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Sample records for accurate hplc method

  1. Simple, Precise and Accurate HPLC Method of Analysis for Nevirapine Suspension from Human Plasma

    PubMed Central

    Halde, S.; Mungantiwar, A.; Chintamaneni, M.

    2011-01-01

    A selective and sensitive high performance liquid chromatography with UV detector (HPLC-UV) method was developed and validated from human plasma. Nevirapine and internal standard (IS) zidovudine were extracted from human plasma by liquid-liquid extraction process using methyl tert-butyl ether. The samples were analysed using Inertsil ODS 3, 250×4.6 mm, 5 μ column using a mobile phase consists of 50 mM sodium acetate buffer solution (pH-4.00±0.05): acetonitrile (73:27 v/v). The method was validated over a concentration range of 50.00 ng/ml to 3998.96 ng/ml. The method was successfully applied to bioequivalence study of 10 ml single dose nevirapine oral suspension 50 mg/5 ml in healthy male volunteers. PMID:22707826

  2. A simple and accurate HPLC method for fecal bile acid profile in healthy and cirrhotic subjects: validation by GC-MS and LC-MS[S

    PubMed Central

    Kakiyama, Genta; Muto, Akina; Takei, Hajime; Nittono, Hiroshi; Murai, Tsuyoshi; Kurosawa, Takao; Hofmann, Alan F.; Pandak, William M.; Bajaj, Jasmohan S.

    2014-01-01

    We have developed a simple and accurate HPLC method for measurement of fecal bile acids using phenacyl derivatives of unconjugated bile acids, and applied it to the measurement of fecal bile acids in cirrhotic patients. The HPLC method has the following steps: 1) lyophilization of the stool sample; 2) reconstitution in buffer and enzymatic deconjugation using cholylglycine hydrolase/sulfatase; 3) incubation with 0.1 N NaOH in 50% isopropanol at 60°C to hydrolyze esterified bile acids; 4) extraction of bile acids from particulate material using 0.1 N NaOH; 5) isolation of deconjugated bile acids by solid phase extraction; 6) formation of phenacyl esters by derivatization using phenacyl bromide; and 7) HPLC separation measuring eluted peaks at 254 nm. The method was validated by showing that results obtained by HPLC agreed with those obtained by LC-MS/MS and GC-MS. We then applied the method to measuring total fecal bile acid (concentration) and bile acid profile in samples from 38 patients with cirrhosis (17 early, 21 advanced) and 10 healthy subjects. Bile acid concentrations were significantly lower in patients with advanced cirrhosis, suggesting impaired bile acid synthesis. PMID:24627129

  3. [Analysis of HPLC and NIRS fingerprints of Chrysanthemum indicum of different processing methods].

    PubMed

    Hu, Xiao-li; Bai, Yan; Lei, Jing-wei; Zhang, Di-wen; Hao, Min

    2015-10-01

    This paper studied the HPLC and NIRS fingerprints of Chrysanthemum with different processing methods, including directly drying, drying after steamed, and drying after fried. The method of discriminant analysis of TQ software was used to analysis the NIRS fingerprint of Chrysanthemum with three different processing methods, and the results were consistent with HPLC fingerprint similarity analysis. NIRS and HPLC fingerprints were of different characteristics, and the combination of the two methods can quickly and accurately identify Chrysanthemum with different processing methods. PMID:26975109

  4. Analysis of Biomass Sugars Using a Novel HPLC Method

    SciTech Connect

    Agblevor, F. A.; Hames, B. R.; Schell, D.; Chum, H. L.

    2007-01-01

    The precise quantitative analysis of biomass sugars is a very important step in the conversion of biomass feedstocks to fuels and chemicals. However, the most accurate method of biomass sugar analysis is based on the gas chromatography analysis of derivatized sugars either as alditol acetates or trimethylsilanes. The derivatization method is time consuming but the alternative high-performance liquid chromatography (HPLC) method cannot resolve most sugars found in biomass hydrolysates. We have demonstrated for the first time that by careful manipulation of the HPLC mobile phase, biomass monomeric sugars (arabinose, xylose, fructose, glucose, mannose, and galactose) can be analyzed quantitatively and there is excellent baseline resolution of all the sugars. This method was demonstrated for standard sugars, pretreated corn stover liquid and solid fractions. Our method can also be used to analyze dimeric sugars (cellobiose and sucrose).

  5. Methods and applications of HPLC-AMS

    NASA Astrophysics Data System (ADS)

    Buchholz, Bruce A.; Dueker, Stephen R.; Lin, Yumei; Clifford, Andrew J.; Vogel, John S.

    2000-10-01

    Pharmacokinetics of physiologic doses of nutrients, pesticides, and herbicides can easily be traced in humans using a 14C-labeled compound. Basic kinetics can be monitored in blood or urine by measuring the elevation in the 14C content above the control predose tissue and converting to equivalents of the parent compound. High performance liquid chromatography (HPLC) is an excellent method for the chemical separation of complex mixtures whose profiles afford estimation of biochemical pathways of metabolism. Compounds elute from the HPLC systems with characteristic retention times and can be collected in fractions that can then be graphitized for AMS measurement. Unknowns are tentatively identified by co-elution with known standards and chemical tests that reveal functional groupings. Metabolites are quantified with the 14C signal. Thoroughly accounting for the carbon inventory in the LC solvents, ion-pairing agents, samples, and carriers adds some complexity to the analysis. In most cases the total carbon inventory is dominated by carrier. Baseline background and stability need to be carefully monitored. Limits of quantitation near 10 amol of 14C per HPLC fraction are typically achieved. Baselines are maintained by limiting injected 14C activity <0.17 Bq (4.5 pCi) on the HPLC column.

  6. Correlation of Two Anthocyanin Quantification Methods: HPLC and Spectrophotometric Methods

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The pH differential method and HPLC are methods that are commonly used by researchers and the food industry for quantifying anthocyanins in a sample. This study was conducted to establish a relationship between the two analytical methods. Seven juice samples containing an array of different individu...

  7. A rapid sample preparation method for the HPLC determination of the opioid antagonist naltrexone in serum.

    PubMed

    Hurst, W J; Zagon, I S; Aboul-Enein, H Y

    1999-08-01

    HPLC with UV and electrochemical detection has routinely been employed for the determination of the opioid antagonist naltrexone in serum. Sample preparation protocols range from liquid/liquid to solid phase extraction. The sample preparation described in this communication uses ultrafiltration as the mode of sample preparation prior to HPLC analysis. The method is accurate, precise and saves considerable time compared to previously published techniques. PMID:10483613

  8. Accurate, meshless methods for magnetohydrodynamics

    NASA Astrophysics Data System (ADS)

    Hopkins, Philip F.; Raives, Matthias J.

    2016-01-01

    Recently, we explored new meshless finite-volume Lagrangian methods for hydrodynamics: the `meshless finite mass' (MFM) and `meshless finite volume' (MFV) methods; these capture advantages of both smoothed particle hydrodynamics (SPH) and adaptive mesh refinement (AMR) schemes. We extend these to include ideal magnetohydrodynamics (MHD). The MHD equations are second-order consistent and conservative. We augment these with a divergence-cleaning scheme, which maintains nabla \\cdot B≈ 0. We implement these in the code GIZMO, together with state-of-the-art SPH MHD. We consider a large test suite, and show that on all problems the new methods are competitive with AMR using constrained transport (CT) to ensure nabla \\cdot B=0. They correctly capture the growth/structure of the magnetorotational instability, MHD turbulence, and launching of magnetic jets, in some cases converging more rapidly than state-of-the-art AMR. Compared to SPH, the MFM/MFV methods exhibit convergence at fixed neighbour number, sharp shock-capturing, and dramatically reduced noise, divergence errors, and diffusion. Still, `modern' SPH can handle most test problems, at the cost of larger kernels and `by hand' adjustment of artificial diffusion. Compared to non-moving meshes, the new methods exhibit enhanced `grid noise' but reduced advection errors and diffusion, easily include self-gravity, and feature velocity-independent errors and superior angular momentum conservation. They converge more slowly on some problems (smooth, slow-moving flows), but more rapidly on others (involving advection/rotation). In all cases, we show divergence control beyond the Powell 8-wave approach is necessary, or all methods can converge to unphysical answers even at high resolution.

  9. A systematic approach to the accurate quantification of selenium in serum selenoalbumin by HPLC-ICP-MS.

    PubMed

    Jitaru, Petru; Goenaga-Infante, Heidi; Vaslin-Reimann, Sophie; Fisicaro, Paola

    2010-01-11

    In this paper, two different methods are for the first time systematically compared for the determination of selenium in human serum selenoalbumin (SeAlb). Firstly, SeAlb was enzymatically hydrolyzed and the resulting selenomethionine (SeMet) was quantified using species-specific isotope dilution (SSID) with reversed phase-HPLC (RP-HPLC) hyphenated to (collision/reaction cell) inductively coupled plasma-quadrupole mass spectrometry (CRC ICP-QMS). In order to assess the enzymatic hydrolysis yield, SeAlb was determined as an intact protein by affinity-HPLC (AF-HPLC) coupled to CRC ICP-QMS. Using this approach, glutathione peroxidase (GPx) and selenoprotein P (SelP) (the two selenoproteins present in serum) were also determined within the same chromatographic run. The levels of selenium associated with SeAlb in three serum materials, namely BCR-637, Seronorm level 1 and Seronorm level 2, obtained using both methods were in a good agreement. Verification of the absence of free SeMet, which interferes with the SeAlb determination (down to the amino acid level), in such materials was addressed by analyzing the fraction of GPx, partially purified by AF-HPLC, using RP-HPLC (GPx only) and size exclusion-HPLC (SE-HPLC) coupled to CRC ICP-QMS. The latter methodology was also used for the investigation of the presence of selenium species other than the selenoproteins in the (AF-HPLC) SelP and SeAlb fractions; the same selenium peaks were detected in both control and BCR-637 serum with a difference in age of ca. 12 years. It is also for the first time that the concentrations of selenium associated with SeAlb, GPx and SelP species in such commercially available serums (only certified or having indicative levels of total selenium content) are reported. Such indicative values can be used for reference purposes in future validation of speciation methods for selenium in human serum and/or inter-laboratory comparisons. PMID:20005320

  10. Two highly accurate methods for pitch calibration

    NASA Astrophysics Data System (ADS)

    Kniel, K.; Härtig, F.; Osawa, S.; Sato, O.

    2009-11-01

    Among profiles, helix and tooth thickness pitch is one of the most important parameters of an involute gear measurement evaluation. In principle, coordinate measuring machines (CMM) and CNC-controlled gear measuring machines as a variant of a CMM are suited for these kinds of gear measurements. Now the Japan National Institute of Advanced Industrial Science and Technology (NMIJ/AIST) and the German national metrology institute the Physikalisch-Technische Bundesanstalt (PTB) have each developed independently highly accurate pitch calibration methods applicable to CMM or gear measuring machines. Both calibration methods are based on the so-called closure technique which allows the separation of the systematic errors of the measurement device and the errors of the gear. For the verification of both calibration methods, NMIJ/AIST and PTB performed measurements on a specially designed pitch artifact. The comparison of the results shows that both methods can be used for highly accurate calibrations of pitch standards.

  11. Validated HPLC and Ultra-HPLC Methods for Determination of Dronedarone and Amiodarone Application for Counterfeit Drug Analysis.

    PubMed

    El-Bagary, Ramzia I; Elkady, Ehab F; Mowaka, Shereen; Attallah, Maria

    2015-01-01

    Two simple, accurate, and precise chromatographic methods have been developed and validated for the determination of dronedarone (DRO) HCl and amiodarone (AMI) HCl either alone or in binary mixtures due to the possibility of using AMI as a counterfeit of DRO because of its lower price. First, an RP-HPLC method is described for the simultaneous determination of DRO and AMI. Chromatographic separation was achieved on a BDS Hypersil C18 column (150×4.6 mm, 5 μm). Isocratic elution based on potassium dihydrogen phosphate buffer with 0.1% triethylamine pH 6-methanol (10+90, v/v) at a flow rate of 2 mL/min with UV detection at 254 nm was performed. The second method is RP ultra-HPLC in which the chromatographic separation was achieved on an AcclaimTM RSLC 120 C18 column (100×2.1 mm, 2.2 μm) using isocratic elution with potassium dihydrogen phosphate buffer with 0.1% triethylamine pH 6-methanol (5+95, v/v) at a flow rate of 1 mL/min with UV detection at 254 nm. Linearity, accuracy, and precision of the two methods were found to be acceptable over the concentration ranges of 5-80 μg/mL for both DRO and AMI. The results were statistically compared using one-way analysis of variance. The optimized methods were validated and proved to be specific, robust, precise, and accurate for the QC of the drugs in their pharmaceutical preparations. PMID:26651561

  12. HPLC-DAD and HPLC-ESI-MS/MS methods for metabolite profiling of propolis extracts.

    PubMed

    Pellati, Federica; Orlandini, Giulia; Pinetti, Diego; Benvenuti, Stefania

    2011-07-15

    In this study, the composition of polyphenols (phenolic acids and flavonoids) in propolis extracts was investigated by HPLC-DAD and HPLC-ESI-MS/MS by comparing the performance of ion trap and triple quadrupole mass analyzers. The analyses were carried out on an Ascentis C(18) column (250mm×4.6mm I.D., 5μm), with a mobile phase composed by 0.1% formic acid in water and acetonitrile. Overall, the UV spectra, the MS and MS/MS data allowed the identification of 40 compounds. In the case of flavonoids, the triple quadrupole mass analyzer provided more collision energy if compared with the ion trap, originating product ions at best sensitivity. The HPLC method was validated in agreement with ICH guidelines: the correlation coefficients were >0.998; the limit of detection was in the range 1.6-4.6μg/ml; the recovery range was 96-105%; the intra- and inter-day %RSD values for retention times and peak areas were found to be <0.3 and 1.9%, respectively. The developed technique was applied to the analysis of hydroalcoholic extracts of propolis available on the Italian market. Although the chromatographic profile of the analyzed samples was similar, the quantitative analysis indicated that there is a great variability in the amount of the active compounds: the content of total phenolic acids ranged from 0.17 to 16.67mg/ml and the level of total flavonoids from 2.48 to 41.10mg/ml. The proposed method can be considered suitable for the phytochemical analysis of propolis extracts used in phytotherapy. PMID:21497475

  13. Accurate upwind methods for the Euler equations

    NASA Technical Reports Server (NTRS)

    Huynh, Hung T.

    1993-01-01

    A new class of piecewise linear methods for the numerical solution of the one-dimensional Euler equations of gas dynamics is presented. These methods are uniformly second-order accurate, and can be considered as extensions of Godunov's scheme. With an appropriate definition of monotonicity preservation for the case of linear convection, it can be shown that they preserve monotonicity. Similar to Van Leer's MUSCL scheme, they consist of two key steps: a reconstruction step followed by an upwind step. For the reconstruction step, a monotonicity constraint that preserves uniform second-order accuracy is introduced. Computational efficiency is enhanced by devising a criterion that detects the 'smooth' part of the data where the constraint is redundant. The concept and coding of the constraint are simplified by the use of the median function. A slope steepening technique, which has no effect at smooth regions and can resolve a contact discontinuity in four cells, is described. As for the upwind step, existing and new methods are applied in a manner slightly different from those in the literature. These methods are derived by approximating the Euler equations via linearization and diagonalization. At a 'smooth' interface, Harten, Lax, and Van Leer's one intermediate state model is employed. A modification for this model that can resolve contact discontinuities is presented. Near a discontinuity, either this modified model or a more accurate one, namely, Roe's flux-difference splitting. is used. The current presentation of Roe's method, via the conceptually simple flux-vector splitting, not only establishes a connection between the two splittings, but also leads to an admissibility correction with no conditional statement, and an efficient approximation to Osher's approximate Riemann solver. These reconstruction and upwind steps result in schemes that are uniformly second-order accurate and economical at smooth regions, and yield high resolution at discontinuities.

  14. Methods and applications of HPLC-AMS (WBio 5)

    SciTech Connect

    Bucholz, B A; Clifford, A J; Duecker, S R; Lin, Y; Vogel, J S

    1999-09-29

    Pharmacokinetics of physiologic doses of nutrients, pesticides, and herbicides can easily be traced in humans using a {sup 14}C-labelled compound. Basic kinetics can be monitored in blood or urine by measuring the elevation in the {sup 14}C content above the control predose tissue and converting to equivalents of the parent compound. High Performance Liquid Chromatography (HPLC) is an excellent method for the chemical separation of complex mixtures whose profiles afford estimation of biochemical pathways of metabolism. Compounds elute from the HPLC systems with characteristic retention times and can be collected in fractions that can then be graphitized for AMS measurement. Unknowns are identified by coelution with known standards and chemical tests that reveal functional groupings. Metabolites are quantified with the {sup 14}C signal. Thoroughly accounting for the carbon inventory in the LC solvents, ion-pairing agents, samples, and carriers adds some complexity to the analysis. In most cases the total carbon inventory is dominated by carrier. Baseline background and stability need to be carefully monitored. Limits of quantitation near 10 amol of {sup 14}C per HPLC fraction are typically achieved. Baselines are maintained by limiting injected {sup 14}C activity <0.17 Bq (4.5 pCi) on the HPLC column.

  15. [Validation of a HPLC method for ochratoxin A determination].

    PubMed

    Bulea, Delia; Spac, A F; Dorneanu, V

    2011-01-01

    Ochratoxin A is a mycotoxin produced by various species of Aspergillus and Penicillium. Ochratoxin A has been detected in cereals and cereal products, coffee beans, beer, wine, spices, pig's kidney and cow's milk. For ochratoxin A, a HPLC method was developed and validated. Ochratoxin A was determined by RP-HPLC, using a liquid chromatograph type HP 1090 Series II, equiped with a fluorescence detector. The analysis was performed with a Phenomenex column, type Luna C18(2) 100A (150 x 4.6 mm; 5 microm) with a mobile phase consisting of a mixture of acetonitrile/water/acid acetic (99/99/2), a flow of 0.7 mL/min. For detection, the wavelenght of excitation was 228 nm and wavelenght of emision was 423 nm. The calibration graph was linear in 6.25-50 ng/mL concentration range (r2 = 0,9991). The detection limits was 1.6 ng/mL and the quantification limit was 4.9 ng/mL. The method precision (RSD = 2.4975%) and the accuracy (recovery was 100.1%) were studied. The HPLC method was applyed for ochratoxin A from food samples with good results. PMID:21870763

  16. TLC and HPLC methods to follow the synthesis of vinorelbine.

    PubMed

    Chunfang, Zhao; Yin, Xiong; Longjiang, Yu; Shuo, Li; Zeqiang, Wu

    2010-09-01

    The thin-layer chromatography (TLC) combined with high-performance liquid chromatography (HPLC) has been proved to be a quick and valid method to detect the intermediates and the end-product created during the chemosynthesis process of vinorelbine (VB). This paper gives a detailed investigation on the results of two determination methods when the condition of the detection changed. It shows that when TLC developer is consisted of petroleum ether, chloroform, acetone, and diethyl amine (23.5:12:2:2.5, v/v/v/v), vinblastine sulfate (VBS), anhydrovinblastine (AHVB), and VB can be separated specifically. When the mobile phase of HPLC is a mixture of methyl alcohol, acetonitrile, diethyl amine, and high purity water (420:252:3:225; v/v/v/v), adjusted with orthophosphoric acid to pH 6.5, the intermediates and the resultants of the chemosynthesis of VB can be determined effectively. It can also be used to fix quantify of the resultants. The calibration curve for VB shows good linearity in the two mass concentration ranges of 0.0100-0.0500 mg/mL (r = 0.9956) and 0.00600-0.0100 mg/mL (r = 0.9978), respectively. The limit of detection of HPLC for VB is 0.200 microg/mL. PMID:20819300

  17. Determination of the biotin content of select foods using accurate and sensitive HPLC/avidin binding

    PubMed Central

    Staggs, C.G.; Sealey, W.M.; McCabe, B.J.; Teague, A.M.; Mock, D.M.

    2006-01-01

    Assessing dietary biotin content, biotin bioavailability, and resulting biotin status are crucial in determining whether biotin deficiency is teratogenic in humans. Accuracy in estimating dietary biotin is limited both by data gaps in food composition tables and by inaccuracies in published data. The present study applied sensitive and specific analytical techniques to determine values for biotin content in a select group of foods. Total biotin content of 87 foods was determined using acid hydrolysis and the HPLC/avidin-binding assay. These values are consistent with published values in that meat, fish, poultry, egg, dairy, and some vegetables are relatively rich sources of biotin. However, these biotin values disagreed substantially with published values for many foods. Assay values varied between 247 times greater than published values for a given food to as much as 36% less than the published biotin value. Among 51 foods assayed for which published values were available, only seven agreed within analytical variability (720%). We conclude that published values for biotin content of foods are likely to be inaccurate. PMID:16648879

  18. Practical aspects of spatially high accurate methods

    NASA Technical Reports Server (NTRS)

    Godfrey, Andrew G.; Mitchell, Curtis R.; Walters, Robert W.

    1992-01-01

    The computational qualities of high order spatially accurate methods for the finite volume solution of the Euler equations are presented. Two dimensional essentially non-oscillatory (ENO), k-exact, and 'dimension by dimension' ENO reconstruction operators are discussed and compared in terms of reconstruction and solution accuracy, computational cost and oscillatory behavior in supersonic flows with shocks. Inherent steady state convergence difficulties are demonstrated for adaptive stencil algorithms. An exact solution to the heat equation is used to determine reconstruction error, and the computational intensity is reflected in operation counts. Standard MUSCL differencing is included for comparison. Numerical experiments presented include the Ringleb flow for numerical accuracy and a shock reflection problem. A vortex-shock interaction demonstrates the ability of the ENO scheme to excel in simulating unsteady high-frequency flow physics.

  19. Accurate paleointensities - the multi-method approach

    NASA Astrophysics Data System (ADS)

    de Groot, Lennart

    2016-04-01

    The accuracy of models describing rapid changes in the geomagnetic field over the past millennia critically depends on the availability of reliable paleointensity estimates. Over the past decade methods to derive paleointensities from lavas (the only recorder of the geomagnetic field that is available all over the globe and through geologic times) have seen significant improvements and various alternative techniques were proposed. The 'classical' Thellier-style approach was optimized and selection criteria were defined in the 'Standard Paleointensity Definitions' (Paterson et al, 2014). The Multispecimen approach was validated and the importance of additional tests and criteria to assess Multispecimen results must be emphasized. Recently, a non-heating, relative paleointensity technique was proposed -the pseudo-Thellier protocol- which shows great potential in both accuracy and efficiency, but currently lacks a solid theoretical underpinning. Here I present work using all three of the aforementioned paleointensity methods on suites of young lavas taken from the volcanic islands of Hawaii, La Palma, Gran Canaria, Tenerife, and Terceira. Many of the sampled cooling units are <100 years old, the actual field strength at the time of cooling is therefore reasonably well known. Rather intuitively, flows that produce coherent results from two or more different paleointensity methods yield the most accurate estimates of the paleofield. Furthermore, the results for some flows pass the selection criteria for one method, but fail in other techniques. Scrutinizing and combing all acceptable results yielded reliable paleointensity estimates for 60-70% of all sampled cooling units - an exceptionally high success rate. This 'multi-method paleointensity approach' therefore has high potential to provide the much-needed paleointensities to improve geomagnetic field models for the Holocene.

  20. Quantitative analysis of eugenol in clove extract by a validated HPLC method.

    PubMed

    Yun, So-Mi; Lee, Myoung-Heon; Lee, Kwang-Jick; Ku, Hyun-Ok; Son, Seong-Wan; Joo, Yi-Seok

    2010-01-01

    Clove (Eugenia caryophyllata) is a well-known medicinal plant used for diarrhea, digestive disorders, or in antiseptics in Korea. Eugenol is the main active ingredient of clove and has been chosen as a marker compound for the chemical evaluation or QC of clove. This paper reports the development and validation of an HPLC-diode array detection (DAD) method for the determination of eugenol in clove. HPLC separation was accomplished on an XTerra RP18 column (250 x 4.6 mm id, 5 microm) with an isocratic mobile phase of 60% methanol and DAD at 280 nm. Calibration graphs were linear with very good correlation coefficients (r2 > 0.9999) from 12.5 to 1000 ng/mL. The LOD was 0.81 and the LOQ was 2.47 ng/mL. The method showed good intraday precision (%RSD 0.08-0.27%) and interday precision (%RSD 0.32-1.19%). The method was applied to the analysis of eugenol from clove cultivated in various countries (Indonesia, Singapore, and China). Quantitative analysis of the 15 clove samples showed that the content of eugenol varied significantly, ranging from 163 to 1049 ppb. The method of determination of eugenol by HPLC is accurate to evaluate the quality and safety assurance of clove, based on the results of this study. PMID:21313806

  1. Evaluation of tamoxifen and metabolites by LC-MS/MS and HPLC methods.

    PubMed

    Heath, D D; Flat, S W; Wu, A H B; Pruitt, M A; Rock, C L

    2014-01-01

    Epidemiological and laboratory evidence suggests that quantification of serum or plasma levels of tamoxifen and its metabolites, 4-hydroxy-N-desmethyl-tamoxifen (endoxifen), Z-4-hydroxytamoxifen (4HT), N-desmethyl-tamoxifen (ND-tam), is a clinically useful tool in the assessment and monitoring of breast cancer status in patients taking adjuvant tamoxifen. A liquid chromatographic mass spectrometric method (LC-MS/MS) was used to measure the blood levels of tamoxifen and its metabolites. This fully automated analytical method is specific, accurate and sensitive. The LC-MS/MS automated technique has now become a widely accepted reference method. This study analysed a randomly selected batch of blood samples from participants enrolled in a breast cancer study to compare results from this reference method in 40 samples with those obtained from a recently developed high-performance liquid chromatography (HPLC) method with fluorescence detection. The mean (SD) concentrations for the LC-MS/MS method (endoxifen 12.6 [7.5] ng/mL, tamoxifen 105 [44] ng/mL, 4-HT 1.9 [1.0] ng/mL, ND-tam 181 [69] ng/mL) and the HPLC method (endoxifen 13.1 [7.8] ng/mL, tamoxifen 108 [55] ng/mL, 4-HT 1.8 [0.8] ng/mL, ND-tam 184 [81] ng/mL) did not show any significant differences. The results confirm that the HPLC method offers an accurate and comparable alternative for the quantification of tamoxifen and tamoxifen metabolites. PMID:24693573

  2. Screening of the polyphenol content of tomato-based products through accurate-mass spectrometry (HPLC-ESI-QTOF).

    PubMed

    Vallverdú-Queralt, Anna; Jáuregui, Olga; Di Lecce, Giuseppe; Andrés-Lacueva, Cristina; Lamuela-Raventós, Rosa M

    2011-12-01

    Tomatoes, the second most important vegetable crop worldwide, are a key component in the so-called "Mediterranean diet" and its consumption has greatly increased worldwide over the past 2 decades, mostly due to a growing demand for tomato-based products such as ketchups, gazpachos and tomato juices. In this work, tomato-based products were analysed after a suitable work-up extraction procedure using liquid chromatography/electrospray ionisation-time of flight-mass spectrometry (HPLC-ESI-QTOF) with negative ion detection using information-dependent acquisition (IDA) to determine their phenolic composition. The compounds were confirmed by accurate mass measurements in MS and MS(2) modes. The elemental composition was selected according to the accurate masses and isotopic pattern. In this way, 47 compounds (simple phenolic and hydroxycinnamoylquinic acids and flavone, flavonol, flavanone and dihydrochalcone derivatives) were identified in tomato-based products, five of them, as far as was known, were previously unreported in tomatoes. The phenolic fingerprint showed that tomato-based products differ in phenolic composition, principally in protocatechuic acid-O-hexoside, apigenin and its glycosylated forms, quercetin-O-dihexoside, kaempferol-C-hexoside and eriodictyol-O-dihexoside. Gazpacho showed the highest number of phenolic compounds due to the vegetables added for its production. PMID:25212313

  3. An HPLC-ECD method for monoamines and metabolites quantification in cuttlefish (cephalopod) brain tissue.

    PubMed

    Bidel, Flavie; Corvaisier, Sophie; Jozet-Alves, Christelle; Pottier, Ivannah; Dauphin, François; Naud, Nadège; Bellanger, Cécile

    2016-08-01

    The cuttlefish belongs to the mollusk class Cephalopoda, considered as the most advanced marine invertebrates and thus widely used as models to study the biology of complex behaviors and cognition, as well as their related neurochemical mechanisms. Surprisingly, methods to quantify the biogenic monoamines and their metabolites in cuttlefish brain remain sparse and measure a limited number of analytes. This work aims to validate an HPLC-ECD method for the simultaneous quantification of dopamine, serotonin, norepinephrine and their main metabolites in cuttlefish brain. In comparison and in order to develop a method suitable to answer both ecological and biomedical questions, the validation was also carried out on a phylogenetically remote species: mouse (mammals). The method was shown to be accurate, precise, selective, repeatable and sensitive over a wide range of concentrations for 5-hydroxyindole-3-acetic acid, serotonin, dopamine, 3,4-dihydroxyphenylacetic acid and norepinephrine in the both extracts of cuttlefish and mouse brain, though with low precision and recovery for 4-hydroxy-3-methoxyphenylethylene glycol. Homovanillic acid, accurately studied in rodents, was not detectable in the brain of cuttlefish. Overall, we described here the first fully validated HPLC method for the routine measurement of both monoamines and metabolites in cuttlefish brain. Copyright © 2016 John Wiley & Sons, Ltd. PMID:26613377

  4. Multiresidue HPLC methods for phenyl urea herbicides in water.

    PubMed

    Ruberu, S R; Draper, W M; Perera, S K

    2000-09-01

    High-performance liquid chromatography (HPLC) methods for the determination of phenyl urea herbicides in water are described. The target compounds include chlortoluron, diuron, fluometuron, isoproturon, linuron, metobromuron, metoxuron, monuron, neburon, and siduron. Water was subjected to solid phase extraction (SPE) using either automated SPE with 47 mm C(18) Empore disks or on-line precolumn concentration. Herbicides were separated on a C(18) reversed phase column with an acetonitile-water gradient and were detected with either a diode array detector (DAD) or a postcolumn photolysis and derivatization (PPD) detector system. Photolysis converted the phenyl ureas to monoalkylamines that were derivatized to fluorescent isoindoles by reaction with o-phthalaldehyde and 2-mercaptoethanol. The DAD monitoring at 245 nm was linear over three decades with instrument detection limits of approximately 0.01 mg/L. SPE efficiency was between 48 and 70% in laboratory reagent water, but use of the internal standard quantitation method improved accuracy. High total dissolved solids and total organic carbon values in surface water improved recoveries relative to laboratory reagent water for all of the phenyl ureas. In Colorado River water spiked at 1 or 50 microg/L, mean recoveries ranged from 74 to 104%. Method detection limits (MDLs) ranged from 4 to 40 ng/L (parts per trillion) with the DAD instrument. PPD detection was highly specific but resulted in a slight loss in chromatographic efficiency and average MDLs approximately 5 times higher using a single set of detection conditions. The study indicates that methods based on SPE followed by HPLC with diode array or PPD detection have practical utility for trace analysis of phenyl ureas in drinking water or surface waters. PMID:10995323

  5. Structural characterization of low level degradants in aztreonam injection and an innovative approach to aid HPLC method validation.

    PubMed

    Ye, Qingmei; Ding, Wei; Rinaldi, Frank; Huang, Yande; Miller, Scott A; Bolgar, Mark

    2016-05-30

    Three new degradants have been identified from drug product and active pharmaceutical ingredient stability samples of aztreonam, a marketed synthetic monocyclic beta-lactam antibiotic. The degradants were detected following the implementation of a new, more selective HPLC method for the determination of impurities and degradants. The new method was developed in response to changes in the regulatory requirement for mature products. Two of the new unknown Degradants (I and II) were observed in chromatograms from stability samples of aztreonam injection. The third new Degradant (III) was observed during a stability study of the aztreonam active pharmaceutical ingredient. These degradants were structurally characterized. A small amount (ca. 1-3mg) of each degradant was isolated via preparative HPLC for structure elucidation using accurate MS, one and two-dimensional NMR spectroscopy. The small amount of each NMR sample was then reused as a standard for HPLC purity/impurity method validation. Their exact concentrations were determined using quantitative NMR which enabled the execution of the quantitative elements of the HPLC method validation. This innovative approach eliminated the need to isolate or synthesize larger quantities of markers for HPLC/UV method validation, thus saving significant time and reducing costs. PMID:26991056

  6. Determination of Lutein from Fruit and Vegetables Through an Alkaline Hydrolysis Extraction Method and HPLC Analysis.

    PubMed

    Fratianni, Alessandra; Mignogna, Rossella; Niro, Serena; Panfili, Gianfranco

    2015-12-01

    A simple and rapid analytical method for the determination of lutein content, successfully used for cereal matrices, was evaluated in fruit and vegetables. The method involved the determination of lutein after an alkaline hydrolysis of the sample matrix, followed by extraction with solvents and analysis by normal phase HPLC. The optimized method was simple, precise, and accurate and it was characterized by few steps that could prevent loss of lutein and its degradation. The optimized method was used to evaluate the lutein amounts in several fruit and vegetables. Rich sources of lutein were confirmed to be green vegetables such as parsley, spinach, chicory, chard, broccoli, courgette, and peas, even if in a range of variability. Taking into account the suggested reference values these vegetables can be stated as good sources of lutein. PMID:26540023

  7. Validation of AN Hplc-Dad Method for the Classification of Green Teas

    NASA Astrophysics Data System (ADS)

    Yu, Jingbo; Ye, Nengsheng; Gu, Xuexin; Liu, Ni

    A reversed phase high performance liquid chromatography (RP-HPLC) separation coupled with diode array detection (DAD) and electrospray ionization mass spectrometer (ESI/MS) was developed and optimized for the classification of green teas. Five catechins [epigallocatechin (EGC), epigallocatechin gallate (EGCG), epicatechin (EC), gallocatechin gallate (GCG), epicatechin gallate (ECG)] had been identified and quantified by the HPLC-DAD-ESI/MS/MS method. The limit of detection (LOD) of five catechins was within the range of 1.25-15 ng. All the analytes exhibited good linearity up to 2500 ng. These compounds were considered as chemical descriptors to define groups of green teas. Chemometric methods including principal component analysis (PCA) and hierarchical cluster analysis (HCA) were applied for the purpose. Twelve green tea samples originating from different regions were subjected to reveal the natural groups. The results showed that the analyzed green teas were differentiated mainly by provenance; HCA afforded an excellent performance in terms of recognition and prediction abilities. This method was accurate and reproducible, providing a potential approach for authentication of green teas.

  8. [Quality assessment for sustained release pharmaceutical preparations by dissolution test using microdialysis-HPLC method].

    PubMed

    Nagai, Noriaki; Murao, Takatoshi; Inubuse, Rino; Konishi, Nahoko; Ito, Yoshimasa

    2011-04-01

    Dissolution testing is a core performance test in pharmaceutical development and quality control. The conventional HPLC dissolution method (batch-sampling method) has many steps such as the filtration, collection and replenishment of sample solutions. We previously reported the dissolution test by using microdialysis methods (microdialysis-HPLC method) that can omit many steps. In this study, we investigated whether the microdialysis-HPLC method can be applied to quality assessment for sustained release preparations by a dissolution test. Calcium-channel blockers nifedipine tablets (20 mg) were used, and the test solution used was 0.2 M hydrogen phosphate-citric acid buffer (pH 6.8) with or without 1% sodium lauryl sulfate. In both test solutions, the microdialysis-HPLC method is able to accomplish continuous sampling of sample solutions, and the dissolution behaviors of original nifedipine tablets by the microdialysis-HPLC method were similar to that of the batch-sampling method. In contrast, the dissolution behaviors by the microdialysis-HPLC method were different between original nifedipine tablets and generic products, and the dissolution behaviors in the microdialysis-HPLC method tend to reflect the pharmaceutical design in comparison with the batch-sampling method. In addition, standard deviation in the microdialysis-HPLC method was lower than that of the batch-sampling method. We found that the recovery rate of nifedipine by the microdialysis-HPLC method was increased with the decrease in flow rate through dialysis probe. These findings provide significant information that can be used in pharmaceutical development and quality assessment for original and generic pharmaceutical products, which are sustained release preparations. PMID:21467802

  9. Analysis of Piperaceae germplasm by HPLC and LCMS: a method for isolating and identifying unsaturated amides from Piper spp extracts.

    PubMed

    Scott, Ian M; Puniani, Evaloni; Jensen, Helen; Livesey, John F; Poveda, Luis; Sanchez-Vindas, Pablo; Durst, Tony; Arnason, John T

    2005-03-23

    A method for extraction and high performance liquid chromatography-mass spectrometer (HPLC-MS) analysis of the medicinally important genus Piper (Piperaceae) was developed. This allows for a rapid and accurate measure of unsaturated amides, or piperamides, in black pepper, Piper nigrum L., and in wild species from Central America. Reflux extraction provided the highest recovery of piperine (>80%) from leaf and peppercorn material. HPLC analysis using a binary gradient of acetonitrile and water separated the major amide peaks between 5 and 12 min. Atmospheric pressure chemical ionization (APCI)-MS improved the detection limit to 0.2 ng, 10-fold below the 2 ng limit of the HPLC-diode array detector (DAD) based on linear standard curves between 0.1 and 250 microg/mL (R2 = 0.999). The HPLC-MS method identified pellitorine, piperylin, 4,5-dihydropiperlonguminine, piperlonguminine, 4,5-dihydropiperine, piperine, and pipercide. The biological activity of six Costa Rican Piper species assessed by mosquito larval bioassays correlated well with piperamide content. PMID:15769112

  10. Rapid HPLC-MS method for the simultaneous determination of tea catechins and folates.

    PubMed

    Araya-Farias, Monica; Gaudreau, Alain; Rozoy, Elodie; Bazinet, Laurent

    2014-05-14

    An effective and rapid HPLC-MS method for the simultaneous separation of the eight most abundant tea catechins, gallic acid, and caffeine was developed. These compounds were rapidly separated within 9 min by a linear gradient elution using a Zorbax SB-C18 packed with sub 2 μm particles. This methodology did not require preparative and semipreparative HPLC steps. In fact, diluted tea samples can be easily analyzed using HPLC-MS as described in this study. The use of mass spectrometry detection for quantification of catechins ensured a higher specificity of the method. The percent relative standard deviation was generally lower than 4 and 7% for most of the compounds tested in tea drinks and tea extracts, respectively. Furthermore, the method provided excellent resolution for folate determination alone or in combination with catechins. To date, no HPLC method able to discriminate catechins and folates in a quick analysis has been reported in the literature. PMID:24734959

  11. Accurate wavelength calibration method for flat-field grating spectrometers.

    PubMed

    Du, Xuewei; Li, Chaoyang; Xu, Zhe; Wang, Qiuping

    2011-09-01

    A portable spectrometer prototype is built to study wavelength calibration for flat-field grating spectrometers. An accurate calibration method called parameter fitting is presented. Both optical and structural parameters of the spectrometer are included in the wavelength calibration model, which accurately describes the relationship between wavelength and pixel position. Along with higher calibration accuracy, the proposed calibration method can provide information about errors in the installation of the optical components, which will be helpful for spectrometer alignment. PMID:21929865

  12. Differential equation based method for accurate approximations in optimization

    NASA Technical Reports Server (NTRS)

    Pritchard, Jocelyn I.; Adelman, Howard M.

    1990-01-01

    A method to efficiently and accurately approximate the effect of design changes on structural response is described. The key to this method is to interpret sensitivity equations as differential equations that may be solved explicitly for closed form approximations, hence, the method is denoted the Differential Equation Based (DEB) method. Approximations were developed for vibration frequencies, mode shapes and static displacements. The DEB approximation method was applied to a cantilever beam and results compared with the commonly-used linear Taylor series approximations and exact solutions. The test calculations involved perturbing the height, width, cross-sectional area, tip mass, and bending inertia of the beam. The DEB method proved to be very accurate, and in most cases, was more accurate than the linear Taylor series approximation. The method is applicable to simultaneous perturbation of several design variables. Also, the approximations may be used to calculate other system response quantities. For example, the approximations for displacements are used to approximate bending stresses.

  13. Spectroscopic characterization and quantitative determination of atorvastatin calcium impurities by novel HPLC method

    NASA Astrophysics Data System (ADS)

    Gupta, Lokesh Kumar

    2012-11-01

    Seven process related impurities were identified by LC-MS in the atorvastatin calcium drug substance. These impurities were identified by LC-MS. The structure of impurities was confirmed by modern spectroscopic techniques like 1H NMR and IR and physicochemical studies conducted by using synthesized authentic reference compounds. The synthesized reference samples of the impurity compounds were used for the quantitative HPLC determination. These impurities were detected by newly developed gradient, reverse phase high performance liquid chromatographic (HPLC) method. The system suitability of HPLC analysis established the validity of the separation. The analytical method was validated according to International Conference of Harmonization (ICH) with respect to specificity, precision, accuracy, linearity, robustness and stability of analytical solutions to demonstrate the power of newly developed HPLC method.

  14. A new validated HPLC method for the determination of sulforaphane: application to study pharmacokinetics of sulforaphane in rats.

    PubMed

    Ong, Chau; Elbarbry, Fawzy

    2016-07-01

    A simple, accurate and reproducible high-performance liquid chromatography (HPLC) method has been developed and validated for the quantification of sulforaphane (SF) in rat plasma. The method involves a simple liquid-liquid extraction procedure to extract both SF and 7-hyrdoxycoumarin, the internal standard. The chromatographic analysis was achieved on a Shimadzu LC 20A HPLC system equipped with a Zorbax Eclipse XDB C18 column and an isocratic mobile phase consisting of 10 mm KH2 PO4 (pH 4.5) and acetonitrile HPLC grade (40:60, v/v) run at a flow rate of 1 mL/min for 10 min. The UV detection wavelength was set at 202 nm. The method exhibited good linearity (R(2) > 0.999) over the assayed concentration range (0.05-2 μg/mL) and demonstrated good intra- and inter-day precision and accuracy (relative standard deviations and the deviation from predicted values were <15%). This method was also successfully applied for studying the pharmacokinetics of SF in spontaneously hypertensive rats following single oral dietary doses of SF. The pharmacokinetics of SF show linear behavior at the dose range investigated in this study. Copyright © 2015 John Wiley & Sons, Ltd. PMID:26542340

  15. A validated UV-HPLC method for determination of chlorogenic acid in Lepidogrammitis drymoglossoides (Baker) Ching, Polypodiaceae

    PubMed Central

    Wen, Jiagen; Kang, Liqun; Liu, Huan; Xiao, Yiyun; Zhang, Xiuzhen; Chen, Yuxiang

    2012-01-01

    Background: Lepidogrammitis drymoglossoides (Baker) Ching (L. drymoglossoides), a member of the Polypodiaceae family, was used in the treatment of numerous diseases. However, none of the potential ingredients and the quality control methods concerning this plant medicine was pronounced. Objective: To identify chlorogenic acid (CGA) from L. drymoglossoides and develop a high performance liquid chromatography (HPLC) assay of CGA. Materials and Methods: UV, TLC, and HPLC were utilized to identify the phytochemicals of L. drymoglossoides and determine the CGA content, respectively. The HPLC conditions were as following: a Phenomenex Luna C18 (2) (250 × 4.6 mm i.d.; 5 μm particle size; 100 Å pore size) column; the mobile phase of the mixture of acetonitrile and 0.5% aqueous phosphoric acid (11.5:88.5 v/v); the flow rate of 1.0 mL/min and determination wavelength of 327 nm. Results: The proposed HPLC method has been developed and validated. The calibration curve was y = 28328x + 16610 (R2 = 0.9997). The intra-day and inter-day precision and intermediate precision were validated with the RSD less than 5%. The mean recovery rate of the method ranged from 95% to 104%, with the RSD less than 5%. The LOD and LQD values were 0.049 and 0.132 mg/L, respectively. The content of CGA in L. drymoglossoides approximately reached 0.24% (v/v) by the proposed extraction and determination methods. Conclusion: The assay method was simple, convenient, and accurate to the quantification of CGA and can be used for the quality control of the herb. PMID:22923952

  16. A Simple and Accurate Method for Measuring Enzyme Activity.

    ERIC Educational Resources Information Center

    Yip, Din-Yan

    1997-01-01

    Presents methods commonly used for investigating enzyme activity using catalase and presents a new method for measuring catalase activity that is more reliable and accurate. Provides results that are readily reproduced and quantified. Can also be used for investigations of enzyme properties such as the effects of temperature, pH, inhibitors,…

  17. The RP-HPLC method for simultaneous estimation of esomeprazole and naproxen in binary combination

    PubMed Central

    Jain, Deepak Kumar; Jain, Nitesh; Charde, Rita; Jain, Nilesh

    2011-01-01

    Objective: A simple, precise, reliable, rapid, sensitive and validated RP-HPLC method has been developed to determine esomeprazole magnesium trihydrate (ESO) and naproxen (NAP) in synthetic mixture form. Materials and Methods: Chromatographic separation achieved isocratically on Phenomenex, Luna C18 column (5 μm, 150mm × 4.60mm) and acetonitrile: phosphate buffer (pH 7.0) in the ratio of 50:50 (v/v) as the mobile phase, at a flow rate of 0.5 ml/min. Detection was carried out at 300 nm. The retention times for NAP and ESO was found to be 2.67 ±0.014 and 5.65 ±0.09 min respectively. Parameters such as linearity, precision, accuracy, recovery, specificity and ruggedness are studied as reported in the ICH guidelines. Results: The method was linear in the concentration range of 50-250 μg/ml for NAP and 2-10 μg/ml for ESO with correlation coefficient of 0.999 and 0.998 respectively. The mean recoveries obtained for NAP and ESO were 100.01% and 97.76 % respectively and RSD was less than 2. The correlation coefficients for all components are close to 1. Conclusions: Developed method was found to be accurate, precise, selective and rapid for simultaneous estimation of NAP and ESO. PMID:23781450

  18. Combination of an enzymatic method and HPLC for the quantitation of cholesterol in cultured cells.

    PubMed

    Contreras, J A; Castro, M; Bocos, C; Herrera, E; Lasunción, M A

    1992-06-01

    The study of the cellular events that lead to the foam cell formation requires the development of fast, accurate, and sensitive methods to quantify cholesterol in cultured cells. Here we describe a procedure that allows the rapid determination of free and total cholesterol in a reduced number of cells, which makes it very suitable for cholesterol determination in cell cultures. The method consists of the enzymatic conversion of cholesterol to cholest-4-ene-3-one by cholesterol oxidase followed by the analysis of the sample by high performance liquid chromatography (HPLC) to detect this oxidized product. Due to the relatively high wavelength at which cholest-4-ene-3-one has its maximum absorption (240 nm), other cellular components do not interfere with the chromatographic procedure and prior lipid extraction is not required. Moreover, the duration of each chromatogram is about 3 min, contributing to the celerity of the method. All the cholesteryl esters used (oleate, palmitate, stearate and linoleate) were quantitatively hydrolyzed by incubation with cholesterol esterase; this was observed to occur with both pure standards and in cell homogenates. Sensitivity is enough to allow the determination of free and total cholesterol in less than 5 x 10(3) cells. We have applied this method to human monocyte-derived macrophages and the values obtained for free and total cholesterol are in close agreement with published data. PMID:1512516

  19. Optimization of an HPLC Method for Determining the Genomic Methylation Levels of Taxus Cells.

    PubMed

    Li, Xiao-li; Yuan, Jie; Dong, Yan-shan; Fu, Chun-hua; Li, Mao-Teng; Yu, Long-jiang

    2016-02-01

    An HPLC method for quantifying total DNA methylation in Taxus chinensis cells is described. Optimal conditions for the method were established as follows: DNA was hydrolyzed with DNA degradase at 37°C for 3 h. The mobile phase was a mixture of Solvent A [50 mM potassium dihydrogen phosphate/triethylamine (100:0.2, v/v)] and Solvent B (methanol); the gradient was 10% (v/v) solvent B. The calibration curves for deoxycytidine monophosphate (dCMP) and methylated dCMP were linear within 1.0-160.0 µg mL(-1), with correlation coefficients of 0.9996 and 0.9998. The limits of detection for dCMP and 5-mdCMP were 0.482 and 0.301 ng mL(-1), respectively, and the limits of quantification were 1.6 and 1.0 ng mL(-1), respectively. The method has been validated according to the current International Conference Harmonization guidelines. The method was able to quantify the content of dCMP and methylated dCMP specifically, accurately and precisely. The global DNA methylation level in different Taxus cells was measured using as little as 3 µg of DNA according to the optimized procedure. In addition, degradation of 5-methylcytosine was prevented. PMID:26341490

  20. Matrix Solid-Phase Dispersion Extraction and Quantification of Alpinetin in Amomum Seed using Validated HPLC and HPTLC Methods

    PubMed Central

    Singh, M.; Kamal, Y. T.; Khan, M. A.; Parveen, Rabea; Ansari, S. H.; Ahmad, S.

    2015-01-01

    Alpinetin is a flavonoidal constituent of seeds of Amomum subulatum Roxb., recently reported to possess vasorelaxant and antiHIV activities. Simple, accurate and precise HPLC and HPTLC methods were developed for the analysis of alpinetin in A. subulatum seed extracts and extraction technique was optimized to get maximum yield using conventional, ultrasonic and matrix solid phase dispersion extraction. HPLC was performed on a C18 column with methanol and water (70:30, v/v) as mobile phase at a flow rate of 1.0 ml/min whereas HPTLC on silica aluminum sheet (60F254) using toluene, dichloromethane and ethyl acetate as solvent system. A sharp peak was obtained for alpinetin at a retention time (Rt) of 5.7 min by HPLC and retardation factor (Rf) of 0.48 by HPTLC. Both methods were validated as per the ICH guidelines and the content of alpinetin was estimated in different extracts. Matrix solid phase dispersion technique was found most suitable for extracting alpinetin as compared to other techniques. Validation data are indicative of good precision and accuracy and proved the reliability of the methods. PMID:25767318

  1. Method development and validation for the analysis of a new anti-cancer infusion solution via HPLC.

    PubMed

    Donnarumma, Fabrizio; Schober, Margot; Greilberger, Joachim; Matzi, Veronika; Lindenmann, Jörg; Maier, Alfred; Herwig, Ralf; Wintersteiger, Reinhold

    2011-01-01

    A fast and simple HPLC method has been developed and validated for the quantification of a completely new anti-cancer drug during the manufacturing process. The combination of four compounds including α-ketoglutaric acid, hydroxymethylfurfural, N-acetyl-L-methionine and N-acetyl-L-selenomethionine, administered intravenously, is still in test phase but has already shown promising results in cancer therapy. HPLC separation was achieved on an RP-18 column with a gradient system. However, the highly different concentrations of the compounds required a variation in the detection wavelength within one run. In order to produce a chromatogram where peaks were comparable on a similar range scale, detection at absorption maxima for the two most concentrated components was avoided. After optimization of the gradient program it was possible to detect all four substances within 14 min in spite of their strongly different chemical structure. The method developed was validated for accuracy, repeatability, reproducibility and robustness in relation to temperature and pH of buffer. Linearity as well as the limit of detection and quantification were determined. This HPLC method was found to be precise, accurate and reproducible and can be easily used for in-line process control during the manufacture of the anti-tumour infusion solution. PMID:21246718

  2. Improved quantification of pyrogenic carbon in soils and sediments by a HPLC-DAD method

    NASA Astrophysics Data System (ADS)

    Wiedemeier, D. B.; Hilf, M. D.; Smittenberg, R. H.; Schmidt, M. W. I.

    2012-04-01

    Fire-derived (pyrogenic) carbon (PyC) is produced by the incomplete combustion of biomass, for example during wildfires. It can persist in the environment for a long time due to its relative resistance against biological and chemical breakdown. Its accurate quantification in soils and sediments is of great interest because the slow turn-over of PyC has implications for the global carbon cycle and carbon budget calculations. Moreover, PyC in pedological and sedimentological records can be used to reconstruct wildfire history or to investigate historical periods like the industrialization. A whole suite of PyC quantification methods exists because PyC is not a defined chemical structure but rather a continuum of thermally altered biomass. The benzene polycarboxylic acids (BPCA) analysis is a molecular marker method that was shown to give conservative estimates of PyC quantity in soils. In addition, it yields qualitative information about the degree of aromaticity and condensation of PyC. The commonly used BPCA method consists in digesting samples with nitric acid that breaks down the PyC into a suite of BPCAs, which are cleaned, derivatized and finally analyzed by gas chromatography-flame ionization detection (GC-FID). Here, we present a modified BPCA method for soils and sediments that uses a high performance liquid chromatography system coupled to diode array detection (HPLC-DAD). We demonstrate that this method greatly enhances the reproducibility of PyC quantification in soil and sediment samples while significantly reducing analysis time. Moreover, much less sample material is needed for precise PyC quantification and we show that the HPLC-DAD method yields consistently higher PyC contents than the GC-FID method. Additionally, the modified method also facilitates δ13C and 14C measurements of the PyC fraction in these complex matrix samples. The isotopic information further improves the assessment of PyC budgets in the environment and the reconstruction of past

  3. Quantifying Accurate Calorie Estimation Using the "Think Aloud" Method

    ERIC Educational Resources Information Center

    Holmstrup, Michael E.; Stearns-Bruening, Kay; Rozelle, Jeffrey

    2013-01-01

    Objective: Clients often have limited time in a nutrition education setting. An improved understanding of the strategies used to accurately estimate calories may help to identify areas of focused instruction to improve nutrition knowledge. Methods: A "Think Aloud" exercise was recorded during the estimation of calories in a standard dinner meal…

  4. Accurate quantification of total chromium and its speciation form Cr(VI) in water by ICP-DRC-IDMS and HPLC/ICP-DRC-IDMS.

    PubMed

    Markiewicz, Barbara; Komorowicz, Izabela; Barałkiewicz, Danuta

    2016-05-15

    Two analytical procedures have been developed for the determination of total chromium (TCr) and its highly toxic species, i.e. Cr(VI) in water samples using the following methods: inductively coupled plasma dynamic reaction cell isotope dilution mass spectrometry (ICP-DRC-IDMS) and high performance liquid chromatography inductively coupled plasma dynamic reaction cell isotope dilution mass spectrometry (HPLC/ICP-DRC-IDMS). Spectral interferences, predominantly occurring in chromium determination, were removed using a dynamic reaction cell (DRC). The presented procedures facilitate the quantification of trace amounts - below 1 µg L(-1) of TCr and individual Cr species - in various water matrices including drinking water and still bottled water with different mineral composition. Special attention has been paid to the adequate preparation of isotopically enriched (53)Cr(VI) standard solution in order to avoid artifacts in chromium speciation. Both procedures were fully validated as well as establishing the traceability and estimation of the uncertainty of measurement were carried out. Application of all of the above mentioned elements and of the isotope dilution technique, which provides the highest quality of metrological traceability, allowed to obtain reliable and high quality results of chromium determination in water samples. Additionally, the comparison of two methods: HPLC/ICP-DRC-MS and HPLC/ICP-DRC-IDMS for Cr(VI) determination, was submitted basing on the validation parameters. As a result, the lower values for these parameters were obtained using the second method. PMID:26992546

  5. Improved method for HPLC analysis of polyamines, agmatine and aromatic monoamines in plant tissue

    NASA Technical Reports Server (NTRS)

    Slocum, R. D.; Flores, H. E.; Galston, A. W.; Weinstein, L. H.

    1989-01-01

    The high performance liquid chromatographic (HPLC) method of Flores and Galston (1982 Plant Physiol 69: 701) for the separation and quantitation of benzoylated polyamines in plant tissues has been widely adopted by other workers. However, due to previously unrecognized problems associated with the derivatization of agmatine, this important intermediate in plant polyamine metabolism cannot be quantitated using this method. Also, two polyamines, putrescine and diaminopropane, also are not well resolved using this method. A simple modification of the original HPLC procedure greatly improves the separation and quantitation of these amines, and further allows the simulation analysis of phenethylamine and tyramine, which are major monoamine constituents of tobacco and other plant tissues. We have used this modified HPLC method to characterize amine titers in suspension cultured carrot (Daucas carota L.) cells and tobacco (Nicotiana tabacum L.) leaf tissues.

  6. An HPLC method for the determination of ethacridine lactate in human urine.

    PubMed

    Guo, Zhi-Yong; Wei, Dan-Yi; Wang, Yuan-Yuan; Xuan, Kun-Fei; Yu, Xu-Fei; Yu, Qiu-Luan; Chu, Yun

    2007-05-01

    An HPLC method was developed and validated for the determination of ethacridine lactate in human urine. Solid-phase extraction cartridges were used to extract urine samples. Separation was carried out on a C(18) column maintained at 30 degrees C with methanol-0.05% sodium dodecylsulfonate (70:30, v/v, pH 3) as mobile phase at a flow rate of 1.0 mL/min. Detection was at UV 272 nm. The calibration curve was linear in the concentration range of 4-4000 ng/mL, with linear correlation coefficient r equal to 0.9998. The limit of detection for the assay was 1.1 ng/mL. The within-day accuracy ranged from 94.8 to 101.6% and precision from 2.3 to 5.4%. The between-day accuracy ranged from 96.8 to 102.6% and precision from 4.0 to 5.3%. The absolute recovery was 95.4-101.2%. Urine samples were stable for at least 15 days if stored in the dark at -20 degrees C. This simple and accurate method allows the sensitive determination of ethacridine lactate in human urine. It was successfully applied to assess the urine level of ethacridine lactate in women received intra-amniotic injection. PMID:17294498

  7. Differential equation based method for accurate approximations in optimization

    NASA Technical Reports Server (NTRS)

    Pritchard, Jocelyn I.; Adelman, Howard M.

    1990-01-01

    This paper describes a method to efficiently and accurately approximate the effect of design changes on structural response. The key to this new method is to interpret sensitivity equations as differential equations that may be solved explicitly for closed form approximations, hence, the method is denoted the Differential Equation Based (DEB) method. Approximations were developed for vibration frequencies, mode shapes and static displacements. The DEB approximation method was applied to a cantilever beam and results compared with the commonly-used linear Taylor series approximations and exact solutions. The test calculations involved perturbing the height, width, cross-sectional area, tip mass, and bending inertia of the beam. The DEB method proved to be very accurate, and in msot cases, was more accurate than the linear Taylor series approximation. The method is applicable to simultaneous perturbation of several design variables. Also, the approximations may be used to calculate other system response quantities. For example, the approximations for displacement are used to approximate bending stresses.

  8. Accurate upwind-monotone (nonoscillatory) methods for conservation laws

    NASA Technical Reports Server (NTRS)

    Huynh, Hung T.

    1992-01-01

    The well known MUSCL scheme of Van Leer is constructed using a piecewise linear approximation. The MUSCL scheme is second order accurate at the smooth part of the solution except at extrema where the accuracy degenerates to first order due to the monotonicity constraint. To construct accurate schemes which are free from oscillations, the author introduces the concept of upwind monotonicity. Several classes of schemes, which are upwind monotone and of uniform second or third order accuracy are then presented. Results for advection with constant speed are shown. It is also shown that the new scheme compares favorably with state of the art methods.

  9. [Determination of saponosides from Panax ginseng C.A. Meyer. Comparison of official methods and HPLC].

    PubMed

    Guédon, D; Abbe, P; Cappelaere, N; Rames, N

    1989-01-01

    Official methods for determination of ginsenosides of the French and Helvetic Pharmacopoeias have been compared with HPLC method. Sample preparation schemes used are those of monographs with conventional solvent extraction and solid phase extraction with a polar and a non-polar sorbents, respectively kieselguhr and C 18 octadecyl. Liquid-solid sample clean-up with C 18 cartridge is the most effective procedure. Prior HPLC method, an hydrolysis step of malonylginsenosides is necessary. Very selective extraction resulting in highly purified solution authorizes reliable and rapid colorimetric determination from ginseng saponosides. PMID:2634933

  10. Accurate Method for Determining Adhesion of Cantilever Beams

    SciTech Connect

    Michalske, T.A.; de Boer, M.P.

    1999-01-08

    Using surface micromachined samples, we demonstrate the accurate measurement of cantilever beam adhesion by using test structures which are adhered over long attachment lengths. We show that this configuration has a deep energy well, such that a fracture equilibrium is easily reached. When compared to the commonly used method of determining the shortest attached beam, the present method is much less sensitive to variations in surface topography or to details of capillary drying.

  11. Accurate method for determining adhesion of cantilever beams

    SciTech Connect

    de Boer, M.P.; Michalske, T.A.

    1999-07-01

    Using surface micromachined samples, we demonstrate the accurate measurement of cantilever beam adhesion by using test structures which are adhered over long attachment lengths. We show that this configuration has a deep energy well, such that a fracture equilibrium is easily reached. When compared to the commonly used method of determining the shortest attached beam, the present method is much less sensitive to variations in surface topography or to details of capillary drying. {copyright} {ital 1999 American Institute of Physics.}

  12. FTIR assay method for UV inactive drug carisoprodol and identification of degradants by RP-HPLC and ESI-MS.

    PubMed

    Acharya, Pratap Chandra; Vasi, Ruqaiya; Suares, Divya

    2016-09-01

    A new method of analysis has been developed for UV inactive drug carisoprodol using FTIR spectroscopy. These methods were validated for various parameters according to ICH guidelines. The proposed method has also been successfully applied for the determination of the drug concentration in a tablet formulation. The method proved to be accurate (mean percentage recovery between 95 and 105%), precise and reproducible (relative standard deviation<2%), while being simple, economical and less time consuming than other methods and can be used for routine estimation of carisoprodol in the pharmaceutical industry. The developed method also implicates its utility for other UV inactive substances. The stability of the drug under various stress conditions was studied and the drug was found to be particularly susceptible to alkaline hydrolysis. Degradation products of the alkaline hydrolysis were detected by RP-HPLC and tentatively identified by ESI-MS. PMID:27398631

  13. Method for Accurately Calibrating a Spectrometer Using Broadband Light

    NASA Technical Reports Server (NTRS)

    Simmons, Stephen; Youngquist, Robert

    2011-01-01

    A novel method has been developed for performing very fine calibration of a spectrometer. This process is particularly useful for modern miniature charge-coupled device (CCD) spectrometers where a typical factory wavelength calibration has been performed and a finer, more accurate calibration is desired. Typically, the factory calibration is done with a spectral line source that generates light at known wavelengths, allowing specific pixels in the CCD array to be assigned wavelength values. This method is good to about 1 nm across the spectrometer s wavelength range. This new method appears to be accurate to about 0.1 nm, a factor of ten improvement. White light is passed through an unbalanced Michelson interferometer, producing an optical signal with significant spectral variation. A simple theory can be developed to describe this spectral pattern, so by comparing the actual spectrometer output against this predicted pattern, errors in the wavelength assignment made by the spectrometer can be determined.

  14. Simultaneous determination of contents of three active components in Jiejia tincture by HPLC method.

    PubMed

    Li, Kun; Wang, Fei; Diao, Yun-Peng; Pan, Xiao-qiu; Yun-Juan, E; Zhang, Huo-Li

    2013-01-01

    The objective of the study was to determine the contents of three active components in Jiejia tincture by establishing HPLC method. Test articles were prepared by ultrasonic extraction. Separation was performed using a Kromasil C18 (250 mm × 4.6 mm, 5 µm) chromatographic column, and gradient elution was performed with acetonitrile-0.3% phosphoric acid solution as the mobile phase at a volumetric flow rate of 0.80 mL/min. The contents of catechin, baicalin and berberine in Jiejia tincture were determined at the wavelength of 276 nm and a column temperature of 30 □. The results revealed that catechin showed a good linear relationship at the range of 100∼800 µg/mL (r=0.9997); baicalin showed a good linear relationship at the range of 15∼120 µg/mL (r=0.9996), and berberine at the range of 7∼56 µg/mL (r=0.9995). Their average recovery rates were 99.67% (RSD 1.01%, n=6), 98.7% (RSD 1.93%, n=6) and 100.5% (RSD 2.88%, n=6) respectively. The study concluded that the high-performance liquid chromatography established in this study was simple, accurate and reproducible, and can also be used in the determination of catechin, baicalin and berberine contents in Jiejia tincture. PMID:24311852

  15. A thin film degradation study of a fluorinated polyether liquid lubricant using an HPLC method

    NASA Technical Reports Server (NTRS)

    Morales, W.

    1986-01-01

    A High Pressure Liquid Chromatography (HPLC) separation method was developed to study and analyze a fluorinated polyether fluid which is promising liquid lubricant for future applications. This HPLC separation method was used in a preliminary study investigating the catalytic effect of various metal, metal alloy, and ceramic engineering materials on the degradation of this fluid in a dry air atmosphere at 345 C. Using a 440 C stainless steel as a reference catalytic material it was found that a titanium alloy and a chromium plated material degraded the fluorinated polyether fluid substantially more than the reference material.

  16. Exploring accurate Poisson–Boltzmann methods for biomolecular simulations

    PubMed Central

    Wang, Changhao; Wang, Jun; Cai, Qin; Li, Zhilin; Zhao, Hong-Kai; Luo, Ray

    2013-01-01

    Accurate and efficient treatment of electrostatics is a crucial step in computational analyses of biomolecular structures and dynamics. In this study, we have explored a second-order finite-difference numerical method to solve the widely used Poisson–Boltzmann equation for electrostatic analyses of realistic bio-molecules. The so-called immersed interface method was first validated and found to be consistent with the classical weighted harmonic averaging method for a diversified set of test biomolecules. The numerical accuracy and convergence behaviors of the new method were next analyzed in its computation of numerical reaction field grid potentials, energies, and atomic solvation forces. Overall similar convergence behaviors were observed as those by the classical method. Interestingly, the new method was found to deliver more accurate and better-converged grid potentials than the classical method on or nearby the molecular surface, though the numerical advantage of the new method is reduced when grid potentials are extrapolated to the molecular surface. Our exploratory study indicates the need for further improving interpolation/extrapolation schemes in addition to the developments of higher-order numerical methods that have attracted most attention in the field. PMID:24443709

  17. A NEW HPLC METHOD FOR SEPARATION OF PHYTOPLANKTON PIGMENTS IN NATURAL SAMPLES

    EPA Science Inventory

    A new high-performance liquid chromatographic (HPLC) method was developed to analyze, in a single run, most polar and non-polar chlorophylls and carotenoids from marine phytoplankton. The method is based on a reverse-phase amide C16 (RP-amide C16) column and an elution gradient o...

  18. HPLC method to characterize cyanogen bromide collagen fractions containing pyridinoline groups.

    PubMed

    Bruno, R; Mazza, R; Calafiori, A R; Covello, C; Falbo, L; Martino, G; Marotta, M

    1997-01-01

    The HPLC method here described allows to separate CNBr collagen peptides within 2.5 h by reversed phase and gradient elution. The method is useful to determine both peptide bond and pyridinoline groups by absorbance spectophotometry. The fractions can be recovered and then submitted to other characterization techniques. PMID:10327703

  19. Preliminary Study of High Resolution HPLC Analytical Method for Sedimentary Pigments Based on Coupled C8 Columns

    NASA Astrophysics Data System (ADS)

    Yao, P.; Yu, Z.; Deng, C.; Liu, S.; Zhao, J.

    2008-05-01

    The pigments in marine water columns can provide accurate estimates of community composition and abundance of phytoplankton. In addition, the sedimentary pigments, especially the derivatives of chlorophyll such as pyrophaeophytins, pyrophaeophorbides and steryl chlorin esters (SCEs) formed during early diagenesis can also provide information on the primary producer community and the changes in paleoproductivity. Accordingly, analysis of pigments and their derivatives is of great importance for oceanography, limnology and geochemistry. Many methods have been developed for the separation of chlorophylls, carotenoids and their derivatives derived from phytoplankton and water column samples using high-performance liquid chromatography (HPLC). Methods widely cited in the literatures include those developed by Wright et al. (1991) and Zapata et al. (2000). Both methods use reversed-phase columns, but C18 column was employed in Wright et al. (1991) and C8 column in Zapata et al. (2000). However, evident coelutions are observed in published works. This will particularly cause problematic identification and quantification in dealing with sedimentary pigments which are highly complex and often display a broad range in polarity. Clearly, it is necessary to improve the separation of the complex pigments if the information carried by the pigments is to be used fully. Coupled C18 columns were used in the HPLC method developed by Airs et al. (2001) for the analysis of complex pigment distributions. Improved chromatographic resolution, more pigment components and novel bacteriochlorophyll derivatives were obtained by this method. It indicates a new road for HPLC method development. C8 column has shorter carbon chains than that of C18 column and can provide less retention of apolar compounds which is of particular advantaged to hydrophobic chlorophyll a, b and their derivatives. That is one of the reasons why the C8 method developed by Zapata et al. (2000) is admittedly better than

  20. Accurate projector calibration method by using an optical coaxial camera.

    PubMed

    Huang, Shujun; Xie, Lili; Wang, Zhangying; Zhang, Zonghua; Gao, Feng; Jiang, Xiangqian

    2015-02-01

    Digital light processing (DLP) projectors have been widely utilized to project digital structured-light patterns in 3D imaging systems. In order to obtain accurate 3D shape data, it is important to calibrate DLP projectors to obtain the internal parameters. The existing projector calibration methods have complicated procedures or low accuracy of the obtained parameters. This paper presents a novel method to accurately calibrate a DLP projector by using an optical coaxial camera. The optical coaxial geometry is realized by a plate beam splitter, so the DLP projector can be treated as a true inverse camera. A plate having discrete markers on the surface is used to calibrate the projector. The corresponding projector pixel coordinate of each marker on the plate is determined by projecting vertical and horizontal sinusoidal fringe patterns on the plate surface and calculating the absolute phase. The internal parameters of the DLP projector are obtained by the corresponding point pair between the projector pixel coordinate and the world coordinate of discrete markers. Experimental results show that the proposed method can accurately calibrate the internal parameters of a DLP projector. PMID:25967789

  1. Development and application of a validated HPLC method for the analysis of dissolution samples of levothyroxine sodium drug products.

    PubMed

    Collier, J W; Shah, R B; Bryant, A R; Habib, M J; Khan, M A; Faustino, P J

    2011-02-20

    A rapid, selective, and sensitive gradient HPLC method was developed for the analysis of dissolution samples of levothyroxine sodium tablets. Current USP methodology for levothyroxine (L-T(4)) was not adequate to resolve co-elutants from a variety of levothyroxine drug product formulations. The USP method for analyzing dissolution samples of the drug product has shown significant intra- and inter-day variability. The sources of method variability include chromatographic interferences introduced by the dissolution media and the formulation excipients. In the present work, chromatographic separation of levothyroxine was achieved on an Agilent 1100 Series HPLC with a Waters Nova-pak column (250 mm × 3.9 mm) using a 0.01 M phosphate buffer (pH 3.0)-methanol (55:45, v/v) in a gradient elution mobile phase at a flow rate of 1.0 mL/min and detection UV wavelength of 225 nm. The injection volume was 800 μL and the column temperature was maintained at 28°C. The method was validated according to USP Category I requirements. The validation characteristics included accuracy, precision, specificity, linearity, and analytical range. The standard curve was found to have a linear relationship (r(2)>0.99) over the analytical range of 0.08-0.8 μg/mL. Accuracy ranged from 90 to 110% for low quality control (QC) standards and 95 to 105% for medium and high QC standards. Precision was <2% at all QC levels. The method was found to be accurate, precise, selective, and linear for L-T(4) over the analytical range. The HPLC method was successfully applied to the analysis of dissolution samples of marketed levothyroxine sodium tablets. PMID:20947276

  2. Development and application of a validated HPLC method for the analysis of dissolution samples of levothyroxine sodium drug products

    PubMed Central

    Collier, J.W.; Shah, R.B.; Bryant, A.R.; Habib, M.J.; Khan, M.A.; Faustino, P.J.

    2011-01-01

    A rapid, selective, and sensitive gradient HPLC method was developed for the analysis of dissolution samples of levothyroxine sodium tablets. Current USP methodology for levothyroxine (l-T4) was not adequate to resolve co-elutants from a variety of levothyroxine drug product formulations. The USP method for analyzing dissolution samples of the drug product has shown significant intra- and inter-day variability. The sources of method variability include chromatographic interferences introduced by the dissolution media and the formulation excipients. In the present work, chromatographic separation of levothyroxine was achieved on an Agilent 1100 Series HPLC with a Waters Nova-pak column (250mm × 3.9mm) using a 0.01 M phosphate buffer (pH 3.0)–methanol (55:45, v/v) in a gradient elution mobile phase at a flow rate of 1.0 mL/min and detection UV wavelength of 225 nm. The injection volume was 800 µL and the column temperature was maintained at 28 °C. The method was validated according to USP Category I requirements. The validation characteristics included accuracy, precision, specificity, linearity, and analytical range. The standard curve was found to have a linear relationship (r2 > 0.99) over the analytical range of 0.08–0.8 µg/mL. Accuracy ranged from 90 to 110% for low quality control (QC) standards and 95 to 105% for medium and high QC standards. Precision was <2% at all QC levels. The method was found to be accurate, precise, selective, and linear for l-T4 over the analytical range. The HPLC method was successfully applied to the analysis of dissolution samples of marketed levothyroxine sodium tablets. PMID:20947276

  3. Reverse radiance: a fast accurate method for determining luminance

    NASA Astrophysics Data System (ADS)

    Moore, Kenneth E.; Rykowski, Ronald F.; Gangadhara, Sanjay

    2012-10-01

    Reverse ray tracing from a region of interest backward to the source has long been proposed as an efficient method of determining luminous flux. The idea is to trace rays only from where the final flux needs to be known back to the source, rather than tracing in the forward direction from the source outward to see where the light goes. Once the reverse ray reaches the source, the radiance the equivalent forward ray would have represented is determined and the resulting flux computed. Although reverse ray tracing is conceptually simple, the method critically depends upon an accurate source model in both the near and far field. An overly simplified source model, such as an ideal Lambertian surface substantially detracts from the accuracy and thus benefit of the method. This paper will introduce an improved method of reverse ray tracing that we call Reverse Radiance that avoids assumptions about the source properties. The new method uses measured data from a Source Imaging Goniometer (SIG) that simultaneously measures near and far field luminous data. Incorporating this data into a fast reverse ray tracing integration method yields fast, accurate data for a wide variety of illumination problems.

  4. Pharmacokinetic study of arctigenin in rat plasma and organ tissue by RP-HPLC method.

    PubMed

    He, Fan; Dou, De-Qiang; Hou, Qiang; Sun, Yu; Kang, Ting-Guo

    2013-01-01

    A high-performance liquid chromatography (HPLC) technique was developed for the determination of arctigenin in plasma and various organs of rats after the oral administration of 30, 50 and 70 mgkg(-1) of arctigenin to the Sprague-Dawley rats. Results showed that the validated HPLC method was simple, fast, reproducible and suitable to the determination of arctigenin in rat plasma and organ tissue and one-compartmental model with zero-order absorption process can well describe the changes of arctigenin concentration in the plasma. The concentration of compound was highest in the spleen, less in the liver and the least in the lung. PMID:22404522

  5. Accurate method of modeling cluster scaling relations in modified gravity

    NASA Astrophysics Data System (ADS)

    He, Jian-hua; Li, Baojiu

    2016-06-01

    We propose a new method to model cluster scaling relations in modified gravity. Using a suite of nonradiative hydrodynamical simulations, we show that the scaling relations of accumulated gas quantities, such as the Sunyaev-Zel'dovich effect (Compton-y parameter) and the x-ray Compton-y parameter, can be accurately predicted using the known results in the Λ CDM model with a precision of ˜3 % . This method provides a reliable way to analyze the gas physics in modified gravity using the less demanding and much more efficient pure cold dark matter simulations. Our results therefore have important theoretical and practical implications in constraining gravity using cluster surveys.

  6. HPLC and UPLC methods for the determination of zearalenone in noodles, cereal snacks and infant formula.

    PubMed

    Ok, Hyun Ee; Choi, Sung-Wook; Kim, Meehye; Chun, Hyang Sook

    2014-11-15

    High-performance liquid chromatography (HPLC) and ultra-performance liquid chromatography (UPLC) were compared to validate a method for determination of zearalenone (ZON) in noodles, cereal snacks, and infant formulas. The limits of detection and quantification in HPLC and UPLC were found to be 4.0 and 13.0 μg kg(-1) and 2.5 and 8.3 μg kg(-1), respectively. The average recoveries of ZON by HPLC and UPLC ranged from 79.1% to 105.3% and from 85.1% to 114.5%, respectively. The measurement uncertainties of the two methods for ZON determination were within the maximum standard uncertainty. The two methods showed that the levels of ZON in 163 naturally contaminated samples ranged from 4.3 to 8.3 μg kg(-1) by HPLC and 3.1 to 17.6 μg kg(-1) by UPLC. These findings indicate that either method is suitable for the determination of ZON in noodles, cereal snacks, and infant formulas, but UPLC gives faster results with better sensitivity. PMID:24912723

  7. A SIMPLE HPLC METHOD FOR DETECTING CARBARYL AND 1-NAPHTHOL IN BIOLOGICAL TISSUES.

    EPA Science Inventory

    Carbamates are a class of pesticide used in both agricultural and residential applications. A simple HPLC method for detecting Carb and its metabolite 1-naphthol (Naph) in tissues was developed to try to correlate tissue levels of carbaryl (Carb) (a prototypical carbamate) with c...

  8. A Sensitive RP-HPLC Method for Simultaneous Estimation of Diethylcarbamazine and Levocetirizine in Tablet Formulation

    PubMed Central

    Reddy, J. Mahesh; Jeyaprakash, M. R.; Madhuri, K.; Meyyanathan, S. N.; Elango, K.

    2011-01-01

    A simple, sensitive and reproducible method was developed and validated for the simultaneous estimation of diethylcarbamazine and levocetirizine in its tablet formulation by reverse phase high performance liquid chromatography using Waters1515 HPLC with UV detector at the λmax of 224 nm, using Princeton Sphere-100 C18 (250×4.6 mm. 5 μ) column. The mobile phase used was 20mM potassium dihydrogen orthophosphate buffer (pH: 3.2):acetonitrile (50:50 v/v) with isocratic flow (flow rate 1 ml/min) and the pH was adjusted with orthophosphoric acid. Losartan potassium was used as an internal standard. The compounds diethylcarbamazine, levocetirizine and losartan potassium were eluted at 2.12, 4.27 and 5.96 min, respectively. The peaks were eluted with better resolution. The method was accurate with assay values of 96.32 and 93.04% w/w, precise (%RSD) with intra-day 1.72 and 1.89 and inter-day 1.85 and 1.92, recoveries 102.86 and 101.1% w/w, which are very sensitive with limit of detections (LOD)'s 75, 50 ng/ml and limit of quantification (LOQ)'s 100, 75 ng/ml and linear with R2 values 0.994 in the range of 5 to 30 μg/ml 0.1 to 1 μg/ml for diethylcarbamazine and levocetirizine, respectively. Hence this method can be applied for quantification of different formulations containing diethylcarbamazine and levocetirizine simultaneously. PMID:22457560

  9. A Sensitive RP-HPLC Method for Simultaneous Estimation of Diethylcarbamazine and Levocetirizine in Tablet Formulation.

