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Sample records for normal-phase liquid chromatography

  1. Determination of void volume in normal phase liquid chromatography.

    PubMed

    Jiang, Ping; Wu, Di; Lucy, Charles A

    2014-01-10

    Void volume is an important fundamental parameter in chromatography. Little prior discussion has focused on the determination of void volume in normal phase liquid chromatography (NPLC). Various methods to estimate the total void volume are compared: pycnometry; minor disturbance method based on injection of weak solvent; tracer pulse method; hold-up volume based on unretained compounds; and accessible volume based on Martin's rule and its descendants. These are applied to NPLC on silica, RingSep and DNAP columns. Pycnometry provides a theoretically maximum value for the total void volume and should be performed at least once for each new column. However, pycnometry does not reflect the volume of adsorbed strong solvent on the stationary phase, and so only yields an accurate void volume for weaker mobile phase conditions. 1,3,5-Tri-t-butyl benzene (TTBB) results in hold-up volumes that are convenient measures of the void volume for all eluent conditions on charge-transfer columns (RingSep and DNAP), but is weakly retained under weak eluent conditions on silica. Injection of the weak mobile phase component (hexane) may be used to determine void volume, but care must be exercised to select the appropriate disturbance feature. Accessible volumes, that are determined using a homologous series, are always biased low, and are not recommended as a measure of the void volume. Copyright © 2013 Elsevier B.V. All rights reserved.

  2. Separation of some platinum metal 8-hydroxyquinolinates by normal phase high-performance liquid chromatography.

    PubMed

    Alimarinod, I P; Basova, E M; Malykhin, A Y; Bol'shova, T A

    1990-05-01

    The method of normal phase high-performance liquid chromatography has been applied to the separation and determination of Pd(II), Pt(II), Rh(III), Ir(IV), Ru(III) and Os(IV) as chelates with 8-hydroxyquinoline on a 62 x 2 mm column packed with Silasorb 600 5 mu silica gel by elution with methylene chloride-isopropyl alcohol mixture (97:3 v/v). The detection limits (ng per 5 mul), were Pd 0.3, Pt 1.0, Rh 1.0, Ir 5.0, Ru 1.5, Os 25. The separation time was 12 min at a flow-rate of 0.1 ml/min.

  3. Purification of flavonoids from licorice using an off-line preparative two-dimensional normal-phase liquid chromatography/reversed-phase liquid chromatography method.

    PubMed

    Fan, Yunpeng; Fu, Yanhui; Fu, Qing; Cai, Jianfeng; Xin, Huaxia; Dai, Mei; Jin, Yu

    2016-07-01

    An orthogonal (71.9%) off-line preparative two-dimensional normal-phase liquid chromatography/reversed-phase liquid chromatography method coupled with effective sample pretreatment was developed for separation and purification of flavonoids from licorice. Most of the nonflavonoids were firstly removed using a self-made Click TE-Cys (60 μm) solid-phase extraction. In the first dimension, an industrial grade preparative chromatography was employed to purify the crude flavonoids. Click TE-Cys (10 μm) was selected as the stationary phase that provided an excellent separation with high reproducibility. Ethyl acetate/ethanol was selected as the mobile phase owing to their excellent solubility for flavonoids. Flavonoids co-eluted in the first dimension were selected for further purification using reversed-phase liquid chromatography. Multiple compounds could be isolated from one normal-phase fraction and some compounds with bad resolution in one-dimensional liquid chromatography could be prepared in this two-dimensional system owing to the orthogonal separation. Moreover, this two-dimensional liquid chromatography method was beneficial for the preparation of relatively trace flavonoid compounds, which were enriched in the first dimension and further purified in the second dimension. Totally, 24 flavonoid compounds with high purity were obtained. The results demonstrated that the off-line two-dimensional liquid chromatography method was effective for the preparative separation and purification of flavonoids from licorice.

  4. Analysis of amitrole by normal-phase liquid chromatography and tandem mass spectrometry using a sheath liquid electrospray interface.

    PubMed

    Girod, Marion; Delaurent, Corinne; Charles, Laurence

    2006-01-01

    The coupling of normal-phase liquid chromatography to tandem mass spectrometry, previously developed in our laboratory, has been applied to the analysis of amitrole. This coupling utilizes an electrospray interface modified to accommodate the introduction of a make-up solution at the tip of the electrospray probe. A methanolic solution containing 3 mM ammonium acetate delivered at a flow rate of 10 microL . min(-1) was found to be the optimal sheath liquid to promote successful ionization of the amitrole. Protonated molecules, arising from in-source dissociation of ammonium adducts, were subjected to tandem mass spectrometric experiments in a triple-quadrupole instrument. The main fragmentation reactions were characterized and selected to acquire chromatographic data in the multiple reaction monitoring mode. The limit of detection for amitrole was in the ppm range without any preconcentration step. Enhanced efficiency of ion transmission achievable nowadays in mass spectrometers (this analytical configuration was developed with a 15-year-old instrument) is reasonably expected to further improve this detection level. Copyright 2006 John Wiley & Sons, Ltd.

  5. Quantitative analysis of vitamin D3 in a feed using normal phase high pressure liquid chromatography.

    PubMed

    Cohen, H; Lapointe, M

    1979-09-01

    A procedure is described for the separation and quantification of Vitamin D3 from different feeds and premixes. The study was conducted, first using a liquid partition step as a preliminary clean-up after extraction, then chromatography on activated Silica gel 60 before final analysis on a high pressure liquid chromatograph (HPLC) using a LiChrosorb NH2 (10 mu) column and a variable wavelength UV detector set at 264 nm. Total analysis on the HPLC was achieved in fifteen minutes. The detector response curve for an authentic D3 standard was linear using peak areas with a minimum detectable amount being 5 ng. The overall percent recovery of D3 in feeds was 94.4 +/- 2.4%. The minimum detectable amount of D3 in animal feeds was found to be in the region of 2,000 I.U./kg.

  6. Preparation and characterization of neutral poly(ethylene glycol) methacrylate-based monolith for normal phase liquid chromatography.

    PubMed

    Li, Yun; Lee, Milton L; Jin, Jing; Chen, Jiping

    2012-09-15

    A novel porous poly(ethylene glycol) methacrylate-based monolithic column for normal phase liquid chromatography was prepared by thermally initiated polymerization of poly(ethylene glycol) methyl ether methacrylate (PEGMEMA) and ethylene dimethacrylate (EDMA) in the presence of selected porogens. The monolith was macroscopically homogeneous, had low flow resistance, and did not swell or shrink significantly in solvents of different polarities. Inverse size-exclusion data indicate that the monolith had a total porosity of 79.2%, including an external porosity of 69.3% and an internal porosity of 9.9%. Due to its mild polarity (hydrophilicity), the PEG-functionalized monolith could perform traditional normal phase chromatography using non-polar solvents The van Deemter plot demonstrated that the column efficiency of 33,600-34,320 theoretical plates/m could be achieved at a linear flow velocity of 0.9-1.5mm/s. The dual retention capability (both weak hydrophilic and hydrophobic interactions) investigated in this paper explains well why the PEG-functionalized monolith could operate in various chromatographic modes.

  7. Quantitation of ceramides in nude mouse skin by normal-phase liquid chromatography and atmospheric pressure chemical ionization mass spectrometry.

    PubMed

    Liou, Yi-Bo; Sheu, Ming-Thau; Liu, Der-Zen; Lin, Shan-Yang; Ho, Hsiu-O

    2010-06-01

    A sensitive and accurate normal-phase liquid chromatography and atmospheric pressure chemical ionization mass spectrometry (LC-APCI-MS) method for determining the standard ceramide [NS] (Cer[NS]) was developed and validated so as to improve the traditional thin-layer chromatography (TLC) technique and LC-electrospray ionization (ESI)-MS method to profile and quantify ceramides in nude mouse skin. Normal-phase LC-APCI-MS was optimized to separate the nine classes of ceramides presented in the stratum corneum (SC) of nude mouse skin. A normal-phase silica column eluted with the gradient system from heptane:acetone/butanol (90:10, v/v) of 75:25 to 100% acetone/butanol (90:10, v/v) (with each solvent containing 0.1% [v/v] triethylamine and 0.1% [v/v] formic acid) at a flow rate of 0.8 ml/min was found to be optimal for analyzing standard Cer[NS]. The analysis of Cer[NS] was validated and employed as the standard for constructing a calibration curve to quantitate all classes of ceramides. This method was applied to profile the classes and contents of ceramides in the SC of nude mouse skin and proved to be workable. It was concluded that this improved method can be used to directly detect and quantify all classes of ceramides in the SC of nude mouse skin and that it is more convenient and labor-saving than the traditional TLC method.

  8. On-line comprehensive two-dimensional normal-phase liquid chromatography × reversed-phase liquid chromatography for preparative isolation of Peucedanum praeruptorum.

    PubMed

    Wang, Xin-Yuan; Li, Jia-Fu; Jian, Ya-Mei; Wu, Zhen; Fang, Mei-Juan; Qiu, Ying-Kun

    2015-03-27

    A new on-line comprehensive preparative two-dimensional normal-phase liquid chromatography × reversed-phase liquid chromatography (2D NPLC × RPLC) system was developed for the separation of complicated natural products. It was based on the use of a silica gel packed medium-pressure column as the first dimension and an ODS preparative HPLC column as the second dimension. The two dimensions were connected with normal-phase (NP) and reversed-phase (RP) enrichment units, involving a newly developed airflow assisted adsorption (AAA) technique. The instrument operation and the performance of this NPLC × RPLC separation method were illustrated by gram-scale isolation of ethanol extract from the roots of Peucedanum praeruptorum. In total, 19 compounds with high purity were obtained via automated multi-step preparative separation in a short period of time using this system, and their structures were comprehensively characterized by ESI-MS, (1)H NMR, and (13)C NMR. Including two new compounds, five isomers in two groups with identical HPLC and TLC retention values were also obtained and identified by 1D NMR and 2D NMR. This is the first report of an NPLC × RPLC system successfully applied in an on-line preparative process. This system not only solved the interfacing problem of mobile-phase immiscibility caused by NP and RP separation, it also exhibited apparent advantages in separation efficiency and sample treatment capacity compared with conventional methods.

  9. Comprehensive two-dimensional normal-phase liquid chromatography × reversed-phase liquid chromatography for analysis of toad skin.

    PubMed

    Li, Jia-Fu; Yan, Xia; Wu, Yun-Long; Fang, Mei-Juan; Wu, Zhen; Qiu, Ying-Kun

    2017-04-15

    An analytical two-dimensional normal-phase liquid chromatography × reversed-phase liquid chromatography (2D NPLC × RPLC) system was constructed with a newly developed thermal evaporation assisted adsorption (TEAA) interface. This novel TEAA interface with heating temperature above solvent boiling point allowed fast removal of organic NPLC solvent and successfully solved the solvent incompatibility problem between NPLC and RPLC. The system achieved rapid on-line solvent exchange between the two dimensions within a short modulation time of 190 s and was applied in the analysis of an extract from the skin of Bufo bufo gargarizans. This is the first time to realize the on-line comprehensive analysis of a moderate polar natural product by coupling NPLC with reversed phase ultra-high performance liquid chromatography (UHPLC). To be highlighted, with the TEAA interface, the 2D NPLC × RPLC system provided excellent resolution and orthogonality (75.2%), when compared with that of 2D RPLC × RPLC.

  10. High temperature normal phase liquid chromatography of aromatic hydrocarbons on bare zirconia.

    PubMed

    Paproski, Richard E; Liang, Chen; Lucy, Charles A

    2011-11-04

    The normal phase HPLC behavior of a bare zirconia column was studied at temperatures up to 200 °C using a hexane mobile phase. The use of elevated column temperatures significantly decreased the retention of twenty five aromatic model compounds according to the van't Hoff equation (>30-fold decrease for some compounds). Large improvements in peak shape, efficiency (>2.2-fold), aromatic group-type selectivity, and column re-equilibration times (>5-fold) were obtained at elevated temperatures. The thermal decomposition of two polar nitrogen compounds (indole and carbazole) was observed in a hexane/dichloromethane mobile phase at temperatures greater than 100 °C. The first order decomposition of carbazole was studied in further detail. Copyright © 2011 Elsevier B.V. All rights reserved.

  11. Gradient elution in aqueous normal-phase liquid chromatography on hydrosilated silica-based stationary phases.

    PubMed

    Soukup, Jan; Janás, Petr; Jandera, Pavel

    2013-04-19

    The possibility of applying a theoretical model in the prediction of the retention of phenolic acids on hydrosilated silica, in aqueous normal phase mode was studied. The actual gradient of the aqueous component in acetonitrile may fluctuate from the pre-set program, as even the gradient-grade acetonitrile contains some water. Hence, the actual concentration of water during the gradient run is higher than pre-set by the gradient program, which leads to lower than expected sample retention. Furthermore, the actual gradient profile may be affected by an increase in water uptake on a polar column during the gradient run. These effects were investigated using the using frontal analysis method and Karl-Fischer titration, for the determination of water in the initial mobile phase, and in the column effluent. Preferential adsorption of water on the Silica hydride, Diamond hydride, UDC Cholesterol, Bidentate C18, and Phenyl hydride columns can be described by Langmuir isotherms. At the column saturation capacity, less than one monomolecular water layer is adsorbed, with a further decrease in coverage density for modified materials. Parameters of semi-logarithmic and logarithmic model equations, describing the dependence of retention factor on the concentration of water, were determined under isocratic conditions. These parameters and linear gradient profiles corrected for the actual water concentrations were used in calculation of gradient retention data. The corrections for the actual water concentration greatly improved the agreement between the experiment and the predicted gradient elution volumes. Generally, the semi-logarithmic model provides slightly better prediction of the gradient data, with respect to the logarithmic retention model. Copyright © 2013 Elsevier B.V. All rights reserved.

  12. Separation and characterization of bufadienolides in toad skin using two-dimensional normal-phase liquid chromatography×reversed-phase liquid chromatography coupled with mass spectrometry.

    PubMed

    Zhang, Yun; Jin, Hongli; Li, Xiaolong; Zhao, Jianqiang; Guo, Xiujie; Wang, Jixia; Guo, Zhimou; Zhang, Xiuli; Tao, Yanduo; Liu, Yanfang; Chen, Deliang; Liang, Xinmiao

    2016-07-15

    Bufadienolides possess various bioactivities especially antitumor. Due to the high structural diversity, the separation of bufadienolides often suffers from coelution problem on conventional RP columns. In this work, an off-line two-dimensional normal-phase liquid chromatography×reversed-phase liquid chromatography (2D-NPLC×RPLC) method was developed to separate and characterize bufadienolides in toad skin. Several RP and NP columns were evaluated with five reference bufadienlides. The XUnion C18 and XAmide columns exhibited superior chromatographic performances for bufadienlide separation, and were selected in RPLC and NPLC, respectively. RPLC was used in the second-dimension for the good compatibility with MS, while NPLC was adopted in the first-dimension. The orthogonality of the 2D-NPLC×RPLC system was investigated by the geometric approach using fifteen bufadienolide mixtures. The result was 49.6%, demonstrating reasonable orthogonality of this 2D-LC system. By combining the 2D-LC system with MS, 64 bufadienlides including 33 minor ones and 11 pairs of isomers in toad skin were identified. This off-line 2D-NPLC×RPLC allowed to solve the coelution problem of bufadienlides in one-dimension RPLC, and thus facilitated the identification significantly. Copyright © 2015 Elsevier B.V. All rights reserved.

  13. Quantitation of a de-fluorinated analogue of casopitant mesylate by normal-phase liquid chromatography/mass spectrometry.

    PubMed

    Dams, Riet; Bernabe, Elena; Nicoletti, Anna; Loda, Claudio; Martini, Luca; Papini, Damiano

    2010-09-15

    The introduction of Quality by Design (QbD) in Drug Development has resulted in a greater emphasis on chemical process understanding, in particular on the origin and fate of impurities. Therefore, the identification and quantitation of low level impurities in new Active Pharmaceutical Ingredients (APIs) play a crucial role in project progression and this has created a greater need for sensitive and selective analytical methodology. Consequently, scientists are constantly challenged to look for new applications of traditional analytical techniques. In this context a normal-phase liquid chromatography/electrospray ionization mass spectrometry (LC/ESI-MS) method was developed to determine the amount of a de-fluorinated analogue impurity in Casopitant Mesylate, a new API under development in GlaxoSmithKline, Verona. Normal-phase LC provided the selectivity needed between our target analyte and Casopitant, while a single quadrupole mass spectrometer was used to ensure the sensitivity needed to detect the impurity at <0.05%w/w. Standard solutions and samples were prepared in heptane/ethanol (50:50, v/v) containing 1% of 2 M NH(3) in ethanol; the mobile phase consisted of heptane/ethanol (95:5, v/v) with isocratic elution (flow rate: 1.0 mL/min, total run time: 23 min). To allow the formation of ions in solutions under normal-phase (apolar) conditions, a post-column infusion of a solution of 0.1% v/v of formic acid in methanol was applied (flow rate: 200 microL/min). The analysis was carried out in positive ion mode, monitoring the impurity by single ion monitoring (SIM). The method was fully validated and its applicability was demonstrated by the analysis of real-life samples. This work is an example of the need for selective and accurate methodology during the development of a new chemical entity in order to develop an appropriate control strategy for impurities to ultimately ensure patient safety. Copyright 2010 John Wiley & Sons, Ltd.

  14. Chromatographic performance of synthetic polycrystalline diamond as a stationary phase in normal phase high performance liquid chromatography.

    PubMed

    Peristyy, Anton; Paull, Brett; Nesterenko, Pavel N

    2015-04-24

    The chromatographic properties of high pressure high temperature synthesised diamond (HPHT) are investigated in normal phase mode of high performance liquid chromatography. Purified nonporous irregular shape particles of average particles size 1.2 μm and specific surface area 5.1 m(2) g(-1) were used for packing 100×4.6 mm ID or 50×4.6 mm ID stainless steel columns. The retention behaviour of several classes of compounds including alkyl benzenes, polyaromatic hydrocarbons (PAH), alkylphenylketones, phenols, aromatic acids and bases were studied using n-hexane-2-propanol mixtures as mobile phase. The results are compared with those observed for microdispersed sintered detonation nanodiamond (MSDN) and porous graphitic carbon (PGC). HPHT diamond revealed distinctive separation selectivity, which is orthogonal to that observed for porous graphitic carbon; while selectivities of HPHT diamond and microdispersed sintered detonation nanodiamonds are similar. Owing to non-porous particle nature, columns packed with high pressure high temperature diamond exhibited excellent mass transfer and produce separations with maximum column efficiency of 128,200 theoretical plates per meter.

  15. Normal phase high-performance liquid chromatography method for the determination of tocopherols and tocotrienols in cereals.

    PubMed

    Panfili, Gianfranco; Fratianni, Alessandra; Irano, Mario

    2003-07-02

    The eight vitamers of vitamin E (alpha-, beta-, gamma-, and delta-tocopherols and -tocotrienols) have different antioxidant and biological activities and have different distributions in foods. Some cereals, especially oat, rye, and barley, are good sources of tocotrienols. A fast procedure for the determination of tocopherols and tocotrienols (tocols) in cereal foods was developed. It involves sample saponification and extraction followed by normal phase high-performance liquid chromatography (HPLC). The results have been compared with those found by direct extraction without saponification. The method is sensitive and selective enough to be tested on a wide variety of cereal samples. The highest tocol levels were found in soft wheat and barley ( approximately 75 mg/kg of dry weight). beta-Tocotrienol is the main vitamer found in hulled and dehulled wheats (from 33 to 43 mg/kg of dry weight), gamma-tocopherol predominates in maize (45 mg/kg of dry weight) ), and alpha-tocotrienol predominates in oat and barley (56 and 40 mg/kg of dry weight, respectively).

  16. Determination of alkenes in cracking products by normal-phase high-performance liquid chromatography-diode array detection.

    PubMed

    Tomić, Tatjana; Babić, Sandra; Nasipak, Nada Uzorinac; Ruszkowski, Maja Fabulić; Skrobonja, Livijana; Kastelan-Macan, Marija

    2009-05-01

    Alkene content determinations in fluid catalytic cracking (FCC) liquid products were performed by means of normal-phase high-performance liquid chromatography (NP-HPLC) with diode array detection (UV/DAD). Separation of alkenes from aromatic hydrocarbons was performed on amino-modified silica gel column with n-heptane as mobile phase. The column has a little affinity to alkenes and saturated hydrocarbons and a pronounced affinity to aromatic compounds. The problem of alkenes and saturates co-elution on this column type was overcome with the detection system, UV/DAD, sensitive and selective to alkenes, while saturates are inactive in UV field. Total alkene content was determined as a sum of mono- and dialkene groups quantified by external standard method. Validation and verification of the developed method proved their applicability. The following criteria were used to validate the HPLC-DAD method: selectivity, linearity, precision, limits of detection and quantification. Alkene contents were quantified with the external standard method of wide calibration range, so both low and high alkene contents can be determined by the single calibration. Correlation coefficients were higher than 0.99. Precision was evaluated as repeatability and intermediary precision with relative standard deviations less than 5%. Some structural investigation of alkene groups was performed to confirm the assumption. Proposed method was compared with certified NMR method. Six commercial motor gasoline samples were analyzed by these two methods. Obtained results indicate good agreement between alkene content determined by both methods. The developed method was applied to the determination of alkene content in liquid FCC products in the boiling range from 70 degrees C to 190 degrees C.

  17. Differentiation of isomeric N-glycan structures by normal-phase liquid chromatography-MALDI-TOF/TOF tandem mass spectrometry.

    PubMed

    Maslen, Sarah; Sadowski, Pawel; Adam, Alex; Lilley, Kathryn; Stephens, Elaine

    2006-12-15

    The detailed characterization of protein N-glycosylation is very demanding given the many different glycoforms and structural isomers that can exist on glycoproteins. Here we report a fast and sensitive method for the extensive structure elucidation of reducing-end labeled N-glycan mixtures using a combination of capillary normal-phase HPLC coupled off-line to matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) and TOF/TOF-MS/MS. Using this method, isobaric N-glycans released from honey bee phospholipase A2 and Arabidopsis thaliana glycoproteins were separated by normal-phase chromatography and subsequently identified by key fragment ions in the MALDI-TOF/TOF tandem mass spectra. In addition, linkage and branching information were provided by abundant cross-ring and "elimination" fragment ions in the MALDI-CID spectra that gave extensive structural information. Furthermore, the fragmentation characteristics of N-glycans reductively aminated with 2-aminobenzoic acid and 2-aminobenzamide were compared. The identification of N-glycans containing 3-linked core fucose was facilitated by distinctive ions present only in the MALDI-CID spectra of 2-aminobenzoic acid-labeled oligosaccharides. To our knowledge, this is the first MS/MS-based technique that allows confident identification of N-glycans containing 3-linked core fucose, which is a major allergenic determinant on insect and plant glycoproteins.

  18. Phenolic profiling of rooibos using off-line comprehensive normal phase countercurrent chromatography×reversed phase liquid chromatography.

    PubMed

    Walters, Nico A; de Villiers, André; Joubert, Elizabeth; de Beer, Dalene

    2017-03-24

    Limited performance of one dimensional chromatographic methods provides the incentive for the development of multidimensional chromatographic techniques for the analysis of complex mixtures. Rooibos (Aspalathus linearis) represents such a complex sample, containing a range of phenolic compounds that cannot be separated and identified using a single chromatographic technique within a reasonable run time. By implementing NP high performance countercurrent chromatography (NP-HPCCC) in the first dimension ((1)D) and RP ultra-high pressure LC (RP-UHPLC) in the second dimension ((2)D), a highly orthogonal (∼80%) off-line comprehensive two-dimensional separation of rooibos phenolic compounds was achieved in a total analysis time of 17h. The use of a gradient for the (1)D HPCCC separation ensured a good spread of relatively polar flavonoid di-C-glycosides and less polar mono- and di-O-glycosides, while the highly efficient UHPLC method was able to separate compounds eluting in the same (1)D fraction. Analysis of green ("unfermented") and traditional "fermented" rooibos samples enabled tentative identification of 39 phenolic compounds based on UV-vis and MS characteristics, of which 18 have not previously been reported in rooibos. Scolymoside (a flavone), hesperidin (a flavanone) and phloretin-3',5'-di-C-β-d-glucopyranoside (a dihydrochalcone) were identified for the first time in rooibos by comparison with authentic reference standards.

  19. A rapid method for the simultaneous quantification of the major tocopherols, carotenoids, free and esterified sterols in canola (Brassica napus) oil using normal phase liquid chromatography.

    PubMed

    Flakelar, Clare L; Prenzler, Paul D; Luckett, David J; Howitt, Julia A; Doran, Gregory

    2017-01-01

    A normal phase high performance liquid chromatography (HPLC) method was developed to simultaneously quantify several prominent bioactive compounds in canola oil vis. α-tocopherol, γ-tocopherol, δ-tocopherol, β-carotene, lutein, β-sitosterol, campesterol and brassicasterol. The use of sequential diode array detection (DAD) and tandem mass spectrometry (MS/MS) allowed direct injection of oils, diluted in hexane without derivatisation or saponification, greatly reducing sample preparation time, and permitting the quantification of both free sterols and intact sterol esters. Further advantages over existing methods included increased analytical selectivity, and a chromatographic run time substantially less than other reported normal phase methods. The HPLC-DAD-MS/MS method was applied to freshly extracted canola oil samples as well as commercially available canola, palm fruit, sunflower and olive oils. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. Analysis of oil-biodiesel samples by high performance liquid chromatography using the normal phase column of new generation and the evaporative light scattering detector.

    PubMed

    Fedosov, Sergey N; Fernandes, Natalia A; Firdaus, Mohd Y

    2014-01-24

    Conversion of vegetable oil to biodiesel is usually monitored by gas chromatography. This is not always convenient because of (i) an elaborate derivatization of the samples; (ii) inhibition of this process by methanol and water; (iii) low stability of the derivatives under storage. HPLC methods are apparently more convenient, but none of the described variants had won a wide recognition so far. This can be ascribed to the problems of reproducibility (in the case of normal phase chromatography) and limited separation of some analytes (in the case of reverse phase chromatography). Here we report an HPLC procedure suitable for separation of biodiesel, free fatty acids, glycerides, glycerol and lecithin. The normal phase column of new generation (Poroshell 120 HILIC) and the novel gradient were used. The method was tested on both the artificial mixtures and the crude reaction samples. Elution of the analytes was monitored by an evaporative light scattering detector. This method is usually confined to a very limited range of masses, where only a part of the complex calibration curve is used. We have analyzed the light scattering signal within a very broad range of masses, whereupon the calibration curves were produced. The data were approximated by the appropriate equations used afterward to recalculate the signal to the mass in a convenient way. An experimental conversion of rapeseed oil to biodiesel was performed by a liquid lipase formulation. This process was monitored by HPLC to illustrate advantages of the suggested registration method.

  1. Determination of zafirlukast, a selective leukotriene antagonist, human plasma by normal-phase high-performance liquid chromatography with fluorescence detection.

    PubMed

    Bui, K H; Kennedy, C M; Azumaya, C T; Birmingham, B K

    1997-08-15

    A high-performance liquid chromatographic (HPLC) method was developed for the determination of zafirlukast, a selective peptide leukotriene receptor antagonist, in human plasma. Zafirlukast and the internal standard, ICI 198 707, were extracted from deproteinated plasma samples using large reservoir C18 solid-phase extraction columns and analyzed by normal-phase liquid chromatography with fluorescence detection. The method had a lower limit of quantitation of 0.75 ng/ml and a linear calibration curve in the range of 0.75 to 200 ng/ml. The absolute recovery of zafirlukast was > 90%, and the within-day and between-day relative standard deviations were < 9%. The utility of the method in the characterization of the plasma concentration-time profiles of zafirlukast in clinical studies was demonstrated.

  2. Determination of famotidine in low-volume human plasma by normal-phase liquid chromatography/tandem mass spectrometry.

    PubMed

    Zhong, L; Eisenhandler, R; Yeh, K C

    2001-07-01

    A rapid, sensitive and robust assay procedure using liquid chromatography coupled with tandem mass spectrometry (LC/MS/MS) for the determination of famotidine in human plasma and urine is described. Famotidine and the internal standard were isolated from plasma samples by cation-exchange solid-phase extraction with benzenesulfonic acid (SCX) cartridges. The urine assay used direct injection of a diluted urine sample. The chromatographic separation was accomplished by using a BDS Hypersil silica column with a mobile phase of acetonitrile-water containing trifluoroacetic acid. The MS/MS detection of the analytes was set in the positive ionization mode using electrospray ionization for sample introduction. The analyte and internal standard precursor-product ion combinations were monitored in the multiple-reaction monitoring mode. Assay calibration curves were linear in the concentration range 0.5--500 ng ml(-1) and 0.05--50 microg ml(-1) in plasma and urine, respectively. For the plasma assay, a 100 microl sample aliquot was subjected to extraction. To perform the urine assay, a 50 microl sample aliquot was used. The intra-day relative standard deviations at all concentration levels were <10%. The inter-day consistency was assessed by running quality control samples during each daily run. The limit of quantification was 0.5 ng ml(-1) in plasma and 0.05 microg ml(-1) in urine. The methods were utilized to support clinical pharmacokinetic studies in infants aged 0-12 months.

  3. Application of Diol column under adsorption and mixed partition-adsorption normal-phase liquid chromatography mode for the separation of purines and pyrimidines.

    PubMed

    Kazoka, H

    2008-05-02

    The diol-bonded phase (column LiChrospher 100 Diol) has been studied for the separation of some purines and pyrimidines under normal-phase liquid chromatography (NPLC) conditions. Retention time, column efficiency, and selectivity of column with diol-phase were compared to those of unmodified silica (column LiChrospher SI-60). It was established that under adsorption NPLC mode application of diol-phase can reduce the separation time and a little improve the column efficiency. Significant improvement of the column efficiency for polar solutes is observed if mixed partition-adsorption NPLC mode is used. The investigation has shown that application of diol-phase instead of bare silica is useful not only under adsorption, but also under mixed partition-adsorption mode if the system with specific selectivity is necessary.

  4. Development of LC chiral methods for neutral pharmaceutical related compounds using reversed phase and normal phase liquid chromatography with different types of polysaccharide stationary phases.

    PubMed

    Zhou, Lili; Welch, Chris; Lee, Clair; Gong, Xiaoyi; Antonucci, Vincent; Ge, Zhihong

    2009-05-01

    The enantioselectivity of a collection of neutral pharmaceutical compounds on six different types of polysaccharide chiral stationary phases (CSPs), Chiralpak AD (and AD-RH), Chiralcel OD (and OD-RH), Chiralpak OJ (and OJ-R), Chiralcel AS (and AS-RH), Sepapak-2 and Sepapak-4 are compared using reversed phase (RPLC) and normal phase liquid chromatography (NPLC). Screening strategies for maximizing the probability of achieving an initial chiral separation hit for neutral compounds using both RPLC and NPLC are described. Further method optimizations are demonstrated by modifying parameters such as organic modifier composition, eluent pH or CSP particle size. Several practical examples of the application of chiral methods for the study of synthetic reaction mixtures are presented. The most critical validation aspects, including limit of detection, specificity, and ruggedness, are also briefly presented.

  5. Highly sensitive and rapid normal-phase chiral screen using high-performance liquid chromatography-atmospheric pressure ionization tandem mass spectrometry (HPLC/MS).

    PubMed

    de la Puente, María Luz

    2004-11-05

    In the last years, there has been an increasing demand on the development of quantitative assays for determination of enantiopurity. Herein, we present a methodology based on a direct linking of an atmospheric pressure ionization mass spectrometer (MS-APCI) with a high-performance liquid chromatography HPLC (DAD) system, operated under normal-phase mode and without post-column addition of MS-compatible solvents, which provides the high specificity/selectivity (identification of isomers in complex mixtures) and accuracy (1-2% area level) required for daily chiral studies. As result of the success of our screen, the preparation of individual enantiomers or the racemic mixture in our Drug Discovery Research Laboratories at Lilly, Spain is usually not required. Therefore, additional non-valuable synthetic work is eliminated.

  6. Coal liquefaction process streams characterization and evaluation: High performance liquid chromatography (HPLC) of coal liquefaction process streams using normal-phase separation with uv diode array detection

    SciTech Connect

    Clifford, D.J.; McKinney, D.E.; Hou, Lei; Hatcher, P.G.

    1994-01-01

    This study demonstrated the considerable potential of using two-dimensional, high performance liquid chromatography (HPLC) with normal-phase separation and ultraviolet (UV) diode array detection for the examination of filtered process liquids and the 850{degrees}F{sup {minus}} distillate materials derived from direct coal liquefaction process streams. A commercially available HPLC column (Hypersil Green PAH-2) provided excellent separation of the complex mixture of polynuclear aromatic hydrocarbons (PAHs) found in coal-derived process streams process. Some characteristics of the samples delineated by separation could be attributed to processing parameters. Mass recovery of the process derived samples was low (5--50 wt %). Penn State believes, however, that, improved recovery can be achieved. High resolution mass spectrometry and gas chromatography/mass spectrometry (GC/MS) also were used in this study to characterize the samples and the HPLC fractions. The GC/MS technique was used to preliminarily examine the GC-elutable portion of the samples. The GC/MS data were compared with the data from the HPLC technique. The use of an ultraviolet detector in the HPLC work precludes detecting the aliphatic portion of the sample. The GC/MS allowed for identification and quantification of that portion of the samples. Further development of the 2-D HPLC analytical method as a process development tool appears justified based on the results of this project.

  7. Proanthocyanidins in wild sea buckthorn (Hippophaë rhamnoides) berries analyzed by reversed-phase, normal-phase, and hydrophilic interaction liquid chromatography with UV and MS detection.

    PubMed

    Kallio, Heikki; Yang, Wei; Liu, Pengzhan; Yang, Baoru

    2014-08-06

    A rapid and sensitive method for profiling of proanthocyanidins (PAs) of sea buckthorn (Hippophaë rhamnoides) berries was established based on aqueous, acidified acetone extraction. The extract was purified by Sephadex column chromatography and analyzed using reversed-phase, normal-phase, and hydrophilic interaction liquid chromatography (HILIC). Negative ion electrospray ionization mass spectrometry (ESI-MS) in single ion recording (SIR) and full scan modes combined with UV detection were used to define the combinations and ratios of PA oligomer classes. PAs with degree of polymerization from 2 to 11 were detected by HILIC-ESI-MS. Quantification of dimeric, trimeric, and tetrameric PAs was carried out with ESI-MS-SIR, and their molar proportions were 40, 40, and 20%, respectively. Only B-type PAs were found, and (epi)gallocatechins were the main monomeric units. More than 60 combinations of (epi)catechins and (epi)gallocatechins of proanthocyanidin dimers and trimers were found. A majority of the PAs were shown to be higher polymers based on the HILIC-UV analysis.

  8. Analysis of the enantiomers of VX using normal-phase chiral liquid chromatography with atmospheric pressure chemical ionization-mass spectrometry.

    PubMed

    Smith, J R

    2004-01-01

    The chemical warfare nerve agent O-ethyl S-(2-diisopropylaminoethyl) methylphosphonothioate (VX) is a mixture of two enantiomers resulting from the chiral center at the phosphorus atom. Significant differences exist in the reported toxicity and acetylcholinesterase inhibition rates of the two enantiomers. This makes the ability to distinguish between them desirable for either toxicological studies or the development of antidotal therapies. Using a Chiralcel OD-H column with normal-phase liquid chromatography, the enantiomers were baseline resolved in less than 7 min. Atmospheric pressure chemical ionization was utilized as the interface between a liquid chromatograph and mass spectrometer. The mass spectra of the two enantiomers were virtually identical. The protonated molecule was readily observed at m/z 268. VX was incubated with human plasma for 13 min, followed by hexane extraction. The areas of the first and second eluting VX enantiomers decreased by approximately 40% and 6%, respectively, when compared with VX-spiked plasma samples that were not allowed an incubation phase. Currently, research by others has been directed towards the identification, isolation, and possible modification of enzymes capable of hydrolyzing VX. The method presented here provides an analytical tool capable of monitoring the stereospecificity of enzymes that react with VX.

  9. Normal phase-liquid chromatography-tandem mass spectrometry with atmospheric pressure photoionization for the purity assessment of 17β-estradiol.

    PubMed

    Josephs, Ralf Dieter; Daireaux, Adeline; Choteau, Tiphaine; Westwood, Steven; Wielgosz, Robert Ian

    2015-04-01

    A normal phase-liquid chromatography-hybrid tandem mass spectrometry (NP-LC-MS/MS) method utilizing atmospheric pressure photoionization (APPI) without dopant has been developed and implemented for the simultaneous determination of several estrogenic steroid hormones. The combination of both NP-LC and APPI-MS/MS tolerates the use of solvents that have the advantages of being self-doping for APPI and, at the same time, inhibit the in situ formation of estrogen dimers as frequently observed for conventional reversed phase (RP)-LC methods. The NP-LC-APPI-MS/MS method has been validated in-house, and its performance characteristics (linearity, repeatability, limits of detection, etc.) were assessed for use in the quantification of estrogens. Moreover, the method was used to characterize and determine the inherent related structure impurities in batches of β-estradiol, required for the establishment of reference measurement systems for clinical chemistry and laboratory medicine, which served as candidate reference material for an organic purity assessment interlaboratory study (CCQM-K55.a) organized by the International Bureau of Weights and Measures (BIPM) Chemistry Department and carried out within the framework of the Organic Analysis Working Group (OAWG) of the Consultative Committee for Amount of Substance-Metrology in Chemistry (CCQM).

  10. Analysis of phospholipid species in human blood using normal-phase liquid chromatography coupled with electrospray ionization ion-trap tandem mass spectrometry.

    PubMed

    Uran, S; Larsen, A; Jacobsen, P B; Skotland, T

    2001-07-15

    A narrow-bore normal-phase high-performance liquid chromatography (HPLC) method was developed for separation of phospholipid classes in human blood. The separation was obtained using an HPLC diol column and a gradient of chloroform and methanol with 0.1% formic acid, titrated to pH 5.3 with ammonia and added 0.05% triethylamine. The HPLC system was coupled on-line with an electrospray ionisation ion-trap mass spectrometer. Chromatographic baseline separation was obtained between phosphatidylglycerol, phosphatidylcholine, phosphatidylethanolamine, lyso-phosphatidylcholine, phosphatidylinositol and phosphatidylserine, eluting in that order. The total run time was 30 min. Plasmalogen phosphatidylethanolamine and sphingomyelin, which both are substances with structural similarities to the glycerophospholipids, had similar retention time as phosphatidylethanolamine, but were well separated from the other glycerophospholipid classes. The species from each class were identified using MS2 or MS3, which forms characteristic lyso-fragments. The combination of lyso-fragment mass, molecular ion and chromatographic retention time was used to identify each species, including 20 species of phosphatidylglycerol. The mass spectra obtained for the phospholipid classes are presented. Using this system 17 disaturated phospholipid species not earlier described to be present in blood were identified. The limit of detection varied between different phospholipid classes and was in the range 0.1-5 ng of injected substance.

  11. Retentivity, selectivity and thermodynamic behavior of polycyclic aromatic hydrocarbons on charge-transfer and hypercrosslinked stationary phases under conditions of normal phase high performance liquid chromatography.

    PubMed

    Jiang, Ping; Lucy, Charles A

    2016-03-11

    Charge-transfer and hypercrosslinked polystyrene phases offer retention and separation for polycyclic aromatic hydrocarbons (PAHs) and thus have potential for petroleum analysis. The size, shape and planarity selectivity for PAH standards on charge-transfer (DNAP column) and hypercrosslinked polystyrene (HC-Tol and 5HGN columns) phases are different under normal phase liquid chromatography (NPLC). The HC-Tol column behaves like a conventional NPLC column with low retention of PAHs. Retention of PAHs on the DNAP and 5HGN are strong and increases with the number of aromatic rings. The main retention mechanism is through π-π interactions and dipole-induced dipole interaction. Thermodynamics indicates that the retention mechanism of PAHs remains unchanged over the temperature range 20-60°C. In addition, on either DNAP or 5HGN column, both linear and bent PAHs are retained through the same mechanism. But DNAP possesses smaller π-π interaction and higher planarity selectivity than 5HGN for PAHs. This is suggestive that DNAP interacts with PAHs through a disordered phase arrangement, while 5HGN behaves as an ordered adsorption phase. Copyright © 2016 Elsevier B.V. All rights reserved.

  12. Sample handling and contamination encountered when coupling offline normal phase high performance liquid chromatography fraction collection of petroleum samples to Fourier transform ion cyclotron resonance mass spectrometry.

    PubMed

    Oro, Nicole E; Whittal, Randy M; Lucy, Charles A

    2012-09-05

    Normal phase high performance liquid chromatography (HPLC) is used to separate a gas oil petroleum sample, and the fractions are collected offline and analyzed on a high resolution Fourier Transform Ion Cyclotron Resonance Mass Spectrometer (FT-ICR MS). The separation prior to MS analysis dilutes the sample significantly; therefore the fractions need to be prepared properly to achieve the best signal possible. The methods used to prepare the HPLC fractions for MS analysis are described, with emphasis placed on increasing the concentration of analyte species. The dilution effect also means that contamination in the MS spectra needs to be minimized. The contamination from molecular sieves, plastics, soap, etc. and interferences encountered during the offline fraction collection process are described and eliminated. A previously unreported MS contamination of iron formate clusters with a 0.8 mass defect in positive mode electrospray is also described. This interference resulted from the stainless steel tubing in the HPLC system. Contamination resulting from what has tentatively been assigned as palmitoylglycerol and stearoylglycerol was also observed; these compounds have not previously been reported as contaminant peaks. Copyright © 2012 Elsevier B.V. All rights reserved.

  13. Enantioselective determination of cetirizine in human plasma by normal-phase liquid chromatography-atmospheric pressure chemical ionization-tandem mass spectrometry.

    PubMed

    Kang, Seung Woo; Jang, Hae Jong; Moore, Victor S; Park, Ji-Young; Kim, Kyoung-Ah; Youm, Jeong-Rok; Han, Sang Beom

    2010-12-15

    A highly sensitive and enantioselective method has been developed and validated for the determination of levocetirizine [(R)-cetirizine] in human plasma by normal-phase liquid chromatography coupled to tandem mass spectrometry with an atmospheric pressure chemical ionization (APCI) interface in the positive ion mode. Enantioselective separation was achieved on a CHIRALPAK AD-H column using an isocratic mobile phase consisting of a mixture of n-hexane, ethyl alcohol, diethylamine, and acetic acid (60:40:0.1:0.1, v/v/v/v). Levocetirizine-D(8) was used as an internal standard (IS). Levocetirizine and the IS were detected by multiple-reaction monitoring (MRM). Mass transitions of analyte and IS were m/z 389.2→201.1 and 397.2→201.1, respectively. Under optimized analytical conditions, a baseline separation of two enantiomers and IS was obtained in less than 11 min. Samples were prepared by a simple two-step extraction by protein precipitation using acetonitrile followed by liquid-liquid extraction with a n-hexane-dichloromethane mixture (50:50, v/v). The standard curve for levocetirizine was linear (r(2)>0.995) in the concentration range 0.5-300 ng/mL. Recovery was between 97.0 and 102.2% at low, medium, and high concentration. The limit of quantification (LOQ) was 0.5 ng/mL. Other method validation parameters, such as precision, accuracy, and stability, were very satisfactory. Finally, the proposed method was successfully applied to the study of enantioselective oral pharmacokinetics of levocetirizine in healthy Korean volunteers.

  14. Normal phase liquid chromatography coupled to quadrupole time of flight atmospheric pressure chemical ionization mass spectrometry for separation, detection and mass spectrometric profiling of neutral sphingolipids and cholesterol.

    PubMed

    Farwanah, Hany; Wirtz, Jennifer; Kolter, Thomas; Raith, Klaus; Neubert, Reinhard H H; Sandhoff, Konrad

    2009-10-01

    Many lipidomic approaches focus on investigating aspects of sphingolipid metabolism. Special emphasis is put on neutral sphingolipids and cholesterol and their interaction. Such an interest is attributed to the fact that those lipids are altered in a series of serious disorders including various sphingolipidoses. High performance thin-layer chromatography (HPTLC) has become a widely used technique for lipid analysis. However, mass spectrometric profiling is irreplaceable for gaining an overview about the various molecular species within a lipid class. In this work we have developed a sensitive method based on a gradient normal phase high performance liquid chromatography (HPLC) coupled to quadrupole time of flight (QTOF) atmospheric pressure chemical ionization mass spectrometry (APCI-MS) in positive mode, which for the first time enables separation, on-line detection, and mass spectrometric profiling of multiple neutral sphingolipids including ceramide, glucosylceramide, lactosylceramide, globotriaosylceramide, globotetraosylceramide, sphingomyelin as well as cholesterol within less than 15min. An important advantage of the presented HPLC/APCI-MS approach is that the separation pattern emulates the one obtained by an optimized HPTLC method with a multiple stage development. Thus, the lipid classes previously separated and quantified by HPTLC can be easily screened regarding their mass spectrometric profiles by HPLC/APCI-MS. In addition, the selected ionization conditions enable in-source fragmentation providing useful structural information. The methods (HPLC/APCI-MS and the optimized HPTLC) were applied for the analysis of the mentioned lipids in human fibroblasts. This approach is aimed basically at investigators who perform studies based on genetic modifications or treatment with pharmacological agents leading to changes in the biochemical pathways of neutral sphingolipids and cholesterol. In addition, it can be of interest for research on disorders related to

  15. Specific detection and quantification of palmitoyl-stearoyl-phosphatidylserine in human blood using normal-phase liquid chromatography coupled with electrospray mass spectrometry.

    PubMed

    Hvattum, E; Larsen, A; Uran, S; Michelsen, P M; Skotland, T

    1998-09-25

    A narrow-bore normal-phase high-performance liquid chromatography (HPLC) method was developed for separation of phospholipid classes using an HPLC diol column and a gradient of chloroform and methanol with 0.2% formic acid titrated to pH 5.3 with ammonia. The HPLC system was coupled on-line with an electrospray mass spectrometry (ES-MS) or electrospray tandem mass spectrometry (ES-MS-MS) system and the separation of several major phospholipid classes was shown. The molecular species of some phospholipid classes in human blood were qualitatively determined. A method was further developed for specific determination of a molecular species from phosphatidylserine, palmitoyl-stearoyl-phosphatidylserine (PSPS), in human blood using HPLC-ES-MS. The analyses were performed by single ion monitoring of the [M-H]- molecular ions of PSPS and an internal standard, dipalmitoyl-phosphatidylserine. The limit of quantification of the method was 1.2 ng of PSPS. The calibration curve ranged from 0.12 to 5.81 microg/ml of PSPS dissolved in the mobile phase. The curve was fitted to a second-order polynomial equation and found to be highly reproducible. Analysis of control samples was found to be reproducible with a between-series precision below 9.2% R.S.D. The amount of endogenous PSPS in human blood was determined in 13 subjects and found to range from 1.73 to 3.09 microg/ml. The identity of endogenous PSPS was confirmed by HPLC-ES-MS-MS.

  16. Simultaneous Analysis of Tertiary Butylhydroquinone and 2-tert-Butyl-1,4-benzoquinone in Edible Oils by Normal-Phase High-Performance Liquid Chromatography.

    PubMed

    Li, Jun; Bi, Yanlan; Liu, Wei; Sun, Shangde

    2015-09-30

    During the process of antioxidation of tertiary butylhydroquinone (TBHQ) in oil and fat systems, 2-tert-butyl-1,4-benzoquinone (TQ) can be formed. The toxicity of TQ was much more than that of TBHQ. In the work, a normal-phase high-performance liquid chromatography (NP-HPLC) method for the accurate and simultaneous detection of TBHQ and TQ in edible oils was investigated. A C18 column was used to separate TBHQ and TQ, and the gradient elution solutions consisted of n-hexane containing 5% ethyl acetate and n-hexane containing 5% isopropanol. The ultraviolet (UV) detector was set at dual wavelength mode (280 nm for TBHQ and 310 nm for TQ). The column temperature was 30 °C. Before the NP-HPLC analysis, TBHQ and TQ were first extracted by methanol, subjected to vortex treatment, and then filtered through a 0.45 μm membrane filter. Results showed that linear ranges of TBHQ and TQ were both within 0.10-500.00 μg/mL (R(2) > 0.9999). The limit of detection (LOD) and limit of quantification (LOQ) of TBHQ and TQ were below 0.30 and 0.91 μg/mL and below 0.10 and 0.30 μg/mL, respectively. The recoveries of TBHQ and TQ were 98.92-102.34 and 96.28-100.58% for soybean oil and 96.11-99.42 and 98.83-99.24% for lard, respectively. These results showed that NP-HPLC can be successfully used to analyze simultaneously TBHQ and TQ in the oils and fats.

  17. Normal-Phase Open Column versus Reversed-Phase High Performance Liquid Chromatography: Separation of Chlorophyll a and Chlorophyll b from their Diastereomers.

    ERIC Educational Resources Information Center

    Schaber, Peter M.

    1985-01-01

    Background information, procedures used, and typical results obtained are provided for an experiment involving the separation of chlorophyll a and chlorophyll b from their diastereomers. Reasons why the experiment can be easily integrated into most laboratory curricula where high-performance liquid chromatography capabilities exist are given. (JN)

  18. Normal-Phase Open Column versus Reversed-Phase High Performance Liquid Chromatography: Separation of Chlorophyll a and Chlorophyll b from their Diastereomers.

    ERIC Educational Resources Information Center

    Schaber, Peter M.

    1985-01-01

    Background information, procedures used, and typical results obtained are provided for an experiment involving the separation of chlorophyll a and chlorophyll b from their diastereomers. Reasons why the experiment can be easily integrated into most laboratory curricula where high-performance liquid chromatography capabilities exist are given. (JN)

  19. Development of an on-line coupling of liquid-liquid extraction, normal-phase liquid chromatography and high-resolution gas chromatography producing an analytical marker for the prediction of mutagenicity and carcinogenicity of bitumen and bitumen fumes.

    PubMed

    Blomberg, J; de Groot, P C; Brandt, H C; van der Does, J J; Schoenmakers, P J

    1999-07-23

    A fast and fully automated system for the determination of polycyclic aromatic compounds (PACs) is described. The system has been developed to produce an analytical 'marker', correlating chemical characteristics (including PAC analysis) with mutagenicity and carcinogenicity. The products of interest are bitumen fumes, bitumen and other (heavy or even residual) oil products, regardless of their boiling range. Dimethyl sulphoxide (DMSO) extractables obtained from a flow-injection analysis (FIA) system are introduced on-line in a normal-phase liquid chromatographic (NPLC) system. Here, the PACs are separated from the DMSO and possible co-extracted heavy residual species. The final step incorporates on-line gas chromatographic analysis of the three-to-six-ring PAC fraction, followed by flame-ionisation detection for quantification. It was demonstrated that data obtained from samples in the distillate lubrication-oil range correlate well with data obtained from the manual DMSO-extraction method standardised by the Institute of Petroleum as IP346.

  20. Evaluation of coupling reversed phase, aqueous normal phase, and hydrophilic interaction liquid chromatography with Orbitrap mass spectrometry for metabolomic studies of human urine.

    PubMed

    Zhang, Tong; Creek, Darren J; Barrett, Michael P; Blackburn, Gavin; Watson, David G

    2012-02-21

    In this study, we assessed three liquid chromatographic platforms: reversed phase (RP), aqueous normal phase (ANP), and hydrophilic interaction (HILIC) for the analysis of polar metabolite standard mixtures and for their coverage of urinary metabolites. The two zwitterionic HILIC columns showed high-quality chromatographic performance for metabolite standards, improved separation for isomers, and the greatest coverage of polar metabolites in urine. In contrast, on the reversed phase column, most metabolites eluted very rapidly with little or no separation. Using an Exactive Orbitrap mass spectrometer with a HILIC liquid chromatographic platform, approximately 970 metabolite signals with repeatable peak areas (relative standard deviation (RSD) ≤ 25%) could be putatively identified in human urine, by elemental composition assignment within a 3 ppm mass error. The ability of the methodology for the verification of nonmolecular ions, which arise from adduct formation, and the possibility of distinguishing isomers could also be demonstrated. Careful examination of the raw data and the use of masses for predicted metabolites produced an extension of the metabolite list for human urine.

  1. Quantification of phosphatidylserine, phosphatidic acid and free fatty acids in an ultrasound contrast agent by normal-phase high-performance liquid chromatography with evaporative light scattering detection.

    PubMed

    Hvattum, Erlend; Uran, Steinar; Sandbaek, Anne Gunvor; Karlsson, Anders A; Skotland, Tore

    2006-10-11

    Sonazoid is a new contrast agent for ultrasound imaging. The product is an aqueous suspension of perfluorobutane microbubbles coated with phospholipids obtained from hydrogenated egg phosphatidylserine (H-EPS). A normal-phase high-performance liquid chromatographic (HPLC) method with evaporative light scattering detection was developed for quantification of free fatty acids, phosphatidylserine and phosphatidic acid in H-EPS and Sonazoid. Separation of the lipids was carried out on an HPLC diol column and a gradient of chloroform and methanol with 0.2% formic acid titrated to pH 7.5 with ammonia. The calibration standards contained stearic acid, distearoyl-phosphatidic acid (DSPA) and distearoyl-phosphatidylserine (DSPS) in the concentration range of 0.016-1.0mg/ml (0.4-25microg injected). The method was validated with a limit of quantification of the three lipids set to 0.4microg (approximately 20-60microM). The best fit of the three calibration curves were obtained when the logarithmic transformed theoretical lipid concentration was plotted against the logarithmic transformed area under the peak and fitted to a second order polynomial equation. Stearic acid, DSPA and DSPS were analysed with an intermediate precision ranging from 4.4% to 5.3% R.S.D. and they were extracted from an aqueous suspension with a recovery ranging from 103.3% to 113.3%. The sum of total phospholipid concentration determined in H-EPS ranged from 96.4% to 103.2% of the theoretical values. The lipids in the ultrasound product were quantitated with a repeatability ranging from 6.2% to 11.7% R.S.D.

  2. Determination of (R)-timolol in (S)-timolol maleate active pharmaceutical ingredient: validation of a new supercritical fluid chromatography method with an established normal phase liquid chromatography method.

    PubMed

    Marley, Adrian; Connolly, Damian

    2014-01-17

    An enantioselective supercritical fluid chromatography (SFC) method was developed and validated to meet the current European Pharmacopoeia requirements of a limit test for the determination of S-timolol maleate enantiomeric purity in timolol maleate drug substance. The developed method is presented as an alternative to the current normal phase high performance liquid chromatography (NP-HPLC) method described in the European Pharmacopoeia (Timolol Maleate Monograph). Using a 4.6mm×250mm Chiralcel OD-H (dp: 5μm) column and a mobile phase of (93:7) CO2/0.1% (v/v) TEA in MeOH delivered at 4.0mLmin(-1) resolution of 2.0 was achieved within 5min, representing a 3-fold reduction in run-time and an 11-fold reduction in solvent consumption relative to the NP-HPLC method. Method robustness was examined by the variation of flow rate (±0.5mLmin(-1)), column temperature (±5°C) and column back-pressure (±10bar) and resolution was maintained at ≥1.9 in all cases. R-timolol was resolved from all potential impurities and the limit of detection was improved by increasing the sample concentration threefold compared to the NP-HPLC method such that the method could detect the R-timolol enantiomer at 0.5% (w/w) with respect to S-timolol maleate. Additional validation parameters demonstrated that the potential of the method to be used for routine release testing of timolol maleate raw material for drug product manufacturing in which the quantitation of R-timolol impurity in S-timolol maleate drug substance would be a requirement.

  3. Liquid chromatography/tandem mass spectrometric bioanalysis using normal-phase columns with aqueous/organic mobile phases - a novel approach of eliminating evaporation and reconstitution steps in 96-well SPE.

    PubMed

    Naidong, Weng; Shou, Wilson Z; Addison, Thomas; Maleki, Saber; Jiang, Xiangyu

    2002-01-01

    Bioanalytical methods using automated 96-well solid-phase extraction (SPE) and liquid chromatography with electrospray tandem mass spectrometry (LC/MS/MS) are widely used in the pharmaceutical industry. SPE methods typically require manual steps of drying of the eluates and reconstituting of the analytes with a suitable injection solvent possessing elution strength weaker than the mobile phase. In this study, we demonstrated a novel approach of eliminating these two steps in 96-well SPE by using normal-phase LC/MS/MS methods with low aqueous/high organic mobile phases, which consisted of 70-95% organic solvent, 5-30% water, and small amount of volatile acid or buffer. While the commonly used SPE elution solvents (i.e. acetonitrile and methanol) have stronger elution strength than a mobile phase on reversed-phase chromatography, they are weaker elution solvents than a mobile phase for normal-phase LC/MS/MS and therefore can be injected directly. Analytical methods for a range of polar pharmaceutical compounds, namely, omeprazole, metoprolol, fexofenadine, pseudoephedrine as well as rifampin and its metabolite 25-desacetyl-rifampin, in biological fluids, were developed and optimized based on the foregoing principles. As a result of the time saving, a batch of 96 samples could be processed in one hour. These bioanalytical LC/MS/MS methods were validated according to "Guidance for Industry - Bioanalytical Method Validation" recommended by the Food and Drug Administration (FDA) of the United States.

  4. Stereoselective determination of a novel chiral insecticide, sulfoxaflor, in brown rice, cucumber and apple by normal-phase high-performance liquid chromatography.

    PubMed

    Chen, Zenglong; Dong, Fengshou; Xu, Jun; Liu, Xingang; Cheng, Youpu; Liu, Na; Tao, Yan; Zheng, Yongquan

    2014-02-01

    An effective high-performance liquid chromatography method was developed for the stereoselective determination of a new sulfoximines insecticide, sulfoxaflor, in brown rice, cucumber and apple. Target compounds were extracted with acetonitrile and an aliquot cleaned with Cleanert PestiCarb/PSA (primary and secondary amine) cartridge. Five polysaccharide-based columns were investigated on the separation of sulfoxaflor stereoisomers and the best was achieved on a ChromegaChiral CCA column with n-hexane/ethanol/methanol (90:2:8, v/v/v) as mobile phase by UV detection at 220 nm at 20ºC. The resolutions of the four stereoisomers were 1.85, 1.54 and 3.08, and the elution order was identified by optical rotation and stereoisomers ratio. The mean recoveries of sulfoxaflor stereoisomers ranged from 77.1% to 99.3%, with relative standard deviations less than 8.9% at three concentration levels in all matrices. The limits of detection for all stereoisomers varied from 0.05 mg/kg to 0.07 mg/kg, while the limit of quantification did not exceed 0.22 mg/kg. The method was then successfully applied to determine the sulfoxaflor stereoisomers in authentic samples, confirming that it is convenient and reliable for stereoselective determination of sulfoxaflor stereoisomers in food.

  5. One input-class and two input-class classifications for differentiating olive oil from other edible vegetable oils by use of the normal-phase liquid chromatography fingerprint of the methyl-transesterified fraction.

    PubMed

    Jiménez-Carvelo, Ana M; Pérez-Castaño, Estefanía; González-Casado, Antonio; Cuadros-Rodríguez, Luis

    2017-04-15

    A new method for differentiation of olive oil (independently of the quality category) from other vegetable oils (canola, safflower, corn, peanut, seeds, grapeseed, palm, linseed, sesame and soybean) has been developed. The analytical procedure for chromatographic fingerprinting of the methyl-transesterified fraction of each vegetable oil, using normal-phase liquid chromatography, is described and the chemometric strategies applied and discussed. Some chemometric methods, such as k-nearest neighbours (kNN), partial least squared-discriminant analysis (PLS-DA), support vector machine classification analysis (SVM-C), and soft independent modelling of class analogies (SIMCA), were applied to build classification models. Performance of the classification was evaluated and ranked using several classification quality metrics. The discriminant analysis, based on the use of one input-class, (plus a dummy class) was applied for the first time in this study.

  6. Column temperature as an active variable in the isocratic, normal-phase high-performance liquid chromatography separation of lipophilic metabolites of nonylphenol ethoxylates.

    PubMed

    Babay, Paola A; Gettar, Raquel T; Magallanes, Jorge F; Becquart, Elena T; Thiele, Björn; Batistoni, Daniel A

    2007-07-20

    Normal-phase separation of technical grade nonylphenol (t-NP, about 90% 4-nonylphenol), 4-nonylphenol mono-ethoxylate (4-NP1EO) and 4-nonylphenol di-ethoxylate (4-NP2EO) was assessed, with the inclusion of column temperature as an active variable. The compound 2,4,6-trimethylphenol was evaluated for use as internal standard. Isocratic elution with 2-propanol/hexanes mixtures from an amino-silica column and spectrometric UV detection at 277 nm were employed. Technical nonylphenol presented a significant contribution from unknown substances that eluted with retention times similar to that of 4-NP1EO. GC-MS analysis of the unknowns allowed to identify them as isomers of 2-NP. The response of the system to joint variations in flow rate, eluent composition and column temperature was investigated by means of Doehlert statistical experimental design. A model for retention of the analytes as a function of the experimental variables was proposed, and separation selectivity was studied. Selection of the optimal working zone was made through desirability function (D) calculations. Potential co-elution of 2-NP isomers with 4-NP1EO was considered when optimizing the separation. The occurrence of a restricted region of the experimental space where baseline resolution of analytes, associated impurities and internal standard results feasible (D not equal to 0) is apparent.

  7. Preparation and kinetic performance assessment of thick film 10-20 μm open tubular silica capillaries in normal phase high pressure liquid chromatography.

    PubMed

    Forster, Simon; Kolmar, Harald; Altmaier, Stephan

    2013-11-08

    It is well-known that the open tubular column design basically can offer very high plate numbers. Experimental realization has however not kept pace with theoretical considerations, lacking efficient methods for the deposition of a thick film porous layer within a microbore capillary. A previously published sol-gel synthesis method was extended from 20 μm to 10 μm inner diameter fused silica capillaries and the resulting columns were compared to a monolithic reference capillary in terms of kinetic performance at pressure maximum. Column permeability was investigated and pressure/flow-diagrams were obtained with a 400-fold permeability gain for the open tubes. Structural characterizations regarding layer thickness and surface porosity were carried out and displayed via scanning electron microscopy and nitrogen sorption analysis. Chromatographic results in normal phase mode at elevated mobile phase flow rate reveal the intrinsic performance potential of this column format when it comes to kinetic performance limitation plots, which were constructed for all columns prepared and compared to the monolithic silica reference capillary.

  8. Determination of lycopene in tissues and plasma of rats by normal-phase high-performance liquid chromatography with photometric detection.

    PubMed

    Froescheis, O; Moalli, S; Liechti, H; Bausch, J

    2000-03-10

    An analytical method for the determination of lycopene in tissues and plasma of rats is described. The method was validated for the determination of lycopene in liver and plasma with respect to selectivity, linearity, accuracy, recovery and precision. Following precipitation of proteins with water-ethanol plasma was extracted with hexane; tissues were extracted with acetone followed by precipitation of proteins with water-ethanol and extraction of lycopene with hexane. Separation and quantification of geometrical isomers of lycopene was achieved by normal-phase HPLC with UV/VIS detection at 471 nm. The method proved to be selective and specific for lycopene in plasma and liver. Detector response was linear in the range from 2 ng/g to 10 microg/g liver and 0.5 ng/ml to 2 microg/ml plasma, respectively. Average recoveries ranged from 96 to 101% in spiked liver samples and from 91 to 94% in spiked plasma samples. Intra-day variability (C.V.) was < or = 6% and < or = 5% in liver and plasma, respectively. Inter-day precision was < or = 9% for liver samples and < or = 6% for plasma samples. The procedures were successfully applied to the sample analysis of pharmacokinetic and metabolism studies.

  9. A rapid method for the determination of vitamin E forms in tissues and diet by high-performance liquid chromatography using a normal-phase diol column.

    PubMed

    Kramer, J K; Blais, L; Fouchard, R C; Melnyk, R A; Kallury, K M

    1997-03-01

    This paper describes a simple method for the analysis of tocopherols in tissues by which frozen tissues-70 degrees C were pulverized at dry ice temperatures (-70 degrees C) and immediately extracted with hexane. There was no need to remove the coeluting lipids from tissues by saponification, since at that level of neutral lipids in the sample, there was no reduction in fluorescence response. For the analysis of oil, in which large amounts of neutral lipids were coextracted, a 20% reduction of fluorescence response was observed, but the response was equal for all tocopherol forms, and was appropriately corrected. Saponification was used only when tocopherol esters were present, and only after an initial hexane extraction to remove the free tocopherols in order to avoid their loss by saponification, particularly non alpha-tocopherol and tocotrienols. All the tocopherols and tocotrienols were separated on a normal-phase diol (epoxide) column that gave consistent and reproducible results, without the disadvantages of nonreproducibility with silica columns, or the lack of separation with reversed-phase columns. The tocopherols were quantitated by using a tocopherol form not present in the sample as an internal tocopherol standard, or using an external tocopherol standard if all forms were present, or when the sample was saponified. Piglet heart and liver samples showed the presence of mainly alpha-tocopherol, with minor amounts of beta- and gamma-tocopherol and alpha-tocotrienol, but no delta-tocopherol. Only small amounts of tocopherol esters were present in the liver but not in the heart.

  10. Separation and molecular characterization of mycolic acid from the cell wall skeleton of Mycobacterium bovis BCG Tokyo 172 (SMP-105) and BCG substrains by normal-phase high performance liquid chromatography and liquid chromatography/mass spectrometry.

    PubMed

    Uenishi, Yuko; Takii, Takemasa; Yano, Ikuya; Sunagawa, Makoto

    2009-06-01

    Since mycolic acids, the most characteristic major lipid component in mycobacterial cell envelopes, play pivotal roles in the cell surface-based host immune responses, normal-phase HPLC has been developed to quantify and identify mycolic acids of the cell wall skeleton from Mycobacterium bovis BCG Tokyo 172 (SMP-105).

