Effect of single walled carbon nanotube–cetyltrimethyl ammonium bromide nanocomposite film modified pyrolytic graphite on the determination of betamethasone in human urine

A sensitive voltammetric method has been described for the determination of betamethasone sodium phosphate (BSP) using edge plane pyrolytic graphite electrode (EPPGE) modified with single walled carbon nanotubes–cetyltrimethyl ammonium bromide nanocomposite film. The reduction of BSP occurred in a well-defined peak having Ep −1062 mV in phosphate buffer solution (PBS) of pH 7.2. The voltammetric response of betamethasone sodium phosphate enhanced effectively using cationic surfactant cetyltrimethyl ammonium bromide (CTAB) as electrode surface modifier. The nanotubes-surfactant modified edge plane pyrolytic graphite electrode shows great improvement in peak current and shift of the reduction potential towards less negative potential. The role of cetyltrimethylammonium bromide on electrocatalytic property is discussed. The limit of detection (3σ/slope) was found to be 0.25 × 10−9 M and limit of quantification was 0.86 × 10−9 M. The analytical utility of the proposed method is demonstrated by the direct assay of betamethasone in urine samples of pregnant women.