提出了一种间接分光光度法测定多糖硫酸酯中硫酸根含量的方法.取一定量的经水解后的试样溶液,加入已知且过量的氯化钡标准溶液使试样溶液中的硫酸根以BaSO4形式沉淀析出,放置5 min后,加入已知且过量的标准铬酸钾溶液使过量钡离子以BaCrO4形式沉淀析出,经离心使沉淀与溶液分离.定量移取上层清液,于pH 3.4的HOAc-NaOAc缓冲溶液中加入邻联甲苯胺,使与过量的CrO2-4反应生成蓝绿色产物,于624 nm波长处测得其吸光度.结果表明硫酸根质量在50~250 μg之间服从比耳定律.对方法的精密度和回收率作了试验,测得相对标准偏差(n=6)为1.55%,平均回收率为99.25%.

An indirect spectrophotometric method for determination of SO2-4 radical in polysaccharose sulfate was proposed.A definite amount of the hydrolyzed sample solution was taken and the sulfate radical was precipitated as BaSO4 by adding an excess of known amount of standard barium chloride solution.After staying for 5 min,a definite and excess amount of standard potassium chromate solution was added to the reaction mixture to precipitate the excess amount of Ba2+ as BaCrO4.The precipitate was separated by centrifuging,and an aliquot of the supernatant solution was taken to react with o-toluidine in an acetate buffer solution of pH 3.4,giving a colored product,the absorbancy of which was measured at 624 nm.Beer′s law was obeyed in the range of 50-250 μg for SO2-4.Precision and recovery of the method were tested giving results of RSD′s (n=6) to be 1.55%,and value of average recovery to be 99.25%.