  11. A new approach to bioanalysis: aqueous normal-phase chromatography with silica hydride stationary phases.

    PubMed

    Pesek, Joseph J; Matyska, Maria T

    2012-04-01

    Stationary phases based on silica hydride have demonstrated a number of unique properties that are especially advantageous for bioanalyses. They have excellent retention capabilities for hydrophilic compounds, which have been the most difficult to analyze by standard reversed-phase methods and, in many cases, can outperform newer approaches for the analysis of polar molecules, such as hydrophilic liquid interaction chromatography. In addition, all columns utilizing silica-hydride materials can be used in either the normal-phase or reversed-phase modes, sometimes retaining both polar and nonpolar compounds simultaneously. These stationary phases have a high degree of reproducibility and long-term stability.

  12. Profile and quantification of human stratum corneum ceramides by normal-phase liquid chromatography coupled with dynamic multiple reaction monitoring of mass spectrometry: development of targeted lipidomic method and application to human stratum corneum of different age groups.

    PubMed

    Jia, Zhi-Xin; Zhang, Jin-Lan; Shen, Chun-Ping; Ma, Lin

    2016-09-01

    Skin, the largest organ of the human body, serves as the primary barrier to the external environment. Ceramides are one of the main constituents of stratum corneum (SC), playing an important role in skin barrier function. Therefore, comprehensive profiling and quantification of SC ceramide is important. Herein, a new targeted lipidomic method for human SC ceramide profiling and quantification is presented and tested. Normal-phase high-performance liquid chromatography coupled with dynamic multiple reaction monitoring mass spectrometry (NP-HPLC-dMRM-MS) was used to separate ceramides into subclasses and then characterize different ceramides within each subclass on the basis of their characteristics. In total, 483 ceramides were quantified in a single run within 20 min, covering 12 subclasses as well as some glycosylated ceramides not previously reported. Each subclass had typical standard substances (if available) that served to establish representative standard curves and were used for related substances with no standards. Linearity range, limit of quantification (LOQ), limit of detection (LOD), precision, accuracy, stability, and matrix effects were validated. dMRM increased sensitivity and accuracy greatly compared with common MRM (cMRM). This method was successfully applied to the study of human SC from different age groups. A total of 193 potential biomarkers were found to indicate age differences between children and adults. This method is an innovative approach for high-throughput quantification of SC ceramide. Graphical Abstract Method establishment (MRM spectra by the established method) and method application (score scatter plots of authentic samples).

  13. Liposomes as potential masking agents in sport doping. Part 1: analysis of phospholipids and sphingomyelins in drugs and biological fluids by aqueous normal-phase liquid chromatography-tandem mass spectrometry.

    PubMed

    Esposito, Simone; Colicchia, Sonia; de la Torre, Xavier; Mazzarino, Monica; Botrè, Francesco

    2017-01-01

    In the present work, aqueous normal-phase liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS), in different acquisition modes, was employed for the direct analysis and profiling of nine phospholipid classes (phosphatidic acids, phosphatidylserines, phosphatidylethanolamines, lysophosphatidylethanolamines, phosphatidylglycerols, phosphatidylinositols, phosphatidylcholines, lysophosphatidylcholines, and sphingomyelins) in biological and pharmaceutical matrices. After chromatographic separation by a diol column, detection and elucidation of phospholipid and sphingomyelin classes and molecular species were performed by different scan acquisition modes. For screening analysis, molecular ions [M + H](+) were detected in positive precursor ion scan of m/z 184 for the classes of phosphatidylcholines, lyso-phosphatidylcholines and sphingomyelins; while phosphatidylethanolamines and lyso-phosphatidylethanolamines were detected monitoring neutral loss scan of 141 Da; and phosphatidylserines detected using neutral loss scan of 184 Da. Molecular ions [M-H](-) were instead acquired in negative precursor ion scan of m/z 153 for the classes of phosphatidic acids and phosphatidylglycerols; and of m/z 241 for the phosphatidylinositols. For the identification of the single molecular species, product ion scan mass spectra of the [M + HCOO](-) ions for phosphatidylcholines and [M + H](+) ions for the other phospholipids considered were determined for each class and compared with the fragmentation pattern of model phospholipid reference standard. By this approach, nearly 100 phospholipids and sphingomyelins were detected and identified. The optimized method was then used to characterize the phospholipid and sphingomyelin profiles in human plasma and urine samples and in two phospholipid-based pharmaceutical formulations, proving that it also allows to discriminate compounds of endogenous origin from those resulting from the intake of pharmaceutical

  14. Simultaneous analysis of tert-butylhydroquinone, tert-butylquinone, butylated hydroxytoluene, 2-tert-butyl-4-hydroxyanisole, 3-tert-butyl-4-hydroxyanisole, α-tocopherol, γ-tocopherol, and δ-tocopherol in edible oils by normal-phase high performance liquid chromatography.

    PubMed

    Li, Jun; Bi, Yanlan; Sun, Shangde; Peng, Dan

    2017-11-01

    A normal-phase high performance liquid chromatography method for the simultaneous determination of tert-butylhydroquinone, tert-butylquinone, butylated hydroxytoluene, 2-tert-butyl-4-hydroxyanisole, 3-tert-butyl-4-hydroxyanisole, α-tocopherol, γ-tocopherol, and δ-tocopherol in edible oils was investigated. A silica column was used to separate the analytes with the gradient elution. An ultraviolet-visible detector was set at dual wavelengths mode (280 and 310nm). The column temperature was 30°C. The analytes were directly extracted with methanol. Results showed that the normal-phase high performance liquid chromatography method performed well with wide liner ranges (0.10∼500.00μg/mL, R(2)>0.9998), low limits of detection and quantitation (below 0.40 and 1.21μg/mL, respectively), and good recoveries (81.38∼102.34% in soybean oils and 83.03∼100.79% in lard, respectively). The reduction of tert-butylquinone caused by the reverse-phase high performance liquid chromatography during the injection was avoided with the current normal-phase method. The two isomers of butylated hydroxyanisole can also be separated with good resolution. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. Simultaneous determination of tocopherols and tocotrienols in hazelnuts by a normal phase liquid chromatographic method.

    PubMed

    Amaral, Joana S; Casal, Susana; Torres, Duarte; Seabra, Rosa M; Oliveira, Beatriz P P

    2005-12-01

    A normal-phase high-performance liquid chromatography (NP-HPLC) method for the determination of tocopherols and tocotrienols in hazelnuts is reported. Three extraction procedures (with and without saponification) were assayed; the best results were obtained with a simple solid-liquid extraction procedure. Chromatographic separation was achieved using an Inertsil 5 SI column using isocratic elution with hexane/1,4-dioxane (95.5:4.5, v/v) at a flow rate of 0.7 mL/min. The effluent was monitored by a series arrangement of a diode-array followed by a fluorescence detector. All compounds were separated in a short period of time (17 min). The method proved to be rapid, sensitive, reproducible and accurate, allowing the simultaneous determination of all vitamin E homologues.

  16. Chromatographic behaviour of synthetic high pressure high temperature diamond in aqueous normal phase chromatography.

    PubMed

    Peristyy, Anton; Paull, Brett; Nesterenko, Pavel N

    2016-10-28

    The chromatographic properties of high pressure high temperature synthesised diamond (HPHT) are investigated under the conditions of hydrophilic interaction liquid chromatography (HILIC). A 50×4.6mm ID stainless steel column packed with HPHT particles of mean diameter 1.6μm and specific surface area 5.1m(2)g(-1) is used. According to the results of acid-base titration with NaOH the purified HPHT batch contains 4.59μeqg(-1) of protogenic, mainly carboxyl- and hydroxyl-, groups, which make this polar adsorbent suitable for use as a stationary phase in HILIC. The retention behaviour of several classes of polar compounds including benzoic and benzenesulfonic acids, nitro- and chlorophenols, various organic bases, and quaternary ammonium compounds are studied using acetonitrile and methanol based mobile phases containing 5-30v/v% of water. The effects of the buffer pH and concentration, column temperature and organic solvent content on retention of model compounds are also investigated. It is shown that both pH and acetonitrile/methanol ratio in the mobile phase can be used to vary the separation selectivity. Molecular adsorption mechanism (related to aqueous normal phase mode), rather than partitioning is established to be responsible for the retention.

  17. A Fluorogenic Aromatic Nucleophilic Substitution Reaction for Demonstrating Normal-Phase Chromatography and Isolation of Nitrobenzoxadiazole Chromophores

    ERIC Educational Resources Information Center

    Key, Jessie A.; Li, Matthew D.; Cairo, Christopher W.

    2011-01-01

    Normal-phase chromatography is an essential technique for monitoring chemical reactions, identifying the presence of specific components, as well as the purification of organic compounds. An experiment to facilitate the instruction and understanding of the concepts behind normal-phase chromatography at the introductory and intermediate…

  18. A Fluorogenic Aromatic Nucleophilic Substitution Reaction for Demonstrating Normal-Phase Chromatography and Isolation of Nitrobenzoxadiazole Chromophores

    ERIC Educational Resources Information Center

    Key, Jessie A.; Li, Matthew D.; Cairo, Christopher W.

    2011-01-01

    Normal-phase chromatography is an essential technique for monitoring chemical reactions, identifying the presence of specific components, as well as the purification of organic compounds. An experiment to facilitate the instruction and understanding of the concepts behind normal-phase chromatography at the introductory and intermediate…

  19. High performance liquid chromatographic separations of gas oil samples and their hydrotreated products using commercial normal phases.

    PubMed

    Oro, Nicole E; Lucy, Charles A

    2011-10-28

    Three commercially available high performance liquid chromatography columns are used in normal phase or quasi-normal phase mode for the separation of gas oil samples. The columns are tested with 20 analytical standards to determine their suitability for separations of petroleum samples and their ability to separate the nitrogen group-types (pyrrole and pyridine) found in petroleum. The columns studied are polymeric hypercrosslinked polystyrene (HGN), a biphenyl phase, and a Chromegabond "DNAP" column from ES Industries. The HGN column separates gas oils based on both ring structure and heteroatom, while the biphenyl phase has low retention of most compounds studied in quasi-normal phase mode. The "DNAP" column is selective for nitrogen-containing compounds, separating them from PAHs as well as oxygen and sulphur compounds. Retention data of standards on all three columns is shown, along with chromatograms of gas oil samples on the HGN and "DNAP" columns. Copyright © 2011 Elsevier B.V. All rights reserved.

  20. Linear solvation energy relationships in normal phase chromatography based on gradient separations.

    PubMed

    Wu, Di; Lucy, Charles A

    2017-09-22

    Coupling the modified Soczewiñski model and one gradient run, a gradient method was developed to build a linear solvation energy relationship (LSER) for normal phase chromatography. The gradient method was tested on dinitroanilinopropyl (DNAP) and silica columns with hexane/dichloromethane (DCM) mobile phases. LSER models built based on the gradient separation agree with those derived from a series of isocratic separations. Both models have similar LSER coefficients and comparable goodness of fit, but the LSER model based on gradient separation required fewer trial and error experiments. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. Profiling of polar metabolites in biological extracts using diamond hydride-based aqueous normal phase chromatography.

    PubMed

    Callahan, Damien L; De Souza, David; Bacic, Antony; Roessner, Ute

    2009-07-01

    Highly polar metabolites, such as sugars and most amino acids are not retained by conventional RP LC columns. Without sufficient retention low concentration compounds are not detected due ion suppression and structural isomers are not resolved. In contrast, hydrophilic interaction chromatography (HILIC) and aqueous normal phase chromatography (ANP) retain compounds based on their hydrophilicity and therefore provides a means of separating highly polar compounds. Here, an ANP method based on the diamond hydride stationary phase is presented for profiling biological small molecules by LC. A rapid separation system based upon a fast gradient that delivers reproducible chromatography is presented. Approximately 1000 compounds were reproducibly detected in human urine samples and clear differences between these samples were identified. This chromatography was also applied to xylem fluid from soyabean (Glycine max) plants to which 400 compounds were detected. This method greatly increases the metabolite coverage over RP-only metabolite profiling in biological samples. We show that both forms of chromatography are necessary for untargeted comprehensive metabolite profiling and that the diamond hydride stationary phase provides a good option for polar metabolite analysis.

  2. Method performance and multi-laboratory assessment of a normal phase high pressure liquid chromatography-fluorescence detection method for the quantitation of flavanols and procyanidins in cocoa and chocolate containing samples.

    PubMed

    Robbins, Rebecca J; Leonczak, Jadwiga; Johnson, J Christopher; Li, Julia; Kwik-Uribe, Catherine; Prior, Ronald L; Gu, Liwei

    2009-06-12

    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. Single laboratory method performance was examined over three months using three separate secondary standards. RSD(r) ranged from 1.9%, 4.5% to 9.0% for cocoa powder, liquor and chocolate samples containing 74.39, 15.47 and 1.87 mg/g flavanols and procyanidins, respectively. Accuracy was determined by comparison to the NIST Standard Reference Material 2384. Inter-lab assessment indicated that variability was quite low for seven different cocoa-containing samples, with a RSD(R) of less than 10% for the range of samples analyzed.

  3. Determination of Vitamin E and Vitamin A in Infant Formula and Adult Nutritionals by Normal-Phase High-Performance Liquid Chromatography: Collaborative Study, Final Action 2012.10.

    PubMed

    McMahon, Adrienne

    2016-01-01

    The main objective of the AOAC Stakeholder Panel on Infant Formula and Adult Nutritionals (SPIFAN) project is to establish international consensus methods for infant formula and adult nutritionals, which will benefit intermarket supply and dispute resolution. A collaborative study was conducted on AOAC First Action Method 2012.10 Simultaneous Determination of 13-cis and All-trans Vitamin A Palmitate (Retinyl Palmitate), Vitamin A Acetate (Retinyl Acetate), and Total Vitamin E (α-Tocopherol and D-α-tocopherol acetate) in Infant Formula and Adult Nutritionals by Normal-Phase HPLC. Fifteen laboratories from 11 countries participated in an interlaboratory study to determine 13-cis and all-trans vitamin A palmitate (retinyl palmitate), vitamin A acetate (retinyl acetate), and total vitamin E (α-tocopherol and D-α-tocopherol acetate) in infant formula and adult nutritionals by normal-phase HPLC and all laboratories returned valid data. Eighteen test portions of nine blind duplicates of a variety of infant formula and adult nutritional products were used in the study. The matrixes included milk-based and soy-based hydrolyzed protein as well as a low fat product. Each of the samples was prepared fresh and analyzed in singlicate. As the number of samples exceeded the recommended number to be prepared in a single day, analysis took place over 2 days running 12 samples on day one and 10 samples on day two. The reference standard stock was prepared once and the six-point curve diluted freshly on each day. Results obtained from all 15 laboratories are reported. The RSDR for total vitamin A (palmitate or acetate) ranged from 6.51 to 22.61% and HorRat values ranged from 0.33 to 1.25. The RSDR for total vitamin E (as tocopherol equivalents) ranged from 3.84 to 10.78% and HorRat values ranged from 0.27 to 1.04. Except for an adult low fat matrix which generated reproducibility RSD >40% for some isomers, most SPIFAN matrixes gave results within the acceptance criteria of <16

  4. Analysis of ethyl glucuronide and ethyl sulfate using aqueous normal-phase chromatography with mass spectrometry.

    PubMed

    Pesek, Joseph J; Matyska, Maria T; Dang, Andy

    2015-05-01

    The use of aqueous normal-phase chromatography is explored as a possible format for the analysis of the forensically significant compounds ethyl glucuronide and ethyl sulfate. Standard solutions of the two compounds are used to verify the retention capabilities of two stationary phases (diamond hydride and undecanoic acid). These results are then compared to data obtained on hair extracts to determine if any matrix effects exist with respect to both retention and peak shape. The undecanoic stationary phase is used for the establishment of calibration curves for quantitative analysis. These curves are utilized to determine the concentration of ethyl glucuronide in several hair samples tested. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Class separation of lipids and polycyclic aromatic hydrocarbons in normal phase high performance liquid chromatography - a prospect for analysis of aromatics in edible vegetable oils and biodiesel exhaust particulates.

    PubMed

    Olsson, Petter; Sadiktsis, Ioannis; Holmbäck, Jan; Westerholm, Roger

    2014-09-19

    The retention characteristics of the major lipid components in biodiesels and edible oils as well as representative polycyclic aromatic compounds (PAHs) have been investigated on five different normal phase HPLC stationary phases, in order to optimize class separation for an automatized online HPLC cleanup of PAHs prior GC-MS analysis. By stepwise comparison of different hexane/MTBE compositions as mobile phases on cyano-, phenyl-, pentabromobenzyl-, nitrophenyl- and amino-modified silica columns, the capacity and selectivity factors for each analyte and column could be calculated. It was concluded that the most suitable column for backflush isolation of PAHs in biodiesel and edible oil matrices was the pentabromobenzyl-modified silica (PBB). A previously described online HPLC-GC-MS system using the PBB column was then evaluated by qualitative and quantitative analysis of a biodiesel exhaust particulate extract and a vegetable oil reference material. The GC-MS full scan analysis of the biodiesel particulate extract showed that the lipids had been removed from the sample and a fraction containing PAHs and oxygenated derivatives thereof had been isolated. Quantified mass fractions of PAHs of the reference material BCR-458 agreed well for most of the certified PAH mass fractions in the spiked coconut oil reference material. Copyright © 2014 Elsevier B.V. All rights reserved.

  6. Development of normal phase-high performance liquid chromatography-atmospherical pressure chemical ionization-mass spectrometry method for the study of 6,6'-bis-(5,5,8,8-tetramethyl-5,6,7,8-tetrahydro-benzo[1,2,4]-triazin-3-yl)-[2,2']-bipyridine hydrolytic degradation.

    PubMed

    Nicolas, Grégory; Jankowski, Christopher K; Lucas-Lamouroux, Christine; Bresson, Carole

    2011-09-16

    In the field of nuclear waste management, the 6,6'-bis-(5,5,8,8-tetramethyl-5,6,7,8-tetrahydro-benzo[1,2,4]-triazin-3-yl)-[2,2']-bipyridine (CyMe(4)BTBP) is a polycyclic N-based molecule eligible to remove actinides from spent nuclear fuel by liquid-liquid extraction processes. In such processes, the organic phase containing the extracting molecules will undergo hydrolysis and radiolysis, involving degradation products. The purpose of this work was to develop a normal phase chromatography (NP-HPLC) coupled to atmospherical pressure chemical ionisation-mass spectrometry (APCI-MS) method to separate and identify degradation products of CyMe(4)BTBP dissolved in octanol, submitted to HNO(3) hydrolysis. 1 mol L(-1) HNO(3) hydrolysis conditions were used regarding the selective actinides extraction (SANEX) process, while 3 mol L(-1) HNO(3) conditions were applied for the group actinide extraction (GANEX) process. The first step consisted in optimizing the chromatographic separation conditions using a diode array detection (DAD). Retention behavior of a non hydrolyzed mixture of N,N'-dimethyl-N,N'-dioctyl-hexyloxyethyl-malonamide (DMDOHEMA), a malonamide used in the SANEX process to increase the kinetic of extraction, and CyMe(4)BTBP were investigated on diol-, cyano-, and amino-bonded stationary phases using different mobile phase compositions. These latter were hexane with different polar modifiers, i.e. dioxane, isopropanol, ethanol and methylene chloride/methanol. The different retention processes in NP-HPLC were highlighted when using various stationary and mobile phases. The second step was the setting-up of the NP-HPLC-APCI-MS coupling and the use of the low-energy collision dissociation tandem mass spectrometry (CID-MS/MS) of the precursor protonated molecules that allowed the separation and the characterization of the main hydrolytic CyMe(4)BTBP degradation product under a 3 mol L(-1) HNO(3) concentration. Investigation of the CID-MS/MS fragmentation pattern was

  7. Suitability of silica hydride stationary phase, aqueous normal phase chromatography for untargeted metabolomic profiling of Enterococcus faecium and Staphylococcus aureus.

    PubMed

    Weisenberg, Scott A; Butterfield, Tiffany R; Fischer, Steven M; Rhee, Kyu Y

    2009-07-01

    We report the robustness of silica hydride stationary phase, aqueous normal phase (ANP) chromatography to the chemical complexity of the intracellular metabolomes of Staphylococcus aureus and Enterococcus faecium. We specifically demonstrate that the chromatographic behavior of known metabolites is unaffected by the intracellular chemical matrix of these microbes and that this method enables untargeted profiling of their intracellular metabolites using accurate mass-retention time (AMRT) identifiers. We further demonstrate the ability of AMRT-based metabolite profiling to differentiate bacteria along genetic and phenotypic lines. Overall, these data commend the utility of ANP-based chromatography for untargeted metabolomics-based studies of microbial physiology and antibiotic resistance.

  8. Retention mechanism of hypercrosslinked polystyrene silica hybrid phase in normal phase chromatography.

    PubMed

    Wu, Di; Nedev, Georgi K; Lucy, Charles A

    2014-11-28

    Hypercrosslinked polystyrene phases have been described as quasi-normal phase because they lack discrete polar sites. Retention on the HC-Tol column is investigated using the Snyder-Soczewinski model. Solvent strength of different hexane-solvent binary mobile phase compositions can be predicted with solvent strength of pure dichloromethane (DCM, 0.159), tetrahydrofuran (THF, 0.22), and benzene (0.127). The HC-Tol column is shown to be a localizing adsorptive phase. Also, site-competition delocalization on HC-Tol demonstrates that whatever its adsorption groups are, they are able to participate in lateral interactions. Copyright © 2014 Elsevier B.V. All rights reserved.

  9. Advanced proteomic liquid chromatography

    SciTech Connect

    Xie, Fang; Smith, Richard D.; Shen, Yufeng

    2012-10-26

    Liquid chromatography coupled with mass spectrometry is the predominant platform used to analyze proteomics samples consisting of large numbers of proteins and their proteolytic products (e.g., truncated polypeptides) and spanning a wide range of relative concentrations. This review provides an overview of advanced capillary liquid chromatography techniques and methodologies that greatly improve separation resolving power and proteomics analysis coverage, sensitivity, and throughput.

  10. Column Liquid Chromatography.

    ERIC Educational Resources Information Center

    Majors, Ronald E.; And Others

    1984-01-01

    Reviews literature covering developments of column liquid chromatography during 1982-83. Areas considered include: books and reviews; general theory; columns; instrumentation; detectors; automation and data handling; multidimensional chromatographic and column switching techniques; liquid-solid chromatography; normal bonded-phase, reversed-phase,…

  11. Column Liquid Chromatography.

    ERIC Educational Resources Information Center

    Majors, Ronald E.; And Others

    1984-01-01

    Reviews literature covering developments of column liquid chromatography during 1982-83. Areas considered include: books and reviews; general theory; columns; instrumentation; detectors; automation and data handling; multidimensional chromatographic and column switching techniques; liquid-solid chromatography; normal bonded-phase, reversed-phase,…

  12. Liquid Chromatography in 1982.

    ERIC Educational Resources Information Center

    Freeman, David H.

    1982-01-01

    Reviews trends in liquid chromatography including apparatus, factors affecting efficient separation of a mixture (peak sharpness and speed), simplified problem-solving, adsorption, bonded phase chromatography, ion selectivity, and size exclusion. The current trend is to control chemical selectivity by the liquid phase. (Author/JN)

  13. The use of aqueous normal phase chromatography as an analytical tool for food analysis: determination of histamine as a model system.

    PubMed

    Dang, Andy; Pesek, Joseph J; Matyska, Maria T

    2013-12-15

    A simple, fast, robust protocol that does not require derivatisation for the determination of histamine, a polar primary bioamine, in red wine and food products is presented. Histamine can be retained and quantified under aqueous normal phase (ANP) conditions, using a Diamond Hydride (DH) column for high performance liquid chromatography/ultraviolet-visible (HPLC-UV) and mass spectrometry (MS) detection. An ANP gradient was developed, allowing for the direct analyses of the wines and food products. The peak shape for this basic compound was also evaluated under optimal analytical conditions. From UV and MS detection, a linear correlation for quantitation is obtained. The basic strategy presented for the analysis of histamine is applicable to a broad range of polar compounds in a variety of foods and beverages. Copyright © 2013 Elsevier Ltd. All rights reserved.

  14. Comparison of nonaqueous hydrophilic interaction chromatography with aqueous normal-phase chromatography on hydrosilated silica-based stationary phases.

    PubMed

    Soukup, Jan; Jandera, Pavel

    2013-09-01

    We investigated the retention behavior of phenolic acids in nonaqueous normal-phase (NP) LC with buffered methanol/acetonitrile mobile phases on hydrosilated silica-based stationary phases. The silica hydride, Diamond hydride, Bidentate C18, and Cholesterol columns showed a higher retention of phenolic acids in the nonaqueous mobile phases than in aqueous NP mobile phases. There are some selectivity differences between the aqueous and nonaqueous mobile phases, but generally the resolution and selectivity are better in the aqueous systems. The retention of the phenolic acids tested decreased with increasing concentration of methanol in the mobile phase, up to 20% v/v methanol. At increased temperatures, the retention factors and peak widths decrease in both NP modes, showing linear ln k versus 1/T plots, due to a single retention mechanism over the temperature range from 25°C up to the column stability limit, however, the best separations are achieved at low temperatures. The enthalpic and entropic contributions to the retention were determined, and the differences between the aqueous and nonaqueous modes are possibly due to the adsorbed water layer. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Micellar liquid chromatography

    NASA Astrophysics Data System (ADS)

    Basova, Elena M.; Ivanov, Vadim M.; Shpigun, Oleg A.

    1999-12-01

    Background and possibilities of practical applications of micellar liquid chromatography (MLC) are considered. Various retention models in MLC, the effects of the nature and concentration of surfactants and organic modifiers, pH, temperature and ionic strength on the MLC efficiency and selectivity are discussed. The advantages and limitations of MLC are demonstrated. The performance of MLC is critically evaluated in relationship to the reversed-phase HPLC and ion-pair chromatography. The potential of application of MLC for the analysis of pharmaceuticals including that in biological fluids and separation of inorganic anions, transition metal cations, metal chelates and heteropoly compounds is described. The bibliography includes 146 references.

  16. High Performance Liquid Chromatography

    NASA Astrophysics Data System (ADS)

    Talcott, Stephen

    High performance liquid chromatography (HPLC) has many applications in food chemistry. Food components that have been analyzed with HPLC include organic acids, vitamins, amino acids, sugars, nitrosamines, certain pesticides, metabolites, fatty acids, aflatoxins, pigments, and certain food additives. Unlike gas chromatography, it is not necessary for the compound being analyzed to be volatile. It is necessary, however, for the compounds to have some solubility in the mobile phase. It is important that the solubilized samples for injection be free from all particulate matter, so centrifugation and filtration are common procedures. Also, solid-phase extraction is used commonly in sample preparation to remove interfering compounds from the sample matrix prior to HPLC analysis.

  17. Principles of Liquid Chromatography

    NASA Astrophysics Data System (ADS)

    Bakalyar, Stephen R.

    This article reviews the basic principles of high performance liquid chromatography (HPLC). The introductory section provides an overview of the HPLC technique, placing it in historical context and discussing the elementary facts of the separation mechanism. The next section discusses the nature of resolution, describing the two principal aspects, zone center separation and zone spreading. The third section takes a detailed look at how HPLC is used in practice to achieve a separation. It discusses the three key variables that need to be adjusted: retention, efficiency, and selectivity. A fourth section is concerned with various relationships of practical importance: flow rate, temperature, and pressure. A final section discusses future trends in HPLC.

  18. High-Performance Liquid Chromatography

    NASA Astrophysics Data System (ADS)

    Reuhs, Bradley L.; Rounds, Mary Ann

    High-performance liquid chromatography (HPLC) developed during the 1960s as a direct offshoot of classic column liquid chromatography through improvements in the technology of columns and instrumental components (pumps, injection valves, and detectors). Originally, HPLC was the acronym for high-pressure liquid chromatography, reflecting the high operating pressures generated by early columns. By the late 1970s, however, high-performance liquid chromatography had become the preferred term, emphasizing the effective separations achieved. In fact, newer columns and packing materials offer high performance at moderate pressure (although still high pressure relative to gravity-flow liquid chromatography). HPLC can be applied to the analysis of any compound with solubility in a liquid that can be used as the mobile phase. Although most frequently employed as an analytical technique, HPLC also may be used in the preparative mode.

  19. Impact of normal-phase gradient elution in chiral chromatography: a novel, robust, efficient and rapid chiral screening procedure.

    PubMed

    de la Puente Luz, María; White, Craig T; Rivera-Sagredo, Alfonso; Reilly, John; Burton, Keith; Harvey, Georgina

    2003-01-03

    Novel normal-phase gradient systems have been employed for fast high-throughput chiral analyses of Discovery compounds in our research laboratories in Eli Lilly and Company. In this report, we describe an automated screening approach based on gradient elution, in order to achieve accurate enantiomeric excess determinations, and chiral separations when needed, in the shortest possible timeframe. Baseline resolution of enantiomers has been obtained for over 85% of the samples so tested. For the remaining cases, complete enantioseparation by isocratic optimisation is generally achieved in a single shot. This technique has been proven to be robust and is now standard operating procedure at our analytical research laboratories.

  20. Normal-phase high-performance counter-current chromatography for the fractionation of dissolved organic matter from a freshwater source.

    PubMed

    Sandron, Sara; Nesterenko, Pavel N; McCaul, Margaret V; Kelleher, Brian; Paull, Brett

    2014-01-01

    Normal-phase high-performance counter-current chromatography (HPCCC) is used to obtain a preliminary fractionation of components in dissolved organic matter (DOM) from a freshwater source. The HPCCC solvent system involved a normal-phase approach with water/methanol (1:1) as the lower stationary phase and hexane/ethyl acetate (1:1) as the upper mobile phase. The critical experiment parameters were optimised: revolution speed 1800 rpm and flow rate 0.15 mL/min. Under these conditions 50 μL of a 0.50 mg/mL DOM solution was loaded. The detection wavelength was monitored at 330 nm in order to isolate the main portion of DOM, which includes substances such as carboxyl-rich alicyclic molecules. By optimising this system it was possible to isolate materials that, according to GC-MS, can be related to molecules with an analogous structural background. Where fraction analysis was not suitable for GC-MS, RP-HPLC with UV absorbance detection was used, showing unique chromatograms for each fraction at both 210 and 330 nm. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Migration of lubricants from food packagings. Screening for lipid classes and quantitative estimation using normal-phase liquid chromatographic separation with evaporative light scattering detection.

    PubMed

    Schaefer, A; Küchler, T; Simat, T J; Steinhart, H

    2003-10-31

    A normal-phase high-performance liquid chromatography (NP-HPLC) method is introduced for the identification and quantitative estimation of 12 lipid classes (paraffin, wax esters, cholesterol esters, fatty acid methyl esters, triacyl glycerols, fatty alcohols, free fatty acids, cholesterol, 1,3-diacyl glycerols, 1,2-diacyl glycerols, monoacyl glycerols and fatty acid amide) used as lubricantsin food packaging materials. The HPLC separation is carried out on a LiChrospher Diol (100 A, 5 microm, 125 mm x 3 mm) column with gradient elution (isooctane/0.1% acetic acid in tert-butyl methyl ether) and evaporative light scattering detection (ELSD). The method has been calibrated with representatives of each class in working ranges of about 5-150 mg/l, depending on the lipid class. Intra-day variance for all representatives range from 1.9 to 5.1%, inter-day variances from 7.0 to 26.5% and the limits of detection from 0.79 to 3.65 mg/l (except for two classes). A simple sample preparation could be established for the determination of migrating lubricants obtained from packaging materials containing external or internal lubricants. Since the detector response depends on the chain length and the degree of saturation, the quantification of a lipid class with unknown composition is only semi-quantitative. The amount of migrating lubricants from an epoxy-based can coating could be estimated with 0.3 mg/dm2 and from a light weight container with 5.5 mg/dm2.

  2. Quantitative structure-retardation factor relationship of protein amino acids in different solvent mixtures for normal-phase thin-layer chromatography.

    PubMed

    Yousefinejad, Saeed; Honarasa, Fatemeh; Saeed, Negar

    2015-05-01

    A quantitative predictive/descriptive model was proposed for the retardation factors of protein amino acids in normal-phase thin-layer chromatography. The experimental retardation factors of 126 chromatographic mixtures (21 protein amino acids in different mobile phases) were used as the independent variable. The matrix of dependent variables of the model was built using structural descriptors of amino acids and empirical parameters of solvents of the applied mobile phases. After variable selection, a five-parametr model was proposed for the retardation factor of amino acids, which covered about 84 and 77% variance of data in training and cross-validation, respectively. The correlation coefficient of the external test set was 0.80, which shows the prediction potential of proposed model as well as its good applicability domain that was checked using a standardized residual-leverage plot. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Liquid chromatography/tandem mass spectrometry of dolichols and polyprenols, lipid sugar carriers across evolution*

    PubMed Central

    Guan, Ziqiang; Eichler, Jerry

    2012-01-01

    Across evolution, dolichols and polyprenols serve as sugar carriers in biosynthetic processes that include protein glycosylation and lipopolysaccharide biogenesis. Liquid chromatography coupled with electrospray ionization mass spectrometry offers a powerful tool for studying dolichols and polyprenols in their alcohol or glycan-modified forms in members of all three domains of life. In the following, recent examples of the how different versions of this analytical approach, namely reverse phase liquid chromatography-multiple reaction monitoring, normal phase liquid chromatography/tandem mass spectrometry and normal phase liquid chromatography-precursor ion scan detection have respectively served to address novel aspects of dolichol or polyprenol biology in Eukarya, Archaea and Bacteria. This article is part of a Special Issue entitled Lipodomics and Imaging Mass Spectrometry. PMID:21570481

  4. Qualitative and quantitative analysis of hyaluronan oligosaccharides with high performance thin layer chromatography using reagent-free derivatization on amino-modified silica and electrospray ionization-quadrupole time-of-flight mass spectrometry coupling on normal phase.

    PubMed

    Rothenhöfer, Martin; Scherübl, Rosmarie; Bernhardt, Günther; Heilmann, Jörg; Buschauer, Armin

    2012-07-27

    Purified oligomers of hyalobiuronic acid are indispensable tools to elucidate the physiological and pathophysiological role of hyaluronan degradation by various hyaluronidase isoenzymes. Therefore, we established and validated a novel sensitive, convenient, rapid, and cost-effective high performance thin layer chromatography (HPTLC) method for the qualitative and quantitative analysis of small saturated hyaluronan oligosaccharides consisting of 2-4 hyalobiuronic acid moieties. The use of amino-modified silica as stationary phase allows a simple reagent-free in situ derivatization by heating, resulting in a very low limit of detection (7-19 pmol per band, depending on the analyzed saturated oligosaccharide). By this derivatization procedure for the first time densitometric quantification of the analytes could be performed by HPTLC. The validated method showed a quantification limit of 37-71 pmol per band and was proven to be superior in comparison to conventional detection of hyaluronan oligosaccharides. The analytes were identified by hyphenation of normal phase planar chromatography to mass spectrometry (TLC-MS) using electrospray ionization. As an alternative to sequential techniques such as high performance liquid chromatography (HPLC) and capillary electrophoresis (CE), the validated HPTLC quantification method can easily be automated and is applicable to the analysis of multiple samples in parallel. Copyright © 2012 Elsevier B.V. All rights reserved.

  5. Fluorescent high-performance liquid chromatography assay for lipophilic alcohols.

    PubMed

    Nelson, Thomas J

    2011-12-01

    A new ultrasensitive fluorescent derivatization procedure for chromatographic analysis of primary, secondary, and nonpolar tertiary alcohols is described. The procedure uses Bodipy FL in basic dichloromethane solution with Mukaiyama's reagent (2-chloro-1-methylpyridinium iodide) to form highly fluorescent ester derivatives that can be separated by silica normal-phase high-performance liquid chromatography (HPLC). Rhodamine WT and Oregon green 488 were also useful derivatization reagents. The detection limit for detection of cholesterol and bryostatin by Bodipy FL was less than 1fmol. The reaction conditions are gentle enough that low concentrations of unstable alcohols such as bryostatin 1 can be measured. Copyright © 2011 Elsevier Inc. All rights reserved.

  6. Tandem mass spectrometry with online high-flow reversed-phase extraction and normal-phase chromatography on silica columns with aqueous-organic mobile phase for quantitation of polar compounds in biological fluids.

    PubMed

    Deng, Yuzhong; Zhang, Hongwei; Wu, Jing-Tao; Olah, Timothy V

    2005-01-01

    In this work, high-flow online reversed-phase extraction was coupled with normal phase on silica columns with aqueous-organic mobile phase liquid chromatography/tandem mass spectrometry (LC/MS/MS) to quantify drug candidates in biological fluids. The orthogonal separation effect obtained from this configuration considerably reduced matrix effects and increased sensitivity for highly polar compounds as detected by selected reaction monitoring. This approach also significantly improved the robustness and limit of detection of the assays. An evaluation of this system was performed using a mixture of albuterol and bamethan in rat plasma. Assay validation demonstrated acceptable accuracy (< 8% difference) and precision (< 6% CV) for these model compounds. The system has been used for the quantitation of polar ionic compounds in biological fluids in support of drug discovery programs. This assay was used to analyze samples for a BMS proprietary compound (A) in a rat pharmacokinetic study and is shown as an example to demonstrate the precision, accuracy, and sufficient sensitivity of this system.

  7. Liquid-phase chromatography detector

    DOEpatents

    Voigtman, E.G.; Winefordner, J.D.; Jurgensen, A.R.

    1983-11-08

    A liquid-phase chromatography detector comprises a flow cell having an inlet tubular conduit for receiving a liquid chromatographic effluent and discharging it as a flowing columnar stream onto a vertically adjustable receiving surface spaced apart from and located vertically below and in close proximity to the discharge end of the tubular conduit; a receiver adapted to receive liquid overflowing from the receiving surface; an exit conduit for continuously removing liquid from the receiver; a light source for focusing fluorescence-producing light pulses on the flowing columnar stream as it passes from the outlet of the conduit to the receiving surface and a fluorescence detector to detect the produced fluorescence; a source of light pulse for producing acoustic waves in the columnar stream as it passes from the conduit outlet to the receiving surface; and a piezoelectric transducer adapted to detect those waves; and a source of bias voltage applied to the inlet tubular conduit and adapted to produce ionization of the liquid flowing through the flow cell so as to produce photocurrents therein and an electrical system to detect and record the photocurrents. This system is useful in separating and detecting individual chemical compounds from mixtures thereof. 5 figs.

  8. Liquid-phase chromatography detector

    DOEpatents

    Voigtman, Edward G.; Winefordner, James D.; Jurgensen, Arthur R.

    1983-01-01

    A liquid-phase chromatography detector comprising a flow cell having an inlet tubular conduit for receiving a liquid chromatographic effluent and discharging it as a flowing columnar stream onto a vertically adjustable receiving surface spaced apart from and located vertically below and in close proximity to the discharge end of the tubular conduit; a receiver adapted to receive liquid overflowing from the receiving surface; an exit conduit for continuously removing liquid from the receiver; a light source for focussing fluorescence-producing light pulses on the flowing columnar stream as it passes from the outlet of the conduit to the receiving surface and a fluorescence detector to detect the produced fluorescence; a source of light pulse for producing acoustic waves in the columnar stream as it passes from the conduit outlet to the receiving surface; and a piezoelectric transducer adapted to detect those waves; and a source of bias voltage applied to the inlet tubular conduit and adapted to produce ionization of the liquid flowing through the flow cell so as to produce photocurrents therein and an electrical system to detect and record the photocurrents. This system is useful in separating and detecting individual chemical compounds from mixtures thereof.

  9. Mixed Stationary Liquid Phases for Gas-Liquid Chromatography.

    ERIC Educational Resources Information Center

    Koury, Albert M.; Parcher, Jon F.

    1979-01-01

    Describes a laboratory technique for use in an undergraduate instrumental analysis course that, using the interpretation of window diagrams, prepares a mixed liquid phase column for gas-liquid chromatography. A detailed procedure is provided. (BT)

  10. Mixed Stationary Liquid Phases for Gas-Liquid Chromatography.

    ERIC Educational Resources Information Center

    Koury, Albert M.; Parcher, Jon F.

    1979-01-01

    Describes a laboratory technique for use in an undergraduate instrumental analysis course that, using the interpretation of window diagrams, prepares a mixed liquid phase column for gas-liquid chromatography. A detailed procedure is provided. (BT)

  11. Liquid phase chromatography on microchips.

    PubMed

    Kutter, Jörg P

    2012-01-20

    Over the past twenty years, the field of microfluidics has emerged providing one of the main enabling technologies to realize miniaturized chemical analysis systems, often referred to as micro-Total Analysis Systems (uTAS), or, more generally, Lab-on-a-Chip Systems (LOC) [1,2]. While microfluidics was driven forward a lot from the engineering side, especially with respect to ink jet and dispensing technology, the initial push and interest from the analytical chemistry community was through the desire to develop miniaturized sensors, detectors, and, very early on, separation systems. The initial almost explosive development of, in particular, chromatographic separation systems on microchips, has, however, slowed down in recent years. This review takes a closer, critical look at how liquid phase chromatography has been implemented in miniaturized formats over the past several years, what is important to keep in mind when developing or working with separations in a miniaturized format, and what challenges and pitfalls remain. Copyright © 2011 Elsevier B.V. All rights reserved.

  12. Low thermal mass liquid chromatography.

    PubMed

    Gu, Binghe; Cortes, Hernan; Luong, Jim; Pursch, Matthias; Eckerle, Patric; Mustacich, Robert

    2009-02-15

    A novel technique, low thermal mass liquid chromatography (LTMLC), is introduced in this study. The use of an LTM assembly that utilizes the principle of resistive wire heating and a temperature sensor to accurately deliver unprecedented heating (up to 1800 degrees C/min) or cooling (100 to approximately 200 degrees C/min) rates is reported. With the use of packed microcolumns (<0.5 mm i.d.), essentially instantaneous heat transfer from the assembly to the mobile phase was obtained. A systematic investigation was conducted to study the performance of the LTMLC technique. Both isocratic and gradient mobile phase conditions were used. For temperature control, isothermal, temperature-increasing, and temperature-decreasing gradients were applied. Three model mixtures, two of which containing neutral and acidic analytes and the other containing neutral, acidic, and basic analytes, were used to study the effect of temperature on elution time, resolution, column efficiency, and selectivity. It was found that the LTMLC experimental setup delivered reliable temperature control, as evidenced by linear van't Hoff plots for neutral and acidic compounds. The effect of temperature on the elution of basic analytes yielded nonlinear van't Hoff plots, explaining the dramatic selectivity changes observed for bases with changes in column temperature. Column efficiency generally increased with the increase in column temperature in the range of 25 to approximately 75 degrees C and decreased in the range of 75 to approximately 150 degrees C at a fixed column flow rate (3 microL/min), when extra column band broadening was taken into account. The increase in efficiency upon the increase in column temperature in the low temperature range was mainly due to the decreased mass transfer term resulting from increased analyte diffusivity. However, under even higher temperatures, the longitudinal diffusion dominated band broadening, explaining the decrease in column efficiency upon a further

  13. Liquid chromatography detection unit, system, and method

    SciTech Connect

    Derenzo, Stephen E.; Moses, William W.

    2015-10-27

    An embodiment of a liquid chromatography detection unit includes a fluid channel and a radiation detector. The radiation detector is operable to image a distribution of a radiolabeled compound as the distribution travels along the fluid channel. An embodiment of a liquid chromatography system includes an injector, a separation column, and a radiation detector. The injector is operable to inject a sample that includes a radiolabeled compound into a solvent stream. The position sensitive radiation detector is operable to image a distribution of the radiolabeled compound as the distribution travels along a fluid channel. An embodiment of a method of liquid chromatography includes injecting a sample that comprises radiolabeled compounds into a solvent. The radiolabeled compounds are then separated. A position sensitive radiation detector is employed to image distributions of the radiolabeled compounds as the radiolabeled compounds travel along a fluid channel.

  14. Environmental analyses utilizing gas and liquid chromatography

    SciTech Connect

    Grob, R.L. )

    1993-01-01

    An overview of the various methods of analysis, in environmental studies, which utilizes gas chromatography (GC), liquid chromatography (HPLC), and ion chromatography (IC) is presented. In many cases the samples must be prepared for final measurement by employing other analytical techniques; eg., extraction (liquid-liquid, both micro and macro scale; solid-phase (SPE); supercritical fluid (SFE); headspace equilibration (HSGE); etc.). Details of the various methods will not be given but descriptive explanations and pertinent references will be furnished. Theoretical aspects of the various techniques will be referenced adequately for those not familiar with the methodologies. Since most of these methods are validated by the US Environmental Protection Agency (USEPA) addresses where the methods may be obtained will also be given.

  15. Evaporative light scattering detector in normal-phase high-performance liquid chromatography determination of FAME oxidation products.

    PubMed

    Morales, Arturo; Marmesat, Susana; Dobarganes, M Carmen; Márquez-Ruiz, Gloria; Velasco, Joaquín

    2012-09-07

    The use of an ELS detector in NP-HPLC for quantitative analysis of oxidation products in FAME obtained from oils is evaluated in this study. The results obtained have shown that the ELS detector enables the quantitative determination of the hydroperoxides of oleic and linoleic acid methyl esters as a whole, and connected in series with a UV detector makes it possible to determine both groups of compounds by difference, providing useful complementary information. The limits of detection (LOD) and quantification (LOQ) found for hydroperoxides were respectively 2.5 and 5.7 μg mL⁻¹ and precision of quantitation expressed as coefficient of variation was lower than 10%. Due to a low sensitivity the ELS detector shows limitations to determine the low contents of secondary oxidation products in the direct analysis of FAME oxidized at low or moderate temperature. Analysis of FAME samples obtained either from high linoleic sunflower oil (HLSO) or high oleic sunflower oil (HOSO) and oxidized at 80 °C showed that only ketodienes formed from methyl linoleate can be determined in samples with relatively high oxidation, being the LOD and LOQ 0.2 and 0.4 mg/g FAME, respectively, at the analytical conditions applied. The ELS detector also enabled the determination of methyl cis-9,10-epoxystearate and methyl trans-9,10-epoxystearate, which were resolved at the chromatographic conditions applied. Results showed that these compounds, which are formed from methyl oleate, were not detected in the high-linoleic sample, but occurred at non-negligible levels in the oxidized FAME obtained from HOSO. Copyright © 2012 Elsevier B.V. All rights reserved.

  16. Adsorption of water from aqueous acetonitrile on silica-based stationary phases in aqueous normal-phase liquid chromatography.

    PubMed

    Soukup, Jan; Jandera, Pavel

    2014-12-29

    Excess adsorption of water from aqueous acetonitrile mobile phases was investigated on 16 stationary phases using the frontal analysis method and coulometric Karl-Fischer titration. The stationary phases include silica gel and silica-bonded phases with different polarities, octadecyl and cholesterol, phenyl, nitrile, pentafluorophenylpropyl, diol and zwitterionic sulfobetaine and phosphorylcholine ligands bonded on silica, hybrid organic-silica and hydrosilated matrices. Both fully porous and core-shell column types were included. Preferential uptake of water by the columns can be described by Langmuir isotherms. Even though a diffuse rather than a compact adsorbed discrete layer of water on the adsorbent surface can be formed because of the unlimited miscibility of water with acetonitrile, for convenience, the preferentially adsorbed water was expressed in terms of a hypothetical monomolecular water layer equivalent in the inner pores. The uptake of water strongly depends on the polarity and type of the column. Less than one monomolecular water layer equivalent was adsorbed on moderate polar silica hydride-based stationary phases, Ascentis Express F5 and Ascentis Express CN column at the saturation capacity, while on more polar stationary phases, several water layer equivalents were up-taken from the mobile phase. The strongest affinity to water was observed on the ZIC cHILIC stationary phases, where more than nine water layer equivalents were adsorbed onto its surface at its saturation capacity. Columns with bonded hydroxyl and diol ligands show stronger water adsorption in comparison to bare silica. Columns based on hydrosilated silica generally show significantly decreased water uptake in comparison to stationary phases bonded on ordinary silica. Significant correlations were found between the water uptake and the separation selectivity for compounds with strong polarity differences.

  17. Instrument platforms for nano liquid chromatography.

    PubMed

    Šesták, Jozef; Moravcová, Dana; Kahle, Vladislav

    2015-11-20

    The history of liquid chromatography started more than a century ago and miniaturization and automation are two leading trends in this field. Nanocolumn liquid chromatography (nano LC) and largely synonymous capillary liquid chromatography (capillary LC) are the most recent results of this process where miniaturization of column dimensions and sorbent particle size play crucial role. Very interesting results achieved in the research of extremely miniaturized LC columns at the end of the last century lacked distinctive raison d'être and only advances in mass spectrometry brought a real breakthrough. Configuration of nano LC-electrospray ionization mass spectrometry (LC-ESI-MS) has become a basic tool in bioanalytical chemistry, especially in proteomics. This review discusses and summarizes past and current trends in the realization of nano liquid chromatography (nano LC) platforms. Special attention is given to the mobile phase delivery under nanoflow rates (isocratic, gradient) and sample injection to the nanocolumn. Available detection techniques applied in nano LC separations are also briefly discussed. We followed up the key themes from the original scientific reports over gradual improvements up to the contemporary commercial solutions. Copyright © 2015 Elsevier B.V. All rights reserved.

  18. Analysis of polymethacrylate additive by liquid chromatography

    SciTech Connect

    Fialko, M.M.; Lupanova, N.A.; Mishina, G.Y.; Urman, D.G.

    1983-11-01

    This paper recommends replacing the process of extraction with acetone for determining the content of active substance in polymethacrylate viscosity index improvers and pour-point depressants with liquid chromatography, which offers a more thorough analysis of the contents. An example of the separation process and anlysis is given.

  19. Chromatographic behavior of small organic compounds in low-temperature high-performance liquid chromatography using liquid carbon dioxide as the mobile phase.

    PubMed

    Motono, Tomohiro; Nagai, Takashi; Kitagawa, Shinya; Ohtani, Hajime

    2015-07-01

    Low-temperature high-performance liquid chromatography, in which a loop injector, column, and detection cell were refrigerated at -35ºC, using liquid carbon dioxide as the mobile phase was developed. Small organic compounds (polyaromatic hydrocarbons, alkylbenzenes, and quinones) were separated by low-temperature high-performance liquid chromatography at temperatures from -35 to -5ºC. The combination of liquid carbon dioxide mobile phase with an octadecyl-silica (C18 ) column provided reversed phase mode separation, and a bare silica-gel column resulted in normal phase mode separation. In both the cases, nonlinear behavior at approximately -15ºC was found in the relationship between the temperature and the retention factors of the analytes (van't Hoff plots). In contrast to general trends in high-performance liquid chromatography, the decrease in temperature enhanced the separation efficiency of both the columns.

  20. High Performance Liquid Chromatography Experiments to Undergraduate Laboratories

    ERIC Educational Resources Information Center

    Kissinger, Peter T.; And Others

    1977-01-01

    Reviews the principles of liquid chromatography with electrochemical detection (LCEC), an analytical technique that incorporates the advantages of both liquids chromatography and electrochemistry. Also suggests laboratory experiments using this technique. (MLH)

  1. High Performance Liquid Chromatography Experiments to Undergraduate Laboratories

    ERIC Educational Resources Information Center

    Kissinger, Peter T.; And Others

    1977-01-01

    Reviews the principles of liquid chromatography with electrochemical detection (LCEC), an analytical technique that incorporates the advantages of both liquids chromatography and electrochemistry. Also suggests laboratory experiments using this technique. (MLH)

  2. Comparison of liquid and supercritical fluid chromatography mobile phases for enantioselective separations on polysaccharide stationary phases.

    PubMed

    Khater, Syame; Lozac'h, Marie-Anne; Adam, Isabelle; Francotte, Eric; West, Caroline

    2016-10-07

    Analysis and production of enantiomerically pure compounds is a major topic of interest when active pharmaceutical ingredients are concerned. Enantioselective chromatography has become a favourite both at the analytical and preparative scales. High-performance liquid chromatography (HPLC) and supercritical fluid chromatography (SFC) are dominating the scene and are often seen as complementary techniques. Nowadays, for economic and ecologic reasons, SFC may be preferred over normal-phase HPLC (NPLC) as it allows significant reductions in solvent consumption. However, the transfer of NPLC methods to SFC is not always straightforward. In this study, we compare the retention of achiral molecules and separation of enantiomers under supercritical fluid (carbon dioxide with ethanol or isopropanol) and liquid normal-phase (heptane with ethanol or isopropanol) elution modes with polysaccharide stationary phases in order to explore the differences between the retention and enantioseparation properties between the two modes. Chemometric methods (namely quantitative structure-retention relationships and discriminant analysis) are employed to compare the results obtained on a large set of analytes (171 achiral probes and 97 racemates) and gain some understanding on the retention and separation mechanisms. The results indicate that, contrary to popular belief, carbon dioxide - solvent SFC mobile phases are often weaker eluents than liquid mobile phases. It appears that SFC and NPLC elution modes provide different retention mechanisms. While some enantioseparations are unaffected, facilitating the transfer between the two elution modes, other enantioseparations may be drastically different due to different types and strength of interactions contributing to enantioselectivity.

  3. High Performance Liquid Chromatography/Video Fluorometry. Part I. Instrumentation.

    DTIC Science & Technology

    1981-09-30

    High Performance Liquid Chromatography /Video...PERIOD COVERED High Performance Liquid Chromatography /Video .. / Fluorometry. Part I. Instrumentation. . Interim/ echnicaliepart,. 6. PERFORMING ORG...34Entered SECURITY CLASSIFICATION OF THIS OlAGE (When Data Entered) II1| III I I I I E I II ... .. High Performance Liquid Chromatography

  4. Recent development of ionic liquid stationary phases for liquid chromatography.

    PubMed

    Shi, Xianzhe; Qiao, Lizhen; Xu, Guowang

    2015-11-13

    Based on their particular physicochemical characteristics, ionic liquids have been widely applied in many fields of analytical chemistry. Many types of ionic liquids were immobilized on a support like silica or monolith as stationary phases for liquid chromatography. Moreover, different approaches were developed to bond covalently ionic liquids onto the supporting materials. The obtained ionic liquid stationary phases show multi-mode mechanism including hydrophobic, hydrophilic, hydrogen bond, anion exchange, π-π, and dipole-dipole interactions. Therefore, they could be used in different chromatographic modes including ion-exchange, RPLC, NPLC and HILIC to separate various classes of compounds. This review mainly summarizes the immobilized patterns and types of ionic liquid stationary phases, their retention mechanisms and applications in the recent five years.

  5. High perfomance liquid chromatography in pharmaceutical analyses.

    PubMed

    Nikolin, Branko; Imamović, Belma; Medanhodzić-Vuk, Saira; Sober, Miroslav

    2004-05-01

    In testing the pre-sale procedure the marketing of drugs and their control in the last ten years, high performance liquid chromatography replaced numerous spectroscopic methods and gas chromatography in the quantitative and qualitative analysis. In the first period of HPLC application it was thought that it would become a complementary method of gas chromatography, however, today it has nearly completely replaced gas chromatography in pharmaceutical analysis. The application of the liquid mobile phase with the possibility of transformation of mobilized polarity during chromatography and all other modifications of mobile phase depending upon the characteristics of substance which are being tested, is a great advantage in the process of separation in comparison to other methods. The greater choice of stationary phase is the next factor which enables realization of good separation. The separation line is connected to specific and sensitive detector systems, spectrafluorimeter, diode detector, electrochemical detector as other hyphernated systems HPLC-MS and HPLC-NMR, are the basic elements on which is based such wide and effective application of the HPLC method. The purpose high performance liquid chromatography (HPLC) analysis of any drugs is to confirm the identity of a drug and provide quantitative results and also to monitor the progress of the therapy of a disease.1) Measuring presented on the Fig. 1. is chromatogram obtained for the plasma of depressed patients 12 h before oral administration of dexamethasone. It may also be used to further our understanding of the normal and disease process in the human body trough biomedical and therapeutically research during investigation before of the drugs registration. The analyses of drugs and metabolites in biological fluids, particularly plasma, serum or urine is one of the most demanding but one of the most common uses of high performance of liquid chromatography. Blood, plasma or serum contains numerous endogenous

  6. Analysis of doxylamine in plasma by high-performance liquid chromatography.

    PubMed

    Kohlhof, K J; Stump, D; Zizzamia, J A

    1983-08-01

    A rapid and sensitive high-performance liquid chromatographic (HPLC) assay for the quantitative determination of doxylamine in plasma is described. The drug levels of doxylamine in plasma were monitored after the oral administration of a single 25-mg tablet of doxylamine succinate to each of 20 male volunteers. The compound was extracted from the plasma samples, concentrated under a nitrogen stream, and analyzed by HPLC using normal-phase chromatography with detection at 254 nm. The detection limit is approximately 5 ng/ml.

  7. Fast, comprehensive two-dimensional liquid chromatography

    PubMed Central

    Stoll, Dwight R.; Li, Xiaoping; Wang, Xiaoli; Carr, Peter W.; Porter, Sarah E. G.; Rutan, Sarah C.

    2011-01-01

    The absolute need to improve the separating power of liquid chromatography, especially for multi-constituent biological samples, is becoming increasingly evident. In response, over the past few years, there has been a great deal of interest in the development of two dimension liquid chromatography (2DLC). Just as 1DLC is preferred to 1DGC based on its compatibility with biological materials we believe that ultimately 2DLC will be preferred to the much more highly developed 2DGC for such samples. The huge advantage of 2D chromatographic techniques over 1D methods is inherent in the tremendous potential increase in peak capacity (resolving power). This is especially true of comprehensive 2D chromatography wherein it is possible, under ideal conditions, to obtain a total peak capacity equal to the product of the peak capacities of the first and second dimension separations. However, the very long timescale (typically several hours to tens of hours) of comprehensive 2DLC is clearly its chief drawback. Recent advances in the use of higher temperatures to speed up isocratic and gradient elution liquid chromatography have been used to decrease the time needed to do the second dimension LC separation of 2DLC to about 20 seconds for a full gradient elution run. Thus fast, high temperature LC is becoming a very promising technique. Peak capacities of over 2000 and rates of peak capacity production of nearly 1 peak/s have been achieved. In consequence, many real samples showing more than 200 peaks with signal to noise ratios of better than 10:1 have been run in total times of under 30 minutes. This report is not intended to be a comprehensive review of 2DLC, but is deliberately focused on the issues involved in doing fast 2DLC by means of elevating the column temperature; however, many issues of broader applicability will be discussed. PMID:17888443

  8. Recent applications of hydrophilic interaction liquid chromatography in pharmaceutical analysis.

    PubMed

    Zhang, Qian; Yang, Feng-Qing; Ge, Liya; Hu, Yuan-Jia; Xia, Zhi-Ning

    2017-01-01

    Hydrophilic interaction liquid chromatography, an alternative liquid chromatography mode, is of particular interest in separating hydrophilic and polar ionic compounds. Compared with traditional liquid chromatography techniques, hydrophilic interaction liquid chromatography offers specific advantages mainly including: (1) relatively green and water-soluble mobile phase composition, which enhances the solubility of hydrophilic and polar ionic compounds; (2) no need for ion-pairing reagents and high content of organic solvent, which benefits mass spectrometry detection; (3) high orthogonality to reverse-phase liquid chromatography, well adapted to two-dimensional liquid chromatography for complicated samples. Therefore, hydrophilic interaction liquid chromatography has been rapidly developed in many areas over the past decades. This review summarizes the recent progress (from 2012 to July 2016) of hydrophilic interaction liquid chromatography in pharmaceutical analysis, with the focus on detecting chemical drugs in various matrices, charactering active compounds of natural products and assessing biotherapeutics through typical structure unit. Moreover, the retention mechanism and behavior of analytes in hydrophilic interaction liquid chromatography as well as some novel hydrophilic interaction liquid chromatography columns used for pharmaceutical analysis are also described.

  9. Csaba Horvath and preparative liquid chromatography

    SciTech Connect

    Guiochon, Georges A

    2005-07-01

    Few chromatographers have been interested in furthering preparative liquid chromatography. The pioneers, Tswett, Kuhn and Lederer, A.J.P. Martin, Tiselius, isolated fractions but as an intermediate step in the analysis of their samples. The progress in electronics and sensors, and in their miniaturization has lead to the paradoxical situation that the analysts never see the transient pure fractions that their detector quantitates. Yet, over the last 25 years, preparative liquid chromatography has become an important industrial process for the separation, the extraction, and/or the purification of many pharmaceuticals or pharmaceutical intermediates, including pure enantiomers, purified peptides and proteins, compounds that are manufactured at the relatively large industrial scale of a few kilograms to several hundred tons per year. This development that has strongly affected the modern pharmaceutical industry is mainly due to the pioneering work of Csaba Horvath. His work in preparative HPLC was critical at both the practical and the theoretical levels. He was the first scientist in modern times to pay serious attention to the relationships between the curvature of the equilibrium isotherms, the competitive nature of nonlinear isotherms, and the chromatographic band profiles of complex mixtures. The thermodynamics of multi-component phase equilibria and mass transfer kinetics in chromatography attracted his interest and were the focus of ground-breaking contributions. He investigated displacement chromatography, an old method invented by Tiselius that Csaba was first to implement in HPLC. This choice was explained by the essential characteristic of displacement chromatography, in that it delivers fractions that can be far more concentrated than the feed. Remarkably, once the basics of nonlinear chromatography had been mastered in his group, most of the applications that were studied by his coworkers dealt with peptides of various sizes and with proteins. Thus, all

  10. Spillage detector for liquid chromatography systems

    NASA Technical Reports Server (NTRS)

    Jarvis, M. J.; Fulton, D. S. (Inventor)

    1986-01-01

    A spillage detector device for use in conjunction with fractionation of liquid chromatography systems which includes a spillage recieving enclosure beneath the fractionation area is described. A sensing device having a plurality of electrodes of alternating polarity is mounted within the spillage recieving enclosure. Detection circuitry, responsive to conductivity between electrodes, is operatively connected to the sensing device. The detection circuitry feeds into the output circuitry. The output circuit has relaying and switching circuitry directed to a solenoid, an alarm system and a pump. The solenoid is connected to the pliable conduit of the chromatography system. The alarm system comprises an audio alarm and a visual signal. A 115-volt power system interconnected with the pump, the solenoid, the sensing device, and the detection and output circuitry.

  11. Hydrophilic interaction liquid chromatography in food analysis.

    PubMed

    Bernal, José; Ares, Ana M; Pól, Jaroslav; Wiedmer, Susanne K

    2011-10-21

    The use of hydrophilic interaction liquid chromatography (HILIC) in food analysis in the last decade is reviewed. The HILIC mechanism is briefly discussed, but main emphasis is put on the use of HILIC for separation of different food matrices. The food matrices are divided into food of animal origin and related products, vegetables, fruits and related compounds, and other food-related matrices. A list on important applications is provided for each category including experimental conditions and a brief summary of the results. The 100 references included will provide the reader a comprehensive overview and insight into HILIC applications to food analysis. Copyright © 2011 Elsevier B.V. All rights reserved.

  12. High Performance Liquid Chromatography/Video Fluorometry. Part II. Applications.

    DTIC Science & Technology

    1981-09-30

    HIGH PERFORMANCE LIQUID CHROMATOGRAPHY /VIDEO FLUOROMETRY. PART...REP«T_N&:-ŗ/ High Performance Liquid Chromatography /Video Fluorometry» Part II. Applications« by | Dennis C./Shelly* Michael P./Vogarty and...Data EnlirtdJ REPORT DOCUMENTATION PAGE t. REPORT NUMBER 2 GOVT ACCESSION NO 4. T1TI.F (and Submit) lP-^fffsyva High Performance Liquid Chromatography

  13. Separation of biological proteins by liquid chromatography

    PubMed Central

    Ali, Imran; Aboul-Enein, Hassan Y.; Singh, Prashant; Singh, Rakesh; Sharma, Bhavtosh

    2010-01-01

    After the success of human genome project, proteome is a new emerging field of biochemistry as it provides the knowledge of enzymes (proteins) interactions with different body organs and medicines administrated into human body. Therefore, the study of proteomics is very important for the development of new and effective drugs to control many lethal diseases. In proteomics study, analyses of proteome is essential and significant from the pathological point of views, i.e., in several serious diseases such as cancer, Alzheimer’s disease and aging, heart diseases and also for plant biology. The separation and identification of proteomics is a challenging job due to their complex structures and closely related physico-chemical behaviors. However, the recent advances in liquid chromatography make this job easy. Various kinds of liquid chromatography, along with different detectors and optimization strategies, have been discussed in this article. Besides, attempts have been made to include chirality concept in proteomics for understanding mechanism and medication of various disease controlled by different body proteins. PMID:23960722

  14. Fast and comprehensive analysis of secondary metabolites in cocoa products using ultra high-performance liquid chromatography directly after pressurized liquid extraction.

    PubMed

    Damm, Irina; Enger, Eileen; Chrubasik-Hausmann, Sigrun; Schieber, Andreas; Zimmermann, Benno F

    2016-08-01

    Fast methods for the extraction and analysis of various secondary metabolites from cocoa products were developed and optimized regarding speed and separation efficiency. Extraction by pressurized liquid extraction is automated and the extracts are analyzed by rapid reversed-phase ultra high-performance liquid chromatography and normal-phase high-performance liquid chromatography methods. After extraction, no further sample treatment is required before chromatographic analysis. The analytes comprise monomeric and oligomeric flavanols, flavonols, methylxanthins, N-phenylpropenoyl amino acids, and phenolic acids. Polyphenols and N-phenylpropenoyl amino acids are separated in a single run of 33 min, procyanidins are analyzed by normal-phase high-performance liquid chromatography within 16 min, and methylxanthins require only 6 min total run time. A fourth method is suitable for phenolic acids, but only protocatechuic acid was found in relevant quantities. The optimized methods were validated and applied to 27 dark chocolates, one milk chocolate, two cocoa powders and two food supplements based on cocoa extract. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Liquid Chromatography Mass Spectrometry Profiling of Histones

    PubMed Central

    Su, Xiaodan; Jacob, Naduparambil K.; Amunugama, Ravindra; Lucas, David M.; Knapp, Amy R.; Ren, Chen; Davis, Melanie E.; Marcucci, Guido; Parthun, Mark R.; Byrd, John C.; Fishel, Richard A.; Freitas, Michael A.

