Adsorptive stripping voltammetric determination of pyridostigmine bromide in bulk, pharmaceutical formulations and biological fluid

Electro-analytical behaviour of pyridostigmine bromide (PB) in BR buffers of pH range 2.4-10 at a hanging mercury drop electrode has been investigated using cyclic voltammetry, differential pulse cathodic adsorptive stripping voltammetry (DPCAdSV) and square-wave cathodic adsorptive stripping voltammetry (SWCAdSV). Voltammograms of the drug exhibited a single two-electron wave and it may be attributed to the reduction of -C=O- centre. Based on the high adsorptive character of PB onto the mercury electrode, a validated direct square-wave cathodic adsorptive stripping voltammetric and differential pulse cathodic adsorptive stripping voltammetric procedure has been developed for the determination of drug in bulk form and pharmaceutical formulations. The proposed SWCAdS and DPCAdS voltammetric methods allow quantitation over the range 100 ng mL^-1-72 μg mL^-1 and 1-80 μg mL^-1 with detection limit of 20.7 and 32.3 ng mL^-1, respectively. The procedure was applied to the assay of the drug in tablets form with mean percentage recoveries of 100.1% with SWCAdSV and 99.99% with DPCAdSV. Precision and accuracy were also checked and were within the limits. The peak current was linear with the drug concentration and percentage recovery was found to be good.