Simultaneous analysis of perfluoroalkyl and polyfluoroalkyl substances including ultrashort-chain C2 and C3 compounds in rain and river water samples by ultra performance convergence chromatography

Publication date: 3 November 2017
Source:Journal of Chromatography A, Volume 1522
Author(s): Leo W.Y. Yeung, Christopher Stadey, Scott A. Mabury
An analytical method using ultra performance convergence chromatography (UPC2) coupled to a tandem mass spectrometer operated in negative electrospray mode was developed to measure perfluoroalkyl and polyfluoroalkyl substances (PFASs) including the ultrashort-chain PFASs (C2-C3). Compared to the existing liquid chromatography tandem mass spectrometry method using an ion exchange column, the new method has a lower detection limit (0.4pg trifluoroacetate (TFA) on-column), narrower peak width (3–6s), and a shorter run time (8min). Using the same method, different classes of PFASs (e.g., perfluoroalkyl sulfonates (PFSAs) and perfluorinated carboxylates (PFCAs), perfluorinated phosphonates (PFPAs) and phosphinates (PFPiAs), polyfluoroalkyl phosphate diesters (diPAPs)) can be measured in a single analysis. Rain (n=2) and river water (n=2) samples collected in Toronto, ON, were used for method validation and application. Results showed that short-chain PFAS (C2-C7 PFCAs and C4 PFSA) contributed to over 80% of the detectable PFASs in rain samples and the C2-C3 PFASs alone accounted for over 40% of the total. Reports on environmental levels of these ultrashort-chain PFASs are relatively scarce. Relatively large contribution of these ultrashort-chain PFASs to the total PFASs indicate the need to include the measurement of short-chain PFASs, especially C2 and C3 PFASs, in environmental monitoring. The sources of TFA and other short-chain PFASs in the environment are not entirely clear. The newly developed analytical method may help further investigation on the sources and the environmental levels of these ultrashort-chain PFASs.

Publication date: 3 November 2017
Source:Journal of Chromatography A, Volume 1522

Author(s): Leo W.Y. Yeung, Christopher Stadey, Scott A. Mabury

An analytical method using ultra performance convergence chromatography (UPC2) coupled to a tandem mass spectrometer operated in negative electrospray mode was developed to measure perfluoroalkyl and polyfluoroalkyl substances (PFASs) including the ultrashort-chain PFASs (C2-C3). Compared to the existing liquid chromatography tandem mass spectrometry method using an ion exchange column, the new method has a lower detection limit (0.4pg trifluoroacetate (TFA) on-column), narrower peak width (3–6s), and a shorter run time (8min). Using the same method, different classes of PFASs (e.g., perfluoroalkyl sulfonates (PFSAs) and perfluorinated carboxylates (PFCAs), perfluorinated phosphonates (PFPAs) and phosphinates (PFPiAs), polyfluoroalkyl phosphate diesters (diPAPs)) can be measured in a single analysis. Rain (n = 2) and river water (n = 2) samples collected in Toronto, ON, were used for method validation and application. Results showed that short-chain PFAS (C2-C7 PFCAs and C4 PFSA) contributed to over 80% of the detectable PFASs in rain samples and the C2-C3 PFASs alone accounted for over 40% of the total. Reports on environmental levels of these ultrashort-chain PFASs are relatively scarce. Relatively large contribution of these ultrashort-chain PFASs to the total PFASs indicate the need to include the measurement of short-chain PFASs, especially C2 and C3 PFASs, in environmental monitoring. The sources of TFA and other short-chain PFASs in the environment are not entirely clear. The newly developed analytical method may help further investigation on the sources and the environmental levels of these ultrashort-chain PFASs.





Comparative assessment of software for non-targeted data analysis in the study of volatile fingerprint changes during storage of a strawberry beverage

Publication date: 3 November 2017
Source:Journal of Chromatography A, Volume 1522
Author(s): M.L. Morales, R.M. Callejón, J.L. Ordóñez, A.M. Troncoso, M.C. García-Parrilla
Five free software packages were compared to assess their utility for the non-targeted study of changes in the volatile profile during the storage of a novel strawberry beverage. AMDIS coupled to Gavin software turned out to be easy to use, required the minimum handling for subsequent data treatment and its results were the most similar to those obtained by manual integration. However, AMDIS coupled to SpectConnect software provided more information for the study of volatile profile changes during the storage of strawberry beverage. During storage, volatile profile changed producing the differentiation among the strawberry beverage stored at different temperatures, and this difference increases as time passes; these results were also supported by PCA. As expected, it seems that cold temperature is the best way of preservation for this product during long time storage. Variable Importance in the Projection (VIP) and correlation scores pointed out four volatile compounds as potential markers for shelf-life of our strawberry beverage: 2-phenylethyl acetate, decanoic acid, γ-decalactone and furfural.

Publication date: 3 November 2017
Source:Journal of Chromatography A, Volume 1522

Author(s): M.L. Morales, R.M. Callejón, J.L. Ordóñez, A.M. Troncoso, M.C. García-Parrilla

Five free software packages were compared to assess their utility for the non-targeted study of changes in the volatile profile during the storage of a novel strawberry beverage. AMDIS coupled to Gavin software turned out to be easy to use, required the minimum handling for subsequent data treatment and its results were the most similar to those obtained by manual integration. However, AMDIS coupled to SpectConnect software provided more information for the study of volatile profile changes during the storage of strawberry beverage. During storage, volatile profile changed producing the differentiation among the strawberry beverage stored at different temperatures, and this difference increases as time passes; these results were also supported by PCA. As expected, it seems that cold temperature is the best way of preservation for this product during long time storage. Variable Importance in the Projection (VIP) and correlation scores pointed out four volatile compounds as potential markers for shelf-life of our strawberry beverage: 2-phenylethyl acetate, decanoic acid, γ-decalactone and furfural.





