Pw. Hansen, UREA DETERMINATION IN MILK USING FOURIER-TRANSFORM INFRARED-SPECTROSCOPY AND MULTIVARIATE CALIBRATION, Milchwissenschaft, 53(5), 1998, pp. 251-255
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.