    2007-01-01

    Here we describe the use of reverse-phase liquid chromatography mass spectrometry (RP-LC-MS) to simultaneously characterize variants and post-translationally modified isoforms for each histone. The analysis of intact proteins significantly reduces the time of sample preparation and simplifies data interpretation. LC-MS analysis and peptide mass mapping have previously been applied to identify histone proteins and to characterize their post-translational modifications. However, these studies provided limited characterization of both linker histones and core histones. The current LC-MS analysis allows for the simultaneous observation of all histone PTMs and variants (both replacement and bulk histones) without further enrichment, which will be valuable in comparative studies. Protein identities were verified by the analysis of histone H2A species using RPLC fractionation, AU-PAGE separation and nano-LC-MS/MS. PMID:17254850

  16. Multidimensional liquid chromatography for the determination of chiral coumarins and furocoumarins in Citrus essential oils.

    PubMed

    Dugo, Paola; Russo, Marina; Sarò, Mariagiovanna; Carnovale, Caterina; Bonaccorsi, Ivana; Mondello, Luigi

    2012-07-01

    In this work the enantiomeric distribution of chiral coumarins (meranzin and epoxyaurapten), and furocoumarins (oxypeucedanin, byakangelicol, and epoxybergamottin) in different Citrus essential oils (lemon, lime, grapefruit, and bitter orange) was determined by means of a heart-cutting multidimensional-liquid chromatography (MD-LC) system, equipped with a microsilica column in the first dimension in a combination to a cellulosic-based chiral column used in the second dimension. The normal phase-liquid chromatography-liquid chromatography (NP-LC-LC) instrumentation was equipped with a photodiode array detector and a multiport valve as interface. For method optimization and the determination of absolute configuration, natural compounds were isolated and racemic mixture was synthesized. The NP-LC-LC/PDA (where PDA is photodiode array) method provided a good baseline separation of chiral coumarins (meranzin and epoxyaurapten) and furocoumarins (epoxybergamottin and byakangelicol) present in cold-pressed Citrus essential oils without any sample pretreatment. Results obtained showed that for all the chiral compounds present in Citrus essential oils analyzed, there is always a clear prevalence of one of the two enantiomers, and do not appear influenced by the different geographical origin of the oils.

  17. Trends in High Performance Liquid Chromatography for Cultural Heritage.

    PubMed

    Degano, Ilaria; La Nasa, Jacopo

    2016-04-01

    The separation, detection and quantitation of specific species contained in a sample in the field of Cultural Heritage requires selective, sensitive and reliable methods. Procedures based on liquid chromatography fulfil these requirements and offer a wide range of applicability in terms of analyte types and concentration range. The main applications of High Performance Liquid Chromatography in this field are related to the separation and detection of dyestuffs in archaeological materials and paint samples by reversed-phase liquid chromatography with suitable detectors. The relevant literature will be revised, with particular attention to sample treatment strategies and future developments. Reversed phase chromatography has also recently gained increasing importance in the analysis of lipid binders and lipid materials in archaeological residues: the main advantages and disadvantages of the new approaches will be discussed. Finally, the main applications of ion chromatography and size exclusion chromatography in the field of Cultural Heritage will be revised in this chapter.

  18. Comparison of hypercrosslinked polystyrene columns for the separation of nitrogen group-types in petroleum using High Performance Liquid Chromatography.

    PubMed

    Oro, Nicole E; Lucy, Charles A

    2010-10-01

    High performance liquid chromatography in a quasi-normal phase mode (QNP) is used to separate the nitrogen group-types (pyrrole and pyridine) that are found in petroleum. A new type of stationary phase, hypercrosslinked polystyrene, is used to achieve this separation. Three different hypercrosslinked polystyrene stationary phases are compared under quasi-normal phase mode; a commercial 5-HGN packing, and two hypercrosslinked phases on silica particles. The utility of the columns for petroleum-based separations was explored with the use of 21 analytical standards. Partial elucidation of adsorption retention mechanisms for the columns are shown, as well as a comparison of retention characteristics for the three columns. The silica particle column derived with toluene (HC-Tol) was found to have the best selectivity for nitrogen group-types and polycyclic aromatic hydrocarbons (PAHs), attaining a separation under gradient conditions in less than 30 min. Copyright © 2010 Elsevier B.V. All rights reserved.

  19. Implementations of two-dimensional liquid chromatography

    SciTech Connect

    Guiochon, Georges A; Marchetti, Nicola; Mriziq, Khaled S; Shalliker, R. Andrew

    2008-01-01

    Today scientists must deal with complex samples that either cannot be adequately separated using one-dimensional chromatography or that require an inordinate amount of time for separation. For these cases we need two-dimensional chromatography because it takes far less time to generate a peak capacity n{sub c} twice in a row than to generate a peak capacity n{sub c}{sup 2} once. Liquid chromatography has been carried out successfully on thin layers of adsorbents and along tubes filled with various adsorbents. The first type of separation sorts out the sample components in a physical separation space that is the layer of packing material. The analysis time is the same for all the components of the sample while their migration distance increases with decreasing retention. The resolution between two components having a certain separation factor (a) increases with increasing migration distance, i.e., from the strongly to the weakly retained compounds. In the second type of separation, the sample components are eluted from the column and separated in the time space, their migration distances are all the same while their retention times increase from the unretained to the strongly retained compounds. Separation efficiency varies little with retention, as long as the components are eluted from the column. We call these two types of separation the chromatographic separations in space (LC{sup x}) and the chromatographic separations in time (LC{sup t}), respectively. In principle, there are four ways to combine these two modes and do two-dimensional chromatographic separations, LC{sup t} x LC{sup t}, LC{sup x} x LC{sup t}, LC{sup t} x LC{sup x}, and LC{sup x} x LC{sup x}. We review, discuss and compare the potential performance of these combinations, their advantages, drawbacks, problems, perspectives and results. Currently, column-based combinations (LC{sup t} x LC{sup t}) are the most actively pursued. We suggest that the combination LC{sup x} x LC{sup t} shows exceptional

  20. Use of high pressure liquid chromatography in the study of liquid lubricant oxidation

    NASA Technical Reports Server (NTRS)

    Morales, W.

    1982-01-01

    The general principles of classical liquid chromatography and high-pressure liquid chromatography (HPLC) are reviewed, and their advantages and disadvantages are compared. Several chromatographic techniques are reviewed, and the analysis of a C-ether liquid lubricant by each technique is illustrated. An analysis by size exclusion chromatography of an ester lubricant, which had been degraded using a micro-oxidation apparatus, is illustrated to show how HPLC can be used in the study of high-temperature lubricant degradation.

  1. Review: Recent application of chiral liquid chromatography-tandem mass spectrometric methods for enantiomeric pharmaceutical and biomedical determinations.

    PubMed

    Nie, Yanfang; Liu, Xiumei; Yang, Xinmei; Zhao, Zhongxi

    2013-09-01

    The technology of analyzing the pharmacological and toxicological properties of chiral drugs has become more commonly utilized since the knowledge of the biological actions of enantiomers has been gradually acquired during the last few decades. This work reviews the applications of chiral liquid chromatography coupled to tandem mass spectrometry (LC-MS) for the analysis of chiral pharmaceuticals since 2005. The enantioselective determinations in pharmaceutical and biomedical fields with LC-MS are classified based on three mobile phase modes, including normal phase, reversed phase and polar organic solvent, in terms of their compatibility with various ionization sources and specific applications.

  2. Determination of alkylphenols and alkylphenol polyethoxylates by reversed-phase high-performance liquid chromatography and solid-phase extraction.

    PubMed

    Takasu, Takuma; Iles, Alexander; Hasebe, Kiyoshi

    2002-02-01

    A simple, accurate and reproducible reversed-phase high-performance liquid chromatography (HPLC) method was developed for the separation and characterisation of alkylphenols (APs) and alkylphenol polyethoxylates (APEOs), using a C18 octadecyl silica (ODS) column. APs and each APEO oligomer were separated successfully within a reasonable time without gradient elution. An excellent resolution was obtained, even for mixtures of APs and low EO number APEOs, which are otherwise difficult to separate using conventional normal-phase HPLC methods. This method, combined with solid-phase extraction, was highly applicable for the simultaneous determination of alkylphenols and alkylphenol ethoxylates in real samples.

  3. Sensitive assay of cytochrome P450scc activity by high-performance liquid chromatography.

    PubMed

    Sugano, S; Morishima, N; Ikeda, H; Horie, S

    1989-11-01

    We have developed a simple procedure for analyzing the reaction intermediates and product of the cholesterol side-chain cleavage system by high-performance liquid chromatography with uv absorption monitoring. After the cholesterol side-chain cleavage system had been incubated and the reaction then halted by heat treatment, the product was converted into 3-one-4-en steroid showing intense absorption at 240 nm upon reaction with cholesterol oxidase. The converted steroids were then analyzed by normal-phase HPLC. In consequence, the catalytic activity of the reconstituted adrenocortical cytochrome P450scc system was readily assayed with a sensitivity more than 10-fold higher by this conversion. Also, it was shown that 22R-hydroxy-cholest-4-en-3-one could serve as a good substrate for cytochrome P450scc and that the 20R,22R-dihydroxy derivative could be clearly detected as a reaction intermediate in the reconstituted system.

  4. A simple assay for lipid hydroperoxides based on triphenylphosphine oxidation and high-performance liquid chromatography.

    PubMed

    Nakamura, T; Maeda, H

    1991-09-01

    A simple and sensitive method was developed to measure total hydroperoxides. After the reduction of hydroperoxides with triphenylphosphine (TP) in cyclohexane at 30°C, the amount of triphenylphosphine oxide (TPO) produced is determined by reverse-phase or normal-phase high-performance liquid chromatography (HPLC) in combination with an ultraviolet (UV)-detector by measuring absorption at 220 or 260 nm. TPO was shown to be gener-ated stoichiometrically by reduction of known amounts of either cumene hydroperoxide or methyl 13-hydroper-oxyoctadecadienoate. For various lipids at low levels of oxidation, the peroxide values determined by this method were in good agreement with those obtained by conventional iodometry. The detection limit of TPO in HPLC using absorption at 220 nm was less than 10 pmol. Consequently, total hydroperoxides in lipids at levels corresponding to less than a peroxide value of 1 can be estimated by the TP method on a 10-mg sample.

  5. A generalized theory of chromatography and multistep liquid extraction

    NASA Astrophysics Data System (ADS)

    Chizhkov, V. P.; Boitsov, V. N.

    2017-03-01

    A generalized theory of chromatography and multistep liquid extraction is developed. The principles of highly efficient processes for fine preparative separation of binary mixture components on a fixed sorbent layer are discussed.

  6. High Performance Liquid Chromatography of Vitamin A: A Quantitative Determination.

    ERIC Educational Resources Information Center

    Bohman, Ove; And Others

    1982-01-01

    Experimental procedures are provided for the quantitative determination of Vitamin A (retinol) in food products by analytical liquid chromatography. Standard addition and calibration curve extraction methods are outlined. (SK)

  7. High Performance Liquid Chromatography of Vitamin A: A Quantitative Determination.

    ERIC Educational Resources Information Center

    Bohman, Ove; And Others

    1982-01-01

    Experimental procedures are provided for the quantitative determination of Vitamin A (retinol) in food products by analytical liquid chromatography. Standard addition and calibration curve extraction methods are outlined. (SK)

  8. Instrumentation for hand-portable liquid chromatography.

    PubMed

    Sharma, Sonika; Plistil, Alex; Simpson, Robert S; Liu, Kun; Farnsworth, Paul B; Stearns, Stanley D; Lee, Milton L

    2014-01-31

    Liquid chromatography (LC) has lagged behind gas chromatography (GC) in developments related to hand-portable instrumentation. In this work, a new battery-operated (24V DC) nano-flow pumping system with a stop-flow injector was developed and integrated with an on-column UV-absorption detector (254nm) that was reduced in size to an acceptable weight and power usage for field operation. The pumping system, which includes nano-flow pump, stepper motor and high-pressure valve weighs only 1.372kg (3lbs) and can generate up to 110.32MPa (16,000psi) pressure. A major advantage of this pump is that it does not employ a splitter, since it was specifically designed for capillary column use. The volume capacity of the pump is 24μL, and a sample volume as low as 10nL can be injected. Flow rate calibration (300nL to 6.12μL per min) was performed, and an accuracy >99.94% was obtained. The percent injection carry-over was found to be low (RSD 0.31%), which makes it practical for quantitative analysis. The detector linear range and limit of detection (LOD) were determined using sodium anthraquinone-2-sulfonate. A linear regression coefficient (R) of 0.9996 was obtained for a plot of log peak area versus log concentration over the range of 3.2μM to 6.5mM, and the LOD (S/N=3) was found to be 7.8fmol (0.13μM). The short term noise of the detector is comparable to commercially available detectors (∼10(-5)AU). In this work, the system was tested in the laboratory using regular line power (120V AC) with an AC to DC adapter. Reversed-phase isocratic separations were performed using a 15.5cm×75μm i.d. fused silica capillary column containing a monolithic stationary phase synthesized from 1,6-hexanediol dimethacrylate. Good retention time repeatability (RSD 0.09-0.74%) was obtained for a mixture containing an unretained marker (i.e., uracil) and a homologous series of alkyl benzenes.

  9. Ion Exchange and Liquid Column Chromatography.

    ERIC Educational Resources Information Center

    Walton, Harold F.

    1980-01-01

    Emphasizes recent advances in principles and methodology in ion exchange and chromatography. Two tables list representative examples for inorganic ions and organic compounds. Cites 544 references. (CS)

  10. Ion Exchange and Liquid Column Chromatography.

    ERIC Educational Resources Information Center

    Walton, Harold F.

    1980-01-01

    Emphasizes recent advances in principles and methodology in ion exchange and chromatography. Two tables list representative examples for inorganic ions and organic compounds. Cites 544 references. (CS)

  11. Chromatography

    MedlinePlus

    Chromatography is a way of separating two or more chemical compounds. Chemical compounds are chemicals that are ... of chemical compound. There are different kinds of chromatography. These include gas, high pressure liquid, or ion ...

  12. Hyphenated and comprehensive liquid chromatography × gas chromatography-mass spectrometry for the identification of Mycobacterium tuberculosis.

    PubMed

    Mourão, Marta P B; Denekamp, Ilse; Kuijper, Sjoukje; Kolk, Arend H J; Janssen, Hans-Gerd

    2016-03-25

    Tuberculosis is one of the world's most emerging public health problems, particularly in developing countries. Chromatography based methods have been used to tackle this epidemic by focusing on biomarker detection. Unfortunately, interferences from lipids in the sputum matrix, particularly cholesterol, adversely affect the identification and detection of the marker compounds. The present contribution describes the serial combination of normal phase liquid chromatography (NPLC) with thermally assisted hydrolysis and methylation followed by gas chromatography-mass spectrometry (THM-GC-MS) to overcome the difficulties of biomarker evaluation. The in-series combination consists of an LC analysis where fractions are collected and then transferred to the THM-GC-MS system. This was either done with comprehensive coupling, transferring all the fractions, or with hyphenated interfacing, i.e. off-line multi heart-cutting, transferring only selected fractions. Owing to the high sensitivity and selectivity of LC as a sample pre-treatment method, and to the high specificity of the MS as a detector, this analytical approach, NPLC × THM-GC-MS, is extremely sensitive. The results obtained indicate that this analytical set-up is able to detect down to 1 × 10(3) mycobacteria/mL of Mycobacterium tuberculosis strain 124, spiked in blank sputum samples. It is a powerful analytical tool and also has great potential for full automation. If further studies demonstrate its usefulness when applied blind in real sputum specimens, this technique could compete with the current smear microscopy in the early diagnosis of tuberculosis. Copyright © 2015 Elsevier B.V. All rights reserved.

  13. Thermal modulation for multidimensional liquid chromatography separations using low-thermal-mass liquid chromatography (LC).

    PubMed

    Verstraeten, Matthias; Pursch, Matthias; Eckerle, Patric; Luong, Jim; Desmet, Gert

    2011-09-15

    We report on a proof-of-principle experiment with a novel thermal modulation device with potential use in two-dimensional liquid chromatography (LC × LC) systems. It is based on the thermal desorption concept used in two-dimensional gas chromatography (GC × GC) systems. Preconcentration of neutral analytes eluting from the first dimension column is performed in a capillary "trap" column packed with highly retentive porous graphitic carbon particles, placed in an aluminum low-thermal-mass LC heating sleeve. Remobilization of the trapped analytes is achieved by rapidly heating the trap column, by applying temperature ramps up to +1200 °C/min. Compared to the nonmodulated signal, the presented thermal modulator yielded narrow peaks, and a concentration enhancement factor up to 18 was achieved. With a thermally modulated LC separation of an epoxy resin, it is shown that when the thermal modulation is applied periodically, the trapped and concentrated molecules can be released periodically and that the modulating interface can both serve as a preconcentration device and as an injector for the second dimension column of an LC × LC setup. Because of the thermal modulation, a high-molecular-weight epoxy resin could be adequately separated and the different fractions were identified with a GPC analysis, as well as an offline second dimension LC analysis.

  14. Predicting the behaviour of polydisperse polymers in liquid chromatography under isocratic and gradient conditions.

    PubMed

    Schoenmakers, Peter; Fitzpatrick, Fiona; Grothey, Ricarda

    2002-08-02

    In this paper we describe how the existing theories to describe retention and peak width in isocratic and gradient-elution liquid chromatography can be expanded to describe the retention behaviour of natural and synthetic repetitive polymers, which feature distributions of molecules with different masses (and often different structures) rather than unambiguous molecular formulas. For polydisperse samples, it is vital that the model accommodates (isocratic) elution of sample components before the onset of a gradient, elution during the gradient, and elution after the completion of the gradient. The expanded models can readily be implemented in standard spreadsheet software, such as Excel. We have created such spreadsheets based on the conventional model for retention in reversed-phase liquid chromatography (RPLC) and on two different models for retention in normal-phase liquid chromatography. The implementation allows an easy visualization of the theoretical concept. Up to three different polymeric series can be entered, with a total of up to 100 peaks being computed and displayed in isocratic or gradient-elution chromatograms. Also visualized are "retention models" (diagrams of isocratic retention vs. composition) and "calibration curves" (retention or elution composition vs. molecular mass or degree of polymerization). The coefficients in the isocratic retention model may be correlated, as has often been observed in RPLC. It is shown that under certain conditions such a correlation corresponds to the existence of so-called critical (isocratic) conditions, at which all the members of a given polymeric series (same composition and end groups, different number of repeat units) show co-elution.

  15. Micro-polarimeter for high performance liquid chromatography

    DOEpatents

    Yeung, Edward E.; Steenhoek, Larry E.; Woodruff, Steven D.; Kuo, Jeng-Chung

    1985-01-01

    A micro-polarimeter interfaced with a system for high performance liquid chromatography, for quantitatively analyzing micro and trace amounts of optically active organic molecules, particularly carbohydrates. A flow cell with a narrow bore is connected to a high performance liquid chromatography system. Thin, low birefringence cell windows cover opposite ends of the bore. A focused and polarized laser beam is directed along the longitudinal axis of the bore as an eluent containing the organic molecules is pumped through the cell. The beam is modulated by air gap Faraday rotators for phase sensitive detection to enhance the signal to noise ratio. An analyzer records the beams's direction of polarization after it passes through the cell. Calibration of the liquid chromatography system allows determination of the quantity of organic molecules present from a determination of the degree to which the polarized beam is rotated when it passes through the eluent.

  16. Modified normal-phase ion-pair chromatographic methods for the facile separation and purification of imidazolium-based ionic compounds

    SciTech Connect

    Urban, ND; Schenkel, MR; Robertson, LA; Noble, RD; Gin, DL

    2012-07-04

    lmidazolium- and oligo(imidazolium)-based ionic organic compounds are important in the design of room-temperature ionic liquid materials; however, the chromatographic analysis and separation of such compounds are often difficult. A convenient and inexpensive method for effective thin-layer chromatography (TLC) analysis and column chromatography separation of imidazolium-based ionic compounds is presented. Normal-phase ion-pair TLC is used to effectively analyze homologous mixtures of these ionic compounds. Subsequent separation of the mixtures is performed using ion-pair flash chromatography on normal-phase silica gel, yielding high levels of recovery. This method also results in a complete exchange of the counter anion on the imidazolium compounds to the anion of the ion-pair reagent. (C) 2012 Elsevier Ltd. All rights reserved.

  17. Quinolinium ionic liquid-modified silica as a novel stationary phase for high-performance liquid chromatography.

    PubMed

    Sun, Min; Feng, Juanjuan; Luo, Chuannan; Liu, Xia; Jiang, Shengxiang

    2014-04-01

    A novel stationary phase based on quinolinium ionic liquid-modified silica was prepared and evaluated for high-performance liquid chromatography. The stationary phase was investigated via normal-phase (NP), reversed-phase (RP), and anion-exchange (AE) chromatographic modes, respectively. Polycyclic aromatic hydrocarbons, phthalates, parabens, phenols, anilines, and inorganic anions were used as model analytes in chromatographic separation. Using the newly established column, organic compounds were separated successfully by both NP and RP modes, and inorganic anions were also separated completely by AE mode. The obtained results indicated that the stationary phase could be applied in different chromatographic modes, with multiple-interaction mechanism including van der Waals forces (dipole-dipole, dipole-induced dipole interactions), hydrophobic, π-π stacking, electrostatic forces, hydrogen bonding, anion-exchange interactions, and so on. The column packed with the stationary phase was applied to analyze phthalates and parabens in hexane extracts of plastics. Tap water and bottled water were also analyzed by the column, and nitrate was detected as 20.1 and 13.8 mg L(-1), respectively. The results illustrated that the stationary phase was potential in practical applications.

  18. Liquid Chromatography Applied to Space System

    NASA Astrophysics Data System (ADS)

    Poinot, Pauline; Chazalnoel, Pascale; Geffroy, Claude; Sternberg, Robert; Carbonnier, Benjamin

    Searching for signs of past or present life in our Solar System is a real challenge that stirs up the curiosity of scientists. Until now, in situ instrumentation was designed to detect and determine concentrations of a wide number of organic biomarkers. The relevant method which was and still is employed in missions dedicated to the quest of life (from Viking to ExoMars) corresponds to the pyrolysis-GC-MS. Along the missions, this approach has been significantly improved in terms of extraction efficiency and detection with the use of chemical derivative agents (e.g. MTBSTFA, DMF-DMA, TMAH…), and in terms of analysis sensitivity and resolution with the development of in situ high-resolution mass spectrometer (e.g. TOF-MS). Thanks to such an approach, organic compounds such as amino acids, sugars, tholins or polycyclic aromatic hydrocarbons (PAHs) were expected to be found. However, while there’s a consensus that the GC-MS of Viking, Huygens, MSL and MOMA space missions worked the way they had been designed to, pyrolysis is much more in debate (Glavin et al. 2001; Navarro-González et al. 2006). Indeed, (1) it is thought to remove low levels of organics, (2) water and CO2 could interfere with the detection of likely organic pyrolysis products, and (3) only low to mid-molecular weight organic molecules can be detected by this technique. As a result, researchers are now focusing on other in situ techniques which are no longer based on the volatility of the organic matter, but on the liquid phase extraction and analysis. In this line, micro-fluidic systems involving sandwich and/or competitive immunoassays (e.g. LMC, SOLID; Parro et al. 2005; Sims et al. 2012), micro-chip capillary electrophoreses (e.g. MOA; Bada et al. 2008), or nanopore-based analysis (e.g. BOLD; Schulze-Makuch et al. 2012) have been conceived for in situ analysis. Thanks to such approaches, molecular biological polymers (polysaccharides, polypeptides, polynucleotides, phospholipids, glycolipids

  19. Monitoring stevioside in soju by high-performance liquid chromatography and liquid chromatography/mass spectrometry.

    PubMed

    Ni, Fan; Ammann, Jeffrey; Mabud, Abdul

    2007-01-01

    A method using high-performance liquid chromatography (HPLC) with UV absorption detection was developed to monitor stevioside in soju, a distilled spirits product that is commercially available. The method uses a single-step dilution for sample preparation. It completely eliminates the time-consuming process of solid-phase extraction. A method using HPLC/mass spectrometry was optimized to confirm the identities of stevioside and other related impurities, including rebaudioside A, rebaudioside C, and dulcoside. The method was validated. The validation parameters included range (10.1-1007.3 ppm), precision, linearity, accuracy, robustness, system suitability, and intermediate precision. Stevioside standard solutions at 6 concentration levels were prepared for the validation work, including the tests for precision, linearity, and accuracy. The solutions were prepared in triplicate for each concentration. The relative standard deviation for the precision test was <3% for all 6 concentration levels. The correlation coefficient for the linearity within the concentration range was determined to be > 0.999. The average recovery ranged from 95.7 to 101.1% for the soju samples spiked with stevioside standard. The detection limit for stevioside was estimated at 75 ppb. The method was used to screen several soju samples; no detectable stevioside was found in the samples.

  20. Determination of Caffeine in Beverages by High Performance Liquid Chromatography.

    ERIC Educational Resources Information Center

    DiNunzio, James E.

    1985-01-01

    Describes the equipment, procedures, and results for the determination of caffeine in beverages by high performance liquid chromatography. The method is simple, fast, accurate, and, because sample preparation is minimal, it is well suited for use in a teaching laboratory. (JN)

  1. An Inexpensive Liquid Chromatography Apparatus for Undergraduate Teaching.

    ERIC Educational Resources Information Center

    McCamish, Malcolm; And Others

    1982-01-01

    Describes an inexpensive, low-pressure liquid chromatography pump, slurry filler, stainless steel columns, and injector system suitable for the undergraduate laboratory or routine analysis. Includes sectional diagram of the pump and construction diagram of the preparative columns. (Author/SK)

  2. Liquid Chromatography-Mass Spectrometry-based Quantitative Proteomics

    SciTech Connect

    Xie, Fang; Liu, Tao; Qian, Weijun; Petyuk, Vladislav A.; Smith, Richard D.

    2011-07-22

    Liquid chromatography-mass spectrometry (LC-MS)-based quantitative proteomics has become increasingly applied for a broad range of biological applications due to growing capabilities for broad proteome coverage and good accuracy in quantification. Herein, we review the current LC-MS-based quantification methods with respect to their advantages and limitations, and highlight their potential applications.

  3. Quantification of Tea Flavonoids by High Performance Liquid Chromatography

    ERIC Educational Resources Information Center

    Freeman, Jessica D.; Niemeyer, Emily D.

    2008-01-01

    We have developed a laboratory experiment that uses high performance liquid chromatography (HPLC) to quantify flavonoid levels in a variety of commercial teas. Specifically, this experiment analyzes a group of flavonoids known as catechins, plant-derived polyphenolic compounds commonly found in many foods and beverages, including green and black…

  4. High-Performance Liquid Chromatography-Mass Spectrometry.

    ERIC Educational Resources Information Center

    Vestal, Marvin L.

    1984-01-01

    Reviews techniques for online coupling of high-performance liquid chromatography with mass spectrometry, emphasizing those suitable for application to nonvolatile samples. Also summarizes the present status, strengths, and weaknesses of various techniques and discusses potential applications of recently developed techniques for combined liquid…

  5. Mallow carotenoids determined by high-performance liquid chromatography

    USDA-ARS?s Scientific Manuscript database

    Mallow (corchorus olitorius) is a green vegetable, which is widely consumed either fresh or dry by Middle East population. This study was carried out to determine the contents of major carotenoids quantitatively in mallow, by using a High Performance Liquid Chromatography (HPLC) equipped with a Bis...

  6. Quantification of Tea Flavonoids by High Performance Liquid Chromatography

    ERIC Educational Resources Information Center

    Freeman, Jessica D.; Niemeyer, Emily D.

    2008-01-01

    We have developed a laboratory experiment that uses high performance liquid chromatography (HPLC) to quantify flavonoid levels in a variety of commercial teas. Specifically, this experiment analyzes a group of flavonoids known as catechins, plant-derived polyphenolic compounds commonly found in many foods and beverages, including green and black…

  7. LCEC: The Combination of Liquid Chromatography and Electrochemistry.

    ERIC Educational Resources Information Center

    Kissinger, Peter T.

    1983-01-01

    Use of combined liquid chromatography and finite-current electrochemistry (LCEC) procedures are discussed. Also discusses the relationship between electroactivity and molecular structure, selectivity in LCEC, and LCEC applications. Because of its selectivity and low detection limits, the procedures are most often applied in biomedical and…

  8. Quantitative determination of phenol by high-pressure liquid chromatography.

    PubMed

    Musto, J D; Sane, J N; Warner, V D

    1977-08-01

    High-pressure liquid chromatography was used with a 5-micrometer silica gel column to quantitate the phenol in phenolated calamine lotion USP and a commercial antiseptic solution. This method requires less than 10 min/assay, and other compounds present in the products analyzed did not interfere.

  9. An Inexpensive Liquid Chromatography Apparatus for Undergraduate Teaching.

    ERIC Educational Resources Information Center

    McCamish, Malcolm; And Others

    1982-01-01

    Describes an inexpensive, low-pressure liquid chromatography pump, slurry filler, stainless steel columns, and injector system suitable for the undergraduate laboratory or routine analysis. Includes sectional diagram of the pump and construction diagram of the preparative columns. (Author/SK)

  10. Multichannel Detection in High-Performance Liquid Chromatography.

    ERIC Educational Resources Information Center

    Miller, James C.; And Others

    1982-01-01

    A linear photodiode array is used as the photodetector element in a new ultraviolet-visible detection system for high-performance liquid chromatography (HPLC). Using a computer network, the system processes eight different chromatographic signals simultaneously in real-time and acquires spectra manually/automatically. Applications in fast HPLC…

  11. Multichannel Detection in High-Performance Liquid Chromatography.

    ERIC Educational Resources Information Center

    Miller, James C.; And Others

    1982-01-01

    A linear photodiode array is used as the photodetector element in a new ultraviolet-visible detection system for high-performance liquid chromatography (HPLC). Using a computer network, the system processes eight different chromatographic signals simultaneously in real-time and acquires spectra manually/automatically. Applications in fast HPLC…

  12. Determination of Caffeine in Beverages by High Performance Liquid Chromatography.

    ERIC Educational Resources Information Center

    DiNunzio, James E.

    1985-01-01

    Describes the equipment, procedures, and results for the determination of caffeine in beverages by high performance liquid chromatography. The method is simple, fast, accurate, and, because sample preparation is minimal, it is well suited for use in a teaching laboratory. (JN)

  13. Assay of aspartylglycosylaminase by high-performance liquid chromatography.

    PubMed

    Kaartinen, V; Mononen, I

    1990-10-01

    An aspartylglycosylaminase assay based on high-performance liquid chromatographic analysis of the substrate aspartylglucosamine and product aspartate is described. Aspartylglucosamine and aspartate are derivatized with phenylisothiocyanate and resolved by reverse-phase chromatography. The detection limit for the compounds is 2 pmol. The method can be used for analysis of aspartylglycosylaminase activity in crude cell extracts and tissue samples.

  14. Purification of porcine proinsulin by high-performance liquid chromatography.

    PubMed

    Parman, A U; Rideout, J M

    1983-02-04

    A procedure has been developed for purification of porcine proinsulin by high-performance liquid chromatography from a preparation obtained as a side product during the Sephadex G-50 gel filtration of an impure porcine insulin preparation. Reversed-phase chromatography was carried out on octadecylsilica as the stationary phase with graded mixtures of acetonitrile or methanol-acetonitrile and phosphate buffer pH 2.4 as the mobile phase. The crude preparation separated into five different groups of proteins, the proinsulin-containing peak being identified by the co-eluting internal proinsulin marker. After purification by conventional procedures (separation, pooling, freeze drying, desalting, reprecipitation and drying) this peak fraction was rechromatographed by high-performance liquid chromatography (for final purification) to give a single peak protein which had identical electrophoretic mobility to that of commercial porcine proinsulin, and which converted to a protein with electrophoretic mobility similar to that of porcine insulin.

  15. Drug analysis by direct liquid introduction micro liquid chromatography mass spectrometry.

    PubMed

    Henion, J D; Maylin, G A

    1980-03-01

    The analytical capabilities of a micro high performance liquid chromatograph interfaced to an unchanged quadrupole mass spectrometer are presented. Continuous monitoring of the total micro liquid chromatographic effluent allows full scan chemical ionization mass spectra of from one to five nanograms of drugs and their metabolites to be recorded. The interface is a simple, inexpensive device which can be assembled from commercially available components. An eight microliter per minute flow rate of the micro liquid chromatographic eluant allows separation and identification of biologically important substances not amenable to gas chromatography mass spectrometry techniques. The sensitivity of micro liquid chromatography mass spectrometry performed as described is comparable with gas chromatography mass spectrometry and is achieved by introducing the total micro liquid chromatographic effluent into the chemical ionization ion source of the mass spectrometer. Selected ion monitoring provides 20 pg detection limits of phenothiazine tranquilizers injected on column.

  16. Analysis of Free Fatty Acids on the Fingertips by High Performance Liquid Chromatography.

    DTIC Science & Technology

    1978-12-20

    This investigation studied the efficiency of high performance liquid chromatography in the determination of free fatty acids present on the...utilized to eliminate the microbial contamination. The high performance liquid chromatography provided excellent separation of skin fatty acids for

  17. Determination of cholecalciferol (vitamin D3) in selected foods by liquid chromatography: NMKL collaborative study.

    PubMed

    Staffas, Anders; Nyman, Arne

    2003-01-01

    Results are presented from an NMKL (Nordic Committee on Food Analysis) collaborative study of a method for the determination of cholecalciferol (vitamin D3) in foods. The method is based on the addition of an internal standard (vitamin D2), followed by saponification and extraction with n-heptane. The fraction that contains vitamin D2/D3 is separated by preparative normal-phase liquid chromatography (LC), and the analytes are determined by reversed-phase LC with UV detection at 265 nm. The method was tested by 8 participating laboratories. In this study 6 different matrixes were analyzed for cholecalciferol content: milk, liquid infant formula (gruel), cooking oil, margarine, infant formula, and fish oil. The contents varied from 0.4 to 12 microg/100 g. Three matrixes (milk, gruel, and margarine) were fortified with vitamin D3. In the other matrixes, vitamin D3 was added at 3 different levels at the Swedish National Food Administration. The milk was analyzed as a blind duplicate, whereas the other matrixes were analyzed as split-level pairs. The recoveries from the samples with vitamin D3 added varied from 93 to 102%. The repeatability relative standard deviation (RSDr) values for accepted results varied between 2.2% (fish oil) and 7.4% (cooking oil), whereas the reproducibility relative standard deviation (RSD(R)) values varied between 6.8% (margarine) and 24% (cooking oil).

  18. Sample injector for high pressure liquid chromatography

    DOEpatents

    Paul, Phillip H.; Arnold, Don W.; Neyer, David W.

    2001-01-01

    Apparatus and method for driving a sample, having a well-defined volume, under pressure into a chromatography column. A conventional high pressure sampling valve is replaced by a sample injector composed of a pair of injector components connected in series to a common junction. The injector components are containers of porous dielectric material constructed so as to provide for electroosmotic flow of a sample into the junction. At an appropriate time, a pressure pulse from a high pressure source, that can be an electrokinetic pump, connected to the common junction, drives a portion of the sample, whose size is determined by the dead volume of the common junction, into the chromatographic column for subsequent separation and analysis. The apparatus can be fabricated on a substrate for microanalytical applications.

  19. 21 CFR 862.2250 - Gas liquid chromatography system for clinical use.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Gas liquid chromatography system for clinical use... Instruments § 862.2250 Gas liquid chromatography system for clinical use. (a) Identification. A gas liquid chromatography system for clinical use is a device intended to separate one or more drugs or compounds from a...

  20. 21 CFR 862.2260 - High pressure liquid chromatography system for clinical use.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false High pressure liquid chromatography system for... Clinical Laboratory Instruments § 862.2260 High pressure liquid chromatography system for clinical use. (a) Identification. A high pressure liquid chromatography system for clinical use is a device intended to separate...

  1. 21 CFR 862.2260 - High pressure liquid chromatography system for clinical use.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false High pressure liquid chromatography system for... Clinical Laboratory Instruments § 862.2260 High pressure liquid chromatography system for clinical use. (a) Identification. A high pressure liquid chromatography system for clinical use is a device intended to separate...

  2. 21 CFR 862.2250 - Gas liquid chromatography system for clinical use.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Gas liquid chromatography system for clinical use... Instruments § 862.2250 Gas liquid chromatography system for clinical use. (a) Identification. A gas liquid chromatography system for clinical use is a device intended to separate one or more drugs or compounds from a...

  3. 21 CFR 862.2260 - High pressure liquid chromatography system for clinical use.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false High pressure liquid chromatography system for... Clinical Laboratory Instruments § 862.2260 High pressure liquid chromatography system for clinical use. (a) Identification. A high pressure liquid chromatography system for clinical use is a device intended to separate...

  4. Determination of Stabiliser Contents in Advanced Gun Propellants by Reverse Phase High Performance Liquid Chromatography

    DTIC Science & Technology

    1994-03-01

    HIGH PERFORMANCE LIQUID CHROMATOGRAPHY N"m A.R. TURNER AND A. WHITE...TO biEPROOU.; AND SELL THIS REPORT Determination of Stabiliser Contents in Advanced Gun Propellants by Reverse Phase High Performance Liquid Chromatography A.R...8217/......... .. Availability Cooes Dist Avaiardlo A-i Determination of Stabiliser Contents in Advanced Gun Propellants by Reverse Phase High Performance Liquid Chromatography

  5. Optimizing heterosurface adsorbent synthesis for liquid chromatography

    NASA Astrophysics Data System (ADS)

    Bogoslovskii, S. Yu.; Serdan, A. A.

    2016-03-01

    The structural and geometric parameters of a silica matrix (SM) for the synthesis of heterosurface adsorbents (HAs) are optimized. Modification is performed by shielding the external surfaces of alkyl-modified silica (AS) using human serum albumin and its subsequent crosslinking. The structural and geometric characteristics of the SM, AS, and HA are measured via low-temperature nitrogen adsorption. It is found that the structural characteristics of AS pores with diameters D < 6 nm do not change during HA synthesis, while the volume of pores with diameters of 6 nm < D < 9 nm shrinks slightly due to the adsorption of albumin in the pore orifices. It is established that the volume of pores with diameters D > 9 nm reduces significantly due to adsorption of albumin. It is concluded that silica gel with a maximum pore size distribution close to 5 nm and a minimal proportion of pores with D > 9 nm is optimal for HA synthesis; this allows us to achieve the greatest similarity between the chromatographic retention parameters for HA and AS. The suitability of the synthesized adsorbents for analyzing drugs in biological fluids through direct sample injection is confirmed by chromatography. It was found that the percentage of the protein fraction detected at the outlet of the chromatographic column is 98%.

  6. Quantification of sesquiterpene lactones in Parthenium hyterophorous by normal-phase HPLC.

    PubMed

    Chib, Renu; Shah, Bhahwal Ali; Andotra, Samar Singh; Bharadwaj, Vikram; Gupta, Rajinder Kumar; Taneja, Subhash Chandra; Khajuria, Ravi Kant

    2013-01-01

    This paper describes the development of a normal-phase liquid chromatography ultraviolet-diode array detection method for the simultaneous quantification of parthenin and coronopilin in the leaves and flowers of Parthenium hysterophorous. The compounds were analyzed on a Merck Si60 silica column (5 µm, 250 × 4 mm) using an isocratic 15:85 mixture of isopropyl alcohol and hexane. The calibration curves resulting from the reference compounds in the concentration range of 200-2,000 ng exhibited acceptable linearity (r > 0.999). The method was developed to study the levels of parthenin and coronopilin in the leaves and flowers of P. hysterophorous collected during different seasons, and the method was validated by analyzing the spiked samples.

  7. Amino acids as chiral selectors in enantioresolution by liquid chromatography.

    PubMed

    Bhushan, Ravi; Dixit, Shuchi

    2012-08-01

    Amino acids are unique in terms of their structural features and multidimensional uses. With their simple structures and the ready availability of both enantiomers, amino acids not only serve as a chiral pool for synthesis but also provide an inexpensive pool for resolution studies. There has been no attempt to review the application of amino acids as chiral selectors for chromatographic enantioresolution of pharmaceuticals and other compounds. The present paper deals with application of l-amino acids and complexes of l-amino acids with a metal ion, particularly Cu(II), as an impregnating reagent in thin-layer chromatography or as a chiral ligand exchange reagent or a chiral mobile phase additive in both thin-layer chromatography and high-performance liquid chromatography. Enantiomeric resolution of β-blockers, nonsteroidal anti-inflammatories, amino acids (and their derivatives) and certain other compounds is discussed.

  8. Standard Flow Liquid Chromatography for Shotgun Proteomics in Bioenergy Research

    PubMed Central

    González Fernández-Niño, Susana M.; Smith-Moritz, A. Michelle; Chan, Leanne Jade G.; Adams, Paul D.; Heazlewood, Joshua L.; Petzold, Christopher J.

    2015-01-01

    Over the past 10 years, the bioenergy field has realized significant achievements that have encouraged many follow on efforts centered on biosynthetic production of fuel-like compounds. Key to the success of these efforts has been transformational developments in feedstock characterization and metabolic engineering of biofuel-producing microbes. Lagging far behind these advancements are analytical methods to characterize and quantify systems of interest to the bioenergy field. In particular, the utilization of proteomics, while valuable for identifying novel enzymes and diagnosing problems associated with biofuel-producing microbes, is limited by a lack of robustness and limited throughput. Nano-flow liquid chromatography coupled to high-mass accuracy, high-resolution mass spectrometers has become the dominant approach for the analysis of complex proteomic samples, yet such assays still require dedicated experts for data acquisition, analysis, and instrument upkeep. The recent adoption of standard flow chromatography (ca. 0.5 mL/min) for targeted proteomics has highlighted the robust nature and increased throughput of this approach for sample analysis. Consequently, we assessed the applicability of standard flow liquid chromatography for shotgun proteomics using samples from Escherichia coli and Arabidopsis thaliana, organisms commonly used as model systems for lignocellulosic biofuels research. Employing 120 min gradients with standard flow chromatography, we were able to routinely identify nearly 800 proteins from E. coli samples; while for samples from Arabidopsis, over 1,000 proteins could be reliably identified. An examination of identified peptides indicated that the method was suitable for reproducible applications in shotgun proteomics. Standard flow liquid chromatography for shotgun proteomics provides a robust approach for the analysis of complex samples. To the best of our knowledge, this study represents the first attempt to validate the standard

  9. Nano-liquid chromatography applied to enantiomers separation.

    PubMed

    Fanali, Salvatore

    2017-02-24

    This paper presents the state of the art concerning the separation of chiral compounds by means of nano-liquid chromatography (nano-LC). The enantiomers' separation and determination are a subject of fundamental importance in various application fields such as pharmaceutical industry, biomedicine, food, agrochemical etc. Nano-LC is a miniaturized chromatographic technique offering some advantages over conventional ones such as low consumption of mobile phase, sample volume and amount of chiral stationary phase, reduced costs etc. This is reported in the first part of the paper illustrating the features of the nano-LC. In addition, chiral resolution methods are briefly illustrated. Some chiral selectors, used in high-performance liquid chromatography have also been applied in nano-LC including cyclodextrins, glycopeptide antibiotics, modified polysaccharides etc. This is discussed in the second part of the review. Finally some examples of the applications available in literature are reported.

  10. Evaluation of surface excess isotherms in liquid chromatography.

    PubMed

    Vajda, Péter; Felinger, Attila; Guiochon, Georges

    2013-05-24

    Methods are proposed to calculate surface excess isotherms and to use them to derive adsorption isotherms in liquid chromatography. The consequences of these methods are discussed. The excess isotherm of isopropyl alcohol from its aqueous solutions on a C18 adsorbent was obtained using the minor disturbance method. The slope of the inflection tangent of the excess isotherm provides the position of the plane separating the adsorbed layer and the bulk phase, from which the adsorption isotherm was derived. At low concentrations of isopropyl alcohol, frontal analysis was used to derive the adsorption isotherm on the same adsorbent using an independent method. The isotherm was thus derived from both frontal analysis data and the minor disturbance method. The results obtained are compared. Our results show that the use of the same concentration unit for the calculation and the representation of the data is the only correct way to calculate the excess isotherms in practical applications of liquid chromatography.

  11. Analysis of selected ionic liquid cations by ion exchange chromatography and reversed-phase high performance liquid chromatography.

    PubMed

    Stepnowski, Piotr; Mrozik, Wojciech

    2005-02-01

    The chromatographic behavior of 8 ionic liquids - 7 homologues of 1-alkyl-3-methylimidazolium and 4-methyl-N-butylpyridinium - has been investigated with a strong cation exchange adsorbent. In particular, the dependence of the retention properties of these solutes on mobile phase composition, pH, and buffer concentration was evaluated with the aim of optimizing and improving the selectivity and retention of solute separation. While using the SCX stationary phase, several interactions occurred with varying strengths, depending on the mobile phase composition. Cation exchange, nonspecific hydrophobic interactions, and adsorption chromatography behavior were observed. Reversed phase chromatography occurred at low concentrations of acetonitrile, electrostatic and adsorption interactions at higher organic modifier concentrations. Elevated buffer concentrations lowered the retention factors without affecting the selectivity of ionic liquids. Obtained results were further compared to the chromatographic behaviour of ionic liquids in the reversed phase system. All analyzed ionic liquids follow reversed-phase behavior while being separated. Much lower selectivity in the range of highly hydrophilic compounds is obtained. This suggests preferred use of ion chromatography for separation and analysis of compounds below 4 carbon atoms in the alkyl side chain.

  12. Separation and determination of glycolipids from edible plant sources by high-performance liquid chromatography and evaporative light-scattering detection.

    PubMed

    Sugawara, T; Miyazawa, T

    1999-11-01

    Glycolipids from edible plant sources were accurately quantified by silica-based, normal-phase high-performance liquid chromatography using an evaporative light-scattering detector. Five major glycolipid classes (acylated steryl glucoside, steryl glucoside, ceramide monohexoside, monogalactosyldiacylglycerol, and digalactosyldiacylglycerol) were separated and determined with a binary gradient system consisting of chloroform and methanol/water (95:5, vol/vol) without any interference from other lipid classes and pigments. The described method was applied to 48 edible plants available in Japan including cereals, legumes, vegetables, and fruits. Examined plant species contained glycolipids in wide concentration ranges, such as 5-645 mg/100 g tissue.

  13. 21 CFR 862.2250 - Gas liquid chromatography system for clinical use.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Gas liquid chromatography system for clinical use... Instruments § 862.2250 Gas liquid chromatography system for clinical use. (a) Identification. A gas liquid... pressure. The device may include accessories such as columns, gases, column supports, and liquid...

  14. 21 CFR 862.2250 - Gas liquid chromatography system for clinical use.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Gas liquid chromatography system for clinical use... Instruments § 862.2250 Gas liquid chromatography system for clinical use. (a) Identification. A gas liquid... pressure. The device may include accessories such as columns, gases, column supports, and liquid...

  15. 21 CFR 862.2250 - Gas liquid chromatography system for clinical use.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Gas liquid chromatography system for clinical use... Instruments § 862.2250 Gas liquid chromatography system for clinical use. (a) Identification. A gas liquid... pressure. The device may include accessories such as columns, gases, column supports, and liquid...

  16. Determination of aminocresol isomers by high-speed liquid chromatography.

    PubMed

    Sakurai, H; Kito, M

    Aminocresol isomers (4-hydroxy-m-toluidine [II], 3-hydroxy-p-toluidine [II], 2-hydroxy-p-toluidine [III]) and p-aminophenol have been separated and determined by a high-speed liquid Chromatographie method. Since this method is applicable in aqueous media, it was used to investigate the suitability of a haemin-cysteine system as a model for the cytochrome P-450 mono-oxygenase system, by determination of the [I], [II], [III] and p-aminophenol formed.

  17. Determination of serotonin released from coffee wax by liquid chromatography.

    PubMed

    Kele, M; Ohmacht, R

    1996-04-12

    A simple hydrolysis and extraction method was developed for the release of serotonin (5-hydroxytryptamine) from a coffee wax sample obtained from decaffeination of coffee beans. The recoverable amount of serotonin was determined by reversed-phase high-performance liquid chromatography with gradient elution and UV detection, using the standard addition method. Different type of basic deactivated chromatographic columns were used for the separation.

  18. Analysis of chemically synthesized oleoylethanolamide by gas-liquid chromatography.

    PubMed

    Thabuis, Clémentine; Tissot-Favre, Delphine; Bezelgues, Jean-Baptiste; Martin, Jean-Charles; Cruz-Hernandez, Cristina; Dionisi, Fabiola; Destaillats, Frédéric

    2008-08-22

    Oleoylethanolamide (OEA) is known to potentially have beneficial biological effects on weight management by controlling food intake and activating lipid catabolism. In biological fluids, OEA and other endogenously biosynthesized fatty acid ethanolamides are usually analyzed by liquid chromatography-mass spectrometry (LC-MS). The present study provides analytical method to routinely assess the quality of OEA prepared for biological studies by gas-liquid chromatography (GLC). The preparation of OEA for biomedical studies can be performed by N-acylation of oleic acid/esters or using oleoyl chloride. In the present study, OEA was prepared by transamidation of triolein. The analysis of the synthesized OEA has been performed by gas-liquid chromatography of its trimethylsilyl ether (TMS) derivatives. Free OEA cannot be analyzed as such because dehydration of the ethanolamide moiety promptly happens in the GLC injection. This thermal degradation reaction gives rise to the formation of an oxazoline derivative. The TMS moiety prevents the reaction, and the structure of the formed derivative was assessed by mass spectrometry. We show here that OEA prepared for biological studies can be routinely analyzed by GLC after TMS derivative preparation.

  19. Fiber Bragg grating photoacoustic detector for liquid chromatography.

    PubMed

    Yang, Qingxin; Loock, Hans-Peter; Kozin, Igor; Pedersen, David

    2008-11-01

    Fiber Bragg Gratings (FBGs) are known to be sensitive acoustic transducers and have previously been used for the photoacoustic detection of small solid samples. Here, we demonstrate the use of an FBG as an on-line detector for liquid chromatography. The FBG was inserted into a silica capillary and the photoacoustic response from the effluent was generated by a 10 ns pulsed laser. The acoustic pulse was quantified by the FBG through a characteristic change in the reflection spectrum. Good repeatability and linear response were obtained over three orders of magnitude (R(2) > 0.99), and the limit of detection of Coumarin 440 was determined to be 5 microM. The technique was successfully coupled to high performance liquid chromatography and applied to on-line analysis of a three-compound solution. Photoacoustic detection in liquid chromatography using FBGs is a label-free method, which can be applied to the detection of any chromogenic compound irrespective of its fluorogenic properties. It is a simple, inexpensive, and inherently micron-sized technique, insensitive to electromagnetic interference.

  20. An Isocratic High-Performance Liquid Chromatography Assay for CYP7A1-Catalyzed Cholesterol 7α-Hydroxylation.

    PubMed

    Waxman, David J; Chang, Thomas K H

    2006-01-01

    A normal-phase, isocratic high-performance liquid chromatography assay is described for cholesterol 7α-hydroxylation catalyzed by CYP7A1, which corresponds to the first and rate-limiting step in the conversion of cholesterol into bile acids. This method is based on the conversion of the primary cytochrome P450 metabolite, 7α-hydroxycholesterol, into 7α-hydroxy-4-cholesten-3-one in a reaction catalyzed by exogenous cholesterol oxidase, followed by chromatographic separation with monitoring at 254 nm. This technique is applicable to enzymatic studies for determination of cholesterol 7α- hydroxylation activity catalyzed by cDNA-expressed CYP7A1 and animal or human liver microsomes.

  1. Carbon nanotubes-A resin for electrochemically modulated liquid chromatography.

    PubMed

    Brammen, Markus; Fraga-García, Paula; Berensmeier, Sonja

    2017-03-01

    Electrochemically modulated liquid chromatography is a special form of ion exchange chromatography in which the separation process is controlled by applying an electric potential to the stationary phase. This form of chromatography has so far only been applied in research studies. The present study shows that multiwalled carbon nanotubes are an effective resin material for an electrochemically modulated chromatography process. The experiments are carried out in a newly designed column that enables the packing of nanomaterials. We investigate the influence of the applied potential on the retention and elution of maleic acid, determine the dynamic binding capacity, and calculate the utilization degree of the electrical charge in the adsorption process. Moreover, the stability of the resin and the membrane over more than 200 working hours are presented. In addition to the stability, their sturdiness and inexpensive price are important qualities that make multiwalled carbon nanotubes interesting for application as the stationary phase in an electrochemically driven process. The investigated chromatography technique represents a promising separation process for future applications as a preparative step in biotechnology as well as other life science fields.

  2. Liquid to liquid extraction and liquid chromatography-tandem mass spectrometry determination of hainanmycin in feed.

    PubMed

    Wang, Ze Ping; Shen, Jian Zhong; Linhardt, Robert J; Jiang, Hui; Cheng, Lin Li

    2017-03-01

    Hainanmycin is a new veterinary polyether antibiotic and has few sensitive analytical method in present days. In this study, a liquid chromatography-tandem mass spectrometry (LC-MS/MS) relying on multiple reaction monitoring (MRM) detection was developed for analysis of hainanmycin in animal feed. Feed samples were extracted with ethyl acetate and purified by two steps of liquid-liquid extraction (LLE) to get rid of water solvable matrix and lipids one by one. The final simple was analyzed by LC-MS/MS. The LC mobile phase was composed of 0.1% aqueous formic acid and 0.1% formic acidified acetonitrile by gradient elution. Average recoveries ranged from 74.22% to 87.85%, as determined by spiking with 2.0 (LOQ) ∼2500μgkg(-1) of hainanmycin. The inter-day and intra-day coefficient of variation was 9.21% to 11.77% and 7.67% to 13.49%, respectively. The limit of detection (LOD) and the limit of quantitation (LOQ) were 0.36μgkg(-1) and 2.0μgkg(-1), respectively. Copyright © 2016. Published by Elsevier B.V.

  3. Thermal expansion pump for capillary high-performance liquid chromatography.

    PubMed

    Tao, Qian; Wu, Qian; Zhang, Xiangmin

    2010-02-01

    A thermal expansion pump (TEP) based on a principle of liquid thermal expansion for capillary high-performance liquid chromatography has been developed. The novel pump is capable of generating a continuous flow at high pressure for constant and stable delivery of binary solvents from nanoliters to microliters per minute without splitting. Theoretical equations for controlling fluidic output of this pump have been established and validated by a series of experiments. Factors affecting flow rate, such as density discrepancy, liquid compressibility, and mass loss in output, were taken into account. An assembly of the pump system employing two groups of thermal expansion pumps (TEPs) working in turns were fabricated, and a controlling strategy for the pump system to maintain a continuous delivery without pressure fluctuation even at switching points was also developed. Both isocratic and gradients of binary solvent delivery by the TEPs were performed. Reproducibility and standard deviation at different flow rates were determined. A capillary high-performance liquid chromatography (micro-HPLC) system consisting of the TEPs, an injection valve, a homemade packed capillary column (20 cm x 100 microm i.d. with 5 microm C18), and a laser-induced fluorescence detector was set up, and sample separations were carried out. Results of RSD = 4% for flow and RSD = 2% for retention times at 500 nL/min were achieved. Such a pump system has almost no moving parts except for the solvent switches. Its overall costs of manufacture and running are very low. It is proven that the TEPs system has great potential and competitive capabilities in capillary liquid chromatography.

  4. Capillary monolithic titania column for miniaturized liquid chromatography and extraction of organo-phosphorous compounds.

    PubMed

    Abi Jaoudé, Maguy; Randon, Jérôme

    2011-05-01

    A new sol-gel protocol was designed and optimized to produce titanium-dioxide-based columns within confined geometries such as monolithic capillary columns and porous-layer open-tubular columns. A surface pre-treatment of the capillary enabled an efficient anchorage of the monolith to the silica capillary wall during the synthesis. The monolith was further synthesized from a solution containing titanium n-propoxide, hydrochloric acid, N-methylformamide, water, and poly(ethylene oxide) as pore template. The chromatographic application of capillary titania-based columns was demonstrated with the separation of a set of phosphorylated nucleotides as probe molecules using aqueous normal-phase liquid chromatography conditions. Capillary titania monoliths offered a compromise between the high permeability and the important loading capacity needed to potentially achieve miniaturized sample preparations. The specificity of the miniaturized titania monolithic support is illustrated with the specific enrichment of 5'-adenosine mono-phosphate. The monolithic column offered a ten times higher loading capacity of 5'-adenosine mono-phosphate compared with that of the capillary titania porous-layer open-tubular geometry.

  5. New chiral stationary phases based on xanthone derivatives for liquid chromatography.

    PubMed

    Fernandes, Carla; Tiritan, Maria Elizabeth; Cravo, Sara; Phyo, Ye' Zaw; Kijjoa, Anake; Silva, Artur M S; Cass, Quezia B; Pinto, Madalena M M

    2017-08-01

    Six chiral derivatives of xanthones (CDXs) were covalently bonded to silica, yielding the corresponding xanthonic chiral stationary phases (XCSPs). The new XCSPs were packed into stainless-steel columns with 150 x 4.6 mm i.d. Moreover, the greening of the chromatographic analysis by reducing the internal diameter (150 x 2.1 mm i.d.) of the liquid chromatography (LC) columns was also investigated. The enantioselective capability of these phases was evaluated by LC using different chemical classes of chiral compounds, including several types of drugs. A library of CDXs was evaluated in order to explore the principle of reciprocity as well as the chiral self-recognition phenomenon. The separation of enantiomeric mixtures of CDXs was investigated under multimodal elution conditions. The XCSPs provided high specificity for the enantiomeric mixtures of CDXs evaluated mainly under normal-phase elution conditions. Furthermore, two XCSPs were prepared with both enantiomers of the same xanthonic selector in order to confirm the inversion order elution. © 2017 Wiley Periodicals, Inc.

  6. Simultaneous determination of linear alkylbenzenesulfonates, alkylphenol polyethoxylates, and nonylphenol by high-performance liquid chromatography

    SciTech Connect

    Marcomini, A.; Giger, W.

    1987-07-01

    Linear 4-alkylbenzenesulfonates (LAS), 4-alkylphenol polyethoxylates (APEO) (i.e., 4-octylphenol polyethoxylates (OPEO) and 4-nonylphenol polyethoxylates (NPEO), and 4-nonylphenol (NP) are simultaneously determined by reversed-phase high-performance liquid chromatography (HPLC) using octylsilica columns and water/acetonitrile gradient elution. LAS are separated according to their alkyl chain lengths and coelution of NPEO and NP is observed in contrast to the separation of OPEO and NPEO. The determination of oligomer distributions of APEO and quantitation of NP,NP1EO, and NP2EO require additional information attainable by normal-phase HPLC. Recoveries of 85-100% were found for LAS, APEO, and NP isolated by Soxhlet extraction under basic conditions from laundry detergent powders, sewage sludges, sludge-amended soils, and river sediments. Relative standard deviations for all analytes in the different matrices did not exceed 6%. Detection limits with UV fluorescence detection are 95 ng for NP, 80 ng for LAS, and 65 ng for NPEO with respect to injected amounts.

  7. Liquid chromatography-mass spectroscopy and liquid chromatography-ultraviolet/visible photodiode array analysis of selected colchicum species.

    PubMed

    Gharaibeh, Ahmad A; Al-Serini, Ala'a; Qasaymeh, Rana M; Ma'aya'h, Amani S; Tawaha, Khaled; El-Elimat, Tamam; Alali, Feras Q

    2012-01-01

    An in-house strategy to dereplicate colchicinoid alkaloids was recently developed by our team. It aimed at quickly identifying Colchicum constituents using LC-MS (liquid chromatography-mass spectroscopy) and LC-UV/Vis PDA (liquid chromatography-ultraviolet/ visible photodiode array) techniques. In this project, our goal was to validate the developed method through analysing the alkaloid-rich fractions of three Colchicum species that had been previously studied phytochemically using the traditional bioactivity-guided fractionation methodology. The analysed species were Colchicum tauri Siehe ex Stefanoff, Colchicum stevenii Kunth, and Colchicum tunicatum Feinbr., all belonging to the family Colchicaceae. In addition to identifying the compounds previously isolated and characterized by the traditional methodology, the new strategy succeeded in tentatively identifying a set of known compounds, but new to the species.

  8. Silica hydride based phases for small molecule separations using automated liquid chromatography-mass spectrometry method development.

    PubMed

    Appulage, Dananjaya K; Schug, Kevin A

    2017-07-21

    Silica hydride, or Type C silica, has been developed as an alternative chromatographic support material for liquid chromatography. There are various bonded phases available with this new support. For four such phases (Cholesterol, Bidentate C18, Diamond Hydride, and Diol), retention and selectivity behavior were investigated using liquid chromatography coupled with triple quadrupole mass spectrometry. A set of small molecules from several chemical classes of interest, and varying in their physicochemical properties, were chromatographed under both reversed-phase and aqueous normal phase modes. To screen the columns, column switching was performed using an automated platform controlled by associated software and an additional valve. A typical scouting gradient was implemented. The separation conditions were not further optimized since the goal was simply to evaluate the variable retention behavior of the phases and selectivity under generic conditions. Further, retention of the analytes were evaluated under isocratic conditions with varying percentages of organic phase to visualize the potential for dual retention modes on the same column for certain analytes. Four analytes (fentanyl, hydrocodone, hydromorphone, and matrine) showed dual mode retention behavior with all four phases. Especially, fentanyl exhibited dramatic "U-shaped" retention profiles on Cholesterol and Bidentate C18 phases. Overall, changes in the retention order between reversed phase and aqueous normal phases emphasized the potential for altered selectivity. Results showed that the Cholesterol phase provided the highest retention for most analytes compared to the other phases. The more polar Diol phase still provided good retention in reversed phase mode. Retention and selectivity were all highly reproducible. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. Comprehensive two-dimensional liquid chromatography: ion chromatography × reversed-phase liquid chromatography for separation of low-molar-mass organic acids.

    PubMed

    Brudin, Stella S; Shellie, Robert A; Haddad, Paul R; Schoenmakers, Peter J

    2010-10-22

    In the work presented here a novel approach to comprehensive two-dimensional liquid chromatography is evaluated. Ion chromatography is chosen for the first-dimension separation and reversed-phase liquid chromatography is chosen for the second-dimension separation mode. The coupling of these modes is made possible by neutralising the first-dimension effluent, containing KOH, prior to transfer to the second-dimension reversed-phase column. A test mixture of 24 low-molar-mass organic acids is used for optimisation of the system. Three food and beverage samples were analysed in order to evaluate the developed methodology, the resulting two-dimensional separation is near-orthogonal, the set-up is simple and all instrumental components are available commercially. The method proved to be robust and suitable for the analysis of wine, orange juice and yogurt.

  10. An evaluation of cis- and trans-retinol contents in juices using dispersive liquid-liquid microextraction coupled to liquid chromatography with fluorimetric detection.

    PubMed

    Viñas, Pilar; Bravo-Bravo, María; López-García, Ignacio; Hernández-Córdoba, Manuel

    2013-01-15

    This study describes a method for coupling dispersive liquid-liquid microextraction (DLLME) and normal-phase liquid chromatography (NP-LC) with fluorescence detection for vitamin A determination with the view to developing a new green sample preparation technique. Parameters affecting DLLME, including the nature and volume of both extractant and disperser solvents, salt addition and time and speed of the centrifugation step, were optimized. The sample was saponified according to European Standards to convert all forms of vitamin A to retinol. For microextraction, 8 mL water were placed in a glass tube with conical bottom and the saponified sample consisting of 2 mL of the methanolic extract containing 100 μL tetrachloroethane was rapidly injected by syringe, thereby forming a cloudy solution. Phase separation was performed by centrifugation, and a volume of 20 μL of the sedimented phase was analyzed by NP-LC. The enrichment factor, calculated as the ratio between the slopes of DLLME-LC and direct LC, was 50 ± 3. The matrix effect was evaluated for different juice samples, and it was concluded that sample quantification can be carried out by aqueous calibration when the standards are also submitted to saponification. The proposed method was applied for determining both cis- and trans-retinol isomers in commercial juices of different types. The intraday and interday precisions were lower than 6% in terms of relative standard deviation. The method was validated using two certified reference materials. Copyright © 2012 Elsevier B.V. All rights reserved.

  11. Electrically assisted capillary liquid chromatography using a silica monolithic column.

    PubMed

    Zhang, Bo; Bergström, Edmund T; Goodall, David M

    2010-04-09

    A silica monolithic capillary column was linked to an open capillary of the same internal diameter via a Teflon sleeve to form a duplex column to investigate the combination of chromatography and electrophoresis in the mode of electrically assisted capillary liquid chromatography (eCLC). Using a commercial CE instrument with an 8.5 cm long, 100 microm i.d. reversed phase silica monolithic section and a window 1.5 cm beyond the end of this in a 21.5 cm open section, a minimum plate height of 9 microm was obtained in capillary liquid chromatography (CLC) mode at a low driving pressure of 50 psi. In eCLC mode, high speed and high resolution separations of acidic and basic compounds were achieved with selectivity tuning based on the flexible combination of pressure (0-100 psi) and voltage. Taking advantage of the excellent permeability of silica monolithic columns, use of a step flow gradient enabled elution of compounds with different charge state. Copyright 2010 Elsevier B.V. All rights reserved.