Simultaneous determination of acrylamide and 4-hydroxy-2,5-dimethyl-3(2H)-furanone in baby food by liquid chromatography–tandem mass spectrometry

Publication date: 3 November 2017
Source:Journal of Chromatography A, Volume 1522
Author(s): Mateus Henrique Petrarca, Maria Aparecida Rosa, Sonia Claudia Nascimento Queiroz, Helena Teixeira Godoy
A liquid chromatography triple quadrupole mass spectrometry method was developed and validated for the simultaneous determination of acrylamide and 4-hydroxy-2,5-dimethyl-3(2H)-furanone (HDMF) in baby food. The sample preparation involves acetonitrile-based extraction combined with dispersive primary secondary amine (PSA) cleanup and cation-exchange solid-phase extraction (SPE), which promotes efficient removal of matrix interferences. Analytical selectivity and sensitivity were achieved for the quantification of acrylamide and HDMF in complex matrices such as fruit, cereal and milk-based baby foods; furthermore, adequate linearity (range 10–300μgkg−1) in solvent and matrix-matched calibration curves, and appropriate recoveries (94–110%) and precision (RSD≤10%), under repeatability and within-laboratory reproducibility conditions, were also obtained. Expanded measurement uncertainty was estimated at the 20μgkg−1 level (limit of quantification) on the basis of data obtained from in-house validation, with values of 25.5 and 16.5% for acrylamide and HDMF, respectively. The fitness for purpose of developed method was verified by analyzing 15 commercial baby foods available in the Brazilian market. Acrylamide was detected in one plum-based baby food (35μgkg−1) while HDMF in 67% of the samples analyzed (levels between 25 and 262μgkg−1).

Publication date: 3 November 2017
Source:Journal of Chromatography A, Volume 1522

Author(s): Mateus Henrique Petrarca, Maria Aparecida Rosa, Sonia Claudia Nascimento Queiroz, Helena Teixeira Godoy

A liquid chromatography triple quadrupole mass spectrometry method was developed and validated for the simultaneous determination of acrylamide and 4-hydroxy-2,5-dimethyl-3(2H)-furanone (HDMF) in baby food. The sample preparation involves acetonitrile-based extraction combined with dispersive primary secondary amine (PSA) cleanup and cation-exchange solid-phase extraction (SPE), which promotes efficient removal of matrix interferences. Analytical selectivity and sensitivity were achieved for the quantification of acrylamide and HDMF in complex matrices such as fruit, cereal and milk-based baby foods; furthermore, adequate linearity (range 10–300μgkg−1) in solvent and matrix-matched calibration curves, and appropriate recoveries (94–110%) and precision (RSD10%), under repeatability and within-laboratory reproducibility conditions, were also obtained. Expanded measurement uncertainty was estimated at the 20μgkg−1 level (limit of quantification) on the basis of data obtained from in-house validation, with values of 25.5 and 16.5% for acrylamide and HDMF, respectively. The fitness for purpose of developed method was verified by analyzing 15 commercial baby foods available in the Brazilian market. Acrylamide was detected in one plum-based baby food (35μgkg−1) while HDMF in 67% of the samples analyzed (levels between 25 and 262μgkg−1).





Qualitative and quantitative analysis of heparin and low molecular weight heparins using size exclusion chromatography with multiple angle laser scattering/refractive index and inductively coupled plasma/mass spectrometry detectors

Publication date: 3 November 2017 Source:Journal of Chromatography A, Volume 1522 Author(s): Yilan Ouyang, Yangyang Zeng, Lin Yi, Hong Tang, Duxin Li, Robert J. Linhardt, Zhenqing Zhang Heparin, a highly sulfated glycosam…

Publication date: 3 November 2017
Source:Journal of Chromatography A, Volume 1522

Author(s): Yilan Ouyang, Yangyang Zeng, Lin Yi, Hong Tang, Duxin Li, Robert J. Linhardt, Zhenqing Zhang

Heparin, a highly sulfated glycosaminoglycan, has been used as a clinical anticoagulant over 80 years. Low molecular weight heparins (LMWHs), heparins partially depolymerized using different processes, are widely used as clinical anticoagulants. Qualitative molecular weight (MW) and quantitative mass content analysis are two important factors that contribute to LMWH quality control. Size exclusion chromatography (SEC), relying on multiple angle laser scattering (MALS)/refractive index (RI) detectors, has been developed for accurate analysis of heparin MW in the absence of standards. However, the cations, which ion-pair with the anionic polysaccharide chains of heparin and LMWHs, had not been considered in previous reports. In this study, SEC with MALS/RI and inductively coupled plasma/mass spectrometry detectors were used in a comprehensive analytical approach taking both anionic polysaccharide and ion-paired cations heparin products. This approach was also applied to quantitative analysis of heparin and LMWHs. Full profiles of MWs and mass recoveries for three commercial heparin/LMWH products, heparin sodium, enoxaparin sodium and nadroparin calcium, were obtained and all showed higher MWs than previously reported. This important improvement more precisely characterized the MW properties of heparin/LMWHs and potentially many other anionic polysaccharides.





Determination of the bioavailability of selected pharmaceutical residues in fish plasma using liquid chromatography coupled to tandem mass spectrometry

Publication date: 3 November 2017
Source:Journal of Chromatography A, Volume 1522
Author(s): S. Poirier Larabie, M. Houde, C. Gagnon
Aquatic systems near major urban centers are constantly contaminated with effluent from wastewater treatment plants. Pharmaceuticals are part of the contamination and several classes of drugs have been detected in surface waters in the last decade. To better understand the impact of those pharmaceuticals in ecosystems, the exposure to aquatic species needs to be investigated. This study presents a new simple and rugged quantitative method for the determination of several classes of drugs using 100μL of plasma from fish environmentally exposed to a major but highly diluted urban effluent. Six common drugs (i.e., diclofenac, ibuprofen, naproxen, salbutamol, sulfamethoxazole and trimethoprim) and one major metabolite (2-hydroxy-ibuprofen), present in significant amount in impacted waterways have been selected for the development and validation of the method. First, all drugs were extracted using cation exchange solid phase extraction (SPE) and eluted with two solvent mixtures. Then, the extracts were analyzed using a reverse-phase analytical column Waters® CORTECS C18+ (150×2.1mm, 2.7μm) within 14min. MS/MS was performed with an electrospray (ESI) interface in positive ion mode, with multiple reaction monitoring (MRM) experiment acquiring two product ions per drugs. Quantification has been made with standard curves for each analyte using isotopically labeled internal standards. This method has high sensitivity with limits of quantification of 1ngmL−1 for each drug, except for ibuprofen and its metabolite 2-hydroxy-ibuprofen at 2ngmL−1. The precision of the method was below 11%, the accuracy between 94 and 105% and overall recovery between 94 and 111% for all drugs, with high selectivity. Application of the method to plasma samples from wild northern pike inhabiting the St. Lawrence River collected over a three-year period showed the presence of naproxen, diclofenac, trimethoprim and salbutamol at very low concentrations (around 1ngmL−1).

