抗坏血酸及L-半胱氨酸的流动注射动力学同时测定法

Simultaneous Determination of VC and L-cys in Fruit Juices by Stopped-Flow Kinetic Spectrophotometry

ｐＨ２～９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，但二者反应速度相差极大、根据这个原理，本研究采用流动注射分析停流技术，建立了抗坏血酸与Ｌ－半胱氨酸的动力学分光光度同时测定法．二者测定的线性范围分别为０－２４ｍｇ／Ｌ及０～２８０ｍｇ／Ｌ，相应的检测限为１ｍｇ／Ｌ及１６ｍｇ／Ｌ，抗坏血酸与Ｌ－半胱氨酸浓度分别为１２．ｍｇ／Ｌ、及１６０．０ｍｇ／Ｌ时，测定的相对标准偏差分别为０．９％及０．６％，采样频率为３０样／ｈ。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－半胱酸的加标回收率分别可达９５．２％及９２．８％

Astopped-flow kinetic spectrophotometric method is proposed for the simultaneous determination of ascorbic acid (Vc ) and L-cysteine(L-cys)in fruit juices.The calibration graphs are linear for 0-24.0-280mg/L and the detection limits are lmg/ L and 16mg/L for Vc and L-cys.respectively.The injectd sample volume is 157uL and the sampling rate is 30 samples/h.This method is simple rapid. sensitive and accurate with high selectivity and has been applied for determination of Vc and L-cys in strawberry juice.The marked recovery rates are up to 95.2%and 92.8%for Vc and L-cys respectivily.