    PubMed

    Reddy, J Mahesh; Jeyaprakash, M R; Madhuri, K; Meyyanathan, S N; Elango, K

    2011-05-01

    A simple, sensitive and reproducible method was developed and validated for the simultaneous estimation of diethylcarbamazine and levocetirizine in its tablet formulation by reverse phase high performance liquid chromatography using Waters1515 HPLC with UV detector at the λ(max) of 224 nm, using Princeton Sphere-100 C(18) (250×4.6 mm. 5 μ) column. The mobile phase used was 20mM potassium dihydrogen orthophosphate buffer (pH: 3.2):acetonitrile (50:50 v/v) with isocratic flow (flow rate 1 ml/min) and the pH was adjusted with orthophosphoric acid. Losartan potassium was used as an internal standard. The compounds diethylcarbamazine, levocetirizine and losartan potassium were eluted at 2.12, 4.27 and 5.96 min, respectively. The peaks were eluted with better resolution. The method was accurate with assay values of 96.32 and 93.04% w/w, precise (%RSD) with intra-day 1.72 and 1.89 and inter-day 1.85 and 1.92, recoveries 102.86 and 101.1% w/w, which are very sensitive with limit of detections (LOD)'s 75, 50 ng/ml and limit of quantification (LOQ)'s 100, 75 ng/ml and linear with R(2) values 0.994 in the range of 5 to 30 μg/ml 0.1 to 1 μg/ml for diethylcarbamazine and levocetirizine, respectively. Hence this method can be applied for quantification of different formulations containing diethylcarbamazine and levocetirizine simultaneously. PMID:22457560

  10. Development and validation of RP-HPLC method to determine anti-allergic compound in Thai traditional remedy called Benjalokawichien.

    PubMed

    Sakpakdeejaroen, Intouch; Juckmeta, Thana; Itharat, Arunporn

    2014-08-01

    Benjalokawichien (BLW) or Ya-Ha-Rak (HR) is a traditional remedy in the Nationaldrug list of herbal medicinal products AD 2012 of Thailand. For traditional use, BLW is used as antipyretic agent. It also has anti-allergic effect, particularly treating allergic rash. The ethanolic extract of BLW exhibited anti-allergic activity via inhibitory effect against a release ofbeta-hexosaminidase in RBL-2H3 cell line. Pectolinarigenin has been identified as the active compound ofBLW extract. In this study, a reversed-phase high performance liquid chromatography (RP-HPLC) method was developed in order to control quality ofpreparation in three aspects such as chemical fingerprint, quantification and stability of the ethanolic extract. The RP-HPLC was performed with a gradient mobile phase composed of 0.1% ortho phosphoric acid and acetronitrile, and peaks were detected at 331 nm. Based on validation results, this analytical method is precise, accurate and stable for quantitative determination ofpectolinarigenin. The amount ofpectolinarigenin in Benjalokawichien extract determined by this method was 18.50 mg/g ofextract. Therefore, this method could be consideredfor quality control ofBLWextract. PMID:25518297

  11. Accurate optical CD profiler based on specialized finite element method

    NASA Astrophysics Data System (ADS)

    Carrero, Jesus; Perçin, Gökhan

    2012-03-01

    As the semiconductor industry is moving to very low-k1 patterning solutions, the metrology problems facing process engineers are becoming much more complex. Choosing the right optical critical dimension (OCD) metrology technique is essential for bridging the metrology gap and achieving the required manufacturing volume throughput. The critical dimension scanning electron microscope (CD-SEM) measurement is usually distorted by the high aspect ratio of the photoresist and hard mask layers. CD-SEM measurements cease to correlate with complex three-dimensional profiles, such as the cases for double patterning and FinFETs, thus necessitating sophisticated, accurate and fast computational methods to bridge the gap. In this work, a suite of computational methods that complement advanced OCD equipment, and enabling them to operate at higher accuracies, are developed. In this article, a novel method for accurately modeling OCD profiles is presented. A finite element formulation in primal form is used to discretize the equations. The implementation uses specialized finite element spaces to solve Maxwell equations in two dimensions.

  12. Stability-Indicating HPLC Method for Posaconazole Bulk Assay

    PubMed Central

    Garcia, Cássia V.; Costa, Gislaine R.; Mendez, Andreas S. L.

    2012-01-01

    A stability-indicating liquid chromatographic (LC) method was developed for the determination of posaconazole in bulk. Chromatographic separation was achieved using an isocratic elution in a reversed-phase system, with a mobile phase composed of methanol-water (75:25, v/v), at 1.0 mL min−1 flow. Samples were exposed to degradation under thermal, oxidative and acid/basic conditions, and no interference in the analysis was observed. System suitability was evaluated and results were satisfactory (N = 4,900.00 tailing factor 1.04; RSD between injections = 0.65). The retention time of posaconazole was about 8.5 min and the method was validated within the concentration range 5–60 μg mL−1 (r = 0.9996). Adequate results were obtained for repeatability (RSD % = 0.86–1.22), inter-day precision (RSD % = 1.21) and accuracy (98.13% mean recovery). Robustness was also determined to be satisfactory after evaluation. The proposed method was successfully applied to posaconazole bulk quantification, showing the method is useful for determination of the drug in routine analysis. PMID:22896819

  13. Development and Validation of an RP-HPLC Method for Quantitative Estimation of Eslicarbazepine Acetate in Bulk Drug and Tablets

    PubMed Central

    Singh, M.; Kumar, L.; Arora, P.; Mathur, S. C.; Saini, P. K.; Singh, R. M.; Singh, G. N.

    2013-01-01

    A convenient, simple, accurate, precise and reproducible RP-HPLC method was developed and validated for the estimation of eslicarbazepine acetate in bulk drug and tablet dosage form. Objective was achieved under optimised chromatographic conditions on Dionex RP-HPLC system with Dionex C18 column (250×4.6 mm, 5 μm particle size) using mobile phase composed of methanol and ammonium acetate (0.005 M) in the ratio of 70:30 v/v. The separation was achieved using an isocratic elution method with a flow rate of 1.0 ml/ min at room temperature. The effluent was monitored at 230 nm using diode array detector. The retention time of eslicarbazepine acetate is found to be 4.9 min and the standard calibration plot was linear over a concentration range of 10-90 μg/ml with r2=0.9995. The limit of detection and quantification were found to be 3.144 and 9.52 μg/ml, respectively. The amount of eslicarbazepine acetate in bulk and tablet dosage form was found to be 99.19 and 97.88%, respectively. The method was validated statistically using the percent relative standard deviation and the values are found to be within the limits. The recovery studies were performed and the percentage recoveries were found to be 98.33± 0.5%. PMID:24591752

  14. Development and Validation of an RP-HPLC Method for Quantitative Estimation of Eslicarbazepine Acetate in Bulk Drug and Tablets.

    PubMed

    Singh, M; Kumar, L; Arora, P; Mathur, S C; Saini, P K; Singh, R M; Singh, G N

    2013-11-01

    A convenient, simple, accurate, precise and reproducible RP-HPLC method was developed and validated for the estimation of eslicarbazepine acetate in bulk drug and tablet dosage form. Objective was achieved under optimised chromatographic conditions on Dionex RP-HPLC system with Dionex C18 column (250×4.6 mm, 5 μm particle size) using mobile phase composed of methanol and ammonium acetate (0.005 M) in the ratio of 70:30 v/v. The separation was achieved using an isocratic elution method with a flow rate of 1.0 ml/ min at room temperature. The effluent was monitored at 230 nm using diode array detector. The retention time of eslicarbazepine acetate is found to be 4.9 min and the standard calibration plot was linear over a concentration range of 10-90 μg/ml with r(2)=0.9995. The limit of detection and quantification were found to be 3.144 and 9.52 μg/ml, respectively. The amount of eslicarbazepine acetate in bulk and tablet dosage form was found to be 99.19 and 97.88%, respectively. The method was validated statistically using the percent relative standard deviation and the values are found to be within the limits. The recovery studies were performed and the percentage recoveries were found to be 98.33± 0.5%. PMID:24591752

  15. HPLC METHOD DEVELOPMENT, VALIDATION AND IMPURITY CHARACTERIZATION FOR AN ANTITUMOR HSP90 INHIBITOR -- PU-H71 (NSC 750424)

    PubMed Central

    Liu, Mingtao; Wang, Jennie; Wu, Xiaogang; Wang, Euphemia; Baptista, Diego; Scott, Brendan; Liu, Paul

    2013-01-01

    An HPLC method for the assay of the heat shock protein 90 inhibitor, PU-H71 (NSC 750424), has been developed and validated. The stress testing of PU-H71 was carried out in accordance with ICH guidelines Q1A (R2) under aqueous, acidic, alkaline, oxidative, thermolytic and photolytic conditions. The separation of PU-H71 from its impurities and degradation products was achieved within 50 min on a Mac-Mod ACE 3 C18 column (150 mm × 4.6 mm i.d., 3 μm) with a gradient mobile phase comprising 20–95% acetonitrile in water, with 0.1% trifluroacetic acid in both phases. LC - Quadruple TOF/MS was used to obtain accurate mass data on various components as well as on their fragments for characterization of impurities and degradation products. The proposed HPLC assay method was validated for specificity, linearity (concentration range 0.1–0.3 mg/mL, r ≥ 0.9998), accuracy (recovery 99.7–101.1%), precision (intra-lab RSD ≤ 1.39%, inter-lab RSD ≤ 0.91%), sensitivity (LOD 0.08 μg/mL), and ruggedness. The developed method was suitable for the assay and stability monitoring of PU-H71 drug substance. PMID:24252723

  16. HPLC method development, validation and impurity characterization for an antitumor Hsp90 inhibitor-PU-H71 (NSC 750424).

    PubMed

    Liu, Mingtao; Wang, Jennie; Wu, Xiaogang; Wang, Euphemia; Baptista, Diego; Scott, Brendan; Liu, Paul

    2014-02-01

    An HPLC method for the assay of the heat shock protein 90 inhibitor, PU-H71 (NSC 750424), has been developed and validated. The stress testing of PU-H71 was carried out in accordance with ICH guidelines Q1A (R2) under aqueous, acidic, alkaline, oxidative, thermolytic and photolytic conditions. The separation of PU-H71 from its impurities and degradation products was achieved within 50min on a Mac-Mod ACE 3 C18 column (150mm×4.6mm i.d., 3μm) with a gradient mobile phase comprising 20-95% acetonitrile in water, with 0.1% trifluroacetic acid in both phases. LC-quadrupole TOF/MS was used to obtain accurate mass data on various components as well as on their fragments for characterization of impurities and degradation products. The proposed HPLC assay method was validated for specificity, linearity (concentration range 0.1-0.3mg/mL, r≥0.9998), accuracy (recovery 99.7-101.1%), precision (intra-lab RSD≤1.39%, inter-lab RSD≤0.91%), sensitivity (LOD 0.08μg/mL), and ruggedness. The developed method was suitable for the assay and stability monitoring of PU-H71 drug substance. PMID:24252723

  17. Novel dispersion tolerant interferometry method for accurate measurements of displacement

    NASA Astrophysics Data System (ADS)

    Bradu, Adrian; Maria, Michael; Leick, Lasse; Podoleanu, Adrian G.

    2015-05-01

    We demonstrate that the recently proposed master-slave interferometry method is able to provide true dispersion free depth profiles in a spectrometer-based set-up that can be used for accurate displacement measurements in sensing and optical coherence tomography. The proposed technique is based on correlating the channelled spectra produced by the linear camera in the spectrometer with previously recorded masks. As such technique is not based on Fourier transformations (FT), it does not require any resampling of data and is immune to any amounts of dispersion left unbalanced in the system. In order to prove the tolerance of technique to dispersion, different lengths of optical fiber are used in the interferometer to introduce dispersion and it is demonstrated that neither the sensitivity profile versus optical path difference (OPD) nor the depth resolution are affected. In opposition, it is shown that the classical FT based methods using calibrated data provide less accurate optical path length measurements and exhibit a quicker decays of sensitivity with OPD.

  18. Accurate camera calibration method specialized for virtual studios

    NASA Astrophysics Data System (ADS)

    Okubo, Hidehiko; Yamanouchi, Yuko; Mitsumine, Hideki; Fukaya, Takashi; Inoue, Seiki

    2008-02-01

    Virtual studio is a popular technology for TV programs, that makes possible to synchronize computer graphics (CG) to realshot image in camera motion. Normally, the geometrical matching accuracy between CG and realshot image is not expected so much on real-time system, we sometimes compromise on directions, not to come out the problem. So we developed the hybrid camera calibration method and CG generating system to achieve the accurate geometrical matching of CG and realshot on virtual studio. Our calibration method is intended for the camera system on platform and tripod with rotary encoder, that can measure pan/tilt angles. To solve the camera model and initial pose, we enhanced the bundle adjustment algorithm to fit the camera model, using pan/tilt data as known parameters, and optimizing all other parameters invariant against pan/tilt value. This initialization yields high accurate camera position and orientation consistent with any pan/tilt values. Also we created CG generator implemented the lens distortion function with GPU programming. By applying the lens distortion parameters obtained by camera calibration process, we could get fair compositing results.

  19. Accurate finite difference methods for time-harmonic wave propagation

    NASA Technical Reports Server (NTRS)

    Harari, Isaac; Turkel, Eli

    1994-01-01

    Finite difference methods for solving problems of time-harmonic acoustics are developed and analyzed. Multidimensional inhomogeneous problems with variable, possibly discontinuous, coefficients are considered, accounting for the effects of employing nonuniform grids. A weighted-average representation is less sensitive to transition in wave resolution (due to variable wave numbers or nonuniform grids) than the standard pointwise representation. Further enhancement in method performance is obtained by basing the stencils on generalizations of Pade approximation, or generalized definitions of the derivative, reducing spurious dispersion, anisotropy and reflection, and by improving the representation of source terms. The resulting schemes have fourth-order accurate local truncation error on uniform grids and third order in the nonuniform case. Guidelines for discretization pertaining to grid orientation and resolution are presented.

  20. HPLC Method for Simultaneous Quantitative Detection of Quercetin and Curcuminoids in Traditional Chinese Medicines

    PubMed Central

    Ang, Lee Fung; Yam, Mun Fei; Fung, Yvonne Tan Tze; Kiang, Peh Kok; Darwin, Yusrida

    2014-01-01

    Objectives: Quercetin and curcuminoids are important bioactive compounds found in many herbs. Previously reported high performance liquid chromatography ultraviolet (HPLC-UV) methods for the detection of quercetin and curcuminoids have several disadvantages, including unsatisfactory separation times and lack of validation according the standard guidelines of the International Conference on Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use. Methods: A rapid, specific, reversed phase, HPLC-UV method with an isocratic elution of acetonitrile and 2% v/v acetic acid (40% : 60% v/v) (pH 2.6) at a flow rate of 1.3 mL/minutes, a column temperature of 35°C, and ultraviolet (UV) detection at 370 nm was developed. The method was validated and applied to the quantification of different types of market available Chinese medicine extracts, pills and tablets. Results: The method allowed simultaneous determination of quercetin, bisdemethoxycurcumin, demethoxycurcumin and curcumin in the concentration ranges of 0.00488 ─ 200 μg/mL, 0.625 ─ 320 μg/mL, 0.07813 ─ 320 μg/mL and 0.03906 ─ 320 μg/mL, respectively. The limits of detection and quantification, respectively, were 0.00488 and 0.03906 μg/mL for quercetin, 0.62500 and 2.50000 μg/mL for bisdemethoxycurcumin, 0.07813 and 0.31250 μg/mL for demethoxycurcumin, and 0.03906 and 0.07813 μg/mL for curcumin. The percent relative intra day standard deviation (% RSD) values were 0.432 ─ 0.806 μg/mL, 0.576 ─ 0.723 μg/mL, 0.635 ─ 0.752 μg/mL and 0.655 ─ 0.732 μg/mL for quercetin, bisdemethoxycurcumin, demethoxycurcumin and curcumin, respectively, and those for intra day precision were 0.323 ─ 0.968 μg/mL, 0.805 ─ 0.854 μg/mL, 0.078 ─ 0.844 μg/mL and 0.275 ─ 0.829 μg/mL, respectively. The intra day accuracies were 99.589% ─ 100.821%, 98.588% ─ 101.084%, 9.289% ─ 100.88%, and 98.292% ─ 101.022% for quercetin, bisdemethoxycurcumin, demethoxycurcumin and

  1. Development and Validation of an HPLC Method for Simultaneous Determination of Rifampicin, Isoniazid, Pyrazinamide, and Ethambutol Hydrochloride in Pharmaceutical Formulations.

    PubMed

    Chellini, Paula R; Lages, Eduardo B; Franco, Pedro H C; Nogueira, Fernando H A; César, Isabela C; Pianetti, Gerson A

    2015-01-01

    Tuberculosis treatment consists of a fixed dose combination of rifampicin (RIF), isoniazid (INH), pyrazinamide (PYZ), and ethambutol hydrochloride (EMB). The combined treatment using various drugs is necessary for patient curing, without recrudescence, and for prevention of drug-resistant mutants, which may occur during treatment. An HPLC-diode array detector (DAD) method for the simultaneous determination of RIF, INH, PYZ, and EMB in fixed dose combination tablets was developed and validated. Chromatographic experiments were performed on an Agilent 1200 HPLC system, and the separation was carried out on a Purospher STAR RP18e (250×4.6 mm id, 5 μm, Merck) analytical column. Gradient elution was carried out with a mobile phase of 20 mM monobasic sodium phosphate buffer with 0.2% triethylamine (pH 7.0) and acetonitrile at a flow rate of 1.5 mL/min. The total run time was 12 min, and the re-equilibration time was 5 min. EMB detection was performed at 210 nm, and RIF, INH, and PYZ were detected at 238 nm, using a DAD. The method proved to be specific, linear (r2>0.99), precise (RSD<2%), accurate, and robust and may be applied to the QC analysis of pharmaceutical formulations. PMID:26525241

  2. An Accurate Projector Calibration Method Based on Polynomial Distortion Representation

    PubMed Central

    Liu, Miao; Sun, Changku; Huang, Shujun; Zhang, Zonghua

    2015-01-01

    In structure light measurement systems or 3D printing systems, the errors caused by optical distortion of a digital projector always affect the precision performance and cannot be ignored. Existing methods to calibrate the projection distortion rely on calibration plate and photogrammetry, so the calibration performance is largely affected by the quality of the plate and the imaging system. This paper proposes a new projector calibration approach that makes use of photodiodes to directly detect the light emitted from a digital projector. By analyzing the output sequence of the photoelectric module, the pixel coordinates can be accurately obtained by the curve fitting method. A polynomial distortion representation is employed to reduce the residuals of the traditional distortion representation model. Experimental results and performance evaluation show that the proposed calibration method is able to avoid most of the disadvantages in traditional methods and achieves a higher accuracy. This proposed method is also practically applicable to evaluate the geometric optical performance of other optical projection system. PMID:26492247

  3. Accurate Evaluation Method of Molecular Binding Affinity from Fluctuation Frequency

    NASA Astrophysics Data System (ADS)

    Hoshino, Tyuji; Iwamoto, Koji; Ode, Hirotaka; Ohdomari, Iwao

    2008-05-01

    Exact estimation of the molecular binding affinity is significantly important for drug discovery. The energy calculation is a direct method to compute the strength of the interaction between two molecules. This energetic approach is, however, not accurate enough to evaluate a slight difference in binding affinity when distinguishing a prospective substance from dozens of candidates for medicine. Hence more accurate estimation of drug efficacy in a computer is currently demanded. Previously we proposed a concept of estimating molecular binding affinity, focusing on the fluctuation at an interface between two molecules. The aim of this paper is to demonstrate the compatibility between the proposed computational technique and experimental measurements, through several examples for computer simulations of an association of human immunodeficiency virus type-1 (HIV-1) protease and its inhibitor (an example for a drug-enzyme binding), a complexation of an antigen and its antibody (an example for a protein-protein binding), and a combination of estrogen receptor and its ligand chemicals (an example for a ligand-receptor binding). The proposed affinity estimation has proven to be a promising technique in the advanced stage of the discovery and the design of drugs.

  4. A stability-indicating HPLC method for medroxyprogesterone acetate in bulk drug and injection formulation.

    PubMed

    Burana-Osot, Jankana; Ungboriboonpisal, Sooksri; Sriphong, Lawan

    2006-03-18

    A stability-indicating HPLC assay method has been developed and validated for medroxyprogesterone acetate (MPA) in bulk drug and injectable suspension. An isocratic RP-HPLC was achieved on a Hichrom C(18) column (150 mm x 4.6mm i.d., 5 microm) utilizing a mobile phase of methanol 0.020 M acetate buffer pH 5 (65:35, v/v) and a photodiode array detector at 245 nm. The stress testing of MPA was carried out under acidic and alkaline hydrolysis, and oxidation conditions. MPA was well resolved from its degradation products, a main related substance (megestrol acetate) and two preservatives (methyl paraben and propyl paraben) with the resolution >or=2. The proposed method was validated for selectivity, linearity, accuracy, precision and solution stability. The method was found to be suitable for the quality control of MPA in bulk drug and injections as well as the stability-indicating studies. PMID:16242876

  5. An Integrative Method for Accurate Comparative Genome Mapping

    PubMed Central

    Swidan, Firas; Rocha, Eduardo P. C; Shmoish, Michael; Pinter, Ron Y

    2006-01-01

    We present MAGIC, an integrative and accurate method for comparative genome mapping. Our method consists of two phases: preprocessing for identifying “maximal similar segments,” and mapping for clustering and classifying these segments. MAGIC's main novelty lies in its biologically intuitive clustering approach, which aims towards both calculating reorder-free segments and identifying orthologous segments. In the process, MAGIC efficiently handles ambiguities resulting from duplications that occurred before the speciation of the considered organisms from their most recent common ancestor. We demonstrate both MAGIC's robustness and scalability: the former is asserted with respect to its initial input and with respect to its parameters' values. The latter is asserted by applying MAGIC to distantly related organisms and to large genomes. We compare MAGIC to other comparative mapping methods and provide detailed analysis of the differences between them. Our improvements allow a comprehensive study of the diversity of genetic repertoires resulting from large-scale mutations, such as indels and duplications, including explicitly transposable and phagic elements. The strength of our method is demonstrated by detailed statistics computed for each type of these large-scale mutations. MAGIC enabled us to conduct a comprehensive analysis of the different forces shaping prokaryotic genomes from different clades, and to quantify the importance of novel gene content introduced by horizontal gene transfer relative to gene duplication in bacterial genome evolution. We use these results to investigate the breakpoint distribution in several prokaryotic genomes. PMID:16933978

  6. Stability-indicating HPLC method for the determination of darunavir ethanolate.

    PubMed

    Reddy, B V Rami; Jyothi, G; Reddy, B S; Raman, N V V S S; Reddy, K Subhash Chander; Rambabu, C

    2013-01-01

    A novel stability-indicating reversed-phase high-performance liquid chromatographic (HPLC) method has been developed for the quantitative determination of darunavir ethanolate, an HIV-1 protease inhibitor. The chromatographic separation was achieved using an X-Bridge C18 (150 × 4.6 mm × 3.5 µm) HPLC column in isocratic mode employing 0.01M ammonium formate (pH.3.0) buffer and acetonitrile in the ratio of 55:45 (v/v) with a flow rate of 1.0 mL/min. The detector wavelength was monitored at 265 nm and the column temperature was maintained at 30°C. Darunavir ethanolate was exposed to thermal, photolytic, acid, base and oxidative stress conditions. Considerable degradation of the drug substance was found to occur under acid, base and oxidative stress conditions. The peak homogeneity data of darunavir ethanolate obtained by photodiode array detection demonstrated the specificity of the method in the presence of degradants. The degradation products were well resolved from primary peak of darunavir, indicating that the method is specific and stability-indicating. The HPLC method was validated as per International Conference on Harmonization guidelines with respect to specificity, precision, linearity, accuracy and robustness. Regression analysis showed a correlation coefficient value greater than 0.999. The accuracy of the method was established based on the recovery obtained for darunavir ethanolate. PMID:23097581

  7. Fingerprint analysis of polysaccharides from different Ganoderma by HPLC combined with chemometrics methods.

    PubMed

    Sun, Xiaomei; Wang, Haohao; Han, Xiaofeng; Chen, Shangwei; Zhu, Song; Dai, Jun

    2014-12-19

    A fingerprint analysis method has been developed for characterization and discrimination of polysaccharides from different Ganoderma by high performance liquid chromatography (HPLC) coupled with chemometrics means. The polysaccharides were extracted under ultrasonic-assisted condition, and then partly hydrolyzed with trifluoroacetic acid. Monosaccharides and oligosaccharides in the hydrolyzates were subjected to pre-column derivatization with 1-phenyl-3-methyl-5-pyrazolone and HPLC analysis, which will generate unique fingerprint information related to chemical composition and structure of polysaccharides. The peak data were imported to professional software in order to obtain standard fingerprint profiles and evaluate similarity of different samples. Meanwhile, the data were further processed by hierarchical cluster analysis and principal component analysis. Polysaccharides from different parts or species of Ganoderma or polysaccharides from the same parts of Ganoderma but from different geographical regions or different strains could be differentiated clearly. This fingerprint analysis method can be applied to identification and quality control of different Ganoderma and their products. PMID:25263911

  8. A novel RP-HPLC method for the detection and quantification of roxithromycin in topical delivery studies.

    PubMed

    Aucamp, M E; Csongradi, C; Gerber, M; Du Plessis, J

    2016-04-01

    A novel HPLC method with UV detection for the identification and quantification of roxithromycin (ROX) during in vitro skin penetration studies has been developed and validated. The method proved to be simple and rapid with isocratic elution (flow rate: 1.0 mL/min) of ROX, using a C18 column and UV detection at 205 nm. The mobile phase consisted of 0.06 M potassium di-hydrogen orthophosphate buffer (pH adjusted to 7.4 with sodium hydroxide) and acetonitrile in a 50:50 (v/v) ratio. This method showed linearity across the concentration range of 5 - 1000 μg/mL with a correlation coefficient of 0.9999. An average recovery of 101.78% was obtained. Limit of detection (LOD) and lower limit of quantification (LLOQ) values proved that ROX can still be detected at a concentration level of 0.3 μg/mL and accurately quantified at a concentration of 0.5 μg/mL. The specificity testing during method validation proved that this method is suitable for the accurate detection and quantification of ROX even when combined with different compounds typically used during the formulation of topical delivery systems. PMID:27209694

  9. Development of an HPLC method for determination of pentachloronitrobenzene, hexachlorobenzene and their possible metabolites

    PubMed Central

    2011-01-01

    Background Pentachloronitrobenzene (PCNB) and hexachlorobenzene (HCB) are highly toxic and widespread in every environmental compartment. Some of metabolic products such as amino/nitro containing chlorinated aromatic compounds can be determined by gas chromatography coupled with electron capture detector (GC-ECD). However, it is difficult to identify some of chlorophenolic and chloroquinolic intermediates produced from PCNB and HCB by the above mentioned technique. Therefore, for analysis of these compounds and their metabolites, we have developed a high performance liquid chromatography (HPLC) based method. Results The extraction of PCNB and HCB from soil and minimal salt medium was carried out with ethyl acetate and hexane respectively with good recoveries (98% for PCNB and 97% for HCB). The validation of the proposed extraction and HPLC method was done by analysis of PCNB and HCB biodegradation and their metabolites identification from anaerobic enriched soil samples. Conclusion A rapid, sensitive and simple HPLC based analytical method was developed for the analysis of PCNB, HCB and their possible intermediates. PMID:22112041

  10. Size-exclusion HPLC as a sensitive and calibrationless method for complex peptide mixtures quantification.

    PubMed

    Bodin, Alice; Framboisier, Xavier; Alonso, Dominique; Marc, Ivan; Kapel, Romain

    2015-12-01

    This work describes an original methodology to quantify complex peptide mixtures by size-exclusion high-performance liquid chromatography (SE-HPLC). The methodology was first tested on simulated elutions of peptide mixtures. For this set of experiments, a good estimation of the total peptide concentration was observed (error less than 10 %). Then 30 fractions obtained by ultrafiltration of hydrolysates from two different sources were titrated by Kjeldahl or BCA analysis and analysed by SE-HPLC for an experimental validation of the methodology. Very good matchs between methods were obtained. The linear working range depends on the hydrolysate but is generally between 0.2 and 4gL(-1) (i.e. between 10 and 200μg). Moreover, the presence of organic solvents or salts in samples does not impact the accuracy of the methodology contrary to common quantification methods. Hence, the findings of this study show that total concentration of complex peptide mixture can be efficiently determinate by the proposed methodology using simple SE-HPLC analysis. PMID:26523666

  11. IRIS: Towards an Accurate and Fast Stage Weight Prediction Method

    NASA Astrophysics Data System (ADS)

    Taponier, V.; Balu, A.

    2002-01-01

    The knowledge of the structural mass fraction (or the mass ratio) of a given stage, which affects the performance of a rocket, is essential for the analysis of new or upgraded launchers or stages, whose need is increased by the quick evolution of the space programs and by the necessity of their adaptation to the market needs. The availability of this highly scattered variable, ranging between 0.05 and 0.15, is of primary importance at the early steps of the preliminary design studies. At the start of the staging and performance studies, the lack of frozen weight data (to be obtained later on from propulsion, trajectory and sizing studies) leads to rely on rough estimates, generally derived from printed sources and adapted. When needed, a consolidation can be acquired trough a specific analysis activity involving several techniques and implying additional effort and time. The present empirical approach allows thus to get approximated values (i.e. not necessarily accurate or consistent), inducing some result inaccuracy as well as, consequently, difficulties of performance ranking for a multiple option analysis, and an increase of the processing duration. This forms a classical harsh fact of the preliminary design system studies, insufficiently discussed to date. It appears therefore highly desirable to have, for all the evaluation activities, a reliable, fast and easy-to-use weight or mass fraction prediction method. Additionally, the latter should allow for a pre selection of the alternative preliminary configurations, making possible a global system approach. For that purpose, an attempt at modeling has been undertaken, whose objective was the determination of a parametric formulation of the mass fraction, to be expressed from a limited number of parameters available at the early steps of the project. It is based on the innovative use of a statistical method applicable to a variable as a function of several independent parameters. A specific polynomial generator

  12. A Simple, Fast, Low Cost, HPLC/UV Validated Method for Determination of Flutamide: Application to Protein Binding Studies

    PubMed Central

    Esmaeilzadeh, Sara; Valizadeh, Hadi; Zakeri-Milani, Parvin

    2016-01-01

    Purpose: The main goal of this study was development of a reverse phase high performance liquid chromatography (RP-HPLC) method for flutamide quantitation which is applicable to protein binding studies. Methods: Ultrafilteration method was used for protein binding study of flutamide. For sample analysis, flutamide was extracted by a simple and low cost extraction method using diethyl ether and then was determined by HPLC/UV. Acetanilide was used as an internal standard. The chromatographic system consisted of a reversed-phase C8 column with C8 pre-column, and the mobile phase of a mixture of 29% (v/v) methanol, 38% (v/v) acetonitrile and 33% (v/v) potassium dihydrogen phosphate buffer (50 mM) with pH adjusted to 3.2. Results: Acetanilide and flutamide were eluted at 1.8 and 2.9 min, respectively. The linearity of method was confirmed in the range of 62.5-16000 ng/ml (r2 > 0.99). The limit of quantification was shown to be 62.5 ng/ml. Precision and accuracy ranges found to be (0.2-1.4%, 90-105%) and (0.2-5.3 %, 86.7-98.5 %) respectively. Acetanilide and flutamide capacity factor values of 1.35 and 2.87, tailing factor values of 1.24 and 1.07 and resolution values of 1.8 and 3.22 were obtained in accordance with ICH guidelines. Conclusion: Based on the obtained results a rapid, precise, accurate, sensitive and cost-effective analysis procedure was proposed for quantitative determination of flutamide. PMID:27478788

  13. Development and validation of a rapid stability indicating HPLC-method using monolithic stationary phase and two spectrophotometric methods for determination of antihistaminic acrivastine in capsules

    NASA Astrophysics Data System (ADS)

    Gouda, Ayman A.; Hashem, Hisham; Jira, Thomas

    2014-09-01

    Simple, rapid and accurate high performance liquid chromatographic (HPLC) and spectrophotometric methods are described for determination of antihistaminic acrivastine in capsules. The first method (method A) is based on accurate, sensitive and stability indicating chromatographic separation method. Chromolith® Performance RP-18e column, a relatively new packing material consisting of monolithic rods of highly porous silica, was used as stationary phase applying isocratic binary mobile phase of ACN and 25 mM NaH2PO4 pH 4.0 in the ratio of 22.5:77.5 at flow rate of 5.0 mL/min and 40 °C. A diode array detector was used at 254 nm for detection. The elution time of acrivastine was found to be 2.080 ± 0.032. The second and third methods (methods B and C) are based on the oxidation of acrivastine with excess N-bromosuccinimide (NBS) and determination of the unconsumed NBS with, metol-sulphanilic acid (λmax: 520 nm) or amaranth dye (λmax: 530 nm). The reacted oxidant corresponds to the drug content. Beer’s law is obeyed over the concentration range 1.563-50, 2.0-20 and 1.0-10 μg mL-1 for methods A, B and C, respectively. The limits of detection and quantitation were 0.40, 0.292 and 0.113 μg mL-1 and 0.782, 0.973 and 0.376 μg mL-1 for methods A, B and C, respectively. The HPLC method was validated for system suitability, linearity, precision, limits of detection and quantitation, specificity, stability and robustness. Stability tests were done through exposure of the analyte solution for four different stress conditions and the results indicate no interference of degradants with HPLC-method. The proposed methods was favorably applied for determination of acrivastine in capsules formulation. Statistical comparison of the obtained results from the analysis of the studied drug to those of the reported method using t- and F-tests showed no significant difference between them.

  14. Development and validation of a rapid stability indicating HPLC-method using monolithic stationary phase and two spectrophotometric methods for determination of antihistaminic acrivastine in capsules.

    PubMed

    Gouda, Ayman A; Hashem, Hisham; Jira, Thomas

    2014-09-15

    Simple, rapid and accurate high performance liquid chromatographic (HPLC) and spectrophotometric methods are described for determination of antihistaminic acrivastine in capsules. The first method (method A) is based on accurate, sensitive and stability indicating chromatographic separation method. Chromolith® Performance RP-18e column, a relatively new packing material consisting of monolithic rods of highly porous silica, was used as stationary phase applying isocratic binary mobile phase of ACN and 25 mM NaH2PO4 pH 4.0 in the ratio of 22.5:77.5 at flow rate of 5.0 mL/min and 40°C. A diode array detector was used at 254 nm for detection. The elution time of acrivastine was found to be 2.080±0.032. The second and third methods (methods B and C) are based on the oxidation of acrivastine with excess N-bromosuccinimide (NBS) and determination of the unconsumed NBS with, metol-sulphanilic acid (λmax: 520 nm) or amaranth dye (λmax: 530 nm). The reacted oxidant corresponds to the drug content. Beer's law is obeyed over the concentration range 1.563-50, 2.0-20 and 1.0-10 μg mL(-1) for methods A, B and C, respectively. The limits of detection and quantitation were 0.40, 0.292 and 0.113 μg mL(-1) and 0.782, 0.973 and 0.376 μg mL(-1) for methods A, B and C, respectively. The HPLC method was validated for system suitability, linearity, precision, limits of detection and quantitation, specificity, stability and robustness. Stability tests were done through exposure of the analyte solution for four different stress conditions and the results indicate no interference of degradants with HPLC-method. The proposed methods was favorably applied for determination of acrivastine in capsules formulation. Statistical comparison of the obtained results from the analysis of the studied drug to those of the reported method using t- and F-tests showed no significant difference between them. PMID:24813276

  15. Development and validation of a modified ultrasound-assisted extraction method and a HPLC method for the quantitative determination of two triterpenic acids in Hedyotis diffusa.

    PubMed

    Yang, Yu-Chiao; Wei, Ming-Chi; Chiu, Hui-Fen; Huang, Ting-Chia

    2013-12-01

    In the present study, the oleanolic acid (OA) and ursolic acid (UA) contents ofHedyotis diffusa and H. corymbosa were determined by a rapid, selective and accurate method combining modified ultrasound-assisted extraction (MUAE) and HPLC. Compared with traditional extraction methods, MUAE reduced the extraction time, the extraction temperature and the solvent consumption and maximized the extraction yields of OA and UA. Furthermore, the combined MUAE-HPLC method was applied to quantitate OA and UA in plant samples and exhibited good repeatability, reproducibility and stability. The mean recovery studies (one extraction cycle) for OA and UA were between 91.3 and 91.7% with RSD values less than 4.5%. The pioneer method was further applied to quantitate OA and UA in six samples of H. diffusa and five samples of H. corymbosa. The results showed that the OA and UA content in the samples from different sources were significantly different. This report is valuable for the application of H. diffusa and H. corymbosa obtained from different regions in clinical research and pharmacology. PMID:24555272

  16. Double-salting out assisted liquid-liquid extraction (SALLE) HPLC method for estimation of temozolomide from biological samples.

    PubMed

    Jain, Darshana; Athawale, Rajani; Bajaj, Amrita; Shrikhande, Shruti

    2014-11-01

    0.47-20 μg/ml. The LOQ and LOD for the developed method were 0.4 μg/ml and 0.1 μg/ml, respectively. Thus, plasma non-interfering SALLE-HPLC method that is precise, robust, accurate, specific and cost effective for estimation of temozolomide from plasma samples was developed and validated. PMID:25240926

  17. Development and Validation of HPLC and HPTLC Methods for Determination of Cefoperazone and Its Related Impurities.

    PubMed

    Abdelaleem, Eglal A; Naguib, Ibrahim A; Zaazaa, Hala E; Hussein, Essraa A

    2016-02-01

    Validated sensitive and highly selective methods were developed for the quantitative determination of cefoperazone sodium (CEF) in the presence of its reported impurities; 7-aminocephalosporanic acid (7-ACA) and 5-mercapto-1-methyl-tetrazole (5-MER). Method A is high-performance liquid chromatography (HPLC), where the mixture of CEF and the reported impurities; 7-ACA and 5-MER were separated on a C8 column (5 µm ps, 250 mm × 4.6 i.d.) using methanol:0.05 M KH2PO4 buffer (22.5:77.5 v/v, pH 7.5) as a mobile phase. The three components were detected at 254 nm with a concentration range of 10-90 µg mL(-1) and the mean percentage recovery 99.67% (SD 1.465). Method B is high-performance thin layer chromatography (HPTLC), where the mixture of CEF and the reported impurities were separated on silica gel HPTLC F254 plates using (acetone:methanol:ethyl acetate:2% sodium lauryl sulfate:glacial acetic acid) (3:2:3:0.8:0.2, by volume) as a developing system and scanning at 254 nm over a concentration range of 1-10 µg per band with the mean percentage recovery 99.95% (SD 1.335). The proposed methods were statistically compared with a reported HPLC method with no significant difference regarding accuracy and precision; indicating the ability of the proposed methods to be reliable and suitable for routine analysis of drug product. The proposed HPTLC method proved to be more sensitive, while the HPLC gave more reproducible results besides saving time. PMID:26306573

  18. A comparative study for PSP toxins quantification by using MBA and HPLC official methods in shellfish.

    PubMed

    Ben-Gigirey, B; Rodríguez-Velasco, M L; Otero, A; Vieites, J M; Cabado, A G

    2012-10-01

    Commission Regulation (EC) N° 2074/2005 recognises the biological method as the reference method for Paralytic Shellfish Poisoning (PSP) toxins detection in molluscs. It was amended by Commission Regulation (EC) N° 1664/2006 that accepted the so-called Lawrence method as an alternative to the reference method. The goal of this study was to compare AOAC Official Methods of Analysis 959.08 (Biological method) and 2005.06 (Prechromatographic Oxidation and Liquid Chromatography with fluorescence detection) in samples with different toxin profiles. The influence of extraction solvent in the total samples toxicity was also evaluated. A total of 40 samples including mussels, clams, scallops, razor-clams, cockles, oysters and barnacles were analysed by both official methods. Samples were selected with Alexandrium and Gymnodinium toxic profiles, from different origin and including several presentations: fresh, frozen, canned and boiled. Acetic and hydrochloric acid extractions were performed in all samples and the extracts were simultaneously analysed by both methods. Most samples were naturally contaminated and two samples were spiked. Comparison of both official methods, mouse bioassay (MBA) with HCl extraction and Liquid Chromatography with fluorescence detection (HPLC-FLD) with acetic acid extraction, led to an 85% of consistent results regarding compliance with legal limit, including samples below and above it. The linear correlation coefficient was r² = 0.69 and the paired t test (two tails, α = 0.05) indicated that there were not significant differences among both sets of data. Nevertheless, toxicity differences were found in several samples. In 15 out of 18 shellfish with a Gymnodinium toxic profile, higher toxicity levels were obtained by MBA. This fact was more evident in 7 samples, partially related to the lack of standards and the impossibility of analysing dc-NEO, C1, 2 and GTX6 at the beginning of the study. However, other factors concerning the extraction

  19. Quantifying Methane Fluxes Simply and Accurately: The Tracer Dilution Method

    NASA Astrophysics Data System (ADS)

    Rella, Christopher; Crosson, Eric; Green, Roger; Hater, Gary; Dayton, Dave; Lafleur, Rick; Merrill, Ray; Tan, Sze; Thoma, Eben

    2010-05-01

    Methane is an important atmospheric constituent with a wide variety of sources, both natural and anthropogenic, including wetlands and other water bodies, permafrost, farms, landfills, and areas with significant petrochemical exploration, drilling, transport, or processing, or refining occurs. Despite its importance to the carbon cycle, its significant impact as a greenhouse gas, and its ubiquity in modern life as a source of energy, its sources and sinks in marine and terrestrial ecosystems are only poorly understood. This is largely because high quality, quantitative measurements of methane fluxes in these different environments have not been available, due both to the lack of robust field-deployable instrumentation as well as to the fact that most significant sources of methane extend over large areas (from 10's to 1,000,000's of square meters) and are heterogeneous emitters - i.e., the methane is not emitted evenly over the area in question. Quantifying the total methane emissions from such sources becomes a tremendous challenge, compounded by the fact that atmospheric transport from emission point to detection point can be highly variable. In this presentation we describe a robust, accurate, and easy-to-deploy technique called the tracer dilution method, in which a known gas (such as acetylene, nitrous oxide, or sulfur hexafluoride) is released in the same vicinity of the methane emissions. Measurements of methane and the tracer gas are then made downwind of the release point, in the so-called far-field, where the area of methane emissions cannot be distinguished from a point source (i.e., the two gas plumes are well-mixed). In this regime, the methane emissions are given by the ratio of the two measured concentrations, multiplied by the known tracer emission rate. The challenges associated with atmospheric variability and heterogeneous methane emissions are handled automatically by the transport and dispersion of the tracer. We present detailed methane flux

  20. A gradient based facile HPLC method for simultaneous estimation of antioxidants extracted from tea powder.

    PubMed

    Nanjegowda, Shankara H; Papanna, Manasa G; Achar, Raghu Ram; Rangappa, Kanchugarakoppal S; Mallu, Puttaswamappa; Swamy, Shivananju Nanjunda

    2016-05-01

    A new simple, rapid and precise RP-HPLC method was developed for the extraction and quantitative estimation of caffeine (C), (-)-epigallocatechin gallate (EGCG), (+)-catechin(Ct), (-)-epicatechin(EC), and (-)-epicatechin gallate (ECG) (collectively named as Tea Powder Bioactives TPBAs) extracted from tea powder using different ratios of ethanol: water. The simultaneous determination of TPBAs was performed using the UV spectrophotometric method which employs the absorbance at 205 nm (λmax of caffeine and polyphenols). This method is a gradient based HPLC method with a flow rate of 0.8 mL/min using Inertsil ODS 100 × 4.6 mm, 3 μm column with methanol and ammonium dihydrogen phosphate (pH-2.8) as mobile phase. The method was validated in terms of specificity, precision, linearity, accuracy, limit of quantification (LOQ), and limit of detection (LOD). The linearity of the proposed method was investigated for concentration ranging between 0.5-60 μg/mL with regression co-efficient, R(2) = 0.999-1.0. This method estimates all the TPBAs simultaneously with enhanced precision and linearity as per the ICH guidelines. Also, to confirm the individual TPBA, the antioxidant property of the each TPBA was analyzed which was commensurate with that of the previous reports. PMID:27407191

  1. A validated HPLC method for the analysis of herbal teas from three chemotypes of Brazilian Lippia alba.

    PubMed

    Timóteo, Patrícia; Karioti, Anastasia; Leitão, Suzana G; Vincieri, Franco Francesco; Bilia, Anna Rita

    2015-05-15

    Infusions and decoctions of three chemotypes of Lippia alba (Mill.) N. E. Brown (Verbenaceae) were investigated for their quantitative profiles by HPLC-DAD-ESI-MS analyses. An RP-HPLC method was developed which permitted the quality control of the preparations. The correct choice of the column allowed the detailed characterization of the constituents in a total analysis time of 35 min. The HPLC method was accordingly validated for linearity range, LOD, LOQ, accuracy and precision. For the quantitative analysis the three major phytochemical groups were taken into consideration, namely iridoids, phenylpropanoids and flavonoids. Comparative quantitative analyses revealed significant differences among the chemotypes that should be taken into account in the uses of the herbal teas. The developed HPLC-UV assay proved to be an efficient and alternative method for the discrimination of the three chemotypes. This is the first report of detailed analysis of the chemical composition of the constituents of L. alba chemotypes' teas. PMID:25577093

  2. Innovative development and validation of an HPLC/DAD method for the qualitative and quantitative determination of major cannabinoids in cannabis plant material.

    PubMed

    De Backer, Benjamin; Debrus, Benjamin; Lebrun, Pierre; Theunis, Laetitia; Dubois, Nathalie; Decock, Lies; Verstraete, Alain; Hubert, Philippe; Charlier, Corinne

    2009-12-15

    GC is commonly used for the analysis of cannabis samples, e.g. in forensic chemistry. However, as this method is based on heating of the sample, acidic forms of cannabinoids are decarboxylated into their neutral counterparts. Conversely, HPLC permits the determination of the original composition of plant cannabinoids by direct analysis. Several HPLC methods have been described in the literature, but most of them failed to separate efficiently all the cannabinoids or were not validated according to general guidelines. By use of an innovative methodology for modelling chromatographic responses, a simple and accurate HPLC/DAD method was developed for the quantification of major neutral and acidic cannabinoids present in cannabis plant material: Delta9-tetrahydrocannabinol (THC), THC acid (THCA), cannabidiol (CBD), CBD acid (CBDA), cannabigerol (CBG), CBG acid (CBGA) and cannabinol (CBN). Delta8-Tetrahydrocannabinol (Delta8-THC) was determined qualitatively. Following the practice of design of experiments, predictive multilinear models were developed and used in order to find optimal chromatographic analytical conditions. The method was validated following an approach using accuracy profiles based on beta-expectation tolerance intervals for the total error measurement, and assessing the measurements uncertainty. This analytical method can be used for diverse applications, e.g. plant phenotype determination, evaluation of psychoactive potency and control of material quality. PMID:19932642

  3. Development of an HPLC Method for Absolute Quantification and QAMS of Flavonoids Components in Psoralea corylifolia L.

    PubMed Central

    Yan, Cuiping; Wu, Yu; Weng, Zebin; Gao, Qianqian; Yang, Guangming; Chen, Zhipeng; Cai, Baochang; Li, Weidong

    2015-01-01

    The seeds of Psoralea corylifolia L. (Fabaceae) are a commonly used medicinal herb in eastern Asia with many beneficial effects in clinical therapies. In this study, a simple, sensitive, precise, and specific reverse phase high-performance liquid chromatography (HPLC) method was established for quantification of 9 flavonoids in P. corylifolia, including isobavachin, neobavaisoflavone, bavachin, corylin, bavachalcone, bavachinin, isobavachalcone, corylifol A, and 4′-O-methylbavachalcone. Based on this method, a quantitative analysis of multicomponents by single marker (QAMS) was carried out, and the relative correction factors (RCFs) were calculated for determining the contents of other flavonoids. The accuracy of QAMS method was verified by comparing with the results of external standard method, as well as the feasibility and adaptability of the method applied on quality control of P. corylifolia. The 9 compounds were baseline separated in 60 min with a good linearity of regression coefficient (R2) over 0.9991. The accuracies of QAMS were between 92.89% and 109.5%. The RSD values of f in different injection volume were between 2.3% and 3.6%. The results obtained from QAMS suggested that it was a convenient and accurate method to determine multicomponents especially when some authentic standard substances were unavailable. It can be used to control the quality of P. corylifolia. PMID:26587307

  4. Stability-indicating HPLC method for the determination of impurities in meprobamate with refractive index detection.

    PubMed

    Karthikeyan, K; Balaji, T S; Shanmugasundaram, P; Chandrasekara Pillai, K

    2010-03-01

    The purpose of this study is to develop and validate a simple, sensitive, and robust high-performance liquid chromagraphic (HPLC) method for the determination of impurities ca. 2-methyl-2-propyl-1,3-propane diol (MP0) and 2-hydroxymethyl-2-methyl pentyl carbamate (MP1) in meprobamate (MEP) drug substance with refractive index (RI) detection. This method utilizes a Zorbax Eclipse XDB C(18) HPLC column, a mobile phase of 80:20 (v/v) 10 mM KH(2)PO(4),-acetonitrile, respectively. The stability-indicating capability of the method has been established by performing stress studies under acidic, basic, oxidation, light, humidity, and thermal conditions. The major degradation products of acid and base hydrolysis are identified as MP0 and MP1. The recovery data obtained for impurities are between 96.0-109.8%. The detection and quantitation limits of this method ranges from 0.009 to 0.017 mg/mL and 0.029 to 0.055 mg/mL, respectively. The relative standard deviation (RSD) for the area at QL is less than 6.1%. Good linearity (r(2) > 0.99) and precision (RSD < 2.2%) have been obtained for MEP, MP0, and MP1. This method has been applied successfully to determine the content of impurities in MEP bulk drug. PMID:20223088

  5. Development of a HPLC Method for the Quantitative Determination of Capsaicin in Collagen Sponge

    PubMed Central

    Guo, Chun-Lian; Chen, Hong-Ying; Cui, Bi-Ling; Chen, Yu-Huan; Zhou, Yan-Fang; Peng, Xin-Sheng; Wang, Qin

    2015-01-01

    Controlling the concentration of drugs in pharmaceutical products is essential to patient's safety. In this study, a simple and sensitive HPLC method is developed to quantitatively analyze capsaicin in collagen sponge. The capsaicin from sponge was extracted for 30 min with ultrasonic wave extraction technique and methanol was used as solvent. The chromatographic method was performed by using isocratic system composed of acetonitrile-water (70 : 30) with a flow rate of 1 mL/min and the detection wavelength was at 280 nm. Capsaicin can be successfully separated with good linearity (the regression equation is A = 9.7182C + 0.8547; R2 = 1.0) and perfect recovery (99.72%). The mean capsaicin concentration in collagen sponge was 49.32 mg/g (RSD = 1.30%; n = 3). In conclusion, the ultrasonic wave extraction method is simple and the extracting efficiency is high. The HPLC assay has excellent sensitivity and specificity and is a convenient method for capsaicin detection in collagen sponge. This paper firstly discusses the quantitative analysis of capsaicin in collagen sponge. PMID:26612986

  6. The effect of assay methods on plasma levels and pharmacokinetics of theophylline: HPLC and EIA.

    PubMed Central

    Ishizaki, T; Watanabe, M; Morishita, N

    1979-01-01

    1 The effects of two assay methods, HPLC and EIA, on theophylline plasma levels (n = 254) and pharmacokinetics (n = 6) were examined on blood samples obtained from asthmatic patients and normal adult male volunteers. 2 The standard curves obtained and the plasma level values during plasma level monitoring of theophylline measured with two methods are well correlated each other within concentration range of 2.5 to 20.0 microgram/ml (P less than 0.001). EIA, however in general, appears to give a lower value than HPLC. 3 The values of plasma theophylline half-life and clearance analyzed using a two-compartment open system model were found different between the two assay methods and dissimilar to those previously reported by using ultraviolet method. 4 The sampling end-point and/or assay sensitivity particularly to measure a lower level of theophylline (less than 2.5 microgram/ml) can influence the pharmacokinetics for a potent bronchodilator with a narrow therapeutic margin, theophylline. PMID:375957

  7. Extraction and Determination of Cyproheptadine in Human Urine by DLLME-HPLC Method

    PubMed Central

    Maham, Mehdi; Kiarostami, Vahid; Waqif-Husain, Syed; Abroomand-Azar, Parviz; Tehrani, Mohammad Saber; Khoeini Sharifabadi, Malihe; Afrouzi, Hossein; Shapouri, MahmoudReza; Karami-Osboo, Rouhollah

    2013-01-01

    Novel dispersive liquid-liquid microextraction (DLLME), coupled with high performance liquid chromatography with photodiode array detection (HPLC-DAD) has been applied for the extraction and determination of cyproheptadine (CPH), an antihistamine, in human urine samples. In this method, 0.6 mL of acetonitrile (disperser solvent) containing 30 μL of carbon tetrachloride (extraction solvent) was rapidly injected by a syringe into 5 mL urine sample. After centrifugation, the sedimented phase containing enriched analyte was dissolved in acetonitrile and an aliquot of this solution injected into the HPLC system for analysis. Development of DLLME procedure includes optimization of some important parameters such as kind and volume of extraction and disperser solvent, pH and salt addition. The proposed method has good linearity in the range of 0.02-4.5 μg mL-1 and low detection limit (13.1 ng mL-1). The repeatability of the method, expressed as relative standard deviation was 4.9% (n = 3). This method has also been applied to the analysis of real urine samples with satisfactory relative recoveries in the range of 91.6-101.0%. PMID:24250605

  8. Development and validation of RP-HPLC method for estimation of ethacridine lactate in bulk and in pharmaceutical formulation

    PubMed Central

    Jain, P. S.; Jivani, H. N.; Khatal, R. N.; Surana, S. J.

    2011-01-01

    A new simple, precise, accurate and selective RP-HPLC method has been developed and validated for estimation of Ethacridine lactate in pharmaceutical formulation. The method was carried out on a Qualisil RP C-18 (250 mm × 4.6 mm, 5 μm) column with a mobile phase consisting of methanol: water (60:40 v/v), pH adjusted to 2.8 with ortho-phosphoric acid and flow rate of 1.0 mL/min. Detection was carried out at 271 nm. The retention time for ethacridine lactate was found to be 4.41 min. The ethacridine lactate followed linearity in the concentration range of 2- 12 μg/mL (r2= 0.9980). The amount of the drug estimated by proposed method was found to be in good agreement with label claim. The developed method was validated for sensitivity, accuracy, precision, ruggedness and robustness. The LOD and LOQ were found to be 0.11 and 0.33 μg. The proposed method can be used for routine analysis of ethacridine lactate in bulk drug and pharmaceutical formulation. PMID:23781440

  9. Development and validation of RP-HPLC method for estimation of ethacridine lactate in bulk and in pharmaceutical formulation.

    PubMed

    Jain, P S; Jivani, H N; Khatal, R N; Surana, S J

    2011-04-01

    A new simple, precise, accurate and selective RP-HPLC method has been developed and validated for estimation of Ethacridine lactate in pharmaceutical formulation. The method was carried out on a Qualisil RP C-18 (250 mm × 4.6 mm, 5 μm) column with a mobile phase consisting of methanol: water (60:40 v/v), pH adjusted to 2.8 with ortho-phosphoric acid and flow rate of 1.0 mL/min. Detection was carried out at 271 nm. The retention time for ethacridine lactate was found to be 4.41 min. The ethacridine lactate followed linearity in the concentration range of 2- 12 μg/mL (r(2)= 0.9980). The amount of the drug estimated by proposed method was found to be in good agreement with label claim. The developed method was validated for sensitivity, accuracy, precision, ruggedness and robustness. The LOD and LOQ were found to be 0.11 and 0.33 μg. The proposed method can be used for routine analysis of ethacridine lactate in bulk drug and pharmaceutical formulation. PMID:23781440

  10. Development, Optimization, and Validation of a Green and Stability-Indicating HPLC Method for Determination of Daptomycin in Lyophilized Powder.

    PubMed

    Tótoli, Eliane Gandolpho; Salgado, Hérida Regina Nunes

    2015-01-01

    Daptomycin is an antimicrobial that plays an important role in clinical practice today because it is considered a promising drug to combat resistant strains, such as methicilin and vancomycin-resistant Gram-positive bacteria. Considering the analysis of daptomycin in a pharmaceutical dosage form, the only method found in literature uses potentially toxic organic solvents. Therefore, the objective of this work was to develop a green and stability-indicating HPLC method for determination of daptomycin in lyophilized powder. The mobile phase was ethanol-water (55+45, v/v) at pH 4.5 pumped at a flow rate of 0.6 mL/min. A C18 column was used, and UV detection was performed at 221 nm. Stress degradation studies were conducted in order to demonstrate the specificity and stability-indicating capability of the method. The method was validated according to International Conference on Harmonization guidelines, proving to be linear (r=0.9996), precise, accurate, robust (demonstrated by the Plackett-Burman model), and specific within the range 20-70 μg/mL. The retention time of daptomycin was 5.8 min. It can be concluded that the validated method can be a fast, safe, and environmentally friendly alternative for the analysis of daptomycin. PMID:26525246

  11. HPLC method development for evolving applications in the pharmaceutical industry and nanoscale chemistry

    NASA Astrophysics Data System (ADS)

    Castiglione, Steven Louis

    As scientific research trends towards trace levels and smaller architectures, the analytical chemist is often faced with the challenge of quantitating said species in a variety of matricies. The challenge is heightened when the analytes prove to be potentially toxic or possess physical or chemical properties that make traditional analytical methods problematic. In such cases, the successful development of an acceptable quantitative method plays a critical role in the ability to further develop the species under study. This is particularly true for pharmaceutical impurities and nanoparticles (NP). The first portion of the research focuses on the development of a part-per-billion level HPLC method for a substituted phenazine-class pharmaceutical impurity. The development of this method was required due to the need for a rapid methodology to quantitatively determine levels of a potentially toxic phenazine moiety in order to ensure patient safety. As the synthetic pathway for the active ingredient was continuously refined to produce progressively lower amounts of the phenazine impurity, the approach for increasingly sensitive quantitative methods was required. The approaches evolved across four discrete methods, each employing a unique scheme for analyte detection. All developed methods were evaluated with regards to accuracy, precision and linear adherence as well as ancillary benefits and detriments -- e.g., one method in this evolution demonstrated the ability to resolve and detect other species from the phenazine class. The second portion of the research focuses on the development of an HPLC method for the quantitative determination of NP size distributions. The current methodology for the determination of NP sizes employs tunneling electron microscopy (TEM), which requires sample drying without particle size alteration and which, in many cases, may prove infeasible due to cost or availability. The feasibility of an HPLC method for NP size characterizations evolved

  12. Two validated HPLC methods for the quantification of alizarin and other anthraquinones in Rubia tinctorum cultivars.

    PubMed

    Derksen, Goverdina C H; Lelyveld, Gerrit P; van Beek, Teris A; Capelle, Anthony; de Groot, A E

    2004-01-01

    Direct and indirect HPLC-UV methods for the quantitative determination of anthraquinones in dried madder root have been developed, validated and compared. In the direct method, madder root was extracted twice with refluxing ethanol-water. This method allowed the determination of the two major native anthraquinone glycosides lucidin primeveroside and ruberythric acid. In the indirect extraction method, the anthraquinone glycosides were first converted into aglycones by endogenous enzymes and the aglycones were subsequently extracted with tetrahydrofuran-water and then analysed. In this case the anthraquinones alizarin, purpurin and nordamnacanthal may be determined. The content of nordamnacanthal is proportional to the amount of lucidin primeveroside originally present. The indirect extraction method is easier to apply. Different madder cultivars were screened for their anthraquinone content. PMID:15599964

  13. A method for producing large, accurate, economical female molds

    SciTech Connect

    Guenter, A.; Guenter, B.

    1996-11-01

    A process in which lightweight, highly accurate, economical molds can be produced for prototype and low production runs of large parts for use in composites molding has been developed. This has been achieved by developing existing milling technology, using new materials and innovative material applications to CNC mill large female molds directly. Any step that can be eliminated in the mold building process translates into savings in tooling costs through reduced labor and material requirements.

  14. Method and apparatus for accurately manipulating an object during microelectrophoresis

    DOEpatents

    Parvin, Bahram A.; Maestre, Marcos F.; Fish, Richard H.; Johnston, William E.

    1997-01-01

    An apparatus using electrophoresis provides accurate manipulation of an object on a microscope stage for further manipulations add reactions. The present invention also provides an inexpensive and easily accessible means to move an object without damage to the object. A plurality of electrodes are coupled to the stage in an array whereby the electrode array allows for distinct manipulations of the electric field for accurate manipulations of the object. There is an electrode array control coupled to the plurality of electrodes for manipulating the electric field. In an alternative embodiment, a chamber is provided on the stage to hold the object. The plurality of electrodes are positioned in the chamber, and the chamber is filled with fluid. The system can be automated using visual servoing, which manipulates the control parameters, i.e., x, y stage, applying the field, etc., after extracting the significant features directly from image data. Visual servoing includes an imaging device and computer system to determine the location of the object. A second stage having a plurality of tubes positioned on top of the second stage, can be accurately positioned by visual servoing so that one end of one of the plurality of tubes surrounds at least part of the object on the first stage.

  15. Method and apparatus for accurately manipulating an object during microelectrophoresis

    DOEpatents

    Parvin, B.A.; Maestre, M.F.; Fish, R.H.; Johnston, W.E.

    1997-09-23

    An apparatus using electrophoresis provides accurate manipulation of an object on a microscope stage for further manipulations and reactions. The present invention also provides an inexpensive and easily accessible means to move an object without damage to the object. A plurality of electrodes are coupled to the stage in an array whereby the electrode array allows for distinct manipulations of the electric field for accurate manipulations of the object. There is an electrode array control coupled to the plurality of electrodes for manipulating the electric field. In an alternative embodiment, a chamber is provided on the stage to hold the object. The plurality of electrodes are positioned in the chamber, and the chamber is filled with fluid. The system can be automated using visual servoing, which manipulates the control parameters, i.e., x, y stage, applying the field, etc., after extracting the significant features directly from image data. Visual servoing includes an imaging device and computer system to determine the location of the object. A second stage having a plurality of tubes positioned on top of the second stage, can be accurately positioned by visual servoing so that one end of one of the plurality of tubes surrounds at least part of the object on the first stage. 11 figs.

  16. Validation of an HPLC method on short columns to assay ketoconazole and formaldehyde in shampoo.

    PubMed

    Nguyen, Minh Nguyet A; Tallieu, L; Plaizier-Vercammen, J; Massart, D L; Vander Heyden, Y

    2003-04-24

    An HPLC method to determine simultaneously ketoconazole and formaldehyde in an anti-dandruff shampoo, originally developed on a long column, was transferred to two short columns with similar stationary phase properties, but with a length of at the most 30% of the initial one. Using the conventional column as reference, the fast HPLC methods on the short columns were validated. The validation characteristics consisted of selectivity, linearity range, precision (repeatability and time-different intermediate precision), bias and robustness. For the ketoconazole assay, linearity for peak area was found in the concentration range up to 0.20 mg/ml. For formaldehyde, two calibration ranges (0-10 x 10(-5) and 0-10 x 10(-4)%) were linear, both for peak area and height. The assays for both ketoconazole and formaldehyde in these ranges showed no bias and an acceptable precision, although the precision found with the short columns was slightly worse than with the long one. The robustness tests were performed applying a Plackett-Burman design. For the ketoconazole assay, 6 factors were examined in a 12 experiments design and for formaldehyde, 11 factors in 16 experiments. The methods were found to be robust. Despite the somewhat less good precision the transfer seems to be successful and the obtained assays on the short columns are applicable for fast routine analysis. PMID:12852444

  17. Measurement of Microcystin -LR in Water Samples Using Improved HPLC Method

    PubMed Central

    Shamsollahi, Hamid Reza; Alimohammadi, Mahmood; Nabizadeh, Ramin; Nazmara, Shahrokh; Mahvi, Amir Hossein

    2015-01-01

    Microcystins are a group of toxic compounds produced by freshwater cyanobacteria and cause diseases. World Health Organization has recommended a concentration of 1 µg/l for Microcystin-LR (MC-LR) in potable water as guideline value. The high performance liquid chromatography (HPLC) followed by C18 analytical column and ultra violet detector for detection of MC-LR. In this regard, 5 different concentrations of MC-LR solutions were injected into HPLC. MC-LR was detected in 5.33 minute retention time and Calibration curve was achieved with R2=0.988. Detection limit for this method was obtained by using acetonitrile solutions (32% and 55%) as a gradient run and a high silanol activity column equal to 0.02 µg/mL. Despite no acidic organic modifier being used in the mixture of solvents, the sensitivity of this method was appropriate for detection of MC-LR. Because of short retention time, reduction in number of solvents and high resolution and suitable sensitivity, this method is affordable and is fast for detection and determination of MC-LR in potable water. PMID:25716387

  18. HPLC-Based Method to Evaluate Kinetics of Glucosinolate Hydrolysis by Sinapis alba Myrosinase1

    PubMed Central

    Vastenhout, Kayla J.; Tornberg, Ruthellen H.; Johnson, Amanda L.; Amolins, Michael W.; Mays, Jared R.

    2014-01-01

    Isothiocyanates (ITCs) are one of several hydrolysis products of glucosinolates, plant secondary metabolites which are substrates for the thioglucohydrolase myrosinase. Recent pursuits toward the development of synthetic, non-natural ITCs have consequently led to an exploration of generating these compounds from non-natural glucosinolate precursors. Evaluation of the myrosinase-dependent conversion of select non-natural glucosinolates to non-natural ITCs cannot be accomplished using established UV-Vis spectroscopic methods. To overcome this limitation, an alternative HPLC-based analytical approach was developed where initial reaction velocities were generated from non-linear reaction progress curves. Validation of this HPLC method was accomplished through parallel evaluation of three glucosinolates with UV-Vis methodology. The results of this study demonstrate that kinetic data is consistent between both analytical methods and that the tested glucosinolates respond similarly to both Michaelis–Menten and specific activity analyses. Consequently, this work resulted in the complete kinetic characterization of three glucosinolates with Sinapis alba myrosinase, with results that were consistent with previous reports. PMID:25068719

  19. A Simple HPLC-UV Method for the Determination of Glutathione in PC-12 Cells.

    PubMed

    Appala, Raju N; Chigurupati, Sridevi; Appala, Raju V V S S; Krishnan Selvarajan, Kesavanarayanan; Islam Mohammad, Jahidul

    2016-01-01

    A highly sensitive and simple HPLC-UV method was developed and validated for the assay of glutathione (GSH) in PC-12 cells. Glutathione is a major intracellular antioxidant having multiple biological effects, best known for its cytoprotective effects against cell damage from reactive oxygen species and toxic reactive metabolites and regulating the cellular redox homeostasis. Due to its own sulfhydryl (SH) group, GSH readily reacts with Ellman's reagent to form a stable dimer which allows for quantitative estimation of GSH in biological systems by UV detection. The separation was achieved using a C8 column with a mobile phase consisting of phosphate buffer adjusted to pH 2.5 (mobile phase A) and acetonitrile (mobile phase B), running in a segmented gradient manner at a flow rate of 0.8 mL/min, and UV detection was performed at 280 nm. The developed HPLC-UV method was validated with respect to precision, accuracy, robustness, and linearity within a range of 1-20 μg/mL. Limit of detection (LOD) and limit of quantification (LOQ) were 0.05 and 0.1 μg/mL, respectively. Furthermore, the method shows the applicability for monitoring the oxidative stress in PC-12 cells. PMID:27127683

  20. HPLC method development, validation, and impurity characterization of a potent antitumor indenoisoquinoline, LMP776 (NSC 725776).

    PubMed

    Wang, Jennie; Liu, Mingtao; Yang, Chun; Wu, Xiaogang; Wang, Euphemia; Liu, Paul

    2016-05-30

    An HPLC method for the assay of a DNA topoisomerase inhibitor, LMP776 (NSC 725776), has been developed and validated. The stress testing of LMP776 was carried out in accordance with International Conference on Harmonization (ICH) guidelines Q1A (R2) under acidic, alkaline, oxidative, thermolytic, and photolytic conditions. The separation of LMP776 from its impurities and degradation products was achieved within 40 min on a Supelco Discovery HS F5 column (150 mm × 4.6 mm i.d., 5 μm) with a gradient mobile phase comprising 38-80% acetonitrile in water, with 0.1% trifluoroacetic acid in both phases. LC/MS was used to obtain mass data for characterization of impurities and degradation products. One major impurity was isolated through chloroform extraction and identified by NMR. The proposed HPLC assay method was validated for specificity, linearity (concentration range 0.25-0.75 mg/mL, r = 0.9999), accuracy (recovery 98.6-100.4%), precision (RSD ≤ 1.4%), and sensitivity (LOD 0.13 μg/mL). The validated method was used in the stability study of the LMP776 drug substance in conformance with the ICH Q1A (R2) guideline. PMID:26970596

  1. A Simple HPLC-UV Method for the Determination of Glutathione in PC-12 Cells

    PubMed Central

    Appala, Raju N.; Appala, Raju V. V. S. S.

    2016-01-01

    A highly sensitive and simple HPLC-UV method was developed and validated for the assay of glutathione (GSH) in PC-12 cells. Glutathione is a major intracellular antioxidant having multiple biological effects, best known for its cytoprotective effects against cell damage from reactive oxygen species and toxic reactive metabolites and regulating the cellular redox homeostasis. Due to its own sulfhydryl (SH) group, GSH readily reacts with Ellman's reagent to form a stable dimer which allows for quantitative estimation of GSH in biological systems by UV detection. The separation was achieved using a C8 column with a mobile phase consisting of phosphate buffer adjusted to pH 2.5 (mobile phase A) and acetonitrile (mobile phase B), running in a segmented gradient manner at a flow rate of 0.8 mL/min, and UV detection was performed at 280 nm. The developed HPLC-UV method was validated with respect to precision, accuracy, robustness, and linearity within a range of 1–20 μg/mL. Limit of detection (LOD) and limit of quantification (LOQ) were 0.05 and 0.1 μg/mL, respectively. Furthermore, the method shows the applicability for monitoring the oxidative stress in PC-12 cells. PMID:27127683

  2. A simple HPLC-UV method for the simultaneous quantification of gefitinib and erlotinib in human plasma.

    PubMed

    Faivre, Lionel; Gomo, Charline; Mir, Olivier; Taieb, Fabrice; Schoemann-Thomas, Audrey; Ropert, Stanislas; Vidal, Michel; Dusser, Daniel; Dauphin, Alain; Goldwasser, Francois; Blanchet, Benoit

    2011-08-01

    Gefitinib and erlotinib are two oral tyrosine kinase inhibitors (TKI) approved for the treatment of advanced non-small cell lung cancer (NSCLC). Published methods for simultaneous analysis of erlotinib and gefitinib in plasma are exclusively based on mass spectrometry. The purpose of this study was to develop a simple and sensitive HPLC-UV method to simultaneously quantify these two TKI in plasma. Following liquid-liquid extraction, gefitinib, erlotinib and sorafenib (internal standard), were separated with gradient elution (on a C8+ Satisfaction(®) using a mobile phase of acetonitrile/20mM ammonium acetate pH 4.5). Samples were eluted at a flow rate of 0.4 ml/min throughout the 15-min run. Dual UV wavelength mode was used, with gefitinib and erlotinib monitored at 331 nm, and sorafenib at 249 nm. The calibration was linear in the range 20-1000 ng/ml and 80-4000 ng/ml for gefitinib and erlotinib, respectively. Inter- and intra-day imprecision were less than 7.2% and 7.6% for gefitinib and erlotinib, respectively. This analytical method was successfully applied to assess the steady state plasma exposure to these TKI in NSCLC patients. This simple, sensitive, accurate and cost-effective method can be used in routine clinical practice to monitor gefitinib or erlotinib concentrations in plasma from NSCLC patients. PMID:21737360

  3. A rapid ultra HPLC-MS/MS method for the quantitation and pharmacokinetic analysis of 3-deazaneplanocin A in mice.

    PubMed

    Peer, Cody J; Rao, Mahadev; Spencer, Shawn D; Shahbazi, Shandiz; Steeg, Patricia S; Schrump, David S; Figg, William D

    2013-05-15

    3-Deazaneplanocin A (DZNep) has been shown to have anti-cancer activity in numerous cancer types and its continued preclinical, and eventual clinical, drug development will require rapid and sensitive bioanalytical methods in order to quantitate this drug for pharmacokinetic analyses. The ultra HPLC with positive thermospray tandem mass spectrometric (LC-MS/MS) detection affords the most sensitive (limit of quantitation 5ng/mL) and rapid (3min run time) bioanalytical method to date for DZNep. Due to the polar nature of this drug and the internal standard (tubercidin), a hydrophilic-interaction column (HILIC) was used. The method was accurate, with less than 10% deviation from nominal values, as well as precise, where both within-day and between-day precisions were less than 15%. A liquid-liquid extraction procedure was able to recover ∼90% of drug from a small volume (50μL) of mouse plasma. This method was successfully applied to a pharmacokinetic study in mice intravenously injected with DZNep. PMID:23352636

  4. A conventional HPLC-MS method for the simultaneous determination of ofloxacin and cefixime in plasma: Development and validation

    PubMed Central

    Attimarad, Mahesh V.; Alnajjar, Ahmed O.

    2013-01-01

    Objective: A simple, rapid, and sensitive high performance liquid chromatography-mass spectrometry (HPLC-MS) method was developed and validated for the simultaneous determination of ofloxacin (OFL) and cefixime (CEF) in human plasma using the moxifloxacin as internal standard. Methodology: Analytes were separated using an Agilent LCMS system equipped with a Zorbax eclipse XBD C18 column (150 mm × 4.6 mm i.d., 5 μm) and using a mobile phase consisting of a mixture of acetonitrile, methanol and 0.5% formic acid in a ratio of 23:10:67% v/v and flow rate was set at 0.6 mL/min. Plasma samples were extracted using the protein precipitation with acetonitrile and analyzed by positive ion mode. Results: The linearity of the proposed method was investigated in the concentration range of 4-500 ng/mL (r = 0.9996) for OFL and 40-6000 ng/mL (r = 0.9998) for CEF. The lower limits of quantification were 4 ng/mL and 40 ng/mL for OFL and CEF respectively, which reach the level of both drugs possibly found in human plasma. Further, the reported method was validated as per the ICH guidelines and found to be well within the acceptable range. Conclusion: The proposed method is simple, rapid, accurate, precise, and appropriate for pharmacokinetic and therapeutic drug monitoring in the clinical laboratories. PMID:24808668

  5. Determination of rifampicin and its main metabolite in plasma and urine in presence of pyrazinamide and isoniazid by HPLC method.

    PubMed

    Panchagnula, R; Sood, A; Sharda, N; Kaur, K; Kaul, C L

    1999-01-01

    A reversed phase HPLC method is described for the simultaneous estimation of rifampicin and its major metabolite desacetyl rifampicin, in the presence of isoniazid and pyrazinamide, in human plasma and urine. The assay involves simple liquid extraction of drug, metabolite and internal standard (rifapentine) from biological specimens and their subsequent separation on a C18 reversed phase column and single wavelength UV detection. In plasma as well as in urine samples, all the three compounds of interest eluted within 17 min. Using methanol-sodium phosphate buffer (pH 5.2; 0.01 M) (65:35, v/v) as mobile phase under isocratic conditions, it was established that isoniazid, pyrazinamide and ascorbic acid (added to prevent oxidative degradation of analytes) did not interfere with the analyte peaks. Recoveries (extraction efficiency) for drug were greater than 90% in both plasma and urine, whereas for metabolite the values were found to be 79 and 86% in plasma and urine, respectively. The plasma and urine methods were precise (total coefficient of variation ranged from 5 to 23%) and accurate (-7 to 5% of the nominal values) for both the analytes. Individual variance components, their estimates and their contribution to the total variance were also determined. Using the same method, unknown samples supplied by WHO were assayed and good correlations were obtained between the found and intended values. The method developed proved to be suitable for simultaneous estimation of rifampicin and desacetyl rifampicin in plasma and urine samples. PMID:9925337

  6. A stability-indicating RP-HPLC method for the quantitative analysis of meclizine hydrochloride in tablet dosage form.

    PubMed

    Peraman, Ramalingam; Manikala, Maheswari; Kondreddy, Vinod Kumar; Yiragamreddy, Padmanabha Reddy

    2015-01-01

    A specific stability-indicating reversed-phase high-performance liquid chromatographic method was developed and validated for the estimation of meclizine hydrochloride (MEC) in tablet dosage form. The HPLC method has shown adequate separation of MEC from their degradation products. The separation was achieved on a C8 (250 mm×4.6 mm×5 µm) column using a mobile phase composition of 0.2% triethylamine in water and methanol in the ratio of 65:35(pH adjusted to 3.0 with orthophosphoric acid) with a flow rate of 1 mL/min. The wavelength of a photo-diode array detector was kept at 229 nm. Stress studies were performed initially under milder conditions followed by stronger conditions so as to get sufficient degradation around 5-20%. There were six degradation products observed with adequate separation from the analyte peak. Among those detected degradation products, structures of four degradation products were verified by comparison with known impurities of meclizine analogs. The method was validated as per the International Conference on Harmonization (Q2) guidelines. The method was specific, selective, accurate and precise to quantify meclizine in the presence of degradation products. PMID:25644814

  7. New Stability-Indicating RP-HPLC Method for Determination of Diclofenac Potassium and Metaxalone from their Combined Dosage Form

    PubMed Central

    Panda, Sagar Suman; Patanaik, Debasis; Ravi Kumar, Bera V. V.

