QuEChERS and ultra-high performance liquid chromatography–tandem mass spectrometry method for the determination of parabens and ultraviolet filters in human milk samples

Publication date: 20 April 2018
Source:Journal of Chromatography A, Volume 1546
Author(s): F. Vela-Soria, L.M. Iribarne-Durán, V. Mustieles, I. Jiménez-Díaz, M.F. Fernández, N. Olea
Concerns are growing about human exposure to endocrine disrupting chemicals (EDCs), especially during developmental stages. Parabens (PBs) and ultraviolet filters (UVFs) are prevalent EDCs widely used as additives in cosmetics and personal care products (PCPs). The objective of this study was to develop a method to determine four PBs and ten UVFs in human milk using QuEChERS treatment and ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC–MS/MS). Multivariate strategies were applied to optimize experimental parameters. Limits of quantification ranged from 0.1 to 0.2 ng mL−1 and inter-day variability (evaluated as relative standard deviation) from 6% to 13%. The method was validated using matrix-matched standard calibration followed by a recovery assay with spiked samples. Recovery percentages ranged from 87% to 112%. The method was satisfactorily applied to assess target compounds in human milk samples from 15 donors. This analytical procedure can provide information on newborn exposure to these EDCs.

Publication date: 20 April 2018
Source:Journal of Chromatography A, Volume 1546

Author(s): F. Vela-Soria, L.M. Iribarne-Durán, V. Mustieles, I. Jiménez-Díaz, M.F. Fernández, N. Olea

Concerns are growing about human exposure to endocrine disrupting chemicals (EDCs), especially during developmental stages. Parabens (PBs) and ultraviolet filters (UVFs) are prevalent EDCs widely used as additives in cosmetics and personal care products (PCPs). The objective of this study was to develop a method to determine four PBs and ten UVFs in human milk using QuEChERS treatment and ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC–MS/MS). Multivariate strategies were applied to optimize experimental parameters. Limits of quantification ranged from 0.1 to 0.2 ng mL−1 and inter-day variability (evaluated as relative standard deviation) from 6% to 13%. The method was validated using matrix-matched standard calibration followed by a recovery assay with spiked samples. Recovery percentages ranged from 87% to 112%. The method was satisfactorily applied to assess target compounds in human milk samples from 15 donors. This analytical procedure can provide information on newborn exposure to these EDCs.





Development of a partitioned liquid-liquid extraction- dispersive solid phase extraction procedure followed by liquid chromatography-tandem mass spectrometry for analysis of 3-monochloropropane-1,2-diol diesters in edible oils

Publication date: 4 May 2018
Source:Journal of Chromatography A, Volume 1548
Author(s): J.A. Custodio-Mendoza, R.A. Lorenzo, I.M. Valente, P.J. Almeida, M.A. Lage, J.A. Rodrigues, A.M. Carro
A fast and effective method using a modified QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) approach which includes partitioned liquid-liquid extraction (PLLE) and dispersive solid phase extraction (dSPE) clean-up step for the determination of seven 3-monochloropropane-1,2-diol (3-MCPD) fatty acid diesters in vegetable oils is developed and validated according to the Food and Drug Administration (FDA) guidelines. Due to the complexity of the matrices, combination of silica based sorbents (Silica Strong Anion Exchange (Si-SAX), Supel™ QuE Z-Sep+ (Z-Sep+) and Primary Secondary Amine (PSA) were tested for lipid removal. The effect of several experimental factors on the efficiency of the extraction procedure was studied by a screening design 3422//16 and a response surface Doehlert design. The separation and determination was carried out by liquid chromatography coupled with tandem mass spectrometry (LC–MS/MS). The method provided suitable linearity (r2 > 0.9960), precision (relative standard deviation (RSD) lower than 10%) and accuracy, in terms of recovery. The limits of detection (LOD) and limits of quantification (LOQ) ranged from 10 to 20 μg kg −1 and from 25 to 50 μg kg−1, respectively. The recoveries at three spiking levels of 100, 250, and 500 μg kg−1 were over the range of 71.4–122.9% with RSD lower than 13%. The method was successfully applied in edible oils and fatty food samples. The results provide valuable information to assess the risk of exposure to these foodborne contaminants.

Publication date: 4 May 2018
Source:Journal of Chromatography A, Volume 1548

Author(s): J.A. Custodio-Mendoza, R.A. Lorenzo, I.M. Valente, P.J. Almeida, M.A. Lage, J.A. Rodrigues, A.M. Carro

A fast and effective method using a modified QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) approach which includes partitioned liquid-liquid extraction (PLLE) and dispersive solid phase extraction (dSPE) clean-up step for the determination of seven 3-monochloropropane-1,2-diol (3-MCPD) fatty acid diesters in vegetable oils is developed and validated according to the Food and Drug Administration (FDA) guidelines. Due to the complexity of the matrices, combination of silica based sorbents (Silica Strong Anion Exchange (Si-SAX), Supel™ QuE Z-Sep+ (Z-Sep+) and Primary Secondary Amine (PSA) were tested for lipid removal. The effect of several experimental factors on the efficiency of the extraction procedure was studied by a screening design 3422//16 and a response surface Doehlert design. The separation and determination was carried out by liquid chromatography coupled with tandem mass spectrometry (LC–MS/MS). The method provided suitable linearity (r2 > 0.9960), precision (relative standard deviation (RSD) lower than 10%) and accuracy, in terms of recovery. The limits of detection (LOD) and limits of quantification (LOQ) ranged from 10 to 20 μg kg −1 and from 25 to 50 μg kg−1, respectively. The recoveries at three spiking levels of 100, 250, and 500 μg kg−1 were over the range of 71.4–122.9% with RSD lower than 13%. The method was successfully applied in edible oils and fatty food samples. The results provide valuable information to assess the risk of exposure to these foodborne contaminants.





Multilevel characterization of marine microbial biodegradation potentiality by means of flow-modulated comprehensive two-dimensional gas chromatography combined with a triple quadrupole mass spectrometer

Publication date: 27 April 2018
Source:Journal of Chromatography A, Volume 1547
Author(s): Mariosimone Zoccali, Simone Cappello, Luigi Mondello
The present research is focused on the use of a triple quadrupole mass spectrometer (QqQ MS) coupled with flow modulated comprehensive two-dimensional gas chromatography (FM GC × GC) for a multilevel elucidation of biodegradation potentiality of natural marine microbial populations during a bioremediation (biostimulation) treatment. The crude oil used for the evaluation of the bioremediation process, namely Dansk Blend Pier E1, represents a very complex sample. Hence, in order to understand the metabolic activity of microbial populations during the bioremediation process, a GC × GC system was used. The high separation power has allowed a detailed characterization of the different chemical families; moreover, thanks to the high acquisition frequency of the QqQ MS spectrometer, both full scan and multiple reaction monitoring (MRM) data were acquired in the same run. By using this system, both qualitative analysis of untargeted hydrocarbons mixture (crude oil) and qualitative analysis of biomarker compounds, present in low amount and often hindered under the bulk of the sample (i.e. adamantanes, diamantanes, steranes and hopanes), were performed simultaneously.The bioremediation capability of biostimulated bacteria was evaluated at four (T4), eight (T8) and fourteen (T14) days. Progressive degradation of linear, branched, and aromatic hydrocarbons, adamantanes, and diamantanes has been showed, whereas, results underline the lack of any kind of activity against steranes, and hopanes.

