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Ping Zhang - One of the best experts on this subject based on the ideXlab platform.
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Chiral Separation and Determination of Etoxazole Enantiomers in Vegetables by Normal-Phase and Reverse-Phase High Performance Liquid Chromatography.
Molecules (Basel Switzerland), 2020Co-Authors: Ping Zhang, Sheng Wang, Dongmei Shi, Furong Yang, Jianhao WangAbstract:The chiral separation of etoxazole enantiomers on Lux Cellulose-1, Lux Cellulose-3, Chiralpak IC, and Chiralpak AD chiral columns was carefully investigated by normal-phase high performance liquid chromatography and reverse-phase high performance liquid chromatography (HPLC). Hexane/isopropanol, hexane/n-butanol, methanol/water, and acetonitrile/water were used as mobile phase at a flow rate of 0.8 mL/min. The effects of chiral stationary phase, mobile phase component, mobile phase ratio, and temperature on etoxazole separation were also studied. Etoxazole enantiomers were baseline separated on Lux Cellulose-1, Chiralpak IC, and Chiralpak AD chiral columns, and partially separated on Lux Cellulose-3 chiral column under normal-phase HPLC. However, the complete separation on Lux Cellulose-1, Chiralpak IC, and partial separation on Chiralpak AD were obtained under reverse-phase HPLC. Normal-phase HPLC presented better resolution for etoxazole enantiomers than reverse-phase HPLC. Thermodynamic parameters, including ΔH and ΔS, were also calculated based on column temperature changes from 10 °C to 40 °C, and the maximum resolutions (Rs) were not always acquired at the lowest temperature. Furthermore, the optimized method was successfully applied to determine etoxazole enantiomers in cucumber, cabbage, tomato, and soil. The results of chiral separation efficiency of etoxazole enantiomers under normal-phase and reverse-phase HPLC were compared, and contribute to the comprehensive environmental risk assessment of etoxazole at the enantiomer level.
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Enantiomeric separation of type I and type II pyrethroid insecticides with different chiral stationary phases by reversed-phase high-performance liquid chromatography.
Chirality, 2017Co-Authors: Ping Zhang, Kun Qian, Wei XiaoAbstract:The enantiomeric separation of type I (bifenthrin, BF) and type II (lambda-cyhalothrin, LCT) pyrethroid insecticides on Lux Cellulose-1, Lux Cellulose-3, and Chiralpak IC chiral columns was investigated by reversed-phase high-performance liquid chromatography. Methanol/water or acetonitrile/water was used as mobile phase at a flow rate of 0.8 mL/min. The effects of chiral stationary phase, mobile phase composition, column temperature, and thermodynamic parameters on enantiomer separation were carefully studied. Bifenthrin got a partial separation on Lux Cellulose-1 column and baseline separation on Lux Cellulose-3 column, while LCT enantiomers could be completely separated on both Lux Cellulose-1 and Lux Cellulose-3 columns. Chiralpak IC provided no separation ability for both BF and LCT. Retention factor (k) and selectivity factor (α) decreased with the column temperature increasing from 10°C to 40°C for both BF and LCT enantiomers. Thermodynamic parameters including ∆H and ∆S were also calculated, and the maximum Rs were not always obtained at lowest temperature. Furthermore, the quantitative analysis methods for BF and LCT enantiomers in soil and water were also established. Such results provide a new approach for pyrethroid separation under reversed-phase condition and contribute to environmental risk assessment of pyrethroids at enantiomer level.
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chiral pyrethroid insecticide fenpropathrin and its metabolite enantiomeric separation and pharmacokinetic degradation in soils by reverse phase high performance liquid chromatography
Analytical Methods, 2017Co-Authors: Ping Zhang, Yuhan He, Qian Yu, Zhiqiang Zhou, Lin HeAbstract:The enantiomeric separation of fenpropathrin enantiomers on Lux Cellulose-1, Lux Cellulose-3 and Chiralpak IC chiral columns as well as enantioselective degradation of fenpropathrin in soil were investigated by reverse-phase high-performance liquid chromatography (RP-HPLC). The effects of the chiral stationary phase, mobile phase component, mobile phase ratio, temperature and thermodynamic parameters on resolution were carefully evaluated. Fenpropathrin enantiomers achieve a baseline separation (Rs = 2.30) on the Lux Cellulose-3 column with a mobile phase of methanol/water at a ratio of 85/15. Partial separations were achieved on Lux Cellulose-1 and Chiralpak IC columns with maximum Rs = 1.01 and Rs = 0.64, respectively. Enantioselective degradation of fenpropathrin enantiomers in soil was investigated based on the proposed separation method. The half-life (t1/2) of S-fenpropathrin and R-fenpropathrin was 17.8 days and 12.6 days, respectively, indicating that the degradation of fenpropathrin in soil was enantioselective, with R-fenpropathrin preferentially degraded. Furthermore, the formation and degradation of 3-PBA, the main metabolite of fenpropathrin, were also investigated in three soils. Soil microorganisms were confirmed as the main factor that is responsible for enantioselective degradation of fenpropathrin enantiomers in soil. Such results provide a new approach for fenpropathrin enantiomer separation and contribute to a comprehensive risk assessment of fenpropathrin at the enantiomer level.
