拟反相色谱法测定儿童巧克力食品中的咖啡因含量

Rapid Determination of Caffeine in Children's Chocolate-containing Foods by Pseudo Reversed Phase Liquid Chromatography

建立了儿童巧克力食品中咖啡因含量的快速检测新方法。采用拟反相色谱法以极性硅胶柱配以高水量的流动相,5分钟内快速完成样品测定。其最佳测定条件为乙腈-甲酸钠溶液(0.03 mol/L,pH 2.9)(5:95)。在线性范围0.2-1000μg/mL内,线性关系良好,r=0.9995(n=5),检出限(S/N=3)为0.05μg/mL。回收率范围为96.5-104.3%,精密度测试结果 RSD%<4.8%。由于分析时间短,而且流动相中乙腈的比例只占5%,极大降低了有机溶剂的消耗和排放,节约测试成本的同时减少了对环境的污染。将其用于多种巧克力食品中咖啡因含量的测定,结果快速、准确、选择性高,可用于食品中咖啡因含量的常规测定,尤其适合大批量样品的连续测定。同时还对咖啡因的保留机理进行了探讨。

In this paper,a rapid and sensitive method based on pseudo reversed phase liquid chromatography（pseudo-RPLC） was developed for analysis of caffeine in children＇s chocolate-containing foods.The samples were analyzed on a polar silica column using an aqueous-rich mobile phase（sodium formate 0.03 mol/L,pH 2.9-acetonitrile,V/V,95：5）.All the samples were tested within 5 min.In view of less organic modifier（only 5%） in mobile phase and shorter analysis time,it was not only economical,but also environment-friendly.In addition,the assay was validated in the concentration range of 0.2-1000 μg/mL.The proposed method was applied to chocolate-containing foods.Recoveries at the concentration of 20-60 μg/mL ranged from 96.5% to 104.3% with RSD 4.8%.The present pseudo-RPLC technique proved to be a good alternative of reversed-phase liquid chromatography for the analysis of caffeine in popular chocolate-containing products with the advantages of fast-speed,low-cost and selectivity.Moreover,the retention mechanism of caffeine was discussed.