Chinese Journal of Chromatography ›› 2018, Vol. 36 ›› Issue (1): 1-4.DOI: 10.3724/SP.J.1123.2017.10008

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Enantiomeric separation of D, L-isoleucine in citric acid-zinc (Ⅱ) medium by capillary electrophoresis

CHEN Li, ZHENG Ying, CHEN Yufu, YUAN Qiuyue, XIE Tianyao   

  1. School of Chemistry, Sun Yat-sen University, Guangzhou 510275, China
  • Received:2017-10-12 Online:2018-01-08 Published:2018-01-22
  • Supported by:

    the Fundamental Research Funds of Sun Yat-sen University (No. KJJ14066); the Innovative Experiment and Research Fund for College Students of Guangdong Province (No. G201401046).

Abstract:

The enantiomeric separation of unmodified D,L-isoleucine was achieved in citric acid-zinc(Ⅱ) medium by capillary electrophoresis (CE) with contactless conductivity detector (C4D). In the conventional chiral separation methods of amino acid, a chiral complex used as the chiral selector was added into the eluent in order to yield a chiral environment. However, in this study a non-chiral solution, i. e. 2.8 mmol/L NaOH+0.8 mmol/L citric acid+2.0 mmol/L zinc acetate was used as the running buffer, and the citric acid-zinc(Ⅱ) acted the role of a chiral selector. Under the optimum experimental conditions:uncoated fused-silica capillary (45 cm×50 μm, Leff=40 cm), separation voltage of +13 kV, electrokinetic injection of 11 kV×8 s, the enantiomers of D,L-isoleucine were baseline separated within 8 min with the resolutions (Rs) of 2.0. The calibration curve of each enantiomer showed good linearity in the range from 1.0 mg/L to 20 mg/L, with the limits of detection of 0.40 mg/L. The intra-and inter-day precisions were examined. The RSDs of peak area and migration time were found to be below 5.0% and 2.5% (n=6), respectively, indicating good repeatability (intra-day) and reproducibility (inter-day) of the method. Interference experiment was also tested. As a result, other common amino acids did not interfere with the detection. The proposed method provided a potential new way to further investigate the enantioseparation of unmodified or native amino acids.

Key words: capillary electrophoresis (CE), chiral separation, contactless conductivity detector, isoleucine enantiomers, non-chiral medium, zinc ion

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