Publication date: 3 November 2017
Source:Journal of Chromatography A, Volume 1522

Author(s): S. Poirier Larabie, M. Houde, C. Gagnon

Aquatic systems near major urban centers are constantly contaminated with effluent from wastewater treatment plants. Pharmaceuticals are part of the contamination and several classes of drugs have been detected in surface waters in the last decade. To better understand the impact of those pharmaceuticals in ecosystems, the exposure to aquatic species needs to be investigated. This study presents a new simple and rugged quantitative method for the determination of several classes of drugs using 100μL of plasma from fish environmentally exposed to a major but highly diluted urban effluent. Six common drugs (i.e., diclofenac, ibuprofen, naproxen, salbutamol, sulfamethoxazole and trimethoprim) and one major metabolite (2-hydroxy-ibuprofen), present in significant amount in impacted waterways have been selected for the development and validation of the method. First, all drugs were extracted using cation exchange solid phase extraction (SPE) and eluted with two solvent mixtures. Then, the extracts were analyzed using a reverse-phase analytical column Waters® CORTECS C18+ (150×2.1mm, 2.7μm) within 14min. MS/MS was performed with an electrospray (ESI) interface in positive ion mode, with multiple reaction monitoring (MRM) experiment acquiring two product ions per drugs. Quantification has been made with standard curves for each analyte using isotopically labeled internal standards. This method has high sensitivity with limits of quantification of 1ngmL−1 for each drug, except for ibuprofen and its metabolite 2-hydroxy-ibuprofen at 2ngmL−1. The precision of the method was below 11%, the accuracy between 94 and 105% and overall recovery between 94 and 111% for all drugs, with high selectivity. Application of the method to plasma samples from wild northern pike inhabiting the St. Lawrence River collected over a three-year period showed the presence of naproxen, diclofenac, trimethoprim and salbutamol at very low concentrations (around 1ngmL−1).





Tantala-based sol-gel coating for capillary microextraction on-line coupled to high-performance liquid chromatography

Publication date: 3 November 2017
Source:Journal of Chromatography A, Volume 1522
Author(s): MinhPhuong Tran, Erica B. Turner, Scott S. Segro, Li Fang, Emre Seyyal, Abdul Malik
A sol-gel organic-inorganic hybrid sorbent, consisting of chemically integrated tantalum (V) ethoxide (TaEO) and polypropylene glycol methacrylate (PPGM), was developed for capillary microextraction (CME). The sol-gel sorbent was synthesized within a fused silica capillary through hydrolytic polycondensation of TaEO and chemical incorporation of PPGM into the evolving sol-gel tantala network. A part of the organic-inorganic hybrid sol-gel network evolving in the vicinity of the capillary walls had favorable conditions to get chemically bonded to the silanol groups on the capillary surface forming a surface-bonded coating. The newly developed sol-gel sorbent was employed to isolate and enrich a variety of analytes from aqueous samples for on-line analysis by high-performance liquid chromatography (HPLC) equipped with a UV detector. CME was performed on aqueous samples containing trace concentrations of analytes representing polycyclic aromatic hydrocarbons, ketones, alcohols, amines, nucleosides, and nucleotides. This sol-gel hybrid coating provided efficient extraction with CME-HPLC detection limits ranging from 4.41pM to 28.19 pM. Due to direct chemical bonding between the sol-gel sorbent coating and the fused silica capillary inner surface, this sol-gel sorbent exhibited enhanced solvent stability. The sol-gel tantala-based sorbent also exhibited excellent pH stability over a wide pH range (pH 0–pH 14). Furthermore, it displayed great performance reproducibility in CME-HPLC providing run-to-run HPLC peak area relative standard deviation (RSD) values between 0.23% and 3.83%. The capillary-to-capillary RSD (n=3), characterizing capillary preparation method reproducibility, ranged from 0.24% to 4.11%. The results show great performance consistency and application potential for the sol-gel tantala-PPGM sorbent in various fields including biomedical, pharmaceutical, and environmental areas.

Publication date: 3 November 2017
Source:Journal of Chromatography A, Volume 1522

Author(s): MinhPhuong Tran, Erica B. Turner, Scott S. Segro, Li Fang, Emre Seyyal, Abdul Malik

A sol-gel organic-inorganic hybrid sorbent, consisting of chemically integrated tantalum (V) ethoxide (TaEO) and polypropylene glycol methacrylate (PPGM), was developed for capillary microextraction (CME). The sol-gel sorbent was synthesized within a fused silica capillary through hydrolytic polycondensation of TaEO and chemical incorporation of PPGM into the evolving sol-gel tantala network. A part of the organic-inorganic hybrid sol-gel network evolving in the vicinity of the capillary walls had favorable conditions to get chemically bonded to the silanol groups on the capillary surface forming a surface-bonded coating. The newly developed sol-gel sorbent was employed to isolate and enrich a variety of analytes from aqueous samples for on-line analysis by high-performance liquid chromatography (HPLC) equipped with a UV detector. CME was performed on aqueous samples containing trace concentrations of analytes representing polycyclic aromatic hydrocarbons, ketones, alcohols, amines, nucleosides, and nucleotides. This sol-gel hybrid coating provided efficient extraction with CME-HPLC detection limits ranging from 4.41pM to 28.19 pM. Due to direct chemical bonding between the sol-gel sorbent coating and the fused silica capillary inner surface, this sol-gel sorbent exhibited enhanced solvent stability. The sol-gel tantala-based sorbent also exhibited excellent pH stability over a wide pH range (pH 0–pH 14). Furthermore, it displayed great performance reproducibility in CME-HPLC providing run-to-run HPLC peak area relative standard deviation (RSD) values between 0.23% and 3.83%. The capillary-to-capillary RSD (n=3), characterizing capillary preparation method reproducibility, ranged from 0.24% to 4.11%. The results show great performance consistency and application potential for the sol-gel tantala-PPGM sorbent in various fields including biomedical, pharmaceutical, and environmental areas.





