电感耦合等离子体质谱法测定植物性农产品中碘含量

Determination of iodine content in vegetalitas agricultural products by inductively coupled plasma mass spectrometer

目的建立了电感耦合等离子体质谱法(inductivelycoupled plasma-mass spectrometry,ICP-MS)测定植物性农产品中碘含量。方法样品中加入碳酸钾和硫酸锌,采用干灰化法破坏有机物,固定样品中的碘,利用电感耦合等离子体质谱仪在标准模式和碰撞模式下测定植物性农产品中碘的含量。结果碘标准溶液在1.0~15.0μg/L质量浓度范围内线性关系良好,标准模式和碰撞模式下相关系数(r)分别为0.9999和0.9998。不同基质样品在3个不同添加水平下的回收率在86.9%~103.1%之间,相对标准偏差在0.88%~3.06%之间,符合要求。2种测定模式下的方法检出限一致,红薯为0.005 mg/kg、西红柿和豇豆为0.003 mg/kg。测定的国家有证标准物质(GBW 10020和GBW 10023)中碘的含量,测定值均在标准值不确定度范围内。结论与传统的硫氰酸铁-亚硝酸催化动力学法相比,该方法操作简便、节省试剂、稳定性好、精密度高、检出限低,大大提高了检测效率,适用于植物性农产品中碘含量的快速、准确定量分析。

Objective To establish a method for determination of iodine content in vegetalitas agricultural products by inductively coupled plasma-mass spectrometry （ICP-MS）. Methods Potassium carbonate and zinc sulfate were added to the sample to destroy organic matter by dry ash method, and the iodine in the sample was fixed. The iodine content in vegetalitas agricultural products was determined under standard mode and collision mode using ICP-MS. Results The iodine standard solution had a good linear relationship within the mass concentration range of 1.0-15.0 μg/L, and the correlation coefficients （r） in the standard mode and the collision mode were 0.9999 and 0.9998, respectively. The average recoveries ranged from 86.9% to 103.1% at the three spiked levels, and the value of RSD was 0.88%-3.06%, meeting the requirements. The limits of detection of the two measurement modes were the same, 0.005 mg/kg for sweet potato, 0.003 mg/kg for tomato and cowpea. The national certified standard substances （GBW 10020 and GBW 10023） were determined using the established method, and the measured values were within the range of standard value uncertainty. Conclusion Compared with the traditional iron thiocyanate-nitrite catalytic kinetics method, this method is easy to operate, reagents saving, with good stability, high precision and low detection limit, and improves the detection efficiency greatly, which is suitable for rapid and accurate quantitative analysis of iodine content in agricultural products.