    2012-01-01

    A simple, precise and accurate isocratic RP-HPLC stability-indicating assay method has been developed to determine diclofenac potassium and metaxalone in their combined dosage forms. Isocratic separation was achieved on a Hibar-C18, Lichrosphere-100® (250 mm × 4.6 mm i.d., particle size 5 μm) column at room temperature in isocratic mode, the mobile phase consists of methanol: water (80:20, v/v) at a flow rate of 1.0 ml/min, the injection volume was 20 μl and UV detection was carried out at 280nm. The drug was subjected to acid and alkali hydrolysis, oxidation, photolysis and heat as stress conditions. The method was validated for specificity, linearity, precision, accuracy, robustness and system suitability. The method was linear in the drug concentration range of 2.5–30 μg/ml and 20–240 μg/ml for diclofenac potassium and metaxalone, respectively. The precision (RSD) of six samples was 0.83 and 0.93% for repeatability, and the intermediate precision (RSD) among six-sample preparation was 1.63 and 0.49% for diclofenac potassium and metaxalone, respectively. The mean recoveries were between 100.99–102.58% and 99.97–100.01% for diclofenac potassium and metaxalone, respectively. The proposed method can be used successfully for routine analysis of the drug in bulk and combined pharmaceutical dosage forms. PMID:22396909

  8. Development and Validation of Stability Indicating RP-HPLC Method for Voriconazole.

    PubMed

    Khetre, A B; Sinha, P K; Damle, Mrinalini C; Mehendre, R

    2009-09-01

    This study describes the development and validation of stability indicating HPLC method for voriconazole, an antifungal drug. Voriconazole was subjected to stress degradation under different conditions recommended by International Conference on Harmonization. The sample so generated was used to develop a stability-indicating high performance liquid chromatographic method for voriconazole. The peak for voriconazole was well resolved from peaks of degradation products, using a Hypersil C18 (250x4.6 mm) column and a mobile phase comprising of acetonitrile: water (40:60, v/v), at flow rate of 1 ml/min. Detection was carried out using photodiode array detector. A linear response (r > 0.99) was observed in the range of 5-25 mug/ml. The method showed good recoveries (average 100.06%) and relative standard deviation for intra and inter-day were method was validated for specificity and robustness also. PMID:20502568

  9. Efficient HPLC method for the determination of nicarbazin, as dinitrocarbanilide in broiler liver.

    PubMed

    Capurro, Emiliana; Danaher, Martin; Anastasio, Aniello; Cortesi, Maria Luisa; O'Keeffe, Michael

    2005-08-01

    A simple, fast and reliable HPLC-UV method has been developed for the determination of dinitrocarbanilide residues in broiler liver. Liver samples (2 g) were extracted with two portions of acetonitrile (10 and 5 ml), defatted with hexane and evaporated to dryness under nitrogen. Extracts were reconstituted in acetonitrile-water (70/30, v/v, 500 microl), loaded onto C18 solid phase (SPE) cartridges and eluted with acetonitrile-water (70/30, v/v, 2.5 ml) into clean test-tubes. Extracts were evaporated to dryness and reconstituted in acetonitrile-water (80/20, v/v, 500 microl). An aliquot of the extract was assayed by high performance liquid chromatography (HPLC) with UV detection at 350 nm. The method was validated according to EU guidelines using liver tissues fortified at levels of 100, 200 and 300 microg/kg, with dinitrocarbanilide. The decision limit (CC(alpha)) and the detection capability (CC(beta)) were calculated from the within laboratory repeatability data to be 228 and 266 microg/kg, respectively. The mean recovery was typically >70% and the limits of quantitation was 12.5 microg/kg (based on the lowest standard on the calibration curve). PMID:16005689

  10. Quality control of Gardeniae Fructus by HPLC-PDA fingerprint coupled with chemometric methods.

    PubMed

    Yin, Fangzhou; Wu, Xiaoyan; Li, Lin; Chen, Yan; Lu, Tuling; Li, Weidong; Cai, Baochang; Yin, Wu

    2015-01-01

    The ripe fruits of Gardenia jasminoides Ellis have been used as traditional Chinese medicine to treat diseases for a long history. Lines of evidence demonstrate that multiple active constituents are responsible for the therapeutic effects of this herbal medicine. However, effective methods for quality control of this herbal medicine are still lacking. In this study, a high-performance liquid chromatography (HPLC) fingerprint analysis was performed on a SinoChrom ODS-BP C18 column (4.6 mm × 250 mm, 5 μm) at 30°C with mobile phase of aqueous solution with 0.1% formic acid and acetonitrile. On the basis of the chromatographic data from 32 batches samples, the HPLC fingerprint pattern containing 27 common peaks was obtained. Among these common peaks, seven peaks were identified by the electrospray ionization-mass spectrometry as geniposidic acid, genipin-1-β-gentiobioside, chlorogenic acid, geniposide, rutin, crocin-1 and crocin-2 and the contents of these seven compounds were simultaneously determined. Finally, chemometric methods including hierarchical clustering analysis and principal component analysis were successfully applied to differentiate the samples from six producing regions. In sum, the data, as described in this study, offer valuable information for the quality control and proper use of Gardeniae Fructus. PMID:26071608

  11. Reverse-phase HPLC method for measuring polarity distributions of natural organic matter.

    PubMed

    Namjesnik-Dejanovic, Ksenija; Cabaniss, Stephen E

    2004-02-15

    A reverse-phase high-pressure liquid chromatography (RP-HPLC) method was developed to measure the polarity distribution of natural organic matter (NOM) samples. The polarity distribution is obtained by calibrating an octadecyl bonded silica phase column and polar eluent with compounds of known octanol-water partition coefficient (Kow) and using this calibration curve to transform NOM retention times into an equivalent Kow. Polarity distributions treat the NOM samples as a complex mixture rather than summarizing the polarity in a single number. The method is sensitive, with UV detection allowing quantitation of samples with <5 mg of C/L. Individual chromatograms are acquired in <20 min, allowing much faster analysis on smaller samples than XAD resin separation or 13C NMR. Polarity distributions of 10 representative NOM isolates and 2 whole water samples indicate that NOM is generally hydrophilic in nature (log Kow < 2), although XAD-8 isolates are more hydrophobic than RO isolates from the same source. Hydrophilicity, as indicated by recovery from the HPLC column, is correlated to the elemental oxygen/carbon ratio but does not correlate strongly with molecular weight or 13C NMR aromaticity. PMID:14998025

  12. HPLC method validation for measurement of sulforaphane level in broccoli by-products.

    PubMed

    Campas-Baypoli, O N; Sánchez-Machado, D I; Bueno-Solano, C; Ramírez-Wong, B; López-Cervantes, J

    2010-04-01

    A simple and specific analytical method was developed and tested for the determination of sulforaphane in broccoli by-products. The method includes the optimization of the conversion of glucoraphanin to sulforaphane, followed by purification of extracts using solid-phase extraction and high-performance liquid chromatography (HPLC) analysis. The response surface methodology was used to find optimum conditions for the preparation and purification procedure. Chromatographic conditions for reversed-phase HPLC with UV photodiode array detection were as follows: column, Exil ODS C(18), 25 x 0.46 cm, 5 microm; column temperature, 36 degrees C; mobile phase, a 30 : 70 (v/v) mixture of acetonitrile:water; flow rate, 0.6 mL/min. The detection wavelength was UV 202 nm. Under these conditions, excellent linearity was obtained (r(2) = 1), and the overall recovery was 97.5 and 98.1% for fresh florets and lyophilized florets, respectively. The precision results showed that the relative standard deviation of the repeatability for florets fresh and lyophilized was 3.0 and 4.0%, respectively. Sulforaphane contents were determined in the edible portion of fresh broccoli, and broccoli crop remains. PMID:19650149

  13. Development and validation of an HPLC/UV/MS method for simultaneous determination of 18 preservatives in grapefruit seed extract.

    PubMed

    Ganzera, Markus; Aberham, Anita; Stuppner, Hermann

    2006-05-31

    Grapefruit seed extracts are used in cosmetics, food supplements, and pesticides because of their antimicrobial properties, but suspicions about the true nature of the active compounds arose when synthetic disinfectants such as benzethonium or benzalkonium chloride were found in commercial products. The HPLC method presented herein allows the quality assessment (qualitative and quantitative) of these products for the first time. On the basis of a standard mixture of 18 preservatives most relevant for food and grapefruit products, a method was developed allowing the baseline separation of all compounds within 40 min. Optimum results were obtained with a C-8 stationary phase and a solvent system comprising aqueous trifluoroacetic acid, acetonitrile, and 2-propanol. The assay was fully validated and shown to be sensitive (LOD < or= 12.1 ng on-column), accurate (recovery rates > or = 96.1%), repeatable (sigma(rel) < or = 3.5%), precise (intra-day variation < or = 4.5%, interday variation < or = 4.1%), and rugged. Without any modifications the method could be adopted for LC-MS experiments, where the compounds of interest were directly assignable in positive ESI mode. The quantitative results of several products for ecofarming confirmed previous studies, as seven out of nine specimens were adulterated with preservatives in varying composition. The samples either contained benzethonium chloride (2.5-176.9 mg/mL) or benzalkonium chloride (138.2-236.3 mg/mL), together with smaller amounts of 4-hydroxybenzoic acid esters, benzoic acid, and salicylic acid. PMID:16719494

  14. Bioanalytical method development and validation for simultaneous estimation of cefixime and dicloxacillin by RP-HPLC in human plasma.

    PubMed

    Bhinge, Somnath D; Malipatil, Sharangouda M; Sonawane, Lalit V

    2014-01-01

    An accurate, rapid and simple reversed-phase high performance liquid chromatography (RP-HPLC) bioanalytical method was developed and validated for simultaneous estimation of cefixime, dicloxacillin in human plasma using ezetimibe as an internal standard. The cefixime, dicloxacillin and internal standard were extracted by liquid-liquid extraction technique. Chromatographic separation is accomplished using CAPCELL PAK C18 (4.6 mm × 250 mm, 5 m) analytical column. The mobile phase consisted of phosphate buffer, acetonitrile and methanol in 42:55:03 proportions. Detection and quantification were performed by UV/Vis detection at 225 nm. The lower limit of quantification was 0.5 µg mL(-1) for both cefixime and dicloxacillin in human plasma. The calibration curves were linear over the concentration range 0.5 to 40 µg mL(-1) for both drugs in human plasma. The method was quantitatively evaluated in terms of linearity, precision, accuracy, recovery, selectivity, and stability. The method was found to be simple, convenient and suitable for the analysis of cefixime and dicloxacillin from biological fluids. PMID:25286213

  15. Development and validation of a rapid HPLC method for the determination of oseltamivir phosphate in Tamiflu and generic versions.

    PubMed

    Joseph-Charles, J; Geneste, C; Laborde-Kummer, E; Gheyouche, R; Boudis, H; Dubost, J-P

    2007-08-15

    Oseltamivir phosphate (OP) is an antiviral drug that is used in the treatment and prophylaxis of both influenza A and influenza B. It is effective against all known influenza viruses than can infect humans, including pandemic influenza viruses and may be the most appropriate antiviral option against avian influenza caused by H5N1 virus. Tamiflu, the registered trademark used under exclusive license by Roche laboratories with OP as active pharmaceutical ingredient, is considered the best treatment for the bird flu disease. A simple, selective, linear, accurate and precise HPLC method was developed and validated for rapid assay of OP aimed to the quality control of Tamiflu capsules and generic versions. Isocratic elution at a flow rate of 1.2 mL/min was employed on a Zorbax CN column (150 mm x 4.6mm; 5 microm) at ambient temperature. The mobile phase consisted of methanol and 0.04 M formic acid pH 3.0 (50:50, v/v). The UV detection wavelength was 226 nm and 20 microL of sample was injected. Sotalol hydrochloride was used as the internal standard (IS). The retention times for OP and IS were 3.40 and 2.25 min, respectively. The method was successfully applied to commercial pharmaceuticals, Tamiflu and generic versions. The proposed method could be applicable for routine analysis of OP and monitoring of the quality of marketed drugs as possibly counterfeit Tamiflu. PMID:17512688

  16. Development and validation of a selective HPLC-UV method for thymol determination in skin permeation experiments.

    PubMed

    Angelo, Tamara; Pires, Felipe Q; Gelfuso, Guilherme M; da Silva, Joyce K R; Gratieri, Tais; Cunha-Filho, Marcílio S S

    2016-06-01

    Thymol is a natural monoterpene, whose antioxidant and antimicrobial properties suggest a potential use in topical formulations. A simple, precise and selective HPLC method for thymol determination in skin penetration studies was developed and validated in this paper. Separation was achieved with a RP-C18 column, mobile phase comprised of acetonitrile:water (35:65v/v), flow rate of 1.5mL/min, oven temperature at 40°C, injection volume of 30μL and UV detection at 278nm. The validation procedure certified the method was selective for thymol determination even when extracted from skin matrix extracts. It was also linear in a range from 0.5 to 15.0μg/mL, robust, precise and accurate, with recovery rates from the skin layers higher than 90%. Limits of detection and quantification were 0.05 and 0.14μg/mL, respectively. The method showed, therefore, to be adequate for use in further skin permeation studies employing thymol topical formulations. PMID:27085016

  17. Simultaneous Determination of Six Active Compounds in Yixin Badiranjibuya Granules, a Traditional Chinese Medicine, by RP-HPLC-UV Method

    PubMed Central

    Yu, Ning; He, ChenHui; Awuti, Gulistan; Zeng, Cheng; Xing, JianGuo; Huang, Wei

    2015-01-01

    In this study, a sensitive, precise, and accurate HPLC-UV method was developed and validated to simultaneously determine the six analytes (luteolin-7-O-β-D-glucuronide, apigenin-7-O-β-D-glucuronide, diosmetin-7-O-β-D-glucuronide, acacetin-7-O-β-D-glucuronide, tilianin, and rosmarinic acid) in Yixin Badiranjibuya Granules, in which five analytes (i.e., luteolin-7-O-β-D-glucuronide, apigenin-7-O-β-D-glucuronide, diosmetin-7-O-β-D-glucuronide, acacetin-7-O-β-D-glucuronide, and rosmarinic acid) were determined for the first time in Yixin Badiranjibuya Granules, the content of tilianin in Yixin Badiranjibuya Granules was reported in other literatures, and the content of tilianin in our work was higher than that of the literature reports. The quality of 11 batch samples from four different manufacturers was evaluated using the proposed determination method. The contents of the six analytes were largely different among samples from various manufacturers. Therefore, this determination method can provide a scientific basis for quality evaluation and control of Yixin Badiranjibuya Granules. PMID:26587308

  18. Development and Application of Multidimensional HPLC Mapping Method for O-linked Oligosaccharides

    PubMed Central

    Yagi, Hirokazu; Ohno, Erina; Kondo, Sachiko; Yoshida, Atsuhiro; Kato, Koichi

    2011-01-01

    Glycosylation improves the solubility and stability of proteins, contributes to the structural integrity of protein functional sites, and mediates biomolecular recognition events involved in cell-cell communications and viral infections. The first step toward understanding the molecular mechanisms underlying these carbohydrate functionalities is a detailed characterization of glycan structures. Recently developed glycomic approaches have enabled comprehensive analyses of N-glycosylation profiles in a quantitative manner. However, there are only a few reports describing detailed O-glycosylation profiles primarily because of the lack of a widespread standard method to identify O-glycan structures. Here, we developed an HPLC mapping method for detailed identification of O-glycans including neutral, sialylated, and sulfated oligosaccharides. Furthermore, using this method, we were able to quantitatively identify isomeric products from an in vitro reaction catalyzed by N-acetylglucosamine-6O-sulfotransferases and obtain O-glycosylation profiles of serum IgA as a model glycoprotein. PMID:24970123

  19. Determination of synthetic food colorants in fish products by an HPLC-DAD method.

    PubMed

    Karanikolopoulos, G; Gerakis, A; Papadopoulou, K; Mastrantoni, I

    2015-06-15

    Reliable methods for quantification of synthetic water-soluble colors in complex food matrices are currently not available. The present work describes the development and validation of an improved protocol for the analysis of synthetic food colorants in complex food matrices presenting high protein and/or fat content. The method developed employs an extraction stage, followed by a subsequent sonification, centrifugation and concentration step. A final clean up via SPE on polyamide cartridges was also employed. The isolated colorants were separated and analyzed by an RP-HPLC/DAD system. High and consistent recoveries (min. 81%) and low RSDs (max. 6%) were achieved for all studied colorants. The issue of high fat content matrices was also addressed showing the need for an additional defatting step in the procedure. Overall, the protocol presented shows high precision and accuracy of detection and can provide the basis for future development of similar methods in other complex food matrices. PMID:25660877

  20. A method for determining arsenolipids in seawater by HPLC-high resolution mass spectrometry.

    PubMed

    Khan, Muslim; Jensen, Kenneth B; Francesconi, Kevin A

    2016-06-01

    Arsenic-containing lipids (arsenolipids), naturally occurring arsenicals in algae, have never been detected in seawater even though they might be introduced to the water column on senescence of marine algae or by active excretion. The complex nature of seawater presents an analytical challenge to detect these compounds and to monitor their environmental fate. We developed a simple sample preparation method using liquid-liquid extraction combined with HPLC-high resolution mass spectrometry (HRMS) capable of measuring six standard arsenolipids in seawater at the ng As/L level (<1% of the total arsenic in seawater). The method is suitable for studies on the biotransformation and pathways of arsenolipids in the marine environment. When we applied the method to four samples of natural seawater, however, we did not find any of the six standard arsenolipids. PMID:27130122

  1. Structural Analysis and Quantitative Determination of Clevidipine Butyrate Impurities Using an Advanced RP-HPLC Method.

    PubMed

    Zhou, Yuxia; Zhou, Fan; Yan, Fei; Yang, Feng; Yao, Yuxian; Zou, Qiaogen

    2016-03-01

    Eleven potential impurities, including process-related compounds and degradation products, have been analyzed by comprehensive studies on the manufacturing process of clevidipine butyrate. Possible formation mechanisms could also be devised. MS and NMR techniques have been used for the structural characterization of three previously unreported impurities (Imp-3, Imp-5 and Imp-11). To separate and quantify the potential impurities in a simultaneous fashion, an efficient and advanced RP-HPLC method has been developed. In doing so, four major degradation products (Imp-2, Imp-4, Imp-8 and Imp-10) can be observed under varying stress conditions. This analytical method has been validated according to ICH guidelines with respect to specificity, accuracy, linearity, robustness and stability. The method described has been demonstrated to be applicable in routine quality control processes and stability evaluation studies of clevidipine butyrate. PMID:26489435

  2. Simple isocratic method for simultaneous determination of caffeine and catechins in tea products by HPLC.

    PubMed

    Fernando, Chamira Dilanka; Soysa, Preethi

    2016-01-01

    Tea is a popular beverage almost all over the world. Many studies show that tea consumption is closely associated with positive health impact. Most of the HPLC methods used for the determination of tea constituents include gradient elution systems which involve expensive instrumentation. The objective of this study was to develop a simple, rapid precise and low cost HPLC method for the separation and quantification of catechins and caffeine in tea (Camellia sinensis). The method utilizes a phenyl column (2.1 × 150 mm) with a UV-detector (280 nm) where excellent chromatographic separation of tea components i.e. gallic acid (GA), caffeine (Caf), epicatechin (EC) and (-)-epigallocatechin gallate (EGCG) was achieved. The isocratic elution system of acetonitrile, glacial acetic acid and deionized water (8:1:91 v/v/v) at a flow rate of 0.5 mL/min was involved. This method produced excellent accuracy and precision. Within run and between run precision was less than 7.5 %. The equations for calibration curves were y = 0.117 (±0.010)x + 0.173 (±0.024), y = 0.100 (±0.003)x + 0.045 (±0.019), y = 0.016 (±0.001)x + 0.006 (±0.004), y = 0.025 (±0.001)x-0.025 (±0.007) for GA, Caf, EC and EGCG respectively. The method validation parameters prove that the method is efficient, a simple and adequate for the quantitative determination of principal components in tea samples. PMID:27429880

  3. Detection of Abnormal Hemoglobin Variants by HPLC Method: Common Problems with Suggested Solutions

    PubMed Central

    Pant, Leela; Kalita, Dipti; Singh, Sompal; Kudesia, Madhur; Mendiratta, Sumanlata; Mittal, Meenakshi; Mathur, Alka

    2014-01-01

    Thalassemia and thalassemic hemoglobinopathies pose serious health problem leading to severe morbidity and mortality in Indian population. Plethora of hemoglobin variants is prevalent in multiethnic Indian population. The aim of the present study was to analyze laboratory aspects, namely, hematological profile and HPLC findings of the hemoglobin variants detected, and to discuss problems that we faced in diagnosis in a routine clinical laboratory. We screened a total of 4800 cases in a hospital based population of North India in a 2-years period of by automated HPLC method using the Variant Hemoglobin Testing System (Variant II Beta Thalassemia Short Program, Bio-Rad Laboratories) under the experimental conditions specified by the manufacturer. Whole blood in EDTA was used and red cell indices were determined using automated hematology analyzer. We detected 290 cases with abnormal variants in which beta thalassemia was the most common followed by hemoglobin E. Here, we discuss the laboratory aspects of various hemoglobin disorders and diagnostic difficulties in cases like borderline HbA2 values, presence of silent mutation, alpha thalassemia gene, and few rare variants which at times require correlation with genetic study. Special attention was given to HbA2 level even in presence of a structural variant to rule out coinheritance of beta thalassemia gene. PMID:27351019

  4. Efficient HPLC method development using structure-based database search, physico-chemical prediction and chromatographic simulation.

    PubMed

    Wang, Lin; Zheng, Jinjian; Gong, Xiaoyi; Hartman, Robert; Antonucci, Vincent

    2015-02-01

    Development of a robust HPLC method for pharmaceutical analysis can be very challenging and time-consuming. In our laboratory, we have developed a new workflow leveraging ACD/Labs software tools to improve the performance of HPLC method development. First, we established ACD-based analytical method databases that can be searched by chemical structure similarity. By taking advantage of the existing knowledge of HPLC methods archived in the databases, one can find a good starting point for HPLC method development, or even reuse an existing method as is for a new project. Second, we used the software to predict compound physicochemical properties before running actual experiments to help select appropriate method conditions for targeted screening experiments. Finally, after selecting stationary and mobile phases, we used modeling software to simulate chromatographic separations for optimized temperature and gradient program. The optimized new method was then uploaded to internal databases as knowledge available to assist future method development efforts. Routine implementation of such standardized workflows has the potential to reduce the number of experiments required for method development and facilitate systematic and efficient development of faster, greener and more robust methods leading to greater productivity. In this article, we used Loratadine method development as an example to demonstrate efficient method development using this new workflow. PMID:25481084

  5. Determination of metrafenone in vegetables by matrix solid-phase dispersion and HPLC-UV method.

    PubMed

    Li, Jianjun; Li, Yangyang; Xu, Dongliang; Zhang, Jingyu; Wang, Yuxi; Luo, Chao

    2017-01-01

    A simple method for determination of metrafenone in vegetables by matrix solid-phase dispersion (MSPD) and HPLC was developed. All vegetable samples were extracted with dichloromethane, and then the extracts were directly separated on a reversed-phase column with isocratic elution without a cleanup step. The linearity of metrafenone was good with the concentration between 0.005 and 5mg/kg, and the limit of detection (LOD) of the metrafenone was 0.002mg/kg. The recoveries ranged from 86.5% to 104.8% with the relative standard deviations (RSDs) in the range of 2.1-7.9% (n=6). The results indicated that the method was simple, rapid, highly sensitive and suitable for the determination of metrafenone in vegetables. PMID:27507450

  6. Laboratory Detection and Analysis of Organic Compounds in Rocks Using HPLC and XRD Methods

    NASA Technical Reports Server (NTRS)

    Dragoi, D.; Kanik, I.; Bar-Cohen, Y.; Sherrit, S.; Tsapin, A.; Kulleck, J.

    2004-01-01

    In this work we describe an analytical method for determining the presence of organic compounds in rocks, limestone, and other composite materials. Our preliminary laboratory experiments on different rocks/limestone show that the organic component in mineralogical matrices is a minor phase on order of hundreds of ppm and can be better detected using high precision liquid chromatography (HPLC). The matrix, which is the major phase, plays an important role in embedding and protecting the organic molecules from the harsh Martian environment. Some rocks bear significant amounts of amino acids therefore, it is possible to identify these phases using powder x-ray diffraction (XRD) by crystallizing the organic. The method of detection/analysis of organics, in particular amino acids, that have been associated with life will be shown in the next section.

  7. Chemical fingerprinting of Gardenia jasminoides Ellis by HPLC-DAD-ESI-MS combined with chemometrics methods.

    PubMed

    Han, Yan; Wen, Jun; Zhou, Tingting; Fan, Guorong

    2015-12-01

    A fingerprint analysis method has been developed for characterization and discrimination of Gardenia jasminoides Ellis from different areas. The chemometrics methods including similarity evaluation, principal components analysis (PCA) and hierarchical clustering analysis (HCA) were introduced to identify more useful chemical markers for improving the quality control standard of dried ripe fruits of G. jasminoides Ellis. Then the selected chemical markers were analyzed by high performance liquid chromatography-diode array detection-electrospray ionization mass spectrometry (HPLC-DAD-ESI-MS) qualitatively and quantitatively. 23 characteristic peaks were assigned while 19 peaks of them were identified by comparing retention times, UV and MS spectra with authentic compounds or literature data. Moreover, 14 of them were determined quantitatively which could effectively evaluate the quality of G. jasminoides Ellis. This study was expected to provide comprehensive information for the quality evaluation of G. jasminoides Ellis, which would be a valuable reference for further study and development of this herb and related medicinal products. PMID:26041243

  8. A Stability Indicating HPLC Method for the Determination of Nitisinone in Capsules.

    PubMed

    Souri, Effat; Lahiji, Farnaz R; Nourhashemi, Tannaz; Jalalizadeh, H

    2015-01-01

    In this study a simple and efficient stability-indicating HPLC method with short run time was developed for the determination of nitisinone. The stress degradation of nitisinone was studied in different acidic, basic, oxidative, thermal and photolytic conditions. The chromatographic separation was achieved on a Nova-Pak C18 column using a mixture of 50 mM NaH2PO4 (pH 2.5) and acetonitrile (45:55, v/v) as mobile phase. UV detection was performed at 280 nm. Good linearity was observed over the concentration range of 0.5-50 μg/ml with r(2)>0.999. The within-day and between-day precision values were less than 2%. The proposed method could be used for the determination of nitisinone in the presence of its degradation products and also dosage form excipients for the quality control purposes. PMID:26180282

  9. A Stability Indicating HPLC Method for the Determination of Nitisinone in Capsules

    PubMed Central

    Souri, Effat; Lahiji, Farnaz R.; Nourhashemi, Tannaz; Jalalizadeh, H.

    2015-01-01

    In this study a simple and efficient stability-indicating HPLC method with short run time was developed for the determination of nitisinone. The stress degradation of nitisinone was studied in different acidic, basic, oxidative, thermal and photolytic conditions. The chromatographic separation was achieved on a Nova-Pak C18 column using a mixture of 50 mM NaH2PO4 (pH 2.5) and acetonitrile (45:55, v/v) as mobile phase. UV detection was performed at 280 nm. Good linearity was observed over the concentration range of 0.5-50 μg/ml with r2>0.999. The within-day and between-day precision values were less than 2%. The proposed method could be used for the determination of nitisinone in the presence of its degradation products and also dosage form excipients for the quality control purposes. PMID:26180282

  10. Development and Validation of a New HPLC Method for the Determination of Biphenyl and Dibenzofuran Phytoalexins in Rosaceae.

    PubMed

    Teotia, Deepa; Saini, Shashank Sagar; Gaid, Mariam; Beuerle, Till; Beerhues, Ludger; Sircar, Debabrata

    2016-07-01

    A simple, precise, rapid and accurate isocratic reversed-phase high-performance liquid chromatographic method was developed and validated for the simultaneous determination of biphenyl (aucuparin and noraucuparin) and dibenzofuran (eriobofuran) phytoalexin from elicitor treated cell culture of Sorbus aucuparia (mountain ash). These phytoalexins play crucial role in combating scab disease in many commercially important rosaceous plants, such as apple, pear and mountain ash. The isocratic separation was performed in a Luna C18 reversed-phase column (250 × 4.6 mm, 5 μm particle size) using a mobile phase of 1 mM trifluoroacetic acid (TFA) in water with methanol [40:60 (v/v)]. Quantization of phytoalexin was carried out on Shimadzu-HPLC system using a Photo Diode Array (PDA) detector at 254 nm by comparing the peak area. Peak purity and identity were confirmed by UV spectroscopy and ESI-MS-MS in the negative ion mode. The different analytical performance parameters such as linearity, accuracy, precision, limit of detection and limit of quantification were determined according to the International Conference on Harmonization guidelines. Linearity was observed in the concentration range of 3-400 µg/mL with excellent correlation coefficient (R(2) ≥ 0.995). This newly developed method is rapid, easy, cost-effective and can be used for monitoring scab-resistance potential of rosaceous plants. PMID:26921892

  11. The development of accurate and efficient methods of numerical quadrature

    NASA Technical Reports Server (NTRS)

    Feagin, T.

    1973-01-01

    Some new methods for performing numerical quadrature of an integrable function over a finite interval are described. Each method provides a sequence of approximations of increasing order to the value of the integral. Each approximation makes use of all previously computed values of the integrand. The points at which new values of the integrand are computed are selected in such a way that the order of the approximation is maximized. The methods are compared with the quadrature methods of Clenshaw and Curtis, Gauss, Patterson, and Romberg using several examples.

  12. Characterization of gliclazide release from Isabgol husk hydrogel beads by validated HPLC method.

    PubMed

    Sharma, Vipin K; Mazumdar, B

    2014-01-01

    Isabgol husk, a medicinally important natural polysaccharide was applied for fabrication of hydrogel beads by ionic gelation method to incorporate gliclazide. Different strengths of Isabgol husk and sodium alginate were utilized for assessing the process variables on formulation performance. Aqueous solution of calcium chloride in 2, 5 and 8% w/v strength was used as cross-linker for polymeric blends of Isabgol husk and sodium alginate. The formulations were characterized for various parameters such as particle size, swelling index, entrapment efficiency, in vitro release, and release kinetics. The quantification of gliclazide throughout the study was performed by HPLC method which was validated according to ICH guidelines for system suitability, linearity, accuracy, sensitivity, precession, robustness, and ruggedness. The surface morphology of beads was observed by scanning electron microscopy. The formed beads were brown, free flowing, spherical, and irregular in structure. The size in different formulations varied from 752.83 +/- 0.630 to 838.62 +/- 0.741 microm. The beads remained for 2-3 h in alkaline phosphate buffer (pH 7.4), after that they showed disintegration. The formulations released up to 95% of loaded gliclazide in phosphate buffer (pH 7.4) within 8 h. No significant difference was observed in parameters studied such as particle size, entrapment efficiency and swelling index for hydrogel beads during accelerated stability study (p > 0.05). The regression equation developed by HPLC method was linear (r5 > 0.9990) over the range 2.5 to 10 microg/mL. The limit of detection (LOD) and limit of quantification (LOQ) were 0.037619 microg/mL and 0.113997 microg/mL, respectively. The observed values for number of theoretical plates (N > or = 2000), tailing factor (T < or = 2), asymmetry factor (AF < or = 1), and relative standard deviation (RSD < or = 1%) of applied method showed the reliability for gliclazide estimation in Isabgol husk hydrogel beads. PMID

  13. Determination of Acyclovir in Human Plasma Samples by HPLC Method with UV Detection: Application to Single-Dose Pharmacokinetic Study

    PubMed Central

    Zendelovska, Dragica; Simeska, Suzana; Atanasovska, Emilija; Georgievska, Kalina; Kikerkov, Igor; Labachevski, Nikola; Jakovski, Krume; Balkanov, Trajan

    2015-01-01

    BACKGROUND: The aim of this study is estimation of pharmacokinetic parameters: Cmax, tmax, t1/2, AUC0-t and AUC0-∞ with the two-way analysis of variance, single observation (ANOVA) for two preparations containing acyclovir. OBJECTIVE: In order to evaluate pharmacokinetic study of acyclovir, method for quantitative determination of acyclovir in human plasma should be simple, rapid and reproducible. Therefore, the method is developed, validated and applied for analysis of acyclovir in plasma samples obtained from healthy volunteers. MATERIAL AND METHODS: High performance liquid chromatographic (HPLC) method with UV-detection for the determination of acyclovir in human plasma is presented. This method involves protein precipitation with 20 % (V/V) perchloric acid. The chromatographic separation was accomplished on a reversed phase C8 column with a mobile phase composed of 0.1 % (V/V) triethylamine in water (pH 2.5). No internal standard is required. UV detection was set at 255 nm. The method was successfully applied for the evaluation of pharmacokinetic profiles of acyclovir tablets in 24 healthy volunteers. RESULTS: The validation results shows that proposed method is rugged, precise (RSDs for intra- and inter-day precision ranged from 1.02 to 8.37 %) and accurate (relative errors are less than 6.66 %). The calibration curve was linear in the concentration range of 0.1-2.0 µg/ml and the limit of quantification was 0.1 µg/ml. The Cmax, tmax and AUCs for the two products were not statistically different (p>0.05), suggesting that the plasma profiles generated by Zovirax were comparable to those produced by acyclovir manufactured by Jaka 80 company. CONCLUSION: Good precision, accuracy, simplicity, sensitivity and shorter time of analysis of the method makes it particularly useful for processing of multiple samples in a limited period of time for pharmacokinetic study of acyclovir. PMID:27275193

  14. Method accurately measures mean particle diameters of monodisperse polystyrene latexes

    NASA Technical Reports Server (NTRS)

    Kubitschek, H. E.

    1967-01-01

    Photomicrographic method determines mean particle diameters of monodisperse polystyrene latexes. Many diameters are measured simultaneously by measuring row lengths of particles in a triangular array at a glass-oil interface. The method provides size standards for electronic particle counters and prevents distortions, softening, and flattening.

  15. Construction of higher order accurate vortex and particle methods

    NASA Technical Reports Server (NTRS)

    Nicolaides, R. A.

    1986-01-01

    The standard point vortex method has recently been shown to be of high order of accuracy for problems on the whole plane, when using a uniform initial subdivision for assigning the vorticity to the points. If obstacles are present in the flow, this high order deteriorates to first or second order. New vortex methods are introduced which are of arbitrary accuracy (under regularity assumptions) regardless of the presence of bodies and the uniformity of the initial subdivision.

  16. Stability-indicating HPLC Method for Simultaneous Determination of Terbutaline Sulphate, Bromhexine Hydrochloride and Guaifenesin

    PubMed Central

    Porel, A.; Haty, Sanjukta; Kundu, A.

    2011-01-01

    The aim of the present study was the development and subsequent validation of a simple, precise and stability-indicating reversed phase HPLC method for the simultaneous determination of guaifenesin, terbutaline sulphate and bromhexine hydrochloride in the presence of their potential impurities in a single run. The photolytic as well as hydrolytic impurities were detected as 3,5-dihydroxybenzoic acid, 3,5-dihydroxybenzaldehyde, 1-(3,5-dihydroxyphenyl)-2-[(1,1-dimethylethyl) amino]-ethanone from terbutaline, 2-methoxyphenol and an unknown impurity identified as (2RS)-3-(2-hydroxyphenoxy)-propane-1,2-diol from guaifenesin. The chromatographic separation of all the three active components and their impurities was achieved on Wakosil II column, using phosphate buffer (pH 3.0) and acetonitrile as mobile phase which was delivered initially in the ratio of 80:20 (v/v) for 18 min, then changed to 60:40 (v/v) for next 12 min, and finally equilibrated back to 80:20 (v/v) for 10 min. Other HPLC parameters were: Flow rate at 1.0 ml/min, detection wavelengths 248 and 280 nm, injection volume 10 μl. The calibration graphs plotted with five concentrations of each component were linear with a regression coefficient R2 >0.9999. The limit of detection and limit of quantitation were estimated for all the five impurities. The established method was then validated for linearity, precision, accuracy, and specificity and demonstrated to be applicable to the determination of the active ingredients in commercial and model cough syrup. No interference from the formulation excipients was observed. These results suggest that this LC method can be used for the determination of multiple active ingredients and their impurities in a cough and cold syrup. PMID:22131621

  17. Simple Isocratic HPLC Method for Determination of Enantiomeric Impurity in Besifloxacin Hydrochloride.

    PubMed

    Kumar, G Pradeep; Srivastava, Vishal; Khandelwal, Kiran; Kumar, Rajesh; Hiriyanna, S G; Kumar, Ajay; Kumar, Pramod

    2016-09-01

    Besifloxacin is a unique chiral broad-spectrum flouroquinolone used in the treatment of bacterial conjunctivitis. R-form of besifloxacin hydrochloride shows higher antibacterial activity as compared to the S-isomer. Therefore, it is necessary to establish chiral purity. To establish chiral purity a high-performance liquid chromatography (HPLC) method for determination of R-besifloxacin and S-besifloxacin (BES impurity A) was developed and validated for in-process quality control and stability studies. The analytical performance parameters such as linearity, precision, accuracy, specificity, limit of detection (LOD), and lower limit of quantification (LOQ) were determined according to International Council for Harmonization ICH Q2(R1) guidelines. HPLC separation was achieved on Chiralpak AD-H (250 x 4.6 mm, 5 μm) column using n-heptane: ethanol: ethylenediamine: acetic acid (800:200:0.5:0.5) (v/v/v/v) as the mobile phase in an isocratic elution. The eluents were monitored by UV/Visible detector at 290 nm. The resolution between S-isomer and besifloxacin hydrochloride was more than 2.0. Based on a signal-to-noise ratio of 3 and 10 the LOD of besifloxacin was 0.30 μg/mL, while the LOQ was 0.90 μg/mL. The calibration curves were linear in the range of 0.9-7.5 μg/mL. Precision of the method was established within the acceptable range. The method was suitable for the quality control enantiomeric impurity in besifloxacin hydrochloride. Chirality 28:628-632, 2016. © 2016 Wiley Periodicals, Inc. PMID:27563753

  18. Stability-indicating HPLC Method for Simultaneous Determination of Terbutaline Sulphate, Bromhexine Hydrochloride and Guaifenesin.

    PubMed

    Porel, A; Haty, Sanjukta; Kundu, A

    2011-01-01

    The aim of the present study was the development and subsequent validation of a simple, precise and stability-indicating reversed phase HPLC method for the simultaneous determination of guaifenesin, terbutaline sulphate and bromhexine hydrochloride in the presence of their potential impurities in a single run. The photolytic as well as hydrolytic impurities were detected as 3,5-dihydroxybenzoic acid, 3,5-dihydroxybenzaldehyde, 1-(3,5-dihydroxyphenyl)-2-[(1,1-dimethylethyl) amino]-ethanone from terbutaline, 2-methoxyphenol and an unknown impurity identified as (2RS)-3-(2-hydroxyphenoxy)-propane-1,2-diol from guaifenesin. The chromatographic separation of all the three active components and their impurities was achieved on Wakosil II column, using phosphate buffer (pH 3.0) and acetonitrile as mobile phase which was delivered initially in the ratio of 80:20 (v/v) for 18 min, then changed to 60:40 (v/v) for next 12 min, and finally equilibrated back to 80:20 (v/v) for 10 min. Other HPLC parameters were: Flow rate at 1.0 ml/min, detection wavelengths 248 and 280 nm, injection volume 10 μl. The calibration graphs plotted with five concentrations of each component were linear with a regression coefficient R(2) >0.9999. The limit of detection and limit of quantitation were estimated for all the five impurities. The established method was then validated for linearity, precision, accuracy, and specificity and demonstrated to be applicable to the determination of the active ingredients in commercial and model cough syrup. No interference from the formulation excipients was observed. These results suggest that this LC method can be used for the determination of multiple active ingredients and their impurities in a cough and cold syrup. PMID:22131621

  19. Comparison of HPLC, UV spectrophotometry and potentiometric titration methods for the determination of lumefantrine in pharmaceutical products.

    PubMed

    da Costa César, Isabela; Nogueira, Fernando Henrique Andrade; Pianetti, Gérson Antônio

    2008-09-10

    This paper describes the development and evaluation of a HPLC, UV spectrophotometry and potentiometric titration methods to quantify lumefantrine in raw materials and tablets. HPLC analyses were carried out using a Symmetry C(18) column and a mobile phase composed of methanol and 0.05% trifluoroacetic acid (80:20), with a flow rate of 1.0ml/min and UV detection at 335nm. For the spectrophotometric analyses, methanol was used as solvent and the wavelength of 335nm was selected for the detection. Non-aqueous titration of lumefantrine was carried out using perchloric acid as titrant and glacial acetic acid/acetic anhydride as solvent. The end point was potentiometrically determined. The three evaluated methods showed to be adequate to quantify lumefantrine in raw materials, while HPLC and UV methods presented the most reliable results for the analyses of tablets. PMID:18571353

  20. More accurate matrix-matched quantification using standard superposition method for herbal medicines.

    PubMed

    Liu, Ying; Shi, Xiao-Wei; Liu, E-Hu; Sheng, Long-Sheng; Qi, Lian-Wen; Li, Ping

    2012-09-01

    Various analytical technologies have been developed for quantitative determination of marker compounds in herbal medicines (HMs). One important issue is matrix effects that must be addressed in method validation for different detections. Unlike biological fluids, blank matrix samples for calibration are usually unavailable for HMs. In this work, practical approaches for minimizing matrix effects in HMs analysis were proposed. The matrix effects in quantitative analysis of five saponins from Panax notoginseng were assessed using high-performance liquid chromatography (HPLC). Matrix components were found to interfere with the ionization of target analytes when mass spectrometry (MS) detection were employed. To compensate the matrix signal suppression/enhancement, two matrix-matched methods, standard addition method with the target-knockout extract and standard superposition method with a HM extract were developed and tested in this work. The results showed that the standard superposition method is simple and practical for overcoming matrix effects for quantitative analysis of HMs. Moreover, the interference components were observed to interfere with light scattering of target analytes when evaporative light scattering detection (ELSD) was utilized for quantitative analysis of HMs but was not indicated when Ultraviolet detection (UV) were employed. Thus, the issue of interference effects should be addressed and minimized for quantitative HPLC-ELSD and HPLC-MS methodologies for quality control of HMs. PMID:22835696

  1. A direct RP-HPLC method for the determination of furanic aldehydes and acids in honey.

    PubMed

    Spano, Nadia; Ciulu, Marco; Floris, Ignazio; Panzanelli, Angelo; Pilo, Maria I; Piu, Paola C; Salis, Severyn; Sanna, Gavino

    2009-04-15

    In this study 5-hydroxymethyl-2-furaldehyde (HMF), 2-furaldehyde, 3-furaldehyde, 2-furoic acid and 3-furoic acid are contemporarily determined in honey using a swift and direct RP-HPLC approach. The validation protocol was performed in terms of detection and quantification limits, precision (by repeatability and reproducibility), linearity and accuracy (by recovery tests); the acceptability of the precision and accuracy results was positively verified using Horwitz's model and AOAC guidelines, respectively. The method was tested on 18 honey samples of different ages, and botanical and geographical origin. HMF and 2-furaldehyde correlated highly with the age of the samples, whereas no correlation was observed with regards to 2-furaldehyde and 2-furoic acid. Hypotheses relating to the formation of minority furanic compounds are also proposed. PMID:19174244

  2. HPLC method for identification and quantification of benzimidazole derivatives in antiparasitic drugs.

    PubMed

    Kulik, Anna; Białecka, Wanda; Podolska, Marzena; Kwiatkowska-Puchniarz, Barbara; Mazurek, Aleksander

    2011-01-01

    The subject of the study was to develop a versatile HPLC system for identification and determination of four benzimidazole derivatives in the antiparasitic drugs. The tests covered: Zentel, Panacur, Vermox tablets and Systamex suspension. A satisfactory separation was obtained using the Nucleosil C8 column in the gradient system composed of mobile phase A: 85% orthophosphoric acid / water / acetonitrile in 0.05:75:25, v/v/v ratio, and mobile phase B: 85% orthophosphoric acid / water / acetonitrile in 0.05:50:50, v/v/v ratio. Both phases were adjusted to pH = 4.5 with 15% sodium hydroxide solution. A detection at 288 nm for oxfendazole and 254 nm for albendazole, fenbendazole and mebendazole was applied. The correlation coefficients in the range 0,9997 - 0,9999 proved that the calibration curves were linear. The method was validated in terms of selectivity, accuracy and precision. PMID:22125945

  3. HPLC-DPPH Screening Method for Evaluation of Antioxidant Compounds in Corylus Species.

    PubMed

    Riethmüller, Eszter; Könczöl, Arpad; Szakál, Dorottya; Végh, Krisztina; Balogh, György T; Kéry, Ágnes

    2016-05-01

    Corylus avellana L., C. colurna L. and C. maxima Mill. have been used in traditional medicine for a long time for the treatment of various diseases, such as phlebitis, varicose veins, haemorrhoidal symptoms and eczema. Our previous studies indicated the presence of flavonol-3-O-glycosides, diarylheptanoids and caffeic acid derivatives in the bark and leaf extracts of the three species mentioned above. Comparison of in vitro DPPH scavenging activity of the Corylus extracts prepared with ethyl acetate and methanol to those of well-known antioxidant phenolics was performed. The contribution of certain compounds to the total antioxidant activity of the extracts was investigated by developing a HPLC method coupled to the DPPH radical scavenging assay. PMID:27319139

  4. Development and Validation of Stability-indicating HPLC Method for Betamethoasone Dipropionate and Related Substances in Topical Formulation

    PubMed Central

    Vairale, A. S.; Sivaswaroop, P.; Bandana, S.

    2012-01-01

    A gradient reversed phase HPLC method was developed and validated for analysis of betamethasone dipropionate, its related substances and degradation products, using Altima C18 column (250×4.6 mm, 5 μm) with a flow rate of 1.0 ml/min and detection wavelength of 240 nm. The mobile phase A is a mixture of water, tetrahydrofuran and acetonitrile in the ratio of 90:4:6 (v/v/v) while mobile phase B is a mixture of acetonitrile, tetrahydrofuran, water and methanol in the ratio of 74:2:4:20 (v/v/v/v). The samples were analyzed using 20 μl injection volume and the column temperature was maintained at 50°. The limit of detection and limit of quantitation were found to be 0.02 μg/ml and 0.07 μg/ml, respectively. The stability-indicating capability of method was established by forced degradation studies and method demonstrated successful separation of drug, its related substances and degradation products. The method was validated as per the International Conference on Harmonization guidelines. The developed method is linear in the range of 0.07 to 200% of specification limits established for all the known related substances; betamethasone17-propionate, betamethasone 21-propionate, betamethasone 17-propionate-21-acetate (RSD <5, 2, 1%, respectively, r2=09991-0.9999 for sample concentration of 100 μg/ml). The method is sensitive, specific, linear, accurate, precise and stability indicating for the quantitation of drug, its related substances and other degradation compounds. PMID:23325990

  5. A Stability-Indicating RP-HPLC Assay Method for 5-Fluorouracil

    PubMed Central

    Sinha, V. R.; Kumar, R. V.; Bhinge, J. R.

    2009-01-01

    The present study describes the development of a validated RP-HPLC method for the determination of 5-fluorouracil in presence of its degradation products or other pharmaceutical excipients. Stress studies were performed on 5-fluorouracil and it was found that it degrades sufficiently in alkaline conditions, while negligible degradation was observed in acidic, neutral, oxidative and photolytic conditions. The peaks of the degradation products were not observed in the chromatogram due to the nonchromophoric nature of the degradation moiety formed. The separations were carried out on a C-18 reversed phase column (Phenomenex; Prodigy ODS3V, 250×4.6 mm, 5 μ) using 50mM KH2PO4 (pH, 5.0) as mobile phase at a flow rate of 1.2 ml/min and temperature of 30°. The wavelength of detection was 254 nm. A retention time of nearly 6 minutes was obtained. Analytical validation parameters such as specificity and selectivity, linearity, accuracy and precision were evaluated. The calibration curve for 5-fluorouracil was linear (r2=0.999±0.0005) from range of 10 μg/ml to 100 μg/ml. Relative standard deviation values for all the key parameters, was less than 2.0 %. The recovery of the drug after standard addition to the degraded sample was found to be 104.69%. Thus, the developed RP-HPLC method was found to be suitable for the determination of 5-fluorouracil in bulk as well as stability samples of the pharmaceutical dosage forms containing various excipients. PMID:20376215

  6. Application of a new HPLC-ICP-MS method for simultaneous determination of Al(3+) and aluminium fluoride complexes.

    PubMed

    Zioła-Frankowska, Anetta; Kuta, Jan; Frankowski, Marcin

    2015-10-01

    The paper presents the new HPLC-ICP-MS method used for conducting speciation analysis of aluminum as free Al(3+) and aluminum fluoride complexes during one analysis. In the study, 5% HNO3 was used as a derivative reagent in order to minimize the possibility of clogging the torch in ICP-MS. Using the new HPLC-ICP-MS method, speciation analysis of aluminum and aluminum fluoride complexes was conducted on the basis of model solutions and real samples (soil-water extracts and groundwater samples). The analysis in the presented analytical system lasts only 4 min. PMID:27441221

  7. Stability-Indicating HPLC Method for the Simultaneous Determination of HIV Tablet Containing Emtricitabine, Tenofovir Disoproxil Fumarate, and Rilpivirine Hydrochloride in Pharmaceutical Dosage Forms

    PubMed Central

    Venkatesan, S.; Kannappan, N.; Mannemala, Sai Sandeep

    2014-01-01

    A simple, accurate, rapid, and stability-indicating RP-HPLC method for a combination of tenofovir disoproxil fumarate, emtricitabine, and rilpivirine has been developed and subsequently validated in commercial tablets. The proposed HPLC method utilizes Phenomenex Gemini C18 column (150 mm × 4.6 mm i.d., 5 µm) and mobile phase consisting of MeCN, potassium dihydrogen phosphate buffer (20 mM, pH 3.3), and triethylamine 58.72 : 41.23 : 0.05 (v/v) at a flow rate of 1.7 mL/min. Quantitation was achieved with UV detection at 270 nm. The method was validated in terms of accuracy, precision, linearity, limits of detection, limits of quantitation, and robustness. This optimized method has been successively applied to pharmaceutical formulation and no interference from the tablet excipients was found. TDF, EMT, and RPV and their combination drug product were subjected to acid, base, neutral hydrolysis, oxidation, dry heat, and photolytic stress conditions and the stressed samples were analyzed by the proposed method. As the proposed LC method could effectively separate the drugs from its degradation products, it can be employed as stability-indicating method for the determination of instability of these drugs in bulk and commercial tablets.

  8. Rapid Analysis of Glibenclamide Using an Environmentally Benign Stability-Indicating RP-HPLC Method

    PubMed Central

    Haq, Nazrul; Alanazi, Fars Kaed; Alsarra, Ibrahim Abdullah; Shakeel, Faiyaz

    2014-01-01

    An environmentally benign RP-HPLC approach for rapid analysis of glibenclamide in pure form, developed nanoemulsion and commercial tablets was developed and validated in present investigation. The green chromatographic identification was performed on Lichrosphere 250 X 4.0 mm RP C8 column having a 5 μm packing as a stationary phase using a combination of ethanol: methanol (50:50 % v/v) as a mobile phase, at a flow rate of 1.0 mL/min with UV detection at 245 nm. The proposed method was validated for linearity, selectivity, accuracy, precision, robustness, sensitivity and specificity as per international conference on harmonization (ICH) guidelines. The utility of proposed method was verified by assay of glibenclamide in developed nanoemulsion and commercial tablets. The proposed method was found to be satisfactory in terms of selectivity, precision, accuracy, robustness, sensitivity and specificity. The content of glibenclamide in developed nanoemulsion and commercial tablets was found to be 100.50 % and 99.15 % respectively. The proposed method successfully resoled glibenclamide peak in the presence of its all type of degradation products which indicated stability-indicating property of the proposed method. These results indicated that the green chromatographic method could be successfully employed for routine analysis of glibenclamide in pure drug and various commercial formulations. PMID:25276186

  9. New HPLC and fluorometric methods for the determination of pyriproxyfen and pyridalyl insecticide residues in tomatoes.

    PubMed

    Farouk, Maha; Hussein, Lobna A; El Azab, Noha F

    2014-01-01

    Two sensitive, selective, and precise methods for the determination of pyriproxyfen and pyridalyl insecticide residues in tomatoes have been developed. The first method is HPLC with UV detection in which pyriproxyfen and pyridalyl were extracted with ethyl acetate and acetone, respectively, followed by cleanup using column chromatography. The recoveries ranged from 86.03 to 94.55 for pyriproxyfen and 95.08 to 99.38% for pyridalyl in tomato samples. The LOD of the method was 0.217 ppm for pyriproxyfen and 0.1866 ppm for pyridalyl. The second method depends on direct fluorometric determination of pyriproxyfen and pyridalyl in acetic and sulfuric acid at excitation and emission wavelengths of 320 and 646 nm, respectively. The recoveries of pyriproxyfen and pyridalyl in tomato samples ranged from 88 to 98% and 86 to 93%, respectively. The LOD of the method was 0.146 ppm for pyriproxyfen and 0.078 ppm for pyridalyl. Both methods were applied successfully to determine residues and rate of disappearance of pyriproxyfen and pyridalyl from tomatoes. PMID:24672877

  10. Evaluation of extraction methods for ochratoxin A detection in cocoa beans employing HPLC.

    PubMed

    Mishra, Rupesh K; Catanante, Gaëlle; Hayat, Akhtar; Marty, Jean-Louis

    2016-01-01

    Cocoa is an important ingredient for the chocolate industry and for many food products. However, it is prone to contamination by ochratoxin A (OTA), which is highly toxic and potentially carcinogenic to humans. In this work, four different extraction methods were tested and compared based on their recoveries. The best protocol was established which involves an organic solvent-free extraction method for the detection of OTA in cocoa beans using 1% sodium hydrogen carbonate (NaHCO3) in water within 30 min. The extraction method is rapid (as compared with existing methods), simple, reliable and practical to perform without complex experimental set-ups. The cocoa samples were freshly extracted and cleaned-up using immunoaffinity column (IAC) for HPLC analysis using a fluorescence detector. Under the optimised condition, the limit of detection (LOD) and limit of quantification (LOQ) for OTA were 0.62 and 1.25 ng ml(-1) respectively in standard solutions. The method could successfully quantify OTA in naturally contaminated samples. Moreover, good recoveries of OTA were obtained up to 86.5% in artificially spiked cocoa samples, with a maximum relative standard deviation (RSD) of 2.7%. The proposed extraction method could determine OTA at the level 1.5 µg kg(-)(1), which surpassed the standards set by the European Union for cocoa (2 µg kg(-1)). In addition, an efficiency comparison of IAC and molecular imprinted polymer (MIP) column was also performed and evaluated. PMID:26829387

  11. Accurate Quantification of Selenoprotein P (SEPP1) in Plasma Using Isotopically Enriched Seleno-peptides and Species-Specific Isotope Dilution with HPLC Coupled to ICP-MS/MS.

    PubMed

    Deitrich, Christian L; Cuello-Nuñez, Susana; Kmiotek, Diana; Torma, Frank Attila; Del Castillo Busto, Maria Estela; Fisicaro, Paola; Goenaga-Infante, Heidi

    2016-06-21

    A novel strategy for the absolute quantification of selenium (Se) included in selenoprotein P (SEPP1), an important biomarker for human nutrition and disease, including diabetes and cancer, is presented here for the first time. It is based on the use of species-specific double isotope dilution mass spectrometry (SSIDA) in combination with HPLC-ICP-MS/MS for the determination of protein bound Se down to the peptide level in a complex plasma matrix with a total content of Se of 105.5 μg kg(-1). The method enabled the selective Se speciation analysis of human plasma samples without the need of extensive cleanup or preconcentration steps as required for traditional protein mass spectrometric approaches. To assess the method accuracy, two plasma reference materials, namely, BCR-637 and SRM1950, for which literature data and a reference value for SEPP1 have been reported, were analyzed using complementary hyphenated methods and the species-specific approach developed in this work. The Se mass fractions obtained via the isotopic ratios (78)Se/(76)Se and (82)Se/(76)Se for each of the Se-peptides, namely, ENLPSLCSUQGLR (ENL) and AEENITESCQUR (AEE) (where U is SeCys), were found to agree within 2.4%. A relative expanded combined uncertainty (k = 2) of 5.4% was achieved for a Se (as SEPP1) mass fraction of approximately 60 μg kg(-1). This work represents a systematic approach to the accurate quantitation of plasma SEPP1 at clinical levels using SSIDA quantification. Such methodology will be invaluable for the certification of reference materials and the provision of reference values to clinical measurements and clinical trials. PMID:27108743

  12. How Accurately Do Spectral Methods Estimate Effective Elastic Thickness?

    NASA Astrophysics Data System (ADS)

    Perez-Gussinye, M.; Lowry, A. R.; Watts, A. B.; Velicogna, I.

    2002-12-01

    The effective elastic thickness, Te, is an important parameter that has the potential to provide information on the long-term thermal and mechanical properties of the the lithosphere. Previous studies have estimated Te using both forward and inverse (spectral) methods. While there is generally good agreement between the results obtained using these methods, spectral methods are limited because they depend on the spectral estimator and the window size chosen for analysis. In order to address this problem, we have used a multitaper technique which yields optimal estimates of the bias and variance of the Bouguer coherence function relating topography and gravity anomaly data. The technique has been tested using realistic synthetic topography and gravity. Synthetic data were generated assuming surface and sub-surface (buried) loading of an elastic plate with fractal statistics consistent with real data sets. The cases of uniform and spatially varying Te are examined. The topography and gravity anomaly data consist of 2000x2000 km grids sampled at 8 km interval. The bias in the Te estimate is assessed from the difference between the true Te value and the mean from analyzing 100 overlapping windows within the 2000x2000 km data grids. For the case in which Te is uniform, the bias and variance decrease with window size and increase with increasing true Te value. In the case of a spatially varying Te, however, there is a trade-off between spatial resolution and variance. With increasing window size the variance of the Te estimate decreases, but the spatial changes in Te are smeared out. We find that for a Te distribution consisting of a strong central circular region of Te=50 km (radius 600 km) and progressively smaller Te towards its edges, the 800x800 and 1000x1000 km window gave the best compromise between spatial resolution and variance. Our studies demonstrate that assumed stationarity of the relationship between gravity and topography data yields good results even in

  13. Single dose pharmacokinetics of atorvastatin oral formulations using a simple HPLC-UV method.

    PubMed

    Sohail, Muhammad; Ahmad, Mahmood; Minhas, Muhammad Usman

    2016-07-01

    The study was aimed to assess pharmacokinetics of atorvastatin (40 mg) in healthy fasted human subjects by a simple and inexpensive high performance liquid chromatography. Experimental design of the study was a randomized, two way, two periods, crossover study (single dose in fasted conditions). Eighteen (18) healthy male volunteers were enrolled according to FDA guidelines. The plasma samples were assayed using an isocratic High Performance Liquid Chromatography (HPLC) system of Agilent technologies USA consisted of an isocratic pump with column of Thermo Electron Corporation USA (ODS hypersil C(18) 4.6 mm x 250 mm), a UV-visible detector set at λ(max) 237 nm. Maximum plasma concentrations (C(max)) of atorvastatin (Mean ± SEM) for the reference product (A) found to be 13.739±0.210ng/ml & 13.374±0.145ng/ml for test product (B). T(max) values (Mean±SEM) of atorvastatin were 1.222 ±0.060 hours and 1.167±0.057 hours for reference and test products, respectively. The values of AUC(0-oo) (Mean ± SEM) for the reference (A) and test product (B) were 73.955 ± 1.715ng.h/ml and 77.773 ± 1.858ng. h/ml, respectively. Other pharmacokinetic parameters of both products were also determined. A statistical non-significant difference between pharmacokinetic parameters has been found and both brands of atorvastatin showed the same rate and extent of absorption in healthy fasted human volunteers after single dose. A simple and cost effective HPLC method was developed and applied. PMID:27393428

  14. A rapid HPLC method for simultaneous determination of tretinoin and isotretinoin in dermatological formulations.

    PubMed

    Tashtoush, Bassam M; Jacobson, Elaine L; Jacobson, Myron K

    2007-02-19

    A rapid method using an isocratic high-pressure liquid chromatography and UV detection for determination of both all-trans retinoic acid (tretinoin) and 13-cis retinoic acid (isotretinoin) in dermatological preparations is presented. Tretinoin and isotretinoin samples were extracted with acetonitrile by a procedure that can be completed in less than 10 min. Subsequent separation and quantification of amounts as low as 10 pmol was accomplished in less than 15 min using reversed-phase HPLC with isocratic elution with 0.01% trifluoroacetic acid (TFA)/acetonitrile (15:85, v/v). Validation experiments confirmed the precision and accuracy of the method. When applied to commercial tretinoin samples, recoveries of 104.9% for cream formulations and 107.7% for gel formulations were obtained. Application of the method for analysis of a tretinoin cream exposed to solar simulated light (SSL) demonstrated detection of the major photoisomerization product isotretinoin as well as 9-cis retinoic acid, demonstrating the utility of the method for studies of tretinoin photostability. The method should also facilitate studies of the formulation compatibility and photocompatibility of tretinoin with agents that may improve its clinical tolerability. PMID:17045442

  15. Development of complementary HPLC-DAD/APCI MS methods for chemical characterization of pharmaceutical packaging materials.

    PubMed

    Petruševski, V; Jolevska, S T; Ribarska, J T; Chachorovska, M; Petkovska, A; Ugarković, S

    2016-05-30

    The chemical characterization of plastics for pharmaceutical packaging has been subject to ever increasing regulatory scrutiny, the reasons for which being: a) plastic additives and degradation products can be extremely hazardous to the patients' health (especially patients on chronic therapy) and b) they offer no therapeutic or formulatory benefit whatsoever. The last decade has seen the issuing of several books, monographs and guidelines dealing with extractables and leachables, however the amount of scientific work done so far is still fairly small (the majority of it performed by only a few research groups), with only a small number of methods published in the literature. This work focuses on developing a set of two complementary HPLC-DAD/APCI MS methods for simultaneous separation, detection, identification and quantification of a wide variety of packaging additives and degradants, the second method specifically targeting a group of compounds known as polymeric hindered amine light stabilizers (HALS), which are known to be notoriously difficult to separate and analyze with standard analytical techniques. The methods are capable of detecting plastic additives present in low ppb concentrations, from samples extracted in solvents with various polarities and pH values. Both methods were developed and optimized using system suitability mixtures comprised of 9 additives commonly encountered in plastic materials, and their practical applicability tested on a variety of extracts from low-density polyethylene (LDPE) and polypropylene (PP), where several additives were successfully separated, detected and identified. PMID:26966896

  16. NMR method for accurate quantification of polysorbate 80 copolymer composition.

    PubMed

    Zhang, Qi; Wang, Aifa; Meng, Yang; Ning, Tingting; Yang, Huaxin; Ding, Lixia; Xiao, Xinyue; Li, Xiaodong

    2015-10-01

    (13)C NMR spectroscopic integration employing short relaxation delays and a 30° pulse width was evaluated as a quantitative tool for analyzing the components of polysorbate 80. (13)C NMR analysis revealed that commercial polysorbate 80 formulations are a complex oligomeric mixture of sorbitan polyethoxylate esters and other intermediates, such as isosorbide polyethoxylate esters and poly(ethylene glycol) (PEG) esters. This novel approach facilitates the quantification of the component ratios. In this study, the ratios of the three major oligomers in polysorbate 80 were measured and the PEG series was found to be the major component of commercial polysorbate 80. The degree of polymerization of -CH2CH2O- groups and the ratio of free to bonded -CH2CH2O- end groups, which correlate with the hydrophilic/hydrophobic nature of the polymer, were analyzed, and were suggested to be key factors for assessing the likelihood of adverse biological reactions to polysorbate 80. The (13)C NMR data suggest that the feed ratio of raw materials and reaction conditions in the production of polysorbate 80 are not well controlled. Our results demonstrate that (13)C NMR is a universal, powerful tool for polysorbate analysis. Such analysis is crucial for the synthesis of a high-quality product, and is difficult to obtain by other methods. PMID:26356097

  17. A bioanalytical HPLC method for coumestrol quantification in skin permeation tests followed by UPLC-QTOF/HDMS stability-indicating method for identification of degradation products.

    PubMed

    Bianchi, Sara E; Teixeira, Helder F; Kaiser, Samuel; Ortega, George G; Schneider, Paulo Henrique; Bassani, Valquiria L

    2016-05-01

    Coumestrol is present in several species of the Fabaceae family widely distributed in plants. The estrogenic and antioxidant activities of this molecule show its potential as skin anti-aging agent. These characteristics reveal the interest in developing analytical methodology for permeation studies, as well as to know the stability of coumestrol identifying the major degradation products. Thus, the present study was designed, first, to develop and validate a versatile liquid chromatography (HPLC) method to quantify coumestrol in a hydrogel formulation in different porcine skin layers (stratum corneum, epidermis, and dermis) in permeation tests. In the stability-indicating test coumestrol samples were exposed to stress conditions: temperature, UVC light, oxidative, acid and alkaline media. The degradation products, as well as the constituents extracted from the hydrogel, adhesive tape or skin were not eluted in the retention time of the coumestrol. Hence, the HPLC method showed to be versatile, specific, accurate, precise and robust showing excellent performance for quantifying coumestrol in complex matrices involving skin permeation studies. Coumestrol recovery from porcine ear skin was found to be in the range of 97.07-107.28μg/mL; the intra-day precision (repeatability) and intermediate precision (inter-day precision), respectively lower than 4.71% and 2.09%. The analysis using ultra-performance liquid chromatography coupled to a quadrupole time-of-flight high definition mass spectrometry detector (UPLC-QTOF/HDMS) suggest the MS fragmentation patterns and the chemical structure of the main degradation products. These results represent new and relevant findings for the development of coumestrol pharmaceutical and cosmetic products. PMID:27010353

  18. Optimization of HPLC method for determination of cefixime using 2-thiophenecarboxaldehyde as derivatizing reagent: A new approach.

    PubMed

    Maheshwari, Madan Lal; Memon, Ayaz Ali; Memon, Shahabuddin; Memon, Fakhar-Un-Nisa; Mughal, Ubed Ur Rahman; Dayo, Abdullah; Memon, Naheed; Ghoto, Mohammed Ali; Khan Leghari, M

    2015-09-01

    The determination of cefixime 1 has clinical and analytical importance due to its broad spectrum antimicrobial activity and stability. Cefixime is a significant member of orally active third generation cephalosporin and has excellent activity against many pathogens. It is for first time that we have developed a new HPLC-DAD method for analysis of imine derivative 3 of cefixime by using reflux method at 100 °C for 50 min without any buffer solution. 2 Thiophenecarboxaldehyde (2TCA) 2 was used first time as a derivatizing reagent for cefixime drug. Furthermore, separation of three components, i.e. drug (cefixime), reagent (2TCA) and derivative was carried out using kromasil 100 C-18 (15 mm × 0.46 mm, 5 μm) column with isocratic elution of methanol: 0.1% aqueous formic acid (70:30 v/v) with flow rate of 1 ml min(-) (1) at retention time of 1.8, 2.4 and 3.3 min, respectively; while, total run time was 5 min. The developed method was repeatable with a relative standard deviation (RSD) of 0.81-1.88% for imine derivative. The limit of detection and quantification of imine derivative 3 were obtained within the range of 0.132-0.401 μg ml(-) (1) and compared with cefixime drug as 0.30-0.90 μg ml(-1), respectively. However, the formation of imine derivative 3 was confirmed by comparing peak height, retention time and spectral changes. The method is rapid, simple, very stable and accurate for the separation and determination of imine derivative 3 of cefixime 1. PMID:27134548

  19. Stability indicating HPLC-UV method for determination of dapoxetine HCl in pharmaceutical product.

    PubMed

    Liew, Kai Bin; Peh, Kok Khiang

    2014-01-01

    A stability-indicating HPLC-UV method for the determination of dapoxetine hydrochloride in solution and pharmaceutical product was developed. The mobile phase was composed of acetonitrile and 0.2 M ammonium acetate buffer at 50 : 50 ratio. The chromatographic parameters, theoretical plates (N), tailing factor (T), capacity factor (k') and peak asymmetry factor (As) were calculated. Stress degradation studies, namely, acid, alkali, oxidation, heat and UV light, were performed. The analyte was eluted at 5.8 min using gradient system at a flow rate of 1.5 mL/min. The theoretical plates count was > 2000, tailing factor < 1.54, capacity factor > 5.38 and peak asymmetry factor was < 1.10. The method was linear from 1 to 40 microg/mL with a correlation coefficient of 0.9994. The intraday precision and accuracy values were 0.14-1.54% and 0.63-1.83%, respectively. On the other hand, the interday precision and accuracy results were 0.49-1.83% and 1.15-1.85%, respectively. The drug solution was stable at ambient room temperature (26 degrees C) for 48 h. Dapoxetine HCI was found susceptible to oxidation and degraded slightly under acid and alkali conditions but was stable under UV light and heat. No interference from tablet excipiets and degradation products was found. Hence, the method can be employed as a stability-indicating method for the determination of dapoxetine HCl in pharmaceutical products. PMID:25265818

  20. HPLC-UV method validation for the identification and quantification of bioactive amines in commercial eggs.

    PubMed

    de Figueiredo, Tadeu Chaves; de Assis, Débora Cristina Sampaio; Menezes, Liliane Denize Miranda; da Silva, Guilherme Resende; Lanza, Isabela Pereira; Heneine, Luiz Guilherme Dias; Cançado, Silvana de Vasconcelos

    2015-09-01

    A quantitative and confirmatory high-performance liquid chromatography with ultraviolet detection (HPLC-UV) method for the determination of bioactive amines in the albumen and yolk of commercial eggs was developed, optimized and validated by analyte extraction with trichloroacetic acid and pre-column derivatization with dansyl chloride. Phenylethylamine, putrescine, cadaverine, histamine, tyramine, spermidine and spermine standards were used to evaluate the following performance parameters: limit of detection (LoD), limit of quantification (LoQ), selectivity, linearity, precision, recovery and ruggedness. The LoD of the method was defined from 0.2 to 0.3 mg kg(-1) for the yolk matrix and from 0.2 to 0.4 mg kg(-1) for the albumen matrix; the LoQ was from 0.7 to 1.0 mg kg(-1) for the yolk matrix and from 0.7 to 1.1 mg kg(-1) for the albumen matrix. The validated method exhibited excellent selectivity and separation of all amines with coefficients of determination higher than 0.99. The obtained recovery values were from 90.5% to 108.3%, and the relative standard deviation (RSD) was lower than 10% under repeatability conditions for the studied analytes. The performance parameters show the validated method to be adequate for the determination of bioactive amines in egg albumen and yolk. PMID:26003718

  1. Development and Validation of Stability-indicating HPLC Method for Simultaneous Estimation of Cefixime and Linezolid

    PubMed Central

    Patel, Nidhi S.; Tandel, Falguni B.; Patel, Yogita D.; Thakkar, Kartavya B.

    2014-01-01

    A stability-indicating reverse phase high performance liquid chromatography method was developed and validated for cefixime and linezolid. The wavelength selected for quantitation was 276 nm. The method has been validated for linearity, accuracy, precision, robustness, limit of detection and limit of quantitation. Linearity was observed in the concentration range of 2-12 μg/ml for cefixime and 6-36 μg/ml for linezolid. For RP-HPLC, the separation was achieved by Phenomenex Luna C18 (250×4.6 mm) 5 μm column using phosphate buffer (pH 7):methanol (60:40 v/v) as mobile phase with flow rate 1 ml/min. The retention time of cefixime and linezolid were found to be 3.127 min and 11.986 min, respectively. During force degradation, drug product was exposed to hydrolysis (acid and base hydrolysis), H2O2, thermal degradation and photo degradation. The % degradation was found to be 10 to 20% for both cefixime and linezolid in the given condition. The method specifically estimates both the drugs in presence of all the degradants generated during forced degradation study. The developed methods were simple, specific and economic, which can be used for simultaneous estimation of cefixime and linezolid in tablet dosage form. PMID:25593387

  2. Development and Validation of Stability-indicating HPLC Method for Simultaneous Estimation of Cefixime and Linezolid.

    PubMed

    Patel, Nidhi S; Tandel, Falguni B; Patel, Yogita D; Thakkar, Kartavya B

    2014-01-01

    A stability-indicating reverse phase high performance liquid chromatography method was developed and validated for cefixime and linezolid. The wavelength selected for quantitation was 276 nm. The method has been validated for linearity, accuracy, precision, robustness, limit of detection and limit of quantitation. Linearity was observed in the concentration range of 2-12 μg/ml for cefixime and 6-36 μg/ml for linezolid. For RP-HPLC, the separation was achieved by Phenomenex Luna C18 (250×4.6 mm) 5 μm column using phosphate buffer (pH 7):methanol (60:40 v/v) as mobile phase with flow rate 1 ml/min. The retention time of cefixime and linezolid were found to be 3.127 min and 11.986 min, respectively. During force degradation, drug product was exposed to hydrolysis (acid and base hydrolysis), H2O2, thermal degradation and photo degradation. The % degradation was found to be 10 to 20% for both cefixime and linezolid in the given condition. The method specifically estimates both the drugs in presence of all the degradants generated during forced degradation study. The developed methods were simple, specific and economic, which can be used for simultaneous estimation of cefixime and linezolid in tablet dosage form. PMID:25593387

  3. A stability-indicating HPLC method for simultaneous determination of morphine and naltrexone.

    PubMed

    Jafari-Nodoushan, Milad; Barzin, Jalal; Mobedi, Hamid

    2016-02-01

    This study developed a stability-indicating reversed-phase HPLC method for the simultaneous determination of morphine sulfate and naltrexone hydrochloride content in bulk, Solid dosage forms and in-vitro dissolution samples to support product development and quality control efforts. Chromatographic separation of the pharmaceutical compound was achieved on a perfectSil™ MZ C18 column (250×4.6mm, 5μm) with an isocratic mobile phase composed of a mixture of acetate buffer (10mM, pH 4, containing 0.1% of 1-heptanesulfonic acid sodium salt) and acetonitrile with 80/20 at a flow rate of 1.5mlmin(-1). Both analytes were quantified using a photodiode array detector set at a wavelength of 280nm and column temperature was set to 30°C. naltrexone, morphine and a mixture of the two were subjected to thermal, peroxide, acid, base and photolytic degradation and their peak homogeneity was obtained using a photodiode array detector, demonstrating the specificity of method. These pharmaceuticals were spiked in biological fluid to examine method selectivity. The method was validated for system suitability, linearity, accuracy, precision, detection and quantification limits and robustness and was found it is acceptable in range of 2-250μgml(-1) for morphine and 4-100μgml(-1) for naltrexone. PMID:26773883

  4. AN IMPROVED HPLC-MS/MS METHOD FOR DETERMINATION OF ISOXAFLUTOLE (BALANCE) AND ITS METABOLITES IN SOILS AND FORAGE PLANTS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    An analytical method using turbo-spray and heat-nebulizer high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was developed for the analysis of isoxaflutole (IXF) and its two metabolites, diketonitrile (DKN) and the benzoic acid metabolite (BA), at sub 'g/kg levels in soil a...

  5. Analytical methods for determination of alkaloids and saponins from roots of Caulophyllum thalictroids (L) Michx using UPLC HPLC and HPTLC

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A comparison study of analytical methods including HPLC, UPLC and HPTLC are presented in this paper for the determination of major alkaloid and triterpene saponins from the roots of Caulophyllum thalictroides (L.) Michx. (blue cohosh) and dietary supplements claiming to contain blue cohosh. The meth...

  6. Simultaneous HPLC determination of 22 components of essential oils; method robustness with experimental design.

    PubMed

    Porel, A; Sanyal, Y; Kundu, A

    2014-01-01

    The aim of the present study was the development and validation of a simple, precise and specific reversed phase HPLC method for the simultaneous determination of 22 components present in different essential oils namely cinnamon bark oil, caraway oil and cardamom fruit oil. The chromatographic separation of all the components was achieved on Wakosil-II C18 column with mixture of 30 mM ammonium acetate buffer (pH 4.7), methanol and acetonitrile in different ratio as mobile phase in a ternary linear gradient mode. The calibration graphs plotted with five different concentrations of each component were linear with a regression coefficient R(2) >0.999. The limit of detection and limit of quantitation were estimated for all the components. Effect on analytical responses by small and deliberate variation of critical factors was examined by robustness testing with Design of Experiment employing Central Composite Design and established that this method was robust. The method was then validated for linearity, precision, accuracy, specificity and demonstrated to be applicable to the determination of the ingredients in commercial sample of essential oil. PMID:24799735

  7. Validation of an HPLC method for direct measurement of steviol equivalents in foods.

    PubMed

    Bartholomees, Uria; Struyf, Tom; Lauwers, Olivier; Ceunen, Stijn; Geuns, Jan M C

    2016-01-01

    Steviol glycosides are intense natural sweeteners used in foods and beverages. Their acceptable daily intake, expressed as steviol equivalents, is set at 0-4 mg/kg body weight. We report the development and validation of a RP-HPLC method with fluorometric detection of derivatized isosteviol, formed by acid hydrolysis of steviol glycosides. Dihydroisosteviol was used as an internal standard. Using this method, the amount of steviol equivalents in commercial steviol glycoside mixtures and different foods can be directly quantified. The method was successfully tested on strawberry jam, low-fat milk, soft drink, yogurt and a commercial mixture of steviol glycosides. Calibration curves were linear between 0.01 and 1.61 mM steviol equivalents, with a quantification limit of 0.2 nmol. The % RSD of intra-day precision varied between 0.4% and 4%, whereas inter-day precision varied between 0.4% and 5%, for high and medium concentrations, and between 3% and 8% for low concentrations. Accuracy of the analysis varied between 99% and 115%. PMID:26212970

  8. Stability indicating RP-HPLC method for simultaneous determination of piroxicam and ofloxacin in binary combination.

    PubMed

    John, Peter; Azeem, Waqar; Ashfaq, Muhammad; Khan, Islam Ullah; Razzaq, Syed Naeem

    2015-09-01

    A simple and precise RP-HPLC method was developed for simultaneous determination of piroxicam and ofloxacin in pharmaceutical formulations and human serum. Optimum separations of piroxicam, ofloxacin and stress-induced degradation products were achieved by use of Hypersil BDS C8 column (250 x 4.6mm, 5 μm). The mobile phase was a mixture of acetonitrile: 0.012M K2HPO4: 0.008M sodium citrate (both buffers mixed and pH adjusted to 2.8) (50:25:25 v/v/v) delivered at flow rate of 1.5 mL min⁻¹ using DAD at 254 nm. Response was linear function of concentration over the ranges of 70-130 mg mL⁻¹ for piroxicam and ofloxacin (r² ≥ 0.999). The method efficiently separated the analytical peaks from degradation products with acceptable tailing and resolution. The developed method was successfully used for concurrent analysis of piroxicam and ofloxacin in pharmaceutical formulations, human serum and in vitro drug interaction studies. PMID:26408892

  9. A Stability Indicating HPLC Method for the Determination of Fluvoxamine in Pharmaceutical Dosage Forms

    PubMed Central

    Souri, Effat; Donyayi, Hassan; khaniha, Reza Ahmad; Barazandeh Tehrani, Maliheh

    2015-01-01

    Fluvoxamine maleate is a selective serotonin reuptake inhibitor, which is used for the treatment of different types of depressive disorders. In the present study, a stability indicating HPLC method was developed and validated for the determination of fluvoxamine maleate. The chromatographic separation was carried out using a Nova-Pak CN column and a mixture of K2HPO4 50 mM (pH 7.0) and acetonitrile (60: 40, v/v) as the mobile phase. Target compounds were detected using a UV detector set at 235 nm. The developed method was linear over the concentration range of 1-80 μg/ml with acceptable precision (CV values < 2.0%) and accuracy (error values < 1.6%). The degradation studies showed that fluvoxamine maleate is relatively unstable under acidic, basic and oxidative conditions and also when exposed to UV radiation. On the other hand, the bulk powder of fluvoxamine maleate was relatively stable when exposed to visible light or heat. The proposed method was successfully applied for the determination of active ingredient of fluvoxamine dosage form without any interference from tablet excipients. PMID:26664372

  10. A Stability Indicating HPLC Method for the Determination of Fluvoxamine in Pharmaceutical Dosage Forms.

    PubMed

    Souri, Effat; Donyayi, Hassan; Khaniha, Reza Ahmad; Barazandeh Tehrani, Maliheh

    2015-01-01

    Fluvoxamine maleate is a selective serotonin reuptake inhibitor, which is used for the treatment of different types of depressive disorders. In the present study, a stability indicating HPLC method was developed and validated for the determination of fluvoxamine maleate. The chromatographic separation was carried out using a Nova-Pak CN column and a mixture of K2HPO4 50 mM (pH 7.0) and acetonitrile (60: 40, v/v) as the mobile phase. Target compounds were detected using a UV detector set at 235 nm. The developed method was linear over the concentration range of 1-80 μg/ml with acceptable precision (CV values < 2.0%) and accuracy (error values < 1.6%). The degradation studies showed that fluvoxamine maleate is relatively unstable under acidic, basic and oxidative conditions and also when exposed to UV radiation. On the other hand, the bulk powder of fluvoxamine maleate was relatively stable when exposed to visible light or heat. The proposed method was successfully applied for the determination of active ingredient of fluvoxamine dosage form without any interference from tablet excipients. PMID:26664372

  11. Simultaneous HPLC Determination of 22 Components of Essential Oils; Method Robustness with Experimental Design

    PubMed Central

    Porel, A.; Sanyal, Y.; Kundu, A.

