研究了4,5-二甲基-2-噻唑偶氮重氮氨基偶氮苯(DMTDAA)与银的显色反应,在pH 11.0的硼砂-氢氧化钠缓冲介质中,乳化剂-OP存在下,DMTDAA与银反应生成2∶1稳定络合物,该络合物可用Waters XterraTM RP18固相萃取小柱富集,小柱上富集的络合物用乙醇 (内含001 mol·L-1 pH为11.0的四氢吡咯-乙酸缓冲盐) 洗脱后用光度法测定,在洗脱剂介质中λmax=518 nm,ε=1.39×105L·mol-1·cm-1.银含量在0.01-2.0 mg·L-1范围内符合比耳定律.方法用于环境水样中银含量的测定,结果的RSD在2.2%-2.8%,回收率在96%-104%.

Color reaction of silver with 4,5-dimethyl-2-thiazolyl-azolyl-diazo-amino-azobenzene (DMTDAA) was carried out in a borate buffer medium of pH 11.0 and in the presence of emulsifier OP to form a stable complex having a composition of molar ratio 2∶1.The complex was enriched by solid phase extraction on a Waters Xterra RP18 column.The enriched complex was then eluted with ethanol solution,containing 0.01 mol·L-1 pyrrolidine acetate buffer of pH 11.0.Absorbance of the eluate was measured at 518 nm.The color complex has the molar absorptivity (ε) of 1.39×105L·mol-1·cm-1.Beer′s law was obeyed in range of 0.01-2.0 mg·L-1 of Ag.The method has been applied to the determination of Ag in environmental water samples,giving RSD′s in the range of 22%-2.8%,and recoveries in the range of 96% to 104%.