One-step preparation of zirconia coated silica microspheres and modification with d-fructose 1, 6-bisphosphate as stationary phase for hydrophilic interaction chromatography

Publication date: 3 November 2017 Source:Journal of Chromatography A, Volume 1522 Author(s): Zhihua Song, Chunfeng Duan, Meng Shi, Shenghong Li, Yafeng Guan In this study, ZrO2 layer coated silica microspheres (ZrO2/SiO2) wer…

Publication date: 3 November 2017
Source:Journal of Chromatography A, Volume 1522

Author(s): Zhihua Song, Chunfeng Duan, Meng Shi, Shenghong Li, Yafeng Guan

In this study, ZrO2 layer coated silica microspheres (ZrO2/SiO2) were successfully prepared by a facile one-step surfactant-free hydrothermal route under low pH condition. The synthesized ZrO2/SiO2 material was then modified with d-fructose 1, 6-bisphosphate (FDP) to improve the chromatographic separation property of the material. Fused-silica capillary columns were prepared with the modified material for evaluation. Phenolic, nucleobases and alkaloids compounds in hydrophilic interaction chromatographic (HILIC) mode showed symmetrical peaks. The FDP-ZrO2/SiO2 stationary phase showed better performance than ZrO2/SiO2 packing material and demonstrated great potential for application in HILIC mode.





Chemical composition separation of a propylene–ethylene random copolymer by high temperature solvent gradient interaction chromatography

Publication date: 3 November 2017
Source:Journal of Chromatography A, Volume 1522
Author(s): Yonggang Liu, Mohau Justice Phiri, Anthony Ndiripo, Harald Pasch
A propylene–ethylene random copolymer was fractionated by preparative temperature rising elution fractionation (TREF). The structural heterogeneity of the bulk sample and its TREF fractions was studied by high temperature liquid chromatography with a solvent gradient elution from 1-decanol to 1,2,4-trichlorobenzene. HPLC alone cannot resolve those propylene-ethylene copolymers with high ethylene content in the bulk sample, due to their low weight fractions in the bulk sample and a small response factor of these components in the ELSD detector, as well as their broad chemical composition distribution. These components can only be detected after being separated and enriched by TREF followed by HPLC analysis. Chemical composition separations were achieved for TREF fractions with average ethylene contents between 2.1 and 22.0mol%, showing that copolymers with higher ethylene contents were adsorbed stronger in the Hypercarb column and eluted later. All TREF fractions, except the 40°C fraction, were relatively homogeneous in both molar mass and chemical composition. The 40°C fraction was rather broad in both molar mass and chemical composition distributions. 2D HPLC showed that the molar masses of the components containing more ethylene units were getting lower for the 40°C fraction. HPLC revealed and confirmed that co-crystallization influences the separation in TREF of the studied propylene-ethylene copolymer.

Publication date: 3 November 2017
Source:Journal of Chromatography A, Volume 1522

Author(s): Yonggang Liu, Mohau Justice Phiri, Anthony Ndiripo, Harald Pasch

A propylene–ethylene random copolymer was fractionated by preparative temperature rising elution fractionation (TREF). The structural heterogeneity of the bulk sample and its TREF fractions was studied by high temperature liquid chromatography with a solvent gradient elution from 1-decanol to 1,2,4-trichlorobenzene. HPLC alone cannot resolve those propylene-ethylene copolymers with high ethylene content in the bulk sample, due to their low weight fractions in the bulk sample and a small response factor of these components in the ELSD detector, as well as their broad chemical composition distribution. These components can only be detected after being separated and enriched by TREF followed by HPLC analysis. Chemical composition separations were achieved for TREF fractions with average ethylene contents between 2.1 and 22.0mol%, showing that copolymers with higher ethylene contents were adsorbed stronger in the Hypercarb column and eluted later. All TREF fractions, except the 40°C fraction, were relatively homogeneous in both molar mass and chemical composition. The 40°C fraction was rather broad in both molar mass and chemical composition distributions. 2D HPLC showed that the molar masses of the components containing more ethylene units were getting lower for the 40°C fraction. HPLC revealed and confirmed that co-crystallization influences the separation in TREF of the studied propylene-ethylene copolymer.





Silk fiber for in-tube solid-phase microextraction to detect aldehydes by chemical derivatization

Publication date: 3 November 2017
Source:Journal of Chromatography A, Volume 1522
Author(s): Xiuqin Wang, Lei Pan, Juanjuan Feng, Yu Tian, Chuannan Luo, Min Sun
Aldehydes are the potentially damaging pollutants in the environment, but it is difficult to be determined due to the low concentration level. Therefore, to accurate analysis of aldehydes, it is important for efficient sample preparation with selective enrichment and rapid separation. Environmentally friendly silk fiber as adsorbent material was directly applied to develop in-tube solid-phase microextraction for analyzing aqueous samples combined with high performance liquid chromatography. 2,4-Dinitrophenylhydrazine as a derivative reagent was used for chemical derivatization of aldehydes before extraction. Under optimum conditions, an online analysis method was built with the limits of detection in the range of 0.005–0.01μgL−1 and the linearity in the range of 0.03–10μgL−1. Three aldehydes were determined in two real samples, and the relative recoveries were in the range of 95–102%.

