氧化还原滴定法测定川盐中碘含量实验条件优化
Optimization of experimental conditions for determination of iodine content by REDOX titration method in Sichuan salt
刘淼 1邓雪 1曾晓龙 1曾云夏1
作者信息
- 1. 重庆市渝中区疾病预防控制中心,重庆 400010
- 折叠
摘要
目的 优化氧化还原滴定法测定川盐碘含量实验条件,获取更好的精密度和准确度.方法 根据方法原理,通过调节次氯酸钠有效氯浓度和煮沸时间,以国家碘缺乏病参照实验室有证标准物质检测结果作为指标,选择适宜条件.结果 加入有效氯为1.5g/1 00 mL的次氯酸钠溶液1 mL,并且在不加盖保持微沸状态延长煮沸时间至90 s,可以在GB 26878-2011《食品安全国家标准食用盐碘含量》允许食用盐碘含量范围(14～39 mg/kg)内达到良好的准确度,使其与标准值的偏差＜1.0 mg/kg;将川盐样品整体溶解定容至适宜容量的容量瓶中混匀,准确吸取一定体积进行测定可以使检测结果偏差减小,两次测量间绝对偏差≤0.5 mg/kg.结论 川盐中碘含量检测结果受次氯酸钠有效氯浓度和煮沸时间影响较大,通过降低次氯酸钠有效氯浓度及延长煮沸时间,可以获得良好的准确度.
Abstract
Objective To optimize the experimental conditions for the determination of iodine content in Sichuan salt by REDOX titration to obtain better precision and accuracy.Methods According to the principle of the method,the appropriate conditions were selected by adjusting the effective chlorine concentration of sodium hypochlorite and boiling time,and using the test results of the certified reference materiats provided by the"National Reference Laboratory for Iodine Deficiency Disorders"as indicators.Results Adding 1 mL sodium hypochlorite solution with effective chlorine of 1.5 g/100 mL,and extending the boiling time to 90 s without capping,good accuracy can be achieved within the allowable range of iodine content in edible salt(14-39 mg/kg)in GB 26878-2011 the"National Standard for Food safety about Iodine Content in Edible Salt",and the deviation from the standard value was ≤1.0 mg/kg.Dissolved and mixed the whole Sichuan salt sample into a volumetric bottle with appropriate capacity and accurately absorbed a certain volume for determination could reduce the deviation of the detection results,and the absolute deviation between two measurements was ≤0.5 mg/kg.Conclusion The determination results of iodine content in Sichuan salt are greatly affected by the effective chlorine concentration of sodium hypochlorite and the boiling time.Good accuracy can be obtained by reducing the effective chlorine concentration of sodium hypochlorite and extending the boiling time.
关键词
氧化还原滴定法/川盐/碘/有效氯/煮沸时间Key words
REDOX titration method/Sichuan salt/Iodine/Effective chlorine/Boiling time引用本文复制引用
出版年
2024
NETL
NSTL
万方数据