Determinação simultânea de ácido clavulânico e amoxicilina em formulações farmacêuticas utilizando técnicas de reflexão no infravermelho médio e métodos de regressão multivariados

Abstract

Clavulanic acid (AC) and amoxicillin (AMO) drugs are used in association and they are commercialized in Brazil as antibiotic agent. The simultaneous determination of these drugs is, usually, carried out by high performance liquid chromatography (HPLC). In the present study a methodology for simultaneous determination of AC and AMO was developed using Fourier transform mid infrared technique coupled with attenuated total reflectance (FTIR/ATR) and diffuse reflectance (DRIFTS). Nineteen commercial samples and 17 synthetic samples (28 samples for calibration set and 8 samples for prevision set) were used. Calibration models were developed using partial least squares (PLS) and interval partial least squares (iPLS), synergy partial least squares (siPLS) and backward interval partial least squares (biPLS) were used as variable selection methods. Multiplicative scatter correction (MSC) and the data centered in the media produced the best models. A relative standard error of prediction (RSEP) of 3.58% (root mean square error of prediction RMSEP = 6.17 mg g-1) for AC and RSEP of 5.12% (RMSEP = 33.58 mg g-1) for AMO was obtained after interval selection using biPLS algorithm for FTIR/ATR. For DRIFTS 4.98% (RMSEP = 8.44 mg g-1) and 4.75% (RMSEP = 23.31 mg g-1) RSEP values were obtained for AC and AMO, respectively, after selection of better intervals by siPLS. Results obtained by the proposed methodology were compared with those using the methodology by HPLC and no significant differences were obtained. Therefore, results using FTIR/ATR and DRIFTS techniques combined to multivariate analysis methods were suitable for the simultaneous determination of AC and AMO in commercial pharmaceuticals products.