On-line comprehensive two-dimensional normal-phase liquid chromatography×reversed-phase liquid chromatography for preparative isolation of toad venom.

PubMed

Li, Jia-Fu; Fang, Hua; Yan, Xia; Chang, Fang-Rong; Wu, Zhen; Wu, Yun-Long; Qiu, Ying-Kun

2016-07-22

An on-line comprehensive preparative two-dimensional normal-phase liquid chromatography×reversed-phase liquid chromatography (2D NPLC×RPLC) system was constructed with a newly developed vacuum evaporation assisted adsorption (VEAA) interface, allowing fast removal of NPLC solvent in the vacuum condition and successfully solving the solvent incompatibility problem between NPLC and RPLC. The system achieved on-line solvent exchange within the two dimensions and its performance was illustrated by gram-scale isolation of crude extract from the venom of Bufo bufo gargarizans. Within separation time of ∼20h, 19 compounds were obtained with high purity in a single run. With the VEAA interface, the 2D system exhibited apparent advantages in separation efficiency and automation compared with conventional methods, indicating its promising application in the routine separation process for complicated natural products. Copyright © 2016 Elsevier B.V. All rights reserved.

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. Copyright © 2017 Elsevier B.V. All rights reserved.

Two-Dimensional Liquid Chromatography Analysis of Polystyrene/Polybutadiene Block Copolymers.

PubMed

Lee, Sanghoon; Choi, Heejae; Chang, Taihyun; Staal, Bastiaan

2018-05-15

A detailed characterization of a commercial polystyrene/polybutadiene block copolymer material (Styrolux) was carried out using two-dimensional liquid chromatography (2D-LC). The Styrolux is prepared by statistical linking reaction of two different polystyrene- block-polybutadienyl anion precursors with a multivalent linking agent. Therefore, it is a mixture of a number of branched block copolymers different in molecular weight, composition, and chain architecture. While individual LC analysis, including size exclusion chromatography, interaction chromatography, or liquid chromatography at critical condition, is not good enough to resolve all the polymer species, 2D-LC separations coupling two chromatography methods were able to resolve all polymer species present in the sample; at least 13 block copolymer species and a homopolystyrene blended. Four different 2D-LC analyses combining a different pair of two LC methods provide their characteristic separation results. The separation characteristics of the 2D-LC separations are compared to elucidate the elution characteristics of the block copolymer species.

Quantitative characterization of solid epoxy resins using comprehensive two dimensional liquid chromatography coupled with electrospray ionization-time of flight mass spectrometry.

PubMed

Julka, Samir; Cortes, Hernan; Harfmann, Robert; Bell, Bruce; Schweizer-Theobaldt, Andreas; Pursch, Matthias; Mondello, Luigi; Maynard, Shawn; West, David

2009-06-01

A comprehensive multidimensional liquid chromatography system coupled to Electrospray Ionization-Mass Spectrometry (LCxLC-ESI-MS) was developed for detailed characterization and quantitation of solid epoxy resin components. The two orthogonal modes of separation selected were size exclusion chromatography (SEC) in the first dimension and liquid chromatography at critical conditions (LCCC) in the second dimension. Different components present in the solid epoxy resins were separated and quantitated for the first time based on the functional groups and molecular weight heterogeneity. Coupling LCxLC separations with mass spectrometry enabled the identification of components resolved in the two-dimensional space. Several different functional group families of compounds were separated and identified, including epoxy-epoxy and epoxy-alpha-glycol functional oligomers, and their individual molecular weight ranges were determined. Repeatability obtained ranged from 0.5% for the main product to 21% for oligomers at the 0.4% concentration level.

Assessing the detectability of antioxidants in two-dimensional high-performance liquid chromatography.

PubMed

Bassanese, Danielle N; Conlan, Xavier A; Barnett, Neil W; Stevenson, Paul G

2015-05-01

This paper explores the analytical figures of merit of two-dimensional high-performance liquid chromatography for the separation of antioxidant standards. The cumulative two-dimensional high-performance liquid chromatography peak area was calculated for 11 antioxidants by two different methods--the areas reported by the control software and by fitting the data with a Gaussian model; these methods were evaluated for precision and sensitivity. Both methods demonstrated excellent precision in regards to retention time in the second dimension (%RSD below 1.16%) and cumulative second dimension peak area (%RSD below 3.73% from the instrument software and 5.87% for the Gaussian method). Combining areas reported by the high-performance liquid chromatographic control software displayed superior limits of detection, in the order of 1 × 10(-6) M, almost an order of magnitude lower than the Gaussian method for some analytes. The introduction of the countergradient eliminated the strong solvent mismatch between dimensions, leading to a much improved peak shape and better detection limits for quantification. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Fully automated multifunctional ultrahigh pressure liquid chromatography system for advanced proteome analyses

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

Lee, Jung Hwa; Hyung, Seok-Won; Mun, Dong-Gi

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 obtainedmore » from these experiments is in excellent agreement, which facilitates correlating peptide information from different experiments.« less

Design and implementation of an array of micro-electrochemical detectors for two-dimensional liquid chromatography--proof of principle.

PubMed

Abia, Jude A; Putnam, Joel; Mriziq, Khaled; Guiochon, Georges A

2010-03-05

Simultaneous two-dimensional liquid chromatography (2D-LC) is an implementation of two-dimensional liquid chromatography which has the potential to provide very fast, yet highly efficient separations. It is based on the use of time x space and space x space separation systems. The basic principle of this instrument has been validated long ago by the success of two-dimensional thin layer chromatography. The construction of a pressurized wide and flat column (100 mm x 100 mm x 1 mm) operated under an inlet pressure of up to 50 bar was described previously. However, to become a modern analytical method, simultaneous 2D-LC requires the development of detectors suitable for the monitoring of the composition of the eluent of this pressurized planar, wide column. An array of five equidistant micro-electrochemical sensors was built for this purpose and tested. Each sensor is a three-electrode system, with the working electrode being a 25 microm polished platinum micro-electrode. The auxiliary electrode is a thin platinum wire and the reference electrode an Ag/AgCl (3M sat. KCl) electrode. In this first implementation, proof of principle is demonstrated, but the final instrument will require a much larger array. 2010 Elsevier B.V. All rights reserved.

New on-line separation workflow of microbial metabolites via hyphenation of analytical and preparative comprehensive two-dimensional liquid chromatography.

PubMed

Yan, Xia; Wang, Li-Juan; Wu, Zhen; Wu, Yun-Long; Liu, Xiu-Xiu; Chang, Fang-Rong; Fang, Mei-Juan; Qiu, Ying-Kun

2016-10-15

Microbial metabolites represent an important source of bioactive natural products, but always exhibit diverse of chemical structures or complicated chemical composition with low active ingredients content. Traditional separation methods rely mainly on off-line combination of open-column chromatography and preparative high performance liquid chromatography (HPLC). However, the multi-step and prolonged separation procedure might lead to exposure to oxygen and structural transformation of metabolites. In the present work, a new two-dimensional separation workflow for fast isolation and analysis of microbial metabolites from Chaetomium globosum SNSHI-5, a cytotoxic fungus derived from extreme environment. The advantage of this analytical comprehensive two-dimensional liquid chromatography (2D-LC) lies on its ability to analyze the composition of the metabolites, and to optimize the separation conditions for the preparative 2D-LC. Furthermore, gram scale preparative 2D-LC separation of the crude fungus extract could be performed on a medium-pressure liquid chromatograph×preparative high-performance liquid chromatography system, under the optimized condition. Interestingly, 12 cytochalasan derivatives, including two new compounds named cytoglobosin Ab (3) and isochaetoglobosin Db (8), were successfully obtained with high purity in a short period of time. The structures of the isolated metabolites were comprehensively characterized by HR ESI-MS and NMR. To be highlighted, this is the first report on the combination of analytical and preparative 2D-LC for the separation of microbial metabolites. The new workflow exhibited apparent advantages in separation efficiency and sample treatment capacity compared with conventional methods. Copyright © 2016 Elsevier B.V. All rights reserved.

Mobile phase effects on the retention on polar columns with special attention to the dual hydrophilic interaction-reversed-phase liquid chromatography mechanism, a review.

PubMed

Jandera, Pavel; Hájek, Tomáš

2018-01-01

Hydrophilic interaction liquid chromatography on polar columns in aqueous-organic mobile phases has become increasingly popular for the separation of many biologically important compounds in chemical, environmental, food, toxicological, and other samples. In spite of many new applications appearing in literature, the retention mechanism is still controversial. This review addresses recent progress in understanding of the retention models in hydrophilic interaction liquid chromatography. The main attention is focused on the role of water, both adsorbed by the column and contained in the bulk mobile phase. Further, the theoretical retention models in the isocratic and gradient elution modes are discussed. The dual hydrophilic interaction liquid chromatography reversed-phase retention mechanism on polar columns is treated in detail, especially with respect to the practical use in one- and two-dimensional liquid chromatography separations. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Two-dimensional solid-phase extraction strategy for the selective enrichment of aminoglycosides in milk.

PubMed

Shen, Aijin; Wei, Jie; Yan, Jingyu; Jin, Gaowa; Ding, Junjie; Yang, Bingcheng; Guo, Zhimou; Zhang, Feifang; Liang, Xinmiao

2017-03-01

An orthogonal two-dimensional solid-phase extraction strategy was established for the selective enrichment of three aminoglycosides including spectinomycin, streptomycin, and dihydrostreptomycin in milk. A reversed-phase liquid chromatography material (C 18 ) and a weak cation-exchange material (TGA) were integrated in a single solid-phase extraction cartridge. The feasibility of two-dimensional clean-up procedure that experienced two-step adsorption, two-step rinsing, and two-step elution was systematically investigated. Based on the orthogonality of reversed-phase and weak cation-exchange procedures, the two-dimensional solid-phase extraction strategy could minimize the interference from the hydrophobic matrix existing in traditional reversed-phase solid-phase extraction. In addition, high ionic strength in the extracts could be effectively removed before the second dimension of weak cation-exchange solid-phase extraction. Combined with liquid chromatography and tandem mass spectrometry, the optimized procedure was validated according to the European Union Commission directive 2002/657/EC. A good performance was achieved in terms of linearity, recovery, precision, decision limit, and detection capability in milk. Finally, the optimized two-dimensional clean-up procedure incorporated with liquid chromatography and tandem mass spectrometry was successfully applied to the rapid monitoring of aminoglycoside residues in milk. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Two-dimensional liquid chromatography system for online top-down mass spectrometry

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

Tian, Zhixin; Zhao, Rui; Tolic, Nikola

2010-10-01

An online metal-free weak cation exchange-hydrophilic interaction liquid chromatography/reversed phase liquid chromatography (WCX-HILIC/RPLC) system has been developed for sensitive high-throughput top-down mass spectrometry. Analyzing posttranslational modifications (PTMs) of core histones, with focus on histone H4, tested the system. Using ~24 μg of core histones (H4, H2B, H2A and H3) purified from human fibroblasts, 41 H4 isoforms were identified, with the type and locations of PTMs unambiguously mapped for 20 of these variants. Compared to corresponding offline studies reported previously, online WCXHILIC/ RPLC platform offers significant improvement in sensitivity, with several orders of magnitude reduction in sample requirements and reduction inmore » the overall analysis time. To the best of our knowledge, this study represents the first online two-dimensional (2D) LC-MS/MS characterization of core histone mixture at the intact protein level.« less

Application and recovery of ionic liquids in the preparative separation of four flavonoids from Rhodiola rosea by on-line three-dimensional liquid chromatography.

PubMed

Ma, Shufeng; Hu, Liming; Ma, Chaoyang; Lv, Wenping; Wang, Hongxin

2014-09-01

A novel on-line three-dimensional liquid chromatography method was developed to separate four main flavonoids from Rhodiola rosea. Ethyl acetate/0.5 mol/L ionic liquid 1-butyl-3-methylimidazolium chloride aqueous solution was selected as the solvent system. In the first-dimension separation, the target flavonoids were entrapped and subsequently desorbed into the second-dimension high-speed countercurrent chromatographic column for separation. In the third-dimension chromatography, the residual ionic liquid in the four separated flavonoids was removed and the used ionic liquid was recovered. As a result, 35.1 mg of compound 1, 20.4 mg of compound 2, 8.5 mg of compound 3, and 10.6 mg of compound 4 were obtained from 1.53 g R. rosea extract. They were identified as rhodiosin, rhodionin, herbacetin, and kaempferol, respectively. The recovery of ionic liquid reached 99.1% of the initial amount. The results showed that this method is a powerful technology for the separation of R. rosea flavonoids and that the ionic-liquid-based solvent system has advantages over traditional solvent systems in renewable and environmentally friendly properties. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Detailed analysis of petroleum hydrocarbon attenuation in biopiles by high-performance liquid chromatography followed by comprehensive two-dimensional gas chromatography.

PubMed

Mao, Debin; Lookman, Richard; Van De Weghe, Hendrik; Van Look, Dirk; Vanermen, Guido; De Brucker, Nicole; Diels, Ludo

2009-02-27

Enhanced bioremediation of petroleum hydrocarbons in two biopiles was quantified by high-performance liquid chromatography (HPLC) followed by comprehensive two-dimensional gas chromatography (GCXGC). The attenuation of 34 defined hydrocarbon classes was calculated by HPLC-GCXGC analysis of representative biopile samples at start-up and after 18 weeks of biopile operation. In general, a-cyclic alkanes were most efficiently removed from the biopiles, followed by monoaromatic hydrocarbons. Cycloalkanes and polycyclic aromatic hydrocarbons (PAHs) were more resistant to degradation. A-cyclic biomarkers farnesane, trimethyl-C13, norpristane, pristane and phytane dropped to only about 10% of their initial concentrations. On the other hand, C29-C31 hopane concentrations remained almost unaltered after 18 weeks of biopile operation, confirming their resistance to biodegradation. They are thus reliable indicators to estimate attenuation potential of petroleum hydrocarbons in biopile processed soils.

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

The versatility of heart-cutting and comprehensive two-dimensional liquid chromatography in monoclonal antibody clone selection.

PubMed

Sandra, Koen; Steenbeke, Mieke; Vandenheede, Isabel; Vanhoenacker, Gerd; Sandra, Pat

2017-11-10

In recent years, two-dimensional liquid chromatography (2D-LC) has seen an enormous evolution and one of the fields where it is being widely adopted is in the analysis of therapeutic monoclonal antibodies (mAbs). We here further add to the many flavours of this powerful technology. Workflows based on heart-cutting (LC-LC) and comprehensive (LC×LC) 2D-LC are described that allow to guide the clone selection process in mAb and biosimilar development. Combining Protein A affinity chromatography in the first dimension with size exclusion (SEC), cation exchange (CEX) or reversed-phase liquid chromatography-mass spectrometry (RPLC-MS) in the second dimension simultaneously allows to assess mAb titer and critical structural aspects such as aggregation, fragmentation, charge heterogeneity, molecular weight (MW), amino acid sequence and glycosylation. Complementing the LC-LC measurements at intact protein level with LC×LC based peptide mapping provides the necessary information to make clear decisions on which clones to take further into development. Copyright © 2017 Elsevier B.V. All rights reserved.

Detecting trace components in liquid chromatography/mass spectrometry data sets with two-dimensional wavelets

NASA Astrophysics Data System (ADS)

Compton, Duane C.; Snapp, Robert R.

2007-09-01

TWiGS (two-dimensional wavelet transform with generalized cross validation and soft thresholding) is a novel algorithm for denoising liquid chromatography-mass spectrometry (LC-MS) data for use in "shot-gun" proteomics. Proteomics, the study of all proteins in an organism, is an emerging field that has already proven successful for drug and disease discovery in humans. There are a number of constraints that limit the effectiveness of liquid chromatography-mass spectrometry (LC-MS) for shot-gun proteomics, where the chemical signals are typically weak, and data sets are computationally large. Most algorithms suffer greatly from a researcher driven bias, making the results irreproducible and unusable by other laboratories. We thus introduce a new algorithm, TWiGS, that removes electrical (additive white) and chemical noise from LC-MS data sets. TWiGS is developed to be a true two-dimensional algorithm, which operates in the time-frequency domain, and minimizes the amount of researcher bias. It is based on the traditional discrete wavelet transform (DWT), which allows for fast and reproducible analysis. The separable two-dimensional DWT decomposition is paired with generalized cross validation and soft thresholding. The Haar, Coiflet-6, Daubechie-4 and the number of decomposition levels are determined based on observed experimental results. Using a synthetic LC-MS data model, TWiGS accurately retains key characteristics of the peaks in both the time and m/z domain, and can detect peaks from noise of the same intensity. TWiGS is applied to angiotensin I and II samples run on a LC-ESI-TOF-MS (liquid-chromatography-electrospray-ionization) to demonstrate its utility for the detection of low-lying peaks obscured by noise.

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.

Comprehensive hydrophilic interaction and ion-pair reversed-phase liquid chromatography for analysis of di- to deca-oligonucleotides.

PubMed

Li, Qin; Lynen, Frédéric; Wang, Jian; Li, Hanlin; Xu, Guowang; Sandra, Pat

2012-09-14

A comprehensive two-dimensional HPLC approach with a high degree of orthogonality was developed for analysis of di- to deca-oligonucleotides (ONs). Hydrophilic interaction liquid chromatography (HILIC) was used in the first dimension, and ion-pair reversed-phase liquid chromatography (IP-RPLC) was employed in the second dimension. The two dimensions were connected via a ten-port valve interface equipped with octadecyl silica (ODS) traps to immobilize and focus the ONs eluting from the first dimension prior to IP-RPLC separation. An aqueous make-up flow was used for effective trapping. The comprehensive two-dimensional HPLC system was optimized with a mixture consisting of 27 oligonucleotide standards. An overall chromatographic peak capacity of 500 was obtained. The use of the volatile buffer triethylamine acetate in the second dimension allowed straightforward coupling to electrospray ionization mass spectrometry (ESI-MS) and detection of each ON in the negative ionization mode. Copyright © 2011 Elsevier B.V. All rights reserved.

Separation of Poly(styrene-block-t-butyl methacrylate) Copolymers by Various Liquid Chromatography Techniques

PubMed Central

Šmigovec Ljubič, Tina; Pahovnik, David; Žigon, Majda; Žagar, Ema

2012-01-01

The separation of a mixture of three poly(styrene-block-t-butyl methacrylate) copolymers (PS-b-PtBMA), consisting of polystyrene (PS) blocks of similar length and t-butyl methacrylate (PtBMA) blocks of different lengths, was performed using various chromatographic techniques, that is, a gradient liquid chromatography on reversed-phase (C18 and C8) and normal-phase columns, a liquid chromatography under critical conditions for polystyrene as well as a fully automated two-dimensional liquid chromatography that separates block copolymers by chemical composition in the first dimension and by molar mass in the second dimension. The results show that a partial separation of the mixture of PS-b-PtBMA copolymers can be achieved only by gradient liquid chromatography on reversed-phase columns. The coelution of the two block copolymers is ascribed to a much shorter PtBMA block length, compared to the PS block, as well as a small difference in the length of the PtBMA block in two of these copolymers, which was confirmed by SEC-MALS and NMR spectroscopy. PMID:22489207

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.

Conventional and Advanced Separations in Mass Spectrometry-Based Metabolomics: Methodologies and Applications

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

Heyman, Heino M.; Zhang, Xing; Tang, Keqi

2016-02-16

Metabolomics is the quantitative analysis of all metabolites in a given sample. Due to the chemical complexity of the metabolome, optimal separations are required for comprehensive identification and quantification of sample constituents. This chapter provides an overview of both conventional and advanced separations methods in practice for reducing the complexity of metabolite extracts delivered to the mass spectrometer detector, and covers gas chromatography (GC), liquid chromatography (LC), capillary electrophoresis (CE), supercritical fluid chromatography (SFC) and ion mobility spectrometry (IMS) separation techniques coupled with mass spectrometry (MS) as both uni-dimensional and as multi-dimensional approaches.

Two-dimensional liquid chromatography consisting of twelve second-dimension columns for comprehensive analysis of intact proteins.

PubMed

Ren, Jiangtao; Beckner, Matthew A; Lynch, Kyle B; Chen, Huang; Zhu, Zaifang; Yang, Yu; Chen, Apeng; Qiao, Zhenzhen; Liu, Shaorong; Lu, Joann J

2018-05-15

A comprehensive two-dimensional liquid chromatography (LCxLC) system consisting of twelve columns in the second dimension was developed for comprehensive analysis of intact proteins in complex biological samples. The system consisted of an ion-exchange column in the first dimension and the twelve reverse-phase columns in the second dimension; all thirteen columns were monolithic and prepared inside 250 µm i.d. capillaries. These columns were assembled together through the use of three valves and an innovative configuration. The effluent from the first dimension was continuously fractionated and sequentially transferred into the twelve second-dimension columns, while the second-dimension separations were carried out in a series of batches (six columns per batch). This LCxLC system was tested first using standard proteins followed by real-world samples from E. coli. Baseline separation was observed for eleven standard proteins and hundreds of peaks were observed for the real-world sample analysis. Two-dimensional liquid chromatography, often considered as an effective tool for mapping proteins, is seen as laborious and time-consuming when configured offline. Our online LCxLC system with increased second-dimension columns promises to provide a solution to overcome these hindrances. Copyright © 2018 Elsevier B.V. All rights reserved.

Molecular differences between deuterated and protonated polystyrenes using reversed-phase high-performance liquid chromatography.

PubMed

Kayillo, Sindy; Gray, Michael J; Shalliker, R Andrew; Dennis, Gary R

2005-05-06

Isotopic substitution is a technique used to highlight particular bonds within a molecule for kinetic, spectroscopic and structure analysis. It is presumed that although some properties such as stretching frequencies will not be the same for substituted analogues, the chemical interactions will not vary appreciably as a function of labelling. Reversed-phase liquid chromatography has been used to demonstrate that there are significant differences between the chromatographic behaviour of a sequence of deuterated and protonated oligomeric polystyrenes. Two-dimensional reversed-phase liquid chromatography was used to show that even the diasteromers of the oligomers (n = 5) have retention mechanisms that are dependent on the subtle changes to the molecular conformation and electronic structure, which are a consequence of deuteration.

Evaluation and application of a mixed-mode chromatographic stationary phase in two-dimensional liquid chromatography for the separation of traditional Chinese medicine.

PubMed

Wei, Zhishen; Fu, Qing; Cai, Jianfeng; Huan, Liyun; Zhao, Jianchao; Shi, Hui; Jin, Yu; Liang, Xinmiao

2016-06-01

In this study, two mixed-mode chromatography stationary phases (C8SAX and C8SCX) were evaluated and used to establish a two-dimensional liquid chromatography system for the separation of traditional Chinese medicine. The chromatographic properties of the mixed-mode columns were systematically evaluated by comparing with other three columns of C8, strong anion exchanger, and strong cation exchanger. The result showed that C8SAX and C8SCX had a mixed-mode retention mechanism including electrostatic interaction and hydrophobic interaction. Especially, they were suitable for separating acidic and/or basic compounds and their separation selectivities could be easily adjusted by changing pH value. Then, several off-line 2D-LC systems based on the C8SAX in the first dimension and C8SAX, C8SCX, or C8 columns in the second dimension were developed to analyze a traditional Chinese medicine-Uncaria rhynchophylla. The two-dimensional liquid chromatography system of C8SAX (pH 3.0) × C8SAX (pH 6.0) exhibited the most effective peak distribution. Finally, fractions of U. rhynchophylla prepared from the first dimension were successfully separated on the C8SAX column with a gradient pH. Thus, the mixed-mode stationary phase could provide a platform to separate the traditional Chinese medicine in practical applications. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Characterization of cellulose acetates according to DS and molar mass using two-dimensional chromatography.

PubMed

Ghareeb, Hewa Othman; Radke, Wolfgang

2013-11-06

A two-dimensional liquid chromatographic method (2D LC) was developed to analyze the heterogeneities of cellulose acetates (CA) in the DS-range DS=1.5-2.9 with respect to both, molar mass and degree of substitution (DS). The method uses gradient liquid chromatography (HPLC) as the first dimension in order to separate by DS followed by separation of the different fractions by size (SEC) in the second dimension. The 2D experiments revealed different correlations between gradient and SEC elution volume. These correlations might arise from differences in the synthetic conditions. The newly developed 2D LC separation therefore provides new insights into the heterogeneity of CAs. Copyright © 2013 Elsevier Ltd. All rights reserved.

Simultaneous achiral-chiral analysis of pharmaceutical compounds using two-dimensional reversed phase liquid chromatography-supercritical fluid chromatography.

PubMed

Venkatramani, C J; Al-Sayah, Mohammad; Li, Guannan; Goel, Meenakshi; Girotti, James; Zang, Lisa; Wigman, Larry; Yehl, Peter; Chetwyn, Nik

2016-02-01

A new interface was designed to enable the coupling of reversed phase liquid chromatography (RPLC) and supercritical fluid chromatography (SFC). This online two-dimensional chromatographic system utilizing RPLC in the first dimension and SFC in the second was developed to achieve simultaneous achiral and chiral analysis of pharmaceutical compounds. The interface consists of an eight-port, dual-position switching valve with small volume C-18 trapping columns. The peaks of interest eluting from the first RPLC dimension column were effectively focused as sharp concentration pulses on small volume C-18 trapping column/s and then injected onto the second dimension SFC column. The first dimension RPLC separation provides the achiral purity result, and the second dimension SFC separation provides the chiral purity result (enantiomeric excess). The results are quantitative enabling simultaneous achiral, chiral analysis of compounds. The interface design and proof of concept demonstration are presented. Additionally, comparative studies to conventional SFC and case studies of the applications of 2D LC-SFC in pharmaceutical analysis is presented. Copyright © 2015 Elsevier B.V. All rights reserved.

Analysis of human plasma lipids by using comprehensive two-dimensional gas chromatography with dual detection and with the support of high-resolution time-of-flight mass spectrometry for structural elucidation.

PubMed

Salivo, Simona; Beccaria, Marco; Sullini, Giuseppe; Tranchida, Peter Q; Dugo, Paola; Mondello, Luigi

2015-01-01

The main focus of the present research is the analysis of the unsaponifiable lipid fraction of human plasma by using data derived from comprehensive two-dimensional gas chromatography with dual quadrupole mass spectrometry and flame ionization detection. This approach enabled us to attain both mass spectral information and analyte percentage data. Furthermore, gas chromatography coupled with high-resolution time-of-flight mass spectrometry was used to increase the reliability of identification of several unsaponifiable lipid constituents. The synergism between both the high-resolution gas chromatography and mass spectrometry processes enabled us to attain a more in-depth knowledge of the unsaponifiable fraction of human plasma. Additionally, information was attained on the fatty acid and triacylglycerol composition of the plasma samples, subjected to investigation by using comprehensive two-dimensional gas chromatography with dual quadrupole mass spectrometry and flame ionization detection and high-performance liquid chromatography with atmospheric pressure chemical ionization quadrupole mass spectrometry, respectively. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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. Copyright © 2015 Elsevier B.V. All rights reserved.

Screening anti-tumor compounds from Ligusticum wallichii using cell membrane chromatography combined with high-performance liquid chromatography and mass spectrometry.

PubMed

Zhang, Tao; Ding, Yuanyuan; An, Hongli; Feng, Liuxin; Wang, Sicen

2015-07-14

Tyrosine 367 Cysteine-fibroblast growth factor receptor 4 cell membrane chromatography combined with high-performance liquid chromatography and mass spectrometry was developed. Tyrosine 367 Cysteine-HEK293 cells were used as cell membrane stationary phase. Specificity and reproducibility of the cell membrane chromatography was evaluated using 1-tert-butyl-3-{2-[4-(diethylamino)butylamino]-6-(3,5-dimethoxyphenyl)pyrido[2,3-d]pyrimidin-7-yl}urea, Nimodipine and dexamethasone acetate. Then, anti-tumor components acting on Tyrosine 367 Cysteine-fibroblast growth factor receptor 4 were screened and identified from extracts of Ligusticum wallichii. Components from the extract were retained on the cell membrane chromatographic column. The retained fraction was directly eluted into high-performance liquid chromatography with mass spectrometry system for separation and identification. Finally, Levistolide A was identified as an active component from Ligusticum wallichii extracts. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide-formazan colorimetric assay revealed that Levistolide A inhibits proliferation of overexpressing the mutated receptor cells with dose-dependent manner. Phosphorylation of fibroblast growth factor receptor 4 was also decrease under Levistolide A treatment. Flex dock simulation verified that Levistolide A could bind with the tyrosine kinase domain of fibroblast growth factor receptor 4. Therefore, Levistolide A screened by the cell membrane chromatography combined with high-performance liquid chromatography and mass spectrometry can arrest cell growth. In conclusion, the two-dimensional high-performance liquid chromatography method can screen and identify potential anti-tumor ingredients which specifically act on the tyrosine kinase domain of the mutated fibroblast growth factor receptor 4. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Performance evaluation of a versatile multidimensional chromatographic preparative system based on three-dimensional gas chromatography and liquid chromatography-two-dimensional gas chromatography for the collection of volatile constituents.

PubMed

Pantò, Sebastiano; Sciarrone, Danilo; Maimone, Mariarosa; Ragonese, Carla; Giofrè, Salvatore; Donato, Paola; Farnetti, Sara; Mondello, Luigi

2015-10-23

The present research deals with the multi-collection of the most important sesquiterpene alcohols belonging to sandalwood essential oil, as reported by the international regulations: (Z)-α-santalol, (Z)-α-trans bergamotol, (Z)-β-santalol, epi-(Z)-β-santalol, α-bisabolol, (Z)-lanceol, and (Z)-nuciferol. A versatile multidimensional preparative system, based on the hyphenation of liquid and gas chromatography techniques, was operated in the LC-GC-GC-prep or GC-GC-GC-prep configuration, depending on the concentration to be collected from the sample, without any hardware or software modification. The system was equipped with a silica LC column in combination with polyethylene glycol-poly(5% diphenyl/95% dimethylsiloxane)-medium polarity ionic liquid or β-cyclodextrin based GC stationary phases. The GC-GC-GC-prep configuration was exploited for the collection of four components, by using a conventional split/splitless injector, while the LC-GC-GC-prep approach was applied for three low abundant components (<5%), in order to increase the quantity collected within a single run, by the LC injection of a high sample amount. All target compounds, whose determination is hampered by the unavailability of commercial standards, were collected at milligram levels and with a high degree of purity (>87%). Copyright © 2015 Elsevier B.V. All rights reserved.

[Identification of impurity peaks in the HPLC chromatogram by LC-MS and two-dimensional chromatographic correlation spectroscopy].

PubMed

Chen, Zhen-Zhen; Zhang, Dou-Sheng; Wang, Nan; Feng, Fang; Hu, Chang-Qin

2012-04-01

A novel qualitative analytical method by using two-dimensional chromatographic correlation spectroscopy techniques for recognizing impurity peaks of HPLC methods of quality control and LC-MS chromatographic system was established. The structures of major degradation products of ceftizoxime and cefdinir were identified by LC-MS and MassWorks application; the standard chromatographic and spectral data of the degradation impurities were obtained by high-performance liquid chromatography with diode array detection. The impurity peaks of two-dimensional chromatography were matched by comparison of spectra and calculating correlation coefficients. Peaks in chromatography can be identified accurately and rapidly in different chromatographic systems such as column and mobile phase changed. The method provides a new way and thought to identify the peaks in quality control of impurities without reference impurity substances.

Separation of five compounds from leaves of Andrographis paniculata (Burm. f.) Nees by off-line two-dimensional high-speed counter-current chromatography combined with gradient and recycling elution.

PubMed

Zhang, Li; Liu, Qi; Yu, Jingang; Zeng, Hualiang; Jiang, Shujing; Chen, Xiaoqing

2015-05-01

An off-line two-dimensional high-speed counter-current chromatography method combined with gradient and recycling elution mode was established to isolate terpenoids and flavones from the leaves of Andrographis paniculata (Burm. f.) Nees. By using the solvent systems composed of n-hexane/ethyl acetate/methanol/water with different volume ratios, five compounds including roseooside, 5,4'-dihydroxyflavonoid-7-O-β-d-pyranglucuronatebutylester, 7,8-dimethoxy-2'-hydroxy-5-O-β-d-glucopyranosyloxyflavon, 14-deoxyandrographiside, and andrographolide were successfully isolated. Purities of these isolated compounds were all over 95% as determined by high-performance liquid chromatography. Their structures were identified by UV, mass spectrometry, and (1) H NMR spectroscopy. It has been demonstrated that the combination of off-line two-dimensional high-speed counter-current chromatography with different elution modes is an efficient technique to isolate compounds from complex natural product extracts. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Comprehensive two-dimensional liquid chromatography tandem diode array detector (DAD) and accurate mass QTOF-MS for the analysis of flavonoids and iridoid glycosides in Hedyotis diffusa.

PubMed

Li, Duxin; Schmitz, Oliver J

2015-01-01

The analysis of chemical constituents in Chinese herbal medicines (CHMs) is a challenge because of numerous compounds with various polarities and functional groups. Liquid chromatography coupled with quadrupole time-of-flight (QTOF) mass spectrometry (LC/MS) is of particular interest in the analysis of herbal components. One of the main attributes of QTOF that makes it an attractive analytical technique is its accurate mass measurement for both precursor and product ions. For the separation of CHMs, comprehensive two-dimensional chromatography (LCxLC) provides much higher resolving power than traditional one-dimensional separation. Therefore, a LCxLC-QTOF-MS system was developed and applied to the analysis of flavonoids and iridoid glycosides in aqueous extracts of Hedyotis diffusa (Rubiaceae). Shift gradient was applied in the two-dimensional separation in the LCxLC system to increase the orthogonality and effective peak distribution area of the analysis. Tentative identification of compounds was done by accurate mass interpretation and validation by UV spectrum. A clear classification of flavonol glycosides (FGs), acylated FGs, and iridoid glycosides (IGs) was shown in different regions of the LCxLC contour plot. In total, five FGs, four acylated FGs, and three IGs were tentatively identified. In addition, several novel flavonoids were found, which demonstrates that LCxLC-QTOF-MS detection also has great potential in herbal medicine analysis.

Tear proteomic analysis of patients with type 2 diabetes and dry eye syndrome by two-dimensional nano-liquid chromatography coupled with tandem mass spectrometry.

PubMed

Li, Bing; Sheng, Minjie; Xie, Liqi; Liu, Feng; Yan, Guoquan; Wang, Weifang; Lin, Anjuan; Zhao, Fei; Chen, Yihui

2014-01-09

Diabetes mellitus has been shown to be associated with and complicated by dry eye syndrome. We sought to examine and compare the tear film proteome of type 2 diabetic patients with or without dry eye syndrome and normal subjects using two-dimensional nano-liquid chromatography coupled with tandem mass spectrometry (MS)-based proteomics. Tears were collected from eight type 2 diabetes patients with dry eye syndrome, eight type 2 diabetes patients without dry eye syndrome, and eight normal subjects. Tear breakup time (BUT) was determined, and tear proteins were prepared and analyzed using two-dimensional strong cation-exchange/reversed-phase nano-scale liquid chromatography MS. All MS/MS spectra were identified by using SEQUEST against the human International Protein Index (IPI) database and the relative abundance of individual proteins was assessed by spectral counting. Tear BUT was significantly lower in patients with diabetes and dry eye syndrome than in patients with diabetes only and normal subjects. Analysis of spectral counts of tear proteins showed that, compared to healthy controls, patients with diabetes and dry eye syndrome had increased expression of apoptosis-related proteins, like annexin A1, and immunity- and inflammation-related proteins, including neutrophil elastase 2 and clusterin, and glycometabolism-related proteins, like apolipoprotein A-II. Dry eye syndrome in diabetic patients is associated with aberrant expression of tear proteins, and the findings could lead to identification of novel pathways for therapeutic targeting and new diagnostic markers.

High-temperature two-dimensional liquid chromatography of ethylene-vinylacetate copolymers.

PubMed

Ginzburg, Anton; Macko, Tibor; Dolle, Volker; Brüll, Robert

2010-10-29

Temperature rising elution fractionation hyphenated to size exclusion chromatography (TREF×SEC) is a routine technique to determine the chemical heterogeneity of semicrystalline olefin copolymers. Its applicability is limited to well crystallizing samples. High-temperature two-dimensional liquid chromatography, HT 2D-LC, where the chromatographic separation by HPLC is hyphenated to SEC (HPLC×SEC) holds the promise to separate such materials irrespective of their crystallizability. A model blend consisting of ethylene-vinyl acetate (EVA) copolymers covering a broad range of chemical composition distribution including amorphous and semicrystalline copolymers and a polyethylene standard was separated by HT 2D-LC at 140°C. Both axes of the contour plot, i.e. the compositional axis from the HPLC and the molar mass axis from the SEC separation were calibrated for the first time. Therefore, a new approach to determine the void and dwell volume of the developed HT 2D-LC instrument was applied. The results from the HT 2D-LC separation are compared to those from a cross-fractionation (TREF×SEC) experiment. Copyright © 2010. Published by Elsevier B.V.

Aqueous solubility calculation for petroleum mixtures in soil using comprehensive two-dimensional gas chromatography analysis data.

PubMed

Mao, Debin; Lookman, Richard; Van De Weghe, Hendrik; Vanermen, Guido; De Brucker, Nicole; Diels, Ludo

2009-04-03

An assessment of aqueous solubility (leaching potential) of soil contaminations with petroleum hydrocarbons (TPH) is important in the context of the evaluation of (migration) risks and soil/groundwater remediation. Field measurements using monitoring wells often overestimate real TPH concentrations in case of presence of pure oil in the screened interval of the well. This paper presents a method to calculate TPH equilibrium concentrations in groundwater using soil analysis by high-performance liquid chromatography followed by comprehensive two-dimensional gas chromatography (HPLC-GCXGC). The oil in the soil sample is divided into 79 defined hydrocarbon fractions on two GCXGC color plots. To each of these fractions a representative water solubility is assigned. Overall equilibrium water solubility of the non-aqueous phase liquid (NAPL) present in the sample and the water phase's chemical composition (in terms of the 79 fractions defined) are then calculated using Raoult's law. The calculation method was validated using soil spiked with 13 different TPH mixtures and 1 field-contaminated soil. Measured water solubilities using a column recirculation equilibration experiment agreed well to calculated equilibrium concentrations and water phase TPH composition.

Size-exclusion chromatography using core-shell particles.

PubMed

Pirok, Bob W J; Breuer, Pascal; Hoppe, Serafine J M; Chitty, Mike; Welch, Emmet; Farkas, Tivadar; van der Wal, Sjoerd; Peters, Ron; Schoenmakers, Peter J

2017-02-24

Size-exclusion chromatography (SEC) is an indispensable technique for the separation of high-molecular-weight analytes and for determining molar-mass distributions. The potential application of SEC as second-dimension separation in comprehensive two-dimensional liquid chromatography demands very short analysis times. Liquid chromatography benefits from the advent of highly efficient core-shell packing materials, but because of the reduced total pore volume these materials have so far not been explored in SEC. The feasibility of using core-shell particles in SEC has been investigated and contemporary core-shell materials were compared with conventional packing materials for SEC. Columns packed with very small core-shell particles showed excellent resolution in specific molar-mass ranges, depending on the pore size. The analysis times were about an order of magnitude shorter than what could be achieved using conventional SEC columns. Copyright © 2016 Elsevier B.V. All rights reserved.

Monolithic Integration of Two-Dimensional Liquid Chromatography-Capillary Electrophoresis and Electrospray Ionization on a Microfluidic Device

PubMed Central

Chambers, Andrew G.; Mellors, J. Scott; Henley, W. Hampton; Ramsey, J. Michael

2011-01-01

A microfluidic device capable of two-dimensional reversed-phase liquid chromatography-capillary electrophoresis with integrated electrospray ionization (LC-CE-ESI) for mass spectrometry (MS)-based proteomic applications is described. Traditional instrumentation was used for the LC sample injection and delivery of the LC mobile phase. The glass microfabricated device incorporated a sample-trapping region and an LC channel packed with reversed-phase particles. Rapid electrokinetic injections of the LC effluent into the CE dimension were performed at a cross channel intersection. The CE separation channel terminated at a corner of the square device, which functioned as an integrated electrospray tip. In addition to LC-CE-ESI, this device was used for LC-ESI without any instrumental modifications. To evaluate the system, LC-MS and LC-CE-MS analysis of protein digests were performed and compared. PMID:21214194

Simultaneous enantioselective quantification of fluoxetine and norfluoxetine in human milk by direct sample injection using 2-dimensional liquid chromatography-tandem mass spectrometry.

PubMed

Alvim, Joel; Lopes, Bianca Rebelo; Cass, Quezia Bezerra

2016-06-17

A two-dimensional liquid chromatography system coupled to triple quadrupole tandem mass spectrometer (2D LC-MS/MS) was employed for the simultaneously quantification of fluoxetine (FLX) and norfluoxetine (NFLX) enantiomers in human milk by direct injection of samples. A restricted access media of bovine serum albumin octadecyl column (RAM-BSAC18) was used in the first dimension for the milk proteins depletion, while an antibiotic-based chiral column was used in the second dimension. The results herein described show good selectivity, extraction efficiency, accuracy, and precision with limits of quantification in the order of 7.5ngmL(-1)for the FLX enantiomers and 10.0ngmL(-1) for NFLX enantiomers. Furthermore, it represents a practical tool in terms of sustainability for the sample preparation of such a difficult matrix. Copyright © 2016 Elsevier B.V. All rights reserved.

Use of shift gradient in the second dimension to improve the separation space in comprehensive two-dimensional liquid chromatography.

PubMed

Li, Duxin; Schmitz, Oliver J

2013-08-01

Comprehensive two-dimensional liquid chromatography (LC × LC) has received much attention because it offers much higher peak capacities than separation in a single dimension. The advantageous peak capacity makes it attractive for the separation of complex samples. Various gradient methods have been used in LC × LC systems. The use of continuous shift gradient is advantageous because it combines the peak compression effect of full gradient mode and the tailed gradient program in parallel gradient mode. Here, a comparison of LC × LC analysis of Chinese herbal medicine with full gradient mode and shift gradient mode in the second dimension was performed. A correlation between the first and second dimensions was found in full gradient mode, and this was significantly reduced with shift gradient mode. The orthogonality increased by 43.7%. The effective peak distribution area increased significantly, which produced better separation.

Longitudinal On-Column Thermal Modulation for Comprehensive Two-Dimensional Liquid Chromatography.

PubMed

Creese, Mari E; Creese, Mathew J; Foley, Joe P; Cortes, Hernan J; Hilder, Emily F; Shellie, Robert A; Breadmore, Michael C

2017-01-17

Longitudinal on-column thermal modulation for comprehensive two-dimensional liquid chromatography is introduced. Modulation optimization involved a systematic investigation of heat transfer, analyte retention, and migration velocity at a range of temperatures. Longitudinal on-column thermal modulation was realized using a set of alkylphenones and compared to a conventional valve-modulator employing sample loops. The thermal modulator showed a reduced modulation-induced pressure impact than valve modulation, resulting in reduced baseline perturbation by a factor of 6; yielding a 6-14-fold improvement in signal-to-noise. A red wine sample was analyzed to demonstrate the potential of the longitudinal on-column thermal modulator for separation of a complex sample. Discrete peaks in the second dimension using the thermal modulator were 30-55% narrower than with the valve modulator. The results shown herein demonstrate the benefits of an active focusing modulator, such as reduced detection limits and increased total peak capacity.

A strategy for screening antioxidants in Ginkgo biloba extract by comprehensive two-dimensional ultra high performance liquid chromatography.

PubMed

Guo, Ru-Zhou; Liu, Xin-Guang; Gao, Wen; Dong, Xin; Fanali, Salvatore; Li, Ping; Yang, Hua

2015-11-27

Recently, screening of bioactive compounds by on-line ultra-high performance liquid chromatography (UHPLC) draws increasing attentions for the advantages of rapidity and intuition. Nevertheless, most on-line methods were limited to the shortcoming like low resolution and peak capacity, which could interfere the active ingredient identification. Comprehensive two-dimensional UHPLC (LC×LC) has revealed to be a powerful tool to separate complex mixtures. Herein, a strategy based on LC×LC analysis coupled with pre-column 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay was proposed to screen the antioxidants from the extract of Ginkgo biloba (EGB). A total of 61 compounds were identified in EGB, and 25 of them showed appreciable radical scavenging capacity. This work may offer pharmacodynamics base for further research about EGB, also the strategy is likelihood to be applied in screening antioxidant in other herbal medicine. Copyright © 2015 Elsevier B.V. All rights reserved.

Two-dimensional preparative liquid chromatography system for preparative separation of minor amount components from complicated natural products.

PubMed

Qiu, Ying-Kun; Chen, Fang-Fang; Zhang, Ling-Ling; Yan, Xia; Chen, Lin; Fang, Mei-Juan; Wu, Zhen

2014-04-11

An on-line comprehensive two-dimensional preparative liquid chromatography system was developed for preparative separation of minor amount components from complicated natural products. Medium-pressure liquid chromatograph (MPLC) was applied as the first dimension and preparative HPLC as the second one, in conjunction with trapping column and makeup pump. The performance of the trapping column was evaluated, in terms of column size, dilution ratio and diameter-height ratio, as well as system pressure from the view of medium pressure liquid chromatograph. Satisfactory trapping efficiency can be achieved using a commercially available 15 mm × 30 mm i.d. ODS pre-column. The instrument operation and the performance of this MPLC×preparative HPLC system were illustrated by gram-scale isolation of crude macro-porous resin enriched water extract of Rheum hotaoense. Automated multi-step preparative separation of 25 compounds, whose structures were identified by MS, (1)H NMR and even by less-sensitive (13)C NMR, could be achieved in a short period of time using this system, exhibiting great advantages in analytical efficiency and sample treatment capacity compared with conventional methods. Copyright © 2014 Elsevier B.V. All rights reserved.

Isolation of Three Triterpene Saponins, Including Two New Oleanane Derivatives, from Soldanella alpina and Hydrophilic Interaction Liquid Chromatography-Evaporative Light Scattering Detection of these Three Saponins in Four Soldenella Species.

PubMed

Haller, Julia; Schwaiger, Stefan; Stuppner, Hermann; Gafner, Frank; Ganzera, Markus

2017-11-01

The genus Soldanella is one of the few endemic to Europe. Some of its species have relevance in local traditional medicine. Earlier work has indicated the possible presence of saponins in S. alpina. To investigate S. alpina and other related species for the occurrence of saponins. Following sequential extraction with n-hexane, dichloromethane and ethyl acetate the subsequent methanolic extract of S. alpina roots was fractionated after solvent precipitation using fast centrifugal partition chromatography and column chromatography. Structures were elucidated by LC-MS n , high-resolution MS, hydrolysis experiments and one-dimensional (1D)- and two-dimensional (2D)-NMR. A hydrophilic interaction liquid chromatography method was developed to quantitate saponins in the leaves and roots of four Soldanella species. Three triterpene saponins, two of them new natural products, were isolated from S. alpina. Based on an epoxyoleanal aglycone substituted with four sugar units, they were analytically quantitated using a Kinetex 2.6 μm hydrophilic interaction liquid chromatography (HILIC) column together with a mobile phase comprising of ammonium acetate, water and acetonitrile. Method validation confirmed that the assay meets all requirements in respect to linearity, accuracy, sensitivity and precision. All four Soldanella species investigated contained the three saponins. The lowest total level of the three saponins (1.09%) was observed in S. montana leaves while the highest saponin content (5.14%) was determined in S. alpina roots. The detection of saponins within the genus Soldanella is an indication that further phytochemical examination of this genus may reveal more secondary metabolites of interest. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

Integration of magnetic solid phase fishing and off-line two-dimensional high-performance liquid chromatography-diode array detector-mass spectrometry for screening and identification of human serum albumin binders from Radix Astragali.

PubMed

Zhang, Yuping; Nie, Mingkun; Shi, Shuyun; You, Qingping; Guo, Junfang; Liu, Liangliang

2014-03-01

Radix Astragali is one of the most popular traditional medicinal herb and healthy dietary supplement. Isoflavonoids and astragalosides are the main bioactive ingredients. However, the systematic bioactive component analysis is inadequate so far. Then a facile method based on Fe3O4@SiO2-human serum albumin (Fe3O4@SiO2-HSA) magnetic solid phase fishing integrated with two-dimensional high-performance liquid chromatography-diode array detector-mass spectrometry (2D HPLC-DAD-MS(n)) was developed to fish out and identify HSA binders from Radix Astragali. The immobilized HSA displayed a high stability with 96.2% retained after ten consecutive cycles. 2D HPLC system (size exclusion chromatography×reversed phase chromatography, SEC×RP) were developed and optimised. Forty-seven bioactive compounds including thirty-four isoflavonoids and thirteen astragalosides were screened and identified or tentatively deduced based on their retention time, ultraviolet (UV), accurate molecular weight and diagnostic fragment ions. The results indicated that the integrated method could be widely applied for systematical fishing and identification of bioactive compounds, especially for low-abundance and overlapped compounds, from complex mixtures. Copyright © 2013 Elsevier Ltd. All rights reserved.

Quality evaluation of Hypericum ascyron extract by two-dimensional high-performance liquid chromatography coupled with the colorimetric 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide method.

PubMed

Li, Xiu-Mei; Luo, Xue-Gang; Zhang, Chao-Zheng; Wang, Nan; Zhang, Tong-Cun

2015-02-01

In this paper, a heart-cutting two-dimensional high-performance liquid chromatography coupled with the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) method was established for controlling the quality of different batches of Hypericum ascyron extract for the first time. In comparison with the common one-dimensional fingerprint, the second-dimensional fingerprint compiled additional spectral data and was hence more informative. The quality of H. ascyron extract was further evaluated by similarity measures and the same results were achieved, the correlation coefficients of the similarity of ten batches of H. ascyron extract were ＞0.99. Furthermore, we also evaluated the quality of the ten batches of H. ascyron extract by antibacterial activity. The result demonstrated that the quality of the ten batches of H. ascyron extract was not significantly different by MTT. Finally, we demonstrated that the second-dimensional fingerprint coupled with the MTT method was a more powerful tool to characterize the quality of samples of batch to batch. Therefore the proposed method could be used to comprehensively conduct the quality control of traditional Chinese medicines. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Computer Series, 32.

ERIC Educational Resources Information Center

Moore, John W., Ed.

1982-01-01

Ten computer programs (available from authors) and a noncomputer calculation of the electron in one-dimensional, one-Bohr box are described, including programs for analytical chemistry, space group generation using Pascal, mass-spectral search system (Applesoft), microcomputer-simulated liquid chromatography, voltammetry/amperometric titrations,…

Comprehensive two-dimensional liquid chromatography of therapeutic monoclonal antibody digests.

PubMed

Vanhoenacker, Gerd; Vandenheede, Isabel; David, Frank; Sandra, Pat; Sandra, Koen

2015-01-01

Comprehensive two-dimensional liquid chromatography (LC×LC) is here proposed as a novel tool for peptide mapping of therapeutic monoclonal antibodies in both R&D and routine (QA/QC) environments. This is illustrated by the analysis of the tryptic digest of trastuzumab (Herceptin) applying a commercially available two-dimensional 2D-LC system. Three different LC×LC combinations, i.e., strong cation-exchange × reversed-phase (SCX×RP), reversed-phase × reversed-phase (RP×RP), and hydrophilic interaction × reversed-phase (HILIC×RP), are reported. Detection was carried out using both UV detection (DAD) and mass spectrometry (MS). Several challenges related to the application of LC×LC in peptide mapping and the hyphenation to MS are addressed. The applicability of LC×LC in the assessment of identity, purity, and comparability is demonstrated by the analysis of different Herceptin innovator production batches, a Herceptin biosimilar in development and of stressed samples. The described methodology was shown to be precise in terms of peak volume and (2)D retention time opening interesting perspectives for use in QA/QC testing.

High-throughput determination of vancomycin in human plasma by a cost-effective system of two-dimensional liquid chromatography.

PubMed

Sheng, Yanghao; Zhou, Boting

2017-05-26

Therapeutic drug monitoring (TDM) is one of the most important services of clinical laboratories. Two main techniques are commonly used: the immunoassay and chromatography method. We have developed a cost-effective system of two-dimensional liquid chromatography with ultraviolet detection (2D-LC-UV) for high-throughput determination of vancomycin in human plasma that combines the automation and low start-up costs of the immunoassay with the high selectivity and sensitivity of the liquid chromatography coupled with mass spectrometric detection without incurring their disadvantages, achieving high cost-effectiveness. This 2D-LC system offers a large volume injection to provide sufficient sensitivity and uses simulated gradient peak compression technology to control peak broadening and to improve peak shape. A middle column was added to reduce the analysis cycle time and make it suitable for high-throughput routine clinical assays. The analysis cycle time was 4min and the peak width was 0.8min. Compared with other chromatographic methods that have been developed, the analysis cycle time and peak width for vancomycin was reduced significantly. The lower limit of quantification was 0.20μg/mL for vancomycin, which is the same as certain LC-MS/MS methods that have been recently developed and validated. The method is rapid, automated, and low-cost and has high selectivity and sensitivity for the quantification of vancomycin in human plasma, thus making it well-suited for use in hospital clinical laboratories. Copyright © 2017 Elsevier B.V. All rights reserved.

Advanced analytical techniques for the extraction and characterization of plant-derived essential oils by gas chromatography with mass spectrometry.

PubMed

Waseem, Rabia; Low, Kah Hin

2015-02-01

In recent years, essential oils have received a growing interest because of the positive health effects of their novel characteristics such as antibacterial, antifungal, and antioxidant activities. For the extraction of plant-derived essential oils, there is the need of advanced analytical techniques and innovative methodologies. An exhaustive study of hydrodistillation, supercritical fluid extraction, ultrasound- and microwave-assisted extraction, solid-phase microextraction, pressurized liquid extraction, pressurized hot water extraction, liquid-liquid extraction, liquid-phase microextraction, matrix solid-phase dispersion, and gas chromatography (one- and two-dimensional) hyphenated with mass spectrometry for the extraction through various plant species and analysis of essential oils has been provided in this review. Essential oils are composed of mainly terpenes and terpenoids with low-molecular-weight aromatic and aliphatic constituents that are particularly important for public health. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effect of background correction on peak detection and quantification in online comprehensive two-dimensional liquid chromatography using diode array detection.

PubMed

Allen, Robert C; John, Mallory G; Rutan, Sarah C; Filgueira, Marcelo R; Carr, Peter W

2012-09-07

A singular value decomposition-based background correction (SVD-BC) technique is proposed for the reduction of background contributions in online comprehensive two-dimensional liquid chromatography (LC×LC) data. The SVD-BC technique was compared to simply subtracting a blank chromatogram from a sample chromatogram and to a previously reported background correction technique for one dimensional chromatography, which uses an asymmetric weighted least squares (AWLS) approach. AWLS was the only background correction technique to completely remove the background artifacts from the samples as evaluated by visual inspection. However, the SVD-BC technique greatly reduced or eliminated the background artifacts as well and preserved the peak intensity better than AWLS. The loss in peak intensity by AWLS resulted in lower peak counts at the detection thresholds established using standards samples. However, the SVD-BC technique was found to introduce noise which led to detection of false peaks at the lower detection thresholds. As a result, the AWLS technique gave more precise peak counts than the SVD-BC technique, particularly at the lower detection thresholds. While the AWLS technique resulted in more consistent percent residual standard deviation values, a statistical improvement in peak quantification after background correction was not found regardless of the background correction technique used. Copyright © 2012 Elsevier B.V. All rights reserved.

Characterization of the pigment fraction in sweet bell peppers (Capsicum annuum L.) harvested at green and overripe yellow and red stages by offline multidimensional convergence chromatography/liquid chromatography-mass spectrometry.