    2014-01-01

    The aim of the present study was the development and validation of a simple, precise and specific reversed phase HPLC method for the simultaneous determination of 22 components present in different essential oils namely cinnamon bark oil, caraway oil and cardamom fruit oil. The chromatographic separation of all the components was achieved on Wakosil–II C18 column with mixture of 30 mM ammonium acetate buffer (pH 4.7), methanol and acetonitrile in different ratio as mobile phase in a ternary linear gradient mode. The calibration graphs plotted with five different concentrations of each component were linear with a regression coefficient R2 >0.999. The limit of detection and limit of quantitation were estimated for all the components. Effect on analytical responses by small and deliberate variation of critical factors was examined by robustness testing with Design of Experiment employing Central Composite Design and established that this method was robust. The method was then validated for linearity, precision, accuracy, specificity and demonstrated to be applicable to the determination of the ingredients in commercial sample of essential oil. PMID:24799735

  12. Comparative analysis of lycorine in wild plant and callus culture samples of Hymenocallis littoralis by HPLC-UV method.

    PubMed

    Subramaniam, Sreeramanan; Sundarasekar, Jeevandran; Sahgal, Geethaa; Murugaiyah, Vikneswaran

    2014-01-01

    The Hymenocallis littoralis, an ornamental and medicinal plant, had been traditionally used for wound healing. In the present study, an analytical method using HPLC with ultraviolet detection was developed for the quantification of lycorine in the extracts of different parts of wild plant and tissue culture samples of H. littoralis. The separation was achieved using a reversed-phase column. The method was found to be accurate, repeatable, and sensitive for the quantification of minute amount of lycorine present in the samples. The highest lycorine content was found in the bulb extract (2.54 ± 0.02 μg/mg) whereas the least was in the root extract (0.71 ± 0.02 μg/mg) of the wild plants. Few callus culture samples had high content of lycorine, comparable to that of wild plants. The results showed that plant growth regulators, 2,4-dichlorophenoxyacetic acid (2,4-D) alone at 4.5 μM (2.58 ± 0.38 μg/mg) or a combination of 2,4-D at 9.00 μM with 4.5 μM of 6-benzylaminopurine (BAP), were the optimum concentrations for the production of high lycorine (2.45 ± 0.15 μg/mg) content in callus culture. The present analytical method could be of value for routine quantification of lycorine in the tissue culture production and standardization of the raw material or extracts of H. littoralis. PMID:24895650

  13. Comparative Analysis of Lycorine in Wild Plant and Callus Culture Samples of Hymenocallis littoralis by HPLC-UV Method

    PubMed Central

    Sahgal, Geethaa; Murugaiyah, Vikneswaran

    2014-01-01

    The Hymenocallis littoralis, an ornamental and medicinal plant, had been traditionally used for wound healing. In the present study, an analytical method using HPLC with ultraviolet detection was developed for the quantification of lycorine in the extracts of different parts of wild plant and tissue culture samples of H. littoralis. The separation was achieved using a reversed-phase column. The method was found to be accurate, repeatable, and sensitive for the quantification of minute amount of lycorine present in the samples. The highest lycorine content was found in the bulb extract (2.54 ± 0.02 μg/mg) whereas the least was in the root extract (0.71 ± 0.02 μg/mg) of the wild plants. Few callus culture samples had high content of lycorine, comparable to that of wild plants. The results showed that plant growth regulators, 2,4-dichlorophenoxyacetic acid (2,4-D) alone at 4.5 μM (2.58 ± 0.38 μg/mg) or a combination of 2,4-D at 9.00 μM with 4.5 μM of 6-benzylaminopurine (BAP), were the optimum concentrations for the production of high lycorine (2.45 ± 0.15 μg/mg) content in callus culture. The present analytical method could be of value for routine quantification of lycorine in the tissue culture production and standardization of the raw material or extracts of H. littoralis. PMID:24895650

  14. Development and Validation of a Precise, Single HPLC Method for the Determination of Tolperisone Impurities in API and Pharmaceutical Dosage Forms

    PubMed Central

    Raju, Thummala Veera Raghava; Seshadri, Raja Kumar; Arutla, Srinivas; Mohan, Tharlapu Satya Sankarsana Jagan; Rao, Ivaturi Mrutyunjaya; Nittala, Someswara Rao

    2013-01-01

    A novel, sensitive, stability-indicating HPLC method has been developed for the quantitative estimation of Tolperisone-related impurities in both bulk drugs and pharmaceutical dosage forms. Effective chromatographic separation was achieved on a C18 stationary phase with a simple mobile phase combination delivered in a simple gradient programme, and quantitation was by ultraviolet detection at 254 nm. The mobile phase consisted of a buffer and acetonitrile delivered at a flow rate 1.0 ml/min. The buffer consisted of 0.01 M potassium dihydrogen phosphate with the pH adjusted to 8.0 by using diethylamine. In the developed HPLC method, the resolution between Tolperisone and its four potential impurities was found to be greater than 2.0. Regression analysis showed an R value (correlation coefficient) of greater than 0.999 for the Tolperisone impurities. This method was capable of detecting all four impurities of Tolperisone at a level of 0.19 μg/mL with respect to the test concentration of 1000 μg/mL for a 10 µl injection volume. The tablets were subjected to the stress conditions of hydrolysis, oxidation, photolysis, and thermal degradation. Considerable degradation was found to occur in base hydrolysis, water hydrolysis, and oxidation. The stress samples were assayed against a qualified reference standard and the mass balance was found to be close to 100%. The established method was validated and found to be linear, accurate, precise, specific, robust, and rugged. PMID:23641333

  15. Stability-Indicating RP-HPLC Method for the Determination of Ambrisentan and Tadalafil in Pharmaceutical Dosage Form

    PubMed Central

    Patel, Jayvadan K.; Patel, Nilam K.

    2014-01-01

    Abstract A simple, rapid, and highly selective RP-HPLC method was developed for the simultaneous determination of Ambrisentan (AMB) and Tadalafil (TADA) drug substances in the fixed dosage strength of 10 mg and 40 mg, respectively. Effective chromatographic separation was achieved using a Hypersil GOLD C18 column (150 mm × 4.6 mm internal diameter, 5 μm particle size) with a mobile phase composed of methanol, water, and acetonitrile in the ratio of 40:40:20 (by volume). The mobile phase was pumped using a gradient HPLC system at a flow rate of 0.5 mL/min, and quantification of the analytes was based on measuring their peak areas at 260 nm. The retention times for Ambrisentan and Tadalafil were about 2.80 and 7.10 min, respectively. The reliability and analytical performance of the proposed HPLC procedure were statistically validated with respect to system suitability, linearity, ranges, precision, accuracy, specificity, robustness, detection, and quantification limits. Calibration curves were linear in the ranges of 1–20 μg/mL for Ambrisentan and 4–80 μg/mL for Tadalafil with correlation coefficients >0.990. The proposed method proved to be selective and stability-indicating by the resolution of the two analytes from the forced degradation (hydrolysis, oxidation, and photolysis) products. The validated HPLC method was successfully applied to the analysis of AMB and TADA in pharmaceutical dosage form. PMID:26279975

  16. [Application of HPLC-UV method for aripiprazole determination in serum].

    PubMed

    Synowiec, Anna; Gomółka, Ewa; Zyss, Tomasz; Zieba, Andrzej; Florek, Ewa; Piekoszewski, Wojciech

    2012-01-01

    Aripiprazole is a new drug applied in schizophrenia treatment. There are not strict indications for aripiprazole therapeutic drug monitoring. Despite, serum aripiprazole measuring would help control the drug doses effectiveness. The drug monitoring can eliminate overdosing, adverse effects and let control proper drug ingestion. The aim of the paper was to develop a simple method for aripiprazole determination in serum for therapeutic drug monitoring. High performance liquid chromatography with spectrophotometric detection (HPLC-UV) was used. Resolution was performed on LC-8 column; moving phase was solution 0,025M trimethylammonium buffer: acetonitrile (62:38). Isocratic flow was 1,2 ml/min; internal standard (IS) was promazine; monitored wavelength was lambda=214 nm. The validation parameters were: limits of linearity (LOL) 100-800 ng/ml, limit of detection (LOD) 10 ng/ml, limit of quantity (LOQ) 100 ng/ml. Coefficient of variation (CV) describing accuracy and precision didn't cross 10%. The method was useful for therapeutic drug monitoring in serum of patients treated with aripiprazole. PMID:23421079

  17. Validation of a HPLC method for determination of hydroxymethylfurfural in crude palm oil.

    PubMed

    Ariffin, Abdul Azis; Ghazali, H M; Kavousi, Parviz

    2014-07-01

    For the first time 5-hydroxymethyl-2-furaldehyde (HMF) was separated from crude palm oil (CPO), and its authenticity was determined using an RP-HPLC method. Separation was accomplished with isocratic elution of a mobile phase comprising water and methanol (92:8 v/v) on a Purospher Star RP-18e column (250mm×4.6mm, 5.0μm). The flow rate was adjusted to 1ml/min and detection was performed at 284nm. The method was validated, and results obtained exhibit a good recovery (95.58% to 98.39%). Assessment of precision showed that the relative standard deviations (RSD%) of retention times and peak areas of spiked samples were less than 0.59% and 2.66%, respectively. Further, the limit of detection (LOD) and LOQ were 0.02, 0.05mg/kg, respectively, and the response was linear across the applied ranges. The crude palm oil samples analysed exhibited HMF content less than 2.27mg/kg. PMID:24518321

  18. An improved extraction method for the HPLC determination of morphine and its metabolites in plasma.

    PubMed

    Pawula, M; Barrett, D A; Shaw, P N

    1993-01-01

    A new, simple and rapid extraction procedure coupled with a combined coulometric-fluorescence HPLC assay is described for the simultaneous determination of morphine (M) and morphine-3-glucuronide (M3G), morphine-6-glucuronide (M6G), and normorphine (NM) in plasma. The effect of concentration and pH of selected ion-pairing agents on the extraction of these compounds from plasma by solid-phase extraction was investigated. The extraction procedure was optimized in terms of recovery, reproducibility and lack of interference from endogenous materials. The optimized method uses tetrabutylammonium hydrogen sulphate (TBAHS) at pH 10 followed by separation on a single C18 solid-phase extraction cartridge. For routine analysis the procedure provides high and reproducible recoveries over a concentration range of 1.0-1000 ng ml-1 for morphine, M6G and normorphine and 20-1000 ng ml-1 for M3G. The method was used successfully to analyse plasma samples from a pharmacokinetic study in which sheep had received an intravenous dose of 0.015 mg kg-1 of M6G. PMID:8357878

  19. Systematic optimization of an SPE with HPLC-FLD method for fluoroquinolone detection in wastewater.

    PubMed

    He, Ke; Blaney, Lee

    2015-01-23

    This paper describes a selective and ultra-sensitive analytical method for simultaneous determination of 11 fluoroquinolone (FQ) antibiotics in environmental and wastewater samples. The method employs offline solid-phase extraction (SPE) and reversed-phase high performance liquid chromatography with fluorescence detection (HPLC-FLD). A weak cation exchange SPE protocol was developed with a novel loading volume optimization algorithm and a methanol cleanup step to remove background organic matter. Various parameters were optimized to recover FQs from water/wastewater and analyte recovery was generally greater than 80%. Chromatographic separation of the 11 FQs was achieved on a 150 mm pentafluorophenyl column using a gradient elution scheme with methanol, acetonitrile, and 20mM phosphate buffer (pH=2.4). Excitation and emission wavelengths were individually optimized for each FQ using fluorescence spectroscopy; the excitation and emission wavelengths were 276-296 nm and 444-506 nm, respectively. Instrumental quantitation limits were 20-100 pg of mass injected. Of the 11 FQs investigated, seven (i.e., ciprofloxacin, difloxacin, enrofloxacin, fleroxacin, norfloxacin, moxifloxacin, and ofloxacin) were detected during a four-month sampling campaign of wastewater and wastewater-impacted surface water. Concentrations of FQs in raw wastewater, wastewater effluent, and wastewater-impacted surface water were 5-1292, 2-504, and 4-187ng/L, respectively. PMID:25200119

  20. An improved HPLC-DAD method for clavulanic acid quantification in fermentation broths of Streptomyces clavuligerus.

    PubMed

    Ramirez-Malule, Howard; Junne, Stefan; López, Carlos; Zapata, Julian; Sáez, Alex; Neubauer, Peter; Rios-Estepa, Rigoberto

    2016-02-20

    Clavulanic acid (CA) is an important secondary metabolite commercially produced by cultivation of Streptomyces clavuligerus (Sc). It is a potent inhibitor of bacterial β-lactamases. In this work, a specific and improved high performance liquid chromatography (HPLC) method, using a C-18 reversed phase column, diode array detector and gradient elution for CA quantification in fermentation broths of Sc, was developed and successfully validated. Samples were imidazole-derivatized for the purpose of creating a stable chromophore (clavulanate-imidazole). The calibration curve was linear over a typical range of CA concentration between 0.2 and 400mg/L. The detection and quantification limits were 0.01 and 0.02mg/L, respectively. The precision of the method was evaluated for CA spiked into production media and a recovery of 103.8%, on average, was obtained. The clavulanate-imidazole complex was not stable when the samples were not cooled during the analysis. The recovery rate was 39.3% on average. This assay was successfully tested for CA quantification in samples from Sc fermentation, using both, a chemically defined and a complex medium. PMID:26760242

  1. A rapid and simple HPLC method for the analysis of propofol in biological fluids.

    PubMed

    Cussonneau, Xavier; De Smet, Els; Lantsoght, Kristof; Salvi, Jean-Paul; Bolon-Larger, Magali; Boulieu, Roselyne

    2007-07-27

    A selective and sensitive high-performance liquid chromatographic method for the analysis of propofol in biological samples was developed. Propofol and thymol (internal standard) were analysed on a Purospher RP-18 endcapped (75 mmx4 mm, 3 microm) stationary phase using acetonitrile and water (65:35, v/v) as eluents at a flow rate of 0.6 mL/min. The excitation and emission wavelengths were 276 and 310 nm, respectively. Sample treatment consisted of deproteinization by acetonitrile containing the internal standard and direct injection of the supernatant. Mean analytical recovery were 105% (CV 2.0%) at concentrations ranging from 0.05 to 10 mg/L. The quantification limit was 3 ng/mL for a 500 microL sample plasma volume and 5 ng/mL for a 500 microL blood sample. The intra-day and inter-day precisions were lower than 5.5% for three concentrations assessed (0.05, 1.0 and 10.0 mg/L). Considering the column size and the flow rate, the separation was achieved with an analysis time less than 6 min with a reduced consumption of solvent. This rapid HPLC method using a simple treatment procedure is sensitive enough for monitoring propofol in human biological samples. PMID:17129698

  2. Simultaneous Quantification of 13 Compounds in Guanxin Shutong Capsule by HPLC Method.

    PubMed

    Zhou, Feifei; Zhang, Lunhui; Gu, Liqiang; Zhang, Yuanyuan; Hou, Chenzhi; Bi, Kaishun; Chen, Xiaohui; Zhang, Huifen

    2016-07-01

    Guanxin Shutong (GXST) capsule, which is frequently used in clinical therapy, has a certain and positive therapeutic effect against coronary heart disease. However, the existing quality standard of GXST capsule is inadequate to control the quality of GXST capsule. In this paper, a new high-performance liquid chromatographic (HPLC) method for simultaneous determination of 13 compounds (gallic acid, danshensu, protocatechuic acid, procatechuic aldehyde, ellagic acid, rosmarinic acid, salvianolic acid A and salvianolic acid B, eugenol, dihydrotanshinone I, cryptotanshinone, tanshinone I and tanshinone IIA) in GXST capsule was developed and validated. The analytes were successfully separated and quantified with an Agilent TC-C18 column (250 × 4.6 mm, 5 µm) by gradient elution using 0.05% phosphoric acid and acetonitrile as mobile phase. The flow rate was 1 mL/min and the detection wavelength was set at 280 nm. All the compounds showed good linearity (r > 0.9991) in a relatively wide concentration range. The intra-and the inter-day variability were in the range of 0.85-2.68 and 1.47-2.86%, respectively. The recoveries of the selected compounds were in the range of 95.24-104.75%. This method was successfully applied to quantify the 13 components in GXST capsule and was conducive to controlling the quality of GXST capsule. PMID:26969683

  3. An isocratic HPLC method for the determination of sorbitol and glycerol in pharmaceutical formulations.

    PubMed

    Simonzadeh, Ninus; Ronsen, Bruce

    2012-08-01

    Sorbitol and glycerol, along with other inactive ingredients such as preservatives and dyes, are commonly used in various pharmaceutical and personal care products. To accurately assess the effectiveness of various formulations containing sorbitol and/or glycerol, their quantitative determination is essential. In the current study, two types of detectors (a Varian evaporative light scattering detector and an Agilent ultraviolet-visible detector) are evaluated for the assay of working sample solutions. The two detection techniques are complimentary, and a comparison of the results obtained using the two detectors is presented here. The current method is shown to be stability-indicating and free from interference from any of the formulation excipients and potential degradation products. The method is reproducible, accurate, sensitive and selective. It provides enhanced detection sensitivity for sorbitol and comparable sensitivity for glycerol versus similar methods reported in the literature that utilize a refractive index detector for the analysis of either of the two polyols. PMID:22565491

  4. Simultaneous determination of rivanol and mifepristone in human plasma by a HPLC-UV method with solid-phase extraction.

    PubMed

    Guo, Zhiyong; Wei, Danyi; Yin, Gengxin; Wang, Sui; Zhao, Shasha; Chu, Yun; Zhai, Jinxia

    2007-09-01

    A HPLC method with UV detection was developed and validated for the simultaneous determination of rivanol and mifepristone in human plasma. Norethisterone was used as the internal standard. Separation was performed by a C18 reversed-phase column maintained at 20 degrees C. The mobile phase was a mixture of methanol-acetonitrile-0.05% sodium dodecylsulfonate in a 0.05 M phosphate buffer with the pH adjusted to 3.0 (30:30:40, v/v/v) at a flow rate of 0.8 ml/min. Dual wavelength mode was used, with mifepristone monitored at UV 302 nm, while rivanol and norethisterone at 272 nm. A reliable biological sample pre-treatment procedure by means of solid-phase extraction was used, which allowed to obtain good extraction efficiency (>93%) for both of the analytes and the internal standard. The calibration curves were both linear with the correlation coefficient r equal to 0.9999. For rivanol, the assay gave CV% values for precision always lower than 7.8% and mean accuracy values higher than 95.3%. As to mifepristone, precision was always lower than 10.1% and mean accuracy values were higher than 93.8%. The limit of detection for the assay of rivanol and mifepristone was 1.1 and 3 ng/ml, respectively. The method is simple, sensitive and accurate, and allow for simultaneous determination of nanogram levels of rivanol and mifepristone in human plasma. It could be applied to assess the plasma level of rivanol and mifepristone in women undergoing polypharmacy with the two drugs. PMID:17689304

  5. Ultrasound-assisted extraction of azadirachtin from dried entire fruits of Azadirachta indica A. Juss. (Meliaceae) and its determination by a validated HPLC-PDA method.

    PubMed

    de Paula, Joelma Abadia Marciano; Brito, Lucas Ferreira; Caetano, Karen Lorena Ferreira Neves; de Morais Rodrigues, Mariana Cristina; Borges, Leonardo Luiz; da Conceição, Edemilson Cardoso

    2016-03-01

    Azadirachta indica A. Juss., also known as neem, is a Meliaceae family tree from India. It is globally known for the insecticidal properties of its limonoid tetranortriterpenoid derivatives, such as azadirachtin. This work aimed to optimize the azadirachtin ultrasound-assisted extraction (UAE) and validate the HPLC-PDA analytical method for the measurement of this marker in neem dried fruit extracts. Box-Behnken design and response surface methodology (RSM) were used to investigate the effect of process variables on the UAE. Three independent variables, including ethanol concentration (%, w/w), temperature (°C), and material-to-solvent ratio (gmL(-1)), were studied. The azadirachtin content (µgmL(-1)), i.e., dependent variable, was quantified by the HPLC-PDA analytical method. Isocratic reversed-phase chromatography was performed using acetonitrile/water (40:60), a flow of 1.0mLmin(-1), detection at 214nm, and C18 column (250×4.6mm(2), 5µm). The primary validation parameters were determined according to ICH guidelines and Brazilian legislation. The results demonstrated that the optimal UAE condition was obtained with ethanol concentration range of 75-80% (w/w), temperature of 30°C, and material-to-solvent ratio of 0.55gmL(-1). The HPLC-PDA analytical method proved to be simple, selective, linear, precise, accurate and robust. The experimental values of azadirachtin content under optimal UAE conditions were in good agreement with the RSM predicted values and were superior to the azadirachtin content of percolated extract. Such findings suggest that UAE is a more efficient extractive process in addition to being simple, fast, and inexpensive. PMID:26717816

  6. A simple HPLC method for the isolation and quantification of the allergens tuliposide A and tulipalin A in Alstroemeria.

    PubMed

    Christensen, L P; Kristiansen, K

    1995-04-01

    A practical, rapid, reliable and sensitive method for the isolation and determination of the allergens tuliposide A and alpha-methylene-gamma-butyrolactone (tulipalin A), by reversed-phase high-performance liquid chromatography (RP-HPLC), has been developed in order to select Alstroemeria species for breeding purposes. From the aqueous extracts of flowers, stems and leaves, of several Alstroemeria species, the contents of 6-tuliposide A and tulipalin A were determined by isocratic RP-HPLC, using distilled water as mobile phase. The compounds were detected by an UV detector at 208 nm. Differences in 6-tuliposide A and tulipalin A content were found among the species investigated, with the highest concentrations in stems and flowers. The absence of other tuliposides (e.g., 1-tuliposide A, 1- and 6-tuliposide B) in extracts was proven by TLC, RP-HPLC, 1H- and 13C-NMR. 6-Tuliposide A and tulipalin A were identified by 1H- and 13C-NMR and comparison with authentic material, respectively. With this HPLC method, it is possible to investigate a large number of plants for their contents of tuliposide A and tulipalin A, within a minimum of time, and to isolate them directly from aqueous extracts. PMID:7600774

  7. Combination of automatic HPLC-RIA method for determination of estrone and estradiol in serum.

    PubMed

    Yasui, T; Yamada, M; Kinoshita, H; Uemura, H; Yoneda, N; Irahara, M; Aono, T; Sunahara, S; Mito, Y; Kurimoto, F; Hata, K

    1999-01-01

    We developed a highly sensitive assay for estrone and 17 beta-estradiol in serum. Estrone and 17 beta-estradiol, obtained by solid-phase extraction using a Sep pak tC18 cartridge, were purified by high-performance liquid chromatography (HPLC). Quantitation of estrone and 17 beta-estradiol were carried out by radioimmunoassay. Not insignificantly, this automatic system of extraction and HPLC succeeded in analyzing 80 samples a week. Intra-assay coefficients of variation (CV) for estrone and 17 beta-estradiol ranged from 19.5 to 28.7%, and from 8.5 to 13.7%, respectively. The minimum detectable dose for estrone and 17 beta-estradiol were 1.04 pg/ml and 0.64 pg/ml, respectively. The serum levels of 17 beta-estradiol using our method strongly correlated with those by Gas chromatography mass spectrometry (GC-MS). The serum levels of estrone and 17 beta-estradiol in 154 peri- and postmenopausal women were estimated to be between 15 and 27 pg/ml and between 3.5 and 24.0 pg/ml, respectively, while the serum level of 17 beta-estradiol in postmenopausal women, in particular, was estimated to be from 3.5 to 6.3 pg/ml. For postmenopausal women who suffered from vasomotor symptoms, the mean levels of estrone and 17 beta-estradiol at 12 to 18 hours after treatment with daily 0.625 mg conjugated equine estrogen (CEE) and 2.5 mg medroxyprogesterone acetate (MPA) were 135.0 and 21.3 pg/ml at 12 months, respectively. On the other hand, levels of estrone and 17 beta-estradiol at 12 to 18 hours after treatment with CEE and MPA every other day, were 73.4 and 15.3 pg/ml, respectively. These highly sensitive assays for estrone and 17 beta-estradiol are useful in measuring low levels of estrogen in postmenopausal women, and monitoring estrogen levels in women receiving CEE as hormone replacement therapy. PMID:10633293

  8. Development of a Validated HPLC/Photodiode Array Method for the Determination of Isomenthone in the Aerial Parts of Ziziphora tenuior L.

    PubMed Central

    Ghassemi, Nasrollah; Ghanadian, Mustafa; Ghaemmaghami, Lili; Kiani, Haran

    2013-01-01

    Background Ziziphora tenuior L. known as Kakuti in Persian, is used in traditional medicine for fever, dysentery, uterus infection and as an analgesic. It is used also in the treatment of gastrointestinal disorders as carminative, or remedy of diarrhea or nausea. Major components of plant essential oil including pulegone, isomenthone, thymol, menthone, and piperitone are suggested to be responsible for the mentioned medicinal properties. Objectives In the present study, a normal high performance liquid chromatography (HPLC)/photodiode array validated method for quantification of isomenthone, one of the major constituents of Ziziphora, was established for the first time with a simple, rapid and accurate method. Materials and Methods HPLC analysis was done on a Waters system, equipped with 515 HPLC pump and waters 2996 photodiode array detector. The column was a Nova-Pak Silica (3.9 × 150 mm), and Empower software was used for the determination of the compounds and processing the data. The method was validated according to USP 32 requirements. Results A selective method for the resolution of isomenthone from two nearest peaks, thymol, and carvacrol was obtained with gradient system of hexane (A), and hexane: ethyl acetate (9:1) (B), starting with A: B (100:0) for 2 minutes, then 0−20% B in 5 minutes, A:B (80:20) for 5 minutes, then 20-30% B in 3 minutes, 30-100% B for 5 minutes, A:B (0:100) for 4 minutes following with equilibrating for 10 minutes. The flow rate was 1 mL/min at 22˚C and the injection volume for the standards and the samples was 20 μL. The retention time for isomenthone was found to be 7.45 minutes. The regression equation was y = 143235x - 2433 with the correlation co-factor R2 = 0.9992 and the percent recovery of 65.4 ± 3.85%. The sample obtained from 5 g of Z. teniour dried powder in 6 mL extract was standardized to contain 1.14 ± 0.030 μL/mL isomenthone which is equivalent to % 1.37 μL/g of the dried powdered plant. Limit of detection

  9. Development and validation of an HPLC method to determine metabolites of 5-hydroxymethylfurfural (5-HMF).

    PubMed

    Hardt-Stremayr, Magdalena; Bernaskova, Marketa; Hauser, Stefanie; Kunert, Olaf; Guo, Xinghua; Stephan, Janette; Spreitz, Josef; Lankmayr, Ernst; Schmid, Martin G; Wintersteiger, Reinhold

    2012-10-01

    The food component 5-hydroxymethylfurfural is supposed to have antioxidative properties and is therefore used as an acting agent in a novel anticancer infusion solution, named Karal®, and an oral supplementation. Previous studies showed that after oral and intravenous application, the substance is completely decomposed to its metabolites: 5-hydroxymethylfuroic acid, 2,5-furandicarboxylic acid, and N-(hydroxymethyl)furoyl glycine. The formation of a fourth metabolite, namely 5-sulphoxymethylfurfural, is still not clarified according to literature. Due to commercial unavailability, synthesis of 5-sulphoxymethylfurfural was conducted and a synthesis procedure for N-(hydroxymethyl)furoyl glycine had to be developed. Identification of the synthesised compounds was proven by LC-MS and NMR. An appropriate HPLC method was established to obtain good separation of the four possible metabolic substances and 5-hydroxymethylfurfural within 12 min via a HILIC column (150 × 4.6 mm, 5 μm) using a gradient grade system switching from mobile phase A (ACN/ammonium formate 100 mM, pH 2.35, 95:5, v/v) to mobile phase B (ACN/ammonium formate 100 mM, pH 2.35, 85:15, v/v). The procedure was afterward validated following ICH guidelines in terms of selectivity, linearity, precision, LOD, and LOQ. PMID:22941583

  10. Investigation on the origin of 5-HMF in Shengmaiyin decoction by RP-HPLC method*

    PubMed Central

    Li, Ying-hua; Lu, Xiu-yang

    2005-01-01

    The origin of 5-HMF (5-hydroxymethyl-2-furaldehyde) in a Shengmaiyin decoction was investigated by the RP-HPLC method below. A C18 column (250 mm×4.6 mm, i.d. 5 μm) with a column temperature of 25 °C was used. The mobile phase was a mixture of ultra-pure water-acetonitrile (95:5, V/V) and the flow rate was 1.0 ml/min. The detection wavelength was 280 nm. The injection volume was 1 μl and the running time was about 20 min. The addition of Schisandra was regulated to assess the contribution of an acid environment to the production of 5-HMF. In order to confirm the role of saccharides in the production of 5-HMF, different amount of fructose was used. The 5-HMF level in decoctions of processed and unprocessed Schisandra was investigated in order to determine the origin of 5-HMF. The results showed that 5-HMF was derived mainly from the decoction of Schisandra only and not the mixed decoction of Ophionpogon and Schisandra. The appearance of 5-HMF is not simply the result of the decomposition of saccharides under the acid environment created by Schisandra, but the processing procedure plays an important role in the production of 5-HMF. PMID:16187416

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

    SciTech Connect

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

    2012-01-01

    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 and 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.

  12. Development and Validation of a Stability-Indicating RP-HPLC Method by a Statistical Optimization Process for the Quantification of Asenapine Maleate in Lipidic Nanoformulations.

    PubMed

    Managuli, Renuka S; Kumar, Lalit; Chonkar, Ankita D; Shirodkar, Rupesh K; Lewis, Shaila; Koteshwara, Kunnatur B; Reddy, Meka Sreenivasa; Mutalik, Srinivas

    2016-09-01

    A stability-indicating RP-HPLC method was developed for quantification of asenapine maleate (ASPM) in lipid nanoformulations. The proposed method was used to assess intrinsic stability of ASPM by conducting force degradation study. The results indicated no considerable degradation of ASPM on subjecting it to hydrolytic, oxidative, thermal and photolytic stresses. The method was validated according to ICH Q2(R1) guidelines by employing Full factorial design using Design-Expert(®) software. ASPM was precisely and accurately quantified in nanoparticles by separating it on Hyperclone BDS C18 using 80-20% v/v mixture of potassium phosphate solution containing 0.1% v/v triethylamine and acetonitrile. The effect of flow rate, pH, acetonitrile content and column temperature was assessed on method responses. The current method was linear in the range of 0.1-20 µg/mL with limit of detection (LOD) and limit of quantification (LOQ) of 29 and 89 ng/mL, respectively. The method was precise and accurate in the determination of ASPM with peak area RSD and recovery of <1.0% and 97-101% in bulk drug solution and of <1.0% and 92-104% in nanoformulations, respectively. Analysis of variance indicated the significance (P < 0.0001) of a statistical model in validating the method with respect to change in independent chromatographic factors. The developed method was successfully employed in determining ASPM content in bulk and lipid nanoformulations. PMID:27130879

  13. A routine method for the simultaneous measurement of retinol, alpha-tocopherol and five carotenoids in human plasma by reverse phase HPLC.

    PubMed

    Talwar, D; Ha, T K; Cooney, J; Brownlee, C; O'Reilly, D S

    1998-02-23

    We describe a simple isocratic HPLC method for the accurate and precise measurement of retinol, alpha-tocopherol and the major carotenoids in plasma using UV detection. Reference ranges for retinol, alpha-tocopherol and five carotenoids are determined in a healthy population group. The most abundant carotenoids found in plasma were beta-carotene, lycopene, lutein and cryptoxanthin. Retinol, alpha-tocopherol and carotenoids were determined simultaneously using two internal standards, retinol acetate for retinol and tocopherol acetate for alpha-tocopherol and carotenoids. The use of echinenone as an internal standard for carotenoids was investigated. The protective effect of an antioxidant (ascorbic acid) on the stability of samples and extracted material is documented. The method is useful for the routine measurement of plasma retinol, alpha-tocopherol and carotenoids and could also be used in large scale epidemiological studies. PMID:9544447

  14. An improved HPLC-UV method for the simultaneous quantification of triterpenic glycosides and aglycones in leaves of Centella asiatica (L.) Urb (APIACEAE).

    PubMed

    Rafamantanana, M H; Rozet, E; Raoelison, G E; Cheuk, K; Ratsimamanga, S U; Hubert, Ph; Quetin-Leclercq, J

    2009-08-01

    The simultaneous quantification of madecassoside, asiaticoside, madecassic acid and asiatic acid in Centella asiatica by HPLC-UV is proposed. Asiaticoside was used as reference for the quantification of heterosides and asiatic acid for aglycones. The evaluation of the extraction efficiency of the four molecules led to use Soxhlet extraction for 8 h. The method was validated and was found to be accurate in the concentration range of 1.0-3.0 mg/ml for asiaticoside and 0.5-2.0 mg/ml for asiatic acid with CV <3% for all investigated compounds. LOD and LOQ were, respectively, 0.0113 and 1.0 mg/ml for asiaticoside and 0.0023 and 0.5 mg/ml for asiatic acid. This method was shown to be convenient for routine analysis of samples of C. asiatica. PMID:19349219

  15. Quality by design (QbD) based development of a stability indicating HPLC method for drug and impurities.

    PubMed

    Karmarkar, S; Garber, R; Genchanok, Y; George, S; Yang, X; Hammond, R

    2011-01-01

    In this paper, an application of Quality by Design (QbD) concepts to the development of a stability indicating HPLC method for a complex pain management drug product containing drug substance, two preservatives, and their degradants is described. The QbD approach consisted of (i) developing a full understanding of the intended purpose, (ii) developing predictive solutions, (iii) designing a meaningful system suitability solution that helps to identify failure modes, and (iv) following design of experiments (DOE) approach. The starting method lacked any resolution among drug degradant and preservative oxidative degradant peaks, and peaks for preservative and another drug degradant. The method optimization was accomplished using Fusion AE™ software (S-Matrix Corporation, Eureka, CA) that follows a DOE approach. Column temperature (50 ± 5°C), mobile phase buffer pH (2.9 ± 0.2), initial % acetonitrile (ACN, 2 ± 1%), and initial hold time (2.5, 5, or 10 min) of the HPLC method were simultaneously studied to optimize separation of the unresolved peaks. The optimized HPLC conditions (column temperature of 50°C, buffer pH of 3.1, 3% initial ACN with 2.5 min initial hold) resulted in fully resolved peaks in the two critical pairs. The QbD based method development helped in generating a design space and operating space with knowledge of all method performance characteristics and limitations and successful method robustness within the operating space. PMID:21682993

  16. Development and application of a HPLC method for eight sunscreen agents in suncare products.

    PubMed

    Peruchi, L M; Rath, S

    2012-06-01

    This work describes the development, validation and application of a simple and fast high-performance liquid chromatography-with diode array dectection (HPLC-DAD) method for the determination of eight sunscreen agents: benzophenone-3, octocrylene, ethylhexyl methoxycinnamate, ethylhexyl salicylate, homosalate (used in two isomeric forms), butyl methoxydibenzoylmethane, 4-methylbenzylidene camphor and ethylhexyl dimethyl PABA in sunscreen formulations. The separation of the eight sunscreen compounds was achieved using an ACE C18 column (250 × 4.6 mm, 5 μm), with a column temperature 20°C, and a mobile phase of 88 : 12 (v/v) methanol-water with isocratic elution. Column temperature strongly influences the retention time and resolution of the compounds. The flow rate was 1.0 mL min(-1) and quantitation was performed by external calibration at the maximum wavelength of each compound. The sample preparation was simple and consisted basically of sample dilution with methanol, centrifugation and filtration in syringe filters before quantitation. Total run time was 18 min. The method was validated according to the parameters: linear range, linearity, selectivity, intra-day and inter-day precision and accuracy. Ten samples of sunscreen emulsions commercially available in Brazil (SPF 30) from different manufacturers were analysed using the proposed method. The number of the sunscreen agents varied between one and five in a single sample. The concentrations of all compounds were in the range of 0.9-10% (w/w) and were in accordance with the current Brazilian legislation. PMID:22214440

  17. HPLC Method for the Simultaneous Determination of Ten Annonaceous Acetogenins after Supercritical Fluid CO2 Extraction

    PubMed Central

    Yang, Haijun; Zhang, Ning; Zeng, Qingqi; Yu, Qiping; Ke, Shihuai; Li, Xiang

    2010-01-01

    Annonaceous acetogenins (ACGs) isolated from Annonaceae plants exhibited a broad range of biological bioactivities such as cytotoxic, antitumoral, antiparasitic, pesticidal and immunosuppresive activities. However, their structures were liable to change at more than 60°C and their extraction yields were low using traditional organic solvent extraction. In the present study, all samples from Annona genus plant seeds were extracted by supercritical carbon dioxide under optimized conditions and a high-performance liquid chromatography (HPLC) method was established for simultaneously determining ten ACGs. All of the ten compounds were simultaneously separated on reversed-phase C18 column (250 mm × 4.6 mm, 5 μm) with the column temperature at 30°C. The mobile phase was composed of (A) methanol and (B) distilled water, the flow rate was 1.0 ml/min and the detection wavelength was set at 220 nm. All calibration curves showed good linear regression (γ>0.9995) within the test range. The established method showed good precision and accuracy with overall intra-day and inter-day variations of 0.99-2.56% and 1.93-3.65%, respectively, and overall recoveries of 95.16-105.01% for the ten compounds analyzed. The established method can be applied to evaluate the intrinsic quality of Annonaceae plant seeds. The determination results recover the content-variation regularities of various ACGs in different species, which are helpful to choose the good-quality Annonaceae plant seeds for anticancer lead compound discovery. PMID:23675194

  18. Development and validation of SPMMTE HPLC method for analysis of profens from human plasma.

    PubMed

    Hussain, Afzal; Al-Ajmi, Mohamed F; Amir, Samira; Ali, Imran

    2016-08-01

    A fast, selective and reproducible solid-phase membrane microtip extraction (SPMMTE) HPLC method has been developed and validated for the analyses of ibuprofen, ketoprofen, and flurbiprofen from human plasma. The analysis was carried out on a C18 (150 × 4.6 mm; 5 μm) column. The mobile phase used was water-acetonitrile (55:45, v/v) adjusted to pH 3.0 using trifluoroacetic acid, at a flow rate 0.5 mL/min with a detection wavelength of 225 nm. The values for the capacity factors for the profen samples ranged from 0.47 to 1.50. The values for the selectivity factor (α) for ketoprofen-flurbiprofen, flurbiprofen-ibuprofen and ibuprofen-ketoprofen combinations from human plasma samples were 1.99, 1.00 and 2.10, respectively. The resolution factors (Rs) for ketoprofen-flurbiprofen, flurbiprofen-ibuprofen and ibuprofen-ketoprofen from plasma samples were 3.00, 1.50 and 4.10, respectively. The percentage recoveries of ibuprofen, ketoprofen, and flurbiprofen from human plasma were 75-85%. All of the profens were separated within 7.0 min, indicating a relatively fast method. During the development of the SPMMTE procedure the parameters of pH, contact time, desorption and types of solvents were optimized. The final method was also found to be efficient, effective and inexpensive. Copyright © 2016 John Wiley & Sons, Ltd. PMID:26686197

  19. Robust and Accurate Shock Capturing Method for High-Order Discontinuous Galerkin Methods

    NASA Technical Reports Server (NTRS)

    Atkins, Harold L.; Pampell, Alyssa

    2011-01-01

    A simple yet robust and accurate approach for capturing shock waves using a high-order discontinuous Galerkin (DG) method is presented. The method uses the physical viscous terms of the Navier-Stokes equations as suggested by others; however, the proposed formulation of the numerical viscosity is continuous and compact by construction, and does not require the solution of an auxiliary diffusion equation. This work also presents two analyses that guided the formulation of the numerical viscosity and certain aspects of the DG implementation. A local eigenvalue analysis of the DG discretization applied to a shock containing element is used to evaluate the robustness of several Riemann flux functions, and to evaluate algorithm choices that exist within the underlying DG discretization. A second analysis examines exact solutions to the DG discretization in a shock containing element, and identifies a "model" instability that will inevitably arise when solving the Euler equations using the DG method. This analysis identifies the minimum viscosity required for stability. The shock capturing method is demonstrated for high-speed flow over an inviscid cylinder and for an unsteady disturbance in a hypersonic boundary layer. Numerical tests are presented that evaluate several aspects of the shock detection terms. The sensitivity of the results to model parameters is examined with grid and order refinement studies.

  20. Development and Validation of HPLC and HPTLC Methods for Estimation of Glabridin in Extracts of Glycyrrhiza glabra.

    PubMed

    Viswanathan, Vivek; Mukne, Alka P

    2016-01-01

    Glabridin is a major bioactive phytoconstituent of licorice. This work discusses the development and validation of HPLC and HPTLC methods for analysis of glabridin in licorice. The HPLC separation was performed using a Purospher STAR RP-18e column (5 μm silica particle size, 250 mm × 4.6 mm inner diameter) with gradient elution of 0.2% acetic acid in water-acetonitrile. The flow rate was 1 mL/min. Quantification was performed at a detection wavelength of 280 nm. HTPLC separation was performed on precoated silica gel 60 F254 aluminum plate (10 × 10 cm, 250 μm thickness). A linear ascending development was done using a mobile phase of hexane-ethyl acetate-chloroform (5 + 4 + 3, v/v/v). After development, the plates were scanned at 285 nm. Both of the methods provided good separation of glabridin from other constituents of licorice extract. The methods were validated as per ICH guidelines. Comparison by Student t-test showed that there was a statistically insignificant difference between the mean glabridin content estimated by both methods at 95% confidence interval. The glabridin content in licorice extract was 3.90% by HPLC and 3.79% by HPTLC. PMID:27103104

  1. HPLC method for measuring meropenem and biapenem concentrations in human peritoneal fluid and bile: application to comparative pharmacokinetic investigations.

    PubMed

    Kameda, Keiko; Ikawa, Kazuro; Ikeda, Kayo; Morikawa, Norifumi; Nakashima, Akira; Ohge, Hiroki; Sueda, Taijiro

    2010-01-01

    A high-performance liquid chromatography (HPLC) method using ultrafiltration to pretreat peritoneal fluid and bile samples is developed to measure meropenem and biapenem concentrations in human peritoneal fluid and bile. Meropenem or biapenem in peritoneal fluid or bile samples is stabilized by mixing with 1 mol/L 3-morpholinopropanesulfonic acid buffer (pH 7.0) (1:1). The mixture is transferred to a Nanosep 10K centrifugal filter device; after centrifugation, the filtrate is subjected to reversed-phase HPLC, and the eluate is monitored at 300 nm. No interference from endogenous substances is observed. The lower limits of quantification are 0.05 microg/mL for peritoneal fluid and 0.1 microg/mL for bile. The new method has been applied to comparative site-specific-pharmacokinetic investigations in surgery patients. PMID:20515537

  2. Fingerprint analysis and multi-component determination of Zibu Piyin recipe by HPLC with DAD and Q-TOF/MS method.

    PubMed

    Xiang, Hong; Xu, Huiying; Zhan, Libin; Zhang, Lin

    2016-05-01

    Zibu Piyin recipe (ZBPYR), a traditional Chinese medicine formula, is used for curing dementia caused by diabetes. For quality control of ZBPYR, fingerprint analysis and qualitative analysis using high-performance liquid chromatography (HPLC) with a diode-array detector, and confirmation using HPLC coupled with electrospray ionisation quadrupole time-of-flight tandem mass spectrometry (HPLC-Q-TOF-MS) were undertaken. HPLC fingerprint consisting of 34 common peaks was developed among 10 batches of ZBPYR, in which 7 common peaks were identified in comparison with the authentic standards and detected simultaneously. Furthermore, these seven compounds were verified by HPLC-Q-TOF-MS methods. The method can be applied to the quality control of ZBPYR. PMID:26418623

  3. A simple HPLC method for determination of permethrin residues in wine.

    PubMed

    Shishovska, Maja A; Trajkovska, Vera P; Stefova, Marina T

    2010-10-01

    An isocratic High Performance Liquid Chromatographic (HPLC) method was optimized for 3-phenoxybenzyl (1RS)-cis-trans-3-(2,2-dichlorovinyl)-2,2-dimethyl-cyclopropanecarboxylate (permethrin) residues identification and quantification in wine matrix. Analytical reverse phase (RP) C-18 column was used (25 cm × 4 mm i.d., 5 μ m) with mobile phase consisting of acetonitrile and water in ratio 70 %/30 % (v v(-1)), flow-rate 2.0 mL min(-1), UV-detection at 215 nm and controlled oven temperature at 25°C. The peaks of isomers were identified with the retention times as compared to standard cis-/trans- mixture and confirmed with characteristic spectra using photodiode array detector. Under these conditions, permethrin isomers were well separated with resolution 2.8 and no interference with the naturally present wine compounds was observed. The method was validated for linearity, precision, accuracy, limit of detection (LOD) and limit of quantification (LOQ). Linear regression analysis data proved a good linear relationship (correlation coefficients, r(2), for cis- and trans-isomer are: 0.9995 and 0.9997, respectively) between response of the detector and concentration of permethrin isomers over a wide concentration range for both isomers (0.55 mg L(-1) -4.40 mg L(-1)). Experimental data showed mean recoveries between 93.95% and 96.58% with RSD values in range: 0.89% -3.69%. The effect of ethanol content in the solvent on permethrin isomers peak areas was also studied and 60% v v(-1) ethanol was found to be optimal for sample preparation. The method was successfully tested on 20 commercial wine samples from the market in which no permethrin was detected. Thus, it was proved that it is suitable for routine permethrin residues analysis. The proposed method is suitable for routine analysis because of the simple sample preparation, acceptable run-time, low cost and its applicability with conventional instruments. PMID:20845181

  4. Development and validation of a stability-indicating HPLC method for determination of voriconazole and its related substances.

    PubMed

    Gu, Ping; Li, Yuru

    2009-08-01

    An isocratic reversed-phase high performance liquid chromatographic (RP-HPLC) method has been developed and validated for the determination of voriconazole and its related substances. The drug substance was subjected to stress conditions of UV light, water hydrolysis, acid, base, oxidation, and deoxidization to observe the degradation products. The successful separation of voriconazole from its synthetic impurities and degradation products formed under stress conditions was achieved using an Agilent Zorbax SB-C18 (250mm x 4.6 mm i.d., 5 microm) column maintained at 25 degrees C with a mobile phase of a mixture of ammonium phosphate dibasic buffer (pH adjusted to 6.0 using diluted orthophosphoric acid; 50 mM)-acetonitrile (52:48, v/v). The mobile phase flow rate was 1.0 mL/min, and the detection wavelength was 250 nm. The stress sample solutions were assayed against the qualified reference standard of voriconazole and the mass balance in each case was close to 99.7%, confirming its stability-indication capacity. The developed HPLC method was validated with respect to linearity, accuracy, precision, specificity, and robustness. The developed HPLC method to determine the related substances and assay determination of voriconazole can be used to evaluate the quality of regular production samples. It can be also used to test the stability samples of voriconazole. PMID:19772734

  5. Development and validation of an HPLC-MS/MS analytical method for quantitative analysis of TCBA-TPQ, a novel anticancer makaluvamine analog, and application in a pharmacokinetic study in rats

    PubMed Central

    Jun-Xian, YU; Voruganti, Sukesh; Dan-Dan, LI; Qin, Jiang-Jiang; Nag, Subhasree; Xu, Su; Velu, Sadanandan E.; Wang, Wei; Zhang, Ruiwen

    2016-01-01

    We have recently designed and synthesized several novel iminoquinone anticancer agents that have entered preclinical development for the treatment of human cancers. Herein we developed and validated a quantitative HPLC-MS/MS analytical method for one of the lead novel anticancer makaluvamine analog, TCBA-TPQ, and conducted a pharmacokinetic study in laboratory rats. Our results indicated that the HPLC-MS/MS method was precise, accurate, and specific. Using this method, we carried out in vitro and in vivo evaluations of the pharmacological properties of TCBA-TPQ and plasma pharmacokinetics in rats. Our results provide a basis for future preclinical and clinical development of this promising anticancer marine analog. PMID:26233847

  6. Development and validation of an HPLC-MS/MS analytical method for quantitative analysis of TCBA-TPQ, a novel anticancer makaluvamine analog, and application in a pharmacokinetic study in rats.

    PubMed

    Yu, Jun-Xian; Voruganti, Sukesh; Li, Dan-Dan; Qin, Jiang-Jiang; Nag, Subhasree; Xu, Su; Velu, Sadanandan E; Wang, Wei; Zhang, Ruiwen

    2015-07-01

    We have recently designed and synthesized several novel iminoquinone anticancer agents that have entered preclinical development for the treatment of human cancers. Herein we developed and validated a quantitative HPLC-MS/MS analytical method for one of the lead novel anticancer makaluvamine analog, TCBA-TPQ, and conducted a pharmacokinetic study in laboratory rats. Our results indicated that the HPLC-MS/MS method was precise, accurate, and specific. Using this method, we carried out in vitro and in vivo evaluations of the pharmacological properties of TCBA-TPQ and plasma pharmacokinetics in rats. Our results provide a basis for future preclinical and clinical development of this promising anticancer marine analog. PMID:26233847

  7. Accurate compressed look up table method for CGH in 3D holographic display.

    PubMed

    Gao, Chuan; Liu, Juan; Li, Xin; Xue, Gaolei; Jia, Jia; Wang, Yongtian

    2015-12-28

    Computer generated hologram (CGH) should be obtained with high accuracy and high speed in 3D holographic display, and most researches focus on the high speed. In this paper, a simple and effective computation method for CGH is proposed based on Fresnel diffraction theory and look up table. Numerical simulations and optical experiments are performed to demonstrate its feasibility. The proposed method can obtain more accurate reconstructed images with lower memory usage compared with split look up table method and compressed look up table method without sacrificing the computational speed in holograms generation, so it is called accurate compressed look up table method (AC-LUT). It is believed that AC-LUT method is an effective method to calculate the CGH of 3D objects for real-time 3D holographic display where the huge information data is required, and it could provide fast and accurate digital transmission in various dynamic optical fields in the future. PMID:26831987

  8. Determination of antazoline and tetrahydrozoline in ophthalmic solutions by capillary electrophoresis and stability-indicating HPLC methods.

    PubMed

    Gumustas, Mehmet; Alshana, Usama; Ertas, Nusret; Goger, Nilgun Gunden; Ozkan, Sibel A; Uslu, Bengi

    2016-05-30

    Capillary electrophoretic (CE) and high performance liquid chromatographic (HPLC) methods were developed and optimized for the determination of antazoline (ANT) and tetrahydrozoline (TET) in ophthalmic formulations. Optimum electrophoretic conditions were achieved using a background electrolyte of 20mM phosphate buffer at pH 7.0, a capillary temperature of 25°C, a separation voltage of 22kV and a pressure injection of the sample at 50mbar for 17s. HPLC analysis was performed with Kinetex (150×4.6mm ID×5μm) (Phenomenex, USA) analytical column with 1mLmin(-1) flow rate of mobile phase which consisted of 0.05% TFA in bidistilled water (pH adjusted to 3.0 with 5M NaOH) and acetonitrile/buffer in the ratio of 63:37 (v/v) at room temperature. Injection volume of the samples was 10μL and the wavelength of the detector was set at 215nm for monitoring both analytes. Calibration graphs showed a good linearity with a coefficient of determination (R(2)) of at least 0.998 for both methods. Intraday and interday precision (expressed as RSD%) were lower than 2.8% for CE and 0.92% for HPLC. The developed methods were demonstrated to be simple and rapid for the determination of ANT and TET in ophthalmic solutions providing recoveries in the range between 97.9 and 102.70% for CE and HPLC. PMID:26952922

  9. Determination of Ciprofloxacin in Pharmaceutical Formulations Using HPLC Method with UV Detection.

    PubMed

    Scherer, R; Pereira, Jessica; Firme, Juliete; Lemos, Mariana; Lemos, Mayara

    2014-01-01

    A simple, specific, accurate and rapid reversed phase high performance liquid chromatographic method was validated for the determination of the content of ciprofloxacin in three pharmaceuticals forms: generic, similar and compounded. The results of the validation showed that the method was highly efficient for quantification of ciprofloxacin in the matrices evaluated. The recovery rates were between 97.4 to 104.3 %, and the relative standard deviations were lower than 5 % for repeatability, and lower than 5.15 % for intermediate precision. The limits of detection, quantification and practical, were 0.11, 0.35 and 1.56 μg/ml, respectively. All compounded samples were approved with in the quality control; however, one generic and one similar sample presented above allowed level. PMID:25593388

  10. A novel method HPLC-DAD analysis of the Contentsof Moutan Cortexand Paeoniae Radix Alba with similar constituents-monoterpene glycosides in Guizhi Fuling Wan.

    PubMed

    Wang, Shuyun; Huang, Jian; Mao, Huijuan; Wang, Yuliang; Kasimu, Rena; Xiao, Wei; Wang, Jinhui

    2014-01-01

    A variety of traditional Chinese medical formulations contain two or more herbs from the same genus or family. Although these herbs may have a similar appearance and constituents, they usually have different pharmacodynamic actions. A series of qualitative and quantitative analysis methods are developed to determine one or more compounds for quality control of medicine. As far as we know, no method has been found to determine the real ratio of the two herbs along with the prescription. In this study, we used HPLC-DAD as a way to determine the content of Moutan cortex (M) and Paeoniae radix alba (P) in GuizhiFuling Wan (GZFLW). An effective, accurate and reliable HPLC-DAD method was developed for detecting the content of M and P in GZFLW through the analysis of four monoterpeneglycosides, namely, galloylpaeoniflorin (1), paeoniflorin (2), mudanpioside C (3) and benzoylpaeoniflorin (4). Due to the different UV characteristics of the compounds, the detection wavelength was 270 nm for 1 and 2, while 3 and 4 were monitored at 254 nm and 230 nm, respectively. Four equations were put forward to describe the relationship between content of M as well as P and the four monoterpene glycosides in GZFLW. After validation, all the accuracies of the M and P contents in GZFLW were within 10%. The result showed that the method could be successfully applied to analyze the contents of M and P in GZFLW. Moreover, our method may be more widely used to control the quality of proprietary Chinese medicines, especially for those containing the same genus or family herbs, in industrial GMP production. PMID:25375336

  11. Method performance and multi-laboratory assessment of a normal phase HPLC/FLD method for the quantitation of flavanols and procyanidins in cocoa and chocolate containing samples

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The quantitative parameters and method performance for a normal-phase HPLC separation of flavanols and procyanidins in chocolate and cocoa-containing food products were optimized and assessed. The chromatographic separation based on degree of polymerization (DP) was achieved on a diol stationary ph...

  12. Determination of formaldehyde in food and feed by an in-house validated HPLC method.

    PubMed

    Wahed, P; Razzaq, Md A; Dharmapuri, S; Corrales, M

    2016-07-01

    Formalin is carcinogenic and is detrimental to public health. The illegal addition of formalin (37% formaldehyde and 14% methanol) to foods to extend their shelf-life is considered to be a common practice in Bangladesh. The lack of accurate methods and the ubiquitous presence of formaldehyde in foods make the detection of illegally added formalin challenging. With the aim of helping regulatory authorities, a sensitive high performance liquid chromatography method was validated for the quantitative determination of formaldehyde in mango, fish and milk. The method was fit-for-purpose and showed good analytical performance in terms of specificity, linearity, precision, recovery and robustness. The expanded uncertainty was <35%. The validated method was applied to screen samples of fruits, vegetables, fresh fish, milk and fish feed collected from different local markets in Dhaka, Bangladesh. Levels of formaldehyde in food samples were compared with published data. The applicability of the method in different food matrices might mean it has potential as a reference standard method. PMID:26920321

  13. Effective method for the detection of piroxicam in human plasma using HPLC.

    PubMed

    Calvo, Adriana Maria; Prado, Mariel Tavares de Oliveira; Dionísio, Thiago José; Marques, Maria Paula; Brozoski, Daniel Thomas; Lanchote, Vera Lúcia; Faria, Flávio Augusto Cardoso; Santos, Carlos Ferreira

    2016-05-20

    Non-steroidal anti-inflammatory drugs (NSAIDs) are widely used by the general population to alleviate inflammation and pain after oral surgeries. Piroxicam is among the most commonly used NSAIDs and excels in controlling pain, swelling, trismus and other common symptoms of inflammation. This study aimed to evaluate different concentrations of piroxicam and its major metabolite, 5'-hydroxypiroxicam, in human plasma samples over time using high performance liquid chromatography (HPLC) after liquid-liquid extraction. Briefly, 10 volunteers participated in this study after approval by the Ethics Committee of Bauru School of Dentistry, Universidade de São Paulo - USP, Brazil. Volunteers received a single dose oral of piroxicam (20 mg) and had blood collected at various times following an established protocol. The methodology of liquid-liquid extraction was effective for determining concentrations of piroxicam in plasma using HPLC in 10 out of 10 volunteers while 5'-hydroxypiroxicam was only detected in 2 out of 10 volunteers. PMID:27223141

  14. A simple and sensitive HPLC method for quantification of the metabolin of meclofenoxate in human plasma.

    PubMed

    Ni, Bin; Zhang, Junren; Zou, Jianjun; Zhao, Wei; Li, JianHua

    2010-01-01

    A simple and sensitive high-performance liquid chromatographic method was developed for quantification of the metabolin of meclofenoxate, chlorophenoxyacetic acid, in human plasma. Ibuprofen was used as an internal standard. The present method used protein precipitation for extraction of chlorophenoxyacetic acid from human plasma. Separation was carried out on a reversed-phase C(18) column. The column effluent was monitored by UV detection at 254 nm. The mobile phase was a mixture of methanol and water containing 1.0% glacial acetic acid (70:30 v/v) at a flow rate of 1.0 mL/min. The column temperature was 20 degrees C. This method was linear over the range of 0.047-28.20 microg/mL with a regression coefficient greater than 0.99. The mean recovery of chlorophenoxyacetic acid and IS were (79.54 +/- 6.33)% and (78.48 +/- 2.14)%, respectively, and the method was found to be precise, accurate, and specific during the study. The method was successfully applied for pharmacokinetic study of chlorophenoxyacetic acid in human. PMID:20515527

  15. High-order accurate monotone difference schemes for solving gasdynamic problems by Godunov's method with antidiffusion

    NASA Astrophysics Data System (ADS)

    Moiseev, N. Ya.

    2011-04-01

    An approach to the construction of high-order accurate monotone difference schemes for solving gasdynamic problems by Godunov's method with antidiffusion is proposed. Godunov's theorem on monotone schemes is used to construct a new antidiffusion flux limiter in high-order accurate difference schemes as applied to linear advection equations with constant coefficients. The efficiency of the approach is demonstrated by solving linear advection equations with constant coefficients and one-dimensional gasdynamic equations.

  16. Method for accurate growth of vertical-cavity surface-emitting lasers

    DOEpatents

    Chalmers, S.A.; Killeen, K.P.; Lear, K.L.

    1995-03-14

    The authors report a method for accurate growth of vertical-cavity surface-emitting lasers (VCSELs). The method uses a single reflectivity spectrum measurement to determine the structure of the partially completed VCSEL at a critical point of growth. This information, along with the extracted growth rates, allows imprecisions in growth parameters to be compensated for during growth of the remaining structure, which can then be completed with very accurate critical dimensions. Using this method, they can now routinely grow lasing VCSELs with Fabry-Perot cavity resonance wavelengths controlled to within 0.5%. 4 figs.

  17. Method for accurate growth of vertical-cavity surface-emitting lasers

    DOEpatents

    Chalmers, Scott A.; Killeen, Kevin P.; Lear, Kevin L.

    1995-01-01

    We report a method for accurate growth of vertical-cavity surface-emitting lasers (VCSELs). The method uses a single reflectivity spectrum measurement to determine the structure of the partially completed VCSEL at a critical point of growth. This information, along with the extracted growth rates, allows imprecisions in growth parameters to be compensated for during growth of the remaining structure, which can then be completed with very accurate critical dimensions. Using this method, we can now routinely grow lasing VCSELs with Fabry-Perot cavity resonance wavelengths controlled to within 0.5%.

  18. Development and validation of a rapid HPLC method for quantitation of SP-141, a novel pyrido[b]indole anticancer agent, and an initial pharmacokinetic study in mice

    PubMed Central

    Nag, Subhasree; Qin, Jiang-Jiang; Voruganti, Sukesh; Wang, Ming-Hai; Sharma, Horrick; Patil, Shivaputra; Buolamwini, John K.; Wang, Wei; Zhang, Ruiwen

    2015-01-01

    There is an increasing interest in targeting the MDM2 oncogene for cancer therapy. SP-141, a novel designed small molecule MDM2 inhibitor, exerts excellent in vitro and in vivo anticancer activity. To facilitate the preclinical development of this candidate anticancer agent, we have developed an HPLC method for the quantitative analysis of SP-141. The method was validated to be precise, accurate, and specific, with a linear range of 16.2–32,400 ng/mL in plasma, 16.2–6480 ng/mL in homogenates of brain, heart, liver, kidneys, lungs, muscle and tumor, and 32.4–6480 ng/mL in spleen homogenates. The lower limit of quantification was 16.2 ng/mL in plasma and all the tissue homogenates, except for spleen homogenates, where it was 32.4 ng/mL. The intra- and inter-assay precisions (coefficient of variation) were between 0.86 and 13.39%, and accuracies (relative errors) ranged from −8.50 to 13.92%. The relative recoveries were 85.6–113.38%. SP-141 was stable in mouse plasma, modestly plasma bound and metabolized by S9 microsomal enzymes. We performed an initial pharmacokinetic study in tumor-bearing nude mice, demonstrating that SP-141 has a short half-life in plasma and wide tissue distribution. In summary, this HPLC method can be used in future preclinical and clinical investigations of SP-141. PMID:25294254

  19. Stability-Indicating HPLC-UV Method for Vitamin D3 Determination in Solutions, Nutritional Supplements and Pharmaceuticals.

    PubMed

    Temova, Žane; Roškar, Robert

    2016-08-01

    A simple and fast high-performance liquid chromatography method with UV detection for determination of vitamin D3 in stability studies as well as in solutions, nutritional supplements and pharmaceuticals was developed. Successful separation of vitamin D3 from its degradation products was achieved on a Gemini C18 100 × 3.0 mm column using a mixture of acetonitrile and water (99:1, v/v) as а mobile phase. The method was successfully validated according to the ICH guidelines. The described reversed-phase HPLC method is favorable compared with other published HPLC-UV methods because of its stability-indicating nature, short run time (3.3 min) and wide analytical range with outstanding linearity, accuracy and precision. The method was further applied for quantification of vitamin D3 in selected liquid and solid nutritional supplements and prescription medicines, confirming its suitability for routine analysis. Degradation products, formed under stress conditions (hydrolysis, oxidation, photolysis and thermal degradation), were additionally elucidated by suitable equipment (LC-DAD-MS) to confirm the stability-indicating nature of the developed method. PMID:27048642

  20. Fast HPLC method using ion-pair and hydrophilic interaction liquid chromatography for determination of phenylephrine in pharmaceutical formulations.

    PubMed

    Dousa, Michal; Gibala, Petr

    2010-01-01

    A rapid procedure based on a direct extraction and HPLC determination with fluorescence detection of phenylephrine in pharmaceutical sachets that include a large excess of paracetamol (65 + 1, w/w), ascorbic acid (5 + 1, w/w), and other excipients (aspartame and sucrose) was developed and validated. The final optimized chromatographic method for ion-pair chromatography used an XTerra RP18 column, 3 microm particle size, 50 x 3.0 mm id. The mobile phase consisted of a mixture of acetonitrile and buffer (10 mM sodium octane-1-sulfonate, adjusted with H3PO4 to pH 2.2; 200 + 800, v/v), with a constant flow rate of 0.3 mL/min. The separation was carried out at 30 degrees C, and the injection volume was 3 microL. Fluorescence detection was performed at excitation and emission wavelengths of 275 and 310 nm, respectively. The mobile phase parameters, such as the organic solvent fraction (acetonitrile) in mobile phase as an organic modifier, the concentration of sodium octane-1-sulfonate as a counter-ion, temperature, and pH of mobile phase, were studied. As an alternative to ion-pair chromatography, hydrophilic interaction liquid chromatography (HILIC) was investigated using a Luna HILIC column, 3 microm, 100 x 4.6 mm id. The mobile phase consisted of acetonitrile and buffer (5 mM potassium dihydrogen phosphate, adjusted with H3PO4 to pH 2.5; 750 + 250, v/v) at a flow rate of 0.8 mL/min. The separation was carried out at 25 degrees C, and the injection volume was 5 microL. The proposed method has an advantage of a very simple sample pretreatment, and is much faster than the currently utilized HPLC methods using gradient elution and UV detection. Commercial samples of sachets were successfully analyzed by the proposed HPLC method. PMID:21140654

  1. Fast Monte Carlo Electron-Photon Transport Method and Application in Accurate Radiotherapy

    NASA Astrophysics Data System (ADS)

    Hao, Lijuan; Sun, Guangyao; Zheng, Huaqing; Song, Jing; Chen, Zhenping; Li, Gui

    2014-06-01

    Monte Carlo (MC) method is the most accurate computational method for dose calculation, but its wide application on clinical accurate radiotherapy is hindered due to its poor speed of converging and long computation time. In the MC dose calculation research, the main task is to speed up computation while high precision is maintained. The purpose of this paper is to enhance the calculation speed of MC method for electron-photon transport with high precision and ultimately to reduce the accurate radiotherapy dose calculation time based on normal computer to the level of several hours, which meets the requirement of clinical dose verification. Based on the existing Super Monte Carlo Simulation Program (SuperMC), developed by FDS Team, a fast MC method for electron-photon coupled transport was presented with focus on two aspects: firstly, through simplifying and optimizing the physical model of the electron-photon transport, the calculation speed was increased with slightly reduction of calculation accuracy; secondly, using a variety of MC calculation acceleration methods, for example, taking use of obtained information in previous calculations to avoid repeat simulation of particles with identical history; applying proper variance reduction techniques to accelerate MC method convergence rate, etc. The fast MC method was tested by a lot of simple physical models and clinical cases included nasopharyngeal carcinoma, peripheral lung tumor, cervical carcinoma, etc. The result shows that the fast MC method for electron-photon transport was fast enough to meet the requirement of clinical accurate radiotherapy dose verification. Later, the method will be applied to the Accurate/Advanced Radiation Therapy System ARTS as a MC dose verification module.

  2. Development of an HPLC method for the determination of tetranortriterpenoids in Carapa guianensis seed oil by experimental design.

    PubMed

    Tappin, Marcelo Raul Romero; Nakamura, Marcos Jun; Siani, Antonio Carlos; Lucchetti, Leonardo

    2008-12-01

    Carapa guianensis crabwood, popularly known in Brazil as "andiroba", is a tree that grows in South and Central America and is used by the local population mainly for its anti-inflammatory and insect anti-feeding activities. Scientific studies on this plant have led to the development of an insect-repellent candle and the investigations of the anti-inflammatory properties of its more important biomarkers-tetranortriterpenoids. These compounds, together with glycerides and fatty acids, are present in the seed oil, the most important commercial product from this plant. The growing scientific and commercial interest in "andiroba oil" has urged the development of adequate analytical methods for assessing its quality. Central composite experimental design is a useful statistical method for the development and optimization of HPLC methods, and has been used for a variety of samples. The aim of this work is to develop a HPLC method for the determination of tetranortriterpenoids in "andiroba" oil, by means of central composite experimental design, as well as to prevalidate this method. PMID:18845411

  3. Development and Validation of a RP-HPLC Method for Determination of Related Substances and Degradants in Entacapone.

    PubMed

    Purnachand, Dasari; Veerareddy, Arava; Ramadevi, Bhoomireddy; Kameswarrao, Ch V S L; Madhusudhanreddy, Bethi

    2016-09-01

    A new reverse phase-liquid chromatography (RP-HPLC) method has been developed for simultaneous determination of entacapone and its pharmacopoeia impurities, in-house impurities and degradation impurities (total 17 analytes). Chromatographic separation was achieved on a C18 column (size: 250 × 4.6 mm; 5 µm particle size) at a flow rate of 1.0 mL/min with 210 nm detection. The mobile phase (MP) consists of 1.361 g of potassium di-hydrogen phosphate and 1.742 g of di-potassium phosphate in 1.0 L water, pH adjusted to 2.5 with ortho phosphoric acid (MP-A) and acetonitrile (MP-B) through gradient elution. The product was subjected to stress conditions such as acid, base, peroxide, thermal and photolytic degradation. Two new impurities above 2% level were observed and isolated through preparative HPLC and well characterized. However, no interference observed due to degradation impurities and entacapone and its EP impurities, in-house impurities. As part of the method validation, specificity, limit of detection, limit of quantitation (LOQ), linearity, accuracy, precision, robustness and ruggedness were determined. LOQ values were achieved between 0.01 and 0.04%. Good linearity (r(2) > 0.99) was obtained ranging from LOQ to 150%. Recovery was verified for all impurities at concentrations ranging from LOQ to 150%. Hence, a newly developed RP-HPLC method was capable for well separation of all analytes with acceptable resolution and tailing factor. PMID:27165569

  4. HPLC method for the determination of phytochelatin synthase activity specific for soft metal ion chelators.

    PubMed

    Ogawa, Shinya; Yoshidomi, Takahiro; Shirabe, Tomoo; Yoshimura, Etsuro

    2010-04-01

    Phytochelatins (PCs) are nonprotein peptides with the general structure (gamma-Glu-Cys)(n)-Gly (PC(n)), where n is greater than or equal to 2. They are synthesized through a reaction catalyzed by phytochelatin synthase (PCS) in the presence of metal cations and using the tripeptide glutathione (gamma-Glu-Cys-Gly) and/or previously synthesized PC(n) as the substrate. Here, a highly sensitive assay for PCS activity was devised, in which the dequenching of Cu(I)-bathocuproinedisulfonate complexes was used in the detection system of a reversed-phase high-performance liquid chromatograph. Using recombinant PCS from the higher plant Arabidopsis thaliana (rAtPCS1), this assay system was capable of determining PCS activity based on an amount of the enzyme preparation that was 100-fold less than that required for the 5,5'-dithiobis(2-nitrobenzoic acid) assay method. Although adsorption of the enzyme onto the reaction vessel hindered accurate activity determination, the inclusion of bovine serum albumin successfully resolved this issue. This method is a powerful tool for investigating PCS enzyme mechanisms with respect to the roles of metal ions. PMID:20074807

  5. Stability-indicating HPLC Method for Simultaneous Determination of Montelukast and Fexofenadine Hydrochloride

    PubMed Central

    Pankhaniya, Mona; Patel, Parula; Shah, J. S.

    2013-01-01

    A simple, specific, accurate, and stability-indicating reversed-phase high-performance liquid chromatographic method was developed for the simultaneous determination of montelukast and fexofenadine hydrochloride, using a Lichrospher® 100, RP-18e column and a mobile phase composed of methanol:0.1% o-phosphoric acid (90:10 v/v), pH 6.8. The retention times of montelukast and fexofenadine hydrochloride were found to be 10.16 and 12.03 min, respectively. Linearity was established for montelukast and fexofenadine hydrochloride in the range of 2-10 μg/ml and 24-120 μg/ml, respectively. The percentage recoveries of montelukast and fexofenadine hydrochloride were found to be in the range of 99.09 and 99.81%, respectively. Both the drugs were subjected to acid and base hydrolysis, oxidation, photolytic, and thermal degradation conditions. The degradation products of montelukast and fexofenadine hydrochloride were well resolved from the pure drug with significant differences in their retention time values. This method can be successfully employed for simultaneous quantitative analysis of montelukast and fexofenadine hydrochloride in bulk drugs and formulations. PMID:24082344

  6. RP-HPLC Method for the Determination of Losartan Potassium and Ramipril in Combined Dosage Form

    PubMed Central

    Rao, K. Srinivasa; Srinivas, K.

    2010-01-01

    A simple, specific and accurate reverse phase liquid chromatographic method was developed for the simultaneous determination of losartan potassium and ramipril in table dosage forms. A hypersil ODS C18, 4.6×250 mm, 5 μm column in isocratic mode, with mobile phase acetonitrile:methanol:10 mM tetra butyl ammonium hydrogen sulphate in water in the ratio of 30:30:40% v/v/v was used. The flow rate was 1.0 ml/min and effluent was monitored at 210 nm. The retention times of losartan potassium and ramipril were 4.7 and 3.3 min, respectively. The linearity range for losartan potassium and ramipril were in the range of 0.04-100 μg/ml and 0.2-300 μg/ml, respectively. The proposed method was also validated and successfully applied to the estimation of losartan potassium and ramipril in combined tablet formulations. PMID:20582199

  7. HPLC method for the simultaneous quantification of the major organic acids in Angeleno plum fruit

    NASA Astrophysics Data System (ADS)

    Wang, Yanwei; Wang, Jing; Cheng, Wei; Zhao, Zhilei; Cao, Jiankang

    2014-08-01

    A method was developed to profile major organic acids in Angeleno fruit by high performance liquid chromatography. Organic acids in plum were extracted by water with ultra- sonication at 50°C for 30 min. The extracts were chromatographed on Waters Atlantis T3 C18 column (4.6 mm×250 mm, 5 μm) with 0.01mol/L sulfuric acid and water as mobile phase, and flow rate was 0.5 ml/min. The column temperature was 40C, and chromatography was monitored by a diode array detector at 210 nm. The result showed that malic acid, citric acid, tartaric acid, oxalic acid, pyruvic acid, acetic acid, succinic acid in Angeleno plum, and the malic acid was the major organic acids. The coefficient of determination of the standard calibration curve is R2 > 0.999. The organic acids recovery ranged from 99.11% for Malic acid to 106.70% for Oxalic acid, and CV (n=6) ranged from 0.95% for Malic acid to 6.23% for Oxalic acid, respectively. The method was accurate, sensitive and feasible in analyzing the organic acids in Angeleno plum.

  8. A quantitative HPLC-UV method for determination of serum sorafenib and sorafenib N-oxide and its application in hepatocarcinoma patients.

    PubMed

    Shimada, Miki; Okawa, Hoshimi; Maejima, Takahiro; Yanagi, Toshiki; Hisamichi, Kanehiko; Matsuura, Masaki; Akasaka, Kazutoshi; Tsuchiya, Masami; Kondo, Yasuteru; Shimosegawa, Tooru; Mori, Masaru; Maekawa, Masamitsu; Suzuki, Hiroyuki; Mano, Nariyasu

    2014-01-01

    Sorafenib, an oral multi-kinase inhibitor, has been approved for treatment of advanced renal-cell and hepatocellular carcinoma (HCC). However, 20% of HCC patients taking sorafenib are forced to withdraw due to adverse effects within one month after administration. Orally administered sorafenib is oxidatively metabolized, predominantly by cytochrome P450 3A4 (CYP3A4), in small-intestinal mucosa or liver. We aimed to characterize the CYP3A4-mediated metabolism of sorafenib in HCC patients and explore the contribution of the major metabolite sorafenib N-oxide to adverse effects and therapeutic efficacy. We have therefore developed a method for quantitative determination of sorafenib and its N-oxide in the present study. To optimize the preanalytical procedure, we initially ascertained the solubility of the analytes. Because they are lipophilic, solvents containing more than 40% acetonitrile were required for efficient recovery. The pretreatment procedure that we ultimately developed consists of acetonitrile precipitation, followed by extraction using octadecyl silyl-silica gel to eliminate water-soluble and hydrophilic components of serum. Application of this procedure before HPLC enabled accurate and reproducible quantitation of analytes in a linear range from 0.03 to 30 μg/mL. After characterizing the peaks in the HPLC-ultraviolet chromatogram obtained from a medicated patient by LC-tandem mass spectrometry, we applied this method to HCC patients taking sorafenib, showing large inter-individual differences in the pharmacokinetic profile. In conclusion, our assay system should be useful for follow-up of patients taking sorafenib and for exploring the association between the pharmacokinetics of sorafenib and its N-oxide and the adverse effects or therapeutic efficacy. PMID:24872323

  9. An accurate method of extracting fat droplets in liver images for quantitative evaluation

    NASA Astrophysics Data System (ADS)

    Ishikawa, Masahiro; Kobayashi, Naoki; Komagata, Hideki; Shinoda, Kazuma; Yamaguchi, Masahiro; Abe, Tokiya; Hashiguchi, Akinori; Sakamoto, Michiie

    2015-03-01

    The steatosis in liver pathological tissue images is a promising indicator of nonalcoholic fatty liver disease (NAFLD) and the possible risk of hepatocellular carcinoma (HCC). The resulting values are also important for ensuring the automatic and accurate classification of HCC images, because the existence of many fat droplets is likely to create errors in quantifying the morphological features used in the process. In this study we propose a method that can automatically detect, and exclude regions with many fat droplets by using the feature values of colors, shapes and the arrangement of cell nuclei. We implement the method and confirm that it can accurately detect fat droplets and quantify the fat droplet ratio of actual images. This investigation also clarifies the effective characteristics that contribute to accurate detection.

  10. Development and validation of a HPLC method for determination of degree of polymerization of xylo-oligosaccharides.

    PubMed

    Pu, Jianghua; Zhao, Xia; Wang, Qingchi; Wang, Yingdi; Zhou, Hui

    2016-12-15

    A reliable reversed-phase HPLC method was developed for high resolution separation and high sensitivity determination of xylo-oligosaccharides (XOS) with degree of polymerization from 2 to 8. The method was carried out on a Kromasil C18 column using pre-column derivatization with 1-phenyl-3-methyl-5-pyrazolone (PMP) and UV detection at 245nm. The effects of pH value of mobile phase, volume proportion of acetonitrile, concentration of ammonium acetate buffer and flow rate on the retention time and degree of separation of XOS derivatives were investigated. A satisfactory result was achieved in 25min with a mobile phase of 10mmol/L ammonium acetate buffer (pH5.5)-acetonitrile by a gradient elution at 0.8mL/min. In addition, this method was validated by liquid chromatography-tandem mass spectroscopy (LC-MS) analysis and several uncertain compounds were identified. The proposed HPLC method is suitable for the compositional analysis and quality control of XOS. PMID:27451231

  11. Improved RP-HPLC method to determine biapenem in human plasma/urine and its application to a pharmacokinetic study.

    PubMed

    Zhao, Libo; Liu, Yi; Kou, Zhibin; Bayasi, Aidijie; Cai, Huan; Zhang, Chunyan; Wang, Qian; Li, Yuzhen; Fang, Yi

    2011-01-01

    Existing methods to determine biapenem (CAS 120410-24-4), a carbapenem, either lacked sensitivity/reproducibility or had no internal standard as a control. Here an improved reversed-phase high-performance liquid chromatographic (RP-HPLC) method was established in human plasma and urine. After adding p-aminobenzoic acid as the internal standard to plasma or urine, plasma samples were ultra-filtrated and urine samples were diluted directly. Chromatographic separations were carried out on a 4.6 mm x 150 mm column with acetonitrile-0.1 mol/l sodium acetate (2:98, v:v; pH 4.38 or 4.00) as mobile phase and UV detection at 300 nm. The extraction recovery was 91.51% for biapenem at the concentration level of 5 microg /ml in human plasma. The linear quantification range of the method was 0.1 to approximately 50 microg /ml for plasma and urine, with linear correlation coefficients greater than 0.998. The intra-day and inter-day relative standard deviations (R.S.D.) for biapenem at low, middle and high levels in human samples were less than 12.51% for plasma and less than 7.05% for urine. The RP-HPLC method was successfully applied to pharmacokinetic studies, in which healthy subjects received multiple doses of biapenem (300 mg, i.v., b.i.d., for 5 continuous days). The pharmacokinetic results are presented. PMID:21528646

  12. Determination of three alkylphenol isomers in various water samples using a new HPLC method based on a duet stationary phase.