Publication date: 27 April 2018
Source:Journal of Chromatography A, Volume 1547

Author(s): Mariosimone Zoccali, Simone Cappello, Luigi Mondello

The present research is focused on the use of a triple quadrupole mass spectrometer (QqQ MS) coupled with flow modulated comprehensive two-dimensional gas chromatography (FM GC × GC) for a multilevel elucidation of biodegradation potentiality of natural marine microbial populations during a bioremediation (biostimulation) treatment. The crude oil used for the evaluation of the bioremediation process, namely Dansk Blend Pier E1, represents a very complex sample. Hence, in order to understand the metabolic activity of microbial populations during the bioremediation process, a GC × GC system was used. The high separation power has allowed a detailed characterization of the different chemical families; moreover, thanks to the high acquisition frequency of the QqQ MS spectrometer, both full scan and multiple reaction monitoring (MRM) data were acquired in the same run. By using this system, both qualitative analysis of untargeted hydrocarbons mixture (crude oil) and qualitative analysis of biomarker compounds, present in low amount and often hindered under the bulk of the sample (i.e. adamantanes, diamantanes, steranes and hopanes), were performed simultaneously. The bioremediation capability of biostimulated bacteria was evaluated at four (T4), eight (T8) and fourteen (T14) days. Progressive degradation of linear, branched, and aromatic hydrocarbons, adamantanes, and diamantanes has been showed, whereas, results underline the lack of any kind of activity against steranes, and hopanes.





Method development and optimization for the determination of benzene, toluene, ethylbenzene and xylenes in water at trace levels by static headspace extraction coupled to gas chromatography–barrier ionization discharge detection

Publication date: 4 May 2018
Source:Journal of Chromatography A, Volume 1548
Author(s): Raffaella Pascale, Giuliana Bianco, Stefania Calace, Salvatore Masi, Ignazio M. Mancini, Giuseppina Mazzone, Donatella Caniani
Benzene, toluene, ethylbenzene, and xylenes, more commonly named BTEX, represent one of the most ubiquitous and hazardous groups of atmospheric pollutants. The goal of our research was the trace quantification of BTEX in water by using a new simple, low-cost, and accurate method, based on headspace (HS) extraction and gas chromatography (GC) coupled to barrier ionization discharge detector (BID). This water application dealt with simple matrices without protein, fat, or humic material that adsorb target analytes, thus the external standard calibration was suitable to quantify each compound. The validation steps included the study of linearity, detection and quantification limits, and accuracy. LODs and LOQs varied from 0.159 to 1.845 μg/L and from 0.202 to 2.452 μg/L, respectively. The recovery was between 0.74 ± 0.13 and 1.15 ± 0.09; relative standard deviations (% RDSs) were less than 12.81% (n = 5) and 14.84% (n = 10). Also, GC performance was evaluated in term of efficiency, peak tailing and resolution. Preliminary results from practical applications to analyses of real samples are presented. The results indicate that static HS coupled to GC–BID is a successful method for BTEX analysis in water samples at the μg/L levels, provided that hydrocarbons interference occur at similar concentration levels. GC-BID may become a routine reference method alongside the official analytical techniques for quality control purposes of contaminated waters. Moreover, the new method is amenable to automation by using commercial HS units.

Publication date: 4 May 2018
Source:Journal of Chromatography A, Volume 1548

Author(s): Raffaella Pascale, Giuliana Bianco, Stefania Calace, Salvatore Masi, Ignazio M. Mancini, Giuseppina Mazzone, Donatella Caniani

Benzene, toluene, ethylbenzene, and xylenes, more commonly named BTEX, represent one of the most ubiquitous and hazardous groups of atmospheric pollutants. The goal of our research was the trace quantification of BTEX in water by using a new simple, low-cost, and accurate method, based on headspace (HS) extraction and gas chromatography (GC) coupled to barrier ionization discharge detector (BID). This water application dealt with simple matrices without protein, fat, or humic material that adsorb target analytes, thus the external standard calibration was suitable to quantify each compound. The validation steps included the study of linearity, detection and quantification limits, and accuracy. LODs and LOQs varied from 0.159 to 1.845 μg/L and from 0.202 to 2.452 μg/L, respectively. The recovery was between 0.74 ± 0.13 and 1.15 ± 0.09; relative standard deviations (% RDSs) were less than 12.81% (n = 5) and 14.84% (n = 10). Also, GC performance was evaluated in term of efficiency, peak tailing and resolution. Preliminary results from practical applications to analyses of real samples are presented. The results indicate that static HS coupled to GC–BID is a successful method for BTEX analysis in water samples at the μg/L levels, provided that hydrocarbons interference occur at similar concentration levels. GC-BID may become a routine reference method alongside the official analytical techniques for quality control purposes of contaminated waters. Moreover, the new method is amenable to automation by using commercial HS units.





Development of a large volume injection method using a programmed temperature vaporization injector – gas chromatography hyphenated to ICP-MS for the simultaneous determination of mercury, tin and lead species at ultra-trace levels in natural waters

Publication date: 27 April 2018
Source:Journal of Chromatography A, Volume 1547
Author(s): J. Terán-Baamonde, S. Bouchet, E. Tessier, D. Amouroux
The current EU legislation lays down Environmental Quality Standards (EQS) for 45 priority substances in surface waters; among them levels for (organo)metallic species of Hg, Sn and Pb are set between ng L−1 (for Hg and Sn) and μg L−1 (for Pb). To date, only a few analytical methods can reach these very restrictive limits and there is thus a need for comprehensive methods able to analyze these species down to these levels in natural waters. The aim of this work was to develop an online automated pre-concentration method using large volume injections with a Programmed Temperature Vaporization (PTV) injector fitted with a sorbent packed liner coupled to GC-ICP-MS to further improve the detection limits associated to this well-established method. The influence of several parameters such as the PTV transfer temperature and time, carrier gas flow rate and amount of packing material was investigated. Finally, the maximum volume injected through single or multiple injection modes was optimized to obtain the best compromise between chromatographic resolution and sensitivity. After optimization, very satisfactory results in terms of absolute and methodological detection limits were achieved, down to the pg L−1 level for all species studied. The potential of the method was exemplified by determining the concentrations of organometallic compounds in unpolluted river waters samples from the Adour river basin (SW France) and results were compared with conventional (splitless) GC-ICP-MS. The strength of this analytical method lies in the low detection limits reached for the simultaneous analysis of a wide group of organometallic compounds, and the potential to transfer this method to other gas chromatographic applications with inherent lower sensitivity.

