萃取分光光度法测定白砂糖中微量亚硫酸盐

提出了以甲醛溶液作吸收液,分光光度法测定白砂糖中微量亚硫酸盐的新方法。在酸性及过量的Cl-存在下,亚硫酸盐与碘酸钾和盐酸副玫瑰苯胺反应,生成易被异戊醇萃取的稳定的离子缔合物,在λ=560nm处,分光光度法测定。亚硫酸盐(以二氧化硫计)的线性范围为0～50μg,RSD≤3.4%,检出限为2μg。方法简便灵敏,试剂毒性小。结果与国标法相符。

Determination of Trace Sulphite in Sugar by Extractive Spectrophotometry

A sensitive spectrophotometric method was developed for the determination of trace sulphite (SO 3 2- ) in sugar after SO 2 has been fixed in a buffered formaldehyde solution. The reaction of iodate and pararosaniline hydrochloride with the fixed SO 2 in the presence of H 2SO 4 and an excess of chloride leads to the formation of ion pair; The product is extracted into isopentyl alcohol and measured spectrophotometrically at 560nm. The color system obeys Beer's law over the range 0～50μg SO 2. The relative standard deviation is ≤ 3.4%, detection limit is 2μg. The method was applied to the determination of SO 3 2- in sugar, and the results obtained were showed satisfactory agreement with the GB method.