectrometry (LC-MS/MS) was developed for the quantification of ambroxol in human plasma. Domperidone was used as internal standard, with plasma samples extracted using diethyl ether under basic condition. A centrifuged upper layer was then evaporated and reconstituted with 200 microl methanol. The reconstituted samples were injected into a C(18) XTerra MS column (2.1 x 30 mm) with 3.5 microm particle size. The analytical column lasted for at least 600 injections. The mobile phase was composed of 20 mM ammonium acetate in 90% acetonitrile (pH 8.8), with flow rate at 250 microl/min. The mass spectrometer was operated in positive ion mode using turbo electrospray ionization. Nitrogen was used as the nebulizer, curtain, collision, and auxiliary gases. Using MS/MS with multiple reaction monitoring (MRM) mode, ambroxol was detected without severe interferences from plasma matrix. Ambroxol produced a protonated precursor ion ([M+H](+)) at m/z 379 and a corresponding product ion at m/z 264. And internal standard (domperidone) produced a protonated precursor ion ([M+H](+)) at m/z 426 and a corresponding product ion at m/z 174. Detection of ambroxol in human plasma was accurate and precise, with quantification limit at 0.2 ng/ml. This method has been successfully applied to a study of ambroxol in human specimens.

Residue analysis and degradation studies of fenbuconazole and myclobutanil in strawberry by chiral high-performance liquid chromatography-tandem mass spectrometry.

PubMed

Zhang, Hu; Wang, Xinquan; Qian, Mingrong; Wang, Xiangyun; Xu, Hao; Xu, Mingfei; Wang, Qiang

2011-11-23

A simple and sensitive enantioselective method for the determination of fenbuconazole and myclobutanil in strawberry was developed by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). Fenbuconazole and myclobutanil residues in strawberry were extracted with acetonitrile containing 1% acetic acid, and an aliquot was cleaned up with PSA (primary and secondary amine) and C(18) sorbent. The direct resolution of fenbuconazole and myclobutanil enantiomers was performed on a cellulose tris (3,5-dimethylphenylcarbamate) column using acetonitrile-0.1% formic acid solution (60:40, v/v) as the mobile phase. Quantification was achieved using matrix-matched standard calibration curves, and the limits of quantification for fenbuconazole and myclobutanil enantiomers in strawberry were both 2 μg/kg. The method was successfully utilized to investigate the probable enantioselective degradation of fenbuconazole and myclobutanil in strawberry. The results showed that the degradation of the fenbuconazole and myclobutanil enantiomers in strawberry followed pseudofirst-order kinetics (R(2) > 0.97). The results from this study revealed that the degradation of fenbuconazole in strawberry was not enantioselective, while the degradation of myclobutanil was enantioselective, and the (+)-myclobutanil showed a faster degradation than (-)-myclobutanil in strawberry, resulting in the relative enrichment of (-)-myclobutanil in residue. The results could provide a reference to fully evaluate the risks of these two fungicides.

High performance liquid chromatography with mid-infrared detection based on a broadly tunable quantum cascade laser.

PubMed

Beskers, Timo F; Brandstetter, Markus; Kuligowski, Julia; Quintás, Guillermo; Wilhelm, Manfred; Lendl, Bernhard

2014-05-07

This work introduces a tunable mid-infrared (mid-IR) external cavity quantum cascade laser (EC-QCL) as a new molecular specific detector in liquid chromatography. An EC-QCL with a maximum tunability of 200 cm(-1) (1030-1230 cm(-1)) was coupled to isocratic high performance liquid chromatography (HPLC) for the separation of sugars with a cation exchange column (counter ion: Ca(2+)) and distilled water as the mobile phase. Transmission measurements in a 165 μm thick flow cell allowed for on-line coupling and independent quantification of glucose, fructose and sucrose in the concentration range from 5 mg mL(-1) to 100 mg mL(-1) in several beverages. The results obtained with the EC-QCL detector were found to be in good agreement with those obtained using a differential refractive index detector as a reference. The standard deviation of the method for the linear calibration was better than 5 mg mL(-1) for all sugars and reached a minimum of 1.9 mg mL(-1), while the DRI detector reached a minimum of 1 mg mL(-1). Besides the quantification of sugars for which a calibration was performed, also chromatographic peaks of other components could be identified on the basis of their IR absorption spectra. This includes taurine, ethanol, and sorbitol.

A Simple and Specific Stability- Indicating RP-HPLC Method for Routine Assay of Adefovir Dipivoxil in Bulk and Tablet Dosage Form.

PubMed

Darsazan, Bahar; Shafaati, Alireza; Mortazavi, Seyed Alireza; Zarghi, Afshin

2017-01-01

A simple and reliable stability-indicating RP-HPLC method was developed and validated for analysis of adefovir dipivoxil (ADV).The chromatographic separation was performed on a C 18 column using a mixture of acetonitrile-citrate buffer (10 mM at pH 5.2) 36:64 (%v/v) as mobile phase, at a flow rate of 1.5 mL/min. Detection was carried out at 260 nm and a sharp peak was obtained for ADV at a retention time of 5.8 ± 0.01 min. No interferences were observed from its stress degradation products. The method was validated according to the international guidelines. Linear regression analysis of data for the calibration plot showed a linear relationship between peak area and concentration over the range of 0.5-16 μg/mL; the regression coefficient was 0.9999and the linear regression equation was y = 24844x-2941.3. The detection (LOD) and quantification (LOQ) limits were 0.12 and 0.35 μg/mL, respectively. The results proved the method was fast (analysis time less than 7 min), precise, reproducible, and accurate for analysis of ADV over a wide range of concentration. The proposed specific method was used for routine quantification of ADV in pharmaceutical bulk and a tablet dosage form.

78 FR 45071 - Annual Report for Mobility Fund Phase I Support and Record Retention

Federal Register 2010, 2011, 2012, 2013, 2014

2013-07-26

... for Mobility Fund Phase I Support and Record Retention AGENCY: Federal Communications Commission... information collection associated with the Commission's Annual Report for Mobility Fund Phase I Support and... or sponsor a collection of information unless it displays a current, valid OMB Control Number. No...

47 CFR 54.1005 - Application process.

Code of Federal Regulations, 2012 CFR

2012-10-01

... for Mobility Fund Phase I Support. In addition to providing information specified in § 1.21001(b) of... competitive bidding for Mobility Fund Phase I support also shall: (1) Provide ownership information as set... Mobility Fund Phase I Support—(1) Deadline. Unless otherwise provided by public notice, winning bidders for...

47 CFR 54.1005 - Application process.

Code of Federal Regulations, 2013 CFR

2013-10-01

... for Mobility Fund Phase I support. In addition to providing information specified in § 1.21001(b) of... competitive bidding for Mobility Fund Phase I support also shall: (1) Provide ownership information as set... Mobility Fund Phase I support.—(1) Deadline. Unless otherwise provided by public notice, winning bidders...

47 CFR 54.1005 - Application process.

Code of Federal Regulations, 2014 CFR

2014-10-01

... for Mobility Fund Phase I support. In addition to providing information specified in § 1.21001(b) of... competitive bidding for Mobility Fund Phase I support also shall: (1) Provide ownership information as set... Mobility Fund Phase I support.—(1) Deadline. Unless otherwise provided by public notice, winning bidders...

Simultaneous quantification and inhibitory effect on LDL oxidation of the traditional Korean medicine, Leejung-tang

PubMed Central

2014-01-01

Background Leejung-tang (LJT) is a traditional Korean herbal medicine for the treatment of gastrointestinal disorders. In this study, we performed quantification analysis of five marker components, liquiritin (1), ginsenoside Rg1 (2), ginsenoside Rb1 (3), glycyrrhizin (4), and 6-gingerol (5) in LJT using a high performance liquid chromatography-photodiode array (HPLC–PDA). In addition, we investigated the inhibitory effect on low-density lipoprotein (LDL) oxidation by the LJT sample. Methods Compounds 1–5 were separated within 35 min using a Gemini C18 column. The mobile phase used gradient elution with 1.0% (v/v) aqueous acetic acid (A) and 1.0% (v/v) acetic acid in acetonitrile (B). The flow rate was 1.0 mL/min and the detector was a photodiode array (PDA) set at 203 nm, 254 nm, and 280 nm. The inhibitory effect on LDL oxidation conduct an experiment on thiobarbituric acid reactive substance (TBARS) assay, relative electrophoretic mobility (REM) assay, and electrophoresis of ApoB fragmentation of LJT. Results Calibration curves of compounds 1–5 showed good linearity (r2 ≥0.9995) in different concentration ranges. The recoveries of compounds 1–5 were in the range of 98.90–103.39%, with relative standard deviations (RSD) below 3.0%. The RSDs (%) of intra-day and inter-day precision were 0.10–1.08% and 0.29–1.87%, respectively. The inhibitory effect of LJT on Cu2+-induced LDL oxidation was defined by TBARS assay (IC50: 165.7 μg/mL) and REM of oxLDL (decrease of 50% at 127.7 μg/mL). Furthermore LJT reduced the fragmentation of ApoB of oxLDL in a dose-dependent manner. Conclusions The established HPLC-PDA method will be helpful to improve quality control of LJT. In addition, LJT is a potential LDL oxidation inhibitor. PMID:24383717

A Laterally-Mobile Mixed Polymer/Polyelectrolyte Brush Undergoes a Macroscopic Phase Separation

NASA Astrophysics Data System (ADS)

Lee, Hoyoung; Park, Hae-Woong; Tsouris, Vasilios; Choi, Je; Mustafa, Rafid; Lim, Yunho; Meron, Mati; Lin, Binhua; Won, You-Yeon

2013-03-01

We studied mixed PEO and PDMAEMA brushes. The question we attempted to answer was: When the chain grafting points are laterally mobile, how will this lateral mobility influence the structure and phase behavior of the mixed brush? Two different model mixed PEO/PDMAEMA brush systems were prepared: a mobile mixed brush by spreading a mixture of two diblock copolymers, PEO-PnBA and PDMAEMA-PnBA, onto the air-water interface, and an inseparable mixed brush using a PEO-PnBA-PDMAEMA triblock copolymer having respective brush molecular weights matched to those of the diblock copolymers. These two systems were investigated by surface pressure-area isotherm, X-ray reflectivity and AFM imaging measurements. The results suggest that the mobile mixed brush undergoes a lateral macroscopic phase separation at high chain grafting densities, whereas the inseparable system is only microscopically phase separated under comparable brush density conditions. We also conducted an SCF analysis of the phase behavior of the mixed brush system. This analysis further supported the experimental findings. The macroscopic phase separation observed in the mobile system is in contrast to the microphase separation behavior commonly observed in two-dimensional laterally-mobile small molecule mixtures.

Stereoselective determination of vigabatrin enantiomers in human plasma by high performance liquid chromatography using UV detection.

PubMed

Franco, Valentina; Mazzucchelli, Iolanda; Fattore, Cinzia; Marchiselli, Roberto; Gatti, Giuliana; Perucca, Emilio

2007-07-01

A rapid and simple high-performance liquid chromatographic method for the determination of the R-(-)- and S-(+)-enantiomers of the antiepileptic drug vigabatrin in human plasma is described. After adding the internal standard (1-aminomethyl-cycloheptyl-acetic acid), plasma samples (200 microL) are deproteinized with acetonitrile and the supernatant is derivatized with 2,4,6 trinitrobenzene sulfonic acid (TNBSA). Separation is achieved on a reversed-phase cellulose-based chiral column (Chiralcel-ODR, 250 mm x 4.6 mm i.d.) using 0.05 M potassium hexafluorophosphate (pH 4.5)/acetonitrile/ethanol (50:40:10 vol/vol/vol) as mobile phase at a flow-rate of 0.9 mL/min. Chromatographic selectivity is improved by concentrating the derivatives on High Performance Extraction Disk Cartridges prior to injection. Detection is at 340 nm. Calibration curves are linear (r(2)> or =0.999) over the range of 0.5-40 microg/mL for each enantiomer, with a limit of quantification of 0.5 microg/mL for both analytes. The assay is suitable for therapeutic drug monitoring and for single-dose pharmacokinetic studies in man.

Development and validation of a high performance liquid chromatographic method for the determination of oxcarbazepine and its main metabolites in human plasma and cerebrospinal fluid and its application to pharmacokinetic study.

PubMed

Kimiskidis, Vasilios; Spanakis, Marios; Niopas, Ioannis; Kazis, Dimitrios; Gabrieli, Chrysi; Kanaze, Feras Imad; Divanoglou, Daniil

2007-01-17

An isocratic reversed-phase HPLC-UV procedure for the determination of oxcarbazepine and its main metabolites 10-hydroxy-10,11-dihydrocarbamazepine and 10,11-dihydroxy-trans-10,11-dihydrocarbamazepine in human plasma and cerebrospinal fluid has been developed and validated. After addition of bromazepam as internal standard, the analytes were isolated from plasma and cerebrospinal fluid by liquid-liquid extraction. Separation was achieved on a X-TERRA C18 column using a mobile phase composed of 20 mM KH(2)PO(4), acetonitrile, and n-octylamine (76:24:0.05, v/v/v) at 40 degrees C and detected at 237 nm. The described assay was validated in terms of linearity, accuracy, precision, recovery and lower limit of quantification according to the FDA validation guidelines. Calibration curves were linear with a coefficient of variation (r) greater than 0.998. Accuracy ranged from 92.3% to 106.0% and precision was between 2.3% and 8.2%. The method has been applied to plasma and cerebrospinal fluid samples obtained from patients treated with oxcarbazepine, both in monotherapy and adjunctive therapy.

Development and validation of a dried blood spot-HPLC assay for the determination of metronidazole in neonatal whole blood samples.

PubMed

Suyagh, Maysa Faisal; Iheagwaram, Godwill; Kole, Prashant Laxman; Millership, Jeff; Collier, Paul; Halliday, Henry; McElnay, James C

2010-05-01

A selective and sensitive high-performance liquid chromatography method with UV detection for the determination of metronidazole in dried blood spots (DBS) has been developed and validated. DBS samples [spiked or patient samples] were prepared by applying blood (30 microL) to Guthrie cards. Discs (6 mm diameter) were punched from the cards and extracted using water containing the internal standard, tinidazole. The extracted sample was chromatographed without further treatment using a reversed phase system involving a Symmetry(R) C18 (5 microm, 3.9 x 150 mm) preceded by a Symmetry(R) guard column of matching chemistry and a detection wavelength of 317 nm. The mobile phase comprised acetonitrile/0.01 M phosphate solution (KH(2)PO(4)), pH 4.7, 15:85, v/v, with a flow rate of 1 mL/min. The calibration was linear over the range 2.5-50 mg/mL. The limits of detection and quantification were 0.6 and 1.8 microg/mL, respectively. The method has been applied to the determination of 203 DBS samples from neonatal patients for a phamacokinetic/pharmacodynamic study.

Optimization of Robust HPLC Method for Quantitation of Ambroxol Hydrochloride and Roxithromycin Using a DoE Approach.

PubMed

Patel, Rashmin B; Patel, Nilay M; Patel, Mrunali R; Solanki, Ajay B

2017-03-01

The aim of this work was to develop and optimize a robust HPLC method for the separation and quantitation of ambroxol hydrochloride and roxithromycin utilizing Design of Experiment (DoE) approach. The Plackett-Burman design was used to assess the impact of independent variables (concentration of organic phase, mobile phase pH, flow rate and column temperature) on peak resolution, USP tailing and number of plates. A central composite design was utilized to evaluate the main, interaction, and quadratic effects of independent variables on the selected dependent variables. The optimized HPLC method was validated based on ICH Q2R1 guideline and was used to separate and quantify ambroxol hydrochloride and roxithromycin in tablet formulations. The findings showed that DoE approach could be effectively applied to optimize a robust HPLC method for quantification of ambroxol hydrochloride and roxithromycin in tablet formulations. Statistical comparison between results of proposed and reported HPLC method revealed no significant difference; indicating the ability of proposed HPLC method for analysis of ambroxol hydrochloride and roxithromycin in pharmaceutical formulations. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Determination of phthalate esters in cleaning and personal care products by dispersive liquid-liquid microextraction and liquid chromatography-tandem mass spectrometry.

PubMed

Viñas, Pilar; Campillo, Natalia; Pastor-Belda, Marta; Oller, Ainhoa; Hernández-Córdoba, Manuel

2015-01-09

Phthalic acid esters (PEs) were preconcentrated from cleaning products, detergents and cosmetics using ultrasound assisted extraction (UAE) in the presence of acetonitrile, and then submitted to dispersive liquid-liquid microextraction (DLLME). For DLLME, 3mL of acetonitrile extract, 150μL carbon tetrachloride and 10mL aqueous solution were used. The enriched organic phase was evaporated, reconstituted with 25μL acetonitrile and injected into a liquid chromatograph with a mobile phase (acetonitrile:10mM ammonium acetate, pH 4) under gradient elution. Detection was carried out using both diode-array (DAD) and electrospray-ion trap-tandem mass spectrometry (ESI-IT-MS/MS) in the multiple reaction monitoring mode (MRM) of the positive fragment ions. Quantification was carried out using matrix-matched standards. Detection limits were in the range 0.04-0.45ngmL(-1) for the six PEs considered. The recoveries obtained were in the 84-124% range, with RSDs lower than 10%. Thirty three different cleaning products were analyzed. The most frequently found compound was diethyl phthalate. Copyright © 2014 Elsevier B.V. All rights reserved.

Validated enantiospecific LC method for determination of (R)-enantiomer impurity in (S)-efavirenz.

PubMed

Seshachalam, U; Narasimha Rao, D V L; Chandrasekhar, K B

2008-02-01

A high-performance liquid chromatographic method was developed for separation of the enantiomers of efavirenz. The developed method was applied for the determination of (R)-enantiomer in (S)-efavirenz and satisfactory results were achieved. The base line separation with a resolution of more than 4.0 was achieved on Chiralcel OD (250 mm x 4.6 mm, 10 microm) column containing tris-(3,5-dimethylphenylcarbomate) as stationary phase. The mobile phase consists of n-hexane: isopropyl alcohol (80:20 v/v) with 0.1% (v/v) of formic acid as additive. The flow rate was kept at 1.0 ml/min and the UV detection was monitored at 254 nm. The (R)-enantiomer was found linear over the range of 0.1 microg/ml--6 microg/ml. The limit of detection (LOD) was 0.03 microg/ml and the limit of quantification (LOQ) was 0.1 microg/ml (n=3. The precision of (R)-enantiomer at LOQ level was evaluated through six replicate injections and the RSD of the peak response was achieved as 1.34%. The results demonstrated that the developed LC method was simple, precise, robust and applicable for the purity determination of efavirenz.

Multi-residue analysis method for analysis of pharmaceuticals using liquid chromatography-time of flight/mass spectrometry (LC-TOF/MS) in water sample

NASA Astrophysics Data System (ADS)

Al-Qaim, Fouad Fadhil; Abdullah, Md Pauzi; Othman, Mohamed Rozali

2013-11-01

In this work, a developed method using solid - phase extraction (SPE) followed by liquid chromatography - time of flight mass spectrometry (LC-ESI-TOF/MS) was developed and validated for quantification and confirmation of eleven pharmaceuticals with different therapeutic classes in water samples, Malaysia. These compounds are caffeine (CAF), prazosin (PRZ), enalapril (ENL), carbamazepine (CBZ), nifedipine (NFD), levonorgestrel (LNG), simvastatin (SMV), hydrochlorothiazide (HYD), gliclazide (GLIC), diclofenac-Na (DIC-Na) and mefenamic acid (MEF). LC was performed on a Dionex Ultimate 3000/LC 09115047 (USA) system. Chromatography was performed on a Thermo Scientific C18 (250 mm × 2.1 mm, i.d.: 5μm) column. Several parameters were optimised such as; mobile phase, gradient elution, collision energy and solvent elution for extraction of compounds from water. The recoveries obtained ranged from 30-148 % in river water. Five pharmaceutical compounds were detected in the surface water samples: caffeine, prazosin, enalpril, diclofenac-Na and mefenamic acid. The developed method is precise and accepted recoveries were got. In addition, this method is suitable to identify and quantify trace concentrations of pharmaceuticals in surface water.

Ultra-high-pressure liquid chromatography-tandem mass spectrometry method for the determination of alkylphenols in soil.

PubMed

Wang, Jing; Pan, Hefang; Liu, Zhengzheng; Ge, Fei

2009-03-20

A novel method has been developed for the determination of alkylphenols in soil by ultra-high-pressure liquid chromatography employing small particle sizes, combined with tandem mass spectrometry. Soil samples were extracted with pressurized liquid extraction (PLE) and then cleaned with solid-phase extraction (SPE). The extracts were separated on C18 column (1.7 microm, 50 mm x 2.1mm) with a gradient elution and a mobile phase consisting of water and acetonitrile, and then detected by an electrospray ionization tandem mass spectrometry in negative ion mode with multiple reaction monitoring (MRM). Compared with traditional liquid chromatography, it took ultra-high-pressure liquid chromatography much less time to analyze alkylphenols. Additionally, the ultra-high-pressure liquid chromatography/tandem mass spectrometry method produces satisfactory reliability, sensitivity, and accuracy. The average recoveries of the three target analytes were 74.0-103.4%, with the RSD<15%. The calibration curves for alkylphenols were linear within the range of 0.01-0.4 microg/ml, with the correlation coefficients greater than 0.99. When 10 g soil sample was used for analysis, the limits of quantification (LOQs) of the three alkylphenols were all 1.0 microg/kg.

Microemulsion Liquid Chromatographic Method for Simultaneous Determination of Simvastatin and Ezetimibe in Their Combined Dosage Forms

PubMed Central

Hammouda, Mohammed E. A.; Abu El-Enin, Mohamed A.; El-Sherbiny, Dina T.; El-Wasseef, Dalia R.; El-Ashry, Saadia M.

2013-01-01

A rapid HPLC procedure using a microemulsion as an eluent was developed and validated for analytical quality control of antihyperlipidemic mixture containing simvastatin (SIM) and ezetimibe (EZT) in their pharmaceutical preparations. The separation was performed on a column packed with cyano bonded stationary phase adopting UV detection at 238 nm using a flow rate of 1 mL/min. The optimized microemulsion mobile phase consisted of 0.2 M sodium dodecyl sulphate, 1% octanol, 10% n-propanol, and 0.3% triethylamine in 0.02 M phosphoric acid at pH 5.0. The developed method was validated in terms of specificity, linearity, lower limit of quantification (LOQ), lower limit of detection (LOD), precision, and accuracy. The proposed method is rapid (8.5 min), reproducible (RSD < 2.0%) and achieves satisfactory resolution between SIM and EZT (resolution factor = 2.57). The mean recoveries of the analytes in pharmaceutical preparations were in agreement with those obtained from a reference method, as revealed by statistical analysis of the obtained results using Student's t-test and the variance ratio F-test. PMID:24282651

Improvement of Nicotinic Acid and Nicotinamide Analysis in Meats and Meat Products by HPLC and LC-MS/MS with Solid-Phase Extraction.

PubMed

Hiki, Asako; Yamajima, Yukiko; Uematsu, Yoko

2016-01-01

A method for nicotinic acid (NA) and nicotinamide (NAA) analysis in meats was developed. NA and NAA were extracted from meats or meat products with metaphosphate aqueous solution. The extract was cleaned up with an Oasis MCX cartridge. The cartridge was washed with 2% acetic acid (v/v) and acetic acid-methanol solution. NA and NAA were eluted with ammonia-methanol solution. NA and NAA in the eluate were chromatographed on a Scherzo SM-C18 (3.0×150 mm, 3.0 μm) column with 20 mmol/L ammonium acetate containing 0.1% acetic acid-acetonitrile (97 : 3) as a mobile phase and were monitored at 261 nm. Quantification was performed by LC and LC-MS/MS. Calibration curves showed high linearity (correlation coefficient>0.998) between 1-25 μg/mL for LC and LC-MS/MS. Recoveries were 84-108% (CV≦5.8%) by HPLC and 79-105% (CV≦9.0%) by LC-MS/MS. The limit of quantitation for NA was 0.005-0.01 g/kg and that for NAA was 0.01-0.02 g/kg.

LC-MS/MS assay for the quantitation of the tyrosine kinase inhibitor neratinib in human plasma.

PubMed

Kiesel, Brian F; Parise, Robert A; Wong, Alvin; Keyvanjah, Kiana; Jacobs, Samuel; Beumer, Jan H

2017-02-05

Neratinib is an orally available tyrosine kinase inhibitor targeting HER2 (ERBB2) and EGFR (ERBB). It is being clinically evaluated for the treatment of breast and other solid tumors types as a single agent or in combination with other chemotherapies. In support of several phase I/II clinical trials investigating neratinib combinations, we developed and validated a novel LC-MS/MS assay for the quantification of neratinib in 100μL of human plasma with a stable isotopic internal standard. Analytes were extracted from plasma using protein precipitation and evaporation of the resulting supernatant followed by resuspension. Chromatographic separation was achieved using an Acquity UPLC BEH Shield RP18 column and a gradient methanol-water mobile phase containing 10% ammonium acetate. An ABI 4000 mass spectrometer and electrospray positive mode ionization were used for detection. The assay was linear from 2 to 1,000ng/mL and proved to be accurate (98.9-106.5%) and precise (<6.2%CV), and met the FDA guidance for bioanalytical method validation. This LC-MS/MS assay will be an essential tool to further define the pharmacokinetics of neratinib. Copyright © 2016 Elsevier B.V. All rights reserved.

Present-day Horizontal Mobility in the Serbian Part of the Pannonian Basin; Inferences from the Geometric Analysis of Deformations

NASA Astrophysics Data System (ADS)

Sušić, Zoran; Toljić, Marinko; Bulatović, Vladimir; Ninkov, Toša; Stojadinović, Uroš

2016-10-01

In tectonically complex environments, such as the Pannonian Basin surrounded by the Alps-Dinarides and Carpathians orogens, monitoring of recent deformations represents very challenging matter. Efficient quantification of active continental deformations demands the use of a multidisciplinary approach, including neotectonic, seismotectonic and geodetic methods. The present-day tectonic mobility in the Pannonian Basin is predominantly controlled by the northward movement of the Adria micro-plate, which has produced compressional stresses that were party accommodated by the Alps-Dinarides thrust belt and partly transferred towards its hinterland. Influence of thus induced stresses on the recent strain field, deformations and tectonic mobility in the southern segment of the Pannonian Basin has been investigated using GPS measurements of the horizontal mobility in the Vojvodina area (northern Serbia).

A low cost mobile phone dark-field microscope for nanoparticle-based quantitative studies.

PubMed

Sun, Dali; Hu, Tony Y

2018-01-15

Dark-field microscope (DFM) analysis of nanoparticle binding signal is highly useful for a variety of research and biomedical applications, but current applications for nanoparticle quantification rely on expensive DFM systems. The cost, size, limited robustness of these DFMs limits their utility for non-laboratory settings. Most nanoparticle analyses use high-magnification DFM images, which are labor intensive to acquire and subject to operator bias. Low-magnification DFM image capture is faster, but is subject to background from surface artifacts and debris, although image processing can partially compensate for background signal. We thus mated an LED light source, a dark-field condenser and a 20× objective lens with a mobile phone camera to create an inexpensive, portable and robust DFM system suitable for use in non-laboratory conditions. This proof-of-concept mobile DFM device weighs less than 400g and costs less than $2000, but analysis of images captured with this device reveal similar nanoparticle quantitation results to those acquired with a much larger and more expensive desktop DFMM system. Our results suggest that similar devices may be useful for quantification of stable, nanoparticle-based activity and quantitation assays in resource-limited areas where conventional assay approaches are not practical. Copyright © 2017 Elsevier B.V. All rights reserved.

Rapid imaging, detection and quantification of Giardia lamblia cysts using mobile-phone based fluorescent microscopy and machine learning.

PubMed

Koydemir, Hatice Ceylan; Gorocs, Zoltan; Tseng, Derek; Cortazar, Bingen; Feng, Steve; Chan, Raymond Yan Lok; Burbano, Jordi; McLeod, Euan; Ozcan, Aydogan

2015-03-07

Rapid and sensitive detection of waterborne pathogens in drinkable and recreational water sources is crucial for treating and preventing the spread of water related diseases, especially in resource-limited settings. Here we present a field-portable and cost-effective platform for detection and quantification of Giardia lamblia cysts, one of the most common waterborne parasites, which has a thick cell wall that makes it resistant to most water disinfection techniques including chlorination. The platform consists of a smartphone coupled with an opto-mechanical attachment weighing ~205 g, which utilizes a hand-held fluorescence microscope design aligned with the camera unit of the smartphone to image custom-designed disposable water sample cassettes. Each sample cassette is composed of absorbent pads and mechanical filter membranes; a membrane with 8 μm pore size is used as a porous spacing layer to prevent the backflow of particles to the upper membrane, while the top membrane with 5 μm pore size is used to capture the individual Giardia cysts that are fluorescently labeled. A fluorescence image of the filter surface (field-of-view: ~0.8 cm(2)) is captured and wirelessly transmitted via the mobile-phone to our servers for rapid processing using a machine learning algorithm that is trained on statistical features of Giardia cysts to automatically detect and count the cysts captured on the membrane. The results are then transmitted back to the mobile-phone in less than 2 minutes and are displayed through a smart application running on the phone. This mobile platform, along with our custom-developed sample preparation protocol, enables analysis of large volumes of water (e.g., 10-20 mL) for automated detection and enumeration of Giardia cysts in ~1 hour, including all the steps of sample preparation and analysis. We evaluated the performance of this approach using flow-cytometer-enumerated Giardia-contaminated water samples, demonstrating an average cyst capture efficiency of ~79% on our filter membrane along with a machine learning based cyst counting sensitivity of ~84%, yielding a limit-of-detection of ~12 cysts per 10 mL. Providing rapid detection and quantification of microorganisms, this field-portable imaging and sensing platform running on a mobile-phone could be useful for water quality monitoring in field and resource-limited settings.

