用巯基棉对砷(Ⅲ)富集分离后,基于试剂7-(2,4-羟基-5-羧基苯偶氮)-8-羟基喹琳-5-磺酸(DHCBAQS)与砷(Ⅲ)反应的荧光性能,快速测定水样中痕量砷.在试验条件下,于激发波长和发射波长296,396 nm波长处,pH为9.0时,荧光试剂呈现强荧光,砷(Ⅲ)的存在,使荧光强度下降,其下降强度与砷(Ⅲ)浓度呈线性关系,线性范围为0.5~6 μg·L-1,检出限(3S/N)为0.2 μg·L-1.用于3种不同水样中砷(Ⅲ)的测定,测得方法的相对标准偏差均小于3%,用标准加入法测得其回收率在102%~108%之间.

Trace amounts of arsenic(Ⅲ) was separated and enriched on sulfhydryl cotton from the sample solution acidified to 1 mol·L-1 with HCl,desorbed from the sulfhydryl cotton with conc. HCl and determined by fluorophotometry at wavelengths of (λex) 296 nm and (λem) 396 nm. In an ammoniacal buffer solution of pH 9.0,arsenic(Ⅲ) was reacted with the reagent 7-(2,4-dihydroxy-5-carboxyphenylazo)-8-hydroxyquinoline-5-sulfonic acid (DHCPAQS),leading to quenching of fluorescence of the reagent. Linear relationship between the magnitude of decrease in fluorescence intensity and concentration of arsenic(Ⅲ) was kept in the range of 0.5-6.0 μg·L-1 with detection limit (3S/N) of 0.2 μg·L-1. The proposed method was applied to determination of arsenic in samples of tap water,rain water and channel water,giving values of RSD′s (n=10) less than 3% and values of average recovery in the range of 102%-108%.