Publication date: 3 November 2017
Source:Journal of Chromatography A, Volume 1522

Author(s): Xiuqin Wang, Lei Pan, Juanjuan Feng, Yu Tian, Chuannan Luo, Min Sun

Aldehydes are the potentially damaging pollutants in the environment, but it is difficult to be determined due to the low concentration level. Therefore, to accurate analysis of aldehydes, it is important for efficient sample preparation with selective enrichment and rapid separation. Environmentally friendly silk fiber as adsorbent material was directly applied to develop in-tube solid-phase microextraction for analyzing aqueous samples combined with high performance liquid chromatography. 2,4-Dinitrophenylhydrazine as a derivative reagent was used for chemical derivatization of aldehydes before extraction. Under optimum conditions, an online analysis method was built with the limits of detection in the range of 0.005–0.01μgL−1 and the linearity in the range of 0.03–10μgL−1. Three aldehydes were determined in two real samples, and the relative recoveries were in the range of 95–102%.





Polymeric ionic liquid based on magnetic materials fabricated through layer-by-layer assembly as adsorbents for extraction of pesticides

Publication date: 3 November 2017
Source:Journal of Chromatography A, Volume 1522
Author(s): Lijun He, Wenhang Cui, Yali Wang, Wenjie Zhao, Guoqiang Xiang, Xiuming Jiang, Pu Mao, Juan He, Shusheng Zhang
In this study, layer-by-layer assembly of polyelectrolyte multilayer films on magnetic silica provided a convenient and controllable way to prepare polymeric ionic liquid-based magnetic adsorbents. The resulting particles were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, transmission electron microscopy, and magnetic measurements. The data showed that the magnetic particles had more homogeneous spherical shapes with higher saturation magnetization when compared to those obtained by free radical polymerization method. This facilitated the convenient collection of magnetic particles, with higher extraction repeatability. The extraction performance of the multilayer polymeric ionic liquid-based adsorbents was evaluated by magnetic solid-phase extraction of four pesticides including quinalphos, fenthion, phoxim, and chlorpropham. The data suggested that the extraction efficiency depended on the number of layers in the film. The parameters affecting the extraction efficiency were optimized, and good linearity ranging from 2 to 250μgL−1 was obtained with correlation coefficients of 0.9994–0.9998. Moreover, the proposed method presented low limit of detection (0.5μgL−1, S/N=3) and limit of quantification (1.5μgL−1, S/N=10), and good repeatability expressed by the relative standard deviation (2.0%–4.6%, n=5). The extraction recoveries of four pesticides were found to range from 58.9% to 85.8%. The reliability of the proposed method was demonstrated by analyzing environmental water samples, and the results revealed satisfactory spiked recovery, relative standard deviation, and selectivity.

Publication date: 3 November 2017
Source:Journal of Chromatography A, Volume 1522

Author(s): Lijun He, Wenhang Cui, Yali Wang, Wenjie Zhao, Guoqiang Xiang, Xiuming Jiang, Pu Mao, Juan He, Shusheng Zhang

In this study, layer-by-layer assembly of polyelectrolyte multilayer films on magnetic silica provided a convenient and controllable way to prepare polymeric ionic liquid-based magnetic adsorbents. The resulting particles were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, transmission electron microscopy, and magnetic measurements. The data showed that the magnetic particles had more homogeneous spherical shapes with higher saturation magnetization when compared to those obtained by free radical polymerization method. This facilitated the convenient collection of magnetic particles, with higher extraction repeatability. The extraction performance of the multilayer polymeric ionic liquid-based adsorbents was evaluated by magnetic solid-phase extraction of four pesticides including quinalphos, fenthion, phoxim, and chlorpropham. The data suggested that the extraction efficiency depended on the number of layers in the film. The parameters affecting the extraction efficiency were optimized, and good linearity ranging from 2 to 250μgL−1 was obtained with correlation coefficients of 0.9994–0.9998. Moreover, the proposed method presented low limit of detection (0.5μgL−1, S/N=3) and limit of quantification (1.5μgL−1, S/N=10), and good repeatability expressed by the relative standard deviation (2.0%–4.6%, n=5). The extraction recoveries of four pesticides were found to range from 58.9% to 85.8%. The reliability of the proposed method was demonstrated by analyzing environmental water samples, and the results revealed satisfactory spiked recovery, relative standard deviation, and selectivity.





Graphene-functionalized melamine sponges for microextraction of sulfonamides from food and environmental samples

Publication date: 3 November 2017
Source:Journal of Chromatography A, Volume 1522
Author(s): Theodoros Chatzimitakos, Victoria Samanidou, Constantine D. Stalikas
The study describes the functionalization of melamine sponges with graphene and its use as an adsorbent for the microextraction of sulfonamides from food and environmental samples. The graphene-functionalized melamine sponge (GMeS) was prepared by an easy, one-step procedure, which complies with the principles of green chemistry and is proved advantageous over previously described methods. The applicability of the GMeS in extraction procedures was studied and an analytical method for the determination of sulfonamides in milk, eggs and lake water was developed and validated according to SANCO/12571/2013 guideline. The developed method was highly accurate and reproducible, while the limits of quantification were found to be relatively low (0.31–0.91μgkg−1, 0.96–1.32μgkg−1 and 0.10–0.29μgL−1 in the case of milk, eggs and lake water respectively). Furthermore, matrix effects were absent in all cases, since the microextraction procedure serves also as a clean-up step. The low cost of synthesis, the environmentally friendly conditions, the efficiency and high extraction recoveries are some additional advantages of the proposed procedure. To the best of our knowledge, this is the first time that a GMeS is prepared in a straightforward way and used for analytical purposes.

Publication date: 3 November 2017
Source:Journal of Chromatography A, Volume 1522

Author(s): Theodoros Chatzimitakos, Victoria Samanidou, Constantine D. Stalikas

The study describes the functionalization of melamine sponges with graphene and its use as an adsorbent for the microextraction of sulfonamides from food and environmental samples. The graphene-functionalized melamine sponge (GMeS) was prepared by an easy, one-step procedure, which complies with the principles of green chemistry and is proved advantageous over previously described methods. The applicability of the GMeS in extraction procedures was studied and an analytical method for the determination of sulfonamides in milk, eggs and lake water was developed and validated according to SANCO/12571/2013 guideline. The developed method was highly accurate and reproducible, while the limits of quantification were found to be relatively low (0.31–0.91μgkg−1, 0.96–1.32μgkg−1 and 0.10–0.29μgL−1 in the case of milk, eggs and lake water respectively). Furthermore, matrix effects were absent in all cases, since the microextraction procedure serves also as a clean-up step. The low cost of synthesis, the environmentally friendly conditions, the efficiency and high extraction recoveries are some additional advantages of the proposed procedure. To the best of our knowledge, this is the first time that a GMeS is prepared in a straightforward way and used for analytical purposes.





