共振光猝灭法测定环境水样中痕量硒

Determination of Trace Selenium in Environmental Water Samples by Using Resonance Light Quenching Method

在阿拉伯树胶（AG）存在下,0.14 mol/L硫酸介质中,硒（Ⅳ）与过量的I-反应生成I3-,加入乙酸钠后I3-与亚甲基蓝反应成离子缔合物,在波长288 nm处共振光猝灭,建立了共振光散射法测定痕量硒的方法。确定了碘化钾、亚甲基蓝、乙酸钠和增溶剂阿拉伯树胶溶液的浓度,在室温（20-30℃）下反应15 min,提高了体系的灵敏度和稳定性。共振光散射猝灭值与硒（Ⅳ）浓度在0-0.24μg/mL范围内线性关系良好,方法检出限为1.01μg/L。Fe^3＋、Pb^2＋、Cu^2＋和Zn^2＋的干扰用EDTA消除。方法用于测定环境水样中痕量硒,相对标准偏差（RSD）为1.3%-3.6%（n=5）,回收率为97.4%-100.8%。

A new resonance light quenching method for the quantification of trace selenium has been developed.The method is based on the reaction of Se（Ⅳ） with excess I-in 0.14 mol/L H2SO4 solution to produce I-3 with arabic gum（AG）.After adding NaAc,I-3 reacts with methylene blue（MB） to form an ion-association complex,resulting in resonance light quenching at a wavelength of 288 nm.The optimum concentrations of KI,MB,NaAc and solubilizer AG were decided.In addition,reaction for 15 min at room temperature（20-30℃） was found out.As a result,the sensitivity and stability of the system was improved.Good linear relationship between resonance light quenching intensity and Se（Ⅳ） concentration occurs in the content range of 0-0.24 μg/mL.The detection limit is 1.01 μg/L.The interferences of Fe^3＋,Pb^2＋,Cu^2＋ and Zn^2＋ are eliminated by EDTA.This method was applied to the quantification of trace selenium in environmental water samples with RSD of 1.3%-3.6%（n=5） and recoveries from 97.4% to 100.8%.