    PubMed

    Cruceru, Ioana; Florescu, Andreea; Badea, Irinel Adriana; Vladescu, Luminita

    2012-10-01

    The level of three alkylphenols (APs) 4-nonylphenol, 4-octylphenol and 4-tert-octylphenol was monitored in various water samples using a new developed and validated HPLC method. The HPLC method employed a column with a mixed-mode stationary phase (C18/SCX) using a mobile phase of water to methanol = 15:85 (v/v) delivered at a flow rate of 1 mL/min at room temperature. Both diode array, DAD and fluorescence, FLD detectors were employed. The method is linear when APs concentration ranged from 0.025 to 0.5 μg/mL with a DAD detection at 279 nm and between 0.0008 and 0.1 μg/mL when the detection was made by FLD (excitation at 220 nm, emission at 315 nm). The limit of detection and limit of quantitation for alkylphenols were found to be 5 and 15 ng/mL, respectively (detection by DAD). The method was employed with good results for the determination of APs in the presence of polycyclic aromatic hydrocarbons in various water samples. PMID:22068312

  13. Liquid propellant rocket engine combustion simulation with a time-accurate CFD method

    NASA Technical Reports Server (NTRS)

    Chen, Y. S.; Shang, H. M.; Liaw, Paul; Hutt, J.

    1993-01-01

    Time-accurate computational fluid dynamics (CFD) algorithms are among the basic requirements as an engineering or research tool for realistic simulations of transient combustion phenomena, such as combustion instability, transient start-up, etc., inside the rocket engine combustion chamber. A time-accurate pressure based method is employed in the FDNS code for combustion model development. This is in connection with other program development activities such as spray combustion model development and efficient finite-rate chemistry solution method implementation. In the present study, a second-order time-accurate time-marching scheme is employed. For better spatial resolutions near discontinuities (e.g., shocks, contact discontinuities), a 3rd-order accurate TVD scheme for modeling the convection terms is implemented in the FDNS code. Necessary modification to the predictor/multi-corrector solution algorithm in order to maintain time-accurate wave propagation is also investigated. Benchmark 1-D and multidimensional test cases, which include the classical shock tube wave propagation problems, resonant pipe test case, unsteady flow development of a blast tube test case, and H2/O2 rocket engine chamber combustion start-up transient simulation, etc., are investigated to validate and demonstrate the accuracy and robustness of the present numerical scheme and solution algorithm.

  14. A convenient method for the quantitative determination of elemental sulfur in coal by HPLC analysis of perchloroethylene extracts

    USGS Publications Warehouse

    Buchanan, D.H.; Coombs, K.J.; Murphy, P.M.; Chaven, C.

    1993-01-01

    A convenient method for the quantitative determination of elemental sulfur in coal is described. Elemental sulfur is extracted from the coal with hot perchloroethylene (PCE) (tetrachloroethene, C2Cl4) and quantitatively determined by HPLC analysis on a C18 reverse-phase column using UV detection. Calibration solutions were prepared from sublimed sulfur. Results of quantitative HPLC analyses agreed with those of a chemical/spectroscopic analysis. The HPLC method was found to be linear over the concentration range of 6 ?? 10-4 to 2 ?? 10-2 g/L. The lower detection limit was 4 ?? 10-4 g/L, which for a coal sample of 20 g is equivalent to 0.0006% by weight of coal. Since elemental sulfur is known to react slowly with hydrocarbons at the temperature of boiling PCE, standard solutions of sulfur in PCE were heated with coals from the Argonne Premium Coal Sample program. Pseudo-first-order uptake of sulfur by the coals was observed over several weeks of heating. For the Illinois No. 6 premium coal, the rate constant for sulfur uptake was 9.7 ?? 10-7 s-1, too small for retrograde reactions between solubilized sulfur and coal to cause a significant loss in elemental sulfur isolated during the analytical extraction. No elemental sulfur was produced when the following pure compounds were heated to reflux in PCE for up to 1 week: benzyl sulfide, octyl sulfide, thiane, thiophene, benzothiophene, dibenzothiophene, sulfuric acid, or ferrous sulfate. A sluury of mineral pyrite in PCE contained elemental sulfur which increased in concentration with heating time. ?? 1993 American Chemical Society.

  15. A New Validated HPLC Method for the Simultaneous Determination of 2-phenoxyethanol, Methylparaben, Ethylparaben and Propylparaben in a Pharmaceutical Gel

    PubMed Central

    Shabir, G. A.

    2010-01-01

    A novel reversed-phase HPLC method has been developed and validated for the simultaneous determination of 2-phenoxyethanol, methylparaben, ethylparaben and propylparaben preservatives. The method uses a Lichrosorb C8 (150×4.6 mm, 5 µm) column and isocratic elution. The mobile phase consisted of a mixture of acetonitrile, tetrahydrofuran and water (21:13:66, v/v/v), pumped at a flow rate of 1 ml/min. The UV detection was set at 258 nm. The method was validated with respect to accuracy, precision (repeatability and intermediate precision), specificity, linearity and range. All the parameters examined met the current recommendations for bioanalytical method validation. The developed method was successfully applied to the determination of commercially available pharmaceutical gel products for these preservatives. The procedure describes here is simple, selective and reliable for routine quality control analysis and stability tests. PMID:21218050

  16. A New Validated HPLC Method for the Simultaneous Determination of 2-phenoxyethanol, Methylparaben, Ethylparaben and Propylparaben in a Pharmaceutical Gel.

    PubMed

    Shabir, G A

    2010-07-01

    A novel reversed-phase HPLC method has been developed and validated for the simultaneous determination of 2-phenoxyethanol, methylparaben, ethylparaben and propylparaben preservatives. The method uses a Lichrosorb C8 (150×4.6 mm, 5 µm) column and isocratic elution. The mobile phase consisted of a mixture of acetonitrile, tetrahydrofuran and water (21:13:66, v/v/v), pumped at a flow rate of 1 ml/min. The UV detection was set at 258 nm. The method was validated with respect to accuracy, precision (repeatability and intermediate precision), specificity, linearity and range. All the parameters examined met the current recommendations for bioanalytical method validation. The developed method was successfully applied to the determination of commercially available pharmaceutical gel products for these preservatives. The procedure describes here is simple, selective and reliable for routine quality control analysis and stability tests. PMID:21218050

  17. Fast and accurate determination of the Wigner rotation matrices in the fast multipole method.

    PubMed

    Dachsel, Holger

    2006-04-14

    In the rotation based fast multipole method the accurate determination of the Wigner rotation matrices is essential. The combination of two recurrence relations and the control of the error accumulations allow a very precise determination of the Wigner rotation matrices. The recurrence formulas are simple, efficient, and numerically stable. The advantages over other recursions are documented. PMID:16626188

  18. The U.S. Department of Agriculture Automated Multiple-Pass Method accurately assesses sodium intakes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Accurate and practical methods to monitor sodium intake of the U.S. population are critical given current sodium reduction strategies. While the gold standard for estimating sodium intake is the 24 hour urine collection, few studies have used this biomarker to evaluate the accuracy of a dietary ins...

  19. Comparative study of three analysis methods (TTGE, flow cytometry and HPLC) for xenobiotic impact assessment on phytoplankton communities.

    PubMed

    Stachowski-Haberkorn, Sabine; Quiniou, Louis; Beker, Beatriz; Haberkorn, Hansy; Marie, Dominique; de la Broise, Denis

    2009-04-01

    The impacts of the fungicide Opus (epoxiconazole) on marine phytoplankton communities were assessed in a 12-day field experiment using in situ microcosms maintained underwater at 6 m depth. Three community analysis methods were compared for their sensitivity threshold in fungicide impact detection. When phytoplankton communities were exposed to 1 microg l(-1) of epoxiconazole, no effects could be demonstrated using TTGE (Temporal Temperature Gradient gel Electrophoresis), flow cytometry or HPLC. When exposed to 10 microg l(-1), TTGE fingerprints from PCR amplified 18S rDNA of communities exhibited significant differences compared with controls (ANOSIM, P = 0.028). Neither flow cytometry counts, nor HPLC pigment profiles allowed to show significant differences in microcosms exposed to 10 microg l(-1) of epoxiconazole. When exposed to 100 microg l(-1), all three methods allowed to detect significant differences in treated microcosms, as compared to controls. The TTGE analysis appears in this study as the most sensitive method for fungicide impact assessment on eukaryote microbial communities. PMID:19096934

  20. Stability-Indicating HPLC Method for Simultaneous Determination of Chloramphenicol, Dexamethasone Sodium Phosphate and Tetrahydrozoline Hydrochloride in Ophthalmic Solution

    PubMed Central

    AlAani, Hashem; Alnukkary, Yasmin

    2016-01-01

    Purpose: A simple stability-indicating RP-HPLC assay method was developed and validated for quantitative determination of Chloramphenicol, Dexamethasone Sodium Phosphate and Tetrahydrozoline Hydrochloride in ophthalmic solution in the presence of 2-amino-1-(4-nitrophenyl)propane-1,3-diol, a degradation product of Chloramphenicol, and Dexamethasone, a degradation product of Dexamethasone Sodium Phosphate. Methods: Effective chromatographic separation was achieved using C18 column (250 mm, 4.6 mm i.d., 5 μm) with isocratic mobile phase consisting of acetonitrile - phosphate buffer (pH 4.0; 0.05 M) (30:70, v/v) at a flow rate of 1 mL/minute. The column temperature was maintained at 40°C and the detection wavelength was 230 nm. Results: The proposed HPLC procedure was statistically validated according to the ICH guideline, and was proved to be stability-indicating by resolution of the APIs from their forced degradation products. Conclusion: The developed method is suitable for the routine analysis as well as stability studies. PMID:27123429

  1. Performance review of a fast HPLC-UV method for the quantification of chlorogenic acids in green coffee bean extracts.

    PubMed

    Craig, Ana Paula; Fields, Christine; Liang, Ningjian; Kitts, David; Erickson, Aron

    2016-07-01

    The aim of this study was to test the performance of a HPLC method, designated for rapid quantification of chlorogenic acids (CGA) in green coffee extract (GCE). The precision statistics associated with the method were assessed using three independent laboratories with five samples analyzed in triplicate. Seven main CGA isomers (3-CQA, 5-CQA, 4-CQA, 5-FQA, 3,4-diCQA, 3,5-diCQA and 4,5-diCQA) were quantified. The concentration of total CGA in the samples varied from 32.24% to 52.65% w/w. The repeatability and reproducibility standard deviations for the determination of individual isomers varied, respectively, from 0.01 to 0.28 and 0.05-1.59. The repeatability and reproducibility standard deviations of the calculated total CGA, corresponding to the sum of the seven main CGA isomers, varied respectively, from 0.17 to 0.58 and 0.55-2.01. The fast HPLC method evaluated in this study was considered precise and appropriate for the determination of CGA in GCE. PMID:27154703

  2. Recent Advances in Analytical Methods on Lipoprotein Subclasses: Calculation of Particle Numbers from Lipid Levels by Gel Permeation HPLC Using "Spherical Particle Model".

    PubMed

    Okazaki, Mitsuyo; Yamashita, Shizuya

    2016-01-01

    Recently, we developed an analytical method for determining the lipid levels and particle numbers in lipoprotein subclasses covering a wide size range from chylomicrons to small high density lipoproteins, by using gel permeation high-performance liquid chromatography (GP-HPLC). The challenges in analytical methods on lipoprotein subclasses have been addressed from 1980 by Hara and Okazaki using commercial TSK gel permeation columns. Later, the improvements in the hardware, separation and detection of lipoproteins, and the data processing software, using a Gaussian distribution approximation to calculate lipid levels of lipoprotein subclasses, have been extensively utilized in these analytical methods for over thirty years. In this review, we describe on the recent advances in analytical methods on lipoprotein subclasses based on various techniques, and the calculation of particle numbers from lipid levels by GPHPLC using the "spherical particle model". Free/ester ratio of cholesterol in particular lipoprotein subclass was accurately estimated from triglyceride, total cholesterol (free and esterified) and the size of the particle based on this model originally proposed by Shen and Kezdy. PMID:27041512

  3. Second-order accurate finite volume method for well-driven flows

    NASA Astrophysics Data System (ADS)

    Dotlić, M.; Vidović, D.; Pokorni, B.; Pušić, M.; Dimkić, M.

    2016-02-01

    We consider a finite volume method for a well-driven fluid flow in a porous medium. Due to the singularity of the well, modeling in the near-well region with standard numerical schemes results in a completely wrong total well flux and an inaccurate hydraulic head. Local grid refinement can help, but it comes at computational cost. In this article we propose two methods to address the well singularity. In the first method the flux through well faces is corrected using a logarithmic function, in a way related to the Peaceman model. Coupling this correction with a non-linear second-order accurate two-point scheme gives a greatly improved total well flux, but the resulting scheme is still inconsistent. In the second method fluxes in the near-well region are corrected by representing the hydraulic head as a sum of a logarithmic and a linear function. This scheme is second-order accurate.

  4. Determination of ng rivanol in human plasma by SPE-HPLC method.

    PubMed

    Guo, Zhiyong; Wei, Danyi; Gan, Ning; Xie, Hongzhen; Yu, Xufei

    2007-07-01

    A high-performance liquid chromatography assay is described for the determination of rivanol in human plasma. Solid-phase extraction cartridges are used to extract plasma samples. Separation is done by using a C18 column. The mobile phase is a mixture of methanol-0.05% sodium dodecylsulfonate (70:30, v/v, pH 3), with the flow rate at 1.0 mL/min. UV detection of rivanol is at 272 nm. The calibration curve is linear in the concentration range of 1x10(-8) mol/L to 1x10(-5) mol/L with linear correlation coefficient r equal to 0.9998. The limit of detection for the assay is 3x10(-9) mol/L, corresponding to 1.1 ng/mL. Precision, expressed as the within- and between-day coefficient of variation, is 3.3-8.1% and 4.1-9.5%, respectively, at plasma control samples of 5x10(-8), 5x10(-7), and 5x10(-6) mol/L. And the recovery ranges from 94.8% to 107.2%. The selectivity of the method is confirmed. Plasma samples are stable for at least 15 days if they are stored lightproof at -20 degrees C. This method is simple, sensitive, and accurate, and it allows for the determination ng rivanol in human plasma. It could be applied to assessing its plasma level in women receiving an intra-amniotic injection of rivanol. PMID:17626720

  5. Matrine and oxymatrine in corroborant plant extracts and fertilizers: HPLC/MS-MS method development and single-laboratory validation.

    PubMed

    Sabatino, Leonardo; Scarangella, Michele; Lazzaro, Francesco; Scordino, Monica; Picariello, Giavanna; Leotta, Claudia; Traulo, Pasqualino; Gagliano, Giacomo

    2015-01-01

    A reversed phase high-performance liquid chromatographic method (HPLC/MS-MS) has been developed and validated for detection of alkaloids matrine and oxymatrine in fertilizer with labeled enhancer plant defense activities. The analytical method was validated statistically. The results show a strong matrix effect, requiring quantification by standard addition method. The regression lines showed r(2) > 0.994. Recoveries ranging from 97 to 104% were obtained for the fortification level of 0.01% wt wt(-1) and the relative standard deviations ranged from 3 to 4% (n = 10). The limits of detection were below 0.0001% wt wt(-1), while the limits of quantification did not exceed 0.0004% wt wt(-1). The method is currently applied in ICQRF Laboratory of Catania on fertilized and corroborant plant extract collected in the Italian market in the frame of MIPAAF institutional quality control activity, with the aim to dectect these unpermitted active substances. PMID:26252197

  6. Development of an immunoaffinity chromatography and HPLC-UV method for determination of 16 sulfonamides in feed.

    PubMed

    Kim, Ho Jin; Jeong, Min Hee; Park, Hye Jin; Kim, Won Chan; Kim, Jang Eok

    2016-04-01

    A novel and simple method for detecting 16 sulfonamides (SAs) in animal feed using high performance liquid chromatography equipped with a photo-diode array detector (HPLC/PDA) and immunoaffinity chromatography was developed. The chromatographic peaks of the 16 SAs were successfully identified by comparing their retention times and UV spectra with reference standards. Method validation was performed with linearity, sensitivity, selectivity, accuracy and precision. The limits of detection (LODs) for the instrument used to study sulfonamides ranged from 14.1 to 45.0 μg/kg, and the limits of quantification (LOQs) ranged from 46.9 to 150.0 μg/kg. Average recoveries of the 16 SAs ranged from 78.2% to 105.2%. Method replication resulted in intraday and interday peak area variation of <5.5%. The developed method was specific and reliable and is suited for the routine analysis of SAs in animal feed. PMID:26593600

  7. European official control of food: Determination of histamine in fish products by a HPLC-UV-DAD method.

    PubMed

    Altieri, I; Semeraro, A; Scalise, F; Calderari, I; Stacchini, P

    2016-11-15

    The evaluation of histamine content in fish and fishery products, responsible for scombroid poisoning, is essential to guarantee the safety of food. EU regulation requires validated analytical methods to ensure the verification of compliance with food law in official control activity. To this aim a previous gradient RP-HPLC method with DAD detection was modified and validated, according to international guidelines. The reliability of results was tested by analysing fish reference materials within the participation in European proficiency tests. The method has been used for the analysis of real samples consisting of several fish-based products with considerable differences in matrix composition. This characteristic is of great relevance to be able of apply the method in the field of official control. PMID:27283685

  8. Accurate determination of specific heat at high temperatures using the flash diffusivity method

    NASA Technical Reports Server (NTRS)

    Vandersande, J. W.; Zoltan, A.; Wood, C.

    1989-01-01

    The flash diffusivity method of Parker et al. (1961) was used to measure accurately the specific heat of test samples simultaneously with thermal diffusivity, thus obtaining the thermal conductivity of these materials directly. The accuracy of data obtained on two types of materials (n-type silicon-germanium alloys and niobium), was + or - 3 percent. It is shown that the method is applicable up to at least 1300 K.

  9. An Effective Method to Accurately Calculate the Phase Space Factors for β - β - Decay

    DOE PAGESBeta

    Neacsu, Andrei; Horoi, Mihai

    2016-01-01

    Accurate calculations of the electron phase space factors are necessary for reliable predictions of double-beta decay rates and for the analysis of the associated electron angular and energy distributions. We present an effective method to calculate these phase space factors that takes into account the distorted Coulomb field of the daughter nucleus, yet it allows one to easily calculate the phase space factors with good accuracy relative to the most exact methods available in the recent literature.

  10. HPTLC and RP-HPLC methods for simultaneous determination of Paracetamol and Pamabrom in presence of their potential impurities.

    PubMed

    Abdelaleem, Eglal A; Naguib, Ibrahim A; Hassan, Eman S; Ali, Nouruddin W

    2015-10-10

    Two chromatgraphic methods were developed for determination of Paracetamol (PCM) and Pamabrom (PAM) in presence of P-aminophenol (PAP) and Theophylline (THEO) as potential impurities of both drugs respectively. First method is HPTLC which depends on separation and quantitation of the studied drugs on aluminum plates pre-coated with silica gel 60 F₂₅₄ as a stationary phase using chloroform:methanol:ethyl acetate:glacial acetic acid (8:0.8:0.6:0.2, v/v/v/v) as mobile phase followed by densitometric measurement of the bands at 254 nm. Second method is RP-HPLC which comprises separation of the studied drugs on a Phenomenex C8 column by gradient elution using mobile phase consisting of sodium dihydrogen phosphate buffer (0.05 M): methanol:acetonitrile (85:10:5, v/v/v) at a flow rate of 1 mL/min for first 7.5 min and (70:20:10, v/v/v) at a flow rate of 1.5 mL/min for the next 5 min. The proposed methods were successfully applied for determination of the potential impurities of PCM and PAM after resolving them from the pure drugs. The developed methods have been validated and proved to meet the requirements delineated by ICH guidelines with respect to linearity, accuracy, precision, specificity and robustness. The validated methods were successfully applied for determination of the studied drugs in their pharmaceutical formulation. The results were statistically compared to those obtained by the reported RP-HPLC method where no significant difference was found; indicating the ability of proposed methods to be used for routine quality control analysis of these drugs. PMID:26001162

  11. Simplified RP-HPLC method for multi-residue analysis of abamectin, emamectin benzoate and ivermectin in rice.

    PubMed

    Xie, Xianchuan; Gong, Shu; Wang, Xiaorong; Wu, Yinxing; Zhao, Li

    2011-01-01

    A rapid, reliable and sensitive reverse-phase high-performance liquid chromatography method with fluorescence detection (RP-FLD-HPLC) was developed and validated for simultaneous analysis of the abamectin (ABA), emamectin (EMA) benzoate and ivermectin (IVM) residues in rice. After extraction with acetonitrile/water (2 : 1) with sonication, the avermectin (AVMs) residues were directly derivatised by N-methylimidazole (N-NMIM) and trifluoroacetic anhydride (TFAA) and then analysed on RP-FLD-HPLC. A good linear relationship (r(2 )> 0.99) was obtained for three AVMs ranging from 0.01 to 5 microg ml(-1), i.e. 0.01-5.0 microg g(-1) in rice matrix. The limit of detection (LOD) and the limit of quantification (LOQ) were between 0.001 and 0.002 microg g(-1) and between 0.004 and 0.006 microg g(-1), respectively. Recoveries were from 81.9% to 105.4% and precision less than 12.4%. The proposed method was successfully applied to routine analysis of the AVMs residues in rice. PMID:21132591

  12. Development of a HPLC method for the simultaneous determination of several B-vitamins and ascorbic acid.

    PubMed

    Khor, S; Tee, E S

    1996-03-01

    In cognizance of the difficulties involved in the colorimetric and titrimetric methods for the determination of individual vitamins, this laboratory has been carrying out a series of studies into the use of HPLC for improved analysis of these nutrients. Preliminary studies have been carried out for the determination of four B-vitamins. The present paper reports on further improvements made to enable the simultaneous determination of eight vitamins i.e. B1, B2, B6, B12, C, niacin, niacinamide and folic acid. Trials were carried out to determine the most suitable chromatographic system include changing the proportion of methanol in the mobile phase, the use of different ion-pairing reagents and other additives such as triethylamine and ammonia. Three sets of HPLC mobile phase systems are proposed to enable successful separation of all eight vitamins in less than 20 minutes, varying slightly with the type of ion-pairing reagent and mobile phase additive. This laboratory is currently carrying out trials to determine if the developed methods could be used for the determination of pharmaceutical products and food samples. PMID:22692099

  13. Regioselective deprotection of the monosaccharide-bearing thiocyanomethyl group at the anomeric position monitored by reversed-phase HPLC method.

    PubMed

    Abualassal, Qais; Al Azzam, Khaldun M; Jilani, Jamal A

    2016-09-01

    In the current work, the investigation and development of a chemo-enzymatic approach for the synthesis of neo-glycoproteins have been studied. This strategy is based on the regioselective enzymatic hydrolysis of peracetylated monosaccharide, functionalized at the anomeric position (C1) as 1-thio-(S-cyanomethyl) group, a precursor of the 2- iminomethoxyethyl thioglycosides-linker for protein glycosylation, catalyzed by immobilized enzymes to obtain selectively monodeprotected compounds. The use of this activation in C1 is the most frequently used strategy for glycoprotein preparation. The selected biocatalysts are the lipase from Candida rugosa and the acetyl xylan esterase from Bacillus pumilus. A reversed-phase high-performance liquid-chromatographic (HPLC) method for monitoring the regioselective deprotection reaction has been developed. The developed HPLC method was used as a fingerprint to follow the hydrolysis of substrate 1 to substrate 1a and to determine its purity and yield. Moreover, the obtained compound was further purified by flash chromatography. The obtained compound 1a was further characterized using (1) H, (13) C NMR, correlation spectroscopy (COSY) and heteronuclear multiple bond correlation. The resulting product can be used as an intermediate for the preparation of di- and more complex oligosaccharides aimed at protein conjugation. Copyright © 2016 John Wiley & Sons, Ltd. PMID:26864255

  14. Investigation of the stabilizer elimination during the washing step of charged PLGA microparticles utilizing a novel HPLC-UV-ELSD method.

    PubMed

    Riehl, Markus; Harms, Meike; Hanefeld, Andrea; Mäder, Karsten

    2015-08-01

    Quantification of stabilizer content in microparticles and other products is of great importance for formulation development, drug product quality control as well as for reproducible manufacturing. A fast and sensitive HPLC method with evaporative light scattering detection (ELSD) capable of detecting docusate sodium (DOSS), poly (lactic-co-glycolic acid) (PLGA; Resomer RG 503 H) and R-1,2-dioleoyloxy-3-trimethylammonium-propane (DOTAP) in a single run was successfully developed. In contrast to previously described methods, hydrolysis of PLGA as pretreatment is not necessary, thereby enabling accurate quantification of stabilizer next to the intact matrix polymer. This method was used to investigate the impact of washing procedures of polymeric microparticles manufactured either with anionic stabilizer DOSS or with cationic stabilizer DOTAP. High amounts of DOSS were detected in the washing water. This finding was consistent with the result that no DOSS could be detected in the washed and dried microparticles (

  15. A simple and high-resolution HPLC-PDA method for simultaneous quantification of local anesthetics in in vitro buccal permeation enhancement studies.

    PubMed

    Couto, Renê O; Cubayachi, Camila; Lopez, Renata F V; de Gaitani, Cristiane M; Pedrazzi, Vinícius; de Freitas, Osvaldo

    2016-06-01

    A simple, isocratic, high-resolution and prompt HPLC-PDA method was developed and validated for the simultaneous quantification of prilocaine (PCL) and lidocaine (LCL) hydrochlorides in in vitro buccal iontophoresis-driven permeation studies. A reversed-phase C18 column (250 mm x 4.6 mm, 3μm, 110Å) was used for the chromatographic separation. The mobile phase contained acetonitrile: 0.1M sodium phosphate buffer, pH 7.0 (1:1, v/v), plus 0.05% (v/v) diethylamine. The isocratic flow rate was set at 1 mL/min and the detection wavelength was 203 nm. PCL and LCL eluted in 8.9 min and 13 min, respectively, and the system suitability parameters varied within an acceptable range. The method was selective, sensitive, precise, accurate and robust, producing a linear plot at the concentration range of 0.25 to 10 µg/mL. The application of this method was demonstrated by a significant enhancement of the permeation of PCL and LCL with the application of iontophoresis (1 mA/cm(2) per 1 h) through isolated porcine esophageal epithelium. The amount of the drug retained in the epithelium also increased with the application of an electrical current. Copyright © 2015 John Wiley & Sons, Ltd. PMID:26379211

  16. Simultaneous quantitation of aspirin, amlodipine and simvastatin in a fixed dose combination of encapsulated tablet formulation by HPLC-UV method.

    PubMed

    Sultan, Faisal; Shoaib, Muhammad Harris; Yousuf, Rabia Ismail; Ahmed, Farrukh Rafiq; Salam, Faseeh A; Nasiri, Muhammad Iqbal; Khan, Muhammad Atif; Manzoor, Saeed

    2014-09-01

    A high-pressure liquid chromatography (HPLC-UV) based simple and specific method for simultaneous quantitative determination of aspirin, amlodipine besylate and simvastatin in a capsule formulation has been developed and validated according to ICH guidelines. Chromatographic separation of the three drugs was carried out by aSpherisorbODS2 reverse phase column (4.6 x 250 mm; 5 μm) using amobile phase, which consisted of 70: 30 (v/v) mixture of acetonitrile and triethylamine phosphate buffer (pH 3; 0.015 M) with final pH adjusted to 2.5 using dilute ortho-phosphoric acid, at a flow rate of 1mL/min. The eluents were detected at UV wavelength of 237 nm and the retention times for aspirin, amlodipine besylate and simvastatin were ~2.7 mins, ~6.1 mins and ~10.5mins, respectively. This method is suitable and specific for the three drugs and was found to be linear (R2>0.995), accurate, specific, reproducible and robust in the concentration range of 375 to 1125mcg/ml for aspirin, 25 to 75mcg/ml for amlodipine besylate and 50 to 150mcg/ml for simvastatin. This simple and convenient method could be easily utilized for the characterization and quantitation of the three drugs in a single formulation for combination therapy of cardiovascular diseases. PMID:25176250

  17. RP-HPLC method for simultaneous determination of butenafine hydrochloride and betamethasone dipropionate in a cream formulation.

    PubMed

    Bhosale, Suryakant D; Rajput, Sadhana J

    2011-01-01

    An RP-HPLC method has been developed for the simultaneous determination of butenafine hydrochloride and betamethasone dipropionate on an Inertsil C18 column (250 x 4.6 mm id) using a mobile phase gradient consisting of methanol and water at a flow rate of 1 mL/min. Detection was carried out at 254 nm. Retention times of betamethasone dipropionate and butenafine hydrochloride were 4.82 (+/- 0.80) and 16.18 (+/- 0.17) min, respectively. The method was validated with respect to specificity, linearity, accuracy, precision, ruggedness, and robustness. This method is simple, precise, and sensitive, and applicable for the simultaneous quantification of butenafine hydrochloride and betamethasone dipropionate in a cream formulation. PMID:21391486

  18. A simplified HPLC method for simultaneously quantifying ribonucleotides and deoxyribonucleotides in cell extracts or frozen tissues.

    PubMed

    Cross, D R; Miller, B J; James, S J

    1993-07-01

    Agents and conditions that induce alterations in deoxyribonucleotide pools can have important regulatory effects on the rate of DNA synthesis as well as cell cycle progression. A simplified procedure for the separation of both ribonucleoside triphosphates (NTP) and deoxyribonucleoside triphosphates (dNTP) is presented which utilizes reversed phase high-performance liquid chromatography coupled with diode array detection. The simultaneous resolution of NTP and dNTP peaks within the same cell extract effectively eliminates the need for post-extraction steps such as periodate oxidation and/or boronate affinity chromatography previously used to degrade or isolate co-eluting NTP from dNTP. The resolution of two nucleotides, dGTP and ADP, was found empirically to vary with the efficiency of the C18 column. High efficiency columns (> 90,000 plates/m) provided good separation; however, less efficient columns resulted in co-elution of dGTP and ADP. These co-eluting nucleotides can be accurately quantified, if necessary, using diode array technology and a mathematical expression which incorporates molar peak coefficients and peak areas obtained by monitoring at dual wave-lengths. Tissue samples or single cell suspensions were extracted with trichloroacetic acid and the neutralized extract was injected directly into the column without prior lyophilization. The per cent recovery of standards was > or = 99% and replicate extractions within or between samples were highly reproducible (SD < 5%). The single step method described minimizes potential losses associated with post-extraction manipulation and provides the capability to examine alterations in nucleotide precursor-product metabolism under various physiological and pharmacological conditions. PMID:8343561

  19. A Stability-Indicating HPLC Method for the Determination of Nitrosylcobalamin (NO-Cbl), a Novel Vitamin B12 Analog

    PubMed Central

    Dunphy, Michael J.; Sysel, Annette M.; Lupica, Joseph A.; Griffith, Kristie; Sherrod, Taylor

    2014-01-01

    Nitrosylcobalamin (NO-Cbl), a novel vitamin B12 analog and anti-tumor agent, functions as a biologic ‘Trojan horse’, utilizing the vitamin B12 transcobalamin II transport protein and cell surface receptor to specifically target cancer cells. a stability-indicating HPLC method was developed for the detection of NO-Cbl during forced degradation studies. This method utilized an ascentis® RP-amide (150 mm × 4.6 mm, 5 μm) column at 35 °C with a mobile phase (1.0 mL min−1) combining a gradient of methanol and an acetate buffer at pH 6.0. Detection wavelengths of 450 and 254 nm were used to detect corrin and non-corrin-based products, respectively. NO-Cbl, synthesized from hydroxocobalamin and pure nitric oxide gas, was subjected to degradative stress conditions including oxidation, hydrolysis and thermal and radiant energy challenge. The method was validated by assessing linearity, accuracy, precision, detection and quantitation limits and robustness. The method was applied successfully for purity assessment of synthesized NO-Cbl and for the determination of NO-Cbl during kinetic studies in aqueous solution and in solid-state degradation assessments. This HPLC method is suitable for the separation of cobalamins in aqueous and methanolic solutions, for routine detection of NO-Cbl and for purity assessment of synthesized NO-Cbl. additionally, this method has potential application in identification and monitoring of diseases involving altered nitric oxide homeostasis where vitamin B12 therapy is utilized to scavenge excess nitric oxide, subsequently resulting in the in vivo production of NO-Cbl. PMID:24855323

  20. A rapid stability-indicating, fused-core HPLC method for simultaneous determination of β-artemether and lumefantrine in anti-malarial fixed dose combination products

    PubMed Central

    2013-01-01

    Nexus v2.0® to have toxicity risks similar to β-artemether active pharmaceutical ingredient (API) itself. Conclusions A rapid, robust, precise and accurate stability-indicating, quantitative fused-core isocratic HPLC method was developed for simultaneous assay of β-artemether and lumefantrine. This method can be applied in the routine regulatory quality control of FDC products. The in-silico toxicological investigation using Derek Nexus® indicated that the overall toxicity risk for β-artemether-related impurities is comparable to that of β-artemether API. PMID:23631682

  1. A Novel Method for the Accurate Evaluation of Poisson's Ratio of Soft Polymer Materials

    PubMed Central

    Lee, Jae-Hoon; Lee, Sang-Soo; Chang, Jun-Dong; Thompson, Mark S.; Kang, Dong-Joong; Park, Sungchan

    2013-01-01

    A new method with a simple algorithm was developed to accurately measure Poisson's ratio of soft materials such as polyvinyl alcohol hydrogel (PVA-H) with a custom experimental apparatus consisting of a tension device, a micro X-Y stage, an optical microscope, and a charge-coupled device camera. In the proposed method, the initial positions of the four vertices of an arbitrarily selected quadrilateral from the sample surface were first measured to generate a 2D 1st-order 4-node quadrilateral element for finite element numerical analysis. Next, minimum and maximum principal strains were calculated from differences between the initial and deformed shapes of the quadrilateral under tension. Finally, Poisson's ratio of PVA-H was determined by the ratio of minimum principal strain to maximum principal strain. This novel method has an advantage in the accurate evaluation of Poisson's ratio despite misalignment between specimens and experimental devices. In this study, Poisson's ratio of PVA-H was 0.44 ± 0.025 (n = 6) for 2.6–47.0% elongations with a tendency to decrease with increasing elongation. The current evaluation method of Poisson's ratio with a simple measurement system can be employed to a real-time automated vision-tracking system which is used to accurately evaluate the material properties of various soft materials. PMID:23737733

  2. A calibration-independent method for accurate complex permittivity determination of liquid materials

    SciTech Connect

    Hasar, U. C.

    2008-08-15

    This note presents a calibration-independent method for accurate complex permittivity determination of liquid materials. There are two main advantages of the proposed method over those in the literature, which require measurements of two cells with different lengths loaded by the same liquid material. First, it eliminates any inhomogeneity or impurity present in the second sample and decreases the uncertainty in sample thickness. Second, it removes the undesired impacts of measurement plane deterioration on measurements of liquid materials. For validation of the proposed method, we measure the complex permittivity of distilled water and compare its extracted permittivity with the theoretical datum obtained from the Debye equation.

  3. Formation of accurate 1-nm gaps using the electromigration method during metal deposition

    NASA Astrophysics Data System (ADS)

    Naitoh, Yasuhisa; Wei, Qingshuo; Mukaida, Masakazu; Ishida, Takao

    2016-03-01

    We investigate the origin of fabricated nanogap width variations using the electromigration method during metal deposition. This method also facilitates improved control over the nanogap width. A large suppression in the variation is achieved by sample annealing at 373 K during the application of bias voltages for electromigration, which indicates that the variation is caused by structural changes. This electromigration method during metal deposition for the fabrication of an accurate 1-nm gap electrode is useful for single-molecule-sized electronics. Furthermore, it opens the door for future research on integrated sub-1-nm-sized nanogap devices.

  4. Accurate numerical verification of the instanton method for macroscopic quantum tunneling: Dynamics of phase slips

    SciTech Connect

    Danshita, Ippei; Polkovnikov, Anatoli

    2010-09-01

    We study the quantum dynamics of supercurrents of one-dimensional Bose gases in a ring optical lattice to verify instanton methods applied to coherent macroscopic quantum tunneling (MQT). We directly simulate the real-time quantum dynamics of supercurrents, where a coherent oscillation between two macroscopically distinct current states occurs due to MQT. The tunneling rate extracted from the coherent oscillation is compared with that given by the instanton method. We find that the instanton method is quantitatively accurate when the effective Planck's constant is sufficiently small. We also find phase slips associated with the oscillations.

  5. A fast and accurate method to predict 2D and 3D aerodynamic boundary layer flows

    NASA Astrophysics Data System (ADS)

    Bijleveld, H. A.; Veldman, A. E. P.

    2014-12-01

    A quasi-simultaneous interaction method is applied to predict 2D and 3D aerodynamic flows. This method is suitable for offshore wind turbine design software as it is a very accurate and computationally reasonably cheap method. This study shows the results for a NACA 0012 airfoil. The two applied solvers converge to the experimental values when the grid is refined. We also show that in separation the eigenvalues remain positive thus avoiding the Goldstein singularity at separation. In 3D we show a flow over a dent in which separation occurs. A rotating flat plat is used to show the applicability of the method for rotating flows. The shown capabilities of the method indicate that the quasi-simultaneous interaction method is suitable for design methods for offshore wind turbine blades.

  6. A New HPLC-ELSD Method for Simultaneous Determination of N-Acetylglucosamine and N-Acetylgalactosamine in Dairy Foods

    PubMed Central

    Kim, Ho Jin; Bae, In Kyung; Jeong, Min Hee; Park, Hye Jin; Jung, Jin Sil; Kim, Jang Eok

    2015-01-01

    A rapid high performance liquid chromatographic method with evaporative light scattering detection (HPLC-ELSD), using a carbohydrate column, was developed for simultaneous determination of N-acetylglucosamine (GlcNAc) and N-acetylgalactosamine (GalNAc) in dairy foods. Sample preparation was performed by precipitation using acetonitrile. The limits of detection were 2.097 mg/L for GlcNAc and 3.247 mg/L for GalNAc. The limits of quantification were 6.043 mg/L for GlcNAc and 9.125 mg/L for GalNAc. Accuracy ranged from 96.4 to 105.7% for GlcNAc and from 97.1 to 104.1% for GalNAc. The precision of the method was <1.7% for GlcNAc and <2.2% for GalNAc. The mean recovery of the method was measured by spiking samples with 30.0–120.0 mg/L GlcNAc or 12.5–50.0 mg/L GalNAc and was found to be 95.1–105.5% for GlcNAc and 99.5–105.9% for GalNAc. The stability test results of standard solutions stored at 4, 20, and 40°C were 96.2–104.7% for GlcNAc and 98.0–106.5% for GalNAc. This study determined GlcNAc and GalNAc in dairy foods using HPLC-ELSD method. This rapid, simultaneous quantitation method might be useful as a mean of convenient quality control of dairy foods. PMID:26788060

  7. Introducing GAMER: A fast and accurate method for ray-tracing galaxies using procedural noise

    SciTech Connect

    Groeneboom, N. E.; Dahle, H.

    2014-03-10

    We developed a novel approach for fast and accurate ray-tracing of galaxies using procedural noise fields. Our method allows for efficient and realistic rendering of synthetic galaxy morphologies, where individual components such as the bulge, disk, stars, and dust can be synthesized in different wavelengths. These components follow empirically motivated overall intensity profiles but contain an additional procedural noise component that gives rise to complex natural patterns that mimic interstellar dust and star-forming regions. These patterns produce more realistic-looking galaxy images than using analytical expressions alone. The method is fully parallelized and creates accurate high- and low- resolution images that can be used, for example, in codes simulating strong and weak gravitational lensing. In addition to having a user-friendly graphical user interface, the C++ software package GAMER is easy to implement into an existing code.

  8. Accurate determination of relative metatarsal protrusion with a small intermetatarsal angle: a novel simplified method.

    PubMed

    Osher, Lawrence; Blazer, Marie Mantini; Buck, Stacie; Biernacki, Tomasz

    2014-01-01

    Several published studies have explained in detail how to measure relative metatarsal protrusion on the plain film anteroposterior pedal radiograph. These studies have demonstrated the utility of relative metatarsal protrusion measurement in that it correlates with distal forefoot deformity or pathologic features. The method currently preferred by practitioners in podiatric medicine and surgery often presents one with the daunting challenge of obtaining an accurate measurement when the intermetatarsal 1-2 angle is small. The present study illustrates a novel mathematical solution to this problem that is simple to master, relatively quick to perform, and yields accurate results. Our method was tested and proven by 4 trained observers with varying degrees of clinical skill who independently measured the same 10 radiographs. PMID:24933656

  9. Quantization of Dextromethorphan and Levocetirizine in Combined Dosage form Using a Novel Validated RP-HPLC Method

    PubMed Central

    Joshi, Shalini; Bhatia, C.; Bal, C. S.; Rawat, M. S. M.

    2012-01-01

    The present study reveals a simple isocratic RP-HPLC method for the simultaneous determination of dextromethorphan hydrobromide and levocetirizine dihydrochloride in a cough syrup. The separation of these compounds was achieved within 10 min on a Phenomenex (USA) C18 analytical column, 250×4.0 mm i.d., using an isocratic mobile phase consisting of potassium dihydrogen phosphate buffer (pH 2.5) - acetonitrile- tetrahydrofuran (70:25:5, v/v/v). The analysis was performed at a flow rate of 1.2 ml/min and at a detection wavelength of 232 nm. Percentage recovery and RSD were 100.36% and 0.05% for levocetirizine dihydrochloride, 100.35% and 0.27% for dextromethorphan hydrobromide respectively. Quantification of the components in syrup formulation was calculated against the peak areas of freshly prepared standard solutions. The method was validated as per ICH guidelines. PMID:23204629

  10. A simple HPLC-MS method for the quantitative determination of the composition of bacterial medium chain-length polyhydroxyalkanoates.

    PubMed

    Grubelnik, Andreas; Wiesli, Luzia; Furrer, Patrick; Rentsch, Daniel; Hany, Roland; Meyer, Veronika R

    2008-06-01

    Bacterial poly(hydroxyalkanoates) (PHAs) vary in the composition of their monomeric units. Besides saturated side-chains, unsaturated ones can also be found. The latter leads to unwanted by-products (THF ester, secondary alcohols) during acidic cleavage of the polymer backbone in the conventional analytical assays. To prevent these problems, we developed a new method for the reductive depolymerization of medium chain-length PHAs, leading to monomeric diols that can be separated and quantified by HPLC/MS. Reduction is performed at room temperature with lithium aluminum hydride within 5-15 min. The new method is faster and simpler than the previous ones and is quantitative. The results are consistent with the ones obtained by quantitative (1)H NMR. PMID:18461645

  11. Quantization of Dextromethorphan and Levocetirizine in Combined Dosage form Using a Novel Validated RP-HPLC Method.

    PubMed

    Joshi, Shalini; Bhatia, C; Bal, C S; Rawat, M S M

    2012-01-01

    The present study reveals a simple isocratic RP-HPLC method for the simultaneous determination of dextromethorphan hydrobromide and levocetirizine dihydrochloride in a cough syrup. The separation of these compounds was achieved within 10 min on a Phenomenex (USA) C(18) analytical column, 250×4.0 mm i.d., using an isocratic mobile phase consisting of potassium dihydrogen phosphate buffer (pH 2.5) - acetonitrile- tetrahydrofuran (70:25:5, v/v/v). The analysis was performed at a flow rate of 1.2 ml/min and at a detection wavelength of 232 nm. Percentage recovery and RSD were 100.36% and 0.05% for levocetirizine dihydrochloride, 100.35% and 0.27% for dextromethorphan hydrobromide respectively. Quantification of the components in syrup formulation was calculated against the peak areas of freshly prepared standard solutions. The method was validated as per ICH guidelines. PMID:23204629

  12. HPLC fluorescence method for the determination of nizatidine in human plasma and its application to pharmacokinetic study.

    PubMed

    Çakar, Mahmut B; Ulu, Sevgi T

    2014-06-01

    A sensitive high-performance liquid chromatographic (HPLC) method was developed for the determination of nizatidine in human plasma. Nizatidine was derivatized by 4-fluoro-7-nitrobenzofurazan (NBD-F). Chromatographic separation was performed on a Inertsil C18 column (150 mm × 4.6 mm, 5 µm) using isocratic elution by a mobile phase consisting of methanol/water (55:45) at a flow rate of 1.2 mL/min. Amlodipine was used as the internal standard (IS). Fluorescence detector was used operated at 461 nm (excitation) and 517 nm (emission), respectively. The calibration curve was linear over the range of 50-2000 ng/mL. This method was successfully applied to a pharmacokinetic study after oral administration of a dose (150 mg) of nizatidine. PMID:23836529

  13. Artemisinin evaluation in Romanian Artemisia annua wild plants using a new HPLC/MS method.

    PubMed

    Ivanescu, B; Vlase, L; Corciova, A; Lazar, M I

    2011-04-01

    Artemisinin, a sesquiterpene lactone from Artemisia annua L., has received considerable attention in the last few decades as a potent antimalarial drug. Artemisinin has rather low toxicity; it is effective against drug-resistant Plasmodium species and against cerebral malaria. This study reports the development of a rapid and sensitive assay for the quantification of artemisinin in A. annua by reversed phase HPLC/MS. In the selected optimal experimental conditions, artemisinin exhibited a well-defined chromatographic peak with a retention time of 2 ± 0.2 min. The chromatographic signal shows a linear dependence with artemisinin concentration, enabling the use of this signal for artemisinin quantification according to the following regression equation: y = 2665.40x - 14697.61. The correlation coefficient (R(2)) was 0.9989. For every concentration within the range of the standard curve (0.1-2 µg mL(-1)), accuracy was between 95 and 104%. Artemisinin content in Romanian A. annua wild plants varies between 0.17 and 0.21% (dry weight basis). PMID:21360406

  14. An accurate and practical method for inference of weak gravitational lensing from galaxy images

    NASA Astrophysics Data System (ADS)

    Bernstein, Gary M.; Armstrong, Robert; Krawiec, Christina; March, Marisa C.

    2016-07-01

    We demonstrate highly accurate recovery of weak gravitational lensing shear using an implementation of the Bayesian Fourier Domain (BFD) method proposed by Bernstein & Armstrong, extended to correct for selection biases. The BFD formalism is rigorously correct for Nyquist-sampled, background-limited, uncrowded images of background galaxies. BFD does not assign shapes to galaxies, instead compressing the pixel data D into a vector of moments M, such that we have an analytic expression for the probability P(M|g) of obtaining the observations with gravitational lensing distortion g along the line of sight. We implement an algorithm for conducting BFD's integrations over the population of unlensed source galaxies which measures ≈10 galaxies s-1 core-1 with good scaling properties. Initial tests of this code on ≈109 simulated lensed galaxy images recover the simulated shear to a fractional accuracy of m = (2.1 ± 0.4) × 10-3, substantially more accurate than has been demonstrated previously for any generally applicable method. Deep sky exposures generate a sufficiently accurate approximation to the noiseless, unlensed galaxy population distribution assumed as input to BFD. Potential extensions of the method include simultaneous measurement of magnification and shear; multiple-exposure, multiband observations; and joint inference of photometric redshifts and lensing tomography.

  15. An accurate and practical method for inference of weak gravitational lensing from galaxy images

    NASA Astrophysics Data System (ADS)

    Bernstein, Gary M.; Armstrong, Robert; Krawiec, Christina; March, Marisa C.

    2016-04-01

    We demonstrate highly accurate recovery of weak gravitational lensing shear using an implementation of the Bayesian Fourier Domain (BFD) method proposed by Bernstein & Armstrong (2014, BA14), extended to correct for selection biases. The BFD formalism is rigorously correct for Nyquist-sampled, background-limited, uncrowded image of background galaxies. BFD does not assign shapes to galaxies, instead compressing the pixel data D into a vector of moments M, such that we have an analytic expression for the probability P(M|g) of obtaining the observations with gravitational lensing distortion g along the line of sight. We implement an algorithm for conducting BFD's integrations over the population of unlensed source galaxies which measures ≈10 galaxies/second/core with good scaling properties. Initial tests of this code on ≈109 simulated lensed galaxy images recover the simulated shear to a fractional accuracy of m = (2.1 ± 0.4) × 10-3, substantially more accurate than has been demonstrated previously for any generally applicable method. Deep sky exposures generate a sufficiently accurate approximation to the noiseless, unlensed galaxy population distribution assumed as input to BFD. Potential extensions of the method include simultaneous measurement of magnification and shear; multiple-exposure, multi-band observations; and joint inference of photometric redshifts and lensing tomography.

  16. Validation of HPLC-UV method for determination of minor glycosides contained in Stevia rebaudiana Bertoni leaves.

    PubMed

    Aranda-González, Irma; Moguel-Ordoñez, Yolanda; Betancur-Ancona, David

    2015-05-01

    Leaves of Stevia rebaudiana contain glycosides with sweetness and biological activity. However besides the major glycosides, there are other glycosides within extracts that may contribute to its activity, and therefore it is important to quantify them. In this work, an isocratic HPLC method was validated for determination of dulcoside A, steviolbioside, rebaudioside C and rebaudioside B. An HPLC method was performed using a C18 column (250 × 4.6 mm, particle size 5 µm) and a UV detector set at 210 nm. The mobile phase consisted of a 32:68 (v/v) mixture of acetonitrile and sodium phosphate buffer (10 mmol/L, pH 2.6), set to a flow rate of 1.0 mL/min. The calculated parameters were: sensitivity, linearity, limit of detection (LOD), limit of quantification (LOQ), accuracy and precision. The calibration curves were linear over the working range 25-150 µg/mL, with coefficient of correlation of ≥0.99 and coefficient of determination of ≥0.98. The LOD was 5.68-8.81 µg/mL, while the LOQ was 17.21-26.69 µg/mL. The percentage recoveries of fortified samples were 100 ± 10% and precision, relative standard deviation, was <10%. The method validation showed accuracy, linearity and precision; therefore this method can be applied for quantitative analysis of minor steviol glycosides in S. rebaudiana leaves. PMID:25296637

  17. A Validated Stability-Indicating and Stereoselective HPLC Method for the Determination of Lenalidomide Enantiomers in Bulk Form and Capsules.

    PubMed

    Alzoman, Nourah Z

    2016-01-01

    A simple, rapid and stability-indicating chiral HPLC (CHR-HPLC) method was designed for the enantiomeric separation of lenalidomide (LDM) in the presence of its degradation products. LDM was exposed to different accelerated stress factors. The degradation products were well resolved from the pure drug enantiomers. Separation of the LDM enantiomers was achieved on a LUX 5U cellulose-2 chiral column (250 × 4.6 mm i.d.) with a mobile phase consisting of methanol : glacial acetic acid : triethyl amine (100 : 0.01 : 0.01, v/v/v) at a flow rate of 1.2 mL/min. The detection wavelength was 220 nm, and ornidazole was the internal standard. The chiral method was validated in terms of its specificity, linearity, range, precision and accuracy as well as solution stability, robustness, limit of detection and limit of quantification. The calibration curve was linear for concentrations ranging from 2 to 1,000 ng/mL (r= 0.9999) for both LDM enantiomers. The proposed method, which met International Conference on Harmonization/Food and Drug Administration regulatory requirements, was utilized successfully for the determination of LDM in bulk and in capsules with acceptable accuracy and precision; the label demand percentages were 100.09 ± 0.80 and 99.97 ± 0.93 for the S-(-) and R-(+)-LDM enantiomers, respectively. Based on these results, this method should have great value when applied to quality control and stability studies of LDM. PMID:26850732

  18. Development and validation of a single HPLC method for determination of α-tocopherol in cell culture and in human or mouse biological samples.

    PubMed

    Cimadevilla, Henar M; Hevia, David; Miar, Ana; Mayo, Juan C; Lombo, Felipe; Sainz, Rosa M

    2015-06-01

    A straightforward and common analytical method for α-tocopherol (αT) determination in various biological samples, including plasma, red blood cells (RBC), tissues and cultured cell lines, was developed and validated, using a reverse phase-chromatographic method (RP-HPLC). Even though many chromatographic methods for αT determination have been reported, most of them require readjustment when applied to different types of samples. Thus, an effective and simple method for αT determination in different biological matrices is still necessary, specifically for translational research. This method was applied using a C18 column (250 × 4.6 mm, 5 µm particle size) under isocratic elution with MeOH:ACN:H2 O (90:9:1 v/v/v) at a flow rate of 1 mL/min and detected using photodiode array at 293 nm. Linearity (r >0.9997) was observed for standard calibration with inter- and intraday variation of standard <4%. Lower limits of detection and quantification for αT in this assay were 0.091 and 0.305 µg/mL respectively. Validation proved the method to be selective, linear, accurate and precise. The method was successfully applied in great variety of biological samples, that is, human and mouse plasma, RBCs, murine tissues and human/mouse/rat cultured cell lines. More importantly, a single protocol of extraction and detection can be applied, making this method very convenient for standardization of different types of samples. PMID:25346068

  19. Accurate, efficient, and (iso)geometrically flexible collocation methods for phase-field models

    NASA Astrophysics Data System (ADS)

    Gomez, Hector; Reali, Alessandro; Sangalli, Giancarlo

    2014-04-01

    We propose new collocation methods for phase-field models. Our algorithms are based on isogeometric analysis, a new technology that makes use of functions from computational geometry, such as, for example, Non-Uniform Rational B-Splines (NURBS). NURBS exhibit excellent approximability and controllable global smoothness, and can represent exactly most geometries encapsulated in Computer Aided Design (CAD) models. These attributes permitted us to derive accurate, efficient, and geometrically flexible collocation methods for phase-field models. The performance of our method is demonstrated by several numerical examples of phase separation modeled by the Cahn-Hilliard equation. We feel that our method successfully combines the geometrical flexibility of finite elements with the accuracy and simplicity of pseudo-spectral collocation methods, and is a viable alternative to classical collocation methods.

  20. Single-laboratory validation of a refined AOAC HPLC method 2005.06 for oysters, cockles, and clams in U.K. shellfish.

    PubMed

    Turner, Andrew D; Hatfield, Robert G; Rapkova-Dhanji, Monika; Norton, Deirdre M; Algoet, Myriam; Lees, David N

    2010-01-01

    In 2009, a refined HPLC method based on AOAC Official Method 2005.06 was developed and validated for the determination of paralytic shellfish poisoning (PSP) in mussels. A single-laboratory validation study of this method was undertaken here for the analysis of PSP toxins in oysters, cockles, clams, and razor clams. The method was characterized for selectivity, sensitivity, linearity, precision, repeatability, recovery, ruggedness, and uncertainty of measurement. Validation data were utilized to determine method performance characteristics for non-mussel bivalves for all commercially available certified reference toxins, extending the method to dcNEO and dcGTX2,3, where available. A period of parallel testing of oysters, cockles, and clams enabled a comparison of sample toxicities obtained using mouse bioassay (MBA) and HPLC methodologies, although only a very low number of PSP-positive samples were obtained through the United Kingdom official control monitoring program. Results from the MBA and HPLC methods were well-correlated for PSP-negative samples, but the low number of naturally contaminated PSP-positive samples has prevented any comparative statistical assessment of method performance for non-mussels between the two official methods. However, some evidence for potentially significant differences in total saxitoxin equivalents obtained by the two methods in some species has highlighted the need for further comparative testing in non-mussel samples to be conducted prior to implementation of the HPLC method in routine official control monitoring programs. PMID:21140661

  1. Comparison of methods for accurate end-point detection of potentiometric titrations

    NASA Astrophysics Data System (ADS)

    Villela, R. L. A.; Borges, P. P.; Vyskočil, L.

    2015-01-01

    Detection of the end point in potentiometric titrations has wide application on experiments that demand very low measurement uncertainties mainly for certifying reference materials. Simulations of experimental coulometric titration data and consequential error analysis of the end-point values were conducted using a programming code. These simulations revealed that the Levenberg-Marquardt method is in general more accurate than the traditional second derivative technique used currently as end-point detection for potentiometric titrations. Performance of the methods will be compared and presented in this paper.

  2. The detection of radical scavenging compounds in crude extract of borage (Borago officinalis L.) by using an on-line HPLC-DPPH method.

    PubMed

    Bandoniene, Donata; Murkovic, Michael

    2002-01-01

    The rapid evaluation of antioxidant activity of crude borage (Borago officinalis L.) extract was determined by using DPPH free radical method. This borage extract resulted in a rapid decrease of the absorbance and showed very high hydrogen-donating capacity towards the 2,2'-diphenyl-1-picrylhydrazyl (DPPH) radical. A new HPLC-DPPH on-line method was applied for a screening of several radical scavenging components in this borage extract as well as for quantitative analysis. This on-line HPLC-DPPH method was developed using a methanolic solution of DPPH-stable radical. The HPLC-separated analytes reacted post-column with the DPPH solution in methanol. The induced bleaching was detected as a negative peak photometrically at 515 nm. The separation of antioxidative components was carried out by gradient HPLC with mobile-phase composition ranging from 2% to 80% acetonitrile with 2% acetic acid in water, UV detection was carried out at 280 nm. The HPLC analysis of borage extract revealed the presence of several radical scavenging components in the borage extract. The results obtained from the chromatograms suggest that some compounds present in the extract possess high radical quenching ability. The dominant antioxidative compound in the crude extract of borage leaves was identified as rosmarinic acid. PMID:12406585

  3. A HPLC-fluorescence detection method for determination of phosphatidic acid phosphohydrolase activity: application in human myocardium.

    PubMed

    Burgdorf, Christof; Prey, Antje; Richardt, Gert; Kurz, Thomas

    2008-03-15

    Phosphatidic acid phosphohydrolase (PAP) catalyzes the dephosphorylation of phosphatidic acid (PA) to diacylglycerol, the second messenger responsible for activation of protein kinase C. Despite the crucial role of PAP lipid signaling, there are no data on PAP signaling function in the human heart. Here we present a nonradioactive assay for the investigation of PAP activity in human myocardium using a fluorescent derivative of PA, 2-(4,4-difluoro-5,7-dimethyl-4-bora-3a,4a-diaza-s-indacene-3-pentanoyl)-1-hexadecanoyl-sn-glycero-3-phosphate (BODIPY-PA), as substrate in an in vitro PAP-catalyzed reaction. Unreacted BODIPY-PA was resolved from the PAP products by a binary gradient HPLC system and BODIPY-diacylglycerol was detected by fluorimetry. The reaction proceeded at a linear rate for up to 60 min and increased linearly with increasing amounts of cardiac protein in a range of 0.25 to 8.0 microg. This assay proved to be sensitive for accurate quantitation of total PAP activity, PAP-1 activity, and PAP-2 activity in human atrial tissue and right ventricular endomyocardial biopsies. Total PAP activity was approximately fourfold higher in ventricular myocardium than in atrial tissue. There was negligible PAP-1 activity in atrial myocardium compared with ventricular myocardium, indicating regional differences in activities and distribution pattern of PAP-1 and PAP-2 in the human heart. PMID:18023403

  4. Rapid, potentially automatable, method extract biomarkers for HPLC/ESI/MS/MS to detect and identify BW agents

    SciTech Connect

    White, D.C. |; Burkhalter, R.S.; Smith, C.; Whitaker, K.W.

    1997-12-31

    The program proposes to concentrate on the rapid recovery of signature biomarkers based on automated high-pressure, high-temperature solvent extraction (ASE) and/or supercritical fluid extraction (SFE) to produce lipids, nucleic acids and proteins sequentially concentrated and purified in minutes with yields especially from microeukaryotes, Gram-positive bacteria and spores. Lipids are extracted in higher proportions greater than classical one-phase, room temperature solvent extraction without major changes in lipid composition. High performance liquid chromatography (HPLC) with or without derivatization, electrospray ionization (ESI) and highly specific detection by mass spectrometry (MS) particularly with (MS){sup n} provides the detection, identification and because the signature lipid biomarkers are both phenotypic as well as genotypic biomarkers, insights into potential infectivity of BW agents. Feasibility has been demonstrated with detection, identification, and determination of infectious potential of Cryptosporidium parvum at the sensitivity of a single oocyst (which is unculturable in vitro) and accurate identification and prediction, pathogenicity, and drug-resistance of Mycobacteria spp.

  5. A method to accurately estimate the muscular torques of human wearing exoskeletons by torque sensors.

    PubMed

    Hwang, Beomsoo; Jeon, Doyoung

    2015-01-01

    In exoskeletal robots, the quantification of the user's muscular effort is important to recognize the user's motion intentions and evaluate motor abilities. In this paper, we attempt to estimate users' muscular efforts accurately using joint torque sensor which contains the measurements of dynamic effect of human body such as the inertial, Coriolis, and gravitational torques as well as torque by active muscular effort. It is important to extract the dynamic effects of the user's limb accurately from the measured torque. The user's limb dynamics are formulated and a convenient method of identifying user-specific parameters is suggested for estimating the user's muscular torque in robotic exoskeletons. Experiments were carried out on a wheelchair-integrated lower limb exoskeleton, EXOwheel, which was equipped with torque sensors in the hip and knee joints. The proposed methods were evaluated by 10 healthy participants during body weight-supported gait training. The experimental results show that the torque sensors are to estimate the muscular torque accurately in cases of relaxed and activated muscle conditions. PMID:25860074

  6. A second order accurate embedded boundary method for the wave equation with Dirichlet data

    SciTech Connect

    Kreiss, H O; Petersson, N A

    2004-03-02

    The accuracy of Cartesian embedded boundary methods for the second order wave equation in general two-dimensional domains subject to Dirichlet boundary conditions is analyzed. Based on the analysis, we develop a numerical method where both the solution and its gradient are second order accurate. We avoid the small-cell stiffness problem without sacrificing the second order accuracy by adding a small artificial term to the Dirichlet boundary condition. Long-time stability of the method is obtained by adding a small fourth order dissipative term. Several numerical examples are provided to demonstrate the accuracy and stability of the method. The method is also used to solve the two-dimensional TM{sub z} problem for Maxwell's equations posed as a second order wave equation for the electric field coupled to ordinary differential equations for the magnetic field.

  7. HPLC Methods for Quantitation of Exemestane-Luteolin and Exemestane-Resveratrol Mixtures in Nanoformulations.

    PubMed

    El-Lakany, Sarah A; Elzoghby, Ahmed O; Elgindy, Nazik A; Hamdy, Dalia A

    2016-09-01

    Two HPLC-DAD assays for the simultaneous quantitation of exemestane (EXE) and resveratrol (RES)-Mix 1-and EXE and luteolin (LUT)-Mix 2-in novel breast cancer therapy nanoformulations were developed. Calibration curves 15-30 µg/mL and samples were injected through an Inertsil ODS-3 (250 × 4.6 mm, 5 µm) column. The gradient elution for Mix 1 was methanol : 0.05% (v/v) acetic acid in water (60 : 40 to 80 : 20, linear over 2 min), and for Mix 2, it was methanol : water (60 : 40 for 4 min, then ramped linearly to 90 : 10, over 12 min) pumped at 1.5 mL/min for 4 min, then 1 mL/min till the end of run. EXE, RES, LUT and flutamide (internal standard (IS)) were measured at 246, 307, 350 and 300 nm, respectively. For Mix 1, RES, EXE and IS eluted at 3.5, 6.8 and 7.4 min, respectively, while for Mix 2, LUT, EXE and IS eluted at 7.5, 11.4 and 12.7 min, respectively. The mean r(2) for the standard curves was ≥0.99, and percentage coefficient of variation and % error of the mean were <2. Both assays successfully quantitated Mix 1 and Mix 2 in their nanoformulations. The two developed assays were sensitive and selective for the analysis of EXE-LUT and EXE-RES mixtures in nanoformulations according to International Conference on Harmonization guidelines. PMID:27130876

  8. QbD-Driven Development and Validation of a HPLC Method for Estimation of Tamoxifen Citrate with Improved Performance.

    PubMed

    Sandhu, Premjeet Singh; Beg, Sarwar; Katare, O P; Singh, Bhupinder

    2016-09-01

    The current studies entail Quality by Design (QbD)-enabled development of a simple, rapid, sensitive and cost-effective high-performance liquid chromatographic method for estimation of tamoxifen citrate (TMx). The factor screening studies were performed using a 7-factor 8-run Taguchi design. Systematic optimization was performed employing Box-Behnken design by selecting the mobile phase ratio, buffer pH and oven temperature as the critical method parameters (CMPs) identified from screening studies, thus evaluating the critical analytical attributes (CAAs), namely, peak area, retention time, theoretical plates and peak tailing as the parameters of method robustness. The optimal chromatographic separation was achieved using acetonitrile and phosphate buffer (pH 3.5) 52:48 v/v as the mobile phase with a flow rate 0.7 mL/min, an oven temperature 40°C and UV detection at 256 nm. The method was validated as per the ICH recommended conditions, which revealed high degree of linearity, accuracy, precision, sensitivity and robustness over the existing liquid chromatographic methods of the drug. Also the method was applied for the estimation of TMx in nanostructured formulations, which indicated no significant change in the retention time. In a nutshell, the studies demonstrated successful development of the HPLC method of TMx with improved understanding of the relationship among the influential variables for enhancing the method performance. PMID:27226463

  9. Toward Radiocarbon Measurement of Individual Amino Acids in Marine Dissolved Organic Matter (DOM): Δ14C Blank Quantification for an HPLC Purification Method.

    NASA Astrophysics Data System (ADS)

    Bour, A. L.; Broek, T.; Walker, B. D.; Mccarthy, M. D.

    2014-12-01

    The presence of much of the marine dissolved organic nitrogen (DON) pool as uncharacterized, biologically recalcitrant molecules is a central mystery in the marine nitrogen cycle. Radiocarbon (Δ14C) isotopic measurements have been perhaps the most important data constraining the cycling of dissolved organic matter (DOM), but little Δ14C data specific to DON is available. Amino acids (AAs) are the major component of DON that can be isolated on a molecular level. Δ14C measurements for the operational "protein-like" fraction of DOM in the deep ocean indicate that this compound class has radiocarbon ages greater than several ocean mixing cycles, suggesting remarkable preservation of labile AAs exported from the surface. However, it is possible that the previously defined operational "protein-like" fraction may also contain non-AA material. Radiocarbon measurement of purified individual AAs would provide a more direct and reliable proxy for DON Δ14C age and cycling rate. We present here Δ14C blank characterization of an AA purification method based on HPLC, with on-line fraction collection. This method allows the recovery of unmodified AAs, but accurate measurement of small AA samples that can be extracted from DOM requires a system with extremely low Δ 14C blanks. Here we assess the impact of HPLC purification on the Δ14C age of known amino acids standards. Individual AA standards with contrasting (modern vs. dead) and well- characterized Δ14C ages were processed in a range of sample sizes. The eluted peaks were collected and dried, and measurement of their post-chromatography Δ14C content allowed for determination of the Δ14C blank by method of additions. The same protocol was applied to a mixture of six AA standards, to evaluate tailing effects in consecutive AA peaks of contrasting Δ14C age. AA standards were selected to include both Δ14C modern and dead AAs that elute both early and late in the chromatographic solvent program. We discuss implications

  10. Accurate near-field calculation in the rigorous coupled-wave analysis method

    NASA Astrophysics Data System (ADS)

    Weismann, Martin; Gallagher, Dominic F. G.; Panoiu, Nicolae C.

    2015-12-01

    The rigorous coupled-wave analysis (RCWA) is one of the most successful and widely used methods for modeling periodic optical structures. It yields fast convergence of the electromagnetic far-field and has been adapted to model various optical devices and wave configurations. In this article, we investigate the accuracy with which the electromagnetic near-field can be calculated by using RCWA and explain the observed slow convergence and numerical artifacts from which it suffers, namely unphysical oscillations at material boundaries due to the Gibbs phenomenon. In order to alleviate these shortcomings, we also introduce a mathematical formulation for accurate near-field calculation in RCWA, for one- and two-dimensional straight and slanted diffraction gratings. This accurate near-field computational approach is tested and evaluated for several representative test-structures and configurations in order to illustrate the advantages provided by the proposed modified formulation of the RCWA.

  11. A Novel Method for Accurate Operon Predictions in All SequencedProkaryotes

    SciTech Connect

    Price, Morgan N.; Huang, Katherine H.; Alm, Eric J.; Arkin, Adam P.

    2004-12-01

    We combine comparative genomic measures and the distance separating adjacent genes to predict operons in 124 completely sequenced prokaryotic genomes. Our method automatically tailors itself to each genome using sequence information alone, and thus can be applied to any prokaryote. For Escherichia coli K12 and Bacillus subtilis, our method is 85 and 83% accurate, respectively, which is similar to the accuracy of methods that use the same features but are trained on experimentally characterized transcripts. In Halobacterium NRC-1 and in Helicobacterpylori, our method correctly infers that genes in operons are separated by shorter distances than they are in E.coli, and its predictions using distance alone are more accurate than distance-only predictions trained on a database of E.coli transcripts. We use microarray data from sixphylogenetically diverse prokaryotes to show that combining intergenic distance with comparative genomic measures further improves accuracy and that our method is broadly effective. Finally, we survey operon structure across 124 genomes, and find several surprises: H.pylori has many operons, contrary to previous reports; Bacillus anthracis has an unusual number of pseudogenes within conserved operons; and Synechocystis PCC6803 has many operons even though it has unusually wide spacings between conserved adjacent genes.

  12. Accurate Time/Frequency Transfer Method Using Bi-Directional WDM Transmission

    NASA Technical Reports Server (NTRS)

    Imaoka, Atsushi; Kihara, Masami

    1996-01-01

    An accurate time transfer method is proposed using b-directional wavelength division multiplexing (WDM) signal transmission along a single optical fiber. This method will be used in digital telecommunication networks and yield a time synchronization accuracy of better than 1 ns for long transmission lines over several tens of kilometers. The method can accurately measure the difference in delay between two wavelength signals caused by the chromatic dispersion of the fiber in conventional simple bi-directional dual-wavelength frequency transfer methods. We describe the characteristics of this difference in delay and then show that the accuracy of the delay measurements can be obtained below 0.1 ns by transmitting 156 Mb/s times reference signals of 1.31 micrometer and 1.55 micrometers along a 50 km fiber using the proposed method. The sub-nanosecond delay measurement using the simple bi-directional dual-wavelength transmission along a 100 km fiber with a wavelength spacing of 1 nm in the 1.55 micrometer range is also shown.

  13. Quantification of 4'-geranyloxyferulic acid (GOFA) in honey samples of different origin by validated RP-HPLC-UV method.

    PubMed

    Genovese, Salvatore; Taddeo, Vito Alessandro; Fiorito, Serena; Epifano, Francesco

    2016-01-01

    Natural honey has been employed as a nutraceutical agent with benefits and therapeutic promises for humans for many centuries. It has been largely used as food and medicine by all generations, traditions, and civilizations, both ancient and modern. Several chemicals having beneficial effects for human health have been reported as components of natural honey and these include sugars, organic acids, aminoacids, minerals, and vitamins. Also some important phytochemicals have been described and these comprise tannins, flavonoids, terpenes, saponins, and alkaloids. In this note it is described the successful application of a RP HPLC-UV-vis method for the separation and quantification of 4'-geranyloxyferulic acid (GOFA) in four honey samples of different origin. Concentration values showed a great variation between the four samples tested, being chestnut honey the one richest in GOFA (7.87 mg/g). The findings described herein represent the first example reported in the literature of the characterization of an oxyprenylated phenylpropanoid in honey. PMID:26421962

  14. Development of an HPLC Method for the Determination of Ceftolozane/Tazobactam in Biological and Aqueous Matrixes.

    PubMed

    Sutherland, Christina A; Nicolau, David P

    2016-07-01

    Herein, we report the development and validation of an HPLC method to analyze ceftolozane and tazobactam simultaneously in human plasma, human serum, swine serum and saline matrixes. A reversed-phase column was used with a UV detector set at 260 nm and switched to 218 nm. The mobile phase consisted of methanol and sodium phosphate buffer at a flow rate of 1.1 mL/min. Cefepime was used as the internal standard. The standard curves were linear over a range of 0.4-50 μg/mL. This methodology represents a simple, reproducible approach to the determination of drug concentrations with sufficient accuracy and precision for pharmacokinetic studies undertaken with this recently FDA-approved antimicrobial therapy. PMID:27048639

  15. HPLC-HRMS method for fast phytochelatins determination in plants. Application to analysis of Clinopodium vulgare L.

    PubMed

    Bardarov, Krum; Naydenov, Mladen; Djingova, Rumyana

    2015-09-01

    An optimized analytical method based on C8 core-shell reverse phase chromatographic separation and high resolution mass spectral (HRMS) detection is developed for a fast analysis of unbound phytochelatins (PCs) in plants. Its application to analysis of Clinopodium vulgare L. is demonstrated where proper PCs liberating and preservation conditions were employed using dithiotreitol in the extraction step. A baseline separation of glutathione (GSH) and phytochelatins from 2 to 5 (PC2-PC5) for 3 min was achieved at conventional HPLC backpressure, with detection limits from 3 ppt (for GSH) to 2.5 ppb (for PC5). It is shown, that the use of HRMS with tandem mass spectral (MS/MS) capabilities permits additional wide range screening ability for iso-phytochelatins and PC similar compounds, based on exact mass and fragment spectra in a post acquisition manner. PMID:26003687

  16. Development and Validation of a Simultaneous HPLC Method for Estimation of Bisoprolol Fumarate and Amlodipine Besylate from Tablets

    PubMed Central

    Vora, D. N.; Kadav, A. A.

    2008-01-01

    A fast, robust and stability indicating RP-HPLC method was developed for simultaneous determination of bisoprolol fumarate and amlodipine besylate in tablets. The mobile phase was mixture of 25 mM ammonium acetate adjusted to pH 5.0 and methanol (65: 35) at 0.8 ml/min. The stationary phase was Luna C18-2 column (3 μ, 50×4.6 mm ID). UV detection was performed at 230 nm. Retention time was 1.45 min and 3.91 min for bisoprolol and amlodipine, respectively. Linearity was established in the range of 8–33 μg/ml. Mean recovery was 99.1% and 98.6% for bisoprolol fumarate and amlodipine besylate, respectively. PMID:20046793

  17. Development and validation of HPLC method for the determination of alpha-tocopherol in human erythrocytes for clinical applications.

    PubMed

    Solichová, Dagmar; Korecká, Lucie; Svobodová, Iveta; Musil, Frantisek; Bláha, Vladimír; Zdánský, Petr; Zadák, Zdenek

    2003-06-01

    In this work, a simple isocratic reversed-phase HPLC method for determination of alpha-tocopherol in human erythrocytes has been developed and validated. After separation of plasma the erythrocytes were washed three times with 0.9% sodium chloride containing 0.01% butylated hydroxytoluene (BHT) as antioxidant and then were diluted 1:1 (v/v) with the same solution. In the liquid-liquid extraction (LLE) procedure, 2500 microL of n-hexane was added to 500 microL of erythrocytes. After 2 min this mixture was deproteinized by addition of cool ethanol (500 microL, 5 min) denatured with 5% methanol containing alpha-tocopherol acetate (20 micromol L(-1)), as internal standard, and then extracted for 5 min by vortex mixing. After centrifugation (10 min, 1600xg) an aliquot (2000 microL) of the clean extract was separated and evaporated under nitrogen. The residue was dissolved in 400 microL methanol and analysed by reversed-phase HPLC on a 4.6 mmx150 mm, 5 microm Pecosphere C18 column; the mobile phase was 100% methanol, flow rate 1.2 mL min(-1). The volume injected was 100 microL and detection was by diode-array detector at a wavelength of 295 nm. The extraction recovery of alpha-tocopherol from human erythrocytes was 100.0+/-2.0%. The detection limit was 0.1 micromol L(-1) and a linear calibration plot was obtained in the concentration range 0.5-20.0 micromol L(-1). Within determination precision was 5.2% RSD (n=10), between determination precision was 6.1% RSD (n=10). The method was applied successfully in a clinical study of patients with acute pancreatitis and for determination of the reference values in the healthy Czech population. PMID:12719955

  18. A versatile method for analysis of saliva, plasma and urine for total thiols using HPLC with UV detection.

    PubMed

    Stachniuk, Justyna; Kubalczyk, Paweł; Furmaniak, Paulina; Głowacki, Rafał

    2016-08-01

    A simple and rapid HPLC method using 2-chloro-1-methyllepidinium tetrafluoroborate (CMLT) as a derivatization reagent was developed for simultaneous determination of homocysteine (Hcy), glutathione (GSH), γ-glutamylcysteine (γ-GluCys), cysteinylglycine (CysGly), N-acetylcysteine (NACys) and cysteine (Cys) in human saliva, plasma and urine. Separation of the analytes was achieved in just 7min using an HPLC, followed by UV detection at 355nm. Chromatographic separation was accomplished on Aeris PEPTIDE XB-C18 (150mm×4.6mm, 3.6µm) column from Phenomenex with a gradient elution: 0-4.0min, 7-30% B; 4.0-5.5min, 30-7% B; 5.5-7.5min, 7% B; (A: B, v/v); (A) 0.5% CH3COOH and (B) EtOH. Mobile phase was delivered at a flow rate 1.0mLmin(-1). Linearity in detector response for total thiols was observed over the range of 0.1-20μmolL(-1) for Hcy, GSH and γ-GluCys, 0.25-50μmolL(-1) for NACys and CysGly and 5-300 for Cys. The LOQ values for Hcy, GSH, γ-GluCys, NACys, CysGly and Cys were 0.05, 0.05, 0.10, 0.06, 0.12 and 0.08μmolL(-1), respectively. The method was successfully implemented to analysis of the samples donated by 15 apparently healthy volunteers and 10 patients. PMID:27216658

  19. [Method of quantitative analysis by HPLC and confirmation by LC-MS of sugar alcohols in foods].

    PubMed

    Shindo, Tetsuya; Sadamasu, Yuki; Suzuki, Keiko; Tanaka, Yasukazu; Togawa, Akiko; Uematsu, Yoko

    2013-01-01

    A reliable quantitative determination method of sugar alcohols, D-mannitol, xylitol and D-sorbitol, in food samples by HPLC, and a simple confirmation method by LC-MS were developed. Quantitative HPLC analysis was performed using a separation column packed with polystyrene cation exchange resin of sulfonic acid type, and with pure distilled water as the mobile phase. This column, operated at 0.85 mL/min flow rate of mobile phase and 50℃ column oven temperature, completely separated the three sugar alcohols. Further, these three sugar alcohols were well separated from erythritol and other sugars (sucrose, D-glucose, D-xylose and D-fructose). Recoveries of the three sugar alcohols spiked into food samples, such as orange juice, yogurt, chewing gum and milk, exceeded 91% and the values of coefficient of variance were below 3.1%. A triple extraction process with 80% ethanol was needed for biscuit to achieve recoveries exceeding 82%. LC-MS was carried out on a NH2 column with acetonitrile-water (9 : 1) as the mobile phase, and this afforded partial but acceptable separation of the three sugar alcohols with in 10 minutes. Ion peaks derived from [M-H](-) and [M+Cl](-) were clearly detected for all three sugar alcohols in the negative electrospray inization mode at 30 V cone voltage. The positive electrospray ionization mode produced the ions [M+Na](+) and [M+Na+CH3CN](+). These characteristic ions served to confirm the presence of the sugar alcohols in food samples. PMID:24190289

  20. A HPLC method for the quantitative determination of N-(2-hydroxy-5-nitrophenylcarbamothioyl)-3,5-dimethylbenzamide in biological samples.

