Hostname: page-component-cd9895bd7-fscjk Total loading time: 0 Render date: 2024-12-17T03:27:06.407Z Has data issue: false hasContentIssue false
  • English
  • Français

A method for estimation of urea using ammonia electrode and its applicability to milk samples

Published online by Cambridge University Press:  22 July 2008

Rajan Sharma ,
Yudhishthir S Rajput ,
Sumandeep Kaur  and
Sudhir K Tomar
Rajan Sharma
Affiliation:
Department of Dairy Chemistry, National Dairy Research Institute, Karnal-132 001, India
Yudhishthir S Rajput*
Affiliation:
Department of Dairy Chemistry, National Dairy Research Institute, Karnal-132 001, India
Sumandeep Kaur
Affiliation:
Department of Dairy Chemistry, National Dairy Research Institute, Karnal-132 001, India
Sudhir K Tomar
Affiliation:
Department of Dairy Microbiology, National Dairy Research Institute, Karnal-132 001, India
*
*For correspondence; e-mail: [email protected]
Get access Rights & Permissions [Opens in a new window]

Abstract

A method for the estimation of urea in milk using ammonia electrode is described. Urea is first degraded by urease enzyme into ammonium ion and carbon dioxide at neutral pH. The ammonium ion is then converted into ammonia at alkaline pH. A linear inverse relationship was observed between logarithmic concentration of ammonia or urea and electrode response. Repeatability, expressed as a coefficient of variation, was 1·77% at a level of 8·92 mm-urea in milk. The method was validated in milk samples spiked with between 2×10−3 and 10×10−3 m-urea and recovery of added urea was quantitative. Whereas, preservative sodium azide at 0·5 g/l or 2 g/l level did not affect results, lower values of urea concentration in presence of Bronopol at 0·5 g/l were observed. Urea levels in milk samples estimated by this method were comparable to standard enzymatic method. The method is simple, fast and is not prone to interference from other milk constituents.

Keywords

UreaMilkAmmonia electrodeUreaseAmmonia
Type
Research Article
Information
Journal of Dairy Research , Volume 75 , Issue 4 , November 2008 , pp. 466 - 470
Copyright
Copyright © Proprietors of Journal of Dairy Research 2008

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Bansal, P & Bansal, N 1997 Synthetic milk – genesis, current status and options. Current Science 23 904–905Google Scholar
Bector, BS, Moti, R & Singhal, OP 1998 Rapid platform test for the detection/determination of added urea in milk. Indian Dairyman 50 59–62Google Scholar
Bhavadasan, MK, Rajput, YS & Ganguli, NC 1982 A simple colorimetric method for the determination of urea in milk. Indian Journal of Dairy Science 35 263–266Google Scholar
Broderick, GA & Clayton, MK 1997 A statistical evaluation of animal and nutritional factors influencing concentrations of milk urea nitrogen. Journal of Dairy Science 80 2964–2971CrossRefGoogle ScholarPubMed
Butler, WR, Calaman, JJ & Beam, SW 1996 Plasma and milk urea nitrogen in relation to pregnancy rate in lactating dairy cows. Journal of Animal Science 74 858–865CrossRefGoogle Scholar
Godden, SM, Lissemore, KD, Kelton, DF, Leslie, KE, Walton, JS & Lumsden, JH 2001 Relationship between milk urea concentrations and nutritional, management, production and economic variables in Ontario dairy herds. Journal of Dairy Science 84 1128–1139CrossRefGoogle ScholarPubMed
Guilbault, GG & Kauffmann, JM 1987 Enzyme based electrodes as analytical tools. Biotechnology and Applied Biochemistry 9 95–113Google Scholar
Hansen, PW 1998 Urea determination in milk using Fourier transform infrared spectroscopy and multivariate calibration. Milchwissenschaft 53 251–255Google Scholar
Holf, G, Vervoorn, MD, Lenaers, PJ & Tamminga, S 1997 Milk urea nitrogen as a tool to monitor the protein nutrition of dairy cows. Journal of Dairy Science 80 3333–3340Google Scholar
Hojman, D, Gips, M & Ezra, E 2005 Association between live body weights and milk urea concentration in Holstein cows. Journal of Dairy Science 88 580–584CrossRefGoogle ScholarPubMed
International Dairy Federation 2004 Milk determination of urea content. Enzymatic method using differential pH (Reference method). Standard method 195. Brussels, Belgium: International Dairy FederationGoogle Scholar
Jenkins, DM, Delwiche, MJ, Depeters, EJ & Bon Durant, RH 1999 Chemical Assay of Urea for automated sensing in milk. Journal of Dairy Science 82 1999–2004CrossRefGoogle ScholarPubMed
Jenkins, DM, Delwiche, MJ, Depeters, EJ & Bon Durant, RH 2000 Refinement of the pressure assay for milk urea nitrogen. Journal of Dairy Science 83 2042–2048CrossRefGoogle ScholarPubMed
Kampl, BK, Milas, NP, Francetic, & Srebocan, E 1993 Determination of the urea content in the deproteinized cow's skim milk by the urease/glutamate dehydrogenase method. Veterinarski Arhiv 63 55–60Google Scholar
Kavitha, P, Bector, BS & Sharma, V 2001a Urea content of cow milk in relation to milk yield and breed. Indian Journal of Dairy Science 54 311–315Google Scholar
Kavitha, P, Bector, BS & Sharma, V 2001b Urea content of milk of Murrah breed of buffaloes. Buffalo Newsletter 16 10–12Google Scholar
Larson, SF, Butler, WR & Currie, WB 1997 Reduced fertility associated with low progesterone postbreeding and increased milk urea nitrogen in lactating dairy cows. Journal of Dairy Science 50 1288–1295Google Scholar
Lefier, D 1996 Analytical methods for the determination of the urea content in milk. Bulletin of the International Dairy Federation 315 35–38Google Scholar
Luzzana, M & Giardino, R 1999 Urea determination in milk by a differential pH technique. Lait 79 261–267CrossRefGoogle Scholar
Medndham, J, Denney, RC, Barnes, JD & Thomas, MJK 2000 Vogels's textbook of quantitative chemical analysis. Sixth Edition. Pearson Education (Singapore) Pte. Ltd., New Delhi, IndiaGoogle Scholar
Paradkar, M, Singhal, RS & Kulkarni, PR 2000 An approach to the detection of synthetic milk in dairy milk: 1. Detection of urea. International Dairy Journal 53 87–91Google Scholar
Rajput, YS, