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Gas chromatography with simultaneous detection: Ultraviolet spectroscopy, flame ionization, and mass spectrometry

JOURNAL OF CHROMATOGRAPHY A 2018年 1563卷 171-179页

作者： Gras, Ronda Luong, Jim Haddad, Paul R. Shellie, Robert A. Dow Chem Canada ULC Highway 15 Ft Saskatchewan AB T8L 2P4 Canada Univ Tasmania ARC Training Ctr Portable Analyt Separat Technol Private Bag 75 Hobart Tas 7001 Australia Univ Tasmania Australian Ctr Res Separat Sci ACROSS Private Bag 75 Hobart Tas 7001 Australia Trajan Sci & Med 7 Argent Pl Ringwood 3134 Australia RMIT Univ Sch Sci Private Bag 2476V Melbourne Vic 3001 Australia

An effective analytical strategy was developed and implemented to exploit the synergy derived from three different detector classes for gas chromatography, namely ultraviolet spectroscopy, flame ionization, and mass spectrometry for volatile compound analysis. This strategy was achieved by successfully hyphenating a user-selectable multi-wavelength diode array detector featuring a positive temperature coefficient thermistor as an isothermal heater to a gas chromatograph. By exploiting the non-destructive nature of the diode array detector, the effluent from the detector was split to two parallel detectors;namely a quadrupole mass spectrometer and a flame ionization detector. This multi-hyphenated configuration with the use of three detectors is a powerful approach not only for selective detection enhancement but also for improvement in structural elucidation of volatile compounds where fewer fragments can be obtained or for isomeric compound analysis. With the diode array detector capable of generating high resolution gas phase spectra, the information collected provides useful confirmatory information without a total dependence on the chromatographic separation process which is based on retention time. This information-rich approach to chromatography is achieved without incurring extra analytical time, resulting in improvements in compound identification accuracy, analytical productivity, and cost. Chromatographic performance obtained from model compounds was found to be acceptable with a relative standard deviation of the retention times of less than 0.01% RSD, and a repeatability at two levels of concentration of 100 and 1000 ppm (v/v) of less than 5% (n=10). With this configuration, correlation of data between the three detectors was simplified by having near identical retention times for the analytes studied. (C) 2018 Elsevier B.V. All rights reserved.

关键词： Gas chromatography Hyphenation diode array detection Heated DAD cell Mass spectrometry

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Characterization of water quality of Almiros river (Northeastern Crete, Greece): physicochemical parameters, polycyclic aromatic hydrocarbons and anionic detergents

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MODELING EARTH SYSTEMS AND ENVIRONMENT 2018年第4期4卷 1285-1296页

作者： Kotti, Melina Zacharioudaki, Despoina-Eleni Kokinou, Eleni Stavroulakis, George Technol Educ Inst Crete Romanou 3POB 73133 Khania Greece

Scope of the present work is (a) to explore the presence of polycyclic aromatic hydrocarbons (PAH) and sodium dodecyl benzene sulfonate (SDBS) in the surface water of Almiros River, located in Heraklion, Crete, Greece and (b) to correlate the physicochemical parameters (pH, alkalinity, conductivity, total dissolved solids, salinity, chlorides, hardness) of this river using robust statistical methods. Nine water samplings were performed in Almiros River in the time period January-November 2016. Standard methods of analysis were applied to investigate the physicochemical parameters. The pollutants PAHs and SDBS were determined simultaneously by high performance liquid chromatography with diode array and fluorescence detectors. Pyrene is the abundant PAH with concentrations ranging between 0.75 and 4.89 mu g/L while SDBS ranges between 3.57 and 124.3 mu g/L. Additionally, the correlations between the physicochemical parameters showed that TDS, electrical conductivity, salinity and chlorides reveal a strong correlation in the entire time of water sampling.

关键词： Anionic detergents Correlation diode array detection Fluorescence detection HPLC Polycyclic aromatic hydrocarbons Water quality

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Determination of curcuminoids in substances and dosage forms by cyclodextrin-mediated capillary electrophoresis with diode array detection

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CHEMICAL PAPERS 2011年第4期65卷 398-405页

作者： Marakova, Katarina Mikus, Peter Piest'ansky, Juraj Havranek, Emil Comenius Univ Fac Pharm Dept Pharmaceut Anal & Nucl Pharm Bratislava 83232 Slovakia

