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

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