分光光度法测定离子膜工艺精盐水中的碘

Spectrophotometric determination of iodine in refined brine for ionic membrane process

借鉴水质分析中分光光度法测定微量碘的分析方法,建立了精盐水中碘的分析方法。方法的原理为碘离子与碘酸根的定量反应,用碘化钾-淀粉体系显色测定碘含量。通过试验明确了检测步骤的影响因素。试验表明:恰当的磷酸与甲酸钠加人量能够满足显色要求,无需依照原方法的规定,加热至沸去除甲酸钠,因此显色之前也无需再次调节酸度。本文建立的方法采用磷酸体系,保持pH值在2.5~3.5之间,方法检出限5μg/L,线性范围5~500μg/L,RSD小于10%,回收率在80%~110%。本方法全程无需加热,比借鉴方法大为节省时间,方法的检出限和精密度都能够满足现场快速检定的要求。

Referring to the analytical method of spectrophotometric determination of trace iodine in water quality analysis,an analytical method of iodine in refined brine is established.The methods is based on the principle of quantitative reaction between iodine ion and iodate radical.The iodine content was determined by potassium iodide and starch system.The influencing factors of the detection steps were determined by experiment.The test shows that the appropriate amount of phosphoric acid and sodium formate can meet the requirement of color development,without heating to boil to remove sodium formate according to the provisions of the original method,so there is no need to adjust the acidity again before color development.The method established in this paper adopts phosphoric acid system,keeps the pH value between 2.5 and 3.5,and the detection limit of the method is 5μg/L,linear range 5-500μg/L,RSD less than 10%,recovery 80%-110%.This method does not need heating in the whole process,which greatly saves time compared with the reference method.The detection limit and precision of the method can meet the requirements of on-site rapid verification.