Sensitive quantification of apomorphine in human plasma using a LC-ESI-MS-MS method.

PubMed

Abe, Emuri; Alvarez, Jean-Claude

2006-06-01

An analytical method based on liquid chromatography coupled with ion trap mass spectrometry (MS) detection with electrospray ionization interface has been developed for the identification and quantification of apomorphine in human plasma. Apomorphine was isolated from 0.5 mL of plasma using a liquid-liquid extraction with diethyl ether and boldine as internal standard, with satisfactory extraction recoveries. Analytes were separated on a 5-microm C18 Highpurity (Thermohypersil) column (150 mm x 2.1 mm I.D.) maintained at 30 degrees C, coupled to a precolumn (C18, 5-microm, 10 mm x 2.0 mm I.D., Thermo). The elution was achieved isocratically with a mobile phase of 2 mM NH4COOH buffer pH 3.8/acetonitrile (50/50, vol/vol) at a flow rate of 200 microL per minute. Data were collected either in full-scan MS mode at m/z 150 to 500 or in full-scan tandem mass spectrometry mode, selecting the [M+H]ion at m/z 268.0 for apomorphine and m/z 328.0 for boldine. The most intense daughter ion of apomorphine (m/z 237.1) and boldine (m/z 297.0) were used for quantification. Retention times were 2.03 and 2.11 minutes for boldine and apomorphine, respectively. Calibration curves were linear in the 0.025 to 20 ng/mL range. The limits of detection and quantification were 0.010 ng/mL and 0.025 ng/mL, respectively. Accuracy and precision of the assay were measured by analyzing 54 quality control samples for 3 days. At concentrations of 0.075, 1.5, and 15 ng/mL, intraday precisions were less than 10.1%, 5.3%, and 3.8%, and interday precisions were less than 4.8%, 6.6%, and 6.5%, respectively. Accuracies were in the 99.5 to 104.2% range. An example of a patient who was given 6 mg of apomorphine subcutaneously is shown, with concentrations of 14.1 ng/mL after 30 minutes and 0.20 ng/mL after 6 hours. The method described enables the unambiguous identification and quantification of apomorphine with very good sensitivity using only 0.5 mL of sample, and is very convenient for therapeutic drug monitoring and pharmacokinetic studies.

Development and validation of an UHPLC-ESI-QTOF-MS method for quantification of the highly hydrophilic amyloid-β oligomer eliminating all-D-enantiomeric peptide RD2 in mouse plasma.

PubMed

Hupert, Michelle; Elfgen, Anne; Schartmann, Elena; Schemmert, Sarah; Buscher, Brigitte; Kutzsche, Janine; Willbold, Dieter; Santiago-Schübel, Beatrix

2018-01-15

During preclinical drug development, a method for quantification of unlabeled compounds in blood plasma samples from treatment or pharmacokinetic studies in mice is required. In the current work, a rapid, specific, sensitive and validated liquid chromatography mass-spectrometric UHPLC-ESI-QTOF-MS method was developed for the quantification of the therapeutic compound RD2 in mouse plasma. RD2 is an all-D-enantiomeric peptide developed for the treatment of Alzheimer's disease, a progressive neurodegenerative disease finally leading to dementia. Due to RD2's highly hydrophilic properties, the sample preparation and the chromatographic separation and quantification were very challenging. The chromatographic separation of RD2 and its internal standard were accomplished on an Acquity UPLC BEH C18 column (2.1 × 100 mm, 1.7 μm particle size) within 6.5 min at 50 °C with a flow rate of 0.5 mL/min. Mobile phases consisted of water and acetonitrile with 1% formic acid and 0.025% heptafluorobutyric acid, respectively. Ions were generated by electrospray ionization (ESI) in the positive mode and the peptide was quantified by QTOF-MS. The developed extraction method for RD2 from mouse plasma revealed complete recovery. The linearity of the calibration curve was in the range of 5.3 ng/mL to 265 ng/mL (r 2  > 0.999) with a lower limit of detection (LLOD) of 2.65 ng/mL and a lower limit of quantification (LLOQ) of 5.3 ng/mL. The intra-day and inter-day accuracy and precision of RD2 in plasma ranged from -0.54% to 2.21% and from 1.97% to 8.18%, respectively. Moreover, no matrix effects were observed and RD2 remained stable in extracted mouse plasma at different conditions. Using this validated bioanalytical method, plasma samples of unlabeled RD2 or placebo treated mice were analyzed. The herein developed UHPLC-ESI-QTOF-MS method is a suitable tool for the quantitative analysis of unlabeled RD2 in plasma samples of treated mice. Copyright © 2017 Elsevier B.V. All rights reserved.

The influence of addition of ion-pairing acid and organic modifier of the mobile phase on retention and migration of peptides in pressurized planar electrochromatography system with octadecyl silica-based adsorbent.

PubMed

Gwarda, Radosław Ł; Dzido, Tadeusz H

2018-07-13

In our previous papers we have investigated the influence of the mobile phase composition on mechanism of retention, selectivity and efficiency of peptide separation in various high-performance thin-layer chromatography (HPTLC) systems with commercially available silica-based adsorbents. We have also investigated the influence of pH of the mobile phase buffer on migration and separation of peptides in pressurized planar electrochromatography (PPEC). Here we investigate the influence of concentration of ion-pairing additive, and concentration and type of organic modifier of the mobile phase on migration of peptides in PPEC system with octadecyl silica-based adsorbent, and with the same set of the solutes as before. We compare our current results with the results obtained before for similar HPTLC and PPEC systems, and discuss the influence of particular variables on retention, electrophoretic mobility of solutes and electroosmotic flow of the mobile phase. We show, that the final selectivity of peptide separation results from co-influence of all the three factors mentioned. Concentration of organic modifier of the mobile phase, as well as concentration of ion-pairing additive, affect the retention, the electrophoretic mobility, and the electroosmotic flow simultaneously. This makes independent optimization of these factors rather difficult. Anyway PPEC offers much faster separation of peptides with quite different selectivity, in comparison to HPTLC, with similar adsorbents and similar mobile phase composition. However, we also present and discuss the issue of extensive tailing of peptide zones in the PPEC in comparison to similar HPTLC systems. Copyright © 2018 Elsevier B.V. All rights reserved.

Effect of enzyme on extraction of ginsenoside Rb1 and Rg3 from Panax notoginseng roots

NASA Astrophysics Data System (ADS)

Phuong, Nguyen Tran Xuan; Thy, Lu Thi Mong; Khang, Nguyen Luu Vinh; My, Huynh Thi Kieu; Tam, Nguyen Le Phuong; Hieu, Nguyen Huu

2018-04-01

Panax notoginseng is distributed throughout the north and northwest of Vietnam, especially Ha Giang, Lao Cai, and Cao Bang provinces. The root of this plant contains ginsenosides (Rb1, Rb2, Rd, Rg3), flavonoids, polyacetylene, polysaccharides, amino acids, fatty acids, and peptides. In this study, the ratios of enzyme (Viscozyme, Termamyl, Cellulase), solvent of components, and time extraction were investigated. The results showed that the highest contents of Rb1 and Rg3 were achieved in the sample extracted with the ratio of enzymes V:C:T = 1:0:0, ethanol:water (60:40, v/v) as extracting solvent in 45 minutes. Then, conditions of high performance liquid chromatography with diode array detector method to determine the content of ginsenosides Rb1 and Rg3 in the roots of Panax notoginseng were studied, including wavelength, mobile phase, and flow rate. The separation was subjected on a reversed-phase C18 column using acetonitrile (A) and water (B) as mobile phase. The gradient elution was set as follow: 0-10 min, 15-25% A; 10-20 min, 25-30% A; 20-40 min, 30-60% A; 40-60 min, 60-80% A; and 60-65 min back to 15% A before the next injection, at a flow rate of 0.5 mL/min, and the wavelength was set at 202 nm. The linear range was from 298.59 to 696.72 µg/mL for Rb1 and from 8.19 to 19.10 µg/L for Rg3. The limits of detection for Rb1 and Rg3 obtained were 0.31 µg/mL and 0.33 µg/mL, respectively. The limits of quantification were 0.95 µg/mL and 1.01 µg/mL for Rb1 and Rg3, respectively. Consequently, the high performance liquid chromatography demonstrated the highly sensitive and accurate method for determination of Rb1 and Rg3 in Panax notoginseng.

Geographic Mobility of Postsecondary Occupational Education Graduates. Phase II.

ERIC Educational Resources Information Center

Winter, Gene M.; Fadale, LaVerna M.

This report of the second phase of a study of the geographic mobility patterns of postsecondary occupational education graduates in New York State provides a further examination of reasons for the mobility of program completers, verifies the general magnitude of the identified mobility trends, and examines the occupational status of program…

High-performance liquid chromatographic separations of stereoisomers of chiral basic agrochemicals with polysaccharide-based chiral columns and polar organic mobile phases.

PubMed

Matarashvili, Iza; Shvangiradze, Iamze; Chankvetadze, Lali; Sidamonidze, Shota; Takaishvili, Nino; Farkas, Tivadar; Chankvetadze, Bezhan

2015-12-01

The separation of the stereoisomers of 23 chiral basic agrochemicals was studied on six different polysaccharide-based chiral columns in high-performance liquid chromatography with various polar organic mobile phases. Along with the successful separation of analyte stereoisomers, emphasis was placed on the effect of the chiral selector and mobile phase composition on the elution order of stereoisomers. The interesting phenomenon of reversal of enantiomer/stereoisomer elution order function of the polysaccharide backbone (cellulose or amylose), type of derivative (carbamate or benzoate), nature, and position of the substituent(s) in the phenylcarbamate moiety (methyl or chloro) and the nature of the mobile phase was observed. For several of the analytes containing two chiral centers all four stereoisomers were resolved with at least one chiral selector/mobile phase combination. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Characterization and Quantification of Intact 26S Proteasome Proteins by Real-Time Measurement of Intrinsic Fluorescence Prior to Top-down Mass Spectrometry

PubMed Central

Russell, Jason D.; Scalf, Mark; Book, Adam J.; Ladror, Daniel T.; Vierstra, Richard D.; Smith, Lloyd M.; Coon, Joshua J.

2013-01-01

Quantification of gas-phase intact protein ions by mass spectrometry (MS) is impeded by highly-variable ionization, ion transmission, and ion detection efficiencies. Therefore, quantification of proteins using MS-associated techniques is almost exclusively done after proteolysis where peptides serve as proxies for estimating protein abundance. Advances in instrumentation, protein separations, and informatics have made large-scale sequencing of intact proteins using top-down proteomics accessible to the proteomics community; yet quantification of proteins using a top-down workflow has largely been unaddressed. Here we describe a label-free approach to determine the abundance of intact proteins separated by nanoflow liquid chromatography prior to MS analysis by using solution-phase measurements of ultraviolet light-induced intrinsic fluorescence (UV-IF). UV-IF is measured directly at the electrospray interface just prior to the capillary exit where proteins containing at least one tryptophan residue are readily detected. UV-IF quantification was demonstrated using commercially available protein standards and provided more accurate and precise protein quantification than MS ion current. We evaluated the parallel use of UV-IF and top-down tandem MS for quantification and identification of protein subunits and associated proteins from an affinity-purified 26S proteasome sample from Arabidopsis thaliana. We identified 26 unique proteins and quantified 13 tryptophan-containing species. Our analyses discovered previously unidentified N-terminal processing of the β6 (PBF1) and β7 (PBG1) subunit - such processing of PBG1 may generate a heretofore unknown additional protease active site upon cleavage. In addition, our approach permitted the unambiguous identification and quantification both isoforms of the proteasome-associated protein DSS1. PMID:23536786

Characterization and quantification of intact 26S proteasome proteins by real-time measurement of intrinsic fluorescence prior to top-down mass spectrometry.

PubMed

Russell, Jason D; Scalf, Mark; Book, Adam J; Ladror, Daniel T; Vierstra, Richard D; Smith, Lloyd M; Coon, Joshua J

2013-01-01

Quantification of gas-phase intact protein ions by mass spectrometry (MS) is impeded by highly-variable ionization, ion transmission, and ion detection efficiencies. Therefore, quantification of proteins using MS-associated techniques is almost exclusively done after proteolysis where peptides serve as proxies for estimating protein abundance. Advances in instrumentation, protein separations, and informatics have made large-scale sequencing of intact proteins using top-down proteomics accessible to the proteomics community; yet quantification of proteins using a top-down workflow has largely been unaddressed. Here we describe a label-free approach to determine the abundance of intact proteins separated by nanoflow liquid chromatography prior to MS analysis by using solution-phase measurements of ultraviolet light-induced intrinsic fluorescence (UV-IF). UV-IF is measured directly at the electrospray interface just prior to the capillary exit where proteins containing at least one tryptophan residue are readily detected. UV-IF quantification was demonstrated using commercially available protein standards and provided more accurate and precise protein quantification than MS ion current. We evaluated the parallel use of UV-IF and top-down tandem MS for quantification and identification of protein subunits and associated proteins from an affinity-purified 26S proteasome sample from Arabidopsis thaliana. We identified 26 unique proteins and quantified 13 tryptophan-containing species. Our analyses discovered previously unidentified N-terminal processing of the β6 (PBF1) and β7 (PBG1) subunit - such processing of PBG1 may generate a heretofore unknown additional protease active site upon cleavage. In addition, our approach permitted the unambiguous identification and quantification both isoforms of the proteasome-associated protein DSS1.

Capillary liquid chromatography combined with pressurized liquid extraction and dispersive liquid-liquid microextraction for the determination of vitamin E in cosmetic products.

PubMed

Viñas, Pilar; Pastor-Belda, Marta; Campillo, Natalia; Bravo-Bravo, María; Hernández-Córdoba, Manuel

2014-06-01

Capillary liquid chromatography (LC) is used for the determination of tocopherols and tocotrienols in cosmetic products. Dispersive liquid-liquid microextraction (DLLME) allows the analytes to be preconcentrated into a very small volume of organic solvent which is then injected into the chromatograph running at a very low flow rate. Pressurized liquid extraction (PLE) at a high temperature and pressure was used to isolate vitamin E forms from cosmetics. The Taguchi experimental method was used to optimize the factors affecting DLLME. The parameters selected were 2mL of acetonitrile (disperser solvent), 100μL carbon tetrachloride (extraction solvent) and 10mL aqueous solution. A volume of 5μL of the organic phase was injected into the reversed-phase capillary LC system equipped with a diode array detector and using an isocratic mobile phase composed of an 95:5 (v/v) methanol:water mixture at a flow-rate of 20μLmin(-1). Quantification was carried out using aqueous standards and detection limits were in the range 0.1-0.5ngmL(-1), corresponding to 3-15ngg(-1) in the cosmetic sample. The recoveries were in the 87-105% range, with RSDs lower than 7.8%. The method was validated according to international guidelines and using a certified reference material. Copyright © 2014 Elsevier B.V. All rights reserved.

Methods of analysis by the U.S. Geological Survey Organic Geochemistry Research Group; determination of glyphosate, aminomethylphosphonic acid, and glufonsinate in water using online solid-phase extraction and high-performance liquid chromat

USGS Publications Warehouse

Lee, E.A.; Strahan, A.P.; Thurman, E.M.

2001-01-01

An analytical method for the determination of glyphosate, its principal degradation compound, aminomethylphosphonic acid (AMPA), and glufosinate in water with varying matrices has been developed. Four different sample matrices fortified at 0.2 and 2.0 ?g/L (micrograms per liter) were analyzed using precolumn derivatization with 9-fluorenylmethylchloroformate (FMOC). After derivatization, cleanup and concentration were accomplished using automated online solid-phase extraction followed by elution with the mobile phase allowing for direct injection into a liquid chromatograph/mass spectrometer (LC/MS). Analytical conditions for MS detection were optimized, and quantitation was carried out using the following representative ions: 390 and 168 for glyphosate; 332, 110, and 136 for AMPA; and 402, 180, and 206 for glufosinate. Matrix effects were minimized by utilizing standard addition for quantification and an isotope-labeled glyphosate (2-13C,15N) as the internal standard. Method detection limits (MDLs) were 0.084 ?g/L for glyphosate, 0.078 ?g/L for AMPA, and 0.057 ?g/L for glufosinate. The method reporting limits (MRLs) were set at 0.1 ?g/L for all three compounds. The mean recovery values ranged from 88.0 to 128.7 percent, and relative standard deviation values ranged from 5.6 to 32.6 percent.

Development and evaluation of a hydrophilic interaction liquid chromatography-MS/MS method to quantify 19 nucleobases and nucleosides in rat plasma.

PubMed

Du, Yan; Li, Yin-Jie; Hu, Xun-Xiu; Deng, Xu; Qian, Zeng-Ting; Li, Zheng; Guo, Meng-Zhe; Tang, Dao-Quan

2017-04-01

As essential endogenous compounds, nucleobases and nucleosides fulfill various functions in living organisms. This study presents the development and validation of a new hydrophilic interaction liquid chromatography tandem mass spectrometry method for simultaneous quantification of 19 nucleobases and nucleosides in rat plasma. For the sample preparation, 15 kinds of protein precipitants were evaluated according to the chromatographic profile and ion response of analytes. The optimization of chromatographic separation was respectively performed using reversed-phase liquid chromatography and hydrophilic interaction liquid chromatography mode; each separation mode included two test columns with different stationary phases. The chromatographic profile and parameters such as half-width (W 1/2 ), capacity factor (K') and tailing factor (f t ) were used to evaluate the separation efficiencies. Furthermore, the adopted composition of two mobile phase systems and the concentrations of the additives in the optimum buffer system were also investigated. The developed method was fully validated and successfully applied quantitatively to determine 19 nucleobases and nucleosides in plasma from normal and diabetic nephropathy (DN) rats. Significant differences between normal and DN rats were found in plasma levels of cytosine, xanthine, thymidine, adenosine, guanosine, inosine and 8-hydroxy-2'-deoxyguanosine. This information may provide a useful reference for the discovery of potential biomarkers of DN. Copyright © 2016 John Wiley & Sons, Ltd.

Development and validation of a reversed-phase high-performance thin-layer chromatography-densitometric method for determination of atorvastatin calcium in bulk drug and tablets.

PubMed

Shirkhedkar, Atul A; Surana, Sanjay J

2010-01-01

Atorvastatin calcium is a synthetic HMG-CoA reductase inhibitor that is used as a cholesterol-lowering agent. A simple, sensitive, selective, and precise RP-HPTLC-densitometric determination of atorvastatin calcium both as bulk drug and from pharmaceutical formulation was developed and validated according to International Conference on Harmonization guidelines. The method used aluminum sheets precoated with silica gel 60 RP18F254S as the stationary phase, and the mobile phase consisted of methanol-water (3.5 + 1.5, v/v). The system gave a compact band for atorvastatin calcium with an Rf value of 0.62 +/- 0.02. Densitometric quantification was carried out at 246 nm. The linear regression analysis data for the calibration plots showed a good linear relationship with r = 0.9992 in the working concentration range of 100-800 ng/band. The method was validated for precision, accuracy, ruggedness, robustness, specificity, recovery, LOD, and LOQ. The LOD and LOQ were 6 and 18 ng, respectively. The drug underwent hydrolysis when subjected to acidic conditions and was found to be stable under alkali, oxidation, dry heat, and photodegradation conditions. Statistical analysis proved that the developed RP-HPTLC-densitometry method is reproducible and selective and that it can be applied for identification and quantitative determination of atorvastatin calcium in bulk drug and tablet formulation.

Development and validation of reversed-phase HPLC gradient method for the estimation of efavirenz in plasma.

PubMed

Gupta, Shweta; Kesarla, Rajesh; Chotai, Narendra; Omri, Abdelwahab

2017-01-01

Efavirenz is an anti-viral agent of non-nucleoside reverse transcriptase inhibitor category used as a part of highly active retroviral therapy for the treatment of infections of human immune deficiency virus type-1. A simple, sensitive and rapid reversed-phase high performance liquid chromatographic gradient method was developed and validated for the determination of efavirenz in plasma. The method was developed with high performance liquid chromatography using Waters X-Terra Shield, RP18 50 x 4.6 mm, 3.5 μm column and a mobile phase consisting of phosphate buffer pH 3.5 and Acetonitrile. The elute was monitored with the UV-Visible detector at 260 nm with a flow rate of 1.5 mL/min. Tenofovir disoproxil fumarate was used as internal standard. The method was validated for linearity, precision, accuracy, specificity, robustness and data obtained were statistically analyzed. Calibration curve was found to be linear over the concentration range of 1-300 μg/mL. The retention times of efavirenz and tenofovir disoproxil fumarate (internal standard) were 5.941 min and 4.356 min respectively. The regression coefficient value was found to be 0.999. The limit of detection and the limit of quantification obtained were 0.03 and 0.1 μg/mL respectively. The developed HPLC method can be useful for quantitative pharmacokinetic parameters determination of efavirenz in plasma.

Prediction of peak shape in hydro-organic and micellar-organic liquid chromatography as a function of mobile phase composition.

PubMed

Baeza-Baeza, J J; Ruiz-Angel, M J; García-Alvarez-Coque, M C

2007-09-07

A simple model is proposed that relates the parameters describing the peak width with the retention time, which can be easily predicted as a function of mobile phase composition. This allows the further prediction of peak shape with global errors below 5%, using a modified Gaussian model with a parabolic variance. The model is useful in the optimisation of chromatographic resolution to assess an eventual overlapping of close peaks. The dependence of peak shape with mobile phase composition was studied for mobile phases containing acetonitrile in the presence and absence of micellised surfactant (micellar-organic and hydro-organic reversed-phase liquid chromatography, RPLC). In micellar RPLC, both modifiers (surfactant and acetonitrile) were observed to decrease or improve the efficiencies in the same percentage, at least in the studied concentration ranges. The study also revealed that the problem of achieving smaller efficiencies in this chromatographic mode, compared to hydro-organic RPLC, is not only related to the presence of surfactant covering the stationary phase, but also to the smaller concentration of organic solvent in the mobile phase.

43 CFR 11.71 - Quantification phase-service reduction quantification.

Code of Federal Regulations, 2012 CFR

2012-10-01

... identified geohydrological units, which are aquifers or confining layers, within the assessment area. (2)(i... determined by determining: (1) The surface area of soil with reduced ability to sustain the growth of vegetation from the baseline level; (2) The surface area or volume of soil with reduced suitability as...

43 CFR 11.71 - Quantification phase-service reduction quantification.

Code of Federal Regulations, 2013 CFR

2013-10-01

... identified geohydrological units, which are aquifers or confining layers, within the assessment area. (2)(i... determined by determining: (1) The surface area of soil with reduced ability to sustain the growth of vegetation from the baseline level; (2) The surface area or volume of soil with reduced suitability as...

43 CFR 11.71 - Quantification phase-service reduction quantification.

Code of Federal Regulations, 2014 CFR

2014-10-01

... identified geohydrological units, which are aquifers or confining layers, within the assessment area. (2)(i... determined by determining: (1) The surface area of soil with reduced ability to sustain the growth of vegetation from the baseline level; (2) The surface area or volume of soil with reduced suitability as...

Comparison of the peak resolution and the stationary phase retention between the satellite and the planetary motions using the coil satellite centrifuge with counter-current chromatographic separation of 4-methylumbelliferyl sugar derivatives.

PubMed

Shinomiya, Kazufusa; Zaima, Kazumasa; Harada, Yukina; Yasue, Miho; Harikai, Naoki; Tokura, Koji; Ito, Yoichiro

2017-01-20

Coil satellite centrifuge (CSC) produces the complex satellite motion consisting of the triplicate rotation of the coiled column around three axes including the sun axis (the angular velocity, ω 1 ), the planet axis (ω 2 ) and the satellite axis (the central axis of the column) (ω 3 ) according to the following formula: ω 1 =ω 2 +ω 3 . Improved peak resolution in the separation of 4-methylumbelliferyl sugar derivatives was achieved using the conventional multilayer coiled columns with ethyl acetate/1-butanol/water (3: 2: 5, v/v) for the lower mobile phase at the combination of the rotation speeds (ω 1 , ω 2 , ω 3 )=(300, 150, 150rpm), and (1:4:5, v/v) for the upper mobile phase at (300:100:200rpm). The effect of the satellite motion on the peak resolution and the stationary phase retention was evaluated by each CSC separation with the different rotation speeds of ω 2 and ω 3 under the constant revolution speed at ω 1 =300rpm. With the lower mobile phase, almost constant peak resolution and stationary phase retention were yielded regardless of the change of ω 2 and ω 3 , while with the upper mobile phase these two values were sensitively varied according to the different combination of ω 2 and ω 3 . For example, when ω 2 =147 or 200rpm is used, no stationary phase was retained in the coiled column while ω 2 =150rpm could retain enough volume of stationary phase for separation. On the other hand, the combined rotation speeds at (ω 1 , ω 2 , ω 3 )=(300, 300, 0rpm) or (300, 0, 300rpm) produced insufficient peak resolution regardless of the choice of the mobile phase apparently due to the lack of rotation speed except at (300, 0, 300rpm) with the upper mobile phase. At lower rotation speed of ω 1 =300rpm, better peak resolution and stationary phase retention were obtained by the satellite motion (ω 3 ) than by the planetary motion (ω 2 ), or ω 3 >ω 2 . The effect of the hydrophobicity of the two-phase solvent systems on the stationary phase retention was further examined using the n-hexane/ethyl acetate/1-butanol/methanol/water system at different volume ratios. In the satellite motion at (ω 1 , ω 2 , ω 3 )=(300, 150, 150rpm), almost constant stationary phase retention was obtained with the lower mobile phase regardless of the hydrophobicity of the solvent system whereas the stationary phase retention varied according to the volume ratio of the two-phase solvent system for the upper mobile phase. However, stable stationary phase retention was observed with either phase used as the mobile phase. In order to analyze the acceleration acting on the coiled column, an acceleration sensor was set on the column holder by displacing the multilayer column. The combination of the rotation speeds at (300, 100, 200rpm) showed double loops in the acceleration track, whereas (300, 150, 150rpm) showed a single loop, and all other combinations showed, complex tracks. The overall results indicate that the satellite motion is seriously affected by the combination of rotation speeds and the hydrophobicity of the two-phase solvent system when the upper phase was used as the mobile phase for separation. Copyright © 2016 Elsevier B.V. All rights reserved.

Comparison of the peak resolution and the stationary phase retention between the satellite and the planetary motions using the coil satellite centrifuge with counter-current chromatographic separation of 4-methylumbelliferyl sugar derivatives

PubMed Central

Shinomiya, Kazufusa; Zaima, Kazumasa; Harada, Yukina; Yasue, Miho; Harikai, Naoki; Tokura, Koji; Ito, Yoichiro

2016-01-01

Coil satellite centrifuge (CSC) produces the complex satellite motion consisting of the triplicate rotation of the coiled column around three axes including the sun axis (the angular velocity, ω1), the planet axis (ω2) and the satellite axis (the central axis of the column) (ω3) according to the following formula: ω1 = ω2 + ω3. Improved peak resolution in the separation of 4-methylumbelliferyl sugar derivatives was achieved using the conventional multilayer coiled columns with ethyl acetate/1-butanol/water (3 : 2 : 5, v/v) for the lower mobile phase at the combination of the rotation speeds (ω1, ω2, ω3) = (300, 150, 150 rpm), and (1 : 4 : 5, v/v) for the upper mobile phase at (300 : 100 : 200 rpm). The effect of the satellite motion on the peak resolution and the stationary phase retention was evaluated by each CSC separation with the different rotation speeds of ω2 and ω3 under the constant revolution speed at ω1 = 300 rpm. With the lower mobile phase, almost constant peak resolution and stationary phase retention were yielded regardless of the change of ω2 and ω3, while with the upper mobile phase these two values were sensitively varied according to the different combination of ω2 and ω3. For example, when ω2 = 147 or 200 rpm is used, no stationary phase was retained in the coiled column while ω2 = 150 rpm could retain enough volume of stationary phase for separation. On the other hand, the combined rotation speeds at (ω1, ω2, ω3) = (300, 300, 0 rpm) or (300, 0, 300 rpm) produced insufficient peak resolution regardless of the choice of the mobile phase apparently due to the lack of rotation speed except at (300, 0, 300 rpm) with the upper mobile phase. At lower rotation speed of ω1 = 300 rpm, better peak resolution and stationary phase retention were obtained by the satellite motion (ω3) than by the planetary motion (ω2), or ω3 > ω2. The effect of the hydrophobicity of the two-phase solvent systems on the stationary phase retention was further examined using the n-hexane/ethyl acetate/1-butanol/methanol/water system at different volume ratios. In the satellite motion at (ω1, ω2, ω3) = (300, 150, 150 rpm), almost constant stationary phase retention was obtained with the lower mobile phase regardless of the hydrophobicity of the solvent system whereas the stationary phase retention varied according to the volume ratio of the two-phase solvent system for the upper mobile phase. However, stable stationary phase retention was observed with either phase used as the mobile phase. In order to analyze the acceleration acting on the coiled column, an acceleration sensor was set on the column holder by displacing the multilayer column. The combination of the rotation speeds at (300, 100, 200 rpm) showed double loops in the acceleration track, whereas (300, 150, 150 rpm) showed a single loop, and all other combinations showed, complex tracks. The overall results indicate that the satellite motion is seriously affected by the combination of rotation speeds and the hydrophobicity of the two-phase solvent system when the upper phase was used as the mobile phase for separation. PMID:28040269

Development of Mobile Tracer Correlation Strategies for Quantification of Emissions from Landfills and Other Large Area Sources

EPA Science Inventory

Emission measurements from large area sources such as landfills are complicated by their spatial extent and heterogeneous nature. In recent years, an on-site optical remote sensing (ORS) technique for characterizing emissions from area sources was described in an EPA-published p...