Corrigendum to “Improved separation and analysis of glycolipids by Iatroscan thin-layer chromatography–flame ionization detection” [J. Chromatogr. A 1409 (2015) 259–267]

Publication date: 27 October 2017
Source:Journal of Chromatography A, Volume 1521
Author(s): Blaženka Gašparović, Snježana P. Kazazić, Ana Cvitešić, Abra Penezić, Sanja Frka

Publication date: 27 October 2017
Source:Journal of Chromatography A, Volume 1521

Author(s): Blaženka Gašparović, Snježana P. Kazazić, Ana Cvitešić, Abra Penezić, Sanja Frka







Corrigendum to “Comprehensive determination of macrolide antibiotics, their synthesis intermediates and transformation products in wastewater effluents and ambient waters by liquid chromatography–tandem mass spectrometry” [J. Chromatogr. A 1509 (2017) 60–68]

Publication date: 27 October 2017 Source:Journal of Chromatography A, Volume 1521 Author(s): Ivan Senta, Ivona Krizman-Matasic, Senka Terzic, Marijan Ahel

Publication date: 27 October 2017
Source:Journal of Chromatography A, Volume 1521

Author(s): Ivan Senta, Ivona Krizman-Matasic, Senka Terzic, Marijan Ahel







Gas chromatographic-mass spectrometric determination of glycosides without prior hydrolysis

Publication date: 27 October 2017
Source:Journal of Chromatography A, Volume 1521
Author(s): Valery A. Isidorov, Jolanta Nazaruk
The article presents for the first time the linear temperature programmed retention indices on a column with stationary phases of 5% phenylpolydimethyl silicone and the mass spectra of trimethylsilyl (TMS) derivatives of 71 glycosides (both commercial preparations and compounds extracted from plant tissues) which were not characterized earlier by these parameters. Converted to their TMS derivatives, the glycosides were thermally stable: they exhibited single peaks on their chromatograms without products of thermal decomposition. Therefore this work demonstrates the suitability of high resolution–high temperature gas chromatography (HR-HT/GC) to analyse different groups of glycosides including compounds with disaccharide moieties without the necessity of their hydrolyses. Since a limited number of commercial and plant-isolated glycosides were available, an attempt was made to assess their retention indices using the known “structure–retention relationships” approach. It was demonstrated that the retention indices of silanised glycosides and their aglycones were characterized by a linear dependence.

Publication date: 27 October 2017
Source:Journal of Chromatography A, Volume 1521

Author(s): Valery A. Isidorov, Jolanta Nazaruk

The article presents for the first time the linear temperature programmed retention indices on a column with stationary phases of 5% phenylpolydimethyl silicone and the mass spectra of trimethylsilyl (TMS) derivatives of 71 glycosides (both commercial preparations and compounds extracted from plant tissues) which were not characterized earlier by these parameters. Converted to their TMS derivatives, the glycosides were thermally stable: they exhibited single peaks on their chromatograms without products of thermal decomposition. Therefore this work demonstrates the suitability of high resolution–high temperature gas chromatography (HR-HT/GC) to analyse different groups of glycosides including compounds with disaccharide moieties without the necessity of their hydrolyses. Since a limited number of commercial and plant-isolated glycosides were available, an attempt was made to assess their retention indices using the known “structure–retention relationships” approach. It was demonstrated that the retention indices of silanised glycosides and their aglycones were characterized by a linear dependence.





Development and comparison of chromatographic methods for the analysis of long chain diols and alkenones in biological materials and sediment

Publication date: 27 October 2017
Source:Journal of Chromatography A, Volume 1521
Author(s): Marijke W. de Bar, Ellen C. Hopmans, Monique Verweij, Denise J.C. Dorhout, Jaap S. Sinninghe Damsté, Stefan Schouten
We have compared and assessed the suitability of several chromatographic methods for the analysis of long chain alkenones and long chain diols and the associated paleotemperature proxies (UK’37 and LDI). We evaluated the traditional methods for the analysis of the UK’37 and the LDI, gas chromatography (GC) − flame ionization detection (FID) and GC mass spectrometry (MS) using selected ion monitoring (SIM), respectively, and developed a new method using GC–MS/MS in multiple reaction monitoring mode (MRM) for the analysis of long chain diols as well as a method for automatic silylation of diols using a robot autosampler. Finally, we evaluated liquid chromatography (LC) methods to simultaneously measure the UK’37 and the LDI, using ultra high performance LC (UHPLC) with low (nominal mass) resolution MS in SIM mode, and UHPLC with high resolution MS (HRMS). Detection and quantification limits and reproducibility were assessed by means of serial dilutions of culture extracts.Automated silylation by a robot autosampler showed similar reproducibility as off-line silylation while substantially decreasing sample preparation time. The novel MRM method had a slightly lower limit of quantification (LOQ; i.e. 0.3pgC28 1,13-diol injected on-column) than the traditional method (0.5pg) and improved reproducibility while allowing more unambiguous identification of LCDs in complex matrices. For diols, UHPLC–MS using SIM had the highest LOQ (i.e. 15pg) and a comparable reproducibility as GC–MS. UHPLC–HRMS had a LOQ of ca. 1.5pg, and an improved reproducibility for diol analysis. For alkenone analysis, both UHPLC–HRMS and UHPLC–MS using SIM were 2–3 orders of magnitude more sensitive (LOQ ca. 20 and 2pgC37:2 alkenone injected on-column, respectively) than GC-FID (LOD ca. 3ng), with a similar reproducibility of the UK’37 index. Hence, UHPLC–HRMS allows simultaneous analysis of the UK’37 and LDI at an increased sensitivity. In addition, it allows simultaneous measurement of TEX86, a temperature proxy based on the isoprenoid glycerol dialkyl glycerol tetraethers. This reduces the preparation time by excluding the need of derivatization and separation of the ketone (containing the long chain alkenones) and polar fractions (containing the long chain diols and GDGTs). However, synthetic standards are required to fully assess the accuracy of the new methods for determination of the LDI and UK’37.

