毛细管区带电泳分离/电化学检测果汁中有机酸

SEPARATION OF ORGANIC ACIDS BY CAPILLARY ZONE ELECTROPHORESIS AND ELECTROCHEMICAL DETECTION IN FRUIT JUICES

目的：建立毛细管区带电泳分离／电化学检测果汁中有机酸的方法。方法：以溴化十六烷基溴化吡啶（CPB）作电渗流反向修饰剂，在电泳溶液中添加β-环糊精（β—CD）以提高分离选择性，并进行分离条件的优化，实现了草酸、柠檬酸、苹果酸、酒石酸、琥珀酸、延胡索酸六种有机酸的基线分离．采用纳米钯修饰碳糊电极安培检测器分别加以测定。结果：本法对有机酸检测限（S／N=3）低于2gmol／L，线性范围在2个数量级以上（1×10^-6～1．0×10^-3mol／L），相对标准偏差1．05％～2．15％，加标回收率93．4％。结论：本法快速，灵敏度高，选择性强，适合于果汁中几种有机酸的同时测定。

Objective： The method for separation by capillary zone electrophoresis （CZE） and electrochemical determination of organic acids in fruit juices was developed. Method： In this system, 0.2mmol/L cetylpyridinium bromide （CPB） was used as an electro osmotic flow （EOF） modifier to reverse the direction of EOF.β cyclodexfrin （β-CD） was added into running buffer to improve the separation efficiency. Then, the optimal separation conditions were achieved and successfully employed to separate six organic acids, including oxalic, malic, tartaric, succinic, fumaric acid and citric acids. One nano palladium modified carbon paste electrode was used for determination. Results： The calibration curves for all organic acids studied were linear with 2-3 orders （1 ×10^-6 ～1.0×10^-3 mol/L） of magnitude and all the detection limits （S/N=3） were below 2μmol/L. The RSD was between 1.05%-2.15% , and recovery was 93.4% . Conclusion： CZE separation combined with electrochemical detection is suitable for simultaneous determination of organic acids in fruit juices quickly with high sensitivity and selectivity.