Development of Mobile Tracer Correlation Method for Quantification of Emissions from Landfills and Other Large Area Sources

EPA Science Inventory

There is an emerging need to develop cost effective measurement methods for greenhouse gas and air pollutant emissions from large area sources such as landfills, waste water treatment ponds, open area processing units, agricultural operations, CO2 sequestration fields, and site r...

Development of Mobile Tracer Correlation Approach for Quantification of Emissions from Landfills and Other Large Area Sources

EPA Science Inventory

There is a recognized need to develop cost effective measurement methods for greenhouse gas and air pollutant emissions from large area sources such as landfills, waste water treatment ponds, open area processing units, agricultural operations, CO2 sequestration fields, and site ...

Effects of elevated temperature and mobile phase composition on a novel C18 silica column.

PubMed

Lippert, J Andreas; Johnson, Todd M; Lloyd, Jarem B; Smith, Jared P; Johnson, Bryce T; Furlow, Jason; Proctor, Angela; Marin, Stephanie J

2007-05-01

A novel polydentate C18 silica column was evaluated at an elevated temperature under acidic, basic, and neutral mobile phase conditions using ACN and methanol as the mobile phase organic modifier. The temperature range was 40-200 degrees C. The mobile phase compositions were from 0 to 80% organic-aqueous v/v and the mobile phase pH levels were between 2 and 12. The maximum operating temperature of the column was affected by the amount and type of organic modifier used in the mobile phase. Under neutral conditions, the column showed good column thermal stability at temperatures ranging between 120 and 200 degrees C in methanol-water and ACN-water solvent systems. At pH 2 and 3, the column performed well up to about 160 degrees C at two fixed ACN-buffer compositions. Under basic conditions at elevated temperatures, the column material deteriorated more quickly, but still remained stable up to 100 degrees C at pH 9 and 60 degrees C at pH 10. The results of this study indicate that this novel C18 silica-based column represents a significant advancement in RPLC column technology with enhanced thermal and pH stability when compared to traditional bonded phase silica columns.

[Influence of mobile phase composition on chiral separation of organic selenium racemates].

PubMed

Han, Xiao-qian; Qi, Bang-feng; Dun, Hui-juan; Zhu, Xin-yi; Na, Peng-jun; Jiang, Sheng-xiang; Chen, Li-ren

2002-05-01

The chiral separation of some chiral compounds with similar structure on the cellulose tris (3,5-dimethylphenylcarbamate) chiral stationary phase prepared by us was obtained. Ternary mobile phases influencing chiral recognition were investigated. A mode of interaction between the structural character of samples and chiral stationary phase is discussed. The results indicated that the retention and chiral separation of the analytes had a bigger change with minute addition of alcohols or acetonitrile as modifier in n-hexane/2-propanol (80/20, volume ratio) binary mobile phase.

Simultaneous Quantification of Forskolin and Iso-Forskolin in Coleus forskohlii (Wild.) Briq. and Identification of Elite Chemotype, Collected from Eastern Ghats (India).

PubMed

Shukla, Pushpendra Kumar; Misra, Ankita; Kumar, Manish; Jaichand; Singh, Kuldeep; Akhtar, Juber; Srivastava, Sharad; Agrawal, Pawan K; Singh Rawat, Ajay K

2018-01-01

Coleus forskohlii is a well-known industrially important medicinal plant, for its high forskolin content. A simple, selective, and sensitive high-performance thin layer chromatography (HPTLC) method was developed and validated for simultaneous quantification of forskolin and iso-forskolin in C. forskohlii germplasm collected from the Eastern Ghats, India. Chromatographic separation of the targeted marker(s) was obtained on precoated silica plates using toluene: ethyl acetate: methanol (90:30:0.5, v/v/v) as the mobile phase. Densitometric quantification of forskolin and iso-forskolin was carried out at 545 nm. Forskolin and iso-forskolin were identified by comparing the ultraviolet spectra of standard and sample track at R f of 0.64 ± 0.02 and 0.36 ± 0.01, after derivatization with anisaldehyde sulfuric acid reagent. The linearity of both the analytes was obtained in the range of 300-1200 ng/spot with the regression coefficient ( R 2 ) of 0.991 and 0.986. Recovery of analyte (s) at three levels, namely, 100, 150, and 200 ng/spot was found to be 100.46% ± 0.29%, 99.64% ± 0.33%, 100.02% ± 0.76% and 99.76% ± 0.62%, 99.56% ± 0.35%, 100.02% ± 0.22%, respectively, for forskolin and iso-forskolin. The content of forskolin and iso-forskolin varies from 0.046% to 0.187% and 0.002% to 0.077%, respectively (dry weight basis), the maximum content of both the markers was found in NBC-31, from Thakurwada, Maharashtra. The developed HPTLC method was linear, accurate, and reliable as per the International Council for Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use guidelines. The study aids in the identification of elite chemotype for commercial prospection of industrially viable medicinal crop. 12 Samples are collected from different locations of the eastern ghat regionsQuantification of two major marker forskolin and iso forskolinThe maximum content of both the markers was found in NBC -31, from Thakurwada, MaharashtraIdentification of elite chemotype of collected samples may be useful for commercial prospection in industries.

Near-source mobile methane emission estimates using EPA Method33a and a novel probabilistic approach as a basis for leak quantification in urban areas

NASA Astrophysics Data System (ADS)

Albertson, J. D.

2015-12-01

Methane emissions from underground pipeline leaks remain an ongoing issue in the development of accurate methane emission inventories for the natural gas supply chain. Application of mobile methods during routine street surveys would help address this issue, but there are large uncertainties in current approaches. In this paper, we describe results from a series of near-source (< 30 m) controlled methane releases where an instrumented van was used to measure methane concentrations during both fixed location sampling and during mobile traverses immediately downwind of the source. The measurements were used to evaluate the application of EPA Method 33A for estimating methane emissions downwind of a source and also to test the application of a new probabilistic approach for estimating emission rates from mobile traverse data.

Determination and identification of malathion, ethion and dichlorovos using ion mobility spectrometry.

PubMed

Jafari, Mohammad T

2006-07-15

Positive ion mobility spectra of different organophosphorus pesticides such as malathion (s-(1,2-dicarb-ethoxyethyl) o,o-dimethyl dithiophosphate), ethion (o,o,o',o'-tetraethyl s,s'-methylene bis(phosphorodithioate)) and dichlorovos (2,2-dichlorovinyl dimethyl phosphate) have been studied in air at ambient pressure using ion mobility spectrometry method with (63)Ni ionization source. The limits of quantification (LOQs) were 1.0 x 10(-9), 1.0 x 10(-9) and 5.0 x 10(-9)g for malathion, ethion and dichlorovos, respectively. The working range of these compounds was about three orders of magnitude and the relative standard deviation (R.S.D.) of repeatability at the 5 microg ml(-1) level were all below 15%. Furthermore, in this study, the influences of IMS cell temperature on the ion mobility spectra of these compounds were investigated.

Project inspection using mobile technology - phase II : assessing the impacts of mobile technology on project inspection.

DOT National Transportation Integrated Search

2015-01-01

As mobile technology becomes widely available and affordable, transportation agencies can use this : technology to streamline operations involved within project inspection. This research, conducted in two : phases, identified opportunities for proces...

Offline solid-phase extraction for preconcentration of pharmaceuticals and personal care products in environmental water and their simultaneous determination using the reversed phase high-performance liquid chromatography method.

PubMed

G Archana; Dhodapkar, Rita; Kumar, Anupama

2016-09-01

The present study reports a precise and simple offline solid-phase extraction (SPE) coupled with reversed-phase high-performance liquid chromatography (RP-HPLC) method for the simultaneous determination of five representative and commonly present pharmaceuticals and personal care products (PPCPs), a new class of emerging pollutants in the aquatic environment. The target list of analytes including ciprofloxacin, acetaminophen, caffeine benzophenone and irgasan were separated by a simple HPLC method. The column used was a reversed-phase C18 column, and the mobile phase was 1 % acetic acid and methanol (20:80 v/v) under isocratic conditions, at a flow rate of 1 mL min(-1). The analytes were separated and detected within 15 min using the photodiode array detector (PDA). The linearity of the calibration curves were obtained with correlation coefficients 0.98-0.99.The limit of detection (LOD), limit of quantification (LOQ), precision, accuracy and ruggedness demonstrated the reproducibility, specificity and sensitivity of the developed method. Prior to the analysis, the SPE was performed using a C18 cartridge to preconcentrate the targeted analytes from the environmental water samples. The developed method was applied to evaluate and fingerprint PPCPs in sewage collected from a residential engineering college campus, polluted water bodies such as Nag river and Pili river and the influent and effluent samples from a sewage treatment plant (STP) situated at Nagpur city, in the peak summer season. This method is useful for estimation of pollutants present in microquantities in the surface water bodies and treated sewage as compared to nanolevel pollutants detected by mass spectrometry (MS) detectors.

Hydrophilic interaction liquid chromatography in analysis of granisetron HCl and its related substances. Retention mechanisms and method development.

PubMed

Maksić, Jelena; Tumpa, Anja; Stajić, Ana; Jovanović, Marko; Rakić, Tijana; Jančić-Stojanović, Biljana

2016-05-10

In this paper separation of granisetron and its two related substances in HILIC mode is presented. Separation was done on silica column derivatized with sulfoalkylbetaine groups (ZIC-HILIC). Firstly, retention mechanisms were assessed whereby retention factors of substances were followed in wide range of acetonitrile content (80-97%), at constant concentration of aqueous buffer (10mM) as well as at constant pH value of 3.0. Further, in order to developed optimal HILIC method, Design of Experiments (DoE) methodology was applied. For optimization full factorial design 3(2) was employed. Influence of acetonitrile content and ammonium acetate concentration were investigated while pH of the water phase was kept at 3.3. Adequacy of obtained mathematical models was confirmed by ANOVA. Optimization goals (α>1.15 and minimal run time) were accomplished with 94.7% of acetonitrile in mobile phase and 70 mM of ammonium acetate in water phase. Optimal point was in the middle of defined Design Space. In the next phase, robustness was experimetally tested by Rechtschaffen design. The investigated factors and their levels were: acetonitrile content (±1%), ammonium acetate molarity in water phase (±2 mM), pH value of water phase (±0.2) and column temperature (±4 °C). The validation scope included selectivity, linearity, accuracy and precision as well as determination of limit of detection (LOD) and limit of quantification (LOQ) for the related substances. Additionally, the validation acceptance criteria were met in all cases. Finally, the proposed method could be successfully utilized for estimation of granisetron HCl and its related substances in tablets and parenteral dosage forms, as well as for monitoring degradation under various stress conditions. Copyright © 2016 Elsevier B.V. All rights reserved.

Persistent Homology to describe Solid and Fluid Structures during Multiphase Flow

NASA Astrophysics Data System (ADS)

Herring, A. L.; Robins, V.; Liu, Z.; Armstrong, R. T.; Sheppard, A.

2017-12-01

The question of how to accurately and effectively characterize essential fluid and solid distributions and structures is a long-standing topic within the field of porous media and fluid transport. For multiphase flow applications, considerable research effort has been made to describe fluid distributions under a range of conditions; including quantification of saturation levels, fluid-fluid pressure differences and interfacial areas, and fluid connectivity. Recent research has effectively used topological metrics to describe pore space and fluid connectivity, with researchers demonstrating links between pore-scale nonwetting phase topology to fluid mobilization and displacement mechanisms, relative permeability, fluid flow regimes, and thermodynamic models of multiphase flow. While topology is clearly a powerful tool to describe fluid distribution, topological metrics by definition provide information only on the connectivity of a phase, not its geometry (shape or size). Physical flow characteristics, e.g. the permeability of a fluid phase within a porous medium, are dependent on the connectivity of the pore space or fluid phase as well as the size of connections. Persistent homology is a technique which provides a direct link between topology and geometry via measurement of topological features and their persistence from the signed Euclidean distance transform of a segmented digital image (Figure 1). We apply persistent homology analysis to measure the occurrence and size of pore-scale topological features in a variety of sandstones, for both the dry state and the nonwetting phase fluid during two-phase fluid flow (drainage and imbibition) experiments, visualized with 3D X-ray microtomography. The results provide key insights into the dominant topological features and length scales of a media which control relevant field-scale engineering properties such as fluid trapping, absolute permeability, and relative permeability.

Report: An ex vivo up-take of levamisole molecules by cestode (Monezia expensa) of goat (Capra hirsa) and its detection through RP-HPLC.

PubMed

Ayaz, Muhammad Mazhar; Sajid, Muhammad; Das, Sanjota Nirmal; Hanif, Muhammad

2018-05-01

Detection of various molecules of drugs remained a prime issue especially in tissues of animals, humans and in their target parasites. The cestode/tapeworms pose a dilemma because of their weird body composition and uptake pattern of nutrients and medicines especially through absorption by tegument. We selected levamisole; thought to be potent antiparasitic/ani-cestodal drug. The uptake of levamisole (LEV) through cestodeal tissues is studied through HPCL in this paper. High performance liquid chromatography technique has been utilized to know the uptake of levamisole in tissues of cestodes of Goat (Monezia expensa) in small ruminants. The drug was exposed to M. expensa by in vitro till its death or a parasite ceases its movement. The tissue/ part of proglattids of the M. expensa were homogenized with some modifications and levamisole extraction was performed with liquid phase extraction method. The evaporation of solvent was done and the residual cestodal tissues were cleaned by solid phase. After the solid phase extraction method, the recovery of drug, detection and quantification of levamisole from cestodal tissues was determined through Reverse Phase Column High Performance Liquid Chromatography (RP-HPLC). Levamisole (LEV) molecules assay was obtained on a C18 reverse-phase (20um, 6mm x 150mm) column at flow rate of 1ml/min using acetonitrile and ammonium acetate as mobile phase and UV detection was done at 254nm. The development of method of Levamisole (LEV) detection from cestodal tissues by HPLC in vitro samples has been demonstrated first time in Pakistan, which can provide the solution of parasitic control and provide in sight in to the uptake of anti cestodal drugs either against human or livestock parasites.

Enantioseparation and determination of the chiral fungicide furametpyr enantiomers in rice, soil, and water by high-performance liquid chromatography.

PubMed

Dong, Fengshou; Chen, Xiu; Xu, Jun; Liu, Xingang; Chen, Zenglong; Li, Yuanbo; Zhang, Hongjun; Zheng, Yongquan

2013-12-01

The chiral fungicide furametpyr is widely used in the rice field to control rice sheath blight; however, furametpyr enantiomers are treated as just one compound in traditional achiral analysis, which gives only partial information. An effective chiral analytical method was developed for the resolution and determination of the fungicide furametpyr enantiomers in rice, soil, and water samples. Furametpyr enantiomers were excellently separated and determined on a Chiralpak AD-H column with n-hexane/ethanol (90:10, v/v) as mobile phase at a flow rate of 0.8 mL min(-1) with UV detection at 220 nm. The resolution was up to 8.85. The first eluted enantiomer was (+)-furametpyr and the second eluted one was (-)-furametpyr. The effects of mobile-phase composition and column temperature on the enantioseparation were evaluated. The method was validated for linearity, repeatability, accuracy, limit of detection (LOD), and limit of quantification LOQ. LOD was 2.0 µg kg(-1) in water, 0.02 mg kg(-1) in soil, and 0.07 mg kg(-1) in rice with an LOQ of 6.7 µg kg(-1) in water, 0.07 mg kg(-1) in soil, and 0.23 mg kg(-1) in rice. The average recoveries of the pesticide in all matrices ranged from 73.1 to 101.8% for all fortification levels. The precision values associated with the analytical method, expressed as relative standard deviation (RSD) values, were below 14.0% in all matrices. The methodology was successfully applied for the enantioselective analysis of furametpyr enantiomers in real samples. © 2013 Wiley Periodicals, Inc.

Two complementary liquid chromatography-tandem mass spectrometry (LC-MS/MS) methods to study the excretion and metabolic interaction of edaravone and taurine in rats.

PubMed

Tang, Dao-quan; Zheng, Xiao-xiao; Li, Yin-jie; Bian, Ting-ting; Yu, Yan-yan; Du, Qian; Yang, Dong-zhi; Jiang, Shui-shi

2014-11-01

In this study, two independent and complementary liquid chromatography-tandem mass spectrometry (LC-MS/MS) methods were respectively developed and validated for the determination of edaravone or taurine in rat urine, feces and bile after intravenous administration, using 3-methyl-l-p-tolyl-5-pyrazolone and sulfanilic acid as the internal standards (IS). Edaravone was separated on an Agilent Eclipse Plus C18 column (100×2.1 mm, 3.5 μm) using methanol and water (containing 5 mM ammonium formate and 0.02% formic acid) as mobile phase, while taurine was performed on a Waters Atlantis HILIC Silica column (150×2.1 mm, 3 μm) using acetonitrile and water (containing 5mM ammonium formate and 0.2% formic acid) as mobile phase. The mass analysis was performed in a Triple Quadrupole mass spectrometer via multiple reaction monitoring (MRM) with negative ionization mode. The optimized mass transition ion pairs (m/z) for quantification were 173.1→92.2 and 187.2→106.0 for edaravone and its IS, 124.1→80.0 and 172.0→80.0 for taurine and its IS, respectively. The validated methods have been successfully applied to the excretion and metabolism interaction study of edaravone and taurine in rats after independent intravenous administration and co-administration with a single dose. The results demonstrated that there were no significant alternations on the metabolism and cumulative excretion rate of edaravone and taurine, implying that the proposed combination therapy was pharmacologically viable. Copyright © 2014 Elsevier B.V. All rights reserved.

[Detection of rifampicin concentration in cerebrospinal fluid by online enrichment and restricted-access media coupled with high-performance liquid chromatography].

PubMed

Yang, Xiaoping; Zhang, Xiaohui; Huang, Yanping; Wang, Rong; Xia, Hua; Li, Wenbin; Guo, YouMin

2015-11-01

To establish a method for detecting rifampicin in human cerebrospinal fluid (CSF) with restricted access media coupled with high-performance liquid chromatography that allows online direct sample injection and enrichment. We used the column of restricted access media as the pre-treatment column and a C18 column as the analytical column. The mobile phase of pre-treatment column was water-methanol (95:5,V/V) and the flow rate was 1 mL/min; the mobile phase of the analytical column was methanol-acetonitrile-10 mmol/L ammonuium acetate (volume ratio of 60:5:35). The detection wavelength was 254 nm and the column temperature was set at 25 degrees celsius;. For an injection volume of 100 µL, the peak area of rifampicin was 5.33 times that for an injection volume of 20 µL, and the limit of detection was effectively improved. The calibration curve showed an excellent linear relationship (r=0.9997) between rifampicin concentrations and peak areas within the concentration range of 0.25 to 8 µg/mL in CSF. The limits of detection and quantification was 0.07 µg/mL and 0.25 µg/mL, respecetively, with intra-day and inter-day assay precisions and relative standard deviation (RSD%) all below 5%. The recoveries of rifampicin at 3 blank spiked levels (low, medium, and high) ranged from 87.69% to 102.11%. In patients taking oral rifampicin at the dose of 10 mg/kg, the average rifampicin concentration was 0.29 in the CSF at 2 h after medication. The method we established is simple and fast for detecting rifampicin in CSF and allows direct online injection and enrichment with good detection precisions and accuracies.

Analysis of anthocyanins in commercial fruit juices by using nano-liquid chromatography-electrospray-mass spectrometry and high-performance liquid chromatography with UV-vis detector.

PubMed

Fanali, Chiara; Dugo, Laura; D'Orazio, Giovanni; Lirangi, Melania; Dachà, Marina; Dugo, Paola; Mondello, Luigi

2011-01-01

Nano-LC and conventional HPLC techniques were applied for the analysis of anthocyanins present in commercial fruit juices using a capillary column of 100 μm id and a 2.1 mm id narrow-bore C(18) column. Analytes were detected by UV-Vis at 518 nm and ESI-ion trap MS with HPLC and nano-LC, respectively. Commercial blueberry juice (14 anthocyanins detected) was used to optimize chromatographic separation of analytes and other analysis parameters. Qualitative identification of anthocyanins was performed by comparing the recorded mass spectral data with those of published papers. The use of the same mobile phase composition in both techniques revealed that the miniaturized method exhibited shorter analysis time and higher sensitivity than narrow-bore chromatography. Good intra-day and day-to-day precision of retention time was obtained in both methods with values of RSD less than 3.4 and 0.8% for nano-LC and HPLC, respectively. Quantitative analysis was performed by external standard curve calibration of cyanidin-3-O-glucoside standard. Calibration curves were linear in the concentration ranges studied, 0.1-50 and 6-50 μg/mL for HPLC-UV/Vis and nano-LC-MS, respectively. LOD and LOQ values were good for both methods. In addition to commercial blueberry juice, qualitative and quantitative analysis of other juices (e.g. raspberry, sweet cherry and pomegranate) was performed. The optimized nano-LC-MS method allowed an easy and selective identification and quantification of anthocyanins in commercial fruit juices; it offered good results, shorter analysis time and reduced mobile phase volume with respect to narrow-bore HPLC. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Validation of a multi-analyte HPLC-DAD method for determination of uric acid, creatinine, homovanillic acid, niacinamide, hippuric acid, indole-3-acetic acid and 2-methylhippuric acid in human urine.

PubMed

Remane, Daniela; Grunwald, Soeren; Hoeke, Henrike; Mueller, Andrea; Roeder, Stefan; von Bergen, Martin; Wissenbach, Dirk K

2015-08-15

During the last decades exposure sciences and epidemiological studies attracts more attention to unravel the mechanisms for the development of chronic diseases. According to this an existing HPLC-DAD method for determination of creatinine in urine samples was expended for seven analytes and validated. Creatinine, uric acid, homovanillic acid, niacinamide, hippuric acid, indole-3-acetic acid, and 2-methylhippuric acid were separated by gradient elution (formate buffer/methanol) using an Eclipse Plus C18 Rapid Resolution column (4.6mm×100mm). No interfering signals were detected in mobile phase. After injection of blank urine samples signals for the endogenous compounds but no interferences were detected. All analytes were linear in the selected calibration range and a non weighted calibration model was chosen. Bias, intra-day and inter-day precision for all analytes were below 20% for quality control (QC) low and below 10% for QC medium and high. The limits of quantification in mobile phase were in line with reported reference values but had to be adjusted in urine for homovanillic acid (45mg/L), niacinamide 58.5(mg/L), and indole-3-acetic acid (63mg/L). Comparison of creatinine data obtained by the existing method with those of the developed method showing differences from -120mg/L to +110mg/L with a mean of differences of 29.0mg/L for 50 authentic urine samples. Analyzing 50 authentic urine samples, uric acid, creatinine, hippuric acid, and 2-methylhippuric acid were detected in (nearly) all samples. However, homovanillic acid was detected in 40%, niacinamide in 4% and indole-3-acetic acid was never detected within the selected samples. Copyright © 2015 Elsevier B.V. All rights reserved.

The application of multiple analyte adduct formation in the LC-MS3 analysis of valproic acid in human serum.

PubMed

Dziadosz, Marek

2017-01-01

LC-MS using electrospray ionisation (negative ion mode) and low-energy collision-induced dissociation tandem mass spectrometric (CID-MS/MS) analysis, together with the multiple analyte adduct formation with the components of the mobile phase, were applied to analyse valproic acid in human serum with LC-MS 3 . The CID-fragmentation of the precursor analyte adduct [M+2CH 3 COONa-H] - was applied in the method validation (307.1/225.1/143.0). Chromatographic separation was performed with a Luna 5μm C18 (2) 100A, 150mm×2mm column and the elution with a mobile phase consisting of A (H 2 O/methanol=95/5, v/v) and B (H 2 O/methanol=3/97, v/v), both with 10mM ammonium acetate and 0.1% acetic acid. A binary flow pumping mode with a total flow rate of 0.400mL/min was used. The calculated limit of detection/quantification of the method calibrated in the range of 10-200μg/mL was 0.31/1.0μg/mL. The sample preparation based on protein precipitation with 1mL of H 2 O/methanol solution (3/97, v/v) with 10mM sodium acetate and 100mM acetic acid. On the basis of the experiments performed could be demonstrated, that multiple analyte adduct formation can be applied to generate MS 3 quantitation of analytes with problematic fragmentation. The presented new strategy makes the analysis of small drugs, which do not produce any stable product ions at all, on the basis of LC-MS 3 possible. Copyright © 2016 Elsevier B.V. All rights reserved.

Development and validation of an HPLC-DAD method for simultaneous determination of cocaine, benzoic acid, benzoylecgonine and the main adulterants found in products based on cocaine.

PubMed

Floriani, Gisele; Gasparetto, João Cleverson; Pontarolo, Roberto; Gonçalves, Alan Guilherme

2014-02-01

Here, an HPLC-DAD method was developed and validated for simultaneous determination of cocaine, two cocaine degradation products (benzoylecgonine and benzoic acid), and the main adulterants found in products based on cocaine (caffeine, lidocaine, phenacetin, benzocaine and diltiazem). The new method was developed and validated using an XBridge C18 4.6mm×250mm, 5μm particle size column maintained at 60°C. The mobile phase consisted of a gradient of acetonitrile and ammonium formate 0.05M - pH 3.1, eluted at 1.0mL/min. The volume of injection was 10μL and the DAD detector was set at 274nm. Method validation assays demonstrated suitable sensitivity, selectivity, linearity, precision and accuracy. For selectivity assay, a MS detection system could be directly adapted to the method without the need of any change in the chromatographic conditions. The robustness study indicated that the flow rate, temperature and pH of the mobile phase are critical parameters and should not be changed considering the conditions herein determined. The new method was then successfully applied for determining cocaine, benzoylecgonine, benzoic acid, caffeine, lidocaine, phenacetin, benzocaine and diltiazem in 115 samples, seized in Brazil (2007-2012), which consisted of cocaine paste, cocaine base and salt cocaine samples. This study revealed cocaine contents that ranged from undetectable to 97.2%, with 97 samples presenting at least one of the degradation products or adulterants here evaluated. All of the studied degradation products and adulterants were observed among the seized samples, justifying the application of the method, which can be used as a screening and quantification tool in forensic analysis. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

MobileSat (R): A characteristically Australian MSS

NASA Technical Reports Server (NTRS)

Wagg, Michael; Jansen, Michael

1995-01-01

Optus launched its mobile satellite telephone service MobileSat in August 1994. This provided Australia and its neighboring waters with nation-wide mobile telephone coverage and still is the world's only domestic mobile satellite telephone system. This paper provides details of Optus' experience in developing and launching the MobileSat service, including (1) a retrospective of the issues that have waxed and waned in importance during the development and implementation phases, and (2) the strategy for future activities based on the experience gained in the development phase.

Assessment of elemental mobility in soil using a fluidised bed approach with on-line ICP-MS analysis.