  12. On-line combination of high performance liquid chromatography with comprehensive two-dimensional gas chromatography-triple quadrupole mass spectrometry: a proof of principle study.

    PubMed

    Zoccali, Mariosimone; Tranchida, Peter Quinto; Mondello, Luigi

    2015-02-03

    The present contribution is focused on the on-line combination of high performance liquid chromatography (HPLC), cryogenically modulated comprehensive two-dimensional gas chromatography (GC × GC), and triple quadrupole mass spectrometry (QqQ MS), generating a very powerful unified separation-science tool. The instrument can be used in seven different combinations ranging from one-dimensional HPLC with a photodiode array detector to on-line LC × GC × GC/QqQ MS. The main focus of the present research is directed to the LC-GC × GC/QqQ MS configuration, with its analytical potential shown in a proof-of-principle study involving a very complex sample, namely, coal tar. Specifically, a normal-phase LC process enabled the separation of three classes of coal tar compounds: (1) nonaromatic hydrocarbons; (2) unsaturated compounds (with and without S); (3) oxygenated constituents. The HPLC fractions were transferred to the GC × GC instrument via a syringe-based interface mounted on an autosampler. Each fraction was subjected to a specific programmed temperature vaporizer GC × GC/QqQ MS untargeted or targeted analysis. For example, the coal tar S-containing compounds were pinpointed through multiple-reaction-monitoring analysis, while full-scan information was attained for the oxygenated constituents.

  13. Characterisation of poly(vinyl alcohol) by liquid chromatography techniques

    SciTech Connect

    Meehan, E.; Warner, F.P.; Patterson, M.

    1995-12-01

    The molecular weight distribution of poly (vinyl alcohol) can be measured by aqueous size exclusion chromatography methods but the choice of eluent is critical in eliminating non size exclusion behavior. Aqueous size exclusion experiments have been carried out using a number of eluents including standard electrolytes and surfactants. The most favorable molecular size separation was obtained using 0.25% w/v sodium lauryl sulphate as eluent. Compositional distributions in copolymer systems can be assessed using high performance liquid chromatography employing a reverse phase separation mechanism. For poly (vinyl alcohol) gradient elution with water/tetrahydrofuran was found to produce a separation according to composition. Fast gradient elution (>10% tetrahydrofuran/minute) suggested abroad distribution of composition which was verified using a column packed with non-porous beads. Slower gradient elution (<1% tetrahydrofuran/minute) suggested that this was not due to a gradual composition change but rather discrete fractions of similarly hydrophobic material.

  14. [Preparation of flavonoid reference standards from Scutellariae Radix under the guidance of high performance liquid chromatography-mass spectrometry analysis].

    PubMed

    Guo, Henan; Yang, Xuedong; Liu, Jun; Zheng, Wenfeng

    2012-07-01

    Flavonoid reference standards were targeted-prepared from Scutellariae Radix under the guidance of high performance liquid chromatography-mass spectrometry (HPLC-MS) analysis. With HPLC-MS analysis of Scutellariae Radix, 19 flavonoid components were identified by analyzing and comparing their retention times, ultraviolet spectra, and mass spectrometry data with literature. The separation and purification protocols of all targeted flavonoid reference standards were optimally designed according to the results of HPLC-MS analysis and related literature. The ethanol extract of Scutellariae Radix was suspended in water and extracted with petroleum ether, ethyl acetate, and n-butanol successively. The ethyl acetate extract and n-butanol extract were separately subjected to primary separation by low pressure reverse phase preparative chromatography. Then the fractions containing targeted compounds were further purified by low pressure reverse and normal phases preparative chromatography. Finally, baicalin and wogonoside reference standards were obtained from n-butanol extract; baicaelin, wogonin, and oroxylin A reference standards were obtained from ethyl acetate extract. The structures of the 5 reference standards were identified by mass spectrometry (MS) and 1H nuclear magnetic resonance (1H NMR) spectroscopy. The HPLC analytical results showed that the purities of the 5 reference standards were all above 98%. It is demonstrated that the rapid targeted-preparation method under the guidance of the HPLC-MS analysis is applicable for the isolation and preparation of chemical components in traditional Chinese medicines.

  15. Retention studies of acrylamide for the design of a robust liquid chromatography-tandem mass spectrometry method for food analysis.

    PubMed

    Rosén, Johan; Nyman, Arne; Hellenäs, Karl-Erik

    2007-11-16

    A wide range of solid phases for SPE (solid-phase extraction) (n=14) and HPLC (n=9) were compared regarding the chromatographic retention of acrylamide. For SPE, a hydroxylated polystyrene-divinylbenzene copolymer phase (ENV+) gave the strongest retention. Twenty millilitre of water per gram solid phase could be passed with less than 5% loss of acrylamide from the column, thus enabling significant enrichment of food extracts. Other polymer phases gave varying degrees of retention, while silica bonded phases gave low retention. For HPLC, columns were evaluated both in reversed-phase and aqueous normal-phase (hydrophilic interaction chromatography) modes. The best retention was obtained with a phase comprising porous graphitic carbon (Hypercarb), giving a k-value of 4 with water as the mobile phase. Based on these investigations, a method for analysis of acrylamide in food using liquid chromatography-tandem mass spectrometry was designed to meet the demands of a collaborative validation trial. A comparative investigation of solid phases has not been published earlier. Thus, the paper should provide a base for new method developments regarding clean-up, enrichment and chromatography of acrylamide. In addition, the detailed standard operating procedure (SOP) method, as used in a collaborative validation trial, is provided as an electronic supplement (www.elsevier.com).

  16. MEMS Liquid and Gas Chromatography for Miniaturized Planetary In Situ Instruments

    NASA Astrophysics Data System (ADS)

    Kidd, R. D.; Bae, B.; Willis, P. A.; Noell, A. C.; Scianmarello, N.; Tai, Y.-C.

    2016-10-01

    Micro-Electro-Mechanical Systems (MEMS) technology to reduce the size, mass and power of the three classical chromatographic technologies: gas chromatography (GC), capillary electrophoresis (CE) and high performance liquid chromatography (HPLC).

  17. Enhanced-fluidity liquid chromatography using mixed-mode hydrophilic interaction liquid chromatography/strong cation-exchange retention mechanisms.

    PubMed

    Beres, Martin J; Olesik, Susan V

    2015-07-06

    The potential of enhanced-fluidity liquid chromatography, a subcritical chromatography technique, in mixed-mode hydrophilic interaction/strong cation-exchange separations is explored, using amino acids as analytes. The enhanced-fluidity liquid mobile phases were prepared by adding liquefied CO2 to methanol/water mixtures, which increases the diffusivity and decreases the viscosity of the mixture. The addition of CO2 to methanol/water mixtures resulted in increased retention of the more polar amino acids. The "optimized" chromatographic performance (achieving baseline resolution of all amino acids in the shortest amount of time) of these methanol/water/CO2 mixtures was compared to traditional acetonitrile/water and methanol/water liquid chromatography mobile phases. Methanol/water/CO2 mixtures offered higher efficiencies and resolution of the ten amino acids relative to the methanol/water mobile phase, and decreased the required isocratic separation time by a factor of two relative to the acetonitrile/water mobile phase. Large differences in selectivity were also observed between the enhanced-fluidity and traditional liquid mobile phases. A retention mechanism study was completed, that revealed the enhanced-fluidity mobile phase separation was governed by a mixed-mode retention mechanism of hydrophilic interaction/strong cation-exchange. On the other hand, separations with acetonitrile/water and methanol/water mobile phases were strongly governed by only one retention mechanism, either hydrophilic interaction or strong cation exchange, respectively. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Purification of pituitary autoantigen by column liquid chromatography and chromatofocusing

    PubMed Central

    Fischbach, Jakub; Ziemnicka, Katarzyna; Bączyk, Maciej; Baszko-Błaszyk, Daria; Wrotkowska, Elżbieta; Ruchała, Marek

    2014-01-01

    Introduction Pituitary autoantibodies can be determined both in patients with pituitary disease as well as patients with autoimmune endocrine diseases. The purpose of the study was to isolate and purify pituitary autoantigen using sera of patients and the microsomal fraction of the pituitary. Material and methods To isolate a pituitary autoantigen, patient sera were used, which showed a strong immune response to pituitary antigens. Pituitary microsomal fractions were prepared from pituitary tissue homogenates. In the study, sera of patients with pituitary disease, Addison and Graves’ disease were used. The initial stages were carried out by affinity chromatography on CN -Br sepharose column whereas purification was continued by column liquid chromatography on AcA54 Ultrogel. Chromatofocusing was performed by Polybuffer exchanger PBE 94. Results 125I-labeled pituitary antigens after isolation appeared in column chromatography in three peaks. The first peak contained 50-70 kDa proteins, the second peak – 17 to 22 kDa proteins and the third peak contains 125-iodides. Three fractions obtained from filtration on Ultrogel were separated in a polyacrylamide gel. In the first peak two bands 67 and 55 kDa appeared. The second peak contained low molecular weight substances, and the third peak contained 125I. The first peak from Ultrogel was isolated by chromatofocusing – the first peak with pH 5.9 and the second one with pH 4.9. Conclusions Isolation and purification of pituitary autoantigen with the use of column liquid chromatography and chromatofocusing resulted in obtainment of two antigenic proteins of specific gravity of 67 and 55 kDa. PMID:26155099

  19. Purification of pituitary autoantigen by column liquid chromatography and chromatofocusing.

    PubMed

    Gut, Paweł; Fischbach, Jakub; Ziemnicka, Katarzyna; Bączyk, Maciej; Baszko-Błaszyk, Daria; Wrotkowska, Elżbieta; Ruchała, Marek

    2014-01-01

    Pituitary autoantibodies can be determined both in patients with pituitary disease as well as patients with autoimmune endocrine diseases. The purpose of the study was to isolate and purify pituitary autoantigen using sera of patients and the microsomal fraction of the pituitary. To isolate a pituitary autoantigen, patient sera were used, which showed a strong immune response to pituitary antigens. Pituitary microsomal fractions were prepared from pituitary tissue homogenates. In the study, sera of patients with pituitary disease, Addison and Graves' disease were used. The initial stages were carried out by affinity chromatography on CN -Br sepharose column whereas purification was continued by column liquid chromatography on AcA54 Ultrogel. Chromatofocusing was performed by Polybuffer exchanger PBE 94. (125)I-labeled pituitary antigens after isolation appeared in column chromatography in three peaks. The first peak contained 50-70 kDa proteins, the second peak - 17 to 22 kDa proteins and the third peak contains (125)-iodides. Three fractions obtained from filtration on Ultrogel were separated in a polyacrylamide gel. In the first peak two bands 67 and 55 kDa appeared. The second peak contained low molecular weight substances, and the third peak contained (125)I. The first peak from Ultrogel was isolated by chromatofocusing - the first peak with pH 5.9 and the second one with pH 4.9. Isolation and purification of pituitary autoantigen with the use of column liquid chromatography and chromatofocusing resulted in obtainment of two antigenic proteins of specific gravity of 67 and 55 kDa.

  20. Analysis of radioactive mixed hazardous waste using derivatization gas chromatography/mass spectrometry, liquid chromatography, and liquid chromatography/mass spectrometry

    SciTech Connect

    Campbell, J.A.; Lerner, B.D.; Bean, R.M.; Grant, K.E.; Lucke, R.B.; Mong, G.M.; Clauss, S.A.

    1994-08-01

    Six samples of core segments from Tank 101-SY were analyzed for chelators, chelator fragments, and several carboxylic acids by derivatization gas chromatography/mass spectrometry. The major components detected were ethylenediaminetetraacetic acid, nitroso-iminodiacetic acid, nitrilotriacetic acid, citric acid, succinic acid, and ethylenediaminetriacetic acid. The chelator of highest concentration was ethylenediaminetetraacetic acid in all six samples analyzed. Liquid chromatography was used to quantitate low molecular weight acids including oxalic, formic, glycolic, and acetic acids, which are present in the waste as acid salts. From 23 to 61% of the total organic carbon in the samples analyzed was accounted for by these acids.

  1. Identification of mycobacteria by high-performance liquid chromatography.

    PubMed Central

    Butler, W R; Jost, K C; Kilburn, J O

    1991-01-01

    Mycolic acids extracted from saponified mycobacterial cells were examined as p-bromophenacyl esters by high-performance liquid chromatography (HPLC). Standard HPLC patterns were developed for species of Mycobacterium by examination of strains from culture collections and other well-characterized isolates. Relative retention times of peaks and peak height comparisons were used to develop a differentiation scheme that was 98% accurate for the species examined. A rapid, cost-effective HPLC method which offers an alternative approach to the identification of mycobacteria is described. PMID:1774251

  2. Gas-liquid chromatography in lunar organic analysis.

    NASA Technical Reports Server (NTRS)

    Gehrke, C. W.

    1972-01-01

    Gas-liquid chromatography (GLC) is a powerful and sensitive method for the separation and detection of organic compounds at nanogram levels. The primary requirement for successful analyses is that the compounds of interest must be volatile under the chromatographic conditions employed. Nonvolatile organic compounds must be converted to volatile derivatives prior to analysis. The derivatives of choice must be both amenable to chromatographic separation and be relatively stable. The condition of volatility necessitates the development of efficient derivatization reactions for important groups of compounds as amino acids, carbohydrates, nucleosides, etc. Trimethylsilylation and trifluoroacetylation represent specific areas of recent prominence. Some relevant practical aspects of GLC are discussed.

  3. Training software for high-performance liquid chromatography.

    PubMed

    Reijenga, J C

    2000-12-01

    A computer simulation program of reversed-phase high-performance liquid chromatography was developed for training purposes. Experimental retention values of 75 organic compounds on a reversed-phase column at four different percentages of organic modifiers were reduced to a two-parameter retention model with the modifier content as variable. Modifiers used were acetonitrile, methanol and tetrahydrofuran. Isocratic and programmed solvent composition were included together with the usual experimental parameters available in modern HPLC equipment, such as UV diode array and refractive index detection. Instrument specifications were made variable within wide ranges. Detailed dispersion data were made available as tabulated output.

  4. High-pressure liquid chromatography analysis of antibiotic susceptibility disks.

    PubMed Central

    Hagel, R B; Waysek, E H; Cort, W M

    1979-01-01

    The analysis of antibiotic susceptibility disks by high-pressure liquid chromatography (HPLC) was investigated. Methods are presented for the potency determination of mecillinam, ampicillin, carbenicillin, and cephalothin alone and in various combinations. Good agreement between HPLC and microbiological data is observed for potency determinations with recoveries of greater than 95%. Relative standard deviations of lower than 2% are recorded for each HPLC method. HPLC methods offer improved accuracy and greater precision when compared to the standard microbiological methods of analysis for susceptibility disks. PMID:507793

  5. Gas-liquid chromatography in lunar organic analysis.

    NASA Technical Reports Server (NTRS)

    Gehrke, C. W.

    1972-01-01

    Gas-liquid chromatography (GLC) is a powerful and sensitive method for the separation and detection of organic compounds at nanogram levels. The primary requirement for successful analyses is that the compounds of interest must be volatile under the chromatographic conditions employed. Nonvolatile organic compounds must be converted to volatile derivatives prior to analysis. The derivatives of choice must be both amenable to chromatographic separation and be relatively stable. The condition of volatility necessitates the development of efficient derivatization reactions for important groups of compounds as amino acids, carbohydrates, nucleosides, etc. Trimethylsilylation and trifluoroacetylation represent specific areas of recent prominence. Some relevant practical aspects of GLC are discussed.

  6. Size distributions of gold nanoclusters studied by liquid chromatography

    SciTech Connect

    WILCOXON,JESS P.; MARTIN,JAMES E.; PROVENCIO,PAULA P.

    2000-05-23

    The authors report high pressure liquid chromatography, (HPLC), and transmission electron microscopy, (TEM), studies of the size distributions of nanosize gold clusters dispersed in organic solvents. These metal clusters are synthesized in inverse micelles at room temperature and those investigated range in diameter from 1--10 nm. HPLC is sensitive enough to discern changes in hydrodynamic volume corresponding to only 2 carbon atoms of the passivating agent or metal core size changes of less than 4 {angstrom}. The authors have determined for the first time how the total cluster volume (metal core + passivating organic shell) changes with the size of the passivating agent.

  7. High-performance liquid chromatography enantioseparation of polyhalogenated 4,4'-bipyridines on polysaccharide-based chiral stationary phases under multimodal elution.

    PubMed

    Peluso, Paola; Mamane, Victor; Aubert, Emmanuel; Cossu, Sergio

    2014-09-01

    An investigation on the high-performance liquid chromatography enantioseparation of 12 polyhalogenated 4,4'-bipyridines on polysaccharide-based chiral stationary phases is described. The overall study was directed toward the generation of efficient separations in order to obtain pure atropisomers that will serve as ligands for building homochiral metal organic frameworks. Four coated columns--namely, Lux Cellulose-1, Lux Cellulose-2, Lux Cellulose-4, and Lux Amylose-2--and two immobilized columns--namely, Chiralpak IC and IA--were used under normal, polar organic, and reversed-phase elution modes. Moreover, Chiralcel OJ was considered under normal-phase and polar organic conditions. The effect of the chiral selector and mobile phase composition on the enantioseparation, the enantiomer elution order and the beneficial effect of nonstandard solvents were studied. The effect of water in the mobile phase on the enantioselectivity and retention was investigated and retention profiles typical of hydrophilic interaction liquid chromatography were observed. Interesting phenomena of solvent-induced enantiomer elution order reversal occurred under normal-phase mode. All the considered 4,4'-bipyridines were enantioseparated at the multimilligram level.

  8. Determination of a Jet Fuel Metal Deactivator by High Performance Liquid Chromatography

    DTIC Science & Technology

    1983-06-01

    column packings, and sensitive low dead volume detectors have catapulted HPLC into a rapidly maturing and valuable complement to gas chromatography ...be a gas or liquid; and a stationary phase, which may be either a liquid or a solid. The form of chromatography used in this research was partition...AFWAL-TR-82-21 28 1 1- 0 • DETERMINATION OF A JET FUEL METAL DEACTIVATOR BY HIGH PERFORMANCE LIQUID CHROMATOGRAPHY Paul C. Hayes, Jr. Fuels Branch

  9. Determination of Selected Colored Smokes on Glass Fiber Discs by High Performance Liquid Chromatography (HPLC)

    DTIC Science & Technology

    1991-05-01

    High Performance Liquid Chromatography (HPLC) 12. PERSONAL AUTHOR(S) F F_ n.ipl’prifl. Alan R...GROUP SUB-GROUP High Performance Liquid Chromatography (HPLC), Analytical IMethod, 1,4-diamino-2,3-dihydroanthraquinone, 2-(2 - _ quinolinyl)-1,3...weights, low vapor pressures and low thermal stability. High performance liquid chromatography (HPLC) appears to be the analytical method of choice

  10. Dynamic modification of separations using electrochemically modulated liquid chromatography

    SciTech Connect

    Deinhammer, R.S.; Ting, E.Y.; Porter, M.D. Iowa State Univ., Ames, IA )

    1995-01-15

    A new method for modifying and fine-tuning liquid chromatographic separations without manipulating the mobile phase composition is discussed. This method, termed electrochemically modulated liquid chromatography (EMLC), is based on the electrochemical manipulation of the capacity factors (k' values) of analytes both prior to and during their elution from a column packed with nonporous glassy carbon (GC) spheres. The GC spheres are connected as the working electrode in the three-electrode electrochemical cell. Improvements in the separation of a mixture of aromatic sulfonates (ASFs) obtained at open circuit are demonstrated by the application of several fixed voltages (E[sub app]) as well as voltage and charge ramps to the column. A comparison of these separations to those obtained at various mobile phase combinations suggests that EMLC offers some potentially useful differences in retention that are not easily gained through compositional alterations of the mobile phase. 53 refs., 6 figs., 3 tabs.

  11. Hydrazine Determination in Sludge Samples by High Performance Liquid Chromatography

    SciTech Connect

    G. Elias; G. A. Park

    2006-02-01

    A high-performance liquid chromatographic method using ultraviolet (UV) detection was developed to detect and quantify hydrazine in a variety of environmental matrices. The method was developed primarily for sludge samples, but it is also applicable to soil and water samples. The hydrazine in the matrices was derivatized to their hydrazones with benzaldehyde. The derivatized hydrazones were separated using high performance liquid chromatography (HPLC) with a reversed-phase C-18 column in an isocratic mode with methanol-water (95:5, v/v), and detected with UV detection at 313 nm. The detection limit (25 ml) for the new analytical method is 0.0067 mg ml-1of hydrazine. Hydrazine showed low recovery in soil samples because components in soil oxidized hydrazine. Sludge samples that contained relatively high soil content also showed lower recovery. The technique is relatively simple and cost-effective, and is applicable for hydrazine analysis in different environmental matrices.

  12. Analysis of beechwood creosote by gas chromatography-mass spectrometry and high-performance liquid chromatography.

    PubMed

    Ogata, N; Baba, T

    1989-12-01

    Compounds in beechwood creosote were analyzed by gas chromatography-mass spectrometry, and 22 major constituents were identified. Of these, 19 were phenolic compounds, i. e., guaiacol, phenol, two cresol isomers, four methylguaiacol (creosol) isomers, six xylenol isomers, two trimethylphenol isomers, 4-ethylguaiacol, 4-ethyl-5-methylguaiacol, and 4-propylguaiacol. The remaining three were hitherto unpredicted five-membered ring compounds, i. e., 3-methyl-2-hydroxy-2-cyclopenten-1-one, 3,5-dimethyl-2-hydroxy-2-cyclopenten-1-one, and 3-ethyl-2-hydroxy-2-cyclopenten-1-one. The relative quantities of these compounds were also compared with those obtained by high-resolution high-performance liquid chromatography. This report probably represents the first extensive analysis of beechwood creosote.

  13. Gas chromatography and high-performance liquid chromatography of natural steroids.

    PubMed

    Shimada, K; Mitamura, K; Higashi, T

    2001-11-23

    This review article underlines the importance of gas chromatography (GC), high-performance liquid chromatography (HPLC) and their hyphenated techniques using mass spectrometry (MS) for the determination of natural steroids, especially in human biological fluids. Steroids are divided into eight categories based on their structures and functions, and recent references using the above methodologies for the analysis of these steroids are cited. GC and GC-MS are commonly used for the determination of volatile steroids. Although HPLC is a widely used analytical method for the determination of steroids including the conjugated type in biological fluids, LC-MS is considered to be the most promising one for this purpose because of its sensitivity, specificity and versatility.

  14. Identification of polychlorinated styrene compounds in heron tissues by gas-liquid chromatography-mass spectrometry.

    PubMed

    Reichel, W L; Prouty, R M; Gay, M L

    1977-01-01

    Unknown compounds detected in Ardea herodias tissues are identified by gas-liquid chromatography-mass spectrometry as residues of octachlorostyrene. Heptachlorostyrene and hexachlorostyrene were tentatively identified.

  15. Identification of polychlorinated styrene compounds in heron tissues by gas-liquid chromatography-mass spectrometry

    USGS Publications Warehouse

    Reichel, W.L.; Prouty, R.M.; Gay, M.L.

    1977-01-01

    Unknown compounds detected in Ardea herodias tissues are identified by gas-liquid chromatography-mass spectrometry as residues of octachlorostyrene. Heptachlorostyrene and hexachlorostyrene were tentatively identified.

  16. [Determination of sildenafil and vardenafil in human plasma by high performance liquid chromatography coupled with liquid-liquid-liquid microextraction].

    PubMed

    Zhang, Zhaohui; Kang, Shaoying; Xu, Minjie; Ma, Ming; Chen, Bo; Yao, Shouzhuo

    2005-07-01

    High performance liquid chromatography coupled with liquid-liquid-liquid microextraction was developed for the simultaneous determination of sildenafil and vardenafil in human plasma. The effects of extraction solvent, the volume of organic solvent, dropsize of acceptor phase, stirring rate and extraction time on the enrichment factors of analytes were investigated. The optimized experimental conditions, 300 microL toluene as the organic phase, 2 microL 0.2 mol/L HCl as the acceptor phase, 600 r/min of the stirring rate, and 40 min of the extraction time, were gotten. Under these conditions, high enrichment factors were obtained. The linear range of studied analytes was from 5 microg/L to 1.0 mg/L. The relative standard deviation was lower than 5%. The limits of detection were 1 microg/L for sildenafil and 0.5 microg/L for vardenafil at signal-to-noise ratio of 3. The method with little solvent consumption may provide high analyte preconcentration and excellent sample clean-up, and it is a sensitive and suitable method for simultaneous determination of the above two substances in human plasma.

  17. General theory of peak compression in liquid chromatography.

    PubMed

    Gritti, Fabrice

    2016-02-12

    A new and general expression of the peak compression factor in liquid chromatography is derived. It applies to any type of gradients induced by non-uniform columns (stationary) or by temporal variations (dynamic) of the elution strength related to changes in solvent composition, temperature, or in any external field. The new equation is validated in two ideal cases for which the exact solutions are already known. From a practical viewpoint, it is used to predict the achievable degree of peak compression for curved retention models, retained solvent gradients, and for temperature-programmed liquid chromatography. The results reveal that: (1) curved retention models affect little the compression factor with respect to the best linear strength retention models, (2) gradient peaks can be indefinitely compressed with respect to isocratic peaks if the propagation speed of the gradient (solvent or temperature) becomes smaller than the chromatographic velocity, (3) limitations are inherent to the maximum intensity of the experimental intrinsic gradient steepness, and (4) dynamic temperature gradients can be advantageously combined to solvent gradients in order to improve peak capacities of microfluidic separation devices. Copyright © 2016 Elsevier B.V. All rights reserved.

  18. Liquid chromatography tandem mass spectrometry in the clinical laboratory.

    PubMed

    Adaway, Joanne E; Keevil, Brian G; Owen, Laura J

    2015-01-01

    Clinical laboratory medicine has seen the introduction and evolution of liquid chromatography tandem mass spectrometry in routine clinical laboratories over the last 10-15 years. There still exists a wide diversity of assays from very esoteric and highly specialist manual assays to more simplified kit-based assays. The technology is not static as manufacturers are continually making improvements. Mass spectrometry is now commonly used in several areas of diagnostics including therapeutic drug monitoring, toxicology, endocrinology, paediatrics and microbiology. Some of the most high throughput analyses or common analytes include vitamin D, immunosuppressant monitoring, androgen measurement and newborn screening. It also offers flexibility for the measurement of analytes in a variety of different matrices which would prove difficult with immunoassays. Unlike immunoassays or high-pressure liquid chromatography assays using ultraviolet or fluorescence detection, mass spectrometry offers better specificity and reduced interferences if attention is paid to potential isobaric compounds. Furthermore, multiplexing, which enables multiple analytes to be measured with the same volume of serum is advantageous, and the requirement for large sample volumes is decreasing as instrument sensitivity increases. There are many emerging applications in the literature. Using mass spectrometry to identify novel isoforms or modified peptides is possible as is quantification of proteins and peptides, with or without protein digests. Future developments by the manufacturers may also include mechanisms to improve the throughput of samples and strategies to decrease the level of skill required by the operators.

  19. Comparison of ultra high performance supercritical fluid chromatography, ultra high performance liquid chromatography, and gas chromatography for the separation of synthetic cathinones.

    PubMed

    Carnes, Stephanie; O'Brien, Stacey; Szewczak, Angelica; Tremeau-Cayel, Lauriane; Rowe, Walter F; McCord, Bruce; Lurie, Ira S

    2017-09-01

    A comparison of ultra high performance supercritical fluid chromatography, ultra high performance liquid chromatography, and gas chromatography for the separation of synthetic cathinones has been conducted. Nine different mixtures of bath salts were analyzed in this study. The three different chromatographic techniques were examined using a general set of controlled synthetic cathinones as well as a variety of other synthetic cathinones that exist as positional isomers. Overall 35 different synthetic cathinones were analyzed. A variety of column types and chromatographic modes were examined for developing each separation. For the ultra high performance supercritical fluid chromatography separations, analyses were performed using a series of Torus and Trefoil columns with either ammonium formate or ammonium hydroxide as additives, and methanol, ethanol or isopropanol organic solvents as modifiers. Ultra high performance liquid chromatographic separations were performed in both reversed phase and hydrophilic interaction chromatographic modes using SPP C18 and SPP HILIC columns. Gas chromatography separations were performed using an Elite-5MS capillary column. The orthogonality of ultra high performance supercritical fluid chromatography, ultra high performance liquid chromatography, and gas chromatography was examined using principal component analysis. For the best overall separation of synthetic cathinones, the use of ultra high performance supercritical fluid chromatography in combination with gas chromatography is recommended. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Dispersive liquid-liquid microextraction coupled to liquid chromatography for thiamine determination in foods.

    PubMed

    Viñas, Pilar; López-García, Ignacio; Bravo-Bravo, María; Briceño, Marisol; Hernández-Córdoba, Manuel

    2012-05-01

    A miniaturized dispersive liquid-liquid microextraction (DLLME) procedure coupled to liquid chromatography (LC) with fluorimetric detection was evaluated for the preconcentration and determination of thiamine (vitamin B(1)). Derivatization was carried out by chemical oxidation of thiamine with 5 × 10(-5) M ferricyanide at pH 13 to form fluorescent thiochrome. For DLLME, 0.5 mL of acetonitrile (dispersing solvent) containing 90 μL of tetrachloroethane (extraction solvent) was rapidly injected into 10 mL of sample solution containing the derivatized thiochrome and 24% (w/v) sodium chloride, thereby forming a cloudy solution. Phase separation was carried out by centrifugation, and a volume of 20 μL of the sedimented phase was submitted to LC. The mobile phase was a mixture of a 90% (v/v) 10 mM KH(2)PO(4) (pH 7) solution and 10% (v/v) acetonitrile at 1 mL min(-1). An amide-based stationary phase involving a ligand with amide groups and the endcapping of trimethylsilyl was used. Specificity, linearity, precision, recovery, and sensitivity were satisfactory. Calibration graph was carried out by the standard additions method and was linear between 1 and 10 ng mL(-1). The detection limit was 0.09 ng mL(-1). The selectivity of the method was judged from the absence of interfering peaks at the thiamine elution time for blank chromatograms of unspiked samples. A relative standard deviation of 3.2% was obtained for a standard solution containing thiamine at 5 ng mL(-1). The esters thiamine monophosphate and thiamine pyrophosphate can also be determined by submitting the sample to successive acid and enzymatic treatments. The method was applied to the determination of thiamine in different foods such as beer, brewer's yeast, honey, and baby foods including infant formulas, fermented milk, cereals, and purees. For the analysis of solid samples, a previous extraction step was applied based on an acid hydrolysis with trichloroacetic acid. The reliability of the procedure was

  1. A 96-well single-pot liquid-liquid extraction, hydrophilic interaction liquid chromatography-mass spectrometry method for the determination of muraglitazar in human plasma.

    PubMed

    Xue, Y-J; Liu, Jane; Unger, Steve

    2006-06-07

    A single-pot liquid-liquid extraction (LLE) with hydrophilic interaction liquid chromatography/tandem mass spectrometry (HILIC/MS/MS) method has been developed and validated for the determination of muraglitazar, a hydrophobic diabetes drug, in human plasma. To 0.050 ml of each plasma sample in a 96-well plate, the internal standard solution in acetonitrile and toluene were added to extract the compound of interest. The plate was vortexed, followed by centrifugation. The organic layer was then directly injected into an LC/MS/MS system. Chromatographic separation was achieved isocratically on a Thermohypersil_Keystone, Hypersil silica column (3 mmx50 mm, 3 microm). The mobile phase contained 85% of methyl t-butyl ether and 15% of 90/10 (v/v) acetonitrile/water with 0.3% trifluoroacetic acid. Post-column mobile phase of 50/50 (v/v) acetonitrile/water containing 0.1% formic acid was added. Detection was by positive ion electrospray tandem mass spectrometry on a Sciex API 4000. The standard curve, ranged from 1 to 1000 ng/ml, was fitted to a 1/x weighted quadratic regression model. This single-pot LLE approach effectively eliminated time-consuming organic layer transfer, dry-down, and sample reconstitution steps, which are essential for a conventional liquid-liquid extraction procedure. The modified mobile phase was more compatible with the direct injection of the commonly used extraction solvents in LLE. Furthermore, the modified mobile phase improved the retention of muraglitazar, a hydrophobic compound, on the normal phase silica column. The validation results demonstrated that this method was rugged and suitable for analyzing muraglitazar in human plasma. In comparison with a revised-phase LC/MS/MS method, this single-pot LLE, HILIC/MS/MS method improved the detection sensitivity by more than four-fold based upon the LLOQ signal to noise ratio. This approach may be applied to other hydrophobic compounds with proper modification of the mobile phase compositions.

  2. Enantioselective high performance liquid chromatography and supercritical fluid chromatography separation of spirocyclic terpenoid flavor compounds.

    PubMed

    Schaffrath, Mathias; Weidmann, Verena; Maison, Wolfgang

    2014-10-10

    Chiral spirocyclic terpenoids are abundant natural flavors with significant impact particularly on the food industry. Chromatographic methods for analytical and preparative separation of these compounds are therefore of high interest to natural product chemists in academia and industry. Gas chromatography on chiral stationary phases is currently the standard method for the separation of volatile terpenoids, limiting the scale to analytical quantities. We report herein high performance liquid chromatography (HPLC) and supercritical fluid chromatography (SFC) protocols for the chiral separation of several racemic spirocyclic terpenoids such as the important flavors theaspirane and vitispirane. A screening of mobile phases and 16 commercially available chiral stationary phases (CSPs) largely based on polysaccharides led to identification of protocols for the separation of all terpenoids tested. SFC methods were found to be particularly useful for the separation of these spirocyclic flavors due to the volatility and low polarity of the compounds. The reported chiral HPLC and SFC protocols are scalable alternatives to gas chromatographic separations of volatile terpenoid flavors.

  3. Comprehensive characterization of Stevia rebaudiana using two-dimensional reversed-phase liquid chromatography/hydrophilic interaction liquid chromatography.

    PubMed

    Fu, Qing; Guo, Zhimou; Zhang, Xiuli; Liu, Yanfang; Liang, Xinmiao

    2012-07-01

    Two-dimensional reversed-phase liquid chromatography/hydrophilic interaction liquid chromatography (2D-RPLC/HILIC) system was successfully applied for comprehensive characterization of steviol glycosides from Stevia rebaudiana. The experiments were performed in offline mode using an XCharge C18 column in first dimension and an XAmide column in second dimension. In first dimension, preliminary separation of Stevia aqueous extract was accomplished and 30 fractions were collected. Then fractions 1-20 were selected for further purification and 13 compounds with high purity were obtained in second dimension. Comprehensive characterization of these compounds was completed by determination of their retention time, accurate molecular weight, diagnostic fragmentation ions, and nuclear magnetic resonance spectroscopy. As a result, all nine known steviol glycosides, as well as other four steviol glycosides were fully purified. The result demonstrated that this procedure is an effective approach for the preparative separation and comprehensive characterization of steviol glycosides in Stevia. This 2D-RPLC/HILIC method will be a promising tool for the purification of low-abundance compounds from natural products.

  4. Comparison of liquid chromatography-microchip/mass spectrometry to conventional liquid chromatography-mass spectrometry for the analysis of steroids.

    PubMed

    Ahonen, Linda; Keski-Rahkonen, Pekka; Saarelainen, Taija; Paviala, Jenni; Ketola, Raimo A; Auriola, Seppo; Poutanen, Matti; Kostianen, Risto

    2012-04-06

    The feasibility of a microfluidic-based liquid chromatography-electrospray ionization/mass spectrometric system (HPLC-Chip/ESI/MS) was studied and compared to a conventional narrow-bore liquid chromatography-electrospray ionization/mass spectrometric (LC-ESI/MS) system for the analysis of steroids. The limits of detection (LODs) for oxime derivatized steroids, expressed as concentrations, were slightly higher with the HPLC-Chip/MS system (50-300 pM) using an injection volume of 0.5 μL than with the conventional LC-ESI/MS (10-150 pM) using an injection volume of 40 μL. However, when the LODs are expressed as injected amounts, the sensitivity of the HPLC-Chip/MS system was about 50 times higher than with the conventional LC-ESI/MS system. The results indicate that the use of HPLC-Chip/MS system is clearly advantageous only in the analysis of low-volume samples. Both methods showed good linearity and good quantitative and chromatographic repeatability. In addition to the instrument comparisons with oxime derivatized steroids, the feasibility of the HPLC-Chip/MS system in the analysis of non-derivatized and oxime derivatized steroids was compared. The HPLC-Chip/MS method developed for non-derivatized steroids was also applied to the quantitative analysis of 15 mouse plasma samples. Copyright © 2012 Elsevier B.V. All rights reserved.

  5. Evaluation between ultrahigh pressure liquid chromatography and high-performance liquid chromatography analytical methods for characterizing natural dyestuffs.

    PubMed

    Serrano, Ana; van Bommel, Maarten; Hallett, Jessica

    2013-11-29

    An evaluation was undertaken of ultrahigh pressure liquid chromatography (UHPLC) in comparison to high-performance liquid chromatography (HPLC) for characterizing natural dyes in cultural heritage objects. A new UHPLC method was optimized by testing several analytical parameters adapted from prior UHPLC studies developed in diverse fields of research. Different gradient elution programs were tested on seven UHPLC columns with different dimensions and stationary phase compositions by applying several mobile phases, flow rates, temperatures, and runtimes. The UHPLC method successfully provided more improved data than that achieved by the HPLC method. Indeed, even though carminic acid has shown circa 146% higher resolution with HPLC, UHPLC resulted in an increase of 41-61% resolution and a decrease of 91-422% limit of detection, depending on the dye compound. The optimized method was subsequently assigned to analyse 59 natural reference materials, in which 85 different components were ascribed with different physicochemical properties, in order to create a spectral database for future characterization of dyes in cultural heritage objects. The majority of these reference samples could be successfully distinguished with one single method through the examination of these compounds' retention times and their spectra acquired with a photodiode array detector. These results demonstrate that UHPLC analyses are extremely valuable for the acquisition of more precise chromatographic information concerning natural dyes with complex mixtures of different and/or closely related physicochemical properties, essential for distinguishing similar species of plants and animals used to colour cultural heritage objects.

  6. Method transfer from high-pressure liquid chromatography to ultra-high-pressure liquid chromatography. II. Temperature and pressure effects.

    PubMed

    Åsberg, Dennis; Samuelsson, Jörgen; Leśko, Marek; Cavazzini, Alberto; Kaczmarski, Krzysztof; Fornstedt, Torgny

    2015-07-03

    The importance of the generated temperature and pressure gradients in ultra-high-pressure liquid chromatography (UHPLC) are investigated and compared to high-pressure liquid chromatography (HPLC). The drug Omeprazole, together with three other model compounds (with different chemical characteristics, namely uncharged, positively and negatively charged) were used. Calculations of the complete temperature profile in the column at UHPLC conditions showed, in our experiments, a temperature difference between the inlet and outlet of 16 °C and a difference of 2 °C between the column center and the wall. Through van't Hoff plots, this information was used to single out the decrease in retention factor (k) solely due to the temperature gradient. The uncharged solute was least affected by temperature with a decrease in k of about 5% while for charged solutes the effect was more pronounced, with k decreases up to 14%. A pressure increase of 500 bar gave roughly 5% increase in k for the uncharged solute, while omeprazole and the other two charged solutes gave about 25, 20 and 15% increases in k, respectively. The stochastic model of chromatography was applied to estimate the dependence of the average number of adsorption/desorption events (n) and the average time spent by a molecule in the stationary phase (τs) on temperature and pressure on peak shape for the tailing, basic solute. Increasing the temperature yielded an increase in n and decrease in τs which resulted in less skew at high temperatures. With increasing pressure, the stochastic modeling gave interesting results for the basic solute showing that the skew of the peak increased with pressure. The conclusion is that pressure effects are more pronounced for both retention and peak shape than the temperature effects for the polar or charged compounds in our study.

  7. Optimized determination of polybrominated diphenyl ethers by ultrasound-assisted liquid-liquid extraction and high-performance liquid chromatography.

    PubMed

    He, Kuang; Lv, YuanCai; Chen, YuanCai

    2014-10-01

    A method based on ultrasound-assisted liquid-liquid extraction and high-performance liquid chromatography has been optimized for the determination of six polybrominated diphenyl ether congeners. The optimal condition relevant to the extraction was first investigated, more than 98.7 ± 0.7% recovery was achieved with dichloromethane as extractant, 5 min extraction time, and three cycles of ultrasound-assisted liquid-liquid extraction. Then multiple function was employed to optimize polybrominated diphenyl ether detection conditions with overall resolution and chromatography signal area as the responses. The condition chosen in this experiment was methanol/water 93:7 v/v, flow rate 0.80 mL/min, column temperature 30.0°C. The optimized technique revealed good linearity (R(2) > 0.9962 over a concentration range of 1-100 μg/L) and repeatability (relative standard deviation < 6.3%). Furthermore, the detection limit (S/N = 3) of the method were ranged from 0.02 to 0.13 μg/L and the quantification limit (S/N = 10) ranged from 0.07 to 0.35 μg/L. Finally, the proposed method was applied to spiked samples and satisfactory results were achieved. These results indicate that ultrasound-assisted liquid-liquid extraction coupled with high-performance liquid chromatography was effective to identify and quantify the complex polybrominated diphenyl ethers in effluent samples. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Fully automatable two-dimensional hydrophilic interaction liquid chromatography-reversed phase liquid chromatography with online tandem mass spectrometry for shotgun proteomics.

    PubMed

    Zhao, Yun; Kong, Ricky P W; Li, Guohui; Lam, Maggie P Y; Law, C H; Lee, Simon M Y; Lam, Herman C; Chu, Ivan K

    2012-07-01

    We have developed a fully automatable two-dimensional liquid chromatography platform for shotgun proteomics analyses based on the online coupling of hydrophilic interaction liquid chromatography (HILIC) - using a nonionic type of TSKgel Amide 80 at either pH 6.8 (neutral) or 2.7 (acidic) - with conventional low-pH reversed-phase chromatography. Online coupling of the neutral-pH HILIC and reversed phase chromatography systems outperformed the acidic HILIC-reversed phase chromatography combination, resulting in 18.4% (1914 versus 1617 nonredundant proteins) and 41.6% (12,989 versus 9172 unique peptides) increases in the number of identified peptides and proteins from duplicate analyses of Rat pheochromocytoma lysates. Armed with this optimized HILIC-reversed phase liquid chromatography platform, we identified 2554 nonredundant proteins from duplicate analyses of a Saccharomyces cerevisiae lysate, with the detected protein abundances spanning from approximately 41 to 10(6) copies per cell, which contained up to approximately 2092 different validated protein species with a dynamic range of concentrations of up to approximately 10(4) . This present study establishes a fully automated platform as a promising methodology to enable online coupling of different hydrophilic HILIC and reversed phase chromatography systems, thereby expanding the repertoire of multidimensional liquid chromatography for shotgun proteomics.

  9. Ultrafast Chiral Chromatography as the Second Dimension in Two-Dimensional Liquid Chromatography Experiments.

    PubMed

    Barhate, Chandan L; Regalado, Erik L; Contrella, Nathan D; Lee, Joon; Jo, Junyong; Makarov, Alexey A; Armstrong, Daniel W; Welch, Christopher J

    2017-03-21

    Chromatographic separation and analysis of complex mixtures of closely related species is one of the most challenging tasks in modern pharmaceutical analysis. In recent years, two-dimensional liquid chromatography (2D-LC) has become a valuable tool for improving peak capacity and selectivity. However, the relatively slow speed of chiral separations has limited the use of chiral stationary phases (CSPs) as the second dimension in 2D-LC, especially in the comprehensive mode. Realizing that the recent revolution in the field of ultrafast enantioselective chromatography could now provide significantly faster separations, we herein report an investigation into the use of ultrafast chiral chromatography as a second dimension for 2D chromatographic separations. In this study, excellent selectivity, peak shape, and repeatability were achieved by combining achiral and chiral narrow-bore columns (2.1 mm × 100 mm and 2.1 mm × 150 mm, sub-2 and 3 μm) in the first dimension with 4.6 mm × 30 mm and 4.6 mm × 50 mm columns packed with highly efficient chiral selectors (sub-2 μm fully porous and 2.7 μm fused-core particles) in the second dimension, together with the use of 0.1% phosphoric acid/acetonitrile eluents in both dimensions. Multiple achiral × chiral and chiral × chiral 2D-LC examples (single and multiple heart-cutting, high-resolution sampling, and comprehensive) using ultrafast chiral chromatography in the second dimension are successfully applied to the separation and analysis of complex mixtures of closely related pharmaceuticals and synthetic intermediates, including chiral and achiral drugs and metabolites, constitutional isomers, stereoisomers, and organohalogenated species.

  10. Determination of sulfonamides in butter samples by ionic liquid magnetic bar liquid-phase microextraction high-performance liquid chromatography.

    PubMed

    Wu, Lijie; Song, Ying; Hu, Mingzhu; Xu, Xu; Zhang, Hanqi; Yu, Aimin; Ma, Qiang; Wang, Ziming

    2015-01-01

    A novel, simple, and environmentally friendly pretreatment method, ionic liquid magnetic bar liquid-phase microextraction, was developed for the determination of sulfonamides in butter samples by high-performance liquid chromatography. The ionic liquid magnetic bar was prepared by inserting a stainless steel wire into the hollow of a hollow fiber and immobilizing ionic liquid in the micropores of the hollow fiber. In the extraction process, the ionic liquid magnetic bars were used to stir the mixture of sample and extraction solvent and enrich the sulfonamides in the mixture. After extraction, the analyte-adsorbed ionic liquid magnetic bars were readily isolated with a magnet from the extraction system. It is notable that the present method was environmentally friendly since water and only several microliters of ionic liquid were used in the whole extraction process. Several parameters affecting the extraction efficiency were investigated and optimized, including the type of ionic liquid, sample-to-extraction solvent ratio, the number of ionic liquid magnetic bars, extraction temperature, extraction time, salt concentration, stirring speed, pH of the extraction solvent, and desorption conditions. The recoveries were in the range of 73.25-103.85 % and the relative standard deviations were lower than 6.84 %. The experiment results indicated that the present method was effective for the extraction of sulfonamides in high-fat content samples.

  11. Liquid-chromatography mass spectrometry (LC-MS) of steroid hormone metabolites and its applications

    PubMed Central

    Penning, Trevor M.; Lee, Seon-Hwa; Jin, Yi; Gutierrez, Alejandro; Blair, Ian A.

    2010-01-01

    Advances in liquid chromatography-mass spectrometry (LC-MS) can be used to measure steroid hormone metabolites in vitro and in vivo. We find that LC-Electrospray Ionization (ESI)-MS using a LCQ ion trap mass spectrometer in the negative ion mode can be used to monitor the product profile that results from 5α–dihydrotestosterone(DHT)-17β-glucuronide, DHT-17β-sulfate, and tibolone-17β-sulfate reduction catalyzed by human members of the aldo-keto reductase (AKR) 1C subfamily and assign kinetic constants to these reactions. We also developed a stable-isotope dilution LC-electron capture atmospheric pressure chemical ionization (ECAPCI)-MS method for the quantitative analysis of estrone (E1) and its metabolites as pentafluorobenzyl (PFB) derivatives in human plasma in the attomole range. The limit of detection for E1-PFB was 740 attomole on column. Separations can be performed using normal-phase LC because ionization takes place in the gas phase rather than in solution. This permits efficient separation of the regioisomeric 2- and 4-methoxy-E1. The method was validated for the simultaneous analysis of plasma E2 and its metabolites: 2-methoxy-E2, 4-methoxy-E2, 16α-hydroxy-E2, estrone (E1), 2-methoxy-E1, 4-methoxy-EI, and 16α-hydroxy-E1 from 5 pg/mL to 2,000 pg/mL. Our LC-MS methods have sufficient sensitivity to detect steroid hormone levels in prostate and breast tumors and should aid their molecular diagnosis and treatment. PMID:20083198

  12. Enantiomeric Separations of Pyriproxyfen and its Six Chiral Metabolites by High-Performance Liquid Chromatography.

    PubMed

    Zhang, Chuntao; Liu, Hui; Liu, Donghui; Wang, Liying; Gao, Jing; Zhou, Zhiqiang; Wang, Peng

    2016-03-01

    Pyriproxyfen is a chiral insecticide, and over 10 metabolites have been identified in the environment. In this work the separations of the enantiomers of pyriproxyfen and its six chiral metabolites were studied by high-performance liquid chromatography (HPLC). Both normal phase and reverse phase were applied using the chiral columns Chiralpak IA, Chiralpak IB, Chiralpak IC, Chiralcel OD, Chiralcel OD-RH, Chiralpak AY-H, Chiralpak AD-H, Chiracel OJ-H, (R,R)-Whelk-O 1, and Lux Cellulose-3. The effects of the chromatographic parameters such as mobile phase composition and temperature on the separations were investigated and the enantiomers were identified with an optical rotation detector. The enantiomers of these targets could obtain complete separations (resolution factor Rs > 1.5) on Chiralpak IA, Chiralpak IB, Chiralcel OD, Chiralpak AY-H, or Chiracel OJ-H under normal conditions. Chiralcel OJ-H showed the best chiral separation results with n-hexane as mobile phase and isopropanol (IPA) as modifier. The simultaneous enantiomeric separation of pyriproxyfen and four chiral metabolites was achieved on Chiralcel OJ-H under optimized condition: n-hexane/isopropanol = 80/20, 15°C, flow rate of 0.8 ml/min, and UV detection at 230 nm. The enantiomers of pyriproxyfen and the metabolites , , and obtained complete separations on Chiralpak IA, Chiralpak IC, and Lux Cellulose-3 under reverse phase using acetonitrile/water as the mobile phase. The retention factors (k) and selectivity factors (α) decreased with increasing temperature, and the separations were better under low temperature in most cases. The work is of significance for the investigation of the environmental behaviors of pyriproxyfen on an enantiomeric level.

  13. Liquid chromatography-mass spectrometry in metabolomics research: mass analyzers in ultra high pressure liquid chromatography coupling.

    PubMed

    Forcisi, Sara; Moritz, Franco; Kanawati, Basem; Tziotis, Dimitrios; Lehmann, Rainer; Schmitt-Kopplin, Philippe

    2013-05-31

    The present review gives an introduction into the concept of metabolomics and provides an overview of the analytical tools applied in non-targeted metabolomics with a focus on liquid chromatography (LC). LC is a powerful analytical tool in the study of complex sample matrices. A further development and configuration employing Ultra-High Pressure Liquid Chromatography (UHPLC) is optimized to provide the largest known liquid chromatographic resolution and peak capacity. Reasonably UHPLC plays an important role in separation and consequent metabolite identification of complex molecular mixtures such as bio-fluids. The most sensitive detectors for these purposes are mass spectrometers. Almost any mass analyzer can be optimized to identify and quantify small pre-defined sets of targets; however, the number of analytes in metabolomics is far greater. Optimized protocols for quantification of large sets of targets may be rendered inapplicable. Results on small target set analyses on different sample matrices are easily comparable with each other. In non-targeted metabolomics there is almost no analytical method which is applicable to all different matrices due to limitations pertaining to mass analyzers and chromatographic tools. The specifications of the most important interfaces and mass analyzers are discussed. We additionally provide an exemplary application in order to demonstrate the level of complexity which remains intractable up to date. The potential of coupling a high field Fourier Transform Ion Cyclotron Resonance Mass Spectrometer (ICR-FT/MS), the mass analyzer with the largest known mass resolving power, to UHPLC is given with an example of one human pre-treated plasma sample. This experimental example illustrates one way of overcoming the necessity of faster scanning rates in the coupling with UHPLC. The experiment enabled the extraction of thousands of features (analytical signals). A small subset of this compositional space could be mapped into a mass

  14. Recent advances in ultra-high performance liquid chromatography for the analysis of traditional chinese medicine

    USDA-ARS?s Scientific Manuscript database

    Traditional Chinese medicines (TCMs) have been widely used for the prevention and treatment of various diseases for thousands of years in China. Ultra Performance Liquid Chromatography (UHPLC) is a relatively new technique offering new possibilities in liquid chromatography. This paper reviews recen...

  15. Investigating the Retention Mechanisms of Liquid Chromatography Using Solid-Phase Extraction Cartridges

    ERIC Educational Resources Information Center

    O'Donnell, Mary E.; Musial, Beata A.; Bretz, Stacey Lowery; Danielson, Neil D.; Ca, Diep

    2009-01-01

    Liquid chromatography (LC) experiments for the undergraduate analytical laboratory course often illustrate the application of reversed-phase LC to solve a separation problem, but rarely compare LC retention mechanisms. In addition, a high-performance liquid chromatography instrument may be beyond what some small colleges can purchase. Solid-phase…

  16. Investigating the Retention Mechanisms of Liquid Chromatography Using Solid-Phase Extraction Cartridges

    ERIC Educational Resources Information Center

    O'Donnell, Mary E.; Musial, Beata A.; Bretz, Stacey Lowery; Danielson, Neil D.; Ca, Diep

    2009-01-01

    Liquid chromatography (LC) experiments for the undergraduate analytical laboratory course often illustrate the application of reversed-phase LC to solve a separation problem, but rarely compare LC retention mechanisms. In addition, a high-performance liquid chromatography instrument may be beyond what some small colleges can purchase. Solid-phase…

  17. Applications of nanomaterials in liquid chromatography: opportunities for separation with high efficiency and selectivity.

    PubMed

    Zhang, Zhengxiang; Wang, Zhiyong; Liao, Yiping; Liu, Huwei

    2006-08-01

    During recent decades, great efforts have been made to improve the chemical stability, selectivity, and separation efficiency of stationary phases in liquid chromatography. Significant progress has been achieved, especially after the introduction of nanomaterials into separation science. This review covers the applications of nanomaterials playing various roles in liquid chromatography. Future possibilities for developing nanomaterial-based stationary phases are also discussed.

  18. Application of Inverse Liquid Chromatography for Surface Characterization of Biomaterials.

    PubMed

    Adamska, Katarzyna; Kadlec, Karol; Voelkel, Adam

    In the present study, a novel approach for surface characterization of ceramic biomaterials is proposed. Two ceramic biomaterials-hydroxyapatite and β-tricalcium phosphate-were examined by means of inverse liquid chromatography. The Abraham LFER model was applied for physicochemical characteristics of the surface. Different compounds, characterized by different polarity and different donor-acceptor properties of functional group, were used as test solutes. The chromatographic experiments were carried out with two compositions of the mobile phase: pure acetonitrile (MeCN) and the mixture of acetonitrile and water in 80:20 ratio (MeCN/H2O). Thus, the influence of mobile phase on sorption properties of hydroxyapatite and tricalcium phosphate surface was also discussed.

  19. Structural analysis of amorphous phosphates using high performance liquid chromatography

    SciTech Connect

    Sales, B.C.; Boatner, L.A.; Chakoumakos, B.C.; McCallum, J.C.; Ramey, J.O.; Zuhr, R.A.

    1993-12-31

    Determining the atomic-scale structure of amorphous solids has proven to be a formidable scientific and technological problem for the past 100 years. The technique of high-performance liquid chromatography (HPLC) provides unique detailed information regarding the structure of partially disordered or amorphous phosphate solids. Applications of the experimental technique of HPLC to phosphate solids are reviewed, and examples of the type of information that can be obtained with HPLC are presented. Inorganic phosphates encompass a large class of important materials whose applications include: catalysts, ion-exchange media, solid electrolytes for batteries, linear and nonlinear optical components, chelating agents, synthetic replacements for bone and teeth, phosphors, detergents, and fertilizers. Phosphate ions also represent a unique link between living systems and the inorganic world.

  20. Protein identification using nano liquid chromatography-tandem mass spectrometry.

    PubMed

    Negroni, Luc

    2007-01-01

    Tandem mass spectrometry is an efficient technique for the identification of peptides on the basis of their fragmentation pattern (MS/MS scan). It can generate individual spectra for each peptide, thereby creating a powerful tool for protein identification on the basis of peptide characterization. This important advance in automatic data acquisition has allowed an efficient association between liquid chromatography and tandem mass spectrometry, and the use of nanocolumns and nanoelectrospray ionization has dramatically increased the efficiency of this method. Now large sets of peptides can be identified at a femtomole level. At the end of the process, batch processing of the MS/MS spectra produces peptide lists that identify purified proteins or protein mixtures with high confidence.

  1. High performance liquid chromatography characteristic spectrum of artificial musk.

    PubMed

    Zhang, Ping; Xiao, Xuan; Zhang, Nan-Ping; Xiao, Xin-Yue; Zhang, Shu; Wei, Feng; Yu, De-Quan

    2014-12-01

    To determine the high performance liquid chromatography(HPLC)characteristic spectrum of artificial musk. HPLC was performed on a HiQ Sil C18 analytical column(4.6 mm×250 mm)with the mobile phase of methanol/water(90:10 v/v);the detection wavelength was 254 nm and the column temperature was maintained at 25 ℃. The similarities among 10 batches of artificial musk samples were anlysised in accordance with the System for Evaluating the Similarities among the Chromatographic Fingerprints of Traditional Chinese Drugs,which is recommended by Chinese Pharmacopoeia Commission. The similarities among these 10 batches of artificial musk ranged between 0.999 and 1.000. HPLC is a convenient,accurate and reliable technique for establishing the specific spectum of artificial musk and therefore can be used for the quality control of this product.

  2. A rapid liquid chromatography determination of free formaldehyde in cod.

    PubMed

    Storey, Joseph M; Andersen, Wendy C; Heise, Andrea; Turnipseed, Sherri B; Lohne, Jack; Thomas, Terri; Madson, Mark

    2015-01-01

    A rapid method for the determination of free formaldehyde in cod is described. It uses a simple water extraction of formaldehyde which is then derivatised with 2,4-dinitrophenylhydrazine (DNPH) to form a sensitive and specific chromophore for high-performance liquid chromatography (HPLC) detection. Although this formaldehyde derivative has been widely used in past tissue analysis, this paper describes an improved derivatisation procedure. The formation of the DNPH formaldehyde derivative has been shortened to 2 min and a stabilising buffer has been added to the derivative to increase its stability. The average recovery of free formaldehyde in spiked cod was 63% with an RSD of 15% over the range of 25-200 mg kg(-1) (n = 48). The HPLC procedure described here was also compared to a commercial qualitative procedure - a swab test for the determination of free formaldehyde in fish. Several positive samples were compared by both methods.

  3. Ultra high pressure liquid chromatography for crude plant extract profiling.

    PubMed

    Eugster, Philippe J; Guillarme, Davy; Rudaz, Serge; Veuthey, Jean-Luc; Carrupt, Pierre-Alain; Wolfender, Jean-Luc

    2011-01-01

    Ultra high pressure liquid chromatography (UHPLC) systems operating at very high pressures and using sub-2 microm packing columns have allowed a remarkable decrease in analysis time and increase in peak capacity, sensitivity, and reproducibility compared to conventional HPLC. This technology has rapidly been widely accepted by the analytical community and is being gradually applied to various fields of plant analysis such as QC, profiling and fingerprinting, dereplication, and metabolomics. For many applications, an important improvement of the overall performances has been reported. In this review, the basic principles of UHPLC are summarized, and practical information on the type of columns used and phase chemistry available is provided. An overview of the latest applications to natural product analysis in complex mixtures is given, and the potential and limitations as well as some new trends in the development of UHPLC are discussed.

  4. Nano-liquid chromatography in pharmaceutical and biomedical research.

    PubMed

    Gama, Mariana Roberto; Collins, Carol H; Bottoli, Carla B G

    2013-08-01

    Miniaturized separation techniques have emerged as environmentally friendly alternatives to available separation methods. Nano-liquid chromatography (nano-LC), microchip devices and nano-capillary electrophoresis are miniaturized methods that minimize reagent consumption and waste generation. Furthermore, the low levels of analytes, especially in biological samples, promote the search for more highly sensitive techniques; coupled to mass spectrometry, nano-LC has great potential to become an indispensable tool for routine analysis of biomolecules. This short review presents the fundamental aspects of nano-LC analytical instrumentation, discussing practical considerations and the primary differences between miniaturized and conventional instrumentation. Some theoretical aspects are discussed to better explain both the potential and the principal limitations of nano-LC. Recent pharmaceutical and biomedical applications of this separation technique are also presented to indicate the satisfactory performance for complex matrices, especially for proteomic analysis, that is obtained with nano-LC.

  5. Liquid chromatography of active principles in Sophora flavescens root.

    PubMed

    Chen, Xi; Yi, Changqing; Yang, Xiaoqing; Wang, Xiaoru

    2004-12-05

    Herbal medicines were one of the major resources for healthcare in earlier stages, and some traditional herbal medicines have been in use for more than 2000 years. Currently, they are attracting more and more attention of the modern pharmaceutical industry, as scientists has become aware that herbs have almost infinite resources for medicine development. This review provides an overview of the analytical approaches applied in the researches concentrated on various aspects of the matrine-type alkaloids in Sophora flavescens root. Emphasis will be laid on the analytical processes of high-performance liquid chromatography (HPLC), capillary electrophoresis (CE), as well as gas chromatography (GC) methods. The sample extraction, separation and detection have been summarized. In addition, the applications of chromatographic determinations are introduced for the main matrine-type alkaloids in S. flavescens root, such as matrine, sophoridine, sophocarpine, lehmannine, sophoramine, oxymartine, oxysophocarpine, cytosine and aloperine. The advantages and limitations of HPLC, CE and GC methods in the analytical applications of the alkaloids are also discussed.

  6. Quantitative analysis of aromatics for synthetic biology using liquid chromatography.

    PubMed

    Lai, Bin; Plan, Manuel R; Averesch, Nils J H; Yu, Shiqin; Kracke, Frauke; Lekieffre, Nicolas; Bydder, Sarah; Hodson, Mark P; Winter, Gal; Krömer, Jens O

    2017-01-01

    The replacement of petrochemical aromatics with bio-based molecules is a key area of current biotechnology research. To date, a small number of aromatics have been produced by recombinant bacteria in laboratory scale while industrial production still requires further strain development. While each study includes some distinct analytical methodology to quantify certain aromatics, a method that can reliably quantify a great number of aromatic products and relevant pathway intermediates is needed to accelerate strain development. In this study, we developed a robust reverse phase high performance liquid chromatography method to quantify a wide range of aromatic metabolites present in host microorganisms using the shikimate pathway, which is the major metabolic pathway for biosynthesis of aromatics. Twenty-three metabolites can be quantified precisely with the optimized method using standard HPLC equipment and UV detection, with the mobile phase used for chromatography also compatible with mass spectrometry (MS). The limit of quantification/detection is as low as 10(-10) to 10(-13) mol, respectively, which makes this method feasible for quantification of intracellular metabolites. This method covers most metabolic routes for aromatics biosynthesis, it is inexpensive, robust, simple, precise and sensitive, and has been demonstrated on cell extracts from S. cerevisiae genetically engineered to overproduce aromatics. Copyright © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Group type analysis of asphalt by column liquid chromatography

    SciTech Connect

    Zhang, C.; Yang, J.; Xue, Y.; Li, Y.

    2008-07-01

    An improved analysis method for characterization of asphalt was established. The method is based on column chromatography technique. The asphalts were separated into four groups: saturates, aromatics, resins, and asphaltenes, quantitatively. About 0.1 g of sample was required in each analysis. About 20 mL of n-heptanes was used to separate out saturates first. Then about 35 mL of n-heptanes/dichloromethane (.5, v/v) mixture was used to separate out aromatics. About 30 mL of dichloromethane/tetrahydrofuran (1/3, v/v) mixture was used to separate out resin. The quality of the separation was confirmed by infrared spectra (IR) and {sup 1}H NMR analysis. The model compounds, tetracosan for saturates, dibenz(o)anthracen for aromatics, and acetanilide for resins were used for verification. The IR and {sup 1}H NMR analysis of the prepared fractions from the column liquid chromatography were in good agreement that of pure reagents.

  8. Gradient chromatofocusing high-performance liquid chromatography. I. Practical aspects.

    PubMed

    Liu, Y; Anderson, D J

    1997-02-21

    In this work, a versatile method for generating linear pH gradients using weak anion-exchange HPLC has been developed, which is termed gradient chromatofocusing high-performance liquid chromatography. This method utilizes a linear external pH gradient generated in the mobile phase entering the column (inlet pH gradient), superimposed on an internally-generated pH gradient within the column (column pH gradient), which results from the buffering action of the ion exchanger on the mobile phase and vice versa. The method shows significant advantages over conventional chromatofocusing, including: decreased expense due to the use of common buffer components, ease of adjusting the slope of the pH gradient produced at the outlet of the column (outlet pH gradient) through the manipulation of the inlet pH gradient and the ability of using high concentration buffers in the mobile phase. Chromatography of fibrinogen degradation products was done using gradient chromatofocusing. Bandwidths comparable to conventional chromatofocusing were obtained in the separation of fibrinogen degradation products.

  9. Cortisol production rates measured by liquid chromatography/mass spectrometry

    SciTech Connect

    Esteban, N.V.; Yergey, A.L. )

    1990-04-01

    Cortisol production rates (FPRs) in physiologic and pathologic states in humans have been investigated over the past 30 years. However, there has been conflicting evidence concerning the validity of the currently accepted value of FPRs in humans (12 to 15 mg/m2/d) as determined by radiotracer methodology. The present study reviews previous methods proposed for the measurement of FPRs in humans and discusses the applications of the first method for the direct determination of 24-hour plasma FPRs during continuous administration of a stable isotope, using a thermospray high-pressure liquid chromatography-mass spectrometry technique. The technique is fast, sensitive, and, unlike gas chromatography-mass spectrometry methods, does not require derivatization, allowing on-line detection and quantification of plasma cortisol after a simple extraction procedure. The results of determination of plasma FPRs by stable tracer/mass spectrometry are directly in units of mass/time and, unlike radiotracer methods, are independent of any determination of volume of distribution or cortisol concentration. Our methodology offers distinct advantages over radiotracer techniques in simplicity and reliability since only single measurements of isotope ratios are required. The technique was validated in adrenalectomized patients. Circadian variations in daily FRPs were observed in normal volunteers, and, to date, results suggest a lower FRP in normal children and adults than previously believed. 88 references.

