Document Detail

Chemical assay of urea for automated sensing in milk.
MedLine Citation:
PMID:  10509259     Owner:  NLM     Status:  MEDLINE    
Results of a new chemical assay for urea involving enzymatic hydrolysis to ammonium and carbonate and subsequent measurement of CO2 partial pressure are presented. The assay is simple to implement in an automated version, and the hardware used is not prone to fouling and damage by raw milk. The assay sensitivity at 24 degrees C is about 0.367 kPa per milligram per deciliter of urea N. The assay has no dependence on milk fat in the sample, and effects of milk proteins and lactose are slight (less than 2% change in sensitivity per change in w/v percent). Observed sensitivities to urea in spiked milk samples were not significantly different from each other or from standards in distilled water or 0.1 M phosphate-buffered saline. The standard error of the assay is about 0.3 mg/dl of urea N (0.1 mM) in standard solution, and about 1 mg/dl of urea N (0.3 mM) in milk in a range of 0 to 30 mg/dl of urea N (0 to 11 mM). The assay holds promise for use in an on-line sensor to measure milk urea N in the milking parlor.
D M Jenkins; M J Delwiche; E J Depeters; R H Bondurant
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, Non-P.H.S.    
Journal Detail:
Title:  Journal of dairy science     Volume:  82     ISSN:  0022-0302     ISO Abbreviation:  J. Dairy Sci.     Publication Date:  1999 Sep 
Date Detail:
Created Date:  1999-11-01     Completed Date:  1999-11-01     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  2985126R     Medline TA:  J Dairy Sci     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  1999-2004     Citation Subset:  IM    
Department of Biological and Agricultural Engineering, University of California at Davis 95616, USA.
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MeSH Terms
Carbon Dioxide / analysis
Carbonates / analysis
Drug Stability
Lactose / analysis
Lipids / analysis
Milk / chemistry*
Milk Proteins / analysis
Nitrogen / analysis
Partial Pressure
Quaternary Ammonium Compounds
Sensitivity and Specificity
Urea / analysis*
Reg. No./Substance:
0/Carbonates; 0/Lipids; 0/Milk Proteins; 0/Quaternary Ammonium Compounds; 124-38-9/Carbon Dioxide; 57-13-6/Urea; 63-42-3/Lactose; 7727-37-9/Nitrogen

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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