样品中I-被溴水氧化成IO-3, 用甲酸除去多余的溴水, 在磷酸介质中IO-3与过量的I-生成I-3; 样品中的IO-3在磷酸介质中直接与加入的过量 I-生成I-3, I-3在350和288 nm具有强吸收, 且吸光度与I-3的浓度在一定的范围内具有线性关系。 通过测定样品氧化前后的吸光度分别得到样品中I-和IO-3总量以及IO-3的量, 差减法得到I-的量, 建立了自身紫外光谱法快速方便地测定卤水和海产品中的I和IO-3。 讨论了溴水、 甲酸、 磷酸和碘化钾的加入量以及光照、 反应时间、 反应温度对测定的影响, 优化试剂条件是: 对测定I-的体系, 加入3% 溴水溶液2滴, 10%甲酸溶液0.5 mL, 20%磷酸溶液4 mL, 100 g·L-1 KI溶液1 mL; 对测定IO-3的体系, 加入20%磷酸溶液0.2 mL, 100 g·L-1 KI溶液1 mL。 室温避光条件下反应30 min测定体系吸光度。 在优化条件下, I和IO-3的浓度分别在0～1.2 mg ·L-1与0～1.5 mg ·L-1的范围内符合朗伯-比尔定律。 对样品空白平行测定12次, 得到I-和IO-3的检出限分别是1.54和14.8 μg·L-1。 对0.8 mg·L-1的I和IO-3平行测定12次, 相对标准偏差分别是0.097%和0.067%。 用建立的方法直接测定了扎布耶卤水、 洪峰地下卤水中的I-和IO-3, 并且采用碱式消解测定了海带、 紫菜、 海白菜中I-和IO-3, 同时进行了样品加标回收实验, I-和IO-3回收率均在80%～120%之间, 测定结果符合分析化学检测要求。

The iodide in samples was oxidized to iodate by bromine water, which could be removed by formic acid, and iodate could be transformed to I-3 with excess of I- in phosphoric acid, the iodate in samples could be transformed directly to I-3 with excess of I- in phosphoric acid. The I-3 solution had strong absorption at 350 and 288 nm, and the absorbance had a linear relationship to the concentration of I-3 in a certain range. Total content of iodide and iodate had been detected after samples were oxidized by bromine water and the content of iodate had been detected directly, and the content of iodide was obtained by difference of the two results. Based on this, the method had been established to detect iodide and iodate in brine and seafood simultaneously by ultraviolet absorption spectrometry. The volumes of bromine water, formic acid, phosphoric acid and potassium iodide had been optimized. The effect of illumination, temperature and time also had been discussed. The optional reagents condition for iodide was: 2 drops of 3% bromine water, 0.5 mL of 10% formic acid, 4 mL of 20% phosphoric acid and 1 mL of 100 g·L-1 KI. The optional reagents condition for iodate was: 0.2 mL of 20% phosphoric acid and 1 mL of 100 g·L-1 KI. The absorbance were determined after reacting for 30 min at room temperature and natural light conditions. Under the optimized conditions, the concentration of iodide and iodate in the range of 0～1.2 and 0～1.5 mg·L-1 were well agreed with Lambert Beer law. The sample blank was detected for twelve times and the detection limit of iodide and iodate were 1.54 and 14.8 μg·L-1 respectively. The RSD of twelve times determination of 0.8 mg·L-1 of iodide and iodate were 0.097% and 0.067%, respectively. The iodide and iodate in Zhabuye brine, Hong Feng underground brine, kelp, seaweed and sea cabbage had been detected, the recovery experiments also had been conducted at the same time, the recovery of iodide and iodate were between 80%～120%. All the results met the requirement of analytical chemistry.