Development and validation of an adsorptive stripping voltammetric method for the quantification of vincamine in its formulations and human serum using a Nujol-based carbon paste electrode.

An easy, rapid and selective adsorptive stripping voltammetry (AdSV) method for the determination of vincamine in its formulation and human serum was developed and validated. It was based on the oxidation of the drug onto a Nujol-based carbon paste electrode. The stripping step was carried out by using a square-wave (SW) potential-time voltammetric excitation signal. The optimal experimental variables as well as accumulation parameters were investigated as; frequency f=120 Hz, scan increment DeltaE(i)=10 mV, pulse-amplitude DeltaE(a)=25 mV and an accumulation potential E(acc) of 0.0 V using a Britton-Robinson (B-R) universal buffer of pH 5 as a supporting electrolyte. After validation of the described method, it was applied for determination of vincamine in its formulation and human serum. Mean recovery of 100.41+/-0.74 (n=5) was achieved for assay of vincamine in Oxybral capsules. Limits of detection and quantitation of 6.0 x 10(-9) M (2.20 ng ml(-1)) and 2 x 10(-8) M (7.33 ng ml(-1)) vincamine were achieved in human serum with a mean recovery of 99.5+/-1.79%, without prior extraction of the drug. No interferences were observed in formulation and/or human serum. Due to high sensitivity and specificity of the developed method, it was successfully applied for evaluating some pharmacokinetic parameters of two healthy volunteers after administration of a single oral Oxybral capsule.