The present work illustrates the potential of the capillary zone electrophoresis (CZE) separation technique coupled with the on-capillary diode array detector (DAD) for highly reliable determination of curcuminoids (curcumin, CUR, demethoxycurcumin, DCUR, and bisdemethoxycurcumin, BCUR) in substances (commercially available plant extract) and pharmaceutical preparation (commercial pharmaceutical capsules) with minimal sample preparation;(2-hydroxypropyl)-beta-cyclodextrin (HP-beta-CD) was chosen for an anionic separation of CUR and its structural analogues (DCUR and BCUR) as an appropriate complexing agent (i) providing complete resolution of the curcuminoids and (ii) reducing adsorption of these hydrophobic analytes onto the capillary wall. DAD detection was utilised for characterisation of the composition of the separated zones via differences in the corresponding UV-VIS spectra (scanned at interval of 200-800 nm). Reference and real spectra of the analytes demonstrated that the proposed separation method was sufficiently selective to produce well-separated (i. e. spectrally homogeneous) analyte zones with no interfering compounds present. Successful validation and application of the CZE-DAD method proposed here suggest its routine use in highly effective and reliable analysis of curcuminoids in pharmaceutical samples. (C) 2011 Institute of Chemistry, Slovak Academy of Sciences

关键词： capillary zone electrophoresis diode array detection curcuminoids cyclodextrin pharmaceutical analysis

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QUANTITATION OF THE FLAVONOLS QUERCETIN AND KAEMPFEROL IN THE LEAVES OF TRIGONELLA FOENUM-GRAECUM BY HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY - diode array detection

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ANALYTICAL LETTERS 2011年第8期44卷 1463-1472页

作者： Gikas, Evagelos Bazoti, Fotini N. Papadopoulos, Nikolaos Alesta, Alexandra Economou, Garyfalia Tsarbopoulos, Anthony Univ Patras Dept Pharm Lab Pharmaceut Anal Rion 26504 Greece Goulandris Nat Hist Museum GAIA Res Ctr Bioanalyt Dept Kifisia 14562 Greece Agr Univ Athens Dept Crop Sci Athens Greece

Trigonella foenum-graecum is known for the strong hypoglycemic effects of the seed extract and for its significant allelopathic effects. The leaf extract however has not been studied thoroughly up-to-date and no data are available regarding the quantitative content of the plant's leaves. The purpose of this study was to quantify the flavonoid content and to assess the flavonoid seasonal variation in the leaves of the plant during the three developmental stages, vegetative, flowering, and fruiting. An HPLC method has been developed and validated employing a reversed phase C18 column and diode array detection. Sample pre-treatment was performed by methanol: water (80:20 v:v) extraction and glucoside hydrolysis with HCl. The method allowed the reliable determination of the aforementioned substances in the Trigonella's leaves revealing the highest amount of flavonoids during the flowering stage.

关键词： diode array detection Fabaceae Fenugreek Flavonoids HPLC Kaempferol Quercetin Trigonella foenum-graecum

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Recognition and alignment of variables from UV-vis chromatograms and application to industrial enzyme digests classification

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CHEMOMETRICS AND INTELLIGENT LABORATORY SYSTEMS 2017年 165卷 46-55页

作者： Burgos-Simon, Clara Javier Carrasco-Correa, Enrique Beneito-Cambra, Miriam Ramis-Ramos, Guillermo Francisco Simo-Alfonso, Ernesto Univ Politecn Valencia Inst Matemat Multidisciplinar E-46022 Valencia Spain Univ Valencia Dept Analyt Chem Dr Moliner 50 E-46100 Valencia Spain

In the last years, industrial applications of chemometrics have largely increased due to their capacity to extract important information from complex records as chromatograms or spectra data. The use of chemometric methods also can avoid the use of detectors of elevated cost. In this work, a procedure to recognize the relevant chemical information contained in complex UV vis chromatograms, after a trypsin digestion, to identify the three enzyme main classes (proteases, amylases and cellulases) commonly employed in the cleaning industry, has been developed. In order to recognize the chromatogram peaks, six indices of peak identity or identifiers were defined. A program written in MATLAB was elaborated to accomplish multiple comparisons between chromatograms to construct 3rd order tensors, which contain the common peaks of two or more chromatograms. Using a training test and these tensors, the target and sample chromatograms were ordered according to the proximity to its respective class centroids. Further, the peaks with the best warranties of being correctly recognized as belonging to characteristic peptides, common tout least two chromatograms, were used to align the sample chromatograms. Afterwards, to construct an LDA model for enzyme classification, the relative peak area of the aligned and identified peaks were employed. The LDA model was validated showing a 100% of prediction capability by leave-one-out, by dividing the samples in training and evaluation sets and also by the successful prediction of some spiked real samples.

