调味盐碘离子测定中碱保护剂的选择

Selection of alkali protectant in the determination of iodide in salt

目的探索适合调味盐碘含量测定的碱保护剂。方法选取低钠菇盐为样品,在样品前处理过程中分别用NaOH、NaHCO_3、Na_2CO_3作为碱保护剂,采用国家标准氧化还原法,对盐产品的碘含量进行检测。结果最佳碱保护剂为NaHCO_3,溶液最佳pH值为4,相对标准偏差2.3%～4.2%,回收率98.9%～100.5%,能够满足调味盐碘测定精密度和准确度要求。结论 NaOH作为碱保护剂对瓷坩埚造成强烈腐蚀性,降低坩埚使用寿命; Na_2CO_3作为碱保护剂,反应剧烈,结果误差较大; NaHCO_3为碱保护剂时,腐蚀刺激性低,安全环保,故推荐NaHCO_3作为调味盐碘离子测定的碱保护剂。

Objective To explore the suitable alkali protectant for the determination of iodine content in seasoning salt. Methods Low sodium mushroom salt was selected as sample, and NaOH, NaHCO3 and Na2CO3 were used as alkali protectant in the sample pretreatment process. The iodine content of salt products was detected by the national standard redox method. Results The best alkali protectant was NaHCO3. The best pH value of the solution was 4, the relative standard deviations were 2.3%-4.2% and the recovery rates were 98.9%-100.5%, which could meet the precision and accuracy requirements of the flavoring salt iodine. Conclusion NaOH as an alkali protector causes strong corrosiveness to porcelain crucible and reduces the life of crucible. Na2CO3 as an alkali protector, the reaction is intense, the result error is large. NaHCO3 as an alkali protector has low corrosion irritation and safety. Therefore, NaHCO3 is recommended as alkali protector for the determination of salt iodide ion.