PubMed

Beeston, Michael Philip; Glass, Hylke Jan; van Elteren, Johannes Teun; Slejkovec, Zdenka

2007-09-19

A new method has been developed to analyse the mobility of elements within soils employing counter-current flow soil contacting in a fluidised bed (FB) column. This method alleviates the problem of irreproducible peaks suffered by state-of-the-art micro-column techniques as a result of particle compaction. Reproducible extraction profiles are produced through the leaching of soil with a linear gradient of 0.05 mol L(-1) ammonium sulphate to 0.11 mol L(-1) acetic acid using a high pressure liquid chromatography (HPLC) quaternary pump, and the continuous monitoring of the elements in the leachate with inductively coupled plasma mass spectrometry (ICP-MS). Quantification of the procedure is achieved with an external flow injection (FI) calibration method. Flow rate and FB column length were investigated as critical parameters to the efficiency of the extraction methodology. It was found that an increase in the column length from 10 to 20 cm using a flow rate of 0.15 mL min(-1) produced the same increase in extracted elemental concentration as an increase in flow rate from 0.15 to 0.30 mL min(-1). In both examples, the increase in the concentration of elements leached from the soil may be ascribed to the increase in the concentration gradient between the solid and liquid. The exhaustive nature of the technique defines the maximum leachable concentration within the operationally defined leaching parameters of the exchangeable phase, providing a more accurate assessment of the risk associated with the elements in the soil for the phase providing the greatest risk to the environment. The multi-elemental high sensitivity nature of the on-line detector provides an accurate determination of the associations present between the elements in the soil, and the identification of multiple phases within the exchangeable phase through the presence of multiple peaks in the extraction profiles. It is possible through the deconvolution of these extraction profiles that the concentration corresponding to the peaks identified can be defined.

Influence of variation in mobile phase pH and solute pK(a) with the change of organic modifier fraction on QSRRs of hydrophobicity and RP-HPLC retention of weakly acidic compounds.

PubMed

Han, Shu-ying; Liang, Chao; Zou, Kuan; Qiao, Jun-qin; Lian, Hong-zhen; Ge, Xin

2012-11-15

The variation in mobile phase pH and ionizable solute dissociation constant (pK(a)) with the change of organic modifier fraction in hydroorganic mobile phase has seemingly been a troublesome problem in studies and applications of reversed phase high performance liquid chromatography (RP-HPLC). Most of the early studies regarding the RP-HPLC of acid-base compounds have to measure the actual pH of the mixed mobile phase rigorously, sometimes bringing difficulties in the practices of liquid chromatographic separation. In this paper, the effect of this variation on the apparent n-octanol/water partition coefficient (K(ow)″) and the related quantitative structure-retention relationship (QSRR) of logK(ow)″ vs. logk(w), the logarithm of retention factor of analytes in neat aqueous mobile phases, was investigated for weakly acidic compounds. This QSRR is commonly used as a classical method for K(ow) measurement by RP-HPLC. The theoretical and experimental derivation revealed that the variation in mobile phase pH and solute pK(a) will not affect the QSRRs of acidic compounds. This conclusion is proved to be suitable for various types of ion-suppressors, i.e., strong acid (perchloric acid), weak acid (acetic acid) and buffer salt (potassium dihydrogen phosphate/phosphoric acid, PBS). The QSRRs of logK(ow)″ vs. logk(w) were modeled by 11 substituted benzoic acids using different types of ion-suppressors in a binary methanol-water mobile phase to confirm our deduction. Although different types of ion-suppressor all can be used as mobile phase pH modifiers, the QSRR model obtained by using perchloric acid as the ion-suppressor was found to have the best result, and the slightly inferior QSRRs were obtained by using acetic acid or PBS as the ion-suppressor. Copyright © 2012 Elsevier B.V. All rights reserved.

Reversed phase liquid chromatography with UV absorbance and flame ionization detection using a water mobile phase and a cyano propyl stationary phase Analysis of alcohols and chlorinated hydrocarbons.

PubMed

Quigley, W W; Ecker, S T; Vahey, P G; Synovec, R E

1999-10-01

The development of liquid chromatography with a commercially available cyano propyl stationary phase and a 100% water mobile phase is reported. Separations were performed at ambient temperature, simplifying instrumental requirements. Excellent separation efficiency using a water mobile phase was achieved, for example N=18 800, or 75 200 m(-1), was obtained for resorcinol, at a retention factor of k'=4.88 (retention time of 9.55 min at 1 ml min(-1) for a 25 cmx4.6 mm i.d. column, packed with 5 mum diameter particles with the cyano propyl stationary phase). A separation via reversed phase liquid chromatography (RP-LC) with a 100% water mobile phase of six phenols and related compounds was compared to a separation of the same compounds by traditional RP-LC, using octadecylsilane (ODS), i.e. C18, bound to silica and an aqueous mobile phase modified with acetonitrile. Nearly identical analysis time was achieved for the separation of six phenols and related compounds using the cyano propyl stationary phase with a 100% water mobile phase, as compared to traditional RP-LC requiring a relatively large fraction of organic solvent modifier in the mobile phase (25% acetonitrile:75% water). Additional understanding of the retention mechanism with the 100% water mobile phase was obtained by relating measured retention factors of aliphatic alcohols, phenols and related compounds, and chlorinated hydrocarbons to their octanol:water partition coefficients. The retention mechanism is found to be consistent with a RP-LC mechanism coupled with an additional retention effect due to residual hydroxyl groups on the cyano propyl stationary phase. Advantages due to a 100% water mobile phase for the chemical analysis of alcohol mixtures and chlorinated hydrocarbons are reported. By placing an absorbance detector in-series and preceding a novel drop interface to a flame ionization detector (FID), selective detection of a separated mixture of phenols and related compounds and aliphatic alcohols is achieved. The compound class of aliphatic alcohols is selectively and sensitively detected by the drop interface/FID, and the phenols and related compounds are selectively and sensitively detected by absorbance detection at 200 nm. The separation and detection of chlorinated hydrocarbons in a water sample matrix further illustrated the advantages of this methodology. The sensitivity and selectivity of the FID signal for the chlorinated hydrocarbons are significantly better than absorbance detection, even at 200 nm. This methodology is well suited to continuous and automated monitoring of water samples. The applicability of samples initially in an organic solvent matrix is explored, since an organic sample matrix may effect retention and efficiency. Separations in acetonitrile and isopropyl alcohol sample matrices compared well to separations with a water sample matrix.

77 FR 57085 - Mobility Fund Phase I Auction; Release of Files with Recalculated Road Miles for Auction 901...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-09-17

... FEDERAL COMMUNICATIONS COMMISSION [AU Docket No. 12-25; DA 12-1446] Mobility Fund Phase I Auction... Mobility Fund Phase I support to be offered in Auction 901, which is to be held on September 27, 2012, and the change of the mock auction date from September 25, 2012 to September 21, 2012. DATES: The mock...

Project inspection using mobile technology - phase I : an investigation into existing business processes and areas for improvement using mobile technology.

DOT National Transportation Integrated Search

2013-08-01

As mobile technology becomes widely available and affordable, transportation agencies can use this technology to : streamline operations involved within project inspection. This research, conducted in two phases, identified : opportunities for proces...

Quantification of the xenoestrogens 4-tert.-octylphenol and bisphenol A in water and in fish tissue based on microwave assisted extraction, solid-phase extraction and liquid chromatography-mass spectrometry.

PubMed

Pedersen, S N; Lindholst, C

1999-12-09

Extraction methods were developed for quantification of the xenoestrogens 4-tert.-octylphenol (tOP) and bisphenol A (BPA) in water and in liver and muscle tissue from the rainbow trout (Oncorhynchus mykiss). The extraction of tOP and BPA from tissue samples was carried out using microwave-assisted solvent extraction (MASE) followed by solid-phase extraction (SPE). Water samples were extracted using only SPE. For the quantification of tOP and BPA, liquid chromatography mass spectrometry (LC-MS) equipped with an atmospheric pressure chemical ionisation interface (APCI) was applied. The combined methods for tissue extraction allow the use of small sample amounts of liver or muscle (typically 1 g), low volumes of solvent (20 ml), and short extraction times (25 min). Limits of quantification of tOP in tissue samples were found to be approximately 10 ng/g in muscle and 50 ng/g in liver (both based on 1 g of fresh tissue). The corresponding values for BPA were approximately 50 ng/g in both muscle and liver tissue. In water, the limit of quantification for tOP and BPA was approximately 0.1 microg/l (based on 100 ml sample size).

Development of a rapid, simple and sensitive HPLC-FLD method for determination of rhodamine B in chili-containing products.

PubMed

Qi, Ping; Lin, Zhihao; Li, Jiaxu; Wang, ChengLong; Meng, WeiWei; Hong, Hong; Zhang, Xuewu

2014-12-01

In this work, a simple, rapid and sensitive analytical method for the determination of rhodamine B in chili-containing foodstuffs is described. The dye is extracted from samples with methanol and analysed without further cleanup procedure by high-performance liquid chromatography (HPLC) coupled to fluorescence detection (FLD). The influence of matrix fluorescent compounds (capsaicin and dihydrocapsaicin) on the analysis was overcome by the optimisation of mobile-phase composition. The limit of determination (LOD) and limit of quantification (LOQ) were 3.7 and 10 μg/kg, respectively. Validation data show a good repeatability and within-lab reproducibility with relative standard deviations <10%. The overall recoveries are in the range of 98-103% in chili powder and in the range of 87-100% in chili oil depending on the concentration of rhodamine B in foodstuffs. This method is suitable for the routine analysis of rhodamine B due to its sensitivity, simplicity, reasonable time and cost. Copyright © 2014 Elsevier Ltd. All rights reserved.

[Simultaneous determination of aspartame and alitame in jellies and preserved fruits by HPLC].

PubMed

Jiang, Dingguo; Fang, Congrong; Yang, Dajin

2012-05-01

To establish a determination method for aspartame and alitame in jellies and preserved fruits. Aspartame and alitame in jellies were extracted with 80% methanol at 70 degrees C. Preserved fruits were homogenized with water and then were extracted with 50% methanol. A chromatographic column Zorbax SB-C18 was used; the mobile phase was methanol/water (40 + 60, volume ratio), and a diode array detector was used for the detection at wavelength 200 nm. The limits of quantification of aspartame and alitame were both 8 mg/kg for jellies and both 20 mg/kg for preserved fruits; the calibration curves were linear in the range of tested concentration. The correlation coefficients were better than 0.9996. The average recovery rates were in the range of 98.1% -101.2%, the relative standard deviations were 2.21% - 4.10%. The method is simple, practical, accurate, reliable and successful in the determination of aspartame and alitame in jellies and preserved fruits from various brands on markets.

Sodium benzoate and potassium sorbate preservatives in Iranian doogh.

PubMed

Zamani Mazdeh, F; Esmaeili Aftabdari, F; Moradi-Khatoonabadi, Z; Shaneshin, M; Torabi, P; Shams Ardekani, M R; Hajimahmoodi, M

2014-01-01

Sodium benzoate and potassium sorbate are two common preservatives used in Iran, yet use of these preservatives in doogh (Iranian dairy-based drink) is forbidden according to national standards. The aim of this study was to consider the presence of these preservatives in doogh by high-performance liquid chromatography with UV detection (HPLC-UV). The method was performed using a C18 column and detection at 225 nm. The mobile phase contained ammonium acetate buffer (pH = 4.2) and acetonitrile (80:20 v/v). The survey included 130 samples of doogh for identification and quantification of the named preservatives. All samples contained sodium benzoate, but potassium sorbate was detected in only 13% of them. The means of benzoate and sorbate were 21.3 ± 2.7 and 13.3 ± 39.6 mg kg(-1), respectively. The limits of detection were 2 and 40 ng g(-1) for benzoate and sorbate, respectively. Results indicate that sodium benzoate may occur in doogh naturally.

Arsenic species separation by IELC-ICP/OES: Arsenocholine behavior

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rubio, R.; Peralta, I.; Alberti, J.

1993-01-01

In the literature an increasing interest is observed in developing methods to determine arsenobetaine, arsenocholine and related compounds in sea food and in reference materials. The separation conditions and quantification of As(III), As(V), monomethylarsenate (MMA), dimethylarsinate (DMA), arsenobetaine (AsBet) and arsenocholine (AsChol) are studied by Liquid Chromatography (LC) coupled directly to an Inductively Coupled Plasma Optical Emission Spectroscopy (ICP/OES) system. The separation conditions are optimized to improve the resolution of the six arsenic species. Arsenocholine shows a particular pattern of behavior when phosphate is used as eluent: two peaks are observed in the chromatogram, thus a systematic study assaying differentmore » pH and concentration of phosphate is carried out to improve resolution and analysis time when the six arsenic compounds are analyzed in a mixture. Boric acid as mobile phase avoids the splitting of the arsenocholine peak and leads to a good separation of the six arsenic compounds. Detection limits are established for the six arsenic species.« less

Improvement in HPLC separation of acetic acid and levulinic acid in the profiling of biomass hydrolysate.

PubMed

Xie, Rui; Tu, Maobing; Wu, Yonnie; Adhikari, Sushil

2011-04-01

5-Hydroxymethylfurfural (HMF) and furfural could be separated by the Aminex HPX-87H column chromatography, however, the separation and quantification of acetic acid and levulinic acid in biomass hydrolysate have been difficult with this method. In present study, the HPLC separation of acetic acid and levulinic acid on Aminex HPX-87H column has been investigated by varying column temperature, flow rate, and sulfuric acid content in the mobile phase. The column temperature was found critical in resolving acetic acid and levulinic acid. The resolution for two acids increased dramatically from 0.42 to 1.86 when the column temperature was lowered from 60 to 30 °C. So did the capacity factors for levulinic acid that was increased from 1.20 to 1.44 as the column temperature dropped. The optimum column temperature for the separation was found at 45 °C. Variation in flow rate and sulfuric acid concentration improved not as much as the column temperature did. Published by Elsevier Ltd.

Liquid chromatography-tandem mass spectrometry method of loxoprofen in human plasma.

PubMed

Lee, Hye Won; Ji, Hye Young; Sohn, Dong Hwan; Kim, Se-Mi; Lee, Yong Bok; Lee, Hye Suk

2009-07-01

A rapid, sensitive and selective liquid chromatography-electrospray ionization mass spectrometric method for the determination of loxoprofen in human plasma was developed. Loxoprofen and ketoprofen (internal standard) were extracted from 20 microL of human plasma sample using ethyl acetate at acidic pH and analyzed on an Atlantis dC(18) column with the mobile phase of methanol:water (75:25, v/v). The analytes were quantified in the selected reaction monitoring mode. The standard curve was linear over the concentration range of 0.1-20 microg/mL with a lower limit of quantification of 0.1 microg/mL. The coefficient of variation and relative error for intra- and inter-assay at four quality control levels were 2.8-5.2 and 4.8-7.0%, respectively. The recoveries of loxoprofen and ketoprofen were 69.7 and 67.6%, respectively. The matrix effects for loxoprofen and ketoprofen were practically absent. This method was successfully applied to the pharmacokinetic study of loxoprofen in humans. (c) 2009 John Wiley & Sons, Ltd.

Development and Validation of a Stability-Indicating Assay of Etofenamate by RP-HPLC and Characterization of Degradation Products

PubMed Central

Peraman, Ramalingam; Nayakanti, Devanna; Dugga, Hari Hara Theja; Kodikonda, Sudhakara

2013-01-01

A validated stability-indicating RP-HPLC method for etofenamate (ETF) was developed by separating its degradation products on a C18 (250 mm × 4.6 mm 5 μm) Qualisil BDS column using a phosphate buffer (pH-adjusted to 6.0 with orthophosphoric acid) and methanol in the ratio of 20:80 % v/v as the mobile phase at a flow rate of 1.0 mL/min. The column effluents were monitored by a photodiode array detector set at 286 nm. The method was validated in terms of specificity, linearity, accuracy, precision, detection limit, quantification limit, and robustness. Forced degradation of etofenamate was carried out under acidic, basic, thermal, photo, and peroxide conditions and the major degradation products of acidic and basic degradation were isolated and characterized by 1H-NMR, 13C-NMR, and mass spectral studies. The mass balance of the method varied between 92–99%. PMID:24482770

Quantification of urinary zwitterionic organic acids using weak-anion exchange chromatography with tandem MS detection.

PubMed

Bishop, Michael Jason; Crow, Brian S; Kovalcik, Kasey D; George, Joe; Bralley, James A

2007-04-01

A rapid and accurate quantitative method was developed and validated for the analysis of four urinary organic acids with nitrogen containing functional groups, formiminoglutamic acid (FIGLU), pyroglutamic acid (PYRGLU), 5-hydroxyindoleacetic acid (5-HIAA), and 2-methylhippuric acid (2-METHIP) by liquid chromatography tandem mass spectrometry (LC/MS/MS). The chromatography was developed using a weak anion-exchange amino column that provided mixed-mode retention of the analytes. The elution gradient relied on changes in mobile phase pH over a concave gradient, without the use of counter-ions or concentrated salt buffers. A simple sample preparation was used, only requiring the dilution of urine prior to instrumental analysis. The method was validated based on linearity (r2>or=0.995), accuracy (85-115%), precision (C.V.<12%), sample preparation stability (

Simple and sensitive HPLC method with fluorescence detection for the measurement of ibuprofen in rat plasma: application to a long-lasting dosage form.

PubMed

Hassan, Ahmed Sheikh; Sapin, Anne; Ubrich, Nathalie; Maincent, Philippe; Bolzan, Claire; Leroy, Pierre

2008-10-01

A simple and sensitive high-performance liquid chromatography (HPLC) assay applied to the measurement of ibuprofen in rat plasma has been developed. Two parameters have been investigated to improve ibuprofen detectability using fluorescence detection: variation of mobile phase pH and the use of beta-cyclodextrin (beta-CD). Increasing the pH value from 2.5 to 6.5 and adding 5 mM beta-CD enhanced the fluorescence signal (lambda(exc) = 224 nm; lambda(em) = 290 nm) by 2.5 and 1.3-fold, respectively, when using standards. In the case of plasma samples, only pH variation significantly lowered detection and quantification limits, down to 10 and 35 ng/mL, respectively. Full selectivity was obtained with a single step for plasma treatment, that is, protein precipitation with acidified acetonitrile. The validated method was applied to a pharmacokinetic study of ibuprofen encapsulated in microspheres and subcutaneously administered to rats.

High-throughput method based on quick, easy, cheap, effective, rugged and safe followed by liquid chromatography-multi-wavelength detection for the quantification of multiclass polyphenols in wines.

PubMed

Fontana, Ariel R; Bottini, Rubén

2014-05-16

In this work, a reliable, simple, fast, inexpensive and robust sample preparation approach for the determination of multiclass polyphenols in wine samples is proposed. The polyphenols selected for this work were gallic acid, (+)-catechin, (-)-epicatechin, caffeic acid, syringic acid, coumaric acid, ferulic acid, trans-resveratrol, quercetin and cinnamic acid. The method is based on QuEChERS (quick, easy, cheap, effective, rugged and safe) extraction technique coupled with dispersive solid-phase extraction (d-SPE) clean-up. Under optimized conditions, the analytes were extracted from 5mL wine samples (previously acidified with 1% formic acid) using 2.5mL acetonitrile. For phase separation, 1.5g NaCl and 4g anhydrous MgSO4 were added. Then, a 1mL aliquot of the partitioned supernatant was cleaned-up using d-SPE with a combination of 150mg CaCl2, 50mg primary-secondary amine (PSA) and 50mgC18 as sorbents. A 250μL aliquot of the obtained cleaned extract was concentrated to dryness and taken up with the initial mobile phase previous to liquid chromatography-multi-wavelength detection (LC-MWD). The proposed method provided limits of detection (LODs) ranging from 0.004 to 0.079μgmL(-1) and an inter-day variability below 12% RSD for all analytes in red and white wine samples. Considering external calibration (red wines) and matrix-matched calibration (white wines) as quantification techniques, the overall recoveries (accuracy) of the method ranged between 75.0% and 119.6% for red and white wine samples, respectively. The developed method was applied for the determination of polyphenols in 10 wines produced in Argentina. Nine phenolic compounds were determined, at concentrations above detectable levels in the method. The maximum concentrations corresponded to (-)-epicatechin in white wines, while gallic acid and (+)-catechin were the most abundant in red wines. Copyright © 2014 Elsevier B.V. All rights reserved.

Determination of Alkaloid Contents in Various Tissues of Coptis Chinensis Franch. by Reversed Phase-High Performance Liquid Chromatography and Ultraviolet Spectrophotometry.

PubMed

Yang, Yanfang; Peng, Jingling; Li, Fangping; Liu, Xin; Deng, Meng; Wu, Hezhen

2017-05-01

A simple and intuitive method for optimizing the chemical constituents of Coptis Chinensis Franch. is important to assess its quality and clinical efficacy. An high performance liquid chromatography and ultraviolet spectrophotometry method was developed for the determination of berberine hydrochloride, palmatine chloride, jatrorrhizine hydrochloride, epiberberine, coptisine, columbamine and magnoflorine in various tissues (i.e., phloem, xylem and medulla) and rizhome of C. Chinensis Franch. The transection of rhizome from outside-in includes cork layer, cortex, phloem, cambium, xylem and medulla. Cork layer consists of dead cells, and therefore is not of any research significance. Cortex, phloem and cambium were almost impossible to separate, therefore they were studied as a whole in our experiments. They were collectively referred to as "phloem". The analytes were separated on a Gemini-NX C18 (250 mm × 4.6 mm, 5 μm) reversed phase column using a gradient elution of acetonitrile-0.03 mol/L ammonium acetate solution (containing 0.1% triethylamine and 0.6% ammonium hydroxide) as the mobile phase at a flow rate of 1.0 mL/min and UV detection at 270 nm. The method allowing the simultaneous quantification of seven major active constituents was optimized and validated for linearity, precision, accuracy, limits of detection (LOD) and quantification. The LOD ranged from 0.102 to 0.651 mg/mL (r ≥ 0.9993). Accuracy, precision and recovery were all within the required limits. The average recovery was between 100.14% and 102.75% and the relative standard deviations were <3.34%. At the same time, the absorbance was determined by ultraviolet spectrophotometry at 345 nm wavelength. Based on contents of the seven constituents and clustering result, this investigation suggests that there are significant differences in the distribution of seven alkaloids in the tissues examined. Furthermore, the total alkaloid content in xylem is relatively lower than that in phloem, medulla and rhizome. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Rapid determination of minoxidil in human plasma using ion-pair HPLC.

PubMed

Zarghi, A; Shafaati, A; Foroutan, S M; Khoddam, A

2004-10-29

A rapid, simple and sensitive ion-pair high-performance liquid chromatography (HPLC) method has been developed for quantification of minoxidil in plasma. The assay enables the measurement of minoxidil for therapeutic drug monitoring with a minimum detectable limit of 0.5 ng ml(-1). The method involves simple, one-step extraction procedure and analytical recovery was complete. The separation was performed on an analytical 150 x 4.6 mm i.d. microbondapak C18 column. The wavelength was set at 281 nm. The mobile phase was a mixture of 0.01 M sodium dihydrogen phosphate buffer and acetonitrile (60:40, v/v) containing 2.5 mM sodium dodecyl sulphate adjusted to pH 3.5 at a flow rate of 1 ml/min. The column temperature was set at 50 degrees C. The calibration curve was linear over the concentration range 2-100 ng ml(-1). The coefficients of variation for inter-day and intra-day assay were found to be less than 8%.

An efficient separation and method development for the quantifying of two basic impurities of Nicergoline by reversed-phase high performance liquid chromatography using ion-pairing counter ions.

PubMed

Yalçin, Güler; Yüktaş, Nüray

2006-10-11

A quantification method was developed for the two basic impurities, one of which is also a metabolite, of Nicergoline (NIC), by using reversed-phase high performance liquid chromatography (RP-HPLC) and diode array detector (DAD). One of these compounds,10-methoxy-6-methylergoline-8beta-methanol-5-bromo-3-pyridinecarboxylate (1-DN) is the metabolite as well as the impurity whereas, the other 10-methoxy-1,6-dimethylergoline-8beta-methanol-5-chloro-3-pyridinecarboxylate (5-CN) is only an impurity. The chromatographic column was Phenomenex, Luna, 5 microm, C18 (2), 250 mm x 4.6 mm. Mobile phase was 0.1 M ammonium acetate (NH4Ac) solution containing 4 mM 1-octanesulfonicacid sodium salt (OSASS) and 6 mM tetrabutylammonium hydrogen sulphate (TBAHS) (pH: 5.9)/acetonitrile (ACN) (62:38) for 1-DN and (64:36) for 5-CN. Flow rate was 1.0 mL min-1. The diode array detector was operated at 285 nm, band width: 4 nm. Linearity was obtained in the concentration range of 0.032 x 10-5 to 3.828 x 10-5 M, y = 116.88x + 0.2773 (r2 = 0.99989); the limit of detection (LOD) and limit of quantification (LOQ) were determined as 0.012 x 10-5 and 0.041 x 10-5 M for 1-DN, respectively. Linearity was obtained in the concentration range of 0.034 x 10-5 to 4.092 x 10-5 M, y = 104.24x + 0.7486 (r2 = 0.99996); (LOD) and (LOQ) were determined as 0.014 x 10-5 and 0.046 x 10-5 M for 5-CN, respectively. The recovery was 100.65% for 1-DN and 100.32% for 5-CN. The amount of 1-DN in 30 mg NIC was found as 209.65 microg (0.70%) and the amount of 5-CN in 30 mg NIC was found as 27.62 microg (0.09%).

Simultaneous quantitation of acetylsalicylic acid and clopidogrel along with their metabolites in human plasma using liquid chromatography tandem mass spectrometry.

PubMed

Chhonker, Yashpal S; Pandey, Chandra P; Chandasana, Hardik; Laxman, Tulsankar Sachin; Prasad, Yarra Durga; Narain, V S; Dikshit, Madhu; Bhatta, Rabi S

2016-03-01

The interest in therapeutic drug monitoring has increased over the last few years. Inter- and intra-patient variability in pharmacokinetics, plasma concentration related toxicity and success of therapy have stressed the need of frequent therapeutic drug monitoring of the drugs. A sensitive, selective and rapid liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) method was developed for the simultaneous quantification of acetylsalicylic acid (aspirin), salicylic acid, clopidogrel and carboxylic acid metabolite of clopidogrel in human plasma. The chromatographic separations were achieved on Waters Symmetry Shield(TM) C18 column (150 × 4.6 mm, 5 µm) using 3.5 mm ammonium acetate (pH 3.5)-acetonitrile (10:90, v/v) as mobile phase at a flow rate of 0.75 mL/min. The present method was successfully applied for therapeutic drug monitoring of aspirin and clopidogrel in 67 patients with coronary artery disease. Copyright © 2015 John Wiley & Sons, Ltd.

Experimental design for TBT quantification by isotope dilution SPE-GC-ICP-MS under the European water framework directive.

PubMed

Alasonati, Enrica; Fabbri, Barbara; Fettig, Ina; Yardin, Catherine; Del Castillo Busto, Maria Estela; Richter, Janine; Philipp, Rosemarie; Fisicaro, Paola

2015-03-01

In Europe the maximum allowable concentration for tributyltin (TBT) compounds in surface water has been regulated by the water framework directive (WFD) and daughter directive that impose a limit of 0.2 ng L(-1) in whole water (as tributyltin cation). Despite the large number of different methodologies for the quantification of organotin species developed in the last two decades, standardised analytical methods at required concentration level do not exist. TBT quantification at picogram level requires efficient and accurate sample preparation and preconcentration, and maximum care to avoid blank contamination. To meet the WFD requirement, a method for the quantification of TBT in mineral water at environmental quality standard (EQS) level, based on solid phase extraction (SPE), was developed and optimised. The quantification was done using species-specific isotope dilution (SSID) followed by gas chromatography (GC) coupled to inductively coupled plasma mass spectrometry (ICP-MS). The analytical process was optimised using a design of experiment (DOE) based on a factorial fractionary plan. The DOE allowed to evaluate 3 qualitative factors (type of stationary phase and eluent, phase mass and eluent volume, pH and analyte ethylation procedure) for a total of 13 levels studied, and a sample volume in the range of 250-1000 mL. Four different models fitting the results were defined and evaluated with statistic tools: one of them was selected and optimised to find the best procedural conditions. C18 phase was found to be the best stationary phase for SPE experiments. The 4 solvents tested with C18, the pH and ethylation conditions, the mass of the phases, the volume of the eluents and the sample volume can all be optimal, but depending on their respective combination. For that reason, the equation of the model conceived in this work is a useful decisional tool for the planning of experiments, because it can be applied to predict the TBT mass fraction recovery when the experimental conditions are drawn. This work shows that SPE is a convenient technique for TBT pre-concentration at pico-trace levels and a robust approach: in fact (i) number of different experimental conditions led to satisfactory results and (ii) the participation of two institutes to the experimental work did not impact the developed model. Copyright © 2014 Elsevier B.V. All rights reserved.

Validation and application of a high-performance liquid chromatography-tandem mass spectrometric method for simultaneous quantification of lopinavir and ritonavir in human plasma using semi-automated 96-well liquid-liquid extraction.

