U.S. flag

An official website of the United States government

PubAg

Main content area

You searched for: Subject "liquid chromatography" Remove constraint Subject: "liquid chromatography"
Start Over

Search

67,702  Search Results

« Previous | 1 - 20 of 67,702 |
Number of results to display per page

Search Results

1. Constant pressure mode of operation in the second dimension of two-dimensional liquid chromatography: A proof of concept

Author:
Shoykhet, Konstantin; Stoll, Dwight; Buckenmaier, Stephan
Source:
Journal of chromatography 2021 v.1639 pp. 461880
ISSN:
0021-9673
Subject:
liquid chromatography,   etc   ; viability; viscosity;     Show all 3 Subjects
Abstract:
... The use of two-dimensional liquid chromatography (2D-LC) continues to grow as the advantages over 1D-LC become increasingly clear in specific application areas, and the number of experienced 2D-LC users increases. As with any technique, however, there is always room for innovation that could improve the performance of 2D-LC. In recent years the technical aspects and potential benefits of a volume- ...
DOI:
10.1016/j.chroma.2021.461880

2. Deep Q-learning for the selection of optimal isocratic scouting runs in liquid chromatography

Author:
Kensert, Alexander; Collaerts, Gilles; Efthymiadis, Kyriakos; Desmet, Gert; Cabooter, Deirdre
Source:
Journal of chromatography 2021 v.1638 pp. 461900
ISSN:
0021-9673
Subject:
liquid chromatography,   etc   ; algorithms; models;     Show all 3 Subjects
Abstract:
... An important challenge in chromatography is the development of adequate separation methods. Accurate retention models can significantly simplify and expedite the development of adequate separation methods for complex mixtures. The purpose of this study was to introduce reinforcement learning to chromatographic method development, by training a double deep Q-learning algorithm to select optimal iso ...
DOI:
10.1016/j.chroma.2021.461900

3. Theoretical study of the efficiency of liquid chromatography columns with particle size gradient

Author:
Horváth, Szabolcs; Gritti, Fabrice; Horváth, Krisztián
Source:
Journal of chromatography 2021 pp. 462331
ISSN:
0021-9673
Subject:
liquid chromatography,   etc   ; evolution; particle size;     Show all 3 Subjects
Abstract:
... Modern analytical applications of liquid chromatography require more and more efficient columns. In this work, the possibility of utilizing particle size gradient in the chromatographic column was studied by a theoretical approach. In the course of our work three different scenarios of particle size gradients were considered with different shapes (linear, convex and concave). The evolution of band ...
DOI:
10.1016/j.chroma.2021.462331

4. Development of an analytical method based on solid-phase extraction and LC-MS/MS for the monitoring of current-use pesticides and their metabolites in human urine

Author:
Gao, Beibei; Poma, Giulia; Malarvannan, Govindan; Dumitrascu, Catalina; Bastiaensen, Michiel; Wang, Minghua; Covaci, Adrian
Source:
Journal of environmental sciences (China) 2022 v.111 pp. 153-163
ISSN:
1001-0742
Subject:
liquid chromatography,   etc   ; acetamiprid; bifenthrin; chemical species; chlorpyrifos; chlorpyrifos-methyl; cyfluthrin; cypermethrin; deltamethrin; dicarboxylic acids; environmental monitoring; fipronil; humans; imidacloprid; malathion; metabolites; permethrin; pyrethrins; solid phase extraction; tandem mass spectrometry; thiacloprid; triazoles; urine; China;     Show all 24 Subjects
Abstract:
... Pyrethroids, organophosphorus pesticides and fipronil have been listed as priority chemicals in human biomonitoring studies because of their wide use and potential health effects in humans. The determination of 13 pesticides, including pyrethroids (deltamethrin, cypermethrin, permethrin, cyfluthrin, bifenthrin), organophosphorus (chlorpyrifos, chlorpyrifos-methyl, and malathion), fipronil, neonico ...
DOI:
10.1016/j.jes.2021.03.029

5. The history of electron ionization in LC-MS, from the early days to modern technologies: A review

Author:
Famiglini, Giorgio; Palma, Pierangela; Termopoli, Veronica; Cappiello, Achille
Source:
Analytica chimica acta 2021 v.1167 pp. 338350
ISSN:
0003-2670
Subject:
liquid chromatography,   etc   ; gas chromatography-mass spectrometry; ionization;     Show all 3 Subjects
Abstract:
... This review article traces the history of the use of liquid chromatography coupled with mass spectrometry (LC-MS) using electron ionization (EI) from the first attempts up to the present day. At the time of the first efforts to couple LC to MS, 70 eV EI was the most common ionization technique, typically used in gas chromatography-mass spectrometry (GC-MS) and providing highly reproducible mass sp ...
DOI:
10.1016/j.aca.2021.338350

