Analytical Sciences

Simultaneous Determination of Amoxicillin and Diclofenac in Pharmaceutical Formulations Using UV Spectral Data and the PLS Chemometric Method

Miguel A. CANTARELLI,* Roberto G. PELLERANO,* Eduardo J. MARCHEVSKY,* and Jose M. CAMIÑA**

*Instituto de Química de San Luis (INQUISAL), Universidad Nacional de San Luis, Chacabuco y Pedernera (5700) San Luis, Argentina
**Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Av. Rivadavia 1917 (C1033AAJ) Ciudad de Buenos Aires, Argentina

A new method for the simultaneous determination of amoxicillin trihydrate (AMT) and sodium diclofenac (DIC) in pharmaceutical formulations is proposed. The resolution of binary mixtures of these drugs has been accomplished by using partial least squares (PLS) regression analysis. The model was obtained from UV spectral data and validated by internal cross-validation; it was used to find the concentration of analytes in some commercial samples. The method was applied in the concentration ranges of 0 – 120.0 mg L⁻¹ for AMT and 0 – 16.0 mg L⁻¹ for DIC, allowing a rapid, accurate and precise simultaneous estimation of the concentration of both analytes of interest in the presence of small amounts of different, unmodelled, absorbing excipients, in spite of their important spectral overlapping. The accuracy, precision and figures of merit (FOM) for AMT and DIC were calculated. This new method proved to be useful for a fast and simultaneous determination of AMT and DIC in pharmaceutical formulations.

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