PubMed

Wang, Perry G; Wei, Jack S; Kim, Grace; Chang, Min; El-Shourbagy, Tawakol

2006-10-20

Kaletra is an important antiretroviral drug, which has been developed by Abbott Laboratories. It is composed of lopinavir (low-pin-a-veer) and ritonavir (ri-toe-na-veer). Both have been proved to be human immunodeficiency virus (HIV) protease inhibitors and have substantially reduced the morbidity and mortality associated with HIV-1 infection. We have developed and validated an assay, using liquid chromatography coupled with atmospheric pressure chemical ionization tandem mass spectrometry (LC/MS/MS), for the routine quantification of lopinavir and ritonavir in human plasma, in which lopinavir and ritonavir can be simultaneously analyzed with high throughput. The sample preparation consisted of liquid-liquid extraction with a mixture of hexane: ethyl acetate (1:1, v/v), using 100 microL of plasma. Chromatographic separation was performed on a Waters Symmetry C(18) column (150 mm x 3.9 mm, particle size 5 microm) with reverse-phase isocratic using mobile phase of 70:30 (v/v) acetonitrile: 2 mM ammonium acetate aqueous solution containing 0.01% formic acid (v/v) at a flow rate of 1.0 mL/min. A Waters symmetry C(18) guard column (20 mm x 3.9 mm, particle size 5 microm) was connected prior to the analytical column, and a guard column back wash was performed to reduce the analytical column contamination using a mixture of tetrahydrofuran (THF), methanol and water (45:45:10, v/v/v). The analytical run was 4 min. The use of a 96-well plate autosampler allowed a batch size up to 73 study samples. A triple-quadrupole mass spectrometer was operated in a positive ion mode and multiple reaction monitoring (MRM) was used for drug quantification. The method was validated over the concentration ranges of 19-5,300 ng/mL for lopinavir and 11-3,100 ng/mL for ritonavir. A-86093 was used as an internal standard (I.S.). The relative standard deviation (RSD) were <6% for both lopinavir and ritonavir. Mean accuracies were between the designed limits (+/-15%). The robust and rapid LC/MS/MS assay has been successfully applied for routine assay to support bioavailability, bioequivalence, and pharmacokinetics studies.

Comparative study of solvation parameter models accounting the effects of mobile phase composition in reversed-phase liquid chromatography.

PubMed

Torres-Lapasió, J R; Ruiz-Angel, M J; García-Alvarez-Coque, M C

2007-09-28

Solvation parameter models relate linearly compound properties with five fundamental solute descriptors (excess molar refraction, dipolarity/polarizability, effective hydrogen-bond acidity and basicity, and McGowan volume). These models are widely used, due to the availability of protocols to obtain the descriptors, good performance, and general applicability. Several approaches to predict retention in reversed-phase liquid chromatography (RPLC) as a function of these descriptors and mobile phase composition are compared, assaying the performance with a set of 146 organic compounds of diverse nature, eluted with acetonitrile and methanol. The approaches are classified in two groups: those that only allow predictions of retention for the mobile phases used to build the models, and those valid at any other mobile phase composition. The first group includes the use of ratios between the regressed coefficients of the solvation models that are assumed to be characteristic for a column/solvent system, and the application of offsets to transfer the retention from a reference mobile phase to any other. Maximal accuracy in predictions corresponded, however, to the approaches in the second group, which were based on models that describe the retention as a function of mobile phase composition (expressed as the solvent volume fraction or a normalised polarity measurement), where the coefficients were made dependent on the solvent descriptors. The study revealed the properties that influence the retention and distinguish the particular behaviour of acetonitrile and methanol in RPLC.

Multiphase mean curvature flows with high mobility contrasts: A phase-field approach, with applications to nanowires

NASA Astrophysics Data System (ADS)

Bretin, Elie; Danescu, Alexandre; Penuelas, José; Masnou, Simon

2018-07-01

The structure of many multiphase systems is governed by an energy that penalizes the area of interfaces between phases weighted by surface tension coefficients. However, interface evolution laws depend also on interface mobility coefficients. Having in mind some applications where highly contrasted or even degenerate mobilities are involved, for which classical phase field models are inapplicable, we propose a new effective phase field approach to approximate multiphase mean curvature flows with mobilities. The key aspect of our model is to incorporate the mobilities not in the phase field energy (which is conventionally the case) but in the metric which determines the gradient flow. We show the consistency of such an approach by a formal analysis of the sharp interface limit. We also propose an efficient numerical scheme which allows us to illustrate the advantages of the model on various examples, as the wetting of droplets on solid surfaces or the simulation of nanowires growth generated by the so-called vapor-liquid-solid method.

Application of the NUREG/CR-6850 EPRI/NRC Fire PRA Methodology to a DOE Facility

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tom Elicson; Bentley Harwood; Richard Yorg

2011-03-01

The application NUREG/CR-6850 EPRI/NRC fire PRA methodology to DOE facility presented several challenges. This paper documents the process and discusses several insights gained during development of the fire PRA. A brief review of the tasks performed is provided with particular focus on the following: • Tasks 5 and 14: Fire-induced risk model and fire risk quantification. A key lesson learned was to begin model development and quantification as early as possible in the project using screening values and simplified modeling if necessary. • Tasks 3 and 9: Fire PRA cable selection and detailed circuit failure analysis. In retrospect, it wouldmore » have been beneficial to perform the model development and quantification in 2 phases with detailed circuit analysis applied during phase 2. This would have allowed for development of a robust model and quantification earlier in the project and would have provided insights into where to focus the detailed circuit analysis efforts. • Tasks 8 and 11: Scoping fire modeling and detailed fire modeling. More focus should be placed on detailed fire modeling and less focus on scoping fire modeling. This was the approach taken for the fire PRA. • Task 14: Fire risk quantification. Typically, multiple safe shutdown (SSD) components fail during a given fire scenario. Therefore dependent failure analysis is critical to obtaining a meaningful fire risk quantification. Dependent failure analysis for the fire PRA presented several challenges which will be discussed in the full paper.« less

Simultaneous determination of eight bioactive components of Qishen Yiqi dripping pills in rat plasma using UFLC-MS/MS and its application to a pharmacokinetic study.

PubMed

Shao, Yaping; Zhang, Wen; Tong, Ling; Huang, Jingyi; Li, Dongxiang; Nie, Wei; Zhu, Yan; Li, Yunfei; Lu, Tao

2017-08-01

In this study, a rapid and reliable ultra-fast liquid chromatography-tandem mass spectrometry method was developed and validated for the simultaneous determination of eight active ingredients, including astragaloside IV, ononin, tanshinol, protocatechualdehyde, protocatechuic acid, salvianolic acid D, rosmarinic acid and ginsenoside Rg 1 , in rat plasma. The plasma samples were pretreated by protein precipitation with acetonitrile. Chromatographic separation was performed on a Waters Acquity UPLC® BEH C 18 column (1.7 μm particles, 2.1 × 100 mm). The mobile phase consisted of 0.1% aqueous formic acid (A)-acetonitrile with 0.1% formic acid (B) at a flow rate of 0.4 mL/min. Quantification was performed on a triple quadruple tandem mass spectrometry with electrospray ionization by multiple reaction monitoring both in the negative and in the positive ion mode. The lower limit of quantification of tanshinol was 2.0 ng/mL and the others were 5.0 ng/mL. The extraction recoveries, matrix effects, intra- and inter-day precision and accuracy of eight tested components were all within acceptable limits. The validated method was successfully applied to the pharmacokinetic study of the eight active constituents after intragastric administration of three doses (1.0, 3.0, 6.0 g/kg body weight) of Qishen Yiqi Dripping Pills to rats. Copyright © 2017 John Wiley & Sons, Ltd.

Analysis of Flavone C-Glycosides in the Leaves of Clinacanthus nutans (Burm. f.) Lindau by HPTLC and HPLC-UV/DAD

PubMed Central

Chelyn, June Lee; Omar, Maizatul Hasyima; Mohd Yousof, Nor Syaidatul Akmal; Ranggasamy, Ramesh; Wasiman, Mohd Isa; Ismail, Zakiah

2014-01-01

Clinacanthus nutans (family Acanthaceae) has been used for the treatment of inflammation and herpes viral infection. Currently, there has not been any report on the qualitative and quantitative determination of the chemical markers in the leaves of C. nutans. The C-glycosidic flavones such as shaftoside, isoorientin, orientin, isovitexin, and vitexin have been found to be major flavonoids in the leaves of this plant. Therefore, we had developed a two-step method using thin-layer chromatography (TLC) and high pressure liquid chromatography (HPLC) for the rapid identification and quantification of the flavones C-glycosides in C. nutans leaves. The TLC separation of the chemical markers was achieved on silica gel 60 plate using ethyl acetate : formic acid : acetic acid : water (100 : 11 : 11 : 27 v/v/v/v) as the mobile phase. HPLC method was optimized and validated for the quantification of shaftoside, orientin, isovitexin, and vitexin and was shown to be linear in concentration range tested (0.4–200 μg/mL, r 2 ≥ 0.996), precise (RSD ≤ 4.54%), and accurate (95–105%). The concentration of shaftoside, orientin, vitexin, and isovitexin in C. nutans leave samples was 2.55–17.43, 0.00–0.86, 0.00–2.01, and 0.00–0.91 mmol/g, respectively. PMID:25405231

Development and validation of a UPLC-MS/MS method for quantitation of droxidopa in human plasma: Application to a pharmacokinetic study.

PubMed

Wang, Haidong; Yang, Guangsheng; Zhou, Jinyu; Pei, Jiang; Zhang, Qiangfeng; Song, Xingfa; Sun, Zengxian

2016-08-01

In this study, a simple and sensitive ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was developed and validated for quantitation of droxidopa in human plasma for the first time. A simple plasma protein precipitation method using methanol containing 3% formic acid was selected, and the separation was achieved by an Acquity UPLC™ BEH Amide column (2.1mm×50mm, 1.7μm) with a gradient elution using acetonitrile, ammonium formate buffer and formic acid as mobile phase. The detection of droxidopa and benserazide (internal standard, IS) was performed using positive-ion electrospray tandem mass spectrometry via multiple reaction monitoring (MRM). The precursor-to-product ion transitions m/z 214.2→m/z 152.0 for droxidopa, and m/z 258.1→m/z 139.1 for IS were used for quantification. A lower limit of quantification of 5.00ng/mL was achieved and the linear curve range was 5.00-4000ng/mL using a weighted (1/x(2)) linear regression model. Intra-assay and inter-assay precision was less than 10.2%, and the accuracy ranged from 0.1% to 2.1%. Stability, recovery and matrix effects were within the acceptance criteria recommended by the regulatory bioanalytical guidelines. The method was successfully applied to a pharmacokinetic study of droxidopa in healthy Chinese volunteers. Copyright © 2016. Published by Elsevier B.V.

Simultaneous Determination of Reserpine, Rescinnamine, and Yohimbine in Human Plasma by Ultraperformance Liquid Chromatography Tandem Mass Spectrometry

PubMed Central

Iqbal, Muzaffar; Alam, Aftab; Wani, Tanveer A.; Khalil, Nasr Y.

2013-01-01

A sensitive and selective UPLC-MS/MS method was developed and validated for the determination of three indolic alkaloids (reserpine, rescinnamine, and yohimbine) in human plasma using papaverine as internal standard (IS). After a one step protein precipitation with acetonitrile, separation was carried out using C18 column (50 × 2.1 mm, i.d. 1.7 μm) and mobile phase consisting of acetonitrile : water : formic acid (60 : 40 : 0.1%, v/v/v) pumped at a flow rate of 0.2 mL/min. The mass spectrometric determination was carried out using an electrospray interface operated in the positive mode with multiple reaction monitoring (MRM) mode. The precursor to product ion transitions of m/z 609.32 > 195.01, m/z 635.34 > 221.03, m/z 355.19 > 144, and m/z 340.15 > 202.02 were selected for the quantification of reserpine, rescinnamine, yohimbine, and IS, respectively. The analytical response was found to be linear in the range of 0.36–400, 0.27–300, and 0.23–250 ng/mL with lower limit of quantification of 0.36, 0.27, and 0.23 ng/mL for reserpine, rescinnamine, and yohimbine, respectively. Validation was made following official guidelines. The proposed method enabled reproducible results and hence could be reliable for pharmacokinetic and toxicological analysis. PMID:24383039

High-performance liquid chromatography assay using ultraviolet detection for urinary quantification of milrinone concentrations in cardiac surgery patients undergoing cardiopulmonary bypass.

PubMed

Gavra, Paul; Nguyen, Anne Q N; Beauregard, Natasha; Denault, André Y; Varin, France

2014-08-01

An analytical assay using liquid-liquid extraction and high-performance liquid chromatography with ultraviolet detection was developed for the quantification of total (conjugated and unconjugated) urinary concentrations of milrinone after the inhalation of a 5 mg dose in 15 cardiac patients undergoing cardiopulmonary bypass. Urine samples (700 μL) were extracted with ethyl-acetate and subsequently underwent acid back-extraction before and after deconjugation by mild acid hydrolysis. Milrinone was separated on a strong cation exchange analytical column. The mobile phase consisted of a constant mixture of acetonitrile:tetrahydrofurane-NaH2 PO4 buffer (40:60 v/v, pH 3.0). Thirteen calibration curves were linear in the concentration range of 31.25-4000 ng/mL, using olprinone as the internal standard (r(2) range 0.9911-0.9999, n = 13). Mean milrinone recovery and accuracy were respectively 85.2 ± 3.1% and ≥93%. Intra- and inter-day precisions (coefficients of variation) were ≤5% and ≤8%, respectively. Over a 24 h collection period, the cumulative urinary milrinone recovered from 15 patients was 26.1 ± 7.7% of the nominal 5 mg dose administered. The relative amount of milrinone glucuronic acid conjugate was negligible in the urine of patients undergoing cardiopulmonary bypass This method proved to be reliable, specific and accurate to determine the cumulative amount of total milrinone recovered in urine after inhalation. Copyright © 2014 John Wiley & Sons, Ltd.

Simultaneous determination of acetylsalicylic acid and salicylic acid in human plasma by isocratic high-pressure liquid chromatography with post-column hydrolysis and fluorescence detection.

PubMed

Hobl, Eva-Luise; Jilma, Bernd; Ebner, Josef; Schmid, Rainer W

2013-06-01

A selective, sensitive and rapid high-performance liquid chromatography method with post-column hydrolysis and fluorescence detection was developed for the simultaneous quantification of acetylsalicylic acid and its metabolite salicylic acid in human plasma. Following the addition of 2-hydroxy-3-methoxybenzoic acid as internal standard and simple protein precipitation with acetonitrile, the analytes were separated on a ProntoSIL 120 C18 ace-EPS column (150 × 2 mm, 3 µm) protected by a C8 guard column (5 µm). The mobile phase, 10 mm formic acid in water (pH 2.9) and acetonitrile (70:30, v/v), was used at a flow rate of 0.35 mL/min. After on-line post-column hydrolysis of acetylsalicylic acid (ASA) to salicylic acid (SA) by addition of alkaline solution, the analytes were measured at 290 nm (λex ) and 400 nm (λem ). The method was linear in the concentration ranges between 0.05 and 20 ng/μL for both ASA and SA with a lower limit of quantification of 25 pg/μL for SA and 50 pg/μL for ASA. The limit of detection was 15 pg/μL for SA and 32.5 pg/μL for ASA. The analysis of ASA and SA can be carried out within 8 min; therefore this method is suitable for measuring plasma concentrations of salicylates in clinical routine. Copyright © 2012 John Wiley & Sons, Ltd.

A quick, easy, cheap, effective, rugged, and safe sample pretreatment and liquid chromatography with tandem mass spectrometry method for the simultaneous quantification of 33 mycotoxins in Lentinula edodes.

PubMed

Han, Zheng; Feng, Zhihong; Shi, Wen; Zhao, Zhihui; Wu, Yongjiang; Wu, Aibo

2014-08-01

Lentinula edodes, one of the most cultivated edible fungi in the world, are usually neglected for mycotoxins contamination due to the initial thinking of its resistance to mycotoxingenic molds. In the present study, a sensitive and reliable liquid chromatography with tandem mass spectrometry method was developed for the simultaneous quantification of 33 mycotoxins in L. edodes. Targeted mycotoxins were extracted using a quick, easy, cheap, effective, rugged, and safe procedure without any further clean-up step, and analyzed by liquid chromatography with tandem mass spectrometry on an Agilent Poroshell 120 EC-C18 column (100 × 3 mm, 2.7 μm) with a linear gradient elution program using water containing 5 mM ammonium acetate and methanol as the mobile phase. After validation by determining linearity (R(2) > 0.99), sensitivity (LOQ ≤ 20 ng/kg), recovery (73.6-117.9%), and precision (0.8-19.5%), the established method has been successfully applied to reveal the contamination states of various mycotoxins in L. edodes. Among the 30 tested samples, 22 were contaminated by various mycotoxins with the concentration levels ranging from 3.3-28,850.7 μg/kg, predicting that the edible fungus could be infected by the mycotoxins-producing fungi. To the best of our knowledge, this is the first report about real mycotoxins contamination in L. edodes. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Simultaneous determination of tetrahydropalmatine, protopine, and palmatine in rat plasma by LC-ESI-MS and its application to a pharmacokinetic study.

PubMed

Ma, Hongda; Wang, Yongjun; Guo, Tao; He, Zhonggui; Chang, Xinyu; Pu, Xiaohui

2009-02-20

A sensitive and specific liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS) method has been developed and validated for the simultaneous quantification of tetrahydropalmatine, protopine and palmatine in rat plasma using phenacetin as the internal standard (IS). Two hundred microliters plasma samples were extracted by dichloromethane under a strong basic condition. The analytes were separated by a C18 column and detected with a single quadrupole mass spectrometer. The used mobile phase was acetonitrile-water (40:60, v/v) containing 5mM ammonium acetate and 0.2% glacial acetic acid. Detection was carried out by positive electrospray ionization in selected ion reaction (SIR) mode at m/z 356.6 for tetrahydropalmatine, 354.6 for protopine, 352.6 for palmatine and 180.4 for the IS, respectively. The method was validated over the concentration range of 1.00-500ngmL(-1) and the lower limit of quantification (LLOQ) was 1.00ngmL(-1) for all three analytes. The intra- and inter-day precision values were less than 9% relative standard deviation (R.S.D.), and the relative error ranged from -7.4 to 4.8%. The extraction recoveries were on average 91.42% for tetrahydropalmatine, 84.75% for protopine, 57.26% for palmatine, and 83.18% for IS. The validated method was successfully applied to a pharmacokinetic study of tetrahydropalmatine, protopine and palmatine in rats after oral administration of Rhizoma Corydalis Decumbentis extract.

Lithium adduct as precursor ion for sensitive and rapid quantification of 20 (S)-protopanaxadiol in rat plasma by liquid chromatography/quadrupole linear ion trap mass spectrometry and application to rat pharmacokinetic study.

PubMed

Bao, Yuanwu; Wang, Quanying; Tang, Pingming

2013-03-01

A novel, rapid and sensitive liquid chromatography/quadrupole linear ion trap mass spectrometry [LC-ESI-(QqLIT)MS/MS] method was developed and validated for the quantification of protopanaxadiol (PPD) in rat plasma. Oleanolic acid (OA) was used as internal standard (IS). A simple protein precipitation based on acetonitrile (ACN) was employed. Chromatographic separation was performed on a Sepax GP-C18 column (50 × 2.1 mm, 5 μM) with a mobile phase consisting of ACN-water and 1.5 μM formic acid and 25 mM lithium acetate (90 : 10, v/v) at a flow rate of 0.4 ml/min for 3.0 min. Multiple-reaction-monitoring mode was performed using lithium adduct ion as precursor ion of m/z 467.5/449.4 and 455.6/407.4 for the drug and IS, respectively. Calibration curve was recovered over a concentration range of 0.5-100 ng/ml with a correlation coefficient >0.99. The limit of detection was 0.2 ng/ml in rat plasma for PPD. The results of the intraday and interday precision and accuracy studies were well within the acceptable limits. The validated method was successfully applied to investigate the pharmacokinetic study of PPD after intravenous and gavage administration to rat. Copyright © 2013 John Wiley & Sons, Ltd.

[Determination of di (hydrogenated tallow alkyl) dimethyl ammonium compounds in textile auxiliaries by ultra-high performance liquid chromatography-tandem mass spectrometry].

PubMed

Zhu, Feng

2015-01-01

A method has been developed for the determination of di (hydrogenated tallow alkyl) dimethyl ammonium compounds (DHTDMAC) in textile auxiliaries by ultra-high performance liquid chromatography-tandem mass spectrometry. (UPLC-MS/MS). The samples were extracted and diluted with acidified methanol by 5% (v/v) formic acid under ultrasonic assistance. The separation was performed on an Eclipse Plus C18 column (50 mm x 2.1 mm, 1.8 microm) using 0.1% (v/v) formic acid solution and methanol as the mobile phases. Identification and quantification were achieved by UPLC-MS/MS with electrospray ionization (ESI) source in positive ion mode and multiple reaction monitoring (MRM) mode. The results indicated that the calibration curve of DHTDMAC showed good linear relationship between peak area and mass concentration in the range of 10-280 microg/L with the correlation coefficient (r2) of 0.9991. The limit of detection (LOD, S/N=3) and the limit of quantification (LOQ, S/N= 10) of this method were 3 mg/kg and 10 mg/kg, respectively. The average recoveries from three typical textile auxiliary matrices including dispersant, antistatic agent and fabric softener, at three spiked levels were in the range of 97.2%-108.3% with the relative standard deviations (RSDs) of 1.5%-4.6%. The method is sensitive, accurate, simple and effective for the analysis of DHTDMAC in textile auxiliaries.

Development of a fully automated on-line solid phase extraction and high-performance liquid chromatography with diode array detection method for the pharmacokinetic evaluation of bavachinin: a study on absolute bioavailability and dose proportionality.

PubMed

Liu, Lei; Liu, Kang-Ning; Wen, Ya-Bin; Zhang, Han-Wen; Lu, Ya-Xin; Yin, Zheng

2012-04-15

A fully automated on-line solid-phase extraction (SPE) and high-performance liquid chromatography (HPLC) with diode array detection (DAD) method was developed for determination of bavachinin in mouse plasma. Analytical process was performed on two reversed-phase columns (SPE cartridge and analytical column) connected via a Valco 6-port switching valve. Plasma samples (10 μL) were injected directly onto a C18 SPE cartridge (MF Ph-1 C18, 10 mm × 4 mm, 5 μm) and the biological matrix was washed out for 2 min with the loading solvent (5 mM NaH(2)PO(4) buffer, pH 3.5) at a flow rate of 1 mL/min. By rotation of the switching valve, bavachinin was eluted from the SPE cartridge in the back-flush mode and transferred to the analytical column (Venusil MP C18, 4.6 mm × 150 mm, 5 μm) by the chromatographic mobile phase consisted of acetonitrile-5mM NaH(2)PO(4) buffer 65/35 (v/v, pH 3.5) at a flow rate of 1 mL/min. The complete cycle of the on-line SPE purification and chromatographic separation of the analyte was 13 min with UV detection performed at 236 nm. Calibration curve with good linearity (r=0.9997) was obtained in the range of 20-4000 ng/mL in mouse plasma. The intra-day and inter-day precisions (RSD) of bavachinin were in the range of 0.20-2.32% and the accuracies were between 98.47% and 102.95%. The lower limit of quantification (LLOQ) of the assay was 20 ng/mL. In conclusion, the established automated on-line SPE-HPLC-DAD method demonstrated good performance in terms of linearity, specificity, detection and quantification limits, precision and accuracy, and was successfully utilized to quantify bavachinin in mouse plasma to support the pharmacokinetic (PK) studies. The PK properties of bavachinin were characterized as rapid oral absorption, high clearance, and poor absolute bioavailability. Copyright © 2012. Published by Elsevier B.V.

Reverse Phase-ultra Flow Liquid Chromatography-diode Array Detector Quantification of Anticancerous and Antidiabetic Drug Mangiferin from 11 Species of Swertia from India.

PubMed

Kshirsagar, Parthraj R; Gaikwad, Nikhil B; Panda, Subhasis; Hegde, Harsha V; Pai, Sandeep R

2016-01-01

Genus Swertia is valued for its great medicinal potential, mainly Swertia chirayita (Roxb. ex Fleming) H. Karst. is used in traditional medicine for a wide range of diseases. Mangiferin one of xanthoids is referred with enormous pharmacological potentials. The aim of the study was to quantify and compare the anticancerous and antidiabetic drug mangiferin from 11 Swertia species from India. The study also evaluates hierarchical relationships between the species based on mangiferin content using multivariate analysis. The reverse phase-ultra flow liquid chromatography-diode array detector analyses was performed and chromatographic separation was achieved on a Lichrospher 100, C18e (5 μm) column (250-4.6 mm). Mobile phase consisting of 0.2% triethylamine (pH-4 with O-phosphoric acid) and acetonitrile (85:15) was used for separation with injection volume 20 μL and detection wave length at 257 nm. Results indicated that concentration of mangiferin has been found to vary largely between Swertia species collected from different regions. Content of mangiferin was found to be highest in Swertia minor compared to other Swertia species studied herein from the Western Ghats and Himalayan region also. The same was also evident in the multivariate analysis, wherein S. chirayita, S. minor and Swertia paniculata made a separate clade. Conclusively, the work herein provides insights of mangiferin content from 11 Swertia species of India and also presents their hierarchical relationships. To best of the knowledge this is the first report of higher content of mangiferin from any Swertia species. The present study quantifies and compares mangiferin in 11 species of Swertia from India. The study also evaluates hierarchical relationships between the species based on mangiferin content using multivariate analysis. The mangiferin content was highest in S. minor compared to the studied Swertia species. To the best of our knowledge this is the first report of higher content of mangiferin from Swertia species. Abbreviations used: LOD: Limit of detection, LOQ: Limit of quantification, RP-UFLC-DAD: Reverse phase-ultra flow liquid chromatography-diode array detector, RSD: Relative standard deviation, SAN: Swertia angustifolia, SAP: Swertia angustifolia var. pulchella, SBI: S. bimaculata, SCH: S. chirayita, SCO: S. corymbosa, SDE: S. densifolia, SDI: S. dialatata, SLA: S. lawii, SMI: S. minor; SNE: S. nervosa, and SPA: S. paniculata.

Use of vancomycin silica stationary phase in packed capillary electrochromatography: III. enantiomeric separation of basic compounds with the polar organic mobile phase.

PubMed

Fanali, Salvatore; Catarcini, Paolo; Quaglia, Maria Giovanna

2002-02-01

The separation of basic compounds into their enantiomers was achieved using capillary electrochromatography in 50 or 75 microm inner diameter (ID) fused-silica capillaries packed with silica a stationary phase derivatized with vancomycin and mobile phases composed of mixtures of polar organic solvents containing 13 mM ammonium acetate. Enantiomer resolution, electroosmotic flow, and the number of theoretical plates were strongly influenced by the type and concentration of the organic solvent. Mobile phases composed of 13 mM ammonium acetate dissolved in mixtures of acetonitrile/methanol, ethanol, n-propanol, or isopropanol were tested and the highest enantioresolutions were achieved using the first mobile phase, allowing the separation of almost all investigated enantiomers (9 from 11 basic compounds). The use of capillaries with different ID (50 and 75 microm ID) packed with the same chiral stationary phase revealed that a higher number of theoretical plates and higher enantioresolution was achieved with the tube with lowest ID.

Detection of Secondary Phases in UNS S32760 Superduplex Stainless Steel by Destructive and Non-destructive Techniques

NASA Astrophysics Data System (ADS)

Argandona, G.; Biezma, M. V.; Berrueta, J. M.; Berlanga, C.; Ruiz, A.

2016-12-01

Duplex stainless steels (DSS), with a microstructure of an approximately equal mixture of ferrite ( α) and austenite ( γ) phases, are susceptible to the formation of undesirable phases if manufacturing processes are not carefully controlled. In particular, sigma phase (σ) is a Cr- and Mo-rich intermetallic phase, formed generally when DSS are by the temperature range from 600 to 900 °C, even for very short time periods. The precipitation of this phase induces detrimental effects in mechanical and corrosion resistance properties in the material, and even a low volume percentage of σ phase can significantly affect these properties. The current paper presents the effect of thermal treatments on UNS S32760 superduplex stainless steel seamless tubes, applied in order to promote the precipitation of different σ phase percentages in a ferrite/austenite microstructure. The detection and quantification of the σ phase using non-destructive ultrasounds testing has been one of the most relevant events of this study that contributes to improving the correlation of the results obtained using destructive and non-destructive techniques for the quantification of undesirable phases in superduplex seamless tubes during the manufacturing process.

Sol-gel electrospinning preparation of hybrid carbon silica nanofibers for extracting organophosphorus pesticides prior to analyzing them by gas chromatography-ion mobility spectrometry.

PubMed

Jafari, Mohammad T; Saraji, Mohammad; Kermani, Mansoure

2018-07-13

Carbon-silica hybrid nanofibers as high performance coatings for solid-phase microextraction fibers were used for analyzing some pesticides by using gas chromatography-corona discharge ion mobility spectrometry. To that end, the fibers were prepared by carbonizing sol-gel based on electrospun polyacrylonitrile and tetraethyl orthosilicate nanofibers as carbon and silica precursors, respectively. Different parameters affecting the electrospinning and the extraction processes including spinning distance, voltage, feeding rate, stirring rate, salt concentration, temperature and extraction time were optimized by response surface methodology. The method involved deionized water samples spiked with pesticides at different concentration levels. The calibration curves were linear in the ranges of 0.1-20 and 0.05-20 μg L -1 with determination coefficients (R 2 ) of 0.9976 and 0.9928 for malathion and chlorpyrifos, respectively. The limits of detection of 0.032 and 0.019 μg L -1 and the limits of quantification of 0.1 and 0.05 μg L -1 were found for malathion and chlorpyrifos, respectively. Acceptable reproducibility values were obtained with relative standard deviations (RSD, n = 3) lower than 6 and 15%, for intra-day and inter-day precision, respectively. Finally, the relative recoveries of the proposed method were calculated in the range of 80-111% for real samples. Copyright © 2018 Elsevier B.V. All rights reserved.

