Determination of nitrofurantoin drug in pharmaceutical formulation and biological fluids by square-wave cathodic adsorptive stripping voltammetry.

Nitrofurnation is an antibacterial drug. It is used in the treatment of initial or recurrent urinary tract infections caused by susceptible organisms. The cyclic voltammogram of the drug in Britton-Robinson buffers (pH 2-11) exhibited a single well-defined cathodic peak at the hanging mercury drop electrode, that due to the reduction of its nitro group to the amine stage. A fully validated, sensitive, and reproducible developed procedure was described for determination of the drug in bulk form, pharmaceutical formulation, human serum and human urine using, square-wave cathodic adsorptive stripping voltammetry. The optimal experimental parameters for the drug assay were: accumulation potential = -0.4 V (vs. Ag/AgCl/ KCl(s)), accumulation time = 40 s, frequency = 120 Hz, pulse amplitude = 50 mV and scan increment = 10 mV in Britton-Robinson buffer (pH 10). A mean percentage recovery of 100.68 +/- 0.17 (n = 5) and a detection limit of 1.32 x 10(-10) M of bulk drug were achieved. Applicability to assay of the drug in pharmaceutical formulation, human serum and human urine was studied and illustrated. The mean percentage recoveries were found as: 101.49 +/- 0.65, 103.94 +/- 0.73 and 101.98 +/- 0.52 (n = 5) in pharmaceutical formulation, human serum and human urine, respectively. Detection limits of 2.86 x 10(-10) M and 5.77 x 10(-10) M nitrofurantoin were achieved in human serum and urine, respectively.