MULTIVARIATE DETERMINATION OF SUGAR POWDERS BY ATTENUATED TOTAL REFLECTANCE INFRARED-SPECTROSCOPY

Thanks to what has been achieved by Fourier transformation, infrared analysis can now become a state-of-the-art device in quality control laboratories if we consider its precision and the gain in time it ensures. Moreover, an increasing number of new mathematical regression methods such as partial least-squares (PLS) regression allow multicomponent quantitative analysis in mixtures. Nevertheless, the efficiency of infrared spectrometry as a quantitative analytical method often depends on the choice of an adequate presentation for the sample. For quantitative analysis of powders, sampling appears difficult in the mid-IR. We have developed a method built on three advantages: the rapidity of Fourier transform spectroscopy, fast solvent elimination, and good peak resolution. For enhancing peak intensity on attenuated total reflectance (ATR) spectroscopy we use nondissolving and evaporating liquids. For instance, the analysis of three components (glucose, fructose, and sucrose) can be done with a precision in the range of 4%, whereas the time required to obtain an analysis report is about 5 min.