Voltammetric behavior and square-wave voltammetric determination of cefotaxime in urine

The voltammetric behavior of cefotaxime (CFX) is investigated by cyclic and square-wave voltammetry in BR buffers (pH 1.80–12.0). Based on the cathodic reduction peak at approximately −0.5 V in BR buffer (pH 2.8 and 9.25), a robust, highly reliable square-wave voltammetric method (SW) was developed for determination of CFX. The linearity was achieved by SW voltammetry in 7.5 × 10−9 M (3.52 ng ml−1) to 1.0 × 10−7 M (47 ng ml−1) and from 1.2 × 10−7 M (56.4 ng ml−1) to 1.2 × 10−6 M (568.8 ng ml−1) range at pH 2.8 with detection and quantification limits of 0.813 ng ml−1 and 2.71 ng ml−1, and 12.6 ng ml−1 and 42.2 ng ml−1, respectively. At pH 9.25 linear range was obtained from 4 × 10−8 M (18.8 ng ml−1) to 1.6 × 10−7 M (75.2 ng ml−1) with detection and quantification limits of 2.947 ng ml−1 and 9.82 ng ml−1. The method was applied for CFX determination in spiked humane urine sample. A detection and quantification limits of 7.2 ng ml−1 and 23.9 ng ml−1 were achieved for determination of CFX in urine at pH 2.8 and 13.6 ng ml−1 and 45.1 ng ml−1 at pH 9.25. The comparative reference method was DPV. The proposed method was checked for determination of CFX in real human urine, and selectivity of the method over the metabolites was found to be quite satisfactory.