A novel approach based on capillary electrophoresis coupled to augmented multivariate curve resolution-alternating least-squares modeling for the determination of pKa of 2-hydroxy-4,6-dimethylpyrimidine in nicarbazin

Abstract

The determination of the dissociation constant of 2-hydroxy-4,6-dimethylpyrimidine in nicarbazin was carried out by means of capillary electrophoresis using a dynamic coating of a fused-silica capillary with high-molecular-mass poly(diallyldimethylammonium chloride) (PDDA) implementing two methods: (a) fitting the effective mobility determined from different electrophoretic runs at a single wavelength as a function of pH and (b) a novel modeling strategy of the spectrophotometric second-order data generated with the diode array detector at several wavelengths as a function of pH. The accuracy of the proposed methodologies was verified using robenidine as a model compound with known value of pKa.