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建立了测定植物中痕量碘的高温热水解-催化分光光度法。设计了预处理程序以使植物样品能够稳定、彻底地进行热水解。通过正交实验优化了样品预处理的热水解参数:样品质量0.5g、氧气流量100mL/min、吸收液的NaOH浓度0.2mol/L、温度1100℃和热水解时间20min。为提高催化分光光度法测定吸收液中痕量碘的灵敏度,碘催化砷铈氧化还原反应的条件优化为:反应温度45℃、反应时间35min。该方法的检测限和定量下限分别为0.3ng/g和0.9ng/g,满足植物样品中痕量碘的分析要求。对国家标准植物样品的分析结果表明该方法准确度高、精密度好。由于使用的仪器都很常用、便宜,并具有测试费用低廉,检测限低、准确度和精密度高等优点,该方法易于推广使用,适合于植物样品碘含量的日常分析。
A high temperature thermolysis-catalytic spectrophotometry was established for the determination of trace amounts of iodine in plants. Pretreatment procedures were designed to allow plant samples to be stable and thoroughly thermolysis. The orthogonal test was used to optimize the thermal hydrolysis parameters of sample pretreatment. The sample mass was 0.5 g, the oxygen flow rate was 100 mL / min, the NaOH concentration was 0.2 mol / L, the temperature was 1100 ℃ and the thermal hydrolysis time was 20 min. In order to improve the sensitivity of catalytic spectrophotometry for the determination of trace iodine in absorbing solution, the conditions of iodine-catalyzed arsenic-cerium redox reaction were optimized as follows: reaction temperature 45 ℃, reaction time 35min. The limit of detection and limit of quantification for this method were 0.3 ng / g and 0.9 ng / g, respectively, which met the analytical requirements of trace iodine in plant samples. Analysis of the national standard plant samples showed that the method is accurate and precise. Because the instruments used are very common, cheap, and have the advantages of low testing cost, low detection limit, high accuracy and precision, the method is easy to popularize and suitable for routine analysis of iodine content in plant samples.