Qualitative and quantitative analysis of oxytetracycline by near-infrared spectroscopy

Near-infrared (NIR) spectroscopy, in combination with chemometrics, enable the analysis of raw materials without time-consuming sample preparation met hods. The aim of our work was to estimate critical parameters in the analyt ical specification of oxytetracycline, and consequently the development of a method for quantification and qualification of these parameters by MR spe ctroscopy. A Karl Fischer (K.F.) titration to determine the water content, a colorimetric assay method, and Fourier transform-infrared (FT-IR) spectro scopy to identify the oxytetracycline base, were used as reference methods, respectively. Multivariate calibration was performed on MR spectral data u sing principal component analysis (PCA), partial least-squares (PLS 1) and principal component regression (PCR) chemometric methods. Multivariate cali bration models for MR spectroscopy have been developed. Using PCA and the S oft Independent Modelling of Class Analogy (SIMCA) approach, we established the cluster model for the determination of sample identity. PLS 1 and PCR regression methods were applied to develop the calibration models for the d etermination of water content and the assay of the oxytetracycline base. Co mparing the PLS and PCR regression methods we found out that the PLS is bet ter established by MR, especially as the spectroscopic data (NIR spectral a re highly collinear and there are many wavelengths due to non-selective wav elengths. The calibration models for MR spectroscopy are convenient alterna tives to the colorimetric method and to the K.F. method, as well as to FT-I R spectroscopy, in the routine control of incoming material. (C) 2000 Elsev ier Science B.V. All rights reserved.