Stripping voltammetric determination of silver(I) at carbon paste electrode modified with 3-amino-2-mercapto quinazolin-4(3H)-one.

A differential pulse anodic stripping voltammetric method was developed for the determination of Ag(I) at a 3-amino-2-mercapto quinazolin-4(3H)-one modified carbon paste electrode. The analysis procedure consisted of an open circuit accumulation step in stirred sample solution for 12min. This was followed by medium exchange to a clean solution where the accumulated Ag(I) was reduced for 15s in -0.6V. Subsequently an anodic potential scan was effected from -0.2 to +0.2V to obtain the voltammetric peak. The detection limit of silver(I) was 0.4microg L(-1) and R.S.D. for 10, 100 and 200microg L(-1) silver(I) were 2.4, 1.8 and 1.3%, respectively. The calibration curve was linear for 0.9-300microg L(-1) silver(I). Many coexisting ions had little or no effect on the determination of silver(I). The procedure was applied to determination of silver(I) in X-ray photographic films and natural waters. In X-ray photographic film samples, the results have compared to those obtained by atomic absorption spectroscopy.