Publication date: 27 April 2018
Source:Journal of Chromatography A, Volume 1547

Author(s): J. Terán-Baamonde, S. Bouchet, E. Tessier, D. Amouroux

The current EU legislation lays down Environmental Quality Standards (EQS) for 45 priority substances in surface waters; among them levels for (organo)metallic species of Hg, Sn and Pb are set between ng L−1 (for Hg and Sn) and μg L−1 (for Pb). To date, only a few analytical methods can reach these very restrictive limits and there is thus a need for comprehensive methods able to analyze these species down to these levels in natural waters. The aim of this work was to develop an online automated pre-concentration method using large volume injections with a Programmed Temperature Vaporization (PTV) injector fitted with a sorbent packed liner coupled to GC-ICP-MS to further improve the detection limits associated to this well-established method. The influence of several parameters such as the PTV transfer temperature and time, carrier gas flow rate and amount of packing material was investigated. Finally, the maximum volume injected through single or multiple injection modes was optimized to obtain the best compromise between chromatographic resolution and sensitivity. After optimization, very satisfactory results in terms of absolute and methodological detection limits were achieved, down to the pg L−1 level for all species studied. The potential of the method was exemplified by determining the concentrations of organometallic compounds in unpolluted river waters samples from the Adour river basin (SW France) and results were compared with conventional (splitless) GC-ICP-MS. The strength of this analytical method lies in the low detection limits reached for the simultaneous analysis of a wide group of organometallic compounds, and the potential to transfer this method to other gas chromatographic applications with inherent lower sensitivity.





Facile synthesis of hierarchical porous carbon from crude biomass for high-performance solid-phase microextraction

Publication date: 4 May 2018
Source:Journal of Chromatography A, Volume 1548
Author(s): Hu Cheng, Yang Song, Fang Wang, Rongting Ji, Xiaona Li, Yuhao Fu, Xinglun Yang, Yongrong Bian, Xin Jiang
Porous materials have great prospective applications for solid-phase microextraction (SPME) technology because of their large specific surface area and pore volume. In this study, a hierarchical porous carbon (HPC) was synthesized by simple hydrothermal reaction and potassium hydroxide (KOH) activation of crude biomass and found to be an efficient adsorbent for SPME of organic pollutants. Results show that the as-prepared HPC has a partly graphitic amorphous-like structure with ultrahigh specific surface area (2551 m2/g), high pore volume (1.53 cm3/g), good pore size distribution (PSD) (mesopore/micropore ratio of 68%), and great thermal stability (>450 °C). When we utilized it as SPME fiber coating, the extraction capacities for chlorobenzenes (CBs), polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), and phthalates (PAEs) were, respectively, 1.13–39.46, 2.40–7.78, 1.34–36.02, and 1.50–1.83 times higher than those of a commercial polydimethylsiloxane (PDMS) fiber. Under the optimized extraction conditions, an analytical method for CBs with low detection limits (0.01–0.24 ng/L), good repeatability (1.00%–4.93% for intra-day, 1.11%–6.94% for inter-day), and great reproducibility (1.48%–8.91%, n = 3) was developed. Moreover, we evaluated the practicality of the developed method for environmental water sample and obtained satisfactory recoveries (86.21%–104.34%). The findings provide a novel and promising HPC from crude biomass using a low-cost and facile synthetic route for SPME applications.

Publication date: 4 May 2018
Source:Journal of Chromatography A, Volume 1548

Author(s): Hu Cheng, Yang Song, Fang Wang, Rongting Ji, Xiaona Li, Yuhao Fu, Xinglun Yang, Yongrong Bian, Xin Jiang

Porous materials have great prospective applications for solid-phase microextraction (SPME) technology because of their large specific surface area and pore volume. In this study, a hierarchical porous carbon (HPC) was synthesized by simple hydrothermal reaction and potassium hydroxide (KOH) activation of crude biomass and found to be an efficient adsorbent for SPME of organic pollutants. Results show that the as-prepared HPC has a partly graphitic amorphous-like structure with ultrahigh specific surface area (2551 m2/g), high pore volume (1.53 cm3/g), good pore size distribution (PSD) (mesopore/micropore ratio of 68%), and great thermal stability (>450 °C). When we utilized it as SPME fiber coating, the extraction capacities for chlorobenzenes (CBs), polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), and phthalates (PAEs) were, respectively, 1.13–39.46, 2.40–7.78, 1.34–36.02, and 1.50–1.83 times higher than those of a commercial polydimethylsiloxane (PDMS) fiber. Under the optimized extraction conditions, an analytical method for CBs with low detection limits (0.01–0.24 ng/L), good repeatability (1.00%–4.93% for intra-day, 1.11%–6.94% for inter-day), and great reproducibility (1.48%–8.91%, n = 3) was developed. Moreover, we evaluated the practicality of the developed method for environmental water sample and obtained satisfactory recoveries (86.21%–104.34%). The findings provide a novel and promising HPC from crude biomass using a low-cost and facile synthetic route for SPME applications.





Quantitative determination of major oxidation products in edible oils by direct NP-HPLC-DAD analysis

Publication date: 27 April 2018
Source:Journal of Chromatography A, Volume 1547
Author(s): Joaquín Velasco, Arturo Morales-Barroso, M. Victoria Ruiz-Méndez, Gloria Márquez-Ruiz
The objective of the present study was to explore the possibilities of the direct analysis of vegetable oils by normal-phase HPLC-DAD to evaluate the amounts of the main oxidation products of triacylglycerols containing linoleate, i.e. hydroperoxy-, keto- and hydroxy-dienes. A follow-up of oxidation at 40 °C of trilinolein, used as a simplified model lipid system, high-linoleic sunflower oil and high-oleic sunflower oil was performed to evaluate samples with different fatty acid compositions and different oxidation levels. The results showed that the HPLC-DAD method proposed allows for determining the concentrations of mono-hydroperoxydienes in edible oils without applying any isolation or derivatization step. The method was found to be direct, sensitive (LOQ 0.06 mmol/kg oil), precise (CV ≤ 5%) and also accurate, with 99% of analyte recovery. It also enabled the estimation of the minor amounts of ketodienes, but not those of hydroxydienes, which presented wide chromatographic bands and coeluted with a number of different minor oxidation compounds.

