IR spectrophotometric measurement of glucose in phosphate buffered saline solutions: effects of temperature and pH

The feasibility of accurate prediction of physiological glucose concentration in phosphate buffered saline (PBS) solutions with a pH of 7.4, maintained at 37 degrees C, was demonstrated by applying univariate and multivariate statistical methods to their mid-infrared spectra (1500-800 cm^-1). Multivariate methods, partial least squares, and principal components regression produced calibration models with smaller standard errors of estimation (SEE) (10.4 and 10.2 mg/dl, respectively) compared with peak height and area based univariate methods (smallest SEE=15 mg/dl). The effects of temperature and pH changes on the variation of PBS and glucose spectrum were observed. Preliminary studies indicate that multivariate analysis methods should be used to accurately predict glucose concentration in aqueous mixtures like blood since the infrared spectra are affected by variations in physiological conditions such as temperature and pH.