Smartphone-Based Mobile Detection Platform for Molecular Diagnostics and Spatiotemporal Disease Mapping.

PubMed

Song, Jinzhao; Pandian, Vikram; Mauk, Michael G; Bau, Haim H; Cherry, Sara; Tisi, Laurence C; Liu, Changchun

2018-04-03

Rapid and quantitative molecular diagnostics in the field, at home, and at remote clinics is essential for evidence-based disease management, control, and prevention. Conventional molecular diagnostics requires extensive sample preparation, relatively sophisticated instruments, and trained personnel, restricting its use to centralized laboratories. To overcome these limitations, we designed a simple, inexpensive, hand-held, smartphone-based mobile detection platform, dubbed "smart-connected cup" (SCC), for rapid, connected, and quantitative molecular diagnostics. Our platform combines bioluminescent assay in real-time and loop-mediated isothermal amplification (BART-LAMP) technology with smartphone-based detection, eliminating the need for an excitation source and optical filters that are essential in fluorescent-based detection. The incubation heating for the isothermal amplification is provided, electricity-free, with an exothermic chemical reaction, and incubation temperature is regulated with a phase change material. A custom Android App was developed for bioluminescent signal monitoring and analysis, target quantification, data sharing, and spatiotemporal mapping of disease. SCC's utility is demonstrated by quantitative detection of Zika virus (ZIKV) in urine and saliva and HIV in blood within 45 min. We demonstrate SCC's connectivity for disease spatiotemporal mapping with a custom-designed website. Such a smart- and connected-diagnostic system does not require any lab facilities and is suitable for use at home, in the field, in the clinic, and particularly in resource-limited settings in the context of Internet of Medical Things (IoMT).

Occurrence of acidic PPCPs in surface and drinking waters by UHPLC-MS/MS

NASA Astrophysics Data System (ADS)

Picó, Yolanda; Carmona, Eric; Andreu, Vicente

2015-04-01

The term "emerging pollutants" stands for the substances that are released in the environment for which currently no regulations are established for their environmental monitoring. Their occurrence is reported worldwide in a range of aquatic environments, such as lakes, rivers, freshwater catchments, estuaries, reservoirs and marine waters. However, there are still few studies on their occurrence, levels and distribution in River Basins from Spain. This study is aimed at contributing information on the occurrence of three groups of emerging contaminants -licit and illicit drugs and personal care products- in the Turia River Basin. This River is a 280-km Mediterranean River with a flow rate 10.43 m3/s (Carmona et al., 2011), which is born in the province of Teruel and flows near the Valencia city. It has been selected because it is a typical Mediterranean River heavily affected by drought. The most 14 drank waters in Spain were analyzed to determinate the occurrence of some emerging pollutants. Selected contaminants include more than 40 pharmaceuticals, 5 personal care products and two illicit drugs. These substances were determined with an Agilent Technologies HPLC linked with a Triple Quad LC/MS in positive and negative ion mode using for compound separation a Waters C18 analytical column of 2.1x50mm and 3.5 µm particle diameter from Sunfire. The optimal mobile phase was a gradient of 5mM Ammonium fluoride in water (mobile phase A) and 5mM Ammonium fluoride in methanol (mobile phase B), at a flow rate of 0.2mL/min with a gradient that starts with 30% of mobile phase B and increase until 95% at minute 12 and remains 13 minutes more. The analytes were extracted from 250 mL of water by solid-phase extraction using Strata-X cartridges, eluted with methanol, evaporated and dissolved in 250 µL of methanol (Carmona et al. 2014). This procedure provides acceptable recoveries (>70%) and relative standard deviation (RSDs < 20%) at the limits of quantification, which are in the low ppb range ensuring sensitivity enough. Some of the studied compounds were detect at low amounts in the analysed water, which establish the real environmental occurrence of these potential contaminants. Further research will be devoted to characterize their sources and source pathways as well as to define and quantify processes that determine their transport and fate through the Turia River and to identify potential ecologic effects. Acknowledgment The Spanish Ministry of Economy and Competitiveness has supported this work through the projects SCARCE-CSD2009-00065, CGL2011-29703-C02-01 and CGL2011-29703-C02-02 References Carmona P., Ruiz J.M., Historical morphogenesis of the Turia River coastal flood plain in the Mediterranean littoral of Spain, CATENA, Volume 86, Issue 3, September 2011, Pages 139-149. Carmona, E., Andreu, V., Picó, Y., Occurrence of acidic pharmaceuticals and personal care products in Turia River Basin: from waste to drinking water. Science of the Total Environment (2014), vol. 484 pp. 53-63.

Simultaneous and enantioselective determination of cis-epoxiconazole and indoxacarb residues in various teas, tea infusion and soil samples by chiral high performance liquid chromatography coupled with tandem quadrupole-time-of-flight mass spectrometry.

PubMed

Zhang, Xinzhong; Luo, Fengjian; Lou, Zhengyun; Lu, Meiling; Chen, Zongmao

2014-09-12

A novel and sensitive method for simultaneous enantiomeric analysis of two pesticides-cis-epoxiconazole and indoxacarb-in various teas, black tea infusion, and soil samples has been developed. The samples were initially subjected to acetonitrile extraction followed by cleanup using lab-made florisil/graphitized carbon black mixed solid phase extraction (SPE) column (for the different teas and soil samples) and a BondElut C18-SPE column (for the black tea infusion samples). Separation of the analytes was performed on a chiral stationary phase using high performance liquid chromatography (HPLC) under a reversed-phase isocratic elution mode followed by tandem quadrupole time-of-flight mass spectrometry (Q-TOF/MS) detection. The mobile phase components, mobile phase ratios, flow rates, column temperatures, and MS parameters were all optimized to reach high sensitivity and selectivity, good peak shape, and satisfactory resolution. The performance of the method was evaluated based on the sensitivity, linearity, accuracy, precision, and matrix effects. Under optimal conditions, for the various teas (green tea, black tea, and puer tea), fresh tea leaf, soil and black tea infusion samples spiked at low, medium, and high levels, the mean recoveries for the four enantiomers ranged from 61.0% to 129.7% with most relative standard deviations (RSDs) being 17.1% or below. Good linearity can be achieved with regression coefficients (R) of 0.9915 or above for all target enantiomers, and matrix-matched calibration concentration ranging from 5.0 to 1000μg/L. The limits of detection (LODs) for all four target enantiomers were 1.4μg/kg or below in the different teas and soil samples and 0.05μg/kg or below in the black tea infusion, whereas the limits of quantification (LOQs) for those did not exceed 5.0μg/kg and 0.2μg/L, respectively. The proposed method is convenient and reliable and has been applied to real tea samples screening. It has also been extended for studies on the degradation kinetics and environmental behaviors in the field trials, providing additional information for reliable risk assessment of these chiral pesticides. Copyright © 2014 Elsevier B.V. All rights reserved.

A validated ultra high pressure liquid chromatographic method for qualification and quantification of folic acid in pharmaceutical preparations.

PubMed

Deconinck, E; Crevits, S; Baten, P; Courselle, P; De Beer, J

2011-04-05

A fully validated UHPLC method for the identification and quantification of folic acid in pharmaceutical preparations was developed. The starting conditions for the development were calculated starting from the HPLC conditions of a validated method. These start conditions were tested on four different UHPLC columns: Grace Vision HT™ C18-P, C18, C18-HL and C18-B (2 mm × 100 mm, 1.5 μm). After selection of the stationary phase, the method was further optimised by testing two aqueous and two organic phases and by adapting to a gradient method. The obtained method was fully validated based on its measurement uncertainty (accuracy profile) and robustness tests. A UHPLC method was obtained for the identification and quantification of folic acid in pharmaceutical preparations, which will cut analysis times and solvent consumption. Copyright © 2010 Elsevier B.V. All rights reserved.

Identification, Attribution, and Quantification of Highly Heterogeneous Methane Sources Using a Mobile Stable Isotope Analyzer

NASA Astrophysics Data System (ADS)

Crosson, E.; Rella, C.; Cunningham, K.

2012-04-01

Despite methane's importance as a potent greenhouse gas second only to carbon dioxide in the magnitude of its contribution to global warming, natural contributions to the overall methane budget are only poorly understood. A big contributor to this gap in knowledge is the highly spatially and temporally heterogeneous nature of most natural (and for that matter anthropogenic) methane sources. This high degree of heterogeneity, where the methane emission rates can vary over many orders of magnitude on a spatial scale of meters or even centimeters, and over a temporal scale of minutes or even seconds, means that traditional methods of emissions flux estimation, such as flux chambers or eddy-covariance, are difficult or impossible to apply. In this paper we present new measurement methods that are capable of detecting, attributing, and quantifying emissions from highly heterogeneous sources. These methods take full advantage of the new class of methane concentration and stable isotope analyzers that are capable of laboratory-quality analysis from a mobile field platform in real time. In this paper we present field measurements demonstrating the real-time detection of methane 'hot spots,' attribution of the methane to a source process via real-time stable isotope analysis, and quantification of the emissions flux using mobile concentration measurements of the horizontal and vertical atmospheric dispersion, combined with atmospheric transport calculations. Although these techniques are applicable to both anthropogenic and natural methane sources, in this initial work we focus primarily on landfills and fugitive emissions from natural gas distribution, as these sources are better characterized, and because they provide a more reliable and stable source of methane for quantifying the measurement uncertainty inherent in the different methods. Implications of these new technologies and techniques are explored for the quantification of natural methane sources in a variety of environments, including wetlands, peatlands, and the arctic.

Use of low volatility mobile phases in electroosmotic thin-layer chromatography.

PubMed

Berezkin, V G; Balushkin, A O; Tyaglov, B V; Litvin, E F

2005-08-19

A variant of electroosmotic thin-layer chromatography is suggested with the use of low volatility compounds as mobile phases aimed at drastically decreasing the evaporation of the mobile phase and improving the reproducibility of the method. The linear movement velocity of zones of separated compounds is experimentally shown to increase 2-12-fold in electroosmotic chromatography (compared to similar values in traditional TLC). The separation efficiency is also considerably increased.

Oral Administration of (S)-Allyl-l-Cysteine and Aged Garlic Extract to Rats: Determination of Metabolites and Their Pharmacokinetics.

PubMed

Park, Taehoon; Oh, Ju-Hee; Lee, Joo Hyun; Park, Sang Cheol; Jang, Young Pyo; Lee, Young-Joo

2017-11-01

( S )-Allyl-l-cysteine is the major bioactive compound in garlic. ( S )-Allyl-l-cysteine is metabolized to ( S )-allyl-l-cysteine sulfoxide, N -acetyl-( S )-allyl-l-cysteine, and N -acetyl-( S )-allyl-l-cysteine sulfoxide after oral administration. An accurate LC-MS/MS method was developed and validated for the simultaneous quantification of ( S )-allyl-l-cysteine and its metabolites in rat plasma, and the feasibility of using it in pharmacokinetic studies was tested. The analytes were quantified by multiple reaction monitoring using an atmospheric pressure ionization mass spectrometer. Because significant quantitative interference was observed between ( S )-allyl-l-cysteine and N -acetyl-( S )-allyl-l-cysteine as a result of the decomposition of N -acetyl-( S )-allyl-l-cysteine at the detector source, chromatographic separation was required to discriminate ( S )-allyl-l-cysteine and its metabolites on a reversed-phase C 18 analytical column with a gradient mobile phase consisting of 0.1% formic acid and acetonitrile. The calibration curves of ( S )-allyl-l-cysteine, ( S )-allyl-l-cysteine sulfoxide, N -acetyl-( S )-allyl-l-cysteine, and N -acetyl-( S )-allyl-l-cysteine sulfoxide were linear over each concentration range, and the lower limits of quantification were 0.1 µg/mL [( S )-allyl-l-cysteine and N -acetyl-( S )-allyl-l-cysteine] and 0.25 µg/mL [( S )-allyl-l-cysteine sulfoxide and N -acetyl-( S )-allyl-l-cysteine sulfoxide]. Acceptable intraday and inter-day precisions and accuracies were obtained at three concentration levels. The method satisfied the regulatory requirements for matrix effects, recovery, and stability. The validated LC-MS/MS method was successfully used to determine the concentration of ( S )-allyl-l-cysteine and its metabolites in rat plasma samples after the administration of ( S )-allyl-l-cysteine or aged garlic extract. Georg Thieme Verlag KG Stuttgart · New York.

A Study of Method Development, Validation, and Forced Degradation for Simultaneous Quantification of Paracetamol and Ibuprofen in Pharmaceutical Dosage Form by RP-HPLC Method

PubMed Central

Jahan, Md. Sarowar; Islam, Md. Jahirul; Begum, Rehana; Kayesh, Ruhul; Rahman, Asma

2014-01-01

A rapid and stability-indicating reversed phase high-performance liquid chromatography (RP-HPLC) method was developed for simultaneous quantification of paracetamol and ibuprofen in their combined dosage form especially to get some more advantages over other methods already developed for this combination. The method was validated according to United States Pharmacopeia (USP) guideline with respect to accuracy, precision, specificity, linearity, solution stability, robustness, sensitivity, and system suitability. Forced degradation study was validated according to International Conference on Harmonisation (ICH). For this, an isocratic condition of mobile phase comprising phosphate buffer (pH 6.8) and acetonitrile in a ratio of 65:35, v/v at a flow rate of 0.7 mL/minute over RP C18 (octadecylsilane (ODS), 150 × 4.6 mm, 5 μm, Phenomenex Inc.) column at ambient temperature was maintained. The method showed excellent linear response with correlation coefficient (R2) values of 0.999 and 1.0 for paracetamol and ibuprofen respectively, which were within the limit of correlation coefficient (R2 > 0.995). The percent recoveries for two drugs were found within the acceptance limit of (97.0–103.0%). Intra-and inter-day precision studies of the new method were less than the maximum allowable limit percentage of relative standard deviation (%RSD) ≤ 2.0. Forced degradation of the drug product was carried out as per the ICH guidelines with a view to establishing the stability-indicating property of this method and providing useful information about the degradation pathways, degradation products, and how the quality of a drug substance and drug product changes with time under the influence of various stressing conditions. The degradation of ibuprofen was within the limit (5–20%, according to the guideline of ICH), while paracetamol showed <20% degradation in oxidation and basic condition. PMID:25452691

A Study of Method Development, Validation, and Forced Degradation for Simultaneous Quantification of Paracetamol and Ibuprofen in Pharmaceutical Dosage Form by RP-HPLC Method.

PubMed

Jahan, Md Sarowar; Islam, Md Jahirul; Begum, Rehana; Kayesh, Ruhul; Rahman, Asma

2014-01-01

A rapid and stability-indicating reversed phase high-performance liquid chromatography (RP-HPLC) method was developed for simultaneous quantification of paracetamol and ibuprofen in their combined dosage form especially to get some more advantages over other methods already developed for this combination. The method was validated according to United States Pharmacopeia (USP) guideline with respect to accuracy, precision, specificity, linearity, solution stability, robustness, sensitivity, and system suitability. Forced degradation study was validated according to International Conference on Harmonisation (ICH). For this, an isocratic condition of mobile phase comprising phosphate buffer (pH 6.8) and acetonitrile in a ratio of 65:35, v/v at a flow rate of 0.7 mL/minute over RP C18 (octadecylsilane (ODS), 150 × 4.6 mm, 5 μm, Phenomenex Inc.) column at ambient temperature was maintained. The method showed excellent linear response with correlation coefficient (R (2)) values of 0.999 and 1.0 for paracetamol and ibuprofen respectively, which were within the limit of correlation coefficient (R (2) > 0.995). The percent recoveries for two drugs were found within the acceptance limit of (97.0-103.0%). Intra-and inter-day precision studies of the new method were less than the maximum allowable limit percentage of relative standard deviation (%RSD) ≤ 2.0. Forced degradation of the drug product was carried out as per the ICH guidelines with a view to establishing the stability-indicating property of this method and providing useful information about the degradation pathways, degradation products, and how the quality of a drug substance and drug product changes with time under the influence of various stressing conditions. The degradation of ibuprofen was within the limit (5-20%, according to the guideline of ICH), while paracetamol showed <20% degradation in oxidation and basic condition.

[Determination of six anticoccidials in chicken using QuEChERS combined with ultra high liquid chromatography-high resolution mass spectrometry].

PubMed

Muharem, Muhteber; Yan, Hua; Xu, Shan; Feng, Nan; Hao, Jie; Zhu, Chenqi; Guo, Shuang; Zhang, Zhaohui; Han, Nanyin

2015-11-01

An ultra high liquid chromatography-Q Exactive orbitrap mass spectrometry multi-residue method has been developed for the determination of six anticoccidials residues (dinitlmide, nicarbazin, diclazuril, toltrazuril, monensin and salinomycin) in chicken tissue. Sample preparation was based on QuEChERS method, using 1% (v/v) trichloroacetic acid/acetonitrile aqueous solution (3:7, v/v) as the extraction solvent and salting-out with sodium chloride followed by clean-up with 50 mg/mL primary secondary amine (PSA) +50 mg/mL neutral alumina (Alumina-N) dispersive solid phase extraction (DSPE). The separation of the compounds in liquid chromatography was carried out using a Waters Acquity UPLC BEH C8 column (100 mm x 2.1 mm, 1.7 μm) with mobile phases consisting of methanol-5 mmol/L ammonium acetate aqueous solution in gradient elution. The Q Exactive orbitrap mass spectrometric detection was carried out with positive and negative electrospray ionization simultaneously. The results showed the linear ranges of the six target compounds were as follows: dinitolmide, 1.0-30.0 μg/L; nicarbazin, 0.2-6.0 μg/L; diclazuril and toltrazuril, 2.0-60.0 [μg/L; monensin and salinomycin, 4.0-120.0 μg/L. The external standard method was used for quantification. The spiked recoveries at three levels for the six anticoccidials ranged from 67.7% to 126.8%. The relative standard deviations (RSDs) were ≤ 10.4%. The limits of quantification (LOQs) were as follows: dinitolmide, 2.50 μg/kg; nicarbazin, 0.50 μg/kg; diclazuril and toltrazuril, 5.00 μg/kg; monensin and salinomycin, 20.00 μg/kg. The developed method is easy of operation and of high sensitivity. It can meet the requirements of daily inspection.

Dried Blood Spots Combined With Ultra-High-Performance Liquid Chromatography-Mass Spectrometry for the Quantification of the Antipsychotics Risperidone, Aripiprazole, Pipamperone, and Their Major Metabolites.

PubMed

Tron, Camille; Kloosterboer, Sanne M; van der Nagel, Bart C H; Wijma, Rixt A; Dierckx, Bram; Dieleman, Gwen C; van Gelder, Teun; Koch, Birgit C P

2017-08-01

Risperidone, aripiprazole, and pipamperone are antipsychotic drugs frequently prescribed for the treatment of comorbid behavioral problems in children with autism spectrum disorders. Therapeutic drug monitoring (TDM) could be useful to decrease side effects and to improve patient outcome. Dried blood spot (DBS) sample collection seems to be an attractive technique to develop TDM of these drugs in a pediatric population. The aim of this work was to develop and validate a DBS assay suitable for TDM and home sampling. Risperidone, 9-OH risperidone, aripiprazole, dehydroaripiprazole, and pipamperone were extracted from DBS and analyzed by ultra-high-performance liquid chromatography-tandem mass spectrometry using a C18 reversed-phase column with a mobile phase consisting of ammonium acetate/formic acid in water or methanol. The suitability of DBS for TDM was assessed by studying the influence of specific parameters: extraction solution, EDTA carryover, hematocrit, punching location, spot volume, and hemolysis. The assay was validated with respect to conventional guidelines for bioanalytical methods. The method was linear, specific without any critical matrix effect, and with a mean recovery around 90%. Accuracy and imprecision were within the acceptance criteria in samples with hematocrit values from 30% to 45%. EDTA or hemolysis did not skew the results, and no punching carryover was observed. No significant influence of the spot volume or the punch location was observed. The antipsychotics were all stable in DBS stored 10 days at room temperature and 1 month at 4 or -80°C. The method was successfully applied to quantify the 3 antipsychotics and their metabolites in patient samples. A UHPLC-MS/MS method has been successfully validated for the simultaneous quantification of risperidone, 9-OH risperidone, aripiprazole, dehydroaripiprazole, and pipamperone in DBS. The assay provided good analytical performances for TDM and clinical research applications.

Simultaneous detection and quantification of amphetamines, diazepam and its metabolites, cocaine and its metabolites, and opiates in hair by LC-ESI-MS-MS using a single extraction method.

PubMed

Miller, Eleanor I; Wylie, Fiona M; Oliver, John S

2008-09-01

A liquid chromatography-tandem mass spectrometry method was developed and validated for the simultaneous identification and quantification of amphetamines, diazepam and its metabolites, cocaine and its metabolites, and opiates from hair using a single extraction method. As part of the method development, Gemini C18, Synergi Hydro RP, and Zorbax Stablebond-Phenyl LC columns were tested with three different mobile phases. Analyte recovery and limit of detection were evaluated for two different solid-phase extraction methods that used Bond Elut Certify and Clean Screen cartridges. Phosphate buffer (pH 5.0) was chosen as the optimum hair incubation medium because of the high stability of cocaine and 6-monoacetylmorphine using this method and faster sample preparation. The optimized method was fully validated. Linearity was established over the concentration range 0.2-10 ng/mg hair, and the correlation coefficients were all greater than 0.99. Total extraction recoveries were greater than 76%, detection limits were between 0.02 and 0.09 ng/mg, and the intra- and interday imprecisions were generally less than 20% in spiked hair. The intra- and interbatch imprecision of the method for a pooled authentic hair sample ranged from 1.4 to 23.4% relative standard deviation (RSD) and 8.3 to 25.4% RSD, respectively, for representative analytes from the different drug groups. The percent matrix effect ranged from 63.5 to 135.6%, with most analytes demonstrating ion suppression. Sixteen postmortem samples collected from suspected drug-related deaths were analyzed for the 17 drugs of abuse and metabolites included in the method. The method was sufficiently sensitive and specific for the analysis of drugs and metabolites in postmortem hair samples. There is scope for the inclusion of other target drugs and metabolites in the method.

Development and Validation of a UPLC-MS/MS and UPLC-HR-MS Method for the Determination of Fumonisin B1 and Its Hydrolysed Metabolites and Fumonisin B2 in Broiler Chicken Plasma.

PubMed

De Baere, Siegrid; Croubels, Siska; Novak, Barbara; Bichl, Gerlinde; Antonissen, Gunther

2018-01-31

A sensitive and specific method for the quantitative determination of Fumonisin B1 (FB1), its partially hydrolysed metabolites pHFB1a+b and hydrolysed metabolite HFB1, and Fumonisin B2 (FB2) in broiler chicken plasma using ultra-performance liquid chromatography combined with tandem mass spectrometry (UPLC-MS/MS) was developed. The sample preparation was rapid, straightforward and consisted of a deproteinization and phospholipid removal step using an Oasis ® Ostro TM 96-well plate. Chromatography was performed on an Acquity HSS-T3 column, using 0.3% formic acid and 10 mM ammonium formate in water, and acetonitrile as mobile phases. The MS/MS instrument was operated in the positive electrospray ionization mode and the two multiple reaction monitoring transitions were monitored for each component for quantification and identification, respectively. The method was validated in-house: matrix-matched calibration graphs were prepared and good linearity (r ≥ 0.99) was achieved over the concentration ranges tested (1-500 ng/mL for FB1 and FB2; 0.86-860 ng/mL for pHFB1a; 0.72-1430 ng/mL for pHFB1b and 2.5-2500 ng/mL for HFB1). Limits of quantification (LOQ) and detection (LOD) in plasma ranged between 0.72 to 2.5 ng/mL and 0.03 to 0.17 ng/mL, respectively. The results for the within-day and between-day precision and accuracy fell within the specified ranges. Moreover, the method was transferred to an UPLC high-resolution mass spectrometry (HR-MS) instrument in order to determine potential metabolites of HFB1, such as N-acyl-HFB1s and phase II metabolites. The method has been successfully applied to investigate the toxicokinetics and biotransformation of HFB1 in broiler chickens.

Development and Validation of a UPLC-MS/MS and UPLC-HR-MS Method for the Determination of Fumonisin B1 and Its Hydrolysed Metabolites and Fumonisin B2 in Broiler Chicken Plasma

PubMed Central

De Baere, Siegrid; Novak, Barbara; Bichl, Gerlinde

2018-01-01

A sensitive and specific method for the quantitative determination of Fumonisin B1 (FB1), its partially hydrolysed metabolites pHFB1a+b and hydrolysed metabolite HFB1, and Fumonisin B2 (FB2) in broiler chicken plasma using ultra-performance liquid chromatography combined with tandem mass spectrometry (UPLC-MS/MS) was developed. The sample preparation was rapid, straightforward and consisted of a deproteinization and phospholipid removal step using an Oasis® OstroTM 96-well plate. Chromatography was performed on an Acquity HSS-T3 column, using 0.3% formic acid and 10 mM ammonium formate in water, and acetonitrile as mobile phases. The MS/MS instrument was operated in the positive electrospray ionization mode and the two multiple reaction monitoring transitions were monitored for each component for quantification and identification, respectively. The method was validated in-house: matrix-matched calibration graphs were prepared and good linearity (r ≥ 0.99) was achieved over the concentration ranges tested (1–500 ng/mL for FB1 and FB2; 0.86–860 ng/mL for pHFB1a; 0.72–1430 ng/mL for pHFB1b and 2.5–2500 ng/mL for HFB1). Limits of quantification (LOQ) and detection (LOD) in plasma ranged between 0.72 to 2.5 ng/mL and 0.03 to 0.17 ng/mL, respectively. The results for the within-day and between-day precision and accuracy fell within the specified ranges. Moreover, the method was transferred to an UPLC high-resolution mass spectrometry (HR-MS) instrument in order to determine potential metabolites of HFB1, such as N-acyl-HFB1s and phase II metabolites. The method has been successfully applied to investigate the toxicokinetics and biotransformation of HFB1 in broiler chickens. PMID:29385109

Simultaneous detection and quantification of parecoxib and valdecoxib in canine plasma by HPLC with spectrofluorimetric detection: development and validation of a new methodology.

PubMed

Saccomanni, G; Giorgi, M; Del Carlo, S; Manera, C; Saba, A; Macchia, M

2011-09-01

Parecoxib is the injectable prodrug of valdecoxib, a cicloxygenase-2 selective drug, currently used in human medicine. Recent studies have suggested both its excellent clinical effectiveness and wide safety profile. The aim of the present study was to develop and validate a new high-performance liquid chromatography (HPLC) with spectrofluorimetric detection method to quantify parecoxib and valdecoxib in canine plasma. Several parameters both in the extraction and the detection method were evaluated. The applicability of the method was determined by administering parecoxib to one dog: the protocol provided the expected pharmacokinetic results. The final mobile phase was acetonitrile: AcONH(4) (10 mM; pH 5.0) 55:45, v/v, with a flow rate of 0.4 mL min(-1), and excitation and emission wavelengths of 265 and 375 nm, respectively. The analytical column was a reverse-phase C18 ODS2 3-μm particle size. Protein precipitation in acidic medium followed by two successive liquid-liquid steps was carried out. The best extraction solvent was cyclohexane:Et(2)O (3:2, v/v) that gave recoveries ranging from 81.1% to 89.1% and from 94.8% to 103.6% for parecoxib and valdecoxib, respectively. The limits of quantification were 25 and 10 ng mL(-1) for parecoxib and valdecoxib, respectively. The chromatographic runs were specific with no interfering peaks at the retention times of the analytes, as confirmed by HPLC-mass spectrometry experiments. The other validation parameters were in agreement with the European Medicines Evaluation Agency and International Conference on Harmonisation guidelines. In conclusion, this method (extraction, separation and applied techniques) is simple and effective. This is the first time that use of a HPLC with spectrofluorimetric detection technique to simultaneously detect parecoxib and valdecoxib in plasma has been reported. This technique may have applications for pharmacokinetic studies.

Determination and quantification of active phenolic compounds in pigeon pea leaves and its medicinal product using liquid chromatography–tandem mass spectrometry.