Publication date: 27 April 2018
Source:Journal of Chromatography A, Volume 1547

Author(s): Joaquín Velasco, Arturo Morales-Barroso, M. Victoria Ruiz-Méndez, Gloria Márquez-Ruiz

The objective of the present study was to explore the possibilities of the direct analysis of vegetable oils by normal-phase HPLC-DAD to evaluate the amounts of the main oxidation products of triacylglycerols containing linoleate, i.e. hydroperoxy-, keto- and hydroxy-dienes. A follow-up of oxidation at 40 °C of trilinolein, used as a simplified model lipid system, high-linoleic sunflower oil and high-oleic sunflower oil was performed to evaluate samples with different fatty acid compositions and different oxidation levels. The results showed that the HPLC-DAD method proposed allows for determining the concentrations of mono-hydroperoxydienes in edible oils without applying any isolation or derivatization step. The method was found to be direct, sensitive (LOQ 0.06 mmol/kg oil), precise (CV ≤ 5%) and also accurate, with 99% of analyte recovery. It also enabled the estimation of the minor amounts of ketodienes, but not those of hydroxydienes, which presented wide chromatographic bands and coeluted with a number of different minor oxidation compounds.





A simple and highly sensitive on-line column extraction liquid chromatography-tandem mass spectrometry method for the determination of protein-unbound tacrolimus in human plasma samples

Publication date: 27 April 2018
Source:Journal of Chromatography A, Volume 1547
Author(s): Heike Bittersohl, Björn Schniedewind, Uwe Christians, Peter B. Luppa
Therapeutic drug monitoring (TDM) of the immunosuppressive drug tacrolimus is essential to avoid side effects and rejection of the allograft after transplantation. In the blood circulation, tacrolimus is largely located inside erythrocytes or bound to plasma proteins and less than 0.1% is protein-unbound (free). One basic principle of clinical pharmacology is that only free drug is pharmacologically active and monitoring this portion has the potential to better reflect the drug effect than conventional measurements of total tacrolimus in whole blood. To address this, a highly sensitive and straightforward on-line liquid chromatography-tandem mass spectrometry (LC–MS/MS) method was developed, validated and applied to patient plasma samples. The sample preparation included ultracentrifugation and addition of the stable isotope labeled drug analogue D2,13C-tacrolimus, followed by on-line sample extraction and measurement using a Sciex QTRAP® 6500 in the multiple reaction monitoring mode. Due to very low concentrations of protein-unbound tacrolimus, it was important to develop a highly sensitive, precise and accurate assay. Here, we first report the efficient formation of tacrolimus lithium adduct ions, which greatly increased assay sensitivity. A lower limit of quantification (LLOQ) of 1 pg/mL (10 fg on column) was achieved and the assay was linear between 1 and 200 pg/mL. There was no carry-over detected. The inaccuracy ranged from −9.8 to 7.4% and the greatest imprecision was 7.5%. The matrix factor was found to be smaller than 1.1%. In summary, this method represents a suitable tool to investigate the potential clinical value of free tacrolimus monitoring in organ transplant recipients.

Publication date: 27 April 2018
Source:Journal of Chromatography A, Volume 1547

Author(s): Heike Bittersohl, Björn Schniedewind, Uwe Christians, Peter B. Luppa

Therapeutic drug monitoring (TDM) of the immunosuppressive drug tacrolimus is essential to avoid side effects and rejection of the allograft after transplantation. In the blood circulation, tacrolimus is largely located inside erythrocytes or bound to plasma proteins and less than 0.1% is protein-unbound (free). One basic principle of clinical pharmacology is that only free drug is pharmacologically active and monitoring this portion has the potential to better reflect the drug effect than conventional measurements of total tacrolimus in whole blood. To address this, a highly sensitive and straightforward on-line liquid chromatography-tandem mass spectrometry (LC–MS/MS) method was developed, validated and applied to patient plasma samples. The sample preparation included ultracentrifugation and addition of the stable isotope labeled drug analogue D2,13C-tacrolimus, followed by on-line sample extraction and measurement using a Sciex QTRAP® 6500 in the multiple reaction monitoring mode. Due to very low concentrations of protein-unbound tacrolimus, it was important to develop a highly sensitive, precise and accurate assay. Here, we first report the efficient formation of tacrolimus lithium adduct ions, which greatly increased assay sensitivity. A lower limit of quantification (LLOQ) of 1 pg/mL (10 fg on column) was achieved and the assay was linear between 1 and 200 pg/mL. There was no carry-over detected. The inaccuracy ranged from −9.8 to 7.4% and the greatest imprecision was 7.5%. The matrix factor was found to be smaller than 1.1%. In summary, this method represents a suitable tool to investigate the potential clinical value of free tacrolimus monitoring in organ transplant recipients.





Poly(butylene terephthalate) based novel achiral stationary phase investigated under supercritical fluid chromatography conditions

Publication date: 11 May 2018 Source:Journal of Chromatography A, Volume 1549 Author(s): Kanji Nagai, Tohru Shibata, Satoshi Shinkura, Atsushi Ohnishi Poly(butylene terephthalate) based novel stationary phase (SP), composed of …

Publication date: 11 May 2018
Source:Journal of Chromatography A, Volume 1549

Author(s): Kanji Nagai, Tohru Shibata, Satoshi Shinkura, Atsushi Ohnishi

Poly(butylene terephthalate) based novel stationary phase (SP), composed of planar aromatic phenyl group together with ester group monomer units, was designed for supercritical fluid chromatography (SFC) use. As expected from its structure, this phase shows planarity recognition of isomeric aromatics and closely similar compounds. Interestingly, for most analytes, the retention behavior of this SP is significantly distinct from that of the 2-ethylpyridine based SPs which is among the most well-known SFC dedicated phases. Although the poly(butylene terephthalate) is coated on silica gel, the performance of the column did not change by using extended range modifiers such as THF, dichloromethane or ethyl acetate and column robustness was confirmed by cycle durability testing.





