UREA DETERMINATION IN MILK USING FOURIER-TRANSFORM INFRARED-SPECTROSCOPY AND MULTIVARIATE CALIBRATION

Multivariate calibration of urea in milk, in the range from 10 to 80 m g/dl, with Fourier transform infrared spectroscopy is investigated on 900 single cow samples. Different data pretreatments, such as derivati ves, multiplicative scatter correction and normalization, are used. Th e accuracy on an independent test set (expressed as the Root Mean Squa re Error of Prediction) is down to 3.9 mg/dl depending on the pretreat ment. The existing fast method for urea analysis based on infrared fil ter instruments is also tested. The accuracy of this method is 5.5 mg/ dl, which suggests that more information provided by the Fourier trans form infrared spectra is needed to establish more accurate calibration s.