[Study on solid-phase-extraction spectrophotometric determination of silver with p-sulfobenzylidene-rhodanine].

The color reaction of silver with p-sulfobenzylidene-rhodanine (SBDR) was studied. Based on the color reaction of SBDR with silver (I) and the solid phase extraction of its colored complex with Waters Porapak Sep-Park-C18 cartridge, a new method for the determination of micro-amount of silver (I) was studied. In the presence of pH = 2.8 citric acid-sodium hydroxide buffer solution and Tween-80 medium, SBDR can react with silver (I) to form a stable 2:1 complex. The colored complex can be extracted by C18 cartridge and eluted by ethanol (containing 5% acetic acid), and then can be determined by spectrophotometry. The molar absorptivity is 7.53 x 10(4) L x mol(-1) x cm(-1) at 520 nm. Beer's law is obeyed in the range of 0-1.2 microg x (25 mL)(-1). This method can be applied to the determination of silver in water with satisfactory results.