Characterization of plant polysaccharides from Dendrobium officinale by multiple chromatographic and mass spectrometric techniques

Publication date: 27 April 2018
Source:Journal of Chromatography A, Volume 1547
Author(s): Huiying Ma, Keke Zhang, Qing Jiang, Diya Dai, Hongli Li, Wentao Bi, David Da Yong Chen
Plant polysaccharides have numerous medicinal functions. Due to the differences in their origins, regions of production, and cultivation conditions, the quality and the functions of polysaccharides can vary significantly. They are macromolecules with large molecular weight (MW) and complex structure, and pose great challenge for the analytical technology used. Taking Dendrobium officinale (DO) from various origins and locations as model samples. In this investigation, mechanochemical extraction method was used to successfully extract polysaccharides from DO using water as solvent, the process is simple, fast (40 s) and with high yield. The MWs of the intact saccharides from calibration curve and light scattering measurement were determined and compared after separation with size exclusion chromatography (SEC). The large polysaccharide was acid hydrolyzed to oligosaccharides and the products were efficiently separated and identified using liquid chromatography coupled to a high resolution tandem mass spectrometry (LC–MS2). Obvious differences were observed among LC–MS2 chromatograms of digested products, and the chemical structures for the products were proposed based on accurate mass values. More importantly, isomeric digested carbohydrate compounds were explored and characterized. All the chromatographic and mass spectrometric results in this study provided a multi-dimensional characterization, fingerprint analysis, and molecular structure level assessment of plant polysaccharides.

Publication date: 27 April 2018
Source:Journal of Chromatography A, Volume 1547

Author(s): Huiying Ma, Keke Zhang, Qing Jiang, Diya Dai, Hongli Li, Wentao Bi, David Da Yong Chen

Plant polysaccharides have numerous medicinal functions. Due to the differences in their origins, regions of production, and cultivation conditions, the quality and the functions of polysaccharides can vary significantly. They are macromolecules with large molecular weight (MW) and complex structure, and pose great challenge for the analytical technology used. Taking Dendrobium officinale (DO) from various origins and locations as model samples. In this investigation, mechanochemical extraction method was used to successfully extract polysaccharides from DO using water as solvent, the process is simple, fast (40 s) and with high yield. The MWs of the intact saccharides from calibration curve and light scattering measurement were determined and compared after separation with size exclusion chromatography (SEC). The large polysaccharide was acid hydrolyzed to oligosaccharides and the products were efficiently separated and identified using liquid chromatography coupled to a high resolution tandem mass spectrometry (LC–MS2). Obvious differences were observed among LC–MS2 chromatograms of digested products, and the chemical structures for the products were proposed based on accurate mass values. More importantly, isomeric digested carbohydrate compounds were explored and characterized. All the chromatographic and mass spectrometric results in this study provided a multi-dimensional characterization, fingerprint analysis, and molecular structure level assessment of plant polysaccharides.





High temperature multidimensional gas chromatographic approach for improved separation of triacylglycerols in olive oil

Publication date: 11 May 2018
Source:Journal of Chromatography A, Volume 1549
Author(s): Habtewold D. Waktola, Chadin Kulsing, Yada Nolvachai, Philip J. Marriott
Heart-cut multidimensional gas chromatographic (H/C MDGC) methods under suitable flow and high temperature (T) program conditions were developed to separate olive oil triacylglycerols (TAGs). Different column sets were selected for further evaluation, each with relatively short non-polar first dimension (1D) and mid-polar second dimension (2D) columns of high T limits (350 °C). The 1D separation displayed three major groups of peaks in an area ratio of approximately 5:33:62 (of increasing retention), using flame ionisation detection (FID). Four groups of minor peaks, with 2 of them located between the major peaks, were also detected. The H/C fractions of the minor peaks, and sub-sampled regions across the major peaks eluting from the 1D outlet, were cryotrapped at the 2D inlet. The trapped TAGs then underwent temperature programmed 2D separation. Each of the ‘H/C’ zones generally gave 2–5 – and in some cases more – separated peaks of TAGs on the 2D column, under suitable flow condition and phase polarity that resulted in improved separation. Six sub-sampled H/Cs from various regions of the individual peaks from the 1D column were simultaneously trapped and released to 2D, resulting in apparently more than 22 individual TAG peaks. According to their different retention times, different TAGs were revealed within each of the 3 major groups, using H/C sub-sampling. A comprehensive sampling strategy that covers most of the 1D peaks further revealed the presence of more TAGs in the olive oil sample. This tandem column strategy was able to resolve more components than that usually observed on a single column.

Publication date: 11 May 2018
Source:Journal of Chromatography A, Volume 1549

Author(s): Habtewold D. Waktola, Chadin Kulsing, Yada Nolvachai, Philip J. Marriott

Heart-cut multidimensional gas chromatographic (H/C MDGC) methods under suitable flow and high temperature (T) program conditions were developed to separate olive oil triacylglycerols (TAGs). Different column sets were selected for further evaluation, each with relatively short non-polar first dimension (1D) and mid-polar second dimension (2D) columns of high T limits (350 °C). The 1D separation displayed three major groups of peaks in an area ratio of approximately 5:33:62 (of increasing retention), using flame ionisation detection (FID). Four groups of minor peaks, with 2 of them located between the major peaks, were also detected. The H/C fractions of the minor peaks, and sub-sampled regions across the major peaks eluting from the 1D outlet, were cryotrapped at the 2D inlet. The trapped TAGs then underwent temperature programmed 2D separation. Each of the ‘H/C’ zones generally gave 2–5 – and in some cases more – separated peaks of TAGs on the 2D column, under suitable flow condition and phase polarity that resulted in improved separation. Six sub-sampled H/Cs from various regions of the individual peaks from the 1D column were simultaneously trapped and released to 2D, resulting in apparently more than 22 individual TAG peaks. According to their different retention times, different TAGs were revealed within each of the 3 major groups, using H/C sub-sampling. A comprehensive sampling strategy that covers most of the 1D peaks further revealed the presence of more TAGs in the olive oil sample. This tandem column strategy was able to resolve more components than that usually observed on a single column.





Determination of finasteride and its metabolite in urine by dispersive liquid–liquid microextraction combined with field-enhanced sample stacking and sweeping

Publication date: 27 April 2018
Source:Journal of Chromatography A, Volume 1547
Author(s): Chun-Hsien Chen, Yu-Ying Chao, Yi-Hui Lin, Yen-Ling Chen
The on-line preconcentration technique of field-enhanced sample stacking and sweeping (FESS-sweeping) are combined with dispersive liquid–liquid microextraction (DLLME) to monitor the concentrations of finasteride, which is used in the treatment of androgenetic alopecia, and its metabolite, finasteride carboxylic acid (M3), in urine samples. DLLME is used to concentrate and eliminate the interferences of urine samples and uses chloroform as an extracting solvent and acetonitrile as a disperser solvent. A high conductivity buffer (HCB) was introduced into capillary and then sample plug (90.7% capillary length) was injected into capillary. After applying voltage, the sodium dodecyl sulfate (SDS) swept the analytes from the low conductivity sample solution into HCB. The analytes were concentrated on the field-enhanced sample stacking boundary. The limit of detection for the analytes is 20 ng mL−1. The sensitivity enrichment of finasteride and M3 are 362-fold and 480-fold, respectively, compared with the conventional MEKC method. The on-line preconcentration technique of field-enhanced sample stacking and sweeping possess good selectivity because the endogenous steroid did not interfere the detection of finasteride and M3. The analytical technique is applied to investigate the concentrations in urine samples from patients who have been administered finasteride for the treatment of androgenetic alopecia; the amount of M3 detected in 12 h was 72.69 ± 4.18 μg.