PubMed

Liu, Wei; Kong, Yu; Zu, Yuangang; Fu, Yujie; Luo, Meng; Zhang, Lin; Li, Ji

2010-07-09

A novel method using liquid chromatography coupled to electrospray ionization mass spectrometry (LC-ESI-MS) has been optimized and established for the qualitative and quantitative analysis of ten active phenolic compounds originating from the pigeon pea leaves and a medicinal product thereof (Tongluo Shenggu capsules). In the present study, the chromatographic separation was achieved by means of a HiQ Sil C18V reversed-phase column with a mobile phase consisting of methanol and 0.1% formic acid aqueous solution. Low-energy collision-induced dissociation tandem mass spectrometry (CID-MS/MS) using the selected reaction monitoring (SRM) analysis was employed for the detection of ten analytes which included six flavonoids, two isoflavonoids and two stilbenes. All calibration curves showed excellent coefficients of determination (r(2) ≥ 0.9937) within the range of tested concentrations. The intra- and inter-day variations were below 5.36% in terms of relative standard deviation (RSD). The recoveries were 95.08-104.98% with RSDs of 2.06-4.26% for spiked samples of pigeon pea leaves. The method developed was a rapid, efficient and accurate LC-MS/MS method for the detection of phenolic compounds, which can be applied for quality control of pigeon pea leaves and related medicinal products.

Determination of human insulin in dog plasma by a selective liquid chromatography-tandem mass spectrometry method: Application to a pharmacokinetic study.

PubMed

Dong, Shiqi; Zeng, Yong; Wei, Guangli; Si, Duanyun; Liu, Changxiao

2018-03-01

A simple, sensitive and selective LC-MS/MS method for quantitative analysis of human insulin was developed and validated in dog plasma. Insulin glargine was used as the internal standard. After a simple step of solid-phase extraction, the chromatographic separation of human insulin was achieved by using InertSustain Bio C18 column with a mobile phase of acetonitrile containing 1% formic acid (A)-water containing 1% formic acid (B). The detection was performed by positive ion electrospray ionization in multiple-reaction monitoring (MRM) mode. Good linearity was observed in the concentration range of 1-1000 μIU/mL (r 2  > 0.99), and the lower limit of quantification was 1 μIU/mL (equal to 38.46 pg/mL). The intra- and inter-day precision (expressed as relative standard deviation, RSD) of human insulin were ≤12.1% and ≤13.0%, respectively, and the accuracy (expressed as relative error, RE) was in the range of -7.23-11.9%. The recovery and matrix effect were both within acceptable limits. This method was successfully applied for the pharmacokinetic study of human insulin in dogs after subcutaneous administration. Copyright © 2018 Elsevier B.V. All rights reserved.

Preparative separation of α- and β-santalenes and (Z)-α- and (Z)-β-santalols using silver nitrate-impregnated silica gel medium pressure liquid chromatography and analysis of sandalwood oil.

PubMed

Daramwar, Pankaj P; Srivastava, Prabhakar Lal; Priyadarshini, Balaraman; Thulasiram, Hirekodathakallu V

2012-10-07

The major sesquiterpene constituents of East-Indian sandalwood oil (Z)-α- and (Z)-β-santalols have shown to be responsible for most of the biological activities and organoleptic properties of sandalwood oil. The work reported here describes the strategic use of medium pressure liquid chromatography (MPLC) for the separation of both α- and β-santalenes and (Z)-α- and (Z)-β-santalols. Silver nitrate impregnated silica gel was used as the stationary phase in MPLC for quantitative separation of α- and β-santalenes and (Z)-α- and (Z)-β-santalols with mobile phases hexane and dichloromethane, respectively. The purities of α-santalene and (Z)-α-santalol obtained were >96%; however, β-santalene and (Z)-β-santalol were obtained with their respective inseparable epi-isomers. Limits of quantification (LoQ) relative to the FID detector were measured for important sesquiterpene alcohols of heartwood oil of S. album using serial dilutions of the standard stock solutions and demonstrated that the quality of the commercial sandalwood oil can be assessed for the content of individual sesquiterpene alcohols regulated by Australian Standard (AS2112-2003), International Organization for Standardization ISO 3518:2002 (E) and European Union (E. U.).

A validated high-performance liquid chromatography method with diode array detection for simultaneous determination of nine flavonoids in Senecio cannabifolius Less.

PubMed

Niu, Tian-Zeng; Zhang, Yu-Wei; Bao, Yong-Li; Wu, Yin; Yu, Chun-Lei; Sun, Lu-Guo; Yi, Jing-Wen; Huang, Yan-Xin; Li, Yu-Xin

2013-03-25

A reversed phase high performance liquid chromatography method coupled with a diode array detector (HPLC-DAD) was developed for the first time for the simultaneous determination of 9 flavonoids in Senecio cannabifolius, a traditional Chinese medicinal herb. Agilent Zorbax SB-C18 column was used at room temperature and the mobile phase was a mixture of acetonitrile and 0.5% formic acid (v/v) in water in the gradient elution mode at a flow-rate of 1.0mlmin(-1), detected at 360nm. Validation of this method was performed to verify the linearity, precision, limits of detection and quantification, intra- and inter-day variabilities, reproducibility and recovery. The calibration curves showed good linearities (R(2)>0.9995) within the test ranges. The relative standard deviation (RSD) of the method was less than 3.0% for intra- and inter-day assays. The samples were stable for at least 96h, and the average recoveries were between 90.6% and 102.5%. High sensitivity was demonstrated with detection limits of 0.028-0.085μg/ml for flavonoids. The newly established HPLC method represents a powerful technique for the quality assurance of S. cannabifolius. Copyright © 2012 Elsevier B.V. All rights reserved.

Determination of phenol, m-, o- and p-cresol, p-aminophenol and p-nitrophenol in urine by high-performance liquid chromatography.

PubMed

Brega, A; Prandini, P; Amaglio, C; Pafumi, E

1990-12-28

A method for the biological monitoring of human exposure to aromatic hydrocarbons, nitrocompounds, amines and phenols has been developed. Phenol, cresols, p-aminophenol, p-nitrophenol and their glucorono- or sulpho-conjugates, were quantified by HPLC; 4-chlorphenol was added as internal standard. After enzymatic hydrolysis, the free compounds were extracted with an organic solvent and analyzed by an isocratic HPLC Perkin Elmer system at ambient temperature and at a flow-rate of 1 ml/min. The column was a reversed-phase Pecosphere 3 x 3 C18 Perkin Elmer; the mobile phase was a 30:70:0.1 (v/v/v) methanol-water-orthophosphoric acid mixture and the chromatogram was monitored at 215 nm. Identification was based on retention time and quantification was performed by automatic peak height determination, corrected for the internal standard. The recovery was ca. 95% for phenol and cresols; 90% for p-nitrophenol; 85% for p-aminophenol; the coefficients of variance were less than 6% within analysis (n = 20) and less than 10% between analysis (n = 20). The detection limits, at a signal/noise ratio of 2, were 0.5 mg/l for phenol and cresols and 1 mg/l for p-aminophenol and p-nitrophenol.

Quality by design approach for the separation of naproxcinod and its related substances by fused core particle technology column.

PubMed

Inugala, Ugandar Reddy; Pothuraju, Nageswara Rao; Vangala, Ranga Reddy

2013-01-01

This paper describes the development of a rapid, novel, stability-indicating gradient reversed-phase high-performance liquid chromatographic method and associated system suitability parameters for the analysis of naproxcinod in the presence of its related substances and degradents using a quality-by-design approach. All of the factors that affect the separation of naproxcinod and its impurities and their mutual interactions were investigated and robustness of the method was ensured. The method was developed using an Ascentis Express C8 150 × 4.6 mm, 2.7 µm column with a mobile phase containing a gradient mixture of two solvents. The eluted compounds were monitored at 230 nm, the run time was 20 min within which naproxcinod and its eight impurities were satisfactorily separated. Naproxcinod was subjected to the stress conditions of oxidative, acid, base, hydrolytic, thermal and photolytic degradation. Naproxcinod was found to degrade significantly in acidic and basic conditions and to be stable in thermal, photolytic, oxidative and aqueous degradation conditions. The degradation products were satisfactorily resolved from the primary peak and its impurities, proving the stability-indicating power of the method. The developed method was validated as per International Conference on Harmonization guidelines with respect to specificity, linearity, limit of detection, limit of quantification, accuracy, precision and robustness.

Stability-indicating UPLC method for determination of Valsartan and their degradation products in active pharmaceutical ingredient and pharmaceutical dosage forms.

PubMed

Krishnaiah, Ch; Reddy, A Raghupathi; Kumar, Ramesh; Mukkanti, K

2010-11-02

A simple, precise, accurate stability-indicating gradient reverse phase ultra-performance liquid chromatographic (RP-UPLC) method was developed for the quantitative determination of purity of Valsartan drug substance and drug products in bulk samples and pharmaceutical dosage forms in the presence of its impurities and degradation products. The method was developed using Waters Aquity BEH C18 (100 mm x 2.1 mm, 1.7 microm) column with mobile phase containing a gradient mixture of solvents A and B. The eluted compounds were monitored at 225 nm, the run time was within 9.5 min, which Valsartan and its seven impurities were well separated. Valsartan was subjected to the stress conditions of oxidative, acid, base, hydrolytic, thermal and photolytic degradation. Valsartan was found to degrade significantly in acid and oxidative stress conditions and stable in base, hydrolytic and photolytic degradation conditions. The degradation products were well resolved from main peak and its impurities, proving the stability-indicating power of the method. The developed method was validated as per international conference on harmonization (ICH) guidelines with respect to specificity, linearity, limit of detection, limit of quantification, accuracy, precision and robustness. This method was also suitable for the assay determination of Valsartan in pharmaceutical dosage forms.

Multivariate optimization and validation of an analytical methodology by RP-HPLC for the determination of losartan potassium in capsules.

PubMed

Bonfilio, Rudy; Tarley, César Ricardo Teixeira; Pereira, Gislaine Ribeiro; Salgado, Hérida Regina Nunes; de Araújo, Magali Benjamim

2009-11-15

This paper describes the optimization and validation of an analytical methodology for the determination of losartan potassium in capsules by HPLC using 2(5-1) fractional factorial and Doehlert designs. This multivariate approach allows a considerable improvement in chromatographic performance using fewer experiments, without additional cost for columns or other equipment. The HPLC method utilized potassium phosphate buffer (pH 6.2; 58 mmol L(-1))-acetonitrile (65:35, v/v) as the mobile phase, pumped at a flow rate of 1.0 mL min(-1). An octylsilane column (100 mm x 4.6mm i.d., 5 microm) maintained at 35 degrees C was used as the stationary phase. UV detection was performed at 254 nm. The method was validated according to the ICH guidelines, showing accuracy, precision (intra-day relative standard deviation (R.S.D.) and inter-day R.S.D values <2.0%), selectivity, robustness and linearity (r=0.9998) over a concentration range from 30 to 70 mg L(-1) of losartan potassium. The limits of detection and quantification were 0.114 and 0.420 mg L(-1), respectively. The validated method may be used to quantify losartan potassium in capsules and to determine the stability of this drug.

HPLC/Fluorometric Detection of Carvedilol in Real Human Plasma Samples Using Liquid-Liquid Extraction.

PubMed

Yilmaz, Bilal; Arslan, Sakir

2016-03-01

A simple, rapid and sensitive high-performance liquid chromatography (HPLC) method has been developed to quantify carvedilol in human plasma using an isocratic system with fluorescence detection. The method included a single-step liquid-liquid extraction with diethylether and ethylacetate mixture (3 : 1, v/v). HPLC separation was carried out by reversed-phase chromatography with a mobile phase composed of 20 mM phosphate buffer (pH 7)-acetonitrile (65 : 35, v/v), pumped at a flow rate of 1.0 mL/min. Fluorescence detection was performed at 240 nm (excitation) and 330 nm (emission). The calibration curve for carvedilol was linear from 10 to 250 ng/mL. Intra- and interday precision values for carvedilol in human plasma were <4.93%, and accuracy (relative error) was better than 4.71%. The analytical recovery of carvedilol from human plasma averaged out to 91.8%. The limits of detection and quantification of carvedilol were 3.0 and 10 ng/mL, respectively. Also, the method was successfully applied to three patients with hypertension who had been given an oral tablet of 25 mg carvedilol. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

A Liquid Chromatography – Tandem Mass Spectrometry Approach for the Identification of Mebendazole Residue in Pork, Chicken, and Horse

PubMed Central

Lee, Ji Sun; Cho, Soo Hee; Lim, Chae Mi; Chang, Moon Ik; Joo, Hyun Jin; Park, Hyun Jin

2017-01-01

A confirmatory and quantitative method of liquid chromatography-tandem mass spectrometry (LC-MS/MS) for the determination of mebendazole and its hydrolyzed and reduced metabolites in pork, chicken, and horse muscles was developed and validated in this study. Anthelmintic compounds were extracted with ethyl acetate after sample mixture was made alkaline followed by liquid chromatographic separation using a reversed phase C18 column. Gradient elution was performed with a mobile phase consisting of water containing 10 mM ammonium formate and methanol. This confirmatory method was validated according to EU requirements. Evaluated validation parameters included specificity, accuracy, precision (repeatability and within-laboratory reproducibility), analytical limits (decision limit and detection limit), and applicability. Most parameters were proved to be conforming to the EU requirements. The decision limit (CCα) and detection capability (CCβ) for all analytes ranged from 15.84 to 17.96 μgkg-1. The limit of detection (LOD) and the limit of quantification (LOQ) for all analytes were 0.07 μgkg-1 and 0.2 μgkg-1, respectively. The developed method was successfully applied to monitoring samples collected from the markets in major cities and proven great potential to be used as a regulatory tool to determine mebendazole residues in animal based foods. PMID:28085912

Simple and Rapid Determination of Ferulic Acid Levels in Food and Cosmetic Samples Using Paper-Based Platforms

PubMed Central

Tee-ngam, Prinjaporn; Nunant, Namthip; Rattanarat, Poomrat; Siangproh, Weena; Chailapakul, Orawon

2013-01-01

Ferulic acid is an important phenolic antioxidant found in or added to diet supplements, beverages, and cosmetic creams. Two designs of paper-based platforms for the fast, simple and inexpensive evaluation of ferulic acid contents in food and pharmaceutical cosmetics were evaluated. The first, a paper-based electrochemical device, was developed for ferulic acid detection in uncomplicated matrix samples and was created by the photolithographic method. The second, a paper-based colorimetric device was preceded by thin layer chromatography (TLC) for the separation and detection of ferulic acid in complex samples using a silica plate stationary phase and an 85:15:1 (v/v/v) chloroform: methanol: formic acid mobile phase. After separation, ferulic acid containing section of the TLC plate was attached onto the patterned paper containing the colorimetric reagent and eluted with ethanol. The resulting color change was photographed and quantitatively converted to intensity. Under the optimal conditions, the limit of detection of ferulic acid was found to be 1 ppm and 7 ppm (S/N = 3) for first and second designs, respectively, with good agreement with the standard HPLC-UV detection method. Therefore, these methods can be used for the simple, rapid, inexpensive and sensitive quantification of ferulic acid in a variety of samples. PMID:24077320

[Determination of formaldehyde and acetaldehyde in packaging paper by dansylhydrazine derivatization-high performance liquid chromatography-fluorescence detection].

PubMed

Gong, Shuguo; Liang, Yong; Tang, Liyun; Huang, Ping; Dai, Yunhui

2017-07-08

A high performance liquid chromatography with fluorescence detection (HPLC-FLD) method was developed for the simultaneous determination of formaldehyde and acetaldehyde in packaging paper by dansylhydrazine (DNSH) derivatization. The samples were extracted by derivatization reagent for 30 min, and derived for 24 h. After purifying treatment with a PSA/C18 cartridge, a Diamonsil ® C18 column (150 mm×4.6 mm, 5 μ m) was used as stationary phase for separation, the mixtures of acetic acid aqueous solution (pH 2.55)-acetonitrile were used as mobile phases by gradient elution, and the excitation and emission wavelengths were 330 nm and 484 nm, respectively. The results showed that the recoveries of formaldehyde and acetaldehyde spiked in the samples were 81.64%-106.78%, and the relative standard deviations (RSDs) were 2.02%-5.53% ( n =5). The limits of detection of formaldehyde and acetaldehyde were 19.2 μ g/kg and 20.7 μ g/kg, respectively. The limits of quantification of formaldehyde and acetaldehyde were 63.9 μ g/kg and 69.1 μ g/kg, respectively. The method is simple, sensitive and reproducible. It provides a basic approach for the determination of trace formaldehyde and acetaldehyde.

A sensitive and rapid determination of ranitidine in human plasma by HPLC with fluorescence detection and its application for a pharmacokinetic study.

PubMed

Ulu, Sevgi Tatar; Tuncel, Muzaffer

2012-04-01

A novel precolumn derivatization reversed-phase high-performance liquid chromatography method with fluorescence detection is described for the determination of ranitidine in human plasma. The method was based on the reaction of ranitidine with 4-fluoro-7-nitrobenzo-2-oxa-1,3-diazole forming yellow colored fluorescent product. The separation was achieved on a C(18) column using methanol-water (60:40, v/v) mobile phase. Fluorescence detection was used at the excitation and emission of 458 and 521 nm, respectively. Lisinopril was utilized as an internal standard. The flow rate was 1.2 mL/min. Ranitidine and lisinopril appeared at 3.24 and 2.25 min, respectively. The method was validated for system suitability, precision, accuracy, linearity, limit of detection, limit of quantification, recovery and robustness. Intra- and inter-day precisions of the assays were in the range of 0.01-0.44%. The assay was linear over the concentration range of 50-2000 ng/mL. The mean recovery was determined to be 96.40 ± 0.02%. This method was successfully applied to a pharmacokinetic study after oral administration of a dose (150 mg) of ranitidine. © The Author [2012]. Published by Oxford University Press. All rights reserved.

Flow Reactor for studying Physicochemical and aging properties of SOA

NASA Astrophysics Data System (ADS)

Babar, Z. B.

2016-12-01

Secondary organic aerosols (SOA) have importance in environmental processes such as affecting earth's radiative balance and cloud formation processes. For studying SOA formation large scale environmental batch reactors and laboratory scale flow reactors have been used. In this study application of flow reactor to study physicochemical properties of SOA is also investigated after its characterization. The flow reactor is of cylindrical design (ID 15 cm x L 70 cm) equipped with UV lamps. It is coupled with various instruments such as scanning mobility particle sizer, NOx analyzer, ozone analyzer, VOC analyzer, hygrometer, and temperature sensors for gas and particle phase measurements. OH radicals were generated by custom build ozone generator and relative humidity. The following characterizations were performed: (1) residence time distribution (RTD) measurements, (2) RH and temperature control, (3) OH radical exposure range (atmospheric aging time), (4) gas phase oxidation of SOA precursors such as α-pinene by OH radical. The flow reactor yielded narrow RTDs. In particular, RH and temperature can be controlled effectively between 0-60% and 22-43oC, respectively. OH radical exposure ranges from 6.49x1010 to 3.68x1011 molecules/cm3s (0.49 to 4.91 days). Our initial efforts on OH radical generation using hydrogen peroxide and its quantification by using flourescenet technique will be also be presented.

Simultaneous quantification of 5 main components of Psoralea corylifolia L. in rats' plasma by utilizing ultra high pressure liquid chromatography tandem mass spectrometry.

PubMed

Gao, Qianqian; Xu, Zisheng; Zhao, Genhua; Wang, Heng; Weng, Zebin; Pei, Ke; Wu, Li; Cai, Baochang; Chen, Zhipeng; Li, Weidong

2016-02-01

Psoralea corylifolia L. has long been used in traditional Chinese medicine for treating and preventing many diseases. A group of flavonoid components are regarded as the active principals within the seeds. In this research, a rapid, accurate and sensitive ultra high pressure liquid chromatography tandem mass spectrometry (UHPLC/MS/MS) method has been established for simultaneous quantification of its 5 main components, namely, neobavaisoflavone, bavachin, isobavachalcone, bavachinin and corylifol A in rats' plasma after the rats were orally administrated with Buguzhi extract. Negative ion electrospray mode was applied in the detection process. Multiple reactions monitoring (MRM) mode was utilized for simultaneous quantitative analyzing of neobavaisoflavone (m/z 321.1→m/z 265.1), bavachin (m/z 323.1→m/z 119.0), isobavachalcone (m/z 323.2→m/z 119.0), bavachinin (m/z 337.2→m/z 119.0), corylifol A (m/z 389.2→m/z 277.0) and liquiritigenin (Internal Standard, m/z 255.1→m/z 119.0). Chromatographic separation of the above mentioned components was conducted on a Waters BEH-C18 column (100 mm×2.1mm, 1.7μm) with gradient elution system at flow rate of 0.3mL/min. The mobile phase was composed of acetonitrile and 0.1% formic acid solution. The lower limit of quantification (LLOQ) for each of the above analytes was 0.5ng/mL. Each of the analytes exhibited good linearity within the concentration range of 0.5-100ng/mL. The method was fully validated for its selectivity, accuracy, precision, stability, matrix effect and extraction recovery. The validated method has been successfully applied for simultaneous determination of the 5 flavonoids in rat plasma for the first time. Copyright © 2016 Elsevier B.V. All rights reserved.

High Performance Thin layer Chromatography: Densitometry Method for Determination of Rubraxanthone in the Stem Bark Extract of Garcinia cowa Roxb.

PubMed

Hamidi, Dachriyanus; Aulia, Hilyatul; Susanti, Meri

2017-01-01

Garcinia cowa is a medicinal plant widely grown in Southeast Asia and tropical countries. Various parts of this plant have been used in traditional folk medicine. The bark, latex, and root have been used as an antipyretic agent, while fruit and leaves have been used as an expectorant, for indigestion and improvement of blood circulation. This study aims to determine the concentration of rubraxanthone found in ethyl acetate extract of the stem bark of G. cowa by the high-performance thin-layer chromatography (HPTLC). HPTLC method was performed on precoated silica gel G 60 F254 plates using an HPTLC system with a developed mobile-phase system of chloroform: ethyl acetate: methanol: formic acid (86:6:3:5). A volume of 5 μL of standard and sample solutions was applied to the chromatographic plates. The plates were developed in saturated mode of twin trough chamber at room temperature. The method was validated based on linearity, accuracy, precision, limit of detection (LOD), limit of quantification (LOQ), and specificity. The spots were observed at ultraviolet 243 nm. The linearity of rubraxanthone was obtained between 52.5 and 157.5 ppm/spot. The LOD and LOQ were found to be 4.03 and 13.42 ppm/spot, respectively. The proposed method showed good linearity, precision, accuracy, and high sensitivity. Therefore, it may be applied for the quantification of rubraxanthone in ethyl acetate extract of the stem bark of G. cowa . High performance thin layer chromatography (HPTLC) method provides rapid qualitative and quantitative estimation of rubraxanthone as a marker com¬pound in G. cowa extract used for commercial productRubraxanthone found in ethyl acetate extracts of G. cowa was successfully quantified using HPTLC method. Abbreviations Used : TLC: Thin-layer chromatography, HPTLC: High-performance thin-layer chromatography, LOD: Limit of detection, LOQ: Limit of quantification, ICH: International Conference on Harmonization.

Simultaneous identification and quantification of tetrodotoxin in fresh pufferfish and pufferfish-based products using immunoaffinity columns and liquid chromatography/quadrupole-linear ion trap mass spectrometry

NASA Astrophysics Data System (ADS)

Guo, Mengmeng; Wu, Haiyan; Jiang, Tao; Tan, Zhijun; Zhao, Chunxia; Zheng, Guanchao; Li, Zhaoxin; Zhai, Yuxiu

2017-07-01

In this study, we established a comprehensive method for simultaneous identification and quantification of tetrodotoxin (TTX) in fresh pufferfish tissues and pufferfish-based products using liquid chromatography/quadrupole-linear ion trap mass spectrometry (LC-QqLIT-MS). TTX was extracted by 1% acetic acid-methanol, and most of the lipids were then removed by freezing lipid precipitation, followed by purification and concentration using immunoaffinity columns (IACs). Matrix effects were substantially reduced due to the high specificity of the IACs, and thus, background interference was avoided. Quantitation analysis was therefore performed using an external calibration curve with standards prepared in mobile phase. The method was evaluated by fortifying samples at 1, 10, and 100 ng/g, respectively, and the recoveries ranged from 75.8%-107%, with a relative standard deviation of less than 15%. The TTX calibration curves were linear over the range of 1-1 000 μg/L, with a detection limit of 0.3 ng/g and a quantification limit of 1 ng/g. Using this method, samples can be further analyzed using an information-dependent acquisition (IDA) experiment, in the positive mode, from a single liquid chromatography-tandem mass spectrometry injection, which can provide an extra level of confirmation by matching the full product ion spectra acquired for a standard sample with those from an enhanced product ion (EPI) library. The scheduled multiple reaction monitoring method enabled TTX to be screened for, and TTX was positively identified using the IDA and EPI spectra. This method was successfully applied to analyze a total of 206 samples of fresh pufferfish tissues and pufferfish-based products. The results from this study show that the proposed method can be used to quantify and identify TTX in a single run with excellent sensitivity and reproducibility, and is suitable for the analysis of complex matrix pufferfish samples.

Rapid planar chromatographic analysis of 25 water-soluble dyes used as food additives.

PubMed

Morlock, Gertrud E; Oellig, Claudia

2009-01-01

A rapid planar chromatographic method for identification and quantification of 25 water-soluble dyes in food was developed. In a horizontal developing chamber, the chromatographic separation on silica gel 60F254 high-performance thin-layer chromatography plates took 12 min for 40 runs in parallel, using 8 mL ethyl acetate-methanol-water-acetic acid (65 + 23 + 11 + 1, v/v/v/v) mobile phase up to a migration distance of 50 mm. However, the total analysis time, inclusive of application and evaluation, took 60 min for 40 runs. Thus, the overall time/run can be calculated as 1.5 min with a solvent consumption of 200 microL. A sample throughput of 1000 runs/8 h day can be reached by switching between the working stations (application, development, and evaluation) in a 20 min interval, which triples the analysis throughput. Densitometry was performed by absorption measurement using the multiwavelength scan mode in the UV and visible ranges. Repeatabilities [relative standard deviation (RSD), 4 determinations] at the first or second calibration level showed precisions of mostly < or = 2.7%, ranging between 0.2 and 5.2%. Correlation coefficient values (R > or = 0.9987) and RSD values (< or = 4.2%) of the calibration curves were highly satisfactory using classical quantification. However, digital evaluation of the plate image was also used for quantification, which resulted in RSD values of the calibration curves of mostly < or = 3.0%, except for two < or = 6.0%. The method was applied for the analysis of some energy drinks and bakery ink formulations, directly applied after dilution. By recording of absorbance spectra in the visible range, the identities of the dyes found in the samples were ascertained by comparison with the respective standard bands (correlation coefficients > or = 0.9996). If necessary for confirmation, online mass spectra were recorded within a minute.

New validated LC-MS/MS method for the determination of three alkylated adenines in human urine and its application to the monitoring of alkylating agents in cigarette smoke.

PubMed

Tian, Yongfeng; Hou, Hongwei; Zhang, Xiaotao; Wang, An; Liu, Yong; Hu, Qingyuan

2014-09-01

A highly specific liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for simultaneous determination of urinary N(3)-methyladenine (N(3)-MeA), N(3)-ethyladenine (N(3)-EtA), and N(3)-(2-hydroxyethyl)adenine (N(3)-HOEtA). Chromatographic separation was achieved on a hydrophilic interaction liquid chromatography column, with a mobile phase gradient prepared from aqueous 10 mM ammonium formate-acetonitrile (5:95 v/v, pH 4.0). Quantification of the analytes was done by multiple reaction monitoring using a triple-quadrupole mass spectrometer in positive-ionization mode. The limits of quantification were 0.13, 0.02, and 0.03 ng/mL for N(3)-MeA, N(3)-EtA, and N(3)-HOEtA, respectively. Intraday and interday variations (relative standard deviations) ranged from 0.6 to 1.3 % and from 3.7 to 7.5 %. The recovery ranges of N(3)-MeA, N(3)-EtA, and N(3)-HOEtA in urine were 80.1-97.3 %, 83.3-90.0 %, and 100.0-110.0 %, respectively. The proposed method was successfully applied to urine samples from 251 volunteers including 193 regular smokers and 58 nonsmokers. The results showed that the levels of urinary N(3)-MeA, N(3)-EtA, and N(3)-HOEtA in smokers were significantly higher than those in nonsmokers. Furthermore, the level of urinary N(3)-MeA in smokers was found to be positively correlated with the level of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (r = 0.48, P < 0.001, N = 192). This method is appropriate for routine analysis and accurate quantification of N(3)-MeA, N(3)-EtA, and N(3)-HOEtA. It is also a useful tool for the surveillance of alkylating agent exposure.

Development, Validation and Application of a Stability Indicating HPLC Method to Quantify Lidocaine from Polyethylene-co-Vinyl Acetate (EVA) Matrices and Biological Fluids.