关键词： Peak recognition fingerprinting liquid chromatography diode array detection protein analysis classificatory analysis

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Analysis of phenolic compounds in Greek plants of Lamiaceae family by HPLC

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JOURNAL OF APPLIED RESEARCH ON MEDICINAL AND AROMATIC PLANTS 2017年 6卷 62-69页

作者： Skendi, Adriana Irakli, Maria Chatzopoulou, Paschalina Hellen Agr Org Demeter Plant Breeding & Genet Resources Inst POB 60458 Thessaloniki 57001 Greece

The objective of the current study is the simultaneous determination of 24 phenolics including carvacrol and thymol, in plants of Lamiaceae family by developing a simple and reliable reversed-phase high-performance liquid chromatographic method involving diode array detection. The separation of 24 compounds was achieved on a reversed phase C-18 column kept at 30 degrees C by gradient elution with a flow rate of 1.3 mL/min. The method was validated for specificity, linearity and intra- and inter-day precision. The limit of detection and quantification for all analytes were small, ranging from 0.002 to 0.16 and 0.01 to 0.48 mu g/mL, respectively. This method was successfully applied to detect and quantify phenolics present in the plants. It was found that the amount of phenolics in both extracts (water, and methanolic) decreased in the following order: Origanum vulgare ssp. hirtum > Thymus capitatus > Satureja thymbra > Melissa officinalis > Rosmarinus officinalis. The limit of quantification values are low enough to detect and quantify successfully small amounts of 24 phenolics in the plants of Lamiaceae family. Generally, Melissa officinalis exhibited the highest antioxidant activity among the samples followed by Origanum vulgare ssp. hirtum. The developed method, is simple and reliable with satisfactory sensitivity and precision and is ideally suited for routine analysis. (C) 2017 Elsevier GmbH. All rights reserved.

关键词： Antioxidant activity Aromatic medicinal plants HPLC diode array detection Lamiaceae family Phenolicsa

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Development of a matrix solid phase dispersion methodology for the determination of triazine herbicides in marine sediments

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MICROCHEMICAL JOURNAL 2017年 133卷 137-143页

作者： Rodriguez-Gonzalez, Noelia Gonzalez-Castro, Maria-Jose Beceiro-Gonzalez, Elisa Muniategui-Lorenzo, Soledad Univ A Coruna Grp Quim Analit Aplicada Inst Univ Medio Ambiente Ctr Invest Cient AvanzadasDept Quim AnalitFac C Campus Coruna La Coruna 15071 Spain

A method based on Matrix Solid Phase Dispersion (MSPD) for the determination of nine triazines in marine sediments was optimized in terms of dispersant agents, co-sorbents and elution solvents. Three dispersing agents: octadecylsilyl bonded silica (C18), graphitized carbon black (GCB) and diatomaceous earth, and four clean-up co-sorbents: Florisil, GCB, primary and secondary amine (PSA)/strong anion exchanger (SAX), and GCB/PSA were assayed. The best results were obtained with GCB as dispersing agent, without co-sorbent, using 20 mL of ethyl acetate as elution solvent. Finally the extract was concentrated to dryness, re-constituted with 1 mL methanol and determined by HPLC-DAD. The analytical recoveries obtained were close to 100% and repeatability and reproducibility were below than 3.5% for all compounds. The linearity of the calibration curves was excellent in matrix matched standards, and yielded the coefficients of determination >= 0.9992 for all the target analytes. The LOQ values ranged from 0.022 to 0.037 mg kg(-1). Finally the method was applied to analyse the target compounds in marine sediment samples from the estuary of A Coruna (Galicia, NW of Spain). (C) 2017 Elsevier B.V. All rights reserved.

关键词： diode array detection High performance liquid chromatography Matrix solid phase dispersion Sediment Triazines

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Validated stability-indicating HPLC-DAD method for determination of the recently approved hepatitis C antiviral agent daclatasvir

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Annales Pharmaceutiques Francaises 2017年第3期75卷 176-184页

作者： Baker, M.M. El-Kafrawy, D.S. Mahrous, M.S. Belal, T.S. Methodology Department Pharco Pharmaceuticals Company Alexandria Egypt Pharmaceutical Chemistry Department Faculty of Pharmacy University of Alexandria Elmessalah Alexandria 21521 Egypt Pharmaceutical Analytical Chemistry Department Faculty of Pharmacy University of Alexandria Elmessalah Alexandria 21521 Egypt