6. Quantification of tea‐derived catechins without the requirement for respective calibration curves by single reference liquid chromatography based on relative molar sensitivity

Author:
Takahashi, Miki; Nishizaki, Yuzo; Masumoto, Naoko; Sugimoto, Naoki; Sato, Kyoko; Inoue, Koichi
Source:
Journal of the science of food and agriculture 2021 v.101 no.9 pp. 3804-3810
ISSN:
0022-5142
Subject:
liquid chromatography,   etc   ; agriculture; calibration; flavanols; fluorescence; tea;     Show all 6 Subjects
Abstract:
... BACKGROUND: Many studies report the monitoring of catechins in tea samples by chromatographic techniques. Unfortunately, only a small number of screening assays for catechins exist as a result of the complexity of authentic standards for the respective calibration curves. In the present study, a single reference (SR) exhaustive assay for the simultaneous quantification of tea‐derived catechins by ...
DOI:
10.1002/jsfa.11013

7. A critical review of analytical methods for ergot alkaloids in cereals and feed and in particular suitability of method performance for regulatory monitoring and epimer-specific quantification

Author:
Chung, Stephen W.C.
Source:
Food additives & contaminants 2021 v.38 no.6 pp. 997-1012
ISSN:
1944-0057
Subject:
liquid chromatography,   etc   ; ergometrine; ergot; ergotamine; fluorescence; markets;     Show all 6 Subjects
Abstract:
... Cereals and feed contaminated with ergot alkaloids (EAs) have been of concern for several decades. Nowadays, analysis of EAs is focused on ergometrine, ergotamine, ergosine, ergocristine, ergocryptine (a mixture of α- and β-isomers) and ergocornine and their related –inine epimers as listed in the European Commission Recommendation 2012/154/EU. Liquid chromatography with fluorescence detection has ...
DOI:
10.1080/19440049.2021.1898679

8. Effects of rifampicin on plasma pharmacokinetics of tulathromycin in goats

Author:
Şahiner, Hande Sultan; Kum, Cavit
Source:
Journal of veterinary pharmacology and therapeutics 2021 v.44 no.3 pp. 374-380
ISSN:
0140-7783
Subject:
liquid chromatography,   etc   ; males; pharmacokinetics; rifampicin; therapeutics;     Show all 5 Subjects
Abstract:
... We investigated the pharmacokinetic profile of co‐administration of tulathromycin with rifampicin. Healthy male goats were allocated to three groups (n = 8) as Group A (single dose 2.5 mg/kg tulathromycin s.c.), B (10 mg kg⁻¹ day⁻¹ rifampicin p.o. daily for 7 days and single dose 2.5 mg/kg tulathromycin s.c. on 8th day), and C (10 mg kg⁻¹ day⁻¹ rifampicin p.o. daily for 21 days and single dose 2.5 ...
DOI:
10.1111/jvp.12928

9. The influence of injection volume on efficiency of microbore liquid chromatography columns for gradient and isocratic elution

Author:
Werres, Tobias; Schmidt, Torsten C.; Teutenberg, Thorsten
Source:
Journal of chromatography 2021 v.1641 pp. 461965
ISSN:
0021-9673
Subject:
liquid chromatography,   etc   ; drugs; naphthalene; standard deviation;     Show all 4 Subjects
Abstract:
... The injection volume and the associated column volume overload is one of the most common issues in miniaturized chromatography. The injection volume should not exceed 10% of the effective column volume. A further reduction of the injection volume leads to an increase in chromatographic efficiency. However, the signal intensity must be above a certain threshold to generate a chromatographic peak th ...
DOI:
10.1016/j.chroma.2021.461965

10. Basic Structure-Independent Equations of Kinetic Performance of Columns in Liquid Chromatography

Author:
Blumberg, Leonid M.
Source:
Analytical chemistry 2021 v.93 no.12 pp. 5309-5316
ISSN:
1520-6882
Subject:
liquid chromatography,   etc   ; analytical chemistry; flow resistance;     Show all 3 Subjects
Abstract:
... The lowest dimensionless plate height (hₘᵢₙ) of the liquid chromatography (LC) column is a subjective metric that cannot be found from measurements of parameters of a column as a separation device and is not suitable for comparison of kinetic performance of differently structured columns. In some cases (monolithic, pillar-array columns), there is no correlation between hₘᵢₙ (as it is currently und ...
DOI:
10.1021/acs.analchem.1c00514

