Abstract: An infrared attenuation measuring system, for the quantitative determination of the concentration of one or more components in an aqueous fat-containing sample, such as milk, by an infrared attenuation technique. The system comprising a set of waveband-related parameters containing information enabling the system to calculate the concentrations substantially independent of the degree of homogenization of the fat-containing sample, and/or to determine the degree of homogenization of the sample. The parameter set contains parameters which are related to wavebands containing a high degree of information about the homogenization degree of the sample. This may be wavebands containing little information about the chemical components of the sample, and/or wavebands containing a substantial amount of information about the chemical components of the sample. The system is calibrated with aqueous fat-containing samples with different degrees of homogenization.

Abstract: The concentration of urea in a concentration range of 0-0.1% in a milk sample containing at least 1% fat, at least 1% dissolved lactose, and at least 1% protein, is determined with an accuracy better than 0.007%, expressed as Standard Error of Prediction, by an infrared attenuation measuring technique, by determining, on the sample, the attenuation in the region of infrared radiation from 1000 cm.sup.-1 (10.0 .mu.m) to 4000 cm.sup.-1 (2.50 .mu.m), at least one determination being made in a waveband in the region from 1000 cm.sup.-1 (10.0 .mu.m) to 1800 cm.sup.-1 (5.56 .mu.