  10. Reliability of the retention factor estimations in liquid chromatography.

    PubMed

    Escuder-Gilabert, L; Bermúdez-Saldaña, J M; Villanueva-Camañas, R M; Medina-Hernández, M J; Sagrado, S

    2004-04-16

    The retention factor is one of the most universally used parameters in chromatography. However, large differences in the experimental retention factor values are observed when the same compound is injected in a given stationary/mobile phase system under intermediate precision conditions. Conventional protocols for estimating retention factors have problems that mainly arise from difficulties in the hold-up time measurements and the omission of the existence of extra-column times by practicing chromatographers. In the present paper, three different approaches for estimating retention factors are tested: (i) classical retention factor estimations based on the gross hold-up time, (ii) based on the real hold-up time (taking into account the extra-column time), and (iii) a new approach that uses 'relative' retention factors based on the use of an external standard. Assays are performed in micellar liquid chromatography (MLC) under intermediate precision conditions (different days, equipments, columns lengths, and mobile phase flow rates). The reliability of the three approaches tested is evaluated by means of precision studies, analysis of factors affecting retention factors, and uncertainty calculations. The approach based on 'relative' retention factors was found to be the most precise, reliable, and robust strategy for estimating retention factors.

  11. Modern Aspects Of Fluorometric Detection In Liquid-Phase Chromatography

    NASA Astrophysics Data System (ADS)

    Bousquet, Bernard; Garnier, Jean P.; Dreux, Claude

    1983-10-01

    Recent advances are described in the combined use of fluorometric derivatization and high performance liquid chromatography (HPLC) for clinical chemistry determinations. Derivatives (especially dansyl derivatives) can be formed prior to chromatography in the case of estrogens, amino acids, and catecholamines. In post-column reactions, we preferred to use air-segmented reactions as they conform better to all the optimized chromatographic and spectrofluorometric parameters. Fluorescent derivatives produced from cate-cholamines, tryptophan and its metabolites, hydroxyindoles, tryptamine, amino acids, sugars, polyamines, and other substances are often sufficiently sensitive to be detected in picogram quantities by HPLC. Their reaction principle and some of their applications to samples are described. Recently, chemical excitation of fluorophore-like dansyl amino acid was proposed as a detection system for HPLC. By a post-column reaction, a fluorophore can be made to emit light by its reaction with trichlorophenyl oxalate (TCPO) and hydrogen peroxide. The detection limit of this system is about 10 fmol for each dansyl amino acid. Application of this new reaction to catecholamines opens up new prospects for fluorometric detection.

  12. Towards Chip Scale Liquid Chromatography and High Throughput Immunosensing

    SciTech Connect

    Ni, Jing

    2000-09-21

    This work describes several research projects aimed towards developing new instruments and novel methods for high throughput chemical and biological analysis. Approaches are taken in two directions. The first direction takes advantage of well-established semiconductor fabrication techniques and applies them to miniaturize instruments that are workhorses in analytical laboratories. Specifically, the first part of this work focused on the development of micropumps and microvalves for controlled fluid delivery. The mechanism of these micropumps and microvalves relies on the electrochemically-induced surface tension change at a mercury/electrolyte interface. A miniaturized flow injection analysis device was integrated and flow injection analyses were demonstrated. In the second part of this work, microfluidic chips were also designed, fabricated, and tested. Separations of two fluorescent dyes were demonstrated in microfabricated channels, based on an open-tubular liquid chromatography (OT LC) or an electrochemically-modulated liquid chromatography (EMLC) format. A reduction in instrument size can potentially increase analysis speed, and allow exceedingly small amounts of sample to be analyzed under diverse separation conditions. The second direction explores the surface enhanced Raman spectroscopy (SERS) as a signal transduction method for immunoassay analysis. It takes advantage of the improved detection sensitivity as a result of surface enhancement on colloidal gold, the narrow width of Raman band, and the stability of Raman scattering signals to distinguish several different species simultaneously without exploiting spatially-separated addresses on a biochip. By labeling gold nanoparticles with different Raman reporters in conjunction with different detection antibodies, a simultaneous detection of a dual-analyte immunoassay was demonstrated. Using this scheme for quantitative analysis was also studied and preliminary dose-response curves from an immunoassay of a

  13. Highly efficient and ultra-small volume separation by pressure-driven liquid chromatography in extended nanochannels.

    PubMed

    Ishibashi, Ryo; Mawatari, Kazuma; Kitamori, Takehiko

    2012-04-23

    The rapidly developing interest in nanofluidic analysis, which is used to examine liquids ranging in amounts from the attoliter to the femtoliter scale, correlates with the recent interest in decreased sample amounts, such as in the field of single-cell analysis. For general nanofluidic analysis, the fact that a pressure-driven flow does not limit the choice of solvents (aqueous or organic) is important. This study shows the first pressure-driven liquid chromatography technique that enables separation of atto- to femtoliter sample volumes, with a high separation efficiency within a few seconds. The apparent diffusion coefficient measurement of the unretentive sample suggests that there is no increase in the viscosity of toluene in the extended nanospace, unlike in aqueous solvents. Evaluation of the normal phase separation, therefore, should involve only the examination of the effect of the small size of the extended nanospace. Compared to a conventionally packed high-performance liquid chromatography column, the separation here results in a faster separation (4 s) by 2 orders of magnitude, a smaller injection volume (10(0) fL) by 9 orders, and a higher separation efficiency (440,000 plates/m) by 1 order. Moreover, the separation behavior agrees with the theory showing that this high efficiency was due to the small and controlled size of the separation channel, where the diffusion through the channel depth direction is fast enough to be neglected. Our chip-based platform should allow direct and real-time analysis or screening of ultralow volume of sample.

  14. Salting-out assisted liquid-liquid extraction coupled to dispersive liquid-liquid microextraction for the determination of chlorophenols in wine by high-performance liquid chromatography.

    PubMed

    Fan, Yingying; Hu, Shibin; Liu, Shuhui

    2014-12-01

    A novel procedure of sample preparation combined with high-performance liquid chromatography with diode array detection is introduced for the analysis of highly chlorinated phenols (trichlorophenols, tetrachlorophenols, and pentachlorophenol) in wine. The main features of the proposed method are (i) low-toxicity diethyl carbonate as extraction solvent to selectively extract the analytes without matrix effect, (ii) the combination of salting-out assisted liquid-liquid extraction and dispersive liquid-liquid microextraction to achieve an enrichment factor of 334-361, and (iii) the extract is analyzed by high-performance liquid chromatography to avoid derivatization. Under the optimum conditions, correlation coefficients (r) were >0.997 for calibration curves in the range 1-80 ng/mL, detection limits and quantification limits ranged from 0.19 to 0.67 and 0.63 to 2.23 ng/mL, respectively, and relative standard deviation was <8%. The method was applied for the determination of chlorophenols in real wines, with recovery rates in the range 82-104%. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Quantification of amino acid ionic liquids using liquid chromatography-mass spectrometry.

    PubMed

    Tang, Fei; Wu, Kangkang; Nie, Zhou; Ding, Li; Liu, Qian; Yuan, Jinbin; Guo, Manli; Yao, Shouzhuo

    2008-10-24

    Amino acid ionic liquids (AAILs) containing imidazolium cations and amino acid (AA) anions, were synthesized and applied as task-specific ionic liquids. A sensitive and fast liquid chromatography-mass spectrometry (LC-MS) method was established for the quantitative analysis of 20 AAILs. Using ion pairing-reversed phase liquid chromatography technique, heptafluorobutyric acid was used as ion-pairing reagent to increase the retention of AAILs. Based on the zwitterionity of amino acid, this method was proposed to determine both the cation and the anion of AAILs simultaneously. The limit of detection of this method is down to 1-15ng/mL and the analysis time is less than 15min. According to the analytical data of seven selected AAILs, we found that the content of amino acid anion is always lower than that of butyl methyl imidazolium cation in AAILs. Moreover, the molar ratio of imidazolium cation to amino acid anion is dependent on the chemical property of the amino acid. These results supplied useful information on the interaction of imidazolium cation with acidic, basic, neutral and non-polar amino acids in AAILs.

  16. Pressurized liquid extraction followed by liquid chromatography with tandem mass spectrometry to determine pharmaceuticals in mussels.

    PubMed

    Núñez, Mireia; Borrull, Francesc; Pocurull, Eva; Fontanals, Núria

    2016-02-01

    An analytical method based on pressurized liquid extraction and solid-phase extraction with a mixed-mode Oasis(®) MAX sorbent as cleanup, followed by liquid chromatography with electrospray ionization and tandem mass spectrometry was developed and validated for the determination of seven widely used pharmaceuticals in mussel species. The optimization of the pressurized liquid extraction and the solid-phase extraction parameters is described. The method provided extraction recoveries ranging from 61 to 90%, and limits of detection ranging from 2 to 50 ng/g (dry weight). The repeatability and reproducibility of the method, expressed as relative standard deviation, were lower than 15 and 19%, respectively. The method was successfully applied to the analysis of mussel samples from different locations. The analyses showed that salicylic acid was present in mussels at concentrations up to 177 ng/g (dry weight). © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Determination of descriptors for fragrance compounds by gas chromatography and liquid-liquid partition.

    PubMed

    Karunasekara, Thushara; Poole, Colin F

    2012-04-27

    Retention factors on a minimum of eight stationary phases at various temperatures by gas-liquid chromatography and liquid-liquid partition coefficients for five totally organic biphasic systems were combined to estimate descriptors for 28 fragrance compounds with an emphasis on compounds that are known or potential allergens. The descriptors facilitated the estimation of several properties of biological and environmental interest (sensory irritation threshold, odor detection threshold, nasal pungency threshold, skin permeability from water, skin-water partition coefficients, octanol-water partition coefficients, absorption by air particles, adsorption by diesel soot particles, air-water partition coefficients, and adsorption by film water). The descriptors are suitable for use in the solvation parameter model and facilitate the estimation of a wide range of physicochemical, chromatographic, biological, and environmental properties using existing models.

  18. Liquid chromatography/Fourier transform IR spectrometry interface flow cell

    DOEpatents

    Johnson, Charles C.; Taylor, Larry T.

    1986-01-01

    A zero dead volume (ZDV) microbore high performance liquid chromatography (.mu.HPLC)/Fourier transform infrared (FTIR) interface flow cell includes an IR transparent crystal having a small diameter bore therein through which a sample liquid is passed. The interface flow cell further includes a metal holder in combination with a pair of inner, compressible seals for directly coupling the thus configured spectrometric flow cell to the outlet of a .mu.HPLC column end fitting to minimize the transfer volume of the effluents exiting the .mu.HPLC column which exhibit excellent flow characteristics due to the essentially unencumbered, open-flow design. The IR beam passes transverse to the sample flow through the circular bore within the IR transparent crystal, which is preferably comprised of potassium bromide (KBr) or calcium fluoride (CaF.sub.2), so as to minimize interference patterns and vignetting encountered in conventional parallel-plate IR cells. The long IR beam pathlength and lensing effect of the circular cross-section of the sample volume in combination with the refractive index differences between the solvent and the transparent crystal serve to focus the IR beam in enhancing sample detection sensitivity by an order of magnitude.

  19. Liquid chromatography/Fourier transform IR spectrometry interface flow cell

    DOEpatents

    Johnson, C.C.; Taylor, L.T.

    1985-01-04

    A zero dead volume (ZDV) microbore high performance liquid chromatography (..mu.. HPLC)/Fourier transform infrared (FTIR) interface flow cell includes an IR transparent crystal having a small diameter bore therein through which a sample liquid is passed. The interface flow cell further includes a metal holder in combination with a pair of inner, compressible seals for directly coupling the thus configured spectrometric flow cell to the outlet of a ..mu.. HPLC column end fitting to minimize the transfer volume of the effluents exiting the ..mu.. HPLC column which exhibit excellent flow characteristics due to the essentially unencumbered, open-flow design. The IR beam passes transverse to the sample flow through the circular bore within the IR transparent crystal, which is preferably comprised of potassium bromide (KBr) or calcium fluoride (CaF/sub 2/), so as to minimize interference patterns and vignetting encountered in conventional parallel-plate IR cells. The long IR beam pathlength and lensing effect of the circular cross-section of the sample volume in combination with the refractive index differences between the solvent and the transparent crystal serve to focus the IR beam in enhancing sample detection sensitivity by an order of magnitude.

  20. Profiling degradants of paclitaxel using liquid chromatography-mass spectrometry and liquid chromatography-tandem mass spectrometry substructural techniques.

    PubMed

    Volk, K J; Hill, S E; Kerns, E H; Lee, M S

    1997-08-15

    A rapid and systematic strategy based on liquid chromatography-mass spectrometry (LC-MS) profiling and liquid chromatography-tandem mass spectrometry (LC-MS-MS) substructural techniques was utilized to elucidate the degradation products of paclitaxel, the active ingredient in Taxol. This strategy integrates, in a single instrumental approach, analytical HPLC, UV detection, full-scan electrospray MS, and MS-MS to rapidly and accurately elucidate structures of impurities and degradants. In these studies, degradants induced by acid, base, peroxide, and light were profiled using LC-MS and LC-MS-MS methodologies resulting in an LC-MS degradant database which includes information on molecular structures, chromatographic behavior, molecular mass, and MS-MS substructural information. The stressing conditions which may cause drug degradation are utilized to validate the analytical monitoring methods and serve as predictive tools for future formulation and packaging studies. Degradation products formed upon exposure to basic conditions included baccatin III, paclitaxel sidechain methyl ester, 10-deacetylpaclitaxel, and 7-epipaclitaxel. Degradation products formed upon exposure to acidic conditions included 10-deacetylpaclitaxel and the oxetane ring opened product. Treatment with hydrogen peroxide produced only 10-deacetylpaclitaxel. Exposure to high intensity ligh produced a number of degradants. The most abundant photodegradant of paclitaxel corresponded to an isomer which contains a C3-C11 bridge. These methodologies are applicable at any stage of the drug product cycle from discovery through development. This library of paclitaxel degradants provides a foundation for future development work regarding product monitoring, as well as use as a diagnostic tool for new degradation products.

  1. Modeling of closed-loop recycling liquid-liquid chromatography: Analytical solutions and model analysis.

    PubMed

    Kostanyan, Artak E

    2015-08-07

    In closed-loop recycling (CLR) chromatography, the effluent from the outlet of a column is directly returned into the column through the sample feed line and continuously recycled until the required separation is reached. To select optimal operating conditions for the separation of a given feed mixture, an appropriate mathematical description of the process is required. This work is concerned with the analysis of models for the CLR separations. Due to the effect of counteracting mechanisms on separation of solutes, analytical solutions of the models could be helpful to understand and optimize chromatographic processes. The objective of this work was to develop analytical expressions to describe the CLR counter-current (liquid-liquid) chromatography (CCC). The equilibrium dispersion and cell models were used to describe the transport and separation of solutes inside a CLR CCC column. The Laplace transformation is applied to solve the model equations. Several possible CLR chromatography methods for the binary and complex mixture separations are simulated. Copyright © 2015 Elsevier B.V. All rights reserved.

  2. Secondary isotope effects in liquid chromatography behaviour of 2H and 3H labelled solutes and solvents.

    PubMed

    Valleix, Alain; Carrat, Sandrine; Caussignac, Céline; Léonce, Estelle; Tchapla, Alain

    2006-05-26

    The separation of solutes that differ only in the extent of isotopic substitution of their hydrogen atoms, using either mixtures of isotopically non-modified or perdeuterated solvents as mobile phases, is described. The occurrence of a secondary isotope effect is demonstrated in reversed-phase liquid chromatography, which is independent of the nature of the stationary phase (different octadecyl-bonded silicas, an embedded alkylamide-bonded silica, as well as one polymeric stationary phase were tested), and the water content and the nature of organic modifier of the mobile phase. The separation of 24 structurally different isotopologue pairs (apolar compounds and polar compounds with exchangeable or non-exchangeable hydrogen atoms) is examined using reversed-phase liquid chromatography. It is found that the greater the number of isotopically substituted hydrogen atoms in a given organic solute, the better is the separation of a particular isotopologue pair. The single secondary isotope effect is shown to be dependent on the number of isotopic substitutions. The greater the number of these substitutions, the smaller is the single isotope effect. The single secondary isotope effect is higher for aromatic hydrocarbons than for aliphatic hydrocarbons. A secondary isotope effect is also observed in chiral chromatography and normal-phase liquid chromatography, as well as on changing the nature of the substituting isotope, i.e.: tritium instead of deuterium. Thus, we have demonstrated that the total secondary isotopic effect for hydrogen/tritium is higher than for hydrogen/deuterium. This isotope effect involves only the consequences of changes in interactions due to nuclear motions. Overall this study confirms the predominance of hydrophobic effects in retention processes in reversed-phase liquid chromatography. In reversed-phase liquid chromatography, a secondary isotope effect related to mobile phase composition is also observed. The behaviour of deuterium oxide and

  3. Three dimensional liquid chromatography coupling ion exchange chromatography/hydrophobic interaction chromatography/reverse phase chromatography for effective protein separation in top-down proteomics.

    PubMed

    Valeja, Santosh G; Xiu, Lichen; Gregorich, Zachery R; Guner, Huseyin; Jin, Song; Ge, Ying

    2015-01-01

    To address the complexity of the proteome in mass spectrometry (MS)-based top-down proteomics, multidimensional liquid chromatography (MDLC) strategies that can effectively separate proteins with high resolution and automation are highly desirable. Although various MDLC methods that can effectively separate peptides from protein digests exist, very few MDLC strategies, primarily consisting of 2DLC, are available for intact protein separation, which is insufficient to address the complexity of the proteome. We recently demonstrated that hydrophobic interaction chromatography (HIC) utilizing a MS-compatible salt can provide high resolution separation of intact proteins for top-down proteomics. Herein, we have developed a novel 3DLC strategy by coupling HIC with ion exchange chromatography (IEC) and reverse phase chromatography (RPC) for intact protein separation. We demonstrated that a 3D (IEC-HIC-RPC) approach greatly outperformed the conventional 2D IEC-RPC approach. For the same IEC fraction (out of 35 fractions) from a crude HEK 293 cell lysate, a total of 640 proteins were identified in the 3D approach (corresponding to 201 nonredundant proteins) as compared to 47 in the 2D approach, whereas simply prolonging the gradients in RPC in the 2D approach only led to minimal improvement in protein separation and identifications. Therefore, this novel 3DLC method has great potential for effective separation of intact proteins to achieve deep proteome coverage in top-down proteomics.

  4. A Method for the Quantitation of Trace Levels of Dimethyl Sulfoxide in Urine by High Performance Liquid Chromatography

    DTIC Science & Technology

    1989-05-01

    HIGH PERFORMANCE LIQUID CHROMATOGRAPHY by...for the sample cleanup and concentration, followed by separation by reversed phase high performance liquid chromatography . EXPERIMENTAL Materials...DIMETHYL SULFOXIDE IN URINE BY HIGH PERFORMANCE LIQUID CHROMATOGRAPHY 4. AUTHORS (Last name, first name, middle initial. If military, show rank, e.g.

  5. Determination of Dimethyl Sulfoxide (DMSO), Ethanol (ETOH), Formamide (F) and Glycerol/Formal (GF) by High Performance Liquid Chromatography (HPLC)

    DTIC Science & Technology

    1989-01-30

    HIGH PERFORMANCE LIQUID CHROMATOGRAPHY (HPLC...Classification) (U) Determination of Dimethyl Sulfoxide (DMSO), Ethanol, (ETOH), Formamide (F), and Glycerol/ Formal (GF) by High Performance Liquid Chromatography (HPLC...and 5). High performance liquid chromatography (HPLC) was the analytical method of choice for analyzing DMSO, ethanol, formamide and

  6. Determination of 5-Bromo-2’-Deoxyuridine (BrdU) in Well Water by High Performance Liquid Chromatography (HPLC)

    DTIC Science & Technology

    1992-09-01

    HIGH PERFORMANCE LIQUID CHROMATOGRAPHY (HPLC...Securrty Classification) Determination of 5-Bromo-2’-Deoxyuridine (BrdU) in Well Water by High Performance Liquid Chromatography (hPLC) 12. PERSONAL...PLOT OF BrdU STABILITY VERSUS TIME ....................... 10 ii DETERMINATION OF 5-BROMO-2’-DEOXY-URIDINE (BrdU) IN WELL WATER BY HIGH PERFORMANCE LIQUID CHROMATOGRAPHY

  7. Identification of New Metabolites of Bacterial Transformation of Indole by Gas Chromatography-Mass Spectrometry and High Performance Liquid Chromatography

    PubMed Central

    Arora, Pankaj Kumar

    2014-01-01

    Arthrobacter sp. SPG transformed indole completely in the presence of an additional carbon source. High performance liquid chromatography and gas chromatography-mass spectrometry detected indole-3-acetic acid, indole-3-glyoxylic acid, and indole-3-aldehyde as biotransformation products. This is the first report of the formation of indole-3-acetic acid, indole-3-glyoxylic acid, and indole-3-aldehyde from indole by any bacterium. PMID:25548566

  8. Microfluidic liquid chromatography system for proteomic applications and biomarker screening.

    PubMed

    Lazar, Iulia M; Trisiripisal, Phichet; Sarvaiya, Hetal A

    2006-08-01

    A microfluidic liquid chromatography (LC) system for proteomic investigations that integrates all the necessary components for stand-alone operation, i.e., pump, valve, separation column, and electrospray interface, is described in this paper. The overall size of the LC device is small enough to enable the integration of two fully functional separation systems on a 3 in. x 1 in. glass microchip. A multichannel architecture that uses electroosmotic pumping principles provides the necessary functionality for eluent propulsion and sample valving. The flow rates generated within these chips are fully consistent with the requirements of nano-LC platforms that are routinely used in proteomic applications. The microfluidic device was evaluated for the analysis of a protein digest obtained from the MCF7 breast cancer cell line. The cytosolic protein extract was processed according to a shotgun protocol, and after tryptic digestion and prefractionation using strong cation exchange chromatography (SCX), selected sample subfractions were analyzed with conventional and microfluidic LC platforms. Using similar experimental conditions, the performance of the microchip LC was comparable to that obtained with benchtop instrumentation, providing an overlap of 75% in proteins that were identified by more than two unique peptides. The microfluidic LC analysis of a protein-rich SCX fraction enabled the confident identification of 77 proteins by using conventional data filtering parameters, of 39 proteins with p < 0.001, and of 5 proteins that are known to be cancer-specific biomarkers, demonstrating thus the potential applicability of these chips for future high-throughput biomarker screening applications.

  9. Extensive database of liquid phase diffusion coefficients of some frequently used test molecules in reversed-phase liquid chromatography and hydrophilic interaction liquid chromatography.

    PubMed

    Song, Huiying; Vanderheyden, Yoachim; Adams, Erwin; Desmet, Gert; Cabooter, Deirdre

    2016-07-15

    Diffusion plays an important role in all aspects of band broadening in chromatography. An accurate knowledge of molecular diffusion coefficients in different mobile phases is therefore crucial in fundamental column performance studies. Correlations available in literature, such as the Wilke-Chang equation, can provide good approximations of molecular diffusion under reversed-phase conditions. However, these correlations have been demonstrated to be less accurate for mobile phases containing a large percentage of acetonitrile, as is the case in hydrophilic interaction liquid chromatography. A database of experimentally measured molecular diffusion coefficients of some 45 polar and apolar compounds that are frequently used as test molecules under hydrophilic interaction liquid chromatography and reversed-phase conditions is therefore presented. Special attention is given to diffusion coefficients of polar compounds obtained in large percentages of acetonitrile (>90%). The effect of the buffer concentration (5-10mM ammonium acetate) on the obtained diffusion coefficients is investigated and is demonstrated to mainly influence the molecular diffusion of charged molecules. Diffusion coefficients are measured using the Taylor-Aris method and hence deduced from the peak broadening of a solute when flowing through a long open tube. The validity of the set-up employed for the measurement of the diffusion coefficients is demonstrated by ruling out the occurrence of longitudinal diffusion, secondary flow interactions and extra-column effects, while it is also shown that radial equilibration in the 15m long capillary is effective.

  10. Isolation of Xanthomegnin from Penicillium viridicatum by Preparative High-Pressure Liquid Chromatography

    PubMed Central

    Peterson, R. E.; Grove, M. D.

    1983-01-01

    A method was developed for the production and purification of xanthomegnin from Penicillium viridicatum (NRRL 6430) cultured on rice at 15°C for 29 days. Liquid-liquid extraction followed by high-pressure liquid chromatography afforded 440 mg of crystalline xanthomegnin per kg of rice. PMID:6881966

  11. The use of online heart-cutting high-performance liquid chromatography coupled with linear ion trap mass spectrometry in the identification of impurities in vidarabine monophosphate.

    PubMed

    Wang, Hang; Xu, Tongzhou; Yuan, Jiaojian

    2017-04-01

    It is difficult to identify unknown impurities in nucleotide analogues by mass spectrometry because mass-spectrometry-incompatible mobile phases need to be used to separate the major ingredient from impurities. In this study, vidarabine monophosphate was selected, and unknown impurities were identified by online heart-cutting two-dimensional high-performance liquid chromatography and linear ion trap mass spectrometry. The one-dimensional reversed-phase column was filled with a mobile phase containing nonvolatile salt. In two-dimensional high-performance liquid chromatography, we used an Acclaim Q1 column with volatile salt, and the detection wavelength was 260 nm. The mass spectrum was scanned in positive- and negative-ion mode. The online heart-cutting and online demineralization technique ensured that the mobile phase was compatible with mass spectrometry; seven impurities were identified by MS(2) and MS(3) fragments. The mass fragmentation patterns of these impurities were investigated. The two isomers were semiprepared and complemented by nuclear magnetic resonance. The results were further compared with those of normal-phase high-performance liquid chromatography with mass spectrometry. The online heart-cutting two-dimensional high-performance liquid chromatography with mass spectrometry was superior in identifying more impurities. The method solves the problem of incompatibility between the mobile phase and mass spectrometry, so it is suitable for identifying unknown impurities. This method may also be used for investigating impurities in other nucleotide analogues. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Isopropylammonium Formate as a Mobile Phase Modifier for Liquid Chromatography

    PubMed Central

    Collins, Matthew P.; Zhou, Ling; Camp, Suzanne E.; Danielson, Neil D.

    2012-01-01

    Isopropylammonium formate (IPAF), a new alkylammonium formate (AAF) room temperature ionic liquid, has been synthesized from isopropylamine and formic acid and characterized as an organic solvent mobile phase replacement for reversed-phase liquid chromatography (LC). Characterization of IPAF solvent properties in water such as pH, conductivity, and viscosity, as well as its synthesis, is described. The LC polarity (P′) and the solvent strength (S) parameters are determined to be 6.0 and 2.4, respectively, similar to those same parameters for methanol and acetonitrile. Application of this RTIL is demonstrated as an organic solvent replacement for reversed-phase LC to separate a test mixture of niacinamide, acetophenone and p-nitroaniline. The van Deemter plot profile for several columns of different dimensions, particle size, pore size and stationary phase are compared using an IPAF–water mobile phase. At flow rates above 2 mL/min, on-line mixing of the viscous IPAF with water appears not to be uniform. A flattening of the van Deemter profile is noted for particularly short (50 mm) wide bore (4.6 mm) columns packed with larger particles (10 µm). Small particle longer columns likely facilitated mixing at the beginning of the column generating typical linearly increasing van Deemeter curves. IPAF has been further shown as a function of temperature to be a non-denaturing modifier solvent for the separation of the protein cytochrome c from tryptophan compared to methanol. This is important to show, because the semi-preparative separation of native proteins using AAF mobile phases is the long-term goal of this research program. PMID:22718743

  13. Strategies for metabolite profiling based on liquid chromatography.

    PubMed

    Saurina, Javier; Sentellas, Sonia

    2017-02-15

    This paper aims at covering the principal strategies based on liquid chromatography (LC) for metabolite profiling in the field of drug discovery and development. The identification of metabolites generated in the organism is an important task during the early stages of preclinical research to define the most proper strategy for optimizing, adjusting metabolic clearance and minimizing bioactivation. An early assessment of the metabolite profile may be critical since metabolites can contribute to pharmacological and/or toxicological effects. The study of metabolites first involves their synthesis/generation and their further characterization and structural elucidation. For such a purpose, both in vitro and in vivo methods are commonly used for the generation of the corresponding metabolites. Next, analytical methods are used to tackle identification and characterization studies. Among the arsenal of techniques available in our labs, we will focus on LC, especially coupled to mass spectrometry (LC-MS), as one of the most powerful approaches for metabolite identification, characterization and quantification. Here, the topic of metabolite profiling based on LC will be addressed and representative examples of different possibilities will be discussed.

  14. A Fiber Optic Colorimeter For Liquid Phase Chromatography Of Aminoacids

    NASA Astrophysics Data System (ADS)

    Donati, S.; Tambosso, T.

    1989-01-01

    Liquid phase chromatography is a well known technique routinely used in analytical chemistry for assays and measurements of aminoacids 1,2. Basically, the solution is pumped at high pressure in a long capillary tube (the chromatographic column) to fraction out the constituents, is mixed to a suitable reactant (usually ninhydrine) so as to develop a spectral absorbance, and is finally analyzed in a flow cell by a colorimeter. With ninhydrine, the reaction product is DIDA (diketo-hydrindilidene-diketolhydrin diamine) which exhibits absorbance peaks at 440 nm (blue) and 570 nm (yellow) in a proportion dependent on the specific aminoacid (Fig. 1), while the amplitude of peaks is proportional to the aminoacid concentration in view of Lambert-Beer law. Besides the two measurement channels of absorbance, either of which or the sum of which is taken as the output signal, a third channel at the wavelength 690 nm at which DIDA is transparent (Ar = 0), is used internally as the reference to the first two. Thus, the colorimeter is actually a spectrophotometer with two fixed-wavelength channels, each referenced in wavelength. In this paper, we report on the design and engineering of a colorimeter aimed to medium/high performances, high reliability and low cost. Use of fiber optics as the beamsplitter of the optical channels is shown to give substantial advantages.

  15. New method for determining total dietary fiber by liquid chromatography.

    PubMed

    Ohkuma, K; Matsuda, I; Katta, Y; Tsuji, K; Ohkuma, K; Matsuda, I; Katta, Y; Tsuji, K

    2000-01-01

    The molecular weight limit of water-soluble dietary fiber (SDF) determined by the Prosky method was studied by liquid chromatography (LC). It was confirmed that only SDF with an average degree of polymerization of 12 or higher can be determined by the Prosky method. Total dietary fiber (TDF) was determined by 2 additional methods using LC. In the first method, the total quantity of insoluble dietary fiber (IDF) and high molecular weight SDF (HMSDF) was determined according to the modified Prosky method (MES-TRIS buffer-based). The quantitatively collected final filtrate was analyzed by LC for the quantity of low molecular weight SDF (LMSDF), and the 2 quantities were totaled to obtain TDF. TDF values thus determined for rice, polished or unpolished, soybean flour, and pressed barley were higher than those determined by the Prosky method by approximately 6, 3.5, and 3.5%, respectively. In the second method, direct determination by LC analysis was done on samples after enzymatic treatment according to the Prosky method. Results showed that the determination of LMSDF, in particular, was highly accurate and more effective. In both of these methods, the quantity of LMSDF was determined from its chromatographic peak area ratio to glucose as an internal standard, which was produced by hydrolysis.

  16. Determination of patulin in apple juice by liquid chromatography.

    PubMed

    Iha, Maria Helena; Sabino, Myrna

    2006-01-01

    A method was developed and validated in-house for the determination of patulin (PAT), a toxic mold metabolite, in apple juice. The sample was extracted with ethyl acetate-hexane and analyzed by liquid chromatography equipped with a C18 column and diode array detector. The mobile phase used for the quantification was water-ethanol, at a flow rate of 0.5 mL/min. The method showed a mean recovery of 84.8%, the relative standard deviation obtained in the precision study was <7.7%, the quantification and detection limits were 7 and 3 microg/L, respectively, and the linear range for PAT in apple juice was 2.6-650 microg/L. The ruggedness was evaluated by an intralaboratory experiment, in which 5 factors were studied, and only one was found to influence the observed results. The developed method is fast, practical, and simple; the solvents (except hexane) and reagents used were nontoxic. The results of the validation confirmed the efficiency of the method, which is sensitive enough to be used in studies required to quantify PAT in apple juice.

  17. Determination of sulfite in foods by headspace liquid chromatography

    SciTech Connect

    Lawrence, J.F.; Chadha, R.K.

    1988-01-01

    Sulfite was determined in a variety of foods by liquid chromatography (LC) after the samples were mixed with a solution containing mannitol, FeSO/sub 4/, and Na/sub 2/HPO/sub 4/, adjusted to pH 11, and left to stand for 15 min at room temperature. An aliquot of the mixture was placed in a headspace vial and mixed with 50% H/sub 3/PO/sub 4/. After 15 min, a portion of the headspace was removed with a syringe containing LC mobile phase without acetonitrile. The syringe was shaken and an aliquot of the solution was analyzed on an anion exchange column with a mobile phase of 0.03M methane sulfonate (pH 10.8) containing 5% acetonitrile. Sulfite was detected amperometrically (glassy carbon electrode) at +0.7 V. The method was successfully compared to the FDA-modified Monier-Williams procedure for a variety of foods. Minimum detectable levels were about 1 ..mu..g/g, based on a 15 g sample.

  18. Analysis of Cordyceps by multi-column liquid chromatography.

    PubMed

    Qian, Zhengming; Li, Shaoping

    2017-03-01

    Cordyceps is a famous traditional Chinese medicine (TCM) that has been used in China for hundreds of years. In the present study a multi-column liquid chromatography (MC-LC) system was developed for the qualitative analysis of macromolecules and micromolecules in Cordyceps. The MC-LC system includes a size exclusion pre-column, a size exclusion column (SEC) and a reversed phase column (RP) which were controlled by column-switching valves. The sample was separated by the size exclusion pre-column into two fractions (macromolecules and micromolecules). These fractions were further separated on SEC and RP columns, respectively. A diode array detector (DAD) and a mass spectrometer (MS) were used to detect the components. This MC-LC method was utilized for analysis of Cordyceps samples. Two macromolecular peaks and 15 micromolecular peaks were found in Cordyceps, and 11 of the micromolecular peaks were identified as adenosine-5'-monophosphate (AMP), phenylalanine, uridine, hypoxanthine, inosine, guanine, guanosine, deoxyadenosine-5'-monophosphate (dAMP), adenosine, adenine and cordycepin (or its isomer). This method is useful for quality control of Cordyceps.

  19. Gradient chromatofocusing high-performance liquid chromatography. II. Theoretical aspects.

    PubMed

    Liu, Y; Anderson, D J

    1997-02-21

    This article is Part II of a series describing a newly-developed gradient chromatofocusing high-performance liquid chromatography (HPLC) technique. Theoretical aspects of the technique are discussed. In gradient chromatofocusing, the column pH gradient with respect to column distance can be varied without necessarily affecting the outlet pH gradient with respect to time. Factors influencing the value of the slope of the column pH gradient are identified through derived equations and a computer simulation model. A newly-identified parameter is introduced, column travel time, which can be uniquely varied in gradient chromatofocusing. Experiments show increased conversion of fibrinogen to denatured forms with increased column travel time. Another unique aspect of gradient chromatofocusing is that the mobile phase buffer concentration can be manipulated without necessarily affecting the outlet pH gradient slope, giving the technique expanded versatility for optimizing the separation. In the present work, the pIapparent for fibrinogen is found to increase with increased mobile phase buffer concentration.

  20. Determination of neomycin in animal tissues by liquid chromatography.

    PubMed

    Reid, J A; MacNeil, J D

    1999-01-01

    Tissue samples are digested under hot alkaline conditions after initial conditioning at room temperature with phosphate-buffered saline. The cooled digest is deproteinated with concentrated perchloric acid. After centrifugation and pH adjustment, the clear supernatant is applied to an ion-exchange cartridge, and after the cartridge is washed, the neomycin is eluted with dilute perchloric acid. This eluate is derivatized with 9-fluorenylmethyl chloroformate prior to liquid chromatography using a wide-pore spherical silica C4 column and fluorescence detection. Recovery and repeatability are calculated from tissue extract standard calibration curves produced from the same assay. Recoveries ranged from 80 to 120% for fortifications of 0.25-1.00 mg/kg for muscle tissue and from 80 to 100% for fortifications of 0.50-10.0 mg/kg for kidney tissue. Limits of quantitation were 0.25 and 0.50 mg/kg, respectively, for muscle and kidney tissues. Limits of detection were 0.125 and 0.20 mg/kg, respectively, for muscle and kidney tissues.

  1. Gas-liquid chromatography of fecal neutral steriods.

    PubMed

    Gerhardt, K O; Gehrke, C W; Rogers, I T; Flynn, M A; Hentges, D J

    1977-05-21

    A method is described for the analysis of fecal neutral steriods with a dual-column gas-liquid chromatography (GLC) system. After saponification of the fecal slurry, the neutral steroids were extracted with hexane. The GLC separation of the compounds and quantitation were achieved by simultaneous injection of the derivatized and derivatized aliquots of the extract onto dual colmuns under identical conditions. The neutral steroids of interest were than identified by matching the retention times with those of known standards, and identification was confirmed by use of an interfaced GLC high-resolution mass spectrometry system. The detection limit was 0.003 mg of steroid/g of fecal slurry. The pricision of the method is illustrated by a relative standard diviation of 2-10% and a recovery of neutral steroids from 73-96%. The method was applied to the determination of fecal neutral steroids in a "High protein diet in colon cancer study". A considerably larger level of coprostanone than of coprostanol was observed. Data on neutral steroids in fecal samples from subjects on different diets are the subject of a separate publication.

  2. Are analysts doing method validation in liquid chromatography?

    PubMed

    Ruiz-Angel, M J; García-Alvarez-Coque, M C; Berthod, A; Carda-Broch, S

    2014-08-01

    Method validation is being applied in the reported analytical methods for decades. Even before this protocol was defined, authors already somehow validated their methods without full awareness. They wished to assure the quality of their work. Validation is an applied approach to verify that a method is suitable and rugged enough to function as a quality control tool in different locations and times. The performance parameters and statistical protocols followed throughout a validation study vary with the source of guidelines. Before single laboratory validation, an analytical method should be fully developed and optimized. The purpose of the validation is to confirm performance parameters that are determined during method development, and it should provide information on how the method will perform under routine use. An unstable method may require re-validation. Further method development and optimization will be needed if validation results do not meet the accepted performance standards. When possible, the validation protocol should also be conducted as a collaborative study by multiple laboratories, on different instruments, reagents, and standards. At this point, it would be interesting to know how people are validating their methods. Are they evaluating all defined validation parameters? Are they indicating the followed guidelines? Is re-validation really currently used? Is validation performed by a single laboratory, or is it a collaborative work by several laboratories? Is it an evolving discipline? In this survey, we will try to answer these questions focused to the field of liquid chromatography.

  3. Chromatographic analysis of olopatadine in hydrophilic interaction liquid chromatography.

    PubMed

    Maksić, Jelena; Jovanović, Marko; Rakić, Tijana; Popović, Igor; Ivanović, Darko; Jančić-Stojanović, Biljana

    2015-01-01

    In this paper, chromatographic analysis of active substance olopatadine hydrochloride, which is used in eye drops as antihistaminic agent, and its impurity E isomer by hydrophilic interaction liquid chromatography (HILIC) and application of design of experiments (DoE) methodology are presented. In addition, benzalkonium chloride is very often used as a preservative in eye drops. Therefore, the evaluation of its chromatographic behavior in HILIC was carried out as well. In order to estimate chromatographic behavior and set optimal chromatographic conditions, DoE methodology was applied. After the selection of important chromatographic factors, Box-Behnken design was utilized, and on the basis of the obtained models factor effects were examined. Then, multi-objective robust optimization is performed aiming to obtain chromatographic conditions that comply with several quality criteria simultaneously: adequate and robust separation of critical peak pair and maximum retention of the first eluting peak. The optimal conditions are identified by using grid point search methodology. The experimental verification confirmed the adequacy of the defined optimal conditions. Finally, under optimal chromatographic conditions, the method was validated and applicability of the proposed method was confirmed. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  4. Separation of microcystins and nodularins by ultra performance liquid chromatography.

    PubMed

    Spoof, Lisa; Neffling, Milla-Riina; Meriluoto, Jussi

    2009-11-15

    Four ultra performance liquid chromatography (UPLC) columns with different reversed-phase characteristics were tested in the chromatographic separation of 10 microcystins and three nodularins, cyanobacterial peptide toxins. The columns had been designed by the manufacturer to withstand the ultra-high pressure generated by sub-2microm stationary phase particles and the Waters ACQUITY UPLC system in ultra-fast separations. The gradient mobile phase consisted of water and acetonitrile, both acidified with trifluoroacetic acid, with three gradient rise times: 1, 1.5 and 2min. The UV detection of the toxins was performed by a photodiode array detector. The chromatographic performance was evaluated both visually and by calculating chromatographic parameters such as capacity factor, resolution, peak width at half height, selectivity and peak asymmetry. The best chromatographic performance as judged by visual inspection was given by the ACQUITY BEH Shield RP18 and ACQUITY BEH Phenyl columns. The BEH Shield RP18 column showed excellent selectivity and resolution of chosen peak pairs considered as critical. A further advantage of the UPLC system was the high sample throughput with a total analysis time of 3.12min (injection-to-injection) equalling to 461 separations per 24h.

  5. Liquid chromatography of hydrocarbonaeous quaternary amines on cyclodextrin bonded silica

    USGS Publications Warehouse

    Abidi, S.L.

    1986-01-01

    Mixtures of n-alkylbenzyldimethylammonium chloride (ABDAC) were resolved into homologous components by high-performance liquid chromatography (HPLC) with a cyclodextrin-bonded silica stationary phase. With a few exceptions, results from this study are similar to those obtained from traditional reversed-phase HPLC. It was found that the presence of electrolytes in aqueous mobile phases is not a critical factor in determining the success of HPLC separation. Under normal HPLC conditions, a mobile phase consisting of either methanol–water (50:50) or acetonitrile–water (30:70) was employed for obtaining adequate resolution of the quaternary ammonium mixtures. Although the percent organic modifier–water profiles were similar to those in previous studies with these compounds, resolution (R) and selectivity (α) parameters were found to be quite susceptible to changes in the mobile phase solvent composition. The retention behavior of the cationic analytes in the homologous series is consistent with the hydrophobic-interaction concept proposed for the retention mechanism via dominant inclusion complex formation. Several electrolytes were chosen for a study of the counter ion effect on the chromatographic characteristics of ABDAC components. Among the electrolytes examined, the perchlorate ion was found most likely to act as an ion-pairing counter ion for ammonium cations in the HPLC system studied. A correlation study established linear relationships between the chain length of ABDAC and the logarithmic capacity factor (k2). The analytical utility of the HPLC method was demonstrated by the analysis of various unknown mixtures.

  6. [Detecting methamphetamine and amphetamine with high performance liquid chromatography].

    PubMed

    Fu, Qiang; Liao, Lin-chuan; Chen, Li-li; Yan, You-yi; Yang, Lin; Hou, Jun-hong; Chen, Yu

    2007-11-01

    To establish a method for detecting methamphetamine (MA) and amphetamine (AMP) with high performance liquid chromatography (HPLC). Both MA and AMP were isolated on a C18 column and methanol-phosphate buffer (0.015 mol/L NaH2PO4) at a flow rate of 1.0 mL/min. The 190-360 nm ultraviolet spectrum was examined, with 215 nm as the detection wavelength. The MA and AMP were well isolated and determined. The MA determined by the HPLC had good linearity with the real value at the range from 1.4 to 270 microg/mL (R2=1), with an average recovery rate of 102.5%. The detectable Limit was 0.73 microg/mL (S/N > or =3). The AMP determined by the HPLC had a good linearity with the real value at the range from 0.9 to 580 microg/mL (R2 = 0.9999), with an average recovery rate of 101.7%. The detectable limit was 0.52 microg/mL (S/N > or =3). Both intra-day and inter-day precisions expressed by relative standard deviations of the MA and AMP were less than 2.4%. This is a simple, rapid and accurate method for detecting methamphetamine and amphetamine.

  7. Molecular simulation studies of reversed-phase liquid chromatography.

    PubMed

    Lindsey, Rebecca K; Rafferty, Jake L; Eggimann, Becky L; Siepmann, J Ilja; Schure, Mark R

    2013-04-26

    Over the past 20 years, molecular simulation methods have been applied to the modeling of reversed-phase liquid chromatography (RPLC). The purpose of these simulations was to provide a molecular-level understanding of: (i) the structure and dynamics of the bonded phase and its interface with the mobile phase, (ii) the interactions of analytes with the bonded phase, and (iii) the retention mechanism for different analytes. However, the investigation of chromatographic systems poses significant challenges for simulations with respect to the accuracy of the molecular mechanics force fields and the efficiency of the sampling algorithms. This review discusses a number of aspects concerning molecular simulation studies of RPLC systems including the historical development of the subject, the background needed to understand the two prevalent techniques, molecular dynamics (MD) and Monte Carlo (MC) methods, and the wealth of insight provided by these simulations. Examples from the literature employing MD approaches and from the authors' laboratory using MC methods are discussed. The former can provide information on chain dynamics and transport properties, whereas the latter techniques are uniquely suited for the investigation of phase and sorption equilibria that underly RPLC retention, and both can be used to elucidate the bonded-chain conformations and solvent distributions. Copyright © 2013 Elsevier B.V. All rights reserved.

  8. Hydrophilic interaction liquid chromatography with alcohol as a weak eluent.

    PubMed

    Liu, Min; Ostovic, Judy; Chen, Emily X; Cauchon, Nina

    2009-03-20

    There has been a significant increase of interest in polar compound separation by hydrophilic interaction liquid chromatography (HILIC), in which acetonitrile is mostly used as a weak eluent. Although replacing acetonitrile with alcohols as organic modifiers has been previously reported, the separation mechanism was poorly understood. In this paper we explored the separation mechanism through the method development for the analysis of the trace amounts of polar and basic hydrazines, which were genotoxic in nature. Separation parameters such as the type and concentration of alcohol, acid modifier, and buffer in mobile phase as well as the choice of stationary phase and column temperature were studied. The data indicated that both electrostatic and hydrophilic interactions contributed to the retention and separation of the hydrazines. The results presented here provide insight into the adjustment of the retention and separation of analytes in HILIC mode with alcohol as a weak eluent. The optimized HILIC method coupled with chemiluminescent nitrogen detection (CLND) is simple and sensitive (reporting limit at 0.02%) and was applied to simultaneous analysis of hydrazine and 1,1-dimethylhydrazine in a pharmaceutical intermediate.

  9. Simultaneous determination of cyclodol and diprazin by thin layer chromatography and high performance liquid chromatography.

    PubMed

    Makharadze, R; Adeishvili, L; Chelidze, T; Imnadze, N; Nizharadze, N

    2009-11-01

    Ciklodol (trihexyphenidil)--the central and peripheral m-cholinoblocker is currently used with other antipsychotic drugs such as phenotiazines and tricycle antidepressants. For the purpose of simultaneous determination of ciklodol and diprazine, were selected two methods of analysis: Thin Layer Chromatography (TLC) and High Performance Liquid Chromatography (HPLC). During development of TLC method was studied the 10 visualizing system and 24 mobile systems. For individual or simultaneous determination of ciklodol and diprazine were recommended the following solvents' systems: 1. Toluene-acetone-ethanole-25%NH(4)OH (45:45: 7.5:2.5), 2. Hexane-ethyl acetate (15:5), 3. Chloroform-heptene-25%NH(4)OH (16:3:3), 4. Ethylacetate-hexane (10:10), 5. Acetonitrile-metanol (10:10) and 6.Heptene-chloroform-ethanol-25% NH(4)OH (5:10:3:1). As visualizing systems were chosen: Iodine vapors, blacklight (UV254) and reagent of FNP. Reagent of FNP gives colored spot just with diprazine and it is also could be used for separation of both objects in simultaneous analysis. Developed HPLC method of simultaneous determination of ciklodol and diprazine: like mobile phase is recommended: Acetonitril- 0.05M KH(2)PO4 (55:45) (v/v) +H(3)PO(4) (pH3.5), column EC250 x 4.6mm, with solid phase Nucleosil, flow rate 1ml/min, sample volume 40 microl. In given conditions, the retention time of ciklodol is 6.005min and diprazine 7.227min. Developed method of simultaneous determination and separation of ciklodol and diprazine in respective mixtures could be successfully applied as in the pharmaceutical, as well in the chemical-toxicological laboratories.

  10. Determination of triazine herbicides in juice samples by microwave-assisted ionic liquid/ionic liquid dispersive liquid-liquid microextraction coupled with high-performance liquid chromatography.

    PubMed

    Su, Rui; Li, Dan; Wu, Lijie; Han, Jing; Lian, Wenhui; Wang, Keren; Yang, Hongmei

    2017-07-01

    A novel microextraction method, termed microwave-assisted ionic liquid/ionic liquid dispersive liquid-liquid microextraction, has been developed for the rapid enrichment and analysis of triazine herbicides in fruit juice samples by high-performance liquid chromatography. Instead of using hazardous organic solvents, two kinds of ionic liquids, a hydrophobic ionic liquid (1-hexyl-3-methylimidazolium hexafluorophosphate) and a hydrophilic ionic liquid (1-butyl-3-methylimidazolium tetrafluoroborate), were used as the extraction solvent and dispersion agent, respectively, in this method. The extraction procedure was induced by the formation of cloudy solution, which was composed of fine drops of 1-hexyl-3-methylimidazolium hexafluorophosphate dispersed entirely into sample solution with the help of 1-butyl-3-methylimidazolium tetrafluoroborate. In addition, an ion-pairing agent (NH4 PF6 ) was introduced to improve recoveries of the ionic liquid phase. Several experimental parameters that might affect the extraction efficiency were investigated. Under the optimum experimental conditions, the linearity for determining the analytes was in the range of 5.00-250.00 μg/L, with the correlation coefficients of 0.9982-0.9997. The practical application of this effective and green method is demonstrated by the successful analysis of triazine herbicides in four juice samples, with satisfactory recoveries (76.7-105.7%) and relative standard deviations (lower than 6.6%). In general, this method is fast, effective, and robust to determine triazine herbicides in juice samples. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Simultaneous analysis for water- and fat-soluble vitamins by a novel single chromatography technique unifying supercritical fluid chromatography and liquid chromatography.

    PubMed

    Taguchi, Kaori; Fukusaki, Eiichiro; Bamba, Takeshi

    2014-10-03

    Chromatography techniques usually use a single state in the mobile phase, such as liquid, gas, or supercritical fluid. Chromatographers manage one of these techniques for their purpose but are sometimes required to use multiple methods, or even worse, multiple techniques when the target compounds have a wide range of chemical properties. To overcome this challenge, we developed a single method covering a diverse compound range by means of a "unified" chromatography which completely bridges supercritical fluid chromatography and liquid chromatography. In our method, the phase state was continuously changed in the following order; supercritical, subcritical and liquid. Moreover, the gradient of the mobile phase starting at almost 100% CO2 was replaced with 100% methanol at the end completely. As a result, this approach achieved further extension of the polarity range of the mobile phase in a single run, and successfully enabled the simultaneous analysis of fat- and water-soluble vitamins with a wide logP range of -2.11 to 10.12. Furthermore, the 17 vitamins were exceptionally separated in 4min. Our results indicated that the use of dense CO2 and the replacement of CO2 by methanol are practical approaches in unified chromatography covering diverse compounds. Additionally, this is a first report to apply the novel approach to unified chromatography, and can open another door for diverse compound analysis in a single chromatographic technique with single injection, single column and single system.

  12. Simultaneous analysis of carotenoids and tocopherols in botanical species using one step solid-liquid extraction followed by high performance liquid chromatography.

    PubMed

    Valdivielso, Izaskun; Bustamante, María Ángeles; Ruiz de Gordoa, Juan Carlos; Nájera, Ana Isabel; de Renobales, Mertxe; Barron, Luis Javier R

    2015-04-15

    Carotenoids and tocopherols from botanical species abundant in Atlantic mountain grasslands were simultaneously extracted using one-step solid-liquid phase. A single n-hexane/2-propanol extract containing both types of compounds was injected twice under two different sets of HPLC conditions to separate the tocopherols by normal-phase chromatography and carotenoids by reverse-phase mode. The method allowed reproducible quantification in plant samples of very low amounts of α-, β-, γ- and δ-tocopherols (LOD from 0.0379 to 0.0720 μg g(-1) DM) and over 15 different xanthophylls and carotene isomers. The simplified one-step extraction without saponification significantly increased the recovery of tocopherols and carotenoids, thereby enabling the determination of α-tocopherol acetate in plant samples. The two different sets of chromatographic analysis provided near baseline separation of individual compounds without interference from other lipid compounds extracted from plants, and a very sensitive and accurate detection of tocopherols and carotenoids. The detection of minor individual components in botanical species from grasslands is nowadays of high interest in searching for biomarkers for foods derived from grazing animals. Copyright © 2014 Elsevier Ltd. All rights reserved.

  13. How to separate ionic liquids: use of hydrophilic interaction liquid chromatography and mixed mode phases.

    PubMed

    Lamouroux, C; Foglia, G; Le Rouzo, G

    2011-05-20

    This chromatographic study deals with the development of a convenient and versatile method to separate Room Temperature Ionic Liquids. Different modes of chromatography were studied. The study attempts to answer the following question: "what were the most important interactions for the separation of ionic liquids?". The results show that the essential interactions to assure a good retention of RTILs are the ionic ones and that hydrophobic interactions play a role in the selectivity of the separation. The separation of five imidazolium salt with a traditional diol columns in Hydrophilic Interaction Chromatography (HILIC) was demonstrated. It shows that neutral diol grafted column allows an important retention that we assume is due to the capability of diol to develop a thick layer of water. Furthermore, stationary phase based on mixed interaction associating ion exchange and hydrophobic properties were studied. Firstly, it will be argued that it is possible to separate RTILs with a convenient retention and resolution according to a reverse phase elution with the Primesep columns made of a brush type long alkyl chain with an embedded negatively charged functional group. Secondly, a sucessful separation of RTILs in HILIC mode with a mixed phase column containing a cationic exchanger and a hydrophobic octyl chain length will be demonstrated.

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

    PubMed

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

    2015-07-24

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

  15. Improved solvent extraction procedure and high-performance liquid chromatography-evaporative light-scattering detector method for analysis of polar lipids from dairy materials.

    PubMed

    Le, Thien Trung; Miocinovic, Jelena; Nguyen, Tuyet Mai; Rombaut, Roeland; van Camp, John; Dewettinck, Koen

    2011-10-12

    A normal-phase high-performance liquid chromatography-evaporative light-scattering detector method employing dichloromethane, methanol, and acetic acid/triethylamine buffer as the mobile phase was developed for analysis of polar lipids (PLs). This method was applicable for analysis of PLs from both dairy materials and soy lecithin. All of the PLs of interest such as glycolipids, phospholipids, and sphingomyelin were well separated with a total run time of 22.5 min and without necessitating the removal of neutral lipids beforehand. Peak retention times were stable, and the method was reproducible. In this study, a modified method of using solvents for extraction of PLs from dairy matrices was also investigated. The modified method offered higher extraction efficiency, consumed less time, and in some cases saved solvent use.

  16. Preparation and application of methylcalix[4]resorcinarene-bonded silica particles as chiral stationary phase in high-performance liquid chromatography.

    PubMed

    Tan, Huey Min; Soh, Shu Fang; Zhao, Jia; Yong, E L; Gong, Yinhan

    2011-01-01

    Two new types of methylcalix[4]resorcinarene-bonded stationary phases, (3-(C-methylcalix[4]resorcinarene)-2-hydroxypropoxy)-propylsilyl-appended silica particles (MCR-HPS) and bromoacetate-substituted MCR-HPS particles (BAMCR-HPS), have been synthesized and used as chiral stationary phases for high-performance liquid chromatography (HPLC) for the first time. The synthetic stationary phases are characterized by means of elemental analysis and Fourier-transform infrared spectroscopy. The chromatographic behavior of MCR-HPS and BAMCR-HPS was studied with several disubstituted benzenes and some chiral drug compounds under both normal phase and reversed-phase conditions. The results show that MCR-HPS has excellent selectivity for the separation of aromatic positional isomers and BAMCR-HPS exhibits excellent performance for separation of enantiomers of chiral compounds.

  17. Electrochemically modulated liquid chromatography: Theoretical investigations and applications from the perspectives of chromatography and interfacial electrochemistry

    SciTech Connect

    Keller, David W.

    2005-01-01

    Electrochemically modulated liquid chromatography (EMLC) employs a conductive material as both a stationary phase for chromatographic separations and as a working electrode for performing electrochemistry experiments. This dual functionality gives EMLC the capacity to manipulate chromatographic separations by changing the potential applied (Eapp) to the stationary phase with respect to an external reference. The ability to monitor retention as a function of Eapp provides a means to chromatographically monitor electrosorption processes at solid-liquid interfaces. In this dissertation, the retention mechanism for EMLC is examined from the perspective of electrical double layer theory and interfacial thermodynamics. From the chromatographic data, it is possible to determine the interfacial excess (Λ) of a solute and changes in interfacial tension (dγ) as a function of both Eapp and the supporting electrolyte concentration. Taken together, these two experimentally manipulated parameters can be examined within the context of the Gibbs adsorption equation to delineate the contribution of a variety of interfacial properties, including the charge of solute on the stationary phase and the potential of zero charge (PZC), to the mechanism behind EMLC-based retention. The chromatographic probing of interfacial phenomena is complemented by electroanalytical experiments that exploit the ability to monitor the electronic current flowing through an EMLC column. Cyclic voltammetry and chronoamperometry of an EMLC column are used to determine the electronic performance characteristics of an EMLC column. An electrochemical flow injection analysis of a column is provided in which the current required to maintain a constant Eapp is monitored and provides a way to examine the influence that acetonitrile and supporting electrolyte composition, flow rate, column backpressure, and ionic strength have on the structure of electrified interfaces.

  18. Determination of Aspartame, Caffeine, Saccharin, and Benzoic Acid in Beverages by High Performance Liquid Chromatography.

    ERIC Educational Resources Information Center

    Delaney, Michael F.; And Others

    1985-01-01

    Describes a simple and reliable new quantitative analysis experiment using liquid chromatography for the determinaiton of caffeine, saccharin, and sodium benzoate in beverages. Background information, procedures used, and typical results obtained are provided. (JN)

  19. HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY OF SELECTED ORGANIC PEROXIDES WITH OXIDATIVE AMPEROMETRIC DETECTION

    EPA Science Inventory

    Reversed-phase high-performance liquid chromatography with oxidative amperometric detection was optimized for the determination of several organic peroxides in drinking water under ideal conditions.The determinations were performed under isocratic conditions using acetonitrile an...

  20. HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY OF SELECTED ORGANIC PEROXIDES WITH OXIDATIVE AMPEROMETRIC DETECTION

    EPA Science Inventory

    Reversed-phase high-performance liquid chromatography with oxidative amperometric detection was optimized for the determination of several organic peroxides in drinking water under ideal conditions.The determinations were performed under isocratic conditions using acetonitrile an...

  1. IDENTIFICATION OF POLAR DRINKING WATER DISINFECTION BY-PRODUCTS USING LIQUID CHROMATOGRAPHY - MASS SPECTROMETRY

    EPA Science Inventory

    A qualitative method using 2,4-dinitrophenylhydrazine (DNPH) derivatization followed by analysis with liquid chromatography (LC)/negative ion-electrospray mass spectrometry (MS) was developed for identifying polar aldehydes and ketones in ozonated drinking water. This method offe...

  2. Qualitative Analysis of Analgesic Tablets: An Experiment Employing High Pressure Liquid Chromatography.

    ERIC Educational Resources Information Center

    Beaver, Rodney W.; And Others

    1983-01-01

    Describes an experiment on the qualitative analysis of several over-the-counter analgesic tablets. Background information, procedures used (including high pressure liquid chromatography), and typical student results are included. (JN)

  3. IDENTIFICATION OF POLAR DRINKING WATER DISINFECTION BY-PRODUCTS USING LIQUID CHROMATOGRAPHY - MASS SPECTROMETRY

    EPA Science Inventory

    A qualitative method using 2,4-dinitrophenylhydrazine (DNPH) derivatization followed by analysis with liquid chromatography (LC)/negative ion-electrospray mass spectrometry (MS) was developed for identifying polar aldehydes and ketones in ozonated drinking water. This method offe...

  4. Qualitative and quantitative determination of ubiquinones by the method of high-efficiency liquid chromatography

    SciTech Connect

    Yanotovskii, M.T.; Mogilevskaya, M.P.; Obol'nikova, E.A.; Kogan, L.M.; Samokhvalov, G.I.

    1986-07-10

    A method has been developed for the qualitative and quantitative determination of ubiquinones CoQ/sub 6/-CoQ/sub 10/, using high-efficiency reversed-phase liquid chromatography. Tocopherol acetate was used as the internal standard.

  5. Preparation of pure microbiological samples for pyrolysis gas-liquid chromatography studies

    NASA Technical Reports Server (NTRS)

    Oxborrow, G. S.; Fields, N. D.; Puleo, J. R.

    1976-01-01

    Bacterial samples were prepared for pyrolysis gas-liquid chromatography using cells grown on membrane filters. Pyrochromatograms were reproducible when cells harvested from the filters were pyrolyzed without being washed.

  6. Preparation of pure microbiological samples for pyrolysis gas-liquid chromatography studies

    NASA Technical Reports Server (NTRS)

    Oxborrow, G. S.; Fields, N. D.; Puleo, J. R.

    1976-01-01

    Bacterial samples were prepared for pyrolysis gas-liquid chromatography using cells grown on membrane filters. Pyrochromatograms were reproducible when cells harvested from the filters were pyrolyzed without being washed.

  7. Determination of Aspartame, Caffeine, Saccharin, and Benzoic Acid in Beverages by High Performance Liquid Chromatography.

    ERIC Educational Resources Information Center

    Delaney, Michael F.; And Others

    1985-01-01

    Describes a simple and reliable new quantitative analysis experiment using liquid chromatography for the determinaiton of caffeine, saccharin, and sodium benzoate in beverages. Background information, procedures used, and typical results obtained are provided. (JN)

  8. [Applications of fast and ultra performance liquid chromatography in the analysis of Chinese herbal medicines].

    PubMed

    Liu, Ying; Zhou, Jianliang; Li, Ping

    2009-09-01

    The analysis of chemical components of Chinese herbal medicines (CHMs) is one of the most critical issues not only for screening and analyzing the bioactive components but also for controlling their quality. However, due to the complexity of the chemical constituents of CHMs, it is difficult to separate them on column within a short time. In the recent, the fast and ultra performance liquid chromatography, including ultra high pressure liquid chromatography, high performance liquid chromatography based on the monolithic columns and high temperature liquid chromatography, are of particular interest because of the high resolution and fast analytical speed provided by these techniques. This overview covers the principle and separation characteristics of these techniques, as well as their applications in Chinese herbal medicines.

  9. Liquid chromatography-fluorescence and liquid chromatography-mass spectrometry detection of tryptophan degradation products of a recombinant monoclonal antibody.

    PubMed

    Nowak, Christine; Ponniah, Gomathinayagam; Cheng, Guilong; Kita, Adriana; Neill, Alyssa; Kori, Yekaterina; Liu, Hongcheng

    2016-03-01

    Light exposure is one of several conditions used to study the degradation pathways of recombinant monoclonal antibodies. Tryptophan is of particular interest among the 20 amino acids because it is the most photosensitive. Tryptophan degradation forms several products, including an even stronger photosensitizer and several reactive oxygen species. The current study reports a specific peptide mapping procedure to monitor tryptophan degradation. Instead of monitoring peptides using UV 214 nm, fluorescence detection with an excitation wavelength of 295 nm and an emission wavelength of 350 nm was used to enable specific detection of tryptophan-containing peptides. Peaks that decreased in area over time are likely to contain susceptible tryptophan residues. This observation can allow further liquid chromatography-mass spectrometry (LC-MS) analysis to focus only on those peaks to confirm tryptophan degradation products. After confirmation of tryptophan degradation, susceptibility of tryptophan residues can be compared based on the peak area decrease. Copyright © 2015 Elsevier Inc. All rights reserved.

  10. New methods and materials for solid phase extraction and high performance liquid chromatography

    SciTech Connect

    Dumont, Philip John

    1996-04-23

    This paper describes methods for solid phase extraction and high performance liquid chromatography (HPLC). The following are described: Effects of Resin Sulfonation on the Retention of Polar Organic Compounds in Solid Phase Extraction; Ion-Chromatographic Separation of Alkali Metals In Non-Aqueous Solvents; Cation-Exchange Chromatography in Non-Aqueous Solvents; and Silicalite As a Stationary Phase For HPLC.

  11. Investigation of the temperature dependence of water adsorption on silica-based stationary phases in hydrophilic interaction liquid chromatography.

    PubMed

    Bartó, Endre; Felinger, Attila; Jandera, Pavel

    2017-03-17

    In the present work, the adsorption of water was investigated in aqueous normal-phase liquid chromatography on Cogent Silica C and Cogent Phenyl hydride stationary phases at different temperatures by frontal analysis - using coulometric Karl Fischer titration - to compare the temperature dependence of adsorption of water from aqueous acetonitrile. The Cogent Silica-C and Cogent Phenyl Hydride columns have a silicon hydride surface (silica hydride) with less than 2% free silanol group; therefore, they do not have a strong association with water. The adsorption behavior of water on the mentioned stationary phases was modeled by Langmuir isotherm. The preferentially adsorbed water was expressed in terms of a hypothetical monomolecular water layer equivalent in the inner pores. The uptake of water slightly depends on the temperature. The adsorbed water may fill four to eight percent of the pore volume over the studied temperature range, which approximately corresponds to the equivalent of 0.24-0.68 water layer coverage of the adsorbent surface. The phenyl hydride stationary phase shows decreased water uptake in comparison to the Silica C stationary phase. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. Preparation and characterization of mesoporous silicas modified with chiral selectors as stationary phase for high-performance liquid chromatography.

