碘-罗丹明B-OP体系分光光度法测定水中溶解氧

基于I3-与罗丹明B在OP存在下结合成电中性的离子缔合物在360 nm波长处有最大吸收,提出了水样中溶解氧的光度法测定。于待测水样中加入硫酸锰及碱性碘化钾溶液,水中溶解氧与之形成Mn2O3沉淀,加入浓硫酸使与Mn2O3沉淀反应而析出单质碘,在酸性条件下析出的碘与罗丹明B溶液在360 nm波长处有最大吸收,以碘酸钾为基准物,对水样中溶解氧含量进行分光光度法测定。溶解氧浓度在0.002 7~0.686 mg/L范围内符合比尔定律,表观摩尔吸光系数为4.012×104L.cm-1.mol-1,方法的检出限为0.001 0 mg/L。此法对不同来源的水样中溶解氧含量进行测定,所得结果与碘量法及溶解氧测定仪所测得的结果相符合。

Spectrophotometric determination of dissolved oxygen in water through iodine-rhodamine B-OP system

Based on the reaction between iodine and rhodamine B which produced a ion-association complex with its absorption maximum at the wavelength of 360 nm, a photometric determination of dissolved oxygen in water was proposed. Dissolved oxygen in the sample was precipitated by adding MnSO_4 in an alkaline medium to form Mn_2O_3 from which oxygen was liberated upon addition of H_2SO_4, and reacted with the free I_2 liberated by the reaction of KI with H_2SO_4. The absorbance of ion-association complex was measured photometrically at 360 nm. The content of dissolved oxygen was found from the standard curve drawn by using KIO_3 standard solution as reference. Beer's law was kept in the range of 0. 002 7-0. 686 mg/L dissolved oxygen. The apparent molar absorption coeffi-water samples, results obtained by this method were in consistency with the results obtained by io-dometry and by the dissolved-oxygen determinator.