Hydrophobic stripping voltammetry of antihypertensive drugs at lipid-modified electrodes

The antihypertensive agents reserpine and rescinnamine were shown to be partitioned effectively into a lipid layer on a glassy carbon electrode. Such hydrophobic accumulation greatly enhances the sensitivity of the subsequent voltammetric scan, allowing convenient quantification of sub-micromolar concentrations. A high degree of selectivity is achieved as polar electroactive species are excluded by the hydrophobic layer. The drugs can therefore be quantified in the presence of a 100-fold amount of solution species with similar redox potentials. The response was evaluated with respect to accumulation time, concentration dependence, solution conditions, voltammetric waveform, possible interferences and other variables. Detection limits are 5 x 10(-9) M. The applicability of the method to selective measurements in untreated urine is described. The data shed new light on the sensing utility and discriminative properties of lipid electrodes.