气浮溶剂浮选光度法测定食品中痕量SO_3^(2-)的研究  

SOLVENT-FLOATATION-PHOTOMETRIC DETERMINATION OF SO_3^(2-) IN FOODSTUFF

作　　者：李松田[1] 邢朝晖[1] 闫永胜[1] 

机构地区：[1]河南平顶山学院化学系,平顶山467000

出　　处：《理化检验（化学分册）》2005年第2期77-79,86,共4页Physical Testing and Chemical Analysis(Part B:Chemical Analysis)

摘　　要：提出了碘溴化十六烷基三甲胺缔合体系溶剂浮选褪色光度法测定SO2-3 的新方法,方法的摩尔吸光系数ε365=3.0×105L·mol-1·cm-1,最大吸收波长为365 nm,测定5.0μg/50 mLSO2-3 6次,RSD为1.8%,线性范围为0~30μg/50 mL,方法应用于食品中SO2-3 的测定。In a phosphate buffer medium of pH 7.0, free iodine liberated through the oxidation of I^- by IO^-_3, reacts with excess I^- to form a binary complex of I^-_3, which reacts further with CTMAB to form a ternary ion association complex of CTMA^+·I^-_3. This ternary complex is easily soluble and kept stable in organic solvents, in which it has Absorption maximum at 365 nm. In the presence microamounts of SO^(2-)_3 ion, the I^-_3 in the complex is reduced, leading to a decrease in Absorbance of the ternary complex (reductive color-fading) in organic solvent. It was found that the magnitude of decrease in Absorbance (ΔA) keeps a linear relationship with the concentration of SO^(2-)_3 in the range of 0~30μg per 50 mL of solution. Based on this phenomenon and applying the solvent floatation technique with 5.0 mL of benzene, the sensitivity of this method is remarkably enhanced, giving an apparent molar Absorptivity of 3.0×10~5L·mol^(-1)·cm^(-1) (at 365 nm). In the application of this method to the determination of SO^(2-)_3 in vegetables and wine samples, RSD′s (n=5) of less than 4.3% were obtained, and recoveries found by standard addition method were in the range from 97% to 100%.

关 键 词：褪色光度法 溶剂浮选 离子缔合物 亚硫酸根离子 

分 类 号：O647.33[理学—物理化学]