High performance liquid chromatographic determination of some guaiphenesin-containing cough-cold preparations

This paper presents different HPLC methods for the simultaneous determination of some guaiphenesin-containing cough-cold preparations. Three pharmaceutically available combinations were analyzed: salbutamol sulfate (SAL) and guaiphenesin (GUA), combination I; ascorbic acid (ASC), paracetamol (PAR) and guaiphenesin (GUA), combination II; and theophylline anhydrous (THE), guaiphenesin (GUA) and ambroxol hydrochloride (AMB), combination III. A 250 × 4.6 mm C-18 column was used for all combinations. The mobile phase for the three combinations consisted of a mixture of methanol and 0.01 M aqueous phosphate buffer solution. The pH of the mobile phase was adjusted to 3.2, 6.2 and 3.8 for combinations I, II and III, respectively. The proposed HPLC methods were successfully applied to the determination of the investigated drugs, both in synthetic mixtures and in pharmaceutical preparations, without any matrix interference and with high precision and accuracy. Different aspects of analytical validation are presented in the text.