A comprehensive stability indicating HPLC with diode array detection method was developed for the determination of the recently approved antiviral drug daclatasvir dihydrochloride (DCV) which is used for the treatment of chronic Hepatitis C Virus (HCV) genotype 3 infection. Effective chromatographic separation was achieved using Waters C8 column (4.6 × 250 mm, 5 μm particle size) with isocratic elution of the mobile phase composed of mixed phosphate buffer pH 2.5 and acetonitrile in the ratio of 75:25 (by volume). The mobile phase was pumped at a flow rate of 1.2 mL/min, and quantification of DCV was based on measuring its peak areas at 306 nm. DCV eluted at retention time 5.4 min. Analytical performance of the proposed HPLC procedure was thoroughly validated with respect to system suitability, linearity, range, precision, accuracy, specificity, robustness, detection and quantification limits. The linearity range was 0.6–60 μg/mL with correlation coefficient > 0.99999. The drug was subjected to forced degradation conditions of neutral, acidic and alkaline hydrolysis, oxidation and thermal degradation. The proposed method proved to be stability-indicating by resolution of the drug from its forced-degradation products. The validated HPLC method was successfully applied to analysis of the cited drug in its tablets. © 2017 Académie Nationale de Pharmacie

关键词： Daclatasvir diode array detection Forced degradation HCV HPLC Stability-indicating assay

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Variability of some diterpene esters in coffee beverages as influenced by brewing procedures

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JOURNAL OF FOOD SCIENCE AND TECHNOLOGY-MYSORE 2016年第11期53卷 3916-3927页

作者： Moeenfard, Marzieh Erny, Guillaume L. Alves, Arminda Univ Porto LEPABE Fac Engn Rua Dr Roberto Frias P-4200465 Oporto Portugal

Several coffee brews, including classical and commercial beverages, were analyzed for their diterpene esters content (cafestol and kahweol linoleate, oleate, palmitate and stearate) by high performance liquid chromatography with diode array detector (HPLC-DAD) combined with spectral deconvolution. Due to the coelution of cafestol and kahweol esters at 225 nm, HPLC-DAD did not give accurate quantification of cafestol esters. Accordingly, spectral deconvolution was used to deconvolve the co-migrating profiles. Total cafestol and kahweol esters content of classical coffee brews ranged from 5-232 to 2-1016 mg/L, respectively. Commercial blends contained 1-54 mg/L of total cafestol esters and 2-403 mg/L of total kahweol esters. Boiled coffee had the highest diterpene esters content, while filtered and instant brews showed the lowest concentrations. However, individual diterpene esters content was not affected by brewing procedure as in terms of kahweol esters, kahweol palmitate was the main compound in all samples, followed by kahweol linoleate, oleate and stearate. Higher amounts of cafestol palmitate and stearate were also observed compared to cafestol linoleate and cafestol oleate. The ratio of diterpene esters esterified with unsaturated fatty acids to total diterpene esters was considered as measure of their unsaturation in analyzed samples which varied from 47 to 52%. Providing new information regarding the diterpene esters content and their distribution in coffee brews will allow a better use of coffee as a functional beverage.

关键词： Cafestol esters Kahweol esters Coffee brews Spectral deconvolution diode array detection

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Applicability of Pressurized Liquid Extraction for Melamine Analysis in Pet Foods with High-Performance Liquid Chromatography with diode array detection

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FOOD ANALYTICAL METHODS 2010年第3期3卷 188-194页

作者： Kim, Byungchul LeBlanc, Lawrence A. Bushway, Rodney J. Perkins, L. Brian Univ Maine Dept Food Sci & Human Nutr Orono ME 04469 USA

A pressurized liquid extraction (PLE) method was developed for melamine analysis in pet foods. The PLE method which utilized an accelerated solvent extraction (ASEA (R)) system was also compared with sonication and polytron extraction methods. The parameters for the optimized PLE method were temperature (75 A degrees C for wet pet food, 125 A degrees C for dry pet food), pressure (1,500 psi), static time (10 min), flush volume (40%), purge time (1 min), and number of cycles (1). Recoveries obtained by PLE method were significantly higher (P a parts per thousand currency signaEuro parts per thousand 0.05) than those of sonication and polytron methods for dry pet food samples. For the analysis of adulterated pet foods, PLE resulted in the highest melamine content followed by sonication and polytron. Using PLE, samples fortified with melamine at 2.5 and 100 mg kg(-1) resulted in recoveries ranging from 55% to 90% for wet samples and from 90% to 116% for dry samples. Low recovery rate from wet samples at low spike level (2.5 mg kg(-1)) may have been caused by co-aggregation of polysaccharide and protein with melamine due to low pH during solid-phase extraction cleanup. Limit of detection and limit of quantification values were 0.5 (mg kg(-1)) and 1.0 (mg kg(-1)) for dry samples. Overall, PLE had the best extraction efficiency compared to sonication and polytron, proving PLE to be a useful tool for melamine analysis of pet foods.

关键词： Melamine Pet Food Pressurized Liquid Extraction HPLC diode array detection

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