Quantitative analysis of sugar mixtures in solution is important in the soft drinks and brewing industries. Existing infrared sampling methods based on attenuated total reflectance (ATR) generally use crystal materials that do not have direct contact approval in food process environments. Sapphire is an attractive alternative, being hard, inert, and nontoxic. This work discloses a novel sapphire ATR crystal, built into a stainless steel-housed fiber-optic probe, suitable for use in a food production environment. The probe has been used to perform quantitative analysis of sucrose, glucose, and fructose mixtures in solutions, with the use of principal components regression (PCR) as the calibration method, and internal cross-validation to assess the predictive ability. Good prediction results were obtained.
E. K. Kemsley, R. H. Wilson, G. Poulter, and L. L. Day, "Quantitative Analysis of Sugar Solutions Using a Novel Fiber-Optic-Based Sapphire ATR Accessory," Appl. Spectrosc. 47, 1651-1654 (1993)