    PubMed

    Skidan, Igor; Grunwald, Jacob; Thekkedath, Ritesh; Degterev, Alexei; Torchilin, Vladimir

    2011-06-01

    A sensitive and simple HPLC method was developed for the determination of a novel compound, a potential anti-cancer drug, N-(2-hydroxy-5-nitrophenylcarbamothioyl)-3,5-dimethylbenzamide (DM-PIT-1), a member of the new structural class of non-phosphoinositide small molecule antagonist of phosphatidylinositol-3,4,5-trisphosphate-pleckstrin-homology domain interactions, in mouse plasma and tumor tissue homogenates. The chromatographic separation of DM-PIT-1 was achieved on C18 column using isocratic elution with acetonitrile-water (70:30) containing 0.1% formic acid (v/v). DM-PIT-1 was detected by UV absorbance at 320 nm and confirmed by LC-MS. The extraction of the DM-PIT-1 from the plasma and tumor tissue with methylene chloride resulted in its high recovery (70-80%). HPLC calibration curves for DM-PIT-1 based on the extracts from the mouse plasma and tumor tissue samples were linear over a broad concentration range of 0.25-20 μg/ml/g, with intra/inter-day accuracy of 95% and the precision of variation below 10%. The limits of detection and quantification were 0.1 ng and 0.2 ng, respectively. The described method was successfully applied to study the pharmacokinetics of the DM-PIT-1 following the parenteral injections of DM-PIT-1 entrapped in 1,2-disteratoyl-sn-glycero-3-phosphoethanolamine-N-[methoxy(polyethylene-glycol)-2000] (PEG-PE) micelles. PMID:21514904

  1. Validated RP-HPLC and HPTLC methods for determination of anti-inflammatory bis-indole alkaloid in Desmodium gangeticum.

    PubMed

    Yadav, Akhilesh K; Gupta, Madan M

    2014-01-01

    Here, two simple and accurate methods, namely high-performance liquid chromatography and high-performance thin-layer chromatography for the detection of gangenoid, an anti-inflammatory alkaloid, in a well-known Indian medicinal plant Desmodium gangeticum, are described. The proposed methods were successfully used for the estimation of gangenoid in D. gangeticum root. PMID:24079376

  2. Accurate Wind Characterization in Complex Terrain Using the Immersed Boundary Method

    SciTech Connect

    Lundquist, K A; Chow, F K; Lundquist, J K; Kosovic, B

    2009-09-30

    This paper describes an immersed boundary method (IBM) that facilitates the explicit resolution of complex terrain within the Weather Research and Forecasting (WRF) model. Two different interpolation methods, trilinear and inverse distance weighting, are used at the core of the IBM algorithm. Functional aspects of the algorithm's implementation and the accuracy of results are considered. Simulations of flow over a three-dimensional hill with shallow terrain slopes are preformed with both WRF's native terrain-following coordinate and with both IB methods. Comparisons of flow fields from the three simulations show excellent agreement, indicating that both IB methods produce accurate results. However, when ease of implementation is considered, inverse distance weighting is superior. Furthermore, inverse distance weighting is shown to be more adept at handling highly complex urban terrain, where the trilinear interpolation algorithm breaks down. This capability is demonstrated by using the inverse distance weighting core of the IBM to model atmospheric flow in downtown Oklahoma City.

  3. Accurate force fields and methods for modelling organic molecular crystals at finite temperatures.

    PubMed

    Nyman, Jonas; Pundyke, Orla Sheehan; Day, Graeme M

    2016-06-21

    We present an assessment of the performance of several force fields for modelling intermolecular interactions in organic molecular crystals using the X23 benchmark set. The performance of the force fields is compared to several popular dispersion corrected density functional methods. In addition, we present our implementation of lattice vibrational free energy calculations in the quasi-harmonic approximation, using several methods to account for phonon dispersion. This allows us to also benchmark the force fields' reproduction of finite temperature crystal structures. The results demonstrate that anisotropic atom-atom multipole-based force fields can be as accurate as several popular DFT-D methods, but have errors 2-3 times larger than the current best DFT-D methods. The largest error in the examined force fields is a systematic underestimation of the (absolute) lattice energy. PMID:27230942

  4. Size-exclusion HPLC provides a simple, rapid, and versatile alternative method for quality control of vaccines by characterizing the assembly of antigens.

    PubMed

    Yang, Yanli; Li, Hao; Li, Zhengjun; Zhang, Yan; Zhang, Songping; Chen, Yi; Yu, Mengran; Ma, Guanghui; Su, Zhiguo

    2015-02-25

    The assembly of antigen structure is often crucial to the potency of vaccines. Currently adopted methods like animal testing and ultracentrifugation take long time and are difficult to automate for multiple samples. Here we develop a size-exclusion high-performance liquid chromatography (SE-HPLC) method to characterize the assembly of antigen structure during both manufacturing process and storage. Three important vaccine antigens including inactivated foot and mouth disease virus (FMDV), which is a virus vaccine; and two virus-like particles (VLPs) vaccines involving hepatitis B core antigen (HBcAg) VLPs, and hepatitis B surface antigen (HBsAg) VLPs, were successfully analyzed using commercially available TSK gel columns with pore size above 45nm. Combined with other analytical methods including SDS-PAGE, dynamic light scattering, wavelength scan, and multi-angle laser light scattering, the SE-HPLC method was proven to be a simple, rapid, and reliable tool for antigen particles assembly analysis. Specifically, for FMDV whole virus particle, SE-HPLC was used to analyze 146S content in vaccine preparations and the thermal dissociation of the 146S. For HBcAg-VLPs that are expressed in recombinant Escherichia coli, its expression level during cell culture process was quantitatively monitored by SE-HPLC. The SE-HPLC also showed applicability for quality check of HBsAg vaccine preparations by monitoring the product consistency of different lot number and the product stability during storage. Results shown in this work clearly demonstrated that SE-HPLC method has potential as a versatile alternative technology for control of the final product by both manufacturers and the regulatory agencies. PMID:25604799

  5. Compression-based distance (CBD): a simple, rapid, and accurate method for microbiota composition comparison

    PubMed Central

    2013-01-01

    Background Perturbations in intestinal microbiota composition have been associated with a variety of gastrointestinal tract-related diseases. The alleviation of symptoms has been achieved using treatments that alter the gastrointestinal tract microbiota toward that of healthy individuals. Identifying differences in microbiota composition through the use of 16S rRNA gene hypervariable tag sequencing has profound health implications. Current computational methods for comparing microbial communities are usually based on multiple alignments and phylogenetic inference, making them time consuming and requiring exceptional expertise and computational resources. As sequencing data rapidly grows in size, simpler analysis methods are needed to meet the growing computational burdens of microbiota comparisons. Thus, we have developed a simple, rapid, and accurate method, independent of multiple alignments and phylogenetic inference, to support microbiota comparisons. Results We create a metric, called compression-based distance (CBD) for quantifying the degree of similarity between microbial communities. CBD uses the repetitive nature of hypervariable tag datasets and well-established compression algorithms to approximate the total information shared between two datasets. Three published microbiota datasets were used as test cases for CBD as an applicable tool. Our study revealed that CBD recaptured 100% of the statistically significant conclusions reported in the previous studies, while achieving a decrease in computational time required when compared to similar tools without expert user intervention. Conclusion CBD provides a simple, rapid, and accurate method for assessing distances between gastrointestinal tract microbiota 16S hypervariable tag datasets. PMID:23617892

  6. Accurate prediction of protein–protein interactions from sequence alignments using a Bayesian method

    PubMed Central

    Burger, Lukas; van Nimwegen, Erik

    2008-01-01

    Accurate and large-scale prediction of protein–protein interactions directly from amino-acid sequences is one of the great challenges in computational biology. Here we present a new Bayesian network method that predicts interaction partners using only multiple alignments of amino-acid sequences of interacting protein domains, without tunable parameters, and without the need for any training examples. We first apply the method to bacterial two-component systems and comprehensively reconstruct two-component signaling networks across all sequenced bacteria. Comparisons of our predictions with known interactions show that our method infers interaction partners genome-wide with high accuracy. To demonstrate the general applicability of our method we show that it also accurately predicts interaction partners in a recent dataset of polyketide synthases. Analysis of the predicted genome-wide two-component signaling networks shows that cognates (interacting kinase/regulator pairs, which lie adjacent on the genome) and orphans (which lie isolated) form two relatively independent components of the signaling network in each genome. In addition, while most genes are predicted to have only a small number of interaction partners, we find that 10% of orphans form a separate class of ‘hub' nodes that distribute and integrate signals to and from up to tens of different interaction partners. PMID:18277381

  7. A new class of accurate, mesh-free hydrodynamic simulation methods

    NASA Astrophysics Data System (ADS)

    Hopkins, Philip F.

    2015-06-01

    We present two new Lagrangian methods for hydrodynamics, in a systematic comparison with moving-mesh, smoothed particle hydrodynamics (SPH), and stationary (non-moving) grid methods. The new methods are designed to simultaneously capture advantages of both SPH and grid-based/adaptive mesh refinement (AMR) schemes. They are based on a kernel discretization of the volume coupled to a high-order matrix gradient estimator and a Riemann solver acting over the volume `overlap'. We implement and test a parallel, second-order version of the method with self-gravity and cosmological integration, in the code GIZMO:1 this maintains exact mass, energy and momentum conservation; exhibits superior angular momentum conservation compared to all other methods we study; does not require `artificial diffusion' terms; and allows the fluid elements to move with the flow, so resolution is automatically adaptive. We consider a large suite of test problems, and find that on all problems the new methods appear competitive with moving-mesh schemes, with some advantages (particularly in angular momentum conservation), at the cost of enhanced noise. The new methods have many advantages versus SPH: proper convergence, good capturing of fluid-mixing instabilities, dramatically reduced `particle noise' and numerical viscosity, more accurate sub-sonic flow evolution, and sharp shock-capturing. Advantages versus non-moving meshes include: automatic adaptivity, dramatically reduced advection errors and numerical overmixing, velocity-independent errors, accurate coupling to gravity, good angular momentum conservation and elimination of `grid alignment' effects. We can, for example, follow hundreds of orbits of gaseous discs, while AMR and SPH methods break down in a few orbits. However, fixed meshes minimize `grid noise'. These differences are important for a range of astrophysical problems.

  8. HPLC and chemometrics-assisted UV-spectroscopy methods for the simultaneous determination of ambroxol and doxycycline in capsule.

    PubMed

    Hadad, Ghada M; El-Gindy, Alaa; Mahmoud, Waleed M M

    2008-08-01

    High-performance liquid chromatography (HPLC) and multivariate spectrophotometric methods are described for the simultaneous determination of ambroxol hydrochloride (AM) and doxycycline (DX) in combined pharmaceutical capsules. The chromatographic separation was achieved on reversed-phase C(18) analytical column with a mobile phase consisting of a mixture of 20mM potassium dihydrogen phosphate, pH 6-acetonitrile in ratio of (1:1, v/v) and UV detection at 245 nm. Also, the resolution has been accomplished by using numerical spectrophotometric methods as classical least squares (CLS), principal component regression (PCR) and partial least squares (PLS-1) applied to the UV spectra of the mixture and graphical spectrophotometric method as first derivative of the ratio spectra ((1)DD) method. Analytical figures of merit (FOM), such as sensitivity, selectivity, analytical sensitivity, limit of quantitation and limit of detection were determined for CLS, PLS-1 and PCR methods. The proposed methods were validated and successfully applied for the analysis of pharmaceutical formulation and laboratory-prepared mixtures containing the two component combination. PMID:17931962

  9. HPLC and chemometrics-assisted UV-spectroscopy methods for the simultaneous determination of ambroxol and doxycycline in capsule

    NASA Astrophysics Data System (ADS)

    Hadad, Ghada M.; El-Gindy, Alaa; Mahmoud, Waleed M. M.

    2008-08-01

    High-performance liquid chromatography (HPLC) and multivariate spectrophotometric methods are described for the simultaneous determination of ambroxol hydrochloride (AM) and doxycycline (DX) in combined pharmaceutical capsules. The chromatographic separation was achieved on reversed-phase C 18 analytical column with a mobile phase consisting of a mixture of 20 mM potassium dihydrogen phosphate, pH 6-acetonitrile in ratio of (1:1, v/v) and UV detection at 245 nm. Also, the resolution has been accomplished by using numerical spectrophotometric methods as classical least squares (CLS), principal component regression (PCR) and partial least squares (PLS-1) applied to the UV spectra of the mixture and graphical spectrophotometric method as first derivative of the ratio spectra ( 1DD) method. Analytical figures of merit (FOM), such as sensitivity, selectivity, analytical sensitivity, limit of quantitation and limit of detection were determined for CLS, PLS-1 and PCR methods. The proposed methods were validated and successfully applied for the analysis of pharmaceutical formulation and laboratory-prepared mixtures containing the two component combination.

  10. Critical development by design of a rugged HPLC-MS/MS method for direct determination of ibuprofen enantiomers in human plasma.

    PubMed

    Nakov, Natalija; Petkovska, Rumenka; Ugrinova, Liljana; Kavrakovski, Zoran; Dimitrovska, Aneta; Svinarov, Dobrin

    2015-06-15

    Development and validation of a HPLC-MS/MS method for direct determination of R- and S-ibuprofen (Ibu) in human plasma without a need of derivatization or other complexities such as postcolumn infusion of solvents or reagents was performed. Critical steps were investigated during method development using experimental design to achieve a reliable and rugged assay. The LC-MS/MS separation of R-Ibu and S-Ibu was obtained on Lux Cellulose chiral column utilizing 0.1% (v/v) acetic acid in mixture of methanol and water (90:10%, v/v) as a mobile phase. Two types of extraction procedure for Ibu and Ketoprofen (internal standard, IS) were optimized using Full factorial 3(2) design (LLE) and D-Optimal Experimental Design (SPE). Excellent recovery values, 80% (mean) and 95% (mean) for LLE and SPE respectively, were obtained using 50μL plasma. The matrix effect was assessed for both of the extraction procedures, including hyperlipidaemic and haemolyzed plasma. The extensive investigation of matrix effect showed that LLE yields cleaner extracts than the SPE. The result of the investigation of in vitro interconversion of R-Ibu and S-Ibu showed that it does not occur under the influence of pH, temperature, and in the overall analytical procedure. The validation data, adhered to EMA guideline for validation of bioanalytical methods, showed that the proposed method provides accurate and reproducible results in range of 0.1-50mg/L with a lower limit of detection of 0.02mg/L. The applicability of the method was demonstrated through determination of R-Ibu and S-Ibu in human plasma after oral administration of 400mg rac-Ibu. PMID:25958322

  11. CHARACTERIZATION, HPLC METHOD DEVELOPMENT AND IMPURITY IDENTIFICATION FOR 3,4,3-LI(1,2-HOPO), A POTENT ACTINIDE CHELATOR FOR RADIONUCLIDE DECORPORATION

    PubMed Central

    Liu, Mingtao; Wang, Jennie; Wu, Xiaogang; Wang, Euphemia; Abergel, Rebecca J.; Shuh, David K.; Raymond, Kenneth N.; Liu, Paul

    2014-01-01

    3,4,3-LI(1,2-HOPO), 1,5,10,14-tetra(1-hydroxy-2-pyridon-6-oyl)-1,5,10,14-tetraazatetradecane), is a potent octadentate chelator of actinides. It is being developed as a decorporation treatment for internal contamination with radionuclides. Conventional HPLC methods exhibited speciation peaks and bridging, likely attributable to the agent’s complexation with residual metallic ions in the HPLC system. Derivatization of the target ligand in situ with Fe(III) chloride, however, provided a single homogeneous iron-complex that can readily be detected and analyzed by HPLC. The HPLC method used an Agilent Eclipse XDB-C18 column (150 mm × 4.6 mm, 5 μm) at 25 °C with UV detection at 280 nm. A gradient elution, with acetonitrile (11% to 100%)/buffer mobile phase, was developed for impurity profiling. The buffer consisted of 0.02% formic acid and 10 mM ammonium formate at pH 4.6. An Agilent 1200 LC-6530 Q-TOF/MS system was employed to characterize the [Fe(III)-3,4,3-LI(1,2-HOPO)] derivative and impurities. The proposed HPLC method was validated for specificity, linearity (concentration range 0.13–0.35 mg/mL, r = 0.9999), accuracy (recovery 98.3–103.3%), precision (RSD ≤ 1.6%) and sensitivity (LOD 0.08 μg/mL). The LC/HRMS revealed that the derivative was a complex consisting of one 3,4,3-LI(1,2-HOPO) molecule, one hydroxide ligand, and two iron atoms. Impurities were also identified with LC/HRMS. The validated HPLC method was used in shelf-life evaluation studies which showed that the API remained unchanged for one year at 25°C/60% RH. PMID:25459944

  12. A Simple yet Accurate Method for the Estimation of the Biovolume of Planktonic Microorganisms.

    PubMed

    Saccà, Alessandro

    2016-01-01

    Determining the biomass of microbial plankton is central to the study of fluxes of energy and materials in aquatic ecosystems. This is typically accomplished by applying proper volume-to-carbon conversion factors to group-specific abundances and biovolumes. A critical step in this approach is the accurate estimation of biovolume from two-dimensional (2D) data such as those available through conventional microscopy techniques or flow-through imaging systems. This paper describes a simple yet accurate method for the assessment of the biovolume of planktonic microorganisms, which works with any image analysis system allowing for the measurement of linear distances and the estimation of the cross sectional area of an object from a 2D digital image. The proposed method is based on Archimedes' principle about the relationship between the volume of a sphere and that of a cylinder in which the sphere is inscribed, plus a coefficient of 'unellipticity' introduced here. Validation and careful evaluation of the method are provided using a variety of approaches. The new method proved to be highly precise with all convex shapes characterised by approximate rotational symmetry, and combining it with an existing method specific for highly concave or branched shapes allows covering the great majority of cases with good reliability. Thanks to its accuracy, consistency, and low resources demand, the new method can conveniently be used in substitution of any extant method designed for convex shapes, and can readily be coupled with automated cell imaging technologies, including state-of-the-art flow-through imaging devices. PMID:27195667

  13. A Simple yet Accurate Method for the Estimation of the Biovolume of Planktonic Microorganisms

    PubMed Central

    2016-01-01

    Determining the biomass of microbial plankton is central to the study of fluxes of energy and materials in aquatic ecosystems. This is typically accomplished by applying proper volume-to-carbon conversion factors to group-specific abundances and biovolumes. A critical step in this approach is the accurate estimation of biovolume from two-dimensional (2D) data such as those available through conventional microscopy techniques or flow-through imaging systems. This paper describes a simple yet accurate method for the assessment of the biovolume of planktonic microorganisms, which works with any image analysis system allowing for the measurement of linear distances and the estimation of the cross sectional area of an object from a 2D digital image. The proposed method is based on Archimedes’ principle about the relationship between the volume of a sphere and that of a cylinder in which the sphere is inscribed, plus a coefficient of ‘unellipticity’ introduced here. Validation and careful evaluation of the method are provided using a variety of approaches. The new method proved to be highly precise with all convex shapes characterised by approximate rotational symmetry, and combining it with an existing method specific for highly concave or branched shapes allows covering the great majority of cases with good reliability. Thanks to its accuracy, consistency, and low resources demand, the new method can conveniently be used in substitution of any extant method designed for convex shapes, and can readily be coupled with automated cell imaging technologies, including state-of-the-art flow-through imaging devices. PMID:27195667

  14. Direct online HPLC-CV-AFS method for traces of methylmercury without derivatisation: a matrix-independent method for urine, sediment and biological tissue samples.

    PubMed

    Brombach, Christoph-Cornelius; Gajdosechova, Zuzana; Chen, Bin; Brownlow, Andrew; Corns, Warren T; Feldmann, Jörg; Krupp, Eva M

    2015-01-01

    Mercury (Hg) is a global pollutant which occurs in different species, with methylmercury (MeHg) being the critical compound due to its neurotoxicity and bioaccumulation through the food chain. Methods for trace speciation of MeHg are therefore needed for a vast range of sample matrices, such as biological tissues, fluids, soils or sediments. We have previously developed an ultra-trace speciation method for methylmercury in water, based on a preconcentration HPLC cold vapour atomic fluorescence spectrometry (HPLC-CV-AFS) method. The focus of this work is mercury speciation in a variety of sample matrices to assess the versatility of the method. Certified reference materials were used where possible, and samples were spiked where reference materials were not available, e.g. human urine. Solid samples were submitted for commonly used digestion or extraction processes to obtain a liquid sample for injection into the analytical system. For MeHg in sediment samples, an extraction procedure was adapted to accommodate MeHg separation from high amounts of Hg(2+) to avoid an overload of the column. The recovery for MeHg determination was found to be in the range of 88-104% in fish reference materials (DOLT-2, DOLT-4, DORM-3), lobster (TORT-2), seaweed (IAEA-140/TM), sediments (ERM(®)-CC580) and spiked urine and has been proven to be robust, reliable, virtually matrix-independent and relatively cost-effective. Applications in the ultra-trace concentration range are possible using the preconcentration up to 200 mL, while for higher MeHg-containing samples, lower volumes can be applied. A comparison was carried out between species-specific isotope dilution gas chromatography inductively coupled plasma mass spectrometry (SSID-GC-ICP-MS) as the gold standard and HPLC-CV-AFS for biological tissues (liver, kidney and muscle of pilot whales), showing a slope of 1.008 and R (2) = 0.97, which indicates that the HPLC-CV-AFS method achieves well-correlated results for MeHg in

  15. A Validated HPLC Method for Simultaneous Determination of Caffeoyl Phenylethanoid Glucosides and Flavone 8-C-glycosides in Haberlea rhodopensis.

    PubMed

    Zheleva-Dimitrova, Dimitrina; Nedialkov, Paraskev; Giresser, Ulrich

    2016-06-01

    A HPLC-UV method for analysis of the main compounds: caffeoyl phenylethanoid glucosides myconoside (1) and paucifloside (2) and flavone 8-C-glycosides: hispidulin 8-C-β-galactopyranoside (3), hispidulin 8-C-(2"-O-syringoyl-β-glucopyranoside) (4), hispidulin 8-C-(6-O-acetyl-β-glucopyranoside) (5) and hispidulin 8-C-(6-O-acetyl-2"-O-syringoyl--glucopyranoside) (6) in Haberlea rhodopensis leaves was developed and validated. Compound 3 was isolated for the first time from the title species. Ultrasound extraction with 80% methanol at room temperature allowed a good recovery of analytes (from 87.2 % for 1 to 109.8 % for 3) and the precision of the entire procedure was between 1.6% and 6.9%. The subsequent HPLC separation and quantification was achieved using a Hypersil ODS C18 column and UV detection at 280 nm. The mobile phase comprised methanol and 0.1 % o-phosphoric acid, and gradient elution mode was applied. The detection limits ranged from 0.042 μg/mL (6) to 0.18 μg/mL (5). The total amount in leaves of the assayed phenolic compounds was 374.2 mg/g. Myconoside was found to be the dominant compound in H. rhodopensis extract (332.2 ± 0.7 mg/g dw) and reached up to 88.8% of the analyzed mixture in leaves, while the total content of flavone C-glycosides was 17.1 mg/g dw. PMID:27534117

  16. Stability-indicating HPLC method for the determination of the stability of oxytocin parenteral solutions prepared in polyolefin bags.

    PubMed

    Kaushal, G; Sayre, B E; Prettyman, T

    2012-02-01

    Oxytocin is very commonly used in clinical settings and is a nonapeptide hormone that stimulates the contraction of uterine smooth muscles. In this study the stability of extemporaneously compounded oxytocin solutions was investigated in polyolefin bags. The sterile preparations of oxytocin were compounded to the strength of 0.02 U/mL in accordance with United States Pharmacopeia (USP) <797> standards. In order to carry out the stability testing of these parenteral products, the solutions were stored under three different temperature conditions of -20°C (frozen), 2-6°C (refrigerated), and 22-25°C (room temperature). Three solutions from each temperature were withdrawn and were assessed for stability on days 0, 7, 15, 21, and 30 as per the USP guidelines. The assay of oxytocin was examined by an HPLC method at each time point. No precipitation, cloudiness or color change was observed during this study at all temperatures. The assay content by HPLC revealed that oxytocin retains greater than at least 90% of the initial concentrations for 21 days. There was no significant change in pH and absorbance values for 21 days under all the conditions of storage. Oxytocin parenteral solutions in the final concentration of 0.02 U/mL and diluted in normal saline are stable for at least 30 days under frozen and refrigerated conditions for 30 days. At the room temperature, the oxytocin solutions were stable for at least 21 days. The stability analysis results show that the shelf-life of 21 days observed in this study was far better than their recommended expiration dates. PMID:22460429

  17. A simple and accurate resist parameter extraction method for sub-80-nm DRAM patterns

    NASA Astrophysics Data System (ADS)

    Lee, Sook; Hwang, Chan; Park, Dong-Woon; Kim, In-Sung; Kim, Ho-Chul; Woo, Sang-Gyun; Cho, Han-Ku; Moon, Joo-Tae

    2004-05-01

    Due to the polarization effect of high NA lithography, the consideration of resist effect in lithography simulation becomes increasingly important. In spite of the importance of resist simulation, many process engineers are reluctant to consider resist effect in lithography simulation due to time-consuming procedure to extract required resist parameters and the uncertainty of measurement of some parameters. Weiss suggested simplified development model, and this model does not require the complex kinetic parameters. For the device fabrication engineers, there is a simple and accurate parameter extraction and optimizing method using Weiss model. This method needs refractive index, Dill"s parameters and development rate monitoring (DRM) data in parameter extraction. The parameters extracted using referred sequence is not accurate, so that we have to optimize the parameters to fit the critical dimension scanning electron microscopy (CD SEM) data of line and space patterns. Hence, the FiRM of Sigma-C is utilized as a resist parameter-optimizing program. According to our study, the illumination shape, the aberration and the pupil mesh point have a large effect on the accuracy of resist parameter in optimization. To obtain the optimum parameters, we need to find the saturated mesh points in terms of normalized intensity log slope (NILS) prior to an optimization. The simulation results using the optimized parameters by this method shows good agreement with experiments for iso-dense bias, Focus-Exposure Matrix data and sub 80nm device pattern simulation.

  18. Induced Dual-Nanospray: A Novel Internal Calibration Method for Convenient and Accurate Mass Measurement

    NASA Astrophysics Data System (ADS)

    Li, Yafeng; Zhang, Ning; Zhou, Yueming; Wang, Jianing; Zhang, Yiming; Wang, Jiyun; Xiong, Caiqiao; Chen, Suming; Nie, Zongxiu

    2013-09-01

    Accurate mass information is of great importance in the determination of unknown compounds. An effective and easy-to-control internal mass calibration method will dramatically benefit accurate mass measurement. Here we reported a simple induced dual-nanospray internal calibration device which has the following three advantages: (1) the two sprayers are in the same alternating current field; thus both reference ions and sample ions can be simultaneously generated and recorded. (2) It is very simple and can be easily assembled. Just two metal tubes, two nanosprayers, and an alternating current power supply are included. (3) With the low-flow-rate character and the versatility of nanoESI, this calibration method is capable of calibrating various samples, even untreated complex samples such as urine and other biological samples with small sample volumes. The calibration errors are around 1 ppm in positive ion mode and 3 ppm in negative ion mode with good repeatability. This new internal calibration method opens up new possibilities in the determination of unknown compounds, and it has great potential for the broad applications in biological and chemical analysis.

  19. A fast GNU method to draw accurate scientific illustrations for taxonomy.

    PubMed

    Montesanto, Giuseppe

    2015-01-01

    Nowadays only digital figures are accepted by the most important journals of taxonomy. These may be produced by scanning conventional drawings, made with high precision technical ink-pens, which normally use capillary cartridge and various line widths. Digital drawing techniques that use vector graphics, have already been described in literature to support scientists in drawing figures and plates for scientific illustrations; these techniques use many different software and hardware devices. The present work gives step-by-step instructions on how to make accurate line drawings with a new procedure that uses bitmap graphics with the GNU Image Manipulation Program (GIMP). This method is noteworthy: it is very accurate, producing detailed lines at the highest resolution; the raster lines appear as realistic ink-made drawings; it is faster than the traditional way of making illustrations; everyone can use this simple technique; this method is completely free as it does not use expensive and licensed software and it can be used with different operating systems. The method has been developed drawing figures of terrestrial isopods and some examples are here given. PMID:26261449

  20. Accurate Adaptive Level Set Method and Sharpening Technique for Three Dimensional Deforming Interfaces

    NASA Technical Reports Server (NTRS)

    Kim, Hyoungin; Liou, Meng-Sing

    2011-01-01

    In this paper, we demonstrate improved accuracy of the level set method for resolving deforming interfaces by proposing two key elements: (1) accurate level set solutions on adapted Cartesian grids by judiciously choosing interpolation polynomials in regions of different grid levels and (2) enhanced reinitialization by an interface sharpening procedure. The level set equation is solved using a fifth order WENO scheme or a second order central differencing scheme depending on availability of uniform stencils at each grid point. Grid adaptation criteria are determined so that the Hamiltonian functions at nodes adjacent to interfaces are always calculated by the fifth order WENO scheme. This selective usage between the fifth order WENO and second order central differencing schemes is confirmed to give more accurate results compared to those in literature for standard test problems. In order to further improve accuracy especially near thin filaments, we suggest an artificial sharpening method, which is in a similar form with the conventional re-initialization method but utilizes sign of curvature instead of sign of the level set function. Consequently, volume loss due to numerical dissipation on thin filaments is remarkably reduced for the test problems

  1. A fast GNU method to draw accurate scientific illustrations for taxonomy

    PubMed Central

    Montesanto, Giuseppe

    2015-01-01

    Abstract Nowadays only digital figures are accepted by the most important journals of taxonomy. These may be produced by scanning conventional drawings, made with high precision technical ink-pens, which normally use capillary cartridge and various line widths. Digital drawing techniques that use vector graphics, have already been described in literature to support scientists in drawing figures and plates for scientific illustrations; these techniques use many different software and hardware devices. The present work gives step-by-step instructions on how to make accurate line drawings with a new procedure that uses bitmap graphics with the GNU Image Manipulation Program (GIMP). This method is noteworthy: it is very accurate, producing detailed lines at the highest resolution; the raster lines appear as realistic ink-made drawings; it is faster than the traditional way of making illustrations; everyone can use this simple technique; this method is completely free as it does not use expensive and licensed software and it can be used with different operating systems. The method has been developed drawing figures of terrestrial isopods and some examples are here given. PMID:26261449

  2. Joint iris boundary detection and fit: a real-time method for accurate pupil tracking.

    PubMed

    Barbosa, Marconi; James, Andrew C

    2014-08-01

    A range of applications in visual science rely on accurate tracking of the human pupil's movement and contraction in response to light. While the literature for independent contour detection and fitting of the iris-pupil boundary is vast, a joint approach, in which it is assumed that the pupil has a given geometric shape has been largely overlooked. We present here a global method for simultaneously finding and fitting of an elliptic or circular contour against a dark interior, which produces consistently accurate results even under non-ideal recording conditions, such as reflections near and over the boundary, droopy eye lids, or the sudden formation of tears. The specific form of the proposed optimization problem allows us to write down closed analytic formulae for the gradient and the Hessian of the objective function. Moreover, both the objective function and its derivatives can be cast into vectorized form, making the proposed algorithm significantly faster than its closest relative in the literature. We compare methods in multiple ways, both analytically and numerically, using real iris images as well as idealizations of the iris for which the ground truth boundary is precisely known. The method proposed here is illustrated under challenging recording conditions and it is shown to be robust. PMID:25136477

  3. A new cation-exchange method for accurate field speciation of hexavalent chromium

    USGS Publications Warehouse

    Ball, J.W.; McCleskey, R.B.

    2003-01-01

    A new method for field speciation of Cr(VI) has been developed to meet present stringent regulatory standards and to overcome the limitations of existing methods. The method consists of passing a water sample through strong acid cation-exchange resin at the field site, where Cr(III) is retained while Cr(VI) passes into the effluent and is preserved for later determination. The method is simple, rapid, portable, and accurate, and makes use of readily available, inexpensive materials. Cr(VI) concentrations are determined later in the laboratory using any elemental analysis instrument sufficiently sensitive to measure the Cr(VI) concentrations of interest. The new method allows measurement of Cr(VI) concentrations as low as 0.05 ??g 1-1, storage of samples for at least several weeks prior to analysis, and use of readily available analytical instrumentation. Cr(VI) can be separated from Cr(III) between pH 2 and 11 at Cr(III)/Cr(VI) concentration ratios as high as 1000. The new method has demonstrated excellent comparability with two commonly used methods, the Hach Company direct colorimetric method and USEPA method 218.6. The new method is superior to the Hach direct colorimetric method owing to its relative sensitivity and simplicity. The new method is superior to USEPA method 218.6 in the presence of Fe(II) concentrations up to 1 mg 1-1 and Fe(III) concentrations up to 10 mg 1-1. Time stability of preserved samples is a significant advantage over the 24-h time constraint specified for USEPA method 218.6.

  4. Nebulizer calibration using lithium chloride: an accurate, reproducible and user-friendly method.

    PubMed

    Ward, R J; Reid, D W; Leonard, R F; Johns, D P; Walters, E H

    1998-04-01

    Conventional gravimetric (weight loss) calibration of jet nebulizers overestimates their aerosol output by up to 80% due to unaccounted evaporative loss. We examined two methods of measuring true aerosol output from jet nebulizers. A new adaptation of a widely available clinical assay for lithium (determined by flame photometry, LiCl method) was compared to an existing electrochemical method based on fluoride detection (NaF method). The agreement between the two methods and the repeatability of each method were examined. Ten Mefar jet nebulizers were studied using a Mefar MK3 inhalation dosimeter. There was no significant difference between the two methods (p=0.76) with mean aerosol output of the 10 nebulizers being 7.40 mg x s(-1) (SD 1.06; range 5.86-9.36 mg x s(-1)) for the NaF method and 7.27 mg x s(-1) (SD 0.82; range 5.52-8.26 mg x s(-1)) for the LiCl method. The LiCl method had a coefficient of repeatability of 13 mg x s(-1) compared with 3.7 mg x s(-1) for the NaF method. The LiCl method accurately measured true aerosol output and was considerably easier to use. It was also more repeatable, and hence more precise, than the NaF method. Because the LiCl method uses an assay that is routinely available from hospital biochemistry laboratories, it is easy to use and, thus, can readily be adopted by busy respiratory function departments. PMID:9623700

  5. Multi-residue method for detecting coccidiostats at carry-over level in feed by HPLC-MS/MS.

    PubMed

    Delahaut, Ph; Pierret, G; Ralet, N; Dubois, M; Gillard, N

    2010-06-01

    A multi-residue HPLC-ESI-MS/MS method has been developed for the simultaneous extraction, detection and confirmation of the 11 coccidiostats referenced by Regulation 2009/8/EC (lasalocid sodium, narasin, salinomycin sodium, monensin sodium, semduramicin sodium, maduramicin ammonium alpha, robenidine hydrochloride, decoquinate, halofuginone hydrobromide, nicarbazin, and diclazuril) in feedstuffs at carry-over level. The sensitivity of the method allows quantification and confirmation for all coccidiostats below target concentration. The method was in-house validated and meets all criteria of European legislation (2002/657/EC). The precision of the method was determined under repeatability and within-laboratory reproducibility conditions; RSD(r) and RSD(R) were below the maximum permitted values for every tested concentration. The specificity was checked by analysing representative blank samples and blank samples fortified with potentially interfering substances (benzimidazoles, corticosteroides, triphenylmethane dyes, quinolones, nitrofurans, nitroimidazoles, phenicols); no interference were found. Concerning quantification, a quadratic regression model was fitted to every calibration curve with a regression coefficient r2 above 0.99 on each data set. Finally, the expanded uncertainty U was calculated with data obtained within the laboratory while applying the method during validation and in routine tests. PMID:20198524

  6. Analysis of Carbamate Pesticides: Validation of Semi-Volatile Analysis by HPLC-MS/MS by EPA Method MS666

    SciTech Connect

    Owens, J; Koester, C

    2008-05-14

    The Environmental Protection Agency's (EPA) Region 5 Chicago Regional Laboratory (CRL) developed a method for analysis of aldicarb, bromadiolone, carbofuran, oxamyl, and methomyl in water by high performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS), titled Method EPA MS666. This draft standard operating procedure (SOP) was distributed to multiple EPA laboratories and to Lawrence Livermore National Laboratory, which was tasked to serve as a reference laboratory for EPA's Environmental Reference Laboratory Network (ERLN) and to develop and validate analytical procedures. The primary objective of this study was to validate and verify the analytical procedures described in MS666 for analysis of carbamate pesticides in aqueous samples. The gathered data from this validation study will be used to: (1) demonstrate analytical method performance; (2) generate quality control acceptance criteria; and (3) revise the SOP to provide a validated method that would be available for use during a homeland security event. The data contained in this report will be compiled, by EPA CRL, with data generated by other EPA Regional laboratories so that performance metrics of Method EPA MS666 can be determined.

  7. Analysis of Thiodiglycol: Validation of Semi-Volatile Analysis by HPLC-MS/MS by EPA Method MS777

    SciTech Connect

    Owens, J; Koester, C

    2008-07-24

    The Environmental Protection Agency's (EPA) Region 5 Chicago Regional Laboratory (CRL) developed a method for the analysis of thiodiglycol, the breakdown product of the sulfur mustard HD, in water by high performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS), titled Method EPA MS777 (hereafter referred to as EPA CRL SOP MS777). This draft standard operating procedure (SOP) was distributed to multiple EPA laboratories and to Lawrence Livermore National Laboratory, which was tasked to serve as a reference laboratory for EPA's Environmental Reference Laboratory Network (ERLN) and to develop and validate analytical procedures. The primary objective of this study was to verify the analytical procedures described in MS777 for analysis of thiodiglycol in aqueous samples. The gathered data from this study will be used to: (1) demonstrate analytical method performance; (2) generate quality control acceptance criteria; and (3) revise the SOP to provide a validated method that would be available for use during a homeland security event. The data contained in this report will be compiled, by EPA CRL, with data generated by other EPA Regional laboratories so that performance metrics of Method EPA MS777 can be determined.

  8. Validation and Uncertainty Estimation of an Ecofriendly and Stability-Indicating HPLC Method for Determination of Diltiazem in Pharmaceutical Preparations

    PubMed Central

    Sadeghi, Fahimeh; Navidpour, Latifeh; Bayat, Sima; Afshar, Minoo

    2013-01-01

    A green, simple, and stability-indicating RP-HPLC method was developed for the determination of diltiazem in topical preparations. The separation was based on a C18 analytical column using a mobile phase consisted of ethanol: phosphoric acid solution (pH = 2.5) (35 : 65, v/v). Column temperature was set at 50°C and quantitation was achieved with UV detection at 240 nm. In forced degradation studies, the drug was subjected to oxidation, hydrolysis, photolysis, and heat. The method was validated for specificity, selectivity, linearity, precision, accuracy, and robustness. The applied procedure was found to be linear in diltiazem concentration range of 0.5–50 μg/mL (r2 = 0.9996). Precision was evaluated by replicate analysis in which % relative standard deviation (RSD) values for areas were found below 2.0. The recoveries obtained (99.25%–101.66%) ensured the accuracy of the developed method. The degradation products as well as the pharmaceutical excipients were well resolved from the pure drug. The expanded uncertainty (5.63%) of the method was also estimated from method validation data. Accordingly, the proposed validated and sustainable procedure was proved to be suitable for routine analyzing and stability studies of diltiazem in pharmaceutical preparations. PMID:24163778

  9. A validated specific stability-indicating RP-HPLC assay method for the determination of loteprednol etabonate in eye drops.

    PubMed

    Han, Yong K; Segall, Adriana I

    2015-01-01

    A new stability-indicating RP-HPLC assay method was developed and validated for quantitative determination of loteprednol etabonate in bulk drugs and in ophthalmic suspensions in the presence of degradation products generated from forced degradation studies. The system consisted of Agilent Technologies Zorbax Eclipse XDB-Phenyl 5 µm 4.6 × 250 mm, and detection was performed at 244 nm. The mobile phase consisted of water-acetonitrile-acetic acid (34.5:65.0:0.5, v/v/v) run at a flow rate of 1 mL/min and maintained at room temperature. The calibration curve was linear from 30 to 70 µg/mL with r > 0.999. Accuracy (mean recovery 100.78%) and precision were found to be satisfactory. Stress conditions including acid and alkali hydrolysis, water stress, oxidation, photolysis and heat were applied. The degradation products did not interfere with the detection of loteprednol etabonate, thus the method can be considered as a stability-indicating method. The proposed method can be used for quality control assay of loteprednol etabonate in bulk drug and in ophthalmic suspensions and for stability studies as a result of the ability of the method to separate loteprednol etabonate from its degradation products and excipients. PMID:25234383

  10. HPLC-FLD methods to quantify chloroaluminum phthalocyanine in nanoparticles, plasma and tissue: application in pharmacokinetic and biodistribution studies.

    PubMed

    Oliveira, Líliam Teixeira; Garcia, Giani Martins; Kano, Eunice Kazue; Tedesco, Antônio Cláudio; Mosqueira, Vanessa Carla Furtado

    2011-08-25

    Analytical and bioanalytical methods of high-performance liquid chromatography with fluorescence detection (HPLC-FLD) were developed and validated for the determination of chloroaluminum phthalocyanine in different formulations of polymeric nanocapsules, plasma and livers of mice. Plasma and homogenized liver samples were extracted with ethyl acetate, and zinc phthalocyanine was used as internal standard. The results indicated that the methods were linear and selective for all matrices studied. Analysis of accuracy and precision showed adequate values, with variations lower than 10% in biological samples and lower than 2% in analytical samples. The recoveries were as high as 96% and 99% in the plasma and livers, respectively. The quantification limit of the analytical method was 1.12 ng/ml, and the limits of quantification of the bioanalytical method were 15 ng/ml and 75 ng/g for plasma and liver samples, respectively. The bioanalytical method developed was sensitive in the ranges of 15-100 ng/ml in plasma and 75-500 ng/g in liver samples and was applied to studies of biodistribution and pharmacokinetics of AlClPc. PMID:21596512

  11. A validated RP-HPLC method for simultaneous determination of propranolol and valsartan in bulk drug and gel formulation

    PubMed Central

    Imam, Syed Sarim; Ahad, Abdul; Aqil, Mohammed; Sultana, Yasmin; Ali, Asgar

    2013-01-01

    Objective: A simple, precise, and stability indicating high performance liquid chromatography (HPLC) method was developed and validated for the simultaneous determination of propranolol hydrochloride and valsartan in pharmaceutical dosage form. Materials and Methods: The method involves the use of easily available inexpensive laboratory reagents. The separation was achieved on Hypersil ODS C-18 column (250*4.6 mm, i.d., 5 μm particle size) with isocratic flow with UV detector. The mobile phase at a flow rate of 1.0 mL/min consisted of acetonitrile, methanol, and 0.01 M disodium hydrogen phosphate (pH 3.5) in the ratio of 50:35:15 v/v. Results: A linear response was observed over the concentration range 5-50 μg/mL of propranolol and the concentration range 4-32 μg/mL of valsartan. Limit of detection and limit of quantitation for propranolol were 0.27 μg/mL and 0.85 μg/mL, and for valsartan were 0.45 μg/mL and 1.39 μg/mL, respectively. The method was successfully validated in accordance to ICH guidelines acceptance criteria for linearity, accuracy, precision, specificity, robustness. Conclusion: The analysis concluded that the method was selective for simultaneous estimation of propranolol and valsartan can be potentially used for the estimation of these drugs in combined dosage form. PMID:23559826

  12. Validation and uncertainty estimation of an ecofriendly and stability-indicating HPLC method for determination of diltiazem in pharmaceutical preparations.

    PubMed

    Sadeghi, Fahimeh; Navidpour, Latifeh; Bayat, Sima; Afshar, Minoo

    2013-01-01

    A green, simple, and stability-indicating RP-HPLC method was developed for the determination of diltiazem in topical preparations. The separation was based on a C18 analytical column using a mobile phase consisted of ethanol: phosphoric acid solution (pH = 2.5) (35 : 65, v/v). Column temperature was set at 50°C and quantitation was achieved with UV detection at 240 nm. In forced degradation studies, the drug was subjected to oxidation, hydrolysis, photolysis, and heat. The method was validated for specificity, selectivity, linearity, precision, accuracy, and robustness. The applied procedure was found to be linear in diltiazem concentration range of 0.5-50  μ g/mL (r (2) = 0.9996). Precision was evaluated by replicate analysis in which % relative standard deviation (RSD) values for areas were found below 2.0. The recoveries obtained (99.25%-101.66%) ensured the accuracy of the developed method. The degradation products as well as the pharmaceutical excipients were well resolved from the pure drug. The expanded uncertainty (5.63%) of the method was also estimated from method validation data. Accordingly, the proposed validated and sustainable procedure was proved to be suitable for routine analyzing and stability studies of diltiazem in pharmaceutical preparations. PMID:24163778

  13. Consisitent and Accurate Finite Volume Methods for Coupled Flow and Geomechanics

    NASA Astrophysics Data System (ADS)

    Nordbotten, J. M.

    2014-12-01

    We introduce a new class of cell-centered finite volume methods for elasticity and poro-elasticity. As compared to lowest-order finite element discretizations, the new discretization has no additional degrees of freedom, and yet gives more accurate stress and flow fields. This finite volume discretization methods has furthermore the advantage that the mechanical discretization is fully compatible (in terms of grid and variables) with the standard cell-centered finite volume discretizations that are prevailing for commercial simulation of multi-phase flows in porous media. Theoretical analysis proves the convergence of the method. We give results showing that so-called numerical locking is avoided for a large class of structured and unstructured grids. The results are valid in both two and three spatial dimensions. The talk concludes with applications to problems with coupled multi-phase flow, transport and deformation, together with fractured porous media.

  14. An improved method to accurately calibrate the gantry angle indicators of the radiotherapy linear accelerators

    NASA Astrophysics Data System (ADS)

    Chang, Liyun; Ho, Sheng-Yow; Du, Yi-Chun; Lin, Chih-Ming; Chen, Tainsong

    2007-06-01

    The calibration of the gantry angle indicator is an important and basic quality assurance (QA) item for the radiotherapy linear accelerator. In this study, we propose a new and practical method, which uses only the digital level, V-film, and general solid phantoms. By taking the star shot only, we can accurately calculate the true gantry angle according to the geometry of the film setup. The results on our machine showed that the gantry angle was shifted by -0.11° compared with the digital indicator, and the standard deviation was within 0.05°. This method can also be used for the simulator. In conclusion, this proposed method could be adopted as an annual QA item for mechanical QA of the accelerator.

  15. Accurate calculation of computer-generated holograms using angular-spectrum layer-oriented method.

    PubMed

    Zhao, Yan; Cao, Liangcai; Zhang, Hao; Kong, Dezhao; Jin, Guofan

    2015-10-01

    Fast calculation and correct depth cue are crucial issues in the calculation of computer-generated hologram (CGH) for high quality three-dimensional (3-D) display. An angular-spectrum based algorithm for layer-oriented CGH is proposed. Angular spectra from each layer are synthesized as a layer-corresponded sub-hologram based on the fast Fourier transform without paraxial approximation. The proposed method can avoid the huge computational cost of the point-oriented method and yield accurate predictions of the whole diffracted field compared with other layer-oriented methods. CGHs of versatile formats of 3-D digital scenes, including computed tomography and 3-D digital models, are demonstrated with precise depth performance and advanced image quality. PMID:26480062

  16. Quick and accurate estimation of the elastic constants using the minimum image method

    NASA Astrophysics Data System (ADS)

    Tretiakov, Konstantin V.; Wojciechowski, Krzysztof W.

    2015-04-01

    A method for determining the elastic properties using the minimum image method (MIM) is proposed and tested on a model system of particles interacting by the Lennard-Jones (LJ) potential. The elastic constants of the LJ system are determined in the thermodynamic limit, N → ∞, using the Monte Carlo (MC) method in the NVT and NPT ensembles. The simulation results show that when determining the elastic constants, the contribution of long-range interactions cannot be ignored, because that would lead to erroneous results. In addition, the simulations have revealed that the inclusion of further interactions of each particle with all its minimum image neighbors even in case of small systems leads to results which are very close to the values of elastic constants in the thermodynamic limit. This enables one for a quick and accurate estimation of the elastic constants using very small samples.

  17. Accurate prediction of lattice energies and structures of molecular crystals with molecular quantum chemistry methods.

    PubMed

    Fang, Tao; Li, Wei; Gu, Fangwei; Li, Shuhua

    2015-01-13

    We extend the generalized energy-based fragmentation (GEBF) approach to molecular crystals under periodic boundary conditions (PBC), and we demonstrate the performance of the method for a variety of molecular crystals. With this approach, the lattice energy of a molecular crystal can be obtained from the energies of a series of embedded subsystems, which can be computed with existing advanced molecular quantum chemistry methods. The use of the field compensation method allows the method to take long-range electrostatic interaction of the infinite crystal environment into account and make the method almost translationally invariant. The computational cost of the present method scales linearly with the number of molecules in the unit cell. Illustrative applications demonstrate that the PBC-GEBF method with explicitly correlated quantum chemistry methods is capable of providing accurate descriptions on the lattice energies and structures for various types of molecular crystals. In addition, this approach can be employed to quantify the contributions of various intermolecular interactions to the theoretical lattice energy. Such qualitative understanding is very useful for rational design of molecular crystals. PMID:26574207

  18. Development and validation of a stability indicating RP-HPLC method for the simultaneous determination of related substances of albuterol sulfate and ipratropium bromide in nasal solution.

    PubMed

    Kasawar, Gajanan B; Farooqui, Mazahar

    2010-05-01

    A simple, sensitive and specific RP-HPLC method was developed for the quantification of related impurities of albuterol sulfate (AS) and ipratropium bromide (IB) in liquid pharmaceutical dosage form. The chromatographic separation employs gradient elution using an inertsil C8-3, 250mmx4.6mm, 5mum columns. Mobile phase consisting of solvent A (solution containing 2.5g of potassium dihydrogen phosphate and 2.87g of heptane-1-sulfonic acid sodium salt per liter of water, adjusted to pH 4 with orthophosphoric acid) and solvent B (acetonitrile) delivered at a flow rate of 1.0mlmin(-1). The analytes were detected and quantified at 210nm using photodiode array (PDA) detector. The method was validated as per ICH guidelines, demonstrating to be accurate and precise (repeatability and intermediate precision level) within the corresponding linear range of known impurities of AS and IB. The specificity of the method was investigated under different stress conditions including hydrolytic, oxidative, photolytic and thermal as recommended by ICH guidelines. Relevant degradation was found to take place under hydrolytic and oxidative conditions. Robustness against small modification in pH, column oven temperature, flow rate and percentage of the mobile phase composition was ascertained. Lower limit of quantification and detection were also determined. The peak purity indices (purity anglemethod. PMID:20045275

  19. Development of an HPLC-UV Method for the Analysis of Drugs Used for Combined Hypertension Therapy in Pharmaceutical Preparations and Human Plasma

    PubMed Central

    2013-01-01

    A simple, rapid, and selective HPLC-UV method was developed for the determination of antihypertensive drug substances: amlodipine besilat (AML), olmesartan medoxomil (OLM), valsartan (VAL), and hydrochlorothiazide (HCT) in pharmaceuticals and plasma. These substances are mostly used as combinations. The combinations are found in various forms, especially in current pharmaceuticals as threesome components: OLM, AML, and HCT (combination I) and AML, VAL, and HCT (combination II). The separation was achieved by using an RP-CN column, and acetonitrile-methanol-10 mmol orthophosphoric acid pH 2.5 (7 : 13 : 80, v/v/v) was used as a mobile phase; the detector wavelength was set at 235 nm. The linear ranges were found as 0.1–18.5 μg/mL, 0.4–25.6 μg/mL, 0.3–15.5 μg/mL, and 0.3–22 μg/mL for AML, OLM, VAL, and HCT, respectively. In order to check the selectivity of the method for pharmaceutical preparations, forced degradation studies were carried out. According to the validation studies, the developed method was found to be reproducible and accurate as shown by RSD ≤6.1%, 5.7%, 6.9%, and 4.6% and relative mean error (RME) ≤10.6%, 5.8%, 6.5%, and 6.8% for AML, OLM, VAL, and HCT, respectively. Consequently, the method was applied to the analysis of tablets and plasma of the patients using drugs including those substances. PMID:23634320

  20. Development of an HPLC-UV Method for the Analysis of Drugs Used for Combined Hypertension Therapy in Pharmaceutical Preparations and Human Plasma.

    PubMed

    Kepekci Tekkeli, Serife Evrim

    2013-01-01

    A simple, rapid, and selective HPLC-UV method was developed for the determination of antihypertensive drug substances: amlodipine besilat (AML), olmesartan medoxomil (OLM), valsartan (VAL), and hydrochlorothiazide (HCT) in pharmaceuticals and plasma. These substances are mostly used as combinations. The combinations are found in various forms, especially in current pharmaceuticals as threesome components: OLM, AML, and HCT (combination I) and AML, VAL, and HCT (combination II). The separation was achieved by using an RP-CN column, and acetonitrile-methanol-10 mmol orthophosphoric acid pH 2.5 (7 : 13 : 80, v/v/v) was used as a mobile phase; the detector wavelength was set at 235 nm. The linear ranges were found as 0.1-18.5  μ g/mL, 0.4-25.6  μ g/mL, 0.3-15.5  μ g/mL, and 0.3-22  μ g/mL for AML, OLM, VAL, and HCT, respectively. In order to check the selectivity of the method for pharmaceutical preparations, forced degradation studies were carried out. According to the validation studies, the developed method was found to be reproducible and accurate as shown by RSD ≤6.1%, 5.7%, 6.9%, and 4.6% and relative mean error (RME) ≤10.6%, 5.8%, 6.5%, and 6.8% for AML, OLM, VAL, and HCT, respectively. Consequently, the method was applied to the analysis of tablets and plasma of the patients using drugs including those substances. PMID:23634320

  1. HPLC: Early and Recent Perspectives.

    ERIC Educational Resources Information Center

    Karger, Barry L.

    1997-01-01

    Provides a perspective on what it was like in the early days of high-performance liquid chromatography (HPLC) and several of the key developments. Focuses on the advances in HPLC generally, and more specifically for the biological sciences, that were necessary for the method to reach the preeminent stage of today. Contains 20 references. (JRH)

  2. A validated RP-HPLC method for quantitative determination of related impurities of ursodeoxycholic acid (API) by refractive index detection.

    PubMed

    Peepliwal, Ashok; Bonde, C G; Bothara, K G

    2011-03-25

    An isocratic RP-HPLC method was developed and validated for quantitative determination of ursodeoxycholic acid (UDCA) and its related impurities. Considering the lower molecular absorptivity of UDCA, refractive index detector was used to detect the impurities on a Phenomenex Luna C(18), 150 mm × 4.6 mm, 5 μm column. The mobile phase was 0.1% acetic acid/methanol (30:70, v/v) and flow rate was 0.8 ml/min. The detector and column temperature was maintained at 40°C. The method is linear over a range of 0.25-3.5 μg/ml for all impurities and coefficient of correlation (r(2)) was ≥0.9945. The accuracy of method demonstrated at three levels in the range of 50-150% of the specification limit and recoveries were found to be in the range of 97.11-100.75%. The precision for all related impurities was below 3.5% R.S.D. The method was applied to commercial bulk drug sample for assay purpose. PMID:21095088

  3. Development of an HPLC Method with an ODS Column to Determine Low Levels of Aspartame Diastereomers in Aspartame.

    PubMed

    Ohtsuki, Takashi; Nakamura, Ryoichiro; Kubo, Satoru; Otabe, Akira; Oobayashi, Yoko; Suzuki, Shoko; Yoshida, Mika; Yoshida, Mitsuya; Tatebe, Chiye; Sato, Kyoko; Akiyama, Hiroshi

    2016-01-01

    α-L-Aspartyl-D-phenylalanine methyl ester (L, D-APM) and α-D-aspartyl-L-phenylalanine methyl ester (D, L-APM) are diastereomers of aspartame (N-L-α-Aspartyl-L-phenylalanine-1-methyl ester, L, L-APM). The Joint FAO/WHO Expert Committee on Food Additives has set 0.04 wt% as the maximum permitted level of the sum of L, D-APM and D, L-APM in commercially available L, L-APM. In this study, we developed and validated a simple high-performance liquid chromatography (HPLC) method using an ODS column to determine L, D-APM and D, L-APM in L, L-APM. The limits of detection and quantification, respectively, of L, D-APM and D, L-APM were found to be 0.0012 wt% and 0.004 wt%. This method gave excellent accuracy, repeatability, and reproducibility in a recovery test performed on five different days. Moreover, the method was successfully applied to the determination of these diastereomers in commercial L, L-APM samples. Thus, the developed method is a simple, useful, and practical tool for determining L, D-APM and D, L-APM levels in L, L-APM. PMID:27015640

  4. Stability-Indicating RP-HPLC Method for Simultaneous Estimation of Enrofloxacin and Its Degradation Products in Tablet Dosage Forms.

    PubMed

    Chakravarthy, V Ashok; Sailaja, B B V; Kumar, Avvaru Praveen

    2015-01-01

    The present work was the development of a simple, efficient, and reproducible stability-indicating reverse-phase high performance liquid chromatographic (RP-HPLC) method for simultaneous determination enrofloxacin (EFX) and its degradation products including ethylenediamine impurity, desfluoro impurity, ciprofloxacin impurity, chloro impurity, fluoroquinolonic acid impurity, and decarboxylated impurity in tablet dosage forms. The separation of EFX and its degradation products in tablets was carried out on Kromasil C-18 (250 × 4.6 mm, 5 μm) column using 0.1% (v/v) TEA in 10 mM KH2PO4 (pH 2.5) buffer and methanol by linear gradient program. Flow rate was 1.0 mL min(-1) with a column temperature of 35°C and detection wavelength was carried out at 278 nm and 254 nm. The forced degradation studies were performed on EFX tablets under acidic, basic, oxidation, thermal, humidity, and photolytic conditions. The degraded products were well resolved from the main active drug and also from known impurities within 65 minutes. The method was validated in terms of specificity, linearity, LOD, LOQ, accuracy, precision, and robustness as per ICH guidelines. The results obtained from the validation experiments prove that the developed method is a stability-indicating method and suitable for routine analysis. PMID:25705547

  5. Development of an HPLC Method with an ODS Column to Determine Low Levels of Aspartame Diastereomers in Aspartame

    PubMed Central

    Ohtsuki, Takashi; Nakamura, Ryoichiro; Kubo, Satoru; Otabe, Akira; Oobayashi, Yoko; Suzuki, Shoko; Yoshida, Mika; Yoshida, Mitsuya; Tatebe, Chiye; Sato, Kyoko; Akiyama, Hiroshi

    2016-01-01

    α-L-Aspartyl-D-phenylalanine methyl ester (L, D-APM) and α-D-aspartyl-L-phenylalanine methyl ester (D, L-APM) are diastereomers of aspartame (N-L-α-Aspartyl-L-phenylalanine-1-methyl ester, L, L-APM). The Joint FAO/WHO Expert Committee on Food Additives has set 0.04 wt% as the maximum permitted level of the sum of L, D-APM and D, L-APM in commercially available L, L-APM. In this study, we developed and validated a simple high-performance liquid chromatography (HPLC) method using an ODS column to determine L, D-APM and D, L-APM in L, L-APM. The limits of detection and quantification, respectively, of L, D-APM and D, L-APM were found to be 0.0012 wt% and 0.004 wt%. This method gave excellent accuracy, repeatability, and reproducibility in a recovery test performed on five different days. Moreover, the method was successfully applied to the determination of these diastereomers in commercial L, L-APM samples. Thus, the developed method is a simple, useful, and practical tool for determining L, D-APM and D, L-APM levels in L, L-APM. PMID:27015640

  6. ANALYSIS OF VITAMIN E BY HPLC

    Technology Transfer Automated Retrieval System (TEKTRAN)

    HPLC (High-performance liquid chromatography) is the most comon technique for identifying and measuring vitamin E concentrations. A variety of good HPLC methods are available for vitamin E analysis. Reliable and sensitive methods have been developed using reversed-phased and normal-phase HPLC column...

  7. Parente2: a fast and accurate method for detecting identity by descent

    PubMed Central

    Rodriguez, Jesse M.; Bercovici, Sivan; Huang, Lin; Frostig, Roy; Batzoglou, Serafim

    2015-01-01

    Identity-by-descent (IBD) inference is the problem of establishing a genetic connection between two individuals through a genomic segment that is inherited by both individuals from a recent common ancestor. IBD inference is an important preceding step in a variety of population genomic studies, ranging from demographic studies to linking genomic variation with phenotype and disease. The problem of accurate IBD detection has become increasingly challenging with the availability of large collections of human genotypes and genomes: Given a cohort’s size, a quadratic number of pairwise genome comparisons must be performed. Therefore, computation time and the false discovery rate can also scale quadratically. To enable accurate and efficient large-scale IBD detection, we present Parente2, a novel method for detecting IBD segments. Parente2 is based on an embedded log-likelihood ratio and uses a model that accounts for linkage disequilibrium by explicitly modeling haplotype frequencies. Parente2 operates directly on genotype data without the need to phase data prior to IBD inference. We evaluate Parente2’s performance through extensive simulations using real data, and we show that it provides substantially higher accuracy compared to previous state-of-the-art methods while maintaining high computational efficiency. PMID:25273070

  8. An adaptive, formally second order accurate version of the immersed boundary method

    NASA Astrophysics Data System (ADS)

    Griffith, Boyce E.; Hornung, Richard D.; McQueen, David M.; Peskin, Charles S.

    2007-04-01

    Like many problems in biofluid mechanics, cardiac mechanics can be modeled as the dynamic interaction of a viscous incompressible fluid (the blood) and a (visco-)elastic structure (the muscular walls and the valves of the heart). The immersed boundary method is a mathematical formulation and numerical approach to such problems that was originally introduced to study blood flow through heart valves, and extensions of this work have yielded a three-dimensional model of the heart and great vessels. In the present work, we introduce a new adaptive version of the immersed boundary method. This adaptive scheme employs the same hierarchical structured grid approach (but a different numerical scheme) as the two-dimensional adaptive immersed boundary method of Roma et al. [A multilevel self adaptive version of the immersed boundary method, Ph.D. Thesis, Courant Institute of Mathematical Sciences, New York University, 1996; An adaptive version of the immersed boundary method, J. Comput. Phys. 153 (2) (1999) 509-534] and is based on a formally second order accurate (i.e., second order accurate for problems with sufficiently smooth solutions) version of the immersed boundary method that we have recently described [B.E. Griffith, C.S. Peskin, On the order of accuracy of the immersed boundary method: higher order convergence rates for sufficiently smooth problems, J. Comput. Phys. 208 (1) (2005) 75-105]. Actual second order convergence rates are obtained for both the uniform and adaptive methods by considering the interaction of a viscous incompressible flow and an anisotropic incompressible viscoelastic shell. We also present initial results from the application of this methodology to the three-dimensional simulation of blood flow in the heart and great vessels. The results obtained by the adaptive method show good qualitative agreement with simulation results obtained by earlier non-adaptive versions of the method, but the flow in the vicinity of the model heart valves

  9. Generalized weighted ratio method for accurate turbidity measurement over a wide range.

    PubMed

    Liu, Hongbo; Yang, Ping; Song, Hong; Guo, Yilu; Zhan, Shuyue; Huang, Hui; Wang, Hangzhou; Tao, Bangyi; Mu, Quanquan; Xu, Jing; Li, Dejun; Chen, Ying

    2015-12-14

    Turbidity measurement is important for water quality assessment, food safety, medicine, ocean monitoring, etc. In this paper, a method that accurately estimates the turbidity over a wide range is proposed, where the turbidity of the sample is represented as a weighted ratio of the scattered light intensities at a series of angles. An improvement in the accuracy is achieved by expanding the structure of the ratio function, thus adding more flexibility to the turbidity-intensity fitting. Experiments have been carried out with an 850 nm laser and a power meter fixed on a turntable to measure the light intensity at different angles. The results show that the relative estimation error of the proposed method is 0.58% on average for a four-angle intensity combination for all test samples with a turbidity ranging from 160 NTU to 4000 NTU. PMID:26699060

  10. Accurate calculation of Coulomb sums: Efficacy of Pade-like methods

    SciTech Connect

    Sarkar, B. ); Bhattacharyya, K. )

    1993-09-01

    The adequacy of numerical sequence accelerative transforms in providing accurate estimates of Coulomb sums is considered, referring particularly to distorted lattices. Performance of diagonal Pade approximants (DPA) in this context is critically assessed. Failure in the case of lattice vacancies is also demonstrated. The method of multiple-point Pade approximants (MPA) has been introduced for slowly convergent sequences and is shown to work well for both regular and distorted lattices, the latter being due either to impurities or vacancies. Viability of the two methods is also compared. In divergent situations with distortions owing to vacancies, a strategy of obtaining reliable results by separate applications of both DPA and MPA at appropriate places is also sketched. Representative calculations involve two basic cubic-lattice sums, one slowly convergent and the other divergent, from which very good quality estimates of Madelung constants for a number of common lattices follow.

  11. Accurate and rapid optical characterization of an anisotropic guided structure based on a neural method.

    PubMed

    Robert, Stéphane; Battie, Yann; Jamon, Damien; Royer, Francois

    2007-04-10

    Optimal performances of integrated optical devices are obtained by the use of an accurate and reliable characterization method. The parameters of interest, i.e., optical indices and thickness of the waveguide structure, are calculated from effective indices by means of an inversion procedure. We demonstrate how an artificial neural network can achieve such a process. The artificial neural network used is a multilayer perceptron. The first result concerns a simulated anisotropic waveguide. The accuracy in the determination of optical indices and waveguide thickness is 5 x 10(-5) and 4 nm, respectively. Then an experimental application on a silica-titania thin film is performed. In addition, effective indices are measured by m-lines spectroscopy. Finally, a comparison with a classical optimization algorithm demonstrates the robustness of the neural method. PMID:17384718

  12. RAId_DbS: Method for Peptide ID using Database Search with Accurate Statistics

    NASA Astrophysics Data System (ADS)

    Alves, Gelio; Ogurtsov, Aleksey; Yu, Yi-Kuo

    2007-03-01

    The key to proteomics studies, essential in systems biology, is peptide identification. Under tandem mass spectrometry, each spectrum generated consists of a list of mass/charge peaks along with their intensities. Software analysis is then required to identify from the spectrum peptide candidates that best interpret the spectrum. The library search, which compares the spectral peaks against theoretical peaks generated by each peptide in a library, is among the most popular methods. This method, although robust, lacks good quantitative statistical underpinning. As we show, many library search algorithms suffer from statistical instability. The need for a better statistical basis prompted us to develop RAId_DbS. Taking into account the skewness in the peak intensity distribution while scoring peptides, RAId_DbS provides an accurate statistical significance assignment to each peptide candidate. RAId_DbS will be a valuable tool especially when one intends to identify proteins through peptide identifications.

  13. A Fully Implicit Time Accurate Method for Hypersonic Combustion: Application to Shock-induced Combustion Instability

    NASA Technical Reports Server (NTRS)

    Yungster, Shaye; Radhakrishnan, Krishnan

    1994-01-01

    A new fully implicit, time accurate algorithm suitable for chemically reacting, viscous flows in the transonic-to-hypersonic regime is described. The method is based on a class of Total Variation Diminishing (TVD) schemes and uses successive Gauss-Siedel relaxation sweeps. The inversion of large matrices is avoided by partitioning the system into reacting and nonreacting parts, but still maintaining a fully coupled interaction. As a result, the matrices that have to be inverted are of the same size as those obtained with the commonly used point implicit methods. In this paper we illustrate the applicability of the new algorithm to hypervelocity unsteady combustion applications. We present a series of numerical simulations of the periodic combustion instabilities observed in ballistic-range experiments of blunt projectiles flying at subdetonative speeds through hydrogen-air mixtures. The computed frequencies of oscillation are in excellent agreement with experimental data.

  14. Chemometrics-Assisted UV Spectrophotometric and RP-HPLC Methods for the Simultaneous Determination of Tolperisone Hydrochloride and Diclofenac Sodium in their Combined Pharmaceutical Formulation

    PubMed Central

    Gohel, Nikunj Rameshbhai; Patel, Bhavin Kiritbhai; Parmar, Vijaykumar Kunvarji

    2013-01-01

    Chemometrics-assisted UV spectrophotometric and RP-HPLC methods are presented for the simultaneous determination of tolperisone hydrochloride (TOL) and diclofenac sodium (DIC) from their combined pharmaceutical dosage form. Chemometric methods are based on principal component regression and partial least-square regression models. Two sets of standard mixtures, calibration sets, and validation sets were prepared. Both models were optimized to quantify each drug in the mixture using the information included in the UV absorption spectra of the appropriate solution in the range 241–290 nm with the intervals λ = 1 nm at 50 wavelengths. The optimized models were successfully applied to the simultaneous determination of these drugs in synthetic mixture and pharmaceutical formulation. In addition, an HPLC method was developed using a reversed-phase C18 column at ambient temperature with a mobile phase consisting of methanol:acetonitrile:water (60:30:10 v/v/v), pH-adjusted to 3.0, with UV detection at 275 nm. The methods were validated in terms of linearity, accuracy, precision, sensitivity, specificity, and robustness in the range of 3–30 μg/mL for TOL and 1–10 μg/mL for DIC. The robustness of the HPLC method was tested using an experimental design approach. The developed HPLC method, and the PCR and PLS models were used to determine the amount of TOL and DIC in tablets. The data obtained from the PCR and PLS models were not significantly different from those obtained from the HPLC method at 95% confidence limit. PMID:24482768

  15. Spectroscopic Method for Fast and Accurate Group A Streptococcus Bacteria Detection.

    PubMed

    Schiff, Dillon; Aviv, Hagit; Rosenbaum, Efraim; Tischler, Yaakov R

    2016-02-16

    Rapid and accurate detection of pathogens is paramount to human health. Spectroscopic techniques have been shown to be viable methods for detecting various pathogens. Enhanced methods of Raman spectroscopy can discriminate unique bacterial signatures; however, many of these require precise conditions and do not have in vivo replicability. Common biological detection methods such as rapid antigen detection tests have high specificity but do not have high sensitivity. Here we developed a new method of bacteria detection that is both highly specific and highly sensitive by combining the specificity of antibody staining and the sensitivity of spectroscopic characterization. Bacteria samples, treated with a fluorescent antibody complex specific to Streptococcus pyogenes, were volumetrically normalized according to their Raman bacterial signal intensity and characterized for fluorescence, eliciting a positive result for samples containing Streptococcus pyogenes and a negative result for those without. The normalized fluorescence intensity of the Streptococcus pyogenes gave a signal that is up to 16.4 times higher than that of other bacteria samples for bacteria stained in solution and up to 12.7 times higher in solid state. This method can be very easily replicated for other bacteria species using suitable antibody-dye complexes. In addition, this method shows viability for in vivo detection as it requires minute amounts of bacteria, low laser excitation power, and short integration times in order to achieve high signal. PMID:26752013

  16. Highly accurate retrieval method of Japanese document images through a combination of morphological analysis and OCR

    NASA Astrophysics Data System (ADS)

    Katsuyama, Yutaka; Takebe, Hiroaki; Kurokawa, Koji; Saitoh, Takahiro; Naoi, Satoshi

    2001-12-01

    We have developed a method that allows Japanese document images to be retrieved more accurately by using OCR character candidate information and a conventional plain text search engine. In this method, the document image is first recognized by normal OCR to produce text. Keyword areas are then estimated from the normal OCR produced text through morphological analysis. A lattice of candidate- character codes is extracted from these areas, and then character strings are extracted from the lattice using a word-matching method in noun areas and a K-th DP-matching method in undefined word areas. Finally, these extracted character strings are added to the normal OCR produced text to improve document retrieval accuracy when u sing a conventional plain text search engine. Experimental results from searches of 49 OHP sheet images revealed that our method has a high recall rate of 98.2%, compared to 90.3% with a conventional method using only normal OCR produced text, while requiring about the same processing time as normal OCR.

  17. A simple HPLC method for the comprehensive analysis of cis/trans (Z/E) geometrical isomers of carotenoids for nutritional studies

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Geometrical isomers of carotenoids behave differently in aspects like stability towards oxidants, bioavailability, vitamin A activity and specificity for enzymes. The availability of HPLC methods for their detailed profiling is therefore advisable to expand our knowledge on their metabolism and biol...

  18. A stability-Indicating HPLC Method for Simultaneous Determination of Creatine Phosphate Sodium and its Related Substances in Pharmaceutical Formulation.

    PubMed

    Xie, Zengkun; Wei, Lihua; Yang, Qin; Yang, Min; Pan, Hongchun; Liu, Hong

    2016-01-01

    The objective of the study was to develop a simple, specific and stability-indicating HPLC method for the simultaneous determination of creatine phosphate sodium (CPS) and its related substances in pharmaceutical formulation. Separation of creatine phosphate sodium from its major process impurities and degradation products was achieved on a Hypersil BDS C18 column (250 × 4.6 mm, 5 μm) with an aqueous mobile phase containing 0.2% (w/v) tetrabutylammonium hydroxide (TAH) and 0.2% (w/v) monopotassium phosphate adjusted to pH 6.6 with orthophosphoric acid at a flow rate of 1.0 mL min(-1). The analytes were detected at 210 nm. Different chromatographic parameters were carefully optimized. The relative response factors for creatine, creatinine and creatinine phosphate disodium salt relative to CPS were determined. The method has been validated with respect to solution stability, system suitability, LOD, LOQ, linearity, accuracy, precision, specificity and robustness. The validation criteria were met in all cases. The developed method was successfully applied to determine the purity of CPS in pharmaceutical formulation. PMID:27610152

  19. Simultaneous Determination of Tetracyclines Residues in Bovine Milk Samples by Solid Phase Extraction and HPLC-FL Method

    PubMed Central

    Mesgari Abbasi, Mehran; Babaei, Hossein; Ansarin, Masoud; Nourdadgar, Ashraf-o-sadat; Nemati, Mahboob

    2011-01-01

    Introduction: Tetracyclines (TCs) are widely used in animal husbandry and their residues in milk may resultin harmful effects on human. The aim of this study was to investigate the presence of TCs residues in various bovine milk samples from local markets of Ardabil, Iran. Methods: One hundred and fourteen pasteurized, sterilized and raw milk samples were collected from markets of Ardabil. Tetracycline, Oxytetracycline and Chlortetracycline (TCs) residues extraction carried out by Solid Phase Extraction method. Determination of TCs residues were performed by high performance liquid chromatography (HPLC) method using Fluorescence detector. Results: The mean of total TCs residues in all samples (114 samples) was 97.6 ±16.9ng/g and that of pasteurized, sterilized and raw milk samples were 87.1 ± 17.7, 112.0 ± 57.3 and 154.0 ± 66.3ng/g respectively. Twenty five point four percent of the all samples, and 24.4%, 30% and 28.6% of the pasteurized, sterilized and raw milk samples, respectively had higher TCs residues than the recommended maximum levels (100ng/g). Conclusion: This study indicates the presence of tetracycline residues more than allowed amount. Regulatory authorities should ensure proper withdrawal period before milking the animals and definite supervisions are necessary on application of these drugs. PMID:24312754

  20. An HPLC-MS/MS method for the separation of α-retinyl esters from retinyl esters.

    PubMed

    Goetz, Hilary J; Kopec, Rachel E; Riedl, Ken M; Cooperstone, Jessica L; Narayanasamy, Sureshbabu; Curley, Robert W; Schwartz, Steven J

    2016-09-01

    Enzymatic cleavage of the nonsymmetric provitamin A carotenoid α-carotene results in one molecule of retinal (vitamin A), and one molecule of α-retinal, a biologically inactive analog of true vitamin A. Due to structural similarities, α-retinyl esters and vitamin A esters typically coelute, resulting in the overestimation of vitamin A originating from α-carotene. Herein, we present a set of tools to identify and separate α-retinol products from vitamin A. α-Retinyl palmitate (αRP) standard was synthesized from α-ionone following a Wittig-Horner approach. A high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method employing a C30 column was then developed to separate the species. Authentic standards of retinyl esters and the synthesized α-RP confirmed respective identities, while other α-retinyl esters (i.e. myristate, linoleate, oleate, and stearate) were evidenced by their pseudomolecular ions observed in electrospray ionization (ESI) mode, fragmentation, and elution order. For quantitation, an atmospheric pressure chemical ionization (APCI) source operated in positive ion mode was used, and retinol, the predominant in-source parent ion was selected and fragmented. The application of this method to a chylomicron-rich fraction of human plasma is demonstrated. This method can be used to better determine the quantity of vitamin A derived from foods containing α-carotene. PMID:27423669

  1. Validated HPLC-UV method for determination of naproxen in human plasma with proven selectivity against ibuprofen and paracetamol.

