一些方酸偶氮染料与硫酸根的显色反应及其分光光度测定

COLOUR REACTIONS OF SULPHATE WITH SOME SQUARIC ACID AZO CHROMOGENIC REAGENTS AND ITS SPECTROPHOTOMETRIC DETERMINATION

合成了５个方酸偶氮显色剂Ｎ－芳基－Ｎ′－［４－对硝基苯偶氮基）苯基］异方酰胺，它们的ＤＭＳＯ溶液均能与ＳＯ２－４发生显色反应，生成蓝色化合物．建立了用其中三种显色剂测定ＳＯ２－４的直接分光光度法．考察了ｐＨ、显色剂加入量、体系中含水量及共存离子对显色体系的影响．将该法用于自来水及井水中ＳＯ２－４的分析。

Five novel squaric acid azo chromogenic reagents N aryl N′ [4 p nitrobenzeneazo) phenyl] isosquaramides were synthesized.Their DMSO solutions can all react with sulphate to produce blue compounds.Direct spectrophotometric methods were developed for the determination of sulphate with three of the chromogenic reagents.Investigations were made on the effects of pH,concentrations of chromogenic reagents,water contents in chromogenic systems and the interferences of foreign ions.The methods were applied to the analysis of sulphate in tap and well water and satisfactory results were obtained.