电动流动分析-胶束电动毛细管色谱联用测定食品防腐剂

Determination of Preservatives in Food Samples by Electrokinetic Flow Analysis and Micellar Electrokinetic Chromatography

采用电动流动分析(EFA)和胶束电动毛细管色谱(MEKC)联用系统测定了食品中的防腐剂。EFA系统设备简单便携、易于实现自动化。EFA由一台自制电渗泵、5个电磁切换阀(由计算机通过自制接口卡和自编VC语言程序控制)和一个固相萃取微柱组成,采用EFA-MEKC低试剂消耗接口,可减少含贵重试剂的缓冲液消耗。MEKC缓冲溶液为100mmol/L十二烷基硫酸钠(SDS)+20mmol/LNa2B4O7(pH9.3)。使用对羟基苯甲酸(PBA)为内标物,方法可在15min内分离测定6种防腐剂,峰面积相对标准偏差小于3.4%;检出限范围为0.04～0.1mg/L;实际样品的回收率为91.4%～104%。

A combined system of electrokinetic flow analysis （EFA） and micellar electrokinetic capillary chromatography （MEKC） was proposed to determine six preservatives in food samples. The EFA system consists of one homemade electroosmotic pump, five solenoid valves and one solid-phase extraction （SPE） microcolumn. The electroosmotic pump and solenoid valves were controlled by a personal computer with a homemade interface card and a Visual C program written by our group. An interface of EFA and MEKC was designed to reduce running buffer consumption, espexcially for the buffer solution containing expensive reagent. The running buffer of MEKC was 20 mmol/L disodium tetraborate（pH 9.3） containing 100 mmol/L SDS. p-hydroxybenzoic acid（PBA） was adopted as an internal standard. The proposed method can separate and determine the preservatives within 15 min, with the relative standard deviation of peak area less than 3.4% （n = 5）, limits of detection ranged from 0.04 to 0.1 mg/L（S/N = 3, n = 11 ） and recoveries ranged from 91.4% to 104%. The EFA system was simple, convenient and easy to be controlled automatically.