Ms. Ibrahim et al., ADSORPTIVE STRIPPING VOLTAMMETRY MEASUREMENTS OF COPPER-CHELATES OF 3-METHYLXANTHINE AND 7-METHYLXANTHINE, Analusis, 24(3), 1996, pp. 84-88
Controlled adsorptive accumulation of copper complexed with 3-methylxa
nthine (3MXan) and 7-methylxanthine (7MXan) on a hanging mercury drop
electrode provides the basis for direct stripping measurement of these
compounds at the subnanomolar concentration level. The height of the
chelate peak, approximately 0.35 V more negative than the peak of the
free compound, is shown to be proportional to the methylated xanthine
(MXan) concentration. The adsorption and redox behaviour are indicated
by ac and cyclic voltammetry. Experimental and instrumental parameter
s for quantitative analysis are optimized. A more sensitive peak is ob
tained in berate buffer. Under the optimum conditions the calibration
curves are linear and the detection limits are given in absence and pr
esence of Cu(II). The interferences of several organic compounds are e
valuated.