SOLID PHASE EXTRACTION-SPECTROPHOTOMETRIC DETERMINATION OF SILVER WITH 4,5-DIMETHYL-2-THIAZOLYL-AZOLYL-DIAZO-AMINOAZOBEZENE

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%.