Wei Xiao - One of the best experts on this subject based on the ideXlab platform.
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Enantiomeric separation of type I and type II pyrethroid insecticides with different chiral stationary phases by reversed-phase high-performance liquid chromatography.
Chirality, 2017Co-Authors: Ping Zhang, Kun Qian, Wei XiaoAbstract:The enantiomeric separation of type I (bifenthrin, BF) and type II (lambda-cyhalothrin, LCT) pyrethroid insecticides on Lux Cellulose-1, Lux Cellulose-3, and Chiralpak IC chiral columns was investigated by reversed-phase high-performance liquid chromatography. Methanol/water or acetonitrile/water was used as mobile phase at a flow rate of 0.8 mL/min. The effects of chiral stationary phase, mobile phase composition, column temperature, and thermodynamic parameters on enantiomer separation were carefully studied. Bifenthrin got a partial separation on Lux Cellulose-1 column and baseline separation on Lux Cellulose-3 column, while LCT enantiomers could be completely separated on both Lux Cellulose-1 and Lux Cellulose-3 columns. Chiralpak IC provided no separation ability for both BF and LCT. Retention factor (k) and selectivity factor (α) decreased with the column temperature increasing from 10°C to 40°C for both BF and LCT enantiomers. Thermodynamic parameters including ∆H and ∆S were also calculated, and the maximum Rs were not always obtained at lowest temperature. Furthermore, the quantitative analysis methods for BF and LCT enantiomers in soil and water were also established. Such results provide a new approach for pyrethroid separation under reversed-phase condition and contribute to environmental risk assessment of pyrethroids at enantiomer level.
Georges Guiochon - One of the best experts on this subject based on the ideXlab platform.
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Mass transfer mechanism in chiral reversed phase liquid chromatography.
Journal of chromatography. A, 2014Co-Authors: Fabrice Gritti, Georges GuiochonAbstract:Abstract The mechanism of mass transfer in chiral chromatography was investigated using an experimental protocol already applied in RPLC and HILIC chromatography. The different contributions to the reduced height equivalent to a theoretical plate (HETP) include the longitudinal diffusion HETP term, the solid–liquid mass transfer resistance HETP term, the short-range eddy dispersion HETP term, and the long-range eddy dispersion HETP term. Their accurate measurement permits the determination of the adsorption rate constant k ads of trans -stilbene enantiomers on a column packed with Lux 5 μm Cellulose-1 particles. The experimental results demonstrate that the number of adsorption–desorption steps per unit time of chiral compounds on polysaccharide-based chiral stationary phases is four orders of magnitude smaller than that of achiral compounds.
Yvan Vander Heyden - One of the best experts on this subject based on the ideXlab platform.
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Chiral separations in reversed-phase liquid chromatography: Evaluation of several polysaccharide-based chiral stationary phases for a separation strategy update
Journal of chromatography. A, 2012Co-Authors: Ahmed A. Younes, Debby Mangelings, Yvan Vander HeydenAbstract:By application of the reversed-phase generic screening conditions of a separation strategy defined in Matthijs et al. (2004) [18], the chiral discrimination abilities of six recently commercialized polysaccharide-based columns, Lux Cellulose-1, Lux Cellulose-2, Lux Cellulose-3, Lux Cellulose-4, Lux Amylose-2 and Sepapak-5, and of three classic ones, Chiralpak AD-RH, Chiralcel OD-RH and Chiralcel OJ-RH, were evaluated using a set of 58 compounds. Two mobile phases, an acidic and a basic, were sequentially applied on the columns. Using both mobile phases, a column set of Chiralcel OD-RH (or Lux Cellulose-1), Lux Cellulose-3 and Lux Amylose-2 gave the maximal number of cumulative separations, i.e. 51/58 (or 50), of which 35 (or 32) had baseline resolutions. Therefore, this set of systems was selected to update the screening step of the existing separation strategy. The selected columns were subsequently used to evaluate the applicability of the initial optimization steps, part of the existing RPLC strategy, using 66 different optimization cases. The existing optimization steps increased both the number of separations and of baseline separations by eight and by 18, respectively, relative to the screening results. Introduction of some modifications to the existing steps added eight more separations and three more baseline separations. In addition, a new optimization step for late eluting compounds was proposed and implemented. Based on these results, an updated chiral separation strategy in RPLC was defined.
Bezhan Chankvetadze - One of the best experts on this subject based on the ideXlab platform.
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Enantiomer elution order reversal of fluorenylmethoxycarbonyl-isoleucine in high-performance liquid chromatography by changing the mobile phase temperature and composition.
Journal of chromatography. A, 2011Co-Authors: Lali Chankvetadze, N. Ghibradze, Marina Karchkhadze, Liming Peng, Tivadar Farkas, Bezhan ChankvetadzeAbstract:In this paper the elution order reversal of enantiomers of fluorenylmethoxycarbonyl- or FMOC-isoleucine is described depending on the separation temperature and composition of the mobile phase when using the polysaccharide-based chiral column Lux Cellulose-1 in HPLC with normal-phase eluent. Reversal of the enantiomer elution order (EEO) in HPLC depending on the column temperature and content of the polar modifier in the mobile phase has been reported before in the literature. However, EEO reversal by changing the content of acidic modifier in the mobile phase seems to be described for the first time in the present work.