Publication date: 27 April 2018
Source:Journal of Chromatography A, Volume 1547

Author(s): Chun-Hsien Chen, Yu-Ying Chao, Yi-Hui Lin, Yen-Ling Chen

The on-line preconcentration technique of field-enhanced sample stacking and sweeping (FESS-sweeping) are combined with dispersive liquid–liquid microextraction (DLLME) to monitor the concentrations of finasteride, which is used in the treatment of androgenetic alopecia, and its metabolite, finasteride carboxylic acid (M3), in urine samples. DLLME is used to concentrate and eliminate the interferences of urine samples and uses chloroform as an extracting solvent and acetonitrile as a disperser solvent. A high conductivity buffer (HCB) was introduced into capillary and then sample plug (90.7% capillary length) was injected into capillary. After applying voltage, the sodium dodecyl sulfate (SDS) swept the analytes from the low conductivity sample solution into HCB. The analytes were concentrated on the field-enhanced sample stacking boundary. The limit of detection for the analytes is 20 ng mL−1. The sensitivity enrichment of finasteride and M3 are 362-fold and 480-fold, respectively, compared with the conventional MEKC method. The on-line preconcentration technique of field-enhanced sample stacking and sweeping possess good selectivity because the endogenous steroid did not interfere the detection of finasteride and M3. The analytical technique is applied to investigate the concentrations in urine samples from patients who have been administered finasteride for the treatment of androgenetic alopecia; the amount of M3 detected in 12 h was 72.69 ± 4.18 μg.





Utility of a high coverage phenyl-bonding and wide-pore superficially porous particle for the analysis of monoclonal antibodies and related products

Publication date: 11 May 2018
Source:Journal of Chromatography A, Volume 1549
Author(s): Balázs Bobály, Matthew Lauber, Alain Beck, Davy Guillarme, Szabolcs Fekete
A wide-pore silica-based superficially porous material with a high coverage phenyl bonding was evaluated for the analysis of monoclonal antibodies and antibody-drug conjugates. This new material is based on 2.7 μm particles having a shell thickness of 0.40 μm and average pore size of approximately 450 Å.Various important features of this reversed phase column technology were explored, including kinetic performance for large biomolecules (i.e. speed of analysis, efficiency and peak capacity), recovery of proteins, selectivity for resolving modifications, and the possibility to reduce the amount of trifluoroacetic acid in the mobile phase. A systematic comparison was also performed with other existing modern wide-pore phases possessing differences in structure/morphology and chemistry.If all these figures of merit are considered, it is clear that this phenyl bonded wide-pore superficially porous stationary phase is one of the most promising materials to have been developed in recent years. Indeed, it offers kinetic performance comparable to the most efficient wide-pore SPP column on the market. In terms of protein recovery, this new phase was found to be superior to silica-based and silica-hybrid C4 bonded materials, particularly with separations performed at sub-80 °C temperature. Under such conditions, it in fact shows recoveries that are quite similar to a divinyl benzene (DVB) polymer-based material. More importantly, due to its unique, high coverage phenyl bonding, it offers additional steric effects and potentially even π-π interactions that yield advantageous selectivity for mAb sub-unit peaks and ADC species as compared to commonly used C4 or C18 bonded phases. Last but not least, mobile phases consisting of only 0.02–0.05% trifluoroacetic acid can be successfully used with this column, without significant loss in recovery and peak capacity.

Publication date: 11 May 2018
Source:Journal of Chromatography A, Volume 1549

Author(s): Balázs Bobály, Matthew Lauber, Alain Beck, Davy Guillarme, Szabolcs Fekete

A wide-pore silica-based superficially porous material with a high coverage phenyl bonding was evaluated for the analysis of monoclonal antibodies and antibody-drug conjugates. This new material is based on 2.7 μm particles having a shell thickness of 0.40 μm and average pore size of approximately 450 Å. Various important features of this reversed phase column technology were explored, including kinetic performance for large biomolecules (i.e. speed of analysis, efficiency and peak capacity), recovery of proteins, selectivity for resolving modifications, and the possibility to reduce the amount of trifluoroacetic acid in the mobile phase. A systematic comparison was also performed with other existing modern wide-pore phases possessing differences in structure/morphology and chemistry. If all these figures of merit are considered, it is clear that this phenyl bonded wide-pore superficially porous stationary phase is one of the most promising materials to have been developed in recent years. Indeed, it offers kinetic performance comparable to the most efficient wide-pore SPP column on the market. In terms of protein recovery, this new phase was found to be superior to silica-based and silica-hybrid C4 bonded materials, particularly with separations performed at sub-80 °C temperature. Under such conditions, it in fact shows recoveries that are quite similar to a divinyl benzene (DVB) polymer-based material. More importantly, due to its unique, high coverage phenyl bonding, it offers additional steric effects and potentially even π-π interactions that yield advantageous selectivity for mAb sub-unit peaks and ADC species as compared to commonly used C4 or C18 bonded phases. Last but not least, mobile phases consisting of only 0.02–0.05% trifluoroacetic acid can be successfully used with this column, without significant loss in recovery and peak capacity.





QSRR modeling for the chromatographic retention behavior of some β-lactam antibiotics using forward and firefly variable selection algorithms coupled with multiple linear regression

Publication date: 11 May 2018
Source:Journal of Chromatography A, Volume 1549
Author(s): Marwa A. Fouad, Enas H. Tolba, Manal A. El-Shal, Ahmed M. El Kerdawy
The justified continuous emerging of new β-lactam antibiotics provokes the need for developing suitable analytical methods that accelerate and facilitate their analysis. A face central composite experimental design was adopted using different levels of phosphate buffer pH, acetonitrile percentage at zero time and after 15 min in a gradient program to obtain the optimum chromatographic conditions for the elution of 31 β-lactam antibiotics. Retention factors were used as the target property to build two QSRR models utilizing the conventional forward selection and the advanced nature-inspired firefly algorithm for descriptor selection, coupled with multiple linear regression. The obtained models showed high performance in both internal and external validation indicating their robustness and predictive ability. Williams-Hotelling test and student’s t-test showed that there is no statistical significant difference between the models’ results. Y-randomization validation showed that the obtained models are due to significant correlation between the selected molecular descriptors and the analytes’ chromatographic retention. These results indicate that the generated FS-MLR and FFA-MLR models are showing comparable quality on both the training and validation levels. They also gave comparable information about the molecular features that influence the retention behavior of β-lactams under the current chromatographic conditions. We can conclude that in some cases simple conventional feature selection algorithm can be used to generate robust and predictive models comparable to that are generated using advanced ones.

