MULTICOMPONENT ASSAY FOR BLOOD SUBSTRATES IN HUMAN PLASMA BY MIDINFRARED SPECTROSCOPY AND ITS EVALUATION FOR CLINICAL ANALYSIS

An analytical multicomponent method for the blood substrates total protein, glucose, total cholesterol, triglycerides, and urea in human EDTA plasma by FT-IR spectroscopy is described. The spectra were obtained with the use of the attenuated total reflection technique. Partial least-squares was applied for multivariate calibration over optimized spectral ranges. The mean-square prediction errors for the population of 126 plasma samples of different patients calculated by cross-validation are in the range of clinical acceptance. Within an error variance analysis, the contributions of the reference method and the spectrometric measurement to the average (root mean square) prediction error have been estimated for each substrate, giving evidence of the limitations of the spectrometric method. The problem of the biocompatibility of the plasma has been investigated, and the protein adsorption onto the ATR crystal can be reduced to a constant and tolerable level by appropriate cleaning and rinsing. The potential for further improvement is discussed.