Near Infrared Spectrophotometric Determination of Individual Sugars in Aqueous Mixtures

Near infrared region (NIR) spectrophotometry was used to determine concentrations of glucose, fructose and sucrose in aqueous mixtures at 10, 25, and 40% total sugars. Calibration equations and predicted individual concentrations in each total sugar level are reported. The standard errors of prediction varied between 0.35 and 0.69 and confidence limits ranged from ± 0.7 to ± 1.1%. In developing a single equation for predicting individual sugars in solutions, suitable for use over a range of total sugar concentrations, spectral data needed correction for sample density differences. However, at total sugar concentrations above 25%, accompanying wavelength shifts were of sufficient magnitude that a satisfactory single equation could not be developed. Equations for predicting individual sugars in solutions ranging from 10–25% total sugar concentrations were developed. For higher values of total sugars, appropriate calibrations were necessary.