HPLC and chemometric methods for the simultaneous determination of cyproheptadine hydrochloride, multivitamins, and sorbic acid

Three methods are presented for the simultaneous determination of cyproheptadine hydrochloride (CP), thiamine hydrochloride (B1), riboflavin-5-phosphate sodium dihydrate (B2), nicotinamide (B3), pyridoxine hydrochloride (B6), and sorbic acid (SO). The chromatographic method depends on a high performance liquid chromatographic (HPLC) separation on a reversed-phase, RP 18 column. Elution was carried out with 0.1% methanolic hexane sulphonic acid sodium salt (solvent A) and 0.01M phosphate buffer containing 0.1% hexane sulphonic acid sodium salt, adjusted to an apparent pH of 2.7 (solvent B). Gradient HPLC was used with the solvent ratio changed from 20:80 to 70:30 (over 9min), then to 80:20 (over 11min) for solvent A:B, respectively. Quantitation was achieved with UV detection at 220 and 288nm based on peak area. The other two chemometric methods applied were principal component regression (PCR) and partial least squares (PLS). These approaches were successfully applied to quantify each drug in the mixture using the information included in the UV absorption spectra of appropriate solutions in the range 250–290nm with the intervals Δλ=0.4nm at 100 wavelengths. The chemometric methods do not require any separation step. The three methods were successfully applied to a pharmaceutical formulation and the results were compared with each other.