抗坏血酸及L-半胱氨酸的流动注射动力学同时测定法

STOPPED-FLOW INJECTION ANALYSIS FOR SIMULTANEOUS DETERMINATION OF ASCORBIC ACID AND L-CYSTEINE

p H 2～ 9时 ,抗坏血酸与 L-半胱氨酸均可与 Fe3+-邻菲咯啉混合液反应 ,生成 Fe2 +-邻菲咯啉有色配合物 ,但两者反应速度相差极大。根据这个原理 ,采用流动注射分析停流技术 ,建立了抗坏血酸与 L-半胱氨酸的动力学吸光光度同时测定法。两者测定的线性范围分别为 0～ 2 4 mg·L-1和 0～ 2 80 mg· L-1,相应的检出限为 1 mg· L-1和 1 6mg· L-1,抗坏血酸与 L -半胱氨酸浓度分别为 1 2 .0 mg·L-1和 1 60 .0 mg·L-1时 ,测定的相对标准偏差分别为 0 .9%和 0 .6% ,采样频率为30样·h-1。该法灵敏、快速、准确 ,选择性较高 ,且流路及设备简单 ,实用性强 ,用于实际样品测定 ,抗坏血酸及 L-半胱氨酸的加标回收率分别可达 95.2 %和 92 .8%。

A stopped flow kinetic spectrophotometric method is proposed for the simultaneous determination of ascorbic acid (VC) and L cysteine (L cys) in fruit juice. The calibration graphs are linear for 0~24, 0~280mg·L -1 and the detection limits are 1mg·L -1 and 16mg·L -1 respectively. The injectd sample volumn is 157μl and the sampling rate is 30h -1 . This method is simple, rapid, sensitive and accurate with high selectivity. It has been applied to the determination of VC and L cys in strawberry juice. Recovery found by standard addition method are 95.2% and 92.8% for VC and L cys respectively.