Measurement of the Concentrations of Glucose and Citric Acid in the Aqueous Solution of a Blood Anticoagulant Using near Infrared Spectroscopy

Near infrared (NIR) spectroscopy was employed for the simultaneous prediction of the concentrations of glucose and citric acid in the aqueous solution of a blood anticoagulant solution. The solution was placed in an NIR spectrophotometer and the absorbance at wavelengths between 400 and 2500 nm was measured at 2 nm intervals. Multiple linear regression (MLR) was used to obtain calibration equations relating the NIR spectral data and the glucose and citric acid concentrations of a calibration sample set obtained by enzymatic methods. The value of the multiple correlation coefficient (R) was 0.993 when using the wavelengths of 2274 and 1674 nm for glucose. The value of the simple correlation coefficient (r) for citric acid was 0.993 when using the wavelength 1690 nm. To validate the calibration equations obtained, glucose and citric acid concentrations in a prediction sample set were compared with the concentrations measured by the enzymatic methods. Excellent agreement between the results of the enzymatic method and those of NIR spectroscopy was observed for both constituents. The procedure of NIR spectroscopy was simple and the operation time required to predict the concentrations was a few minutes. These results indicate that NIR spectroscopy may be a useful method for monitoring the production process of the blood anticoagulant.