毛细管区带电泳-间接紫外检测β-内酰胺类抗生素中的微量2-乙基己酸___

目的：用毛细管区带电泳-间接紫外检测技术在线富积并检测β-内酰胺类抗生素中的微量2-乙基己酸。方法：采用非涂层弹性石英毛细管 背景电解质为含0.01 mol•L-1山梨酸和0.02 mol•L-1三羟甲基氨基甲烷的水溶液（pH 8.1） 操作电压：30 kV 检测波长：225 nm（间接检测）。结果：在强电渗流的驱动下，2-乙基己酸根向阴极迁移。以探针离子兼作前导离子，供试品溶液中的β-内酰胺类抗生素作为终结离子，在毛细管前端构建瞬间等速电泳体系以产生样品自身堆积效应并富积2-乙基己酸根，避免了在大体积进样时2-乙基己酸根区带的显著展宽或变形。本文方法的定量限约为2 μg•mL-1，相当于β-内酰胺类抗生素量的0.01%。结论：本方法适用于对几种β-内酰胺类抗生素中微量2-乙基己酸的高灵敏度检测。

Objective:To establish a capillary zone electrophoresis with on-line preconcentration method for determination trace 2-ethylhexanoic acid in β-lactam antibiotics.Method:Best results were achieved with the background electrolyte constituting of 0.01 mol•L-1 sorbic acid and 0.02 mol•L-1 tris(hydroxymethyl)methylamine (pH 8.1) in a single bare fused-silica capillary with an operating voltage of 30 kV and indirect UV detection.Result:The strong electroosmotic flow at pH 8.1 pulled 2-ethylhexanoate against its mobility toward the cathode.The terminating-type sample self-stacking was based on transient isotachophoresis in which the probe ion served as leading ion，and native β-lactam antibiotics as the terminating ion.High sensitivity can be obtained with large volume injection,avoiding 2-ethylhexanoate zone distortion.The limit of quantitation was about 2 μg•mL-1，which equivalent to 0.01% of β-lactam antibiotics.Conclusion:The proposed method is suitable for highly sensitive detection of trace 2-ethylhexanoic acid in several kinds of β-lactam antibiotics.

1BP.2009.Vol Ⅰ.Appendix Ⅷ
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