PubMed

Bonaccorsi, Ivana; Cacciola, Francesco; Utczas, Margita; Inferrera, Veronica; Giuffrida, Daniele; Donato, Paola; Dugo, Paola; Mondello, Luigi

2016-09-01

Offline multidimensional supercritical fluid chromatography combined with reversed-phase liquid chromatography was employed for the carotenoid and chlorophyll characterization in different sweet bell peppers (Capsicum annuum L.) for the first time. The first dimension consisted of an Acquity HSS C18 SB (100 × 3 mm id, 1.8 μm particles) column operated with a supercritical mobile phase in an ultra-performance convergence chromatography system, whereas the second dimension was performed in reversed-phase mode with a C30 (250 × 4.6 mm id, 3.0 μm particles) stationary phase combined with photodiode array and mass spectrometry detection. This approach allowed the determination of 115 different compounds belonging to chlorophylls, free xanthophylls, free carotenes, xanthophyll monoesters, and xanthophyll diesters, and proved to be a significant improvement in the pigments determination compared to the conventional one-dimensional liquid chromatography approach so far applied to the carotenoid analysis in the studied species. Moreover, the present study also aimed to investigate and to compare the carotenoid stability and composition in overripe yellow and red bell peppers collected directly from the plant, thus also evaluating whether biochemical changes are linked to carotenoid degradation in the nonclimacteric investigated fruits, for the first time. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Rapid determination of six carcinogenic primary aromatic amines in mainstream cigarette smoke by two-dimensional online solid phase extraction combined with liquid chromatography tandem mass spectrometry.

PubMed

Bie, Zhenying; Lu, Wei; Zhu, You; Chen, Yusong; Ren, Hubo; Ji, Lishun

2017-01-27

A fully automated, rapid, and reliable method for simultaneous determination of six carcinogenic primary aromatic amines (AAs), including o-toluidine (o-TOL), 2, 6-dimethylaniline (2, 6-DMA), o-anisidine (o-ASD), 1-naphthylamine (1-ANP), 2-naphthylamine (2-ANP), and 4-aminobiphenyl (4-ABP), in mainstream cigarette smoke was established. The proposed method was based on two-dimensional online solid phase extraction combined with liquid chromatography tandem mass spectrometry (SPE/LC-MS/MS). The particulate phase of the mainstream cigarette smoke was collected on a Cambridge filter pad and pretreated via ultrasonic extraction with 2% formic acid (FA), while the gas phase was trapped by 2% FA without pretreatment for determination. The two-dimensional online SPE comprised of two cartridges with different absorption characteristics was applied for sample pretreatment. Analysis was performed by liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) under multiple reaction monitoring mode. Each sample required about 0.5h for solid phase extraction and analysis. The limit of detections (LODs) for six AAs ranged from 0.04 to 0.58ng/cig and recoveries were within 84.5%-122.9%. The relative standard deviations of intra- and inter-day tests for 3R4F reference cigarette were less than 6% and 7%, respectively, while no more than 7% and 8% separately for a type of Virginia cigarette. The proposed method enabled minimum sample pretreatment, full automation, and high throughput with high selectivity, sensitivity, and accuracy. As a part of the validation procedure, fifteen brands of cigarettes were tested by the designed method. Copyright © 2016 Elsevier B.V. All rights reserved.

Determination of tropane alkaloids by heart cutting reversed phase - Strong cation exchange two dimensional liquid chromatography.

PubMed

Long, Zhen; Zhang, Yanhai; Gamache, Paul; Guo, Zhimou; Steiner, Frank; Du, Nana; Liu, Xiaoda; Jin, Yan; Liu, Xingguo; Liu, Lvye

2018-01-01

Current Chinese Pharmacopoeia (ChP) standards apply liquid extraction combined with one dimensional liquid chromatography (1DLC) method for determining alkaloids in herbal medicines. The complex pretreatments lead to a low analytical efficiency and possible component loss. In this study, a heart cutting reversed phase - strong cation exchange two dimensional liquid chromatography (RP - SCX 2DLC) approach was optimized for simultaneously quantifying tropane alkaloids (anisodine, scopolamine and hyoscyamine) in herbal medicines and herbal medicine tablets without further treatment of the filtered extract. The chromatographic conditions were systematically optimized in terms of column type, mobile phase composition and flow rate. To improve peak capacity and obtain symmetric peak shape of alkaloids, a polar group embedded C18 column combined with chaotropic salts was used in the first dimension. To remove the disturbance of non-alkaloids, achieve unique selectivity and acquire symmetric peak shape of alkaloids, an SCX column combined with phosphate buffer was used in the second dimension. Method validation was performed in terms of linearity, precision (0.54-0.82%), recovery (94.1-105.2%), limit of detection (LOD) and limit of quantification (LOQ) of the three analytes varied between 0.067-0.115mgL -1 and 0.195-0.268mgL -1 , respectively. The method demonstrated superiority over 1DLC method in respect of resolution (less alkaloid co-eluted), sample preparation (no pretreatment procedure) and transfer rate (minimum component loss). The optimized RP - SCX 2DLC approach was subsequently applied to quantify target alkaloids in five herbal medicines and herbal medicine tablets from three different manufactures. The results demonstrated that the developed heart cutting RP - SCX 2DLC approach represented a new, strategically significant methodology for the quality evaluation of tropane alkaloid in related herbal medicines that involve complex chemical matrix. Copyright © 2017. Published by Elsevier B.V.

Profiling analysis of low molecular weight heparins by multiple heart-cutting two dimensional chromatography with quadruple time-of-flight mass spectrometry.

PubMed

Ouyang, Yilan; Zeng, Yangyang; Rong, Yinxiu; Song, Yue; Shi, Lv; Chen, Bo; Yang, Xinlei; Xu, Naiyu; Linhardt, Robert J; Zhang, Zhenqing

2015-09-01

Low molecular weight heparins (LMWHs) are polydisperse and microheterogenous mixtures of polysaccharides used as anticoagulant drugs. Profiling analysis is important for obtaining deeper insights into the structure of LMWHs. Previous oligosaccharide mapping methods are relatively low resolution and are unable to show an entire picture of the structural complexity of LMWHs. In the current study a profiling method was developed relying on multiple heart-cutting, two-dimensional, ultrahigh performance liquid chromatography with quadruple time-of-flight mass spectrometry. This represents an efficient, automated, and robust approach for profiling LMWHs. Using size-exclusion chromatography and ion-pairing reversed-phase chromatography in a two-dimensional separation, LMW components of different sizes and LMW components of the same size but with different charges and polarities can be resolved, providing a more complete picture of a LMWH. Structural information on each component was then obtained with quadrupole time-of-flight mass spectrometry. More than 80 and 120 oligosaccharides were observed and unambiguously assigned from the LMWHs, nadroparin and enoxaparin, respectively. This method might be useful for quality control of LMWHs and as a powerful tool for heparin-related glycomics.

Chemical Analysis of the Chinese Liquor Luzhoulaojiao by Comprehensive Two-Dimensional Gas Chromatography/Time-of-Flight Mass Spectrometry

PubMed Central

Yao, Feng; Yi, Bin; Shen, Caihong; Tao, Fei; Liu, Yumin; Lin, Zhixin; Xu, Ping

2015-01-01

Luzhoulaojiao liquor is a type of Chinese liquor that dates back hundreds of years, but whose precise chemical composition remains unknown. This paper describes the screening of the liquor and the identification of its compounds using comprehensive two-dimensional gas chromatography/time-of-flight mass spectrometry (GC × GC/TOF-MS). Samples were prepared by both liquid-liquid extraction and solid-phase microextraction, which facilitated the detection of thousands of compounds in the liquor, thus demonstrating the superior performance of the proposed method over those reported in previous studies. A total of 320 compounds were common to all 18 types of Luzhoulaojiao liquor studied here, and 13 abundant and potentially bioactive compounds were further quantified. The results indicated that the high-performance method presented here is well suited for the detection and identification of compounds in liquors. This study also contributes to enriching our knowledge of the contents of Chinese liquors. PMID:25857434

Simultaneous quantification of fluoxetine and norfluoxetine in colostrum and mature human milk using a 2-dimensional liquid chromatography-tandem mass spectrometry system.

PubMed

Lopes, Bianca Rebelo; Cassiano, Neila Maria; Carvalho, Daniela Miarelli; Moisés, Elaine Christine Dantas; Cass, Quezia Bezerra

2018-02-20

A two-dimensional liquid chromatography system coupled to triple quadrupole tandem mass spectrometer (2D LC-MS/MS) was employed for the determination of fluoxetine (FLU) and norfluoxetine (N-FLU) in colostrum and mature milk by direct sample injection. With a run time of 12 min representing a gain in throughput analysis, the validated methods furnished selectivity, extraction efficiency, accuracy, and precision in accordance with the criteria preconized by the European Medicines Agency guidelines. With a linear range of 3.00-150 ng/mL for FLU and 4.00-200 ng/mL for N-FLU they were applied to the analysis of colostrum and mature milk samples from nursing mothers. The paper discusses the differences and similarity of sample preparation for this two sample matrices. The herein reported methods are an advance in sample preparation procedures providing waste reduction and a sustainable approach. Copyright © 2017 Elsevier B.V. All rights reserved.

Chemical Analysis of the Chinese Liquor Luzhoulaojiao by Comprehensive Two-Dimensional Gas Chromatography/Time-of-Flight Mass Spectrometry

NASA Astrophysics Data System (ADS)

Yao, Feng; Yi, Bin; Shen, Caihong; Tao, Fei; Liu, Yumin; Lin, Zhixin; Xu, Ping

2015-04-01

Luzhoulaojiao liquor is a type of Chinese liquor that dates back hundreds of years, but whose precise chemical composition remains unknown. This paper describes the screening of the liquor and the identification of its compounds using comprehensive two-dimensional gas chromatography/time-of-flight mass spectrometry (GC × GC/TOF-MS). Samples were prepared by both liquid-liquid extraction and solid-phase microextraction, which facilitated the detection of thousands of compounds in the liquor, thus demonstrating the superior performance of the proposed method over those reported in previous studies. A total of 320 compounds were common to all 18 types of Luzhoulaojiao liquor studied here, and 13 abundant and potentially bioactive compounds were further quantified. The results indicated that the high-performance method presented here is well suited for the detection and identification of compounds in liquors. This study also contributes to enriching our knowledge of the contents of Chinese liquors.

Proteomic profiling of human pleural effusion using two-dimensional nano liquid chromatography tandem mass spectrometry.

PubMed

Tyan, Yu-Chang; Wu, Hsin-Yi; Lai, Wu-Wei; Su, Wu-Chou; Liao, Pao-Chi

2005-01-01

Pleural effusion, an accumulation of pleural fluid, contains proteins originated from plasma filtrate and, especially when tissues are damaged, parenchyma interstitial spaces of lungs and/or other organs. This study details protein profiles in human pleural effusion from 43 lung adenocarcinoma patients by a two-dimensional nano-high performance liquid chromatography electrospray ionization tandem mass spectrometry (2D nano-HPLC-ESI-MS/MS) system. The experimental results revealed the identification of 1415 unique proteins from human pleural effusion. Among these 124 proteins identified with higher confidence levels, some proteins have not been reported in plasma and may represent proteins specifically present in pleural effusion. These proteins are valuable for mass identification of differentially expressed proteins involved in proteomics database and screening biomarker to further study in human lung adenocarcinoma. The significance of the use of proteomics analysis of human pleural fluid for the search of new lung cancer marker proteins, and for their simultaneous display and analysis in patients suffering from lung disorders has been examined.

Ethanolic extraction, purification, and partial characterization of a fluorescent toxin from the coral reef crab, Lophozozymus pictor.

PubMed

Lau, C O; Tan, C H; Khoo, H E; Li, Q T; Yuen, R

1995-01-01

A purification procedure for Lophozozymus pictor toxin (LPTX) following ethanolic extraction of whole crab homogenate is described. The ethanol-extracted toxin (LPTX-E) had higher yield and specific activity than the hot aqueous-extracted one (LPTX-H). It was found that LPTX-E was fluorescent and cochromatographed with LPTX-H on two-dimensional thin-layer chromatography. Although LPTX-E, LPTX-H, and palytoxin (P. caribaeorum, PTX) had similar migration and retention times when analysed on high performance capillary electrophoresis and gel permeation-high performance liquid chromatography respectively, LPTX-E and LPTX-H were both fluorescent in contrast to PTX. In addition, LPTX-E had a different retention time compared with PTX when chromatographed on reversed phase high performance liquid chromatography in the solvent system 80% acetonitrile and 0.02 M Tris-HCl, pH 7.2, at a 4:1 ratio, respectively, indicating some differences in their chemical structures.

A novel two-dimensional liquid-chromatography method for online prediction of the toxicity of transformation products of benzophenones after water chlorination.

PubMed

Li, Jian; Ma, Li-Yun; Xu, Li; Shi, Zhi-Guo

2015-08-01

Benzophenone-type UV filters (BPs) are ubiquitous in the environment. Transformation products (TPs) of BPs with suspected toxicity are likely to be produced during disinfection of water by chlorination. To quickly predict the toxicity of TPs, in this study, a novel two-dimensional liquid-chromatography (2D-LC) method was established in which the objective of the first dimension was to separate the multiple components of the BPs sample after chlorination, using a reversed-phase liquid-chromatography mode. A biochromatographic system, i.e. bio-partitioning micellar chromatography with the polyoxyethylene (23) lauryl ether aqueous solution as the mobile phase, served as the second dimension to predict the toxicity of the fraction from the first dimension on the basis of the quantitative retention-activity relationships (QRARs) model. Six BPs, namely 2,4-dihydroxybenzophenone, oxybenzone, 4-hydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone and 2,2'-dihydroxy-4-methoxybenzophenone, were the target analytes subjected to chlorination. The products of these BPs after chlorination were directly injected to the 2D-LC system for analysis. The results indicated that most TPs may be less toxic than their parent chemicals, but some may be more toxic, and that intestinal toxicity of TPs may be more obvious than blood toxicity. The proposed method is time-saving, high-throughput, and reliable, and has great potential for predicting toxicity or bioactivity of unknown and/or known components in a complex sample. Graphical Abstract The scheme for the 2D-LC online prediction of toxicity of the transformation products of benzophenone-type UV filters after chlorination.

The speciation of the proteome

PubMed Central

Jungblut, Peter R; Holzhütter, Hermann G; Apweiler, Rolf; Schlüter, Hartmut

2008-01-01

Introduction In proteomics a paradox situation developed in the last years. At one side it is basic knowledge that proteins are post-translationally modified and occur in different isoforms. At the other side the protein expression concept disclaims post-translational modifications by connecting protein names directly with function. Discussion Optimal proteome coverage is today reached by bottom-up liquid chromatography/mass spectrometry. But quantification at the peptide level in shotgun or bottom-up approaches by liquid chromatography and mass spectrometry is completely ignoring that a special peptide may exist in an unmodified form and in several-fold modified forms. The acceptance of the protein species concept is a basic prerequisite for meaningful quantitative analyses in functional proteomics. In discovery approaches only top-down analyses, separating the protein species before digestion, identification and quantification by two-dimensional gel electrophoresis or protein liquid chromatography, allow the correlation between changes of a biological situation and function. Conclusion To obtain biological relevant information kinetics and systems biology have to be performed at the protein species level, which is the major challenge in proteomics today. PMID:18638390

Qualitative and quantitative two-dimensional thin-layer chromatography/high performance liquid chromatography/diode-array/electrospray-ionization-time-of-flight mass spectrometry of cholinesterase inhibitors.

PubMed

Mroczek, Tomasz

2016-09-10

Recently launched thin-layer chromatography-mass spectrometry (TLC-MS) interface enabling extraction of compounds directly from TLC plates into MS ion source was unusually extended into two-dimensional thin-layer chromatography/high performance liquid chromatography (2D, TLC/HPLC) system by its a direct connection to a rapid resolution 50×2.1mm, I.D. C18 column compartment followed by detection by diode array (DAD) and electrospray ionisation time-of-flight mass spectrometry (ESI-TOF-MS). In this way, even not separated bands of complicated mixtures of natural compounds could be analysed structurally, only within 1-2min after development of TLC plates. In comparison to typically applied TLC-MS interface, no ion suppression for acidic mobile phases was observed. Also, substantial increase in ESI-TOF-MS sensitivities and quality of spectra, were noticed. It has been utilised in combination with TLC- based bioautographic approaches of acetylcholinesterase (AChE) inhibitors, However, it can be also applied in any other procedures related to bioactivity (e.g. 2,2-Diphenyl-1-picryl-hydrazyl-DPPH screen test for radicals). This system has been also used for determination of half maximal inhibitory concentration (IC50 values) of the active inhibitor-galanthamine, as an example. Moreover, AChE inhibitory potencies of some of purified plant extracts, never studied before, have been quantitatively measured. This is first report of usage such the 2D TLC/HPLC/MS system both for qualitative and quantitative evaluation of cholinesterase inhibitors in biological matrices. Copyright © 2016 Elsevier B.V. All rights reserved.

Separation and analysis of phenolic acids from Salvia miltiorrhiza and its related preparations by off-line two-dimensional hydrophilic interaction chromatography×reversed-phase liquid chromatography coupled with ion trap time-of-flight mass spectrometry.

PubMed

Sun, Wanyang; Tong, Ling; Miao, Jingzhuo; Huang, Jingyi; Li, Dongxiang; Li, Yunfei; Xiao, Hongting; Sun, Henry; Bi, Kaishun

2016-01-29

Salvia miltiorrhiza (SM) is one of the most widely used Traditional Chinese Medicine. Active constituents of SM mainly contain hydrophilic phenolic acids (PAs) and lipophilic tanshinones. However, due to the existing of multiple ester bonds and unsaturated bonds in the structures, PAs have numerous chemical conversion products. Many of them are so low-abundant that hard to be separated using conventional methods. In this study, an off-line two-dimensional liquid chromatography (2D-LC) method was developed to separate PAs in SM and its related preparations. In the first dimension, samples were fractionated by hydrophilic interaction chromatography (HILIC) (Acchrom×Amide, 4.6×250mm, 5μm) mainly based on the hydrogen bonding effects. The fractions were then separated on reversed-phase liquid chromatography (RP-LC) (Acquity HSS T3, 2.1×50mm, 1.7μm) according to hydrophobicity. For the selective identification of PAs, diode array detector (DAD) and electrospray ionization tandem ion trap time-of-flight mass spectrometry (ESI-IT-TOF-MS) were employed. Practical and effective peak capacities of all the samples were greater than 2046 and 1130, respectively, with the orthogonalities ranged from 69.7% to 92.8%, which indicated the high efficiency and versatility of this method. By utilizing the data post-processing techniques, including mass defect filter, neutral loss filter and product ion filter, a total of 265 compounds comprising 196 potentially new PAs were tentatively characterized. Twelve kinds of derivatives, mainly including glycosylated compounds, O-alkylated compounds, condensed compounds and hydrolyzed compounds, constituted the novelty of the newly identified PAs. The HILIC×RP-LC/TOF-MS system expanded our understanding on PAs of S. miltiorrhiza and its related preparations, which could also benefit the separation and characterization of polar constituents in complicated herbal extracts. Copyright © 2016. Published by Elsevier B.V.

A method for screening active components from Chinese herbs by cell membrane chromatography-offline-high performance liquid chromatography/mass spectrometry and an online statistical tool for data processing.

PubMed

Cao, Yan; Wang, Shaozhan; Li, Yinghua; Chen, Xiaofei; Chen, Langdong; Wang, Dongyao; Zhu, Zhenyu; Yuan, Yongfang; Lv, Diya

2018-03-09

Cell membrane chromatography (CMC) has been successfully applied to screen bioactive compounds from Chinese herbs for many years, and some offline and online two-dimensional (2D) CMC-high performance liquid chromatography (HPLC) hyphenated systems have been established to perform screening assays. However, the requirement of sample preparation steps for the second-dimensional analysis in offline systems and the need for an interface device and technical expertise in the online system limit their extensive use. In the present study, an offline 2D CMC-HPLC analysis combined with the XCMS (various forms of chromatography coupled to mass spectrometry) Online statistical tool for data processing was established. First, our previously reported online 2D screening system was used to analyze three Chinese herbs that were reported to have potential anti-inflammatory effects, and two binding components were identified. By contrast, the proposed offline 2D screening method with XCMS Online analysis was applied, and three more ingredients were discovered in addition to the two compounds revealed by the online system. Then, cross-validation of the three compounds was performed, and they were confirmed to be included in the online data as well, but were not identified there because of their low concentrations and lack of credible statistical approaches. Last, pharmacological experiments showed that these five ingredients could inhibit IL-6 release and IL-6 gene expression on LPS-induced RAW cells in a dose-dependent manner. Compared with previous 2D CMC screening systems, this newly developed offline 2D method needs no sample preparation steps for the second-dimensional analysis, and it is sensitive, efficient, and convenient. It will be applicable in identifying active components from Chinese herbs and practical in discovery of lead compounds derived from herbs. Copyright © 2018 Elsevier B.V. All rights reserved.

Principle of two-dimensional characterization of copolymers.

PubMed

Weidner, Steffen; Falkenhagen, Jana; Krueger, Ralph-Peter; Just, Ulrich

2007-07-01

Two-dimensional polymer characterization is used for a simultaneous analysis of molar masses and chemical heterogeneities (e.g., end groups, copolymer composition, etc.). This principle is based on coupling of two different chromatographic modes. Liquid adsorption chromatography at critical conditions (LACCC) is applied for a separation according to the chemical heterogeneity, whereas in the second-dimension fractions are analyzed with regard to their molar mass distribution by means of size exclusion chromatography (SEC). Because appropriate standards for a calibration of the SEC are seldom available, matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-TOF MS) was used to substitute the SEC. The LACCC-MALDI MS coupling enables acquiring additional structural information on copolymer composition, which can considerably enhance the performance of this coupled method.

Quantitative Characterization of Aqueous Byproducts from Hydrothermal Liquefaction of Municipal Wastes, Food Industry Wastes, and Biomass Grown on Waste

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

Maddi, Balakrishna; Panisko, Ellen; Wietsma, Thomas

Hydrothermal liquefaction (HTL) is a viable thermochemical process for converting wet solid wastes into biocrude which can be hydroprocessed to liquid transportation fuel blendstocks and specialty chemicals. The aqueous byproduct from HTL contains significant amounts (20 to 50%) of the feed carbon, which must be used to enhance economic sustainability of the process on an industrial scale. In this study, aqueous fractions produced from HTL of industrial and municipal waste were characterized using a wide variety of analytical approaches. Organic chemical compounds present in these aqueous fractions were identified using two-dimensional gas chromatography equipped with time-of-flight mass spectrometry. Identified compoundsmore » include organic acids, nitrogen compounds, alcohols, aldehydes, and ketones. Conventional gas chromatography and liquid chromatography methods were employed to quantify the identified compounds. Inorganic species, in the aqueous stream of hydrothermal liquefaction of these aqueous byproducts, also were quantified using ion chromatography and inductively coupled plasma optical emission spectroscopy. The concentrations of organic chemical compounds and inorganic species are reported, and the significance of these results is discussed in detail.« less

Liquid Crystals in Chromatography

NASA Astrophysics Data System (ADS)

Witkiewicz, Zygfryd

The following sections are included: * INTRODUCTION * LIQUID CRYSTALS SUITABLE FOR GAS CHROMATOGRAPHY * Monomeric Liquid Crystal Stationary Phases * Polymeric Liquid Crystal Stationary Phases * Polymeric Liquid Crystal Stationary Phases * Conventional Analytical Columns * Capillary Columns * FACTORS AFFECTING THE CHROMATOGRAPHIC SEPARATIONS ON LIQUID CRYSTAL STATIONARY PHASES * Kind of Mesophase of the Liquid Crystal * Molecular Structure of the Liquid Crystals and of the Chromatographed Substances * Substrate on which the Liquid Crystal is Deposited * ANALYTICAL APPLICATIONS OF LIQUID CRYSTAL STATIONARY PHASES IN GAS CHROMATOGRAPHY * Separation of Isomers of Benzene and Naphthalene Derivatives * Separation of Alkane and Alkene Isomers * Separation of Mixtures of Benzene and Aliphatic Hydrocarbon Derivatives Containing Heteroatoms * Separation of Polynuclear Hydrocarbons * INVESTIGATION OF THE PROPERTIES OF LIQUID CRYSTALS BY GAS CHROMATOGRAPHY * APPLICATION OF LIQUID CRYSTALS IN LIQUID CHROMATOGRAPHY * Column Chromatography * Thin-Layer Chromatography * APPLICATION OF LIQUID CRYSTAL STATIONARY PHASES IN SUPERCRITICAL FLUID CHROMATOGRAPHY * FINAL REMARKS * References

Efficient Exploitation of Separation Space in Two-Dimensional Liquid Chromatography System for Comprehensive and Efficient Proteomic Analyses.

PubMed

Lee, Hangyeore; Mun, Dong-Gi; So, Jeong Eun; Bae, Jingi; Kim, Hokeun; Masselon, Christophe; Lee, Sang-Won

2016-12-06

Proteomics aims to achieve complete profiling of the protein content and protein modifications in cells, tissues, and biofluids and to quantitatively determine changes in their abundances. This information serves to elucidate cellular processes and signaling pathways and to identify candidate protein biomarkers and/or therapeutic targets. Analyses must therefore be both comprehensive and efficient. Here, we present a novel online two-dimensional reverse-phase/reverse-phase liquid chromatography separation platform, which is based on a newly developed online noncontiguous fractionating and concatenating device (NCFC fractionator). In bottom-up proteomics analyses of a complex proteome, this system provided significantly improved exploitation of the separation space of the two RPs, considerably increasing the numbers of peptides identified compared to a contiguous 2D-RP/RPLC method. The fully automated online 2D-NCFC-RP/RPLC system bypassed a number of labor-intensive manual processes required with the previously described offline 2D-NCFC RP/RPLC method, and thus, it offers minimal sample loss in a context of highly reproducible 2D-RP/RPLC experiments.

Blind column selection protocol for two-dimensional high performance liquid chromatography.

PubMed

Burns, Niki K; Andrighetto, Luke M; Conlan, Xavier A; Purcell, Stuart D; Barnett, Neil W; Denning, Jacquie; Francis, Paul S; Stevenson, Paul G

2016-07-01

The selection of two orthogonal columns for two-dimensional high performance liquid chromatography (LC×LC) separation of natural product extracts can be a labour intensive and time consuming process and in many cases is an entirely trial-and-error approach. This paper introduces a blind optimisation method for column selection of a black box of constituent components. A data processing pipeline, created in the open source application OpenMS®, was developed to map the components within the mixture of equal mass across a library of HPLC columns; LC×LC separation space utilisation was compared by measuring the fractional surface coverage, fcoverage. It was found that for a test mixture from an opium poppy (Papaver somniferum) extract, the combination of diphenyl and C18 stationary phases provided a predicted fcoverage of 0.48 and was matched with an actual usage of 0.43. OpenMS®, in conjunction with algorithms designed in house, have allowed for a significantly quicker selection of two orthogonal columns, which have been optimised for a LC×LC separation of crude extractions of plant material. Copyright © 2016 Elsevier B.V. All rights reserved.

Downstream valorization and comprehensive two-dimensional liquid chromatography-based chemical characterization of bioactives from black chokeberries (Aronia melanocarpa) pomace.

PubMed

Brazdauskas, T; Montero, L; Venskutonis, P R; Ibañez, E; Herrero, M

2016-10-14

In this work, a new alternative for the downstream processing and valorization of black chokeberry pomace (Aronia melanocarpa) which could be potentially coupled to a biorefinery process is proposed. This alternative is based on the application of pressurized liquid extraction (PLE) to the residue obtained after the supercritical fluid extraction of the berry pomace. An experimental design is employed to study and optimize the most relevant extraction conditions in order to attain extracts with high extraction yields, total phenols content and antioxidant activity. Moreover, the PLE extracts were characterized by using a new method based on the application of comprehensive two-dimensional liquid chromatography in order to correlate their activity with their chemical composition. Thanks to the use of this powerful analytical tool, 61 compounds could be separated being possible the tentative identification of different anthocyanins, proanthocyanidins, flavonoids and phenolic acids. By using the optimized PLE approach (using pressurized 46% ethanol in water at 165°C containing 1.8% formic acid), extracts with high total phenols content (236.6mg GAE g -1 extract) and high antioxidant activities (4.35mmol TE g -1 extract and EC 50 5.92μgmL -1 ) could be obtained with high yields (72.5%). Copyright © 2016 Elsevier B.V. All rights reserved.

Solvent viscosity mismatch between the solute plug and the mobile phase: Considerations in the applications of two-dimensional HPLC

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

Shalliker, R. Andrew; Guiochon, Georges A

Understanding the nature of viscosity contrast induced flow instabilities is an important aspect in the design of two-dimensional HPLC separations. When the viscosity contrast between the sample plug and the mobile phase is sufficiently large, the phenomenon known as viscous fingering can be induced. Viscous fingering is a flow instability phenomenon that occurs at the interface between two fluids with different viscosities. In liquid chromatography, viscous fingering results in the solute band undergoing a change in form as it enters into the chromatography column. Moreover, even in the absence of viscous fingering, band shapes change shape at low viscosity contrasts.more » These changes can result in a noticeable change in separation performance, with the result depending on whether the solvent pushing the solute plug has a higher or lower viscosity than the solute plug. These viscosity induced changes become more important as the solute injection volume increases and hence understanding the process becomes critical in the implementation of multidimensional HPLC techniques, since in these techniques the sample injection plug into the second dimension is an order of magnitude greater than in one-dimensional HPLC. This review article assesses the current understanding of the viscosity contrast induced processes as they relate to liquid chromatographic separation behaviour.« less

Advances in organic polymer-based monolithic column technology for high-resolution liquid chromatography-mass spectrometry profiling of antibodies, intact proteins, oligonucleotides, and peptides.

PubMed

Eeltink, Sebastiaan; Wouters, Sam; Dores-Sousa, José Luís; Svec, Frantisek

2017-05-19

This review focuses on the preparation of organic polymer-based monolithic stationary phases and their application in the separation of biomolecules, including antibodies, intact proteins and protein isoforms, oligonucleotides, and protein digests. Column and material properties, and the optimization of the macropore structure towards kinetic performance are also discussed. State-of-the-art liquid chromatography-mass spectrometry biomolecule separations are reviewed and practical aspects such as ion-pairing agent selection and carryover are presented. Finally, advances in comprehensive two-dimensional LC separations using monolithic columns, in particular ion-exchange×reversed-phase and reversed-phase×reversed-phase LC separations conducted at high and low pH, are shown. Copyright © 2017 Elsevier B.V. All rights reserved.

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.

Novel comprehensive multidimensional liquid chromatography approach for elucidation of the microbosphere of shikimate-producing Escherichia coli SP1.1/pKD15.071 strain.

PubMed

Cacciola, Francesco; Mangraviti, Domenica; Rigano, Francesca; Donato, Paola; Dugo, Paola; Mondello, Luigi; Cortes, Hernan J

2018-06-01

Shikimic acid is a intermediate of aromatic amino acid biosynthesis and the preferred starting material for production of the most commonly prescribed anti-influenza drug, Tamiflu. Its six-membered carbocyclic ring is adorned with several chiral centers and various functionalities, making shikimic acid a valuable chiral synthon. When microbially-produced, in addition to shikimic acid, numerous other metabolites are exported out of the cytoplasm and accumulate in the culture medium. This extracellular matrix of metabolites is referred to as the microbosphere. Due to the high sample complexity, in this study, the microbosphere of shikimate-producing Escherichia coli SP1.1/pKD15.071 was analyzed by liquid chromatography and comprehensive two-dimensional liquid chromatography coupled to photodiode array and mass spectrometry detection. GC analysis of the trimethylsilyl derivatives was also carried out in order to support the elucidation of the selected metabolites in the microbosphere. The elucidation of the metabolic fraction of this bacterial strain might be of valid aid for improving, through genetic changes, the concentration and yield of shikimic acid synthesized from glucose. Graphical abstract.

Two-dimensional turbulent flow chromatography coupled on-line to liquid chromatography-mass spectrometry for solution-based ligand screening against multiple proteins.

PubMed

Zhou, Jian-Liang; An, Jing-Jing; Li, Ping; Li, Hui-Jun; Jiang, Yan; Cheng, Jie-Fei

2009-03-20

We present herein a novel bioseparation/chemical analysis strategy for protein-ligand screening and affinity ranking in compound mixtures, designed to increase screening rates and improve sensitivity and ruggedness in performance. The strategy is carried out by combining on-line two-dimensional turbulent flow chromatography (2D-TFC) with liquid chromatography-mass spectrometry (LC-MS), and accomplished through the following steps: (1) a reversed-phase TFC stage to separate the protein/ligand complex from the unbound free molecules, (2) an on-line dissociation process to release the bound ligands from the complexes, and (3) a second mixed-mode cation-exchange/reversed-phase TFC stage to trap the bound ligands and to remove the proteins and salts, followed by LC-MS analysis for identification and determination of the binding affinities. The technique can implement an ultra-fast isolation of protein/ligand complex with the retention time of a complex peak in about 5s, and on-line prepare the "clean" sample to be directly compatible with the LC-MS analysis. The improvement in performance of this 2D-TFC/LC-MS approach over the conventional approach has been demonstrated by determining affinity-selected ligands of the target proteins acetylcholinesterase and butyrylcholinesterase from a small library with known binding affinities and a steroidal alkaloid library composed of structurally similar compounds. Our results show that 2D-TFC/LC-MS is a generic and efficient tool for high-throughput screening of ligands with low-to-high binding affinities, and structure-activity relationship evaluation.

NMR Techniques in Metabolomic Studies: A Quick Overview on Examples of Utilization.

PubMed

Kruk, Joanna; Doskocz, Marek; Jodłowska, Elżbieta; Zacharzewska, Anna; Łakomiec, Joanna; Czaja, Kornelia; Kujawski, Jacek

2017-01-01

Metabolomics is a rapidly developing branch of science that concentrates on identifying biologically active molecules with potential biomarker properties. To define the best biomarkers for diseases, metabolomics uses both models (in vitro, animals) and human, as well as, various techniques such as mass spectroscopy, gas chromatography, liquid chromatography, infrared and UV-VIS spectroscopy and nuclear magnetic resonance. The last one takes advantage of the magnetic properties of certain nuclei, such as 1 H, 13 C, 31 P, 19 F, especially their ability to absorb and emit energy, what is crucial for analyzing samples. Among many spectroscopic NMR techniques not only one-dimensional (1D) techniques are known, but for many years two-dimensional (2D, for example, COSY, DOSY, JRES, HETCORE, HMQS), three-dimensional (3D, DART-MS, HRMAS, HSQC, HMBC) and solid-state NMR have been used. In this paper, authors taking apart fundamental division of nuclear magnetic resonance techniques intend to shown their wide application in metabolomic studies, especially in identifying biomarkers.

Separation and characterization of chemical constituents in Ginkgo biloba extract by off-line hydrophilic interaction×reversed-phase two-dimensional liquid chromatography coupled with quadrupole-time of flight mass spectrometry.

PubMed

Ji, Shuai; He, Dan-Dan; Wang, Tian-Yun; Han, Jie; Li, Zheng; Du, Yan; Zou, Jia-Hui; Guo, Meng-Zhe; Tang, Dao-Quan

2017-11-30

Ginkgo biloba extract (GBE), derived from the leaves of Ginkgo biloba L., is one of the most widely used traditional Chinese medicines worldwide. Due to high structural diversity and low abundance of chemical constituents in GBE, conventional reversed-phase liquid chromatography has limited power to meet the needs of its quality control. In this study, an off-line hydrophilic interaction×reversed-phase two-dimensional liquid chromatography (HILIC×RP 2D-LC) system coupled with diode array detection (DAD) and quadrupole time-of-flight mass spectrometry (qTOF-MS) was established to comprehensively analyze the chemical constituents of GBE. After optimizing the chromatographic columns and mobile phase of 2D-LC, a Waters XBridge Amide column using acetonitrile/water/formic acid as the mobile phase was selected as the first dimension to fractionate GBE, and the obtained fractions were further separated on an Agilent Zorbax XDB-C18 column with methanol/water/formic acid as the mobile phase. As a result, a total of 125 compounds were detected in GBE. The orthogonality of the 2D-LC system was 69.5%, and the practical peak capacity was 3864 and 2994, respectively, calculated by two different methods. The structures of 104 compounds were tentatively characterized by qTOF-MS analysis, and 21 of them were further confirmed by comparing with reference standards. This established HILIC×RP 2D-LC-qTOF/MS system can greatly improve the separation and characterization of natural products in GBE or other complicated herbal extracts. Copyright © 2017 Elsevier B.V. All rights reserved.

Lipid and fatty acid analysis of the Plodia interpunctella granulosis virus (PiGV) envelope

NASA Technical Reports Server (NTRS)

Shastri-Bhalla, K.; Funk, C. J.; Consigli, R. A.; Spooner, B. S. (Principal Investigator)

1993-01-01

Virus envelope was isolated from Plodia interpunctella granulosis virus, produced in early fourth-instar larvae. Both polar and neutral lipids were analyzed by two-dimensional thin-layer chromatography. Fatty acid composition of various individual neutral and polar lipids was determined by gas-liquid chromatography. The major components of envelope neutral lipid were diacylglycerols. Palmitic acid and stearic acid were the major saturated fatty acids in both polar and neutral lipids. Whereas palmitoleic acid was the major unsaturated fatty acids in neutral lipids, oleic acid was the major unsaturated fatty acid in the polar lipids.

High-resolution proton nuclear magnetic resonance characterization of seminolipid from bovine spermatozoa.

PubMed

Alvarez, J G; Storey, B T; Hemling, M L; Grob, R L

1990-06-01

The high-resolution one- and two-dimensional proton nuclear magnetic resonance (1H-NMR) characterization of seminolipid from bovine spermatozoa is presented. The 1H-NMR data was confirmed by gas-liquid chromatography-mass spectrometric analysis of the partially methylated alditol acetates of the sugar unit, mild alkaline methanolysis of the glyceryl ester, mobility on normal phase and diphasic thin-layer chromatography (HPTLC), and fast atom bombardment mass spectrometry (FAB-MS). The structure of the molecule corresponds to 1-O-hexadecyl-2-O-hexadecanoyl-3-O-beta-D-(3'-sulfo)-galactopyranosyl- sn-glycerol.

Method development and application of offline two-dimensional liquid chromatography/quadrupole time-of-flight mass spectrometry-fast data directed analysis for comprehensive characterization of the saponins from Xueshuantong Injection.

PubMed

Yang, Wenzhi; Zhang, Jingxian; Yao, Changliang; Qiu, Shi; Chen, Ming; Pan, Huiqin; Shi, Xiaojian; Wu, Wanying; Guo, Dean

2016-09-05

Xueshuantong Injection (XSTI), derived from Notoginseng total saponins, is a popular traditional Chinese medicine injection for the treatment of thrombus-resultant diseases. Current knowledge on its therapeutic basis is limited to five major saponins, whereas those minor ones are rarely investigated. We herein develop an offline two-dimensional liquid chromatography/quadrupole time-of-flight mass spectrometry-fast data directed analysis (offline 2D LC/QTOF-Fast DDA) approach to systematically characterize the saponins contained in XSTI. Key parameters affecting chromatographic separation in 2D LC (including stationary phase, mobile phase, column temperature, and gradient elution program) and the detection by QTOF MS (involving spray voltage, cone voltage, and ramp collision energy) were optimized in sequence. The configured offline 2D LC system showed an orthogonality of 0.84 and a theoretical peak capacity of 8976. Total saponins in XSTI were fractionated into eleven samples by the first-dimensional hydrophilic interaction chromatography, which were further analyzed by reversed-phase UHPLC/QTOF-Fast DDA in negative ion mode. The fragmentation features evidenced from 36 saponin reference standards, high-accuracy MS and Fast-DDA-MS(2) data, elemental composition (C<80, H<120, O<50), double-bond equivalent (DBE 5-15), and searching an in-house library of Panax notoginseng, were simultaneously utilized for structural elucidation. Ultimately, 148 saponins were separated and characterized, and 80 have not been isolated from P. notoginseng. An in-depth depiction of the chemical composition of XSTI was achieved. The results obtained would benefit better understanding of the therapeutic basis and significant promotion on the quality standard of XSTI as well as other homologous products. Copyright © 2016. Published by Elsevier B.V.

Comprehensive Two-Dimensional Hydrophilic Interaction Chromatography (HILIC) × Reversed-Phase Liquid Chromatography Coupled to High-Resolution Mass Spectrometry (RP-LC-UV-MS) Analysis of Anthocyanins and Derived Pigments in Red Wine.

PubMed

Willemse, Chandré M; Stander, Maria A; Vestner, Jochen; Tredoux, Andreas G J; de Villiers, André

2015-12-15

Changes in anthocyanin chemistry represent some of the most important transformations involved in red wine aging. However, accurate analysis of the derived pigments, as required to study the evolution of anthocyanins and tannins during aging, is hampered by their extreme structural diversity, low levels, and the fact that many of these compounds have identical mass spectral characteristics. In this context, chromatographic separation is critical. In this contribution, the application of online hydrophilic interaction chromatography (HILIC) × reversed-phase liquid chromatography (RP-LC) separation coupled to high-resolution mass spectrometry (MS) is described for the detailed characterization of anthocyanins and their derived pigments in aged red wine. A systematic approach was followed for the optimization of HILIC × RP-LC separation parameters using a capillary liquid chromatography (LC) system in the first dimension and an ultrahigh-pressure LC system in the second dimension to ensure maximum sensitivity and performance. Ninety four (94) anthocyanin-derived pigments were tentatively identified in one- and six-year-old Pinotage wines using accurate mass and fragmentation information obtained using quadrupole-time-of-flight mass spectrometry (Q-TOF-MS). Online HILIC × RP-LC-MS was found to offer high-resolution separation, because of the combination of two different separation modes, while the structured elution order observed improved the certainty in compound identification. Therefore, this approach shows promise for the detailed elucidation of the chemical alteration of anthocyanins during wine aging.

Rapid screening and identification of antioxidants in the leaves of Malus hupehensis using off-line two-dimensional HPLC-UV-MS/MS coupled with a 1,1'-diphenyl-2-picrylhydrazyl assay.

PubMed

Liu, Minzhuo; Huang, Xueqian; Liu, Qi; Chen, Miao; Liao, Sen; Zhu, Fawei; Shi, Shuyun; Yang, Hua; Chen, Xiaoqing

2018-04-17

The leaves of Malus hupehensis have a strong antioxidant activity and are commonly consumed as a healthy tea. However, detailed information about its antioxidants is incomplete. Herein, we developed an effective strategy based on combining off-line two-dimensional high-performance liquid chromatography with ultraviolet and tandem mass spectrometry detection with a 1,1'-diphenyl-2-picrylhydrazyl assay to rapidly screen and identify the antioxidants from the leaves of M. hupehensis. In the orthogonal two-dimensional liquid chromatography system, a Venusil HILIC column was used for the first dimension, while a Universil XB-C 18 column was installed in the second dimension. As a result, 32 antioxidants, including ten dihydrochalcones, two flavanones, nine flavonols, four flavones, and seven phenolic acids were tentatively identified, out of which 23 compounds, as far as we know, were isolated and characterized from the leaves of M. hupehensis for the first time. To the best of our knowledge, this is the first systematic investigation of the antioxidants from the leaves of M. hupehensis. The results indicated that the proposed method is an efficient technique to rapidly investigate antioxidants, especially for coeluted and minor compounds in a complex system. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

High efficiency liquid chromatography techniques coupled to mass spectrometry for the characterization of mate extracts.

PubMed

Dugo, Paola; Cacciola, Francesco; Donato, Paola; Jacques, Rosângela Assis; Caramão, Elina Bastos; Mondello, Luigi

2009-10-23

There is growing interest related to rapid screening and full characterization of the constituents of plants with medicinal properties; among these, "Mate" or Yerba Maté is a tea-like beverage widely consumed in South America, obtained from the dried leaves of Ilex paraguariensis. The high content in polyphenols accounts for in vitro and in vivo antioxidant activity of the extracts obtained from this plant; on the other hand, the high complexity of the samples extracted, depending on the method employed, may preclude complete resolution by conventional HPLC techniques. For this purpose, a comprehensive two-dimensional liquid chromatography (LC x LC) system, comprised of an RP-Amide first dimension and a partially porous octadecylsilica column in the second dimension, has been compared with a one-dimensional system. The latter was operated using a partially porous octadecylsilica column, with diode array (DAD) and electrospray/ion trap-time of flight (ESI/IT-TOF) detection for the most complex extracts. The employment of the hybrid mass spectrometer allowed unequivocal identification of several compounds in the mate extracts. Using LC x LC-MS(3), it was possible to discriminate between congeners of chlorogenic acids, along with monoacyl- and diacylchlorogenic acid esters.

Characterization of sulfur and nitrogen compounds in Brazilian petroleum derivatives using ionic liquid capillary columns in comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometric detection.

PubMed

Cappelli Fontanive, Fernando; Souza-Silva, Érica Aparecida; Macedo da Silva, Juliana; Bastos Caramão, Elina; Alcaraz Zini, Claudia

2016-08-26

Diesel and naphtha samples were analyzed using ionic liquid (IL) columns to evaluate the best column set for the investigation of organic sulfur compounds (OSC) and nitrogen(N)-containing compounds analyses with comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry detector (GC×GC/TOFMS). Employing a series of stationary phase sets, namely DB-5MS/DB-17, DB-17/DB-5MS, DB-5MS/IL-59, and IL-59/DB-5MS, the following parameters were systematically evaluated: number of tentatively identified OSC, 2D chromatographic space occupation, number of polyaromatic hydrocarbons (PAH) and OSC co-elutions, and percentage of asymmetric peaks. DB-5MS/IL-59 was chosen for OSC analysis, while IL59/DB-5MS was chosen for nitrogen compounds, as each stationary phase set provided the best chromatographic efficiency for these two classes of compounds, respectively. Most compounds were tentatively identified by Lee and Van den Dool and Kratz retention indexes, and spectra-matching to library. Whenever available, compounds were also positively identified via injection of authentic standards. Copyright © 2016 Elsevier B.V. All rights reserved.

Effect of first dimension phase selectivity in online comprehensive two dimensional liquid chromatography (LC × LC)

PubMed Central

Gu, Haiwei; Huang, Yuan; Filgueira, Marcelo; Carr, Peter W.

2012-01-01

In this study, we examined the effect of first dimension column selectivity in reversed phase (RP) online comprehensive two dimensional liquid chromatography (LC × LC). The second dimension was always a carbon clad metal oxide reversed phase material. The hydrophobic subtraction model (HSM) and the related phase selective triangles were used to guide the selection of six different RP first dimension columns. Various kinds of samples were investigated and thus two different elution conditions were needed to cause full elution from the first dimension columns. We compared LC × LC chromatograms, contours plots, and fcoverage plots by measuring peak capacities, peak numbers, relative spatial coverage, correlation values, etc. The major finding of this study is that the carbon phase due to its rather different selectivity from other reversed phases is reasonably orthogonal to a variety of common types of bonded reversed phases. Thus quite surprisingly the six different first dimension stationary phases all showed generally similar separation patterns when paired to the second dimension carbon phase. This result greatly simplifies the task of choosing the correct pair of phases for RP × RP. PMID:21840009

Multi heart-cutting two-dimensional liquid chromatography-atmospheric pressure photoionization-tandem mass spectrometry method for the determination of endocrine disrupting compounds in water.

PubMed

Matějíček, David

2012-03-30

The multi-heart-cutting two-dimensional liquid chromatography-tandem mass spectrometry method using atmospheric pressure photoionization has been developed and successfully validated for the determination of nine endocrine disrupting compounds in river water. The method is based on the use of two different reverse-phase columns connected through a six-port two-position switching valve equipped with a 200 μl loop. An orthogonal separation was achieved by proper selection of stationary phases, mobile phases, and the use of a gradient elution in both dimensions. The method shows excellent performance in terms of accuracy (86.2-111.1%), precision (intra-batch: 6.7-11.2%, inter-batch: 7.2-13.5%), and sensitivity (1.2-7.1 ng l(-1)). Twenty real samples collected from the Loučka and the Svratka rivers were analyzed, the studied compounds were found in all Svratka samples (9.7-11.2 ng l(-1) for β-estradiol, 7.6-9.3 ng l(-1) for estrone, and 24.6-38.7 ng l(-1) for bisphenol A). Copyright © 2012 Elsevier B.V. All rights reserved.

Development of molecularly imprinted column-on line-two dimensional liquid chromatography for rapidly and selectively monitoring estradiol in cosmetics.

PubMed

Guo, Pengqi; Xu, Xinya; Xian, Liang; Ge, Yanhui; Luo, Zhimin; Du, Wei; Jing, Wanghui; Zeng, Aiguo; Chang, Chun; Fu, Qiang

2016-12-01

Nowadays, the illegal use of estradiol in cosmetics has caused a series of events which endangering public health seriously. Therefore, it is imperative to establish a simple, fast and specific method for monitoring the illegal use of estradiol in cosmetics. In current study, we developed a molecular imprinted monolithic column two dimensional liquid chromatography method (MIMC-2D-LC) for rapid and selective determination of estradiol in various cosmetic samples. The best polymerization, morphology, structure property, surface groups, and the adsorption performance of the prepared material were investigated. The MIMC-2D-LC was validated and successfully used for detecting estradiol in cosmetic samples with good selectivity, sensitivity, efficiency and reproducibility. The linear range of the MIMC-2D-LC for estradiol was 0.5-50μgg -1 with the limit of detection of 0.08μgg -1 . Finally, six batches of cosmetic samples obtained from local markets were tested by the proposed method. The test results showed that the illegal use of estradiol still existed in the commercially available samples. Copyright © 2016 Elsevier B.V. All rights reserved.

Development of a 45kpsi ultrahigh pressure liquid chromatography instrument for gradient separations of peptides using long microcapillary columns and sub-2μm particles.

PubMed

Grinias, Kaitlin M; Godinho, Justin M; Franklin, Edward G; Stobaugh, Jordan T; Jorgenson, James W

2016-10-21

Commercial chromatographic instrumentation for bottom-up proteomics is often inadequate to resolve the number of peptides in many samples. This has inspired a number of complex approaches to increase peak capacity, including various multidimensional approaches, and reliance on advancements in mass spectrometry. One-dimensional reversed phase separations are limited by the pressure capabilities of commercial instruments and prevent the realization of greater separation power in terms of speed and resolution inherent to smaller sorbents and ultrahigh pressure liquid chromatography. Many applications with complex samples could benefit from the increased separation performance of long capillary columns packed with sub-2μm sorbents. Here, we introduce a system that operates at a constant pressure and is capable of separations at pressures up to 45kpsi. The system consists of a commercially available capillary liquid chromatography instrument, for sample management and gradient creation, and is modified with a storage loop and isolated pneumatic amplifier pump for elevated separation pressure. The system's performance is assessed with a complex peptide mixture and a range of microcapillary columns packed with sub-2μm C18 particles. Copyright © 2016 Elsevier B.V. All rights reserved.

Fragmentation study of iridoid glycosides including epimers by liquid chromatography-diode array detection/electrospray ionization mass spectrometry and its application in metabolic fingerprint analysis of Gardenia jasminoides Ellis.

PubMed

Zhou, Tingting; Liu, Hua; Wen, Jun; Fan, Guorong; Chai, Yifeng; Wu, Yutian

2010-09-15

A high-performance liquid chromatography-diode array detection/electrospray ionization mass spectrometry (HPLC-DAD/ESI-MS) method was applied to the characterization of ten iridoid glycosides in Gardenia jasminoides Ellis, a traditional Chinese medicine. During the process of structural elucidation, two groups of isomers including two epimers were structurally characterized and differentiated according to their distinctive fragmentation patterns which were closely related to their isomeric differentiations. Subsequently, the major compounds were purified by multi-dimensional chromatography and semi-preparative HPLC and the structure identification was confirmed with NMR techniques. The major fragmentation pathways of iridoid glycosides in Gardenia jasminoides Ellis obtained through the MS data were schemed systematically, which provided the best sensitivity and specificity for characterization of the iridoid glycosides especially the isomers so far. Based on the fragmentation patterns of iridoid glycosides concluded, seven major iridoid glycosides were characterized in rat plasma after intravenous administration of Gardenia jasminoides Ellis. Copyright 2010 John Wiley & Sons, Ltd.

Comprehensive sample analysis using high performance liquid chromatography with multi-detection.

PubMed

Pravadali, Sercan; Bassanese, Danielle N; Conlan, Xavier A; Francis, Paul S; Smith, Zoe M; Terry, Jessica M; Shalliker, R Andrew

2013-11-25

Herein we assess the separation space offered by a liquid chromatography system with an optimised uni-dimensional separation for the determination of the key chemical entities in the highly complex matrix of a tobacco leaf extract. Multiple modes of detection, including UV-visible absorbance, chemiluminescence (acidic potassium permanganate, manganese(IV), and tris(2,2'-bipyridine)ruthenium(III)), mass spectrometry and DPPH radical scavenging were used in an attempt to systematically reduce the data complexity of the sample whilst obtaining a greater degree of molecule-specific information. A large amount of chemical data was obtained, but several limitations in the ability to assign detector responses to particular compounds, even with the aid of complementary detection systems, were observed. Thirty-three compounds were detected via MS on the tobacco extract and 12 out of 32 compounds gave a peak height ratio (PHR) greater than 0.33 on one or more detectors. This paper serves as a case study of these limitations, illustrating why multidimensional chromatography is an important consideration when developing a comprehensive chemical detection system. Copyright © 2013 Elsevier B.V. All rights reserved.

Comparison of originator and biosimilar therapeutic monoclonal antibodies using comprehensive two-dimensional liquid chromatography coupled with time-of-flight mass spectrometry.

PubMed

Sorensen, Matthew; Harmes, David C; Stoll, Dwight R; Staples, Gregory O; Fekete, Szabolcs; Guillarme, Davy; Beck, Alain

2016-10-01

As research, development, and manufacturing of biosimilar protein therapeutics proliferates, there is great interest in the continued development of a portfolio of complementary analytical methods that can be used to efficiently and effectively characterize biosimilar candidate materials relative to the respective reference (i.e., originator) molecule. Liquid phase separation techniques such as liquid chromatography and capillary electrophoresis are powerful tools that can provide both qualitative and quantitative information about similarities and differences between reference and biosimilar materials, especially when coupled with mass spectrometry. However, the inherent complexity of these protein materials challenges even the most modern one-dimensional (1D) separation methods. Two-dimensional (2D) separations present a number of potential advantages over 1D methods, including increased peak capacity, 2D peak patterns that can facilitate unknown identification, and improvement in the compatibility of some separation methods with mass spectrometry. In this study, we demonstrate the use of comprehensive 2D-LC separations involving cation-exchange (CEX) and reversed-phase (RP) separations in the first and second dimensions to compare 3 reference/biosimilar pairs of monoclonal antibodies (cetuximab, trastuzumab and infliximab) that cover a range of similarity/disimilarity in a middle-up approach. The second dimension RP separations are coupled to time-of-flight mass spectrometry, which enables direct identification of features in the chromatograms obtained from mAbs digested with the IdeS enzyme, or digestion with IdeS followed by reduction with dithiothreitol. As many as 23 chemically unique mAb fragments were detected in a single sample. Our results demonstrate that these rich datasets enable facile assesment of the degree of similarity between reference and biosimilar materials.

Identification of selenium-containing proteins in HEK 293 kidney cells using multiple chromatographies, LC-ICPMS and nano-LC-ESIMS.

PubMed

Chitta, Karnakar R; Landero-Figueroa, Julio A; Kodali, Phanichand; Caruso, Joseph A; Merino, Edward J

2013-09-30

Our previous studies using HeLa and HEK 293 cells demonstrated that selenomethionine, SeMet, exerts more of an antagonistic effect on arsenic than other selenium species. These studies attributed the antagonistic effect of SeMet to decreased levels of reactive oxygen species, ROS, changes in protein phosphorylation and possible incorporation of SeMet into proteins. The present study employs a metallomics approach to identify the selenium-containing proteins in HEK 293 cells raised with SeMet. The proteins were screened and separated using two dimensional high performance liquid chromatography (HPLC)-inductively coupled plasma mass spectrometry (ICPMS), size exclusion chromatography (SEC) and reversed-phase chromatography (RPC). The Se-containing proteins were identified by peptide mapping using nano-HPLC-Chip-electrospray ionization mass spectrometry (ESIMS). Copyright © 2013 Elsevier B.V. All rights reserved.

