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

摘要:

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0.2~1000 μg/mL内，线性关系良好，r=0.9995（n=5)，检出限（S/N=3）为0.05 μg/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。

Abstract:

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.