Publication date: 27 October 2017
Source:Journal of Chromatography A, Volume 1521

Author(s): Marijke W. de Bar, Ellen C. Hopmans, Monique Verweij, Denise J.C. Dorhout, Jaap S. Sinninghe Damsté, Stefan Schouten

We have compared and assessed the suitability of several chromatographic methods for the analysis of long chain alkenones and long chain diols and the associated paleotemperature proxies (UK’ 37 and LDI). We evaluated the traditional methods for the analysis of the UK’ 37 and the LDI, gas chromatography (GC) − flame ionization detection (FID) and GC mass spectrometry (MS) using selected ion monitoring (SIM), respectively, and developed a new method using GC–MS/MS in multiple reaction monitoring mode (MRM) for the analysis of long chain diols as well as a method for automatic silylation of diols using a robot autosampler. Finally, we evaluated liquid chromatography (LC) methods to simultaneously measure the UK’ 37 and the LDI, using ultra high performance LC (UHPLC) with low (nominal mass) resolution MS in SIM mode, and UHPLC with high resolution MS (HRMS). Detection and quantification limits and reproducibility were assessed by means of serial dilutions of culture extracts. Automated silylation by a robot autosampler showed similar reproducibility as off-line silylation while substantially decreasing sample preparation time. The novel MRM method had a slightly lower limit of quantification (LOQ; i.e. 0.3pgC28 1,13-diol injected on-column) than the traditional method (0.5pg) and improved reproducibility while allowing more unambiguous identification of LCDs in complex matrices. For diols, UHPLC–MS using SIM had the highest LOQ (i.e. 15pg) and a comparable reproducibility as GC–MS. UHPLC–HRMS had a LOQ of ca. 1.5pg, and an improved reproducibility for diol analysis. For alkenone analysis, both UHPLC–HRMS and UHPLC–MS using SIM were 2–3 orders of magnitude more sensitive (LOQ ca. 20 and 2pgC37:2 alkenone injected on-column, respectively) than GC-FID (LOD ca. 3ng), with a similar reproducibility of the UK’ 37 index. Hence, UHPLC–HRMS allows simultaneous analysis of the UK’ 37 and LDI at an increased sensitivity. In addition, it allows simultaneous measurement of TEX86, a temperature proxy based on the isoprenoid glycerol dialkyl glycerol tetraethers. This reduces the preparation time by excluding the need of derivatization and separation of the ketone (containing the long chain alkenones) and polar fractions (containing the long chain diols and GDGTs). However, synthetic standards are required to fully assess the accuracy of the new methods for determination of the LDI and UK’ 37.





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

Publication date: 27 October 2017
Source:Journal of Chromatography A, Volume 1521
Author(s): Maurus Biedermann, Celine Munoz, Koni Grob
On-line coupled high performance liquid chromatography-gas chromatography-flame ionization detection (HPLC-GC-FID) is the most widely used method for the analysis of mineral oil hydrocarbons in food, food contact materials, tissues and cosmetics. With comprehensive two-dimensional gas chromatography (GCxGC), a tool became available for better establishing the elution sequence of the various types of hydrocarbons from the HPLC column used for isolating the mineral oil saturated hydrocarbons (MOSH) and mineral oil aromatic hydrocarbons (MOAH). The performance of a heavily used HPLC column with reduced retention for MOAH was investigated to improve the robustness of the method. Updates are recommended that render the MOSH/MOAH separation less dependent of the state of the HPLC column and more correct in cases of highly refined mineral oil products of high molecular mass. Cyclohexyl cyclohexane (Cycy), used as internal standard, turned out to be eluted slightly after cholestane (Cho); apparently the size exclusion effect predominates the extra retention by ring number on the 60Å pore size silica gel. Hence, Cycy can be used to determine the end of the MOSH fraction. Long chain alkyl benzenes were eluted earlier than tri-tert. butyl benzene (Tbb). It is proposed to start the MOAH transfer immediately after the MOSH fraction and use a gradient causing breakthrough of dichloromethane (visible in the UV chromatogram) at a time suitable to elute perylene (Per) at the end of the fraction. In this way, a decrease in retention power of the HPLC column can be tolerated without adjustment of the MOAH fraction until some MOAH start being eluted into the MOSH fraction. This critical point can be checked either with di(2-ethylhexyl) benzene (DEHB) as a marker or the HPLC-UV chromatogram. Finally, based on new findings in rats and human tissues, it is recommended to integrate the MOSH and MOAH up to the retention time of the n-alkane C40.

Publication date: 27 October 2017
Source:Journal of Chromatography A, Volume 1521

Author(s): Maurus Biedermann, Celine Munoz, Koni Grob

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





Development and validation of a high-throughput method for determination of nine fluoroquinolones residues in muscle of different animal species by liquid chromatography coupled to tandem mass spectrometry with low temperature clean up

Publication date: 27 October 2017
Source:Journal of Chromatography A, Volume 1521
Author(s): Fabiano Barreto, Cristina B.D. Ribeiro, Rodrigo Barcellos Hoff, Teresa Dalla Costa
This work describes the development and validation of a quantitative and confirmatory method to determination of nine fluoroquinolones residues in poultry, bovine, swine and fish muscle using LC–MS/MS. Sample preparation was based in a fast solvent extraction with acetonitrile with 1% of formic acid followed by a low-temperature clean up procedure and centrifugation, without further steps. The recoveries ranged between 79% and 115%. The concentration work range was 0–200μgkg−1. The LOD and LOQ were 5 and 10μgkg−1, respectively. This high-throughput method was reliable for identification and confirmation of nine relevant compounds in food-producing animal tissues. Validation procedure was performed according the Directive 2002/657/EC criteria and the method showed fitness to purpose in terms of precision and reproducibility as well as for the other performance parameters.