Modeling RP-1 Fuel Advanced Distillation Data using Comprehensive Two-Dimensional Gas Chromatography Coupled with Time-of-Flight Mass Spectrometry and Partial Least Squares Analysis

DTIC Science & Technology

2014-05-07

of a variety of complex liquid samples including, but not limited to, crude oil [12], gasoline [16], biodiesel fuel [17, 19], jet fuel [5, 10, 11...doi: 10.1021/ie302399v 19. Bruno TJ, Wolk A, Naydich A (2009) Stabilization of Biodiesel Fuel at Elevated Temperature with Hydrogen Donors

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

Effect of Genetic Database Comprehensiveness on Fractional Proteomics of Escherichia coli O157:H7

DTIC Science & Technology

2014-01-01

proteins would be observed in the extracellular fraction. 15. SUBJECT TERMS Escherichia coli O157:H7 Liquid chromatography Mass spectrometry...Preparation ...............1 2.2 Liquid Chromatography /Mass Spectrometry Sample Preparation ....................2 2.3 Liquid Chromatography /Mass... Chromatography /Mass Spectrometry Sample Preparation. Samples were prepared for liquid chromatography tandem mass spectrometry (LC-MS/MS) in a similar

Quantitative characterization of the aqueous fraction from hydrothermal liquefaction of algae

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

Maddi, Balakrishna; Panisko, Ellen; Wietsma, Thomas

Aqueous streams generated from hydrothermal liquefaction contain approximately 30% of the total carbon present from the algal feed. Hence, this aqueous carbon must be utilized to produce liquid fuels and/or specialty chemicals for economic sustainability of hydrothermal liquefaction on industrial scale. In this study, aqueous fractions produced from the hydrothermal liquefaction of fresh water and saline water algal cultures were analyzed using a wide variety of analytical instruments to determine their compositional characteristics. This study will also inform researchers designing catalysts for down-stream processing such as high-pressure catalytic conversion of organics in aqueous phase, catalytic hydrothermal gasification, and biological conversions.more » Organic chemical compounds present in all eight aqueous fractions were identified using two-dimensional gas chromatography equipped with time-of-flight mass spectrometry. Identified compounds include organic acids, nitrogen compounds and aldehydes/ketones. Conventional gas chromatography and liquid chromatography methods were utilized to quantify the identified compounds. Inorganic species in the aqueous stream of hydrothermal liquefaction of algae were identified using ion chromatography and inductively coupled plasma optical emission spectrometer. The concentrations of organic chemical compounds and inorganic species are reported. The amount quantified carbon ranged from 45 to 72 % of total carbon in the aqueous fractions.« less

Comprehensive two-dimensional liquid chromatographic analysis of poloxamers.

PubMed

Malik, Muhammad Imran; Lee, Sanghoon; Chang, Taihyun

2016-04-15

Poloxamers are low molar mass triblock copolymers of poly(ethylene oxide) (PEO) and poly(propylene oxide) (PPO), having number of applications as non-ionic surfactants. Comprehensive one and two-dimensional liquid chromatographic (LC) analysis of these materials is proposed in this study. The separation of oligomers of both types (PEO and PPO) is demonstrated for several commercial poloxamers. This is accomplished at the critical conditions for one of the block while interaction for the other block. Reversed phase LC at CAP of PEO allowed for oligomeric separation of triblock copolymers with regard to PPO block whereas normal phase LC at CAP of PPO renders oligomeric separation with respect to PEO block. The oligomeric separation with regard to PEO and PPO are coupled online (comprehensive 2D-LC) to reveal two-dimensional contour plots by unconventional 2D IC×IC (interaction chromatography) coupling. The study provides chemical composition mapping of both PEO and PPO, equivalent to combined molar mass and chemical composition mapping for several commercial poloxamers. Copyright © 2016 Elsevier B.V. All rights reserved.

21 CFR 862.2260 - High pressure 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 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...

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...

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...

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...

21 CFR 862.2260 - High pressure 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 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...

Fingerprinting of traditional Chinese medicines on the C18-Diol mixed-mode column in online or offline two-dimensional liquid chromatography on the single column modes.

PubMed

Wang, Qing; Tong, Ling; Yao, Lin; Zhang, Peng; Xu, Li

2016-06-05

In the present study, a mixed-mode stationary phase, C18-Diol, was applied for fingerprint analysis of traditional Chinese medicines. Hydrophobic, hydrogen bonding and electrostatic interactions were demonstrated to contribute the retention separately or jointly, which endowed the C18-Diol stationary phase with distinct selectivity compared to the bare C18 one. The separation of total alkaloids extracted from Fritillaria hupehensis was compared on the C18-Diol and conventional C18 column with the greater resolving power and better symmetry responses on the former one. Besides, a novel two-dimensional liquid chromatography on the single column (2D-LC-1C) was realized on C18-Diol with the offline mode for the alcohol extract of Fritillaria hupehensis and online mode for Ligusticum chuanxiong Hort. The early co-eluted extracted components with great polarity on the first dimension were reinjected on the same column and well separated on the second dimension. The results exhibited that the two complementary RPLC and HILIC modes on C18-Diol stationary phase enhanced the separation capacity and revealed more abundant chemical information of the sample, which was a powerful tool in analyzing complex herbal medicines. Copyright © 2016 Elsevier B.V. All rights reserved.

A not-stop-flow online normal-/reversed-phase two-dimensional liquid chromatography-quadrupole time-of-flight mass spectrometry method for comprehensive lipid profiling of human plasma from atherosclerosis patients.

PubMed

Li, Min; Tong, Xunliang; Lv, Pu; Feng, Baosheng; Yang, Li; Wu, Zheng; Cui, Xinge; Bai, Yu; Huang, Yining; Liu, Huwei

2014-11-03

A not-stop-flow online two-dimensional (2D) liquid chromatography (LC) method was developed for comprehensive lipid profiling by coupling normal- and reversed-phase LC with quadrupole time-of-flight mass spectrometry (QToF-MS), which was then applied to separate and identify the lipid species in plasma, making its merits in quality and quantity of the detection of lipids. Total 540 endogenous lipid species from 17 classes were determined in human plasma, and the differences in lipid metabolism products in human plasma between atherosclerosis patients and control subjects were explored in detail. The limit of detections (LODs) of 19 validation standards could all reach ng/mL magnitude, and the RSDs of peak area and retention time ranged 0.4-8.0% and 0.010-0.47%, respectively. In addition, a pair of isomers, galactosylceramides (GalC) and glucosylceramides (GluC), was successfully separated, showing that only the levels of GalC in atherosclerosis patients were significantly increasing, rather than GluC, compared with the controls (controls vs. patients: the ratio was 1.5-2.8-fold increasing). It would be helpful to the further research of the atherosclerosis. Copyright © 2014 Elsevier B.V. All rights reserved.

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 coating...

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 coating...

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 coating...

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... pressure. The device may include accessories such as columns, gases, column supports, and liquid coating...

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... pressure. The device may include accessories such as columns, gases, column supports, and liquid coating...

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

PubMed

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

2015-03-01

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

Phospholipid and fatty acid compositions of Rhizobium leguminosarum biovar trifolii ANU843 in relation to flavone-activated pSym nod gene expression.

PubMed

Orgambide, G G; Huang, Z H; Gage, D A; Dazzo, F B

1993-11-01

The phospholipid and associated fatty acid compositions of the bacterial symbiont of clover, Rhizobium leguminosarum biovar trifolii wild-type ANU843, was analyzed by two-dimensional silica thin-layer chromatography, fast atom bombardment-mass spectrometry, flame-ionization detection gas-liquid chromatography and combined gas-liquid chromatography/mass spectrometry. The phospholipid composition included phosphatidylethanolamine (15%), N-methylphosphatidylethanolamine (47%), N,N-dimethylphosphatidylethanolamine (9%), phosphatidylglycerol (19%), cardiolipin (5%) and phosphatidylcholine (2%). Fatty acid composition included predominantly cis-11-octadecenoic acid, lower levels of cis-9-hexadecenoic acid, hexadecanoic acid, 11-methyl-11-octadecenoic acid, octadecanoic acid, 11,12-methyleneoctadecanoic acid, eicosanoic acid and traces of branched, and di- and triunsaturated fatty acids. The influence of expression of the "nodulation" genes encoding symbiotic functions on the composition of these membrane lipids was examined in wild-type cells grown with or without the flavone inducer, 4',7-dihydroxyflavone and in mutated cells lacking the entire symbiotic plasmid where these genes reside, or containing single transposon insertions in selected nodulation genes. No significant changes in phospholipid or associated fatty acid compositions were detected by the above methods of analysis.

Simultaneous quantitation of five Panax notoginseng saponins by multi heart-cutting two-dimensional liquid chromatography: Method development and application to the quality control of eight Notoginseng containing Chinese patent medicines.

PubMed

Yao, Chang-liang; Yang, Wen-zhi; Wu, Wan-Yyng; Da, Juan; Hou, Jin-jun; Zhang, Jing-xian; Zhang, Yan-hai; Jin, Yan; Yang, Min; Jiang, Bao-hong; Liu, Xuan; Guo, De-an

2015-07-10

Current China Pharmacopoeia (ChP) standards employ diversified and case-dependent assay methods to evaluate the quality of different Chinese patent medicines (CPMs) that contain Panax notoginseng as the monarch drug. These conventional, HPLC-based approaches, utilizing a complex sample preparation procedure, can easily result in low analytical efficiency and possible component loss. Here, a "monomethod-heterotrait matrix" (MHM) strategy is proposed, that is, developing a universal multi heart-cutting two-dimensional liquid chromatography (MHC-2D-LC) approach that facilitates the simultaneous quantitation of five P. notoginseng saponins (noto-R1, Re, Rg1, Rb1, and Rd) in eight different CPMs. The MHC-2D-LC system was constructed on a dual-gradient liquid chromatography instrument equipped with a Poroshell SB C18 column and a Zorbax SB-Aq column for respective (1)D and (2)D separation. Method validation was performed in terms of specificity, linearity (r(2) and F-test), intra-/inter-day precision (0.4-7.9%), stability (1.2-3.9%), and recovery (90.2-108.7%), and the LODs and LOQs (loaded masses) of the five analytes varied between 4.0-11.0ng and 6.0-33.0ng, respectively. The validated MHC-2D-LC approach was subsequently applied to quantify the five saponins in thirty batches of different CPMs. The method demonstrated superiority over the current ChP assay methods in respect of specificity (avoiding co-elution), resolution (Rs>1.5), sample preparation (easy-to-implement ultrasonic extraction without repeated re-extraction), and transfer rate (minimum component loss). This is the first application of an MHC-2D-LC method for the quantitative assessment of the constituents of CPMs. The MHM approach represents a new, strategically significant methodology for the quality control of CPMs that involve complex chemical matrix. Copyright © 2015 Elsevier B.V. All rights reserved.

An enhanced targeted identification strategy for the selective identification of flavonoid O-glycosides from Carthamus tinctorius by integrating offline two-dimensional liquid chromatography/linear ion-trap-Orbitrap mass spectrometry, high-resolution diagnostic product ions/neutral loss filtering and liquid chromatography-solid phase extraction-nuclear magnetic resonance.

PubMed

Yao, Chang-Liang; Yang, Wen-Zhi; Si, Wei; Shen, Yao; Zhang, Nai-Xia; Chen, Hua-Li; Pan, Hui-Qin; Yang, Min; Wu, Wan-Ying; Guo, De-An

2017-03-31

Targeted identification of potentially bioactive molecules from herbal medicines is often stymied by the insufficient chromatographic separation, ubiquitous matrix interference, and pervasive isomerism. An enhanced targeted identification strategy is presented and validated by the selective identification of flavonoid O-glycosides (FOGs) from Carthamus tinctorius. It consists of four steps: (i) enhanced separation and detection by offline two-dimensional liquid chromatography/LTQ-Orbitrap MS (offline 2D-LC/LTQ-Orbitrap MS) using collision-induced dissociation (CID) and high-energy C-trap dissociation (HCD); (ii) improved identification of the major aglycones by acid hydrolysis and LC-SPE-NMR; (iii) simplified spectral elucidation by high-resolution diagnostic product ions/neutral loss filtering; and (iv) more convincing structural identification by matching an in-house library. An offline 2D-LC system configuring an Acchrom XAmide column and a BEH Shield RP-18 UPLC ® column enabled much better separation of the easily co-eluting components. Combined use of CID and HCD could produce complementary fragmentation information. The intensity ratios of the aglycone ion species ([Y 0 -H] - /Y 0 - and [Y 0 -2H] - /Y 0 - ) in the HCD-MS 2 spectra were found diagnostic for discriminating the aglycone subtypes and characterizing the glycosylation patterns. Five aglycone structures (kaempferol, 6-hydroxykaempferol, 6-methoxykaempferol, carthamidin, and isocarthamidin) were identified based on the 1 H-NMR data recorded by LC-SPE-NMR. Of the 107 characterized flavonoids, 80 FOGs were first reported from C. tinctorius. Unknown aglycones, pentose, and novel acyl substituents were discovered. A new compound thereof was isolated and fully identified, which could partially validate the MS-oriented identification. This integral strategy can improve the potency, efficiency, and accuracy in the detection of new compounds from medicinal herbs and other natural sources. Copyright © 2017 Elsevier B.V. All rights reserved.

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)

Identification of novel sulfur-containing steroids in sediments and petroleum: probable incorporation of sulfur into δ 5,7-sterols during early diagenesis

NASA Astrophysics Data System (ADS)

Sinninghe Damsté, Jaap S.; Schouten, Stefan; de Leeuw, Jan W.; van Duin, Adri C. T.; Geenevasen, Jan A. J.

1999-01-01

A novel sulfur-containing sterane, 4α,7α-epithio-5β-cholestane, has been identified in a sediment extract from the Miocene Northern Apennines marl (Italy) after its isolation by column chromatography and high pressure liquid chromatography. The compound has been characterised by GC-MS and mild Nickel boride desulfurisation and one and two-dimensional 1H NMR techniques. C 27-C 29 homologs have been detected in sediment extracts of three different formations and in one petroleum sample. These sulfur-containing steroids are probably formed by an intramolecular reaction of inorganic sulfides with early diagenetic products of Δ 5,7-sterols.

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.

[Analysis of microalbuminuria with immunonephelometry and high performance liquid chromatography. Evaluation of new criteria].

PubMed

Markó, Lajos; Molnár, Gergo Attila; Wagner, Zoltán; Koszegi, Tamás; Matus, Zoltán; Mohás, Márton; Kuzma, Mónika; Szijártó, István András; Wittmann, István

2008-01-13

Hypertension as well as type 2 diabetes mellitus is a major factor in population mortality. Both diseases damage the endothelium, the early sign of which is microalbuminuria, which can be screened by dipstick and can be diagnosed by using immuno-based and high performance liquid chromatography methods. Using high performance liquid chromatography, the non-immunoreactive albumin can be detected as well. The authors aimed at the examination of albuminuria in the case of immunonephelometrically negative patients with high performance liquid chromatography, in diabetic and hypertensive and non-diabetic hypertensive populations. The authors also wanted to compare the present (albumin-creatinine ratio: male: > or =2.5 mg/mmol, female: > or =3.5 mg/mmol) and a new criteria of the Heart Outcomes Prevention Evaluation study (patients without diabetes: immunological method, > or =0.7 mg/mmol; high performance liquid chromatography, > or =3.1 mg/mmol; individuals with diabetes: immunological method, > or =1.4 mg/mmol; high performance liquid chromatography, > or =5.2 mg/mmol) of microalbuminuria. Examination of fresh urines of 469 microalbuminuria negative patients by dipstick were performed by immunonephelometry. Patients, who were microalbuminuria negative by immunonephelometry as well, were further analyzed by high performance liquid chromatography using the Accumintrade mark Kit, based on size-exclusion chromatography. Three times higher albuminuria were found with high performance liquid chromatography than with immunonephelometry. The intraindividual coefficient of variation did not differ in the two methods (37 +/- 31% vs. 40 +/- 31%, p = 0.869; immunonephelometry vs. high performance liquid chromatography; mean +/- standard deviation). Using the present criteria for microalbuminuria, 43% of immunonephelometrically negative patients proved to be microalbuminuric by high performance liquid chromatography. Using the new criteria of the Heart Outcomes Prevention Evaluation study, the rate of microalbuminuria positivity among the immunonephelometrically negative patients decreased to 14.5% by high performance liquid chromatography and the decrease in the number of microalbuminuria positive cases by high performance liquid chromatography could be observed mainly in the diabetic and hypertensive group (49% vs. 7.5%), while slighter decrease could be observed in the non-diabetic hypertensive group (37% vs. 26.5%). Applying the traditional criteria, the strongest predictor was the male gender by the logistic regression analysis. In 28% of microalbuminuria negative patients by immunonephelometry the diagnosis of microalbuminuria can be established using high performance liquid chromatography. Almost in one-third of microalbuminuria negative patients by immunonephelometry the diagnosis of microalbuminuria can be established by high performance liquid chromatography for which diagnosis three constitutive urine examinations are still needed. New criteria determined by the Heart Outcomes Prevention Evaluation study can be used neither in case of diabetic and hypertensive patients, nor in the case of non-diabetic hypertensive patients. The gender as the most important predictor of microalbuminuria cannot be ignored.

Identification, isolation, and N-terminal sequencing of style glycoproteins associated with self-incompatibility in Nicotiana alata.

PubMed

Jahnen, W; Batterham, M P; Clarke, A E; Moritz, R L; Simpson, R J

1989-05-01

S-Gene-associated glycoproteins (S-glycoproteins) from styles of Nicotiana alata, identified by non-equilibrium two-dimensional electrophoresis, were purified by cation exchange fast protein liquid chromatography with yields of 0.5 to 8 micrograms of protein per style, depending on the S-genotype of the plant. The method relies on the highly basic nature of the S-glycoproteins. The elution profiles of the different S-glycoproteins from the fast protein liquid chromatography column were characteristic of each S-glycoprotein, and could be used to establish the S-genotype of plants in outbreeding populations. In all cases, the S-genotype predicted from the style protein profile corresponded to that predicted from DNA gel blot analysis using S-allele-specific DNA probes and to that established by conventional breeding tests. Amino-terminal sequences of five purified S-glycoproteins showed a high degree of homology with the previously published sequences of N. alata and Lycopersicon esculentum S-glycoproteins.

Identification of Apolipoprotein C-I as a Potential Wilms’ Tumor Marker after Excluding Inflammatory Factors

PubMed Central

Zhang, Junjie; Guo, Fei; Wang, Lei; Zhao, Wei; Zhang, Da; Yang, Heying; Yu, Jiekai; Niu, Lili; Yang, Fuquan; Zheng, Shu; Wang, Jiaxiang

2014-01-01

Wilms’ tumor is one of the most common malignant tumors observed in children, and its early diagnosis is important for late-stage treatment and prognosis. We previously screened and identified protein markers for Wilms’ tumor; however, these markers lacked specificity, and some were associated with inflammation. In the current study, serum samples from children with Wilms’ tumors were compared with those of healthy controls and patients with systemic inflammatory response syndrome (SIRS). After exclusion of factors associated with inflammation, specific protein markers for Wilms’ tumors were identified. After comparing the protein peak values obtained from all three groups, a protein with a m/z of 6438 Da was specified. Purification and identification of the target protein using high-pressure liquid chromatography (HPLC) and two-dimensional liquid chromatography-linearion trap mass spectrometry(2D-LC-LTQ-MS) mass spectrometry, respectively, revealed that it was apolipoprotein C-I (APO C-I). Thus, APO C-I is a specific protein marker for Wilms’ tumor. PMID:25222555

A novel high-throughput method for supported liquid extraction of retinol and alpha-tocopherol from human serum and simultaneous quantitation by liquid chromatography tandem mass spectrometry.

PubMed

Hinchliffe, Edward; Rudge, James; Reed, Paul

2016-07-01

Measurement of vitamin A (retinol) and E (alpha-tocopherol) in UK clinical laboratories is currently performed exclusively by high-performance liquid chromatography with ultraviolet detection. We investigated whether retinol and alpha-tocopherol could be measured simultaneously by liquid chromatography tandem mass spectrometry. Serum samples (100 μL) were extracted using Isolute + Supported Liquid Extraction plates. Chromatography was performed on a Phenomenex Kinetex Biphenyl 2.6 μm, 50 × 2.1 mm column, and liquid chromatography tandem mass spectrometry on a Waters Acquity TQD. Injection-to-injection time was 4.3 min. The assay was validated according to published guidelines. Patient samples were used to compare liquid chromatography tandem mass spectrometry and high-performance liquid chromatography with ultraviolet detection methods. For retinol and alpha-tocopherol, respectively, the assay was linear up to 6.0 and 80.0 μmol/L, and lower limit of quantification was 0.07 and 0.26 μmol/L. Intra and interassay imprecision were within desirable analytical specifications. Analysis of quality control material aligned to NIST SRM 968e, and relative spiked recovery from human serum, both yielded results within 15% of target values. Method comparison with high-performance liquid chromatography with ultraviolet detection methodology demonstrated a negative bias for retinol and alpha-tocopherol by the liquid chromatography tandem mass spectrometry method. Analysis of United Kingdom National External Quality Assurance Scheme samples yielded mean bias from the target value of +3.0% for retinol and -11.2% for alpha-tocopherol. We have developed a novel, high-throughput method for extraction of retinol and alpha-tocopherol from human serum followed by simultaneous quantitation by liquid chromatography tandem mass spectrometry. The method offers a rapid, sensitive, specific and cost-effective alternative to high-performance liquid chromatography with ultraviolet detection methodology, and is suitable for routine clinical monitoring of patients predisposed to fat-soluble vitamin malabsorption. © The Author(s) 2015.

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,…

Fast comprehensive two-dimensional gas chromatography method for fatty acid methyl ester separation and quantification using dual ionic liquid columns.

PubMed

Nosheen, Asia; Mitrevski, Blagoj; Bano, Asghari; Marriott, Philip J

2013-10-18

Safflower oil is a complex mixture of C18 saturated and unsaturated fatty acids amongst other fatty acids, and achieving separation between these similar structure components using one dimensional gas chromatography (GC) may be difficult. This investigation aims to obtain improved separation of fatty acid methyl esters in safflower oil, and their quantification using comprehensive two-dimensional GC (GC×GC). Here, GC×GC separation is accomplished by the coupling of two ionic liquid (IL) column phases: the combination of SLB-IL111 with IL59 column phases was finally selected since it provided excellent separation of a FAME standard mixture, as well as fatty acids in safflower and linseed oil, compared to other tested column sets. Safflower oil FAME were well separated in a short run of 16min. FAME validation was demonstrated by method reproducibility, linearity over a range up to 500mgL(-1), and limits of detection which ranged from 1.9mgL(-1) to 5.2mgL(-1) at a split ratio of 20:1. Quantification was carried out using two dilution levels of 200-fold for major components and 20-fold for trace components. The fatty acids C15:0 and C17:0 were not reported previously in safflower oil. The SLB-IL111/IL59 column set proved to be an effective and novel configuration for separation and quantification of vegetable and animal oil fatty acids. Copyright © 2013 Elsevier B.V. All rights reserved.

Optimization of a two-dimensional liquid chromatography-supercritical fluid chromatography-mass spectrometry (2D-LC-SFS-MS) system to assess "in-vivo" inter-conversion of chiral drug molecules.

PubMed

Goel, Meenakshi; Larson, Eli; Venkatramani, C J; Al-Sayah, Mohammad A

2018-05-01

Enantioselective analysis is an essential requirement during the pharmaceutical development of chiral drug molecules. In pre-clinical and clinical studies, the Food and Drug Administration (FDA) mandates the assessment of "in vivo" inter-conversion of chiral drugs to determine their physiological effects. In-vivo analysis of the active pharmaceutical ingredient (API) and its potential metabolites could be quite challenging due to their low abundance (ng/mL levels) and matrix interferences. Therefore, highly selective and sensitive analytical techniques are required to separate the API and its metabolites from the matrix components and one another. Additionally, for chiral APIs, further analytical separation is required to resolve the API and its potential metabolites from their corresponding enantiomers. In this work, we demonstrate the optimization of our previously designed two-dimensional liquid chromatography-supercritical fluid chromatography-mass spectrometry (2D-LC-SFC -MS) system to achieve 10 ng/mL detection limit [1]. The first LC dimension, used as a desalting step, could efficiently separate the API from its potential metabolites and matrix components. The API and its metabolites were then trapped/focused on small trapping columns and transferred onto the second SFC dimension for chiral separation. Detection can be achieved by ultra-violet (UV) or MS detection. Different system parameters such as column dimensions, transfer volumes, trapping column stationary phase, system tubing internal diameter (i.d.), and detection techniques, were optimized to enhance the sensitivity of the 2D-LC-SFC-MS system. The limit of detection was determined to be 10 ng/mL. An application is described where a mouse hepatocyte treated sample was analyzed using the optimized 2D-LC-SFC-MS system with successful assessment of the ratio of API to its metabolite (1D-LC), as well as the corresponding enantiomeric excess values (% e.e.) of each (2D-SFC). Copyright © 2018 Elsevier B.V. All rights reserved.

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.

Rational and Efficient Preparative Isolation of Natural Products by MPLC-UV-ELSD based on HPLC to MPLC Gradient Transfer.

PubMed

Challal, Soura; Queiroz, Emerson Ferreira; Debrus, Benjamin; Kloeti, Werner; Guillarme, Davy; Gupta, Mahabir Prashad; Wolfender, Jean-Luc

2015-11-01

In natural product research, the isolation of biomarkers or bioactive compounds from complex natural extracts represents an essential step for de novo identification and bioactivity assessment. When pure natural products have to be obtained in milligram quantities, the chromatographic steps are generally labourious and time-consuming. In this respect, an efficient method has been developed for the reversed-phase gradient transfer from high-performance liquid chromatography to medium-performance liquid chromatography for the isolation of pure natural products at the level of tens of milligrams from complex crude natural extracts. The proposed method provides a rational way to predict retention behaviour and resolution at the analytical scale prior to medium-performance liquid chromatography, and guarantees similar performances at both analytical and preparative scales. The optimisation of the high-performance liquid chromatography separation and system characterisation allows for the prediction of the gradient at the medium-performance liquid chromatography scale by using identical stationary phase chemistries. The samples were introduced in medium-performance liquid chromatography using a pressure-resistant aluminium dry load cell especially designed for this study to allow high sample loading while maintaining a maximum achievable flow rate for the separation. The method has been validated with a mixture of eight natural product standards. Ultraviolet and evaporative light scattering detections were used in parallel for a comprehensive monitoring. In addition, post-chromatographic mass spectrometry detection was provided by high-throughput ultrahigh-performance liquid chromatography time-of-flight mass spectrometry analyses of all fractions. The processing of all liquid chromatography-mass spectrometry data in the form of an medium-performance liquid chromatography x ultra high-performance liquid chromatography time-of-flight mass spectrometry matrix enabled an efficient localisation of the compounds of interest in the generated fractions. The methodology was successfully applied for the separation of three different plant extracts that contain many diverse secondary metabolites. The advantages and limitations of this approach and the theoretical chromatographic background that rules such as liquid chromatography gradient transfer are presented from a practical viewpoint. Georg Thieme Verlag KG Stuttgart · New York.

Application of a trap-free two-dimensional liquid chromatography combined with ion trap/time-of-flight mass spectrometry for separation and characterization of impurities and isomers in cefpiramide.

PubMed

Wang, Jian; Xu, Yu; Wen, Chunmei; Wang, Zhijian

2017-11-01

High-resolution mass spectrometry had been routinely used for structure identification of impurity. However, all LC-MS methods were based on a volatile mobile phase, and a non-volatile system is used in the official analytical method of United States Pharmacopoeia for cefpiramide which limited the use of mass spectrometry for structure characterization of the impurities. Here we presented the utilization of a trap-free two-dimensional liquid chromatography coupled to high resolution ion trap/time-of-flight mass spectrometry (2D LC-IT-TOF MS) with positive and negative modes of electrospray ionization for characterization of eight impurities in cefpiramide. Trap-free two-dimensional liquid chromatography and online desalting technique made it possible to characterize the impurity in cefpiramide in the condition of official standard, and the TIC chromatogram of LC-MS was in conformity with the LC chromatogram of the official analytical method in the peak sequence of impurities, which could further improve the method of official monographs in pharmacopoeias. Each peak separated by the non-volatile mobile phase was trapped by a 20 μL quantitative loop then transferred into a system with a volatile mobile phase connected to a MS detector. In the first dimension, the column was Kromasil C 8 analytical column (250 mm × 4.6 mm, 5 μm) with a non-volatile salt mobile phase at the flow rate of 0.8 mL min -1 . In the second dimension, the column was Shimadzu Shim-pack GISS C 18 (50 mm × 2.1 mm, 1.9 μm) with a volatile salt mobile phase at the flow rate of 0.3 mL min -1 . Through the multiple heart-cutting 2D-LC approach and online desalting technique, the problem of incompatibility between non-volatile salt mobile phase and mass spectrometry was solved completely. The fragmentation behavior of cefpiramide and its eight impurities were studied. The structures of eight impurities in cefpiramide drug substance were deduced based on the HPLC-MS n data, in which seven impurities were novel impurities. The forming mechanisms of degradation products in cefpiramide were also studied. Copyright © 2017 Elsevier B.V. All rights reserved.

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)

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.

The Combination Process for Preparative Separation and Purification of Paclitaxel and 10-Deacetylbaccatin III Using Diaion® Hp-20 Followed by Hydrophilic Interaction Based Solid Phase Extraction.

PubMed

Shirshekanb, Mahsa; Rezadoost, Hassan; Javanbakht, Mehran; Ghassempour, Ali Reza

2017-01-01

There is no other naturally occurring defense agent against cancer that has a stronger effect than paclitaxel, commonly known under the brand name of Taxol ® . The major drawback for the more widespread use of paclitaxel and its precious precursor, 10-deacetylbaccatin III (10-DAB III), is that they require large-scale extraction from different parts of yew trees ( Taxus species), cell cultures, taxane-producing endophytic fungi, and Corylus species. In our previous work, a novel online two-dimensional heart-cut liquid chromatography process using hydrophilic interaction/ reversed-phase chromatography was used to introduce a semi-preparative treatment for the separation of polar (10-deacetylbaccatin III) and non-polar (paclitaxel) taxanes from Taxus baccata L. In this work, a combination of the absorbent (Diaion ®  HP-20) and a silica based solid phase extraction is utilized as a new, efficient, and cost effective method for large-scale production of taxanes. This process avoids the technical problem of two-dimensional preparative liquid chromatography. The first stage of the process involves discarding co-extractive polar compounds including chlorophylls and pigments using a non-polar synthetic hydrophobic absorbent, Diaion ®  HP-20. Extract was then loaded on to a silica based hydrophilic interaction solid phase extraction (silica 40-60 micron). Taxanes was eluted using a mixture of water and methanol at the optimized ratio of 70:30. Finally, the fraction containing taxanes was applied to semi-preparative reversed phase HPLC. The results revealed that using this procedure, paclitaxel and 10-DAB III could be obtained at 8 and 3 times more, respectively than by the traditional method of extraction.

[High-performance liquid-liquid chromatography in beverage analysis].

PubMed

Bricout, J; Koziet, Y; de Carpentrie, B

1978-01-01

Liquid liquid chromatography was performed with columns packed with stationary phases chemically bonded to silica microparticules. These columns show a high efficiency and are used very easily. Flavouring compounds like aromatic aldehydes which have a low volatility were analyzed in brandy using a polar phase alkylnitrile. Sapid substances like amarogentin in Gentiana lutea or glyryrrhizin in Glycyrrhiza glabra were determined by reversed phase chromatography. Finally ionizable substances like synthetic dyes can be analyzed by paired ion chromatography witha non polar stationary phase.

Identification of clinical isolates of mycobacteria with gas-liquid chromatography: a 10-month follow-up study.

PubMed Central

Tisdall, P A; DeYoung, D R; Roberts, G D; Anhalt, J P

1982-01-01

Identification of routine mycobacterial isolates by gas-liquid chromatography profile analysis was performed on 335 strains received at the Mayo Clinic over a 10-month period. Comparison of identification by gas-liquid chromatography versus conventional biochemical profiles was made. The two methods agreed on the identification of 320 isolates, with gas-liquid chromatography profiling making eight errors and biochemical profiling making four errors. In three cases, discrepancies could not be resolved. PMID:6811612

On-line characterization of monoclonal antibody variants by liquid chromatography-mass spectrometry operating in a two-dimensional format.

PubMed

Alvarez, Melissa; Tremintin, Guillaume; Wang, Jennifer; Eng, Marian; Kao, Yung-Hsiang; Jeong, Justin; Ling, Victor T; Borisov, Oleg V

2011-12-01

Recombinant monoclonal antibodies (MAbs) have become one of the most rapidly growing classes of biotherapeutics in the treatment of human disease. MAbs are highly heterogeneous proteins, thereby requiring a battery of analytical technologies for their characterization. However, incompatibility between separation and subsequent detection is often encountered. Here we demonstrate the utility of a generic on-line liquid chromatography-mass spectrometry (LC-MS) method operated in a two-dimensional format toward the rapid characterization of MAb charge and size variants. Using a single chromatographic system capable of running two independent gradients, up to six fractions of interest from an ion exchange (IEC) or size exclusion (SEC) separation can be identified by trapping and desalting the fractions onto a series of reversed phase trap cartridges with subsequent on-line analysis by mass spectrometry. Analysis of poorly resolved and low-level peaks in the IEC or SEC profile was facilitated by preconcentrating fractions on the traps using multiple injections. An on-line disulfide reduction step was successfully incorporated into the workflow, allowing more detailed characterization of modified MAbs by providing chain-specific information. The system is fully automated, thereby enabling high-throughput analysis with minimal sample handling. This technology provides rapid data turnaround time, a much needed feature during product characterization and development of multiple biotherapeutic proteins. Copyright © 2011 Elsevier Inc. All rights reserved.

Investigation of interpolation techniques for the reconstruction of the first dimension of comprehensive two-dimensional liquid chromatography-diode array detector data.

PubMed

Allen, Robert C; Rutan, Sarah C

2011-10-31

Simulated and experimental data were used to measure the effectiveness of common interpolation techniques during chromatographic alignment of comprehensive two-dimensional liquid chromatography-diode array detector (LC×LC-DAD) data. Interpolation was used to generate a sufficient number of data points in the sampled first chromatographic dimension to allow for alignment of retention times from different injections. Five different interpolation methods, linear interpolation followed by cross correlation, piecewise cubic Hermite interpolating polynomial, cubic spline, Fourier zero-filling, and Gaussian fitting, were investigated. The fully aligned chromatograms, in both the first and second chromatographic dimensions, were analyzed by parallel factor analysis to determine the relative area for each peak in each injection. A calibration curve was generated for the simulated data set. The standard error of prediction and percent relative standard deviation were calculated for the simulated peak for each technique. The Gaussian fitting interpolation technique resulted in the lowest standard error of prediction and average relative standard deviation for the simulated data. However, upon applying the interpolation techniques to the experimental data, most of the interpolation methods were not found to produce statistically different relative peak areas from each other. While most of the techniques were not statistically different, the performance was improved relative to the PARAFAC results obtained when analyzing the unaligned data. Copyright © 2011 Elsevier B.V. All rights reserved.

Resolving the chemical heterogeneity of natural organic matter: new insights from comprehensive two-dimensional liquid chromatography.

PubMed

Duarte, Regina M B O; Barros, Ana C; Duarte, Armando C

2012-08-03

For the purpose of resolving the chemical heterogeneity of natural organic matter (NOM), comprehensive two-dimensional liquid chromatography (LC×LC) was employed for the first time to map the hydrophobicity versus molecular weight (MW) distribution of two well-known complex organic mixtures: Suwannee River Fulvic Acids (SR-FA) and Pony Lake Fulvic Acids (PL-FA). Two methods have been developed using either a conventional reversed-phase (RP) silica column or a mixed-mode hydrophilic interaction column operating under aqueous RP mode in the first dimension, and a size-exclusion column in the second dimension. The LC×LC fractions were screened on-line by UV at 254 nm, molecular fluorescence at excitation/emission wavelengths (λ(Exc)/λ(Em)) of 240/450 nm, and by evaporative light scattering. The MW distributions of these two NOM samples were further characterized by number (Mn) and weight (Mw) average MW, and by polydispersity (Mw/Mn). Findings suggest that the combination of two independent separation mechanisms is promising in extend the range of NOM separation. For the cases where NOM separation was accomplished, smaller Mw group fractions seem to be related to a more hydrophobic nature. Regardless of the detection method, the complete range of MW distribution provided by both comprehensive LC×LC methods was found to be lower than those reported in the literature. Copyright © 2012 Elsevier B.V. All rights reserved.

Structure and function of seed storage proteins in faba bean (Vicia faba L.).

PubMed

Liu, Yujiao; Wu, Xuexia; Hou, Wanwei; Li, Ping; Sha, Weichao; Tian, Yingying

2017-05-01

The protein subunit is the most important basic unit of protein, and its study can unravel the structure and function of seed storage proteins in faba bean. In this study, we identified six specific protein subunits in Faba bean (cv. Qinghai 13) combining liquid chromatography (LC), liquid chromatography-electronic spray ionization mass (LC-ESI-MS/MS) and bio-information technology. The results suggested a diversity of seed storage proteins in faba bean, and a total of 16 proteins (four GroEL molecular chaperones and 12 plant-specific proteins) were identified from 97-, 96-, 64-, 47-, 42-, and 38-kD-specific protein subunits in faba bean based on the peptide sequence. We also analyzed the composition and abundance of the amino acids, the physicochemical characteristics, secondary structure, three-dimensional structure, transmembrane domain, and possible subcellular localization of these identified proteins in faba bean seed, and finally predicted function and structure. The three-dimensional structures were generated based on homologous modeling, and the protein function was analyzed based on the annotation from the non-redundant protein database (NR database, NCBI) and function analysis of optimal modeling. The objective of this study was to identify the seed storage proteins in faba bean and confirm the structure and function of these proteins. Our results can be useful for the study of protein nutrition and achieve breeding goals for optimal protein quality in faba bean.

Increasing Flexibility in Two-Dimensional Liquid Chromatography by Pulsed Elution of the First Dimension: A Proof of Concept.

PubMed

Jakobsen, Simon S; Christensen, Jan H; Verdier, Sylvain; Mallet, Claude R; Nielsen, Nikoline J

2017-09-05

This work demonstrates the development of an online two-dimensional liquid chromatography (2D-LC) method where the first dimension column is eluted by a sequence of pulses of increasing eluotropic strength generated by the LC pumps (pulsed-elution 2D-LC). Between the pulses, the first dimension is kept in a no-elution state using low eluent strength. The eluate from the first dimension is actively modulated using trap columns and subsequently analyzed in the second dimension. We demonstrate that by tuning the length and eluotropic strength of the pulses, peaks with retention factors in water, k w , above 150 can be manipulated to elute in 3-4 pulses. The no-elution state can be kept for 1-10 min with only minor changes as to which and how many pulses the peaks elute in. Pulsed-elution 2D-LC combined with active modulation tackles three of the main challenges encountered in 2D-LC and specifically online comprehensive 2D-LC: undersampling, difficulties in refocusing, and lack of flexibility in the selection of column dimensions and flow rates because the two dimensions constrain each other. The pulsed-elution 2D-LC was applied for the analysis of a basic fraction of vacuum gas oil. Peak capacity was 4018 for a 540 min analysis and 4610 for a 1040 min analysis.

Doping of three-dimensional porous carbon nanotube-graphene-ionic liquid composite into polyaniline for the headspace solid-phase microextraction and gas chromatography determination of alcohols.

PubMed

Li, Lulu; Wu, Mian; Feng, Yingying; Zhao, Faqiong; Zeng, Baizhao

2016-12-15

In this work, ionic liquid (IL, i.e. 1-hydroxyethyl-3-methylimidazolium tetrafluoroborate), carboxyl multiwall carbon nanotubes (MWCNTs) and reduced graphene oxide (rGO) were used to prepare three-dimensional porous material (MWCNTs-rGO-IL) by one-step self-assembly, then it was co-electrodeposited with polyaniline (PANI) on stainless steel wires by cyclic voltammetry. The resulting coating (PANI-MWCNTs-rGO-IL) was characterized by using FT-IR and scanning electron microscopy etc, and it showed porous structure and had high thermal stability. Furthermore, it was found to be very suitable for the headspace solid-phase microextraction of alcohols (i.e. octanol, nonanol, geraniol, decanol, undecanol and dodecanol). By coupling with gas chromatography, wide linear ranges and low limits of detection (i.e. 2.2-28.3 ng L -1 ) were obtained for the alcohols. The coating also presented good repeatability and reproducibility; the relative standard deviations for intra-fiber and fiber-to-fiber were less than 5.6% (n = 5) and 7.0% (n = 5) respectively. In addition, the proposed method was successfully applied to the determination of alcohols in tea drinks, and the recoveries for standards added were 85.6-114%. Copyright © 2016 Elsevier B.V. All rights reserved.

The characterisation of novel secreted Ly-6 proteins from rat urine by the combined use of two-dimensional gel electrophoresis, microbore high performance liquid chromatography and expressed sequence tag data.

PubMed

Southan, Christopher; Cutler, Paul; Birrell, Helen; Connell, John; Fantom, Kenneth G M; Sims, Matthew; Shaikh, Narjis; Schneider, Klaus

2002-02-01

A proteomic study of rat urine was undertaken using two-dimensional gel electrophoresis, microbore high performance liquid chromatography, mass spectrometry and N-terminal sequencing. Five known urinary proteins were identified but two novel peptide fragments matched a large number of rat expressed sequence tags (ESTs) from a liver library. By combining protein chemical and nucleotide data, two 101-residue open reading frames with 90% amino acid identity were determined, rat urinary protein 1 (RUP-1) and RUP-2. The data established signal peptide removal and provided evidence for N-glycosylation. A third related sequence, rat spleen protein (RSP-1) was confirmed from EST searches. These three proteins have been submitted to SWISS-PROT as P81827, P81828 and Q9QXN2, respectively. A fourth novel homologue was found in porcine and bovine ESTs from embryo libraries. Alignment with known homologues showed conserved cysteine positions characteristic of a secreted subfamily of Ly-6 proteins. In two cases, antineoplastic urinary protein and caltrin, these homologues have unverified functional annotations. The RUP sequences showed high scoring matches to three unrelated rat mRNAs subsequently established to be chimeric. Two of these share extended sectional identity to RUP-1 but the third may represent another novel Ly-6 homologue. These chimeras have caused serious annotation errors in secondary databases.

Isolation and Purification of Water Soluble Proteins from Ginger Root (Zingiber officinale) by Two Dimensional Liquid Chromatography

PubMed Central

Sandovall, A.O.; Andrews, K.; Wahab, A.; Choudhary, M.I.; Ahmed, A.

2014-01-01

The RI-INBRE Centralized Core Facility was established in 2003 and participates annually in Undergraduate Summer Research Program. It provides students hands on research experience in key technologies in biomedical sciences. We present here the isolation and purification of water soluble proteins from ginger, a rhizome of the plant, Zingiber officinale. It is an important ingredient of species used in traditional South Asian cuisines. In Indian, Pakistani and Chinese folk medicine, ginger is used for gastro-intestinal disorders, nausea, vomiting, inflammatory diseases, muscle and joint pain. Limited studies have been reported on the bioactive proteins from ginger extract. The water soluble proteins were extracted from ginger root and successfully purified to homogeneity by using two-dimensional liquid chromatography (FPLC/RP-HPLC) approach. The ginger root was washed with distilled water; skin removed and then emulsified using an electric blender. Sample was stirred for four days at 4°C with and without protease inhibitor. Purification of a 42kDa protein was achieved by employing gel filtration, ion-exchange and reversed phase HPLC. The homogeneity of the protein was confirmed by SDS-PAGE gel electrophoresis and MALDI-TOF mass spectrometry. Future work will be conducted on the protein characterization using mass spectrometry and Edman protein sequencing. Supported by grant 5P20GM103430 from the National Institute of General Medical Sciences, NIH, USA.

Determination of alkylphenols by gas chromatography, elution liquid chromatography, and gel permeation chromatography

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

Wittmann, S.; Decsy, Z.; Regensperger, S.

1984-01-01

The separation and determination of groups of alkylphenols with C/sub 15/-C/sub 33/ isoalkane chains by gas chromatography, elution liquid chromatography, and gel permeation chromatography are described. Paraffinic hydrocarbons, monoalkylphenols, dialkylphenols, and bis(hydroxyphenyl)alkanes were identified in industrial alkylphenols by mass spectrometry. 7 references, 3 figures, 2 tables.

Status quo and future research challenges on organic food quality determination with focus on laboratory methods.

PubMed

Kahl, Johannes; Bodroza-Solarov, Marija; Busscher, Nicolaas; Hajslova, Jana; Kneifel, Wolfgang; Kokornaczyk, Maria Olga; van Ruth, Saskia; Schulzova, Vera; Stolz, Peter

2014-10-01

Organic food quality determination needs multi-dimensional evaluation tools. The main focus is on the authentication as an analytical verification of the certification process. New fingerprinting approaches such as ultra-performance liquid chromatography-mass spectrometry, gas chromatography-mass spectrometry, direct analysis in real time-high-resolution mass spectrometry as well as crystallization with and without the presence of additives seem to be promising methods in terms of time of analysis and detecting organic system-related parameters. For further methodological development, a system approach is recommended, which also takes into account food structure aspects. Furthermore, the authentication of processed organic samples needs more consciousness, hence most of organic food is complex and processed. © 2013 Society of Chemical Industry.

Simultaneous determination of niacin and pyridoxine at trace levels by using diode array high-performance liquid chromatography and liquid chromatography with quadrupole time-of-flight tandem mass spectrometry.

PubMed

Sel, Sabriye; Öztürk Er, Elif; Bakırdere, Sezgin

2017-12-01

A highly sensitive and simple diode-array high-performance liquid chromatography and liquid chromatography with quadrupole time-of-flight tandem mass spectrometry method was developed for the simultaneous determination of niacin and pyridoxine in pharmaceutical drugs, tap water, and wastewater samples. To determine the in vivo behavior of niacin and pyridoxine, analytes were subjected to simulated gastric conditions. The calibration plots of the diode-array high-performance liquid chromatography and liquid chromatography with quadrupole time-of-flight tandem mass spectrometry method showed good linearity over a wide concentration range with close to 1.0 correlation coefficients for both analytes. The limit of detection/limit of quantitation values for liquid chromatography quadrupole time-of-flight tandem mass spectrometry analysis were 1.98/6.59 and 1.3/4.4 μg/L for niacin and pyridoxine, respectively, while limit of detection/limit of quantitation values for niacin and pyridoxine in high-performance liquid chromatography analysis were 3.7/12.3 and 5.7/18.9 μg/L, respectively. Recovery studies were also performed to show the applicability of the developed methods, and percentage recovery values were found to be 90-105% in tap water and 94-97% in wastewater for both analytes. The method was also successfully applied for the qualitative and quantitative determination of niacin and pyridoxine in drug samples. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Analysis of host-cell proteins in biotherapeutic proteins by comprehensive online two-dimensional liquid chromatography/mass spectrometry

PubMed Central

Xenopoulos, Alex; Fadgen, Keith; Murphy, Jim; Skilton, St. John; Prentice, Holly; Stapels, Martha

2012-01-01

Assays for identification and quantification of host-cell proteins (HCPs) in biotherapeutic proteins over 5 orders of magnitude in concentration are presented. The HCP assays consist of two types: HCP identification using comprehensive online two-dimensional liquid chromatography coupled with high resolution mass spectrometry (2D-LC/MS), followed by high-throughput HCP quantification by liquid chromatography, multiple reaction monitoring (LC-MRM). The former is described as a “discovery” assay, the latter as a “monitoring” assay. Purified biotherapeutic proteins (e.g., monoclonal antibodies) were digested with trypsin after reduction and alkylation, and the digests were fractionated using reversed-phase (RP) chromatography at high pH (pH 10) by a step gradient in the first dimension, followed by a high-resolution separation at low pH (pH 2.5) in the second dimension. As peptides eluted from the second dimension, a quadrupole time-of-flight mass spectrometer was used to detect the peptides and their fragments simultaneously by alternating the collision cell energy between a low and an elevated energy (MSE methodology). The MSE data was used to identify and quantify the proteins in the mixture using a proven label-free quantification technique (“Hi3” method). The same data set was mined to subsequently develop target peptides and transitions for monitoring the concentration of selected HCPs on a triple quadrupole mass spectrometer in a high-throughput manner (20 min LC-MRM analysis). This analytical methodology was applied to the identification and quantification of low-abundance HCPs in six samples of PTG1, a recombinant chimeric anti-phosphotyrosine monoclonal antibody (mAb). Thirty three HCPs were identified in total from the PTG1 samples among which 21 HCP isoforms were selected for MRM monitoring. The absolute quantification of three selected HCPs was undertaken on two different LC-MRM platforms after spiking isotopically labeled peptides in the samples. Finally, the MRM quantitation results were compared with TOF-based quantification based on the Hi3 peptides, and the TOF and MRM data sets correlated reasonably well. The results show that the assays provide detailed valuable information to understand the relative contributions of purification schemes to the nature and concentrations of HCP impurities in biopharmaceutical samples, and the assays can be used as generic methods for HCP analysis in the biopharmaceutical industry. PMID:22327428

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...

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...

Liquid chromatography/mass spectrometry and liquid chromatography/nuclear magnetic resonance as complementary analytical techniques for unambiguous identification of polymethoxylated flavones in residues from molecular distillation of orange peel oils (Citrus sinensis).

PubMed

Weber, Berthold; Hartmann, Beate; Stöckigt, Detlef; Schreiber, Klaus; Roloff, Michael; Bertram, Heinz-Jürgen; Schmidt, Claus O

2006-01-25

Liquid chromatography/mass spectrometry and liquid chromatography/nuclear magnetic resonance techniques with ultraviolet/diode array detection were used as complementary analytical tools for the reliable identification of polymethoxylated flavones in residues from molecular distillation of cold-pressed peel oils of Citrus sinensis. After development of a liquid chromatographic separation procedure, the presence of several polymethoxy flavones such as sinensetin, nobiletin, tangeretin, quercetogetin, heptamethoxyflavone, and other derivatives was unambiguously confirmed. In addition, proceranone, an acetylated tetranortriterpenoid with limonoid structure, was identified for the first time in citrus.

Two-dimensional chromatographic analysis using three second-dimension columns for continuous comprehensive analysis of intact proteins.

PubMed

Zhu, Zaifang; Chen, Huang; Ren, Jiangtao; Lu, Juan J; Gu, Congying; Lynch, Kyle B; Wu, Si; Wang, Zhe; Cao, Chengxi; Liu, Shaorong

2018-03-01

We develop a new two-dimensional (2D) high performance liquid chromatography (HPLC) approach for intact protein analysis. Development of 2D HPLC has a bottleneck problem - limited second-dimension (second-D) separation speed. We solve this problem by incorporating multiple second-D columns to allow several second-D separations to be proceeded in parallel. To demonstrate the feasibility of using this approach for comprehensive protein analysis, we select ion-exchange chromatography as the first-dimension and reverse-phase chromatography as the second-D. We incorporate three second-D columns in an innovative way so that three reverse-phase separations can be performed simultaneously. We test this system for separating both standard proteins and E. coli lysates and achieve baseline resolutions for eleven standard proteins and obtain more than 500 peaks for E. coli lysates. This is an indication that the sample complexities are greatly reduced. We see less than 10 bands when each fraction of the second-D effluents are analyzed by sodium dodecyl sulfate - polyacrylamide gel electrophoresis (SDS-PAGE), compared to hundreds of SDS-PAGE bands as the original sample is analyzed. This approach could potentially be an excellent and general tool for protein analysis. Copyright © 2017 Elsevier B.V. All rights reserved.

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)

Impact of comprehensive two-dimensional gas chromatography with mass spectrometry on food analysis.

PubMed

Tranchida, Peter Q; Purcaro, Giorgia; Maimone, Mariarosa; Mondello, Luigi

2016-01-01

Comprehensive two-dimensional gas chromatography with mass spectrometry has been on the separation-science scene for about 15 years. This three-dimensional method has made a great positive impact on various fields of research, and among these that related to food analysis is certainly at the forefront. The present critical review is based on the use of comprehensive two-dimensional gas chromatography with mass spectrometry in the untargeted (general qualitative profiling and fingerprinting) and targeted analysis of food volatiles; attention is focused not only on its potential in such applications, but also on how recent advances in comprehensive two-dimensional gas chromatography with mass spectrometry will potentially be important for food analysis. Additionally, emphasis is devoted to the many instances in which straightforward gas chromatography with mass spectrometry is a sufficiently-powerful analytical tool. Finally, possible future scenarios in the comprehensive two-dimensional gas chromatography with mass spectrometry food analysis field are discussed. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Automated clean-up, separation and detection of polycyclic aromatic hydrocarbons in particulate matter extracts from urban dust and diesel standard reference materials using a 2D-LC/2D-GC system.

PubMed

Ahmed, Trifa M; Lim, Hwanmi; Bergvall, Christoffer; Westerholm, Roger

2013-10-01

A multidimensional, on-line coupled liquid chromatographic/gas chromatographic system was developed for the quantification of polycyclic aromatic hydrocarbons (PAHs). A two-dimensional liquid chromatographic system (2D-liquid chromatography (LC)), with three columns having different selectivities, was connected on-line to a two-dimensional gas chromatographic system (2D-gas chromatography (GC)). Samples were cleaned up by combining normal elution and column back-flush of the LC columns to selectively remove matrix constituents and isolate well-defined, PAH enriched fractions. Using this system, the sequential removal of polar, mono/diaromatic, olefinic and alkane compounds from crude extracts was achieved. The LC/GC coupling was performed using a fused silica transfer line into a programmable temperature vaporizer (PTV) GC injector. Using the PTV in the solvent vent mode, excess solvent was removed and the enriched PAH sample extract was injected into the GC. The 2D-GC setup consisted of two capillary columns with different stationary phase selectivities. Heart-cutting of selected PAH compounds in the first GC column (first dimension) and transfer of these to the second GC column (second dimension) increased the baseline resolutions of closely eluting PAHs. The on-line system was validated using the standard reference materials SRM 1649a (urban dust) and SRM 1975 (diesel particulate extract). The PAH concentrations measured were comparable to the certified values and the fully automated LC/GC system performed the clean-up, separation and detection of PAHs in 16 extracts in less than 24 h. The multidimensional, on-line 2D-LC/2D-GC system eliminated manual handling of the sample extracts and minimised the risk of sample loss and contamination, while increasing accuracy and precision.

A Study of the Liquid-Liquid Partitioning Process Using Reverse-Phase Liquid Chromatography: An Undergraduate Analytical Chemistry Experiment.

ERIC Educational Resources Information Center

Lochmuller, C. H.; And Others

1980-01-01

Presents an undergraduate analytical chemistry experiment that promotes an interpretation of the molecular aspects of solute partitioning, enhancing student understanding of separation science and liquid chromatography. (CS)

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…

Fully automated analysis of four tobacco-specific N-nitrosamines in mainstream cigarette smoke using two-dimensional online solid phase extraction combined with liquid chromatography-tandem mass spectrometry.