Publication date: 11 May 2018
Source:Journal of Chromatography A, Volume 1549

Author(s): Marwa A. Fouad, Enas H. Tolba, Manal A. El-Shal, Ahmed M. El Kerdawy

The justified continuous emerging of new β-lactam antibiotics provokes the need for developing suitable analytical methods that accelerate and facilitate their analysis. A face central composite experimental design was adopted using different levels of phosphate buffer pH, acetonitrile percentage at zero time and after 15 min in a gradient program to obtain the optimum chromatographic conditions for the elution of 31 β-lactam antibiotics. Retention factors were used as the target property to build two QSRR models utilizing the conventional forward selection and the advanced nature-inspired firefly algorithm for descriptor selection, coupled with multiple linear regression. The obtained models showed high performance in both internal and external validation indicating their robustness and predictive ability. Williams-Hotelling test and student’s t-test showed that there is no statistical significant difference between the models’ results. Y-randomization validation showed that the obtained models are due to significant correlation between the selected molecular descriptors and the analytes’ chromatographic retention. These results indicate that the generated FS-MLR and FFA-MLR models are showing comparable quality on both the training and validation levels. They also gave comparable information about the molecular features that influence the retention behavior of β-lactams under the current chromatographic conditions. We can conclude that in some cases simple conventional feature selection algorithm can be used to generate robust and predictive models comparable to that are generated using advanced ones.





Preparative concentration of nucleic acids fragments by capillary isotachophoretic analyzer

Publication date: 4 May 2018
Source:Journal of Chromatography A, Volume 1548
Author(s): Vladimíra Datinská, Ivona Voráčová, Jan Berka, František Foret
Sample preparation plays an important role in the DNA analysis workflow. Real samples often include a complex matrix, such as blood and other bodily fluids, or exogenous impurities, e.g., from the scene of crime. Most of the common nucleic acids isolation techniques are based on extractions; however, isotachophoretic focusing has recently attracted some interest for its simplicity and potential for very high enrichment factors and ease of automation. Here, we report on the use of a commercial isotachophoretic instrument for optimization of DNA focusing and preparative fraction collection. In order to achieve a high recovery and enrichment, experimental factors including electric current, sample amount and matrix were investigated experimentally as well as by computer simulation. The sample of a DNA ladder was injected in 30 μl volume and after ITP focusing the DNA zone was recovered using an on-column micropreparative collection valve. The DNA content in the collected sample was verified by fluorescence spectrometry and chip capillary electrophoresis with fluorescence detection.

Publication date: 4 May 2018
Source:Journal of Chromatography A, Volume 1548

Author(s): Vladimíra Datinská, Ivona Voráčová, Jan Berka, František Foret

Sample preparation plays an important role in the DNA analysis workflow. Real samples often include a complex matrix, such as blood and other bodily fluids, or exogenous impurities, e.g., from the scene of crime. Most of the common nucleic acids isolation techniques are based on extractions; however, isotachophoretic focusing has recently attracted some interest for its simplicity and potential for very high enrichment factors and ease of automation. Here, we report on the use of a commercial isotachophoretic instrument for optimization of DNA focusing and preparative fraction collection. In order to achieve a high recovery and enrichment, experimental factors including electric current, sample amount and matrix were investigated experimentally as well as by computer simulation. The sample of a DNA ladder was injected in 30 μl volume and after ITP focusing the DNA zone was recovered using an on-column micropreparative collection valve. The DNA content in the collected sample was verified by fluorescence spectrometry and chip capillary electrophoresis with fluorescence detection.





Supercritical fluid chromatography versus high performance liquid chromatography for enantiomeric and diastereoisomeric separations on coated polysaccharides-based stationary phases: Application to dihydropyridone derivatives

Publication date: 11 May 2018
Source:Journal of Chromatography A, Volume 1549
Author(s): Vanessa Hoguet, Julie Charton, Paul-Emile Hecquet, Chahinaze Lakhmi, Emmanuelle Lipka
For analytical applications, SFC has always remained in the shadow of LC. Analytical enantioseparation of eight dihydropyridone derivatives, was run in both High Performance Liquid Chromatography and Supercritical Fluid Chromatography. Four polysaccharide based chiral stationary phases namely amylose and cellulose tris(3, 5-dimethylphenylcarbamate), amylose tris((S)-α-phenylethylcarbamate) and cellulose tris(4-methylbenzoate) with four mobile phases consisted of either n-hexane/ethanol or propan-2-ol (80:20 v:v) or carbon dioxide/ethanol or propan-2-ol (80:20 v:v) mixtures were investigated under same operatory conditions (temperature and flow-rate). The elution strength, enantioselectivity and resolution were compared in the two methodologies. For these compounds, for most of the conditions, HPLC afforded shorter retention times and a higher resolution than SFC. HPLC appears particularly suitable for the separation of the compounds bearing two chiral centers. For instance compound 7 was baseline resolved on OD-H CSP under n-Hex/EtOH 80/20, with resolution values equal to 2.98, 1.55, 4.52, between the four stereoisomers in less than 17 min, whereas in SFC, this latter is not fully separated in 23 min under similar eluting conditions. After analytical screenings, the best conditions were transposed to semi-preparative scale.

Publication date: 11 May 2018
Source:Journal of Chromatography A, Volume 1549

Author(s): Vanessa Hoguet, Julie Charton, Paul-Emile Hecquet, Chahinaze Lakhmi, Emmanuelle Lipka

For analytical applications, SFC has always remained in the shadow of LC. Analytical enantioseparation of eight dihydropyridone derivatives, was run in both High Performance Liquid Chromatography and Supercritical Fluid Chromatography. Four polysaccharide based chiral stationary phases namely amylose and cellulose tris(3, 5-dimethylphenylcarbamate), amylose tris((S)-α-phenylethylcarbamate) and cellulose tris(4-methylbenzoate) with four mobile phases consisted of either n-hexane/ethanol or propan-2-ol (80:20 v:v) or carbon dioxide/ethanol or propan-2-ol (80:20 v:v) mixtures were investigated under same operatory conditions (temperature and flow-rate). The elution strength, enantioselectivity and resolution were compared in the two methodologies. For these compounds, for most of the conditions, HPLC afforded shorter retention times and a higher resolution than SFC. HPLC appears particularly suitable for the separation of the compounds bearing two chiral centers. For instance compound 7 was baseline resolved on OD-H CSP under n-Hex/EtOH 80/20, with resolution values equal to 2.98, 1.55, 4.52, between the four stereoisomers in less than 17 min, whereas in SFC, this latter is not fully separated in 23 min under similar eluting conditions. After analytical screenings, the best conditions were transposed to semi-preparative scale.