PubMed

Bhusal, Prabhat; Sharma, Manisha; Harrison, Jeff; Procter, Georgina; Andrews, Gavin; Jones, David S; Hill, Andrew G; Svirskis, Darren

2017-09-01

An efficient and cost-effective quantification procedure for lidocaine by HPLC has been developed to estimate lidocaine from an EVA matrix, plasma, peritoneal fluid and intra-articular fluid (IAF). This method guarantees the resolution of lidocaine from the degradation products obtained from alkaline and oxidative stress. Chromatographic separation of lidocaine was achieved with a retention time of 7 min using a C18 column with a mobile phase comprising acetonitrile and potassium dihydrogen phosphate buffer (pH 5.5; 0.02 M) in the ratio of 26:74 at a flow rate of 1 mL min-1 with detection at 230 nm. Instability of lidocaine was observed to an oxidizing (0.02% H2O2) and alkaline environments (0.1 M NaOH). The calibration curve was found to be linear within the concentration range of 0.40-50.0 μg/mL. Intra-day and inter-day accuracy ranged between 95.9% and 99.1%, with precision (% RSD) below 6.70%. The limit of quantification and limit of detection were 0.40 μg/mL and 0.025 μg/mL, respectively. The simple extraction method described enabled the quantification of lidocaine from an EVA matrix using dichloromethane as a solvent. The assay and content uniformity of lidocaine within an EVA matrix were 103 ± 3.60% and 100 ± 2.60%, respectively. The ability of this method to quantify lidocaine release from EVA films was also demonstrated. Extraction of lidocaine from plasma, peritoneal fluid and IAF followed by HPLC analysis confirmed the utility of this method for ex vivo and in vivo studies where the calibration plot was found to be linear from 1.60 to 50.0 μg/mL. © Crown copyright 2017.

Satellite mobile data service for Canada

NASA Technical Reports Server (NTRS)

Egan, Glenn R.; Sward, David J.

1990-01-01

A commercial mobile satellite system which is to be constructed and operated in Canada is examined. This is done in two phases. First, mobile data services was introduced. Hub equipment and 3000 mobile data terminals were supplied. Over the satellite tests were performed. The mobile data service provides full two way digital messaging automatic vehicle location and fleet management services. The second phase is to construct, launch and make operational the MSAT satellite and associated network control facilities. The implementation is examined of the mobile data service in Canada, including the technical description. Marketing and applications are also examined.

A microfluidic investigation of gas exsolution in glass and shale fracture networks

NASA Astrophysics Data System (ADS)

Porter, M. L.; Jimenez-Martinez, J.; Harrison, A.; Currier, R.; Viswanathan, H. S.

2016-12-01

Microfluidic investigations of pore-scale fluid flow and transport phenomena has steadily increased in recent years. In these investigations fluid flow is restricted to two-dimensions allowing for real-time visualization and quantification of complex flow and reactive transport behavior, which is difficult to obtain in other experimental systems. In this work, we describe a unique high pressure (up to 10.3 MPa) and temperature (up to 80 °C) microfluidics experimental system that allows us to investigate fluid flow and transport in geo-material (e.g., shale, Portland cement, etc.) micromodels. The use of geo-material micromodels allows us to better represent fluid-rock interactions including wettability, chemical reactivity, and nano-scale porosity at conditions representative of natural subsurface environments. Here, we present experimental results in fracture systems with applications to hydrocarbon mobility in fractured rocks. Complex fracture network patterns are derived from 3D x-ray tomography images of actual fractures created in shale rock cores. We use both shale and glass micromodels, allowing for a detailed comparison between flow phenomena in the different materials. We discuss results from two-phase gas (CO2 and N2) injection experiments designed to enhance oil recovery. In these experiments gas was injected into micromodels saturated with oil and allowed to soak for approximately 12 hours at elevated pressures. The pressure in the system was then decreased to atmospheric, causing the gas to expand and/or dissolve out of solution, subsequently mobilizing the oil. In addition to the experimental results, we present a relatively simple model designed to quantify the amount of oil mobilized as a function of decreasing system pressure. We will show comparisons between the experiments and model, and discuss the potential use of the model in field-scale reservoir simulations.

Retention of ionisable compounds on high-performance liquid chromatography XVII. Estimation of the pH variation of aqueous buffers with the change of the methanol fraction of the mobile phase.

PubMed

Subirats, Xavier; Bosch, Elisabeth; Rosés, Martí

2007-01-05

The use of methanol-aqueous buffer mobile phases in HPLC is a common election when performing chromatographic separations of ionisable analytes. The addition of methanol to the aqueous buffer to prepare such a mobile phase changes the buffer capacity and the pH of the solution. In the present work, the variation of these buffer properties is studied for acetic acid-acetate, phosphoric acid-dihydrogenphosphate-hydrogenphosphate, citric acid-dihydrogencitrate-hydrogencitrate-citrate, and ammonium-ammonia buffers. It is well established that the pH change of the buffers depends on the initial concentration and aqueous pH of the buffer, on the percentage of methanol added, and on the particular buffer used. The proposed equations allow the pH estimation of methanol-water buffered mobile phases up to 80% in volume of organic modifier from initial aqueous buffer pH and buffer concentration (before adding methanol) between 0.001 and 0.01 mol L(-1). From both the estimated pH values of the mobile phase and the estimated pKa of the ionisable analytes, it is possible to predict the degree of ionisation of the analytes and therefore, the interpretation of acid-base analytes behaviour in a particular methanol-water buffered mobile phase.

A weak cation-exchange monolith as stationary phase for the separation of peptide diastereomers by CEC.

PubMed

Ludewig, Ronny; Nietzsche, Sandor; Scriba, Gerhard K E

2011-01-01

A CEC weak cation-exchange monolith has been prepared by in situ polymerization of acrylamide, methylenebisacrylamide and 4-acrylamidobutyric acid in a decanol-dimethylsulfoxide mixture as porogen. The columns were evaluated by SEM and characterized with regard to the separation of diastereomers and α/β-isomers of aspartyl peptides. Column preparation was reproducible as evidenced by comparison of the analyte retention times of several columns prepared simultaneously. Analyte separation was achieved using mobile phases consisting of acidic phosphate buffer and ACN. Under these conditions the peptides migrated due to their electrophoretic mobility but the EOF also contributed as driving force as a function of the pH of the mobile phase due to increasing dissociation of the carboxyl groups of the polymer. Raising the pH of the mobile phase also resulted in deprotonation of the peptides reducing analyte mobility. Due to these mechanisms each pair of diastereomeric peptides displayed the highest resolution at a different pH of the buffer component of the mobile phase. Comparing the weak-cation exchange monolith to an RP monolith and a strong cation-exchange monolith different elution order of some peptide diastereomers was observed, clearly illustrating that interactions with the stationary phase contribute to the CEC separations. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Slow equilibration of reversed-phase columns for the separation of ionized solutes.

PubMed

Marchand, D H; Williams, L A; Dolan, J W; Snyder, L R

2003-10-10

Reversed-phase columns that have been stored in buffer-free solvents can exhibit pronounced retention-time drift when buffered, low-pH mobile phases are used with ionized solutes. Whereas non-ionized compounds exhibit constant retention times within 20 min of the beginning of mobile phase flow, the retention of ionized compounds can continue to change (by 20% or more) for several hours. If mobile phase pH is changed from low to high and back again, an even longer time may be required before the column reaches equilibration at low pH. The speed of column equilibration for ionized solutes can vary significantly among different reversed-phase columns and is not affected by flow rate.

Combined effect of polarity and pH on the chromatographic behavior of some angiotensin II receptor antagonists and optimization of their determination in pharmaceutical dosage forms.

PubMed

Demiralay, Ebru Cubuk; Cubuk, Burcu; Ozkan, Sibel A; Alsancak, Guleren

2010-11-02

In the present study, the combined effect of mobile phase polarity and pH on retention behavior of some ARA-IIs (irbesartan, losartan, valsartan and telmisartan) is investigated. The linear relationships established between retention factors of the species and the polarity parameter of the mobile phase has proved to predict accurately retention in LC as a function of the acetonitrile content (50%, 55%, 60%, v/v). The suggested model uses the pH value in the acetonitrile-water mixture as mobile phase instead of pH value in water and takes into account the effect of activity coefficients. Moreover, correlation between retention and the mobile phase pH can be established allowing prediction of the retention behavior as a function of the mobile phase pH. The model can be used to estimate the pKa in an acetonitrile percentage between 50% and 60%, at 30 degrees C. The developed method was successfully applied to both the simultaneous separation of these drug-active compounds and individual determination in their commercial pharmaceutical dosage forms.

Quantitative proton magnetic resonance spectroscopy without water suppression

NASA Astrophysics Data System (ADS)

Özdemir, M. S.; DeDeene, Y.; Fieremans, E.; Lemahieu, I.

2009-06-01

The suppression of the abundant water signal has been traditionally employed to decrease the dynamic range of the NMR signal in proton MRS (1H MRS) in vivo. When using this approach, if the intent is to utilize the water signal as an internal reference for the absolute quantification of metabolites, additional measurements are required for the acquisition of the water signal. This can be prohibitively time-consuming and is not desired clinically. Additionally, traditional water suppression can lead to metabolite alterations. This can be overcome by performing quantitative 1H MRS without water suppression. However, the non-water-suppressed spectra suffer from gradient-induced frequency modulations, resulting in sidebands in the spectrum. Sidebands may overlap with the metabolites, which renders the spectral analysis and quantification problematic. In this paper, we performed absolute quantification of metabolites without water suppression. Sidebands were removed by utilizing the phase of an external reference signal of single resonance to observe the time-varying the static field fluctuations induced by gradient-vibration and deconvolving this phase contamination from the desired NMR signal. The quantification of metabolites was determined after sideband correction by calibrating the metabolite signal intensities against the recorded water signal. The method was evaluated by phantom and in vivo measurements in human brain. The maximum systematic error for the quantified metabolite concentrations was found to be 10.8%, showing the feasibility of the quantification after sideband correction.

Understanding the spreading patterns of mobile phone viruses.

PubMed

Wang, Pu; González, Marta C; Hidalgo, César A; Barabási, Albert-László

2009-05-22

We modeled the mobility of mobile phone users in order to study the fundamental spreading patterns that characterize a mobile virus outbreak. We find that although Bluetooth viruses can reach all susceptible handsets with time, they spread slowly because of human mobility, offering ample opportunities to deploy antiviral software. In contrast, viruses using multimedia messaging services could infect all users in hours, but currently a phase transition on the underlying call graph limits them to only a small fraction of the susceptible users. These results explain the lack of a major mobile virus breakout so far and predict that once a mobile operating system's market share reaches the phase transition point, viruses will pose a serious threat to mobile communications.

Atlanta Rail Yard Study (ARYS): Evaluation of local-scale air pollution trends and emissions quantification using stationary and mobile monitoring strategies

EPA Science Inventory

Intermodal rail yards are important nodes in the freight transportation network, where freight is organized and moved from one mode of transport to another, critical equipment is serviced, and freight is routed to its next destination. Rail yard environments are also areas with ...

Method for determining asphaltene stability of a hydrocarbon-containing material

DOEpatents

Schabron, John F; Rovani, Jr., Joseph F

2013-02-05

A method for determining asphaltene stability in a hydrocarbon-containing material having solvated asphaltenes therein is disclosed. In at least one embodiment, it involves the steps of: (a) precipitating an amount of the asphaltenes from a liquid sample of the hydrocarbon-containing material with an alkane mobile phase solvent in a column; (b) dissolving a first amount and a second amount of the precipitated asphaltenes by changing the alkane mobile phase solvent to a final mobile phase solvent having a solubility parameter that is higher than the alkane mobile phase solvent; (c) monitoring the concentration of eluted fractions from the column; (d) creating a solubility profile of the dissolved asphaltenes in the hydrocarbon-containing material; and (e) determining one or more asphaltene stability parameters of the hydrocarbon-containing material.

Single DNA imaging and length quantification through a mobile phone microscope

NASA Astrophysics Data System (ADS)

Wei, Qingshan; Luo, Wei; Chiang, Samuel; Kappel, Tara; Mejia, Crystal; Tseng, Derek; Chan, Raymond Yan L.; Yan, Eddie; Qi, Hangfei; Shabbir, Faizan; Ozkan, Haydar; Feng, Steve; Ozcan, Aydogan

2016-03-01

The development of sensitive optical microscopy methods for the detection of single DNA molecules has become an active research area which cultivates various promising applications including point-of-care (POC) genetic testing and diagnostics. Direct visualization of individual DNA molecules usually relies on sophisticated optical microscopes that are mostly available in well-equipped laboratories. For POC DNA testing/detection, there is an increasing need for the development of new single DNA imaging and sensing methods that are field-portable, cost-effective, and accessible for diagnostic applications in resource-limited or field-settings. For this aim, we developed a mobile-phone integrated fluorescence microscopy platform that allows imaging and sizing of single DNA molecules that are stretched on a chip. This handheld device contains an opto-mechanical attachment integrated onto a smartphone camera module, which creates a high signal-to-noise ratio dark-field imaging condition by using an oblique illumination/excitation configuration. Using this device, we demonstrated imaging of individual linearly stretched λ DNA molecules (48 kilobase-pair, kbp) over 2 mm2 field-of-view. We further developed a robust computational algorithm and a smartphone app that allowed the users to quickly quantify the length of each DNA fragment imaged using this mobile interface. The cellphone based device was tested by five different DNA samples (5, 10, 20, 40, and 48 kbp), and a sizing accuracy of <1 kbp was demonstrated for DNA strands longer than 10 kbp. This mobile DNA imaging and sizing platform can be very useful for various diagnostic applications including the detection of disease-specific genes and quantification of copy-number-variations at POC settings.

Simulating the mobility of meteoric 10Be in the landscape through a coupled soil-hillslope model (Be2D)

NASA Astrophysics Data System (ADS)

Campforts, Benjamin; Vanacker, Veerle; Vanderborght, Jan; Baken, Stijn; Smolders, Erik; Govers, Gerard

2016-04-01

Meteoric 10Be allows for the quantification of vertical and lateral soil fluxes over long time scales (103-105 yr). However, the mobility of meteoric 10Be in the soil system makes a translation of meteoric 10Be inventories into erosion and deposition rates complex. Here, we present a spatially explicit 2D model simulating the behaviour of meteoric 10Be on a hillslope. The model consists of two parts. The first component deals with advective and diffusive mobility of meteoric 10Be within the soil profile, and the second component describes lateral soil and meteoric 10Be fluxes over the hillslope. Soil depth is calculated dynamically, accounting for soil production through weathering as well as downslope fluxes of soil due to creep, water and tillage erosion. Synthetic model simulations show that meteoric 10Be inventories can be related to erosion and deposition across a wide range of geomorphological and pedological settings. Our results also show that meteoric 10Be can be used as a tracer to detect human impact on soil fluxes for soils with a high affinity for meteoric 10Be. However, the quantification of vertical mobility is essential for a correct interpretation of the observed variations in meteoric 10Be profiles and inventories. Application of the Be2D model to natural conditions using data sets from the Southern Piedmont (Bacon et al., 2012) and Appalachian Mountains (Jungers et al., 2009; West et al., 2013) allows to reliably constrain parameter values. Good agreement between simulated and observed meteoric 10Be concentrations and inventories is obtained with realistic parameter values. Furthermore, our results provide detailed insights into the processes redistributing meteoric 10Be at the soil-hillslope scale.

Bioanalytical methods for determination of tamoxifen and its phase I metabolites: a review.

PubMed

Teunissen, S F; Rosing, H; Schinkel, A H; Schellens, J H M; Beijnen, J H

2010-12-17

The selective estrogen receptor modulator tamoxifen is used in the treatment of early and advanced breast cancer and in selected cases for breast cancer prevention in high-risk subjects. The cytochrome P450 enzyme system and flavin-containing monooxygenase are responsible for the extensive metabolism of tamoxifen into several phase I metabolites that vary in toxicity and potencies towards estrogen receptor (ER) alpha and ER beta. An extensive overview of publications on the determination of tamoxifen and its phase I metabolites in biological samples is presented. In these publications techniques were used such as capillary electrophoresis, liquid, gas and thin layer chromatography coupled with various detection techniques (mass spectrometry, ultraviolet or fluorescence detection, liquid scintillation counting and nuclear magnetic resonance spectroscopy). A trend is seen towards the use of liquid chromatography coupled to mass spectrometry (LC-MS). State-of-the-art LC-MS equipment allowed for identification of unknown metabolites and quantification of known metabolites reaching lower limit of quantification levels in the sub pg mL(-1) range. Although tamoxifen is also metabolized into phase II metabolites, the number of publications reporting on phase II metabolism of tamoxifen is scarce. Therefore the focus of this review is on phase I metabolites of tamoxifen. We conclude that in the past decades tamoxifen metabolism has been studied extensively and numerous metabolites have been identified. Assays have been developed for both the identification and quantification of tamoxifen and its metabolites in an array of biological samples. This review can be used as a resource for method transfer and development of analytical methods used to support pharmacokinetic and pharmacodynamic studies of tamoxifen and its phase I metabolites. Copyright © 2010 Elsevier B.V. All rights reserved.

Simultaneous determination of bifonazole and tinctures of calendula flower in pharmaceutical creams by reversed-phase liquid chromatography.

PubMed

Ferreyra, Carola F; Ortiz, Cristina S

2005-01-01

The aim of this research was to develop and validate a sensitive, rapid, easy, and precise reversed-phase liquid chromatography (LC) method for stability studies of bifonazole (I) formulated with tinctures of calendula flower (II). The method was especially developed for the analysis and quantitative determination of I and II in pure and combined forms in cream pharmaceutical formulations without using gradient elution and at room temperature. The influence on the stability of compound I of temperature, artificial radiation, and drug II used for the new pharmaceutical design was evaluated. The LC separation was carried out using a Supelcosil LC-18 column (25 cm x 4.6 mm id, 5 microm particle size); the mobile phase was composed of methanol-0.1 M ammonium acetate buffer (85 + 15, v/v) pumped isocratically at a flow rate of 1 mL/min; and ultraviolet detection was at 254 nm. The analysis time was less than 10 min. Calibration graphs were found to be linear in the 0.125-0.375 mg/mL (rI = 0.9991) and 0.639-1.916 mg/mL (rII = 0.9995) ranges for I and II, respectively. The linearity, precision, recovery, and limits of detection and quantification were satisfactory for I and II. The results obtained suggested that the developed LC method is selective and specific for the analysis of I and II in pharmaceutical products, and that it can be applied to stability studies.

Analysis of metallic nanoparticles and their ionic counterparts in complex matrix by reversed-phase liquid chromatography coupled to ICP-MS.

PubMed

Yang, Yuan; Luo, Li; Li, Hai-Pu; Wang, Qiang; Yang, Zhao-Guang; Qu, Zhi-Peng; Ding, Ru

2018-05-15

Developing quantification and characterization methodology for metallic nanoparticles (MNPs) and their ionic component in complex matrix are crucial for the evaluation of their environmental behavior and health risks to humans. In this study, reversed phase high performance liquid chromatography combined ICP-MS was established for the characterization of MNPs in complex matrix. The ionic component could be separated from NPs with the optimized parameters of aqueous mobile phase. Good linear relationship between average diameter and retention time of NPs was obtained using HPLC-ICP-MS and the size smaller than 40 nm could be determined with this method, the detected results were in accordance with TEM results. The low detection limit of AuNPs and Au(Ⅲ) (both in sub-μg/L level) showed that this method was promising for the characterization of AuNPs and Au(Ⅲ) in environmental water. The mass concentration of ionic Au(Ⅲ) in environmental water could be detected using the proposed HPLC-ICP-MS and the concentration of AuNPs was obtained by subtracting the Au(Ⅲ) concentration from the total Au (The concentration of total Au was detected by ICP-MS after microwave digestion). Furthermore this proposed HPLC-ICP-MS method and single particle-ICPMS (SP-ICP-MS) was used for the analysis of the Ag speciation in commercial antibacterial products. Copyright © 2018 Elsevier B.V. All rights reserved.

Resolution and isolation of enantiomers of (±)-isoxsuprine using thin silica gel layers impregnated with L-glutamic acid, comparison of separation of its diastereomers prepared with chiral derivatizing reagents having L-amino acids as chiral auxiliaries.

PubMed

Bhushan, Ravi; Nagar, Hariom

2015-03-01

Thin silica gel layers impregnated with optically pure l-glutamic acid were used for direct resolution of enantiomers of (±)-isoxsuprine in their native form. Three chiral derivatizing reagents, based on DFDNB moiety, were synthesized having l-alanine, l-valine and S-benzyl-l-cysteine as chiral auxiliaries. These were used to prepare diastereomers under microwave irradiation and conventional heating. The diastereomers were separated by reversed-phase high-performance liquid chromatography on a C18 column with detection at 340 nm using gradient elution with mobile phase containing aqueous trifluoroacetic acid and acetonitrile in different compositions and by thin-layer chromatography (TLC) on reversed phase (RP) C18 plates. Diastereomers prepared with enantiomerically pure (+)-isoxsuprine were used as standards for the determination of the elution order of diastereomers of (±)-isoxsuprine. The elution order in the experimental study of RP-TLC and RP-HPLC supported the developed optimized structures of diastereomers based on density functional theory. The limit of detection was 0.1-0.09 µg/mL in TLC while it was in the range of 22-23 pg/mL in HPLC and 11-13 ng/mL in RP-TLC for each enantiomer. The conditions of derivatization and chromatographic separation were optimized. The method was validated for accuracy, precision, limit of detection and limit of quantification. Copyright © 2014 John Wiley & Sons, Ltd.

Investigation of folic acid stability in fortified instant noodles by use of capillary electrophoresis and reversed-phase high performance liquid chromatography.

PubMed

Hau Fung Cheung, Rodney; Morrison, Paul D; Small, Darryl M; Marriott, Philip J

2008-12-05

A single enzyme treatment with alpha-amylase, prior to the quantification of added folic acid (FA) in fortified instant fried Asian noodles with analysis performed by capillary zone electrophoresis (CZE) and reversed-phase high performance liquid chromatography (RP-HPLC) with UV detection, is described. The method was validated and optimized for capillary electrophoresis (CE) with separation achieved using a 8 mM phosphate-12 mM borate run buffer with 5% MeOH at pH 9.5. FA was well separated from matrix components with nicotinic acid (NA) employed as an internal standard. In a comparative study, separation of FA was performed using HPLC with a mobile phase consisting of 27% MeOH (v/v) in aqueous potassium phosphate buffer (3.5 mM KH(2)PO(4) and 3.2 mM K(2)HPO(4)), pH 8.5, and containing 5 mM tetrabutylammonium dihydrogen phosphate as an ion-pairing agent. For both methods, excellent results were obtained for various analytical parameters including linearity, accuracy and precision. The limit of detection was calculated to be 2.2 mg/L for CE without sample stacking and 0.10 mg/L with high performance liquid chromatography (HPLC). Sample extraction involved homogenization and enzymatic extraction with alpha-amylase. Results indicated that FA was stable during four main stages of instant fried noodle manufacturing (dough crumbs, cut sheets, steaming and frying).

Development and Validation of Eco-Friendly Liquid Chromatographic and Spectrophotometric Methods for Simultaneous Determination of Coformulated Drugs: Phenylephrine Hydrochloride and Prednisolone Acetate.

PubMed

Mostafa, Nadia M; Elsayed, Ghada M; Hassan, Nagiba Y; El Mously, Dina A

2017-11-01

Five simple, sensitive, and eco-friendly LC and UV spectrophotometric methods have been developed for the simultaneous determination of phenylephrine hydrochloride (PHE) and prednisolone acetate (PRD) in their combined dosage form. The first method was reversed-phase (RP) LC using methanol-water-heptane-1-sulfonic acid sodium salt (75 + 25 + 0.1, v/v/w) as a mobile phase. Separation was achieved using an XSelect HSS reversed-phase C18 analytical column (250 × 4.6 mm, 5µm). The flow rate was 1.0 mL/min and UV detection was done at 230 nm. Quantification was achieved over the concentration ranges of 5-50 µg/mL for PHE and 2-90 µg/mL for PRD. Four spectrophotometric methods were proposed, namely dual wavelength, first derivative of ratio spectra, ratio difference, and mean-centering of ratio spectra. Linearity was observed in the concentration ranges of 10-120 and 5-35 µg/mL for PHE and PRD, respectively, for the spectrophotometric methods. Green solvents were used in the proposed methods because they play a vital role in the analytical methods' influence on the environment. The suggested methods were validated regarding linearity, accuracy, and precision according to the International Conference on Harmonization guidelines, with satisfactory results. These methods could be used as harmless substitutes for routine analysis of the mentioned drugs, with no interference from excipients.

A simple assay for the simultaneous determination of human plasma albendazole and albendazole sulfoxide levels by high performance liquid chromatography in tandem mass spectrometry with solid-phase extraction.

PubMed

Wojnicz, Aneta; Cabaleiro-Ocampo, Teresa; Román-Martínez, Manuel; Ochoa-Mazarro, Dolores; Abad-Santos, Francisco; Ruiz-Nuño, Ana

2013-11-15

A simple, reproducible and fast (4 min chromatogram) method of liquid chromatography in tandem with mass spectrometry (LC/MS-MS) was developed to determine simultaneously the plasma levels of albendazole (ABZ) and its metabolite albendazole sulfoxide (ABZOX) for pharmacokinetic and clinical analysis. Each plasma sample was extracted by solid phase extraction (SPE) using phenacetin as internal standard (IS). The extracted sample was eluted with a Zorbax XDB-CN column using an isocratic method. The mobile phase consisting of water with 1% acetic acid (40%, A) and MeOH (60%, B), was used at a flow rate of 1 mL/min. ABZ and ABZOX were detected and identified by mass spectrometry with electrospray ionization (ESI) in the positive ion and multiple-reaction monitoring (MRM) mode. The method was linear in the range of 5-1000 ng/mL for ABZ and 10-1500 ng/mL (full validation) or 10-5000 ng/mL (partial validation) for ABZOX, with 5 and 10 ng/mL lower limit of quantification (LLOQ) for ABZ and ABZOX, respectively. The tests of accuracy and precision, matrix effect, extraction recovery and stability of the samples for both ABZ and ABZOX did not deviate more than 20% for the LLOQ and no more than 15% for other quality controls (QCs), according to regulatory agencies. © 2013.

Use of oleic-acid functionalized nanoparticles for the magnetic solid-phase microextraction of alkylphenols in fruit juices using liquid chromatography-tandem mass spectrometry.

PubMed

Viñas, Pilar; Pastor-Belda, Marta; Torres, Aitor; Campillo, Natalia; Hernández-Córdoba, Manuel

2016-05-01

Magnetic nanoparticles of cobalt ferrite with oleic acid as the surfactant (CoFe2O4/oleic acid) were used as sorbent material for the determination of alkylphenols in fruit juices. High sensitivity and specificity were achieved by liquid chromatography and detection using both diode-array (DAD) and electrospray-ion trap-tandem mass spectrometry (ESI-IT-MS/MS) in the selected reaction monitoring (SRM) mode of the negative fragment ions for alkylphenols (APs) and in positive mode for ethoxylate APs (APEOs). The optimized conditions for the different variables influencing the magnetic separation procedure were: mass of magnetic nanoparticles, 50mg, juice volume, 10mL diluted to 25mL with water, pH 6, stirring for 10min at room temperature, separation with an external neodymium magnet, desorption with 3mL of methanol and orbital shaking for 5min. The enriched organic phase was evaporated and reconstituted with 100µL acetonitrile before injecting 30µL into a liquid chromatograph with a mobile phase composed of acetonitrile/0.1% (v/v) formic acid under gradient elution. Quantification limits were in the range 3.6 to 125ngmL(-1). The recoveries obtained were in the 91-119% range, with RSDs lower than 14%. The ESI-MS/MS spectra permitted the correct identification of both APs and APEOs in the fruit juice samples. Copyright © 2016 Elsevier B.V. All rights reserved.

Determination of 15 N-nitrosodimethylamine precursors in different water matrices by automated on-line solid-phase extraction ultra-high-performance-liquid chromatography tandem mass spectrometry.

PubMed

Farré, Maria José; Insa, Sara; Mamo, Julian; Barceló, Damià

2016-08-05

A new methodology based on on-line solid-phase extraction (SPE) ultra-high-performance-liquid chromatography coupled to a triple quadrupole mass spectrometer (UHPLC-MS-MS) for the determination of 15 individual anthropogenic N-nitrosodimethylamine (NDMA) precursors was developed. On-line SPE was performed by passing 2mL of the water sample through a Hypersil GOLD aQ column and chromatographic separation was done using a Kinetex Biphenyl column using methanol and 0.1% formic acid aqueous solution as a mobile phase. For unequivocal identification and confirmation, two selected reaction monitoring (SRM) transitions were monitored per compound. Quantification was performed by internal standard approach and matrix match calibration. The main advantages of the developed method are high sensitivity (limits of detection in the sub ng/L range), selectivity due to the use of tandem mass spectrometry, precision and minimum sample manipulation as well as fast analytical response. Process efficiency and recovery were also evaluated for all the target compounds. As part of the validation procedure, the method was applied in a sampling campaign for the analysis of influent and secondary effluent of a wastewater treatment plant (WWTP) in Girona, Spain. Additionally, the effluent from a nanofiltration (NF) membrane system used for water recycling was monitored. The percentage of NDMA formation explained by the measured precursors was also quantified. Copyright © 2016 Elsevier B.V. All rights reserved.