ADSORPTIVE STRIPPING VOLTAMMETRY ON MERCURY-COATED CARBON-FIBER ULTRAMICROELECTRODES

The conditions for the electrodeposition of mercury on the surface of carbon fibres to permit the sensitive and reproducible voltammetry of folic acid and mitoxantrone (MXT) were investigated. The accumulation behaviour of both molecules on a mercury film ultramicroelectrode was studied and the possibility of carrying out a.c. adsorptive stripping analysis using mercury-coated carbon ultramicroelectrodes was demonstrated. Optimum conditions for both the deposition of mercury and a.c. monitoring are described. This procedure gave rise to a linear calibration graph from 5.0 x 10(-10) to 2.0 x 10(-8) M, a detection limit of 5.0 x 10(-10) M and a relative standard deviation (R.S.D.) of 5.05% at 5.0 x 10(-9) M (n = 10) for the determination of MXT. For folic acid a linear calibration graph from 1.0 x 10(-9) to 5.0 x 10(-8) M, a detection limit of 9.0 x 10(-10) M and an R.S.D. of 1.44% at 4.0 x 10(-8) M (n = 10) were found. Both compounds can be determined directly in biological samples at physiological levels without any separation or clean-up procedure.