    PubMed

    Pérez-Quintanilla, Damián; Morante-Zarcero, Sonia; Sierra, Isabel

    2014-01-15

    New hybrid materials were prepared as novel chiral stationary phases (CSPs) for high-performance liquid chromatography (HPLC). Pure mesoporous silica (SM) and ethylene-bridged periodic mesostructured organosilica (PMO) were functionalized, by a post-synthesis method, with derivates of erythromycin and vancomycin. N2 adsorption-desorption measurements, XRD, FT-IR, MAS NMR, SEM, TEM and elemental analysis were used to characterize the physico-chemical properties of these mesostructured materials, before and after the modification process. The synthesized particles had non-symmetrical 3-D wormhole-like mesostructure, spherical morphology, and a mean pore diameter between 53 and 59 Å. CSPs prepared were tested for the separation of four chiral β-blockers (atenolol, metoprolol, pindolol and propranolol) in normal phase (NP) and polar organic phase (PO) elution modes. Much stronger chiral interaction was observed in vancomycin-modified silicas. Results obtained in these preliminary studies will permit in future works to improve the synthesis route in order to design mesoporous materials with better performance as a chiral stationary phase for HPLC. Copyright © 2013 Elsevier Inc. All rights reserved.

  13. Plasma pharmacokinetics, tissue disposition, excretion and metabolism of vinleucinol in mice as determined by high-performance liquid chromatography.

    PubMed

    van Tellingen, O; Sonneveldt, A L; Beijnen, J H; Nooijen, W J; Kettenes-van den Bosch, J J; Versluis, C; Bult, A

    1994-01-01

    We investigated the pharmacokinetics of the experimental semisynthetic vinca alkaloid vinleucinol (VileE; O4-deacetyl-3-de(methoxycarbonyl)-3-[[[1-ethoxycarbonyl-2- methylbutyl]amino]carbonyl]-vincaleukoblastine). The study was performed in male FVB mice receiving 10.5 mg/kg VileE i.v. or p.o. Plasma, urine, faeces and tissue samples were analysed by a selective method based on ion-exchange normal-phase high-performance liquid chromatography (HPLC) with fluorescence detection and liquid-liquid extraction for sample clean-up. Apart from the parent drug, two other metabolic compounds were detected. One of these metabolites is vinleucinol acid (VileA; O4-deacetyl-3-de(methoxycarbonyl)-3-[[[1-carboxyl-2- methylbutyl]amino]carbonyl]-vincaleukoblastine), which possesses no cytotoxic activity. The structure proposed for the second metabolite (VileX) was based on tandem mass spectrometry (MS-MS) and infrared (IR) spectroscopy data. Metabolization of VileE to VileX must occur in the amino acid moiety of the molecule, with a (beta- or gamma-) lactone ring being formed after oxidation of the (beta- or gamma) carbon of the amino acid. VileX is a major metabolite, which is excreted in faeces and urine after i.v. administration and accounting for up to 23% of the administered dose. The activity of VileX against cultured L1210 cells is four times that of the parent drug VileE and comparable with that of vinblastine (VBL). At 48 h after administration of VileE, the concentration of VileX exceeds that of the parent drug in many tissues. These findings indicate that the metabolite VileX may be at least largely responsible for the activity observed against xenografts in mice after administration of the parent drug, VileE.

  14. Vortex and air assisted liquid-liquid microextraction as a sample preparation method for high-performed liquid chromatography determinations.

    PubMed

    Hosseini, Mohammad; Heydari, Rouhollah; Alimoradi, Mohammad

    2014-12-01

    A novel, simple and sensitive method based on vortex and air assisted liquid-liquid microextraction (VAALLME) technique coupled with high-performance liquid chromatography (HPLC) has been developed for quantitative analysis of β-naphthol, naphthalene and anthracene as model analytes. Unlike the dispersive liquid-liquid microextraction (DLLME), dispersive solvent and centrifuging step were eliminated in proposed technique. In this technique, extraction solvent was dispersed into the aqueous sample solution by using vortex. Phase separation was achieved via motion of air bubbles from the bottom to top of the extraction tube, which promoted the analytes transfer into the supernatant organic phase. Influential parameters on the extraction efficiency such as type and volume of extraction solvent, salt type and its concentration, vortex and aeration times, and sample pH were evaluated and optimized. The calibration curves showed good linearity (r(2)>0.9947) and precision (RSD<5.0%) in the working concentration ranges. The limit of detection (LOD) for β-naphthol, naphthalene and anthracene were 10, 5.0 and 0.5 ng mL(-1), respectively. The recoveries were in the range of 97.0-102.0% with RSD values ranging from 2.2 to 5.2%. Copyright © 2014 Elsevier B.V. All rights reserved.

  15. Separation of anionic oligosaccharides by high-performance liquid chromatography

    SciTech Connect

    Green, E.D.; Baenziger, J.U.

    1986-10-01

    The authors have developed methods for rapid fractionation of anionic oligosaccharides containing sulfate and/or sialic acid moieties by high-performance liquid chromatography (HPLC). Ion-exchange HPLC on amine-bearing columns (Micropak AX-10 and AX-5) at pH 4.0 is utilized to separate anionic oligosaccharides bearing zero, one, two, three, or four charges, independent of the identity of the anionic moieties (sulfate and/or sialic acid). Ion-exchange HPLC at pH 1.7 allows separation of neutral, mono-, di-, and tetrasialylated, monosulfated, and disulfated oligosaccharides. Oligosaccharides containing three sialic acid residues and those bearing one each of sulfate and sialic acid, however, coelute at pH 1.7. Since the latter two oligosaccharide species separate at pH 4.0, analysis at pH 4.0 followed by analysis at pH 1.7 can be utilized to completely fractionate complex mixtures of sulfated and sialylated oligosaccharides. Ion-suppression amine adsorption HPLC has previously been shown to separate anionic oligosaccharides on the basis of net carbohydrate content (size). In this study they demonstrate the utility of ion-suppression amine adsorption HPLC for resolving sialylated oligosaccharide isomers which differ only in the linkages of sialic acid residues (..cap alpha..2,3 vs ..cap alpha..2,6) and/or location of ..cap alpha..2,3- and ..cap alpha..2,6-linked sialic acid moieties on the peripheral branches of oligosaccharides. These two methods can be used in tandem to separate oligosaccharides, both analytically and preparatively, based on their number, types, and linkages of anionic moieties.

  16. Liquid chromatography method to determine polyamines in thermosetting polymers.

    PubMed

    Dopico-García, M S; López-Vilariño, J M; Fernández-Martínez, G; González-Rodríguez, M V

    2010-05-14

    A simple, robust and sensitive analytical method to determine three polyamines commonly used as hardeners in epoxy resin systems and in the manufacture of polyurethane is reported. The studied polyamines are: one tetramine, TETA (triethylenetetramine), and two diamines, IPDA (Isophorone diamine) and TCD-diamine (4,7-methano-1H-indene-5,?-dimethanamine, octahydro-). The latter has an incompletely defined structure, and, as far as we know, has not been previously determined by other methods. All three polyamines contain primary amines; TETA also contains secondary amines. The analytical method involves derivatization with 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate, used for the first time for these compounds, followed by high performance liquid chromatography (HPLC) analysis with a fluorescence (FL) detector (lambda excitation 248nm, lambda emision 395nm). The HPLC-DAD-LTQ Orbitrap MS was used in order to provide structural information about the obtained derivatized compounds. The hybrid linear ion trap LTQ Orbitrap mass spectrometer has been introduced in recent years and provides a high mass accuracy. The structures of the derivatized analytes were identified from the protonated molecular ions [M+H](+) and corresponded to the fully labelled analytes. The following analytical parameters were determined for the method using the HPLC-FL: linearity, precision (2.5-10%), instrumental precision intraday (0.8-1.5%) and interday (2.9-6.3%), and detection limits (0.02-0.14mgL(-1)). The stability of stock solutions and derivatized compounds was also investigated. The method was applied to determine the amine free content in epoxy resin dust collected in workplaces.

  17. Tryptophan and kynurenine determination in human hair by liquid chromatography.

    PubMed

    Dario, Michelli F; Freire, Thamires Batello; Pinto, Claudinéia Aparecida Sales de Oliveira; Prado, María Segunda Aurora; Baby, André R; Velasco, Maria Valéria R

    2017-09-18

    Tryptophan, an amino acid found in hair proteinaceous structure is used as a marker of hair photodegradation. Also, protein loss caused by several chemical/physical treatments can be inferred by tryptophan quantification. Kynurenine is a photo-oxidation product of tryptophan, expected to be detected when hair is exposed mainly to UVB (290-320nm) radiation range. Tryptophan from hair is usually quantified directly as a solid or after alkaline hydrolysis, spectrofluorimetrically. However, these types of measure are not sufficiently specific and present several interfering substances. Thus, this work aimed to propose a quantification method for both tryptophan and kynurenine in hair samples, after alkali hydrolysis process, by using high-performance liquid chromatography (HPLC) with fluorimetric and UV detection. The tryptophan and kynurenine quantification method was developed and validated. Black, white, bleached and dyed (blond and auburn) hair tresses were used in this study. Tryptophan and kynurenine were separated within ∼9min by HPLC. Both black and white virgin hair samples presented similar concentrations of tryptophan, while bleaching caused a reduction in the tryptophan content as well as dyeing process. Unexpectedly, UV/vis radiation did not promote significantly the conversion of tryptophan into its photo-oxidation product and consequently, kynurenine was not detected. Thus, this works presented an acceptable method for quantification of tryptophan and its photooxidation metabolite kynurenine in hair samples. Also, the results indicated that bleaching and dyeing processes promoted protein/amino acids loss but tryptophan is not extensively degraded in human hair by solar radiation. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Separation of stereoisomers of several furan derivatives by capillary gas chromatography-mass spectrometry, supercritical fluid chromatography, and liquid chromatography using chiral stationary phases.

    PubMed

    Kasai, Hiroko F; Tsubuki, Masayoshi; Takahashi, Kazunori; Shirao, Mika; Matsumoto, Yohichiro; Honda, Toshio; Seyama, Yoshiyuki

    2002-11-15

    The direct separation of several stereoisomers (enantiomers and geometrical isomers) of furan derivatives, important intermediates for the synthesis of physiologically active natural products, was achieved using capillary gas chromatography/mass spectrometry with a per-O-methyl-beta-cyclodextrin, supercritical fluid chromatography and high-performance liquid chromatography with a tris(3,5-dimethylphenylcarbamate) of cellulose or amylose for the chiral stational phases, respectively. The temperature dependence of the peak resolution (Rs) and the retention factor (k) over the range of 110-130 degrees was studied using crotyl furfuryl ether in gas chromatography. Successive increases in the Rs value and of the difference between the k value of the E-isomer and the k value of the Z-isomer were observed when the gradient temperature was decreased. The per-O-methyl-beta-cyclodextrin column was suitable for use with volatile furan ethers whose molecular masses are between 150 and 180. In conclusion, the separation of thermally unstable furan derivatives was accomplished using supercritical fluid chromatography and high-performance liquid chromatography.

  19. Development of an on-line mixed-mode gel liquid chromatography×reversed phase liquid chromatography method for separation of water extract from Flos Carthami.

    PubMed

    Wang, Yu-Qing; Tang, Xu; Li, Jia-Fu; Wu, Yun-Long; Sun, Yu-Ying; Fang, Mei-Juan; Wu, Zhen; Wang, Xiu-Min; Qiu, Ying-Kun

    2017-10-13

    A novel on-line comprehensive two-dimensional liquid chromatography (2D-LC) method by coupling mixed-mode gel liquid chromatography (MMG-LC) with reversed phase liquid chromatography (RPLC) was developed. A mixture of 17 reference compounds was used to study the separation mechanism. A crude water extract of Flos Carthami was applied to evaluate the performance of the novel 2D-LC system. In the first dimension, the extract was eluted with a gradient of water/methanol over a cross-linked dextran gel Sephadex LH-20 column. Meanwhile, the advantages of size exclusion, reversed phase partition and adsorption separation mechanism were exploited before further on-line reversed phase purification on the second dimension. This novel on-line mixed-mode Sephadex LH-20×RPLC method provided higher peak resolution, sample processing ability (2.5mg) and better orthogonality (72.9%) versus RPLC×RPLC and hydrophilic interaction liquid chromatography (HILIC)×RPLC. To the best of our knowledge, this is the first report of a mixed-mode Sephadex LH-20×RPLC separation method with successful applications in on-line mode, which might be beneficial for harvesting targets from complicated medicinal plants. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. Evaluation of a silicon oxynitride hydrophilic interaction liquid chromatography column in saccharide and glycoside separations.

    PubMed

    Wan, Huihui; Sheng, Qianying; Zhong, Hongmin; Guo, Xiujie; Fu, Qing; Liu, Yanfang; Xue, Xingya; Liang, Xinmiao

    2015-05-01

    The retention characteristics of a silicon oxynitride stationary phase for carbohydrate separation were studied in hydrophilic interaction chromatography mode. Four saccharides including mono-, di-, and trisaccharides were employed to investigate the effects of water content and buffer concentration in the mobile phase on hydrophilic interaction liquid chromatography retention. For the tested saccharides, the silicon oxynitride column demonstrated excellent performance in terms of separation efficiency, hydrophilicity, and interesting separation selectivity for carbohydrates compared to the bare silica stationary phase. Finally, the silicon oxynitride hydrophilic interaction liquid chromatography column was employed in the separation of complex samples of fructooligosaccharides, saponins, and steviol glycoside from natural products. The resulting chromatograms demonstrated good separation efficiency and longer retention compared with silica, which further confirmed the advantages and potential application of silicon oxynitride stationary phase for hydrophilic interaction liquid chromatography separation. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Isolation of Gregatin A from Phialophora gregata by Preparative High-Pressure Liquid Chromatography

    PubMed Central

    Taylor, Scott L.; Peterson, Robert E.; Gray, Lynn E.

    1985-01-01

    A method was developed for the production and purification of gregatin A from Phialophora gregata NRRL 13198 cultured on rice at 20°C for 28 days. Liquid extraction followed by high-pressure liquid chromatography afforded 247.0 mg of crystalline gregatin A per kg of rice. PMID:16346936

  2. Chromatography.

    ERIC Educational Resources Information Center

    Brantley, L. Reed, Sr.; Demanche, Edna L.; Klemm, E. Barbara; Kyselka, Will; Phillips, Edwin A.; Pottenger, Francis M.; Yamamoto, Karen N.; Young, Donald B.

    This booklet presents some activities on chromatography. Directions for preparing leaf pigment extracts using alcohol are given, and paper chromatography and thin-layer chromatography are described as modifications of the basic principles of chromatography. (KHR)

  3. Chromatography.

    ERIC Educational Resources Information Center

    Brantley, L. Reed, Sr.; Demanche, Edna L.; Klemm, E. Barbara; Kyselka, Will; Phillips, Edwin A.; Pottenger, Francis M.; Yamamoto, Karen N.; Young, Donald B.

    This booklet presents some activities on chromatography. Directions for preparing leaf pigment extracts using alcohol are given, and paper chromatography and thin-layer chromatography are described as modifications of the basic principles of chromatography. (KHR)

  4. Preparation and evaluation of surface-bonded tricationic ionic liquid silica as stationary phases for high-performance liquid chromatography.

    PubMed

    Qiao, Lizhen; Shi, Xianzhe; Lu, Xin; Xu, Guowang

    2015-05-29

    Two tricationic ionic liquids were prepared and then bonded onto the surface of supporting silica materials through "thiol-ene" click chemistry as new stationary phases for high-performance liquid chromatography. The obtained columns of tricationic ionic liquids were evaluated respectively in the reversed-phase liquid chromatography (RPLC) mode and hydrophilic interaction liquid chromatography (HILIC) mode, and possess ideal column efficiency of 80,000 plates/m in the RPLC mode with naphthalene as the test solute. The tricationic ionic liquid stationary phases exhibit good hydrophobic and shape selectivity to hydrophobic compounds, and RPLC retention behavior with multiple interactions. In the HILIC mode, the retention and selectivity were evaluated through the efficient separation of nucleosides and bases as well as flavonoids, and the typical HILIC retention behavior was demonstrated by investigating retention changes of hydrophilic solutes with water volume fraction in mobile phase. The results show that the tricationic ionic liquid columns possess great prospect for applications in analysis of hydrophobic and hydrophilic samples.

  5. High-pressure liquid chromatography of aromatic amines

    NASA Technical Reports Server (NTRS)

    Young, P. R.

    1979-01-01

    Analysis made on commercially available liquid chromatograph demonstrates high-pressure liquid chromatographic conditions for separation of approximately 50 aromatic amines ranging from simple aniline derivatives to complex multiring di- and tri-amines.

  6. New high-performance liquid chromatography assay for glycosyltransferases based on derivatization with anthranilic acid and fluorescence detection.

    PubMed

    Anumula, Kalyan Rao

    2012-07-01

    Assays were developed using the unique labeling chemistry of 2-aminobenzoic acid (2AA; anthranilic acid, AA) for measuring activities of both β1-4 galactosyltransferase (GalT-1) and α2-6 sialyltransferase (ST-6) by high-performance liquid chromatography (HPLC) with fluorescence detection (Anumula KR. 2006. Advances in fluorescence derivatization methods for high-performance liquid chromatographic analysis of glycoprotein carbohydrates. Anal Biochem. 350:1-23). N-Acetylglucosamine (GlcNAc) and N-acetyllactosamine were used as acceptors and uridine diphosphate (UDP)-galactose and cytidine monophosphate (CMP)-N-acetylneuraminic acid (NANA) as donors for GalT-1 and ST-6, respectively. Enzymatic products were labeled in situ with AA and were separated from the substrates on TSKgel Amide 80 column using normal-phase conditions. Enzyme units were determined from the peak areas by comparison with the concomitantly derivatized standards Gal-β1-4GlcNAc and NANA-α2-6 Gal-β1-4GlcNAc. Linearity (time and enzyme concentration), precision (intra- and interassay) and reproducibility for the assays were established. The assays were found to be useful in monitoring the enzyme activities during isolation and purification. The assays were highly sensitive and performed equal to or better than the traditional radioactive sugar-based measurements. The assay format can also be used for measuring the activity of other transferases, provided that the carbohydrate acceptors contain a reducing end for labeling. An assay for glycoprotein acceptors was developed using IgG. A short HPLC profiling method was developed for the separation of IgG glycans (biantennary G0, G1, G2, mono- and disialylated), which facilitated the determination of GalT-1 and ST-6 activities in a rapid manner. Furthermore, this profiling method should prove useful for monitoring the changes in IgG glycans in clinical settings.

  7. Ionic liquids as novel stationary phases in gas liquid chromatography: inverse or normal isotope effect?

    PubMed

    Schmarr, Hans-Georg; Slabizki, Petra; Müntnich, Sabrina; Metzger, Carmen; Gracia-Moreno, Elisa

    2012-12-28

    The separation of deuterated and non-deuterated compounds in gas liquid partitioning chromatography (GLC) on silicone type stationary phase usually results in the inverse isotope effect. With ionic liquids (ILs) as stationary phase, however, this may show a totally different nature. The inverse isotope effect, in which heavier (deuterated) isotopic compounds (isotopologues) elute earlier, is to be expected when van der Waals (London) dispersion forces play a dominant role in the solute-stationary phase interaction. Such (apolar) interactions seem to play only a minor role when ILs are the stationary phases, leading to only a marginal inverse isotope effect, e.g. for the separation of 2,4,6-trichloroanisole and its [(2)H(5)]-isotopologue on 1,12-di(tripropylphosphonium) dodecane bis(trifluoromethansulfonyl) amide (commercialized as SLB-IL59, Supelco). Indeed, with the most polar stationary phase available (commercialized as SLB-IL111; Supelco), this separation showed a normal isotope effect. Further examples are presented and the nature of the isotope effect observed is discussed. Copyright © 2012 Elsevier B.V. All rights reserved.

  8. Crosslinked polymeric ionic liquids as solid-phase microextraction sorbent coatings for high performance liquid chromatography.

    PubMed

    Yu, Honglian; Merib, Josias; Anderson, Jared L

    2016-03-18

    Neat crosslinked polymeric ionic liquid (PIL) sorbent coatings for solid-phase microextraction (SPME) compatible with high-performance liquid chromatography (HPLC) are reported for the first time. Six structurally different PILs were crosslinked to nitinol supports and applied for the determination of select pharmaceutical drugs, phenolics, and insecticides. Sampling conditions including sample solution pH, extraction time, desorption solvent, desorption time, and desorption solvent volume were optimized using design of experiment (DOE). The developed PIL sorbent coatings were stable when performing extractions under acidic pH and remained intact in various organic desorption solvents (i.e., methanol, acetonitrile, acetone). The PIL-based sorbent coating polymerized from the IL monomer 1-vinyl-3-(10-hydroxydecyl) imidazolium chloride [VC10OHIM][Cl] and IL crosslinker 1,12-di(3-vinylbenzylimidazolium) dodecane dichloride [(VBIM)2C12] 2[Cl] exhibited superior extraction performance compared to the other studied PILs. The extraction efficiency of pharmaceutical drugs and phenolics increased when the film thickness of the PIL-based sorbent coating was increased while many insecticides were largely unaffected. Satisfactory analytical performance was obtained with limits of detection (LODs) ranging from 0.2 to 2 μg L(-1) for the target analytes. The accuracy of the analytical method was examined by studying the relative recovery of analytes in real water samples, including tap water and lake water, with recoveries varying from 50.2% to 115.9% and from 48.8% to 116.6%, respectively.

  9. Orthogonal separation on one beta-cyclodextrin column by switching reversed-phase liquid chromatography and hydrophilic interaction chromatography.

    PubMed

    Feng, Jia-tao; Guo, Zhi-mou; Shi, Hui; Gu, Jiang-ping; Jin, Yu; Liang, Xin-miao

    2010-06-15

    A dual retention combined with reversed-phase liquid chromatography (RP-LC) and hydrophilic interaction chromatography (HILIC) has been observed on beta-cyclodextrin (beta-CD) bonded stationary phase. A typical U-shaped retention curve was achieved owing to dual retention mechanism. Based on this observation, a beta-CD column can be operated under reversed-phase liquid chromatography (RP-LC) and hydrophilic interaction chromatography (HILIC) modes. Two-dimensional liquid chromatography (2D-LC) analysis can be realized on just a beta-CD column by switching these two different separation modes. In this study, off-line 2D-LC analysis for a natural product was carried out to prove the orthogonal separation between RP-LC and HILIC modes on a Click beta-CD column. Herba Hedyotis Diffusae, the whole grass of Hedyotis Diffusae wild was extracted with water, pretreated with macroporous resin and then first separated at RP-LC mode on the Click beta-CD column to obtain successive fractions, which were then reanalyzed at HILIC mode on the same Click beta-CD column. The result proved that both separation modes on the Click beta-CD column have good retention and peak shape, and these two separation modes have good orthogonality. 2D-LC analysis revealed abundant information in the natural product. Especially numerous minor components were enriched and separated. The mobile phase used in RP-LC and HILIC modes can be same and the switch between these two separation modes is easily realized by changing the ratio of the acetonitrile and water. Hence the mobile phase in this 2D-LC system is completely compatible. This advantage makes this combination is an appropriate 2D-LC method for the solutes having retention at both separation modes.

  10. Characterization of synthetic dyes by comprehensive two-dimensional liquid chromatography combining ion-exchange chromatography and fast ion-pair reversed-phase chromatography.

    PubMed

    Pirok, Bob W J; Knip, Jitske; van Bommel, Maarten R; Schoenmakers, Peter J

    2016-03-04

    In the late 19th century, newly invented synthetic dyes rapidly replaced the natural dyes on the market. The characterization of mixtures of these so-called early synthetic dyes is complicated through the occurrence of many impurities and degradation products. Conventional one-dimensional liquid chromatography does not suffice to obtain fingerprints with sufficient resolution and baseline integrity. Comprehensive two-dimensional liquid chromatography (LC×LC) is employed in this study, with ion-exchange chromatography in the first dimension and fast ion-pair liquid chromatography in the second. Retention in the first dimension is largely determined by the number of charges, while the selection of a small ion-pair reagent (tetramethylammonium hydroxide) in the second dimension causes retention to be largely determined by the molecular structure of the dye. As a result, there is a high degree of orthogonality of the two dimensions, similar to the values typically encountered in GC×GC. The proposed LC×LC method shows a theroretical peak capacity of about 2000 in an analysis time of about three hours. Clear, informative fingerprints are obtained that open a way to a more efficient characterization of dyes used in objects of cultural heritage. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. Application of Ionic Liquids in High Performance Reversed-Phase Chromatography

    PubMed Central

    Wang, Ye; Tian, Minglei; Bi, Wentao; Row, Kyung Ho

    2009-01-01

    Ionic liquids, considered “green” chemicals, are widely used in many areas of analytical chemistry due to their unique properties. Recently, ionic liquids have been used as a kind of novel additive in separation and combined with silica to synthesize new stationary phase as separation media. This review will focus on the properties and mechanisms of ionic liquids and their potential applications as mobile phase modifier and surface-bonded stationary phase in reversed-phase high performance liquid chromatography (RP-HPLC). Ionic liquids demonstrate advantages and potential in chromatographic field. PMID:19582220

  12. Partition coefficients of organic compounds in new imidazolium based ionic liquids using inverse gas chromatography.

    PubMed

    Revelli, Anne-Laure; Mutelet, Fabrice; Jaubert, Jean-Noël

    2009-06-05

    Partition coefficients of organic compounds in four ionic liquids: 1-ethanol-3-methylimidazolium tetrafluoroborate, 1-ethanol-3-methylimidazolium hexafluorophosphate, 1,3-dimethylimidazolium dimethylphosphate and 1-ethyl-3-methylimidazolium diethylphosphate were measured using inverse gas chromatography from 303.3 to 332.55K. The influence of gas-liquid and gas-solid interfacial adsorption of different solutes on ionic liquids was also studied. Most of the polar solutes were retained largely by partition while light hydrocarbons were retained predominantly by interfacial adsorption on the ionic liquids studied in this work. The solvation characteristics of the ionic liquids were evaluated using the Abraham solvation parameter model.

  13. Using dispersive liquid-liquid microextraction and liquid chromatography for determination of guaifenesin enantiomers in human urine.

    PubMed

    Hatami, Mehdi; Farhadi, Khalil; Abdollahpour, Assem

    2011-11-01

    A simple, rapid, and efficient method, dispersive liquid-liquid microextraction (DLLME) coupled with high-performance liquid chromatography-fluorescence detector, has been developed for the determination of guaifenesin (GUA) enantiomers in human urine samples after an oral dose administration of its syrup formulation. Urine samples were collected during the time intervals 0-2, 2-4, and 4-6 h and concentration and ratio of two enantiomers was determined. The ratio of R-(-) to S-(+) enantiomer concentrations in urine showed an increase with time, with R/S ratios of 0.66 at 2 h and 2.23 at 6 h. For microextraction process, a mixture of extraction solvent (dichloromethane, 100 μL) and dispersive solvent (THF, 1 mL) was rapidly injected into 5.0 mL diluted urine sample for the formation of cloudy solution and extraction of enantiomers into the fine droplets of CH(2)Cl(2). After optimization of HPLC enantioselective conditions, some important parameters, such as the kind and volume of extraction and dispersive solvents, extraction time, temperature, pH, and salt effect were optimized for dispersive liquid-liquid microextraction process. Under the optimum extraction condition, the method yields a linear calibration curve in the concentration range from 10 to 2000 ng/mL for target analytes. LOD was 3.00 ng/mL for both of the enantiomers. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Identification of Explosives from Porous Materials: Applications Using Reverse Phase High Performance Liquid Chromatography and Gas Chromatography

    NASA Astrophysics Data System (ADS)

    Miller, C. J.; Elias, G.; Schmitt, N. C.; Rae, C.

    2010-06-01

    High performance liquid chromatography and gas chromatography techniques are well documented and widely used for the detection of trace explosives from organic solvents. These techniques were modified to identify and quantify explosives extracted from various materials taken from people who had recently handled explosives. Documented techniques were modified to specifically detect and quantify trace levels of the military explosives, RDX, TNT, and PETN from denim, colored flannel, vinyl, and canvas extracted in methanol and filtered using no additional sample cleanup of the sample extract prior to analysis. The filtered methanol extracts were injected directly into several different column types and analyzed by high performance liquid chromatography using ultraviolet detection and/or gas chromatography using electron capture detection. This paper describes general screening methods that were used to determine the presence of explosives (RDX, TNT, and PETN) in unknown samples of denim, colored flannel, vinyl and canvas in addition to techniques that have been optimized for quantification of each explosive from the substrate extracts.

  15. Separation of Nitration By-Products in Commercial-Grade Trinitro-Toluene by High Performance Liquid Chromatography.

    DTIC Science & Technology

    1982-06-01

    MRL-TN-464 SEPARATION OF NITRATION BY-PRODUCTS IN COMMERCIAL-GRADE TITR-TOLUENE BY HIGH PERFORMANCE LIQUID CHROMATOGRAPHY Peter J. Sanders ABSTRACT...UNCLASSIFIED TITLE SEPARATION OF NITRATION BY-PRODUCTS IN COMMERCIAL-GRADE TRXNITRO-TOLUENE BY HIGH PERFORMANCE LIQUID CHROMATOGRAPHY AUTHOR(S...PRODUCTS IN COMMERCIAL-GRADE TRINITRO-TOLUENE BY HIGH PERFORMANCE LIQUID CHROMATOGRAPHY 16 INTRODUCTION Fbr some time, a need has existed for the

  16. Comprehensive two-dimensional liquid chromatography for polyphenol analysis in foodstuffs.

    PubMed

    Cacciola, Francesco; Farnetti, Sara; Dugo, Paola; Marriott, Philip John; Mondello, Luigi

    2017-01-01

    Polyphenols are a class of plant secondary metabolites that are recently drawing a special interest because of their broad spectrum of pharmacological effects. As they are characterized by an enormous structural variability, the identification of these molecules in food samples is a difficult task, and sometimes having only a limited number of commercially available reference materials is not of great help. One-dimensional liquid chromatography is the most widely applied analytical approach for their analysis. In particular, the hyphenation of liquid chromatography to mass spectrometry has come to play an influential role by allowing relatively fast tentative identification and accurate quantification of polyphenolic compounds at trace levels in vegetable media. However, when dealing with very complex real-world food samples, a single separation system often does not provide sufficient resolving power for attaining rewarding results. Comprehensive two-dimensional liquid chromatography is a technique of great analytical impact, since it offers much higher peak capacities than separations in a single dimension. In the present review, we describe applications in the field of comprehensive two-dimensional liquid chromatography for polyphenol analysis in real-world food samples. Comprehensive two-dimensional liquid chromatography applications to nonfood matrices fall outside the scope of the current report and will not be discussed. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Quality evaluation of moluodan concentrated pill using high-performance liquid chromatography fingerprinting coupled with chemometrics.

    PubMed

    Tao, Lingyan; Zhang, Qing; Wu, Yongjiang; Liu, Xuesong

    2016-12-01

    In this study, a fast and effective high-performance liquid chromatography method was developed to obtain a fingerprint chromatogram and quantitative analysis simultaneously of four indexes including gallic acid, chlorogenic acid, albiflorin and paeoniflorin of the traditional Chinese medicine Moluodan Concentrated Pill. The method was performed by using a Waters X-bridge C18 reversed phase column on an Agilent 1200S high-performance liquid chromatography system coupled with diode array detection. The mobile phase of the high-performance liquid chromatography method was composed of 20 mmol/L phosphate solution and acetonitrile with a 1 mL/min eluent velocity, under a detection temperature of 30°C and a UV detection wavelength of 254 nm. After the methodology validation, 16 batches of Moluodan Concentrated Pill were analyzed by this high-performance liquid chromatography method and both qualitative and quantitative evaluation results were achieved by similarity analysis, principal component analysis and hierarchical cluster analysis. The results of these three chemometrics were in good agreement and all indicated that batch 10 and batch 16 showed significant differences with the other 14 batches. This suggested that the developed high-performance liquid chromatography method could be applied in the quality evaluation of Moluodan Concentrated Pill.

  18. Systematic comparison of sensitivity between hydrophilic interaction liquid chromatography and reversed phase liquid chromatography coupled with mass spectrometry.

    PubMed

    Periat, Aurélie; Boccard, Julien; Veuthey, Jean-Luc; Rudaz, Serge; Guillarme, Davy

    2013-10-18

    Hydrophilic interaction liquid chromatography (HILIC) appears as a promising strategy to increase sensitivity with electrospray ionization source (ESI/MS). In the present study, peak heights, background noises and signal-to-noise ratios (S/N) obtained with HILIC-MS/MS and RPLC-MS/MS conditions were systematically compared using a dataset of 56 basic drugs possessing diverse physico-chemical properties. Various mobile phase conditions were investigated, including different pH (3 and 6 in HILIC; 3, 6 and 9 in RPLC) and flow rates (300, 600 and 1000μL/min). The average gain in sensitivity obtained between HILIC and RPLC was equal to 7 and 10 at pH 3 and 6, respectively. However, this value was not reliable, since it was altered by a few compounds possessing an "extreme" behaviour (gain in sensitivity from 100-fold to >8000-fold better). Then, the median gain in sensitivity, equal to 4 in our case, whatever the pH, should be considered. For about 90% of the tested compounds and analytical conditions, the best S/N was systematically attained under HILIC mode. Thanks to PCA representation, it was shown that the basic compounds with pKa between 6 and 8 generally had the best sensitivity in HILIC at pH 6, while the best sensitivity for basic analytes possessing pKa higher than 8 was usually obtained in HILIC at pH 3. As previously reported, the sensitivity gain in HILIC vs. RPLC was explained by the difference in acetonitrile concentration at elution (in average 29% ACN in RPLC and 82% ACN in HILIC at pH 6) leading to better analytes' desolvation. However, it seems that this high proportion of solvent also favourably influenced the ionization by modifying pH and pKa. Indeed the weakest bases of our training set of compounds (pKa between 2 and 5) showed an unexpectedly strong gain in sensitivity, between 20 and 100-fold in comparison to RPLC. These results prove that the ionic character of analytes in solution (i.e., pKa and pH) and the ionization mechanism (i.e., proton

  19. Determination of vitamins D2 and D3 in selected food matrices by online high-performance liquid chromatography-gas chromatography-mass spectrometry (HPLC-GC-MS).

    PubMed

    Nestola, Marco; Thellmann, Andrea

    2015-01-01

    An online normal-phase liquid chromatography-gas chromatography-mass spectrometry (HPLC-GC-MS) method was developed for the determination of vitamins D2 and D3 in selected food matrices. Transfer of the sample from HPLC to GC was realized by large volume on-column injection; detection was performed with a time-of-flight mass spectrometer (TOF-MS). Typical GC problems in the determination of vitamin D such as sample degradation or sensitivity issues, previously reported in the literature, were not observed. Determination of total vitamin D content was done by quantitation of its pyro isomer based on an isotopically labelled internal standard (ISTD). Extracted ion traces of analyte and ISTD showed cross-contribution, but non-linearity of the calibration curve was not determined inside the chosen calibration range by selection of appropriate quantifier ions. Absolute limits of detection (LOD) and quantitation (LOQ) for vitamins D2 and D3 were calculated as approximately 50 and 150 pg, respectively. Repeatability with internal standard correction was below 2 %. Good agreement between quantitative results of an established high-performance liquid chromatography with UV detection (HPLC-UV) method and HPLC-GC-MS was found. Sterol-enriched margarine was subjected to HPLC-GC-MS and HPLC-MS/MS for comparison, because HPLC-UV showed strong matrix interferences. HPLC-GC-MS produced comparable results with less manual sample cleanup. In summary, online hyphenation of HPLC and GC allowed a minimization in manual sample preparation with an increase of sample throughput.

  20. Isolation and purification of six iridoid glycosides from gardenia jasminoides fruit by medium-pressure liquid chromatography combined with macroporous resin chromatography.

    PubMed

    Wang, Yun; Liu, Hui; Shen, Lifeng; Yao, Lan; Ma, Yinlian; Yu, Dingrong; Chen, Jianhong; Li, Puling; Chen, Ying; Zhang, Cun

    2015-12-01

    Gardeniae fructus is one of the most frequently used herbs in traditional Chinese medicine. In the present study, a process for the enrichment of six iridoid glycosides from Gardeniae fructus was developed using medium-pressure liquid chromatography combined with macroporous resin and reversed-phase chromatography. The purities of different fractions from Gardeniae fructus were assessed using quantitative high-performance liquid chromatography. After fractionation using HPD-100 column chromatography, a 30% ethanol fraction was selected based on high-performance liquid chromatography and liquid chromatography with mass spectrometry qualitative analysis to separate and purify. Based on the orientation analysis results, six compounds-deacetyl asperulosidic acid methyl ester, gardenoside, ixoroside, scandoside methyl ester, genipin-1-O-β-d-gentiobioside, and geniposide-were successfully isolated and purified in three to four combined steps from Gardeniae fructus. The purities of these compounds were found by high-performance liquid chromatography analysis to be 97.9, 98.1, 95.5, 96.3, 97.1, and 98.7%, respectively. Moreover, their structures were elucidated by NMR spectroscopy and liquid chromatography with tandem mass spectrometry. The separation process was highly efficient, rapid, and accurate, making it a potential approach for the large-scale production of iridoids in the laboratory and providing several marker compounds for quality control. This procedure may be meaningful for the purification of other natural products used in traditional Chinese medicine. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. The off-line combination of high performance liquid chromatography and comprehensive two-dimensional gas chromatography-mass spectrometry: a powerful approach for highly detailed essential oil analysis.

    PubMed

    Tranchida, Peter Q; Zoccali, Mariosimone; Bonaccorsi, Ivana; Dugo, Paola; Mondello, Luigi; Dugo, Giovanni

    2013-08-30

    The present contribution is focused on the off-line combination of high performance liquid chromatography (HPLC) and comprehensive two-dimensional gas chromatography-quadrupole mass spectrometry (GC×GC-quadMS), and its application to the detailed qualitative analysis of essential oils. Specifically, a silica column was exploited for the separation of the essential oil constituents in two groups, namely hydrocarbon and oxygenated compounds. After, each HPLC-fraction was reduced in volume, and then subjected to cryogenically modulated GC×GC-quadMS analysis. The volatiles were separated on a normal-phase GC×GC column set, and identified through database matching and linear retention index information. The concentrated HPLC fractions gave origin to unexpectably crowded chromatograms, due to two fundamental GC×GC characteristics, namely the enhanced separation power and sensitivity. The results attained were particularly stimulating with regards to the oxygenated compounds, namely those constituents which contribute most to the essential oil aroma, and are of more use for the evaluation of quality and genuineness. Two genuine Citrus essential oils, bergamot and sweet orange, were subjected to analysis, and compared to applications carried out with a GC-quadMS instrument. Copyright © 2013 Elsevier B.V. All rights reserved.

  2. Recent advances in liquid and gas chromatography methodology for extending coverage of the metabolome.

    PubMed

    Haggarty, Jennifer; Burgess, Karl Ev

    2017-02-01

    The metabolome is the complete complement of metabolites (small organic biomolecules). In order to comprehensively understand the effect of stimuli on a biological system, it is important to detect as many of the metabolites within that system as possible. This review briefly describes some new advances in liquid and gas chromatography to improve coverage of the metabolome, including the serial combination of two columns in tandem, column switching and different variations of two-dimensional chromatography. Supercritical fluid chromatography could provide complimentary data to liquid and gas chromatography. Although there have been many recent advancements in the field of metabolomics, it is evident that a combination, rather than a single method, is required to approach full coverage of the metabolome. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

  3. High-pressure liquid chromatography: A brief introduction and its application in analyzing the degradation of a C-ether (Thio-ether) liquid lubricant

    NASA Technical Reports Server (NTRS)

    1983-01-01

    The general principles of classical liquid chromatography and high pressure liquid chromatography (HPLC) are reviewed, and their advantages and disadvantages are compared. Several chromatographic techniques are reviewed, and the analytical separation of a C-ether liquid lubricant by each technique is illustrated. A practical application of HPLC is then demonstrated by analyzing a degraded C-ether liquid lubricant from full scale, high temperature bearing tests.

  4. Purification of Bovine Hemoglobin via Fast Performance Liquid Chromatography

    PubMed Central

    Dimino, Michael L.

    2007-01-01

    Bovine hemoglobin (bHb) was purified from bovine red blood cells (bRBCs) via anion exchange chromatography preceded by dialysis. This is a fast and effective way to obtain bHb from bRBCs using Q Sepharose XL, a strong anion exchange resin. This resin had double the binding capacity for bHb compared to three other anion exchange resins that were studied in this work. Methemoglobin levels remained below 2% with bHb concentrations between 0.7 and 1.7 mM. The high purity of bHb was confirmed via SDS-PAGE and size exclusion chromatography. PMID:17581802

  5. Monodisperse microbeads of hypercrosslinked polystyrene for liquid and supercritical fluid chromatography

    NASA Astrophysics Data System (ADS)

    Tsyurupa, M. P.; Blinnikova, Z. K.; Il'in, M. M.; Davankov, V. A.; Parenago, O. O.; Pokrovskii, O. I.; Usovich, O. I.

    2015-11-01

    Monodisperse styrene-divinylbenzene (1 wt %) copolymer microbeads are obtained via the elaborate method of high-productivity precipitation polymerization. The crosslinking of this copolymer with chloromethyl methyl ether in the presence of Friedel-Crafts catalyst yields porous hypercrosslinked polymers with degrees of crosslinking that range from 200 to 500%. Microbead sorbents are shown to be suited for selective stationary phases for high-performance liquid chromatography and supercritical fluid chromatography.

  6. The differentiation and assay of vitamins D2 and D3 by gas–liquid chromatography

    PubMed Central

    Murray, T. K.; Day, K. C.; Kodicek, E.

    1966-01-01

    1. A method is described for the differentiation and determination of as little as 0·2μg. of vitamins D2 and D3 by gas–liquid chromatography. 2. The vitamins are converted by treatment with antimony trichloride into isovitamins D2 and D3, which show single, separate peaks on gas–liquid chromatography, unlike the unmodified vitamins, which give twin peaks due to the formation of pyro and isopyro derivatives. 3. Since isovitamins D2 and D3 remain together in all steps of the procedure except during gas–liquid chromatography, one may be used as an internal standard for the other. 4. The use of an internal standard reduces the importance of loss during sample preparation and increases precision. 5. The application of the method to biological materials is demonstrated. PMID:4287184

  7. Plasma lipid analysis by hydrophilic interaction liquid chromatography coupled with electrospray ionization tandem mass spectrometry.

    PubMed

    Sonomura, Kazuhiro; Kudoh, Shinobu; Sato, Taka-Aki; Matsuda, Fumihiko

    2015-06-01

    A novel method for the analysis of endogenous lipids and related compounds was developed employing hydrophilic interaction liquid chromatography with electrospray ionization tandem mass spectrometry. A hydrophilic interaction liquid chromatography with carbamoyl stationary phase achieved clear separation of phosphatidylcholine, lysophosphatidylcholine, sphingomyelin, ceramide, and mono-hexsosyl ceramide groups with good peak area repeatability (RSD% < 10) and linearity (R(2) > 0.99). The established method was applied to human plasma assays and a total of 117 endogenous lipids were successfully detected and reproducibly identified. In addition, we investigated the simultaneous detection of small polar metabolites such as amino and organic acids co-existing in the same biological samples processed in a single analytical run with lipids. Our results show that hydrophilic interaction liquid chromatography is a useful tool for human plasma lipidome analysis and offers more comprehensive metabolome coverage.

  8. Quantification of organophosphorus nerve agent metabolites using a reduced-volume, high-throughput sample processing format and liquid chromatography-tandem mass spectrometry.

    PubMed

    Swaim, Leigh L; Johnson, Rudolph C; Zhou, Yingtao; Sandlin, Chris; Barr, John R

    2008-01-01

    A reduced-volume, high-throughput analytical method has been developed for the quantification of organophosphorus (OP) nerve agent metabolites in human urine. Metabolites of soman, sarin, cyclohexyl-sarin, VX, and Russian-VX were quantified down to a lowest reportable limit of 1 ng/mL in human urine. One hundred microliter urine samples were preconcentrated using normal-phase 96-well solid-phase extraction silica sorbent beds. Dual-column hydrophilic interaction liquid chromatography was applied in a 2.5-min isocratic separation followed by negative electrospray isotope-dilution multiple-reaction-monitoring mass spectrometry. Method validation included the characterization of two synthetic urine pools, relative recovery experiments, and calculation of the method limit of detection. All liquid handling steps were processed in a high-density 96-well format, including sample aliquoting, extraction, dry-down, and reconstitution. This allows up to 3840 unknown samples, plus calibrators and quality control materials, to be prepared on a single liquid handler in a 24-h period. In a public health emergency involving OP-nerve agents, this method provides the sample preparation and analytical capacity to respond rapidly to a large number of patient samples.

  9. Evaluation of the botanical authenticity and phytochemical profile of black cohosh products by high-performance liquid chromatography with selected ion monitoring liquid chromatography-mass spectrometry.

    PubMed

    Jiang, Bei; Kronenberg, Fredi; Nuntanakorn, Paiboon; Qiu, Ming-Hua; Kennelly, Edward J

    2006-05-03

    Black cohosh (Actaea racemosa L., syn. Cimicifuga racemosa L.) has become increasingly popular as a dietary supplement in the United States for the treatment of symptoms related to menopause, but the botanical authenticity of most products containing black cohosh has not been evaluated, nor is manufacturing highly regulated in the United States. In this study, 11 black cohosh products were analyzed for triterpene glycosides, phenolic constituents, and formononetin by high-performance liquid chromatography-photodiode array detection and a new selected ion monitoring liquid chromatography-mass spectrometry method. Three of the 11 products were found to contain the marker compound cimifugin and not cimiracemoside C, thereby indicating that these plants contain Asian Actaea instead of black cohosh. One product contained both black cohosh and an Asian Actaea species. For the products containing only black cohosh, there was significant product-to-product variability in the amounts of the selected triterpene glycosides and phenolic constituents, and as expected, no formononetin was detected.

  10. Hard modeling methods for the curve resolution of data from liquid chromatography with a diode array detector and on-flow liquid chromatography with nuclear magnetic resonance spectroscopy.

    PubMed

    Wasim, Mohammad; Brereton, Richard G

    2006-01-01

    Hard modeling methods have been performed on data from high-performance liquid chromatography with a diode array detector (LC-DAD) and on-flow liquid chromatography with 1H nuclear magnetic spectroscopy (LC-NMR). Four methods have been used to optimize parameters to model concentration profiles, three of which belong to classical optimization methods (the simplex method of Nelder-Mead, sequential quadratic programming approach, and Levenberg-Marquardt method), and the fourth is the application of genetic algorithms using real-value encoding. Only classical methods worked well for LC-DAD data, while all of the methods produced good results when LC-NMR data were divided into small spectral windows of peak clusters and parameters were optimized over each window.

  11. Determination of muscimol and ibotenic acid in Amanita mushrooms by high-performance liquid chromatography and liquid chromatography-tandem mass spectrometry.

    PubMed

    Tsujikawa, Kenji; Kuwayama, Kenji; Miyaguchi, Hajime; Kanamori, Tatsuyuki; Iwata, Yuko; Inoue, Hiroyuki; Yoshida, Takemi; Kishi, Tohru

    2007-06-01

    A reliable analytical method was developed for the quantification and identification of muscimol (MUS) and ibotenic acid (IBO), the toxic constituents of Amanita muscaria and Amanita pantherina. MUS and IBO were extracted from mushrooms by aqueous methanol and derivatized with dansyl chloride (DNS-Cl). After extraction with ethyl acetate and evaporation of the solvent, the residue was ethylated with 1.25 M hydrogen chloride in ethanol. The resulting derivatives were quantified by high-performance liquid chromatography with UV detection and identified by liquid chromatography electrospray ionization tandem mass spectrometry. Calibration curves were linear in the range of 25-2500 ppm for MUS and 40-2500 ppm for IBO, respectively. This method was successfully applied to identify and quantify MUS and IBO in Amanita mushrooms naturally grown and circulated in the drug market.

  12. Ultrasound-assisted ionic liquid-based homogeneous liquid-liquid microextraction high-performance liquid chromatography for determination of tanshinones in Salvia miltiorrhiza Bge. root.

    PubMed

    Wang, Zhibing; Cao, Bocheng; Yu, Aimin; Zhang, Hanqi; Qiu, Fangping

    2015-02-01

    The ultrasound-assisted ionic liquid-based homogeneous liquid-liquid microextraction has been developed and applied to the extraction of four tanshinones, including dihydrotanshinone, tanshinone I, cryptotanshinone and tanshinone IIA in Salvia miltiorrhiza Bge. root. High performance liquid chromatography was applied to the separation and determination of the analytes. The ionic liquid was used as extraction solvent and target analytes were extracted with help of ultrasound. Then, ion-pairing agent was added into the sample solution, which resulted in the formation of water-insoluble ionic liquid in the solution. The phase separation was performed by centrifugation. The extraction, concentration and purification of target analytes were performed simultaneously. The experimental parameters, including type and volume of ionic liquid, sample amount, the size of sample particle, pH value of extraction medium, extraction temperature, extraction time, amount of ion-pairing agent and centrifuging time, were investigated and optimized. The calibration curves showed good linear relationship (r>0.9997). The limits of detection and quantification were in the range of 0.052-0.093 and 0.17-0.31 μg mL(-1), respectively. The recoveries were between 70.45% and 94.23% with relative standard deviations lower than 5.31%. The present method is free of volatile organic solvents, and represents lower expenditures of sample, extraction time and solvent, compared with UAE and HRE. There was no obvious difference in the extraction yields of active constitutions obtained by the three extraction methods.

  13. Surface diffusion in reversed-phase liquid chromatography

    SciTech Connect

    Miyabe, Kanji; Guiochon, Georges A

    2010-01-01

    More than 40 years ago, Giddings pointed out in 'Dynamics of Chromatography' that surface diffusion should become an important research topic in the kinetics of chromatographic phenomena. However, few studies on surface diffusion in adsorbents used in chromatography were published since then. Most scientists use ordinary rate equations to study mass transfer kinetics in chromatography. They take no account of surface diffusion and overlook the significant contributions of this mass transfer process to chromatographic behavior and to column efficiency at high mobile phase flow rate. Only recently did the significance of surface diffusion in separation processes begin to be recognized in connection with the development of new techniques of fast flow, high efficiency chromatography. In this review, we revisit the reports on experimental data on surface diffusion and introduce a surface-restricted molecular diffusion model, derived as a first approximation for the mechanism of surface diffusion, on the basis of the absolute rate theory. We also explain how this model accounts for many intrinsic characteristics of surface diffusion that cannot properly be explained by the conventional models of surface diffusion.

  14. Determination of organophosphorus pesticides in soil by dispersive liquid-liquid microextraction and gas chromatography.

    PubMed

    Yang, Zhonghua; Liu, Yu; Liu, Donghui; Zhou, Zhiqiang

    2012-01-01

    In this article, a rapid and sensitive sample pretreatment technique for the determination of organophosphorus pesticides (OPPs) in soil samples is developed by using dispersive liquid-liquid microextraction (DLLME) combined with gas chromatography-flame photometric detection. Experimental conditions, including the kind of extraction and disperser solvent and their volumes, the extraction time, and the salt addition, are investigated, and the following experiment factors are used: 20 µL chlorobenzene as the extraction solvent; 1.0 mL acetonitrile as the disperser solvent; no addition of salt; and an extraction time of 1 min. Under the optimum conditions, the linearities for the three target OPPs (ethoprophos, chlorpyriphos, and profenofos) are obtained by five points in the concentration range of 2.5-1500 µg/kg, and three replicates are used for each point. Correlation coefficients vary from 0.9987 to 0.9997. The repeatability is tested by spiking soil samples at a concentration level of 5.0 µg/kg. The relative standard deviation (n = 3) varied between 2.0% and 6.6%. The limits of detection, based on a signal-to-noise ratio (S/N) of 3, range from 200 to 500 pg/g. This method is applied to the analysis of the spiked samples S1, S2, and S3, which are collected from the China Agriculture University's orchard, lawn, and garden, respectively. The recoveries for each target analyte are in the range between 87.9% and 108.0%, 87.4% and 108.0%, and 86.7% and 107.2%, respectively.

  15. Fluorimetric assay for ornithine decarboxylase by high-performance liquid chromatography.

    PubMed

    Haraguchi, K; Kai, M; Kohashi, K; Ohkura, Y

    1980-12-05

    A highly sensitive method for the assay of ornithine decarboxylase in sample solutions prepared from rat tissue homogenate is described which employs high-performance liquid chromatography with fluorescence detection. Putrescine formed from ornithine under the optimal conditions for the enzyme reaction is treated by Cellex P column chromatography for clean-up and converted into the fluorescamine derivative in the presence of cupric ion which inhibits the reaction of interfering amines with fluorescamine. The derivative is separated by reversed-phase chromatography on LiChrosorb RP-18 with linear gradient elution. The lower limit of detection for putrescine formed enzymatically is 5 pmol.

  16. Clinical Proteomics: Liquid Chromatography-Mass Spectrometry (LC-MS) Purification Systems.

    PubMed

    Henry, Michael; Meleady, Paula

    2017-01-01

    Liquid chromatography-mass spectrometry (LC-MS) has become a routine powerful technology in clinical proteomic studies for protein identification, protein characterization and the discovery of biomarkers. In this chapter, we describe two protocol methods to analyze clinical patient samples using a resin based depletion column followed by either protein In-gel enzymatic digestion or protein in-solution enzymatic digestion and then analysis by one-dimensional reverse-phase chromatography or two-dimensional strong cation exchange (SCX)-reverse-phase chromatography (RPC).

  17. High-performance liquid chromatography of oligoguanylates at high pH

    NASA Technical Reports Server (NTRS)

    Stribling, R.; Deamer, D. (Principal Investigator)

    1991-01-01

    Because of the stable self-structures formed by oligomers of guanosine, standard high-performance liquid chromatography techniques for oligonucleotide fractionation are not applicable. Previously, oligoguanylate separations have been carried out at pH 12 using RPC-5 as the packing material. While RPC-5 provides excellent separations, there are several limitations, including the lack of a commercially available source. This report describes a new anion-exchange high-performance liquid chromatography method using HEMA-IEC BIO Q, which successfully separates different forms of the guanosine monomer as well as longer oligoguanylates. The reproducibility and stability at high pH suggests a versatile role for this material.

  18. Quaternary ammonium-functionalized silica sorbents for the solid-phase extraction of aromatic amines under normal phase conditions.

    PubMed

    Vidal, Lorena; Robin, Orlane; Parshintsev, Jevgeni; Mikkola, Jyri-Pekka; Riekkola, Marja-Liisa

    2013-04-12

    Quaternary ammonium-functionalized silica materials were synthesized and applied for solid-phase extraction (SPE) of aromatic amines, which are classified as priority pollutants by US Environmental Protection Agency. Hexamethylenetetramine used for silica surface modification for the first time was employed as SPE sorbent under normal phase conditions. Hexaminium-functionalized silica demonstrated excellent extraction efficiencies for o-toluidine, 4-ethylaniline and quinoline (recoveries 101-107%), while for N,N-dimethylaniline and N-isopropylaniline recoveries were from low to moderate (14-46%). In addition, the suitability of 1-alkyl-3-(propyl-3-sulfonate) imidazolium-functionalized silica as SPE sorbent was tested under normal phase conditions. The recoveries achieved for the five aromatic amines ranged from 89 to 99%. The stability of the sorbent was evaluated during and after 150 extractions. Coefficients of variation between 4.5 and 10.2% proved a high stability of the synthesized sorbent. Elution was carried out using acetonitrile in the case of hexaminium-functionalized silica and water for 1-alkyl-3-(propyl-3-sulfonate) imidazolium-functionalized silica sorbent. After the extraction the analytes were separated and detected by liquid chromatography ultraviolet detection (LC-UV). The retention mechanism of the materials was primarily based on polar hydrogen bonding and π-π interactions. Comparison made with activated silica proved the quaternary ammonium-functionalized materials to offer different selectivity and better extraction efficiencies for aromatic amines. Finally, 1-alkyl-3-(propyl-3-sulfonate) imidazolium-functionalized silica sorbent was successfully tested for the extraction of wastewater and soil samples.

  19. [Simultaneous determination of three antioxidants BHA, BHT and TBHQ in food by liquid chromatography and gas chromatography].

    PubMed

    Yang, Jie; Fang, Congrong; Yang, Dajin

    2013-01-01

    To develop a method for determining 3 kinds of antioxidants in food in same time with HPLC and GC. Firstly, extracted fat with petroleum ether, then extracted antioxidants with 13 ml methnol, centrifuged, repeated the above procedure twice, combined the extracts, next evaporated to 5 ml, constanted volume to 10 ml, then kepted in freezer (- 1h), lastly, the supernatant injected into high performance liquid chromatography (HPLC) and Gas chromatography (GC) which had been optimized condition. The limits of quantitation for BHA,BHT and TBHQ were 0.002, 0.010 and 0.002g/kg respectively in HPLC, The limits of quantitation for BHA, BHT and TBHQ were 0.003, 0.002 and 0.005 g/kg respectively in GC, The mean recoveries at the two spiked levels were 82.8% - 109.0%. There were no significant difference between HPLC and GC. The method can be used to determine the antioxidants in food accurately and sensitively, the comparative results are constant between liquid and gas chromatography.

  20. Determination of statin drugs in hospital effluent with dispersive liquid-liquid microextraction and quantification by liquid chromatography.

    PubMed

    Martins, Ayrton F; Frank, Carla da S; Altissimo, Joseline; de Oliveira, Júlia A; da Silva, Daiane S; Reichert, Jaqueline F; Souza, Darliana M

    2017-08-24

    Statins are classified as being amongst the most prescribed agents for treating hypercholesterolaemia and preventing vascular diseases. In this study, a rapid and effective liquid chromatography method, assisted by diode array detection, was designed and validated for the simultaneous quantification of atorvastatin (ATO) and simvastatin (SIM) in hospital effluent samples. The solid phase extraction (SPE) of the analytes was optimized regarding sorbent material and pH, and the dispersive liquid-liquid microextraction (DLLME), in terms of pH, ionic strength, type and volume of extractor/dispersor solvents. The performance of both extraction procedures was evaluated in terms of linearity, quantification limits, accuracy (recovery %), precision and matrix effects for each analyte. The methods proved to be linear in the concentration range considered; the quantification limits were 0.45 µg L(-1) for ATO and 0.75 µg L(-1) for SIM; the matrix effect was almost absent in both methods and the average recoveries remained between 81.5-90.0%; and the RSD values were <20%. The validated methods were applied to the quantification of the statins in real samples of hospital effluent; the concentrations ranged from 18.8 µg L(-1) to 35.3 µg L(-1) for ATO, and from 30.3 µg L(-1) to 38.5 µg L(-1) for SIM. Since the calculated risk quotient was ≤192, the occurrence of ATO and SIM in hospital effluent poses a potential serious risk to human health and the aquatic ecosystem.

  1. Analysis of drugs of abuse in human plasma by dispersive liquid-liquid microextraction and high-performance liquid chromatography.

    PubMed

    Fernández, P; Regenjo, M; Bermejo, A M; Fernández, A M; Lorenzo, R A; Carro, A M

    2015-04-01

    Opioids and cocaine are widely used at present, both for recreational purposes and as drugs of abuse. This raises the need to develop new analytical methods specifically designed for the simultaneous detection of several drugs of abuse in biological samples. In this work, dispersive liquid-liquid microextraction (DLLME) was assessed as a new sample treatment for the simultaneous extraction of morphine (MOR), 6-acetylmorphine (6AM), cocaine (COC), benzoylecgonine (BZE) and methadone (MET) from human plasma. Preliminary assays were done before developing an experimental design based on a Uniform Network Doehlert which allowed the optimum extraction conditions to be identified, namely: a volume of extractant solvent (chloroform) and dispersant solvent (acetonitrile) of 220 µl and 3.2 ml, respectively; 0.2 g of NaCl as a salting-out additive; pH 10.6 and ultrasound stirring for 3.5 min. The resulting extracts were analyzed by high-performance liquid chromatography with photodiode array detection (HPLC-PDA), using an XBridge® RP18 column (250 × 4.6 mm i.d., 5 µm particle size). Calibration graphs were linear over the concentration range 0.1-10 µg ml⁻¹, and detection limits ranged from 13.9 to 28.5 ng ml⁻¹. Precision calculated at three different concentration levels in plasma was included in the range 0.1-6.8% RSD. Recoveries of the five drugs were all higher than 84% on average. Finally the proposed method was successfully applied to 22 plasma samples from heroin, cocaine and/or methadone users, and the most frequently detected drug was benzoylecgonine, followed by methadone, cocaine and morphine.

  2. Determination of five antiarrhythmic drugs in human plasma by dispersive liquid-liquid microextraction and high-performance liquid chromatography.

    PubMed

    Jouyban, Abolghasem; Sorouraddin, Mohammad Hossein; Farajzadeh, Mir Ali; Somi, Mohammad Hossein; Fazeli-Bakhtiyari, Rana

    2015-03-01

    A fast and sensitive high-performance liquid chromatography (HPLC) method with ultraviolet (UV) detection was developed and validated for the simultaneous quantitation of five antiarrhythmic drugs (metoprolol, propranolol, carvedilol, diltiazem, and verapamil) in human plasma samples. It involves dispersive liquid-liquid microextraction (DLLME) of the desired drugs from 660 µL plasma and separation using isocratic elution with UV detection at 200 nm. The complete separation of all analytes was achieved within 7 min. Acetonitrile (as disperser solvent) resulting from the protein precipitation procedure was mixed with 100 µL dichloromethane (as an extraction solvent) and rapidly injected into 5 mL aqueous solution (pH 11.5) containing 1% (w/v), NaCl. After centrifugation, the sedimented phase containing enriched analytes was collected and evaporated to dryness. The residue was re-dissolved in 50 µL de-ionized water (acidified to pH 3) and injected into the HPLC system for analysis. Under the optimal conditions, the enrichment factors and extraction recoveries ranged between 4.4-10.8 and 33-82%, respectively. The suggested method was linear (r(2) ≥0.997) over a dynamic range of 0.02-0.80 µg mL(-1) in plasma. The intra- and inter-days relative standard deviation (RSD%) and relative error (RE%) values of the method were below 20%, which shows good precision and accuracy. Finally, this method was applied to the analysis of real plasma samples obtained from the patients treated with these drugs.

  3. Comprehensive Profiling of Phytohormones in Honey by Sequential Liquid-Liquid Extraction Coupled with Liquid Chromatography-Mass Spectrometry.

    PubMed

    Wang, Qing; Cai, Wen-Jing; Yu, Lei; Ding, Jun; Feng, Yu-Qi

    2017-01-25

    Honey exhibits various nutritional and medicinal functions, which are highly related to the active components; thus, the exploration of new compounds in honey is of great importance. Because honey is a byproduct of flower nectar, which is rich in phytohormones, the existence of phytohormones in honey is anticipated. In this research, a method for comprehensive profiling of 49 phytohormones in honey was developed by sequential liquid-liquid extraction (LLE) coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS). Good linearities for 49 phytohormones were obtained with correlation coefficients (R) larger than 0.9913. The limits of detection (LODs) were in the range of 0.2-628.2 pg/mL. Satisfied reproducibility and reliability were achieved by evaluation of the intra- and interday precisions with relative standard deviations (RSDs) less than 15.8% and relative recoveries ranging from 80.4 to 123.7%. The method was further applied to analyze the phytohormones in 14 monofloral raw honey samples and 3 commercial honey samples. The existence of 34 phytohormones was confirmed, including 14 cytokinins (CKs), 8 gibberellins (GAs), 5 brassinosteroids (BRs), indole-3-acetic acid (IAA), indole-3-butyric acid (IBA), abscisic acid (ABA), salicylic acid (SA), jasmonic acid (JA), jasmonoyl-leucine (JA-Leu), and jasmonoyl-phenylalanine (JA-Phe). In addition, the content and species of phytohormones varies in different kinds of honey. The study is beneficial to fully illustrate the phytohormone profile of honey and contributive to elucidate the mechanism of its nutritional and medicinal functions.

  4. Determination of tetraalkyllead compounds in gasoline by liquid chromatography-atomic absorption spectrometry

    USGS Publications Warehouse

    Messman, J.D.; Rains, T.C.

    1981-01-01

    A liquid chromatography-atomic absorption spectrometry (LC-AAS) hybrid analytical technique is presented for metal speciation measurements on complex liquid samples. The versatility and inherent metal selectivity of the technique are Illustrated by the rapid determination of five tetraalkyllead compounds in commercial gasoline. Separation of the individual tetraalkyllead species is achieved by reversed-phase liquid chromatography using an acetonitrile/water mobile phase. The effluent from the liquid Chromatograph Is introduced directly into the aspiration uptake capillary of the nebulizer of an air/acetylene flame atomic absorption spectrometer. Spectral interferences due to coeluting hydrocarbon matrix constituents were not observed at the 283.3-nm resonance line of lead used for analysis. Detection limits of this LC-AAS hydrid analytical technique, based on a 20-??L injection, are approximately 10 ng Pb for each tetraalkyllead compound.

  5. Liquid chromatography/mass spectrometry investigation of the impact of thermal processing and storage on peach procyanidins.

