Method of determining urea in milk
First Claim
1. A method for determining, with an accuracy better than 0.007%, expressed as Standard Error of Prediction, 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, by an infrared absorption measuring technique, said method comprising the steps of:
- (a) determining absorption in an infrared radiation waveband from 1000 cm-1 (10.0 μ
m) to 4000 cm-1 (2.50 μ
m) of the milk sample, wherein at least one determination is made in a waveband from 1000 cm-1 (10.0 μ
m) to 1800 cm-1 (5.56 μ
m) in which urea absorbs, wherein at least one determination is made in a waveband in which fat absorbs, wherein at least one determination is made in a waveband where lactose absorbs, and at least one determination is made in a waveband where protein absorbs;
(b) determining, on the basis of said absorption determinations and predetermined parameters established by multivariate calibration, a contribution from fat, lactose, and protein in said waveband where urea absorbs, and(c) quantitatively assessing the concentration of urea in the milk sample on the basis of the absorption in the waveband where urea absorbs and on the basis of the determined contribution from fat, lactose, and protein in said waveband.
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Accused Products
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-1 (10.0 μm) to 4000 cm-1 (2.50 μm), at least one determination being made in a waveband in the region from 1000 cm-1 (10.0 μm) to 1800 cm-1 (5.56 μm) in which urea absorbs, at least one other determination being made in a waveband in which fat absorbs, at least one further determination being made in a waveband where lactose absorbs, and at least one further determination being made in a waveband where protein absorbs; determining, on the basis of the thus determined attenuations and predetermined parameters established by multivariate calibration, the contribution from fat, lactose, and protein in the waveband where urea absorbs, and quantitatively assessing the concentration of urea in the sample on the basis of the absorption in the waveband where urea absorbs, and on the basis of the determined contribution from fat, lactose and protein in said waveband. The multivariate calibration may be performed by a Partial Least Squares algorithm, Principal Component Regression, Multiple Linear Regression, or Artificial Neural Network learning. Using the method according to the invention, compensation for the influence on the urea measurement may further be performed for one or several of the following components: citric acid, free fatty acids, antibiotics, phosphates, somatic cells, bacteria, preservatives and casein.
37 Citations
27 Claims
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1. A method for determining, with an accuracy better than 0.007%, expressed as Standard Error of Prediction, 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, by an infrared absorption measuring technique, said method comprising the steps of:
-
(a) determining absorption in an infrared radiation waveband from 1000 cm-1 (10.0 μ
m) to 4000 cm-1 (2.50 μ
m) of the milk sample, wherein at least one determination is made in a waveband from 1000 cm-1 (10.0 μ
m) to 1800 cm-1 (5.56 μ
m) in which urea absorbs, wherein at least one determination is made in a waveband in which fat absorbs, wherein at least one determination is made in a waveband where lactose absorbs, and at least one determination is made in a waveband where protein absorbs;(b) determining, on the basis of said absorption determinations and predetermined parameters established by multivariate calibration, a contribution from fat, lactose, and protein in said waveband where urea absorbs, and (c) quantitatively assessing the concentration of urea in the milk sample on the basis of the absorption in the waveband where urea absorbs and on the basis of the determined contribution from fat, lactose, and protein in said waveband. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27)
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Specification