PubMed

Zhang, Jie; Bai, Ruoshi; Yi, Xiaoli; Yang, Zhendong; Liu, Xingyu; Zhou, Jun; Liang, Wei

2016-01-01

A fully automated method for the detection of four tobacco-specific nitrosamines (TSNAs) in mainstream cigarette smoke (MSS) has been developed. The new developed method is based on two-dimensional online solid-phase extraction-liquid chromatography-tandem mass spectrometry (SPE/LC-MS/MS). The two dimensional SPE was performed in the method utilizing two cartridges with different extraction mechanisms to cleanup disturbances of different polarity to minimize sample matrix effects on each analyte. Chromatographic separation was achieved using a UPLC C18 reversed phase analytical column. Under the optimum online SPE/LC-MS/MS conditions, N'-nitrosonornicotine (NNN), N'-nitrosoanatabine (NAT), N'-nitrosoanabasine (NAB), and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) were baseline separated with good peak shapes. This method appears to be the most sensitive method yet reported for determination of TSNAs in mainstream cigarette smoke. The limits of quantification for NNN, NNK, NAT and NAB reached the levels of 6.0, 1.0, 3.0 and 0.6 pg/cig, respectively, which were well below the lowest levels of TSNAs in MSS of current commercial cigarettes. The accuracy of the measurement of four TSNAs was from 92.8 to 107.3%. The relative standard deviations of intra-and inter-day analysis were less than 5.4% and 7.5%, respectively. The main advantages of the method developed are fairly high sensitivity, selectivity and accuracy of results, minimum sample pre-treatment, full automation, and high throughput. As a part of the validation procedure, the developed method was applied to evaluate TSNAs yields for 27 top-selling commercial cigarettes in China. Copyright © 2015 Elsevier B.V. All rights reserved.

Evaluation of comprehensive multidimensional separations using reversed-phase, reversed-phase liquid chromatography/mass spectrometry for shotgun proteomics.

PubMed

Nakamura, Tatsuji; Kuromitsu, Junro; Oda, Yoshiya

2008-03-01

Two-dimensional liquid-chromatographic (LC) separation followed by mass spectrometric (MS) analysis was examined for the identification of peptides in complex mixtures as an alternative to widely used two-dimensional gel electrophoresis followed by MS analysis for use in proteomics. The present method involves the off-line coupling of a narrow-bore, polymer-based, reversed-phase column using an acetonitrile gradient in an alkaline mobile phase in the first dimension with octadecylsilanized silica (ODS)-based nano-LC/MS in the second dimension. After the first separation, successive fractions were acidified and dried off-line, then loaded on the second dimension column. Both columns separate peptides according to hydrophobicity under different pH conditions, but more peptides were identified than with the conventional technique for shotgun proteomics, that is, the combination of a strong cation exchange column with an ODS column, and the system was robust because no salts were included in the mobile phases. The suitability of the method for proteomics measurements was evaluated.

DryLab® optimised two-dimensional high performance liquid chromatography for differentiation of ephedrine and pseudoephedrine based methamphetamine samples.

PubMed

Andrighetto, Luke M; Stevenson, Paul G; Pearson, James R; Henderson, Luke C; Conlan, Xavier A

2014-11-01

In-silico optimised two-dimensional high performance liquid chromatographic (2D-HPLC) separations of a model methamphetamine seizure sample are described, where an excellent match between simulated and real separations was observed. Targeted separation of model compounds was completed with significantly reduced method development time. This separation was completed in the heart-cutting mode of 2D-HPLC where C18 columns were used in both dimensions taking advantage of the selectivity difference of methanol and acetonitrile as the mobile phases. This method development protocol is most significant when optimising the separation of chemically similar chemical compounds as it eliminates potentially hours of trial and error injections to identify the optimised experimental conditions. After only four screening injections the gradient profile for both 2D-HPLC dimensions could be optimised via simulations, ensuring the baseline resolution of diastereomers (ephedrine and pseudoephedrine) in 9.7 min. Depending on which diastereomer is present the potential synthetic pathway can be categorized.

Recent advances in liquid-phase separations for clinical metabolomics.

PubMed

Kohler, Isabelle; Giera, Martin

2017-01-01

Over the last decades, several technological improvements have been achieved in liquid-based separation techniques, notably, with the advent of fully porous sub-2 μm particles and superficially porous sub-3 μm particles, the comeback of supercritical fluid chromatography, and the development of alternative chromatographic modes such as hydrophilic interaction chromatography. Combined with mass spectrometry, these techniques have demonstrated their added value, substantially increasing separation efficiency, selectivity, and speed of analysis. These benefits are essential in modern clinical metabolomics typically involving the study of large-scale sample cohorts and the analysis of thousands of metabolites showing extensive differences in physicochemical properties. This review presents a brief overview of the recent developments in liquid-phase separation sciences in the context of clinical metabolomics, focusing on increased throughput as well as metabolite coverage. Relevant metabolomics applications highlighting the benefits of ultra-high performance liquid chromatography, core-shell technology, high-temperature liquid chromatography, capillary electrophoresis, supercritical fluid chromatography, and hydrophilic interaction chromatography are discussed. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Preparation of well-controlled three-dimensional skeletal hybrid monoliths via thiol-epoxy click polymerization for highly efficient separation of small molecules in capillary liquid chromatography.

PubMed

Lin, Hui; Chen, Lianfang; Ou, Junjie; Liu, Zhongshan; Wang, Hongwei; Dong, Jing; Zou, Hanfa

2015-10-16

Two kinds of hybrid monoliths were first prepared via thiol-epoxy click polymerization using a multi-epoxy monomer, octaglycidyldimethylsilyl POSS (POSS-epoxy), and two multi-thiols, trimethylolpropanetris(3-mercaptopropionate) (TPTM) and pentaerythritoltetrakis(3-mercaptopropionate) (PTM), respectively, as the precursors. The resulting two hybrid monoliths (assigned as POSS-epoxy-TPTM and POSS-epoxy-PTM) not only possessed high thermal, mechanical and chemical stabilities, but also exhibited well-controlled 3D skeletal microstructure and high efficiency in capillary liquid chromatography (cLC) separation of small molecules. The highest column efficiency reached 182,700N/m (for butylbenzene) on the monolith POSS-epoxy-PTM at the velocity of 0.75mm/s. Furthermore, the hybrid monolith POSS-epoxy-PTM was successfully applied for cLC separations of various samples, not only standard compounds such as alkylbenzenes, PAHs, phenols and dipeptides, as well as intact proteins, but also complex samples of EPA 610 and BSA digest. Copyright © 2015 Elsevier B.V. All rights reserved.

Limitation of predictive 2-D liquid chromatography in reducing the database search space in shotgun proteomics: in silico studies.

PubMed

Moskovets, Eugene; Goloborodko, Anton A; Gorshkov, Alexander V; Gorshkov, Mikhail V

2012-07-01

A two-dimensional (2-D) liquid chromatography (LC) separation of complex peptide mixtures that combines a normal phase utilizing hydrophilic interactions and a reversed phase offers reportedly the highest level of 2-D LC orthogonality by providing an even spread of peptides across multiple LC fractions. Matching experimental peptide retention times to those predicted by empirical models describing chromatographic separation in each LC dimension leads to a significant reduction in a database search space. In this work, we calculated the retention times of tryptic peptides separated in the C18 reversed phase at different separation conditions (pH 2 and pH 10) and in TSK gel Amide-80 normal phase. We show that retention times calculated for different 2-D LC separation schemes utilizing these phases start to correlate once the mass range of peptides under analysis becomes progressively narrow. This effect is explained by high degree of correlation between retention coefficients in the considered phases. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Gas-liquid chromatographic and gas-liquid-mass spectometric determination of fenvalerate and permethrin residues in grasshoppers and duck tissue samples

USGS Publications Warehouse

Reichel, W.L.; Kolbe, E.J.; Stafford, C.J.

1981-01-01

A procedure is described for determining fenvalerate and permethrin residues in grasshoppers and duck tissues. Samples are Soxhlet-extracted with hexane and cleaned up by gel permeation chromatography with an in-line alumina column. Samples are analyzed by gas-liquid chromatography with electron capture detection, and confirmed by gas-liquid chromatography-mass spectrometry. The average recovery from fortified tissues was 97%.

Chemometrics comparison of gas chromatography with mass spectrometry and comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry Daphnia magna metabolic profiles exposed to salinity.

PubMed

Parastar, Hadi; Garreta-Lara, Elba; Campos, Bruno; Barata, Carlos; Lacorte, Silvia; Tauler, Roma

2018-06-01

The performances of gas chromatography with mass spectrometry and of comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry are examined through the comparison of Daphnia magna metabolic profiles. Gas chromatography with mass spectrometry and comprehensive two-dimensional gas chromatography with mass spectrometry were used to compare the concentration changes of metabolites under saline conditions. In this regard, a chemometric strategy based on wavelet compression and multivariate curve resolution-alternating least squares is used to compare the performances of gas chromatography with mass spectrometry and comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry for the untargeted metabolic profiling of Daphnia magna in control and salinity-exposed samples. Examination of the results confirmed the outperformance of comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry over gas chromatography with mass spectrometry for the detection of metabolites in D. magna samples. The peak areas of multivariate curve resolution-alternating least squares resolved elution profiles in every sample analyzed by comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry were arranged in a new data matrix that was then modeled by partial least squares discriminant analysis. The control and salt-exposed daphnids samples were discriminated and the most relevant metabolites were estimated using variable importance in projection and selectivity ratio values. Salinity de-regulated 18 metabolites from metabolic pathways involved in protein translation, transmembrane cell transport, carbon metabolism, secondary metabolism, glycolysis, and osmoregulation. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Advanced proteomic liquid chromatography

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

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.

Dissolution of NTO, DNAN, and Insensitive Munitions Formulations and Their Fates in Soils

DTIC Science & Technology

2014-09-01

3 2 Mass loss measured by high precision liquid chromatography (HPLC) versus measured mass loss by... Liquid Chromatography IM Insensitive Munitions IMX Insensitive Munitions eXplosive k First-Order Transformation Rate Constant kphoto First...Performance Liquid Chromatography U.S. EPA United States Environmental Protection Agency WMRD Weapons and Materials Research Directorate ERDC/CRREL

76 FR 61647 - Receipt of Several Pesticide Petitions Filed for Residues of Pesticide Chemicals in or on Various...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-10-05

... was required for gas chromatography with mass selective detection (GC/MSD) but not for liquid... detection (LOD = 0.01) and a gas liquid chromatography (GLC) method with a flame photometric detection (LOD... quantification by high performance liquid chromatography with tandem mass spectrometric detection (HPLC/MS/MS...

Examination of segmental average mass spectra from liquid chromatography-tandem mass spectrometric (LC-MS/MS) data enables screening of multiple types of protein modifications.

PubMed

Liu, Nai-Yu; Lee, Hsiao-Hui; Chang, Zee-Fen; Tsay, Yeou-Guang

2015-09-10

It has been observed that a modified peptide and its non-modified counterpart, when analyzed with reverse phase liquid chromatography, usually share a very similar elution property [1-3]. Inasmuch as this property is common to many different types of protein modifications, we propose an informatics-based approach, featuring the generation of segmental average mass spectra ((sa)MS), that is capable of locating different types of modified peptides in two-dimensional liquid chromatography-mass spectrometric (LC-MS) data collected for regular protease digests from proteins in gels or solutions. To enable the localization of these peptides in the LC-MS map, we have implemented a set of computer programs, or the (sa)MS package, that perform the needed functions, including generating a complete set of segmental average mass spectra, compiling the peptide inventory from the Sequest/TurboSequest results, searching modified peptide candidates and annotating a tandem mass spectrum for final verification. Using ROCK2 as an example, our programs were applied to identify multiple types of modified peptides, such as phosphorylated and hexosylated ones, which particularly include those peptides that could have been ignored due to their peculiar fragmentation patterns and consequent low search scores. Hence, we demonstrate that, when complemented with peptide search algorithms, our approach and the entailed computer programs can add the sequence information needed for bolstering the confidence of data interpretation by the present analytical platforms and facilitate the mining of protein modification information out of complicated LC-MS/MS data. Copyright © 2015 Elsevier B.V. All rights reserved.

Multiple heart-cutting and comprehensive two-dimensional liquid chromatography hyphenated to mass spectrometry for the characterization of the antibody-drug conjugate ado-trastuzumab emtansine.

PubMed

Sandra, Koen; Vanhoenacker, Gerd; Vandenheede, Isabel; Steenbeke, Mieke; Joseph, Maureen; Sandra, Pat

2016-10-01

Antibody-drug conjugates might be the magic bullets referred to by Paul Ehrlich over 100 years ago. Together with a huge therapeutic potential, these molecules come with a structural complexity that drives state-of-the-art chromatography and mass spectrometry to its limits. The use of multiple heart-cutting (mLC-LC) and comprehensive (LC×LC) multidimensional LC in combination with high resolution mass spectrometry for the characterization of the lysine conjugated antibody-drug conjugate ado-trastuzumab emtansine, commercialized as Kadcyla, is presented. By combining protein and peptide measurements, attributes such as drug loading, drug distribution and drug conjugation sites can be assessed in an elegant manner. Copyright © 2016 Elsevier B.V. All rights reserved.

Ionic liquid stationary phases for gas chromatography.

PubMed

Poole, Colin F; Poole, Salwa K

2011-04-01

This article provides a summary of the development of ionic liquids as stationary phases for gas chromatography beginning with early work on packed columns that established details of the retention mechanism and established working methods to characterize selectivity differences compared with molecular stationary phases through the modern development of multi-centered cation and cross-linked ionic liquids for high-temperature applications in capillary gas chromatography. Since there are many reviews on ionic liquids dealing with all aspects of their chemical and physical properties, the emphasis in this article is placed on the role of gas chromatography played in the design of ionic liquids of low melting point, high thermal stability, high viscosity, and variable selectivity for separations. Ionic liquids provide unprecedented opportunities for extending the selectivity range and temperature-operating range of columns for gas chromatography, an area of separation science that has otherwise been almost stagnant for over a decade. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Applications of hydrophilic interaction chromatography to amino acids, peptides, and proteins.

PubMed

Periat, Aurélie; Krull, Ira S; Guillarme, Davy

2015-02-01

This review summarizes the recent advances in the analysis of amino acids, peptides, and proteins using hydrophilic interaction chromatography. Various reports demonstrate the successful analysis of amino acids under such conditions. However, a baseline resolution of the 20 natural amino acids has not yet been published and for this reason, there is often a need to use mass spectrometry for detection to further improve selectivity. Hydrophilic interaction chromatography is also recognized as a powerful technique for peptide analysis, and there are a lot of papers showing its applicability for proteomic applications (peptide mapping). It is expected that its use for peptide mapping will continue to grow in the future, particularly because this analytical strategy can be combined with reversed-phase liquid chromatography, in a two-dimensional setup, to reach very high resolving power. Finally, the interest in hydrophilic interaction chromatography for intact proteins analysis is less evident due to possible solubility issues and a lack of suitable hydrophilic interaction chromatography stationary phases. To date, it has been successfully employed only for the characterization of membrane proteins, histones, and the separation of glycosylated isoforms of an intact glycoprotein. From our point of view, the number of hydrophilic interaction chromatography columns compatible with intact proteins (higher upper temperature limit, large pore size, etc.) is still too limited. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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.

Contaminant screening of wastewater with HPLC-IM-qTOF-MS and LC+LC-IM-qTOF-MS using a CCS database.

PubMed

Stephan, Susanne; Hippler, Joerg; Köhler, Timo; Deeb, Ahmad A; Schmidt, Torsten C; Schmitz, Oliver J

2016-09-01

Non-target analysis has become an important tool in the field of water analysis since a broad variety of pollutants from different sources are released to the water cycle. For identification of compounds in such complex samples, liquid chromatography coupled to high resolution mass spectrometry are often used. The introduction of ion mobility spectrometry provides an additional separation dimension and allows determining collision cross sections (CCS) of the analytes as a further physicochemical constant supporting the identification. A CCS database with more than 500 standard substances including drug-like compounds and pesticides was used for CCS data base search in this work. A non-target analysis of a wastewater sample was initially performed with high performance liquid chromatography (HPLC) coupled to an ion mobility-quadrupole-time of flight mass spectrometer (IM-qTOF-MS). A database search including exact mass (±5 ppm) and CCS (±1 %) delivered 22 different compounds. Furthermore, the same sample was analyzed with a two-dimensional LC method, called LC+LC, developed in our group for the coupling to IM-qTOF-MS. This four dimensional separation platform revealed 53 different compounds, identified over exact mass and CCS, in the examined wastewater sample. It is demonstrated that the CCS database can also help to distinguish between isobaric structures exemplified for cyclophosphamide and ifosfamide. Graphical Abstract Scheme of sample analysis and database screening.

Increased Depth and Breadth of Plasma Protein Quantitation via Two-Dimensional Liquid Chromatography/Multiple Reaction Monitoring-Mass Spectrometry with Labeled Peptide Standards.

PubMed

Percy, Andrew J; Yang, Juncong; Chambers, Andrew G; Borchers, Christoph H

2016-01-01

Absolute quantitative strategies are emerging as a powerful and preferable means of deriving concentrations in biological samples for systems biology applications. Method development is driven by the need to establish new-and validate current-protein biomarkers of high-to-low abundance for clinical utility. In this chapter, we describe a methodology involving two-dimensional (2D) reversed-phase liquid chromatography (RPLC), operated under alkaline and acidic pH conditions, combined with multiple reaction monitoring (MRM)-mass spectrometry (MS) (also called selected reaction monitoring (SRM)-MS) and a complex mixture of stable isotope-labeled standard (SIS) peptides, to quantify a broad and diverse panel of 253 proteins in human blood plasma. The quantitation range spans 8 orders of magnitude-from 15 mg/mL (for vitamin D-binding protein) to 450 pg/mL (for protein S100-B)-and includes 31 low-abundance proteins (defined as being <10 ng/mL) of potential disease relevance. The method is designed to assess candidates at the discovery and/or verification phases of the biomarker pipeline and can be adapted to examine smaller or alternate panels of proteins for higher sample throughput. Also detailed here is the application of our recently developed software tool-Qualis-SIS-for protein quantitation (via regression analysis of standard curves) and quality assessment of the resulting data. Overall, this chapter provides the blueprint for the replication of this quantitative proteomic method by proteomic scientists of all skill levels.

Comparison of fractionation strategies for offline two-dimensional liquid chromatography tandem mass spectrometry analysis of proteins from mouse adipose tissue.

PubMed

Sajic, Tatjana; Varesio, Emmanuel; Szanto, Ildiko; Hopfgartner, Gérard

2015-09-01

In the frame of protein identification from mouse adipose tissue, two strategies were compared for the offline elution of peptides from a strong cation exchange (SCX) column in two-dimensional liquid chromatography tandem mass spectrometry (2D-LC-MS/MS) analyses. First, the salt gradient (using K(+) as displacing agent) was evaluated from 25 to 500mM KCl. Then, a less investigated elution mode using a pH gradient (using citric acid and ammonium hydroxide) was carried out from pH 2.5 to 9.0. Equal amounts of peptide digest derived from mouse adipose tissue were loaded onto the SCX column and fractionated according to the two approaches. A total of 15 fractions were collected in two independent experiments for each SCX elution strategy. Then, each fraction was analyzed on a nanoLC-MS/MS platform equipped with a column-switching unit for desalting and enrichment. No substantial differences in peptide quality characteristics (molecular weight, isoelectric point, or GRAVY [grand average of hydropathicity] index distributions) were observed between the two datasets. The pH gradient approach was found to be superior, with 27.5% more unique peptide identifications and 10% more distinct protein identifications compared with the salt-based elution method. In conclusion, our data imply that the pH gradient SCX fractionation is more desirable for proteomics analysis of entire adipose tissue. Copyright © 2015 Elsevier Inc. All rights reserved.

Lipidomic analysis of plasma in patients with lacunar infarction using normal-phase/reversed-phase two-dimensional liquid chromatography-quadrupole time-of-flight mass spectrometry.

PubMed

Yang, Li; Lv, Pu; Ai, Wanpeng; Li, Linnan; Shen, Sensen; Nie, Honggang; Shan, Yabing; Bai, Yu; Huang, Yining; Liu, Huwei

2017-05-01

Stroke is a major cause of mortality and long-term disability worldwide. The study of biomarkers and pathogenesis is vital for early diagnosis and treatment of stroke. In the present study, a continuous-flow normal-phase/reversed-phase two-dimensional liquid chromatography-quadrupole time-of-flight mass spectrometry (NP/RP 2D LC-QToF/MS) method was employed to measure lipid species in human plasma, including healthy controls and lacunar infarction (LI) patients. As a result, 13 lipid species were demonstrated with significant difference between the two groups, and a "plasma biomarker model" including glucosylceramide (38:2), phosphatidylethanolamine (35:2), free fatty acid (16:1), and triacylglycerol (56:5) was finally established. This model was evaluated as an effective tool in that area under the receiver operating characteristic curve reached 1.000 in the discovery set and 0.947 in the validation set for diagnosing LI patients from healthy controls. Besides, the sensitivity and specificity of disease diagnosis in validation set were 93.3% and 96.6% at the best cutoff value, respectively. This study demonstrates the promising potential of NP/RP 2D LC-QToF/MS-based lipidomics approach in finding bio-markers for disease diagnosis and providing special insights into the metabolism of stroke induced by small vessel disease. Graphical abstract Flow-chart of the plasma biomarker model establishment through biomarker screening and validation.

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...

Coupling Front-End Separations, Ion Mobility Spectrometry, and Mass Spectrometry For Enhanced Multidimensional Biological and Environmental Analyses

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

Zheng, Xueyun; Wojcik, Roza; Zhang, Xing

Ion mobility spectrometry (IMS) is a widely used analytical technique for rapid molecular separations in the gas phase. IMS alone is useful, but its coupling with mass spectrometry (MS) and front-end separations has been extremely beneficial for increasing measurement sensitivity, peak capacity of complex mixtures, and the scope of molecular information in biological and environmental sample analyses. Multiple studies in disease screening and environmental evaluations have even shown these IMS-based multidimensional separations extract information not possible with each technique individually. This review highlights 3-dimensional separations using IMS-MS in conjunction with a range of front-end techniques, such as gas chromatography (GC),more » supercritical fluid chromatography (SFC), liquid chromatography (LC), solid phase extractions (SPE), capillary electrophoresis (CE), field asymmetric ion mobility spectrometry (FAIMS), and microfluidic devices. The origination, current state, various applications, and future capabilities for these multidimensional approaches are described to provide insight into the utility and potential of each technique.« less

Comprehensive two-dimensional chromatography with coupling of reversed phase high performance liquid chromatography and supercritical fluid chromatography.

PubMed

Stevenson, Paul G; Tarafder, Abhijit; Guiochon, Georges

2012-01-13

A 2D comprehensive chromatographic separation of blackberry sage fragrant oil was performed by using HPLC in the first dimension and SFC in the second. A C(18)-bonded silica column eluted with an ACN gradient was used in the HPLC dimension and an amino-bonded silica column eluted with ACN as a modifier in the SFC dimension. This 2D separation was completed in the off-line mode, the fractions from the HPLC column being collected and injected in the SFC column. The retention factors on the two columns have a -0.757 correlation coefficient. The method provides a practical peak capacity of 2400 in 280 min. The first eluted peaks in HPLC are the last ones eluted in SFC and vice versa. The results demonstrate that the coupling of an HPLC and an SFC separation have a great potential for 2D chromatographic separations. Copyright © 2011 Elsevier B.V. All rights reserved.

Coupling Front-End Separations, Ion Mobility Spectrometry, and Mass Spectrometry For Enhanced Multidimensional Biological and Environmental Analyses

PubMed Central

Zheng, Xueyun; Wojcik, Roza; Zhang, Xing; Ibrahim, Yehia M.; Burnum-Johnson, Kristin E.; Orton, Daniel J.; Monroe, Matthew E.; Moore, Ronald J.; Smith, Richard D.; Baker, Erin S.

2017-01-01

Ion mobility spectrometry (IMS) is a widely used analytical technique for rapid molecular separations in the gas phase. Though IMS alone is useful, its coupling with mass spectrometry (MS) and front-end separations is extremely beneficial for increasing measurement sensitivity, peak capacity of complex mixtures, and the scope of molecular information available from biological and environmental sample analyses. In fact, multiple disease screening and environmental evaluations have illustrated that the IMS-based multidimensional separations extract information that cannot be acquired with each technique individually. This review highlights three-dimensional separations using IMS-MS in conjunction with a range of front-end techniques, such as gas chromatography, supercritical fluid chromatography, liquid chromatography, solid-phase extractions, capillary electrophoresis, field asymmetric ion mobility spectrometry, and microfluidic devices. The origination, current state, various applications, and future capabilities of these multidimensional approaches are described in detail to provide insight into their uses and benefits. PMID:28301728

Advanced proteomic liquid chromatography

PubMed Central

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

2012-01-01

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. PMID:22840822

Analysis of new psychoactive substances in human urine by ultra-high performance supercritical fluid and liquid chromatography: Validation and comparison.

PubMed

Borovcová, Lucie; Pauk, Volodymyr; Lemr, Karel

2018-05-01

New psychoactive substances represent serious social and health problem as tens of new compounds are detected in Europe annually. They often show structural proximity or even isomerism, which complicates their analysis. Two methods based on ultra high performance supercritical fluid chromatography and ultra high performance liquid chromatography with mass spectrometric detection were validated and compared. A simple dilute-filter-and-shoot protocol utilizing propan-2-ol or methanol for supercritical fluid or liquid chromatography, respectively, was proposed to detect and quantify 15 cathinones and phenethylamines in human urine. Both methods offered fast separation (<3 min) and short total analysis time. Precision was well <15% with a few exceptions in liquid chromatography. Limits of detection in urine ranged from 0.01 to 2.3 ng/mL, except for cathinone (5 ng/mL) in supercritical fluid chromatography. Nevertheless, this technique distinguished all analytes including four pairs of isomers, while liquid chromatography was unable to resolve fluoromethcathinone regioisomers. Concerning matrix effects and recoveries, supercritical fluid chromatography produced more uniform results for different compounds and at different concentration levels. This work demonstrates the performance and reliability of supercritical fluid chromatography and corroborates its applicability as an alternative tool for analysis of new psychoactive substances in biological matrixes. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Determination of phytate in high molecular weight, charged organic matrices by two-dimensional size exclusion-ion chromatography

USDA-ARS?s Scientific Manuscript database

A two-dimensional chromatography method for analyzing anionic targets (specifically phytate) in complex matrices is described. Prior to quantification by anion exchange chromatography, the sample matrix was prepared by size exclusion chromatography, which removed the majority of matrix complexities....

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. Copyright © 2015 Elsevier B.V. All rights reserved.

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

Method for enhanced accuracy in predicting peptides using liquid separations or chromatography

DOEpatents

Kangas, Lars J.; Auberry, Kenneth J.; Anderson, Gordon A.; Smith, Richard D.

2006-11-14

A method for predicting the elution time of a peptide in chromatographic and electrophoretic separations by first providing a data set of known elution times of known peptides, then creating a plurality of vectors, each vector having a plurality of dimensions, and each dimension representing the elution time of amino acids present in each of these known peptides from the data set. The elution time of any protein is then be predicted by first creating a vector by assigning dimensional values for the elution time of amino acids of at least one hypothetical peptide and then calculating a predicted elution time for the vector by performing a multivariate regression of the dimensional values of the hypothetical peptide using the dimensional values of the known peptides. Preferably, the multivariate regression is accomplished by the use of an artificial neural network and the elution times are first normalized using a transfer function.

Using comprehensive two-dimensional gas chromatography to explore the geochemistry of the Santa Barbara oil seeps

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

Reddy, Christopher; Nelson, Robert

The development of comprehensive two-dimensional gas chromatography (GC x GC) has expanded the analytical window for studying complex mixtures like oil. Compared to traditional gas chromatography, this technology separates and resolves at least an order of magnitude more compounds, has a much larger signal to noise ratio, and sorts compounds based on their chemical class; hence, providing highly refined inventories of petroleum hydrocarbons in geochemical samples that was previously unattainable. In addition to the increased resolution afforded by GC x GC, the resulting chromatograms have been used to estimate the liquid vapor pressures, aqueous solubilities, octanol-water partition coefficients, and vaporizationmore » enthalpies of petroleum hydrocarbons. With these relationships, powerful and incisive analyses of phase-transfer processes affecting petroleum hydrocarbon mixtures in the environment are available. For example, GC x GC retention data has been used to quantitatively deconvolve the effects of phase transfer processes such as water washing and evaporation. In short, the positive attributes of GC x GC-analysis have led to a methodology that has revolutionized the analysis of petroleum hydrocarbons. Overall, this research has opened numerous fields of study on the biogeochemical "genetics" (referred to as petroleomics) of petroleum samples in both subsurface and surface environments. Furthermore, these new findings have already been applied to the behavior of oil at other seeps as well, for petroleum exploration and oil spill studies.« less

[Ascending one-dimensional thin layer chromatography in specific blood diagnosis (author's transl)].

PubMed

Bernardelli, B; Masotti, G

1976-01-01

A brief review of the literature on chromatography in forensic haematology is followed by a report of the results obtained by using ascending one-dimensional thin layer chromatography in specific blood diagnosis.

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. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

Screening, separation, and evaluation of xanthine oxidase inhibitors from Paeonia lactiflora using chromatography combined with a multi-mode microplate reader.

PubMed

Wang, Jing; Shi, Dongfang; Zheng, Meizhu; Ma, Bing; Cui, Jing; Liu, Chunming; Liu, Chengyu

2017-11-01

Natural products have become one of the most important resources for discovering novel xanthine oxidase inhibitors, which are commonly employed in the treatment of hyperuricemia and gout. However, to date, few reports exist regarding the use of monoterpene glycosides as xanthine oxidase inhibitors. Thus, we herein report the use of ultrafiltration coupled with liquid chromatography in the screening of monoterpene glycoside xanthine oxidase inhibitors from the extract of Paeonia lactiflora (P. lactiflora), and both high-performance counter-current chromatography and medium-pressure liquid chromatography were employed to separate the main constituents. Furthermore, the xanthine oxidase inhibitory activities and the mechanisms of inhibition of the isolated compounds were evaluated using a multi-mode microplate reader by Molecular Devices. As a result, three monoterpene glycosides were separated by combined high-performance counter-current chromatography and medium-pressure liquid chromatography in purities of 90.4, 98.0, and 86.3%, as determined by liquid chromatography. These three compounds were identified as albiflorin, paeoniflorin, and 1-O-β-ᴅ-glucopyranosyl-8-O-benzoylpaeonisuffrone by electrospray ionization tandem mass spectrometry, and albiflorin and paeoniflorin were screened as potential xanthine oxidase inhibitors by ultrafiltration with liquid chromatography. The evaluation results of xanthine oxidase inhibitory activity corresponded with the screening results, as only albiflorin and paeoniflorin exhibited xanthine oxidase inhibitory activity. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

On-line coupling of counter-current chromatography and macroporous resin chromatography for continuous isolation of arctiin from the fruit of Arctium lappa L.

PubMed

Guo, Mengzhe; Liang, Junling; Wu, Shihua

2010-08-13

In this work, we have developed a novel hybrid two-dimensional counter-current chromatography and liquid chromatography (2D CCC x LC) system for the continuous purification of arctiin from crude extract of Arctium lappa. The first dimensional CCC column has been designed to fractionalize crude complex extract into pure arctiin effluent using a one-component organic/salt-containing system, and the second dimensional LC column has been packed with macroporous resin for on-line adsorption, desalination and desorption of arctiin which was effluent purified from the first CCC dimension. Thus, the crude arctiin mixture has been purified efficiently and conveniently by on-line CCC x LC in spite of the use of a salt-containing solvent system in CCC separation. As a result, high purity (more than 97%) of arctiin has been isolated by repeated injections both using the ethyl acetate-8% sodium chloride aqueous solution and butanol-1% sodium chloride aqueous solution. By contrast with the traditional CCC processes using multi-component organic/aqueous solvent systems, the present on-line CCC x LC process only used a one-component organic solvent and thus the solvent is easier to recover and regenerate. All of used solvents such as ethyl acetate, n-butanol and NaCl aqueous solution are low toxicity and environment-friendly. Moreover, the lower phase of salt-containing aqueous solution used as mobile phase, only contained minor organic solvent, which will save much organic solvent in continuous separation. In summary, our results indicated that the on-line hybrid 2D CCC x LC system using one-component organic/salt-containing aqueous solution is very promising and powerful tool for high-throughput purification of arctiin from fruits of A. lappa. 2010 Elsevier B.V. All rights reserved.

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 C 18 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. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Spill-Detector-and-Shutoff Device

NASA Technical Reports Server (NTRS)

Jarvis, M. R.; Fulton, D. S.

1985-01-01

Overflow in liquid chromatography systems rapidly detected and stopped. Spill-detector-and-shutoff device incorporated into liquid-chromatography system. When liquid from output nozzle spills on liquid sensor, device automatically shuts off pump and releases solenoid to pinch off flow in tube. Device uses common type of alarm circuit reset manually before normal operation resumes.

Two-dimensional liquid chromatography (LC) of phenolic compounds from the shoots of Rubus idaeus 'Glen Ample' cultivar variety.

PubMed

Kula, Marta; Głód, Daniel; Krauze-Baranowska, Mirosława

2016-03-20

In this study the application of two-dimensional LC (2D LC) for qualitative analysis of polyphenols and simple phenols in the shoots of Rubus idaeus 'Glen Ample' variety is presented. In the preliminary analysis, the methanol extract of the shoots was analyzed by one-dimensional LC. One-dimensional LC separation profiles of phenolics from R. idaeus 'Glen Ample' shoots were dependent on column type, mobile phase composition and gradient program used. Two-dimensional LC system was built from connecting an octadecyl C-18 silica column in the first dimension and pentafluorophenyl column in the second dimension, coupled with DAD and MS (ESI, APCI, DUIS ionization) detectors. A total of 34 phenolic compounds belonging to the groups of phenolic acids, ellagitannins, flavan-3-ols, flavonols and ellagic acid conjugates were identified in the shoots of R. idaeus 'Glen Ample'. The established 2D LC method offers an effective tool for analysis of phenolics present in Rubus species. Copyright © 2015 Elsevier B.V. All rights reserved.

Progressing the analysis of Improvised Explosive Devices: Comparative study for trace detection of explosive residues in handprints by Raman spectroscopy and liquid chromatography.

PubMed

Zapata, Félix; de la Ossa, Mª Ángeles Fernández; Gilchrist, Elizabeth; Barron, Leon; García-Ruiz, Carmen

2016-12-01

Concerning the dreadful global threat of terrorist attacks, the detection of explosive residues in biological traces and marks is a current need in both forensics and homeland security. This study examines the potential of Raman microscopy in comparison to liquid chromatography (ion chromatography (IC) and reversed-phase high performance liquid chromatography (RP-HPLC)) to detect, identify and quantify residues in human handmarks of explosives and energetic salts commonly used to manufacture Improvised Explosive Devices (IEDs) including dynamite, ammonium nitrate, single- and double-smokeless gunpowders and black powder. Dynamite, ammonium nitrate and black powder were detected through the identification of the energetic salts by Raman spectroscopy, their respective anions by IC, and organic components by RP-HPLC. Smokeless gunpowders were not detected, either by Raman spectroscopy or the two liquid chromatography techniques. Several aspects of handprint collection, sample treatment and a critical comparison of the identification of compounds by both techniques are discussed. Raman microscopy and liquid chromatography were shown to be complementary to one another offering more comprehensive information for trace explosives analysis. Copyright © 2016 Elsevier B.V. All rights reserved.

[Development of methods for determining acrylamide in food products by gas-liquid chromatography].

PubMed

Bessonov, V V; Malinkin, A D; Perederiaev, O I; Bogachuk, M N; Volkovich, S V; Medvedev, Iu V

2011-01-01

The method of determination of acrylamide in various food (milk powder, potato chips, instant coffee) by gas-liquid chromatography after pre-bromination was developed. Studies have shown the possibility of using bromination of acrylamide to give it the necessary properties for better extraction, purification and detection. Also revealed the possibility of qualitative and quantitative determine a acrylamide in food by gas-liquid chromatography with detection by electron capture detector.

Quantitative analysis of psilocybin and psilocin in psilocybe baeocystis (Singer and Smith) by high-performance liquid chromatography and by thin-layer chromatography.

PubMed

Beug, M W; Bigwood, J

1981-03-27

Rapid quantification of psilocybin and psilocin in extracts of wild mushrooms is accomplished by reversed-phase high-performance liquid chromatography with paired-ion reagents. Nine solvent systems and three solid supports are evaluated for their efficiency in separating psilocybin, psilocin and other components of crude mushroom extracts by thin-layer chromatography.

Incorporation of ionic liquid into porous polymer monoliths to enhance the separation of small molecules in reversed-phase high-performance liquid chromatography.

PubMed

Wang, Jiafei; Bai, Ligai; Wei, Zhen; Qin, Junxiao; Ma, Yamin; Liu, Haiyan

2015-06-01

An ionic liquid was incorporated into the porous polymer monoliths to afford stationary phases with enhanced chromatographic performance for small molecules in reversed-phase high-performance liquid chromatography. The effect of the ionic liquid in the polymerization mixture on the performance of the monoliths was studied in detail. While monoliths without ionic liquid exhibited poor resolution and low efficiency, the addition of ionic liquid to the polymerization mixture provides highly increased resolution and high efficiency. The chromatographic performances of the monoliths were demonstrated by the separations of various small molecules including aromatic hydrocarbons, isomers, and homologues using a binary polar mobile phase. The present column efficiency reached 27 000 plates/m, which showed that the ionic liquid monoliths are alternative stationary phases in the separation of small molecules by high-performance liquid chromatography. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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...

Ultra-high-pressure liquid chromatography-tandem mass spectrometry method for the determination of alkylphenols in soil.

PubMed

Wang, Jing; Pan, Hefang; Liu, Zhengzheng; Ge, Fei

2009-03-20

A novel method has been developed for the determination of alkylphenols in soil by ultra-high-pressure liquid chromatography employing small particle sizes, combined with tandem mass spectrometry. Soil samples were extracted with pressurized liquid extraction (PLE) and then cleaned with solid-phase extraction (SPE). The extracts were separated on C18 column (1.7 microm, 50 mm x 2.1mm) with a gradient elution and a mobile phase consisting of water and acetonitrile, and then detected by an electrospray ionization tandem mass spectrometry in negative ion mode with multiple reaction monitoring (MRM). Compared with traditional liquid chromatography, it took ultra-high-pressure liquid chromatography much less time to analyze alkylphenols. Additionally, the ultra-high-pressure liquid chromatography/tandem mass spectrometry method produces satisfactory reliability, sensitivity, and accuracy. The average recoveries of the three target analytes were 74.0-103.4%, with the RSD<15%. The calibration curves for alkylphenols were linear within the range of 0.01-0.4 microg/ml, with the correlation coefficients greater than 0.99. When 10 g soil sample was used for analysis, the limits of quantification (LOQs) of the three alkylphenols were all 1.0 microg/kg.

APPLICATION OF A SPRAY DEPOSITION METHOD FOR REVERSED PHASE LIQUID CHROMATOGRAPHY-MASS SPECTROMETRY

EPA Science Inventory

Four coal gasification wastewater samples were analyzed for nonvolatile and polar organics by liquid chromatography-mass spectrometry (LC/MS). Samples were separated on a reverse phase liquid chromatographic column using an aqueous solvent as the eluant. A special spray depositio...

Liquid Chromatography at Critical Conditions: Balancing size exclusion and adsorption in nanopores

NASA Astrophysics Data System (ADS)

Abdulahad, Asem; Amos, Jeffrey; Ryu, Chang

2009-03-01

Liquid chromatography at critical condition (LCCC) is a measure to identify thermodynamic conditions, in which polymers elute independently of molar mass during high performance liquid chromatography. Under these critical conditions the entropic exclusions that dominate size exclusion chromatography (SEC) and the enthalpic adsorption that governs adsorption-based interaction chromatography (IC) are said to negate one another resulting in simultaneous elution of the polymer of different molecular weights. Using multiple C18-bonded silica columns with different average nanopore sizes (from 5 nm to 30 nm), we will study the LCCC conditions of PS in methylene chloride/acetonitrile solvent mixture at different temperature. In addition, we will show that the separation of polystyrene can be fine tuned using a refined temperature gradient interaction chromatography (TGIC) that employs multiple columns of varying pore size in sequence.

Counter-current motion in counter-current chromatography.

PubMed

Ito, Yoichiro

2014-12-12

After the CCC2012 meeting, I have received an e-mail regarding the terminology of "Countercurrent Chromatography". It stated that the term "Countercurrent" is a misnomer, because its stationary phase is motionless in the column and that the method should be renamed as liquid-liquid separations or centrifugal separations. However, it was found that these names are already used for various other techniques as found via Google search. The term "Countercurrent Chromatography" was originally made after two preparative methods of Countercurrent distribution and liquid Chromatography, both having no countercurrent motion in the column. However, it is surprising to find that this F1 hybrid method "Countercurrent Chromatography" can clearly exhibit countercurrent motion within the separation column in both hydrodynamic and hydrostatic equilibrium systems. This justifies that "Countercurrent Chromatography" is a proper term for this chromatographic method. Published by Elsevier B.V.

3D-liquid chromatography as a complex mixture characterization tool for knowledge-based downstream process development.

PubMed

Hanke, Alexander T; Tsintavi, Eleni; Ramirez Vazquez, Maria Del Pilar; van der Wielen, Luuk A M; Verhaert, Peter D E M; Eppink, Michel H M; van de Sandt, Emile J A X; Ottens, Marcel

2016-09-01

Knowledge-based development of chromatographic separation processes requires efficient techniques to determine the physicochemical properties of the product and the impurities to be removed. These characterization techniques are usually divided into approaches that determine molecular properties, such as charge, hydrophobicity and size, or molecular interactions with auxiliary materials, commonly in the form of adsorption isotherms. In this study we demonstrate the application of a three-dimensional liquid chromatography approach to a clarified cell homogenate containing a therapeutic enzyme. Each separation dimension determines a molecular property relevant to the chromatographic behavior of each component. Matching of the peaks across the different separation dimensions and against a high-resolution reference chromatogram allows to assign the determined parameters to pseudo-components, allowing to determine the most promising technique for the removal of each impurity. More detailed process design using mechanistic models requires isotherm parameters. For this purpose, the second dimension consists of multiple linear gradient separations on columns in a high-throughput screening compatible format, that allow regression of isotherm parameters with an average standard error of 8%. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:1283-1291, 2016. © 2016 American Institute of Chemical Engineers.

Aminoquinolines as fluorescent labels for hydrophilic interaction liquid chromatography of oligosaccharides.

PubMed

Struwe, Weston B; Rudd, Pauline M

2012-08-01

In this study, we investigated the potential of four different aminoquinoline (AQ) compounds as fluorescent labels for glycan analysis using hydrophilic interaction liquid chromatography (HILIC) and fluorescence detection (FLD). We confirmed the optimal excitation and emission wavelengths of 3-AQ and 6-AQ conjugated to glycan standards using three-dimensional fluorescent spectral scanning. The optimal excitation and emission wavelengths for 6-AQ were confirmed at λ(ex)=355 nm and λ(em)=440 nm. We concluded that the optimal wavelengths for 3-AQ were λ(ex)=355 nm and λ(em)=420 nm, which differed considerably from the wavelengths applied in previous reports. HILIC-FLD chromatograms using experimentally determined wavelengths were similar to 2-aminobenzamide controls, but the peak capacity and resolution differed significantly when published 3-AQ λ(ex/em) values were applied. Furthermore, we found that 5-AQ and 8-AQ labeled maltohexaose did not display any fluorescent properties when used as a carbohydrate tag for HPLC analysis. Finally, we applied experimentally determined wavelengths to 3-AQ labeled N-glycans released from human IgG to illustrate changes in retention time as well as to demonstrate that AQ labeling is applicable to complex sample analysis via exoglycosidase sequencing.

Measurement of H2S in Crude Oil and Crude Oil Headspace Using Multidimensional Gas Chromatography, Deans Switching and Sulfur-selective Detection

PubMed Central

Heshka, Nicole E.; Hager, Darcy B.

2015-01-01

A method for the analysis of dissolved hydrogen sulfide in crude oil samples is demonstrated using gas chromatography. In order to effectively eliminate interferences, a two dimensional column configuration is used, with a Deans switch employed to transfer hydrogen sulfide from the first to the second column (heart-cutting). Liquid crude samples are first separated on a dimethylpolysiloxane column, and light gases are heart-cut and further separated on a bonded porous layer open tubular (PLOT) column that is able to separate hydrogen sulfide from other light sulfur species. Hydrogen sulfide is then detected with a sulfur chemiluminescence detector, adding an additional layer of selectivity. Following separation and detection of hydrogen sulfide, the system is backflushed to remove the high-boiling hydrocarbons present in the crude samples and to preserve chromatographic integrity. Dissolved hydrogen sulfide has been quantified in liquid samples from 1.1 to 500 ppm, demonstrating wide applicability to a range of samples. The method has also been successfully applied for the analysis of gas samples from crude oil headspace and process gas bags, with measurement from 0.7 to 9,700 ppm hydrogen sulfide. PMID:26709594

Evaluation of two-dimensional electrophoresis and liquid chromatography – tandem mass spectrometry for tissue-specific protein profiling of laser-microdissected plant samples

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

Schad, Martina; Lipton, Mary S.; Giavalisco, Patrick

2005-07-14

Laser microdissection (LM) allows the collection of homogeneous tissue- and cell specific plant samples. The employment of this technique with subsequent protein analysis has thus far not been reported for plant tissues, probably due to the difficulties associated with defining a reasonable cellular morphology and, in parallel, allowing efficient protein extraction from tissue samples. The relatively large sample amount needed for successful proteome analysis is an additional issue that complicates protein profiling on a tissue- or even cell-specific level. In contrast to transcript profiling that can be performed from very small sample amounts due to efficient amplification strategies, there ismore » as yet no amplification procedure for proteins available. In the current study, we compared different tissue preparation techniques prior to LM/laser pressure catapulting (LMPC) with respect to their suitability for protein retrieval. Cryosectioning was identified as the best compromise between tissue morphology and effective protein extraction. After collection of vascular bundles from Arabidopsis thaliana stem tissue by LMPC, proteins were extracted and subjected to protein analysis, either by classical two-dimensional gel electrophoresis (2-DE), or by high-efficiency liquid chromatography (LC) in conjunction with tandem mass spectrometry (MS/MS). Our results demonstrate that both methods can be used with LMPC collected plant material. But because of the significantly lower sample amount required for LC-MS/MS than for 2-DE, the combination of LMPC and LC-MS/MS has a higher potential to promote comprehensive proteome analysis of specific plant tissues.« less

Active Solvent Modulation: A Valve-Based Approach To Improve Separation Compatibility in Two-Dimensional Liquid Chromatography.

PubMed

Stoll, Dwight R; Shoykhet, Konstantin; Petersson, Patrik; Buckenmaier, Stephan

2017-09-05

Two-dimensional liquid chromatography (2D-LC) is increasingly being viewed as a viable tool for solving difficult separation problems, ranging from targeted separations of structurally similar molecules to untargeted separations of highly complex mixtures. In spite of this performance potential, though, many users find method development challenging and most frequently cite the "incompatibility" between the solvent systems used in the first and second dimensions as a major obstacle. This solvent strength related incompatibility can lead to severe peak distortion and loss of resolution and sensitivity in the second dimension. In this paper, we describe a novel approach to address the incompatibility problem, which we refer to as Active Solvent Modulation (ASM). This valve-based approach enables dilution of 1 D effluent with weak solvent prior to transfer to the 2 D column but without the need for additional instrument hardware. ASM is related to the concept we refer to as Fixed Solvent Modulation (FSM), with the important difference being that ASM allows toggling of the diluent stream during each 2 D separation cycle. In this work, we show that ASM eliminates the major drawbacks of FSM including complex elution solvent profiles, baseline disturbances, and slow 2 D re-equilibration and demonstrate improvements in 2 D separation quality using both simple small molecule probes and degradants of heat-treated bovine insulin as case studies. We believe that ASM will significantly ease method development for 2D-LC, providing a path to practical methods that involve both highly complementary 1 D and 2 D separations and sensitive detection.

Quantitative analysis of valsartan by two-dimensional liquid chromatography (2D-HPLC) and its application in a bioequivalence study in Chinese volunteers
.

PubMed

Zhang, Min; Deng, Yang; Cai, Hua-Lin; Fang, Ping-Fei; Yan, Miao; Zhang, Bi-Kui; Wu, Yan-Qin

2017-04-01

To develop a sensitive, two-dimensional liquid chromatography (2D-LC) method for determination of valsartan, applied to investigate bioequivalence of two valsartan tablets in Chinese volunteers under fasting condition. A full automatic 2D-HPLC system was used to quantify valsartan in human plasma. The analytes were extracted by protein precipitation, using telmisartan as internal standard. The analytical method was applied in a randomized, crossover bioequivalence study of valsartan tablets; the study enrolled 18 Chinese volunteers (12 were men and 6 were women). The subjects received a single 160-mg dose of test or reference preparation with 7-days of washout under fasting state. Plasma samples were collected, pharmacokinetic parameters were obtained and the bioequivalence was evaluated. The calibration range was 9.2 - 4213.8 ng×mL-1. Inter- and intraprecision was less than 7.0%, and accuracies ranged from 99.5 to 103.8%. The extraction recovery for valsartan varied between 89.3 and 97.8%, and the stability in all conditions was excellent. The 90% CI of AUC_0→36h and C_max were 96.5 - 109.4% and 94.2 - 108.6%, respectively. The relative bioavailability was 103.9 ± 15.7%. No gender difference was observed in pharmacokinetic parameters. A sensitive 2D-HPLC method was established for the estimation of valsartan in human plasma and successfully applied in a bioequivalence study of valsartan, which suggests that these two formulations can be assumed to be bioequivalent.
.

Analysis of selected herbicide metabolites in surface and ground water of the United States

USGS Publications Warehouse

Scribner, E.A.; Thurman, E.M.; Zimmerman, L.R.

2000-01-01

One of the primary goals of the US Geological Survey (USGS) Laboratory in Lawrence, Kansas, is to develop analytical methods for the analysis of herbicide metabolites in surface and ground water that are vital to the study of herbicide fate and degradation pathways in the environment. Methods to measure metabolite concentrations from three major classes of herbicides - triazine, chloroacetanilide and phenyl-urea - have been developed. Methods for triazine metabolite detection cover nine compounds: six compounds are detected by gas chromatography/mass spectrometry; one is detected by high-performance liquid chromatography with diode-array detection; and eight are detected by liquid chromatography/mass spectrometry. Two metabolites of the chloroacetanilide herbicides - ethane sulfonic acid and oxanilic acid - are detected by high-performance liquid chromatography with diode-array detection and liquid chromatography/mass spectrometry. Alachlor ethane sulfonic acid also has been detected by solid-phase extraction and enzyme-linked immunosorbent assay. Six phenylurea metabolites are all detected by liquid chromatography/mass spectrometry; four of the six metabolites also are detected by gas chromatography/mass spectrometry. Additionally, surveys of herbicides and their metabolites in surface water, ground water, lakes, reservoirs, and rainfall have been conducted through the USGS laboratory in Lawrence. These surveys have been useful in determining herbicide and metabolite occurrence and temporal distribution and have shown that metabolites may be useful in evaluation of non-point-source contamination. Copyright (C) 2000 Elsevier Science B.V.

Phenolic composition of pomegranate peel extracts using an liquid chromatography-mass spectrometry approach with silica hydride columns.

PubMed

Young, Joshua E; Pan, Zhongli; Teh, Hui Ean; Menon, Veena; Modereger, Brent; Pesek, Joseph J; Matyska, Maria T; Dao, Lan; Takeoka, Gary

2017-04-01

The peels of different pomegranate cultivars (Molla Nepes, Parfianka, Purple Heart, Wonderful and Vkunsyi) were compared in terms of phenolic composition and total phenolics. Analyses were performed on two silica hydride based stationary phases: phenyl and undecanoic acid columns. Quantitation was accomplished by developing a liquid chromatography with mass spectrometry approach for separating different phenolic analytes, initially in the form of reference standards and then with pomegranate extracts. The high-performance liquid chromatography columns used in the separations had the ability to retain a wide polarity range of phenolic analytes, as well as offering beneficial secondary selectivity mechanisms for resolving the isobaric compounds, catechin and epicatechin. The Vkunsyi peel extract had the highest concentration of phenolics (as determined by liquid chromatography with mass spectrometry) and was the only cultivar to contain the important compound punicalagin. The liquid chromatography with mass spectrometry data were compared to the standard total phenolics content as determined by using the Folin-Ciocalteu assay. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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.

Preparation and Characterization of a Polymeric Monolithic Column for Use in High-Performance Liquid Chromatography (HPLC)

ERIC Educational Resources Information Center

Bindis, Michael P.; Bretz, Stacey Lowery; Danielson, Neil D.

2011-01-01

The high-performance liquid chromatography (HPLC) experiment, most often done in the undergraduate analytical instrumentation laboratory course, generally illustrates reversed-phase chromatography using a commercial C[subscript]18 silica column. To avoid the expense of periodic column replacement and introduce a choice of columns with different…

75 FR 14154 - Notice of Receipt of Several Pesticide Petitions Filed for Residues of Pesticide Chemicals in or...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-03-24

... for plant commodities) are both gas liquid chromatography (GLC) methods with electron capture... analytical methodology using liquid chromatography/mass spectrometry/mass spectrometry (LC/MS/MS) detection...-aminopropane]) using gas chromatography (GC) have been submitted to the EPA. In addition, a new validated...

Preparative Isolation and Purification of Flavone C-Glycosides from the Leaves of Ficus microcarpa L. f by Medium-Pressure Liquid Chromatography, High-Speed Countercurrent Chromatography, and Preparative Liquid Chromatography

PubMed Central

Wang, Xiaohong; Liang, Yong; Zhu, Licai; Xie, Huichun; Li, Hang; He, Junting; Pan, Man; Zhang, Tianyou; Ito, Yoichiro

2009-01-01

Combined with medium-pressure liquid chromatography (MPLC) and preparative high-performance liquid chromatography (perp-HPLC), high-speed countercurrent chromatography (HSCCC) was applied for separation and purification of flavone C-glycosides from the crude extract of leaves of Ficus microcarpae L. f. HSCCC separation was performed on a two-phase solvent system composed of methyl tert- butyl ether - ethyl acetate – 1-butanol – acetonitrile – 0.1% aqueous trifluoroacetic acid at a volume ratio of 1:3:1:1:5. Partially resolved peak fractions from HSCCC separation were further purified by preparative HPLC. Four well-separated compounds were obtained and their purities were determined by HPLC. The purities of these peaks were 97.28%, 97.20%, 92.23%, and 98.40%.. These peaks were characterized by ESI-MSn. According to the reference, they were identified as orientin (peak I), isovitexin-3″-O-glucopyranoside (peak II), isovitexin (peak III), and vitexin (peak IV), yielded 1.2 mg, 4.5 mg, 3.3 mg, and 1.8 mg, respectively. PMID:20190866

Analysis of Whiskey by Dispersive Liquid-Liquid Microextraction Coupled with Gas Chromatography/Mass Spectrometry: An Upper Division Analytical Chemistry Experiment Guided by Green Chemistry

ERIC Educational Resources Information Center

Owens, Janel E.; Zimmerman, Laura B.; Gardner, Michael A.; Lowe, Luis E.

2016-01-01

Analysis of whiskey samples prepared by a green microextraction technique, dispersive liquid-liquid microextraction (DLLME), before analysis by a qualitative gas chromatography-mass spectrometry (GC/MS) method, is described as a laboratory experiment for an upper division instrumental methods of analysis laboratory course. Here, aroma compounds in…

Quantitative Analysis of Tetramethylenedisulfotetramine ("Tetramine") Spiked into Beverages by Liquid Chromatography Tandem Mass Spectrometry with Validation by Gas Chromatography Mass Spectrometry

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

Owens, J; Hok, S; Alcaraz, A

Tetramethylenedisulfotetramine, commonly known as tetramine, is a highly neurotoxic rodenticide (human oral LD{sub 50} = 0.1 mg/kg) used in hundreds of deliberate food poisoning events in China. Here we describe a method for quantitation of tetramine spiked into beverages, including milk, juice, tea, cola, and water and cleaned up by C8 solid phase extraction and liquid-liquid extraction. Quantitation by high performance liquid chromatography tandem mass spectrometry (LC/MS/MS) was based upon fragmentation of m/z 347 to m/z 268. The method was validated by gas chromatography mass spectrometry (GC/MS) operated in SIM mode for ions m/z 212, 240, and 360. The limitmore » of quantitation was 0.10 {micro}g/mL by LC/MS/MS versus 0.15 {micro}g/mL for GC/MS. Fortifications of the beverages at 2.5 {micro}g/mL and 0.25 {micro}g/mL were recovered ranging from 73-128% by liquid-liquid extraction for GC/MS analysis, 13-96% by SPE and 10-101% by liquid-liquid extraction for LC/MS/MS analysis.« less

Determination of γ-hydroxybutyrate in human urine samples by ion exclusion and ion exchange two-dimensional chromatography system.