    PubMed

    Hong, Yun-Jeong; Barrett, Diane M; Mitchell, Alyson E

    2004-04-21

    Normal-phase liquid chromatography/mass spectrometry (LC/MS) was used to determine the levels and fate of procyanidins in frozen and canned Ross clingstone peaches as well as in the syrup used in the canning over a 3 month period. Procyanidin oligomers, monomers through undecamers, were identified in Ross clingstone peaches. Optimized methods allowed for the quantitation of oligomers through octamers. The profile of procyanidins in peaches is similar to profiles found in grapes, chocolate, and beverages linked to health benefits such as tea and wine. The monomer content in frozen peeled peaches was found to be 19.59 mg/kg. Dimers (39.59 mg/kg) and trimers (38.81 mg/kg) constituted the largest percent composition of oligomers in the peaches. Tetramers through octamers were present in levels of 17.81, 12.43, 10.62, 3.94 and 1.75 mg/kg, respectively. Thermal processing resulted in an 11% reduction in monomers, a 9% reduction in dimers, a 12% reduction in trimers, a 6% reduction in tetramers, and a 5% reduction in pentamers. Hexamers and heptamers demonstrated an approximate 30% loss, and octamers were no longer detected. Analysis of the syrup after thermal processing indicates that there is a migration of procyanidin monomers through hexamers into the syrup that can account for the losses observed during the canning process. Storage of canned peaches for 3 months demonstrated a time-related loss in higher oligomers and that by 3 months oligomers larger than tetramers are not observed. At 3 months postcanning, levels of monomers had decreased by 10%, dimers by 16%, trimers by 45%, and tetramers by 80%. A similar trend was observed in the canning syrup.

  6. Microwave-assisted ionic liquid homogeneous liquid-liquid microextraction coupled with high performance liquid chromatography for the determination of anthraquinones in Rheum palmatum L.

    PubMed

    Wang, Zhibing; Hu, Jianxue; Du, Hongxia; He, Shuang; Li, Qing; Zhang, Hanqi

    2016-06-05

    The microwave-assisted ionic liquid homogeneous liquid-liquid microextraction (MA-IL-HLLME) coupled with high performance liquid chromatography with diode array detection (HPLC-DAD) was developed for the determination of anthraquinones, including aloe-emodin, emodin, chrysophanol and physcion in root of Rheum palmatum L. Several experimental parameters influencing the extraction efficiency, including amount of sample, type and volume of ionic liquid, volume and pH value of extraction medium, microwave power and extraction time, concentration of NH4PF6 as well as centrifugal condition were optimized. When 140μL of ionic liquid ([C8MIM][BF4]) was used as an extraction solvent, target analytes can be extracted from sample matrix in one minute with the help of microwave irradiation. The MA-IL-HLLME is simple and quick. The calibration curves exhibited good linear relationship (r>0.9984). The limits of detection and quantification were in the range of 0.015-0.026 and 0.051-0.088μgmL(-1), respectively. The spiked recovery for each analyte was in the range of 81.13-93.07% with relative standard deviations lower than 6.89%. The present method is free of volatile organic solvents, and represents lower expenditures of sample, extraction time and solvent, compared with ultrasonic and heat reflux extraction. The results indicated that the present method can be successfully applied to the determination of anthraquinones in medicinal plant.

  7. [Determination of five triazine herbicides in infant milk powder by high performance liquid chromatography coupled with ionic liquid-based homogeneous liquid-liquid microextraction].

    PubMed

    Zhang, Liyuan; Yao, Di; Li, Na; Zhang, Hanqi; Yu, Aimin

    2015-07-01

    A high performance liquid chromatography coupled with homogeneous liquid-liquid microextraction was developed for the determination of five triazine herbicides in infant milk powders. The ionic liquid was used as microextraction solvent. The separation of the herbicides was performed on an Eclipse XDB-C18 column using acetonitrile and water as mobile phases in gradient mode. The effects of homogeneous liquid-liquid extraction conditions on the experimental results were investigated in detail. Under the optimized experimental conditions, the calibration curves for determining the analytes were linear and the correlation coefficients were ≥ 0.9992. The limits of detection for cyanazine, desmetryn, terbumeton, terbuthylazine and dimethametryn were 12.1, 13.8, 11.8, 14.6 and 13.7 μg/kg, respectively. The recoveries of the analytes spiked in four infant milk powders ranged from 92.2% to 103.2% and the relative standard deviations were lower than 6%. This method is sensitive, simple, and suitable for the determination of triazine herbicides in milk powder samples.

  8. Identification of Explosives from Porous Materials: Applications Using Reverse Phase High Performance Liquid Chromatography and Gas Chromatography

    SciTech Connect

    C.J. Miller; G. Elias; N.C. Schmitt; C. Rae

    2010-06-01

    High performance liquid chromatography and gas chromatography techniques are well documented and widely used for the detection of trace explosives from organic solvents. These techniques were modified to specifically identify and quantify explosives extracted from various materials taken from people who had recently handled explosives. Documented techniques were modified to specifically detect and quantify RDX, TNT, and PETN from denim, colored flannel, vinyl, and canvas extracted in methanol using no sample cleanup prior to analysis. The methanol extracts were injected directly into several different column types and analyzed by HPLC-UV and/or GC-ECD. This paper describes general screening methods that were used to determine the presence of explosives in unknown samples and techniques that have been optimized for quantification of each explosive from the substrate extracts.

  9. Application in pesticide analysis: Liquid chromatography - A review of the state of science for biomarker discovery and identification

    EPA Science Inventory

    Book Chapter 18, titled Application in pesticide analysis: Liquid chromatography - A review of the state of science for biomarker discovery and identification, will be published in the book titled High Performance Liquid Chromatography in Pesticide Residue Analysis (Part of the C...

  10. Application in pesticide analysis: Liquid chromatography - A review of the state of science for biomarker discovery and identification

    EPA Science Inventory

    Book Chapter 18, titled Application in pesticide analysis: Liquid chromatography - A review of the state of science for biomarker discovery and identification, will be published in the book titled High Performance Liquid Chromatography in Pesticide Residue Analysis (Part of the C...

  11. Analysis of nitroguanidine in Aqueous Solutions by HPLC (High Performance Liquid Chromatography) with electrochemical Detection and Voltammetry

    DTIC Science & Technology

    1987-04-01

    The nitroguanidine was analyzed by high performance liquid chromatography (HPLC) with electrochemical detection at a hanging miercury drop electrode...previously reported on the application of solid sorbent collection techniques to the analysis of several explosives in water by high performance liquid chromatography (HPLC

  12. DETERMINATION OF CARBENDAZIM IN WATER BY HIGH-PERFORMANCE IMMUNOAFFINITY CHROMATOGRAPHY ON-LINE WITH HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY WITH DIODE-ARRAY OR MASS SPECTROMETRIC DETECTION

    EPA Science Inventory

    An automated method for the determination of carbendazim in water that combines high-performance immunoaffinity chromatography (HPIAC), high-performance liquid chromatography (HPLC) in the reversed-phase mode, and detection by either UV-Vis diode array detector (DAD) spectroscopy...

  13. DETERMINATION OF CARBENDAZIM IN WATER BY HIGH-PERFORMANCE IMMUNOAFFINITY CHROMATOGRAPHY ON-LINE WITH HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY WITH DIODE-ARRAY OR MASS SPECTROMETRIC DETECTION

    EPA Science Inventory

    An automated method for the determination of carbendazim in water that combines high-performance immunoaffinity chromatography (HPIAC), high-performance liquid chromatography (HPLC) in the reversed-phase mode, and detection by either UV-Vis diode array detector (DAD) spectroscopy...

  14. The analysis of aqueous mixtures using liquid chromatography-electrospray mass spectrometry

    SciTech Connect

    Johnson, Steven

    1999-02-12

    The focus of this dissertation is the use of chromatographic methods coupled with electrospray mass spectrometry (ES-MS) for the determination of both organic and inorganic compounds in aqueous solutions. The combination of liquid chromatography (LC) methods and ES-MS offers one of the foremost methods for determining compounds in complex aqueous solutions. In this work, LC-ES-MS methods are devised using ion exclusion chromatography, reversed phase chromatography, and ion exchange chromatography, as well as capillary electrophoresis (CE). For an aqueous sample, these LC-ES-MS and CE-ES-MS techniques require no sample preparation or analyte derivatization, which makes it possible to observe a wide variety of analytes as they exist in solution. The majority of this work focuses on the use of LC-ES-MS for the determination of unknown products and intermediates formed during electrochemical incineration (ECI), an experimental waste remediation process. This report contains a general introduction to the project and the general conclusions. Four chapters have been removed for separate processing. Titles are: Chapter 2: Determination of small carboxylic acids by ion exclusion chromatography with electrospray mass spectrometry; Chapter 3: Electrochemical incineration of benzoquinone in aqueous media using a quaternary metal oxide electrode in the absence of a soluble supporting electrolyte; Chapter 4: The determination of electrochemical incineration products of 4-chlorophenol by liquid chromatography-electrospray mass spectrometry; and Chapter 5: Determination of small carboxylic acids by capillary electrophoresis with electrospray mass spectrometry.

  15. Liquid chromatography and supercritical fluid chromatography as alternative techniques to gas chromatography for the rapid screening of anabolic agents in urine.

    PubMed

    Desfontaine, Vincent; Nováková, Lucie; Ponzetto, Federico; Nicoli, Raul; Saugy, Martial; Veuthey, Jean-Luc; Guillarme, Davy

    2016-06-17

    This work describes the development of two methods involving supported liquid extraction (SLE) sample treatment followed by ultra-high performance liquid chromatography or ultra-high performance supercritical fluid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS and UHPSFC-MS/MS) for the screening of 43 anabolic agents in human urine. After evaluating different stationary phases, a polar-embedded C18 and a diol columns were selected for UHPLC-MS/MS and UHPSFC-MS/MS, respectively. Sample preparation, mobile phases and MS conditions were also finely tuned to achieve highest selectivity, chromatographic resolution and sensitivity. Then, the performance of these two methods was compared to the reference routine procedure for steroid analyses in anti-doping laboratories, which combines liquid-liquid extraction (LLE) followed by gas chromatography coupled to tandem mass spectrometry (GC-MS/MS). For this purpose, urine samples spiked with the compounds of interest at five different concentrations were analyzed using the three analytical platforms. The retention and selectivity of the three techniques were very different, ensuring a good complementarity. However, the two new methods displayed numerous advantages. The overall procedure was much faster thanks to high throughput SLE sample treatment using 48-well plates and faster chromatographic analysis. Moreover, the highest sensitivity was attained using UHPLC-MS/MS with 98% of the doping agents detected at the lowest concentration level (0.1ng/mL), against 76% for UHPSFC-MS/MS and only 14% for GC-MS/MS. Finally, the weakest matrix effects were obtained with UHPSFC-MS/MS with 76% of the analytes displaying relative matrix effect between -20 and 20%, while the GC-MS/MS reference method displayed very strong matrix effects (over 100%) for all of the anabolic agents. Copyright © 2016 Elsevier B.V. All rights reserved.

  16. Vortex-assisted liquid-liquid-liquid microextraction (VALLLME) technique: A new microextraction approach for direct liquid chromatography and capillary electrophoresis analysis.

    PubMed

    Makahleh, Ahmad; Yap, Hui Fang; Saad, Bahruddin

    2015-10-01

    A new, rapid and sensitive microextraction technique named vortex-assisted liquid-liquid-liquid microextraction (VALLLME) is proposed. The complete extraction process involves two steps. First, a vortex-assisted liquid-liquid microextraction (VALLME) procedure was used to extract the analytes from a relatively large volume of sample (donor phase) to a small volume of organic solvent (intermediate phase). Next, a micro-vortex-assisted liquid-liquid extraction (µ-VALLE) was used to extract the target analytes from the intermediate phase to a smaller volume of aqueous solution (acceptor phase). The final extract (acceptor phase) can be directly injected into the high performance liquid chromatography or capillary electrophoresis units without any further treatments. The selection of the intermediate phase and the manipulation of pH are key parameters that ensure good extraction efficiency of the technique. The proposed technique has been successfully applied for the determination of carvedilol (used as model analyte) in biological fluid samples. The optimum extraction conditions were: toluene as intermediate phase (150 μL); pH of the donor phase, 9.5; vortex time of the VALLME, 45 s (maximum speed, 2500 rpm); 0.1M HCl (15 μL) as acceptor phase; vortexing time of the µ-VALLME, 75 s (maximum stirring speed, 2500 rpm) and salt concentration in the donor phase, 5% (w/v). Under these conditions, enrichment factors of 51- and 418-fold for VALLME step and VALLLME procedure, respectively, were achieved. Copyright © 2015 Elsevier B.V. All rights reserved.

  17. ANALYSIS OF SELECTED PYRETHROID PESTICIDES USING REVERSE PHASE HIGH PRESSURE LIQUID CHROMATOGRAPHY/UV

    EPA Science Inventory

    This research was conducted in cooperation with EPA Region 4 in Athens, GA to develop a method to analyze selected pyrethroid pesticides using Reverse Phase-High Pressure Liquid Chromatography (HPLC). This HPLC method will aid researchers in separating and identifying these py...

  18. (PRESENT AT NCCU) ANALYSIS OF SELECTED PYRETHROID PESTICIDES USING REVERSE PHASE HIGH LIQUID CHROMATOGRAPHY

    EPA Science Inventory

    This research was conducted in cooperation with EPA Region 4 in Athens, GA to develop a method to analyze selected pyrethroid pesticides using Reverse Phase-High Pressure Liquid Chromatography (HPLC). This HPLC method will aid researchers in separating and identifying these pyre...

  19. MEASUREMENT OF OXIDATIVE STRESS PARAMETERS USING LIQUID CHROMATOGRAPHY - TANDEM MASS SPECTROSCOPY (LC-MS/MS)

    EPA Science Inventory

    What is the study?
    An invited review article. Measurement of oxidative stress parameters using liquid chromatography-tandem mass spectroscopy (LC-MS/MS)
    Why was it done?
    Although oxidative stress is frequently cited as a cause of various adverse biological eff...

  20. DETERMINATION OF CHLOROPHEONIS, NITROPHENOIS AND METHYLPHENOIS IN GROUND-WATER SAMPLES USING HIGH PERFORMANCE LIQUID CHROMATOGRAPHY

    EPA Science Inventory

    A high performance liquid chromatography (HPLC) method was developed to quantitatively determine phenolic compounds and their isomers in aqueous samples. The HPLC method can analyze a mixture of 15 contaminants in the same analytical run with an analysis time of 25 minutes. The...

  1. DETERMINATION OF CHLOROPHENOLS, NITROPHENOLS, AND METHYLPHENOLS IN GROUND-WATER SAMPLES USING HIGH PERFORMANCE LIQUID CHROMATOGRAPHY

    EPA Science Inventory

    A high performance liquid chromatography (HPLC) method was developed to quantitatively determine phenolic compounds and their isomers in aqueous samples. The HPLC method can analyze a mixture of 15 contaminants in the same analytical run with an analysis time of 25 minutes. The...

  2. Quantitative separation of tetralin hydroperoxide from its decomposition products by high performance liquid chromatography

    NASA Technical Reports Server (NTRS)

    Worstell, J. H.; Daniel, S. R.

    1981-01-01

    A method for the separation and analysis of tetralin hydroperoxide and its decomposition products by high pressure liquid chromatography has been developed. Elution with a single, mixed solvent from a micron-Porasil column was employed. Constant response factors (internal standard method) over large concentration ranges and reproducible retention parameters are reported.

  3. Simulated Moving Bed Chromatography: Separation and Recovery of Sugars and Ionic Liquid from Biomass Hydrolysates

    PubMed Central

    Caes, Benjamin R.; Van Oosbree, Thomas R.; Lu, Fachuang; Ralph, John; Maravelias, Christos T.

    2015-01-01

    Simulated moving bed chromatography, a continuous separation method, enables the nearly quantitative recovery of sugar products and ionic liquid solvent from chemical hydrolysates of biomass. The ensuing sugars support microbial growth, and the residual lignin from the process is intact. PMID:23939991

  4. Determination of low molecular weight thiols using monobromobimane fluorescent labeling and high-performance liquid chromatography

    NASA Technical Reports Server (NTRS)

    Fahey, Robert C.; Newton, Gerald L.

    1988-01-01

    Methods are described for the preparation and high-performance liquid chromatography (HPLC) analysis of monobromobimane derivatives of low molecular weight thiols in extracts of biological samples. Typical problems encountered in the development and application of these methods are discussed. Analysis of mung bean extract is used as an example.

  5. The Separation and Identification of Straight Chain Hydrocarbons: An Experiment Using Gas-Liquid Chromatography.

    ERIC Educational Resources Information Center

    Benson, G. A.

    1982-01-01

    An experiment using gas-liquid chromatography is discussed, introducing the student to concept of dead volume and its measurement, idea and use of an internal reference compound, and to linear relationship existing between measurements of a separation on two different stationary phases. (Author/SK)

  6. Extraction and Purification of Glucoraphanin by Preparative High-Performance Liquid Chromatography (HPLC)

    ERIC Educational Resources Information Center

    Lee, Iris; Boyce, Mary C.

    2011-01-01

    A student activity that focuses on the isolation of glucoraphanin from broccoli using preparative high-performance liquid chromatography (HPLC) is presented here. Glucoraphanin is a glucosinolate, whose byproducts are known to possess anticancer properties. It is present naturally at high levels in broccoli and other "Brassica" vegetables. This…

  7. High Performance Liquid Chromatography of Some Analgesic Compounds: An Instrumental Analysis Experiment.

    ERIC Educational Resources Information Center

    Haddad, Paul; And Others

    1983-01-01

    Background information, procedures, and results are provided for an experiment demonstrating techniques of solvent selection, gradient elution, pH control, and ion-pairing in the analysis of an analgesic mixture using reversed-phase liquid chromatography on an octadecylsilane column. Although developed using sophisticated/expensive equipment, less…

  8. A Laboratory Experiment in Pharmaceutical Analysis: Analysis of Diazepam Tablets by High Pressure Liquid Chromatography

    ERIC Educational Resources Information Center

    Bailey, Leonard

    1978-01-01

    The experiment described was developed for the third-year course in inorganic and analytical pharmaceutical chemistry to provide students with "hands-on" experience with high pressure liquid chromatography. Assay procedures are given along with experimental parameters and student results. (LBH)

  9. Benzoin Condensation: Monitoring a Chemical Reaction by High-Pressure Liquid Chromatography

    ERIC Educational Resources Information Center

    Bhattacharya, Apurba; Purohit, Vikram C.; Bellar, Nicholas R.

    2004-01-01

    High-pressure liquid chromatography (HPLC) is the preferred method of separating a variety of materials in complex mixtures such as pharmaceuticals, polymers, soils, food products and biological fluids and is also considered to be a powerful analytical tool in both academia and industry. The use of HPLC analysis as a means of monitoring and…

  10. High-Performance Liquid Chromatography in the Undergraduate Chemical Engineering Laboratory

    ERIC Educational Resources Information Center

    Frey, Douglas D.; Guo, Hui; Karnik, Nikhila

    2013-01-01

    This article describes the assembly of a simple, low-cost, high-performance liquid chromatography (HPLC) system and its use in the undergraduate chemical engineering laboratory course to perform simple experiments. By interpreting the results from these experiments students are able to gain significant experience in the general method of…

  11. Determination of febuxostat in human plasma using ultra-performance liquid chromatography tandem mass spectrometry.

    PubMed

    Lukram, Ojikumar; Parmar, Shivaji; Hande, Amit

    2013-06-01

    A rapid and sensitive liquid chromatography-tandem mass spectrometry method has been developed and validated for the determination of febuxostat in human plasma. The liquid-liquid extraction technique was used for the extraction of febuxostat from human plasma using trandolapril as the internal standard (IS). Chromatography was performed on a ultra-performance liquid chromatography (UPLC) BEH C18, 50 mm X 2.1 mm, 1.7 µm particle size column, with the mobile phase consisting of 0.1% formic acid and acetonitrile (in a 25:75 ratio), followed by detection using mass spectrometry. The method involves a simple reversed isocratic chromatography condition and mass spectrometry detection, which enables detection at sub-microgram levels. The method was validated and the lower limit of quantification for febuxostat was found to be 0.075 µg/ml. The mean recovery for febuxostat ranged from 100.9 to 106.5%. This method increased the sensitivity and selectivity; resulting in high-throughput analysis of febuxostat using commercially available IS for pharmacokinetic, bioavailability, and bioequivalence studies, with a chromatographic run time of 1.5 min only. Copyright © 2012 John Wiley & Sons, Ltd.

  12. MEASUREMENT OF OXIDATIVE STRESS PARAMETERS USING LIQUID CHROMATOGRAPHY - TANDEM MASS SPECTROSCOPY (LC-MS/MS)

    EPA Science Inventory

    What is the study?
    An invited review article. Measurement of oxidative stress parameters using liquid chromatography-tandem mass spectroscopy (LC-MS/MS)
    Why was it done?
    Although oxidative stress is frequently cited as a cause of various adverse biological eff...

  13. High Performance Liquid Chromatography of Some Analgesic Compounds: An Instrumental Analysis Experiment.

    ERIC Educational Resources Information Center

    Haddad, Paul; And Others

    1983-01-01

    Background information, procedures, and results are provided for an experiment demonstrating techniques of solvent selection, gradient elution, pH control, and ion-pairing in the analysis of an analgesic mixture using reversed-phase liquid chromatography on an octadecylsilane column. Although developed using sophisticated/expensive equipment, less…

  14. Analysis of Currently Available Analgesic Tablets by Modern Liquid Chromatography: An Undergraduate Laboratory Introduction to HPLC.

    ERIC Educational Resources Information Center

    Kagel, R. A.; Farwell, S. O.

    1983-01-01

    Background information, procedures, and results, are provided for an undergraduate experiment in which analgesic tablets are analyzed using liquid chromatography. The experiment, an improved, modified version of the Waters Associates Inc. experiment, is simple to prepare, requiring little glassware and minimal sample manipulation by students. (JN)

  15. Sorption of catechins under conditions of reverse-phase high-efficiency liquid chromatography

    NASA Astrophysics Data System (ADS)

    Shafigulin, R. V.; Egorova, K. V.; Bulanova, A. V.

    2010-08-01

    The physico-chemical principles of catechin sorption from various polar solvents onto silica gel modified with octadecyl groups were studied. Thermodynamic characteristics of the sorption were calculated, and the applicability of different models of retention was demonstrated for catechins under the conditions of reverse-phase high-efficiency liquid chromatography.

  16. (PRESENT AT NCCU) ANALYSIS OF SELECTED PYRETHROID PESTICIDES USING REVERSE PHASE HIGH LIQUID CHROMATOGRAPHY

    EPA Science Inventory

    This research was conducted in cooperation with EPA Region 4 in Athens, GA to develop a method to analyze selected pyrethroid pesticides using Reverse Phase-High Pressure Liquid Chromatography (HPLC). This HPLC method will aid researchers in separating and identifying these pyre...

  17. An Advanced, Interactive, High-Performance Liquid Chromatography Simulator and Instructor Resources

    ERIC Educational Resources Information Center

    Boswell, Paul G.; Stoll, Dwight R.; Carr, Peter W.; Nagel, Megan L.; Vitha, Mark F.; Mabbott, Gary A.

    2013-01-01

    High-performance liquid chromatography (HPLC) simulation software has long been recognized as an effective educational tool, yet many of the existing HPLC simulators are either too expensive, outdated, or lack many important features necessary to make them widely useful for educational purposes. Here, a free, open-source HPLC simulator is…

  18. DETERMINATION OF CHLOROPHEONIS, NITROPHENOIS AND METHYLPHENOIS IN GROUND-WATER SAMPLES USING HIGH PERFORMANCE LIQUID CHROMATOGRAPHY

    EPA Science Inventory

    A high performance liquid chromatography (HPLC) method was developed to quantitatively determine phenolic compounds and their isomers in aqueous samples. The HPLC method can analyze a mixture of 15 contaminants in the same analytical run with an analysis time of 25 minutes. The...

  19. DETERMINATION OF CHLOROPHENOLS, NITROPHENOLS, AND METHYLPHENOLS IN GROUND-WATER SAMPLES USING HIGH PERFORMANCE LIQUID CHROMATOGRAPHY

    EPA Science Inventory

    A high performance liquid chromatography (HPLC) method was developed to quantitatively determine phenolic compounds and their isomers in aqueous samples. The HPLC method can analyze a mixture of 15 contaminants in the same analytical run with an analysis time of 25 minutes. The...

  20. Separation of bacterial ubiquinones by reverse-phase high-pressure liquid chromatography.

    PubMed Central

    Moss, C W; Guerrant, G O

    1983-01-01

    A procedure was developed for the separation of ubiquinones by high-pressure liquid chromatography on a reverse-phase C18 column. Ubiquinones Q6 through Q14 were resolved in 20 min and were distinguished from menaquinones by comparing UV spectra at 248 and 275 nm. PMID:6885985

  1. High-Performance Liquid Chromatography in the Undergraduate Chemical Engineering Laboratory

    ERIC Educational Resources Information Center

    Frey, Douglas D.; Guo, Hui; Karnik, Nikhila

    2013-01-01

    This article describes the assembly of a simple, low-cost, high-performance liquid chromatography (HPLC) system and its use in the undergraduate chemical engineering laboratory course to perform simple experiments. By interpreting the results from these experiments students are able to gain significant experience in the general method of…

  2. Comparison of high performance liquid chromatography and enzymatic analysis of soluble carbohydrates in loblolly pine

    Treesearch

    Patricia L. Faulkner; Michele M. Schoeneberger; Kim H. Ludovici

    1993-01-01

    Foliar tissue was collected from a field study designed to test impacts of atmospheric pollutants on loblolIy pine (Pinus taeda L.) seedlings. Standard enzymatic (ENZ) and high performance liquid chromatography (HPLC) methods were used to analyze the tissue for soluble sugars. A comparison of the methods revealed no significant diffennces in accuracy...

  3. Analysis of Currently Available Analgesic Tablets by Modern Liquid Chromatography: An Undergraduate Laboratory Introduction to HPLC.

    ERIC Educational Resources Information Center

    Kagel, R. A.; Farwell, S. O.

    1983-01-01

    Background information, procedures, and results, are provided for an undergraduate experiment in which analgesic tablets are analyzed using liquid chromatography. The experiment, an improved, modified version of the Waters Associates Inc. experiment, is simple to prepare, requiring little glassware and minimal sample manipulation by students. (JN)

  4. An Advanced, Interactive, High-Performance Liquid Chromatography Simulator and Instructor Resources

    ERIC Educational Resources Information Center

    Boswell, Paul G.; Stoll, Dwight R.; Carr, Peter W.; Nagel, Megan L.; Vitha, Mark F.; Mabbott, Gary A.

    2013-01-01

    High-performance liquid chromatography (HPLC) simulation software has long been recognized as an effective educational tool, yet many of the existing HPLC simulators are either too expensive, outdated, or lack many important features necessary to make them widely useful for educational purposes. Here, a free, open-source HPLC simulator is…

  5. Benzoin Condensation: Monitoring a Chemical Reaction by High-Pressure Liquid Chromatography

    ERIC Educational Resources Information Center

    Bhattacharya, Apurba; Purohit, Vikram C.; Bellar, Nicholas R.

    2004-01-01

    High-pressure liquid chromatography (HPLC) is the preferred method of separating a variety of materials in complex mixtures such as pharmaceuticals, polymers, soils, food products and biological fluids and is also considered to be a powerful analytical tool in both academia and industry. The use of HPLC analysis as a means of monitoring and…

  6. Sugar Determination in Foods with a Radially Compressed High Performance Liquid Chromatography Column.

    ERIC Educational Resources Information Center

    Ondrus, Martin G.; And Others

    1983-01-01

    Advocates use of Waters Associates Radial Compression Separation System for high performance liquid chromatography. Discusses instrumentation and reagents, outlining procedure for analyzing various foods and discussing typical student data. Points out potential problems due to impurities and pump seal life. Suggests use of ribose as internal…

  7. Going Beyond, Going Further: An Inexpensive Experiment for the Introduction of High Performance Liquid Chromatography.

    ERIC Educational Resources Information Center

    Bidlingmeyer, Brian A.; Warren, F. Vincent, Jr.

    1984-01-01

    Background information, materials needed, laboratory procedures, and typical results are provided for five high performance liquid chromatography experiments (three isocratic and two step gradient separations). Suggestions for further experimentation are also provided, including quantitative determinations and separation of charged solutes. (JN)

  8. Models of retention of adamantylamidrazones in reversed-phase high-performance liquid chromatography

    NASA Astrophysics Data System (ADS)

    Prokopov, S. V.; Kurbatova, S. V.

    2011-05-01

    Rules governing the chromatographic behavior of some amidrazones of the adamantane series were studied under the conditions of reversed-phase high-performance liquid chromatography. The characteristics of the retention of sorbates in elution by aqueous-acetonitrile phases with various compositions were calculated. Correlations between the structure and physicochemical characteristics of sorbate molecules and their retention were studied.

  9. Extraction and Purification of Glucoraphanin by Preparative High-Performance Liquid Chromatography (HPLC)

    ERIC Educational Resources Information Center

    Lee, Iris; Boyce, Mary C.

    2011-01-01

    A student activity that focuses on the isolation of glucoraphanin from broccoli using preparative high-performance liquid chromatography (HPLC) is presented here. Glucoraphanin is a glucosinolate, whose byproducts are known to possess anticancer properties. It is present naturally at high levels in broccoli and other "Brassica" vegetables. This…

  10. The Separation and Identification of Straight Chain Hydrocarbons: An Experiment Using Gas-Liquid Chromatography.

    ERIC Educational Resources Information Center

    Benson, G. A.

    1982-01-01

    An experiment using gas-liquid chromatography is discussed, introducing the student to concept of dead volume and its measurement, idea and use of an internal reference compound, and to linear relationship existing between measurements of a separation on two different stationary phases. (Author/SK)

  11. ANALYSIS OF SELECTED PYRETHROID PESTICIDES USING REVERSE PHASE HIGH PRESSURE LIQUID CHROMATOGRAPHY/UV

    EPA Science Inventory

    This research was conducted in cooperation with EPA Region 4 in Athens, GA to develop a method to analyze selected pyrethroid pesticides using Reverse Phase-High Pressure Liquid Chromatography (HPLC). This HPLC method will aid researchers in separating and identifying these py...

  12. Recent Advance in Liquid Chromatography/Mass Spectrometry Techniques for Environmental Analysis in Japan

    PubMed Central

    Suzuki, Shigeru

    2014-01-01

    The techniques and measurement methods developed in the Environmental Survey and Monitoring of Chemicals by Japan’s Ministry of the Environment, as well as a large amount of knowledge archived in the survey, have led to the advancement of environmental analysis. Recently, technologies such as non-target liquid chromatography/high resolution mass spectrometry and liquid chromatography with micro bore column have further developed the field. Here, the general strategy of a method developed for the liquid chromatography/mass spectrometry (LC/MS) analysis of environmental chemicals with a brief description is presented. Also, a non-target analysis for the identification of environmental pollutants using a provisional fragment database and “MsMsFilter,” an elemental composition elucidation tool, is presented. This analytical method is shown to be highly effective in the identification of a model chemical, the pesticide Bendiocarb. Our improved micro-liquid chromatography injection system showed substantially enhanced sensitivity to perfluoroalkyl substances, with peak areas 32–71 times larger than those observed in conventional LC/MS. PMID:26819891

  13. Gold nanoparticle decorated graphene oxide/silica composite stationary phase for high-performance liquid chromatography.

    PubMed

    Liang, Xiaojing; Wang, Xusheng; Ren, Haixia; Jiang, Shengxiang; Wang, Licheng; Liu, Shujuan

    2014-06-01

    In the initial phase of this study, graphene oxide (GO)/silica was fabricated by assembling GO onto the silica particles, and then gold nanoparticles (GNPs) were used to modify the GO/silica to prepare a novel stationary phase for high-performance liquid chromatography. The new stationary phase could be used in both reversed-phase chromatography and hydrophilic interaction liquid chromatography modes. Good separations of alkylbenzenes, isomerides, amino acids, nucleosides, and nucleobases were achieved in both modes. Compared with the GO/silica phase and GNPs/silica phase, it is found that except for hydrophilicity, large π-electron systems, hydrophobicity, and coordination functions, this new stationary phase also exhibited special separation performance due to the combination of 2D GO with zero-dimensional GNPs.

  14. 3D printed metal columns for capillary liquid chromatography.

    PubMed

    Sandron, S; Heery, B; Gupta, V; Collins, D A; Nesterenko, E P; Nesterenko, P N; Talebi, M; Beirne, S; Thompson, F; Wallace, G G; Brabazon, D; Regan, F; Paull, B

    2014-12-21

    Coiled planar capillary chromatography columns (0.9 mm I.D. × 60 cm L) were 3D printed in stainless steel (316L), and titanium (Ti-6Al-4V) alloys (external dimensions of ~5 × 30 × 58 mm), and either slurry packed with various sized reversed-phase octadecylsilica particles, or filled with an in situ prepared methacrylate based monolith. Coiled printed columns were coupled directly with 30 × 30 mm Peltier thermoelectric direct contact heater/cooler modules. Preliminary results show the potential of using such 3D printed columns in future portable chromatographic devices.

  15. Determination of pyrrolnitrin and derivatives by gas-liquid chromatography.

    PubMed

    Hamill, R L; Sullivan, H R; Gorman, M

    1969-09-01

    A gas-liquid chromatographic technique was applied to the separation of pyrrolnitrin and its derivatives. The simultaneous use of a flame detector and an electron capture detector made possible the distinction between the nitro derivatives of pyrrolnitrin and the other metabolites. The metabolites could be readily quantitated with the electron capture detector, offering a much more sensitive assay than the flame detector.

  16. Position sensitive radioactivity detection for gas and liquid chromatography

    DOEpatents

    Cochran, Joseph L.; McCarthy, John F.; Palumbo, Anthony V.; Phelps, Tommy J.

    2001-01-01

    A method and apparatus are provided for the position sensitive detection of radioactivity in a fluid stream, particularly in the effluent fluid stream from a gas or liquid chromatographic instrument. The invention represents a significant advance in efficiency and cost reduction compared with current efforts.

  17. Characterization of goat colostrum oligosaccharides by nano-liquid chromatography on chip quadrupole time-of-flight mass spectrometry and hydrophilic interaction liquid chromatography-quadrupole mass spectrometry.

    PubMed

    Martín-Ortiz, A; Salcedo, J; Barile, D; Bunyatratchata, A; Moreno, F J; Martin-García, I; Clemente, A; Sanz, M L; Ruiz-Matute, A I

    2016-01-08

    A detailed qualitative and quantitative characterization of goat colostrum oligosaccharides (GCO) has been carried out for the first time. Defatted and deproteinized colostrum samples, previously treated by size exclusion chromatography (SEC) to remove lactose, were analyzed by nanoflow liquid chromatography-quadrupole-time of flight mass spectrometry (Nano-LC-Chip-Q-TOF MS). Up to 78 oligosaccharides containing hexose, hexosamine, fucose, N-acetylneuraminic acid or N-glycolylneuraminic acid monomeric units were identified in the samples, some of them detected for the first time in goat colostra. As a second step, a hydrophilic interaction liquid chromatography coupled to mass spectrometry (HILIC-MS) methodology was developed for the separation and quantitation of the main GCO, both acidic and neutral carbohydrates. Among other experimental chromatographic conditions, mobile phase additives and column temperature were evaluated in terms of retention time, resolution, peak width and symmetry of target carbohydrates. Narrow peaks (wh: 0.2-0.6min) and good symmetry (As: 0.8-1.4) were obtained for GCO using an acetonitrile:water gradient with 0.1% ammonium hydroxide at 40°C. These conditions were selected to quantify the main oligosaccharides in goat colostrum samples. Values ranging from 140 to 315mgL(-1) for neutral oligosaccharides and from 83 to 251mgL(-1) for acidic oligosaccharides were found. The combination of both techniques resulted to be useful to achieve a comprehensive characterization of GCO.

  18. Characterization of goat colostrum oligosaccharides by nano-liquid chromatography on chip quadrupole time-of-flight mass spectrometry and hydrophilic interaction liquid chromatography-quadrupole mass spectrometry

    PubMed Central

    Martín-Ortiz, A.; Salcedo, J.; Barile, D.; Bunyatratchata, A.; Moreno, F.J.; Martin-García, I.; Clemente, A.; Sanz, M.L.; Ruiz-Matute, A.I.

    2016-01-01

    A detailed qualitative and quantitative characterization of goat colostrum oligosaccharides (GCO) has been carried out for the first time. Defatted and deproteinized colostrum samples, previously treated by size exclusion chromatography (SEC) to remove lactose, were analyzed by nanoflow liquid chromatography-quadrupole-time of flight mass spectrometry (Nano-LC-Chip-Q-TOF MS). Up to 78 oligosaccharides containing hexose, hexosamine, fucose, N-acetylneuraminic acid or N-glycolylneuraminic acid monomeric units were identified in the samples, some of them detected for the first time in goat colostra. As a second step, a hydrophilic interaction liquid chromatography coupled to mass spectrometry (HILIC-MS) methodology was developed for the separation and quantitation of the main GCO, both acidic and neutral carbohydrates. Among other experimental chromatographic conditions, mobile phase additives and column temperature were evaluated in terms of retention time, resolution, peak width and symmetry of target carbohydrates. Narrow peaks (wh: 0.2–0.6 min) and good symmetry (As: 0.8–1.4) were obtained for GCO using an acetonitrile:water gradient with 0.1% ammonium hydroxide at 40 °C. These conditions were selected to quantify the main oligosaccharides in goat colostrum samples. Values ranging from 140 to 315 mg L−1 for neutral oligosaccharides and from 83 to 251 mg L−1 for acidic oligosaccharides were found. The combination of both techniques resulted to be useful to achieve a comprehensive characterization of GCO. PMID:26427327

  19. Nontargeted lipidomic characterization of porcine organs using hydrophilic interaction liquid chromatography and off-line two-dimensional liquid chromatography-electrospray ionization mass spectrometry.

    PubMed

    Cífková, Eva; Holčapek, Michal; Lísa, Miroslav

    2013-09-01

    Lipids form a significant part of animal organs and they are responsible for important biological functions, such as semi-permeability and fluidity of membranes, signaling activity, anti-inflammatory processes, etc. We have performed a comprehensive nontargeted lipidomic characterization of porcine brain, heart, kidney, liver, lung, spinal cord, spleen, and stomach using hydrophilic interaction liquid chromatography (HILIC) coupled to electrospray ionization mass spectrometry (ESI/MS) to describe the representation of individual lipid classes in these organs. Detailed information on identified lipid species inside classes are obtained based on relative abundances of deprotonated molecules [M-H](-) in the negative-ion ESI mass spectra, which provides important knowledge on phosphatidylethanolamines and their different forms of fatty acyl linkage (ethers and plasmalogens), phosphatidylinositols, and hexosylceramides containing nonhydroxy- and hydroxy-fatty acyls. The detailed analysis of identified lipid classes using reversed-phase liquid chromatography in the second dimension was performed for porcine brain to determine more than 160 individual lipid species containing attached fatty acyls of different acyl chain length, double-bond number, and positions on the glycerol skeleton. The fatty acid composition of porcine organs is determined by gas chromatography with flame ionization detection after the transesterification with sodium methoxide.

  20. Ionic liquid-based air-assisted liquid-liquid microextraction followed by high performance liquid chromatography for the determination of five fungicides in juice samples.

    PubMed

    You, Xiangwei; Chen, Xiaochu; Liu, Fengmao; Hou, Fan; Li, Yiqiang

    2018-01-15

    A novel and simple ionic liquid-based air-assisted liquid-liquid microextraction technique combined with high performance liquid chromatography was developed to analyze five fungicides in juice samples. In this method, ionic liquid was used instead of a volatile organic solvent as the extraction solvent. The emulsion was formed by pulling in and pushing out the mixture of aqueous sample solution and extraction solvent repeatedly using a 10mL glass syringe. No organic dispersive solvent was required. Under the optimized conditions, the limits of detection (LODs) were 0.4-1.8μgL(-1) at a signal-to-noise ratio of 3. The limits of quantification (LOQs) set as the lowest spiking levels with acceptable recovery in juices were 10μgL(-1), except for fludioxonil whose LOQ was 20μgL(-1). The proposed method was applied to determine the target fungicides in juice samples, and acceptable recoveries ranging from 74.9% to 115.4% were achieved. Copyright © 2017. Published by Elsevier Ltd.

  1. Vortex-assisted ionic liquid dispersive liquid-liquid microextraction for the determination of sulfonylurea herbicides in wine samples by capillary high-performance liquid chromatography.

    PubMed

    Gure, Abera; Lara, Francisco J; García-Campaña, Ana M; Megersa, Negussie; del Olmo-Iruela, Monsalud

    2015-03-01

    A new sample treatment, namely vortex-assisted ionic liquid dispersive liquid-liquid microextraction (VA-IL-DLLME), followed by capillary liquid chromatography has been developed for the determination of four sulfonylurea herbicides (SUHs): flazasulfuron (FS), prosulfuron (PS), primisulfuron-methyl (PSM) and triflusulfuron-methyl (TSM) in wine samples. The ionic liquid (IL) 1-hexyl-3-methylimidazolium hexafluorophosphate ([C6MIM][PF6]) was used as extraction solvent and was dispersed using methanol into the sample solution, assisted by a vortex mixer. Various parameters influencing the extraction efficiency, such as type and amount of IL, type and volume of disperser solvent, sample pH, salting-out effect, vortex and centrifugation time were studied. Under the optimum conditions, the limits of detection and quantification of the proposed method were in the ranges of 3.2-6.6 and 10.8-22.0 μg kg(-1), respectively; lower than the maximum residue limits set by the EU for these matrices. The proposed method was successfully applied to different wine samples and satisfactory recoveries were obtained.

  2. Ionic-liquid-based dispersive liquid-liquid microextraction combined with high-performance liquid chromatography for the determination of multiclass pesticide residues in water samples.

    PubMed

    Tadesse, Bezuayehu; Teju, Endale; Gure, Abera; Megersa, Negussie

    2015-03-01

    Ionic-liquid-based dispersive liquid-liquid microextraction in combination with high-performance liquid chromatography and diode array detection has been proposed for the simultaneous analysis of four multiclass pesticide residues including carbaryl, methidathion, chlorothalonil, and ametryn from water samples. The major experimental parameters including the type and volume of ionic liquid, sample pH, type, and volume of disperser solvent and cooling time were investigated and optimum conditions were established. Under the optimum experimental conditions, limits of detection and quantification of the method were in the range of 0.1-1.8 and 0.4-5.9 μg/L, respectively, with satisfactory enrichment factors ranging from 10-20. The matrix-matched calibration curves, which were constructed for lake water, as a representative matrix were linear over wide range with coefficients of determination of 0.996 or better. Intra- and interday precisions, expressed as relative standard deviations, were in the range of 1.1-9.7 and 3.1-7.8%, respectively. The relative recoveries of the spiked environmental water samples at one concentration level were in the range of 77-102%. The results of the present study revealed that the proposed method is simple, fast, and uses environmentally friendly extraction solvent for the analysis of the target pesticide residues in environmental water samples.

  3. Detection of Geothermal Phosphite Using High Performance Liquid Chromatography

    PubMed Central

    Pech, Herbe; Henry, Amanda; Khachikian, Crist S.; Salmassi, Tina M.; Hanrahan, Grady; Foster, Krishna L.

    2009-01-01

    Little is known about the pre-biotic mechanisms that initiated the bioavailability of phosphorus, an element essential to life. A better understanding of phosphorus speciation in modern earth environments representative of early earth, may help to elucidate the origins of bioavailable phosphorus. This paper presents the first quantitative measurements of phosphite in a pristine geothermal pool representative of early earth. Phosphite and phosphate were initially identified and quantified in geothermal pool and stream samples at Hot Creek Gorge near Mammoth Lakes, California using suppressed conductivity ion chromatography. Results confirmed the presence of 0.06 ± 0.02 μM of phosphite and 0.05 ± 0.01 μM of phosphate in a geothermal pool. In the stream, phosphite concentrations were below detection limit (0.04 μM) and phosphate was measured at 1.06 ± 0.36 μM. The presence of phosphite in the geothermal pool was confirmed using both chemical oxidation and ion chromatography/mass spectrometry. PMID:19921877

  4. Determination of pyrazon residues in water by reversed phase high performance liquid chromatography.

    PubMed

    Ahmad, I

    1982-01-01

    A simple analytical method is described for the quantitative determination of pyrazon residues in water. It involves high performance liquid chromatography with ultraviolet detection at 270 nm. The procedure is used to determine 2 ppb to 1 ppm levels of pyrazon in water. The traditional liquid-liquid extraction method has been replaced by an adsorption-trapping method for the extraction of pyrazon. Average recovery of pyrazon from the laboratory spiked samples was 98.1%. The method can be used for water samples with concentrations as low as 2 ppb.

  5. Determination of synthetic hormones in animal urine by high-performance liquid chromatography/mass spectrometry.

    PubMed

    Rúbies, Antoni; Cabrera, Albert; Centrich, Francesc

    2007-01-01

    A method was developed for the extraction of stanozolol, taleranol, zeranol, hexestrol, dienestrol, ethynylestradiol, diethylstilbestrol, and trenbolone from animal urine. The analytes were extracted from the matrix by enzymatic hydrolysis, solid-phase extraction, and liquid-liquid extraction. Detection and quantitation were performed on a high-performance liquid chromatography system coupled to a triple quadrupole mass spectrometer. The identification criteria met the European Union regulations. Validation of this method established a decision limit between 0.2 and 0.9 microg/L and a detection capability between 0.3 and 1.0 microg/L, depending on the analyte.

  6. Two-dimensional liquid chromatography analysis of synthetic polymers using fast size exclusion chromatography at high column temperature.

    PubMed

    Im, Kyuhyun; Park, Hae-Woong; Lee, Sekyung; Chang, Taihyun

    2009-05-22

    In recent years, two-dimensional liquid chromatography (2D-LC) has been used increasingly for the analysis of synthetic polymers. A 2D-LC analysis provides richer information than a single chromatography analysis at the cost of longer analysis time. The time required for a comprehensive 2D-LC analysis is essentially proportional to the analysis time of the second dimension separation. Many of 2D-LC analyses of synthetic polymers have employed size exclusion chromatography (SEC) for the second-dimension analysis due to the relatively short analysis time in addition to the wide use in the polymer analysis. Nonetheless, short SEC columns are often used for 2D-LC analyses to reduce the separation time, which inevitably deteriorates the resolution. In this study, we demonstrated that high temperature SEC can be employed as an efficient second-LC in the 2D-LC separation of synthetic polymers. By virtue of high temperature operation (low solvent viscosity and high diffusivity of the polymer molecules), a normal length SEC column can be used at high flow rate with little loss in resolution.

  7. Separation and liquid chromatography using a single carbon nanotube

    PubMed Central

    Singhal, Riju; Mochalin, Vadym N.; Lukatskaya, Maria R.; Friedman, Gary; Gogotsi, Yury

    2012-01-01

    Use of a single template-grown carbon nanotube as a separation column to separate attoliter volumes of binary mixtures of fluorescent dyes has been demonstrated. The cylindrical nanotube walls are used as stationary phase and the surface area is increased by growing smaller multi-walled carbon nanotubes within the larger nanotube column. Liquid-liquid extraction is performed to separate selectively soluble solutes in a solvent, and chromatographic separation is demonstrated using thin, long nanotubes coated inside with iron oxide nanoparticles. The setup is also used to determine the diffusion coefficient of a solute at the sub-micrometer scale. This study opens avenues for analytical chemistry in attoliter volumes of fluids for various applications and cellular analysis at the single cell level. PMID:22798987

  8. Separation and liquid chromatography using a single carbon nanotube.

    PubMed

    Singhal, Riju; Mochalin, Vadym N; Lukatskaya, Maria R; Friedman, Gary; Gogotsi, Yury

    2012-01-01

    Use of a single template-grown carbon nanotube as a separation column to separate attoliter volumes of binary mixtures of fluorescent dyes has been demonstrated. The cylindrical nanotube walls are used as stationary phase and the surface area is increased by growing smaller multi-walled carbon nanotubes within the larger nanotube column. Liquid-liquid extraction is performed to separate selectively soluble solutes in a solvent, and chromatographic separation is demonstrated using thin, long nanotubes coated inside with iron oxide nanoparticles. The setup is also used to determine the diffusion coefficient of a solute at the sub-micrometer scale. This study opens avenues for analytical chemistry in attoliter volumes of fluids for various applications and cellular analysis at the single cell level.

  9. Determination of Pyrrolnitrin and Derivatives by Gas-Liquid Chromatography

    PubMed Central

    Hamill, Robert L.; Sullivan, Hugh R.; Gorman, Marvin

    1969-01-01

    A gas-liquid chromatographic technique was applied to the separation of pyrrolnitrin and its derivatives. The simultaneous use of a flame detector and an electron capture detector made possible the distinction between the nitro derivatives of pyrrolnitrin and the other metabolites. The metabolites could be readily quantitated with the electron capture detector, offering a much more sensitive assay than the flame detector. PMID:5373671

  10. High-performance liquid chromatography of organophosphorus insecticides.

    PubMed

    Szalontai, G

    1976-09-01

    The high-performance liquid chromatographic behaviour of 23 organophosphorus insecticides has been studied on a stainless-steel column packed with silica gel. It has been stated that the usual classification of organophosphorus compounds into phosphonic, phosphoric, thiophosphoric and dithiophosphoric acid ester types gives some information about their adsorption properties. The chromatographic conditions of the analyses and a method for separation of the stereoisomers of tetrachlorvinphos are presented.

  11. Separation of carbohydrates using hydrophilic interaction liquid chromatography.

    PubMed

    Fu, Qing; Liang, Tu; Li, Zhenyu; Xu, Xiaoyong; Ke, Yanxiong; Jin, Yu; Liang, Xinmiao

    2013-09-20

    A strategy was developed to rapidly evaluate chromatographic properties of hydrophilic interaction chromatography (HILIC) columns for separating carbohydrates. Seven HILIC columns (Silica, Diol, TSK Amide-80, XAmide, Click Maltose, Click β-CD, and Click TE-Cys columns) were evaluated by using three monosaccharide and seven disaccharides as probes. The influence of column temperature on the peak shape and tautomerization of carbohydrates, as well as column selectivity were investigated. The influence of surface charge property on the retention was also studied by using glucose, glucuronic acid, and glucosamine, which indicated that buffer salt concentration and pH value in mobile phase was necessary to control the ionic interactions between ionic carbohydrates and HILIC columns. According to evaluation results, the XAmide column was selected as an example to establish experimental schemes for separation of complex mixtures of oligosaccharide.

  12. Simultaneous determination of hypericin and hyperforin in human plasma and serum using liquid-liquid extraction, high-performance liquid chromatography and liquid chromatography-tandem mass spectrometry.

    PubMed

    Pirker, R; Huck, C W; Bonn, G K

    2002-09-25

    A method for the simultaneous extraction of hypericin and hyperforin from a St. John's Wort extract, which is used in case of moderate depressions and skin injuries, from human plasma and serum by liquid-liquid extraction (LLE) with n-hexane-ethylacetate (70:30, w/w) was developed. A reversed-phase high-performance liquid chromatographic (RP-HPLC) method with UV, fluorescence (FLD) and mass spectrometric (MS) detection using electrospray ionization (ESI) was used to identify and quantify hypericin and hyperforin in the extracts from blood samples. Linearity was obtained in the ranges 8.4-28.7 ng/ml (hypericin) and 21.6-242.6 ng/ml (hyperforin). Recoveries were between 32.2 and 35.6% for hypericin and 100.1 and 89.9% for hyperforin. Intra-day accuracy and precision for this method ranged between 3.2 and 4.3% and 2.6 and 2.8%, respectively. After validation of the LLE, the method was tested on real plasma samples which were obtained by ingestion of St. John's Wort extract capsules. Blood samples were taken 2, 4, and 6 h after ingestion. Finally, this method proved to be highly suitable for clinical and pharmacologically relevant studies.

  13. Structural characterization of neutral glycosphingolipids using high-performance liquid chromatography-electrospray ionization mass spectrometry with a repeated high-speed polarity and MSn switching system.

    PubMed

    Ito, Emi; Waki, Hiroaki; Miseki, Kozo; Shimada, Takashi; Sato, Taka-Aki; Kakehi, Kazuaki; Suzuki, Minoru; Suzuki, Akemi

    2013-12-01

    Four types of neutral glycosphingolipids (LacCer, Gb3Cer, Gb4Cer, and IV3αGalNAc-Gb4Cer; 10 pmol each) were analyzed using high-performance liquid chromatography (HPLC)-electrospray ionization quadrupole ion trap time-of-flight (ESI-QIT-TOF) mass spectrometry (MS) with a repeated high-speed polarity and MSn switching system. This system can provide six types of mass spectra, including positive and negative ion MS, MS2, and MS3 spectra, within 1 s per cycle. Using HPLC with a normal-phase column, information on the molecular weights of major molecular species of four neutral glycosphingolipids was obtained by detecting [M+Na]+ in the positive ion mode mass spectra and [M−H]− in the negative ion mode mass spectra. Sequences of glycosphingolipid oligosaccharide were obtained in the negative ion MS2 spectra. In addition, information on the ceramide structures was clearly obtained in the negative ion MS3 mass spectra. GlcCer molecular species were analyzed by HPLC-ESI-QIT-TOF MS with a reversed-phase column using 1 pmole of GlcCer. The structures of the seven molecular species of GlcCer, namely, d18:1-C16:0, d18:1-C18:0, d18:1-C20:0, d18:1-C22:0, d18:1-C23:0, d18:1-C24:1, and d18:1-C24:0, were characterized using positive ion MS and negative ion MS, MS2, and MS3. The established HPLC-ESI-QIT-TOF MS with MSn switching and a normal phase column has been successfully applied to the structural characterization of LacCer and Gb4Cer in a crude mixture prepared from human erythrocytes.

  14. Sensitive determination of nitrophenol isomers by reverse-phase high-performance liquid chromatography in conjunction with liquid-liquid extraction

    USDA-ARS?s Scientific Manuscript database

    A method for the highly sensitive determination of 2-, 3- and 4- nitrophenols was developed using reverse-phase high-performance liquid chromatography (RP-HPLC) with a UV photodiode array detector. Using a reverse-phase column and 40% aqueous acetonitrile as an eluent (i.e. isocratic elution), the i...

  15. Determination of flavanol and procyanidin (by degree of polymerization 1-10) content of chocolate, cocoa liquors, powder(s), and cocoa flavanol extracts by normal phase high-performance liquid chromatography: collaborative study.

    PubMed

    Robbins, Rebecca J; Leonczak, Jadwiga; Li, Julia; Johnson, J Christopher; Collins, Tom; Kwik-Uribe, Catherine; Schmitz, Harold H

    2012-01-01

    An international collaborative study was conducted on an HPLC method with fluorescent detection (FLD) for the determination of flavanols and procyanidins in materials containing chocolate and cocoa. The sum of the oligomeric fractions with degree of polymerization 1-10 was the determined content value. Sample materials included dark and milk chocolates, cocoa powder, cocoa liquors, and cocoa extracts. The content ranged from approximately 2 to 500 mg/g (defatted basis). Thirteen laboratories representing commercial, industrial, and academic institutions in six countries participated in the study. Fourteen samples were sent as blind duplicates to the collaborators. Results from 12 laboratories yielded repeatability relative standard deviation (RSDr) values that were below 10% for all materials analyzed, ranging from 4.17 to 9.61%. The reproducibility relative standard deviation (RSD(R)) values ranged from 5.03 to 12.9% for samples containing 8.07 to 484.7 mg/g. In one sample containing a low content of flavanols and procyanidins (approximately 2 mg/g), the RSD(R) was 17.68%. Based on these results, the method is recommended for Official First Action for the determination of flavanols and procyanidins in chocolate, cocoa liquors, powder(s), and cocoa extracts.

  16. Combined normal-phase and reversed-phase liquid chromatography/ESI-MS as a tool to determine the molecular diversity of A-type procyanidins in peanut skins.

    PubMed

    Appeldoorn, Maaike M; Vincken, Jean-Paul; Sanders, Mark; Hollman, Peter C H; Gruppen, Harry

    2009-07-22

    Peanut skins, a byproduct of the peanut butter industry, are a rich source of proanthocyanidins, which might be used in food supplements. Data on the molecular diversity of proanthocyanidins in peanut skins is limited and conflicting with respect to the ratio of double- (A-type) versus single-linked (B-type) flavan-3-ol units. NP- and RP-HPLC-MS were used as tools to analyze the molecular diversity of proanthocyanidins in a 20% (v/v) methanol extract of peanut skins. NP-HPLC was used to prepurify monomeric to pentameric fractions, which were further separated and characterized by RP-HPLC-MS. With this method, 83 different proanthocyanidin molecular species were characterized and quantified. Furthermore, it was possible to determine that A-type procyanidin oligomers were predominant and represented 95.0% (w/w) of the extract. In addition, the position of the A-linkages in 16 trimers and 27 tetramers could be determined, which in this case appeared to occur at all possible positions. The majority of trimers and tetramers with one or more A-linkage always had an A-linkage at the terminal unit.

  17. Study of the slope of the linear relationship between retention and mobile phase composition (Snyder-Soczewiñski model) in normal phase liquid chromatography with bonded and charge-transfer phases.

    PubMed

    Wu, Di; Lucy, Charles A

    2016-12-02

    The Snyder model and the Soczewiñski model are compared on classic NPLC bonded phases using literature data, and on the charge transfer 2, 4-dinitroanilinopropyl (DNAP) column using experimentally collected data. Overall, the Snyder model slightly better predicts the n-slope than the Soczewiñski model. However, both models give comparable uncertainty in predicting n-slope for a given compound. The number of aromatic double bonds was the most suitable descriptor for estimating the relative n-slope of PAHs, as it correlated with behavior better than the number of aromatic rings and is simpler to calculate than the solute adsorption area. On the DNAP phase, a modified Soczewiñski model is suggested to allow for the significant contribution of the aromatic rings to the n-slope. For classic NPLC bonded phases and DNAP columns, the contribution of polar group to the n-slope parallels the adsorption energy of each polar group. Copyright © 2016 Elsevier B.V. All rights reserved.

  18. Forensic analysis of ignitable liquids in fire debris by comprehensive two-dimensional gas chromatography.

    PubMed

    Frysinger, Glenn S; Gaines, Richard B

    2002-05-01

    The application of comprehensive two-dimensional gas chromatography (GC x GC) for the forensic analysis of ignitable liquids in fire debris is reported. GC x GC is a high resolution, multidimensional gas chromatographic method in which each component of a complex mixture is subjected to two independent chromatographic separations. The high resolving power of GC x GC can separate hundreds of chemical components from a complex fire debris extract. The GC x GC chromatogram is a multicolor plot of two-dimensional retention time and detector signal intensity that is well suited for rapid identification and fingerprinting of ignitable liquids. GC x GC chromatograms were used to identify and classify ignitable liquids, detect minor differences between similar ignitable liquids, track the chemical changes associated with weathering, characterize the chemical composition of fire debris pyrolysates, and detect weathered ignitable liquids against a background of fire debris pyrolysates.

  19. Characterization of sodium carboxymethyl cellulose by comprehensive two-dimensional liquid chromatography.

    PubMed

    Shakun, Maria; Heinze, Thomas; Radke, Wolfgang

    2015-10-05

    Two series of sodium carboxymethyl celluloses (NaCMC) with average degrees of substitution (DS) ranging from 0.45 to 1.55 were synthesized from low molecular mass Avicel cellulose (Avicel samples) and from high molecular mass cotton linters (BWL samples). The samples were characterized by online two-dimensional liquid chromatography using gradient liquid adsorption chromatography in the first and size exclusion chromatography (SEC) in the second dimension. This method allows the simultaneous determination of the chemical composition (DS) and the molar mass distribution within the individual samples. Moreover information was obtained on the dependence of the elution volume in gradient chromatography on molar mass. As expected, evidence for a stronger influence of molar mass on gradient elution volume was found for the low molecular mass NaCMC as compared to the high molecular mass BWL samples. Finally the applicability of the method for the simultaneous separation of blends heterogeneous with respect to chemical composition (DS) and molar mass was demonstrated. Such blends cannot be efficiently separated by either SEC or gradient chromatography alone, nor by simply combining the results of both methods. Only the complete two-dimensional chromatogram can reveal the complexity of such blends, since it reveals the correlations between molar mass and chemical composition.

  20. Determination of Oxidized Phosphatidylcholines by Hydrophilic Interaction Liquid Chromatography Coupled to Fourier Transform Mass Spectrometry

    PubMed Central

    Sala, Pia; Pötz, Sandra; Brunner, Martina; Trötzmüller, Martin; Fauland, Alexander; Triebl, Alexander; Hartler, Jürgen; Lankmayr, Ernst; Köfeler, Harald C.

    2015-01-01

    A novel liquid chromatography-mass spectrometry (LC-MS) approach for analysis of oxidized phosphatidylcholines by an Orbitrap Fourier Transform mass spectrometer in positive electrospray ionization (ESI) coupled to hydrophilic interaction liquid chromatography (HILIC) was developed. This method depends on three selectivity criteria for separation and identification: retention time, exact mass at a resolution of 100,000 and collision induced dissociation (CID) fragment spectra in a linear ion trap. The process of chromatography development showed the best separation properties with a silica-based Kinetex column. This type of chromatography was able to separate all major lipid classes expected in mammalian samples, yielding increased sensitivity of oxidized phosphatidylcholines over reversed phase chromatography. Identification of molecular species was achieved by exact mass on intact molecular ions and CID tandem mass spectra containing characteristic fragments. Due to a lack of commercially available standards, method development was performed with copper induced oxidation products of palmitoyl-arachidonoyl-phosphatidylcholine, which resulted in a plethora of lipid species oxidized at the arachidonoyl moiety. Validation of the method was done with copper oxidized human low-density lipoprotein (LDL) prepared by ultracentrifugation. In these LDL samples we could identify 46 oxidized molecular phosphatidylcholine species out of 99 possible candidates. PMID:25874761

  1. Rapid resolution liquid chromatography for monitoring the quality of stockpiled atropine preparations for injection.

    PubMed

    Zimmermann, Thomas; Dimmel, Andre; Jüttemeyer, Sandra; Springer, Dietmar; Loch, Michael

    2012-01-01

    We describe a rapid resolution liquid chromatography (RRLC) method for analyzing atropine sulfate, its degradation products (tropic acid, apoatropine, atropic acid) and other components (e.g. phenol, methylparaben) in injectable medicines that are used by the German armed forces in emergency situations. Chromatography is performed using an acetonitrile/phosphate buffer gradient (pH = 1.0) and an RP 18 column (50 x 4.6 mm, 1.8 µm) with the detection wavelength set at 220 nm. The concentration of the active ingredient (atropine sulfate) in the tested products ranges from about 1 mg•ml(-1) to 10 mg•ml(-1) . The concentrations of the detected degradation products range from 0.2% to 4.7% (tropic acid) in relation to the active pharmaceutical ingredient (API). Using shorter separation columns and smaller particle sizes of the stationary phase improved analysis time from 40 to 10 min and reduced the consumption of solvents by approximately 75%. Owing to the pressure conditions (< 200 bar), UHPLC (ultra high performance liquid chromatography) systems are not needed. Comparison of the atropine and tropic acid results obtained with the previously used HPLC (high performance liquid chromatography) method of the MAH (marketing authorization holder) show that there is no indication of a significant difference between the two methods. Copyright © 2012 John Wiley & Sons, Ltd.

  2. Comprehensive two-dimensional liquid chromatography for the separation of protonated and deuterated polystyrene.

    PubMed

    Sinha, Pritish; Harding, Gareth W; Maiko, Khumo; Hiller, Wolf; Pasch, Harald

    2012-11-23

    Liquid chromatography at critical conditions (LCCC) has been shown to be a powerful method for the separation of complex polymers regarding chemical composition, functionality, or molecular topology. LCCC has never been used, however, to separate polymers according to the degree of deuteration. This is a very challenging task since polymers shall be separated that are identical regarding molar mass, endgroups and chemical composition. In the present work, critical conditions were established in such a way that one component of a complex mixture elutes at critical conditions, whereas the other component shows size exclusion chromatography (SEC) behaviour. Blends of protonated (h) and deuterated (d) polystyrene (PS) were separated by LCCC at critical conditions of both h-PS and d-PS. Depending on the molar masses of the blend components, baseline separation could be achieved. In order to improve the separation further, comprehensive two-dimensional liquid chromatography was carried out on a number of model blends. In the first dimension LCCC was used, which separated the blends according to isotopic effects whereas in the second dimension the separation took place with respect to hydrodynamic volume. In order to further improve the separation of a number of blends a separation protocol was used where one component shows SEC conditions whereas the other component shows liquid adsorption chromatography (LAC) conditions. This separation protocol was achieved by varying the column temperature.

  3. Identification of Abscisic Acid in Tulipa gesneriana L. by Gas-Liquid Chromatography with Electron Capture and Combined Gas-Liquid Chromatography and Mass Spectrometry

    PubMed Central

    Terry, Paul H.; Aung, Louis H.; De Hertogh, August A.

    1982-01-01

    A major growth inhibitory substance of tulip bulbs (Tulipa gesneriana L. cv Paul Richter) has been unequivocally shown to be abscisic acid (ABA). The ABA methyl ester of the free ether-soluble acid fractions of tulip organs had the identical retention time on gas-liquid chromatography with electron capture detector as authentic ABA methyl ester. In addition, the mass spectra were the same. On a unit dry matter basis, the basalplate and floral shoot contained 3.6 and 2.6 times more ABA than the fleshy scales, respectively. PMID:16662721

  4. Rapid analysis of phentolamine by high-performance liquid chromatography.

    PubMed

    Webster, Gregory K; Lemmer, Robert R; Greenwald, Steven

    2003-02-01

    A rapid liquid chromatographic method is validated for the quantitative analysis of phentolamine. Phentolamine exists in three forms for this investigation: as a mesylate salt, hydrochloride salt, and free base. In solution, phentolamine dissociates from its salt and is chromatographed as free phentolamine. This validation confirms the analysis of each form, which is simply based upon molar mass differences encountered in weighing. As such, both the United States Pharmacopeia hydrochloride and mesylate standards are used throughout this validation to demonstrate this equivalency. The validation demonstrates that this method may be used to quantitate phentolamine, regardless of its salt form.

