Application of Molecular Spectroscopy in the Mid-Infrared Region to the Determination of Glucose and Cholesterol in Whole Blood and in Blood Serum

The feasibility of applying molecular spectroscopy in the mid-infrared region to the quantitation of glucose and cholesterol in whole blood and in blood serum was examined by measuring the samples in the dry state on a polyethylene carrier. The partial least-squares (PLS) algorithm was employed to set up the calibration models. Analysis was performed by normalizing the spectra to a standard area. Evidence that this approach is warranted was obtained through experiments where potassium thiocyanate served as the internal standard. The following average PRESS1/2 values (PRESS stands for prediction residual error sum of squares) emerged from the calibration: glucose, 22.3 mg/dL; cholesterol, 31.3 mg/dL. Such errors are comparable with those achieved in attenuated total reflectance (ATR) measurements. The calibration models set up for blood serum samples fit better than those for whole blood samples. If the procedure of sample application onto the carrier is improved, the method may work well for the determination of glucose and cholesterol in whole blood and in blood serum.