Self-assembled surfactant monolayers on electrode surfaces

The electrochemical behavior of mometasone furoate (MF) has been studied at single-walled carbon nanotubes modified pyrolytic graphite electrode (MPG). Addition of cationic surfactant (cetyltrimethylammonium bromide, CTAB) was found to enhance the reduction current signal of MF, whereas, anionic (sodium dodecylsulfate, SDS) and non-ionic (Tween 60) surfactants exhibited opposite effect. A sensitive and selective electrochemical determination of mometasone furoate (MF) by square wave voltammetry and cyclic voltammetry in phosphate buffer of pH 7.2 has been carried out in the presence of CTAB. The cathodic peak current showed a linear response for MF reduction in the concentration range 10–1000 μM and using an electrode with effective surface area 0.225 cm2, a sensitivity and detection limit of 0.017 μA/μM and 1.23 μM, respectively were observed. The reduction site in MF was established by the separation and characterization of the product of reduction by 1H NMR and FT-IR spectroscopic measurements and found to be carbonyl group at position 3. The developed method was successfully applied for the determination of MF in pharmaceutical preparations and in human urine.