“滴定法测定二氧化硫”的实验方法改进研究

Improvement Research on the Experimental Method of“Titration Method for Determination of Sulfur Dioxide”

根据《食品检测与分析实验》教材中的方法,香菇中二氧化硫的测定由于溶液颜色较深影响终点的判断。实验通过水蒸气蒸馏,将馏出液用25 mL 1 mol/L KOH吸收,再通过0.01 mol/L I2标液测定香菇中SO2。同时对实验条件也进行了优化,结果表明:加热时间为110分钟,吸收液浓度为1 mol/L,加入1∶3硫酸10 mL后滴定结果最佳。同时与国标进行对比,偏差为6.7%。改进后的实验操作简单,实验终点易于观察,数据可靠。

According to the method in the textbook named“Food testing and analysis experiment”,the determination of sulfur dioxide in shiitake mushrooms affects the judgment of the end point due to the darker color of the solution.The experiment was carried out by steam distillation,the distillate was absorbed with 25 mL of 1 mol/L KOH,and SO2 in the mushroom was determined by 0.01 mol/L I2 standard solution.At the same time,the experimental conditions were also optimized.The results showed that the heating time was 110 minutes,the concentration of the absorption liquid was 1mol/L,and the titration result was the best after adding 10mL of 3∶1 sulfuric acid.What’s more,Meanwhile,the deviation of this experiment compared with the national standard was 6.7%.The improved experimental operation is simple and the experimental end point is easy to observe with more accurate results.