柱前衍生毛细管电泳-电致化学发光法测定日用化妆品中的氨甲环酸含量

将氨甲环酸进行N-甲基化衍生反应后,其衍生产物能与联吡啶钌电致化学发光试剂产生强的共发光信号,据此建立了毛细管电泳-电致化学发光法高选择性测定日用化妆品试样中氨甲环酸含量的新方法。实验中发现,添加一种Mg2+-海藻糖-SiO2-3三元缔合物凝胶至背景电解液中,可极大地改善电泳分离效能。在优化的分析条件下,氨甲环酸和内标物肌氨酸衍生产物的电泳峰可在500 s内达到完全分离,且此两个电泳峰的强度比值与氨甲环酸的初始浓度在10~750μmol/L的范围内呈良好的线性关系(相关系数r2=0.9993),检出限为3.6μmol/L(S/N=3)。采用内标法对3种市售牙膏膏体和2种面膜护理液中的氨甲环酸进行了定量测定,测得这些试样中氨甲环酸含量的均值分别为4.05、0.24、6.06 mg/g和51.3、7.98 mg/mL,加标回收率在92.5%~104.0%内,结果令人满意。

Determination of tranexamic acid in essential cosmetics by pre-column derivatization capillary electrophoresis coupled with electrogenerated chemiluminescence detection

N-Methylation of tranexamic acid yields an unique derivative, which generates strong co-luminescence signals in the presence of an electrochemiluminescence reagent such as Ru(bpy)₃²⁺. Using this principle, we established a highly selective analytical method based on pre-column derivatization capillary electrophoresis coupled with electrogenerated chemiluminescence detection for determining the tranexamic acid content in essential cosmetics. The addition of a ternary ionic association gel, Mg²⁺-trehalose-SiO₃^2-, in the components of background electrolyte greatly improved the electrophoretic separation efficiency. Under the optimized assay conditions, two electrophoretic peaks attributed to the derivatives of tranexamic acid and its internal standard (sarcosine) were completely separated in 500 s, and their electrophoretic peak intensities ratio showed a good linear relationship with the initial concentration of tranexamic acid in the range of 10-750 μmol/L (correlation coefficient r²=0.9993). The limit of detection was estimated to be 3.6 μmol/L (S/N=3). Moreover, the internal standard method was further applied to the quantitative determination of tranexamic acid content in three kinds of toothpaste and two kinds of nutrient solutions in facial masks. The results showed that the average tranexamic acid content in three toothpaste samples was 4.05, 0.24, and 6.06 mg/g, while that in two facial masks was 51.3 and 7.98 mg/mL. The recoveries for the above-mentioned samples were within the range 92.5% to 104.0%, implying satisfactory results.