自动充氮蒸馏-酸碱滴定法测定食品中二氧化硫

Determination of sulfur dioxide in food by automatic nitrogen-filled distillation and acid-base titration

中文关键词:  二氧化硫  酸碱滴定  条件优化  基质选择  干扰

英文关键词:sulfur dioxide  acid-base titration  condition optimization  matrix selection  interference

中文摘要:

      目的 建立自动充氮蒸馏-酸碱滴定法测定食品中二氧化硫残留量的分析方法。方法 称取20 g(或mL)均质试样, 加入350 mL纯水后进行充氮酸化蒸馏, 以50 mL 3%过氧化氢溶液为吸收液, 加盐酸溶液(6 mol/L) 10 mL, 氮气流量1.50 L/min, 蒸馏时间90 min, 微沸功率350 W, 用0.01 mol/L或0.1 mol/L氢氧化钠标准溶液进行滴定。结果 增加纯水添加量使测定结果轻微下降。加标实验有基质选择性, 亚硫酸钠溶液的储存时间与加标回收率负相关。乙酸是阳性干扰物, 能使检测结果显著偏高。本方法的相对标准偏差为0.5%~2.1%, 回收率范围为86.0%~96.3%, 最低检出限和定量限为0.5 mg/kg和5 mg/kg。对9类98批食品进行检测, 结果显示百合干和淮山干的检出率与超标率最高。结论 该方法稳定、操作简便, 测定结果准确度高、精密度好, 适用于食品(不含乙酸)中二氧化硫残留量的测定。

英文摘要:

      Objective To establish an analytical method for the determination of sulfur dioxide residues in food by automatic nitrogen-filled distillation and acid-base titration. Methods The 20 g (or mL) homogeneous sample was weighed, 350 mL pure water was added, and then nitrogen acidified distillation was carried out. The 50 mL 3% hydrogen peroxide solution was used as absorption solution, 10 mL hydrochloric acid solution (6 mol/L) was added, nitrogen flow rate was 1.50 L/min, distillation time was 90 min, and micro-boiling power was 350 W. Titrate with 0.01 mol/L or 0.1 mol/L sodium hydroxide standard solution. Results Increasing the amount of pure water made the measurement result decrease slightly. The additiontest had matrix selectivity, and the storage time of sodium sulfite solution was negatively correlated with the recovery rate. Acetic acid was a positive disruptor that could significantly increase the test results. The relative standard deviation of the method was 0.5%?2.1%, the recovery was 86.0%?96.3%, and the minimum limits of detection and quantitation were 0.5 mg/kg and 5 mg/kg respectively. Ninety-eight batches of 9 categories of food were tested, and the results showed that the detection rate and excess rate of dried lily bulb and dried dioscorea opposite were the highest. Conclusion The method is stable, easy to operate, has high accuracy and precision, and is suitable for the determination of sulfur dioxide residue in food (without acetic acid).