PubMed

Liu, Junwei; Deng, Zhifen; Zhu, Zuoyi; Wang, Yong; Wang, Guoqing; Sun, Yu-An; Zhu, Yan

2017-12-15

A two-dimensional ion chromatography system was developed for the determination of γ-hydroxybutyrate (GHB) in human urine samples. Ion exclusion chromatography was used in the first dimensional separation for elimination of urine matrices and detection of GHB above 10mgL -1 , ion exchange chromatography was used in the second dimensional separation via column-switching technique for detection of GHB above 0.08mgL -1 . Under the optimized chromatographic conditions, the ion exclusion and ion exchange chromatography separation system exhibited satisfactory repeatability (RSD<3.1%, n=6) and good linearity in the range of 50-1000mgL -1 and 0.5-100mgL -1 , respectively. By this method, concentrations of GHB in the selected human urine samples were detected in the range of 0-1.57mgL -1 . The urine sample containing 0.89mgL -1 GHB was selected to evaluate the accuracy; the spiked recoveries of GHB were 95.9-102.8%. The results showed that the two-dimensional ion chromatography system was convenient and practical for the determination of GHB in human urine samples. Copyright © 2017 Elsevier B.V. All rights reserved.

Liquid Chromatography Electrospray Ionization Mass Spectrometric (LC-ESI-MS) and Desorption Electrospray Ionization Mass Spectrometric (DESI-MS) Identification of Chemical Warfare Agents in Consumer Products

DTIC Science & Technology

2007-06-01

T ACanadaY Approved for PublicR Distribution Uln& Liquid Chromatography Electrospray Ionization Mass Spectrometric ( LC -ESI- MS) and Desorption...consumer products with chemical warfare agents or other toxic chemicals. Liquid chromatography electrospray ionization mass spectrometry ( LC -ESI-MS) and...house LC -ESI-MS and LC -ESI-MS/MS methods were evaluated for the determination of chemical warfare agents in spiked bottled water samples. The

Quantitative analysis of phylloquinone (vitamin K1) in soy bean oils by high-performance liquid chromatography.

PubMed

Zonta, F; Stancher, B

1985-07-19

A high-performance liquid chromatographic method for determining phylloquinone (vitamin K1) in soy bean oils is described. Resolution of vitamin K1 from interfering peaks of the matrix was obtained after enzymatic digestion, extraction and liquid-solid chromatography on alumina. An isocratic reversed-phase chromatography with UV detection was used in the final stage. The quantitation was carried out by the standard addition method, and the recovery of the whole procedure was 88.2%.

EPA Method 8321B (SW-846): Solvent-Extractable Nonvolatile Compounds by High Performance Liquid Chromatography-Thermospray-Mass Spectrometry (HPLC-TS-MS) or Ultraviolet (UV) Detection

EPA Pesticide Factsheets

Method 8321B describes procedures for preparation and analysis of solid, aqueous liquid, drinking water and wipe samples using high performance liquid chromatography and mass spectrometry for extractable non-volatile compounds.

Improvement of mineral oil saturated and aromatic hydrocarbons determination in edible oil by liquid-liquid-gas chromatography with dual detection.

PubMed

Zoccali, Mariosimone; Barp, Laura; Beccaria, Marco; Sciarrone, Danilo; Purcaro, Giorgia; Mondello, Luigi

2016-02-01

Mineral oils, which are mainly composed of saturated hydrocarbons and aromatic hydrocarbons, are widespread food contaminants. Liquid chromatography coupled to gas chromatography with flame ionization detection represents the method of choice to determine these two families. However, despite the high selectivity of this technique, the presence of olefins (particularly squalene and its isomers) in some samples as in olive oils, does not allow the correct quantification of the mineral oil aromatic hydrocarbons fraction, requiring additional off-line tools to eliminate them. In the present research, a novel on-line liquid chromatography coupled to gas chromatography method is described for the determination of hydrocarbon contamination in edible oils. Two different liquid chromatography columns, namely a silica one (to retain the bulk of the matrix) and a silver-ion one (which better retains the olefins), were coupled in series to obtain the mineral oil aromatic hydrocarbons hump free of interfering peaks. Furthermore, the use of a simultaneous dual detection, flame ionization detector and triple quadrupole mass spectrometer allowed us not only to quantify the mineral oil contamination, but also to evaluate the presence of specific markers (i.e. hopanes) to confirm the petrogenic origin of the contamination. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Crosslinked structurally-tuned polymeric ionic liquids as stationary phases for the analysis of hydrocarbons in kerosene and diesel fuels by comprehensive two-dimensional gas chromatography.

PubMed

Zhang, Cheng; Park, Rodney A; Anderson, Jared L

2016-04-01

Structurally-tuned ionic liquids (ILs) have been previously applied as the second dimension column in comprehensive two-dimensional gas chromatography (GC×GC) and have demonstrated high selectivity in the separation of individual aliphatic hydrocarbons from other aliphatic hydrocarbons. However, the maximum operating temperatures of these stationary phases limit the separation of analytes with high boiling points. In order to address this issue, a series of polymeric ionic liquid (PIL)-based stationary phases were prepared in this study using imidazolium-based IL monomers via in-column free radical polymerization. The IL monomers were functionalized with long alkyl chain substituents to provide the needed selectivity for the separation of aliphatic hydrocarbons. Columns were prepared with different film thicknesses to identify the best performing stationary phase for the separation of kerosene. The bis[(trifluoromethyl)sulfonyl]imide ([NTf2](-))-based PIL stationary phase with larger film thickness (0.28μm) exhibited higher selectivity for aliphatic hydrocarbons and showed a maximum allowable operating temperature of 300°C. PIL-based stationary phases containing varied amount of IL-based crosslinker were prepared to study the effect of the crosslinker on the selectivity and thermal stability of the resulting stationary phase. The optimal resolution of aliphatic hydrocarbons was achieved when 50% (w/w) of crosslinker was incorporated into the PIL-based stationary phase. The resulting stationary phase exhibited good selectivity for different groups of aliphatic hydrocarbons even after being conditioned at 325°C. Finally, the crosslinked PIL-based stationary phase was compared with SUPELCOWAX 10 and DB-17 columns for the separation of aliphatic hydrocarbons in diesel fuel. Better resolution of aliphatic hydrocarbons was obtained when employing the crosslinked PIL-based stationary phase as the second dimension column. Copyright © 2016 Elsevier B.V. All rights reserved.

Comparative Proteomic Analysis of Three Gelatinous Chinese Medicines and Their Authentications by Tryptic-digested Peptides Profiling using Matrix-assisted Laser Desorption/Ionization-time of Flight/Time of Flight Mass Spectrometry.

PubMed

Yang, Huan; Zheng, Jie; Wang, Hai-Yan; Li, Nan; Yang, Ya-Ya; Shen, Yu-Ping

2017-01-01

Gelatinous Chinese medicines (GCMs) including Asini Corii Colla, Testudinis Carapacis ET Plastri Colla, and Cervi Cornus Colla, were made from reptile shell or mammalian skin or deer horn, and consumed as a popular tonic, as well as hemopoietic and hemostatic agents. Misuse of them would not exert their functions, and fake or adulterate products have caused drug market disorder and affected food and drug safety. GCMs are rich in denatured proteins, but insufficient in available DNA fragments, hence commonly used cytochrome c oxidase I barcoding was not successful for their authentication. In this study, we performed comparative proteomic analysis of them and their animal origins to identify the composition of intrinsic proteins for the first time. A reliable and convenient approach was proposed for their authentication, by the incorporation of sodium dodecyl sulfate-polyacrylamide gel electrophoresis, two-dimensional electrophoresis, and matrix-assisted laser desorption/ionization-time of flight/time of flight mass spectrometry (MALDI-TOF/TOF-MS). A total of 26 proteins were identified from medicinal parts of original animals, and GCMs proteins presented in a dispersive manner in electrophoresis analyses due to complicated changes in the structure of original proteins caused by long-term decoction and the addition of ingredients during their manufacturing. In addition, by comparison of MALDI-TOF/TOF-MS profiling, 19 signature peptide fragments originated from the protein of GCM products were selected according to criteria. These could assist in the discrimination and identification of adulterates of GCMs and other ACMs for their form of raw medicinal material, the pulverized, and even the complex. Comparative proteomic analysis of three gelatinous Chinese medicines was conducted, and their authentications were based on tryptic-digested peptides profiling using matrix-assisted laser desorption/ionization-time of flight/time of flight mass spectrometry. Abbreviations used: GCMs: Gelatinous Chinese medicines, COI: Cytochrome c oxidase I, SDS-PAGE: Sodium dodecyl sulfate polyacrylamide gel electrophoresis, 2-DE: Two-dimensional electrophoresis, MALDI-TOF/TOF-MS: Matrix-assisted laser desorption/ionization-time of flight/time of flight mass spectrometry, LC: Liquid chromatography, ChP: Chinese Pharmacopoeia, HPLC: High performance liquid chromatography, LC-ESI + -MS: Liquid chromatography-electro spray ionization-mass spectrometry, IEF: isoelectric focusing, HCCA: α-Cyano-4-hydroxycinnamic acid.

Characterisation of dense non-aqueous phase liquids of coal tar using comprehensive two-dimensional gas chromatography coupled with time of flight mass spectrometry.

NASA Astrophysics Data System (ADS)

Gauchotte-Lindsay, Caroline; McGregor, Laura; Richards, Phil; Kerr, Stephanie; Glenn, Aliyssa; Thomas, Russell; Kalin, Robert

2013-04-01

Comprehensive two-dimensional gas chromatography (GCxGC) is a recently developed analytical technique in which two capillary columns with different stationary phases are placed in series enabling planar resolution of the analytes. The resolution power of GCxGC is one order of magnitude higher than that of one dimension gas chromatography. Because of its high resolution capacity, the use of GCxGC for complex environmental samples such as crude oils, petroleum derivatives and polychlorinated biphenyls mixtures has rapidly grown in recent years. We developed a one-step method for the forensic analysis of coal tar dense non-aqueous phase liquids (DNAPLs) from former manufactured gas plant (FMGP) sites. Coal tar is the by-product of the gasification of coal for heating and lighting and it is composed of thousands of organic and inorganic compounds. Before the boom of natural gases and oils, most towns and cities had one or several manufactured gas plants that have, in many cases, left a devastating environmental print due to coal tar contamination. The fate of coal tar DNAPLs, which can persist in the environment for more than a hundred years, is therefore of crucial interest. The presented analytical method consists of a unique clean-up/ extraction stage by pressurized liquid extraction and a single analysis of its organic chemical composition using GCxGC coupled with time of flight mass spectrometry (TOFMS). The chemical fingerprinting is further improved by derivatisation by N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) of the tar compounds containing -OH functions such as alcohols and carboxylic acids. We present here how, using the logical order of elution in GCxGC-TOFMS system, 1) the identification of never before observed -OH containing compounds is possible and 2) the isomeric selectivity of an oxidation reaction on a DNAPL sample can be revealed. Using samples collected at various FMGP sites, we demonstrate how this GCxGC method enables the simultaneous uncovering of information on the source of the coal tar, particularly the coal gasification process it originates from, and on its fate once released in the subsurface, i.e. the nature of the transformations it underwent such as evaporation, water-washing, chemical reactions or biodegradation.

Classification of organic aerosol in the atmosphere over Seoul based on chemical group separation using two dimensional gas chromatography-time of flight mass spectrometry (GC×GC TOFMS) data

NASA Astrophysics Data System (ADS)

Jeon, S.; Lim, H. B.; Choi, N.; Lee, J.; Ahn, Y. K.; Kim, Y. P.

2016-12-01

Organic aerosols contain thousands of organic compounds and contribute to 20-90% of the total fine aerosol mass. For analyzing organic aerosols, a wide range of analytical techniques have been used such as gas chromatography mass spectrometer (GC/MS), liquid chromatography mass spectrometer (LC/MS), aerosol mass spectrometer (AMS), etc. Among them, comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometer (GCxGC/TOF-MS) can provide higher chemical resolution than AMS and analyze more mass fractions of organic aerosols than GC/MS. In this study, we suggest a new data processing method using GCxGC/TOF-MS data for analyzing organic compounds in the ambient aerosols. TSP samples were collected on the roof of the Asan engineering building, Ewha Womans University, Seoul, South Korea (37.56 °N, 126.94 °E, 20 m above ground level). A total of 67 samples were obtained during summer (August 2013) and winter (January and February 2014) with a PUF sampler (Tisch, TE-1000) on quartz fiber filter. Filters were extracted using accelerated solvent extractor with a mixture of dichloromethane and methanol (3:1, v/v). Total extracts were blown down to 0.5 mL using a nitrogen evaporator (Turbo Vap Ⅱ, caliper Life Sciences). Organic compounds in the TSP samples were separated into 6 chemical groups, depending on their retention time in two dimensions for their volatility and polarity. All area of peaks in each group was summed and variance of total area in each group was compared depending on season and diurnal cycle.

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)

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.

40 CFR Appendix A to Subpart C of... - Alternative Testing Methods Approved for Analyses Under the Safe Drinking Water Act

Code of Federal Regulations, 2013 CFR

2013-07-01

... Chromatography/Mass Spectrometry (GC/MS) 525.3 24 Carbofuran High-performance liquid chromatography (HPLC) with... (HPLC) with Post-Column Derivatization and Fluorescence Detection 6651 B 6651 B 6651 B-00. Heptachlor... Spectrometry (GC/MS) 525.3 24 Oxamyl High-performance liquid chromatography (HPLC) with post-column...

Ionic-liquid-based ultrasound-assisted extraction of isoflavones from Belamcanda chinensis and subsequent screening and isolation of potential α-glucosidase inhibitors by ultrafiltration and semipreparative high-performance liquid chromatography.

PubMed

Li, Senlin; Li, Sainan; Huang, Yu; Liu, Chunming; Chen, Lina; Zhang, Yuchi

2017-06-01

The separation of a compound of interest from its structurally similar homologues to produce high-purity natural products is a challenging problem. This work proposes a novel method for the separation of iristectorigenin A from its structurally similar homologues by ionic-liquid-based ultrasound-assisted extraction and the subsequent screening and isolation of potential α-glucosidase inhibitors via ultrafiltration and semipreparative high-performance liquid chromatography. Ionic-liquid-based ultrasound-assisted extraction was successfully applied to the extraction of tectorigenin, iristectorigenin A, irigenin, and irisflorentin from Belamcanda chinensis. The optimum conditions for the efficient extraction of isoflavones were determined as 1.0 M 1-ethyl-3-methylimidazolium tetrafluoroborate with extraction time of 30 min and a solvent to solid ratio of 30 mL/g. Ultrafiltration with liquid chromatography and mass spectrometry was applied to screen and identify α-glucosidase inhibitors from B. chinensis, followed by the application of semipreparative high-performance liquid chromatography to separate and isolate the active constituents. Four major compounds including tectorigenin, iristectorigenin A, irigenin, and irisflorentin were screened and identified as α-glucosidase inhibitors, and then the four active compounds abovementioned were subsequently isolated by semipreparative high-performance liquid chromatography (99.89, 88.97, 99.79, and 99.97% purity, respectively). The results demonstrate that ionic liquid extraction can be successfully applied to the extraction of isoflavones from B. chinensis. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Free silanols and ionic liquids as their suppressors in liquid chromatography.

PubMed

Buszewska-Forajta, Magdalena; Markuszewski, Michał J; Kaliszan, Roman

2018-07-20

In this review, we will firstly discuss the types and the general properties of silica, focusing on the silica support used in chromatography and capillary electrophoresis. Additionally, the characterization of functional groups (silanols and siloxanes) will be considered in terms of activity of the stationary phases. We will then discuss physical chemistry of the stationary phases applied in liquid chromatography and capillary electrophoresis. The use of ionic liquids as a silanols' suppressors will be presented in the next parts of the study, along with the examples of specific applications. The review is completed with conclusions and an outlook for the future developments in the area of analytical applications of ionic liquids. Copyright © 2018 Elsevier B.V. All rights reserved.

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.

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.

Syringe needle-based sampling coupled with liquid-phase extraction for determination of the three-dimensional distribution of l-ascorbic acid in apples.

PubMed

Tang, Sheng; Lee, Hian Kee

2016-05-15

A novel syringe needle-based sampling approach coupled with liquid-phase extraction (NBS-LPE) was developed and applied to the extraction of l-ascorbic acid (AsA) in apple. In NBS-LPE, only a small amount of apple flesh (ca. 10mg) was sampled directly using a syringe needle and placed in a glass insert for liquid extraction of AsA by 80 μL oxalic acid-acetic acid. The extract was then directly analyzed by liquid chromatography. This new procedure is simple, convenient, almost organic solvent free, and causes far less damage to the fruit. To demonstrate the applicability of NBS-LPE, AsA levels at different sampling points in a single apple were determined to reveal the spatial distribution of the analyte in a three-dimensional model. The results also showed that this method had good sensitivity (limit of detection of 0.0097 mg/100g; limit of quantification of 0.0323 mg/100g), acceptable reproducibility (relative standard deviation of 5.01% (n=6)), a wide linear range of between 0.05 and 50mg/100g, and good linearity (r(2)=0.9921). This interesting extraction technique and modeling approach can be used to measure and monitor a wide range of compounds in various parts of different soft-matrix fruits and vegetables, including single specimens. Copyright © 2015 Elsevier Ltd. All rights reserved.

At-line hyphenation of high-speed countercurrent chromatography with Sephadex LH-20 column chromatography for bioassay-guided separation of antioxidants from vine tea (Ampelopsis grossedentata).

PubMed

Ma, Ruyi; Zhou, Rongrong; Tong, Runna; Shi, Shuyun; Chen, Xiaoqing

2017-01-01

Vine tea (Ampelopsis grossedentata), a widely used healthy tea, beverage and herbal medicine, exhibited strong antioxidant activity. However, systematic purification of antioxidants, especially for those with similar structures or polarities, is a challenging work. Here, we present a novel at-line hyphenation of high-speed countercurrent chromatography with Sephadex LH-20 column chromatography (HSCCC-Sephadex LH-20 CC) for rapid and efficient separation of antioxidants from vine tea target-guided by 1,1-diphenyl-2-picryl-hydrazyl radical-high performance liquid chromatography (DPPH-HPLC) experiment. A makeup pump, a six-port switching valve and a trapping column were served as interface. The configuration had no operational time and mobile phase limitations between two dimensional chromatography and showed great flexibility without tedious sample-handling procedure. Seven targeted antioxidants were firstly separated by stepwise HSCCC using petroleum ether-ethyl acetate-methanol-water (4:9:4:9, v/v/v/v) and (4:9:5:8, v/v/v/v) as solvent systems, and then co-eluted antioxidants were on-line trapped, concentrated and desorbed to Sephadex LH-20 column for further off-line purification by methanol. It is noted that six elucidated antioxidants with purity over 95% exhibited stronger activity than ascorbic acid (VC). More importantly, this at-line hyphenated strategy could sever as a rapid and efficient pathway for systematic purification of bioactive components from complex matrix. Copyright © 2016 Elsevier B.V. All rights reserved.

Determination of proenkephalin products in brain tissue by high-performance liquid chromatography and a modified bioassay procedure.

PubMed

Bailey, C; Kitchen, I

1985-06-01

A method is described for the separation of proenkephalin products using gradient high-performance liquid chromatography preceded by Sep-Pak chromatography. Samples can be assayed simply by use of a modified mouse vas deferens bioassay which is sufficiently sensitive for most applications. The preliminary Sep-Pak chromatography method excludes alpha-neoendorphin and the dynorphins and thus provides a suitable procedure for separation of prodynorphin and proenkephalin products.

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

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.

Integrating qualitative and quantitative characterization of traditional Chinese medicine injection by high-performance liquid chromatography with diode array detection and tandem mass spectrometry.

PubMed

Xie, Yuan-yuan; Xiao, Xue; Luo, Juan-min; Fu, Chan; Wang, Qiao-wei; Wang, Yi-ming; Liang, Qiong-lin; Luo, Guo-an

2014-06-01

The present study aims to describe and exemplify an integrated strategy of the combination of qualitative and quantitative characterization of a multicomponent mixture for the quality control of traditional Chinese medicine injections with the example of Danhong injection (DHI). The standardized chemical profile of DHI has been established based on liquid chromatography with diode array detection. High-performance liquid chromatography coupled with time-of-flight mass spectrometry and high-performance liquid chromatography with electrospray multistage tandem ion-trap mass spectrometry have been developed to identify the major constituents in DHI. The structures of 26 compounds including nucleotides, phenolic acids, and flavonoid glycosides were identified or tentatively characterized. Meanwhile, the simultaneous determination of seven marker constituents, including uridine, adenosine, danshensu, protocatechuic aldehyde, p-coumaric acid, rosmarinic acid, and salvianolic acid B, in DHI was performed by multiwavelength detection based on high-performance liquid chromatography with diode array detection. The integrated qualitative and quantitative characterization strategy provided an effective and reliable pattern for the comprehensive and systematic characterization of the complex traditional Chinese medicine system. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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)

Characterization of crude oil biomarkers using comprehensive two-dimensional gas chromatography coupled to tandem mass spectrometry.

PubMed

Mogollón, Noroska Gabriela Salazar; Prata, Paloma Santana; Dos Reis, Jadson Zeni; Neto, Eugênio Vaz Dos Santos; Augusto, Fabio

2016-09-01

Oil samples from Recôncavo basin (NE Brazil), previously analyzed by traditional techniques such as gas chromatography coupled to tandem mass spectrometry, were evaluated using comprehensive two-dimensional gas chromatography coupled to quadrupole mass spectrometry and comprehensive two-dimensional gas chromatography coupled to tandem mass spectrometry along with simplified methods of samples preparation to evaluate the differences and advantages of these analytical techniques to better understand the development of the organic matter in this basin without altering the normal distribution of the compounds in the samples. As a result, the geochemical parameters calculated by comprehensive two-dimensional gas chromatography coupled to tandem mass spectrometry described better the origin, maturity, and biodegradation of both samples probably by increased selectivity, resolution, and sensitivity inherent of the multidimensional technique. Additionally, the detection of the compounds such as, the C(14α-) homo-26-nor-17α-hopane series, diamoretanes, nor-spergulanes, C19 -C26 A-nor-steranes and 4α-methylsteranes resolved and detected by comprehensive two-dimensional gas chromatography coupled to tandem mass spectrometry were key to classify and differentiate these lacustrine samples according to their maturity and deposition conditions. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The gas–liquid chromatography of carboxylic acid esters of the urinary 11-deoxy-17-oxo steroids

PubMed Central

Sadler, Patricia A.; Kellie, A. E.

1967-01-01

1. The gas–liquid-chromatographic separations of the acetate, propionate, n-butyrate, isobutyrate and n-valerate esters of androsterone, aetiocholanolone and dehydroepiandrosterone were studied on a 1% neopentyl glycol sebacate column. The n-butyrate, isobutyrate and n-valerate esters were well resolved. 2. The three steroids derived from hydrolysed urinary 17-oxo steroid conjugate extracts were analysed by gas–liquid chromatography after conversion into their n-butyrate esters. The results were compared with independent determinations involving chromatography on alumina. PMID:4227802

The gas-liquid chromatography of carboxylic acid esters of the urinary 11-deoxy-17-oxo steroids. Determination as n-butyrates.

PubMed

Sadler, P A; Kellie, A E

1967-06-01

1. The gas-liquid-chromatographic separations of the acetate, propionate, n-butyrate, isobutyrate and n-valerate esters of androsterone, aetiocholanolone and dehydroepiandrosterone were studied on a 1% neopentyl glycol sebacate column. The n-butyrate, isobutyrate and n-valerate esters were well resolved. 2. The three steroids derived from hydrolysed urinary 17-oxo steroid conjugate extracts were analysed by gas-liquid chromatography after conversion into their n-butyrate esters. The results were compared with independent determinations involving chromatography on alumina.

40 CFR Appendix A to Subpart C of... - Alternative Testing Methods Approved for Analyses Under the Safe Drinking Water Act

Code of Federal Regulations, 2014 CFR

2014-07-01

... Spectrometry (GC/MS) 525.3 24 Carbofuran High-performance liquid chromatography (HPLC) with post-column... (HPLC) with Post-Column Derivatization and Fluorescence Detection 6651 B 6651 B 6651 B-00, B-05... Chromatography/Mass Spectrometry (GC/MS) 525.3 24 Oxamyl High-performance liquid chromatography (HPLC) with post...

Traceability and Quality Control in Traditional Chinese Medicine: From Chemical Fingerprint to Two-Dimensional Barcode.

PubMed

Cai, Yong; Li, Xiwen; Li, Mei; Chen, Xiaojia; Hu, Hao; Ni, Jingyun; Wang, Yitao

2015-01-01

Chemical fingerprinting is currently a widely used tool that enables rapid and accurate quality evaluation of Traditional Chinese Medicine (TCM). However, chemical fingerprints are not amenable to information storage, recognition, and retrieval, which limit their use in Chinese medicine traceability. In this study, samples of three kinds of Chinese medicines were randomly selected and chemical fingerprints were then constructed by using high performance liquid chromatography. Based on chemical data, the process of converting the TCM chemical fingerprint into two-dimensional code is presented; preprocess and filtering algorithm are also proposed aiming at standardizing the large amount of original raw data. In order to know which type of two-dimensional code (2D) is suitable for storing data of chemical fingerprints, current popular types of 2D codes are analyzed and compared. Results show that QR Code is suitable for recording the TCM chemical fingerprint. The fingerprint information of TCM can be converted into data format that can be stored as 2D code for traceability and quality control.

Ionic Liquid-Liquid Chromatography: A New General Purpose Separation Methodology.

PubMed

Brown, Leslie; Earle, Martyn J; Gîlea, Manuela A; Plechkova, Natalia V; Seddon, Kenneth R

2017-08-10

Ionic liquids can form biphasic solvent systems with many organic solvents and water, and these solvent systems can be used in liquid-liquid separations and countercurrent chromatography. The wide range of ionic liquids that can by synthesised, with specifically tailored properties, represents a new philosophy for the separation of organic, inorganic and bio-based materials. A customised countercurrent chromatograph has been designed and constructed specifically to allow the more viscous character of ionic liquid-based solvent systems to be used in a wide variety of separations (including transition metal salts, arenes, alkenes, alkanes, bio-oils and sugars).

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

PubMed Central

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. Images PMID:970947

75 FR 38156 - Small Business Size Standards: Waiver of the Nonmanufacturer Rule

Federal Register 2010, 2011, 2012, 2013, 2014

2010-07-01

... Systems (CS-MS), High Performance Liquid Chromatography (HPLC) Systems, Gas Chromatography Mass... Chromatography (HPLC) Systems, Gas Chromatography Mass Spectrometry (GC-MS) Systems, and, Inductively Coupled...

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.

A simple liquid extraction protocol for overcoming the ion suppression of triacylglycerols by phospholipids in liquid chromatography mass spectrometry studies.

PubMed

Araujo, Pedro; Tilahun, Ephrem; Breivik, Joar Fjørtoft; Abdulkader, Bashir M; Frøyland, Livar; Zeng, Yingxu

2016-02-01

It is well-known that triacylglycerol (TAG) ions are suppressed by phospholipid (PL) ions in regiospecific analysis of TAG by mass spectrometry (MS). Hence, it is essential to remove the PL during sample preparation prior to MS analysis. The present article proposes a cost-effective liquid-liquid extraction (LLE) method to remove PL from TAG in different kinds of biological samples by using methanol, hexane and water. High performance thin layer chromatography confirmed the lack of PL in krill oil and salmon liver samples, submitted to the proposed LLE protocol, and liquid chromatography tandem MS confirmed that the identified TAG ions were highly enhanced after implementing the LLE procedure. Copyright © 2015 Elsevier B.V. All rights reserved.

A novel four-dimensional analytical approach for analysis of complex samples.

PubMed

Stephan, Susanne; Jakob, Cornelia; Hippler, Jörg; Schmitz, Oliver J

2016-05-01

A two-dimensional LC (2D-LC) method, based on the work of Erni and Frei in 1978, was developed and coupled to an ion mobility-high-resolution mass spectrometer (IM-MS), which enabled the separation of complex samples in four dimensions (2D-LC, ion mobility spectrometry (IMS), and mass spectrometry (MS)). This approach works as a continuous multiheart-cutting LC system, using a long modulation time of 4 min, which allows the complete transfer of most of the first - dimension peaks to the second - dimension column without fractionation, in comparison to comprehensive two-dimensional liquid chromatography. Hence, each compound delivers only one peak in the second dimension, which simplifies the data handling even when ion mobility spectrometry as a third and mass spectrometry as a fourth dimension are introduced. The analysis of a plant extract from Ginkgo biloba shows the separation power of this four-dimensional separation method with a calculated total peak capacity of more than 8700. Furthermore, the advantage of ion mobility for characterizing unknown compounds by their collision cross section (CCS) and accurate mass in a non-target approach is shown for different matrices like plant extracts and coffee. Graphical abstract Principle of the four-dimensional separation.

Multiple, simultaneous, independent gradients for a versatile multidimensional liquid chromatography. Part II: Application 2: Computer controlled pH gradients in the presence of urea provide improved separation of proteins: Stability influenced anion and cation exchange chromatography.

PubMed

Hirsh, Allen G; Tsonev, Latchezar I

2017-04-28

This paper details the use of a method of creating controlled pH gradients (pISep) to improve the separation of protein isoforms on ion exchange (IEX) stationary phases in the presence of various isocratic levels of urea. The pISep technology enables the development of computer controlled pH gradients on both cationic (CEX) and anionic (AEX) IEX stationary phases over the very wide pH range from 2 to 12. In pISep, titration curves generated by proportional mixing of the acidic and basic pISep working buffers alone, or in the presence of non-buffering solutes such as the neutral salt NaCl (0-1M), polar organics such as urea (0-8M) or acetonitrile (0-80 Vol%), can be fitted with high fidelity using high order polynomials which, in turn allows construction of a mathematical manifold %A (% acidic pISep buffer) vs. pH vs. [non-buffering solute], permitting precise computer control of pH and the non-buffering solute concentration allowing formation of dual uncoupled liquid chromatographic (LC) gradients of arbitrary shape (Hirsh and Tsonev, 2012 [1]). The separation of protein isoforms examined in this paper by use of such pH gradients in the presence of urea demonstrates the fractionation power of a true single step two dimensional liquid chromatography which we denote as Stability-Influenced Ion Exchange Chromatography (SIIEX). We present evidence that SIIEX is capable of increasing the resolution of protein isoforms difficult to separate by ordinary pH gradient IEX, and potentially simplifying the development of laboratory and production purification strategies involving on-column simultaneous pH and urea unfolding or refolding of targeted proteins. We model some of the physics implied by the dynamics of the observed protein fractionations as a function of both urea concentration and pH assuming that urea-induced native state unfolding competes with native state electrostatic interaction binding to an IEX stationary phase. Implications for in vivo protein-membrane interactions are discussed. Copyright © 2017 Elsevier B.V. All rights reserved.

Application of an efficient strategy based on liquid-liquid extraction, high-speed counter-current chromatography, and preparative HPLC for the rapid enrichment, separation, and purification of four anthraquinones from Rheum tanguticum.

PubMed

Chen, Tao; Liu, Yongling; Zou, Denglang; Chen, Chen; You, Jinmao; Zhou, Guoying; Sun, Jing; Li, Yulin

2014-01-01

This study presents an efficient strategy based on liquid-liquid extraction, high-speed counter-current chromatography, and preparative HPLC for the rapid enrichment, separation, and purification of four anthraquinones from Rheum tanguticum. A new solvent system composed of petroleum ether/ethyl acetate/water (4:2:1, v/v/v) was developed for the liquid-liquid extraction of the crude extract from R. tanguticum. As a result, emodin, aloe-emodin, physcion, and chrysophanol were greatly enriched in the organic layer. In addition, an efficient method was successfully established to separate and purify the above anthraquinones by high-speed counter-current chromatography and preparative HPLC. This study supplies a new alternative method for the rapid enrichment, separation, and purification of emodin, aloe-emodin, physcione, and chrysophanol. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Rapid and sensitive screening and selective quantification of antibiotics in human urine by two-dimensional ultraperformance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry.

PubMed

Wang, He-Xing; Wang, Bin; Zhou, Ying; Jiang, Qing-Wu

2014-12-01

A rapid and sensitive method for the screening and selective quantification of antibiotics in urine by two-dimensional ultraperformance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry was developed. This method allowed the injection of 200 μL urine extract. The 200-μL injection volume used in this method increased the absolute sensitivity for target antibiotics in solvent by an average 13.3 times, with a range from 8.4 to 28.5 times, compared with the 10-μL conventional injection volume. A 96-well solid phase extraction procedure was established to eliminate the contamination on the chromatographic column resulting from the large-volume injection and increase the throughput of sample preparation. Fourteen target antibiotics from six common categories (β-lactams, quinolones, tetracyclines, macrolides, sulfonamides, and chloramphenicols) were selected as model compounds, and a database containing an additional 74 antibiotics was compiled for posttarget screening. The limit of detection of the target antibiotics, defined as a signal-to-noise ratio of 3, ranged from 0.04 to 1.99 ng/mL. The mean interday recoveries ranged between 79.6 and 121.3 %, with a relative standard deviation from 2.9 to 18.3 % at three spiking levels of 20 ng/mL, 50 ng/mL, and 100 ng/mL. This method was successfully applied in 60 real urine samples from schoolchildren aged 8-11 years, and four target antibiotics (azithromycin, sulfadiazine, trimethoprim, and oxytetracycline) and two posttarget antibiotics (sulfadimidine and cefaclor) were found in the urine samples. This method can be used as a large-scale biomonitoring tool for exposure of the human population to antibiotics.

Determination of nonylphenol isomers in landfill leachate and municipal wastewater using steam distillation extraction coupled with comprehensive two-dimensional gas chromatography/time-of-flight mass spectrometry.

PubMed

Zhang, Caixiang; Eganhouse, Robert P; Pontolillo, James; Cozzarelli, Isabelle M; Wang, Yanxin

2012-03-23

4-Nonylphenols (4-NPs) are known endocrine disruptors and by-products of the microbial degradation of nonylphenol polyethoxylate surfactants. One of the challenges to understanding the toxic effects of nonylphenols is the large number of isomers that may exist in environmental samples. In order to attribute toxic effects to specific compounds, a method is needed for the separation and quantitation of individual nonylphenol isomers. The pre-concentration methods of solvent sublimation, solid-phase extraction or liquid-liquid extraction prior to chromatographic analysis can be problematic because of co-extraction of thousands of compounds typically found in complex matrices such as municipal wastewater or landfill leachate. In the present study, steam distillation extraction (SDE) was found to be an effective pre-concentration method for extraction of 4-NPs from leachate and wastewater, and comprehensive two-dimensional gas chromatography (GC×GC) coupled with fast mass spectral data acquisition by time-of-flight mass spectrometry (ToFMS) enhanced the resolution and identification of 4-NP isomers. Concentrations of eight 4-NP isomers were determined in leachate from landfill cells of different age and wastewater influent and effluent samples. 4-NP isomers were about 3 times more abundant in leachate from the younger cell than the older one, whereas concentrations in wastewater effluent were either below detection limits or <1% of influent concentrations. 4-NP isomer distribution patterns were found to have been altered following release to the environment. This is believed to reflect isomer-specific degradation and accumulation of 4-NPs in the aquatic environment. Copyright © 2012 Elsevier B.V. All rights reserved.

Two-Dimensional MoS2-Based Zwitterionic Hydrophilic Interaction Liquid Chromatography Material for the Specific Enrichment of Glycopeptides.

PubMed

Xia, Chaoshuang; Jiao, Fenglong; Gao, Fangyuan; Wang, Heping; Lv, Yayao; Shen, Yehua; Zhang, Yangjun; Qian, Xiaohong

2018-06-05

Mass spectrometry (MS)-based glycoproteomics research requires highly efficient sample preparation to eliminate interference from non-glycopeptides and to improve the efficiency of glycopeptide detection. In this work, a novel MoS 2 /Au-NP (gold nanoparticle)-L-cysteine nanocomposite was prepared for glycopeptide enrichment. The two-dimensional (2D) structured MoS 2 nanosheets served as a matrix that could provide a large surface area for immobilizing hydrophilic groups (such as L-cysteine) with low steric hindrance between the materials and the glycopeptides. As a result, the novel nanomaterial possessed an excellent ability to capture glycopeptides. Compared to commercial zwitterionic hydrophilic interaction liquid chromatography (ZIC-HILIC) materials, the novel nanomaterials exhibited excellent enrichment performance with ultrahigh selectivity and sensitivity (approximately 10 fmol), high binding capacity (120 mg g -1 ), high enrichment recovery (more than 93%), satisfying batch-to-batch reproducibility, and good universality for glycopeptide enrichment. In addition, its outstanding specificity and efficiency for glycopeptide enrichment was confirmed by the detection of glycopeptides from an human serum immunoglobulin G (IgG) tryptic digest in quantities as low as a 1:1250 molar ratio of IgG tryptic digest to bovine serum albumin tryptic digest. The novel nanocomposites were further used for the analysis of complex samples, and 1920 glycopeptide backbones from 775 glycoproteins were identified in three replicate analyses of 50 μg of proteins extracted from HeLa cell exosomes. The resulting highly informative mass spectra indicated that this multifunctional nanomaterial-based enrichment method could be used as a promising tool for the in-depth and comprehensive characterization of glycoproteomes in MS-based glycoproteomics.

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. Copyright © 2014. Published by Elsevier B.V.

DNAPL Dissolution in Bedrock Fractures And Fracture Networks

DTIC Science & Technology

2011-06-01

were filtered through a 0.2 micron filter and then analyzed via ion chromatography ( Dionex DX-120, Sunnyvale, CA). An additional set of sorption...analyzed via ion chromatography ( Dionex DX-120, Sunnyvale, CA). The effluent pH was monitored periodically with pH test strips. Aqueous DHC...liquid EDTA ethylenediaminetetraacetic acid GC gas chromatograph HPLC high-performance liquid chromatography ISCO in situ chemical oxidation

Exudate Chemical Profiles Derived from Lespedeza and Other Tallgrass Prairie Plant Species

DTIC Science & Technology

2017-05-01

assayed by liquid chromatography–tandem mass spec- trometry (LC-MS/MS) and gas chromatography/mass spectrometry (GC/MS). The objective was to elucidate...molecular weight compounds were identified via gas chromatography/mass spectrometry (GC/MS) and tentatively identified as benzophenone and 1,4...diacetylbenzene. Three higher molecular weight compounds were identified by liquid chromatography-electrospray ionization- mass spectrometry (LC-ESI-MS

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)

Rapid characterization of the chemical constituents of Cortex Fraxini by homogenate extraction followed by UHPLC coupled with Fourier transform ion cyclotron resonance mass spectrometry and GC-MS.

PubMed

Wang, Yinan; Han, Fei; Song, Aihua; Wang, Miao; Zhao, Min; Zhao, Chunjie

2016-11-01

Cortex Fraxini is an important traditional Chinese medicine. In this work, a rapid and reliable homogenate extraction method was applied for the fast extraction for Cortex Fraxini, and the method was optimized by response surface methodology. Ultra high performance liquid chromatography combined with Fourier transform ion cyclotron resonance mass spectrometry and gas chromatography with mass spectrometry were established for the separation and characterization of the constituents of Cortex Fraxini. Liquid chromatography separation was conducted on a C 18 column (150 mm × 2.1 mm, 1.8 μm), and gas chromatography separation was performed on a capillary with a 5% phenyl-methylpolysiloxane stationary phase (30 m × 0.25 mm × 0.25 mm) by injection of silylated samples. According to the results, 33 chemical compounds were characterized by liquid chromatography with mass spectrometry, and 11 chemical compounds were characterized by gas chromatography with mass spectrometry, and coumarins were the major components characterized by both gas chromatography with mass spectrometry and liquid chromatography with mass spectrometry. The proposed homogenate extraction was an efficient and rapid method, and coumarins, phenylethanoid glycosides, iridoid glycosides, phenylpropanoids, and lignans were the main constituents of Cortex Fraxini. This work laid the foundation for further study of Cortex Fraxini and will be helpful for the rapid extraction and characterization of ingredients in other traditional Chinese medicines. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Applying Chromatography.

ERIC Educational Resources Information Center

Klein, Jessie W.; Patev, Paul

1998-01-01

Presents three experiments to introduce students to different kinds of chromatography: (1) paper chromatography; (2) gel filtration chromatography; and (3) reverse-phase liquid chromatography. Written in the form of a laboratory manual, explanations of each of the techniques, materials needed, procedures, and a glossary are included. (PVD)

Quantitative structure-retention relationship studies for taxanes including epimers and isomeric metabolites in ultra fast liquid chromatography.

PubMed

Dong, Pei-Pei; Ge, Guang-Bo; Zhang, Yan-Yan; Ai, Chun-Zhi; Li, Guo-Hui; Zhu, Liang-Liang; Luan, Hong-Wei; Liu, Xing-Bao; Yang, Ling

2009-10-16

Seven pairs of epimers and one pair of isomeric metabolites of taxanes, each pair of which have similar structures but different retention behaviors, together with additional 13 taxanes with different substitutions were chosen to investigate the quantitative structure-retention relationship (QSRR) of taxanes in ultra fast liquid chromatography (UFLC). Monte Carlo variable selection (MCVS) method was adopted to choose descriptors. The selected four descriptors were used to build QSRR model with multi-linear regression (MLR) and artificial neural network (ANN) modeling techniques. Both linear and nonlinear models show good predictive ability, of which ANN model was better with the determination coefficient R(2) for training, validation and test set being 0.9892, 0.9747 and 0.9840, respectively. The results of 100 times' leave-12-out cross validation showed the robustness of this model. All the isomers can be correctly differentiated by this model. According to the selected descriptors, the three dimensional structural information was critical for recognition of epimers. Hydrophobic interaction was the uppermost factor for retention in UFLC. Molecules' polarizability and polarity properties were also closely correlated with retention behaviors. This QSRR model will be useful for separation and identification of taxanes including epimers and metabolites from botanical or biological samples.

Combinatorial modification of human histone H4 quantitated by two-dimensional liquid chromatography coupled with top down mass spectrometry.

PubMed

Pesavento, James J; Bullock, Courtney R; LeDuc, Richard D; Mizzen, Craig A; Kelleher, Neil L

2008-05-30

Quantitative proteomics has focused heavily on correlating protein abundances, ratios, and dynamics by developing methods that are protein expression-centric (e.g. isotope coded affinity tag, isobaric tag for relative and absolute quantification, etc.). These methods effectively detect changes in protein abundance but fail to provide a comprehensive perspective of the diversity of proteins such as histones, which are regulated by post-translational modifications. Here, we report the characterization of modified forms of HeLa cell histone H4 with a dynamic range >10(4) using a strictly Top Down mass spectrometric approach coupled with two dimensions of liquid chromatography. This enhanced dynamic range enabled the precise characterization and quantitation of 42 forms uniquely modified by combinations of methylation and acetylation, including those with trimethylated Lys-20, monomethylated Arg-3, and the novel dimethylated Arg-3 (each <1% of all H4 forms). Quantitative analyses revealed distinct trends in acetylation site occupancy depending on Lys-20 methylation state. Because both modifications are dynamically regulated through the cell cycle, we simultaneously investigated acetylation and methylation kinetics through three cell cycle phases and used these data to statistically assess the robustness of our quantitative analysis. This work represents the most comprehensive analysis of histone H4 forms present in human cells reported to date.

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…

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)

Detection of radiation-induced hydrocarbons in baked sponged cake prepared with irradiated liquid egg

NASA Astrophysics Data System (ADS)

Schulzki, G.; Spiegelberg, A.; Bögl, K. W.; Schreiber, G. A.

1995-02-01

For identification of irradiated food, radiation-induced volatile hydrocarbons (HC) are determined by gas chromatography in the non-polar fraction of fat. However, in complex food matrices the detection is often disturbed by fat-associated compounds. On-line coupling of high performance liquid chromatography (LC) and gas chromatography (GC) is very efficient to remove such compounds from the HC fraction. The high sensitivity of this fast and efficient technique is demonstrated by the example of detection of radiation-induced HC in fat isolated from baked sponge cake which had been prepared with irradiated liquid egg.

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.

Multidimensional and comprehensive two-dimensional gas chromatography of dichloromethane soluble products from a high sulfur Jordanian oil shale.

PubMed

Amer, Mohammad W; Mitrevski, Blagoj; Jackson, W Roy; Chaffee, Alan L; Marriott, Philip J

2014-03-01

A high sulfur Jordanian oil shale was converted into liquid hydrocarbons by reaction at 390 °C under N2, and the dichloromethane soluble fraction of the products was isolated then analyzed by using gas chromatography (GC). Comprehensive two-dimensional GC (GC×GC) and multidimensional GC (MDGC) were applied for component separation on a polar - non-polar column set. Flame-ionization detection (FID) was used with GC×GC for general sample profiling, and mass spectrometry (MS) for component identification in MDGC. Multidimensional GC revealed a range of thiophenes (th), benzothiophenes (bth) and small amounts of dibenzothiophenes (dbth) and benzonaphthothiophenes (bnth). In addition, a range of aliphatic alkanes and cycloalkanes, ethers, polar single ring aromatic compounds and small amounts of polycyclic aromatics were also identified. Some of these compound classes were not uniquely observable by conventional 1D GC, and certainly this is true for many of their minor constituent members. The total number of distinct compounds was very large (ca.>1000). GC×GC was shown to be appropriate for general sample profiling, and MDGC-MS proved to be a powerful technique for the separation and identification of sulfur-containing components and other polar compounds. © 2013 Published by Elsevier B.V.

Development of quality assurance methods for epoxy graphite prepreg

NASA Technical Reports Server (NTRS)

Chen, J. S.; Hunter, A. B.

1982-01-01

Quality assurance methods for graphite epoxy/prepregs were developed. Liquid chromatography, differential scanning calorimetry, and gel permeation chromatography were investigated. These methods were applied to a second prepreg system. The resin matrix formulation was correlated with mechanical properties. Dynamic mechanical analysis and fracture toughness methods were investigated. The chromatography and calorimetry techniques were all successfully developed as quality assurance methods for graphite epoxy prepregs. The liquid chromatography method was the most sensitive to changes in resin formulation. The were also successfully applied to the second prepreg system.

High-performance liquid chromatography separation of unsaturated organic compounds by a monolithic silica column embedded with silver nanoparticles.

PubMed

Zhu, Yang; Morisato, Kei; Hasegawa, George; Moitra, Nirmalya; Kiyomura, Tsutomu; Kurata, Hiroki; Kanamori, Kazuyoshi; Nakanishi, Kazuki

2015-08-01

The optimization of a porous structure to ensure good separation performances is always a significant issue in high-performance liquid chromatography column design. Recently we reported the homogeneous embedment of Ag nanoparticles in periodic mesoporous silica monolith and the application of such Ag nanoparticles embedded silica monolith for the high-performance liquid chromatography separation of polyaromatic hydrocarbons. However, the separation performance remains to be improved and the retention mechanism as compared with the Ag ion high-performance liquid chromatography technique still needs to be clarified. In this research, Ag nanoparticles were introduced into a macro/mesoporous silica monolith with optimized pore parameters for high-performance liquid chromatography separations. Baseline separation of benzene, naphthalene, anthracene, and pyrene was achieved with the theoretical plate number for analyte naphthalene as 36,000 m(-1). Its separation function was further extended to cis/trans isomers of aromatic compounds where cis/trans stilbenes were chosen as a benchmark. Good separation of cis/trans-stilbene with separation factor as 7 and theoretical plate number as 76,000 m(-1) for cis-stilbene was obtained. The trans isomer, however, is retained more strongly, which contradicts the long- established retention rule of Ag ion chromatography. Such behavior of Ag nanoparticles embedded in a silica column can be attributed to the differences in the molecular geometric configuration of cis/trans stilbenes. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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.

Significant viscosity dependent deviations from classical van Deemter theory in liquid chromatography with porous silica monolithic columns.

PubMed

Nesterenko, Pavel N; Rybalko, Marina A; Paull, Brett

2005-06-01

Significant deviations from classical van Deemter behaviour, indicative of turbulent flow liquid chromatography, has been recorded for mobile phases of varying viscosity on porous silica monolithic columns at elevated mobile phase flow rates.

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)

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...

Quantitative analysis of fragrance in selectable one dimensional or two dimensional gas chromatography-mass spectrometry with simultaneous detection of multiple detectors in single injection.

PubMed

Tan, Hui Peng; Wan, Tow Shi; Min, Christina Liew Shu; Osborne, Murray; Ng, Khim Hui

2014-03-14

A selectable one-dimensional ((1)D) or two-dimensional ((2)D) gas chromatography-mass spectrometry (GC-MS) system coupled with flame ionization detector (FID) and olfactory detection port (ODP) was employed in this study to analyze perfume oil and fragrance in shower gel. A split/splitless (SSL) injector and a programmable temperature vaporization (PTV) injector are connected via a 2-way splitter of capillary flow technology (CFT) in this selectable (1)D/(2)D GC-MS/FID/ODP system to facilitate liquid sample injections and thermal desorption (TD) for stir bar sorptive extraction (SBSE) technique, respectively. The dual-linked injectors set-up enable the use of two different injector ports (one at a time) in single sequence run without having to relocate the (1)D capillary column from one inlet to another. Target analytes were separated in (1)D GC-MS/FID/ODP and followed by further separation of co-elution mixture from (1)D in (2)D GC-MS/FID/ODP in single injection without any instrumental reconfiguration. A (1)D/(2)D quantitative analysis method was developed and validated for its repeatability - tR; calculated linear retention indices (LRI); response ratio in both MS and FID signal, limit of detection (LOD), limit of quantitation (LOQ), as well as linearity over a concentration range. The method was successfully applied in quantitative analysis of perfume solution at different concentration level (RSD≤0.01%, n=5) and shower gel spiked with perfume at different dosages (RSD≤0.04%, n=5) with good recovery (96-103% for SSL injection; 94-107% for stir bar sorptive extraction-thermal desorption (SBSE-TD). Copyright © 2014 Elsevier B.V. All rights reserved.

Highly sensitive reversed-phase high-performance liquid chromatography assay for the detection of Tamm-Horsfall protein in human urine.

PubMed

Akimoto, Masaru; Hokazono, Eisaku; Ota, Eri; Tateishi, Takiko; Kayamori, Yuzo

2016-01-01

Tamm-Horsfall protein (also known as uromodulin) is the most abundant urinary protein in healthy individuals. Since initially characterized by Tamm and Horsfall, the amount of urinary excretion and structural mutations of Tamm-Horsfall protein is associated with kidney diseases. However, currently available assays for Tamm-Horsfall protein, which are mainly enzyme-linked immunosorbent assay-based, suffer from poor reproducibility and might give false negative results. We developed a novel, quantitative assay for Tamm-Horsfall protein using reversed-phase high-performance liquid chromatography. A precipitation pretreatment avoided urine matrix interference and excessive sample dilution. High-performance liquid chromatography optimization based on polarity allowed excellent separation of Tamm-Horsfall protein from other major urine components. Our method exhibited high precision (based on the relative standard deviations of intraday [≤2.77%] and interday [≤5.35%] repetitions). The Tamm-Horsfall protein recovery rate was 100.0-104.2%. The mean Tamm-Horsfall protein concentration in 25 healthy individuals was 31.6 ± 18.8 mg/g creatinine. There was a strong correlation between data obtained by high-performance liquid chromatography and enzyme-linked immunosorbent assay (r = 0.906), but enzyme-linked immunosorbent assay values tended to be lower than high-performance liquid chromatography values at low Tamm-Horsfall protein concentrations. The high sensitivity and reproducibility of our Tamm-Horsfall protein assay will reduce the number of false negative results of the sample compared with enzyme-linked immunosorbent assay. Moreover, our method is superior to other high-performance liquid chromatography methods, and a simple protocol will facilitate further research on the physiological role of Tamm-Horsfall protein. © The Author(s) 2015.

Highly Efficient Gluten Degradation by Lactobacilli and Fungal Proteases during Food Processing: New Perspectives for Celiac Disease▿

PubMed Central

Rizzello, Carlo G.; De Angelis, Maria; Di Cagno, Raffaella; Camarca, Alessandra; Silano, Marco; Losito, Ilario; De Vincenzi, Massimo; De Bari, Maria D.; Palmisano, Francesco; Maurano, Francesco; Gianfrani, Carmen; Gobbetti, Marco

2007-01-01

Presently, the only effective treatment for celiac disease is a life-long gluten-free diet. In this work, we used a new mixture of selected sourdough lactobacilli and fungal proteases to eliminate the toxicity of wheat flour during long-time fermentation. Immunological (R5 antibody-based sandwich and competitive enzyme-linked immunosorbent assay [ELISA] and R5 antibody-based Western blot), two-dimensional electrophoresis, and mass spectrometry (matrix-assisted laser desorption ionization-time of flight, strong-cation-exchange-liquid chromatography/capillary liquid chromatography-electrospray ionization-quadrupole-time of flight [SCX-LC/CapLC-ESI-Q-TOF], and high-pressure liquid chromatography-electrospray ionization-ion trap mass spectrometry) analyses were used to determine the gluten concentration. Assays based on the proliferation of peripheral blood mononuclear cells (PBMCs) and gamma interferon production by PBMCs and intestinal T-cell lines (iTCLs) from 12 celiac disease patients were used to determine the protein toxicity of the pepsin-trypsin digests from fermented wheat dough (sourdough). As determined by R5-based sandwich and competitive ELISAs, the residual concentration of gluten in sourdough was 12 ppm. Albumins, globulins, and gliadins were completely hydrolyzed, while ca. 20% of glutenins persisted. Low-molecular-weight epitopes were not detectable by SCX-LC/CapLC-ESI-Q-TOF mass spectrometry and R5-based Western blot analyses. The kinetics of the hydrolysis of the 33-mer by lactobacilli were highly efficient. All proteins extracted from sourdough activated PBMCs and induced gamma interferon production at levels comparable to the negative control. None of the iTCLs demonstrated immunoreactivity towards pepsin-trypsin digests. Bread making was standardized to show the suitability of the detoxified wheat flour. Food processing by selected sourdough lactobacilli and fungal proteases may be considered an efficient approach to eliminate gluten toxicity. PMID:17513580

Environmental proteomics: a paradigm shift in characterizing microbial activities at the molecular level.

PubMed

Keller, Martin; Hettich, Robert

2009-03-01

The increase in sequencing capacity led to a new wave of metagenomic projects, enabling and setting the prerequisite for the application of environmental proteomics technologies. This review describes the current status of environmental proteomics. It describes sample preparation as well as the two major technologies applied within this field: two-dimensional electrophoresis-based environmental proteomics and liquid chromatography-mass spectrometry-based environmental proteomics. It also highlights current publications and describes major scientific findings. The review closes with a discussion of critical improvements in the area of integrating experimental mass spectrometry technologies with bioinformatics as well as improved sample handling.

Chromatographic background drift correction coupled with parallel factor analysis to resolve coelution problems in three-dimensional chromatographic data: quantification of eleven antibiotics in tap water samples by high-performance liquid chromatography coupled with a diode array detector.

