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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0.01mol.L-1山梨酸和0.02mol.L-1三羟甲基氨基甲烷的水溶液(pH8.1);操作电压:30kV;检测波长:225nm(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2μg.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 enrich and detect trace 2-ethylhexanoic acid in β-lactam antibiotics by capillary zone electrophoresis with indirect UV detection. Methods: Uncoated flexible quartz capillary tube was used. The background electrolyte was an aqueous solution containing 0.01 mol·L-1 sorbic acid and 0.02 mol·L-1 Tris (pH8.1). The operating voltage was 30 kV. The detection wavelength : 225nm (indirect detection). Results: 2-Ethylhexanoate migrated towards the cathode driven by a strong electroosmotic flow. The probe ion also serves as a precursor ion for the β -lactam antibiotics in the test solution as the terminal ions to construct an instantaneous isokinetic electrophoresis system in the capillary front to generate the sample self-accumulation effect and to enrich the 2-ethylhexanoate to avoid Significant broadening or deformation of the 2-ethylhexanoate zone during large volume injection. The limit of quantification for this method is 2 μg.mL-1, which corresponds to 0.01% of the amount of β-lactam antibiotics. Conclusion: This method is suitable for the high sensitivity detection of trace 2-ethylhexanoic acid in several β-lactam antibiotics.