THE CATHODIC STRIPPING VOLTAMMETRIC DETERMINATION OF 6-MERCAPTOPURINEAT A SILVER ELECTRODE

Voltammetric studies have been carried out on 6-mercaptopurine (6MP) d eposited at a silver electrode. 6MP yields a cathodic stripping signal at about -1.0 V (vs. Ag/AgCl) in pH 7.2 sodium phosphate buffer. Unde r selected conditions a linear calibration plot was obtained over the range of 0.2-6 mu M with a relative standard derivation of 2.9% for 1 mu M 6MP (n = 11, t(d) = 60 s). The voltammetric response of 6MP was d ependent on experimental conditions such as solution pH and potential- scan range. Generally 6MP exhibits two adjacent peaks in acidic soluti ons (pH < 6, C < 0.1 mM), a sharp peak in pH6-9 solutions, and a broad wave with a small peak in basic solutions (pH > 9). Cetyltrimethylamm onium bromide causes an enhancement of the cathodic stripping peak.