PubMed

Yu, Yong-Jie; Wu, Hai-Long; Fu, Hai-Yan; Zhao, Juan; Li, Yuan-Na; Li, Shu-Fang; Kang, Chao; Yu, Ru-Qin

2013-08-09

Chromatographic background drift correction has been an important field of research in chromatographic analysis. In the present work, orthogonal spectral space projection for background drift correction of three-dimensional chromatographic data was described in detail and combined with parallel factor analysis (PARAFAC) to resolve overlapped chromatographic peaks and obtain the second-order advantage. This strategy was verified by simulated chromatographic data and afforded significant improvement in quantitative results. Finally, this strategy was successfully utilized to quantify eleven antibiotics in tap water samples. Compared with the traditional methodology of introducing excessive factors for the PARAFAC model to eliminate the effect of background drift, clear improvement in the quantitative performance of PARAFAC was observed after background drift correction by orthogonal spectral space projection. Copyright © 2013 Elsevier B.V. All rights reserved.

MULTI-DIMENSIONAL MASS SPECTROMETRY-BASED SHOTGUN LIPIDOMICS AND NOVEL STRATEGIES FOR LIPIDOMIC ANALYSES

PubMed Central

Han, Xianlin; Yang, Kui; Gross, Richard W.

2011-01-01

Since our last comprehensive review on multi-dimensional mass spectrometry-based shotgun lipidomics (Mass Spectrom. Rev. 24 (2005), 367), many new developments in the field of lipidomics have occurred. These developments include new strategies and refinements for shotgun lipidomic approaches that use direct infusion, including novel fragmentation strategies, identification of multiple new informative dimensions for mass spectrometric interrogation, and the development of new bioinformatic approaches for enhanced identification and quantitation of the individual molecular constituents that comprise each cell’s lipidome. Concurrently, advances in liquid chromatography-based platforms and novel strategies for quantitative matrix-assisted laser desorption/ionization mass spectrometry for lipidomic analyses have been developed. Through the synergistic use of this repertoire of new mass spectrometric approaches, the power and scope of lipidomics has been greatly expanded to accelerate progress toward the comprehensive understanding of the pleiotropic roles of lipids in biological systems. PMID:21755525

Quantification of Quercetin and Rutin from Benincasa hispida Seeds and Carissa Congesta Roots by High-performance Thin Layer Chromatography and High-performance Liquid Chromatography.

PubMed

Doshi, Gaurav Mahesh; Une, Hemant Devidas

2016-01-01

In Indian Ayurvedic system, Benincasa hispida (BH) and Carissa congesta (CC) are well-known plants used for major and minor ailments. BH has been regarded as Kushmanda, whereas CC has been used in immune-related disorders of the human system. Quercetin and rutin identified from the vast plethora of plant extracts have proved to possess ethnopharmacological relevance. In present studies, we have determined quercetin and rutin in terms of percentage in BH seeds and CC roots by high-performance thin layer chromatography (HPTLC) and high-performance liquid chromatography (HPLC). After extraction and phytochemical screening, the extracts were subjected to quantification for the presence of quercetin and rutin by HPTLC and HPLC. HPTLC showed quercetin as 44.60, 27.13% and rutin as 32.00, 36.31% w/w, whereas HPLC revealed quercetin as 34.00, 35.00% and rutin as 21.99, 45.03% w/v in BH and CC extracts, respectively. The BH and CC extracts have elucidated peaks that were corresponding with standard peaks on undertaking chromatographic studies. Quercetin and rutin are isolated from BH seeds and CC roots by High Performance. Thin Layer Chromatography and High Performance Liquid Chromatography. HPTLC revealed presence of quercetin as 44.60, 27.13 % and rutin as 32.00, 36.31 % w/w. HPLC revealed presence of quercetin as 34.00, 35.00 % and rutin as 21.99, 45.03 % w/v. Abbreviation Used: HPTLC: High Performance Thin Layer Chromatography; HPLC: High Pressure Liquid Chromatography, UV: Ultraviolet, CC: Carissa congesta, BH: Benincasa hispida.

Analysis of lignans in Magnoliae Flos by turbulent flow chromatography with online solid-phase extraction and high-performance liquid chromatography with tandem mass spectrometry.

PubMed

Zhou, Xuan; Chen, Cen; Ye, Xiaolan; Song, Fenyun; Fan, Guorong; Wu, Fuhai

2016-04-01

In this study, a method coupling turbulent flow chromatography with online solid-phase extraction and high-performance liquid chromatography with tandem mass spectrometry was developed for analyzing the lignans in Magnoliae Flos. By the online pretreatment of turbulent flow chromatography solid-phase extraction, the impurities removal and analytes concentration were automatically processed, and the lignans were separated rapidly and well. Seven lignans of Magnoliae Flos including epieudesmin, magnolin, 1-irioresinol-B-dimethyl ether, epi-magnolin, fargesin aschantin, and demethoxyaschantin were identified by comparing their retention behavior, UV spectra, and mass spectra with those of reference substances or literature data. The developed method was validated, and the good results showed that the method was not only automatic and rapid, but also accurate and reliable. The turbulent flow chromatography with online solid-phase extraction and high-performance liquid chromatography with tandem mass spectrometry method holds a high potential to become an effective method for the quality control of lignans in Magnoliae Flos and a useful tool for the analysis of other complex mixtures. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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…

Enantioselective separation of racemic juvenile hormone III by normal-phase high-performance liquid chromatography and preparation of [(2)H(3)]juvenile hormone III as an internal standard for liquid chromatography-mass spectrometry quantification.

PubMed

Ichikawa, Akio; Ono, Hiroshi; Furuta, Kenjiro; Shiotsuki, Takahiro; Shinoda, Tetsuro

2007-08-17

Juvenile hormone III (JH III) racemate was prepared from methyl (2E,6E)-farnesoate via epoxidation with 3-chloroperbenzoic acid (mCPBA). Enantioselective separation of JH III was conducted using normal-phase high-performance liquid chromatography (HPLC) on a chiral stationary phase. [(2)H(3)]Methyl (2E,6E)-farnesoate was also prepared from (2E,6E)-farnesoic acid and [(2)H(4)]methanol (methanol-d(4)) using 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC) and 4-dimethylaminopyridine (DMAP); the conjugated double bond underwent isomerization to some degree. Epoxidation of [(2)H(3)]methyl (2E,6E)-farnesoate with mCPBA gave a novel deuterium-substituted internal standard [(2)H(3)]JH III (JH III-d(3)). The standard curve was produced by linear regression using the peak area ratios of JH III and JH III-d(3) in liquid chromatography-mass spectrometry (LC-MS).

Haemoglobin variants may cause significant differences in haemoglobin A1c as measured by high-performance liquid chromatography and enzymatic methods in diabetic patients: a cross-sectional study.

PubMed

Otabe, Shuichi; Nakayama, Hitomi; Ohki, Tsuyoshi; Soejima, Eri; Tajiri, Yuji; Yamada, Kentaro

2017-07-01

Background We aimed to determine whether the discrepancy between haemoglobin A1c values determined by high-performance liquid chromatography and enzymatic haemoglobin A1c measurements in diabetic patients was clinically relevant. Methods We randomly recruited 1421 outpatients undergoing diabetic treatment and follow-up who underwent at least three haemoglobin A1c measurements between April 2014 and March 2015 at our clinic. In 6369 samples, haemoglobin A1c was simultaneously measured by HA-8160 and MetaboLead (enzymatic assay), and the values were compared. Results haemoglobin A1c measurements by high-performance liquid chromatography and enzymatic assay were strongly correlated (correlation coefficient: 0.9828, linear approximation curve y = 0.9986x - 0.2507). Mean haemoglobin A1c (6.8 ± 1.0%) measured by high-performance liquid chromatography was significantly higher than that measured by enzymatic assay (6.5 ± 1.0%, P < 0.0001). During the sample processing, four (0.3%) subjects presented consistently lower haemoglobin A1c values (<0.7%) by high-performance liquid chromatography than those from enzymatic assay. Of these, three had Hb Toranomon [β112 (G14) Cys→Trp]. The fourth had Hb Ube-2 [α68 (E17) Asn→Asp]. One other subject presented consistently higher haemoglobin A1c values (>1%) by high-performance liquid chromatography than those from enzymatic assay and was diagnosed with a -77 (T > C) mutation in the δ-globin gene. These unrelated asymptomatic subjects had normal erythrocyte profiles, without anaemia. Conclusions We showed that haemoglobin A1c values measured by high-performance liquid chromatography were significantly higher than those measured by enzymatic assay in diabetic subjects. However, when an oversized deviation (>0.7%) between glycaemic control status and haemoglobin A1c is apparent, clinicians should check the methods used to measure haemoglobin A1c and consider the possible presence of a haemoglobin variant.

Simple high-performance liquid chromatography method for formaldehyde determination in human tissue through derivatization with 2,4-dinitrophenylhydrazine.

PubMed

Yilmaz, Bilal; Asci, Ali; Kucukoglu, Kaan; Albayrak, Mevlut

2016-08-01

A simple high-performance liquid chromatography method has been developed for the determination of formaldehyde in human tissue. FA Formaldehyde was derivatized with 2,4-dinitrophenylhydrazine. It was extracted from human tissue with ethyl acetate by liquid-liquid extraction and analyzed by high-performance liquid chromatography. The calibration curve was linear in the concentration range of 5.0-200 μg/mL. Intra- and interday precision values for formaldehyde in tissue were <6.9%, and accuracy (relative error) was better than 6.5%. The extraction recoveries of formaldehyde from human tissue were between 88 and 98%. The limits of detection and quantification of formaldehyde were 1.5 and 5.0 μg/mL, respectively. Also, this assay was applied to liver samples taken from a biopsy material. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Recent progress of task-specific ionic liquids in chiral resolution and extraction of biological samples and metal ions.

PubMed

Wu, Datong; Cai, Pengfei; Zhao, Xiaoyong; Kong, Yong; Pan, Yuanjiang

2018-01-01

Ionic liquids have been functionalized for modern applications. The functional ionic liquids are also called task-specific ionic liquids. Various task-specific ionic liquids with certain groups have been constructed and exploited widely in the field of separation. To take advantage of their properties in separation science, task-specific ionic liquids are generally used in techniques such as liquid-liquid extraction, solid-phase extraction, gas chromatography, high-performance liquid chromatography, and capillary electrophoresis. This review mainly covers original research papers published in the last five years, and we will focus on task-specific ionic liquids as the chiral selectors in chiral resolution and as extractant or sensor for biological samples and metal ion purification. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

An Efficient Protocol for Preparation of Gallic Acid from Terminalia bellirica (Gaertn.) Roxb by Combination of Macroporous Resin and Preparative High-Performance Liquid Chromatography.

PubMed

Zou, Denglang; Chen, Tao; Chen, Chen; Li, Hongmei; Liu, Yongling; Li, Yulin

2016-08-01

In this article, macroporous resin column chromatography and preparative high-performance liquid chromatography were applied for preparation of gallic acid from Terminalia bellirica (Gaertn.) Roxb. In the first step, six kinds of resins were investigated by adsorption and desorption tests and AB-8 macroporous resin was selected for the enrichment of gallic acid. As a result, 20 g of gallic acid at a purity of 71% could be separated from 100 g of crude extract in which the content of gallic acid was 16.7% and the recovery of gallic acid reached 85.0%. In the second step, preparative high-performance liquid chromatography was selected to purify gallic acid. As a result, 640 mg of gallic acid at a purity of 99.1% was obtained from 1 g of sample in 35 min. The results demonstrated that macroporous resin coupled with preparative high-performance liquid chromatography was suitable for preparation of gallic acid from T. bellirica (Gaertn.) Roxb. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

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

Evaluation of gas-liquid chromatography for the rapid diagnosis of Clostridium difficile associated disease.

PubMed Central

Gianfrilli, P; Pantosti, A; Luzzi, I

1985-01-01

Direct gas-liquid chromatography of faecal specimens with isocaproic acid as a marker was used for the rapid diagnosis of Clostridium difficile associated diarrhoeal diseases. Ninety stools were examined and results were compared with conventional culture on selective medium and cytotoxin assay in tissue culture. Using a combined analysis of isocaproic acid and butyric acid peak heights we defined three categories: positive, negative, and indeterminate. When the indeterminate group was excluded, the positive and negative predictive values of gas-liquid chromatography analysis were 86.9% and 85% respectively compared with culture and 71.4% and 95% respectively compared with cytotoxin assay. PMID:4008667

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.

Gas-liquid chromatography with a volatile "stationary" liquid phase.

PubMed

Wells, P S; Zhou, S; Parcher, J F

2002-05-01

A unique type of gas-liquid chromatography is described in which both mobile and "stationary" phases are composed of synthetic mixtures of helium and carbon dioxide. At temperatures below the critical point of the binary mixture and pressures above the vapor pressure of pure liquid carbon dioxide, helium and carbon dioxide can form two immiscible phases over extended composition ranges. A binary vapor phase enriched in helium can act as the mobile phase for chromatographic separations, whereas a CO2-rich liquid in equilibrium with the vapor phase, but condensed on the column wall, can act as a pseudostationary phase. Several examples of chromatographic separations obtained in "empty" capillary columns with no ordinary stationary liquid phase illustrate the range of conditions that produce such separations. In addition, several experiments are reported that confirm the proposed two-phase hypothesis. The possible consequences of the observed chromatographic phenomenon in the field of supercritical fluid chromatography with helium headspace carbon dioxide are discussed.

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...

Single Laboratory Validated Method for Determination of Cylindrospermopsin and Anatoxin-a in Ambient Freshwaters by Liquid Chromatography/Tandem Mass Spectrometry (LC/MS/MS)

EPA Pesticide Factsheets

This document is a standardized single laboratory validated liquid chromatography/tandem mass spectrometry (LC/MS/MS) method for the detection and quantification of cyanotoxins (combined intracellular and extracellular) in ambient freshwaters.

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)

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…

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...

Ionic Liquids in HPLC and CE: A Hope for Future.

PubMed

Ali, Imran; Suhail, Mohd; Sanagi, Mohd Marsin; Aboul-Enein, Hassan Y

2017-07-04

The ionic liquids (ILs) are salts with melting points below 100°C. These are called as ionic fluids, ionic melts, liquid electrolytes, fused salts, liquid salts, ionic glasses, designer solvents, green solvents and solvents of the future. These have a wide range of applications, including medical, pharmaceutical and chemical sciences. Nowadays, their use is increasing greatly in separation science, especially in chromatography and capillary electrophoresis due to their remarkable properties. The present article describes the importance of ILs in high-performance liquid chromatography and capillary electrophoresis. Efforts were also made to highlight the future expectations of ILs.

State-of-the art of selective detection and identification of I-, Br-, Cl-, and F-containing compounds in gas chromatography and liquid chromatography.

PubMed

Brede, Cato; Pedersen-Bjergaard, Stig

2004-09-24

This review article presents an overview of halogen-specific detection in gas chromatography (GC) and liquid chromatography (LC). Attention is primarily focused on the use of plasma emission spectroscopy and plasma mass spectrometry as detectors, but other halogen-selective detection principles are also mentioned. Different instrumental configurations are discussed both with respect to technical set-up and performance, the principal reasons for halogen-selective detection are highlighted, and recent applications are reviewed from areas such as environmental chemistry, petroleum characterization, and drug analysis.

Trends in Analytical Scale Separations.

ERIC Educational Resources Information Center

Jorgenson, James W.

1984-01-01

Discusses recent developments in the instrumentation and practice of analytical scale operations. Emphasizes detection devices and procedures in gas chromatography, liquid chromatography, electrophoresis, supercritical fluid chromatography, and field-flow fractionation. (JN)

Simultaneous determination of furfural and its degradation products, furoic acid and maleic acid, in transformer oil by the reversed-phase vortex-assisted liquid-liquid microextraction followed by high-performance liquid chromatography.

PubMed

Wang, Yifan; Li, Haiyan; Yang, Zhen; Zhang, Weijie; Hua, Jia

2017-12-01

To explore why the use of furfural as a transformer oil-paper insulation aging characteristic is problematic in real world application, we developed a method for the simultaneous determination of furfural, furoic acid, and maleic acid in transformer oil by reversed-phase vortex-assisted liquid-liquid microextraction combined with high-performance liquid chromatography. The conditions for the proposed method were optimized, and the obtained extract can be directly analyzed by high-performance liquid chromatography. The detection limits (signal-to-noise ratio = 3) of the method ranged from 1.0 to 4.6 μg/L, the enrichment factors for furfural, furoic acid, maleic acid, and fumaric acid were 4.6, 25.1, 15.6, and 17.5, respectively, and the recovery rates for three analytes (fumaric acid was undetected) range from 82.1 to 106.2%. The contents of furfural, furoic acid, and maleic acid resulted from accelerated aging of transformer insulation oil-paper were measured using the present method for the first time, and the aging samples were analyzed by liquid chromatography with mass spectrometry for the identification of furoic acid and maleic acid in the aging transformer oil samples. Using the optimal method, the target products of samples at different aging time were tracked and measured. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Direct probing of chromatography columns by laser-induced fluorescence

NASA Astrophysics Data System (ADS)

McGuffin, V. L.

1992-12-01

This report summarizes the progress and accomplishments of this research project from 1 Sep. 1989 to 28 Feb. 1993. During this period, we have accomplished all of the primary scientific objectives of the research proposal: (1) constructed and evaluated a laser-induced fluorescence detection system that allows direct examination of the chromatographic column, (2) examined nonequilibrium processes that occur upon solute injection and elution, (3) examined solute retention in liquid chromatography as a function of temperature and pressure, (4) examined solute zone dispersion in liquid chromatography as a function of temperature and pressure, and (5) developed appropriate theoretical models to describe these phenomena. In each of these studies, substantial knowledge has been gained of the fundamental processes that are responsible for chromatographic separations. In addition to these primary research objectives, we have made significant progress in three related areas: (1) examined pyrene as a fluorescent polarity probe in supercritical fluids and liquids as a function of temperature and pressure, (2) developed methods for the class-selective identification of polynuclear aromatic hydrocarbons in coal-derived fluids by microcolumn liquid chromatography with fluorescence quenching detection, and (3) developed methods for the determination of saturated and unsaturated (including omega-3) fatty acids in fish oil extracts by microcolumn liquid chromatography with laser-induced fluorescence detection. In these studies, the advanced separation and detection techniques developed in our laboratory are applied to practical problems of environmental and biomedical significance.

Comparison of pulse glow discharge-ion mobility spectrometry and liquid chromatography with tandem mass spectrometry based on multiplug filtration cleanup for the analysis of tricaine mesylate residues in fish and water.

PubMed

Zou, Nan; Chen, Ronghua; Qin, Yuhong; Song, Shuangyu; Tang, Xinglin; Pan, Canping

2016-09-01

Analytical methods based on multiplug filtration cleanup coupled with pulse glow discharge-ion mobility spectrometry and liquid chromatography tandem mass spectrometry were developed for the analysis of tricaine mesylate residue in fish and fish-raising water samples. A silica fiber holder and an appropriate new interface were designed to make the direct introduction of the fiber into the pulse glow discharge-ion mobility spectrometry introduction mechanism. The multiplug filtration cleanup method with adsorption mixtures was optimized for the determination of tricaine mesylate in fish samples. Good linear relationships were obtained by the two methods. For fish samples, limits of detection were 6 and 0.6 μg/kg by ion mobility spectrometry and liquid chromatography with tandem mass spectrometry, respectively. The matrix effect of the established liquid chromatography tandem mass spectrometry method was negligible for fish samples but that of the ion mobility spectrometry method was not. The two methods were compared. The ion mobility spectrometry system could be used a rapid screening tool on site with the advantage of rapidity, simplicity, and portability, and the liquid chromatography tandem mass spectrometry system could be used for validation in laboratory conditions with the advantage of lower limit of detection, stability, and precision. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Simulation of elution profiles in liquid chromatography - II: Investigation of injection volume overload under gradient elution conditions applied to second dimension separations in two-dimensional liquid chromatography.

PubMed

Stoll, Dwight R; Sajulga, Ray W; Voigt, Bryan N; Larson, Eli J; Jeong, Lena N; Rutan, Sarah C

2017-11-10

An important research direction in the continued development of two-dimensional liquid chromatography (2D-LC) is to improve the detection sensitivity of the method. This is especially important in applications where injection of large volumes of effluent from the first dimension ( 1 D) column into the second dimension ( 2 D) column leads to severe 2 D peak broadening and peak shape distortion. For example, this is common when coupling two reversed-phase columns and the organic solvent content of the 1 D mobile phase overwhelms the 2 D column with each injection of 1 D effluent, leading to low resolution in the second dimension. In a previous study we validated a simulation approach based on the Craig distribution model and adapted from the work of Czok and Guiochon [1] that enabled accurate simulation of simple isocratic and gradient separations with very small injection volumes, and isocratic separations with mismatched injection and mobile phase solvents [2]. In the present study we have extended this simulation approach to simulate separations relevant to 2D-LC. Specifically, we have focused on simulating 2 D separations where gradient elution conditions are used, there is mismatch between the sample solvent and the starting point in the gradient elution program, injection volumes approach or even exceed the dead volume of the 2 D column, and the extent of sample loop filling is varied. To validate this simulation we have compared results from simulations and experiments for 101 different conditions, including variation in injection volume (0.4-80μL), loop filling level (25-100%), and degree of mismatch between sample organic solvent and the starting point in the gradient elution program (-20 to +20% ACN). We find that that the simulation is accurate enough (median errors in retention time and peak width of -1.0 and -4.9%, without corrections for extra-column dispersion) to be useful in guiding optimization of 2D-LC separations. However, this requires that real injection profiles obtained from 2D-LC interface valves are used to simulate the introduction of samples into the 2 D column. These profiles are highly asymmetric - simulation using simple rectangular pulses leads to peak widths that are far too narrow under many conditions. We believe the simulation approach developed here will be useful for addressing practical questions in the development of 2D-LC methods. Copyright © 2017 Elsevier B.V. All rights reserved.

Electrochemical Detectors in HPLC and Ion Chromatography.

PubMed

Horvai, George; Pungor, ErnÕ

1989-01-01

Back in 1952, the renowned Polish electrochemist Wiktor Kemula introduced chromato-polarography, 1 i.e., polaro-graphic detection for liquid chromatography. This technique continued to develop slowly until the early 1970s (for a review see Reference 2) when modem high-performance liquid chromatography (HPLC) emerged. This new, highly efficient chromatographc method could only be. used with detectors ensuring low dispersion. It was not easy to modify the dropping mercury electrode cells to satisfy this requirement. However, at the same time, electroanalytical chemists, who already had much experience in using carbon-based electrodes for oxidative detection in flow analysis, put forward the idea of oxidative amperometric detection in liquid chromatography. 3,4 In this technique, solid or quasi-solid (paste) electrodes were used and this made possible the construction of miniaturized cells with just a few microliter volume.

Significant advancement of mass spectrometry imaging for food chemistry.

PubMed

Yoshimura, Yukihiro; Goto-Inoue, Naoko; Moriyama, Tatsuya; Zaima, Nobuhiro

2016-11-01

Food contains various compounds that have an impact on our daily lives. Many technologies have been established to analyze these molecules of interest in foods. However, the analysis of the spatial distribution of these compounds in foods using conventional technology, such as high-performance liquid chromatography-mass spectrometry or gas chromatography-mass spectrometry is difficult. Matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) is considered an ideal complementary approach. MALDI-MSI is a two-dimensional MALDI-MS technology that can detect compounds in a tissue section without extraction, purification, separation, or labeling. MALDI-MSI can be used to visualize the spatial distribution of chemical compounds or biomolecules in foods. Although the methodology of MALDI-MSI in food science is not yet fully established, the versatility of MALDI-MSI is expected to open a new frontier in food science. Herein, we describe the principles and applications of MALDI-MSI in food science and related fields. Copyright © 2016 Elsevier Ltd. All rights reserved.

Modelling the Maillard reaction during the cooking of a model cheese.

PubMed

Bertrand, Emmanuel; Meyer, Xuân-Mi; Machado-Maturana, Elizabeth; Berdagué, Jean-Louis; Kondjoyan, Alain

2015-10-01

During processing and storage of industrial processed cheese, odorous compounds are formed. Some of them are potentially unwanted for the flavour of the product. To reduce the appearance of these compounds, a methodological approach was employed. It consists of: (i) the identification of the key compounds or precursors responsible for the off-flavour observed, (ii) the monitoring of these markers during the heat treatments applied to the cheese medium, (iii) the establishment of an observable reaction scheme adapted from a literature survey to the compounds identified in the heated cheese medium (iv) the multi-responses stoichiokinetic modelling of these reaction markers. Systematic two-dimensional gas chromatography time-of-flight mass spectrometry was used for the semi-quantitation of trace compounds. Precursors were quantitated by high-performance liquid chromatography. The experimental data obtained were fitted to the model with 14 elementary linked reactions forming a multi-response observable reaction scheme. Copyright © 2015 Elsevier Ltd. All rights reserved.

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...

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...

EXTRACTION AND QUANTITATIVE ANALYSIS OF ELEMENTAL SULFUR FROM SULFIDE MINERAL SURFACES BY HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY. (R826189)

EPA Science Inventory

A simple method for the quantitative determination of elemental sulfur on oxidized sulfide minerals is described. Extraction of elemental sulfur in perchloroethylene and subsequent analysis with high-performance liquid chromatography were used to ascertain the total elemental ...

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…

The Determination of Pesticidal and Non-Pesticidal Organotin Compounds by in situ Ethylation and Capillary Gas Chromatography with Pulsed Flame Photometric Detection

EPA Science Inventory

The concurrent determination of pesticidal and non-pesticidal organotin compounds in several water matrices, using a simultaneous in situ ethylation and liquid-liquid extraction followed by splitless injection mode capillary gas chromatography with pulsed flame photometric detect...

(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...

Single Laboratory Validated Method for Determination of Microcystins and Nodularin in Ambient Freshwaters by Solid Phase Extraction and Liquid Chromatography/ Tandem Mass Spectrometry (LC/MS/MS)

EPA Pesticide Factsheets

This document is a standardized, single laboratory validated liquid chromatography/tandem mass spectrometry (LC/MS/MS) method for the detection of cyanotoxins—microsystins and nodularin (combined intracellular and extracellular)—in ambient freshwaters.

CHARACTERIZATION OF DANSYLATED CYSTEINE, GLUTATHIONE DISULFIDE, CYSTEINE AND CYSTINE BY NARROW BORE LIQUID CHROMATOGRAPHY/ELECTROSPRAY IONIZATION MASS SPECTROMETRY

EPA Science Inventory

A method using reversed phase high performance liquid chromatography/electrospray ionization-mass spectrometric (RP-LC/ESI-MS) method has been developed to confirm the identity of dansylated derivatives of cysteine and glutathione, and their respective dimers. Cysteine, GSH, CSSC...

Simultaneous determination of estrogens and progestogens in honey using high performance liquid chromatography-tandem mass spectrometry

USDA-ARS?s Scientific Manuscript database

This work describes the development and validation of a method for the simultaneous determination of 13 estrogens and progestogens in honey by high performance liquid chromatography-tandem mass spectrometry. The target compounds were preconcentrated by solid phase extraction. Pretreatment variables ...

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…

EPA CRL MS014: Analysis of Aldicarb, Bromadiolone, Carbofuran, Oxamyl and Methomyl in Water by Multiple Reaction Monitoring Liquid Chromatography / Tandem Mass Spectrometry (LC/MS/MS)

EPA Pesticide Factsheets

Method MS014 describes procedures for solvent extraction of aldicarb, bromadiolone, carbofuran, oxamyl and methomyl from water samples, followed by analysis using liquid chromatography tandem mass spectrometry (LC-MS-MS).

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…

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…

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)

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...

Characterization of phenolic amides from cortex lycii by ultra high-performance liquid chromatography coupled with LTQ-Orbitrap mass spectrometry

USDA-ARS?s Scientific Manuscript database

High performance liquid chromatography (UPLC) and flow injection electrospray ionization with ion trap mass spectrometry (FIMS) fingerprints combined with the principal component analysis (PCA) were examined for their potential in differentiating commercial organic and conventional sage samples. The...

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)

78 FR 11126 - Receipt of Several Pesticide Petitions Filed for Residues of Pesticide Chemicals in or on Various...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-02-15

... using capillary gas liquid chromatography (GLC) with flame ionization detector (FID). Contact: Andrew...) purification. Detection and quantitation are conducted by gas chromatograph equipped with nitrogen phosphorus... pressure liquid chromatography/triple stage quadrupole mass spectrometry (LC/MS/MS) using the stable...

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

Three-dimensional desirability spaces for quality-by-design-based HPLC development.

PubMed

Mokhtar, Hatem I; Abdel-Salam, Randa A; Hadad, Ghada M

2015-04-01

In this study, three-dimensional desirability spaces were introduced as a graphical representation method of design space. This was illustrated in the context of application of quality-by-design concepts on development of a stability indicating gradient reversed-phase high-performance liquid chromatography method for the determination of vinpocetine and α-tocopheryl acetate in a capsule dosage form. A mechanistic retention model to optimize gradient time, initial organic solvent concentration and ternary solvent ratio was constructed for each compound from six experimental runs. Then, desirability function of each optimized criterion and subsequently the global desirability function were calculated throughout the knowledge space. The three-dimensional desirability spaces were plotted as zones exceeding a threshold value of desirability index in space defined by the three optimized method parameters. Probabilistic mapping of desirability index aided selection of design space within the potential desirability subspaces. Three-dimensional desirability spaces offered better visualization and potential design spaces for the method as a function of three method parameters with ability to assign priorities to this critical quality as compared with the corresponding resolution spaces. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

High Performance Thin Layer Chromatography.

ERIC Educational Resources Information Center

Costanzo, Samuel J.

1984-01-01

Clarifies where in the scheme of modern chromatography high performance thin layer chromatography (TLC) fits and why in some situations it is a viable alternative to gas and high performance liquid chromatography. New TLC plates, sample applications, plate development, and instrumental techniques are considered. (JN)

Quantification of Quercetin and Rutin from Benincasa hispida Seeds and Carissa Congesta Roots by High-performance Thin Layer Chromatography and High-performance Liquid Chromatography

PubMed Central

Doshi, Gaurav Mahesh; Une, Hemant Devidas

2016-01-01

Objective: In Indian Ayurvedic system, Benincasa hispida (BH) and Carissa congesta (CC) are well-known plants used for major and minor ailments. BH has been regarded as Kushmanda, whereas CC has been used in immune-related disorders of the human system. Quercetin and rutin identified from the vast plethora of plant extracts have proved to possess ethnopharmacological relevance. Materials and Methods: In present studies, we have determined quercetin and rutin in terms of percentage in BH seeds and CC roots by high-performance thin layer chromatography (HPTLC) and high-performance liquid chromatography (HPLC). After extraction and phytochemical screening, the extracts were subjected to quantification for the presence of quercetin and rutin by HPTLC and HPLC. Results: HPTLC showed quercetin as 44.60, 27.13% and rutin as 32.00, 36.31% w/w, whereas HPLC revealed quercetin as 34.00, 35.00% and rutin as 21.99, 45.03% w/v in BH and CC extracts, respectively. Conclusion: The BH and CC extracts have elucidated peaks that were corresponding with standard peaks on undertaking chromatographic studies. SUMMARY Quercetin and rutin are isolated from BH seeds and CC roots by High Performance. Thin Layer Chromatography and High Performance Liquid Chromatography. HPTLC revealed presence of quercetin as 44.60, 27.13 % and rutin as 32.00, 36.31 % w/w. HPLC revealed presence of quercetin as 34.00, 35.00 % and rutin as 21.99, 45.03 % w/v. Abbreviation Used: HPTLC: High Performance Thin Layer Chromatography; HPLC: High Pressure Liquid Chromatography, UV: Ultraviolet, CC: Carissa congesta, BH: Benincasa hispida PMID:26941534

A Simple and Universal Gel Permeation Chromatography Technique for Precise Molecular Weight Characterization of Well-Defined Poly(ionic liquid)s

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

He, Hongkun; Zhong, Mingjiang; Adzima, Brian

2013-03-20

Poly(ionic liquid)s (PILs) are an important class of technologically relevant materials. However, characterization of well-defined polyionic materials remains a challenge. Herein, we have developed a simple and versatile gel permeation chromatography (GPC) methodology for molecular weight (MW) characterization of PILs with a variety of anions. PILs with narrow MW distributions were synthesized via atom transfer radical polymerization, and the MWs obtained from GPC were further confirmed via nuclear magnetic resonance end group analysis.

Update of on-line coupled liquid chromatography - gas chromatography for the analysis of mineral oil hydrocarbons in foods and cosmetics.

PubMed

Biedermann, Maurus; Munoz, Celine; Grob, Koni

2017-10-27

On-line coupled high performance liquid chromatography-gas chromatography-flame ionization detection (HPLC-GC-FID) is the most widely used method for the analysis of mineral oil hydrocarbons in food, food contact materials, tissues and cosmetics. With comprehensive two-dimensional gas chromatography (GCxGC), a tool became available for better establishing the elution sequence of the various types of hydrocarbons from the HPLC column used for isolating the mineral oil saturated hydrocarbons (MOSH) and mineral oil aromatic hydrocarbons (MOAH). The performance of a heavily used HPLC column with reduced retention for MOAH was investigated to improve the robustness of the method. Updates are recommended that render the MOSH/MOAH separation less dependent of the state of the HPLC column and more correct in cases of highly refined mineral oil products of high molecular mass. Cyclohexyl cyclohexane (Cycy), used as internal standard, turned out to be eluted slightly after cholestane (Cho); apparently the size exclusion effect predominates the extra retention by ring number on the 60Å pore size silica gel. Hence, Cycy can be used to determine the end of the MOSH fraction. Long chain alkyl benzenes were eluted earlier than tri-tert. butyl benzene (Tbb). It is proposed to start the MOAH transfer immediately after the MOSH fraction and use a gradient causing breakthrough of dichloromethane (visible in the UV chromatogram) at a time suitable to elute perylene (Per) at the end of the fraction. In this way, a decrease in retention power of the HPLC column can be tolerated without adjustment of the MOAH fraction until some MOAH start being eluted into the MOSH fraction. This critical point can be checked either with di(2-ethylhexyl) benzene (DEHB) as a marker or the HPLC-UV chromatogram. Finally, based on new findings in rats and human tissues, it is recommended to integrate the MOSH and MOAH up to the retention time of the n-alkane C40. Copyright © 2017 Elsevier B.V. All rights reserved.

Simulating Gas-Liquid-Water Partitioning and Fluid Properties of Petroleum under Pressure: Implications for Deep-Sea Blowouts.

PubMed

Gros, Jonas; Reddy, Christopher M; Nelson, Robert K; Socolofsky, Scott A; Arey, J Samuel

2016-07-19

With the expansion of offshore petroleum extraction, validated models are needed to simulate the behaviors of petroleum compounds released in deep (>100 m) waters. We present a thermodynamic model of the densities, viscosities, and gas-liquid-water partitioning of petroleum mixtures with varying pressure, temperature, and composition based on the Peng-Robinson equation-of-state and the modified Henry's law (Krychevsky-Kasarnovsky equation). The model is applied to Macondo reservoir fluid released during the Deepwater Horizon disaster, represented with 279-280 pseudocomponents, including 131-132 individual compounds. We define >n-C8 pseudocomponents based on comprehensive two-dimensional gas chromatography (GC × GC) measurements, which enable the modeling of aqueous partitioning for n-C8 to n-C26 fractions not quantified individually. Thermodynamic model predictions are tested against available laboratory data on petroleum liquid densities, gas/liquid volume fractions, and liquid viscosities. We find that the emitted petroleum mixture was ∼29-44% gas and ∼56-71% liquid, after cooling to local conditions near the broken Macondo riser stub (∼153 atm and 4.3 °C). High pressure conditions dramatically favor the aqueous dissolution of C1-C4 hydrocarbons and also influence the buoyancies of bubbles and droplets. Additionally, the simulated densities of emitted petroleum fluids affect previous estimates of the volumetric flow rate of dead oil from the emission source.

Traceability and Quality Control in Traditional Chinese Medicine: From Chemical Fingerprint to Two-Dimensional Barcode

PubMed Central

Cai, Yong; Li, Xiwen; Li, Mei; Chen, Xiaojia; Ni, Jingyun; Wang, Yitao

2015-01-01

Chemical fingerprinting is currently a widely used tool that enables rapid and accurate quality evaluation of Traditional Chinese Medicine (TCM). However, chemical fingerprints are not amenable to information storage, recognition, and retrieval, which limit their use in Chinese medicine traceability. In this study, samples of three kinds of Chinese medicines were randomly selected and chemical fingerprints were then constructed by using high performance liquid chromatography. Based on chemical data, the process of converting the TCM chemical fingerprint into two-dimensional code is presented; preprocess and filtering algorithm are also proposed aiming at standardizing the large amount of original raw data. In order to know which type of two-dimensional code (2D) is suitable for storing data of chemical fingerprints, current popular types of 2D codes are analyzed and compared. Results show that QR Code is suitable for recording the TCM chemical fingerprint. The fingerprint information of TCM can be converted into data format that can be stored as 2D code for traceability and quality control. PMID:26089936

Stability behaviour of antiretroviral drugs and their combinations. 5: Characterization of novel degradation products of abacavir sulfate by mass and nuclear magnetic resonance spectrometry.

PubMed

Kurmi, Moolchand; Sahu, Archana; Singh, Saranjit

2017-02-05

In the present study, degradation behaviour of abacavir sulfate was evaluated in solution and solid stress conditions. Solution state studies resulted in formation of eleven degradation products; of which two were also formed on solid stress. The same were separated by high performance liquid chromatography. They were characterized using liquid chromatography-high resolution mass spectrometry, liquid chromatography-multistage mass spectrometry and hydrogen/deuterium exchange mass spectrometry data. Additionally, seven degradation products were isolated and subjected to 1D and 2D nuclear magnetic resonance studies for their structural confirmation. Copyright © 2016 Elsevier B.V. All rights reserved.

21 CFR 177.1990 - Vinylidene chloride/methyl acrylate copolymers.

Code of Federal Regulations, 2013 CFR

2013-04-01

... in Saran MA/VDC Resins and Pellets by Headspace Gas Chromatography,” dated March 3, 1986, which are... gel permeation chromatography using tetrahydrofuran as the solvent. The gel permeation chromatograph... Distribution of Polystyrene by Liquid Exclusion Chromatography (Gel Permeation Chromatography-GPC),” which is...

21 CFR 177.1990 - Vinylidene chloride/methyl acrylate copolymers.

Code of Federal Regulations, 2012 CFR

2012-04-01

... in Saran MA/VDC Resins and Pellets by Headspace Gas Chromatography,” dated March 3, 1986, which are... gel permeation chromatography using tetrahydrofuran as the solvent. The gel permeation chromatograph... Distribution of Polystyrene by Liquid Exclusion Chromatography (Gel Permeation Chromatography-GPC),” which is...

21 CFR 177.1990 - Vinylidene chloride/methyl acrylate copolymers.

Code of Federal Regulations, 2010 CFR

2010-04-01

... in Saran MA/VDC Resins and Pellets by Headspace Gas Chromatography,” dated March 3, 1986, which are... gel permeation chromatography using tetrahydrofuran as the solvent. The gel permeation chromatograph... Distribution of Polystyrene by Liquid Exclusion Chromatography (Gel Permeation Chromatography-GPC),” which is...

21 CFR 177.1990 - Vinylidene chloride/methyl acrylate copolymers.

Code of Federal Regulations, 2011 CFR

2011-04-01

... in Saran MA/VDC Resins and Pellets by Headspace Gas Chromatography,” dated March 3, 1986, which are... gel permeation chromatography using tetrahydrofuran as the solvent. The gel permeation chromatograph... Distribution of Polystyrene by Liquid Exclusion Chromatography (Gel Permeation Chromatography-GPC),” which is...

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. Copyright © 2015 Elsevier B.V. All rights reserved.

[Separation and identification of bovine lactoferricin by high performance liquid chromatography-matrix-assisted laser desorption/ionization time of flight/ time of flight mass spectrometry].

PubMed

An, Meichen; Liu, Ning

2010-02-01

A high performance liquid chromatography-matrix-assisted laser desorption/ionization time of flight/time of flight mass spectrometry (HPLC-MALDI-TOF/TOF MS) method was developed for the separation and identification of bovine lactoferricin (LfcinB). Bovine lactoferrin was hydrolyzed by pepsin and then separated by ion exchange chromatography and reversed-phase liquid chromatography (RP-LC). The antibacterial activities of the fractions from RP-LC separation were determined and the protein concentration of the fraction with the highest activity was measured, whose sequence was indentified by MALDI-TOF/TOF MS. The relative molecular mass of LfcinB was 3 124.89 and the protein concentration was 18.20 microg/mL. The method of producing LfcinB proposed in this study has fast speed, high accuracy and high resolution.

Preparative isolation and purification of chemical constituents from the root of Adenophora tetraphlla by high-speed counter-current chromatography with evaporative light scattering detection.

PubMed

Yao, Shun; Liu, Renming; Huang, Xuefeng; Kong, Lingyi

2007-01-19

Preparative high-speed counter-current chromatography (HSCCC), as a continuous liquid-liquid partition chromatography with no solid support matrix, combined with evaporative light scattering detection (ELSD) was employed for systematic separation and purification of non-chromophoric chemical components from Chinese medicinal herb Adenophora tetraphlla (Thunb.), Fisch. Nine compounds, including alpha-spinasterol, beta-sitosterol, nonacosan-10-ol, 24-methylene cycloartanol, lupenone, 3-O-palmitoyl-beta-sitosterol, 3-O-beta-d-glucose-beta-sitosterol, eicosanoic acid and an unknown compound, were obtained. The compounds were all above 95% determined by high-performance liquid chromatography (HPLC)-ELSD, and their structures were identified by (1)H NMR and chemical ionization mass spectroscopy (CI-MS). The results demonstrate that HSCCC coupled with ELSD is a feasible and efficient technique for systematic isolation of non-chromophoric components from traditional medicinal herbs.

Rapid pretreatment and determination of bisphenol A in water samples based on vortex-assisted liquid-liquid microextraction followed by high-performance liquid chromatography with fluorescence detection.

PubMed

Yang, Xiao; Diao, Chun-Peng; Sun, Ai-Ling; Liu, Ren-Min

2014-10-01

A method for the rapid pretreatment and determination of bisphenol A in water samples based on vortex-assisted liquid-liquid microextraction followed by high-performance liquid chromatography with fluorescence detection was proposed in this paper. A simple apparatus consisting of a test tube and a cut-glass dropper was designed and applied to collect the floating extraction drop in liquid-liquid microextraction when low-density organic solvent was used as the extraction solvent. Solidification and melting steps that were tedious but necessary once the low-density organic solvent used as extraction solvent could be avoided by using this apparatus. Bisphenol A was selected as model pollutant and vortex-assisted liquid-liquid microextraction was employed to investigate the usefulness of the apparatus. High-performance liquid chromatography with fluorescence detection was selected as the analytical tool for the detection of bisphenol A. The linear dynamic range was from 0.10 to 100 μg/L for bisphenol A, with good squared regression coefficient (r(2) = 0.9990). The relative standard deviation (n = 7) was 4.7% and the limit of detection was 0.02 μg/L. The proposed method had been applied to the determination of bisphenol A in natural water samples and was shown to be economical, fast, and convenient. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Liquid Chromatography-Mass Spectrometry-based Quantitative Proteomics

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

Xie, Fang; Liu, Tao; Qian, Weijun

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.

Ultra-Trace Analysis of Nine Macrolides, including Tulathromycin A (Draxxin), in Edible Animal Tissues with Mini-Column Liquid Chromatography Tandem Mass Spectrometry

USDA-ARS?s Scientific Manuscript database

Analysis of 9 macrolides is presented, including tulathromycin A (Draxxin), in beef, poultry and pork muscle with a simple multi-residue extraction and analysis method using high performance liquid chromatography coupled to electrospray ionization tandem mass spectrometry. The extraction method inv...

Classification of cultivation locations of Panax quinquefolius L samples using high performance liquid chromatography-electrospray ionization mass spectrometry and chemometric analysis

USDA-ARS?s Scientific Manuscript database

Panax quinquefolius L (P. quinquefolius L) samples grown in the United States and China were analyzed with high performance liquid chromatography-mass spectrometry (HPLC—MS). Prior to classification, the two-way datasets were subjected to pretreatment including baseline correction and retention tim...

Classification of cultivation locations of panax quinquefolius L samples using high performance liquid chromatography-electrospray ionization mass spectrometry and chemometric analysis

USDA-ARS?s Scientific Manuscript database

Panax quinquefolius L (P. quinquefolius L) samples grown in the United States and China were analyzed with high performance liquid chromatography-mass spectrometry (HPLC—MS). Prior to classification, the two-way datasets were subjected to pretreatment including baseline correction and retention ti...

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…

MEASUREMENT OF HIGH-MOLECULAR-WEIGHT POLYCYCLIC AROMATIC HYDROCARBONS IN SOILS BY PARTICLE BEAM HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY-MASS SPECTROMETRY

EPA Science Inventory

Polycyclic aromatic hydrocarbons (PAHs) comprise a class of potentially hazardous compounds of concern to the U.S.EPA. The application of particle-beam (PB) liquid chromatography-mass spectrometry (LC-MS) to the measurement of high-molecular-weight PAHs was investigated. Instrume...

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…

Determination of citrus limonoid glucosides by high performance liquid chromatography coupled to post-column reaction with Ehrlich’s Reagent

USDA-ARS?s Scientific Manuscript database

A method for the identification and quantification of citrus limonoid glucosides in juices based upon high performance liquid chromatography (HPLC) separation coupled to post-column reaction with Ehrlichs’s reagent has been developed. This method utilizes a phenyl stationary phase and an isocratic ...

Matrix effects break the LC behavior rule for analytes in LC-MS/MS analysis of biological samples

USDA-ARS?s Scientific Manuscript database

High-performance liquid chromatography (HPLC) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) are generally accepted as the preferred techniques for detecting and quantitating analytes of interest in biological matrices on the basis of the rule that one chemical compound yields one LC-...

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)

Constructing a LabVIEW-Controlled High-Performance Liquid Chromatography (HPLC) System: An Undergraduate Instrumental Methods Exercise

ERIC Educational Resources Information Center

Smith, Eugene T.; Hill, Marc

2011-01-01

In this laboratory exercise, students develop a LabVIEW-controlled high-performance liquid chromatography system utilizing a data acquisition device, two pumps, a detector, and fraction collector. The programming experience involves a variety of methods for interface communication, including serial control, analog-to-digital conversion, and…

Using reversed phase high performance liquid chromatography to study the complexation of anthocyanins with β-cyclodextrin

NASA Astrophysics Data System (ADS)

Deineka, V. I.; Lapshova, M. S.; Deineka, L. A.

2014-06-01

It is shown by means of reversed phase high performance liquid chromatography (RP HPLC) with mobile phases containing additions of β-cyclodextrin that 5-glucosides of cyanidin and pelargonidin form stronger inclusion complexes than 3-glucosides; this is explained by the steric interference of the glucoside radical.

The Determination of Pesticidal and Non-Pesticidal Organotin Compounds in Water Matrices by in situ Ethylation and Gas Chromatography with Pulsed Flame Photometric Detection

EPA Science Inventory

The concurrent determination of pesticidal and non-pesticidal organotin compounds in several water matrices, using a simultaneous in situ ethylation and liquid-liquid extraction followed by splitless injection mode capillary gas chromatography with pulsed flame photometric detect...

Simultaneous Determination of Perfluorinated Compounds in Edible Oil by Gel-Permeation Chromatography Combined with Dispersive Solid-Phase Extraction and Liquid Chromatography-Tandem Mass Spectrometry.

PubMed

Yang, Lili; Jin, Fen; Zhang, Peng; Zhang, Yanxin; Wang, Jian; Shao, Hua; Jin, Maojun; Wang, Shanshan; Zheng, Lufei; Wang, Jing

2015-09-30

A simple analytical method was developed for the simultaneous analysis of 18 perfluorinated compounds (PFCs) in edible oil. The target compounds were extracted by acetonitrile, purified by gel permeation chromatography (GPC) and dispersive solid-phase extraction (DSPE) using graphitized carbon black (GCB) and octadecyl (C18), and analyzed by liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ES-MS/MS) in negative ion mode. Recovery studies were performed at three fortification levels. The average recoveries of all target PFCs ranged from 60 to 129%, with an acceptable relative standard deviation (RSD) (1-20%, n = 3). The method detection limits (MDLs) ranged from 0.004 to 0.4 μg/kg, which was significantly improved compared with the existing liquid-liquid extraction and cleanup method. The method was successfully applied for the analysis of all target PFCs in edible oil samples collected from markets in Beijing, China, and the results revealed that C6-C10 perfluorocarboxylic acid (PFCAs) and C7 perfluorosulfonic acid PFSAs were the major PFCs detected in oil samples.

Determination and removal of antibiotics in secondary effluent using a horizontal subsurface flow constructed wetland.

PubMed

Zhang, Chunhui; Ning, Ke; Zhang, Wenwen; Guo, Yuanjie; Chen, Jun; Liang, Chen

2013-04-01

Increased attention is currently being directed towards the potential negative effects of antibiotics and other PPCPs discharged into the aquatic environment via municipal WWTP secondary effluents. A number of analytical methods, such as high performance liquid chromatography technologies, including a high performance liquid chromatography-fluorescence method (HPLC-FLD), high performance liquid chromatography-UV detection method (HPLC-UV) and high performance liquid chromatography-mass spectrometry method (HPLC-MS), have been suggested as determination technologies for antibiotic residues in water. In this study, we implement a HPLC-MS/MS combined method to detect and analyze antibiotics in WWTP secondary effluent and apply a horizontal subsurface flow constructed wetland (CW) as an advanced wastewater treatment for removing antibiotics in the WWTP secondary effluent. The results show that there were 2 macrolides, 2 quinolones and 5 sulfas in WWTP secondary effluent among all the 22 antibiotics considered. After the CW advanced treatment, the concentration removal efficiencies and removal loads of 9 antibiotics were 53-100% and 0.004-0.7307 μg m(-2) per day, respectively.

Identification, characterization, and high-performance liquid chromatography quantification of process-related impurities in vonoprazan fumarate.

PubMed

Liu, Lei; Cao, Na; Ma, Xingling; Xiong, Kaihe; Sun, Lili; Zou, Qiaogen

2016-04-01

High-performance liquid chromatography analysis of vonoprazan fumarate, a novel proton pump inhibitor drug revealed six impurities. These were identified by liquid chromatography with mass spectrometry. Further, the structures of the impurities were confirmed by synthesis followed by characterization by mass spectrometry, NMR spectroscopy, and infrared spectroscopy. On the basis of these data and knowledge of the synthetic scheme of vonoprazan fumarate, the previously unknown impurity was identified as 1-[5-(2-fluorophenyl)-1-(pyridin-3-ylsulfonyl)-1H-pyrrol-3-yl]-N-methyldimethylamine, which is a new compound. The possible mechanisms by which these impurities were formed were also discussed. A high-performance liquid chromatography method was optimized in order to separate, selectively detect, and quantify all process-related impurities of vonoprazan fumarate. The presented method has been validated in terms of linearity, limits of detection, and quantification, and response factors and, therefore, is highly suitable for routine analysis of vonoprazan fumarate related substances as well as stability studies. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Major and Modified Nucleosides, RNA, and DNA

NASA Astrophysics Data System (ADS)

Gehrke, Charles W.; Kuo, Kenneth C.

Most analytical chemists are well aware of the rapid rate of development of high-performance liquid chromatography (HPLC) over the past 5 years. A number of articles have been published in Analytical Chemistry on different topics in HPLC and many papers appear in the chromatographic journals. Some books also have been published covering this subject. HPLC has proved to be a very effective, broadly applicable chromatographic method for the separation and analysis of complex molecules in fields as diverse as biochemistry and environmental, pharmaceutical, medical, and polymer chemistry. HPLC is now having a major impact on the clinical and research aspects of medical biochemistry. Although the contributions of HPLC to other disciplines generally complements gas-liquid chromatography, this method is destined to play a much greater role in medical and biochemical research. This is because many of the biomolecules, owing to their molecular complexity and size, are thermally unstable or nonvolatile, preventing or complicating an analysis by GC. A major factor contributing to the powerful advances in biomedical liquid chromatography is the development of reversed-phase high-performance liquid chromatography (RP-HPLC) using n-alkyl and phenyl chemically bonded substrates.

Characterization of the efficiency of microbore liquid chromatography columns by van Deemter and kinetic plot analysis.

PubMed

Hetzel, Terence; Loeker, Denise; Teutenberg, Thorsten; Schmidt, Torsten C

2016-10-01

The efficiency of miniaturized liquid chromatography columns with inner diameters between 200 and 300 μm has been investigated using a dedicated micro-liquid chromatography system. Fully porous, core-shell and monolithic commercially available stationary phases were compared applying van Deemter and kinetic plot analysis. The sub-2 μm fully porous as well as the 2.7 μm core-shell particle packed columns showed superior efficiency and similar values for the minimum reduced plate heights (2.56-2.69) before correction for extra-column contribution compared to normal-bore columns. Moreover, the influence of extra-column contribution was investigated to demonstrate the difference between apparent and intrinsic efficiency by replacing the column by a zero dead volume union to determine the band spreading caused by the system. It was demonstrated that 72% of the intrinsic efficiency could be reached. The results of the kinetic plot analysis indicate the superior performance of the sub-2 μm fully porous particle packed column for ultra-fast liquid chromatography. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Determination of Grayanotoxins from Rhododendron brachycarpum in Dietary Supplements and Homemade Wine by Liquid Chromatography-Quadrupole Time-of-Flight-Mass Spectrometry and Liquid Chromatography-Tandem Mass Spectrometry.

PubMed

Hwang, Taeik; Noh, Eunyoung; Jeong, Ji Hye; Park, Sung-Kwan; Shin, Dongwoo; Kang, Hoil

2018-02-28

A sensitive and specific high-performance liquid chromatography-quadrupole time-of-flight-mass spectrometry (LC-QTOF-MS) method combined with liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed for the determination of grayanotoxins I and III in dietary supplements and homemade wine. Grayanotoxins I and III were successfully extracted using solid-phase extraction cartridges, characterized by LC-QTOF-MS, and quantitated by LC-MS/MS. The LC-MS/MS calibration curves were linear over concentrations of 10-100 ng/mL (grayanotoxin I) and 20-400 ng/mL (grayanotoxin III). Grayanotoxins I and III were found in 51 foodstuffs, with quantitative determinations revealing total toxin concentrations of 18.4-101 000 ng/mL (grayanotoxin I) and 15.3-56 000 ng/mL (grayanotoxin III). The potential of the validated method was demonstrated by successful quantitative analysis of grayanotoxins I and III in dietary supplements and homemade wine; the method appears suitable for the routine detection of grayanotoxins I and III from Rhododendron brachycarpum.

Self-assembled cyclodextrin-modified gold nanoparticles on silica beads as stationary phase for chiral liquid chromatography and hydrophilic interaction chromatography.

PubMed

Li, Yuanyuan; Wei, Manman; Chen, Tong; Zhu, Nan; Ma, Yulong

2016-11-01

A facile strategy based on self-assembly of Au nanoparticles (AuNPs) (60±10nm in size) on the surfaces of amino-functionalized porous silica spheres under mild conditions was proposed. The resulting material possessed a core-shell structure in which AuNPs were the shell and silica spheres were the core. Then, thiolated-β-cyclodextrin (SH-β-CD) was covalently attached onto the AuNPs as chiral selector for the enantioseparation. The resultant packing material was evaluated by high-performance liquid chromatography (HPLC). The separations of nine pairs of enantiomers were achieved by using the new chiral stationary phase (CSP) in the reversed-phase liquid chromatography (RPLC) mode, respectively. The results showed the new CSP have more sufficient interaction with the analytes due to the existence of AuNPs on silica surfaces, resulting in faster mass transfer rate, compared with β-CD modified silica column. The result shed light on potential usage of chemical modified NPs as chiral selector for enantioseparation based on HPLC. In addition, the new phase was also used in hydrophilic interaction liquid chromatography (HILIC) to separate polar compounds and highly hydrophilic compounds. Copyright © 2016 Elsevier B.V. All rights reserved.

Dispersive liquid-liquid microextraction based on solidification of floating organic droplet followed by high-performance liquid chromatography with ultraviolet detection and liquid chromatography-tandem mass spectrometry for the determination of triclosan and 2,4-dichlorophenol in water samples.

