Simultaneous voltammetric determination of triclosan and chlorhexidine in pharmaceutical and personal care products at glassy carbon electrode.

Although a number of electroanalytical methods for the determination of triclosan (TCS) and chlorhexidine (CHX) have been reported to date, none has been developed for their simultaneous determination. The present work describes the first electroanalytical method for their simultaneous voltammetric determination in pharmaceutical and personal care products. The method is based on the anodic oxidation of these antimicrobial agents at a glassy carbon electrode in a mixture of 0.1 mol L-1 acetate buffer (pH 4) and 99.8% ethanol in an 8:2 ratio, using differential pulse voltammetry. At optimum working conditions, the current responses could be calibrated within a linear range of 5-50 µmol L-1, with sensitivities of 0.026 µA L µmol-1 for TCS and 0.018 µA L µmol-1 for CHX, quantification limit of 4.6 µmol L-1 for TCS and 5.8 µmol L-1 for CHX, and detection limit of 1.4 µmol L-1 for TCS and 1.8 µmol L-1 for CHX. A satisfactory precision, characterised by a relative standard deviation of 4%, was achieved. Negligible interference from accompanying substances allows the use of the calibration-curve method, while a statistically insignificant y‑intercept enables the application of the multiple standard-addition method. The validation performed by the analysis of a model sample, a toothpaste and a mouthwash provided results comparable to those obtained by reference reversed-phase HPLC with spectrophotometric detection and gas chromatography with mass spectrometry. The results were statistically comparable according to Horn's test, thus confirming the practical applicability of the developed voltammetric method in pharmaceutical safety control.