滴定法及离子色谱法测定中药二氧化硫残留量的对比实验

Study on comparison the determination of residue of sulfur dioxide in traditional Chinese medicine by ion chromatography and titration

目的比较及建立检测中药二氧化硫残留量的方法。方法样品采用酸提取-碘滴定法及酸性条件下水蒸气蒸馏法提取,以3%过氧化氢溶液作吸收液,离子交换-电导检测离子色谱法测定。色谱柱为IonPac@AS11-HC（250 mm×4mm）离子交换柱,保护柱为AG11-HC（50 mm×4 mm）,流动相为20 mmol/L KOH,流速1 ml/min,柱温30℃,检测池温度35℃。结果滴定法与离子色谱法测定的结果不完全一致。离子色谱法硫酸根在1～200μg/ml范围内线性关系良好,r=0.999。平均回收率为80.80%～103.07%,RSD为1.73%～7.62%。结论滴定法操作简便,成体低,但干扰因素多,误差较大;而离子色谱法具有灵敏度高、专属性强、自动化程度高等优点,可用于中药二氧化硫残留量的准确检测。实际工作中应根据条件及中药品种差异选用不同的方法进行测定。

Objective To establish a method for the determination of residue of sulfur dioxide in traditional Chinese medicine. Methods The samples were extracted by wet distillation under acidic conditions, with 3% hydrogen peroxide as absorption liquid, and then determined by ion exchange - ion chromatography conductivity detection. The determination was performed on IonPac@ AS11 - HC （250 mm × 4 mm） ion exchange column with mobile phase consisted of 20 mmoL/L KOH at a flow rate of 1 mL/min, the column temperature was set at 30℃, the detection cell temperature was set at 35 ℃. Results The linear range of sulphate was 1 - 200 μg/ml （ r = 0.999 ） with an average recovery of 80.80% - 103.07% （ RSD = 1.73 % - 7.62 % ）. Conclusion The method is sensitive, specific, automatic and simple.