PubMed

Zheng, Cao; Zhao, Jing; Bao, Peng; Gao, Jin; He, Jin

2011-06-24

A novel, simple and efficient dispersive liquid-liquid microextraction based on solidification of floating organic droplet (DLLME-SFO) technique coupled with high-performance liquid chromatography with ultraviolet detection (HPLC-UV) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed for the determination of triclosan and its degradation product 2,4-dichlorophenol in real water samples. The extraction solvent used in this work is of low density, low volatility, low toxicity and proper melting point around room temperature. The extractant droplets can be collected easily by solidifying it at a lower temperature. Parameters that affect the extraction efficiency, including type and volume of extraction solvent and dispersive solvent, salt effect, pH and extraction time, were investigated and optimized in a 5 mL sample system by HPLC-UV. Under the optimum conditions (extraction solvent: 12 μL of 1-dodecanol; dispersive solvent: 300 of μL acetonitrile; sample pH: 6.0; extraction time: 1 min), the limits of detection (LODs) of the pretreatment method combined with LC-MS/MS were in the range of 0.002-0.02 μg L(-1) which are lower than or comparable with other reported approaches applied to the determination of the same compounds. Wide linearities, good precisions and satisfactory relative recoveries were also obtained. The proposed technique was successfully applied to determine triclosan and 2,4-dichlorophenol in real water samples. Copyright © 2011 Elsevier B.V. All rights reserved.

Coupling nanoliter high-performance liquid chromatography to inductively coupled plasma mass spectrometry for arsenic speciation.

PubMed

Cheng, Heyong; Shen, Lihuan; Liu, Jinhua; Xu, Zigang; Wang, Yuanchao

2018-04-01

Nanoliter high-performance liquid chromatography shows low consumption of solvents and samples, offering one of the best choices for arsenic speciation in precious samples in combination with inuctively coupled plasma mass spectrometry. A systematic investigation on coupling nanoliter high-performance liquid chromatography to inductively coupled plasma mass spectrometry from instrument design to injected sample volume and mobile phase was performed in this study. Nanoflow mobile phase was delivered by flow splitting using a conventional high-pressure pump with reuse of mobile phase waste. Dead volume was minimized to 60 nL for the sheathless interface based on the previously developed nanonebulizer. Capillary columns for nanoliter high-performance liquid chromatography were found to be sensitive to sample loading volume. An apparent difference was also found between the mobile phases for nanoliter and conventional high-performance liquid chromatography. Baseline separation of arsenite, arsenate, monomethylarsenic, and dimethylarsenic was achieved within 11 min on a 15 cm C 18 capillary column and within 12 min on a 25 cm strong anion exchange column. Detection limits of 0.9-1.8 μg/L were obtained with precisions variable in the range of 1.6-4.2%. A good agreement between determined and certified values of a certified reference material of human urine (GBW 09115) validated its accuracy along with good recoveries (87-102%). © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Study of the in vitro metabolism of TJ0711 using ultra high performance liquid chromatography with quadrupole time-of-flight and ultra fast liquid chromatography with quadrupole linear ion trap mass spectrometry.

PubMed

Hu, Lei; Lv, Zhenhua; Li, Gao; Xu, Xiaolong; Zhang, Chenghao; Cao, Peng; Huang, Jiangeng; Si, Luqin

2015-06-01

TJ0711 (1-[4-(2-methoxyethyl)phenoxy]-3-[2-(2-methoxyphenoxy)ethylamino]-2-propanol) is a novel β-adrenoreceptor blocker with vasodilating activity. The aim of this study was to investigate the in vitro metabolic properties of TJ0711 from both qualitative and quantitative aspects using mouse, rat, dog, and human liver microsomes as well as rat hepatocytes. Two modern liquid chromatography with tandem mass spectrometry systems, ultra high performance liquid chromatography with quadrupole time-of-flight mass spectrometry and ultra fast liquid chromatography with quadrupole linear ion trap mass spectrometry, were utilized for the analysis. To better characterize the metabolic pathways of TJ0711, two major metabolites were incubated under the same conditions as that for TJ0711. TJ0711 was extensively metabolized in vitro, and a total of 34 metabolites, including 19 phase I and 15 phase II metabolites, were identified. Similar metabolite profiles were observed among species, and demethylation, hydroxylation, carboxylic acid formation, and glucuronidation were proposed as the major metabolic routes. Significant interspecies differences were observed in the metabolic stability studies of TJ0711. Furthermore, gender differences were significant in mice, rats, and dogs, but were negligible in humans. The valuable information provided in this work will be useful in planning and interpreting further pharmacokinetic, in vivo metabolism and toxicological studies of this novel β-blocker. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Analysis of major antioxidants from extracts of Myrmecodia pendans by UV/visible spectrophotometer, liquid chromatography/tandem mass spectrometry, and high-performance liquid chromatography/UV techniques.

PubMed

Engida, Adam Mekonnen; Faika, Sitti; Nguyen-Thi, Bich Thuyen; Ju, Yi-Hsu

2015-06-01

In the present work, heat reflux extraction with ethanol/water (80:20; v/v) as the solvent was used to extract antioxidants from Myrmecodia pendans. The crude extract (CE) was fractionated using hexane and ethyl acetate. Ethyl acetate fraction (EAF) and aqueous fraction were collected. Antioxidant activity against 1,1-diphenyl-2-picrylhydrazyl-radical radical and ferric reducing power of the CE, EAF, and aqueous fraction were evaluated. EAF showed comparable antioxidant activity against 1,1-diphenyl-2-picrylhydrazyl-radical radical and ferric reducing power to those of the CE. UV/visible, liquid chromatography/electrospray ionization/tandem mass spectrometry, and high-performance liquid chromatography were employed for identifying the major antioxidant compounds in the EAF. Three major phenolic compounds (rosmarinic acid, procyanidin B1, and polymer of procyanidin B1) were identified. The first two compounds were confirmed and quantified by high-performance liquid chromatography using authentic standards, but confirmation of the third compound was hampered by a lack of commercial standard. Concentrations of rosmarinic acid and procyanidin B1 in the EAF were found to be 20.688 ± 1.573 mg/g dry sample and 3.236 ± 0.280 mg/g dry sample, respectively. All these three compounds are reported for the first time in sarang semut. Copyright © 2014. Published by Elsevier B.V.

Two-way and three-way approaches to ultra high performance liquid chromatography-photodiode array dataset for the quantitative resolution of a two-component mixture containing ciprofloxacin and ornidazole.

PubMed

Dinç, Erdal; Ertekin, Zehra Ceren; Büker, Eda

2016-09-01

Two-way and three-way calibration models were applied to ultra high performance liquid chromatography with photodiode array data with coeluted peaks in the same wavelength and time regions for the simultaneous quantitation of ciprofloxacin and ornidazole in tablets. The chromatographic data cube (tensor) was obtained by recording chromatographic spectra of the standard and sample solutions containing ciprofloxacin and ornidazole with sulfadiazine as an internal standard as a function of time and wavelength. Parallel factor analysis and trilinear partial least squares were used as three-way calibrations for the decomposition of the tensor, whereas three-way unfolded partial least squares was applied as a two-way calibration to the unfolded dataset obtained from the data array of ultra high performance liquid chromatography with photodiode array detection. The validity and ability of two-way and three-way analysis methods were tested by analyzing validation samples: synthetic mixture, interday and intraday samples, and standard addition samples. Results obtained from two-way and three-way calibrations were compared to those provided by traditional ultra high performance liquid chromatography. The proposed methods, parallel factor analysis, trilinear partial least squares, unfolded partial least squares, and traditional ultra high performance liquid chromatography were successfully applied to the quantitative estimation of the solid dosage form containing ciprofloxacin and ornidazole. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Comprehensive analysis of pharmaceutical products using simultaneous mixed-mode (ion-exchange/reversed-phase) and hydrophilic interaction liquid chromatography.

PubMed

Kazarian, Artaches A; Nesterenko, Pavel N; Soisungnoen, Phimpha; Burakham, Rodjana; Srijaranai, Supalax; Paull, Brett

2014-08-01

Liquid chromatographic assays were developed using a mixed-mode column coupled in sequence with a hydrophilic interaction liquid chromatography column to allow the simultaneous comprehensive analysis of inorganic/organic anions and cations, active pharmaceutical ingredients, and excipients (carbohydrates). The approach utilized dual sample injection and valve-mediated column switching and was based upon a single high-performance liquid chromatography gradient pump. The separation consisted of three distinct sequential separation mechanisms, namely, (i) ion-exchange, (ii) mixed-mode interactions under an applied dual gradient (reversed-phase/ion-exchange), and (iii) hydrophilic interaction chromatography. Upon first injection, the Scherzo SS C18 column (Imtakt) provided resolution of inorganic anions and cations under isocratic conditions, followed by a dual organic/salt gradient to elute active pharmaceutical ingredients and their respective organic counterions and potential degradants. At the top of the mixed-mode gradient (high acetonitrile content), the mobile phase flow was switched to a preconditioned hydrophilic interaction liquid chromatography column, and the standard/sample was reinjected for the separation of hydrophilic carbohydrates, some of which are commonly known excipients in drug formulations. The approach afforded reproducible separation and resolution of up to 23 chemically diverse solutes in a single run. The method was applied to investigate the composition of commercial cough syrups (Robitussin®), allowing resolution and determination of inorganic ions, active pharmaceutical ingredients, excipients, and numerous well-resolved unknown peaks. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Review of in situ derivatization techniques for enhanced bioanalysis using liquid chromatography with mass spectrometry.

PubMed

Baghdady, Yehia Z; Schug, Kevin A

2016-01-01

Accurate and specific analysis of target molecules in complex biological matrices remains a significant challenge, especially when ultra-trace detection limits are required. Liquid chromatography with mass spectrometry is often the method of choice for bioanalysis. Conventional sample preparation and clean-up methods prior to the analysis of biological fluids such as liquid-liquid extraction, solid-phase extraction, or protein precipitation are time-consuming, tedious, and can negatively affect target recovery and detection sensitivity. An alternative or complementary strategy is the use of an off-line or on-line in situ derivatization technique. In situ derivatization can be incorporated to directly derivatize target analytes in their native biological matrices, without any prior sample clean-up methods, to substitute or even enhance the extraction and preconcentration efficiency of these traditional sample preparation methods. Designed appropriately, it can reduce the number of sample preparation steps necessary prior to analysis. Moreover, in situ derivatization can be used to enhance the performance of the developed liquid chromatography with mass spectrometry-based bioanalysis methods regarding stability, chromatographic separation, selectivity, and ionization efficiency. This review presents an overview of the commonly used in situ derivatization techniques coupled to liquid chromatography with mass spectrometry-based bioanalysis to guide and to stimulate future research. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Validation of highly sensitive simultaneous targeted and untargeted analysis of keto-steroids by Girard P derivatization and stable isotope dilution-liquid chromatography-high resolution mass spectrometry.

PubMed

Frey, Alexander J; Wang, Qingqing; Busch, Christine; Feldman, Daniel; Bottalico, Lisa; Mesaros, Clementina A; Blair, Ian A; Vachani, Anil; Snyder, Nathaniel W

2016-12-01

A multiplexed quantitative method for the analysis of three major unconjugated steroids in human serum by stable isotope dilution liquid chromatography-high resolution mass spectrometry (LC-HRMS) was developed and validated on a Q Exactive Plus hybrid quadrupole/Orbitrap mass spectrometer. This quantification utilized isotope dilution and Girard P derivatization on the keto-groups of testosterone (T), androstenedione (AD) and dehydroepiandrosterone (DHEA) to improve ionization efficiency using electrospray ionization. Major isomeric compounds to T and DHEA; the inactive epimer of testosterone (epiT), and the metabolite of AD, 5α-androstanedione (5α-AD) were completely resolved on a biphenyl column within an 18min method. Inter- and intra-day method validation using LC-HRMS with qualifying product ions was performed and acceptable analytical performance was achieved. The method was further validated by comparing steroid levels from 100μL of serum from young vs older subjects. Since this approach provides high-dimensional HRMS data, untargeted analysis by age group was performed. DHEA and T were detected among the top analytes most significantly different across the two groups after untargeted LC-HRMS analysis, as well as a number of other still unknown metabolites, indicating the potential for combined targeted/untargeted analysis in steroid analysis. Copyright © 2016 Elsevier Inc. All rights reserved.

Silica-Based, Hyper-Crosslinked Acid Stable Stationary Phases for High Performance Liquid Chromatography

PubMed Central

Zhang, Yu; Luo, Hao; Carr, Peter W.

2011-01-01

A new family of Hyper-Crosslinked (HC) phases has been recently introduced for use under very aggressive acid conditions including those encountered in ultra-fast, high temperature Two-Dimensional Liquid Chromatography (2DLC). This type of stationary phase showed significantly enhanced acid and thermal stability compared to the most acid stable, commercial RPLC phases. In addition, the use of “orthogonal” chemistry to make surface-confined polymer networks ensures good reproducibility and high efficiency. One of the most interesting features of the HC phases is the ability to derivatize the surface aromatic groups with various functional groups. This led to the development of a family of hyper-crosslinked phases possessing a wide variety of chromatographic selectivities by attaching hydrophobic (e.g. –C8), ionizable (e.g. -COOH, -SO3H), aromatic (e.g. –toluene) or polar (e.g. -OH) species to the aromatic polymer network. HC reversed phases with various degrees of hydrophobicity and mixed-mode HC phases with added strong and weak cation exchange sites have been synthesized, characterized and applied. These silica-based acid-stable HC phases, with their attractive chromatographic properties, should be very useful in the separations of bases or biological analytes in acidic media, especially at elevated temperatures. This work reviews the prior research on HC phases and introduces a novel HC phase made by alternative chemistry. PMID:21906745

An evaluation of sucrose as a possible contaminant in e-liquids for electronic cigarettes by hydrophilic interaction liquid chromatography-tandem mass spectrometry.

PubMed

Kubica, Paweł; Wasik, Andrzej; Kot-Wasik, Agata; Namieśnik, Jacek

2014-05-01

The influence of sucrose combustion products on smoking and nicotine addiction is still controversial because the presence of the sucrose may be treated as a source of aldehydes and organic acids. In e-liquids used as refills for electronic cigarettes, which are made primarily of poly(propylene glycol), glycerine and ethanol, sucrose may be present at trace levels, and its impact on mainstream smoke formation, and hence on human health and smoking/nicotine addiction is unknown. An analytical method was developed where high-performance liquid chromatography in hydrophilic interaction liquid chromatography mode and tandem mass spectrometry were used for fast and simple determination of sucrose and other saccharides in e-liquids for electronic cigarettes. Minimal effort was required in the sample preparation step, and satisfactory results were obtained, and the sample matrix had an insignificant impact. The chromatographic separation was done using an Ascentis Express OH5 column (150 mm × 2.1 mm, 2.7 μm). The coefficients of variation for within-day precision for three concentrations were 2.4 %, 1.6 % and 2.3 %, and the between-day coefficients of variation for a single concentration were 2.1 %, 2.5 % and 1.7 % measured on the next 3 days. The detection limit was 0.73 μg/g, and the sucrose content in e-liquids ranged from 0.76 to 72.93 μg/g among 37 samples. Moreover, with the method presented it is possible to determine the presence of other saccharides such as fructose, glucose, maltose and lactose. However, only sucrose was found in all samples of e-liquids. The proposed method is rapid, simple and reliable in terms of high-performance liquid chromatography coupled with tandem mass spectrometry.

Interaction of human low density lipoprotein and apolipoprotein B with ternary lipid microemulsion. Physical and functional properties.

PubMed

Chun, P W; Brumbaugh, E E; Shiremann, R B

1986-12-31

Based on data from sedimentation velocity experiments, electrophoresis, electron microscopy, cellular uptake studies, scanning molecular sieve chromatography using a quasi-three-dimensional data display and flow performance liquid chromatography (FPLC), models for the interaction of human serum low density lipoprotein (LDL) and of apolipoprotein B (apo B) with a ternary lipid microemulsion (ME) are proposed. The initial step in the interaction of LDL (Stokes radius 110 A) with the ternary microemulsion (Stokes radius 270 A) appears to be attachment of the LDL to emulsion particles. This attachment is followed by a very slow fusion into particles having a radius of approx. 280 A. Sonication of this mixture yields large aggregates. Electron micrographs of deoxycholate-solubilized apo B indicate an arrangement of apo B resembling strings of beads. During incubation, these particles also attach to the ternary microemulsion particles and, upon sonication, spherical particles result which resemble native LDL particles in size. Scanning chromatography corroborates the electron microscopy results. By appropriate choice of display angles in a quasi-three-dimensional display of the scanning data (corrected for gel apparent absorbance) taken at equal time intervals during passage of a sample through the column, changes in molecular radius of less than 10 A can be detected visually. Such a display gives a quantitative estimate of 101 +/- 2 A for these particles (compared to 110 A for native LDL). The LDL-ME particles and apo B-ME particles compete efficiently with native LDL for cellular binding and uptake. Cellular association studies indicate that both LDL- and apo B-ME particles are effective vehicles for lipid delivery into cells.

A simple and inexpensive on-column frit fabrication method for fused-silica capillaries for increased capacity and versatility in LC-MS/MS applications.

PubMed

Wang, Ling-Chi; Okitsu, Cindy Yen; Kochounian, Harold; Rodriguez, Anthony; Hsieh, Chih-Lin; Zandi, Ebrahim

2008-05-01

A modified sol-gel method for a one-step on-column frit preparation for fused-silica capillaries and its utility for peptide separation in LC-MS/MS is described. This method is inexpensive, reproducible, and does not require specialized equipments. Because the frit fabrication process does not damage polyimide coating, the frit-fabricated column can be tightly connected on-line for high pressure LC. These columns can replace any capillary liquid transfer tubing without any specialized connections up-stream of a spray tip column. Therefore multiple columns with different phases can be connected in series for one- or multiple-dimensional chromatography.

Indirect ultraviolet detection of alkaline earth metal ions using an imidazolium ionic liquid as an ultraviolet absorption reagent in ion chromatography.

PubMed

Liu, Yong-Qiang; Yu, Hong

2017-04-01

A convenient and versatile method was developed for the separation and detection of alkaline earth metal ions by ion chromatography with indirect UV detection. The chromatographic separation of Mg 2+ , Ca 2+ , and Sr 2+ was performed on a carboxylic acid base cation exchange column using imidazolium ionic liquid/acid as the mobile phase, in which the imidazolium ionic liquid acted as an UV-absorption reagent. The effects of imidazolium ionic liquids, detection wavelength, acids in the mobile phase, and column temperature on the retention of Mg 2+ , Ca 2+ , and Sr 2+ were investigated. The main factors influencing the separation and detection were the background UV absorption reagent and the concentration of hydrogen ion in ion chromatography with indirect UV detection. The successful separation and detection of Mg 2+ , Ca 2+ , and Sr 2+ within 14 min were achieved using the selected chromatographic conditions, and the detection limits (S/N = 3) were 0.06, 0.12, and 0.23 mg/L, respectively. A new separation and detection method of alkaline earth metal ions by ion chromatography with indirect UV detection was developed, and the application range of ionic liquids was expanded. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Analytical methodologies for broad metabolite coverage of exhaled breath condensate.

PubMed

Aksenov, Alexander A; Zamuruyev, Konstantin O; Pasamontes, Alberto; Brown, Joshua F; Schivo, Michael; Foutouhi, Soraya; Weimer, Bart C; Kenyon, Nicholas J; Davis, Cristina E

2017-09-01

Breath analysis has been gaining popularity as a non-invasive technique that is amenable to a broad range of medical uses. One of the persistent problems hampering the wide application of the breath analysis method is measurement variability of metabolite abundances stemming from differences in both sampling and analysis methodologies used in various studies. Mass spectrometry has been a method of choice for comprehensive metabolomic analysis. For the first time in the present study, we juxtapose the most commonly employed mass spectrometry-based analysis methodologies and directly compare the resultant coverages of detected compounds in exhaled breath condensate in order to guide methodology choices for exhaled breath condensate analysis studies. Four methods were explored to broaden the range of measured compounds across both the volatile and non-volatile domain. Liquid phase sampling with polyacrylate Solid-Phase MicroExtraction fiber, liquid phase extraction with a polydimethylsiloxane patch, and headspace sampling using Carboxen/Polydimethylsiloxane Solid-Phase MicroExtraction (SPME) followed by gas chromatography mass spectrometry were tested for the analysis of volatile fraction. Hydrophilic interaction liquid chromatography and reversed-phase chromatography high performance liquid chromatography mass spectrometry were used for analysis of non-volatile fraction. We found that liquid phase breath condensate extraction was notably superior compared to headspace extraction and differences in employed sorbents manifested altered metabolite coverages. The most pronounced effect was substantially enhanced metabolite capture for larger, higher-boiling compounds using polyacrylate SPME liquid phase sampling. The analysis of the non-volatile fraction of breath condensate by hydrophilic and reverse phase high performance liquid chromatography mass spectrometry indicated orthogonal metabolite coverage by these chromatography modes. We found that the metabolite coverage could be enhanced significantly with the use of organic solvent as a device rinse after breath sampling to collect the non-aqueous fraction as opposed to neat breath condensate sample. Here, we show the detected ranges of compounds in each case and provide a practical guide for methodology selection for optimal detection of specific compounds. Copyright © 2017 Elsevier B.V. All rights reserved.

Trends in data processing of comprehensive two-dimensional chromatography: state of the art.

PubMed

Matos, João T V; Duarte, Regina M B O; Duarte, Armando C

2012-12-01

The operation of advanced chromatographic systems, namely comprehensive two-dimensional (2D) chromatography coupled to multidimensional detectors, allows achieving a great deal of data that need special care to be processed in order to characterize and quantify as much as possible the analytes under study. The aim of this review is to identify the main trends, research needs and gaps on the techniques for data processing of multidimensional data sets obtained from comprehensive 2D chromatography. The following topics have been identified as the most promising for new developments in the near future: data acquisition and handling, peak detection and quantification, measurement of overlapping of 2D peaks, and data analysis software for 2D chromatography. The rational supporting most of the data processing techniques is based on the generalization of one-dimensional (1D) chromatography although algorithms, such as the inverted watershed algorithm, use the 2D chromatographic data as such. However, for processing more complex N-way data there is a need for using more sophisticated techniques. Apart from using other concepts from 1D chromatography, which have not been tested for 2D chromatography, there is still room for new improvements and developments in algorithms and software for dealing with 2D comprehensive chromatographic data. Copyright © 2012 Elsevier B.V. All rights reserved.

Application of ionic liquids in liquid chromatography and electrodriven separation.

PubMed

Huang, Yi; Yao, Shun; Song, Hang

2013-08-01

Ionic liquids (ILs) are salts in the liquid state at ambient temperature, which are nonvolatile, nonflammable with high thermal stability and dissolve easily for a wide range of inorganic and organic materials. As a kind of potential green solvent, they show high efficiency and selectivity in the field of separation research, especially in instrumental analysis. Thus far, ILs have been successfully applied by many related researchers in high-performance liquid chromatography and capillary electrophoresis as chromatographic stationary phases, mobile phase additives or electroosmotic flow modifiers. This paper provides a detailed review of these applications in the study of natural products, foods, drugs and other fine chemicals. Furthermore, the prospects of ILs in liquid chromatographic and electrodriven techniques are discussed.

Ruggedness testing and validation of a practical analytical method for > 100 veterinary drug residues in bovine muscle by ultrahigh performance liquid chromatography – tandem mass spectrometry

USDA-ARS?s Scientific Manuscript database

In this study, optimization, extension, and validation of a streamlined, qualitative and quantitative multiclass, multiresidue method was conducted to monitor great than100 veterinary drug residues in meat using ultrahigh-performance liquid chromatography – tandem mass spectrometry (UHPLC-MS/MS). I...

An Undergraduate Experiment for the Measurement of Perfluorinated Surfactants in Fish Liver by Liquid Chromatography-Tandem Mass Spectrometry

ERIC Educational Resources Information Center

Stock, Naomi L.; Martin, Jonathan W.; Ye, Yun; Mabury, Scott A.

2007-01-01

A laboratory experiment that provides students a hands-on introduction to the specific techniques of liquid chromatography-tandem mass spectrometry (LC-MS/MS) and electrospray ionization is presented. The students can thus practice the analytical principles of sample extraction, detection, quantification, and quality control using a fresh fish…

Identification of glyceollin metabolites derived from conjugation with glutathione and glucuronic acid in rats by on-line liquid chromatography-electrospray ionization tandem mass spectrometry

USDA-ARS?s Scientific Manuscript database

Glyceollin-related metabolites produced in rats following oral glyceollin administration were screened and identified by precursor and product ion scanning using liquid chromatography, coupled on-line with electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS), to identify all glyceollin me...

ON SITE SOLID-PHASE EXTRACTION AND LABORATORY ANALYSIS OF ULTRA-TRACE SYNTHETIC MUSKS IN MUNICIPAL SEWAGE EFFLUENT USING GAS CHROMATOGRAPHY-MASS SPECTROMETRY. FULL-SCAN MODE

EPA Science Inventory

Fragrance materials such as synthetic musks in aqueous samples, are normally determined by gas chromatography/mass spectrometry in the selected ion monitoring (SIM) mode to provide maximum sensitivity after liquid-liquid extraction of I -L samples. Full-scan mass spectra are requ...

Liquid chromatography-electrospray ionization mass spectrometry analysis of limonoids and flavanois in seeds of grapefruits, other citrus species, and dietary supplements

USDA-ARS?s Scientific Manuscript database

A selective ultra-high performance liquid chromatography-didode array detector-quadrapole time of flight-mass spectrometry (UHPLC-DAD-QToF-MS) method has been developed to screen grapefruit seeds, and other citrus seed samples for limonoid aglycones, limonoid acids, limonoid glucosides and flavonoid...

Profiling the indole alkaloids in yohimbe bark with ultra-performance liquid chromatography coupled with ion mobility quadrupole time-of-flight mass spectrometry

USDA-ARS?s Scientific Manuscript database

An ultra-high performance liquid chromatography-ion mobility- quadrupole time-of-flight mass spectrometry (UHPLC-IM-QTOF-MS) method was developed for profiling the indole alkaloids in yohimbe bark. Many indole alkaloids with the yohimbine core structure, plus methylated, oxidized, and reduced speci...

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…

Liquid chromatography with tandem mass spectrometry quantification of urinary proanthocyanin A2 dimer and its potential use as a biomarker of cranberry intake

USDA-ARS?s Scientific Manuscript database

The lack of a biomarker for the consumption of cranberries has confounded the interpretation of several studies investigating the effect of cranberry products, especially juices, on health outcomes. The objectives of this pilot study were to develop a liquid chromatography tandem mass spectrometric ...

Simultaneous Determination of Caffeine and Vitamin B6 in Energy Drinks by High-Performance Liquid Chromatography (HPLC)

ERIC Educational Resources Information Center

Leacock, Rachel E.; Stankus, John J.; Davis, Julian M.

2011-01-01

A high-performance liquid chromatography experiment to determine the concentration of caffeine and vitamin B6 in sports energy drinks has been developed. This laboratory activity, which is appropriate for an upper-level instrumental analysis course, illustrates the standard addition method and simultaneous determination of two species. (Contains 1…

Rapid qualitative and quantitative analysis of proanthocyanidin oligomers and polymers by ultra-performance liquid chromatography – tandem mass spectrometry (UPLC-MS/MS)

USDA-ARS?s Scientific Manuscript database

We developed a rapid method with ultra-performance liquid chromatography – tandem mass spectrometry (UPLC-MS/MS) for the qualitative and quantitative analysis of plant proanthocyanidins (PAs) directly from crude plant extracts. The method utilizes a range of cone voltages to achieve the depolymeriza...

Exploring Liquid Sequential Injection Chromatography to Teach Fundamentals of Separation Methods: A Very Fast Analytical Chemistry Experiment

ERIC Educational Resources Information Center

Penteado, Jose C.; Masini, Jorge Cesar

2011-01-01

Influence of the solvent strength determined by the addition of a mobile-phase organic modifier and pH on chromatographic separation of sorbic acid and vanillin has been investigated by the relatively new technique, liquid sequential injection chromatography (SIC). This technique uses reversed-phase monolithic stationary phase to execute fast…

Determination of sugars in honey by liquid chromatography

PubMed Central

Kamal, Mohammad A.; Klein, Peter

2010-01-01

Honey is a rich conventional natural resource of sweetness and energy for human beings. A protocol for the determination of two important monosaccharide sugars (fructose and glucose) in honey was established in the current study by using normal phase partition liquid chromatography and 1–5% combined working standard of glucose, fructose and sucrose. PMID:23961099

Utilization of high performance liquid chromatography coupled to tandem mass spectrometry for characterization of 8-O-methylbostrycoidin production by species of the fungus Fusarium

USDA-ARS?s Scientific Manuscript database

The pigment, 8-O-methylbostrycoidin is a polyketide metabolite produced by multiple species of the fungus Fusarium that infects plant crops, including maize. A technique was developed for the analysis of 8-O-methylbostrycoidin by high performance liquid chromatography coupled to electrospray ionizat...

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.

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.

Comparative oxidation state specific analysis of arsenic species by high-performance liquid chromatography-inductively coupled-mass spectrometry and hydride generation-cryotrapping-atomic absorption spectrometry

EPA Science Inventory

The formation of methylarsonous acid (MAsIII) and dimethylarsinous acid (DMAsIII) in the course of inorganic arsenic (iAs) metabolism plays an important role in the adverse effects of chronic exposure to iAs. High-performance liquid chromatography-inductively coupled plasma-mass ...

The Trace Analysis of DEET in Water using an On-line Preconcentration Column and Liquid Chromatography with UV Photodiode Array Detection

EPA Science Inventory

A method for the detection of trace levels of N,N-diethyl-m-toluamide (DEET) in water is discussed. The method utilizes an on-line preconcentration column in series with high performance liquid chromatography (HPLC) and UV photodiode array detection. DEET, a common insect repel...

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

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.

Highly efficient peptide separations in proteomics. Part 2: bi- and multidimensional liquid-based separation techniques.

PubMed

Sandra, Koen; Moshir, Mahan; D'hondt, Filip; Tuytten, Robin; Verleysen, Katleen; Kas, Koen; François, Isabelle; Sandra, Pat

2009-04-15

Multidimensional liquid-based separation techniques are described for maximizing the resolution of the enormous number of peptides generated upon tryptic digestion of proteomes, and hence, reduce the spatial and temporal complexity of the sample to a level that allows successful mass spectrometric analysis. This review complements the previous contribution on unidimensional high performance liquid chromatography (HPLC). Both chromatography and electrophoresis will be discussed albeit with reversed-phase HPLC (RPLC) as the final separation dimension prior to MS analysis.

Ergosterol from the soilborne fungus Ganoderma boninense.

PubMed

Toh Choon, R L; Sariah, M; Siti Mariam, M N

2012-10-01

Ergosterol is the main component of the fungal membrane and is not found in plants or other microbial cells. Therefore, it can be a useful biomarker for the quantification of fungal biomass. We are now reporting the first isolation and characterisation of ergosterol from the mycelium of G. boninense. The ergosterol structure was detected by Thin Liquid Chromatography (TLC) and Ultra Performance Liquid Chromatography (UPLC) and confirmed with Gas Chromatography coupled with Mass Spectrometry (GCMS) and Nuclear Magnetic Resonance (NMR) analysis. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Recent Analytical Techniques Advances in the Carotenoids and Their Derivatives Determination in Various Matrixes.

PubMed

Giuffrida, Daniele; Donato, Paola; Dugo, Paola; Mondello, Luigi

2018-04-04

In the present perspective, different approaches to the carotenoids analysis will be discussed providing a brief overview of the most advanced both monodimensional and bidimensional liquid chromatographic methodologies applied to the carotenoids analysis, followed by a discussion on the recents advanced supercritical fluid chromatography × liquid chromatography bidimensional approach with photodiode-array and mass spectrometry detection. Moreover a discussion on the online supercritical fluid extraction-supercritical fluid chromatography with tandem mass spectrometry detection applied to the determination of carotenoids and apocarotenoids will also be provided.

Separation of flavonol-2-O-glycosides from Calendula officinalis and Sambucus nigra by high-performance liquid and micellar electrokinetic capillary chromatography.

PubMed

Pietta, P; Bruno, A; Mauri, P; Rava, A

1992-02-28

Calendula officinalis and Sambucus nigra flowers were analysed by reversed-phase high-performance liquid chromatography (RP-HPLC) and micellar electrokinetic capillary chromatography (MECC). RP-HPLC was performed on C8 Aquapore RP 300 columns with eluents containing 2-propanol and tetrahydrofuran. MECC was carried out on a 72-cm fused-silica capillary using sodium dodecyl sulphate and sodium borate (pH 8.3) as the running buffer. The results obtained by these techniques are compared.

Rapid screening, separation, and detection of hydroxyl radical scavengers from total flavonoids of Ginkgo biloba leaves by chromatography combined with molecular devices.

PubMed

Wang, Jing; Zheng, Meizhu; Chen, Lina; Liu, Zhiqiang; Zhang, Yuchi; Liu, Chun-Ming; Liu, Shu

2016-11-01

Hydroxyl radicals are the most reactive free radical of human body, a strong contributor to tissue damage. In this study, liquid chromatography coupled to electrospray ionization mass spectrometry was applied to screen and identify hydroxyl radical scavengers from the total flavonoids of Ginkgo biloba leaves, and high-performance counter current chromatography was used to separate and isolate the active compounds. Furthermore, molecular devices were used to determine hydroxyl radical scavenging activities of the obtained hydroxyl radical scavengers and other flavonoids from G. biloba leaves. As a result, six compounds were screened as hydroxyl radical scavengers, but only three flavonoids, namely, rutin, cosmos glycosides and apigenin-7-O-Glu-4'-O-Rha, were isolated successfully from total flavonoids by high-performance counter current chromatography. The purities of the three obtained compounds were over 90%, respectively, as determined by liquid chromatography. Molecular devices with 96-well microplates evaluation indicated that the 50% scavenging concentration values of screened compounds were lower than that of other flavonoids, they performed greater hydroxyl radical scavenging activity, and the evaluation effects were consistent with the liquid chromatography with mass spectrometry screening results. Therefore, chromatography combined with molecular devices is a feasible and an efficient method for systematic screening, identification, isolation, and evaluation of bioactive components in mixture of botanical medicines. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Using cell membrane chromatography and HPLC-TOF/MS method for in vivo study of active components from roots of Aconitum carmichaeli

PubMed Central

Cao, Yan; Chen, Xiao-Fei; Lü, Di-Ya; Dong, Xin; Zhang, Guo-Qing; Chai, Yi-Feng

2012-01-01

An offline two-dimensional system combining a rat cardiac muscle cell membrane chromatography time-of-flight mass spectrometry (CMC-TOF/MS) with a high Performance liquid chromatography time-of-flight mass spectrometry (HPLC-TOF/MS) was established for investigating the parent components and metabolites in rat urine samples after administration of the roots of Aconitum carmichaeli. On the basis ofthe analysis of the first dimension, retention components of the urine sample were collected into 30 fractions (one fraction per minute). Then offline analysis of the second dimension was carried out. 34 compounds including 24 parent alkaloids and 10 potential metabolites were identified from the dosed rat urine, and then binding affinities of different compounds on cell membranes were compared and influences of some functional groups on activity were estimated with the semi-quantification and curve fitting method. As a result, binding affinities decreased along with the process of deacylation, debenzoylation and demethylation, which may be related to the alleviation of toxicity in the procedure of herb processing or metabolism. Moreover, some minor components in rat urine (Songorine, 14-benzoylneoline, Deoxyaconitine, etc.) exerted relatively strong affinity on cell membranes are worth exploring. The results delivered by the System suggest that the CMC can be applied to in vivo study. PMID:29403691

Chromatographic methods for determination of macrolide antibiotic residues in tissues and milk of food-producing animals.

PubMed

Moats, W A

1985-01-01

Tylosin, an antibiotic developed specifically for agricultural use, and erythromycin are the main macrolide antibiotics used in animal production. Two-dimensional thin layer chromatography has been used for detection of tylosin in poultry meat, eggs, and milk and for erythromycin in poultry meat. Detection limits reported are, for tylosin, 0.1 ppm in poultry meat, 0.05 ppm in egg, and 0.01 ppm in milk, and for erythromycin, 0.25 ppm in poultry meat. Liquid chromatography (LC) has also been used for determination of tylosin in milk, blood, and tissues of animals. Samples (milk, blood serum, or tissue homogenates in water or pH 2.2 buffer) were deproteinized with acetonitrile, tylosin was partitioned into methylene chloride, and the extracts were concentrated and dissolved in acetonitrile. Chromatography was done on a reverse phase end-capped C18 column using 0.002-0.005 M ammonium dihydrogen phosphate-acetonitrile-methanol (10 + 60 + 30-5 + 80 + 15). Solvent composition was varied with the type of sample analyzed. The method will detect 0.1 ppm tylosin in tissues and less in milk and blood serum. The LC method was more sensitive than microbiological assays for detection of tylosin in tissues of treated swine; recoveries of tylosin by the LC method were frequently several-fold higher.

Liquid-liquid phase separation causes high turbidity and pressure during low pH elution process in Protein A chromatography.

PubMed

Luo, Haibin; Lee, Nacole; Wang, Xiangyang; Li, Yuling; Schmelzer, Albert; Hunter, Alan K; Pabst, Timothy; Wang, William K

2017-03-10

Turbid elution pools and high column back pressure are common during elution of monoclonal antibodies (mAbs) by acidic pH in Protein A chromatography. This phenomenon has been historically attributed to acid-induced precipitation of incorrectly folded or pH-sensitive mAbs and host cell proteins (HCPs). In this work, we propose a new mechanism that may account for some observations of elution turbidity in Protein A chromatography. We report several examples of turbidity and high column back pressure occurring transiently under a short course of neutral conditions during Protein A elution. A systematic study of three mAbs displaying this behavior revealed phase separation characterized by liquid drops under certain conditions including neutral pH, low ionic strength, and high protein concentration. These liquid droplets caused solution turbidity and exhibited extremely high viscosity, resulting in high column back pressure. We found out that the droplets were formed through liquid-liquid phase separation (LLPS) as a result of protein self-association. We also found multiple factors, including pH, temperature, ionic strength, and protein concentration can affect LLPS behaviors. Careful selection of process parameters during protein A elution, including temperature, flow rate, buffer, and salt can inhibit formation of a dense liquid phase, reducing both turbidity (by 90%) and column back pressure (below 20 pounds per square inch). These findings provide both mechanistic insight and practical mitigation strategies for Protein A chromatography induced LLPS. Copyright © 2017 The Author(s). Published by Elsevier B.V. All rights reserved.

Simultaneous determination of caffeine, paracetamol, and ibuprofen in pharmaceutical formulations by high-performance liquid chromatography with UV detection and by capillary electrophoresis with conductivity detection.

PubMed

Cunha, Rafael R; Chaves, Sandro C; Ribeiro, Michelle M A C; Torres, Lívia M F C; Muñoz, Rodrigo A A; Dos Santos, Wallans T P; Richter, Eduardo M

2015-05-01

Paracetamol, caffeine and ibuprofen are found in over-the-counter pharmaceutical formulations. In this work, we propose two new methods for simultaneous determination of paracetamol, caffeine and ibuprofen in pharmaceutical formulations. One method is based on high-performance liquid chromatography with diode-array detection and the other on capillary electrophoresis with capacitively coupled contactless conductivity detection. The separation by high-performance liquid chromatography with diode-array detection was achieved on a C18 column (250×4.6 mm(2), 5 μm) with a gradient mobile phase comprising 20-100% acetonitrile in 40 mmol L(-1) phosphate buffer pH 7.0. The separation by capillary electrophoresis with capacitively coupled contactless conductivity detection was achieved on a fused-silica capillary (40 cm length, 50 μm i.d.) using 10 mmol L(-1) 3,4-dimethoxycinnamate and 10 mmol L(-1) β-alanine with pH adjustment to 10.4 with lithium hydroxide as background electrolyte. The determination of all three pharmaceuticals was carried out in 9.6 min by liquid chromatography and in 2.2 min by capillary electrophoresis. Detection limits for caffeine, paracetamol and ibuprofen were 4.4, 0.7, and 3.4 μmol L(-1) by liquid chromatography and 39, 32, and 49 μmol L(-1) by capillary electrophoresis, respectively. Recovery values for spiked samples were between 92-107% for both proposed methods. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Comprehensive quantitative analysis of Chinese patent drug YinHuang drop pill by ultra high-performance liquid chromatography quadrupole time of flight mass spectrometry.

PubMed

Wong, Tin-Long; An, Ya-Qi; Yan, Bing-Chao; Yue, Rui-Qi; Zhang, Tian-Bo; Ho, Hing-Man; Ren, Tian-Jing; Fung, Hau-Yee; Ma, Dik-Lung; Leung, Chung-Hang; Liu, Zhong-Liang; Pu, Jian-Xin; Han, Quan-Bin; Sun, Han-Dong

2016-06-05

YinHuang drop pill (YHDP) is a new preparation, derived from the traditional YinHuang (YH) decoction. Since drop pills are one of the newly developed forms of Chinese patent drugs, not much research has been done regarding the quality and efficacy. This study aims to establish a comprehensive quantitative analysis of the chemical profile of YHDP. ultra high-performance liquid chromatography quadrupole time of flight mass spectrometry (UHPLC-Q-TOF-MS/MS) was used to identify 34 non-sugar small molecules including 15 flavonoids, 9 phenolic acids, 5 saponins, 1 iridoid, and 4 iridoid glycosides in YHDP samples, and 26 of them were quantitatively determined. Sugar composition of YHDP in terms of fructose, glucose and sucrose was examined via a high performance liquid chromatography-evaporative light scattering detector on an amide column (HPLC-NH2P-ELSD). Macromolecules were examined by high performance gel permeation chromatography coupled with ELSD (HPGPC-ELSD). The content of the drop pill's skeleton component PEG-4000 was also quantified via ultra-high performance liquid chromatography coupled with charged aerosol detector (UHPLC-CAD). The results showed that up to 73% (w/w) of YHDP could be quantitatively determined. Small molecules accounted for approximately 5%, PEG-4000 represented 68%, while no sugars or macromolecules were found. Furthermore, YHDP showed no significant differences in terms of daily dosage, compared to YinHuang granules and YinHuang oral liquid; however, it has a higher small molecules content compared to YinHuang lozenge. Copyright © 2016 Elsevier B.V. All rights reserved.

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. Copyright © 2016 Elsevier B.V. All rights reserved.

Screening of synthetic PDE-5 inhibitors and their analogues as adulterants: analytical techniques and challenges.

PubMed

Patel, Dhavalkumar Narendrabhai; Li, Lin; Kee, Chee-Leong; Ge, Xiaowei; Low, Min-Yong; Koh, Hwee-Ling

2014-01-01

The popularity of phosphodiesterase type 5 (PDE-5) enzyme inhibitors for the treatment of erectile dysfunction has led to the increase in prevalence of illicit sexual performance enhancement products. PDE-5 inhibitors, namely sildenafil, tadalafil and vardenafil, and their unapproved designer analogues are being increasingly used as adulterants in the herbal products and health supplements marketed for sexual performance enhancement. To date, more than 50 unapproved analogues of prescription PDE-5 inhibitors were found as adulterants in the literature. To avoid detection of such adulteration by standard screening protocols, the perpetrators of such illegal products are investing time and resources to synthesize exotic analogues and devise novel means for adulteration. A comprehensive review of conventional and advance analytical techniques to detect and characterize the adulterants is presented. The rapid identification and structural elucidation of unknown analogues as adulterants is greatly enhanced by the wide myriad of analytical techniques employed, including high performance liquid chromatography (HPLC), gas chromatography-mass spectrometry (GC-MS), liquid chromatography mass-spectrometry (LC-MS), nuclear magnetic resonance (NMR) spectroscopy, vibrational spectroscopy, liquid chromatography-Fourier transform ion cyclotron resonance-mass spectrometry (LC-FT-ICR-MS), liquid chromatograph-hybrid triple quadrupole linear ion trap mass spectrometer with information dependent acquisition, ultra high performance liquid chromatography-time of flight-mass spectrometry (UHPLC-TOF-MS), ion mobility spectroscopy (IMS) and immunoassay methods. The many challenges in detecting and characterizing such adulterants, and the need for concerted effort to curb adulteration in order to safe guard public safety and interest are discussed. Copyright © 2013 Elsevier B.V. All rights reserved.

High-resolution liquid chromatography/electrospray ionization time-of-flight mass spectrometry combined with liquid chromatography/electrospray ionization tandem mass spectrometry to identify polyphenols from grape antioxidant dietary fiber.

PubMed

Touriño, Sonia; Fuguet, Elisabet; Jáuregui, Olga; Saura-Calixto, Fulgencio; Cascante, Marta; Torres, Josep Lluís

2008-11-01

Grape antioxidant dietary fiber (GADF) is a dietary supplement that combines the benefits of both fiber and antioxidants that help prevent cancer and cardiovascular diseases. The antioxidant polyphenolic components in GADF probably help prevent cancer in the digestive tract, where they are bioavailable. Mass spectrometry coupled to liquid chromatography is a powerful tool for the analysis of complex plant derivatives such as GADF. We use a combination of MS techniques, namely liquid chromatography/electrospray ionization time-of-flight mass spectrometry (LC/ESI-TOF-MS) and liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS) on a triple quadrupole, for the identification of the polyphenolic constituents of the soluble fraction of GADF. First, we separated the mixture into four fractions which were tested for phenolic constituents using the TOF system in the full scan mode. The high sensitivity and resolution of the TOF detector over the triple quadrupole facilitate the preliminary characterization of the fractions. Then we used LC/ESI-MS/MS to identify the individual phenols through MS/MS experiments (product ion scan, neutral loss scan, precursor ion scan). Finally, most of the identities were unequivocally confirmed by accurate mass measurements on the TOF spectrometer. LC/ESI-TOF-MS combined with MS/MS correctly identifies the bioactive polyphenolic components from the soluble fraction of GADF. High-resolution TOF-MS is particularly useful for identifying the structure of compounds with the same LC/ESI-MS/MS fragmentation patterns.

Separation of four flavonol glycosides from Solanum rostratum Dunal using aqueous two-phase flotation followed by preparative high-performance liquid chromatography.

PubMed

Chang, Lin; Shao, Qian; Xi, Xingjun; Chu, Qiao; Wei, Yun

2017-02-01

Aqueous two-phase flotation followed by preparative high-performance liquid chromatography was used to separate four flavonol glycosides from Solanum rostratum Dunal. In the aqueous two-phase flotation section, the effects of sublation solvent, solution pH, (NH 4 ) 2 SO 4 concentration in aqueous solution, cosolvent, N 2 flow rate, flotation time, and volumes of the polyethylene glycol phase on the recovery were investigated in detail, and the optimal conditions were selected: 50 wt% polyethylene glycol 1000 ethanol solvent as the flotation solvent, pH 4, 350 g/L of (NH 4 ) 2 SO 4 concentration in aqueous phase, 40 mL/min of N 2 flow rate, 30 min of flotation time, 10.0 mL of flotation solvent volume, and two times. After aqueous two-phase flotation concentration, the flotation products were purified by preparative high-performance liquid chromatography. The purities of the final products A and B were 98.1 and 99.0%. Product B was the mixture of three compounds based on the analysis of high-performance liquid chromatography at the temperature of 10°C, while product A was hyperoside after the identification by nuclear magnetic resonance. Astragalin, 3'-O-methylquercetin 3-O-β-d-galactopyranoside, and 3'-O-methylquercetin 3-O-β-d-glucopyranoside were obtained with the purity of 93.8, 97.1, and 99.2%, respectively, after the further separation of product B using preparative high-performance liquid chromatography. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

On-line hyphenation of centrifugal partition chromatography and high pressure liquid chromatography for the fractionation of flavonoids from Hippophaë rhamnoides L. berries.

PubMed

Michel, Thomas; Destandau, Emilie; Elfakir, Claire

2011-09-09

Centrifugal Partition Chromatography (CPC), a liquid-liquid preparative chromatography using two immiscible solvent systems, benefits from numerous advantages for the separation or purification of synthetic or natural products. This study presents the on-line hyphenation of CPC-Evaporative Light Scattering Detector (CPC-ELSD) with High Performance Liquid Chromatography-UV (HPLC-UV) for the fractionation of flavonols from a solvent-free microwave extract of sea buckthorn (Hippophaë rhamnoides L., Elaeagnaceae) berries. An Arizona G system was used for the fractionation of flavonoids by CPC and a fused core Halo C18 column allowed the on-line analyses of collected fractions by HPLC. The on-line CPC/HPLC procedure allowed the simultaneous fractionation step at preparative scale combined with the HPLC analyses which provide direct fingerprint of collected fractions. Thus the crude extract was simplified and immediate information on the composition of fractions could be obtained. Furthermore, this methodology reduced the time of post-fractionation steps and facilitated identification of main molecules by Mass Spectrometry (MS). Rutin, isorhamnetin-3-O-rutinoside, isorhamnetin-3-O-glucoside, quercetin-3-O-glucoside, isorhamnetin-rhamnoside, quercetin and isorhamnetin were identified. CPC-ELSD/HPLC-UV could be considered as a high-throughput technique for the guided fractionation of bioactive natural products from complex crude extracts. Copyright © 2011 Elsevier B.V. All rights reserved.

The quantitation of 2-oxo-3-hydroxy lysergic acid diethylamide (O-H-LSD) in human urine specimens, a metabolite of LSD: comparative analysis using liquid chromatography-selected ion monitoring mass spectrometry and liquid chromatography-ion trap mass spectrometry.

PubMed

Poch, G K; Klette, K L; Anderson, C

2000-04-01

This paper compares the potential forensic application of two sensitive and rapid procedures (liquid chromatography-mass spectrometry and liquid chromatography-ion trap mass spectrometry) for the detection and quantitation of 2-oxo-3-hydroxy lysergic acid diethylamide (O-H-LSD) a major LSD metabolite. O-H-LSD calibration curves for both procedures were linear over the concentration range 0-8,000 pg/mL with correlation coefficients (r2) greater than 0.99. The observed limit of detection (LOD) and limit of quantitation (LOQ) for O-H-LSD in both procedures was 400 pg/mL. Sixty-eight human urine specimens that had previously been found to contain LSD by gas chromatography-mass spectrometry were reanalyzed by both procedures for LSD and O-H-LSD. These specimens contained a mean concentration of O-H-LSD approximately 16 times higher than the LSD concentration. Because both LC methods produce similar results, either procedure can be readily adapted to O-H-LSD analysis for use in high-volume drug-testing laboratories. In addition, the possibility of significantly increasing the LSD detection time window by targeting this major LSD metabolite for analysis may influence other drug-free workplace programs to test for LSD.

High temperature-ultra performance liquid chromatography-mass spectrometry for the metabonomic analysis of Zucker rat urine.

PubMed

Gika, Helen G; Theodoridis, Georgios; Extance, Jon; Edge, Anthony M; Wilson, Ian D

2008-08-15

The applicability and potential of using elevated temperatures and sub 2-microm porous particles in chromatography for metabonomics/metabolomics was investigated using, for the first time, solvent temperatures higher than the boiling point of water (up to 180 degrees C) and thermal gradients to reduce the use of organic solvents. Ultra performance liquid chromatography, combined with mass spectrometry, was investigated for the global metabolite profiling of the plasma and urine of normal and Zucker (fa/fa) obese rats (a well established disease animal model). "Isobaric" high temperature chromatography, where the temperature and flow rate follow a gradient program, was developed and evaluated against a conventional organic solvent gradient. LC-MS data were first examined by established chromatographic criteria in order to evaluate the chromatographic performance and next were treated by special peak picking algorithms to allow the application of multivariate statistics. These studies showed that, for urine (but not plasma), chromatography at elevated temperatures provided better results than conventional reversed-phase LC with higher peak capacity and better peak asymmetry. From a systems biology point of view, better group clustering and separation was obtained with a larger number of variables of high importance when using high temperature-ultra performance liquid chromatography (HT-UPLC) compared to conventional solvent gradients.

A strategy for identification and structural characterization of compounds from Gardenia jasminoides by integrating macroporous resin column chromatography and liquid chromatography-tandem mass spectrometry combined with ion-mobility spectrometry.

PubMed

Wang, Lu; Liu, Shu; Zhang, Xueju; Xing, Junpeng; Liu, Zhiqiang; Song, Fengrui

2016-06-24

In this paper, an analysis strategy integrating macroporous resin (AB-8) column chromatography and high performance liquid chromatography-electrospray ionization-tandem mass spectrometry (HPLC-ESI-MS/MS) combined with ion mobility spectrometry (IMS) was proposed and applied for identification and structural characterization of compounds from the fruits of Gardenia jasminoides. The extracts of G. jasminoides were separated by AB-8 resin column chromatography combined with reversed phase liquid chromatography (C18 column) and detected by electrospray ionization tandem mass spectrometry. Additionally, ion mobility spectrometry (IMS) was employed as a supplementary separation technique to discover previously undetected isomers from the fruits of G. jasminoides. A total of 71 compounds, including iridoids, flavonoids, triterpenes, monoterpenoids, carotenoids and phenolic acids were identified by the characteristic high resolution mass spectrometry and the ESI-MS/MS fragmentations. In conclusion, the IMS-MS technique achieved the separation of isomers in crocin-3 and crocin-4 according to their acquired mobility drift times differing from classical analysis by mass spectrometry. The proposed strategy can be used as a highly sensitive and efficient procedure for identification and separation isomeric components in extracts of herbal medicines. Copyright © 2016 Elsevier B.V. All rights reserved.

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)

Analysis of CYP3A inhibitory components of star fruit (Averrhoa carambola L.) using liquid chromatography-mass spectrometry.

PubMed

Hosoi, Shinzo; Shimizu, Eri; Arimori, Kazuhiko; Okumura, Manabu; Hidaka, Muneaki; Yamada, Mitsuko; Sakushima, Akiyo

2008-07-01

In this study, we analyzed the CYP3A inhibitory components of star fruit Averrhoa carambola L., using liquid chromatography-mass spectrometry (LC-MS). The stereoisomer of procyanidin B1 and B2 and/or the trimer consisting of catechin and/or epicatechin were suggested to be potent inhibitory components.

POLAR ORGANIC CHEMICAL INTEGRATIVE SAMPLING AND LIQUID CHROMATOGRAPHY-ELECTROSPRAY/ION-TRAP MASS SPECTROMETRY FOR ASSESSING SELECTED PRESCRIPTION AND ILLICIT DRUGS IN TREATED SEWAGE EFFLUENTS

EPA Science Inventory

The purpose of the research presented in this paper is two-fold: (1) to demonstrate the 4 coupling of two state-of-the-art techniques: a time-weighted polar organic integrative sampler (POCIS) and micro-liquid chromatography-electrospray/ion trap mass spectrometry (u-LC-6 ES/ITMS...

Ultra-performance liquid chromatography tandem mass-spectrometry (uplc-ms/ms) for the rapid, simultaneous analysis of thiamin, riboflavin, flavin adenine dinucleotide, nicotinamide and pyridoxal in human milk

USDA-ARS?s Scientific Manuscript database

A novel, rapid and sensitive Ultra Performance Liquid-Chromatography tandem Mass-Spectrometry (UPLC-MS/MS) method for the simultaneous determination of several B-vitamins in human milk was developed. Resolution by retention time or multiple reaction monitoring (MRM) for thiamin, riboflavin, flavin a...

Observation of T-2 and HT-2 glucosides from Fusarium sporotrichioides by liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS)

USDA-ARS?s Scientific Manuscript database

Cultures of Fusarium sporotrichioides were extracted and subjected to evaluation by high performance liquid chromatography – tandem mass spectrometry (LC-MS/MS). Along with the expected T-2 and HT-2 toxins, compounds 162 m/z higher than the toxins were observed. Fragmentation behavior of the larger ...