  5. Capillary liquid chromatography combined with pressurized liquid extraction and dispersive liquid-liquid microextraction for the determination of vitamin E in cosmetic products.

    PubMed

    Viñas, Pilar; Pastor-Belda, Marta; Campillo, Natalia; Bravo-Bravo, María; Hernández-Córdoba, Manuel

    2014-06-01

    Capillary liquid chromatography (LC) is used for the determination of tocopherols and tocotrienols in cosmetic products. Dispersive liquid-liquid microextraction (DLLME) allows the analytes to be preconcentrated into a very small volume of organic solvent which is then injected into the chromatograph running at a very low flow rate. Pressurized liquid extraction (PLE) at a high temperature and pressure was used to isolate vitamin E forms from cosmetics. The Taguchi experimental method was used to optimize the factors affecting DLLME. The parameters selected were 2mL of acetonitrile (disperser solvent), 100μL carbon tetrachloride (extraction solvent) and 10mL aqueous solution. A volume of 5μL of the organic phase was injected into the reversed-phase capillary LC system equipped with a diode array detector and using an isocratic mobile phase composed of an 95:5 (v/v) methanol:water mixture at a flow-rate of 20μLmin(-1). Quantification was carried out using aqueous standards and detection limits were in the range 0.1-0.5ngmL(-1), corresponding to 3-15ngg(-1) in the cosmetic sample. The recoveries were in the 87-105% range, with RSDs lower than 7.8%. The method was validated according to international guidelines and using a certified reference material. Copyright © 2014 Elsevier B.V. All rights reserved.

  6. Ionic-liquid-based dispersive liquid-liquid microextraction coupled with high-performance liquid chromatography for the forensic determination of methamphetamine in human urine.

    PubMed

    Wang, Ruifeng; Qi, Xiujuan; Zhao, Lei; Liu, Shimin; Gao, Shuang; Ma, Xiangyuan; Deng, Youquan

    2016-07-01

    Determination of methamphetamine in forensic laboratories is a major issue due to its health and social harm. In this work, a simple, sensitive, and environmentally friendly method based on ionic liquid dispersive liquid-liquid microextraction combined with high-performance liquid chromatography was established for the analysis of methamphetamine in human urine. 1-Octyl-3-methylimidazolium hexafluorophosphate with the help of disperser solvent methanol was selected as the microextraction solvent in this process. Various parameters affecting the extraction efficiency of methamphetamine were investigated systemically, including extraction solvent and its volume, disperser solvent and its volume, sample pH, extraction temperature, and centrifugal time. Under the optimized conditions, a good linearity was obtained in the concentration range of 10-1000 ng/mL with determination coefficient >0.99. The limit of detection calculated at a signal-to-noise ratio of 3 was 1.7 ng/mL and the relative standard deviations for six replicate experiments at three different concentration levels of 100, 500, and 1000 ng/mL were 6.4, 4.5, and 4.7%, respectively. Meanwhile, up to 220-fold enrichment factor of methamphetamine and acceptable extraction recovery (>80.0%) could be achieved. Furthermore, this method has been successfully employed for the sensitive detection of a urine sample from a suspected drug abuser.

  7. Magnetic ionic liquid-based dispersive liquid-liquid microextraction for the determination of triazine herbicides in vegetable oils by liquid chromatography.

    PubMed

    Wang, Yuanpeng; Sun, Ying; Xu, Bo; Li, Xinpei; Jin, Rui; Zhang, Hanqi; Song, Daqian

    2014-12-19

    Magnetic ionic liquid-based dispersive liquid-liquid microextraction (MIL-based DLLME) was developed for extracting triazine herbicides from vegetable oils. The MIL, 1-hexyl-3-methylimidazolium tetrachloroferrate ([C6mim] [FeCl4]), was used as the microextraction solvent. The magnetic separation time was shortened by simply mixing carbonyl iron powder with the MIL in the sample after DLLME. The effects of several important experimental parameters, including the amount of MIL, the time of ultrasonic extraction, the type and the volume of cleanup solvent were investigated. The MIL-based DLLME coupled with liquid chromatography gave the limits of detection of 1.31-1.49ngmL(-1) and limits of quantification of 4.33-4.91 ng mL(-1) for triazine herbicides. When the present method was applied to the analysis of vegetable oil samples, the obtained recoveries were in the range of 81.8-114.2% and the relative standard deviations were lower than 7.7%. Compared with existing methods, the performances achieved by the present method were acceptable.

  8. Quantitation of antioxidants in water samples using ionic liquid dispersive liquid-liquid microextraction followed by high-performance liquid chromatography-ultraviolet detection.

    PubMed

    Sobhi, Hamid Reza; Kashtiaray, Amir; Farahani, Hadi; Farahani, Mohammad Reza

    2011-01-01

    A simple and efficient method, ionic liquid-based dispersive liquid-liquid microextraction combined with high-performance liquid chromatography-ultraviolet detection (HPLC-UV), has been applied for the extraction and determination of some antioxidants (Irganox 1010, Irganox 1076 and Irgafos 168) in water samples. The microextraction efficiency factors were investigated and optimized: 1-hexyl-3-methylimidazolium hexafluorophosphate [C(6)MIM][PF(6)] (0.06 g) as extracting solvent, methanol (0.5 mL) as disperser solvent without salt addition. Under the selected conditions, enrichment factors up to 48-fold, limits of detection (LODs) of 5.0-10.0 ng/mL and dynamic linear ranges of 25-1500 ng/mL were obtained. A reasonable repeatability (RSD≤11.8%, n=5) with satisfactory linearity (r(2)≥0.9954) of the results illustrated a good performance of the presented method. The accuracy of the method was tested by the relative recovery experiments on spiked samples, with results ranging from 85 to 118%. Finally, the method was successfully applied for determination of the analytes in several real water samples.

  9. Determination of formaldehyde in beverages using microwave-assisted derivatization and ionic liquid-based dispersive liquid-liquid microextraction followed by high-performance liquid chromatography.

    PubMed

    Xu, Xu; Su, Rui; Zhao, Xin; Liu, Zhuang; Li, Dan; Li, Xueyuan; Zhang, Hanqi; Wang, Ziming

    2011-10-15

    A simple method based on simultaneous microwave-assisted derivatization and ionic liquid-based dispersive liquid-liquid microextraction (IL-based DLLME) is proposed for the derivatization, extraction and preconcentration of formaldehyde in beverage samples prior to the determination by high-performance liquid chromatography (HPLC). Formaldehyde was in situ derivatized with 2,4-dinitrophenylhydrazine (DNPH) and simultaneously extracted and preconcentrated by using microwave-assisted derivatization and IL-based DLLME in a single step. Several experimental parameters, including type and volume of extraction solvent, type and volume of disperser, microwave power and irradiation time, volume of DNPH, pH of sample solution, and ionic strength were evaluated. When the microwave power was 120 W, formaldehyde could be derivatized and extracted simultaneously only within 90 s. Under optimal experimental conditions, good linearity was observed in the range of 0.5-50 ng/mL with the correlation coefficient of 0.9965, and the limit of detection was 0.12 ng/mL. The proposed method was applied to the analysis of different beverage samples, and the recoveries of formaldehyde obtained were in the range of 84.9-95.1% with the relative standard deviations lower than 8.4%. The results showed that the proposed method was a rapid, convenient and feasible method for the determination of formaldehyde in beverage samples.

  10. Simultaneous determination of seven anticoagulant rodenticides in agricultural products by gel permeation chromatography and liquid chromatography-tandem mass spectrometry.

    PubMed

    Saito-Shida, Shizuka; Nemoto, Satoru; Matsuda, Rieko; Akiyama, Hiroshi

    2016-11-01

    A sensitive and reliable method for the simultaneous determination of hydroxycoumarin-type (brodifacoum, bromadiolone, coumatetralyl, and warfarin) and indandione-type (chlorophacinone, diphacinone, and pindone) rodenticides in agricultural products by gel permeation chromatography (GPC) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed. The procedure involved extraction of the rodenticides from samples with acetone, followed by liquid-liquid partitioning with hexane/ethyl acetate (1:1, v/v) and 10% sodium chloride aqueous solution, then cleanup using GPC, and finally, analysis using LC-MS/MS. High recoveries from the GPC column were obtained for all rodenticides tested using a mobile phase of acetone/cyclohexane/triethylamine (400:1600:1, v/v/v). An ODS column, which contains low levels of metal impurities, gave satisfactory peak shapes for both hydroxycoumarin- and indandione-type rodenticides in the LC-MS/MS separation. The average recoveries of rodenticides from eight agricultural foods (apple, eggplant, cabbage, orange, potato, tomato, brown rice, and soybean) fortified at 0.0005-0.001 mg/kg ranged from 76 to 116%, except for bromadiolone in orange (53%) and diphacinone in soybean (54%), and the relative standard deviations ranged from 1 to 16%. The proposed method effectively removed interfering components, such as pigments and lipids, and showed high selectivity. In addition, the matrix effects were negligible for most of the rodenticide/food combinations. The results suggest that the proposed method is reliable and suitable for determining hydroxycoumarin- and indandione-type rodenticides in agricultural products.

  11. General methodology for the estimation of common neutral urinary steroids by multi-columin liquid chromatography.

    PubMed

    Vestergaard, P; Sayegh, J F

    1978-01-01

    A method is described for the estimation of common neutral urinary steroids by multi-column liquid chromatography. Hydrolysis is performed in two steps: enzymatically, using beta-glucuronidase, followed by solvolysis. Initial short column chromatography separates the neutral steroids into three fractions according to polarity: 17-oxosteroids, corticosteriods less polar than cortolones, and cortolones and cortols. The cortolone, cortol fraction is oxidized and the different steroid groups are chromatographed on capillary aluminum oxide and silica gel columns. A computerized, spectrophotometric system is used for the quantitation procedure.

  12. Emerging approaches to estimate retention factors in high performance liquid chromatography.

    PubMed

    Bermúdez-Saldaña, José María; Escuder-Gilabert, Laura; Villanueva-Camañas, Rosa María; Medina-Hernández, María José; Sagrado, Salvador

    2005-11-11

    The retention factor is one of the most universally used parameters in chromatography. The errors associated with the conventional ways to determine the retention factor of compounds in liquid chromatography are studied and compared with those corresponding to new approaches. The later avoid the use of extra-column time and hold-up time values, which have proven to be tedious and ambiguous. Simulations and real data, used to examine the accuracy of four different approaches (two classic and two new), suggest that the new approaches could be considered more satisfactory than the classic ones.

  13. Separation of tocopherols by nano-liquid chromatography.

    PubMed

    Fanali, Salvatore; Camera, Emanuela; Chankvetadze, Bezhan; D'Orazio, Giovanni; Quaglia, Maria Giovanna

    2004-04-16

    Nanoliquid chromatography (nano-LC) was used for the separation of tocopherols (delta-, gamma-, alpha-TOH), alpha-tocopherol acetate (alpha-TOH-Ac) and an antioxidant compound, namely butylated hydroxytoluene (BHT) used to prevent TOHs autoxidation. The separation was carried out in a fused silica capillary of 100 microm I.D. and 375 microm O.D. packed in our laboratory with RP18 silica stationary phase of either 5- or 3-microm diameter (23-cm long). The mobile phase was composed by mixtures of methanol (MeOH), acetonitrile (MeCN) and water. Typical analyses time for the separation of all the five components of the mixture were 6-9 min depending on the composition of the mobile phase. Efficiency and resolution were strongly influenced by the particle diameter and the highest Rs and N/m values were observed using 3-microm RP18 particles. Experiments performed with capillaries packed with 3-microm RP18 particles provided good limit of detection (LOD) and limit of quantification (LOQ) (for delta-, gamma-TOH, alpha-TOH-Ac were 4 and 8 microg/ml, while for alpha-TOH were 6 and 10 microg/ml, respectively). The optimized method was applied to extracts of serum and pharmaceutical preparation containing alpha-TOH and alpha-TOH-Ac.

  14. Bridging the gap between gas and liquid chromatography.

    PubMed

    Gritti, Fabrice; Fogwill, Michael; Gilar, Martin; Jarrell, Joseph A

    2016-11-11

    The rapid and complete baseline separation of both volatile (C5 to C16 alkanes in gasoline or terpenes in plant extracts) and non-volatile (>C20 alkanes) organic compounds was achieved by combining (1) low-density fluid chromatography (LDFC) using carbon dioxide at elevated temperature (>90°C) and low pressure (1500psi) designed to increase the retention of the most volatile compounds and (2) high-vacuum technology (<10(-4)Torr) in order to preserve the maximum efficiency of short analytical columns (3.0mm×150mm packed with 1.8μm fully porous HSS-SB-C18 particles) when used in LDFC. The volatile compounds are eluted first under isobaric conditions (1500psi) in less than a minute followed by a linear gradient of the column back pressure (from 1500 to 3500psi in 5min) for the elution of the non-volatile compounds up to C40. The experimental results demonstrate that LDFC performed with short 3.0mm i.d. columns packed with sub-2μm particles and placed under adiabatic conditions enables the analysts to deliver a single, fast, and high-resolution separation of both volatile and non-volatile compounds.

  15. Separation and determination of homogenous fatty alcohol ethoxylates by liquid chromatography with mulitstage mass spectrometry.

    PubMed

    Zembrzuska, Joanna; Budnik, Irena; Lukaszewski, Zenon

    2014-07-01

    Alcohol ethoxylates (AEs) are a significant component of a stream of surfactants directed to the aquatic environment. The aim of this work was the investigation of the dependence of the analytical signals of homogeneous AE homologues on liquid chromatography with tandem mass spectrometry conditions, as well as the separation of AEs from the water matrix and, on this basis, the development of an analytical procedure suitable for the determination of AEs in environmental samples. Homogeneous homologues containing dodecyl moiety and 2-9 oxyethylene subunits were investigated. The analytical signals of the investigated homologues were optimized in terms of concentration of ammonium acetate in the mobile phase (optimum 5 mM) and a column temperature (optimum 35°C) of the liquid chromatography with tandem mass spectrometry system. A separation of AEs from the water matrix by liquid-liquid extraction (ethyl acetate, chloroform) or solid-phase extraction (C18 , styrene divinylbenzene, H-RX) was investigated. In a model investigation, the best recoveries (>90%) were obtained with a styrene divinylbenzene cartridge eluted with a 1:1 mixture of chloroform and methanol. However, much worse recoveries were obtained from the river water sample. Better results were obtained for liquid-liquid extraction with ethyl acetate. Recoveries of 62-80% were obtained for homologues having 4-9 oxyethylene subunits, at the lowest spike.

  16. Coupling of nanoflow liquid chromatography to matrix-assisted laser desorption/ionization mass spectrometry: real-time liquid chromatography run mapping on a MALDI plate.

    PubMed

    Nägele, Edgar; Vollmer, Martin

    2004-01-01

    The major obstacle in the use of matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) instruments in the analysis of complex proteome samples is the lack of a direct coupling of a highly resolving separation technique with the mass spectrometer itself. To overcome this drawback, a spotting device for capillary and nanoflow liquid chromatography (LC) with a special liquid deposition principle for lowest volumes was developed. The instrument is able to perform MALDI spotting in real time in order to deposit the LC run on the MALDI plate, and therefore couples the high resolution power of nano-RP-HPLC separation directly with MALDI-MS. This work describes the development and optimization of a method for spotting with online matrix addition, and illustrates its use in the analysis of a complex proteome sample.

  17. Quantitative analysis of multiple components based on liquid chromatography with mass spectrometry in full scan mode.

    PubMed

    Xu, Min Li; Li, Bao Qiong; Wang, Xue; Chen, Jing; Zhai, Hong Lin

    2016-08-01

    Although liquid chromatography with mass spectrometry in full scan mode can obtain all the signals simultaneously in a large range and low cost, it is rarely used in quantitative analysis due to several problems such as chromatographic drifts and peak overlap. In this paper, we propose a Tchebichef moment method for the simultaneous quantitative analysis of three active compounds in Qingrejiedu oral liquid based on three-dimensional spectra in full scan mode of liquid chromatography with mass spectrometry. After the Tchebichef moments were calculated directly from the spectra, the quantitative linear models for three active compounds were established by stepwise regression. All the correlation coefficients were more than 0.9978. The limits of detection and limits of quantitation were less than 0.11 and 0.49 μg/mL, respectively. The intra- and interday precisions were less than 6.54 and 9.47%, while the recovery ranged from 102.56 to 112.15%. Owing to the advantages of multi-resolution and inherent invariance properties, Tchebichef moments could provide favorable results even in the situation of peaks shifting and overlapping, unknown interferences and noise signals, so it could be applied to the analysis of three-dimensional spectra in full scan mode of liquid chromatography with mass spectrometry.

  18. Direct Measurement of Free Estradiol in Human Serum and Plasma by Equilibrium Dialysis-Liquid Chromatography-Tandem Mass Spectrometry.

    PubMed

    Ray, Julie A; Kushnir, Mark M; Rockwood, Alan L; Meikle, A Wayne

    2016-01-01

    We describe a direct method of measurement of free estradiol using equilibrium dialysis followed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Serum aliquots and internal standards are extracted by liquid-liquid extraction using methyl-tert-butyl ether (MTBE) followed by derivatization with dansyl chloride. An API 5500 mass spectrometer operated in positive electrospray mode is used for detection.

  19. Determination of flunitrazepam in plasma by liquid chromatography.

    PubMed

    Benhamou-Batut, F; Demotes-Mainard, F; Labat, L; Vinçon, G; Bannwarth, B

    1994-07-01

    A reversed-phase liquid chromatographic method has been used to determine flunitrazepam in plasma. Extraction was simple and there was no need to hydrolyse the drug. Separation was achieved on a 150 x 3.9 mm i.d. column packed with 4-microns Nova Pack C18 using a mobile phase of water-acetonitrile-triethylamine (700:300:4, v/v/v) (adjusted to pH 7.5 with orthophosphoric acid). The method was shown to be rapid and reliable with a lower limit of detection of 5 ng ml-1. Results are reported of simple experiments on the effects of temperature and light on the stability of flunitrazepam in plasma kept on the laboratory bench.

  20. Determination of diclazuril in animal feed by liquid chromatography.

    PubMed

    De Kock, J; De Smet, M; Sneyers, R

    1992-07-31

    A method is described for the determination of diclazuril (Janssen Research Compound R64433; trademark Clinacox) in chicken feed at the mg kg(-1) level. Compound R062646, a structure analogous to diclazuril, was used as the interna standard. The drug was extracted from food with acidified methanol. Diclazuril was then isolated by means of solid-phase extraction with a cartridge containing a C18 phase. The eluate was evaporated and the residue redissolved in dimethylformamide. An aliquot was injected onto a reversed-phase high-performance liquid chromatographic column and the drug substance quantified at 280 nm by an ultraviolet detector. Extraction (absolute) recoveries of 85% for both internal standard and diclazuril were obtained. The method is suitable for diclazuril concentrations ranging from 0.1 to 1.5 mg kg(-1). Method validation data are presented.

  1. [Determination of amygdalin in hawthorn by high performance liquid chromatography].

    PubMed

    Lü, Weifeng; Ding, Mingyu

    2005-09-01

    A suitable method for extraction of amygdalin from hawthorn has been established. At first, the lipophilic components were removed with petroleum ether by ultrasonic extraction. The amygdalin was then extracted by methanol in a Soxhlet's apparatus. For quantitation, a high performance liquid chromatographic method was developed by using a reversed-phase C18 column, mobile phase of methanol-water (15:85, v/v) and a detection wavelengh of 215 nm. It can be concluded that the content of amygdalin is higher in the seeds than that in the hawthorn powder without the seeds and the yield of amygdalin is higher in the hawthorn pieces than that in the hawthorn powder.

  2. Determination of diflubenzuron and chlorbenzuron in fruits by combining acetonitrile-based extraction with dispersive liquid-liquid microextraction followed by high-performance liquid chromatography.

    PubMed

    Ruan, Chunqiang; Zhao, Xiang; Liu, Chenglan

    2015-09-01

    In this study, a simple and low-organic-solvent-consuming method combining an acetonitrile-partitioning extraction procedure followed by "quick, easy, cheap, effective, rugged and safe" cleanup with ionic-liquid-based dispersive liquid-liquid microextraction and high-performance liquid chromatography with diode array detection was developed for the determination of diflubenzuron and chlorbenzuron in grapes and pears. Ionic-liquid-based dispersive liquid-liquid microextraction was performed using the ionic liquid 1-hexyl-3-methylimidazolium hexafluorophosphate as the extractive solvent and acetonitrile extract as the dispersive solvent. The main factors influencing the efficiency of the dispersive liquid-liquid microextraction were evaluated, including the extractive solvent type and volume and the dispersive solvent volume. The validation parameters indicated the suitability of the method for routine analyses of benzoylurea insecticides in a large number of samples. The relative recoveries at three spiked levels ranged between 98.6 and 109.3% with relative standard deviations of less than 5.2%. The limit of detection was 0.005 mg/kg for the two insecticides. The proposed method was successfully used for the rapid determination of diflubenzuron and chlorbenzuron residues in real fruit samples.

  3. Nanoparticle Analysis by Online Comprehensive Two-Dimensional Liquid Chromatography combining Hydrodynamic Chromatography and Size-Exclusion Chromatography with Intermediate Sample Transformation

    PubMed Central

    2017-01-01

    Polymeric nanoparticles have become indispensable in modern society with a wide array of applications ranging from waterborne coatings to drug-carrier-delivery systems. While a large range of techniques exist to determine a multitude of properties of these particles, relating physicochemical properties of the particle to the chemical structure of the intrinsic polymers is still challenging. A novel, highly orthogonal separation system based on comprehensive two-dimensional liquid chromatography (LC × LC) has been developed. The system combines hydrodynamic chromatography (HDC) in the first-dimension to separate the particles based on their size, with ultrahigh-performance size-exclusion chromatography (SEC) in the second dimension to separate the constituting polymer molecules according to their hydrodynamic radius for each of 80 to 100 separated fractions. A chip-based mixer is incorporated to transform the sample by dissolving the separated nanoparticles from the first-dimension online in tetrahydrofuran. The polymer bands are then focused using stationary-phase-assisted modulation to enhance sensitivity, and the water from the first-dimension eluent is largely eliminated to allow interaction-free SEC. Using the developed system, the combined two-dimensional distribution of the particle-size and the molecular-size of a mixture of various polystyrene (PS) and polyacrylate (PACR) nanoparticles has been obtained within 60 min. PMID:28745485

  4. Monitoring of cefepime in human serum and plasma by micellar electrokinetic capillary chromatography: Improvement of sample preparation and validation by liquid chromatography coupled to mass spectrometry.

    PubMed

    Šestáková, Nela; Theurillat, Regula; Sendi, Parham; Thormann, Wolfgang

    2017-02-20

    Cefepime monitoring in deproteinized human serum and plasma by micellar electrokinetic capillary chromatography and liquid chromatography coupled to mass spectrometry in presence of other drugs is reported. For micellar electrokinetic capillary chromatography, sample preparation comprised dodecylsulfate protein precipitation at pH 4.5 using an increased buffer concentration compared to that of a previous assay and removal of hydrophobic compounds with dichloromethane. This provided robust conditions for cefepime analysis in the presence of sulfamethoxazole and thus enabled its determination in samples of patients that receive co-trimoxazole. The liquid chromatography assay is based upon use of a column with a pentafluorophenyl-propyl modified and multi-endcapped stationary phase and the coupling to electrospray ionization with a single quadrupole detector. The performances of both assays with multi-level internal calibration were assessed with calibration and control samples and both assays were determined to be robust. Cefepime levels monitored by micellar electrokinetic capillary chromatography in samples from patients that were treated with cefepime only and with cefepime and co-trimoxazole were found to compare well with those obtained by liquid chromatography coupled to mass spectrometry. Cefepime drug levels determined by micellar electrokinetic capillary chromatography could thereby be validated. This article is protected by copyright. All rights reserved.

  5. Rational approach to solvent system selection for liquid-liquid extraction-assisted sample pretreatment in counter-current chromatography.

    PubMed

    Wang, Jiajia; Gu, Dongyu; Wang, Miao; Guo, Xinfeng; Li, Haoquan; Dong, Yue; Guo, Hong; Wang, Yi; Fan, Mengqi; Yang, Yi

    2017-05-15

    A rational liquid-liquid extraction approach was established to pre-treat samples for high-speed counter-current chromatography (HSCCC). n-Hexane-ethyl acetate-methanol-water (4:5:4:5, v/v) and (1:5:1:5, v/v) were selected as solvent systems for liquid-liquid extraction by systematically screening K of target compounds to remove low- and high-polarity impurities in the sample, respectively. After liquid-liquid extraction was performed, 1.4g of crude sample II was obtained from 18.5g of crude sample I which was extracted from the flowers of Robinia pseudoacacia L., and then separated with HSCCC by using a solvent system composed of n-hexane-ethyl acetate-methanol-water (1:2:1:2, v/v). As a result, 31mg of robinin and 37mg of kaempferol 7-O-α-l-rhamnopyranoside were isolated from 200mg of crude sample II in a single run of HSCCC. A scale-up separation was also performed, and 160mg of robinin with 95% purity and 188mg of kaempferol 7-O-α-l-rhamnopyranoside with 97% purity were produced from 1.2g of crude sample II. Copyright © 2017 Elsevier B.V. All rights reserved.

  6. [Determination of N-nitrosodimethylamine in beer by frozen zone melting liquid-liquid extraction/gas chromatography].

    PubMed

    Peng, Qiaorong; Tang, Tao; Yu, Shuxin; Sun, Yuanshe; Lei, Wu; Wang, Fengyun; Zhang, Weibing; Li, Tong

    2014-04-01

    A simple and effective sample enrichment method of frozen zone melting liquid-liquid extraction was optimized and validated for the analysis of trace N-nitrosodimethylamine (NDMA) in beer samples. The method was based on high pressure liquid-liquid extraction with a low temperature frozen step. The 90 mL beer was placed in a container with 10 mL dichloromethane. After agitation, the sample was kept in a freezer for 16 h at -19 degrees C. The organic extract was analyzed by gas chromatography with a flame ionization detector (GC-FID). The accuracy, precision, detection and quantification limits and linearity of the method were evaluated. The results showed that the calibration curve of NDMA was linear in the range of 5-200 mg/L with a good correlation coefficient (r2) of 0.999 6. The recoveries at the spiked levels of 5, 10 and 20 mg/L were 84.94%, 83.24%, 85.14% with the relative standard deviations (n = 7) of 3.06%, 3.19%, 2.63%, respectively. The ordinary extraction method of N-nitrosodimethylamine in beer includes the four steps of low-temperature distillation, liquid-liquid extraction, rotary evaporation and nitrogen blowing concentration. With the extremely low volume of solvent used, the proposed extraction method proved to be easy and simple, and adequate for high-throughput analysis at low cost.

  7. Determination of nitrofurans in animal feeds by liquid chromatography-UV photodiode array detection and liquid chromatography-ionspray tandem mass spectrometry.

    PubMed

    Barbosa, Jorge; Moura, Sara; Barbosa, Rita; Ramos, Fernando; da Silveira, Maria Irene Noronha

    2007-03-14

    Within the EU, the use of nitrofurans is prohibited in food production animals. For this reason detection of these compounds in feedingstuffs, at whatever limit, constitutes an offence under EU legislation. This detection generally involves the use of analytical methods with limits of quantification lowers than 1 mg kg(-1). These procedures are unsuitable for the detection and confirmation of trace amounts of nitrofurans in feedingstuffs due to contamination. It is well known that very low concentrations of these compounds can be the source of residues of nitrofuran metabolites in meat and other edible products obtained from animals consuming the contaminated feed. The present multi-compound method was capable of measuring very low concentrations of nitrofurantoin (NFT), nitrofurazone (NFZ), furazolidone (FZD) and furaltadone (FTD) in animal feed using nifuroxazide (NXZ) as internal standard. Following ethyl acetate extraction at mild alkaline conditions and purification on NH2 column, the nitrofurans are determined using liquid chromatography with photodiode-array detection (LC-DAD). It was observed a CCalpha ranged from 50 to 100 microg kg(-1). The liquid chromatography-tandem mass spectrometric (LC-MS/MS) procedure was used to confirm the identity of the suspected presence of any of the nitrofuran compounds.

  8. Comparison of liquid-liquid extraction-thin layer chromatography with solid-phase extraction-high-performance thin layer chromatography in detection of urinary morphine

    PubMed Central

    Ahadi, Ali; Partoazar, Alireza; Abedi-Khorasgani, Mohammad-Hassan; Shetab-Boushehri, Seyed Vahid

    2011-01-01

    Liquid-liquid extraction-thin layer chromatography (LLE-TLC) has been a common and routine combined method for detection of drugs in biological materials. Solid-phase extraction (SPE) is gradually replacing the traditional LLE method. High performance thin layer chromatography (HPTLC) has several advantages over TLC. The present work studied the higher efficiency of a new SPE-HPTLC method over that of a routine LLE-TLC method, in extraction and detection of urinary morphine. Fifty-eight urine samples, primarily identified as morphine-positive samples by a strip test, were re-screened by LLE-TLC and SPE-HPTLC. The results of LLE-TLC and SPE-HPTLC were then compared with each other. The results showed that the SPE-HPTLC detected 74% of total samples as morphine-positive samples whereas the LLE-TLC detected 48% of the same samples. We further discussed the effect of codeine abuse on TLC analysis of urinary morphine. Regarding the importance of morphine detection in urine, the present combined SPE-HPTLC method is suggested as a replacement method for detection of urinary morphine by many reference laboratories. PMID:23554712

  9. Comparison of liquid-liquid extraction-thin layer chromatography with solid-phase extraction-high-performance thin layer chromatography in detection of urinary morphine.

    PubMed

    Ahadi, Ali; Partoazar, Alireza; Abedi-Khorasgani, Mohammad-Hassan; Shetab-Boushehri, Seyed Vahid

    2011-09-01

    Liquid-liquid extraction-thin layer chromatography (LLE-TLC) has been a common and routine combined method for detection of drugs in biological materials. Solid-phase extraction (SPE) is gradually replacing the traditional LLE method. High performance thin layer chromatography (HPTLC) has several advantages over TLC. The present work studied the higher efficiency of a new SPE-HPTLC method over that of a routine LLE-TLC method, in extraction and detection of urinary morphine. Fifty-eight urine samples, primarily identified as morphine-positive samples by a strip test, were re-screened by LLE-TLC and SPE-HPTLC. The results of LLE-TLC and SPE-HPTLC were then compared with each other. The results showed that the SPE-HPTLC detected 74% of total samples as morphine-positive samples whereas the LLE-TLC detected 48% of the same samples. We further discussed the effect of codeine abuse on TLC analysis of urinary morphine. Regarding the importance of morphine detection in urine, the present combined SPE-HPTLC method is suggested as a replacement method for detection of urinary morphine by many reference laboratories.

  10. Liquid chromatography-mass spectrometric and liquid chromatography-tandem mass spectrometric determination of hallucinogenic indoles psilocin and psilocybin in "magic mushroom" samples.

    PubMed

    Kamata, Tooru; Nishikawa, Mayumi; Katagi, Munehiro; Tsuchihashi, Hitoshi

    2005-03-01

    Accurate and sensitive analytical methods for psilocin (PC) and psilocybin (PB), tryptamine-type hallucinogens contained in "magic mushrooms," were investigated using liquid chromatography-mass spectrometry (LC-MS) and liquid chromatography-tandem mass spectrometry (LC-MS-MS). The chromatographic separation on an ODS column and mass spectral information gave complete discrimination between PC and PB without derivatization. The mass spectrometric detection had a high sensitivity, and the tandem mass spectrometric detection provided more specificity and accuracy, as well as high sensitivity. The detection limits ranged from 1 to 25 pg by LC-MS in the selected ion monitoring mode, and the intra- and inter-day coefficients of variation were estimated to be 4.21-5.93% by LC-MS-MS in the selected reaction monitoring mode. By applying the present LC-MS-MS technique to four real samples, the contents of PC and PB were found to vary over a wide range (0.60-1.4 and 0.18-3.8 mg/g dry wt. for PC and PB, respectively) between samples.

  11. Determination of chloroacetanilide herbicide metabolites in water using high-performance liquid chromatography-diode array detection and high-performance liquid chromatography/mass spectrometry

    USGS Publications Warehouse

    Hostetler, K.A.; Thurman, E.M.

    2000-01-01

    Analytical methods using high-performance liquid chromatography-diode array detection (HPLC-DAD) and high-performance liquid chromatography/mass spectrometry (HPLC/MS) were developed for the analysis of the following chloroacetanilide herbicide metabolites in water: alachlor ethanesulfonic acid (ESA); alachlor oxanilic acid; acetochlor ESA; acetochlor oxanilic acid; metolachlor ESA; and metolachlor oxanilic acid. Good precision and accuracy were demonstrated for both the HPLC-DAD and HPLC/MS methods in reagent water, surface water, and ground water. The average HPLC-DAD recoveries of the chloroacetanilide herbicide metabolites from water samples spiked at 0.25, 0.5 and 2.0 ??g/l ranged from 84 to 112%, with relative standard deviations of 18% or less. The average HPLC/MS recoveries of the metabolites from water samples spiked at 0.05, 0.2 and 2.0 ??g/l ranged from 81 to 118%, with relative standard deviations of 20% or less. The limit of quantitation (LOQ) for all metabolites using the HPLC-DAD method was 0.20 ??g/l, whereas the LOQ using the HPLC/MS method was at 0.05 ??g/l. These metabolite-determination methods are valuable for acquiring information about water quality and the fate and transport of the parent chloroacetanilide herbicides in water. Copyright (C) 2000 Elsevier Science B.V.

  12. Chemical fingerprint of Ganmaoling granule by double-wavelength ultra high performance liquid chromatography and ultra high performance liquid chromatography with quadrupole time-of-flight mass spectrometry.

    PubMed

    Lou, Qiong; Ye, Xiaolan; Zhou, Yingyi; Li, Hua; Song, Fenyun

    2015-06-01

    A method incorporating double-wavelength ultra high performance liquid chromatography with quadrupole time-of-flight mass spectrometry was developed for the investigation of the chemical fingerprint of Ganmaoling granule. The chromatographic separations were performed on an ACQUITY UPLC HSS C18 column (2.1 × 50 mm, 1.8 μm) at 30°C using gradient elution with water/formic acid (1%) and acetonitrile at a flow rate of 0.4 mL/min. A total of 11 chemical constituents of Ganmaoling granule were identified from their molecular weight, UV spectra, tandem mass spectrometry data, and retention behavior by comparing the results with those of the reference standards or literature. And 25 peaks were selected as the common peaks for fingerprint analysis to evaluate the similarities among 25 batches of Ganmaoling granule. The results of principal component analysis and orthogonal projection to latent structures discriminant analysis showed that the important chemical markers that could distinguish the different batches were revealed as 4,5-di-O-caffeoylquinic acid, 3,5-di-O-caffeoylquinic acid, and 4-O-caffeoylquinic acid. This is the first report of the ultra high performance liquid chromatography chemical fingerprint and component identification of Ganmaoling granule, which could lay a foundation for further studies of Ganmaoling granule.

  13. Simultaneous determination of several phytohormones in natural coconut juice by hollow fiber-based liquid-liquid-liquid microextraction-high performance liquid chromatography.

    PubMed

    Wu, Yunli; Hu, Bin

    2009-11-06

    A simple, selective, sensitive and inexpensive method of hollow fiber-based liquid-liquid-liquid microextraction (HF-LLLME) combined with high performance liquid chromatography (HPLC)-ultraviolet (UV) detection was developed for the determination of four acidic phytohormones (salicylic acid (SA), indole-3-acetic acid (IAA), (+/-) abscisic acid (ABA) and (+/-) jasmonic acid (JA)) in natural coconut juice. To the best of our knowledge, this is the first report on the use of liquid phase microextraction (LPME) as a sample pretreatment technique for the simultaneous analysis of several phytohormones. Using phenetole to fill the pores of hollow fiber as the organic phase, 0.1molL(-1) NaOH solution in the lumen of hollow fiber as the acceptor phase and 1molL(-1) HCl as the donor phase, a simultaneous preconcentration of four target phytohormones was realized. The acceptor phase was finally withdrawn into the microsyringe and directly injected into HPLC for the separation and quantification of the target phytohormones. The factors affecting the extraction efficiency of four phytohormones by HF-LLLME were optimized with orthogonal design experiment, and the data was analyzed by Statistical Product and Service Solutions (SPSS) software. Under the optimized conditions, the enrichment factors for SA, IAA, ABA and JA were 243, 215, 52 and 48, with the detection limits (S/N=3) of 4.6, 1.3, 0.9ngmL(-1) and 8.8 microg mL(-1), respectively. The relative standard deviations (RSDs, n=7) were 7.9, 4.9, 6.8% at 50ngmL(-1) level for SA, IAA, ABA and 8.4% at 500 microg mL(-1) for JA, respectively. To evaluate the accuracy of the method, the developed method was applied for the simultaneous analysis of several phytohormones in five natural coconut juice samples, and the recoveries for the spiked samples were in the range of 88.3-119.1%.

  14. Ionic liquid-based ultrasound-assisted dispersive liquid-liquid microextraction followed high-performance liquid chromatography for the determination of ultraviolet filters in environmental water samples.

    PubMed

    Zhang, Yufeng; Lee, Hian Kee

    2012-10-31

    In the present study, a rapid, highly efficient and environmentally friendly sample preparation method named ionic liquid-based ultrasound-assisted dispersive liquid-liquid microextraction (IL-USA-DLLME), followed by high performance liquid chromatography (HPLC) has been developed for the extraction and preconcentration of four benzophenone-type ultraviolet (UV) filters (viz. benzophenone (BP), 2-hydroxy-4-methoxybenzophenone (BP-3), ethylhexyl salicylate (EHS) and homosalate (HMS)) from three different water matrices. The procedure was based on a ternary solvent system containing tiny droplets of ionic liquid (IL) in the sample solution formed by dissolving an appropriate amount of the IL extraction solvent 1-hexyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate ([HMIM][FAP]) in a small amount of water-miscible dispersive solvent (methanol). An ultrasound-assisted process was applied to accelerate the formation of the fine cloudy solution, which markedly increased the extraction efficiency and reduced the equilibrium time. Various parameters that affected the extraction efficiency (such as type and volume of extraction and dispersive solvents, ionic strength, pH and extraction time) were evaluated. Under optimal conditions, the proposed method provided good enrichment factors in the range of 354-464, and good repeatability of the extractions (RSDs below 6.3%, n=5). The limits of detection were in the range of 0.2-5.0 ng mL(-1), depending on the analytes. The linearities were between 1 and 500 ng mL(-1) for BP, 5 and 500 ng mL(-1) for BP-3 and HMS and 10 and 500 ng mL(-1) for EHS. Finally, the proposed method was successfully applied to the determination of UV filters in river, swimming pool and tap water samples and acceptable relative recoveries over the range of 71.0-118.0% were obtained.

  15. Determination of Niacinamide in Lotions and Creams Using Liquid-Liquid Extraction and High-Performance Liquid Chromatography

    ERIC Educational Resources Information Center

    Usher, Karyn M.; Simmons, Carolyn R.; Keating, Daniel W.; Rossi, Henry F., III

    2015-01-01

    Chemical separations are an important part of an undergraduate chemistry curriculum. Sophomore students often get experience with liquid-liquid extraction in organic chemistry classes, but liquid-liquid extraction is not as often introduced as a quantitative sample preparation method in honors general chemistry or quantitative analysis classes.…

  16. Determination of Niacinamide in Lotions and Creams Using Liquid-Liquid Extraction and High-Performance Liquid Chromatography

    ERIC Educational Resources Information Center

    Usher, Karyn M.; Simmons, Carolyn R.; Keating, Daniel W.; Rossi, Henry F., III

    2015-01-01

    Chemical separations are an important part of an undergraduate chemistry curriculum. Sophomore students often get experience with liquid-liquid extraction in organic chemistry classes, but liquid-liquid extraction is not as often introduced as a quantitative sample preparation method in honors general chemistry or quantitative analysis classes.…

  17. Purification of capsular polysaccharide from Neisseria meningitidis serogroup C by liquid chromatography.

    PubMed

    Pato, Tânia Pinheiro; Barbosa, Antonio de Pádua R; da Silva Junior, José Godinho

    2006-03-07

    Neisseria meningitidis serogroup C capsular polysaccharide (MenCPS) is an important antigen against meningococcal infection. This paper describes a new purification methodology employing liquid chromatography that resulted in a polysaccharide showing the characteristics recommended by the World Health Organization for vaccine purposes. In this method, steps of the traditional procedure that yield low recovery and use toxic materials were modified. The present process consists in the following steps: (1) continuous flow centrifugation of the culture for removal of the cells; (2) supernatant concentration by tangential filtration (100 kDa cutoff); (3) addition of 0.5% DOC, heating to 55 degrees C during 30 min and tangential filtration (100 kDa cutoff); (4) anion exchange chromatography (Source 15Q) and (5) size exclusion chromatography (Sepharose CL-4B). The polysaccharide C fraction obtained in that way was dialyzed and freeze-dried. The structural identity of the polysaccharide was demonstrated by (1)H-NMR spectrometry.

  18. Determination of oxyfluorfen herbicide and oxyfluorfen amine residues in garbanzo beans by liquid chromatography.

    PubMed

    Zhou, M; Miles, C J

    1991-01-01

    Oxyfluorfen and oxyfluorfen amine were determined by liquid chromatography (LC) with ultraviolet (UV) and photoconductivity detection (PCD). A simple extraction procedure acceptably recovered both analytes from garbanzo beans over a wide range of fortifications (0.05 to 20 ppm) (83 +/- 4 for oxyfluorfen; 85 +/- 4 for oxyfluorfen amine). Percent recoveries decreased slightly as the fortification level decreased. Both analytes could be determined simultaneously at a concentration greater than 0.2 ppm in garbanzo beans. Detection limits were 3 ng for oxyfluorfen and 100 ng for oxyfluorfen amine using LC/UV, and 12 ng for both oxyfluorfen and oxyfluorfen amine with LC/PCD. Different knitted reaction coils and photoreactors were evaluated. Photoproduct yields and identification were determined by ion chromatography. The LC/PCD method measures oxyfluorfen and oxyfluorfen amine separately and has a shorter analysis time, while the standard method using gas chromatography measures total residues and is more sensitive.

  19. Online coupling of hydrophilic interaction/strong cation exchange/reversed-phase liquid chromatography with porous graphitic carbon liquid chromatography for simultaneous proteomics and N-glycomics analysis.

    PubMed

    Zhao, Yun; Law, Henry C H; Zhang, Zaijun; Lam, Herman C; Quan, Quan; Li, Guohui; Chu, Ivan K

    2015-10-09

    In this study we developed a fully automated three-dimensional (3D) liquid chromatography methodology-comprising hydrophilic interaction separation as the first dimension, strong cation exchange fractionation as the second dimension, and low-pH reversed-phase (RP) separation as the third dimension-in conjunction downstream with additional complementary porous graphitic carbon separation, to capture non-retained hydrophilic analytes, for both shotgun proteomics and N-glycomics analyses. The performance of the 3D system alone was benchmarked through the analysis of the total lysate of Saccharomyces cerevisiae, leading to improved hydrophilic peptide coverage, from which we identified 19% and 24% more proteins and peptides, respectively, relative to those identified from a two-dimensional hydrophilic interaction liquid chromatography and low-pH RP chromatography (HILIC-RP) system over the same mass spectrometric acquisition time; consequently, the 3D platform also provided enhanced proteome and protein coverage. When we applied the integrated technology to analyses of the total lysate of primary cerebellar granule neurons, we characterized a total of 2201 proteins and 16,937 unique peptides for this primary cell line, providing one of its most comprehensive datasets. Our new integrated technology also exhibited excellent performance in the first N-glycomics analysis of cynomolgus monkey plasma; we successfully identified 122 proposed N-glycans and 135 N-glycosylation sites from 122 N-glycoproteins, and confirmed the presence of 38 N-glycolylneuraminic acid-containing N-glycans, a rare occurrence in human plasma, through tandem mass spectrometry for the first time.

  20. High-throughput determination of cortisol, cortisone, and melatonin in oral fluid by on-line turbulent flow liquid chromatography interfaced with liquid chromatography/tandem mass spectrometry.

    PubMed

    Fustinoni, Silvia; Polledri, Elisa; Mercadante, Rosa

    2013-07-15

    Cortisol, cortisone, and melatonin (CORTol, CORTone, and MELA, respectively) are hormones related to stress and sleep disorders. Their detection is relevant to epidemiological studies aimed at investigating the effects of circadian cycle disruption. The aim of this study was to develop and evaluate a high-throughput assay for the detection of CORTol, CORTone, and MELA concentrations in non-invasively collected oral fluid samples. A liquid chromatography/tandem mass spectrometry (LC/MS/MS) method to measure levels of CORTol, CORTone, and MELA in oral fluid samples in the presence of deuterated analogs was optimized and validated. A 50 μL aliquot of oral fluid sample, obtained by centrifugation of a chewed swab, was purified using on-line turbulent flow liquid chromatography. Analytes were then separated using C18 reversed-phase chromatography, subjected to positive ionization using an electrospray source, then quantitated using a triple quadrupole mass detector in the selected reaction monitoring mode. Limits of quantification and linear dynamic ranges were found to be 0.55 nmol/L, 5.5 nmol/L, and 0.004 nmol/L, and up to 28 nmol/L, 277 nmol/L, and 0.43 nmol/L for CORTol, CORTone, and MELA, respectively. Inter- and intra-run precisions as relative standard deviation values were <5%, and accuracies were within 95-106% of theoretical concentrations. An evaluation of matrix effects showed that the use of deuterated analogs controlled sources of bias. Furthermore, the total analysis time per sample was 13 min, resulting in a throughput of approximately 100 samples/day. To our knowledge, this is the first automated, high-throughput assay for the simultaneous quantification of CORTol, CORTone, and MELA in oral fluid specimens. Copyright © 2013 John Wiley & Sons, Ltd.

  1. Determination of acaricides in honey by high-performance liquid chromatography with photodiode array detection.

    PubMed

    Martel, Anne-Claire; Zeggane, Sarah

    2002-04-19

    Rapid analytical methods are described to control quality of honeys, concerning residues of acaricides applied in hives to prevent Varroa jacobsoni infestation. A liquid-liquid extraction with hexane-propanol-2-ammonia (60 ml:30 ml:0.28%) was used for the simultaneous analysis of coumaphos, bromopropylate, amitraz and fluvalinate. For thymol, one clean up on a solid-phase extraction C18 (500 mg, 6 ml) column was performed; for rotenone, a liquid extraction with dichloromethane was realised. Quantitative recoveries obtained with honey were satisfactory and were superior to 80%. All acaricides are identified by reversed-phase high-performance liquid chromatography with photodiode array detection. Quantification limits obtained were below maximal residue limits when these exist.

  2. Liquid chromatography/microspray mass spectrometry for bacterial investigations.

    PubMed

    Krishnamurthy, T; Davis, M T; Stahl, D C; Lee, T D

    1999-01-01

    Cellular proteins (biomarkers) specific to any individual microorganism, determined by the direct mass spectral analysis of the corresponding intact cellular suspension, can be applied for the rapid and specific identification of the organisms present in unknown samples. The components of the bacterial suspensions, after a rapid separation over a C18 reversed-phase microcapillary column, were directly subjected to on-line electrospray ionization followed by analysis using an ion trap tandem mass spectrometer. This approach is equally effective for gram-positive as well as gram-negative bacteria but has a distinct advantage over our earlier reported method involving matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS). During electrospray ionitation mass spectrometry (ESI-MS), liquid samples can be directly analyzed and there is the potential for developing tandem mass spectral methods for more specific identification of the individual organisms present in crude bacterial mixtures. The total analysis time leading to unambiguous bacterial identification in samples was less than 10 minutes and the results were quite reproducible. Miniaturization of the instrumentation along with total automation of this simple process could have immense impact on field operations. Routine, rapid, cost-effective field monitoring of environmental samples, agricultural products, samples from food processing, industrial sites and health institutions for suspected bacterial contamination could be a reality in the near future. Potential utility in biological, medical, bioprocessing, pharmaceutical, and other industrial research is also enormous.

  3. Application of micellar liquid chromatography for the determination of antitumoral and antiretroviral drugs in plasma.

    PubMed

    Peris-Vicente, Juan; Casas-Breva, Inmaculada; Roca-Genovés, Pasqual; Esteve-Romero, Josep

    2014-01-01

    In micellar liquid chromatography, the mobile phase is made of a surfactant and, eventually, an alcohol. This article describes several methods to measure the concentration of antitumoral and antiretroviral drugs in plasma, utilizing micellar liquid chromatography. Samples can be injected after dilution with a micellar solution and filtration, because proteins and other endogenous compounds are solubilized in micellar medium. We will discuss the following optimized parameters: dilution ratio, type of column, detection conditions and mobile phase composition. This article will also cover the validation performed following the International Conference on Harmonization guidelines and the results reported in the literature, indicating that the methods are useful for the routine analysis of plasma samples for clinical purposes.

  4. Current practice of liquid chromatography-mass spectrometry in metabolomics and metabonomics.

    PubMed

    Gika, Helen G; Theodoridis, Georgios A; Plumb, Robert S; Wilson, Ian D

    2014-01-01

    Based on publication and citation numbers liquid chromatography (LC-MS) has become the major analytical technology in the field of global metabolite profiling. This dominance reflects significant investments from both the research community and instrument manufacturers. Here an overview of the approaches taken for LC-MS-based metabolomics research is given, describing critical steps in the realisation of such studies: study design and its needs, specific technological problems to be addressed and major obstacles in data treatment and biomarker identification. The current state of the art for LC-MS-based analysis in metabonomics/metabolomics is described including recent developments in liquid chromatography, mass spectrometry and data treatment as these are applied in metabolomics underlining the challenges, limitations and prospects for metabolomics research. Examples of the application of metabolite profiling in the life sciences focusing on disease biomarker discovery are highlighted. In addition, new developments and future prospects are described. Copyright © 2013 Elsevier B.V. All rights reserved.

  5. Analysis of antimycin A by reversed-phase liquid chromatography/nuclear magnetic-resonance spectrometry

    USGS Publications Warehouse

    Ha, Steven T.K.; Wilkins, Charles L.; Abidi, Sharon L.

    1989-01-01

    A mixture of closely related streptomyces fermentation products, antimycin A, Is separated, and the components are identified by using reversed-phase high-performance liquid chromatography with directly linked 400-MHz proton nuclear magnetic resonance detection. Analyses of mixtures of three amino acids, alanine, glycine, and valine, are used to determine optimal measurement conditions. Sensitivity increases of as much as a factor of 3 are achieved, at the expense of some loss in chromatographic resolution, by use of an 80-μL NMR cell, Instead of a smaller 14-μL cell. Analysis of the antimycin A mixture, using the optimal analytical high performance liquid chromatography/nuclear magnetic resonance conditions, reveals it to consist of at least 10 closely related components.

  6. Emerging liquid chromatography-mass spectrometry technologies improving dried blood spot analysis.

    PubMed

    Rao, Ramisetti Nageswara

    2014-08-01

    Dried blood spots (DBS), a micro blood sampling technique, has recently gained interest in drug discovery and development due to its inherent advantages over the conventional whole blood, plasma or serum sample collection. Since the regulatory authorities have agreed to the use of blood as an acceptable biological matrix for drug exposure measurements, its applications have been extended not only to therapeutic drug monitoring but also to toxicokinetic and pharmacokinetic studies. The pharmaceutical industry is keen to promote DBS as a prominent tool in bioanalytical applications due to the financial, ethical and organizational issues involved in clinical trials. This could be accomplished due to the latest advances in modern analytical technology, particularly liquid chromatography-mass spectrometry. The present review discusses some of the emerging liquid chromatography-mass spectrometry technologies in improving DBS analysis for its innovative applications in the development of new drugs.

  7. Principles and Applications of Liquid Chromatography-Mass Spectrometry in Clinical Biochemistry

    PubMed Central

    Pitt, James J

    2009-01-01

    Liquid chromatography-mass spectrometry (LC-MS) is now a routine technique with the development of electrospray ionisation (ESI) providing a simple and robust interface. It can be applied to a wide range of biological molecules and the use of tandem MS and stable isotope internal standards allows highly sensitive and accurate assays to be developed although some method optimisation is required to minimise ion suppression effects. Fast scanning speeds allow a high degree of multiplexing and many compounds can be measured in a single analytical run. With the development of more affordable and reliable instruments, LC-MS is starting to play an important role in several areas of clinical biochemistry and compete with conventional liquid chromatography and other techniques such as immunoassay. PMID:19224008

  8. Pyrolysis gas-liquid chromatography of the genus Bacillus: effect of growth media on pyrochromatogram reproducibility.

    PubMed

    Oxborrow, G S; Fields, N D; Puleo, J R

    1977-04-01

    Pyrolysis gas-liquid chromatography was performed on dried Bacillus microorganisms to evaluate the effects of growth media. Six cultures of Bacillus and six lot numbers of Trypticase soy agar (BBL) were used to test the hypothesis that a microorganism grown on various lot numbers of the same chromatogram. Also tested was the effect of three different media on chromatogram reproduction using the same six cultures. Results show little or no differences observed between the chromatograms of the individual Bacillus spp. grown on the six lot numbers of Trypticase soy agar. When chromatograms of the three different media were compared, several differences were observed, particularly in the areas most characteristic of individual species. Pryolysis gas-liquid chromatography can be a useful tool for the characterization or identification of the genus Bacillus if the chromatographic and cultural conditions are maintained.

  9. Analysis of glucosylceramides from various sources by liquid chromatography-ion trap mass spectrometry.

    PubMed

    Sugawara, Tatsuya; Aida, Kazuhiko; Duan, Jingjing; Hirata, Takashi

    2010-01-01

    Liquid chromatography-mass spectrometry is one of the most powerful methods for the identification and detection of chemical structures of lipids. In this study, we attempted to identify the chemical structures of glucosylceramides from maize, rice, mushroom (maitake) and sea cucumber by liquid chromatography-ion trap mass spectrometry. For structural analysis of glucosylceramides, [M+H]+, [M+H-18]+ or [M+H-162]+ in the positive scan mode was used for MS/MS analysis to obtain product ion spectra. The typical signals which are characteristic for the sphingoid base moieties were observed while the isomers could not be distinguished. This method should be useful for the structural determination of diverse glucosylceramide molecular species.

  10. Fractionation of Gibberellins in plant extracts by reverse phase high performance liquid chromatography

    SciTech Connect

    Jones, M.G.; Metzger, J.D.; Zeevaart, J.A.D.

    1980-02-01

    In studies on endogenous plant gibberellins (GAs), reverse phase (Bondapak C/sub 18/) high performance liquid chromatography (HPLC) has proved to be a useful method for the fractionation of plant extracts. The behavior of 18 authentic GAs in such a chromatographic system is described. The main factors determining chromatographic behavior are the degree and the position of hydroxylation of the GA. As an illustration of the use of reverse phase HPLC, the endogeneous GAs of immature seeds of Pharbitis nil L., strain Violet, were reinvestigated. The presence of gibberellins A/sub 3/, A/sub 5/, A/sub 17/, A/sub 20/, and A/sub 29/ was confirmed by gas-liquid chromatography-mass spectrometry. In addition, two other GAs, A/sub 19/ and A/sub 44/, were also identified in extracts of this material.

  11. Gas-liquid chromatography in routine processing of blood cultures for detecting anaerobic bacteraemia.

    PubMed Central

    Reig, M; Molina, D; Loza, E; Ledesma, M A; Meseguer, M A

    1981-01-01

    Gas-liquid chromatography was performed on 233 positive blood cultures and findings were compared with culture results. Obligate anaerobic bacteria were recovered from 78 out of 79 blood cultures containing butyric or iso-valeric acids, or both; from 28 out of 69 blood cultures containing succinic acid; and from only one out of 41 blood cultures containing succinic but not butyric or iso-valeric acid. Good correlations (88%) were found for the recovery of anaerobic bacteria and the detection of butyric and/or iso-valeric acids. Detecting volatile fatty acids by gas-liquid chromatography performed on blood cultures at the first signs of growth can therefore provide an early and reliable indication of the presence of anaerobic bacteria. PMID:7014645

  12. Liquid chromatography-thermospray mass spectrometry of DNA adducts formed with mitomycin C, porfiromycin and thiotepa.

    PubMed

    Musser, S M; Pan, S S; Callery, P S

    1989-07-14

    High-performance liquid chromatography (HPLC) and thermospray mass spectrometry were combined for the analysis of DNA adducts formed from the interaction of the anticancer drugs mitomycin C, porfiromycin and thiotepa with calf thymus DNA. The adducts formed from reaction of mitomycin C and porfiromycin with DNA were separated from unmodified nucleosides by HPLC on a C18 column and identified by thermospray mass spectrometry. Thiotepa DNA adducts readily depurinated from DNA and were chromatographed and identified by thermospray liquid chromatography-mass spectrometry as the modified bases without the ribose moiety attached. The utility of thermospray mass spectrometry for the identification of microgram quantities of nucleoside adducts and depurinated base adducts of these anticancer drugs was demonstrated.

  13. Identification of bupropion urinary metabolites by liquid chromatography/mass spectrometry.

    PubMed

    Petsalo, Aleksanteri; Turpeinen, Miia; Tolonen, Ari

    2007-01-01

    Human urinary metabolism of the antidepressant bupropion was studied using liquid chromatography/time-of-flight mass spectrometry (LC/TOFMS) and liquid chromatography/tandem mass spectrometry (LC/MS/MS). A total of 20 metabolites were detected and identified. The phase I metabolism included formation of morpholinohydroxybupropion, threo- and erythrohydrobupropion, aromatic hydroxylation, butyl group hydroxylation with ketone hydrogenation and dihydroxylation. These metabolites were detected either as the free form or as glucuronide and/or sulphate conjugates. In addition also m-chlorohippuric acid was detected. Of the phase I metabolites, a dihydroxylation to the aromatic ring and to the methyl group in the middle of the substrate molecule was reported here for the first time, as well as eight of the glucuronide conjugates (to hydroxy, dihydroxy, hydroxy and hydrogenation metabolites) and three of the sulphate conjugates (to aromatic hydroxy and hydroxy and hydrogenation metabolites). Copyright (c) 2007 John Wiley & Sons, Ltd.

  14. High-pressure liquid chromatography with direct injection of gas sample.

    PubMed

    Astanin, Anton I; Baram, Grigory I

    2017-06-09

    The conventional method of using liquid chromatography to determine the composition of a gaseous mixture entails dissolving vapors in a suitable solvent, then obtaining a chromatograph of the resulting solution. We studied the direct introduction of a gaseous sample into a C18 reversed-phase column, followed by separation of the components by HPLC with UV detection. Since the chromatography was performed at high pressure, vapors readily dissolved in the eluent and the substances separated in the column as effectively as in liquid samples. Samples were injected into the column in two ways: a) through the valve without a flow stop; b) after stopping the flow and relieving all pressure. We showed that an injectable gas volume could reach 70% of column dead volume. When an injected gaseous sample volume was less than 10% of the column dead volume, the resulting peaks were symmetrical and the column efficiency was high. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. [Measurement of proinsulin, insulin and C-peptide in human blood by high performance liquid chromatography].

    PubMed

    Povazhenko, A A; Ryzhova, T I; Kozyreva, E V

    1997-09-01

    The technique of measuring insulin, proinsulin, and C-peptide in human blood by high-pressure liquid chromatography is described. Donors, subjects with abnormal glucose tolerance, and patients with type I diabetes were examined. The main advantage of the method over radioimmunoassay and enzyme immunoassay is the possibility of simultaneous differentiated measurement of human insulin and animal hormone administered parenterally, and separation of insulin and its precursor on the basis of difference in molecular weight and charge of molecules. The results indicate that patients with type I diabetes retain the secretion of endogenous insulin, although its level is appreciably lower than in healthy donors, and the structure of its molecules is heterogeneous, which is proven by a biphasic chromatographic peak. Inhibition of proinsulin transformation into insulin is one probable mechanism of impairment of glucose tolerance. High-pressure liquid chromatography can be used at clinical laboratories for examinations of diabetics.

  16. Analyses of acute kidney injury biomarkers by ultra-high performance liquid chromatography with mass spectrometry.

    PubMed

    Al Za'abi, Mohammed; Ali, Badreldin H; ALOthman, Zeid A; Ali, Imran

    2016-01-01

    The newly developed acute kidney injury biomarkers are very important for the early and timely detection of kidney diseases. This review contains details of the analyses of several acute kidney injury biomarkers using ultra-high performance liquid chromatography-mass spectrometry in urine and plasma samples. In this review we attempt to discuss some aspects of the types of the biomarkers, patents, sample preparation, and the analyses. Besides, efforts were also made to discuss the possible uses of superficially porous (core-shell) columns in traditional and inexpensive high-performance liquid chromatography instruments. Additionally, the challenges and the future prospects are also highlighted. The present review will be useful for the academicians, scientists, and clinicians for the early detection of acute kidney injury biomarkers.

  17. Ultrahigh-pressure liquid chromatography: fundamental aspects of compression and decompression heating.

    PubMed

    Gilpin, R K; Zhou, W

    2008-03-01

    Ultrahigh-pressure liquid chromatography is an emerging technique for carrying out rapid and highly efficient separations. Unfortunately, one of the simplifying assumptions made in conventional high-performance liquid chromatography, incompressibility of the mobile phase, is not valid when higher and higher pressures are used. Rather, both compression and decompression of the eluent must be considered in terms of both heating and changes in the solvent's structure. The first of these problems, eluent heating during the compression and decompression cycles, which occurs in the pump and column, respectively, are considered in terms of a combined first principle-empirical approach that is solved (i.e., an analytic solution obtained from the resulting integral equation) using 0.01 Bar pressure steps. The approach is used to estimate compression and decompression heating for methanol and water.

  18. Fully automated multifunctional ultrahigh pressure liquid chromatography system for advanced proteome analyses

    SciTech Connect

    Lee, Jung Hwa; Hyung, Seok-Won; Mun, Dong-Gi; Jung, Hee-Jung; Kim, Hokeun; Lee, Hangyeore; Kim, Su-Jin; Park, Kyong Soo; Moore, Ronald J.; Smith, Richard D.; Lee, Sang-Won

    2012-08-03

    A multi-functional liquid chromatography system that performs 1-dimensional, 2-dimensional (strong cation exchange/reverse phase liquid chromatography, or SCX/RPLC) separations, and online phosphopeptides enrichment using a single binary nano-flow pump has been developed. With a simple operation of a function selection valve, which is equipped with a SCX column and a TiO2 (titanium dioxide) column, a fully automated selection of three different experiment modes was achieved. Because the current system uses essentially the same solvent flow paths, the same trap column, and the same separation column for reverse-phase separation of 1D, 2D, and online phosphopeptides enrichment experiments, the elution time information obtained from these experiments is in excellent agreement, which facilitates correlating peptide information from different experiments.

  19. Atmospheric pressure chemical ionisation liquid chromatography/mass spectrometry of bacteriochlorophylls from Chlorobiaceae: characteristic fragmentations.

    PubMed

    Airs, Ruth L; Keely, Brendan J

    2002-01-01

    Atmospheric pressure chemical ionisation liquid chromatography/mass spectrometry/mass spectrometry (APCI-LC/MS/MS) has been applied to the study of bacteriochlorophylls c, d, and e of phototrophic prokaryotes. Cultures of Chlorobiaceae containing bacteriochlorophyll c, d or e were examined using a high-resolution high-performance liquid chromatography (HPLC) method and APCI-LC/MS/MS employing post-column addition of formic acid. The results reveal complex distributions of bacteriochlorophyll homologues, with some closely eluting species giving isobaric protonated molecules. On-line LC/MS/MS studies reveal characteristic fragment ions for bacteriochlorophylls c, d, and e. Fragmentations involving loss of the extended alkyl substituents that are unique to bacteriochlorophylls c, d and e and their derivatives have been rationalised by studying the phaeophorbides and the results applied to the direct study of the bacteriochlorophylls.

  20. Ultrasound-assisted dispersive liquid-liquid microextraction combined with high-performance liquid chromatography-fluorescence detection for sensitive determination of biogenic amines in rice wine samples.

    PubMed

    Huang, Ke-Jing; Wei, Cai-Yun; Liu, Wei-Li; Xie, Wan-Zhen; Zhang, Jun-Feng; Wang, Wei

    2009-09-18

    Ultrasound-assisted dispersive liquid-liquid microextraction coupled with high-performance liquid chromatography-fluorescence detection was used for the extraction and determination of three biogenic amines including octopamine, tyramine and phenethylamine in rice wine samples. Fluorescence probe 2,6-dimethyl-4-quinolinecarboxylic acid N-hydroxysuccinimide ester was applied for derivatization of biogenic amines. Acetonitrile and 1-octanol were used as disperser solvent and extraction solvent, respectively. Extraction conditions including the type of extraction solvent, the volume of extraction solvent, ultrasonication time and centrifuging time were optimized. After extraction and centrifuging, analyte was injected rapidly into high-performance liquid chromatography and then detected with fluorescence. The calibration graph of the proposed method was linear in the range of 5-500 microg mL(-1) (octopamine and tyramine) and 0.025-2.5 microg mL(-1) (phenethylamine). The relative standard deviations were 2.4-3.2% (n=6) and the limits of detection were in the range of 0.02-5 ng mL(-1). The method was applied to analyze the rice wine samples and spiked recoveries in the range of 95.42-104.56% were obtained. The results showed that ultrasound-assisted dispersive liquid-liquid microextraction was a very simple, rapid, sensitive and efficient analytical method for the determination of trace amount of biogenic amines.