    PubMed

    Filist, Monika; Szlaska, Iwona; Kaza, Michał; Pawiński, Tomasz

    2016-06-01

    Estimating the influence of interfering compounds present in the biological matrix on the determination of an analyte is one of the most important tasks during bioanalytical method development and validation. Interferences from endogenous components and, if necessary, from major metabolites as well as possible co-administered medications should be evaluated during a selectivity test. This paper describes a simple, rapid and cost-effective HPLC-UV method for the determination of naproxen in human plasma in the presence of two other analgesics, ibuprofen and paracetamol. Sample preparation is based on a simple liquid-liquid extraction procedure with a short, 5 s mixing time. Fenoprofen, which is characterized by a similar structure and properties to naproxen, was first used as the internal standard. The calibration curve is linear in the concentration range of 0.5-80.0 µg/mL, which is suitable for pharmacokinetic studies following a single 220 mg oral dose of naproxen sodium. The method was fully validated according to international guidelines and was successfully applied in a bioequivalence study in humans. Copyright © 2015 John Wiley & Sons, Ltd. PMID:26458096

  2. A Validated RP HPLC-PAD Method for the Determination of Hederacoside C in Ivy-Thyme Cough Syrup.

    PubMed

    Khdair, Ayman; Mohammad, Mohammad K; Tawaha, Khaled; Al-Hamarsheh, Eman; Alkhatib, Hatim S; Al-Khalidi, Bashar; Bustanji, Yasser; Najjar, Samer; Hudaib, Mohammad

    2010-01-01

    A simple reversed phase high-performance liquid chromatographic (RP-HPLC) method coupled with a photodiode array detector (PAD) has been developed and validated for the analysis of hederacoside C, the marker of ivy plant, in Ivy-Thyme cough syrup. Separation of hederacoside C was achieved using a Phenomenex-Gemini C18 column isothermally at 40°C. A mobile phase system constituted of solvent A (water: acetonitrile: orthophosphoric acid (85%), 860 : 140 : 2 v/v) and solvent B (acetonitrile: orthophosphoric acid (85%), 998 : 2 v/v) was used, at gradient conditions, at a flow rate of 1.5 mL/min. Analysis was performed using UV-detection (205 nm). The method was linear over the range (0.03-0.15) mg/mL of hederacoside C (r = 0.9992). Repeatability and intermediate precision were acceptable (RSD <2%). Limits of detection (LOD) and quantitation (LOQ) were 0.011 and 0.032 mg/mL, respectively. Percentage recovery was found to lie between 99.69% and 100.90% (RSD <2%). The method was also proved to be specific (peak-purity coefficient = 0.996). PMID:20862201

  3. Dual Wavelength RP-HPLC Method for Simultaneous Determination of Two Antispasmodic Drugs: An Application in Pharmaceutical and Human Serum

    PubMed Central

    Hasan, Najmul; Chaiharn, Mathurot; Khan, Sauleha; Khalid, Hira; Sher, Nawab; Siddiqui, Farhan Ahmed; Siddiqui, Muhammad Zain

    2013-01-01

    A reverse phase stability indicating HPLC method for simultaneous determination of two antispasmodic drugs in pharmaceutical parenteral dosage forms (injectable) and in serum has been developed and validated. Mobile phase ingredients consist of Acetonitrile : buffer : sulfuric acid 0.1 M (50 : 50 : 0.3 v/v/v), at flow rate 1.0 mL/min using a Hibar μBondapak ODS C18 column monitored at dual wavelength of 266 nm and 205 nm for phloroglucinol and trimethylphloroglucinol, respectively. The drugs were subjected to stress conditions of hydrolysis (oxidation, base, acid, and thermal degradation). Oxidation degraded the molecule drastically while there was not so much significant effect of other stress conditions. The calibration curve was linear with a correlation coefficient of 0.9999 and 0.9992 for PG and TMP, respectively. The drug recoveries fall in the range of 98.56% and 101.24% with 10 pg/mL and 33 pg/mL limit of detection and limit of quantification for both phloroglucinol and trimethylphloroglucinol. The method was validated in accordance with ICH guidelines and was applied successfully to quantify the amount of trimethylphloroglucinol and phloroglucinol in bulk, injectable form and physiological fluid. Forced degradation studies proved the stability indicating abilities of the method. PMID:24286017

  4. Stability indicating HPLC-UV method for detection of curcumin in Curcuma longa extract and emulsion formulation.

    PubMed

    Syed, Haroon Khalid; Liew, Kai Bin; Loh, Gabriel Onn Kit; Peh, Kok Khiang

    2015-03-01

    A stability-indicating HPLC-UV method for the determination of curcumin in Curcuma longa extract and emulsion was developed. The system suitability parameters, theoretical plates (N), tailing factor (T), capacity factor (K'), height equivalent of a theoretical plate (H) and resolution (Rs) were calculated. Stress degradation studies (acid, base, oxidation, heat and UV light) of curcumin were performed in emulsion. It was found that N>6500, T<1.1, K' was 2.68-3.75, HETP about 37 and Rs was 1.8. The method was linear from 2 to 200 μg/mL with a correlation coefficient of 0.9998. The intra-day precision and accuracy for curcumin were ⩽0.87% and ⩽2.0%, while the inter-day precision and accuracy values were ⩽2.1% and ⩽-1.92. Curcumin degraded in emulsion under acid, alkali and UV light. In conclusion, the stability-indicating method could be employed to determine curcumin in bulk and emulsions. PMID:25306352

  5. Dual Wavelength RP-HPLC Method for Simultaneous Determination of Two Antispasmodic Drugs: An Application in Pharmaceutical and Human Serum.

    PubMed

    Hasan, Najmul; Chaiharn, Mathurot; Khan, Sauleha; Khalid, Hira; Sher, Nawab; Siddiqui, Farhan Ahmed; Siddiqui, Muhammad Zain

    2013-01-01

    A reverse phase stability indicating HPLC method for simultaneous determination of two antispasmodic drugs in pharmaceutical parenteral dosage forms (injectable) and in serum has been developed and validated. Mobile phase ingredients consist of Acetonitrile : buffer : sulfuric acid 0.1 M (50 : 50 : 0.3 v/v/v), at flow rate 1.0 mL/min using a Hibar μ Bondapak ODS C18 column monitored at dual wavelength of 266 nm and 205 nm for phloroglucinol and trimethylphloroglucinol, respectively. The drugs were subjected to stress conditions of hydrolysis (oxidation, base, acid, and thermal degradation). Oxidation degraded the molecule drastically while there was not so much significant effect of other stress conditions. The calibration curve was linear with a correlation coefficient of 0.9999 and 0.9992 for PG and TMP, respectively. The drug recoveries fall in the range of 98.56% and 101.24% with 10 pg/mL and 33 pg/mL limit of detection and limit of quantification for both phloroglucinol and trimethylphloroglucinol. The method was validated in accordance with ICH guidelines and was applied successfully to quantify the amount of trimethylphloroglucinol and phloroglucinol in bulk, injectable form and physiological fluid. Forced degradation studies proved the stability indicating abilities of the method. PMID:24286017

  6. Optimisation of an HPLC method for the simultaneous quantification of the major sugars and organic acids in grapevine berries.

    PubMed

    Eyéghé-Bickong, Hans A; Alexandersson, Erik O; Gouws, Liezel M; Young, Philip R; Vivier, Melané A

    2012-02-15

    A high performance liquid chromatographic method was developed to profile major sugars and organic acids in grapevine berries. Sugars and organic acids in grapevine berries were extracted by chloroform/polyvinylpolypyrrolidone purification. The extracts were chromatographed on an Aminex HPX-87H ion-exchange HPLC column with 5mM sulphuric acid as mobile phase. Chromatography was visualised via a diode array detector combined with a refractive index detector. The analysis was calibrated using external standard calibration and a novel equation was used to calculate the concentrations of malic acid and fructose from unresolved separation. For the method to be utilised for analysing a large numbers of berry samples, each sample was directly injected after sample extraction and the extraction step was downscaled to allow the use of small amounts of sample material. The concentrations of sugars and organic acids in grapevine berry samples were normalised to the internal standard concentrations obtained after extraction of an internal standard mixture. The analysis method exhibits a good precision and a high analyte recovery from samples spiked with the standard mixture and is suitable for the profiling of major sugars and organic acids in grapevine berry samples at different stages of berry development. This is the first report on the combined profiling of the major sugars and organic acids in grapevine berries using milligram amounts of plant material with direct injection after sample extraction. PMID:22265666

  7. A stability-Indicating HPLC Method for Simultaneous Determination of Creatine Phosphate Sodium and its Related Substances in Pharmaceutical Formulation

    PubMed Central

    Xie, Zengkun; Wei, Lihua; Yang, Qin; Yang, Min; Pan, Hongchun; Liu, Hong

    2016-01-01

    The objective of the study was to develop a simple, specific and stability-indicating HPLC method for the simultaneous determination of creatine phosphate sodium (CPS) and its related substances in pharmaceutical formulation. Separation of creatine phosphate sodium from its major process impurities and degradation products was achieved on a Hypersil BDS C18 column (250 × 4.6 mm, 5 μm) with an aqueous mobile phase containing 0.2% (w/v) tetrabutylammonium hydroxide (TAH) and 0.2% (w/v) monopotassium phosphate adjusted to pH 6.6 with orthophosphoric acid at a flow rate of 1.0 mL min-1. The analytes were detected at 210 nm. Different chromatographic parameters were carefully optimized. The relative response factors for creatine, creatinine and creatinine phosphate disodium salt relative to CPS were determined. The method has been validated with respect to solution stability, system suitability, LOD, LOQ, linearity, accuracy, precision, specificity and robustness. The validation criteria were met in all cases. The developed method was successfully applied to determine the purity of CPS in pharmaceutical formulation. PMID:27610152

  8. Simultaneous quantitative determination of nine active chemical compositions in traditional Chinese medicine Glycyrrhiza by RP-HPLC with full-time five-wavelength fusion method.

    PubMed

    Wu, Yin-Ping; Meng, Xian-Sheng; Bao, Yong-Rui; Wang, Shuai; Kang, Ting-Guo

    2013-01-01

    A new, simple, accurate and reliable full-time five-wavelength fusion method for the simultaneous separation and determination of nine active chemical compositions (liquiritin apioside, liquiritin, isoliquiritin apioside, ononin, isoliquiritin, liquiritigenin, calycosin, isoliquiritigenin, Glycyrrhizic acid monoammonium salt) in traditional Chinese medicine Glycyrrhiza was developed using reverse phase high-performance liquid chromatography (RP-HPLC) coupled with a diode-array detector (DAD). The chromatographic separation was performed on an Agilent TC-C18 column with gradient elution using 0.04% methanoic acid (A) and acetonitrile (B) at a flow rate of 1.0 mL min(-1) and UV detection at 248 nm, 250 nm, 276 nm, 362 nm, 370 nm. The standard curves were linear over the range of 2.1379-12.8272 μg for liquiritin apioside, 3.9299-23.5794 μg for liquiritin, 1.0432-6.2592 μg for isoliquiritin apioside, 0.8764-5.8584 μg for ononin, 1.0701-6.4205 μg for isoliquiritin, 1.3685-8.2111 μg for liquiritigenin, 0.3927-2.3563 μg for calycosin, 0.2498- 1.4986 μg for isoliquiritigenin, 2.0094-12.0564 μg for Glycyrrhizic acid monoammonium salt, respectively (r(2) > 0.9997). The recoveries and relative standard deviation (RSD) varied from 95.09% to 103.54% and 1.09% to 2.36%, respectively. The precision for all the analytes was less than 2.52%. The method indicated good performance in terms of precision, accuracy and linearity. The method enabled the simultaneous determination of nine active chemical compositions for quality control of Glycyrrhiza. PMID:23336517

  9. [A New Method of Accurately Extracting Spectral Values for Discrete Sampling Points].

    PubMed

    Lü, Zhen-zhen; Liu, Guang-ming; Yang, Jin-song

    2015-08-01

    In the establishment of remote sensing information inversion model, the actual measured data of discrete sampling points and the corresponding spectrum data to pixels of remote sensing image, are used to establish the relation, thus to realize the goal of information retrieval. Accurate extraction of spectrum value is very important to establish the remote sensing inversion mode. Converting target spot layer to ROI (region of interest) and then saving the ROI as ASCII is one of the methods that researchers often used to extract the spectral values. Analyzing the coordinate and spectrum values extracted using original coordinate in ENVI, we found that the extracted and original coordinate were not inconsistent and part of spectrum values not belong to the pixel containing the sampling point. The inversion model based on the above information cannot really reflect relationship between the target properties and spectral values; so that the model is meaningless. We equally divided the pixel into four parts and summed up the law. It was found that only when the sampling points distributed in the upper left corner of pixels, the extracted values were correct. On the basis of the above methods, this paper systematically studied the principle of extraction target coordinate and spectral values, and summarized the rule. A new method for extracting spectral parameters of the pixel that sampling point located in the environment of ENVI software. Firstly, pixel sampling point coordinates for any of the four corner points were extracted by the sample points with original coordinate in ENVI. Secondly, the sampling points were judged in which partition of pixel by comparing the absolute values of difference longitude and latitude of the original and extraction coordinates. Lastly, all points were adjusted to the upper left corner of pixels by symmetry principle and spectrum values were extracted by the same way in the first step. The results indicated that the extracted spectrum

  10. Genotypic variation in wheat grain fructan content revealed by a simplified HPLC method

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Fructans are regarded as prebiotics, with potentially beneficial effects on human health. This study aimed to examine genetic variation in wheat grain fructan content using an improved analytical method. The method involves extracting fructans from wheat grain followed by enzymatic hydrolysis to bre...

  11. A simplified HPLC method for determination of tryptophan in some cereals and legumes.

    PubMed

    Çevikkalp, Senem A; Löker, Gül B; Yaman, Mustafa; Amoutzopoulos, Birdem

    2016-02-15

    In the present study, a simple analytical method is proposed for determining tryptophan, and method is validated on some cereal and legume samples. In the method alkaline hydrolysis of proteins was used due to the destruction of tryptophan structure during acid hydrolysis. Following alkaline hydrolysis (120°C for 12h), hydrolysates are filtered through ashless filter paper and pH values are adjusted with hydrochloric acid solution. Separation and detection of tryptophan are performed on a reversed-phase column with fluorescence detection within 10min by using a mobile phase of acetonitrile and acetate buffer of pH 6.3 (1:9, v/v). For determination of tryptophan content, the procedure described in the study offers an alternative analysis method by enabling high speed analysis and the use of simple extraction process to the other available methods. PMID:26433283

  12. An accurate clone-based haplotyping method by overlapping pool sequencing.

    PubMed

    Li, Cheng; Cao, Changchang; Tu, Jing; Sun, Xiao

    2016-07-01

    Chromosome-long haplotyping of human genomes is important to identify genetic variants with differing gene expression, in human evolution studies, clinical diagnosis, and other biological and medical fields. Although several methods have realized haplotyping based on sequencing technologies or population statistics, accuracy and cost are factors that prohibit their wide use. Borrowing ideas from group testing theories, we proposed a clone-based haplotyping method by overlapping pool sequencing. The clones from a single individual were pooled combinatorially and then sequenced. According to the distinct pooling pattern for each clone in the overlapping pool sequencing, alleles for the recovered variants could be assigned to their original clones precisely. Subsequently, the clone sequences could be reconstructed by linking these alleles accordingly and assembling them into haplotypes with high accuracy. To verify the utility of our method, we constructed 130 110 clones in silico for the individual NA12878 and simulated the pooling and sequencing process. Ultimately, 99.9% of variants on chromosome 1 that were covered by clones from both parental chromosomes were recovered correctly, and 112 haplotype contigs were assembled with an N50 length of 3.4 Mb and no switch errors. A comparison with current clone-based haplotyping methods indicated our method was more accurate. PMID:27095193

  13. Efficient and accurate numerical methods for the Klein-Gordon-Schroedinger equations

    SciTech Connect

    Bao, Weizhu . E-mail: bao@math.nus.edu.sg; Yang, Li . E-mail: yangli@nus.edu.sg

    2007-08-10

    In this paper, we present efficient, unconditionally stable and accurate numerical methods for approximations of the Klein-Gordon-Schroedinger (KGS) equations with/without damping terms. The key features of our methods are based on: (i) the application of a time-splitting spectral discretization for a Schroedinger-type equation in KGS (ii) the utilization of Fourier pseudospectral discretization for spatial derivatives in the Klein-Gordon equation in KGS (iii) the adoption of solving the ordinary differential equations (ODEs) in phase space analytically under appropriate chosen transmission conditions between different time intervals or applying Crank-Nicolson/leap-frog for linear/nonlinear terms for time derivatives. The numerical methods are either explicit or implicit but can be solved explicitly, unconditionally stable, and of spectral accuracy in space and second-order accuracy in time. Moreover, they are time reversible and time transverse invariant when there is no damping terms in KGS, conserve (or keep the same decay rate of) the wave energy as that in KGS without (or with a linear) damping term, keep the same dynamics of the mean value of the meson field, and give exact results for the plane-wave solution. Extensive numerical tests are presented to confirm the above properties of our numerical methods for KGS. Finally, the methods are applied to study solitary-wave collisions in one dimension (1D), as well as dynamics of a 2D problem in KGS.

  14. An accurate clone-based haplotyping method by overlapping pool sequencing

    PubMed Central

    Li, Cheng; Cao, Changchang; Tu, Jing; Sun, Xiao

    2016-01-01

    Chromosome-long haplotyping of human genomes is important to identify genetic variants with differing gene expression, in human evolution studies, clinical diagnosis, and other biological and medical fields. Although several methods have realized haplotyping based on sequencing technologies or population statistics, accuracy and cost are factors that prohibit their wide use. Borrowing ideas from group testing theories, we proposed a clone-based haplotyping method by overlapping pool sequencing. The clones from a single individual were pooled combinatorially and then sequenced. According to the distinct pooling pattern for each clone in the overlapping pool sequencing, alleles for the recovered variants could be assigned to their original clones precisely. Subsequently, the clone sequences could be reconstructed by linking these alleles accordingly and assembling them into haplotypes with high accuracy. To verify the utility of our method, we constructed 130 110 clones in silico for the individual NA12878 and simulated the pooling and sequencing process. Ultimately, 99.9% of variants on chromosome 1 that were covered by clones from both parental chromosomes were recovered correctly, and 112 haplotype contigs were assembled with an N50 length of 3.4 Mb and no switch errors. A comparison with current clone-based haplotyping methods indicated our method was more accurate. PMID:27095193

  15. A highly accurate method for the determination of mass and center of mass of a spacecraft

    NASA Technical Reports Server (NTRS)

    Chow, E. Y.; Trubert, M. R.; Egwuatu, A.

    1978-01-01

    An extremely accurate method for the measurement of mass and the lateral center of mass of a spacecraft has been developed. The method was needed for the Voyager spacecraft mission requirement which limited the uncertainty in the knowledge of lateral center of mass of the spacecraft system weighing 750 kg to be less than 1.0 mm (0.04 in.). The method consists of using three load cells symmetrically located at 120 deg apart on a turntable with respect to the vertical axis of the spacecraft and making six measurements for each load cell. These six measurements are taken by cyclic rotations of the load cell turntable and of the spacecraft, about the vertical axis of the measurement fixture. This method eliminates all alignment, leveling, and load cell calibration errors for the lateral center of mass determination, and permits a statistical best fit of the measurement data. An associated data reduction computer program called MASCM has been written to implement this method and has been used for the Voyager spacecraft.

  16. Accurate and automatic extrinsic calibration method for blade measurement system integrated by different optical sensors

    NASA Astrophysics Data System (ADS)

    He, Wantao; Li, Zhongwei; Zhong, Kai; Shi, Yusheng; Zhao, Can; Cheng, Xu

    2014-11-01

    Fast and precise 3D inspection system is in great demand in modern manufacturing processes. At present, the available sensors have their own pros and cons, and hardly exist an omnipotent sensor to handle the complex inspection task in an accurate and effective way. The prevailing solution is integrating multiple sensors and taking advantages of their strengths. For obtaining a holistic 3D profile, the data from different sensors should be registrated into a coherent coordinate system. However, some complex shape objects own thin wall feather such as blades, the ICP registration method would become unstable. Therefore, it is very important to calibrate the extrinsic parameters of each sensor in the integrated measurement system. This paper proposed an accurate and automatic extrinsic parameter calibration method for blade measurement system integrated by different optical sensors. In this system, fringe projection sensor (FPS) and conoscopic holography sensor (CHS) is integrated into a multi-axis motion platform, and the sensors can be optimally move to any desired position at the object's surface. In order to simple the calibration process, a special calibration artifact is designed according to the characteristics of the two sensors. An automatic registration procedure based on correlation and segmentation is used to realize the artifact datasets obtaining by FPS and CHS rough alignment without any manual operation and data pro-processing, and then the Generalized Gauss-Markoff model is used to estimate the optimization transformation parameters. The experiments show the measurement result of a blade, where several sampled patches are merged into one point cloud, and it verifies the performance of the proposed method.

  17. A Method for Accurate in silico modeling of Ultrasound Transducer Arrays

    PubMed Central

    Guenther, Drake A.; Walker, William F.

    2009-01-01

    This paper presents a new approach to improve the in silico modeling of ultrasound transducer arrays. While current simulation tools accurately predict the theoretical element spatio-temporal pressure response, transducers do not always behave as theorized. In practice, using the probe's physical dimensions and published specifications in silico, often results in unsatisfactory agreement between simulation and experiment. We describe a general optimization procedure used to maximize the correlation between the observed and simulated spatio-temporal response of a pulsed single element in a commercial ultrasound probe. A linear systems approach is employed to model element angular sensitivity, lens effects, and diffraction phenomena. A numerical deconvolution method is described to characterize the intrinsic electro-mechanical impulse response of the element. Once the response of the element and optimal element characteristics are known, prediction of the pressure response for arbitrary apertures and excitation signals is performed through direct convolution using available tools. We achieve a correlation of 0.846 between the experimental emitted waveform and simulated waveform when using the probe's physical specifications in silico. A far superior correlation of 0.988 is achieved when using the optimized in silico model. Electronic noise appears to be the main effect preventing the realization of higher correlation coefficients. More accurate in silico modeling will improve the evaluation and design of ultrasound transducers as well as aid in the development of sophisticated beamforming strategies. PMID:19041997

  18. A rapid and sensitive method for HPLC cholesterol determination in bile.

    PubMed

    Bocos, C; Castro, M; Orozco, E; Contreras, J A; Herrera, E

    1992-09-01

    A relatively little time consuming simple method based on the treatment of bile with cholesterol oxidase and subsequent high performance liquid chromatography measurement of the 3-ketocholesterol produced in order to determine the level of the cholesterol concentration is described. The method avoids bilirubin interferences, has high reproducibility and recovery assays give 100% values. It is highly sensitive and suitable for use in the determination of cholesterol concentrations in bile and other bilirubin containing biological fluids. PMID:1301638

  19. Assessment of cosmetic ingredients in the in vitro reconstructed human epidermis test method EpiSkin™ using HPLC/UPLC-spectrophotometry in the MTT-reduction assay.

    PubMed

    Alépée, N; Hibatallah, J; Klaric, M; Mewes, K R; Pfannenbecker, U; McNamee, P

    2016-06-01

    Cosmetics Europe recently established HPLC/UPLC-spectrophotometry as a suitable alternative endpoint detection system for measurement of formazan in the MTT-reduction assay of reconstructed human tissue test methods irrespective of the test system involved. This addressed a known limitation for such test methods that use optical density for measurement of formazan and may be incompatible for evaluation of strong MTT reducer and/or coloured chemicals. To build on the original project, Cosmetics Europe has undertaken a second study that focuses on evaluation of chemicals with functionalities relevant to cosmetic products. Such chemicals were primarily identified from the Scientific Committee on Consumer Safety (SCCS) 2010 memorandum (addendum) on the in vitro test EpiSkin™ for skin irritation testing. Fifty test items were evaluated in which both standard photometry and HPLC/UPLC-spectrophotometry were used for endpoint detection. The results obtained in this study: 1) provide further support for Within Laboratory Reproducibility of HPLC-UPLC-spectrophotometry for measurement of formazan; 2) demonstrate, through use a case study with Basazol C Blue pr. 8056, that HPLC/UPLC-spectrophotometry enables determination of an in vitro classification even when this is not possible using standard photometry and 3) addresses the question raised by SCCS in their 2010 memorandum (addendum) to consider an endpoint detection system not involving optical density quantification in in vitro reconstructed human epidermis skin irritation test methods. PMID:26891813

  20. Spectrophotometric and HPLC Methods for Simultaneous Estimation of Amlodipine Besilate, Losartan Potassium and Hydrochlorothiazide in Tablets

    PubMed Central

    Wankhede, S. B.; Raka, K. C.; Wadkar, S. B.; Chitlange, S. S.

    2010-01-01

    Two UV-spectrophotometric and one reverse phase high performance liquid chromatography methods have been developed for the simultaneous estimation of amlodipine besilate, losartan potassium and hydrochlorothiazide in tablet dosage form. The first UV spectrophotometric method was a determination using the simultaneous equation method at 236.5, 254 and 271 nm over the concentration range 5-25, 10-50 and 5-25 μg/ml for amlodipine besilate, losartan potassium and hydrochlorothiazide, respectively. The second UV method was a determination using the area under curve method at 231.5-241.5, 249-259 and 266-276 nm over the concentration range of 5-25, 5-25 and 10-50 μg/ml for amlodipine besilate, hydrochlorothiazide and losartan potassium, respectively. In reverse phase high performance liquid chromatography analysis is carried out using 0.025 M phosphate buffer (pH 3.7):acetonitrile (57:43 v/v) as the mobile phase and Kromasil C18 (4.6 mm i.d×250 mm) column as stationery phase with detection wavelength of 232 nm linearity was obtained in the concentration range of 2-14, 20-140 and 5-40 μg/ml for amlodipine besilate, losartan potassium and hydrochlorothiazide, respectively. Both UV-spectrophotometric and reverse phase high performance liquid chromatography methods were statistically validated and can be used for analysis of combined dose tablet formulation containing amlodipine besilate, losartan potassium and hydrochlorothiazide. PMID:20582208

  1. A reversed-phase HPLC method for measurement of 5-hydroxymethyl furfuraldehyde and furfuraldehyde in processed juices.

    PubMed

    Roig, M G; Bello, J F; Kennedy, J F; Rivera, Z S; Lloyd, L L

    1992-01-01

    An HPLC method using a reversed-phase macroreticular PLRP-S column and phosphate buffer as eluent is described for the analysis of L-ascorbic acid degradation products, 5-hydroxymethyl furfuraldehyde and furfuraldehyde, in processed fruit juices. Measurement of the levels of 5-HMF and furfuraldehyde in citrus juices against time showed the presence of 5-HMF (0.45 mg l-1) even at zero time. An assessment on the effect of the additives on the formation of 5-HMF of reconstituted single-strength orange juice showed virtually the same results for all the samples stored at 4 degrees C and 20 degrees C, irrespective of the additive. For citrus juice samples which had been subjected to accelerated degradation, those that showed the highest decomposition of L-ascorbic acid, produced the highest level of 5-HMF. The presence of furfuraldehyde in any of the samples was not detected, probably due to the fact that furfuraldehyde was formed in such small amounts which are below the minimum detectability limit of the method (0.050 mg l-1). PMID:1369241

  2. Validation of a HPLC method for the measurement of erythrocyte encapsulated thymidine phosphorylase (EE-TP) activity.

    PubMed

    Fairbanks, Lynette D; Levene, Michelle; Bax, Bridget E

    2013-03-25

    A sensitive and simple reverse-phase high performance liquid chromatographic (HPLC) assay has been validated for the determination of thymine as a measure of thymidine phosphorylase activity encapsulated in erythrocytes (EE-TP), a formulation which is under clinical development as an enzyme replacement therapy for the treatment of mitochondrial neurogastrointestinal encephalomyopathy (MNGIE). Diluted erythrocyte lysates were incubated in 100mM sodium phosphate buffer and 10mM thymidine at 37°C for 10min and the reaction stopped with 40% trichloroacetic acid. Following centrifugation, the supernatant was washed with water saturated diethyl ether, and injected onto a Spherisorb C(18) column (125mm×4.6mm, 5μm), with a mobile phase (40mM ammonium acetate, 5mM tetrabutyl ammonium hydrogen sulphate, pH 2.70) delivered at a flow rate of 1.0ml/min and run time of 8min. Ultraviolet detection (UV) was employed at 254nm. The method was linear in the range of 5-500nmol/ml (r(2)=0.992), specific with intra- and inter-day precisions of <9.6 and accuracies within ±20%. Limits of detection and quantification were 1.2nmol/ml and 10nmol/ml, respectively. The method was applied to quantify thymidine phosphorylase activity in samples of in-process controls and batches of EE-TP manufactured for clinical use. PMID:23291437

  3. Stability-Indicating RP-HPLC Method for the Simultaneous Estimation of Doxofylline and Terbutalinesulphate in Pharmaceutical Formulations

    PubMed Central

    Samanthula, Gananadhamu; Yadiki, Krishnaveni; Saladi, Shantikumar; Gutala, Sreekanth; Surendranath, K. V.

    2013-01-01

    An isocratic, stability-indicating, reversed-phase high-performance liquid chromatography (RP-HPLC) method was developed for the quantitative determination of doxofylline and terbutaline sulphate, used for the treatment of respiratory problems. The chromatographic separation was achieved on a Zorbax-SB Phenyl 250 × 4.6mm × 5 μm column with the mobile phase consisting of a mixture of 25 mM ammonium acetate (pH 5.0) : acetonitrile (85:15 %v/v) at a flow rate of 1.0 ml/min. The eluate was monitored at 274 nm using a PDA detector. Forced degradation studies were performed on the bulk sample of doxofylline and terbutaline sulphate using acid (0.1N HCl), base (0.1N NaOH), oxidation (10% hydrogen peroxide), photolytic, and thermal degradation conditions. Good resolution was observed between the degradants and analytes. Degradation products resulting from the stress studies did not interfere with the detection of doxofylline and terbutaline sulphate, thus the assay is stability-indicating. The method has the requisite accuracy, selectivity, sensitivity, and precision for the simultaneous estimation of doxofylline and terbutaline sulphate in bulk and pharmaceutical dosage forms. The limit of quantitation and limit of detection were found to be 1.16 μg/ml and 0.38 μg/ml for doxofylline, 2.08 μg/ml and 0.62 μg/ml for terbutaline sulphate, respectively. PMID:24482767

  4. Stability-Indicating RP-HPLC Method for the Simultaneous Estimation of Doxofylline and Terbutalinesulphate in Pharmaceutical Formulations.

    PubMed

    Samanthula, Gananadhamu; Yadiki, Krishnaveni; Saladi, Shantikumar; Gutala, Sreekanth; Surendranath, K V

    2013-12-01

    An isocratic, stability-indicating, reversed-phase high-performance liquid chromatography (RP-HPLC) method was developed for the quantitative determination of doxofylline and terbutaline sulphate, used for the treatment of respiratory problems. The chromatographic separation was achieved on a Zorbax-SB Phenyl 250 × 4.6mm × 5 μm column with the mobile phase consisting of a mixture of 25 mM ammonium acetate (pH 5.0) : acetonitrile (85:15 %v/v) at a flow rate of 1.0 ml/min. The eluate was monitored at 274 nm using a PDA detector. Forced degradation studies were performed on the bulk sample of doxofylline and terbutaline sulphate using acid (0.1N HCl), base (0.1N NaOH), oxidation (10% hydrogen peroxide), photolytic, and thermal degradation conditions. Good resolution was observed between the degradants and analytes. Degradation products resulting from the stress studies did not interfere with the detection of doxofylline and terbutaline sulphate, thus the assay is stability-indicating. The method has the requisite accuracy, selectivity, sensitivity, and precision for the simultaneous estimation of doxofylline and terbutaline sulphate in bulk and pharmaceutical dosage forms. The limit of quantitation and limit of detection were found to be 1.16 μg/ml and 0.38 μg/ml for doxofylline, 2.08 μg/ml and 0.62 μg/ml for terbutaline sulphate, respectively. PMID:24482767

  5. Analytical method of measuring tea catechins in human plasma by solid-phase extraction and HPLC with electrochemical detection.

    PubMed

    Umegaki, K; Sugisawa, A; Yamada, K; Higuchi, M

    2001-12-01

    We developed an analytical method for measuring tea catechins in plasma by solid-phase extraction (SPE), followed by HPLC with a coulometric electrochemical detector. The plasma was mixed with an equal volume of acetonitrile to precipitate protein, and catechins in the resulting supernatant were extracted by SPE, using a C18 cartridge. To correct the extraction efficiency, ethyl gallate was simultaneously added with acetonitrile as an internal standard. Plasma samples were treated in microtubes, and evaporation and SPE were performed by the use of a vacuum centrifuge and vacuum manifold for SPE. The use of these instruments allowed the handling of a large number of samples simultaneously. In this method, (-)-epicatechin (EC), (-)-epicatechin-3-O-gallate (ECg), (-)-epigallocatechin (EGC), (-)-epigallocatechin-3-O-gallate (EGCg), and ethyl gallate could be detected as a single peak with high sensitivity. For an analysis of the conjugated form of catechins, plasma samples were treated with glucuronidase and sulfatase. Type H-2 beta-glucuronidase effectively digested the conjugated forms, and the enzyme also converted EGCg and ECg to their nongallated form. When the concentrations of catechins in plasma were analyzed in subjects who took a single dose of catechin liquid, the concentration of free EGCg in plasma reached a maximum of 300 nM at 1 h after intake; those of the other free form of catechins increased only slightly after the intake. The concentration of total catechins (free+conjugated forms) in plasma increased up to 2 h after the intake. PMID:11922115

  6. Validating a Stability Indicating HPLC Method for Kinetic Study of Cetirizine Degradation in Acidic and Oxidative Conditions

    PubMed Central

    Souri, Effat; Hatami, Ali; Shabani Ravari, Nazanin; Alvandifar, Farhad; Barazandeh Tehrani, Maliheh

    2013-01-01

    A stability indicating High-Performance Liquid Chromatography (HPLC) method was validated and used to study the degradation of cetirizine dihydrochloride in acidic and oxidative conditions. The separation was carried out on a Symmetry C18 column and a mixture of 50 mM KH2PO4 and acetonitrile (60:40 v/v, pH = 3.5) was used as the mobile phase. The method was linear over the range of 1-20 μg/mL of cetirizine dihydrochloride (r2 > 0.999) and the within-day and between-day precision values were less than 1.5%. The results showed that cetirizine dihydrochloride was unstable in 2 M HCl and 0.5% H2O2. The kinetics of the acidic degradation showed a pseudo-first-order reaction in the temperature range of 70-90°C. In addition, the kinetics of hydrogen peroxide mediated degradation was pseudo-first-order in the temperature range of 50-80°C. PMID:24250602

  7. Direct injection method for HPLC/MS/MS analysis of acrylamide in aqueous solutions: application to adsorption experiments.

    PubMed

    Mnif, Ines; Hurel, Charlotte; Marmier, Nicolas

    2015-05-01

    Polyacrylamides are polymers used in many fields and represent the main source of release of the highly toxic acrylamide in the environment. In this work, a simple, rapid, and sensitive analytical method was developed with HPLC/MS/MS and direct injection for acrylamide analysis in water and adsorption samples. AFNOR standards NF T90-210 and NF T90-220 were used for the analytical method validation and uncertainty estimation. Limit of quantification (LOQ) for acrylamide was 1 μg/L, and accuracy was checked at three acrylamide levels (1, 6, and 10 μg/L). Uncertainties were estimated at 34.2, 22, and 12.4 % for acrylamide concentrations at LOQ, 6 μg/L, and 10 μg/L, respectively. Acrylamide adsorption on clays (kaolinite, illite) and sludge was then studied as a function of pH, time, and acrylamide concentrations. Acrylamide adsorption on kaolinite, illite, and sludge was found to be very weak since adsorption percentages were inferior to 10 %, whatever the pH value and the initial acrylamide concentration. The low affinity of acrylamide for clays and sludge is likely due to its hydrophilic property, small size, and charge neutrality. PMID:25388555

  8. Development of an analytical method for antimony speciation in vegetables by HPLC-hydride generation-atomic fluorescence spectrometry.

    PubMed

    Olivares, David; Bravo, Manuel; Feldmann, Jorg; Raab, Andrea; Neaman, Alexander; Quiroz, Waldo

    2012-01-01

    A new method for antimony speciation in terrestrial edible vegetables (spinach, onions, and carrots) was developed using HPLC with hydride generation-atomic fluorescence spectrometry. Mechanical agitation and ultrasound were tested as extraction techniques. Different extraction reagents were evaluated and optimal conditions were determined using experimental design methodology, where EDTA (10 mmol/L, pH 2.5) was selected because this chelate solution produced the highest extraction yield and exhibited the best compatibility with the mobile phase. The results demonstrated that EDTA prevents oxidation of Sb(III) to Sb(V) and maintains the stability of antimony species during the entire analytical process. The LOD and precision (RSD values obtained) for Sb(V), Sb(III), and trimethyl Sb(V) were 0.08, 0.07, and 0.9 microg/L and 5.0, 5.2, and 4.7%, respectively, for a 100 microL sample volume. The application of this method to real samples allowed extraction of 50% of total antimony content from spinach, while antimony extracted from carrots and onion samples ranged between 50 and 60 and 54 and 70%, respectively. Only Sb(V) was detected in three roots (onion and spinach) that represented 60-70% of the total antimony in the extracts. PMID:22970588

  9. A Validated HPLC Method for Zanamivir and its Application to In vitro Permeability Study in Caco-2 Culture Model.

    PubMed

    Boonyapiwat, B; Sarisuta, N; Ma, Y; Steventon, G B

    2011-09-01

    A simple HPLC method was developed and validated for the quantification of zanamivir in permeability studies using Caco-2 cell culture model. Chromatographic resolution was achieved using 98% (v/v) ultrapure water and 2% (v/v) acetonitrile as mobile phase with flow rate of 0.5 ml/min on a BDS Hypersil Cyano column (length 250 mm; internal diameter 4.6 mm; particle size 5 μm) and UV detection at 230 nm. The method was linear for the quantification of zanamivir at concentration ranging from 0.1-10 μg/ml with coefficient of determination greater than 0.999. The recovery of zanamivir was in the range of 99.76-105.08%. The relative standard deviations of the within-day precision and between-day precision were lower than 10.32 and 14.33%, respectively. The permeability of zanamivir was independent of the transport direction and zanamivir concentrations, indicating a passive transport of zanamivir across Caco-2 cells. With the absence of Ca(2+) in transport medium, the permeability values of zanamivir increased 56.21 and 57.20 fold in the directions of apical to basolateral and basolateral to apical, respectively. On the basis of these results, zanamivir was found to be predominantly transported across Caco-2 monolayers via the passive paracellular pathway. PMID:22923870

  10. Development and Validation of HPLC Method for the Simultaneous Determination of Five Food Additives and Caffeine in Soft Drinks

    PubMed Central

    Aşçı, Bürge; Dinç Zor, Şule; Aksu Dönmez, Özlem

    2016-01-01

    Box-Behnken design was applied to optimize high performance liquid chromatography (HPLC) conditions for the simultaneous determination of potassium sorbate, sodium benzoate, carmoisine, allura red, ponceau 4R, and caffeine in commercial soft drinks. The experimental variables chosen were pH (6.0–7.0), flow rate (1.0–1.4 mL/min), and mobile phase ratio (85–95% acetate buffer). Resolution values of all peak pairs were used as a response. Stationary phase was Inertsil OctaDecylSilane- (ODS-) 3V reverse phase column (250 × 4.6 mm, 5 μm) dimensions. The detection was performed at 230 nm. Optimal values were found 6.0 pH, 1.0 mL/min flow rate, and 95% mobile phase ratio for the method which was validated by calculating the linearity (r2 > 0.9962), accuracy (recoveries ≥ 95.75%), precision (intraday variation ≤ 1.923%, interday variation ≤ 1.950%), limits of detection (LODs), and limits of quantification (LOQs) parameters. LODs and LOQs for analytes were in the range of 0.10–0.19 μg/mL and 0.33–0.63 μg/mL, respectively. The proposed method was applied successfully for the simultaneous determination of the mixtures of five food additives and caffeine in soft drinks. PMID:26989415

  11. Development and Validation of HPLC Method for the Simultaneous Determination of Five Food Additives and Caffeine in Soft Drinks.

    PubMed

    Aşçı, Bürge; Dinç Zor, Şule; Aksu Dönmez, Özlem

    2016-01-01

    Box-Behnken design was applied to optimize high performance liquid chromatography (HPLC) conditions for the simultaneous determination of potassium sorbate, sodium benzoate, carmoisine, allura red, ponceau 4R, and caffeine in commercial soft drinks. The experimental variables chosen were pH (6.0-7.0), flow rate (1.0-1.4 mL/min), and mobile phase ratio (85-95% acetate buffer). Resolution values of all peak pairs were used as a response. Stationary phase was Inertsil OctaDecylSilane- (ODS-) 3V reverse phase column (250 × 4.6 mm, 5 μm) dimensions. The detection was performed at 230 nm. Optimal values were found 6.0 pH, 1.0 mL/min flow rate, and 95% mobile phase ratio for the method which was validated by calculating the linearity (r (2) > 0.9962), accuracy (recoveries ≥ 95.75%), precision (intraday variation ≤ 1.923%, interday variation ≤ 1.950%), limits of detection (LODs), and limits of quantification (LOQs) parameters. LODs and LOQs for analytes were in the range of 0.10-0.19 μg/mL and 0.33-0.63 μg/mL, respectively. The proposed method was applied successfully for the simultaneous determination of the mixtures of five food additives and caffeine in soft drinks. PMID:26989415

  12. HPLC-MS/MS method validation for the detection of carbadox and olaquindox in poultry and swine feedingstuffs.

    PubMed

    Souza Dibai, Wagner Lutero; de Alkimin Filho, Juarez Fabiano; da Silva Oliveira, Fabiano Aurélio; Sampaio de Assis, Débora Cristina; Camargos Lara, Leonardo José; de Figueiredo, Tadeu Chaves; de Vasconcelos Cançado, Silvana

    2015-11-01

    Carbadox (CBX) and olaquindox (OLA) were used in poultry and swine feed for growth promotion, to improve feed efficiency and increase the rate of weight gain. However, the use of these agents in feedingstuffs was prohibited because of concerns about their toxicity. Regulatory laboratories are required to have suitably validated analytical methods to ensure compliance with the ban. A quantitative and confirmatory method for determining the presence of CBX and OLA in poultry and swine feed by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was developed, optimized, and validated. The analytes extraction was performed with a mixture of water and acetonitrile (1:1v/v) and cleanup with hexane and C18 (dispersive phase). The method was evaluated by the following parameters: specificity, linearity, matrix effect, decision limits (CCα), detection capability (CCβ), accuracy, precision, limits of detection (LoD), limits of quantification (LoQ) and measurement uncertainty. The validated method presented a broad linear study range and no significant matrix effect. The limit of detection (LoD) was defined at 9 μg kg(-1) for CBX and 80 μg kg(-1) for OLA, and the limit of quantification (LoQ) was defined at 12 μg kg(-1) and 110 μg kg(-1) for CBX and OLA, respectively. The accuracy of the method was adequate for CBX and OLA. The recovery values found in the repeatability conditions were 99.41% for CBX and 104.62% for OLA. Under intralaboratory reproducibility conditions, the values were 98.63% for CBX and 95.07% for OLA. It was concluded that the performance parameters demonstrated total method adequacy for the detection and quantification of CBX and OLA in poultry and swine feedingstuffs. PMID:26452885

  13. Development of validated stability indicating assay method for simultaneous estimation of metformin hydrochloride and vildagliptin by RP-HPLC.

    PubMed

    Satheeshkumar, N; Pradeepkumar, M; Shanthikumar, S; Rao, V J

    2014-03-01

    A simple, precise and stability-indicating HPLC method was developed and validated for the simultaneous determination of metformin hydrochloride (MET) and vildagliptin (VLG) in pharmaceutical dosage forms. The method involves use of easily available inexpensive laboratory reagents. The separation was achieved on Grace Cyano column (250 mm×4.6 mm) 5 µm with isocratic flow. The mobile phase was pumped at a flow rate of 1.0 mL/min, consisted of 25 mM ammonium bicarbonate buffer and acetonitrile (65:35, v/v). The UV detection was carried out at 207 nm. A linear response was observed over the concentration range of 25-125 µg/mL for MET and 50-250 µg/mL for VLG respectively. Limit of detection and limit of quantification for MET were 0.36 µg/mL and 1.22 µg/mL, and for VLG were 0.75 µg/mL and 2.51 µg/mL respectively. The method was successfully validated in accordance to ICH guidelines acceptance criteria for specificity, linearity, accuracy, precision, robustness, and system suitability. Individual drugs (MET and VLG) were exposed to thermal, photolytic, hydrolytic and oxidative stress conditions. The resultant stressed samples were analyzed by the proposed method. The method gave high resolution among the degradation products and the analytes. The peak purity of analyte peak in the stressed samples was confirmed by photo diode array detector. The proposed method was successfully applied for the quantitative analysis of MET and VLG in tablet dosage form, which will help to improve quality control and contribute to stability studies of pharmaceutical tablets containing these drugs. PMID:24081820

  14. Development and validation of an HPLC-MS/MS method to determine clopidogrel in human plasma.

    PubMed

    Liu, Gangyi; Dong, Chunxia; Shen, Weiwei; Lu, Xiaopei; Zhang, Mengqi; Gui, Yuzhou; Zhou, Qinyi; Yu, Chen

    2016-01-01

    A quantitative method for clopidogrel using online-SPE tandem LC-MS/MS was developed and fully validated according to the well-established FDA guidelines. The method achieves adequate sensitivity for pharmacokinetic studies, with lower limit of quantifications (LLOQs) as low as 10 pg/mL. Chromatographic separations were performed on reversed phase columns Kromasil Eternity-2.5-C18-UHPLC for both methods. Positive electrospray ionization in multiple reaction monitoring (MRM) mode was employed for signal detection and a deuterated analogue (clopidogrel-d 4) was used as internal standard (IS). Adjustments in sample preparation, including introduction of an online-SPE system proved to be the most effective method to solve the analyte back-conversion in clinical samples. Pooled clinical samples (two levels) were prepared and successfully used as real-sample quality control (QC) in the validation of back-conversion testing under different conditions. The result showed that the real samples were stable in room temperature for 24 h. Linearity, precision, extraction recovery, matrix effect on spiked QC samples and stability tests on both spiked QCs and real sample QCs stored in different conditions met the acceptance criteria. This online-SPE method was successfully applied to a bioequivalence study of 75 mg single dose clopidogrel tablets in 48 healthy male subjects. PMID:26904399

  15. Aeroacoustic Flow Phenomena Accurately Captured by New Computational Fluid Dynamics Method

    NASA Technical Reports Server (NTRS)

    Blech, Richard A.

    2002-01-01

    One of the challenges in the computational fluid dynamics area is the accurate calculation of aeroacoustic phenomena, especially in the presence of shock waves. One such phenomenon is "transonic resonance," where an unsteady shock wave at the throat of a convergent-divergent nozzle results in the emission of acoustic tones. The space-time Conservation-Element and Solution-Element (CE/SE) method developed at the NASA Glenn Research Center can faithfully capture the shock waves, their unsteady motion, and the generated acoustic tones. The CE/SE method is a revolutionary new approach to the numerical modeling of physical phenomena where features with steep gradients (e.g., shock waves, phase transition, etc.) must coexist with those having weaker variations. The CE/SE method does not require the complex interpolation procedures (that allow for the possibility of a shock between grid cells) used by many other methods to transfer information between grid cells. These interpolation procedures can add too much numerical dissipation to the solution process. Thus, while shocks are resolved, weaker waves, such as acoustic waves, are washed out.

  16. A more accurate method for measurement of tuberculocidal activity of disinfectants.

    PubMed Central

    Ascenzi, J M; Ezzell, R J; Wendt, T M

    1987-01-01

    The current Association of Official Analytical Chemists method for testing tuberculocidal activity of disinfectants has been shown to be inaccurate and to have a high degree of variability. An alternate test method is proposed which is more accurate, more precise, and quantitative. A suspension of Mycobacterium bovis BCG was exposed to a variety of disinfectant chemicals and a kill curve was constructed from quantitative data. Data are presented that show the discrepancy between current claims, determined by the Association of Official Analytical Chemists method, of selected commercially available products and claims generated by the proposed method. The effects of different recovery media were examined. The data indicated that Mycobacteria 7H11 and Middlebrook 7H10 agars were equal in recovery of the different chemically treated cells, with Lowenstein-Jensen agar having approximately the same recovery rate but requiring incubation for up to 3 weeks longer for countability. The kill curves generated for several different chemicals were reproducible, as indicated by the standard deviations of the slopes and intercepts of the linear regression curves. PMID:3314707

  17. HPLC-MS/MS Method for the Measurement of Insecticide Degradates in Baby Food

    PubMed Central

    2015-01-01

    A solid phase extraction method was developed to isolate four insecticide degradates from baby food that were measured subsequently using high-performance liquid chromatography–tandem mass spectrometry. The degradates [parent insecticide] measured were malathion dicarboxylic acid [malathion], 3,5,6-trichloro-2-pyridinol [chlorpyrifos, chlorpyrifos methyl] (TCPy), cis/trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane-1-carboxylic acid [permethrin, cypermethrin, cyfluthrin], and 3-phenoxybenzoic acid [general pyrethroid]. All degradates produced recoveries between 80 and 120% except TCPy in fruit (122% recovery), and all relative standard deviations were <16%. Use of this method demonstrated that insecticide degradates were found in baby foods frequently purchased in the United States, supporting the need for this method. These data will assist in differentiating whether biomarker levels of insecticide metabolites are the result of exposures to the toxic insecticide or its preformed degradate. PMID:24910900

  18. Numerical system utilising a Monte Carlo calculation method for accurate dose assessment in radiation accidents.

    PubMed

    Takahashi, F; Endo, A

    2007-01-01

    A system utilising radiation transport codes has been developed to derive accurate dose distributions in a human body for radiological accidents. A suitable model is quite essential for a numerical analysis. Therefore, two tools were developed to setup a 'problem-dependent' input file, defining a radiation source and an exposed person to simulate the radiation transport in an accident with the Monte Carlo calculation codes-MCNP and MCNPX. Necessary resources are defined by a dialogue method with a generally used personal computer for both the tools. The tools prepare human body and source models described in the input file format of the employed Monte Carlo codes. The tools were validated for dose assessment in comparison with a past criticality accident and a hypothesized exposure. PMID:17510203

  19. Temperature dependent effective potential method for accurate free energy calculations of solids

    NASA Astrophysics Data System (ADS)

    Hellman, Olle; Steneteg, Peter; Abrikosov, I. A.; Simak, S. I.

    2013-03-01

    We have developed a thorough and accurate method of determining anharmonic free energies, the temperature dependent effective potential technique (TDEP). It is based on ab initio molecular dynamics followed by a mapping onto a model Hamiltonian that describes the lattice dynamics. The formalism and the numerical aspects of the technique are described in detail. A number of practical examples are given, and results are presented, which confirm the usefulness of TDEP within ab initio and classical molecular dynamics frameworks. In particular, we examine from first principles the behavior of force constants upon the dynamical stabilization of the body centered phase of Zr, and show that they become more localized. We also calculate the phase diagram for 4He modeled with the Aziz potential and obtain results which are in favorable agreement both with respect to experiment and established techniques.

  20. Distance scaling method for accurate prediction of slowly varying magnetic fields in satellite missions

    NASA Astrophysics Data System (ADS)

    Zacharias, Panagiotis P.; Chatzineofytou, Elpida G.; Spantideas, Sotirios T.; Capsalis, Christos N.

    2016-07-01

    In the present work, the determination of the magnetic behavior of localized magnetic sources from near-field measurements is examined. The distance power law of the magnetic field fall-off is used in various cases to accurately predict the magnetic signature of an equipment under test (EUT) consisting of multiple alternating current (AC) magnetic sources. Therefore, parameters concerning the location of the observation points (magnetometers) are studied towards this scope. The results clearly show that these parameters are independent of the EUT's size and layout. Additionally, the techniques developed in the present study enable the placing of the magnetometers close to the EUT, thus achieving high signal-to-noise ratio (SNR). Finally, the proposed method is verified by real measurements, using a mobile phone as an EUT.

  1. An Inexpensive, Accurate, and Precise Wet-Mount Method for Enumerating Aquatic Viruses

    PubMed Central

    Cunningham, Brady R.; Brum, Jennifer R.; Schwenck, Sarah M.; Sullivan, Matthew B.

    2015-01-01

    Viruses affect biogeochemical cycling, microbial mortality, gene flow, and metabolic functions in diverse environments through infection and lysis of microorganisms. Fundamental to quantitatively investigating these roles is the determination of viral abundance in both field and laboratory samples. One current, widely used method to accomplish this with aquatic samples is the “filter mount” method, in which samples are filtered onto costly 0.02-μm-pore-size ceramic filters for enumeration of viruses by epifluorescence microscopy. Here we describe a cost-effective (ca. 500-fold-lower materials cost) alternative virus enumeration method in which fluorescently stained samples are wet mounted directly onto slides, after optional chemical flocculation of viruses in samples with viral concentrations of <5 × 107 viruses ml−1. The concentration of viruses in the sample is then determined from the ratio of viruses to a known concentration of added microsphere beads via epifluorescence microscopy. Virus concentrations obtained by using this wet-mount method, with and without chemical flocculation, were significantly correlated with, and had precision equivalent to, those obtained by the filter mount method across concentrations ranging from 2.17 × 106 to 1.37 × 108 viruses ml−1 when tested by using cultivated viral isolates and natural samples from marine and freshwater environments. In summary, the wet-mount method is significantly less expensive than the filter mount method and is appropriate for rapid, precise, and accurate enumeration of aquatic viruses over a wide range of viral concentrations (≥1 × 106 viruses ml−1) encountered in field and laboratory samples. PMID:25710369

  2. Development and Validation of RP-HPLC Method for the Estimation of Ivabradine Hydrochloride in Tablets

    PubMed Central

    Seerapu, Sunitha; Srinivasan, B. P.

    2010-01-01

    A simple, sensitive, precise and robust reverse–phase high-performance liquid chromatographic method for analysis of ivabradine hydrochloride in pharmaceutical formulations was developed and validated as per ICH guidelines. The separation was performed on SS Wakosil C18AR, 250×4.6 mm, 5 μm column with methanol:25 mM phosphate buffer (60:40 v/v), adjusted to pH 6.5 with orthophosphoric acid, added drop wise, as mobile phase. A well defined chromatographic peak of Ivabradine hydrochloride was exhibited with a retention time of 6.55±0.05 min and tailing factor of 1.14 at the flow rate of 0.8 ml/min and at ambient temperature, when monitored at 285 nm. The linear regression analysis data for calibration plots showed good linear relationship with R=0.9998 in the concentration range of 30-210 μg/ml. The method was validated for precision, recovery and robustness. Intra and Inter-day precision (% relative standard deviation) were always less than 2%. The method showed the mean % recovery of 99.00 and 98.55 % for Ivabrad and Inapure tablets, respectively. The proposed method has been successfully applied to the commercial tablets without any interference of excipients. PMID:21695008

  3. Stability indicating HPLC method for the simultaneous determination of moxifloxacin and prednisolone in pharmaceutical formulations

    PubMed Central

    2012-01-01

    Background A simple, specific, and fast stability indicating reverse phase liquid chromatographic method was established for instantaneous determination of moxifloxacin and prednisolone in bulk drugs and pharmaceutical formulations. Results Optimum chromatographic separations among the moxifloxacin, prednisolone and stress-induced degradation products were achieved within 10 minutes by use of BDS Hypersil C8 column (250 X 4.6 mm, 5 μm) as stationary phase with mobile phase consisted of a mixture of phosphate buffer (18 mM) containing 0.1% (v/v) triethylamine, at pH 2.8 (adjusted with dilute phosphoric acid) and methanol (38:62 v/v) at a flow rate of 1.5 mL min-1. Detection was performed at 254 nm using diode array detector. The method was validated in accordance with ICH guidelines. Response was a linear function of concentrations over the range of 20–80 μg mL-1 for moxifloxacin (r2 ≥ 0.998) and 40–160 μg mL-1 for prednisolone (r2 ≥ 0.998). The method was resulted in good separation of both the analytes and degradation products with acceptable tailing and resolution. The peak purity index for both the analytes after all types of stress conditions was ≥ 0.9999 indicated a complete separation of both the analyte peaks from degradation products. The method can therefore, be regarded as stabilityindicating. Conclusions The developed method can be applied successfully for simultaneous determination of moxifloxacin and prednisolone in pharmaceutical formulations and their stability studies. PMID:22947049

  4. Forced Degradation and Photodegradation Studies of Pyrrolo[3,4-c]pyridine-1,3-dione Derivatives as Analgesic Active Compounds Using HPLC, UV and IR Spectrometry, and HPLC/MS Methods.

    PubMed

    Muszalska, Izabela; Ciemniejewski, Michał P; Lesniewska, Monika A; Szkatuła, Dominika; Malinka, Wiesław

    2015-01-01

    The stress and accelerated tests as well as photostability analysis in solutions and the solid phase of three selected derivatives of pyrrolo[3,4-c]pyridine-1,3-dione were carried out according the International Conference on Harmonization guidelines. For observation of the degradation of tested compounds, the RP-HPLC method was used. The study included the effect of temperature, relative humidity, water, H+ and OH- ions, hydrogen peroxide, and light (6.0×10(6), 1.2×10(6) lux·h) on the stability of pyrrolo[3,4-c]pyridine-1,3-dione derivatives. Studies have shown that these derivatives are photolabile, extremely unstable in an alkaline medium, labile in an acidic medium, and stable in a neutral medium. Their sensitivity to oxidizing agents depends on the chemical structure. The shortening of the aliphatic chain leads to an increase in the sensitivity to hydrolytic and oxidizing factors. The presence of the 1,3,4-tetraisoquinoline group promotes an increase in the susceptibility to photodegradation. The introduction of a carbonyl group to the aliphatic chain and the tetrafluoromethyl group to the phenyl ring stabilizes the molecule in the case of hydrolysis and oxidation and also increases sensitivity to light. The analysis of observed photodegradation products using the HPLC-diode array detector, HPLC/MS, and UV and IR spectrometry techniques showed degradation targeted at the breaking of the pyrrolo[3,4-c]pyridine-1,3-dione, piperazine, and/or tetrahydroisoquinoline rings. PMID:26525243

  5. Comparison of polarimetry and crown ether-based HPLC chiral stationary phase method to determine (L)-amino acid optical purity.

    PubMed

    Lee, Mee Sung; Khan, F Nawaz; Shin, Sung Chul; Jeong, Euh Duck; Kim, Hae Gyeong; Kim, Mi Jin; Cho, Yoon Jae; Cha, Jae-Young; Hyun, Myung Ho; Jin, Jong Sung

    2012-11-15

    Although various pharmacopoeias provide titration methods to assay (L)-amino acid content, none of these methods distinguish between (L)- and (D)-amino acids and do not consider the presence of enantiomeric impurities. Consequently, these methods are limited in scope to describe the relationship between content and specific rotation, [α]. In this study, the US Pharmacopoeia method was compared with the crown ether-based high performance liquid chromatographic (HPLC) chiral stationary phase (CSP) method to determine (L)-amino acid content and specific rotation. The (L)-amino acid content specified by the US Pharmacopoeia method was not consistent with the specific rotation in the presence of enantiomeric impurities, whereas the HPLC-CSP method was very effective for determining the (L)-amino acid content and the optical purity. The other advantage is that the HPLC-CSP method requires amino acid samples of quite low concentration (as low as 1 μg/mL), whereas the pharmacopoeia method requires higher concentrations (20-110 mg/mL). PMID:22868097

  6. Validation of a HPLC/FLD Method for Quantification of Tocotrienols in Human Plasma.

    PubMed

    Che, Hui-Ling; Tan, Doryn Meam-Yee; Meganathan, Puvaneswari; Gan, Yee-Lin; Abdul Razak, Ghazali; Fu, Ju-Yen

    2015-01-01

    Quantification of tocotrienols in human plasma is critical when the attention towards tocotrienols on its distinctive properties is arising. We aim to develop a simple and practical normal-phase high performance liquid chromatography method to quantify the amount of four tocotrienol homologues in human plasma. Using both the external and internal standards, tocotrienol homologues were quantified via a normal-phase high performance liquid chromatography with fluorescence detector maintained at the excitation wavelength of 295 nm and the emission wavelength of 325 nm. The four tocotrienol homologues were well separated within 30 minutes. A large interindividual variation between subjects was observed as the absorption of tocotrienols is dependent on food matrix and gut lipolysis. The accuracies of lower and upper limit of quantification ranged between 92% and 109% for intraday assays and 90% and 112% for interday assays. This method was successfully applied to quantify the total amount of four tocotrienol homologues in human plasma. PMID:26604927

  7. Validation of a HPLC/FLD Method for Quantification of Tocotrienols in Human Plasma

    PubMed Central

    Che, Hui-Ling; Tan, Doryn Meam-Yee; Meganathan, Puvaneswari; Gan, Yee-Lin; Abdul Razak, Ghazali; Fu, Ju-Yen

    2015-01-01

    Quantification of tocotrienols in human plasma is critical when the attention towards tocotrienols on its distinctive properties is arising. We aim to develop a simple and practical normal-phase high performance liquid chromatography method to quantify the amount of four tocotrienol homologues in human plasma. Using both the external and internal standards, tocotrienol homologues were quantified via a normal-phase high performance liquid chromatography with fluorescence detector maintained at the excitation wavelength of 295 nm and the emission wavelength of 325 nm. The four tocotrienol homologues were well separated within 30 minutes. A large interindividual variation between subjects was observed as the absorption of tocotrienols is dependent on food matrix and gut lipolysis. The accuracies of lower and upper limit of quantification ranged between 92% and 109% for intraday assays and 90% and 112% for interday assays. This method was successfully applied to quantify the total amount of four tocotrienol homologues in human plasma. PMID:26604927

  8. An HPLC-HR-MS-MS method for identification of anticoagulant rodenticides in blood.

    PubMed

    Schaff, Jason E; Montgomery, Madeline A

    2013-01-01

    This paper presents a fully validated method for the qualitative identification of bromadiolone, brodifacoum, coumachlor, coumatetralyl, difenacoum and warfarin in whole blood specimens. Samples are protein precipitated with acetonitrile, processed via solid-phase extraction and analyzed by high-performance liquid chromatography with high resolution tandem mass spectrometric detection. Limits of detection were 10 ng/mL or better for all analytes. PMID:23667199

  9. Earthquake Rupture Dynamics using Adaptive Mesh Refinement and High-Order Accurate Numerical Methods

    NASA Astrophysics Data System (ADS)

    Kozdon, J. E.; Wilcox, L.

    2013-12-01

    Our goal is to develop scalable and adaptive (spatial and temporal) numerical methods for coupled, multiphysics problems using high-order accurate numerical methods. To do so, we are developing an opensource, parallel library known as bfam (available at http://bfam.in). The first application to be developed on top of bfam is an earthquake rupture dynamics solver using high-order discontinuous Galerkin methods and summation-by-parts finite difference methods. In earthquake rupture dynamics, wave propagation in the Earth's crust is coupled to frictional sliding on fault interfaces. This coupling is two-way, required the simultaneous simulation of both processes. The use of laboratory-measured friction parameters requires near-fault resolution that is 4-5 orders of magnitude higher than that needed to resolve the frequencies of interest in the volume. This, along with earlier simulations using a low-order, finite volume based adaptive mesh refinement framework, suggest that adaptive mesh refinement is ideally suited for this problem. The use of high-order methods is motivated by the high level of resolution required off the fault in earlier the low-order finite volume simulations; we believe this need for resolution is a result of the excessive numerical dissipation of low-order methods. In bfam spatial adaptivity is handled using the p4est library and temporal adaptivity will be accomplished through local time stepping. In this presentation we will present the guiding principles behind the library as well as verification of code against the Southern California Earthquake Center dynamic rupture code validation test problems.

  10. Simultaneous quantification of paracetamol, acetylsalicylic acid and papaverine with a validated HPLC method.

    PubMed

    Kalmár, Eva; Gyuricza, Anett; Kunos-Tóth, Erika; Szakonyi, Gerda; Dombi, György

    2014-01-01

    Combined drug products have the advantages of better patient compliance and possible synergic effects. The simultaneous application of several active ingredients at a time is therefore frequently chosen. However, the quantitative analysis of such medicines can be challenging. The aim of this study is to provide a validated method for the investigation of a multidose packed oral powder that contained acetylsalicylic acid, paracetamol and papaverine-HCl. Reversed-phase high-pressure liquid chromatography was used. The Agilent Zorbax SB-C18 column was found to be the most suitable of the three different stationary phases tested for the separation of the components of this sample. The key parameters in the method development (apart from the nature of the column) were the pH of the aqueous phase (set to 3.4) and the ratio of the organic (acetonitrile) and the aqueous (25 mM phosphate buffer) phases, which was varied from 7:93 (v/v) to 25:75 (v/v) in a linear gradient, preceded by an initial hold. The method was validated: linearity, precision (repeatability and intermediate precision), accuracy, specificity and robustness were all tested, and the results met the ICH guidelines. PMID:24344050

  11. Development and validation of RP-HPLC method for quantification of glipizide in biological macromolecules.

    PubMed

    Pani, Nihar Ranjan; Acharya, Sujata; Patra, Sradhanjali

    2014-04-01

    Glipizide (GPZ) has been widely used in the treatment of type-2 diabetics as insulin secretogague. Multiunit chitosan based GPZ floating microspheres was prepared by ionotropic gelation method for gastroretentive delivery using sodiumtripolyphosphate as cross-linking agent. Pharmacokinetic study of microspheres was done in rabbit and plasma samples were analyzed by a newly developed and validated high-performance liquid chromatographic method. Method was developed on Hypersil ODS-18 column using a mobile phase of 10mM phosphate buffer (pH, 3.5) and methanol (25:75, v/v). Elute was monitored at 230 nm with a flow rate of 1 mL/min. Calibration curve was linear over the concentration range of 25.38-2046.45 ng/mL. Retention times of GPZ and internal standard (gliclazide) were 7.32 and 9.02 min respectively. Maximum plasma drug concentration, area under the plasma drug concentration-time curve and elimination half life for GPZ floating microspheres were 2.88±0.29 μg mL(-1), 38.46±2.26 μg h mL(-1) and 13.55±1.36 h respectively. When the fraction of drug dissolved from microspheres in pH 7.4 was plotted against the fraction of drug absorbed, a linear correlation (R(2)=0.991) was obtained in in vitro and in vivo correlation study. PMID:24418334

  12. Development of a method for the determination of cefovecin in plasma by HPLC.

    PubMed

    Cox, Sherry; Martin, Ali; Hamill, Mallery; Pistole, Nealy; Steeil, James; Schumacher, Juergen

    2014-08-01

    A simple high-performance liquid chromatography method for the determination of cefovecin in small volume plasma has been developed. Following solid-phase extraction using Oasis HLB cartridges, samples were separated by reverse-phase high-performance liquid chromatography on an XBridge C8 (3.5 µm) 4.6 × 250 mm column and quantified using ultraviolet detection at 280 nm. The mobile phase was a mixture of 10 mm ammonium acetate (pH 3.5) and acetonitrile (89:11), with a flow rate of 0.85 mL/min. The standard curve ranged from 0.1 to 200 µg/mL. Intra- and Inter-assay variability for cefovecin was <10%, and the average recovery was >90%. The lower limit of quantitation was 0.1 µg/mL. This method was successfully applied to the analysis of cefovecin samples at our institution. This is also the first fully validated method with an internal standard that does not use mass spectrometry. PMID:24420236

  13. A stability indicating HPLC method for the determination of clobazam and its basic degradation product characterization

    PubMed Central

    2014-01-01

    Background Clobazam is used for the treatment of different types of seizure and epilepsy. The present research is undertaken to study the systematic forced degradation of clobazam and to identify its main degradation product under basic conditions. Methods The degradation of clobazam was studied under different conditions. Clobazam and its degradation products were separated using a Nova-Pak C18 column and a mixture of KH2PO4 50 mM (pH 8.5) and acetonitrile (50:50, v/v) as the mobile phase with UV detection at 230 nm. Results The within-day and between-day precision values in the calibration range of 0.1-20 μg/ml were within 0.5-1.5%. Clobazam was relatively stable in solid from under exposure to visible and UV light and also heat. The clobazam aqueous solution of clobazam was more labile under exposure to visible and UV light. The bulk drug was significantly degraded under exposure to 2 M HCl, 0.1 M NaOH or 3% H2O2. Using the tablet powder, higher degradation rates were observed under different stress conditions. The main degradation product of clobazam under basic condition was subsequently characterized. Conclusion The developed method could be used for the determination of clobazam in the presence of its degradation products with acceptable precision and accuracy. The applicability of the proposed method was evaluated in commercial dosage forms analysis. PMID:24919821

  14. Stability-Indicating RP-HPLC Method for Estimation of Miglitol in Bulk and Tablets

    PubMed Central

    Shrivastava, B.; Baghel, U. S.; Sahu, M.

    2010-01-01

    A selective and sensitive, stability-indicating reverse phase high performance liquid chromatography method has been first developed and validated for the estimation of miglitol in bulk and tablet dosages form. Samples were separated on a prepacked, Inertsil amino C18 column (150×4.6 mm i.d.) using a mobile phase comprised of acetonitrile and monobasic sodium phosphate pH 7.5 (80:20, v/v) delivered at 1.5 ml/min flow rate. Detection was performed on a SPD-20A prominence UV/Vis detector at 220 nm. The retention time for miglitol was 13.93±0.0367. The method was validated in terms of linearity, precision, accuracy, ruggedness, and specificity, limit of detection and limit of quantification. The linearity (r2) and percentage recoveries of miglitol were 0.9986 and 99.85%. This method is suitable for routine estimation of miglitol in bulk and tablet dosages form. PMID:21969753

  15. Extracting accurate strain measurements in bone mechanics: A critical review of current methods.

    PubMed

    Grassi, Lorenzo; Isaksson, Hanna

    2015-10-01

    Osteoporosis related fractures are a social burden that advocates for more accurate fracture prediction methods. Mechanistic methods, e.g. finite element models, have been proposed as a tool to better predict bone mechanical behaviour and strength. However, there is little consensus about the optimal constitutive law to describe bone as a material. Extracting reliable and relevant strain data from experimental tests is of fundamental importance to better understand bone mechanical properties, and to validate numerical models. Several techniques have been used to measure strain in experimental mechanics, with substantial differences in terms of accuracy, precision, time- and length-scale. Each technique presents upsides and downsides that must be carefully evaluated when designing the experiment. Moreover, additional complexities are often encountered when applying such strain measurement techniques to bone, due to its complex composite structure. This review of literature examined the four most commonly adopted methods for strain measurements (strain gauges, fibre Bragg grating sensors, digital image correlation, and digital volume correlation), with a focus on studies with bone as a substrate material, at the organ and tissue level. For each of them the working principles, a summary of the main applications to bone mechanics at the organ- and tissue-level, and a list of pros and cons are provided. PMID:26099201

  16. An accurate and nondestructive GC method for determination of cocaine on US paper currency.

    PubMed

    Zuo, Yuegang; Zhang, Kai; Wu, Jingping; Rego, Christopher; Fritz, John

    2008-07-01

    The presence of cocaine on US paper currency has been known for a long time. Banknotes become contaminated during the exchange, storage, and abuse of cocaine. The analysis of cocaine on various denominations of US banknotes in the general circulation can provide law enforcement circles and forensic epidemiologists objective and timely information on epidemiology of illicit drug use and on how to differentiate money contaminated in the general circulation from banknotes used in drug transaction. A simple, nondestructive, and accurate capillary gas chromatographic method has been developed for the determination of cocaine on various denominations of US banknotes in this study. The method comprises a fast ultrasonic extraction using water as a solvent followed by a SPE cleanup process with a C(18) cartridge and capillary GC separation, identification, and quantification. This nondestructive analytical method has been successfully applied to determine the cocaine contamination in US paper currency of all denominations. Standard calibration curve was linear over the concentration range from the LOQ (2.00 ng/mL) to 100 microg/mL and the RSD less than 2.0%. Cocaine was detected in 67% of the circulated banknotes collected in Southeastern Massachusetts in amounts ranging from approximately 2 ng to 49.4 microg per note. On average, $5, 10, 20, and 50 denominations contain higher amounts of cocaine than $1 and 100 denominations of US banknotes. PMID:18646272

  17. A Method for Accurate Reconstructions of the Upper Airway Using Magnetic Resonance Images

    PubMed Central

    Xiong, Huahui; Huang, Xiaoqing; Li, Yong; Li, Jianhong; Xian, Junfang; Huang, Yaqi

    2015-01-01

    Objective The purpose of this study is to provide an optimized method to reconstruct the structure of the upper airway (UA) based on magnetic resonance imaging (MRI) that can faithfully show the anatomical structure with a smooth surface without artificial modifications. Methods MRI was performed on the head and neck of a healthy young male participant in the axial, coronal and sagittal planes to acquire images of the UA. The level set method was used to segment the boundary of the UA. The boundaries in the three scanning planes were registered according to the positions of crossing points and anatomical characteristics using a Matlab program. Finally, the three-dimensional (3D) NURBS (Non-Uniform Rational B-Splines) surface of the UA was constructed using the registered boundaries in all three different planes. Results A smooth 3D structure of the UA was constructed, which captured the anatomical features from the three anatomical planes, particularly the location of the anterior wall of the nasopharynx. The volume and area of every cross section of the UA can be calculated from the constructed 3D model of UA. Conclusions A complete scheme of reconstruction of the UA was proposed, which can be used to measure and evaluate the 3D upper airway accurately. PMID:26066461

  18. Conservative high-order-accurate finite-difference methods for curvilinear grids

    NASA Technical Reports Server (NTRS)

    Rai, Man M.; Chakrvarthy, Sukumar

    1993-01-01

    Two fourth-order-accurate finite-difference methods for numerically solving hyperbolic systems of conservation equations on smooth curvilinear grids are presented. The first method uses the differential form of the conservation equations; the second method uses the integral form of the conservation equations. Modifications to these schemes, which are required near boundaries to maintain overall high-order accuracy, are discussed. An analysis that demonstrates the stability of the modified schemes is also provided. Modifications to one of the schemes to make it total variation diminishing (TVD) are also discussed. Results that demonstrate the high-order accuracy of both schemes are included in the paper. In particular, a Ringleb-flow computation demonstrates the high-order accuracy and the stability of the boundary and near-boundary procedures. A second computation of supersonic flow over a cylinder demonstrates the shock-capturing capability of the TVD methodology. An important contribution of this paper is the dear demonstration that higher order accuracy leads to increased computational efficiency.

  19. Assessment of isoflavone aglycones variability in soy food supplements using a validated HPLC-UV method

    PubMed Central

    UIFĂLEAN, ALINA; FARCAŞ, ANCA; ILIEŞ, MARIA; HEGHEŞ, SIMONA CODRUŢA; IONESCU, CORINA; IUGA, CRISTINA ADELA

    2015-01-01

    Background and aims Soy supplements are often recommended in the management of menopause symptoms. The declared content of soy supplements is commonly expressed as total isoflavones per dosage form. Given that soy isoflavones have different estrogenic potencies, pharmacokinetics and metabolism, the aim of this study was to evaluate the total isoflavone content and the aglycone profile of seven soy supplements and one soy seed extract. Label accuracy was assessed, in relation to the precise content and the recommended posology for estimating whether the optimal dose is achieved for alleviating menopause symptoms. Methods A high performance liquid chromatography method was developed for evaluating the aglycone content (genistein, daidzein, glycitein). After extraction and acidic hydrolysis, the aglycones were separated on a C18 column, using 0.1% acetic acid and acetonitrile as mobile phases. The flow rate was 1.5mL min−1 and the UV detector wavelength was set at 260nm. A linear relationship was found in the range 5–80μg mL−1. The method was validated using the accuracy profile methodology. Results The total isoflavone content ranged from 6.07 to 41.68mg dosage form−1. Various aglycone profiles were obtained for each supplement which can result in a different estrogenic activity, bioavailability and finally, in a different efficiency in alleviating menopause symptoms. In most clinical trials where soy isoflavones were evaluated, little attention was paid to determining the exact aglycone profile of the employed soy extracts. Conclusions As clinical outcomes continue to be controversial, this study highlights the need of standardization in genistein, rather than total isoflavones and labeling accuracy for soy supplements. PMID:26609272

  20. Sensitive and rapid HPLC-UV method with back-extraction step for the determination of sildenafil in human plasma.

    PubMed

    Al-Hroub, Hamza; Alkhawaja, Bayan; Alkhawaja, Eman; Arafat, Tawfiq

    2016-01-15

    In this work we provided a selective, sensitive and rapid HPLC-UV method for quantification of sildenafil in human plasma. We have adopted a simple liquid-liquid extraction procedure followed a back-extraction in 5% perchloric acid solution. Chromatographic separation was achieved on a BDS C-18Column (150mm×4.6mm, 5μm) using a mobile phase consisted 63% water, 37% acetonitrile and 0.1% triethylamine (pH 7.7). The analysis was detected at 230nm. The achieved lower limit of quantification was 2.00ng/ml. The method showed linear calibration curve over the range of 2.00-200ng/ml. Intra- and inter day precision (CV%) were less than 6.80 and 5.19%, respectively. Whilst intra- and inter day accuracy% were ranged between (98.3 and 105%) and (99.4 and 103%), respectively. Tests confirmed the stability of sildenafil in plasma at room temperature for 24h, during three freeze-thaw cycles, after 24h in autosampler at 10°C and after 60 days in plasma at -30°C. The recovery of sildenafil was greater than 78.4%. The described simple UV method achieved very low limit of quantification and by using simple and inexpensive extraction procedure, complete separation was obtained within short run time. Having demonstrated the validity and novelty of our method, thus it is applicable for the clinical and pharmacokinetic studies of sildenafil in human volunteers especially in laboratories in countries where cost of modern techniques and instrumentation is prohibitive. PMID:26688342

  1. Solid-Phase Extraction and Simultaneous Determination of Tetracycline Residues in Edible Cattle Tissues Using an HPLC-FL Method

    PubMed Central

    Mesgari Abbasi, Mehran; Nemati, Mahboob; Babaei, Hossein; Ansarin, Masoud; Nourdadgar, Ashraf-O-Sadat

    2012-01-01

    In this assay, edible cattle tissues from local markets of Ardabil, a Province of Iran, were examined for residues of tetracycline antibiotics (tetracycline, oxytetracycline and chlortetracycline). In total, 110 samples of triceps, gluteal muscle, diaphragm, kidney and liver were randomly obtained from the local markets of the city of Ardabil. Solid-phase extraction (SPE) and high-performance liquid chromatography (HPLC) methods were used to extract and analyze tetracycline antibiotic (TC) residues, respectively. The mean amount of total TC residues in all tested samples was 226.3 ± 112.5 ng/g and the mean amount of the total TC residues in triceps, gluteal muscle, diaphragm, kidney and liver samples were 176.3 ± 46.8, 405.3 ± 219.6, 96.8 ± 26.9, 672.4 ± 192.0 and 651.3 ± 210.1 ng/g, respectively. Additionally, 25.8% of muscle samples, 31.8% of liver samples and 22.7% of kidney samples contained amounts of TC residues beyond the maximum residue limit (MRLs). To reduce the TC residues found in edible cattle tissues, regulatory authorities should ensure that the cattle would undergo the proper withdrawal period from TCs before the slaughtering. PMID:24250505

  2. An HPLC-DAD method for simultaneous quantitative determination of four active hydrophilic compounds in Magnoliae officinalis cortex.