Review of Peak Detection Algorithms in Liquid-Chromatography-Mass Spectrometry

PubMed Central

Zhang, Jianqiu; Gonzalez, Elias; Hestilow, Travis; Haskins, William; Huang, Yufei

2009-01-01

In this review, we will discuss peak detection in Liquid-Chromatography-Mass Spectrometry (LC/MS) from a signal processing perspective. A brief introduction to LC/MS is followed by a description of the major processing steps in LC/MS. Specifically, the problem of peak detection is formulated and various peak detection algorithms are described and compared. PMID:20190954

Production of Reactive Oxygen Species by Polyhalogenated Cyclic Hydrocarbons (PCH)

DTIC Science & Technology

1991-07-22

dry ice in metabolism cages. One ml aliquots of urine were derivatized with 2,4- dinitrophenylhydrazine , and extracted with pentane. The hydrazones of...U.S.A. Key Words: formaldehyde; acetaldehyde; malondialdehyde; acetone; high pressure liquid chromatography; 2,4- dinitrophenylhydrazine ; gas... dinitrophenylhydrazine , and extracted with pentane. The hydrazones of the four lipid metabolic products were quantitated by high pressure liquid chromatography

IDENTIFICATION OF MICROCYSTIN TOXINS FROM A STRAIN OF MICROCYSTIS AERUGINOSA BY LIQUID CHROMATOGRAPHY INTRODUCTION INTO A HYBRID LINEAR ION TRAP-FOURIER TRANSFORM ION CYCLOTRON RESONANCE MASS SPECTROMETER

EPA Science Inventory

The cyclic heptapeptide microcystin toxins produced by a strain of Microcystis aeruginosa that has not been investigated previously were separated by liquid chromatography and identified by high-accuracy m/z measurements of their [M + H]+ ions and the fragment i...

Analysis of swainsonine and swainsonine N-oxide as trimethylsilyl derivatives by Liquid Chromatography-Mass Spectrometry and their relative occurrence in plants toxic to livestock

USDA-ARS?s Scientific Manuscript database

A liquid chromatography-mass spectrometry method was developed for the analysis of the indolizidine alkaloid swainsonine and its N-oxide. The method is based on a one step solvent partitioning extraction procedure followed by trimethylsilylation of the dried extract and subsequent detection and qua...

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...

Ultramicroelectrode Sensors and Detectors. Considerations of the Stability, Sensitivity, Reproducibility, and Mechanism of Ion Transport in Gas Phase Chromatography and in High Performance Liquid Phase Chromatography

DTIC Science & Technology

1988-07-15

solvents were used. For high performance liquid chromatographic studies, the DNA bases thymine, adenine, cytocine, uracil, and guanine (Aldrich...this experiment. The DNA bases guanine, adenine, cytocine, uracil, and thymine were detected for a gradient elution of a mixture of the bases in a

The use of ultra-high pressure liquid chromatography with tandem mass spectrometric detection of analysis of agrochemical residues and mycotoxines in food - challenges and applications

USDA-ARS?s Scientific Manuscript database

In the field of food contaminant analysis, the most significant development of recent years has been the integration of ultra-high pressure liquid chromatography (UHPLC), coupled to tandem quadrupole mass spectrometry (MS/MS), into analytical applications. In this review, we describe the emergence o...

METHOD 544. DETERMINATION OF MICROCYSTINS AND NODULARIN IN DRINKING WATER BY SOLID PHASE EXTRACTION AND LIQUID CHROMATOGRAPHY/TANDEM MASS SPECTROMETRY (LC/MS/MS)

EPA Science Inventory

Method 544 is an accurate and precise analytical method to determine six microcystins (including MC-LR) and nodularin in drinking water using solid phase extraction and liquid chromatography tandem mass spectrometry (SPE-LC/MS/MS). The advantage of this SPE-LC/MS/MS is its sensi...

ON-SITE SOLID-PHASE EXTRACTION AND LABORATORY ANALYSIS OF ULTRA-TRACE SYNTHETIC MUSKS IN MUNICIPAL SEWAGE EFFLUENT USING GAS CHROMATOGRAPHY-MASS SPECTROMETRY IN THE FULL-SCAN MODE

EPA Science Inventory

Fragrance materials such as synthetic musks in aqueous samples, are normally determined by gas chromatography/mass spectrometry in the selected ion monitoring (SIM) mode to provide maximum sensitivity after liquid-liquid extraction of I -L samples. Full-scan mass spectra are requ...

Detection of Stimulants and Narcotics by Liquid Chromatography-Tandem Mass Spectrometry and Gas Chromatography-Mass Spectrometry for Sports Doping Control.

PubMed

Ahrens, Brian D; Kucherova, Yulia; Butch, Anthony W

2016-01-01

Sports drug testing laboratories are required to detect several classes of compounds that are prohibited at all times, which include anabolic agents, peptide hormones, growth factors, beta-2 agonists, hormones and metabolic modulators, and diuretics/masking agents. Other classes of compounds such as stimulants, narcotics, cannabinoids, and glucocorticoids are also prohibited, but only when an athlete is in competition. A single class of compounds can contain a large number of prohibited substances and all of the compounds should be detected by the testing procedure. Since there are almost 70 stimulants on the prohibited list it can be a challenge to develop a single screening method that will optimally detect all the compounds. We describe a combined liquid chromatography-tandem mass spectrometry (LC-MS/MS) and gas chromatography-mass spectrometry (GC-MS) testing method for detection of all the stimulants and narcotics on the World Anti-Doping Agency prohibited list. Urine for LC-MS/MS testing does not require sample pretreatment and is a direct dilute and shoot method. Urine samples for the GC-MS method require a liquid-liquid extraction followed by derivatization with trifluoroacetic anhydride.

Peptide profiling of Internet-obtained Cerebrolysin using high performance liquid chromatography - electrospray ionization ion trap and ultra high performance liquid chromatography - ion mobility - quadrupole time of flight mass spectrometry.

PubMed

Gevaert, Bert; D'Hondt, Matthias; Bracke, Nathalie; Yao, Han; Wynendaele, Evelien; Vissers, Johannes Petrus Cornelis; De Cecco, Martin; Claereboudt, Jan; De Spiegeleer, Bart

2015-09-01

Cerebrolysin, a parenteral peptide preparation produced by controlled digestion of porcine brain proteins, is an approved nootropic medicine in some countries. However, it is also easily and globally available on the Internet. Nevertheless, until now, its exact chemical composition was unknown. Using high performance liquid chromatography (HPLC) coupled to ion trap and ultra high performance liquid chromatography (UHPLC) coupled to quadrupole-ion mobility-time-of-flight mass spectrometry (Q-IM-TOF MS), combined with UniProt pig protein database search and PEAKS de novo sequencing, we identified 638 unique peptides in an Internet-obtained Cerebrolysin sample. The main components in this sample originate from tubulin alpha- and beta-chain, actin, and myelin basic protein. No fragments of known neurotrophic factors like glial cell-derived neurotrophic factor (GDNF), neurotrophin nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), and ciliary neurotrophic factor (CNTF) were found, suggesting that the activities reported in the literature are likely the result of new, hitherto unknown cryptic peptides with nootropic properties. Copyright © 2015 John Wiley & Sons, Ltd.

Detection of AGXT bgene mutations by denaturing high-performance liquid chromatography for diagnosis of hyperoxaluria type 1.

PubMed

Pirulli, D; Giordano, M; Lessi, M; Spanò, A; Puzzer, D; Zezlina, S; Boniotto, M; Crovella, S; Florian, F; Marangella, M; Momigliano-Richiardi, P; Savoldi, S; Amoroso, A

2001-06-01

Primary hyperoxaluria type 1 is an autosomal recessive disorder of glyoxylate metabolism, caused by a deficiency of alanine:glyoxylate aminotransferase, which is encoded by a single copy gene (AGXT. The aim of this research was to standardize denaturing high-performance liquid chromatography, a new, sensitive, relatively inexpensive, and automated technique, for the detection of AGXT mutation. Denaturing high-performance liquid chromatography was used to analyze in blind the AGXT gene in 20 unrelated Italian patients with primary hyperoxaluria type I previously studied by other standard methods (single-strand conformation polymorphism analysis and direct sequencing) and 50 controls. Denaturing high-performance liquid chromatography allowed us to identify 13 mutations and the polymorphism at position 154 in exon I of the AGXT gene. Hence the method is more sensitive and less time consuming than single-strand conformation polymorphism analysis for the detection of AGXT mutations, thus representing a useful and reliable tool for detecting the mutations responsible for primary hyperoxaluria type 1. The new technology could also be helpful in the search for healthy carriers of AGXT mutations amongst family members and their partners, and for screening of AGXT polymorphisms in patients with nephrolithiasis and healthy populations.

Recent development in liquid chromatography stationary phases for separation of Traditional Chinese Medicine components.

PubMed

Jin, Hongli; Liu, Yanfang; Guo, Zhimou; Wang, Jixia; Zhang, Xiuli; Wang, Chaoran; Liang, Xinmiao

2016-10-25

Traditional Chinese Medicine (TCM) is an ancient medical practice which has been used to prevent and cure diseases for thousands of years. TCMs are frequently multi-component systems with mainly unidentified constituents. The study of the chemical compositions of TCMs remains a hotspot of research. Different strategies have been developed to manage the significant complexity of TCMs, in an attempt to determine their constituents. Reversed-phase liquid chromatography (RPLC) is still the method of choice for the separation of TCMs, but has many problems related to limited selectivity. Recently, enormous efforts have been concentrated on the development of efficient liquid chromatography (LC) methods for TCMs, based on selective stationary phases. This can improve the resolution and peak capacity considerably. In addition, high-efficiency stationary phases have been applied in the analysis of TCMs since the invention of ultra high-performance liquid chromatography (UHPLC). This review describes the advances in LC methods in TCM research from 2010 to date, and focuses on novel stationary phases. Their potential in the separation of TCMs using relevant applications is also demonstrated. Copyright © 2016 Elsevier B.V. All rights reserved.

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

PubMed

Turak, Fatma; Güzel, Remziye; Dinç, Erdal

2017-04-01

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

Development, validation and application of a hydrophilic interaction liquid chromatography-evaporative light scattering detection based method for process control of hydrolysis of xylans obtained from different agricultural wastes.

PubMed

Li, Fangbing; Wang, Hui; Xin, Huaxia; Cai, Jianfeng; Fu, Qing; Jin, Yu

2016-12-01

Purified standards of xylooligosaccharides (XOSs) (DP2-6) were first prepared from a mixture of XOSs using solid phase extraction (SPE), followed by semi-preparative liquid chromatography both under hydrophilic interaction liquid chromatography (HILIC) modes. Then, an accurate quantitative analysis method based on hydrophilic interaction liquid chromatography-evaporative light scattering detection (HILIC-ELSD) was developed and validated for simultaneous determination of xylose (X1), xylobiose (X2), xylotriose (X3), xylotetraose (X4), xylopentaose (X5), and xylohexaose (X6). This developed HILIC-ELSD method was applied to the comparison of different hydrolysis methods for xylans and assessment of XOSs contents from different agricultural wastes. The result indicated that enzymatic hydrolysis was preferable with fewer by-products and high XOSs yield. The XOSs yield (48.40%) from sugarcane bagasse xylan was the highest, showing conversions of 11.21g X2, 12.75g X3, 4.54g X4, 13.31g X5, and 6.78g X6 from 100g xylan. Copyright © 2016 Elsevier Ltd. All rights reserved.

GLC analysis of base composition of RNA and DNA hydrolysates

NASA Technical Reports Server (NTRS)

Lakings, D. B.; Gehreke, C. W.

1971-01-01

Various methods used for the analysis of the base composition of RNA and DNA hydrolysates are presented. The methods discussed are: (1) ion-exchange chromatography, (2) paper chromatography, (3) paper electrophoresis, (4) thin layer chromatography, (5) paper chromatography and time of flight mass spectrometry, and (6) gas-liquid chromatography. The equipment required and the conditions for obtaining the best results with each method are described.

Relative quantitative comparisons of the extracellular protein profiles of Staphylococcus aureus UAMS-1 and its sarA, agr, and sarA agr regulatory mutants using one-dimensional polyacrylamide gel electrophoresis and nanocapillary liquid chromatography coupled with tandem mass spectrometry.

PubMed

Jones, Richard C; Deck, Joanna; Edmondson, Ricky D; Hart, Mark E

2008-08-01

One-dimensional polyacrylamide gel electrophoresis followed by nanocapillary liquid chromatography coupled with mass spectrometry was used to analyze proteins isolated from Staphylococcus aureus UAMS-1 after 3, 6, 12, and 24 h of in vitro growth. Protein abundance was determined using a quantitative value termed normalized peptide number, and overall, proteins known to be associated with the cell wall were more abundant early on in growth, while proteins known to be secreted into the surrounding milieu were more abundant late in growth. In addition, proteins from spent media and cell lysates of strain UAMS-1 and its isogenic sarA, agr, and sarA agr regulatory mutant strains during exponential growth were identified, and their relative abundances were compared. Extracellular proteins known to be regulated by the global regulators sarA and agr displayed protein levels in accordance with what is known regarding the effects of these regulators. For example, cysteine protease (SspB), endopeptidase (SspA), staphopain (ScpA), and aureolysin (Aur) were higher in abundance in the sarA and sarA agr mutants than in strain UAMS-1. The immunoglobulin G (IgG)-binding protein (Sbi), immunodominant staphylococcal antigen A (IsaA), IgG-binding protein A (Spa), and the heme-iron-binding protein (IsdA) were most abundant in the agr mutant background. Proteins whose abundance was decreased in the sarA mutant included fibrinogen-binding protein (Fib [Efb]), IsaA, lipase 1 and 2, and two proteins identified as putative leukocidin F and S subunits of the two-component leukotoxin family. Collectively, this approach identified 1,263 proteins (matches of two peptides or more) and provided a convenient and reliable way of identifying proteins and comparing their relative abundances.

Effect of pressure pulses at the interface valve on the stability of second dimension columns in online comprehensive two-dimensional liquid chromatography.

PubMed

Talus, Eric S; Witt, Klaus E; Stoll, Dwight R

2015-01-23

Users of online comprehensive two-dimensional liquid chromatography (LCxLC) frequently acknowledge that the mechanical instability of HPLC columns installed in these systems, particularly in the second dimension, is a significant impediment to its use. Such instability is not surprising given the strenuous operating environment to which these columns are subjected, including the large number (thousands per day) of fast and large pressure pulses resulting from interface valve switches (on the timescale of tens of milliseconds) associated with very fast second dimension separations. There appear to be no published reports of systematic studies of the relationship between second dimension column lifetime and any of these variables. In this study we focused on the relationship between the lifetimes of commercially available columns and the pressure pulses observed at the inlet of the second dimension column that occur during the switching of the valve that interfaces the two dimensions of a LCxLC system. We find that the magnitude of the pressure drop at the inlet of the second dimension column during the valve switch, which may vary between 10 and 95% of the column inlet pressure, is dependent on valve switching speed and design, and has a dramatic impact on column lifetime. In the worst case, columns fail within the first few hours of use in an LCxLC system. In the best case, using a valve that exhibits much smaller pressure pulses, the same columns exhibit much improved lifetimes and have been used continuously under LCxLC conditions for several days with no degradation in performance. This result represents a first step in understanding the factors that affect second dimension column lifetime, and will significantly improve the usability of the LCxLC technique in general. Copyright © 2014 Elsevier B.V. All rights reserved.

Proteomic analysis of tears following acupuncture treatment for menopausal dry eye disease by two-dimensional nano-liquid chromatography coupled with tandem mass spectrometry.

PubMed

Liu, Qingyu; Liu, Junling; Ren, Chengda; Cai, Wenting; Wei, Qingquan; Song, Yi; Yu, Jing

2017-01-01

The purpose of this study was to investigate whether acupuncture is effective at treating dry eye disease among postmenopausal women and to identify the possible mechanisms. Twenty-eight postmenopausal women with dry eye disease were randomly divided into two groups: an acupuncture plus artificial tears (AC + AT) group and an artificial tears (AT) only group. After baseline examination of clinical parameters and tear sample collection, each patient received the designated modality of topical therapy for 2 months. Post-treatment documentation of clinical parameters was recorded, and tear samples were collected. Tear samples from the AC + AT group were subjected to two-dimensional nano-liquid chromatography coupled with tandem mass spectrometry (2D nano-LC-MS/MS). Western blot analysis was also performed on tear samples from both groups. After treatment, the Ocular Surface Disease Index scores, symptom assessment scores, scores of sign assessment, and tear break-up time were significantly improved in both groups ( P =0.000). Symptom assessment scores were significantly improved in the AC + AT group ( P =0.000) compared with the AT group. 2D nano-LC-MS/MS identified 2,411 proteins, among which 142 were downregulated and 169 were upregulated. After combined AC + AT treatment, the abundance of secreted proteins was increased, whereas that of cytoplasmic proteins decreased (Pearson's χ 2 test, P =0.000, P =0.000, respectively). Proteins involved in immunity and regulation were also more abundant (Pearson's χ 2 test, P =0.040, P =0.016, respectively), while components and proliferation-related proteins were downregulated (Pearson's χ 2 test, P =0.003, P =0.011, respectively). AC + AT treatment increased protein synthesis and secretion, and improved clinical symptoms. These results indicate that acupuncture may be a complimentary therapy for treating postmenopausal dry eye disease.

The Proteome of Seed Development in the Model Legume Lotus japonicus1[C][W

PubMed Central

Dam, Svend; Laursen, Brian S.; Ørnfelt, Jane H.; Jochimsen, Bjarne; Stærfeldt, Hans Henrik; Friis, Carsten; Nielsen, Kasper; Goffard, Nicolas; Besenbacher, Søren; Krusell, Lene; Sato, Shusei; Tabata, Satoshi; Thøgersen, Ida B.; Enghild, Jan J.; Stougaard, Jens

2009-01-01

We have characterized the development of seeds in the model legume Lotus japonicus. Like soybean (Glycine max) and pea (Pisum sativum), Lotus develops straight seed pods and each pod contains approximately 20 seeds that reach maturity within 40 days. Histological sections show the characteristic three developmental phases of legume seeds and the presence of embryo, endosperm, and seed coat in desiccated seeds. Furthermore, protein, oil, starch, phytic acid, and ash contents were determined, and this indicates that the composition of mature Lotus seed is more similar to soybean than to pea. In a first attempt to determine the seed proteome, both a two-dimensional polyacrylamide gel electrophoresis approach and a gel-based liquid chromatography-mass spectrometry approach were used. Globulins were analyzed by two-dimensional polyacrylamide gel electrophoresis, and five legumins, LLP1 to LLP5, and two convicilins, LCP1 and LCP2, were identified by matrix-assisted laser desorption ionization quadrupole/time-of-flight mass spectrometry. For two distinct developmental phases, seed filling and desiccation, a gel-based liquid chromatography-mass spectrometry approach was used, and 665 and 181 unique proteins corresponding to gene accession numbers were identified for the two phases, respectively. All of the proteome data, including the experimental data and mass spectrometry spectra peaks, were collected in a database that is available to the scientific community via a Web interface (http://www.cbs.dtu.dk/cgi-bin/lotus/db.cgi). This database establishes the basis for relating physiology, biochemistry, and regulation of seed development in Lotus. Together with a new Web interface (http://bioinfoserver.rsbs.anu.edu.au/utils/PathExpress4legumes/) collecting all protein identifications for Lotus, Medicago, and soybean seed proteomes, this database is a valuable resource for comparative seed proteomics and pathway analysis within and beyond the legume family. PMID:19129418

Acrylamide: formation, occurrence in food products, detection methods, and legislation.

PubMed

Arvanitoyannis, Ioannis S; Dionisopoulou, Niki

2014-01-01

This review aims at summarizing the most recent updates in the field of acrylamide (AA) formation (mechanism, conditions) and the determination of AA in a number of foods (fried or baked potatoes, chips, coffee, bread, etc). The methods applied for AA detection [Capillary Electrophoresis-Mass Spectrometry (CE-MS), Liquid Chromatography-Mass Spectrometry (LC-MS), Non-Aqueous Capillary Electrophoresis (NACE), High Performance Liquid Chromatography-Mass Spectrometry (HPLC-MS), Pressurized Fluid Extraction (PFE), Matrix Solid-Phase Dispersion (MSPD), Gas Chromatography-Mass Spectrometry (GC-MS), Solid-Phase MicroExtraction-Gas Chromatography (SPME-GC), Enzyme Linked Immunosorbent Assay (ELISA), and MicroEmulsion ElectroKinetic Chromatography (MEEKC) are presented and commented. Several informative figures and tables are included to show the effect of conditions (temperature, time) on the AA formation. A section is also included related to AA legislation in EU and US.

Silica, hybrid silica, hydride silica and non-silica stationary phases for liquid chromatography.

PubMed

Borges, Endler M

2015-04-01

Free silanols on the surface of silica are the "villains", which are responsible for detrimental interactions of those compounds and the stationary phase (i.e., bad peak shape, low efficiency) as well as low thermal and chemical stability. For these reasons, we began this review describing new silica and hybrid silica stationary phases, which have reduced and/or shielded silanols. At present, in liquid chromatography for the majority of analyses, reversed-phase liquid chromatography is the separation mode of choice. However, the needs for increased selectivity and increased retention of hydrophilic bases have substantially increased the interest in hydrophilic interaction chromatography (HILIC). Therefore, stationary phases and this mode of separation are discussed. Then, non-silica stationary phases (i.e., zirconium oxide, titanium oxide, alumina and porous graphitized carbon), which afford increased thermal and chemical stability and also selectivity different from those obtained with silica and hybrid silica, are discussed. In addition, the use of these materials in HILIC is also reviewed. © Crown copyright 2014.

Simultaneous quantification of four native estrogen hormones at trace levels in human cerebrospinal fluid using liquid chromatography-tandem mass spectrometry.

PubMed

Nguyen, Hien P; Li, Li; Gatson, Joshua W; Maass, David; Wigginton, Jane G; Simpkins, James W; Schug, Kevin A

2011-03-25

Estrogens are known to exhibit neuroprotective effects on the brain. Their importance in this regard and in others has been emphasized in many recent studies, which increases the need to develop reliable analytical methods for the measurement of estrogen hormones. A heart-cutting two-dimensional liquid chromatography separation method coupled with electrospray ionization-tandem mass spectrometry (ESI-MS/MS) has been developed for simultaneous measurement of four estrogens, including estriol (E3), estrone (E1), 17β-estradiol (17β-E2), and 17α-estradiol (17α-E2), in human cerebrospinal fluid (CSF). The method was based on liquid-liquid extraction and derivatization of estrogens with dansyl chloride to enhance the sensitivity of ESI-based detection in conjunction with tandem mass spectrometry. Dansylated estriol and estrone were separated in the first dimension by an amide-C18 column, while dansylated 17β- and 17α-estradiol were resolved on the second dimension by two C18 columns (175 mm total length) connected in series. This is the first report of a method for simultaneous quantification of all four endogenous estrogen compounds in their dansylated form. The detection limits for E1, 17α-E2, 17β-E2, and E3 were 19, 35, 26, and 61pg/mL, respectively. Due to matrix effects, validation and calibration was carried out in charcoal-stripped CSF. The precision and accuracy were more than 86% for the two E2 compounds and 79% for E1 and E3 while the extraction recovery ranged from 91% to 104%. The method was applied to measure estrogens obtained in a clinical setting, from the CSF of ischemic trauma patients. While 17β-estradiol was present at a significant level in the CSF of some samples, other estrogens were present at lower levels or were undetectable. Copyright © 2010 Elsevier B.V. All rights reserved.

Improved selectivity for high-performance liquid chromatographic determination of clonazepam in plasma of epileptic patients.

PubMed

Le Guellec, C; Gaudet, M L; Breteau, M

1998-11-20

We report a high-performance liquid chromatography method for clonazepam determination in plasma. The use of a synthetic silica-based stationary phase markedly improved clonazepam resolution compared to standard reversed-phase columns. A liquid-liquid extraction was used, associated with reversed-phase chromatography, gradient elution and ultraviolet detection. Accuracy and precision were satisfactory at therapeutic concentrations. Selectivity was studied for benzodiazepines or other antiepileptic drugs, with particular attention to newly marketed drugs i.e., gabapentine and vigabatrin. No interfering substance was evidenced. Under the conditions described, it was possible to quantify clonazepam at nanogram level even when carbamazepine was present at therapeutic concentrations.

Detection of volatile spoilage metabolites in fermented cucumbers using nontargeted, comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry (GCxGC-TOFMS)

USDA-ARS?s Scientific Manuscript database

A nontargeted, comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry (GCxGC-TOFMS) method was developed for the analysis of fermented cucumber volatiles before and after anaerobic spoilage. Volatiles extracted by solid-phase microextraction were separated on a polyethyle...

Large-Scale and Deep Quantitative Proteome Profiling Using Isobaric Labeling Coupled with Two-Dimensional LC-MS/MS

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

Gritsenko, Marina A.; Xu, Zhe; Liu, Tao

Comprehensive, quantitative information on abundances of proteins and their post-translational modifications (PTMs) can potentially provide novel biological insights into diseases pathogenesis and therapeutic intervention. Herein, we introduce a quantitative strategy utilizing isobaric stable isotope-labelling techniques combined with two-dimensional liquid chromatography-tandem mass spectrometry (2D-LC-MS/MS) for large-scale, deep quantitative proteome profiling of biological samples or clinical specimens such as tumor tissues. The workflow includes isobaric labeling of tryptic peptides for multiplexed and accurate quantitative analysis, basic reversed-phase LC fractionation and concatenation for reduced sample complexity, and nano-LC coupled to high resolution and high mass accuracy MS analysis for high confidence identification andmore » quantification of proteins. This proteomic analysis strategy has been successfully applied for in-depth quantitative proteomic analysis of tumor samples, and can also be used for integrated proteome and PTM characterization, as well as comprehensive quantitative proteomic analysis across samples from large clinical cohorts.« less

Proteomic analysis of protein deposits on worn daily wear silicone hydrogel contact lenses

PubMed Central

Wei, Xiaojia; Aliwarga, Yulina; Carnt, Nicole A.; Garrett, Qian; Willcox, Mark D.P.

2008-01-01

Purpose Previous studies have demonstrated deposition of tear proteins onto worn contact lenses. In this study, we used proteomic techniques to analyze the protein deposits extracted from worn daily wear silicone hydrogel contact lenses in combination with different lens care solutions. Methods Worn lenses were collected and protein deposits extracted using urea and surfactant. Protein extracts were desalted, concentrated, and then separated using one-dimensional gel electrophoresis. Individual protein components in extracts were identified using liquid chromatography combined with tandem mass spectrometry (LC-MS-MS) after trypsin digestion. Results One-dimensional gel electrophoresis revealed that lysozyme and other small proteins (around 20 kDa) were the most abundant proteins in the extracts. LC-MS-MS revealed a wide array of proteins in lens extracts with lysozyme and lipocalin 1 being the most commonly identified in deposit extracts. Conclusions Worn contact lenses deposit a wide array of proteins from tear film and other sources. Protein deposit profiles varied and were specific for each contact lens material. PMID:18989384

Large-Scale and Deep Quantitative Proteome Profiling Using Isobaric Labeling Coupled with Two-Dimensional LC-MS/MS.

PubMed

Gritsenko, Marina A; Xu, Zhe; Liu, Tao; Smith, Richard D

2016-01-01

Comprehensive, quantitative information on abundances of proteins and their posttranslational modifications (PTMs) can potentially provide novel biological insights into diseases pathogenesis and therapeutic intervention. Herein, we introduce a quantitative strategy utilizing isobaric stable isotope-labeling techniques combined with two-dimensional liquid chromatography-tandem mass spectrometry (2D-LC-MS/MS) for large-scale, deep quantitative proteome profiling of biological samples or clinical specimens such as tumor tissues. The workflow includes isobaric labeling of tryptic peptides for multiplexed and accurate quantitative analysis, basic reversed-phase LC fractionation and concatenation for reduced sample complexity, and nano-LC coupled to high resolution and high mass accuracy MS analysis for high confidence identification and quantification of proteins. This proteomic analysis strategy has been successfully applied for in-depth quantitative proteomic analysis of tumor samples and can also be used for integrated proteome and PTM characterization, as well as comprehensive quantitative proteomic analysis across samples from large clinical cohorts.

Determination of diacylhydrazines-type insect growth regulator JS-118 residues in cabbage and soil by high performance liquid chromatography with DAD detection.

PubMed

Hu, J-Y; Deng, Z-B; Qin, D-M

2009-12-01

JS-118 is a diacylhydrazines-type insect growth regulator used extensively in China now. An analytical method for residues determination of JS-118 in cabbage and soil samples by high performance liquid chromatography with DAD detection was established and optimized. Primary secondary amine solid phase extraction cartridge was used for sample preparation. Mean recoveries for the analyte ranged from 96.6% to 107.0% with CV value less than 4.7%. The limit of quantification is 0.01 mg/kg. Direct confirmation of JS-118 residues in samples was realized by high performance liquid chromatography-mass spectrometry. The proposed method is simple, rapid and reliable to perform and could be utilized for monitoring of pesticides residues.

Identifying Ca2+-Binding Sites in Proteins by Liquid Chromatography-Mass Spectrometry Using Ca2+-Directed Dissociations

PubMed Central

Jamalian, Azadeh; Sneekes, Evert-Jan; Wienk, Hans; Dekker, Lennard J. M.; Ruttink, Paul J. A.; Ursem, Mario; Luider, Theo M.; Burgers, Peter C.

2014-01-01

Here we describe a new method to identify calcium-binding sites in proteins using high-resolution liquid chromatography-mass spectrometry in concert with calcium-directed collision-induced dissociations. Our method does not require any modifications to the liquid chromatography-mass spectrometry apparatus, uses standard digestion protocols, and can be applied to existing high-resolution MS data files. In contrast to NMR, our method is applicable to very small amounts of complex protein mixtures (femtomole level). Calcium-bound peptides can be identified using three criteria: (1) the calculated exact mass of the calcium containing peptide; (2) specific dissociations of the calcium-containing peptide from threonine and serine residues; and (3) the very similar retention times of the calcium-containing peptide and the free peptide. PMID:25023127

Peak picking and the assessment of separation performance in two-dimensional high performance liquid chromatography.

PubMed

Stevenson, Paul G; Mnatsakanyan, Mariam; Guiochon, Georges; Shalliker, R Andrew

2010-07-01

An algorithm was developed for 2DHPLC that automated the process of peak recognition, measuring their retention times, and then subsequently plotting the information in a two-dimensional retention plane. Following the recognition of peaks, the software then performed a series of statistical assessments of the separation performance, measuring for example, correlation between dimensions, peak capacity and the percentage of usage of the separation space. Peak recognition was achieved by interpreting the first and second derivatives of each respective one-dimensional chromatogram to determine the 1D retention times of each solute and then compiling these retention times for each respective fraction 'cut'. Due to the nature of comprehensive 2DHPLC adjacent cut fractions may contain peaks common to more than one cut fraction. The algorithm determined which components were common in adjacent cuts and subsequently calculated the peak maximum profile by interpolating the space between adjacent peaks. This algorithm was applied to the analysis of a two-dimensional separation of an apple flesh extract separated in a first dimension comprising a cyano stationary phase and an aqueous/THF mobile phase as the first dimension and a second dimension comprising C18-Hydro with an aqueous/MeOH mobile phase. A total of 187 peaks were detected.

Determination of chlorophenols in honey samples using in-situ ionic liquid-dispersive liquid-liquid microextraction as a pretreatment method followed by high-performance liquid chromatography.

PubMed

Fan, Chen; Li, Nai; Cao, Xueli

2015-05-01

In-situ ionic liquid-dispersive liquid-liquid microextraction (IL-DLLME) method was developed as a pretreatment method for the detection of six chlorophenols (CPs) in honey samples. The hydrophobic ionic liquid [C4MIM][NTf2], formed in-situ by the hydrophilic ionic liquid [C4MIM][BF4] and the ion exchange reagent LiNTf2 was used as the microextractant solvent of CPs from honey sample. Then the enriched analytes were back-extracted into 40 μL of 0.14 M NaOH solution and finally subjected to analysis by high-performance liquid chromatography. The method showed low limit of detection of CPs, 0.8-3.2 μg/L and high enrichment factor, 34-65 with the recoveries range from 91.60% to 114.33%. The method is simple, rapid, environmentally friendly and with high extraction efficiency. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.

Protein separations using enhanced-fluidity liquid chromatography.

PubMed

Bennett, Raffeal; Olesik, Susan V

2017-11-10

Enhanced-fluidity liquid chromatography (EFLC) methods using methanol/H 2 O/CO 2 and hydrophilic interaction liquid chromatography (HILIC) were explored for the separation of proteins and peptides. EFLC is a separation mode that uses a mobile phase made of conventional solvents combined with liquid carbon dioxide (CO 2 ) in subcritical conditions. The addition of liquid CO 2 enhances diffusivity and decreases viscosity while maintaining mixture polarity, which typically results in reduced time of analysis. TFA additive and elevated temperature were leveraged as key factors in the separation of a 13-analyte intact protein mixture in under 5min. Under these conditions EFLC showed modest improvement in terms of peak asymmetry and analysis time over the competing ACN/H 2 O separation. Protein analytes detected by electrospray ionization - quadrupole time of flight, were shown to be unaffected by the addition of CO 2 in the mobile phase. Herein, the feasibility of separating hydrophilic proteins up to 80kDa (with transferrin) is demonstrated for CO 2 -containing mobile phases. Copyright © 2017 Elsevier B.V. All rights reserved.

Determination of parabens in serum by liquid chromatography-tandem mass spectrometry: Correlation with lipstick use.

PubMed

Tahan, Gabriella Padovani; Santos, Nayara de Kássia Souza; Albuquerque, Ana Carolina; Martins, Isarita

2016-08-01

Parabens are the most widely used preservative and are considered to be relatively safe compounds. However, studies have demonstrated that they may have estrogenic activity, and there is ongoing debate regarding the safety and potential cancer risk of using products containing these compounds. In the present work, liquid chromatography-tandem mass spectrometry was applied to determine methylparaben and propylparaben concentrations in serum, and the results were correlated with lipstick application. Samples were analyzed using liquid-liquid extraction, followed by liquid chromatography-tandem mass spectrometry. The validation results demonstrated the linearity of the method over a range of 1-20 ng/mL, in addition to the method's precision and accuracy. A statistically significant difference was demonstrated between serum parabens in women who used lipstick containing these substances compared with those not using this cosmetic (p = 0.0005 and 0.0016, respectively), and a strong association was observed between serum parabens and lipstick use (Spearman correlation = 0.7202). Copyright © 2016 Elsevier Inc. All rights reserved.

Diesel Engine Air Emissions Reduction Technologies

DTIC Science & Technology

2010-04-01

Hour GC/MS Gas Chromatography /Mass Spectroscopy GC/FID Gas Chromatography /Flame Ionization Detector g/mile Gram per Mile HAP Hazardous Air...Pollutant HC Hydrocarbon HPLC/UV High Performance Liquid Chromatography / Ultraviolet KPa Kilo-Pascals NDIR Non Dispersive Infrared... Chromatography (GC) where the samples were collected on DNPH cartridges. Portable versions of these instruments were available and employed for

In situ ionic liquid dispersive liquid-liquid microextraction coupled to gas chromatography-mass spectrometry for the determination of organophosphorus pesticides.

PubMed

Cacho, J I; Campillo, N; Viñas, P; Hernández-Córdoba, M

2018-07-20

Nine organophosphorus pesticides (OPPs) were determined in environmental waters from different origins using in situ ionic liquid dispersive liquid microextraction (IL-DLLME). This preconcentration technique was coupled to gas chromatography-mass spectrometry (GC-MS) using microvial insert thermal desorption, an approach that uses a thermal desorption injector as sample introduction system. The parameters affecting both the microextraction and sample injection steps were optimized. The proposed method showed good precision, with RSD values ranging from 4.1 to 9.7%, accuracy with recoveries in the 85-118% range, and sensitivity with DLs ranging from 5 to 16 ng L -1 . Copyright © 2017 Elsevier B.V. All rights reserved.

Discovery and Synthesis of GS-5734, a Phosphoramidate Prodrug of a Pyrrolo[2,1 f][triazin-4-amino] Adenine C-Nucleoside for the Treatment of Ebola and Emerging Viruses

DTIC Science & Technology

2017-01-26

high- performance liquid chromatography (HPLC) and were greater than 95% unless otherwise noted. HPLC conditions to assess purity were as follows...cell culture plates using a μFlow liquid dispenser and cultured for 4 days at 37 °C. After incubation, the cells were allowed to equilibrate to 25...t1/2) was determined assuming first-order kinetics. LC/MS/MS Instrumentation Liquid chromatography was performed using an Agilent 1200-series

Use of absorbent materials in on-line coupled reversed-phase liquid chromatography-gas chromatography via the through oven transfer adsorption desorption interface.

PubMed

Flores, Gema; Díaz-Plaza, Eva María; Cortés, Jose Manuel; Villén, Jesús; Herraiz, Marta

2008-11-21

The use of absorbents as retaining materials in the through oven transfer adsorption desorption interface (TOTAD) of an on-line coupled reversed-phase liquid chromatography-gas chromatography system (RPLC-GC) is proposed for the first time. A comparative study of an adsorbent (Tenax TA) and two absorbents, namely polydimethylsiloxane and poly(50% phenyl/50% methylsiloxane) is performed to establish the best experimental conditions for the automated and simultaneous determination of 15 organophosphorus and organochlorine pesticide residues in olive oil. The proposed method provides satisfactory repeatability (RSDs lower, in general, than 8.5%) and sensitivity (limits of detection ranging from 0.6 to 81.9 microg/L) for the investigated compounds.

Fast liquid chromatography combined with mass spectrometry for the analysis of metabolites and proteins in human body fluids.

PubMed

Kortz, Linda; Helmschrodt, Christin; Ceglarek, Uta

2011-03-01

In the last decade various analytical strategies have been established to enhance separation speed and efficiency in high performance liquid chromatography applications. Chromatographic supports based on monolithic material, small porous particles, and porous layer beads have been developed and commercialized to improve throughput and separation efficiency. This paper provides an overview of current developments in fast chromatography combined with mass spectrometry for the analysis of metabolites and proteins in clinical applications. Advances and limitations of fast chromatography for the combination with mass spectrometry are discussed. Practical aspects of, recent developments in, and the present status of high-throughput analysis of human body fluids for therapeutic drug monitoring, toxicology, clinical metabolomics, and proteomics are presented.

Review: Current applications and challenges for liquid chromatography coupled to isotope ratio mass spectrometry (LC/IRMS).

PubMed

Godin, Jean-Philippe; McCullagh, James S O

2011-10-30

High-precision isotope analysis is recognized as an essential research tool in many fields of study. Until recently, continuous flow isotope ratio mass spectrometry (CF-IRMS) was available via an elemental analyzer or a gas chromatography inlet system for compound-specific analysis of light stable isotopes. In 2004, however, an interface that coupled liquid chromatography with IRMS (LC/IRMS) became commercially available for the first time. This brought the capability for new areas of application, in particular enabling compound-specific δ(13)C analysis of non-volatile, aqueous soluble, compounds from complex mixtures. The interface design brought with it several analytical constraints, however, in particular a lack of compatibility with certain types of chromatography as well as limited flow rates and mobile phase compositions. Routine LC/IRMS methods have, however, been established for measuring the δ(13)C isotopic ratios of underivatized individual compounds for application in archeology, nutrition and physiology, geochemistry, hydrology, soil science and food authenticity. Seven years after its introduction, we review the technical advances and constraints, methodological developments and new applications of liquid chromatography coupled to isotope ratio mass spectrometry. Copyright © 2011 John Wiley & Sons, Ltd.

Polymer Analysis by Liquid Chromatography/Electrospray Ionization Time-of-Flight Mass Spectrometry.

PubMed

Nielen, M W; Buijtenhuijs, F A

1999-05-01

Hyphenation of liquid chromatography (LC) techniques with electrospray ionization (ESI) orthogonal acceleration time-of-flight (oa-TOF) mass spectrometry (MS) provides both MS-based structural information and LC-based quantitative data in polymer analysis. In one experimental setup, three different LC modes are interfaced with MS:  size-exclusion chromatography (SEC/MS), gradient polymer elution chromatography (GPEC/MS), and liquid chromatography at the critical point of adsorption (LCCC/MS). In SEC/MS, both absolute mass calibration of the SEC column based on the polymer itself and determination of monomers and end groups from the mass spectra are achieved. GPEC/MS shows detailed chemical heterogeneity of the polymer and the chemical composition distribution within oligomer groups. In LCCC/MS, the retention behavior is primarily governed by chemical heterogeneities, such as different end group functionalities, and quantitative end group calculations can be easily made. The potential of these methods and the benefit of time-of-flight analyzers in polymer analysis are discussed using SEC/MS of a polydisperse poly(methyl methacrylate) sample, GPEC/MS of dipropoxylated bisphenol A/adipic acid polyester resin, LCCC/MS of alkylated poly(ethylene glycol), and LCCC/MS of terephthalic acid/neopentyl glycol polyester resin.

Determination of mycotoxins produced by Fusarium isolates from banana fruits by capillary gas chromatography and high-performance liquid chromatography.

PubMed

Jiménez, M; Mateo, R

1997-08-22

A method of analysis for trichothecenes (nivalenol, deoxynivalenol, 3- and 15-acetyldeoxynivalenol, diacetoxyscirpenol, neosolaniol, T-2 tetraol, T-2 and HT-2 toxins), zearalenone and zearalenols, and another method for determination of fumonisin B1 are described and applied to cultures of Fusarium isolated from bananas. Both methods were adapted from different techniques of extraction, clean-up and determination of these mycotoxins. The first method involves extraction with methanol-1% aqueous sodium chloride, clean-up of extracts by partition with hexane and dichloromethane, additional solid reversed-phase clean-up and analysis of two eluates by both high-performance liquid chromatography with ultraviolet detection and capillary gas chromatography. The method for fumonisin B1 implies extraction with aqueous methanol, concentration, clean-up with water and methanol on Amberlite XAD-2 column, formation of a fluorescent 4-fluoro-7-nitrobenzofurazan derivative and analysis by high-performance liquid chromatography with fluorescence detection. Both procedures give good limits of detection and recoveries, and are considered suitable for the detection and quantification of the studied toxins in corn and rice cultures of Fusarium spp. isolated from banana fruits.

Lipidomics in triacylglycerol and cholesteryl ester oxidation.

PubMed

Kuksis, Arnis

2007-05-01

Although direct mass spectrometry is capable of identification the major molecular species of lipids in crude total lipid extracts, prior chromatographic isolation is necessary for detection and identification of the minor components. This is especially important for the analysis of the oxolipids, which usually occur in trace amounts in the total lipid extract, and require prior isolation for detailed analysis. Both thin-layer chromatography and adsorption cartridges provide effective means for isolation and enrichment of lipid classes, while gas-liquid chromatography and high performance liquid chromatography with on-line mass spectrometry permit further separation and identification of molecular species. Prior chromatographic resolution is absolutely necessary for the identification of isobaric and chiral molecules, which mass spectrometry/mass spectrometry (MS/MS) cannot distinguish. Both gas chromatography-mass spectrometry and liquid chromatography-mass spectrometry applications may require the preparation of derivatives in order to improve the chromatographic and mass spectrometric properties of the oxolipids which is a small inconvenience for securing analytical reliability. The following chapter reviews the advantages and necessity of combined chromatographic-mass spectrometric approaches to successful identification and quantification of molecular species of oxoacylglycerols and oxocholesteryl esters in in-vitro model studies of lipid peroxidation and in the analyses of oxolipids recovered from tissues.

Experiments for Modern Introductory Chemistry.

ERIC Educational Resources Information Center

Kildahl, Nicholas; Berka, Ladislav H.

1995-01-01

Presents a headspace gas chromatography experiment that enables discovery of the temperature dependence of the vapor pressure of a pure liquid. Illustrates liquid-vapor phase equilibrium of pure liquids. Contains 22 references. (JRH)

Determination of atenolol in human plasma using ionic-liquid-based ultrasound-assisted in situ solvent formation microextraction followed by high-performance liquid chromatography.

PubMed

Zeeb, Mohsen; Farahani, Hadi; Papan, Mohammad Kazem

2016-06-01

An efficient analytical method called ionic-liquid-based ultrasound-assisted in situ solvent formation microextraction followed by high-performance liquid chromatography was developed for the determination of atenolol in human plasma. A hydrophobic ionic liquid (1-butyl-3-methylimidazolium hexafluorophosphate) was formed by the addition of a hydrophilic ionic liquid (1-butyl-3-methylimidazolium tetrafluoroborate) to a sample solution containing an ion-pairing agent during microextraction. The analyte was extracted into the ionic liquid phase while the microextraction solvent was dispersed throughout the sample by utilizing ultrasound. The sample was then centrifuged, and the extracting phase retracted into the microsyringe and injected to liquid chromatography. After optimization, the calibration curve showed linearity in the range of 2-750 ng/mL with the regression coefficient corresponding to 0.998. The limits of detection (S/N = 3) and quantification (S/N = 10) were 0.5 and 2 ng/mL, respectively. A reasonable relative recovery range of 90-96.7% and satisfactory intra-assay (4.8-5.1%, n = 6) and interassay (5.0-5.6%, n = 9) precision along with a substantial sample clean-up demonstrated good performance of the procedure. It was applied for the determination of atenolol in human plasma after oral administration and some pharmacokinetic data were obtained. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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.

Physicochemical application of capillary chromatography

NASA Astrophysics Data System (ADS)

Vasil'ev, A. V.; Aleksandrov, E. N.

1992-04-01

The application of capillary gas chromatography in the determination of the free energy, enthalpy, and entropy of sorption, the saturated vapour pressure and activity coefficients, the assessment of the lipophilicity of volatile compounds, and the study of the properties of polymers and liquid crystals is described. The use of reaction cappillary chromatography in kinetic studies of conformational conversions, thermal degradation, and photochemical reactions is examined. Studies on the use of capillary columns for determination of the second virial coefficients and viscosity of gases and the diffusion coefficients in gases, liquids, supercritical fluids, and polymers are analysed. The bibliography includes 114 references.

Assay of free and glycine- and taurine-conjugated bile acids in serum by high-pressure liquid chromatography by using post-column reaction after group separation.

PubMed Central

Onishi, S; Itoh, S; Ishida, Y

1982-01-01

An accurate and sensitive method that involves the group separations of serum bile acids (i.e. free and glycine- and taurine-conjugated bile acid fractions) by ion-exchange chromatography on piperidinohydroxypropyl-Sephadex LH-20 is described. Each group was then analysed by high-pressure liquid chromatography by using the post-column reaction technique with immobilized 3 alpha-hydroxy steroid dehydrogenase. The bile acid patterns in the umbilical venous serum samples were analysed by this method. Taurochenodeoxycholate predominated in the umbilical blood. PMID:6956336

[Blood levels of homocysteine by high pressure liquid chromatography and comparison with two other techniques].

PubMed

Ceppa, F; Drouillard, I; Chianea, D; Burnat, P; Perrier, F; Vaillant, C; El Jahiri, Y

1999-01-01

Cardio-vascular diseases are the most common cause of death in industrialized countries. A new marker has emerged among offending risk factors in the past few years: homocysteine. This sulphured amino-acid is an important intermediate in transsulphuration and remethylation reactions of methionine's metabolism. We proposed to evaluate a home made method of determination for this parameter by high performance liquid chromatography (HPLC) and to compare it to fluorescence polarization immunoassay technique (FPIA) and to gaz phase chromatography (CG-SM). This method associated with good sensibility and precision remain much less expensive than FPIA technique.

Characterization of Extracellular Vesicles by Size-Exclusion High-Performance Liquid Chromatography (HPLC).

PubMed

Huang, Tao; He, Jiang

2017-01-01

Extracellular vesicles (EVs) have recently attracted substantial attention due to the potential diagnostic and therapeutic relevance. Although a variety of techniques have been used to isolate and analyze EVs, it is still far away from satisfaction. Size-exclusion chromatography (SEC), which separates subjects by size, has been widely applied in protein purification and analysis. The purpose of this chapter is to show the applications of size-exclusion high-performance liquid chromatography (HPLC) as methods for EV characterization of impurities or contaminants of small size, and thus for quality assay for the purity of the samples of EVs.

Fractionation by liquid chromatography combined with comprehensive two-dimensional gas chromatography-mass spectrometry for analysis of cyclics in oligomerisation products of Fischer-Tropsch derived light alkenes.

PubMed

van der Westhuizen, Rina; Potgieter, Hein; Prinsloo, Nico; de Villiers, André; Sandra, Pat

2011-05-27

In oligomerisation products of High Temperature Fischer-Tropsch (HTFT) derived light alkenes using a solid phosphoric acid (SPA) catalyst, the presence of cyclics was presumed although their occurrence could not be explained by the generally accepted oligomerisation mechanism. Notwithstanding the use of GC×GC-TOFMS, the cyclic alkanes could not be differentiated from the alkenes. On the one hand, compounds co-eluted in GC×GC and, on the other hand, MS cannot distinguish between these classes because of identical molecular masses and very similar mass fragmentation patterns. An LC pre-fractionation procedure utilising a silver-modified column was developed to separate the saturates from the unsaturates. Using this approach we were able, for the first time, to confirm the presence of cyclics, probably resulting from secondary reactions, in HTFT oligomerisation products. The occurrence of cyclics can be an indication of the beginning of carbonaceous deposit formation that could eventually lead to catalyst deactivation. Copyright © 2010 Elsevier B.V. All rights reserved.

The polar lipids of Clostridium psychrophilum, an anaerobic psychrophile

PubMed Central

Guan, Ziqiang; Tian, Bing; Perfumo, Amedea; Goldfine, Howard

2013-01-01

We have examined the polar lipids of Clostridium psychrophilum, a recently characterized psychrophilic Clostridium isolated from an Antarctic microbial mat. Lipids were extracted from cells grown near the optimal growth temperature (+5 °C) and at −5 °C, and analyzed by two-dimensional thin layer chromatography and liquid chromatography coupled with mass spectrometry. The major phospholipids of this species are: cardiolipin, phosphatidylethanolamine, and phosphatidylglycerol. Phosphatidylserine and lyso-phosphatidylethanolamine were found as minor components. The most abundant glycolipids are a monoglycosyldiradylglycerol (MGDRG) and a diglycosyldiradylglycerol (DGDRG). The latter was only seen in cells grown at −5 °C. An ethanolamine-phosphate derivative of N-acetylglucosaminyldiradylglycerol was seen in cells grown at −5 °C and an ethanolamine-phosphate derivative of MGDRG was found in cells grown at +5 °C. All lipids were present in both the all acyl and plasmalogen (alk-1′-enyl acyl) forms with the exception of PS and MGDRG, which were predominantly in the diacyl form. The significance of lipid changes at the two growth temperatures is discussed. PMID:23454375

Fuel Composition and Performance Analysis of Endothermically Heated Fuels for Pulse Detonation Engines

DTIC Science & Technology

2009-03-01

Waste heat from a pulse detonation engine (PDE) was extracted via concentric, counter flow heat exchangers to produce supercritical pyrolytic...mass spectrometry HLPC = High performance liquid chromatography NPT = National pipe thread PAH = Polycyclic aromatic hydrocarbon PDE = Pulse...Precision Liquid Chromatography (HPLC). The resulting “stressed” fuel showed a 29 shift to lower molecular weight compounds, as well as the production

Method 447.0 - Determination of Chlorophylls a and b and Identification of Other Pigments of Interest in Marine and Freshwater Algae Using High Performance Liquid Chromatography with Visible Wavelength Detection

EPA Science Inventory

This method provides a procedure for determination of chlorophylls a (chl a) and b (chl b) found in marine and freshwater phytoplankton. Reversed phase high performance liquid chromatography (HPLC) with detection at 440 nm is used to separate the pigments from a complex pigment ...

Chitin-coated Celite as an affinity adsorbent for high-performance liquid chromatography of lysozyme.

PubMed

Yamada, H; Fukumura, T; Ito, Y; Imoto, T

1985-04-01

Preparation of chitin-coated Celite as an affinity adsorbent for high-performance liquid chromatography of lysozymes and its application to separation of N-bromosuccinimide-oxidized lysozymes are described. By pH gradient elution, two diastereomers of oxindolealanine-62-lysozyme, delta 1-acetoxytryptophan-62-lysozyme (intermediate product in the reaction in acetate buffer), and native lysozyme were all separated within 40 min.

Determination of Poly-β-Hydroxybutyrate and Poly-β-Hydroxyvalerate in Activated Sludge by Gas-Liquid Chromatography

PubMed Central

Comeau, Yves; Hall, Kenneth J.; Oldham, William K.

1988-01-01

A convenient gas-liquid chromatography procedure to quantify poly-β-hydroxybutyrate and poly-β-hydroxyvalerate in activated sludge was developed by combining lyophilization of the samples, purification of the chloroform phase by water reextraction, and the use of capillary columns. With a flame ionization detector the sensitivity was estimated at 10−5 g/liter. PMID:16347745

Determination of the purity of valine by isocratic liquid chromatography coupled with charged aerosol detection (CAD).

PubMed

Lodi, A; Angus, M; Nap, C J; Skellern, G; Nicolas, A

2015-01-01

A liquid chromatography coupled with charged aerosol detection (LC-CAD) procedure; capable of separating and quantifying the most common impurities of valine at levels as low as 0.05 per cent (m/m), has been developed. The procedure is simple (isocratic), rapid, linear, sensitive and repeatable. It employs a widely available and inexpensive stationary phase (C18).

Factors That Contribute to Assay Variation in Quantitative Analysis of Sex Steroid Hormones Using Liquid and Gas Chromatography-Mass Spectrometry

ERIC Educational Resources Information Center

Xu, Xia; Veenstra, Timothy D.

2012-01-01

The list of physiological events in which sex steroids play a role continues to increase. To decipher the roles that sex steroids play in any condition requires high quality cohorts of samples and assays that provide highly accurate quantitative measures. Liquid and gas chromatography coupled with mass spectrometry (LC-MS and GC-MS) have…

Separation of the Components of a Commercial Analgesic Tablet: A Two-Week Sequence Comparing Purification by Two-Base Extraction and Column Chromatography

ERIC Educational Resources Information Center

Revell, Kevin D.

2011-01-01

A new laboratory experiment is described in which students compare two benchtop separation methods to isolate the three active components of the commercial analgesic Excedrin. In the two-week sequence, aspirin, acetaminophen, and caffeine are separated using either a two-base liquid-liquid extraction or silica column chromatography. Students then…

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.

Screening antiallergic components from Carthamus tinctorius using rat basophilic leukemia 2H3 cell membrane chromatography combined with high-performance liquid chromatography and tandem mass spectrometry.

PubMed

Han, Shengli; Huang, Jing; Cui, Ronghua; Zhang, Tao

2015-02-01

Carthamus tinctorius, used in traditional Chinese medicine, has many pharmacological effects, such as anticoagulant effects, antioxidant effects, antiaging effects, regulation of gene expression, and antitumor effects. However, there is no report on the antiallergic effects of the components in C. tinctorius. In the present study, we investigated the antiallergic components of C. tinctorius and its mechanism of action. A rat basophilic leukemia 2H3/cell membrane chromatography coupled online with high-performance liquid chromatography and tandem mass spectrometry method was developed to screen antiallergic components from C. tinctorius. The screening results showed that Hydroxysafflor yellow A, from C. tinctorius, was the targeted component that retained on the rat basophilic leukemia 2H3/cell membrane chromatography column. We measured the amount of β-hexosaminidase and histamine released in mast cells and the key markers of degranulation. The release assays showed that Hydroxysafflor yellow A could attenuate the immunoglobulin E induced release of allergic cytokines without affecting cell viability from 1.0 to 50.0 μM. In conclusion, the established rat basophilic leukemia 2H3 cell membrane chromatography coupled with online high-performance liquid chromatography and tandem mass spectrometry method successfully screened and identified Hydroxysafflor yellow A from C. tinctorius as a potential antiallergic component. Pharmacological analysis elucidated that Hydroxysafflor yellow A is an effective natural component for inhibiting immunoglobulin E-antigen-mediated degranulation. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.