共振光猝灭法测定食盐中硒

基于聚乙烯醇存在的条件下,在pH 10.6的Na2B4O7-NaOH缓冲溶液中,钼酸铵与溴代十六烷基吡啶生成离子缔合物而产生强而稳定的共振光散射,1-(2-吡啶偶氮)-2-萘酚促进此离子缔合物离解,导致共振光猝灭,硒(Ⅳ)能加剧共振光猝灭,据此建立了共振光猝灭法测定硒的新方法。通过单因素试验和L16(45)正交试验对反应体系进行优化,确定了适宜反应条件。最大共振光猝灭波长位于375 nm,共振光强度猝灭值与硒(Ⅳ)浓度在0.8～4.8μg/L内线性关系良好。方法用于测定硒强化营养盐和健康平衡盐中硒,结果与荧光法一致,相对标准偏差为1.07%～1.61%(n=5),回收率为99.5%～101.5%。

Determination of Selenium in Salt by Resonance Light Quenching

A new resonance light quenching method for the determination of selenium has been established.In presence of polyvinyl alcohol,ammonium molybdate can react with cetylpyridimium bromide to form an ion-association complex in Na2B4O7-NaOH buffer solution at pH 10.6,which can produce strong and stable resonance light scattering.The chemical 1-(2-pyridylazo)-2-naphthol can promote the disassociation of the ion-association complex to cause the resonance light quenching.In addition,selenium can accelerate the quenching.Through single factor experiments and orthogonal designed experiments L16(45),the optimum reaction conditions were determined.Good linear relationship between resonance light quenching intensity and Se(Ⅳ) concentration occurs in the content range of 0.8~4.8 μg/L with the maximum resonance light quenching wavelength at 375 nm.The method has been applied in the determination of selenium in selenium fortified salt and healthy balanced salt.The results showed well consisted with those obtained by fluorescence method.The relative standard deviation was 1.07 %~1.61 %(n = 5),and the average recovery was 99.5 %~101.5 %.