Derivative spectrophotometric and liquid chromatographic methods for the simultaneous determination of metoclopramide hydrochloride and aspirin in pharmaceuticals.

Two simple analytical methods were developed and validated for the analysis of a binary mixture of metoclopramide (MET) and aspirin (ASP). The first method depends on measuring the first derivative amplitudes at 257 nm for MET and at 310 nm for ASP, respectively. The calibration graphs were linear in the range of 0.25-20.0 µg/mL for MET and 10.0-200.0 µg/mL for ASP. For the second method, good chromatographic separation was achieved using Promosil C18 column (250 × 4.6 mm i.d., 5 µm particle size). Mobile phase consisting of methanol and 0.02 M phosphate buffer in the ratio of 60:40 (v/v) at pH 4.0 was pumped at a flow rate of 1 mL/min with UV detection at 260 nm. Indapamide was used as an internal standard. The method showed good linearity over the concentration ranges of 0.20-10.0 and 10.0-200.0 μg/mL with limits of detection of 0.06, 1.81 μg/mL and limits of quantification of 0.17, 5.46 μg/mL for MET and ASP, respectively. The results of the proposed methods were statistically compared with those obtained by the official United States Pharmacopeia method revealing non-significant differences in the performance of the methods regarding accuracy and precision. The suggested methods were successfully applied for the simultaneous analysis of the studied drugs in their co-formulated tablets as well as in their single dosage forms.