11. The retention index approach in liquid chromatography: An historical review and recent advances

Author:
Rigano, Francesca; Arigò, Adriana; Oteri, Marianna; La Tella, Roberta; Dugo, Paola; Mondello, Luigi
Source:
Journal of chromatography 2021 v.1640 pp. 461963
ISSN:
0021-9673
Subject:
liquid chromatography,   etc   ; databases; gas chromatography; spectrometers;     Show all 4 Subjects
Abstract:
... Historically, retention parameters were reliably used as identification criterion in chromatographic analytical systems. However, pure analytical standards are necessary to determine the retention behaviour of a given compound. In recent decades, mass spectrometer (MS) became the detector of choice to obtain structural information on unknown peaks, thanks to the elucidation of fragments, often ari ...
DOI:
10.1016/j.chroma.2021.461963

12. A methodology employing retention modeling for achieving control space in liquid chromatography method development using quality by design approach

Author:
Jayaraman, Karthik; Rajendran, Ashok Kumar; Kumar, Gandhi Santosh; Bhutani, Hemant
Source:
Journal of chromatography 2021 v.1635 pp. 461658
ISSN:
0021-9673
Subject:
liquid chromatography,   etc   ; computer simulation; models; temperature;     Show all 4 Subjects
Abstract:
... This study reports the application of retention modeling and quality by design practices for reverse-phase liquid chromatographic method development of a new chemical entity. Prior to the retention modeling, preliminary screening experiments were performed for the selection of stationary phase, organic modifiers, and method parameters. Based on the results of preliminary method conditions, tG-T (g ...
DOI:
10.1016/j.chroma.2020.461658

13. Computer aided optimization of multilinear gradient elution in liquid chromatography

Author:
Hao, Weiqiang; Li, Bo; Deng, Yuying; Chen, Qiang; Liu, Lijuan; Shen, Qiaoyin
Source:
Journal of chromatography 2021 v.1635 pp. 461754
ISSN:
0021-9673
Subject:
liquid chromatography,   etc   ; algorithms; computers; lignin; models; solvents;     Show all 6 Subjects
Abstract:
... Analytical expressions for retention time and peak compression factor are deduced by assuming quadratic solvent strength model and multilinear gradient elution. Based on these expressions, a program for the optimization of multilinear gradient profile is written with Visual Basic for Applications in Excel using genetic algorithm. The program is applied to search for a gradient profile for the sepa ...
DOI:
10.1016/j.chroma.2020.461754

14. Reducing the influence of geometry-induced gradient deformation in liquid chromatographic retention modelling

Author:
Bos, Tijmen S.; Niezen, Leon E.; den Uijl, Mimi J.; Molenaar, Stef R.A.; Lege, Sascha; Schoenmakers, Peter J.; Somsen, Govert W.; Pirok, Bob W.J.
Source:
Journal of chromatography 2021 v.1635 pp. 461714
ISSN:
0021-9673
Subject:
liquid chromatography,   etc   ; algorithms; chemical species; deformation; models;     Show all 5 Subjects
Abstract:
... Rapid optimization of gradient liquid chromatographic (LC) separations often utilizes analyte retention modelling to predict retention times as function of eluent composition. However, due to the dwell volume and technical imperfections, the actual gradient may deviate from the set gradient in a fashion unique to the employed instrument. This makes accurate retention modelling for gradient LC chal ...
DOI:
10.1016/j.chroma.2020.461714

15. Reduction of the extra-column band dispersion by a slow transport and splitting of a sample band in isocratic reversed-phase liquid chromatography

Author:
Terada, Hidetoshi; Kuroda, Ikuma; Uzu, Hideyuki; Ohira, Masayoshi; Yoshikawa, Kohei; Furuno, Masahiro; Fukusaki, Eiichiro; Tanaka, Nobuo
Source:
Journal of chromatography 2021 v.1641 pp. 461996
ISSN:
0021-9673
Subject:
reversed-phase high performance liquid chromatography; reversed-phase liquid chromatography,   etc   ; variance;     Show all 3 Subject
Abstract:
... Sample introduction method was studied to reduce the extra-column effect in reversed-phase HPLC. Slow transport of a sample band (SToSB) in the pre-column space followed by the introduction of the band into the column at a near-optimum flow rate resulted in larger plate counts for a 1.0 mmID, 5 cm long column as much as 1.4-1.6 times for solutes with a retention factor (k) of 0.5-1.8 compared to a ...
DOI:
10.1016/j.chroma.2021.461996

