自制Z-Ⅱ碘探针应用于快速测定食盐及海带中的无机碘和有机碘

Rapid Determination of Inorganic and Organic Iodine in Edible Salt and Kelp Samples by a Z-Ⅱ Iodine Probe

目前食盐和海带产品中碘含量分析主要是总碘含量测定,而无机碘与有机碘形态分析主要依靠大型精密仪器联用技术。本文研制了一种基于硫化碘化银法研制的全固态、无内参液的晶体膜电极(Z-Ⅱ碘探针),采用聚四氟乙烯消化罐微波消解技术,建立了食用盐及海带中的无机碘及有机碘含量测定方法。实验结果表明:食盐中无机碘含量为20mg/kg,有机碘含量为2mg/kg,海带中有机碘含量为2.9×10^3mg/kg。无机碘及有机碘含量分别在10~100mg/kg范围内线性关系良好,加标回收率为97.1%~101.0%,检出限均为1mg/kg。本方法应用于食盐和海带实际样品中的碘含量测定,无机碘和有机碘测定结果的相对标准偏差(RSD)分别小于0.92%和2.49%,且测定结果与国家标准方法和紫外分光光度法的测定结果基本一致。该方法具有试剂耗量少、成本低的特点,操作方便,可应用于有机碘和无机碘含量的测定。

BACKGROUND: At present, iodine content in edible salt and kelp products is mainly determined as the form of total iodine content, but the speciation analysis of inorganic iodine and organic iodine mainly relies on the hyphenated techniques of large-scale instruments.OBJECTIVES: To establish the determination method of iodine content in edible salt and kelp as well as the digestion method for the organic iodine in the closed PTFE bomb.METHODS: Rapid determination of inorganic and organic iodine content in edible salt and kelp products by using crystal membrane electrode technique with a solid-state and no internal reference liquid crystal film electrode(Z-Ⅱ iodine probe) developed by silver sulfide iodide method, combined with PTFE bomb microwave digestion technique.RESULTS: Table salt contained 20 mg/kg of inorganic iodine, and 2 mg/kg of organic iodine. The concentration of organic iodine was 2.9×10^3mg/kg in kelp. The linear correlation of inorganic and organic iodine contents in the range of 10-100 mg/kg was good. The standard-addition recoveries were 97.1%-101.0%, and the detection limit was up to 1 mg/kg. This method was applied to the determination of iodine content in actual edible salt and kelp on the market, the relative standard deviation of inorganic and organic iodine in the samples was less than 0.92% and 4.20%, respectively. The analytical results were in agreement with those of the national standard method and ultraviolet spectrophotometry method, which indicated that the established method was reliable.CONCLUSIONS: The analytical method has the advantages of low reagent consumption, low cost and convenient operation, which can be used for the determination of inorganic and organic iodine contents.