电化学法测定天花粉和葛根饮片中二氧化硫残留量

目的:建立天花粉、葛根饮片中二氧化硫残留量的电化学测定法。方法:样品经粉碎后加入适量碳酸钙及酸水溶液,加热,通过产生的二氧化碳气体将样品中亚硫酸酸化后生成的二氧化硫气体带出,选用吸收液将其吸收,蘸取少许溶液在微电极上发生氧化还原反应,通过电流电势的变化来检测样品中二氧化硫的含量。将该方法测定值与离子色谱法和滴定法测定结果进行比较。结果:3种方法测得天花粉、葛根饮片样品中二氧化硫残留量基本相同。结论:电化学法具有重现性好,实验成本低,分析速度快的优点,可用于天花粉、葛根饮片中二氧化硫残留量的测定。

Objective:To establish an electrochemical method for determining the sulfur dioxide residues in sliced prepared Chinese raw medicinal materials, such as Radices Trichosanthis and Radix Puerariae. Methods:After being smashed, the samples were added with suitable amount of calcium carbonate and acid aqueous solution and were heated. The SO₂ gas generated from the sulfites of samples by acidification was carried out by CO₂ gas and was absorbed in the absorption solution. The oxidation-reduction reaction was produced by dipping a little solution on the micro electrode and the content of SO₂ in the samples then was determined by the means of current potential changes. The results of SO₂ values were compared with the results by the electrochemical method, ion chromatography method and titration method. Results:The sulfur dioxide contents were basically the same by the three different methods. Conclusion:The electrochemical method possesses the advantages of good reproducibility, low cost of experiment and fast analysis speed, and it can be used for the determination of sulfur dioxide residue in Radices Trichosanthis and Radix Puerariae.