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建立了高效液相色谱-电感耦合等离子体质谱(HPLC-ICP-MS)联用技术测定紫菜中IO_3~-,I~-,MIT和DIT的方法。采用离子交换色谱柱AS7分离4种碘形态,以175 mmol/L NH_4NO_3和4%(V/V)甲醇为流动相,在梯度洗脱的条件下可实现4种碘形态的完全分离。在此条件下,IO_3~-,I~-,MIT和DIT的方法检出限(以碘计)分别为0.09,0.34,0.09,0.33μg/L,可满足紫菜中碘形态的测定要求。对紫菜样品前处理方法进行了优化比较,最终确定40℃超声提取2次,每次超声2 h为紫菜样品前处理方法,方法可保持样品处理过程中各碘形态的稳定。利用建立的方法并结合体积排阻色谱对紫菜标准物质GSB-14中的碘形态进行分析,发现其主要以I~-和一种未知碘形态存在。
A method for determination of IO_3 ~ -, I ~ -, MIT and DIT in seaweed was established by HPLC-ICP-MS. Four iodine forms were isolated by ion-exchange column AS7. The separation of four iodine forms was achieved under gradient elution with 175 mmol / L NH_4NO_3 and 4% (V / V) methanol as mobile phase. Under these conditions, the detection limits (by iodine) of IO_3 ~ -, I ~ -, MIT and DIT were 0.09,0.34,0.09,0.33μg / L respectively, which could meet the determination requirements of iodine in seaweed. The method of pretreatment of seaweed samples was optimized and compared. The ultrasonic extraction was carried out twice at 40 ℃, and the method of pre-treatment of seaweed samples was carried out 2 h each time. The method could maintain the stability of each iodine form during the sample processing. Based on the established method and size exclusion chromatography, the iodine speciation of laver GSB-14 was found to be mainly present in I ~ - and an unknown iodine form.