茶叶中黄曲霉毒素的碘柱后衍生化和光化学柱后衍生化-高效液相色谱法比较

Comparison of iodine and photochemical derivatization methods after column separation-high performance liquid chromatography in the determination of aflatoxins in tea

目的比较茶叶中黄曲霉毒素测定的碘柱后衍生化和光化学柱后衍生化-高效液相色谱法。方法样品经过多功能净化柱净化,HPLC-柱后衍生化-荧光检测器检测。采用Agilent XDB C_(18)(4.6 mm×250 mm,5μm)色谱柱分离,检测激发波长为360 nm,发射波长为420 nm;以甲醇-水(40∶60,V/V)为流动相,流速为1.0 ml/min。柱后衍生化系统:(1)碘衍生化:衍生化溶液为0.05%碘溶液,流速为0.5 ml/min,衍生化反应温度为70℃;(2)光化学衍生化:接Welch Toxin Star光化学衍生器,内含254 nm紫外光源及15 m反应环。结果对于碘衍生化和光化学衍生化方法,黄曲霉毒素G2、B2在0.6 ng/ml^6 ng/ml,黄曲霉毒素G1、B1在2 ng/ml^20 ng/ml时线性关系良好,r>0.999 0,回收率为80.2%~97.5%。结论 2种衍生化方法的测定结果比较接近,光化学衍生化方法较灵敏,操作简单,2种柱后衍生方法都适用于茶叶中黄曲霉毒素的测定。

Objective To compare the iodine and photochemical derivatization methods after column with HPLC in the determination of aflatoxins in tea. Methods The samples were cleaned up with multi- functional columns and analyzed using HPLC after post- column derivatization. For chromatographic separation,an Agilent XDB C_（18）（ 4. 6 mm × 250 mm,5 μm） column was employed. The detection was performed using a fluorescence detector with the excitation wavelength at 360 nm and the emission wavelength at 420 nm. The mobile phase was methanol- water（ 40∶60,V / V）,and the flow rate was 1. 0 ml / min. For iodine post- column derivatization,0. 05% iodine solution was used as the derivatization reagent at a flow rate of 0. 5 ml / min and the reaction temperature of 70 ℃. For photochemical derivatization,the Welch Toxin Star photochemical derivatization device composed of a 254 nm UV light source and a 15 m reaction loop were used. Results Good linear relationships,with these two methods,were obtained when the concentration of aflatoxin G2 and B2were within 0. 6 ng / ml- 6 ng / ml,and that of aflatox G1,B1 within 2 ng / ml- 20 ng / ml,respectively（ r〉0. 999 0）. The recovery rates were among 80. 2%- 97. 5%. Conclusion The detection results are similar with the two post- column derivatization methods,with photochemical derivatization more sensitive and simpler,so both the derivatization methods are all applicable to the determination of aflatoxins in tea.