Multivariate determination of glucose in whole blood by attenuated total reflection infrared spectroscopy.

A spectral analysis of whole EDTA blood was undertaken by using attenuated total reflection and Fourier-transform infrared spectroscopy. The concentration of blood glucose was measured by an enzymatic method using glucose dehydrogenase and ranged between 40 and 290 mg/dL with an average concentration of 90.4 mg/dL. Multivariate calibration with the partial least-squares (PLS) algorithm was performed on spectral data between 1500 and 750 cm-1 showing a varying background from different unidentified interfering compounds. Cross validation was carried out for optimizing the PLS model. PRESS was 19.8 mg/dL, which was calculated on the basis of 127 standards, whereas the estimated standard deviation for the calibration fit was computed to be 11.9 mg/dL. Infrared spectroscopy can be used for monitoring glucose levels within the normal physiological range in a complex matrix like whole blood as an alternative to electrochemical sensors.

Multivariate calibration for assays in clinical chemistry using attenuated total reflection infrared spectra of human blood plasma.

A spectral analysis of human blood plasma was undertaken by use of a Fourier-transform infrared spectrometer with a circular attenuated total reflection cell. The concentrations of total protein, glucose, triglycerides, total cholesterol, urea, and uric acid were measured by chemical or enzymatic methods. For these constituents the partial least-squares (PLS) algorithm was used for a multivariate calibration including the infrared fingerprint region of the plasma spectra. Best results were achieved for total protein with an average prediction error (PRESS based on cross validation) of 2.1 g/L; other PRESS results were for glucose 22 mg/dL, triglycerides 33 mg/dL, cholesterol 31 mg/dL, urea 4.4 mg/dL, and uric acid 1.6 mg/dL.