SIMPLE PARTIAL LEAST SQUARES-ATTENUATED TOTAL REFLECTANCE FOURIER-TRANSFORM INFRARED SPECTROMETRIC METHOD FOR THE DETERMINATION OF SUGARS IN FRUIT JUICES AND SOFT DRINKS USING AQUEOUS STANDARDS

A simple analytical procedure was developed for the direct determinati on of sugars in fruit juices (apple, orange, grape) and soft drinks. T he method is based on the partial least squares treatment of attenuate d total reflectance Fourier transform infrared spectrometric data obta ined in the wavenumber range 4000-700 cm(-1) and does not require any sample pre-treatment, Absorbance and first-derivative spectra were emp loyed for measurements, using a reduced set of eight aqueous standard mixtures of glucose, fructose and sucrose at two concentration levels for calibration, The limits of detection found for absorbance measurem ents were 0.2 g per 100 ml for total sugar and 0.1, 0.1 and 0.03 g per 100 ml for glucose, fructose and sucrose, respectively, Relative stan dard deviations varied from 1.7 to 2.0% for six independent measuremen ts of individual and total sugar concentration, In the analysis of rea l and synthetic samples, precise and accurate results were obtained, p roviding accuracy errors lower than 2% in all cases, Average recoverie s of 96 +/- 4% for total sugar and between 93 +/- 7 and 99 +/- 7% for single sugars demonstrate the applicability of the methodology develop ed to the direct analysis of fruit juice and soft drink samples.