Enzyme assay for d-amino acid oxidase using optically gated capillary electrophoresis-laser induced fluorescence detection

Publication date: 4 May 2018
Source:Journal of Chromatography A, Volume 1548
Author(s): Ning Zhang, Miaomiao Tian, Xin Liu, Li Yang
Because d-amino acids (AAs) play an essential role in the regulation of many processes in living cells, detection of D-AAs and assay of d-amino acid oxidase (DAAO) activity are of vital importance in bioanalytical science. However, the reliability and accuracy of DAAO assays could be interfered due to the facts that DAAO presents broad substrate activity towards different D-AAs and there could be abundant L-AA enantiomers in biological samples. In this study we presented the first application of optically gated capillary electrophoresis with LIF detection (OGCE-LIF) for efficient assay of DAAO activity. High repeatability of the OGCE-LIF assay of amino acids (AAs) was achieved with relative standard deviation (RSD) (n = 15) less than 1.5% and 2.7% for migration time and peak height, respectively. Under the optimal OGCE-LIF conditions, five pairs of D/L-AA enantiomers were efficiently separated in less than 1 min with low limit of detection of 1.3 μM. Enzymatic assays of DAAO were successfully achieved by detection the substrate consumption with OGCE-LIF, for either single or mixed AA substrates. Kinetic analysis of the parallel oxidation reactions of two different substrates was performed, which was in good agreement with the experimental results. Our study indicates OGCE-LIF can perform rapid and efficient separation of mixed pairs of AA enantiomers and is a promising method for quantitatively assaying DAAO catalyzed reaction with the presence of L-AA enantiomers in the sample. Our study would pave the way for accurate determination of D-AAs and DAAO enzymes in complicated biological samples.

Publication date: 4 May 2018
Source:Journal of Chromatography A, Volume 1548

Author(s): Ning Zhang, Miaomiao Tian, Xin Liu, Li Yang

Because d-amino acids (AAs) play an essential role in the regulation of many processes in living cells, detection of D-AAs and assay of d-amino acid oxidase (DAAO) activity are of vital importance in bioanalytical science. However, the reliability and accuracy of DAAO assays could be interfered due to the facts that DAAO presents broad substrate activity towards different D-AAs and there could be abundant L-AA enantiomers in biological samples. In this study we presented the first application of optically gated capillary electrophoresis with LIF detection (OGCE-LIF) for efficient assay of DAAO activity. High repeatability of the OGCE-LIF assay of amino acids (AAs) was achieved with relative standard deviation (RSD) (n = 15) less than 1.5% and 2.7% for migration time and peak height, respectively. Under the optimal OGCE-LIF conditions, five pairs of D/L-AA enantiomers were efficiently separated in less than 1 min with low limit of detection of 1.3 μM. Enzymatic assays of DAAO were successfully achieved by detection the substrate consumption with OGCE-LIF, for either single or mixed AA substrates. Kinetic analysis of the parallel oxidation reactions of two different substrates was performed, which was in good agreement with the experimental results. Our study indicates OGCE-LIF can perform rapid and efficient separation of mixed pairs of AA enantiomers and is a promising method for quantitatively assaying DAAO catalyzed reaction with the presence of L-AA enantiomers in the sample. Our study would pave the way for accurate determination of D-AAs and DAAO enzymes in complicated biological samples.





Validation and application of analytical method for glyphosate and glufosinate in foods by liquid chromatography-tandem mass spectrometry

Publication date: 11 May 2018
Source:Journal of Chromatography A, Volume 1549
Author(s): Yang Liao, Jean-Marie Berthion, Isabelle Colet, Mathilde Merlo, Alexandre Nougadère, Renwei Hu
A reliable and sensitive method was developed for simultaneous determination of glyphosate and glufosinate in various food products by liquid chromatography-tandem mass spectrometry. Based on extraction, derivatization with 9-fluorenylmethylchloroformate and purification on solid phase extraction column, quantification was done by using isotopic-labeled analytes as internal standard and calibration in matrix. Good selectivity and sensitivity were achieved with a limit of quantification of 5 μg/kg. The recoveries of these two pesticides ranged from 91% to 114% with inter-day and relative standard deviation of 3.8–6.1% in five matrices of cereal group spiked at 5, 10, and 20 μg/kg. An accuracy profile was performed for method validation, demonstrating the accuracy and precision of the method for the studied food groups. The verification results in expanded food groups indicated extensive applicability for the analysis of glyphosate and glufosinate. Finally, the developed method was applied to analyze 136 food samples including milk-based baby foods from the French Agency for Food, Environmental and Occupational Health & Safety. Glyphosate residues were detected in two breakfast cereal samples (6.0 and 34 μg/kg). Glufosinate residues were found in a sample of boiled potatoes (9.8 μg/kg). No residues were detected in the other samples, including milk-based baby foods with limits of detection ranging from 1 to 2 μg/kg. The method has been applied for routine national monitoring of glyphosate and glufosinate in various foods.

Publication date: 11 May 2018
Source:Journal of Chromatography A, Volume 1549

Author(s): Yang Liao, Jean-Marie Berthion, Isabelle Colet, Mathilde Merlo, Alexandre Nougadère, Renwei Hu

A reliable and sensitive method was developed for simultaneous determination of glyphosate and glufosinate in various food products by liquid chromatography-tandem mass spectrometry. Based on extraction, derivatization with 9-fluorenylmethylchloroformate and purification on solid phase extraction column, quantification was done by using isotopic-labeled analytes as internal standard and calibration in matrix. Good selectivity and sensitivity were achieved with a limit of quantification of 5 μg/kg. The recoveries of these two pesticides ranged from 91% to 114% with inter-day and relative standard deviation of 3.8–6.1% in five matrices of cereal group spiked at 5, 10, and 20 μg/kg. An accuracy profile was performed for method validation, demonstrating the accuracy and precision of the method for the studied food groups. The verification results in expanded food groups indicated extensive applicability for the analysis of glyphosate and glufosinate. Finally, the developed method was applied to analyze 136 food samples including milk-based baby foods from the French Agency for Food, Environmental and Occupational Health & Safety. Glyphosate residues were detected in two breakfast cereal samples (6.0 and 34 μg/kg). Glufosinate residues were found in a sample of boiled potatoes (9.8 μg/kg). No residues were detected in the other samples, including milk-based baby foods with limits of detection ranging from 1 to 2 μg/kg. The method has been applied for routine national monitoring of glyphosate and glufosinate in various foods.