Publication date: 27 October 2017
Source:Journal of Chromatography A, Volume 1521

Author(s): Fabiano Barreto, Cristina B.D. Ribeiro, Rodrigo Barcellos Hoff, Teresa Dalla Costa

This work describes the development and validation of a quantitative and confirmatory method to determination of nine fluoroquinolones residues in poultry, bovine, swine and fish muscle using LC–MS/MS. Sample preparation was based in a fast solvent extraction with acetonitrile with 1% of formic acid followed by a low-temperature clean up procedure and centrifugation, without further steps. The recoveries ranged between 79% and 115%. The concentration work range was 0–200μgkg−1. The LOD and LOQ were 5 and 10μgkg−1, respectively. This high-throughput method was reliable for identification and confirmation of nine relevant compounds in food-producing animal tissues. Validation procedure was performed according the Directive 2002/657/EC criteria and the method showed fitness to purpose in terms of precision and reproducibility as well as for the other performance parameters.





An easy and fast adenosine 5′-diphosphate quantification procedure based on hydrophilic interaction liquid chromatography-high resolution tandem mass spectrometry for determination of the in vitro adenosine 5′-triphosphatase activity of the human breast cancer resistance protein ABCG2

Publication date: 27 October 2017
Source:Journal of Chromatography A, Volume 1521
Author(s): Lea Wagmann, Hans H. Maurer, Markus R. Meyer
Interactions with the human breast cancer resistance protein (hBCRP) significantly influence the pharmacokinetic properties of a drug and can even lead to drug-drug interactions. As efflux pump from the ABC superfamily, hBCRP utilized energy gained by adenosine 5′-triphosphate (ATP) hydrolysis for the transmembrane movement of its substrates, while adenosine 5′-diphosphate (ADP) and inorganic phosphate were released. The ADP liberation can be used to detect interactions with the hBCRP ATPase. An ADP quantification method based on hydrophilic interaction liquid chromatography (HILIC) coupled to high resolution tandem mass spectrometry (HR-MS/MS) was developed and successfully validated in accordance to the criteria of the guideline on bioanalytical method validation by the European Medicines Agency. ATP and adenosine 5′-monophosphate were qualitatively included to prevent interferences. Furthermore, a setup consisting of six sample sets was evolved that allowed detection of hBCRP substrate or inhibitor properties of the test compound. The hBCRP substrate sulfasalazine and the hBCRP inhibitor orthovanadate were used as controls. To prove the applicability of the procedure, the effect of amprenavir, indinavir, nelfinavir, ritonavir, and saquinavir on the hBCRP ATPase activity was tested. Nelfinavir, ritonavir, and saquinavir were identified as hBCRP ATPase inhibitors and none of the five HIV protease inhibitors turned out to be an hBCRP substrate. These findings were in line with a pervious publication.

Publication date: 27 October 2017
Source:Journal of Chromatography A, Volume 1521

Author(s): Lea Wagmann, Hans H. Maurer, Markus R. Meyer

Interactions with the human breast cancer resistance protein (hBCRP) significantly influence the pharmacokinetic properties of a drug and can even lead to drug-drug interactions. As efflux pump from the ABC superfamily, hBCRP utilized energy gained by adenosine 5′-triphosphate (ATP) hydrolysis for the transmembrane movement of its substrates, while adenosine 5′-diphosphate (ADP) and inorganic phosphate were released. The ADP liberation can be used to detect interactions with the hBCRP ATPase. An ADP quantification method based on hydrophilic interaction liquid chromatography (HILIC) coupled to high resolution tandem mass spectrometry (HR-MS/MS) was developed and successfully validated in accordance to the criteria of the guideline on bioanalytical method validation by the European Medicines Agency. ATP and adenosine 5′-monophosphate were qualitatively included to prevent interferences. Furthermore, a setup consisting of six sample sets was evolved that allowed detection of hBCRP substrate or inhibitor properties of the test compound. The hBCRP substrate sulfasalazine and the hBCRP inhibitor orthovanadate were used as controls. To prove the applicability of the procedure, the effect of amprenavir, indinavir, nelfinavir, ritonavir, and saquinavir on the hBCRP ATPase activity was tested. Nelfinavir, ritonavir, and saquinavir were identified as hBCRP ATPase inhibitors and none of the five HIV protease inhibitors turned out to be an hBCRP substrate. These findings were in line with a pervious publication.





Identification and characterization of curcuminoids in turmeric using ultra-high performance liquid chromatography-quadrupole time of flight tandem mass spectrometry

Publication date: 27 October 2017 Source:Journal of Chromatography A, Volume 1521 Author(s): Shuailong Jia, Zhifeng Du, Chengwu Song, Shuna Jin, Yang Zhang, Yulin Feng, Chaomei Xiong, Hongliang Jiang A three-step strate…

Publication date: 27 October 2017
Source:Journal of Chromatography A, Volume 1521

Author(s): Shuailong Jia, Zhifeng Du, Chengwu Song, Shuna Jin, Yang Zhang, Yulin Feng, Chaomei Xiong, Hongliang Jiang

A three-step strategy was developed for systematic characterization of curcuminoids in turmeric. Based on UHPLC-QTOF-MS/MS analysis, 89 curcuminoids including 16 novel ones were identified in the turmeric samples using this approach. During the identification process, false positive results were excluded by combining the positive and negative ESI-MS/MS analyses. Moreover, the characterization of the keto and enol forms of type A, B and C curcuminoids was first discussed and they were clearly distinguished using negative ESI-MS/MS method with UV spectra analyses. The structures of detected curcuminoids were identified and rationalized in both ion modes. Additionally, the fragmentation behaviors of the 15 types of curcuminoids were clearly illustrated in this work, which will be helpful for detection and identification of corresponding trace curcuminoids in complex turmeric samples using UHPLC-QTOF-MS/MS methods.