    PubMed

    Yan, Renyi; Yu, Shengxian; Liu, Hongliang; Xue, Zhenzhen; Yang, Bin

    2015-04-01

    Magnoliae officinalis cortex (MOC), derived from Magnolia officinalis and its variation M. officinalis var. biloba, is an important traditional Chinese medicine. In our previous work, 11 hydrophilic ingredients of MOC were isolated and structurally elucidated and four, namely syringin (SG), magnoloside A (MA), magnoloside B (MB) and magnoflorine (MF), showed bioactive effects. Herein, we describe an HPLC-DAD method for the simultaneous quantitative determination of MA, MB, MF and SG in MOC for the first time. The chromatographic separation of samples was performed on an Agilent Zorbax SB-C18 column (250 × 4.6 mm i.d., 5 µm) by gradient elution with water-acetic acid (pH 3.0) and methanol at a flow rate of 1.0 mL/min. The wavelengths were set at 265 nm for MF and SG, and 328 nm for MA and MB. The average recovery of the four compounds was from 97.63 to 103.84%. Nearly 100 MOC samples harvested from eight habitats were analyzed in which the contents of the tested compound varied in the range of 0.016-0.350% (MF), 0.010-0.337% (SG), 0.017-3.009% (MB) and 0.077-2.529% (MA). The analysis also indicated that MOC contains a significant amount of phenylethanoid glycosides. This was an unexpected finding because previously lignan was considered to be the main component of MOC. PMID:25085894

  3. Physical and chemical properties and stability of sodium cefazolin in buffered eye drops determined with HPLC method.

    PubMed

    Kodym, Anna; Bilski, Piotr; Domańska, Agata; Hełminiak, Łukasz; Jabłońska, Maria; Jachymska, Anna

    2012-01-01

    The aim of the studies was to analyze the stability of 1% and 5% eye drops containing sodium cefazolin, prepared in citrate buffer of pH 6.11-6.27, which were stored at the temperature of 4 degrees C and 20 degrees C with light protection. The drops were prepared under aseptic conditions by dissolving sodium cefazolin (Biofazolin, IBA Bioton), dry injection form of the drug, in citrate buffer. The viscosity of the drops was increased using polyvinyl alcohol. The drops were preserved with phenylmercuric borate of 0.001% concentration mixed with beta-phenylethyl alcohol of 0.4% concentration in the drops. The concentration of cefazolin was determined at every three days using HPLC method. Besides, the measurements of pH, osmotic pressure and viscosity were performed as well as the organoleptic analysis of the drops (clarity, color, odor). The concentration of cefazolin in 1% drops after the 30-day-storage at the temperature of 4 degrees C, depending on their composition, decreased in the range of 2.17-6.02%. In 5% drops the decrease in cefazolin concentration was similar, i.e., after 30-day-storage at the temperature of 4 degrees C it was 1.62-6.76%. In 1% and 5% drops stored at the temperature of 20 degrees C the stability of the drops determined as the 10% degradation time of cefazolin was in the range of 9-15 days. PMID:22574512

  4. Fast and Accurate Microplate Method (Biolog MT2) for Detection of Fusarium Fungicides Resistance/Sensitivity

    PubMed Central

    Frąc, Magdalena; Gryta, Agata; Oszust, Karolina; Kotowicz, Natalia

    2016-01-01

    The need for finding fungicides against Fusarium is a key step in the chemical plant protection and using appropriate chemical agents. Existing, conventional methods of evaluation of Fusarium isolates resistance to fungicides are costly, time-consuming and potentially environmentally harmful due to usage of high amounts of potentially toxic chemicals. Therefore, the development of fast, accurate and effective detection methods for Fusarium resistance to fungicides is urgently required. MT2 microplates (BiologTM) method is traditionally used for bacteria identification and the evaluation of their ability to utilize different carbon substrates. However, to the best of our knowledge, there is no reports concerning the use of this technical tool to determine fungicides resistance of the Fusarium isolates. For this reason, the objectives of this study are to develop a fast method for Fusarium resistance to fungicides detection and to validate the effectiveness approach between both traditional hole-plate and MT2 microplates assays. In presented study MT2 microplate-based assay was evaluated for potential use as an alternative resistance detection method. This was carried out using three commercially available fungicides, containing following active substances: triazoles (tebuconazole), benzimidazoles (carbendazim) and strobilurins (azoxystrobin), in six concentrations (0, 0.0005, 0.005, 0.05, 0.1, 0.2%), for nine selected Fusarium isolates. In this study, the particular concentrations of each fungicides was loaded into MT2 microplate wells. The wells were inoculated with the Fusarium mycelium suspended in PM4-IF inoculating fluid. Before inoculation the suspension was standardized for each isolates into 75% of transmittance. Traditional hole-plate method was used as a control assay. The fungicides concentrations in control method were the following: 0, 0.0005, 0.005, 0.05, 0.5, 1, 2, 5, 10, 25, and 50%. Strong relationships between MT2 microplate and traditional hole

  5. Fast and Accurate Microplate Method (Biolog MT2) for Detection of Fusarium Fungicides Resistance/Sensitivity.

    PubMed

    Frąc, Magdalena; Gryta, Agata; Oszust, Karolina; Kotowicz, Natalia

    2016-01-01

    The need for finding fungicides against Fusarium is a key step in the chemical plant protection and using appropriate chemical agents. Existing, conventional methods of evaluation of Fusarium isolates resistance to fungicides are costly, time-consuming and potentially environmentally harmful due to usage of high amounts of potentially toxic chemicals. Therefore, the development of fast, accurate and effective detection methods for Fusarium resistance to fungicides is urgently required. MT2 microplates (Biolog(TM)) method is traditionally used for bacteria identification and the evaluation of their ability to utilize different carbon substrates. However, to the best of our knowledge, there is no reports concerning the use of this technical tool to determine fungicides resistance of the Fusarium isolates. For this reason, the objectives of this study are to develop a fast method for Fusarium resistance to fungicides detection and to validate the effectiveness approach between both traditional hole-plate and MT2 microplates assays. In presented study MT2 microplate-based assay was evaluated for potential use as an alternative resistance detection method. This was carried out using three commercially available fungicides, containing following active substances: triazoles (tebuconazole), benzimidazoles (carbendazim) and strobilurins (azoxystrobin), in six concentrations (0, 0.0005, 0.005, 0.05, 0.1, 0.2%), for nine selected Fusarium isolates. In this study, the particular concentrations of each fungicides was loaded into MT2 microplate wells. The wells were inoculated with the Fusarium mycelium suspended in PM4-IF inoculating fluid. Before inoculation the suspension was standardized for each isolates into 75% of transmittance. Traditional hole-plate method was used as a control assay. The fungicides concentrations in control method were the following: 0, 0.0005, 0.005, 0.05, 0.5, 1, 2, 5, 10, 25, and 50%. Strong relationships between MT2 microplate and traditional hole

  6. Validated RP-HPLC and TLC-Densitometric Methods for Analysis of Ternary Mixture of Cetylpyridinium Chloride, Chlorocresol and Lidocaine in Oral Antiseptic Formulation.

    PubMed

    Abdelwahab, Nada S; Ali, Nouruddin W; Abdelkawy, M; Emam, Aml A

    2016-03-01

    This work was concerned with development, optimization, application and validation of reversed phase high performance liquid chromatography (RP-HPLC) and thin layer chromatography (TLC)-densitometric methods for analysis of cetylpyridinium chloride, chlorocresol and lidocaine in Canyon(®) gel. The first developed RP-HPLC method depended on chromatographic separation on a ZORBAX Eclipse Plus C8 column, with elution with a mobile phase consisting of 0.05% phosphoric acid solution : acetonitrile : methanol (15 : 24 : 61, by volume), pumping the mobile phase at a flow rate of 1.00 mL min(-1), with ultraviolet detection at 220 nm. While in the subsequently developed method, the TLC-densitometric method, complete separation of the studied mixture was achieved using methanol : acetone : acetic acid (7 : 3 : 0.2, by volume) as a mobile phase, aluminum plates precoated with silica gel 60 F254 as a stationary phase and 215 nm as the scanning wavelength. Factors affecting the developed methods were studied and optimized; moreover, methods had been validated as per the International Conference of Harmonization guideline and the results indicated that the suggested methods were reproducible, reliable and applicable for rapid routine analysis. Statistical comparison of the two developed methods with the reported HPLC ones using F- and Student's t tests showed no significant difference. PMID:26363491

  7. Dietary Sugars Analysis: Quantification of Fructooligossacharides during Fermentation by HPLC-RI Method

    PubMed Central

    Correia, Daniela M.; Dias, Luís G.; Veloso, Ana C. A.; Dias, Teresa; Rocha, Isabel; Rodrigues, Lígia R.; Peres, António M.

    2014-01-01

    In this work, a simple chromatographic method is proposed and in-house validated for the quantification of total and individual fructooligossacharides (e.g., 1-kestose, nystose, and 1F-fructofuranosylnystose). It was shown that a high-performance liquid chromatography with refractive index detector could be used to monitor the dynamic of fructooligossacharides production via sucrose fermentation using Aspergillus aculeatus. This analytical technique may be easily implemented at laboratorial or industrial scale for fructooligossacharides mass-production monitoring allowing also controlling the main substrate (sucrose) and the secondary by-products (glucose and fructose). The proposed chromatographic method had a satisfactory intra- and inter-day variability (in general, with a relative standard deviation lower than 5%), high sensitivity for each sugar (usually, with a relative error lower than 5%), and low detection (lower than 0.06 ± 0.04 g/L) and quantification (lower than 0.2 ± 0.1 g/L) limits. The correct quantification of fructooligossacharides in fermentative media may allow a more precise nutritional formulation of new functional foods, since it is reported that different fructooligossacharides exhibit different biological activities and effects. PMID:25988114

  8. A Weight-Averaged Interpolation Method for Coupling Time-Accurate Rarefied and Continuum Flows

    NASA Astrophysics Data System (ADS)

    Diaz, Steven William

    A novel approach to coupling rarefied and continuum flow regimes as a single, hybrid model is introduced. The method borrows from techniques used in the simulation of spray flows to interpolate Lagrangian point-particles onto an Eulerian grid in a weight-averaged sense. A brief overview of traditional methods for modeling both rarefied and continuum domains is given, and a review of the literature regarding rarefied/continuum flow coupling is presented. Details of the theoretical development of the method of weighted interpolation are then described. The method evaluates macroscopic properties at the nodes of a CFD grid via the weighted interpolation of all simulated molecules in a set surrounding the node. The weight factor applied to each simulated molecule is the inverse of the linear distance between it and the given node. During development, the method was applied to several preliminary cases, including supersonic flow over an airfoil, subsonic flow over tandem airfoils, and supersonic flow over a backward facing step; all at low Knudsen numbers. The main thrust of the research centered on the time-accurate expansion of a rocket plume into a near-vacuum. The method proves flexible enough to be used with various flow solvers, demonstrated by the use of Fluent as the continuum solver for the preliminary cases and a NASA-developed Large Eddy Simulation research code, WRLES, for the full lunar model. The method is applicable to a wide range of Mach numbers and is completely grid independent, allowing the rarefied and continuum solvers to be optimized for their respective domains without consideration of the other. The work presented demonstrates the validity, and flexibility of the method of weighted interpolation as a novel concept in the field of hybrid flow coupling. The method marks a significant divergence from current practices in the coupling of rarefied and continuum flow domains and offers a kernel on which to base an ongoing field of research. It has the

  9. Qualitative and quantitative analysis of chemical constituents of Centipeda minima by HPLC-QTOF-MS & HPLC-DAD.

    PubMed

    Chan, Chi-On; Jin, Deng-Ping; Dong, Nai-Ping; Chen, Si-Bao; Mok, Daniel Kam Wah

    2016-06-01

    A high performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (HPLC-QTOF-MS) method in both positive and negative ion modes was established to investigate the major constituents in the ethanolic extract of Centipeda minima (EBSC). Twelve common components including flavones and their glycosides, phenolic and polyphenolic acids, and sesquiterpene lactone were identified in ten batches of samples based on comparison with the retention time and accurate mass of external standards (mass accuracy within 3ppm) or the fragmentation patterns of tandem MS. Meanwhile, a simple, accurate and reliable HPLC-DAD method was also developed to determine the content of 10 chemical markers simultaneously. Results obtained from method validations including linearity, accuracy and precision showed that this new method is reliable and robust. Isochlorogenic acid A and brevilin A were found to be the most abundant in the ethanol extract of EBSC and could be served as markers for quality control of EBSC. PMID:27131150

  10. A time-accurate adaptive grid method and the numerical simulation of a shock-vortex interaction

    NASA Technical Reports Server (NTRS)

    Bockelie, Michael J.; Eiseman, Peter R.

    1990-01-01

    A time accurate, general purpose, adaptive grid method is developed that is suitable for multidimensional steady and unsteady numerical simulations. The grid point movement is performed in a manner that generates smooth grids which resolve the severe solution gradients and the sharp transitions in the solution gradients. The temporal coupling of the adaptive grid and the PDE solver is performed with a grid prediction correction method that is simple to implement and ensures the time accuracy of the grid. Time accurate solutions of the 2-D Euler equations for an unsteady shock vortex interaction demonstrate the ability of the adaptive method to accurately adapt the grid to multiple solution features.

  11. Simple and rapid RP-HPLC method for simultaneous determination of acyclovir and zidovudine in human plasma.

    PubMed

    Sharma, Megha; Nautiyal, Pragya; Jain, Surendra; Jain, Deepti

    2010-01-01

    Combination therapy with acyclovir and zidovudine is used for the treatment of herpes-infected immunocompromised patients. In the view of the optimal drug concentrations (minimum effective concentrations) for viral suppression and avoidance of drug toxicity, monitoring of drug levels has been considered essential to determine drug concentrations in plasma after administration of a dose of acyclovir and zidovudine. A simple, precise, and rapid RP-HPLC method has been developed for this purpose. Chromatographic separation was performed using methanol-water (50 + 50, v/v), pH 2.5 adjusted with orthophosphoric acid, as an isocratic mobile phase at a flow rate of 0.8 mL/min with an Inertsil ODS (C18) column (5 microm particle size, 250 x 4.60 mm id). Detection was carried out using a UV photo diode array detector at 258 nm. The plasma samples were prepared by a protein precipitation method. The retention time for acyclovir and zidovudine was 3.5 +/- 0.2 and 6.2 +/- 0.3 min, respectively. The method was linear in the range of 200-1800 and 400-3600 ng/mL with LOQ of 200 ng (SD = +/-1.4) and 400 ng (SD = +/-0.9) for zidovudine and acyclovir, respectively, in plasma. The mean accuracy was 98.0 and 96.4%, with average extraction recovery of 64.8 +/- 2.1 and 77.5 +/- 1.7% for lower nominal concentrations of acyclovir and zidovudine, respectively. PMID:21140658

  12. HPLC-DAD Method for the Pharmacokinetic Interaction Study of Atorvastatin with Pioglitazone and Cholestyramine in Wistar Rats.

    PubMed

    Sharma, Ritesh N; Pancholi, Shyam S

    2014-09-01

    Carotid intima-media thickness is used as a surrogate marker for cardiovascular complications in diabetes mellitus. The combination of atorvastatin and pioglitazone was found to be effective in reducing the thickness of the carotid intima-media layer. The method of RP-HPLC coupled with a diode array detector (DAD) was developed for the pharmacokinetic interaction study of atorvastatin with pioglitazone and cholestyramine, respectively, in Wistar rats. Atorvastatin (ATR) and pioglitazone (PIO) were resolved on a C18 column with a mobile phase composed of 48% methanol, 19% acetonitrile, and 33% 10 mM ammonium formate (v/v/v; pH 3.5±0.3, by formic acid) and a 260 nm detection wavelength on the diode array detector. The method was validated according to international standards with good reproducibility and linear response; mean (r) 0.9987 and 0.9972 to ATR and PIO, respectively. The coefficients of variation of intra- and interassay precision ranged between 4.95-8.12 and 7.29-9.67, respectively. Pharmacokinetic parameters were determined in rats following an oral administration of atorvastatin in the presence and absence of pioglitazone and also with cholestyramine. Compared with the control given atorvastatin alone, the Cmax and AUC of atorvastatin were merely unchanged in rats with the co-administration of pioglitazone, while they decreased by nearly 21 and 15%, respectively, with the concurrent use of cholestyramine. There were no significant changes in Tmax and the plasma half-life (T1/2 ) of atorvastatin in both cases. The performed experiment demonstrated that the presented method was suitable for the estimation and pharmacokinetic interaction study of atorvastatin with pioglitazone and cholestyramine in Wistar rat plasma. PMID:25853068

  13. Development of a new HPLC method using fluorescence detection without derivatization for determining purine nucleoside phosphorylase activity in human plasma.

    PubMed

    Giuliani, Patricia; Zuccarini, Mariachiara; Buccella, Silvana; Rossini, Margherita; D'Alimonte, Iolanda; Ciccarelli, Renata; Marzo, Matteo; Marzo, Antonio; Di Iorio, Patrizia; Caciagli, Francesco

    2016-01-15

    Purine nucleoside phosphorylase (PNP) activity is involved in cell survival and function, since PNP is a key enzyme in the purine metabolic pathway where it catalyzes the phosphorolysis of the nucleosides to the corresponding nucleobases. Its dysfunction has been found in relevant pathological conditions (such as inflammation and cancer), so the detection of PNP activity in plasma could represent an attractive marker for early diagnosis or assessment of disease progression. Thus the aim of this study was to develop a simple, fast and sensitive HPLC method for the determination of PNP activity in plasma. The separation was achieved on a Phenomenex Kinetex PFP column using 0.1% formic acid in water and methanol as mobile phases in gradient elution mode at a flow rate of 1ml/min and purine compounds were detected using UV absorption and fluorescence. The analysis was fast since the run was achieved within 13min. This method improved the separation of the different purines, allowing the UV-based quantification of the natural PNP substrates (inosine and guanosine) or products (hypoxanthine and guanine) and its subsequent metabolic products (xanthine and uric acid) with a good precision and accuracy. The most interesting innovation is the simultaneous use of a fluorescence detector (excitation/emission wavelength of 260/375nm) that allowed the quantification of guanosine and guanine without derivatization. Compared with UV, the fluorescence detection improved the sensitivity for guanine detection by about 10-fold and abolished almost completely the baseline noise due to the presence of plasma in the enzymatic reaction mixture. Thus, the validated method allowed an excellent evaluation of PNP activity in plasma which could be useful as an indicator of several pathological conditions. PMID:26720700

  14. Development and validation of an anion-exchange HPLC method for the determination of fluoride content and radiochemical purity in [18F]NaF.

    PubMed

    Li, Chang-Chin; Farn, Shiou-Shiow; Yeh, Yuen-Han; Lin, Wuu-Jyh; Shen, Lie-Hang

    2011-05-01

    (18)F-labeled sodium fluoride ([(18)F]NaF) is a useful bone imaging agent that has been demonstrated to be significantly more accurate than (99m)Tc-labeled methylene diphosphonate for the detection of both sclerotic and lytic lesions in various malignancies. A reliable anion-exchange HPLC method equipped with suppressed conductivity and radioactive detectors has been developed in order to analyze the content of NaF and radiochemical purity in [(18)F]NaF radiopharmaceuticals. The method described for fluoride analysis uses an isocratic elution of NaF in a Hamilton anion-exchange column using a mobile phase that consists of 7.5 mM sodium carbonate and 0.018 mM potassium thiocyanate. The flow rate was 1.0 ml/min. The method was validated in accordance with several parameters, including system suitability, specificity, precision, accuracy, linearity, robustness, limit of detection and limit of quantification. The results are described as follows: (1) The system suitability includes the tailing factor, theoretical plate number and resolution, which are 1.192534, 2729.6594 and 16.7415, respectively. (2) For specificity, the solvent peak and chloride ion did not interfere with the retention time of the fluoride. (3) The percentage coefficient of variation for analysis of precision, including repeatability and intermediate precision, is less than 2.0%. (4) Accuracy of method is within the range of 98%-102%. (5) The range of linearity is from 10 to 400 μg/ml, with the correlation coefficient (R(2)) always being above 0.9985. (6) The data of method robustness are within acceptance criteria. (7) The limit of detection and limit of quantification are 0.0678 and 0.20 μg/ml, respectively. All of the analysis results demonstrate that this method is highly sensitive, convenient, specific and suitable for quantification of NaF over a wide linear range. Therefore, the method can be successfully performed for routine analysis of fluoride content in [(18)F]NaF radiopharmaceuticals

  15. Accurate Ionization Potentials and Electron Affinities of Acceptor Molecules III: A Benchmark of GW Methods.

    PubMed

    Knight, Joseph W; Wang, Xiaopeng; Gallandi, Lukas; Dolgounitcheva, Olga; Ren, Xinguo; Ortiz, J Vincent; Rinke, Patrick; Körzdörfer, Thomas; Marom, Noa

    2016-02-01

    The performance of different GW methods is assessed for a set of 24 organic acceptors. Errors are evaluated with respect to coupled cluster singles, doubles, and perturbative triples [CCSD(T)] reference data for the vertical ionization potentials (IPs) and electron affinities (EAs), extrapolated to the complete basis set limit. Additional comparisons are made to experimental data, where available. We consider fully self-consistent GW (scGW), partial self-consistency in the Green's function (scGW0), non-self-consistent G0W0 based on several mean-field starting points, and a "beyond GW" second-order screened exchange (SOSEX) correction to G0W0. We also describe the implementation of the self-consistent Coulomb hole with screened exchange method (COHSEX), which serves as one of the mean-field starting points. The best performers overall are G0W0+SOSEX and G0W0 based on an IP-tuned long-range corrected hybrid functional with the former being more accurate for EAs and the latter for IPs. Both provide a balanced treatment of localized vs delocalized states and valence spectra in good agreement with photoemission spectroscopy (PES) experiments. PMID:26731609

  16. A Statistical Method for Assessing Peptide Identification Confidence in Accurate Mass and Time Tag Proteomics

    SciTech Connect

    Stanley, Jeffrey R.; Adkins, Joshua N.; Slysz, Gordon W.; Monroe, Matthew E.; Purvine, Samuel O.; Karpievitch, Yuliya V.; Anderson, Gordon A.; Smith, Richard D.; Dabney, Alan R.

    2011-07-15

    High-throughput proteomics is rapidly evolving to require high mass measurement accuracy for a variety of different applications. Increased mass measurement accuracy in bottom-up proteomics specifically allows for an improved ability to distinguish and characterize detected MS features, which may in turn be identified by, e.g., matching to entries in a database for both precursor and fragmentation mass identification methods. Many tools exist with which to score the identification of peptides from LC-MS/MS measurements or to assess matches to an accurate mass and time (AMT) tag database, but these two calculations remain distinctly unrelated. Here we present a statistical method, Statistical Tools for AMT tag Confidence (STAC), which extends our previous work incorporating prior probabilities of correct sequence identification from LC-MS/MS, as well as the quality with which LC-MS features match AMT tags, to evaluate peptide identification confidence. Compared to existing tools, we are able to obtain significantly more high-confidence peptide identifications at a given false discovery rate and additionally assign confidence estimates to individual peptide identifications. Freely available software implementations of STAC are available in both command line and as a Windows graphical application.

  17. Obtaining accurate amounts of mercury from mercury compounds via electrolytic methods

    DOEpatents

    Grossman, Mark W.; George, William A.

    1987-01-01

    A process for obtaining pre-determined, accurate rate amounts of mercury. In one embodiment, predetermined, precise amounts of Hg are separated from HgO and plated onto a cathode wire. The method for doing this involves dissolving a precise amount of HgO which corresponds to a pre-determined amount of Hg desired in an electrolyte solution comprised of glacial acetic acid and H.sub.2 O. The mercuric ions are then electrolytically reduced and plated onto a cathode producing the required pre-determined quantity of Hg. In another embodiment, pre-determined, precise amounts of Hg are obtained from Hg.sub.2 Cl.sub.2. The method for doing this involves dissolving a precise amount of Hg.sub.2 Cl.sub.2 in an electrolyte solution comprised of concentrated HCl and H.sub.2 O. The mercurous ions in solution are then electrolytically reduced and plated onto a cathode wire producing the required, pre-determined quantity of Hg.

  18. Obtaining accurate amounts of mercury from mercury compounds via electrolytic methods

    DOEpatents

    Grossman, M.W.; George, W.A.

    1987-07-07

    A process is described for obtaining pre-determined, accurate rate amounts of mercury. In one embodiment, predetermined, precise amounts of Hg are separated from HgO and plated onto a cathode wire. The method for doing this involves dissolving a precise amount of HgO which corresponds to a pre-determined amount of Hg desired in an electrolyte solution comprised of glacial acetic acid and H[sub 2]O. The mercuric ions are then electrolytically reduced and plated onto a cathode producing the required pre-determined quantity of Hg. In another embodiment, pre-determined, precise amounts of Hg are obtained from Hg[sub 2]Cl[sub 2]. The method for doing this involves dissolving a precise amount of Hg[sub 2]Cl[sub 2] in an electrolyte solution comprised of concentrated HCl and H[sub 2]O. The mercurous ions in solution are then electrolytically reduced and plated onto a cathode wire producing the required, pre-determined quantity of Hg. 1 fig.

  19. Methods for accurate cold-chain temperature monitoring using digital data-logger thermometers

    NASA Astrophysics Data System (ADS)

    Chojnacky, M. J.; Miller, W. M.; Strouse, G. F.

    2013-09-01

    Complete and accurate records of vaccine temperature history are vital to preserving drug potency and patient safety. However, previously published vaccine storage and handling guidelines have failed to indicate a need for continuous temperature monitoring in vaccine storage refrigerators. We evaluated the performance of seven digital data logger models as candidates for continuous temperature monitoring of refrigerated vaccines, based on the following criteria: out-of-box performance and compliance with manufacturer accuracy specifications over the range of use; measurement stability over extended, continuous use; proper setup in a vaccine storage refrigerator so that measurements reflect liquid vaccine temperatures; and practical methods for end-user validation and establishing metrological traceability. Data loggers were tested using ice melting point checks and by comparison to calibrated thermocouples to characterize performance over 0 °C to 10 °C. We also monitored logger performance in a study designed to replicate the range of vaccine storage and environmental conditions encountered at provider offices. Based on the results of this study, the Centers for Disease Control released new guidelines on proper methods for storage, handling, and temperature monitoring of vaccines for participants in its federally-funded Vaccines for Children Program. Improved temperature monitoring practices will ultimately decrease waste from damaged vaccines, improve consumer confidence, and increase effective inoculation rates.

  20. Accurate method to study static volume-pressure relationships in small fetal and neonatal animals.

    PubMed

    Suen, H C; Losty, P D; Donahoe, P K; Schnitzer, J J

    1994-08-01

    We designed an accurate method to study respiratory static volume-pressure relationships in small fetal and neonatal animals on the basis of Archimedes' principle. Our method eliminates the error caused by the compressibility of air (Boyle's law) and is sensitive to a volume change of as little as 1 microliters. Fetal and neonatal rats during the period of rapid lung development from day 19.5 of gestation (term = day 22) to day 3.5 postnatum were studied. The absolute lung volume at a transrespiratory pressure of 30-40 cmH2O increased 28-fold from 0.036 +/- 0.006 (SE) to 0.994 +/- 0.042 ml, the volume per gram of lung increased 14-fold from 0.39 +/- 0.07 to 5.59 +/- 0.66 ml/g, compliance increased 12-fold from 2.3 +/- 0.4 to 27.3 +/- 2.7 microliters/cmH2O, and specific compliance increased 6-fold from 24.9 +/- 4.5 to 152.3 +/- 22.8 microliters.cmH2O-1.g lung-1. This technique, which allowed us to compare changes during late gestation and the early neonatal period in small rodents, can be used to monitor and evaluate pulmonary functional changes after in utero pharmacological therapies in experimentally induced abnormalities such as pulmonary hypoplasia, surfactant deficiency, and congenital diaphragmatic hernia. PMID:8002489

  1. Accurate computation of surface stresses and forces with immersed boundary methods

    NASA Astrophysics Data System (ADS)

    Goza, Andres; Liska, Sebastian; Morley, Benjamin; Colonius, Tim

    2016-09-01

    Many immersed boundary methods solve for surface stresses that impose the velocity boundary conditions on an immersed body. These surface stresses may contain spurious oscillations that make them ill-suited for representing the physical surface stresses on the body. Moreover, these inaccurate stresses often lead to unphysical oscillations in the history of integrated surface forces such as the coefficient of lift. While the errors in the surface stresses and forces do not necessarily affect the convergence of the velocity field, it is desirable, especially in fluid-structure interaction problems, to obtain smooth and convergent stress distributions on the surface. To this end, we show that the equation for the surface stresses is an integral equation of the first kind whose ill-posedness is the source of spurious oscillations in the stresses. We also demonstrate that for sufficiently smooth delta functions, the oscillations may be filtered out to obtain physically accurate surface stresses. The filtering is applied as a post-processing procedure, so that the convergence of the velocity field is unaffected. We demonstrate the efficacy of the method by computing stresses and forces that converge to the physical stresses and forces for several test problems.

  2. Full factorial design for optimization, development and validation of HPLC method to determine valsartan in nanoparticles.

    PubMed

    Kumar, Lalit; Sreenivasa Reddy, M; Managuli, Renuka S; Pai K, Girish

    2015-10-01

    High performance liquid chromatographic method was optimized, developed and validated as per the ICH guidelines. In this study the 20 mM ammonium formate and acetonitrile in the 57:43 ratio were used as mobile phase for the analysis of valsartan. Full factorial design was used to optimize the effect of variable factors. The responses were peak area, tailing factor and number of theoretical plates. The quadratic effect of flow rate and wavelength individually as well as in interaction were most significant (p < 0.0001 and p < 0.0086, respectively) on peak area; the quadratic effect of pH of buffer was also most significant effect (p < 0.0001) on tailing factor (5%) whereas the quadratic effect of flow rate and wavelength individually was significant (p = 0.0006 and p = 0.0265, respectively) on the number of theoretical plates. The high-performance liquid chromatographic separation was performed at the flow rate 1.0 min/mL, UV detector wavelength 250 nm and pH of the buffer 3.0 as optimized parameters using design of experiments. The retention time values of valsartan were found to be 10.177 min. Percent recovery in terms of accuracy for the prepared valsartan nanoparticles was found in the range of 98.57-100.27%. PMID:26594122

  3. Validation of Quantitative HPLC Method for Bacosides in KeenMind

    PubMed Central

    Dowell, Ashley; Davidson, George; Ghosh, Dilip

    2015-01-01

    Brahmi (Bacopa monnieri) has been used by Ayurvedic medical practitioners in India for almost 3000 years. The pharmacological properties of Bacopa monnieri were studied extensively and the activities were attributed mainly due to the presence of characteristic saponins called “bacosides.” Bacosides are complex mixture of structurally closely related compounds, glycosides of either jujubogenin or pseudojujubogenin. The popularity of herbal medicines and increasing clinical evidence to support associated health claims require standardisation of the phytochemical actives contained in these products. However, unlike allopathic medicines which typically contain a single active compound, herbal medicines are typically complex mixtures of various phytochemicals. The assay for bacosides in the British Pharmacopoeia monograph for Bacopa monnieri exemplifies that only a subset of bacosides present are included in the calculation of total bacosides. These results in calculated bacoside values are significantly lower than those attained for the same material using more inclusive techniques such as UV spectroscopy. This study illustrates some of the problems encountered when applying chemical analysis for standardisation of herbal medicines, particularly in relation to the new method development and validation of bacosides from KeenMind. PMID:26448776

  4. Full factorial design for optimization, development and validation of HPLC method to determine valsartan in nanoparticles

    PubMed Central

    Kumar, Lalit; Sreenivasa Reddy, M.; Managuli, Renuka S.; Pai K., Girish

    2015-01-01

    High performance liquid chromatographic method was optimized, developed and validated as per the ICH guidelines. In this study the 20 mM ammonium formate and acetonitrile in the 57:43 ratio were used as mobile phase for the analysis of valsartan. Full factorial design was used to optimize the effect of variable factors. The responses were peak area, tailing factor and number of theoretical plates. The quadratic effect of flow rate and wavelength individually as well as in interaction were most significant (p < 0.0001 and p < 0.0086, respectively) on peak area; the quadratic effect of pH of buffer was also most significant effect (p < 0.0001) on tailing factor (5%) whereas the quadratic effect of flow rate and wavelength individually was significant (p = 0.0006 and p = 0.0265, respectively) on the number of theoretical plates. The high-performance liquid chromatographic separation was performed at the flow rate 1.0 min/mL, UV detector wavelength 250 nm and pH of the buffer 3.0 as optimized parameters using design of experiments. The retention time values of valsartan were found to be 10.177 min. Percent recovery in terms of accuracy for the prepared valsartan nanoparticles was found in the range of 98.57–100.27%. PMID:26594122

  5. A HPLC-MS/MS method for determination of 6'''-feruloylspinosin in rat plasma and tissues: Pharmacokinetics and tissue distribution study.

    PubMed

    Qiao, Longdong; Liu, Yan; Chen, Xiaoyan; Xie, Junbo; Zhang, Yanqing; Yang, Ke; Zhou, Hongjian; Duan, Yayun; Zheng, Wei; Xie, Wenlin

    2016-03-20

    A sensitive, reliable and accurate HPLC-MS/MS method was developed and validated for the quantification of 6'''-feruloylspinosin in rat plasma and tissues with puerarin as the internal standard. The separation was performed on a Proshell 120 EC-C18 column (4.6×150 mm, 2.7 μm) with a mobile phase consisting of acetonitrile and 0.1% formic acid (20:80, v/v) at 0.3 mL/min. The quantification was performed by MRM with m/z [M-H](-) 783.3→427.2 for 6'''-feruloylspinosin and m/z [M-H](-) 415.4→295.4 for the internal standard, respectively. The calibration curves covered over a concentration range of 20-2000 ng/mL in plasma and various tissues samples (heart, liver, spleen, lung, kidney, stomach, intestine, muscle, cerebrum and cerebellum) with good linearity (r(2)≥0.9914). Both the intra- and inter-day precisions were less than 14.70%, and the accuracy (RE%) ranged from -5.80% to 4.93%. The extraction recoveries were within 75.21-92.96%, and the matrix effect ranged from 87.21% to 113.44%. Compared with spinosin, 6'''-feruloylspinosin was distributed in rats faster whereas more slowly eliminated from the plasma. 6'''-Feruloylspinosin could be distributed rapidly and widely in various tissues, and transfer across the blood-brain barrier. In addition, both 6'''-feruloylspinosin and spinosin could enhance the expression of GABAAα1, GABAAα5, GABABR1 mRNA in rat hippocampal neurons significantly, indicating the bioactivity mechanism of 6'''-feruloylspinosin was involved in the GABA receptors. PMID:26780157

  6. Methods for accurate estimation of net discharge in a tidal channel

    USGS Publications Warehouse

    Simpson, M.R.; Bland, R.

    2000-01-01

    Accurate estimates of net residual discharge in tidally affected rivers and estuaries are possible because of recently developed ultrasonic discharge measurement techniques. Previous discharge estimates using conventional mechanical current meters and methods based on stage/discharge relations or water slope measurements often yielded errors that were as great as or greater than the computed residual discharge. Ultrasonic measurement methods consist of: 1) the use of ultrasonic instruments for the measurement of a representative 'index' velocity used for in situ estimation of mean water velocity and 2) the use of the acoustic Doppler current discharge measurement system to calibrate the index velocity measurement data. Methods used to calibrate (rate) the index velocity to the channel velocity measured using the Acoustic Doppler Current Profiler are the most critical factors affecting the accuracy of net discharge estimation. The index velocity first must be related to mean channel velocity and then used to calculate instantaneous channel discharge. Finally, discharge is low-pass filtered to remove the effects of the tides. An ultrasonic velocity meter discharge-measurement site in a tidally affected region of the Sacramento-San Joaquin Rivers was used to study the accuracy of the index velocity calibration procedure. Calibration data consisting of ultrasonic velocity meter index velocity and concurrent acoustic Doppler discharge measurement data were collected during three time periods. Two sets of data were collected during a spring tide (monthly maximum tidal current) and one of data collected during a neap tide (monthly minimum tidal current). The relative magnitude of instrumental errors, acoustic Doppler discharge measurement errors, and calibration errors were evaluated. Calibration error was found to be the most significant source of error in estimating net discharge. Using a comprehensive calibration method, net discharge estimates developed from the three

  7. Accurate gradient approximation for complex interface problems in 3D by an improved coupling interface method

    NASA Astrophysics Data System (ADS)

    Shu, Yu-Chen; Chern, I.-Liang; Chang, Chien C.

    2014-10-01

    Most elliptic interface solvers become complicated for complex interface problems at those “exceptional points” where there are not enough neighboring interior points for high order interpolation. Such complication increases especially in three dimensions. Usually, the solvers are thus reduced to low order accuracy. In this paper, we classify these exceptional points and propose two recipes to maintain order of accuracy there, aiming at improving the previous coupling interface method [26]. Yet the idea is also applicable to other interface solvers. The main idea is to have at least first order approximations for second order derivatives at those exceptional points. Recipe 1 is to use the finite difference approximation for the second order derivatives at a nearby interior grid point, whenever this is possible. Recipe 2 is to flip domain signatures and introduce a ghost state so that a second-order method can be applied. This ghost state is a smooth extension of the solution at the exceptional point from the other side of the interface. The original state is recovered by a post-processing using nearby states and jump conditions. The choice of recipes is determined by a classification scheme of the exceptional points. The method renders the solution and its gradient uniformly second-order accurate in the entire computed domain. Numerical examples are provided to illustrate the second order accuracy of the presently proposed method in approximating the gradients of the original states for some complex interfaces which we had tested previous in two and three dimensions, and a real molecule (1D63) which is double-helix shape and composed of hundreds of atoms.

  8. Accurate gradient approximation for complex interface problems in 3D by an improved coupling interface method

    SciTech Connect

    Shu, Yu-Chen; Chern, I-Liang; Chang, Chien C.

    2014-10-15

    Most elliptic interface solvers become complicated for complex interface problems at those “exceptional points” where there are not enough neighboring interior points for high order interpolation. Such complication increases especially in three dimensions. Usually, the solvers are thus reduced to low order accuracy. In this paper, we classify these exceptional points and propose two recipes to maintain order of accuracy there, aiming at improving the previous coupling interface method [26]. Yet the idea is also applicable to other interface solvers. The main idea is to have at least first order approximations for second order derivatives at those exceptional points. Recipe 1 is to use the finite difference approximation for the second order derivatives at a nearby interior grid point, whenever this is possible. Recipe 2 is to flip domain signatures and introduce a ghost state so that a second-order method can be applied. This ghost state is a smooth extension of the solution at the exceptional point from the other side of the interface. The original state is recovered by a post-processing using nearby states and jump conditions. The choice of recipes is determined by a classification scheme of the exceptional points. The method renders the solution and its gradient uniformly second-order accurate in the entire computed domain. Numerical examples are provided to illustrate the second order accuracy of the presently proposed method in approximating the gradients of the original states for some complex interfaces which we had tested previous in two and three dimensions, and a real molecule ( (1D63)) which is double-helix shape and composed of hundreds of atoms.

  9. A New Method for Accurate Treatment of Flow Equations in Cylindrical Coordinates Using Series Expansions

    NASA Technical Reports Server (NTRS)

    Constantinescu, G.S.; Lele, S. K.

    2000-01-01

    The motivation of this work is the ongoing effort at the Center for Turbulence Research (CTR) to use large eddy simulation (LES) techniques to calculate the noise radiated by jet engines. The focus on engine exhaust noise reduction is motivated by the fact that a significant reduction has been achieved over the last decade on the other main sources of acoustic emissions of jet engines, such as the fan and turbomachinery noise, which gives increased priority to jet noise. To be able to propose methods to reduce the jet noise based on results of numerical simulations, one first has to be able to accurately predict the spatio-temporal distribution of the noise sources in the jet. Though a great deal of understanding of the fundamental turbulence mechanisms in high-speed jets was obtained from direct numerical simulations (DNS) at low Reynolds numbers, LES seems to be the only realistic available tool to obtain the necessary near-field information that is required to estimate the acoustic radiation of the turbulent compressible engine exhaust jets. The quality of jet-noise predictions is determined by the accuracy of the numerical method that has to capture the wide range of pressure fluctuations associated with the turbulence in the jet and with the resulting radiated noise, and by the boundary condition treatment and the quality of the mesh. Higher Reynolds numbers and coarser grids put in turn a higher burden on the robustness and accuracy of the numerical method used in this kind of jet LES simulations. As these calculations are often done in cylindrical coordinates, one of the most important requirements for the numerical method is to provide a flow solution that is not contaminated by numerical artifacts. The coordinate singularity is known to be a source of such artifacts. In the present work we use 6th order Pade schemes in the non-periodic directions to discretize the full compressible flow equations. It turns out that the quality of jet-noise predictions

  10. Stability-indicating reversed-phase HPLC method development and characterization of impurities in vortioxetine utilizing LC-MS, IR and NMR.

    PubMed

    Liu, Lei; Cao, Na; Ma, Xingling; Xiong, Kaihe; Sun, Lili; Zou, Qiaogen; Yao, Lili

    2016-01-01

    The current study reports the development and validation of a stability-indicating reversed phase HPLC method for the separation and identification of potential impurities in vortioxetine, a recently developed antidepressant. The structures of a new compound and four process-related impurities formed during the synthesis were characterized and confirmed by NMR, MS, and IR spectroscopy analyses. The most probable formation mechanisms of the impurities identified were proposed. Based on the characterization data, the new compound was proposed to be 1-[4-[(2,4-dimethylphenyl)thio]phenyl]-piperazine. In addition, an efficient chromatographic method was optimized to separate and quantify the impurities, which were obtained in the 0.05-0.75 μg/mL range. The developed HPLC method was validated with respect to accuracy, precision, linearity, robustness, and limits of detection and quantitation. PMID:26412721

  11. [Development of Determination Method of Fluoroquinolone Antibiotics in Sludge Based on Solid Phase Extraction and HPLC-Fluorescence Detection Analysis].

    PubMed

    Dai, Xiao-hu; Xue, Yong-gang; Liu, Hua-jie; Dai, Ling-ling; Yan, Han; Li, Ning

    2016-04-15

    Fluoroquinolone antibiotics (FQs), as the common pharmaceuticals and personal care products (PPCPs), are widespread in the environment. FQs contained in wastewater would be ultimately enriched in sludge, posing a potential threat to the consequent sludge utilization. To optimize the analytical method applicable to the determination of FQs in sludge, the authors selected ofloxacin (OFL), norfioxacin (NOR), ciprofloxacin (CIP) and lomefloxacin (LOM) as the target FQs, and established a method which was based on cell lysis, FQs extraction with triethylamine/methanol/water solution, Solid Phase Extraction (SPE) and HPLC-Fluorescence Detection (FLD) determination. After the investigation, phosphoric acid-triethylamine was decided to be the buffer salt, and methanol was chosen as the organic mobile phase. The gradient fluorescence scanning strategy was proved to be necessary for the optimal detection as well. Furthermore, by the designed orthogonal experiments, the effects of the extraction materials, pH, and the eluents on the efficiency of SPE extraction were evaluated, by which the optimal extraction conditions were determined. As a result, FQs in liquid samples could be analyzed by utilizing HLB extraction cartridge, and the recovery rates of the four FQs were in the range of 82%-103%. As for solid samples, the recovery rates of the four FQs contained reached up to 71%-101%. Finally, the adsorptivity of the sludge from the different tanks ( anaerobic, anoxic and oxic tanks) was investigated, showing gradual decrease in the adsorption capacity, but all adsorbed over 90% of the EQs. This conclusion also confirmed that 50% removal of FQs in the domestic wastewater treatment plant was realized by sludge adsorption. PMID:27548982

  12. A novel uHPLC-MS/MS method for the quantitation of AZD7451 (AZ12607092) in human plasma.

    PubMed

    Peer, Cody J; Brown, Jeffrey L; Martin, Timothy J; Roth, Jeffrey; Spencer, Shawn D; Brassil, Patrick; McNeill, Katharine A; Kreisl, Teri N; Fine, Howard A; Figg, William D

    2013-12-30

    Tropomyosin-related kinases (Trk) are tyrosine kinase receptors implicated in tumor proliferation, invasion, and survival signaling across a number of tumors, making them potentially attractive targets for the treatment of cancer. AZD7451 is a potent and selective inhibitor of Trk kinases currently undergoing a Phase I dose escalation in glioblastoma multiforme at the National Cancer Institute. A key part of early clinical testing for AZD7451 involves demonstrating that pharmacokinetic half-life and clinical exposures of AZD7451 are sufficient to inhibit Trk receptors in preclinical models. To address this need, an ultra sensitive analytical method was developed to measure the AZD7451 profile in human plasma. A liquid-liquid extraction recovered >80% of AZD7451 before quantitative analysis by ultra HPLC-MS/MS. A Varian Polaris(®) C18-A column and a mass transition of m/z 383.5→340.5 (m/z 389.6→342.0 for the internal standard [(2)H6]-AZD7451) was used, and a dynamic calibration range of 0.5-1000ng/mL was established, which provided a sensitive (<8.5% deviation), and precise (<6%) quantitative assay for AZD7451. AZD7451 demonstrated stability in human plasma at room temperature for 24h (<7% change) and after extraction at 4°C for 24h (<8% change), and was stable through 4 freeze/thaw cycles (<8% change). This method was used to measure AZD7451 plasma levels in clinical samples to confirm the sensitivity at several time points following AZD7451 treatment in subjects with glioblastoma. PMID:24239935

  13. Simple HPLC-UV method for the quantification of metformin in human plasma with one step protein precipitation.

    PubMed

    Chhetri, Himal Paudel; Thapa, Panna; Van Schepdael, Ann

    2014-11-01

    This study presents the optimization of a simple HPLC-UV method for the determination of metformin in human plasma. Ion pair separation followed by UV detection was performed on deproteinized human plasma samples. The separation was carried out on a Discovery Reversed Phase C-18 column (250 × 4.6 mm, 5 μm) with UV detection at 233 nm. The mobile phase contained 34% acetonitrile and 66% aqueous phase. Aqueous phase contained 10 mM KH2PO4 and 10 mM sodium lauryl sulfate. Aqueous phase pH was adjusted to 5.2. The mobile phase was run isocratically. The flow rate of the mobile phase was maintained at 1.3 ml/min. The linearity of the calibration curve was obtained in the concentration range of 0.125-2.5 μg/ml and coefficient of determination (R (2)) was found to be 0.9951. The lowest limit of quantification and detection was 125 and 62 ng/ml respectively. No endogenous substances were found to interfere with the peaks of drug and internal standard. The intra-day and inter-day coefficient of variations was 6.97% or less for all the selected concentrations. The relative errors at all the studied concentrations were 5.60% or less. This method is time efficient and samples are easy to prepare with minimum dilution. So, it can be applied for monitoring metformin in human plasma. PMID:25473337

  14. Application of spectrophotometric, densitometric, and HPLC techniques as stability indicating methods for determination of Zaleplon in pharmaceutical preparations

    NASA Astrophysics Data System (ADS)

    Metwally, Fadia H.; Abdelkawy, M.; Abdelwahab, Nada S.

    2007-12-01

    Spectrophotometric, spectrodensitometric and HPLC are stability indicating methods described for determination of Zaleplon in pure and dosage forms. As Zaleplon is easily degradable, the proposed techniques in this manuscript are adopted for its determination in presence of its alkaline degradation product, namely N-[4-(3-cyano-pyrazolo[1,5a]pyridin-7-yl)-phenyl]- N-ethyl-acetamide. These approaches are successfully applied to quantify Zaleplon using the information included in the absorption spectra of appropriate solutions. The second derivative (D 2) spectrophotometric method, allows determination of Zaleplon without interference of its degradate at 235.2 nm using 0.01N HCl as a solvent with obedience to Beer's law over a concentration range of 1-10 μg ml -1 with mean percentage recovery 100.24 ± 0.86%. The first derivative of the ratio spectra ( 1DD) based on the simultaneous use of ( 1DD) and measurement at 241.8 nm using the same solvent and over the same concentration range as (D 2) spectrophotometric method, with mean percentage recovery 99.9 ± 1.07%. The spectrodensitometric analysis allows the separation and quantitation of Zaleplon from its degradate on silica gel plates using chloroform:acetone:ammonia solution (9:1:0.2 by volume) as a mobile phase. This method depends on quantitave densitometric evaluation of thin layer chromatogram of Zaleplon at 338 nm over a concentration range of 0.2-1 μg band -1, with mean percentage recovery 99.73 ± 1.35. Also a reversed-phase liquid chromatographic method using 5-C8 (22 cm × 4.6 mm i.d. 5 μm particle size) column was described and validated for quantitation of Zaleplon using acetonitrile:deionised water (35:65, v/v) as a mobile phase using Paracetamol as internal standard and a flow rate of 1.5 ml min -1 with UV detection of the effluent at 232 nm at ambient temperature over a concentration range of 2-20 μg ml -1 with mean percentage recovery 100.19 ± 1.15%. The insignificance difference of the proposed

  15. Accurate reliability analysis method for quantum-dot cellular automata circuits

    NASA Astrophysics Data System (ADS)

    Cui, Huanqing; Cai, Li; Wang, Sen; Liu, Xiaoqiang; Yang, Xiaokuo

    2015-10-01

    Probabilistic transfer matrix (PTM) is a widely used model in the reliability research of circuits. However, PTM model cannot reflect the impact of input signals on reliability, so it does not completely conform to the mechanism of the novel field-coupled nanoelectronic device which is called quantum-dot cellular automata (QCA). It is difficult to get accurate results when PTM model is used to analyze the reliability of QCA circuits. To solve this problem, we present the fault tree models of QCA fundamental devices according to different input signals. After that, the binary decision diagram (BDD) is used to quantitatively investigate the reliability of two QCA XOR gates depending on the presented models. By employing the fault tree models, the impact of input signals on reliability can be identified clearly and the crucial components of a circuit can be found out precisely based on the importance values (IVs) of components. So this method is contributive to the construction of reliable QCA circuits.

  16. Accurate methods for computing inviscid and viscous Kelvin-Helmholtz instability

    NASA Astrophysics Data System (ADS)

    Chen, Michael J.; Forbes, Lawrence K.

    2011-02-01

    The Kelvin-Helmholtz instability is modelled for inviscid and viscous fluids. Here, two bounded fluid layers flow parallel to each other with the interface between them growing in an unstable fashion when subjected to a small perturbation. In the various configurations of this problem, and the related problem of the vortex sheet, there are several phenomena associated with the evolution of the interface; notably the formation of a finite time curvature singularity and the ‘roll-up' of the interface. Two contrasting computational schemes will be presented. A spectral method is used to follow the evolution of the interface in the inviscid version of the problem. This allows the interface shape to be computed up to the time that a curvature singularity forms, with several computational difficulties overcome to reach that point. A weakly compressible viscous version of the problem is studied using finite difference techniques and a vorticity-streamfunction formulation. The two versions have comparable, but not identical, initial conditions and so the results exhibit some differences in timing. By including a small amount of viscosity the interface may be followed to the point that it rolls up into a classic ‘cat's-eye' shape. Particular attention was given to computing a consistent initial condition and solving the continuity equation both accurately and efficiently.

  17. Method for accurate sizing of pulmonary vessels from 3D medical images

    NASA Astrophysics Data System (ADS)

    O'Dell, Walter G.

    2015-03-01

    Detailed characterization of vascular anatomy, in particular the quantification of changes in the distribution of vessel sizes and of vascular pruning, is essential for the diagnosis and management of a variety of pulmonary vascular diseases and for the care of cancer survivors who have received radiation to the thorax. Clinical estimates of vessel radii are typically based on setting a pixel intensity threshold and counting how many "On" pixels are present across the vessel cross-section. A more objective approach introduced recently involves fitting the image with a library of spherical Gaussian filters and utilizing the size of the best matching filter as the estimate of vessel diameter. However, both these approaches have significant accuracy limitations including mis-match between a Gaussian intensity distribution and that of real vessels. Here we introduce and demonstrate a novel approach for accurate vessel sizing using 3D appearance models of a tubular structure along a curvilinear trajectory in 3D space. The vessel branch trajectories are represented with cubic Hermite splines and the tubular branch surfaces represented as a finite element surface mesh. An iterative parameter adjustment scheme is employed to optimally match the appearance models to a patient's chest X-ray computed tomography (CT) scan to generate estimates for branch radii and trajectories with subpixel resolution. The method is demonstrated on pulmonary vasculature in an adult human CT scan, and on 2D simulated test cases.

  18. Fast, accurate and easy-to-pipeline methods for amplicon sequence processing

    NASA Astrophysics Data System (ADS)

    Antonielli, Livio; Sessitsch, Angela

    2016-04-01

    Next generation sequencing (NGS) technologies established since years as an essential resource in microbiology. While on the one hand metagenomic studies can benefit from the continuously increasing throughput of the Illumina (Solexa) technology, on the other hand the spreading of third generation sequencing technologies (PacBio, Oxford Nanopore) are getting whole genome sequencing beyond the assembly of fragmented draft genomes, making it now possible to finish bacterial genomes even without short read correction. Besides (meta)genomic analysis next-gen amplicon sequencing is still fundamental for microbial studies. Amplicon sequencing of the 16S rRNA gene and ITS (Internal Transcribed Spacer) remains a well-established widespread method for a multitude of different purposes concerning the identification and comparison of archaeal/bacterial (16S rRNA gene) and fungal (ITS) communities occurring in diverse environments. Numerous different pipelines have been developed in order to process NGS-derived amplicon sequences, among which Mothur, QIIME and USEARCH are the most well-known and cited ones. The entire process from initial raw sequence data through read error correction, paired-end read assembly, primer stripping, quality filtering, clustering, OTU taxonomic classification and BIOM table rarefaction as well as alternative "normalization" methods will be addressed. An effective and accurate strategy will be presented using the state-of-the-art bioinformatic tools and the example of a straightforward one-script pipeline for 16S rRNA gene or ITS MiSeq amplicon sequencing will be provided. Finally, instructions on how to automatically retrieve nucleotide sequences from NCBI and therefore apply the pipeline to targets other than 16S rRNA gene (Greengenes, SILVA) and ITS (UNITE) will be discussed.

  19. An automated, fast and accurate registration method to link stranded seeds in permanent prostate implants.

    PubMed

    Westendorp, Hendrik; Nuver, Tonnis T; Moerland, Marinus A; Minken, André W

    2015-10-21

    The geometry of a permanent prostate implant varies over time. Seeds can migrate and edema of the prostate affects the position of seeds. Seed movements directly influence dosimetry which relates to treatment quality. We present a method that tracks all individual seeds over time allowing quantification of seed movements. This linking procedure was tested on transrectal ultrasound (TRUS) and cone-beam CT (CBCT) datasets of 699 patients. These datasets were acquired intraoperatively during a dynamic implantation procedure, that combines both imaging modalities. The procedure was subdivided in four automatic linking steps. (I) The Hungarian Algorithm was applied to initially link seeds in CBCT and the corresponding TRUS datasets. (II) Strands were identified and optimized based on curvature and linefits: non optimal links were removed. (III) The positions of unlinked seeds were reviewed and were linked to incomplete strands if within curvature- and distance-thresholds. (IV) Finally, seeds close to strands were linked, also if the curvature-threshold was violated. After linking the seeds an affine transformation was applied. The procedure was repeated until the results were stable or the 6th iteration ended. All results were visually reviewed for mismatches and uncertainties. Eleven implants showed a mismatch and in 12 cases an uncertainty was identified. On average the linking procedure took 42 ms per case. This accurate and fast method has the potential to be used for other time spans, like Day 30, and other imaging modalities. It can potentially be used during a dynamic implantation procedure to faster and better evaluate the quality of the permanent prostate implant. PMID:26439900

  20. An automated, fast and accurate registration method to link stranded seeds in permanent prostate implants

    NASA Astrophysics Data System (ADS)

    Westendorp, Hendrik; Nuver, Tonnis T.; Moerland, Marinus A.; Minken, André W.

    2015-10-01

    The geometry of a permanent prostate implant varies over time. Seeds can migrate and edema of the prostate affects the position of seeds. Seed movements directly influence dosimetry which relates to treatment quality. We present a method that tracks all individual seeds over time allowing quantification of seed movements. This linking procedure was tested on transrectal ultrasound (TRUS) and cone-beam CT (CBCT) datasets of 699 patients. These datasets were acquired intraoperatively during a dynamic implantation procedure, that combines both imaging modalities. The procedure was subdivided in four automatic linking steps. (I) The Hungarian Algorithm was applied to initially link seeds in CBCT and the corresponding TRUS datasets. (II) Strands were identified and optimized based on curvature and linefits: non optimal links were removed. (III) The positions of unlinked seeds were reviewed and were linked to incomplete strands if within curvature- and distance-thresholds. (IV) Finally, seeds close to strands were linked, also if the curvature-threshold was violated. After linking the seeds an affine transformation was applied. The procedure was repeated until the results were stable or the 6th iteration ended. All results were visually reviewed for mismatches and uncertainties. Eleven implants showed a mismatch and in 12 cases an uncertainty was identified. On average the linking procedure took 42 ms per case. This accurate and fast method has the potential to be used for other time spans, like Day 30, and other imaging modalities. It can potentially be used during a dynamic implantation procedure to faster and better evaluate the quality of the permanent prostate implant.

  1. Antioxidant components of Viburnum opulus L. determined by on-line HPLC-UV-ABTS radical scavenging and LC-UV-ESI-MS methods.

    PubMed

    Karaçelik, Ayça Aktaş; Küçük, Murat; İskefiyeli, Zeynep; Aydemir, Sezgin; De Smet, Seppe; Miserez, Bram; Sandra, Patrick

    2015-05-15

    Antioxidant activity of the juice and seed and skin extracts prepared with methanol, acetonitrile, and water of Viburnum opulus L. grown in Eastern Black Sea Region were studied with an on-line HPLC-ABTS method and off-line antioxidant methods, among which a linear positive correlation was observed. The fruit extracts were analysed with the HPLC-UV method optimised with 14 standard phenolics. Identification of the phenolic components in the juice was made using an HPLC-UV-ESI-MS method. Nineteen phenolic compounds in juice were identified by comparing the retention times and mass spectra with those of the standards and the phenolics reported in the literature. The major peaks in the juice belonged to coumaroyl-quinic acid, chlorogenic acid, procyanidin B2, and procyanidin trimer. Quite different antioxidant composition profiles were obtained from the extracts with the solvents of different polarities. The antioxidant activities of the seed extracts were higher than those of the skin extracts in general. PMID:25577058

  2. A PLS-based extractive spectrophotometric method for simultaneous determination of carbamazepine and carbamazepine-10,11-epoxide in plasma and comparison with HPLC

    NASA Astrophysics Data System (ADS)

    Hemmateenejad, Bahram; Rezaei, Zahra; Khabnadideh, Soghra; Saffari, Maryam

    2007-11-01

    Carbamazepine (CBZ) undergoes enzyme biotransformation through epoxidation with the formation of its metabolite, carbamazepine-10,11-epoxide (CBZE). A simple chemometrics-assisted spectrophotometric method has been proposed for simultaneous determination of CBZ and CBZE in plasma. A liquid extraction procedure was operated to separate the analytes from plasma, and the UV absorbance spectra of the resultant solutions were subjected to partial least squares (PLS) regression. The optimum number of PLS latent variables was selected according to the PRESS values of leave-one-out cross-validation. A HPLC method was also employed for comparison. The respective mean recoveries for analysis of CBZ and CBZE in synthetic mixtures were 102.57 (±0.25)% and 103.00 (±0.09)% for PLS and 99.40 (±0.15)% and 102.20 (±0.02)%. The concentrations of CBZ and CBZE were also determined in five patients using the PLS and HPLC methods. The results showed that the data obtained by PLS were comparable with those obtained by HPLC method.

  3. Validation of an analytical method to determine sulfamides in kidney by HPLC-DAD and PARAFAC2 with first-order derivative chromatograms.

    PubMed

    García, I; Ortiz, M C; Sarabia, L; Aldama, J M

    2007-03-28

    Six sulfamides were extracted from kidney and analysed by high-performance liquid chromatography with diode array detection (HPLC-DAD): sulfadiazine, sulfamethazine, sulfamethoxypyridazine, sulfamethoxazole, sulfadimethoxine and sulfaquinoxaline. Two main difficulties arose in identifying and quantifying the analytes. Firstly, the chromatographic peaks of the matrix interferences overlapped with those of the analytes. The uniqueness property of PARAFAC2 solved this problem. Secondly, the gradient elution caused a baseline drift. The first-order derivative of the chromatograms minimized its effect. The analytical method was validated. As the performance criteria detailed in the European Decision 2002/657/EC are based on specific signals, this paper generalizes those criteria for higher-order and non-specific signals. In this sense the proposed methodology is general and can be applied to any chromatographic method (HPLC or GC) with a detector that provide a multivariate signal (MS, DAD, EC, etc.). PMID:17386777

  4. Standardization of RP-HPLC methods for the detection of the major peanut allergens Ara h 1, Ara h 2 and Ara h 3.

    PubMed

    Singh, Harmit; Cantoria, Mary Jo; Malave, Poonam; Saputra, Denny; Maleki, Soheila

    2016-03-01

    Crude peanut extract (CPE) was analyzed for three major allergens (Ara h 1, h 2, and h 3) using a C12 and a C18 column at two wavelengths (280 and 220nm) and under different solvent conditions. HPLC profiles were compared for retention time, resolution, and peak heights. CPE samples were spiked with pure allergens to identify the peaks corresponding to allergens. The HPLC fractions of corresponding allergens were collected and freeze-dried in order to perform SDS-PAGE and immunoblotting tests. The best method was identified the one with a shorter retention time, better resolution, and greater peak height as compared with the other methods. In general, the peak heights were greater at 220nm than at 280nm. The major disadvantage of the C12 column was the need for two sets of conditions to identify the allergens as compared to the C18 column where all three allergens could be identified in one run. PMID:26471570

  5. Determination of rat serum esterase activities by an HPLC method using S-acetylthiocholine iodide and p-nitrophenyl acetate.

    PubMed

    Koitka, Matthias; Höchel, Joachim; Obst, Detlev; Rottmann, Antje; Gieschen, Hille; Borchert, Hans-Hubert

    2008-10-01

    Establishing esterase assays allows the determination and comparison of esteratic activities of tissues of one organism and between organisms. We have developed a high-performance liquid chromatography (HPLC) assay for the determination of S-acetylthiocholine (ATC) and p-nitrophenyl acetate (NPA) hydrolyzing activities of rat serum esterases based on ion pair chromatography with on-line radiochemical and ultraviolet (UV) detection. ATC is a substrate for cholinesterases, whereas NPA is cleaved by a variety of esterases and other proteins (e.g., cholinesterases, paraoxonase, carboxylesterase, albumin). Both substrates were incubated, simultaneously or separately, with rat serum to explore potential interferences between the enzymatic hydrolyses of the compounds. The ratio of the peak area of the (14)C-labeled substrates to the total peak area of the substrates and their corresponding cleavage products was compared with the UV quantitation of ATC and p-nitrophenolate (NP), the cleavage product of NPA, measured at 230 and 350 nm, respectively. The peak identity of ATC and NP was confirmed by electrospray ionization-tandem mass spectrometry (ESI-MS/MS). The reaction rates of the assays using one substrate or both, as well as using radiochemical or UV detection, were equal. Moreover, the correlation between rat serum volumes and reaction rates was shown for both substrates. In conclusion, one can (i) choose between the two detection methods reliably, (ii) take advantage of monitoring both substrate and product by using radiochemical detection, and (iii) combine both substrates to determine esterase activities in rat serum and probably other biological matrices. PMID:18602882

  6. RP-HPLC method and its validation for the determination of naloxone from a novel transdermal formulation.

    PubMed

    Panchagnula, Ramesh; Sharma, Puneet; Khandavilli, Sateesh; Varma, Manthena V S

    2004-10-01

    The aim of the present work was to develop a simple and reliable liquid chromatographic method for the quantitative determination of naloxone (NLX) in a novel transdermal formulation. Chromatography was carried out by reversed-phase technique on a C-18 column with a mobile phase composed of methanol, acetonitrile and 50 mM phosphate buffer (pH 7) in the proportion of 40:20:40 v/v/v, at a flow rate of 1 ml/min. The UV spectrophotometric determination was performed at 220 nm. This method was found to be specific and accurate with the mean recovery of 98.72% in the range of 2-50 microg/ml, and a run time of 15 min (retention time of NLX 11.3 min). Method was applied for stability testing of novel transdermal formulation developed in our laboratory. Assay content of NLX in the formulation was determined in stability samples and compared with the control samples. Statistical analysis by Student's t-test showed no significant difference between the assay content of NLX in control and test samples at 95% confidence interval. Overall, the proposed method is highly sensitive, precise and accurate and can be used for the reliable quantitation of NLX in developed transdermal formulation with the added advantage of simple procedure. PMID:15474062

  7. Simultaneous free and glycosylated pyridinium crosslink determination in urine: validation of an HPLC-fluorescence method using a deoxypyridinoline homologue as internal standard.

    PubMed

    Monticelli, Elena; Aman, Caroline Stéphanie; Costa, Maria Letizia; Rota, Paola; Bogdan, Daniela; Allevi, Pietro; Cighetti, Giuliana

    2011-09-15

    Pyridinoline (Pyr), deoxypyridinoline (D-Pyr), galactosyl-pyridinoline (Gal-Pyr) and glucosyl-galactosyl pyridinoline (GluGal-Pyr) are enzymatic mature pyridinium crosslinks. Generally, only total Pyr and D-Pyr urinary amounts (free+bound forms) are evaluated by HPLC as indices of bone resorption. This report describes the validation of an HPLC-fluorescence method for the simultaneous evaluation of free Pyr and D-Pyr, together with GluGal-Pyr and Gal-Pyr, in urine of healthy women (n=20, aged 27-41) and girls (n=20, aged 5-10). The use of an unnatural D-Pyr homologue, here proposed for the first time as internal standard, and of pure Pyr, D-Pyr, GluGal-Pyr and Gal-Pyr synthesized to be used as primary calibrators, guarantees method specificity and correct crosslink quantification. Urine, spiked with IS, was solid-phase extracted prior to HPLC analysis. Total Pyr and D-Pyr amounts were also evaluated after urine hydrolysis. The HPLC method was validated for selectivity, sensitivity, linearity, precision, accuracy, recovery and stability for all measured crosslinks. Both free and total Pyr and D-Pyr as well as GluGal-Pyr and Gal-Pyr amounts were significantly higher in girls than in women (p<0.0001), indicating an increased collagen turnover rather than only bone turnover. Gal-Pyr, for the first time evaluated in girls, was under its lower quantification limit (method could be a useful non-invasive technique for studying pathological conditions characterized by modified glycosylation enzyme activity and for more clinical investigation on bone fragility. PMID:21855424

  8. A Generalized Subspace Least Mean Square Method for High-resolution Accurate Estimation of Power System Oscillation Modes

    SciTech Connect

    Zhang, Peng; Zhou, Ning; Abdollahi, Ali

    2013-09-10

    A Generalized Subspace-Least Mean Square (GSLMS) method is presented for accurate and robust estimation of oscillation modes from exponentially damped power system signals. The method is based on orthogonality of signal and noise eigenvectors of the signal autocorrelation matrix. Performance of the proposed method is evaluated using Monte Carlo simulation and compared with Prony method. Test results show that the GSLMS is highly resilient to noise and significantly dominates Prony method in tracking power system modes under noisy environments.

  9. A Method for Deriving Accurate Gas-Phase Abundances for the Multiphase Interstellar Galactic Halo

    NASA Astrophysics Data System (ADS)

    Howk, J. Christopher; Sembach, Kenneth R.; Savage, Blair D.

    2006-01-01

    We describe a new method for accurately determining total gas-phase abundances for the Galactic halo interstellar medium with minimal ionization uncertainties. For sight lines toward globular clusters containing both ultraviolet-bright stars and radio pulsars, it is possible to measure column densities of H I and several ionization states of selected metals using ultraviolet absorption line measurements and of H II using radio dispersion measurements. By measuring the ionized hydrogen column, we minimize ionization uncertainties that plague abundance measurements of Galactic halo gas. We apply this method for the first time to the sight line toward the globular cluster Messier 3 [(l,b)=(42.2d,+78.7d), d=10.2 kpc, z=10.0 kpc] using Far Ultraviolet Spectroscopic Explorer and Hubble Space Telescope ultraviolet spectroscopy of the post-asymptotic giant branch star von Zeipel 1128 and radio observations by Ransom et al. of recently discovered millisecond pulsars. The fraction of hydrogen associated with ionized gas along this sight line is 45%+/-5%, with the warm (T~104 K) and hot (T>~105 K) ionized phases present in roughly a 5:1 ratio. This is the highest measured fraction of ionized hydrogen along a high-latitude pulsar sight line. We derive total gas-phase abundances logN(S)/N(H)=-4.87+/-0.03 and logN(Fe)/N(H)=-5.27+/-0.05. Our derived sulfur abundance is in excellent agreement with recent solar system determinations of Asplund, Grevesse, & Sauval. However, it is -0.14 dex below the solar system abundance typically adopted in studies of the interstellar medium. The iron abundance is ~-0.7 dex below the solar system abundance, consistent with the significant incorporation of iron into interstellar grains. Abundance estimates derived by simply comparing S II and Fe II to H I are +0.17 and +0.11 dex higher, respectively, than the abundance estimates derived from our refined approach. Ionization corrections to the gas-phase abundances measured in the standard way are

  10. Development of On-Line High Performance Liquid Chromatography (HPLC)-Biochemical Detection Methods as Tools in the Identification of Bioactives

    PubMed Central

    Malherbe, Christiaan J.; de Beer, Dalene; Joubert, Elizabeth

    2012-01-01

    Biochemical detection (BCD) methods are commonly used to screen plant extracts for specific biological activities in batch assays. Traditionally, bioactives in the most active extracts were identified through time-consuming bio-assay guided fractionation until single active compounds could be isolated. Not only are isolation procedures often tedious, but they could also lead to artifact formation. On-line coupling of BCD assays to high performance liquid chromatography (HPLC) is gaining ground as a high resolution screening technique to overcome problems associated with pre-isolation by measuring the effects of compounds post-column directly after separation. To date, several on-line HPLC-BCD assays, applied to whole plant extracts and mixtures, have been published. In this review the focus will fall on enzyme-based, receptor-based and antioxidant assays. PMID:22489144

  11. Stability-indicating HPLC method development and structural elucidation of novel degradation products in posaconazole injection by LC-TOF/MS, LC-MS/MS and NMR.

    PubMed

    Yang, Yidi; Zhu, Xi; Zhang, Fei; Li, Wei; Wu, Ying; Ding, Li

    2016-06-01

    Stress testing was carried out under acidic, alkaline, oxidative, thermal and photolytic conditions to evaluate the intrinsic stability of posaconazole injection. A total of four degradation products were detected and the drug was found to be susceptible to oxidative and thermal degradations. Three unknown degradants formed under oxidative stress condition were isolated by preparative HPLC and unambiguously elucidated by LC-TOF/MS, LC-MS/MS, (1)H NMR, (13)C NMR and 2D NMR techniques. Based on the spectrometric and spectroscopic information, these novel degradation products were unequivocally assigned as the N-oxides of posaconazole. Probable mechanisms for the formation of the degradants were proposed. A new and selective HPLC method was developed and validated to separate, detect and quantify all the degradants in posaconazole injection. PMID:27023129

  12. Development and Validation of an HPLC-UV Method for Determination of Eight Phenolic Compounds in Date Palms.

    PubMed

    Al-Rimawi, Fuad; Odeh, Imad

    2015-01-01

    A simple, precise, accurate, and selective method was developed and validated for determination of eight phenolic compounds (gallic acid, p-hydroxybenzoic acid, vanilic acid, caffeic acid, syringic acid, p-coumaric acid, ferulic acid, and sinapic acid) in date palms. Separation was achieved on an RP C18 column using the mobile phase methanol-water with 2% acetic acid (18+82, v/v). This method was validated according to the requirements for new methods, which include accuracy, precision, selectivity, robustness, LOD, LOQ, linearity, and range. The method demonstrated good linearity over the range 1-1000 ppm of gallic acid, p-hydroxybenzoic acid, vanilic acid, caffeic acid, and syringic acid with r2 greater than 0.99, and in the range of 3-1000 ppm for p-coumaric acid, ferulic acid, and sinapic acid with r2 greater than 0.99. The recovery of the eight phenolic compounds ranged from 97.1 to 102.2%. The method is selective because adjacent peaks of phenolic compounds were well separated with good resolution. The degree of reproducibility of the results obtained as a result of small deliberate variations in the method parameters and by changing analytical operators proved that the method is robust and rugged. PMID:26525252

  13. Simultaneous Determination of Aspirin, Dipyridamole and Two of Their Related Impurities in Capsules by Validated TLC-Densitometric and HPLC Methods.

    PubMed

    El-Ragehy, Nariman A; Hassan, Nagiba Y; Tantawy, Mahmoud A; Abdelkawy, Mohamed

    2016-08-01

    Aspirin (ASP) and dipyridamole (DIP) are widely used as a combination in pharmaceutical formulations for treatment of strokes. Many of these formulations are containing tartaric acid as an excipient (in DIP pellets formulation for sustained release), which increases the probability of formation of dipyridamole tartaric acid ester impurity (DIP-I). On the other hand, salicylic acid (SAL) is considered to be one of the synthesis impurities and a degradation product of ASP. In this work, two chromatographic methods, namely, TLC-densitometry and HPLC, have been established and validated for simultaneous determination of ASP, DIP, SAL and DIP-I. Good separation was achieved by using silica gel as stationary phase and toluene-methanol-ethyl acetate (2:3:5, by volume) as mobile phase in the case of TLC-densitometry and Zorbax ODS column with mobile phase consisting of phosphate buffer (pH 3.3)-acetonitrile-triethylamine (40:60:0.03, by volume) for HPLC. Influence of different organic solvents in mobile phase composition has been studied to optimize the separation efficiency in TLC densitometry. Moreover, factors affecting the efficiency of HPLC, like pH of the buffer used, organic solvent ratio in the mobile phase and flow rate, have been carefully studied using one variable at a time approach. Finally, the proposed methods were validated as per ICH guidelines. PMID:27406124

  14. Bioanalytical method development for quantification of ulifloxacin, fenbufen and felbinac in rat plasma by solid-phase extraction (SPE) and HPLC with PDA detection.

    PubMed

    Ferrone, Vincenzo; Carlucci, Maura; Palumbo, Paola; Carlucci, Giuseppe

    2016-05-10

    A procedure based on solid-phase extraction (SPE) followed by high performance liquid chromatography (HPLC) with PDA detection has been developed for the analysis of multiple drugs in rat plasma. The analytes evaluated were ulifloxacin, fenbufen and felbinac. Eight different solid phase extraction cartridges were tested to evaluate their applicability for the isolation of drugs from rat plasma. Comparison were recovery of different drugs and reproducibility. The samples were analyzed by HPLC using a Kinetex C18 EVO column and acetonitrile-10mM ammonium acetate-methanol as the mobile phase under gradient elution conditions. SPE combined with HPLC-PDA allowed the determination of drugs over a linear range of 0.05-15 μg/mL for ulifloxacin while 0.5-50 μg/mL for felbinac and fenbufen, with limit of detection at 0.05 for ulifloxacin and 0.5 for felbinac and fenbufen. Bond Elut Plexa sorbent was found to provide the most effective clean-up, removing the greatest amount of interfering substance and simultaneously ensuring analyte recoveries higher than 93.54% with relative standard deviation (RSD) <10%. The method was applied with good accuracy and precision in the determination of ulifloxacin, fenbufen and felbinac in rat plasma obtained from rats treated with selected drugs. This method permits its application to pharmacokinetic and pharmacodynamic studies of these analytes and will facilitate detailed investigations on the interactions between new fluoroquinolones and fenbufen. PMID:26898973

  15. A validated reversed phase HPLC method for the determination of process-related impurities in almotriptan malate API.

    PubMed

    Kumar, A Phani; Ganesh, V R L; Rao, D V Subba; Anil, C; Rao, B Venugopala; Hariharakrishnan, V S; Suneetha, A; Sundar, B Syama

    2008-03-13

    An isocratic reversed phase liquid chromatographic (RP-LC) method has been developed and subsequently validated for the determination of almotriptan malate and its process-related impurities. Separation was achieved with a Phenomenex, Gemini, C-18 column and sodium phosphate buffer (pH adjusted to 7.6): acetonitrile (80:20, v/v) as eluent, at a flow rate of 1.5 mL/min. UV detection was performed at 227 nm. The method is simple, rapid, selective, accurate and stability indicating. The described method is linear over a range of LOQ, 1.5 ug/mL (150% of the specification limit) for all the process-related impurities. The method precision for the determination of related compounds was below 1.0% R.S.D. The accuracy of the method demonstrated at 4 levels in the range of 25-150% of the specification limit and the recovery of impurities were found to be in the range of 96-102%. The method is useful in the quality control of bulk manufacturing. PMID:18191357

  16. Dissolution profiles of perindopril and indapamide in their fixed-dose formulations by a new HPLC method and different mathematical approaches.

    PubMed

    Gumieniczek, Anna; Mączka, Paulina; Komsta, Łukasz; Pietraś, Rafał

    2015-09-01

    A new HPLC method was introduced and validated for simultaneous determination of perindopril and indapamide. Validation procedure included specificity, sensitivity, robustness, stability, linearity, precision and accuracy. The method was used for the dissolution test of perindopril and indapamide in three fixed-dose formulations. The dissolution procedure was optimized using different media, different pH of the buffer, surfactants, paddle speed and temperature. Similarity of dissolution profiles was estimated using different model-independent and model-dependent methods and, additionally, by principal component analysis (PCA). Also, some kinetic models were checked for dissolved amounts of drugs as a function of time. PMID:26431103

  17. A time-accurate implicit method for chemical non-equilibrium flows at all speeds

    NASA Technical Reports Server (NTRS)

    Shuen, Jian-Shun

    1992-01-01

    A new time accurate coupled solution procedure for solving the chemical non-equilibrium Navier-Stokes equations over a wide range of Mach numbers is described. The scheme is shown to be very efficient and robust for flows with velocities ranging from M less than or equal to 10(exp -10) to supersonic speeds.

  18. A spectrally accurate method for overlapping grid solution of incompressible Navier-Stokes equations

    NASA Astrophysics Data System (ADS)

    Merrill, Brandon E.; Peet, Yulia T.; Fischer, Paul F.; Lottes, James W.

    2016-02-01

    An overlapping mesh methodology that is spectrally accurate in space and up to third-order accurate in time is developed for solution of unsteady incompressible flow equations in three-dimensional domains. The ability to decompose a global domain into separate, but overlapping, subdomains eases mesh generation procedures and increases flexibility of modeling flows with complex geometries. The methodology employs implicit spectral element discretization of equations in each subdomain and explicit treatment of subdomain interfaces with spectrally-accurate spatial interpolation and high-order accurate temporal extrapolation, and requires few, if any, iterations, yet maintains the global accuracy and stability of the underlying flow solver. The overlapping mesh methodology is thoroughly validated using two-dimensional and three-dimensional benchmark problems in laminar and turbulent flows. The spatial and temporal convergence is documented and is in agreement with the nominal order of accuracy of the solver. The influence of long integration times, as well as inflow-outflow global boundary conditions on the performance of the overlapping grid solver is assessed. In a turbulent benchmark of fully-developed turbulent pipe flow, the turbulent statistics with the overlapping grids is validated against published available experimental and other computation data. Scaling tests are presented that show near linear strong scaling, even for moderately large processor counts.

  19. Development and validation of a HPLC method for simultaneous quantitation of gatifloxacin, sparfloxacin and moxifloxacin using levofloxacin as internal standard in human plasma: application to a clinical pharmacokinetic study.

    PubMed

    Srinivas, Nimmagadda; Narasu, Lakshmi; Shankar, B Prabha; Mullangi, Ramesh

    2008-11-01

    A highly selective, sensitive and accurate HPLC method has been developed and validated for the estimation of three fluoroquinolones (FQs) viz., gatifloxacin (GFC), sparfloxacin (SFC) and moxifloxacin (MFC) with 500 microL human plasma using levofloxacin (LFC) as an internal standard (IS). The sample preparation involved simple liquid-liquid extraction of GFC, SFC, MFC and IS from human plasma with ethyl acetate. The resolution of peaks was achieved with phosphate buffer (pH 2.5)-acetonitrile (80:20, v/v) at a flow rate of 1 mL/min on a Kromasil C(18) column. The total chromatographic run time was 18.0 min and the simultaneous elution of GFC, SFC, MFC and IS occurred at approximately 10.8, 12.8, 17.0 and 6.0 min, respectively. The method proved to be accurate and precise at linearity range of 100-10,000 ng/mL with a correlation coefficient (r) of > or =0.999. The limit of quantitation for each of the FQs studied was 100 ng/mL. The intra- and inter-day precision and accuracy values found to be within the assay variability limits as per the FDA guidelines. The developed assay method was applied to a pharmacokinetic study in human volunteers following oral administration of 400 mg GFC tablet. PMID:18655224

  20. Validation of a fast and accurate ch