16. Measuring and using scanning-gradient data for use in method optimization for liquid chromatography

Author:
den Uijl, Mimi J.; Schoenmakers, Peter J.; Schulte, Grace K.; Stoll, Dwight R.; van Bommel, Maarten R.; Pirok, Bob W.J.
Source:
Journal of chromatography 2021 v.1636 pp. 461780
ISSN:
0021-9673
Subject:
comprehensive two-dimensional liquid chromatography; reversed-phase liquid chromatography,   etc   ; chemical species; models; prediction; uncertainty;     Show all 6 Subjects
Abstract:
... The use of scanning gradients can significantly reduce method-development time in reversed-phase liquid chromatography. However, there is no consensus on how they can best be used. In the present work we set out to systematically investigate various factors and to formulate guidelines. Scanning gradients are used to establish retention models for individual analytes. Different retention models wer ...
DOI:
10.1016/j.chroma.2020.461780

17. Maximizing two-dimensional liquid chromatography peak capacity for the separation of complex industrial samples

Author:
Zhu, Koudi; Pursch, Matthias; Eeltink, Sebastiaan; Desmet, Gert
Source:
Journal of chromatography 2020 v.1609 pp. 460457
ISSN:
0021-9673
Subject:
liquid chromatography,   etc   ; industry; polymers;     Show all 3 Subjects
Abstract:
... We report on a study on the use of 2D-LC in industry wherein we maximized the peak capacity by serially coupling up to six 15 cm long columns in the 1st dimension. For the considered aromatic amine oligomer sample, the combination of reverse phase pentafluorophenyl column providing selectivity based on π–π interaction in the 1st and a more retaining reverse phase polymeric C18 column in the 2nd di ...
DOI:
10.1016/j.chroma.2019.460457

18. Determination of S- and/or R-equol in plant-based food products and efficacy of topical or oral 4′,7-isoflavandiol (R/S equol) to improve skin health in adult men, a Placebo-controlled pilot study

Author:
Lephart, Edwin D.
Source:
Journal of functional foods 2021 v.83 pp. 104563
ISSN:
1756-4646
Subject:
high performance liquid chromatography,   etc   ; adults; plant-based foods; topical application;     Show all 4 Subjects
Abstract:
... There were two purposes for this investigation: 1) determine if S- and/or R-equol is present in seven plant-based food products and 2) to establish if topical or oral R/S equol administration improved skin health in adult men. First, the presence of R- and/or S-equol was determined by high performance liquid chromatography (HPLC) in commercial food products. Next, in a small pilot study R/S equol ...
DOI:
10.1016/j.jff.2021.104563

19. Creation of Mo/Tc@C₆₀ and Au@C₆₀ and molecular-dynamics simulations

Author:
Ohtsuki, Tsutomu; Manjanath, Aaditya; Ohno, Kaoru; Inagaki, Makoto; Sekimoto, Shun; Kawazoe, Yoshiyuki
Source:
RSC advances 2021 v.11 no.32 pp. 19666-19672
ISSN:
2046-2069
Subject:
high performance liquid chromatography,   etc   ; fullerene; medicine; molecular dynamics;     Show all 4 Subjects
Abstract:
... The formation of middle- and/or high-weight atom (Mo, Au)-incorporated fullerenes was investigated using radionuclides produced by nuclear reactions. From the trace radioactivities of ⁹⁹Mo/⁹⁹ᵐTc or ¹⁹⁴Au after high-performance liquid chromatography, it was found that the formation of endohedral and/or heterofullerene fullerenes in ⁹⁹Mo/⁹⁹ᵐTc and ¹⁹⁴Au atoms could occur by a recoil process followin ...
DOI:
10.1039/d0ra10196f

20. Adventitious root culture of Pfaffia glomerata (Spreng.) Pedersen in a roller bottle system: An alternative source of β-ecdysone

Author:
da Silva, Thaila Fernanda Oliveira; Yamaguchi, Cristina Sayuri; Ribeiro, Susana Tavares Cotrim; da Silva Avincola, Alexandre; Pilau, Eduardo Jorge; Porto, Carla; de Oliveira, Arildo José Braz; Gonçalves, Regina Aparecida Correia
Source:
Phytochemistry letters 2021 v.43 pp. 1-7
ISSN:
1874-3900
Subject:
liquid chromatography,   etc   ; Pfaffia glomerata; adventitious roots; bioreactors; metabolites; plant biochemistry;     Show all 6 Subjects
Abstract:
... β-ecdysone is the main compound of commercial interest produced by the roots of Pfaffia glomerata (Spreng.) Pedersen, and is used in herbal medicines and dietary supplements. In-vitro root culture facilitates the continuous production of high-quality compounds, and uses sustainable production techniques. Adventitious roots of P. glomerata were cultivated in a roller bottle system and an orbital gy ...
DOI:
10.1016/j.phytol.2021.02.009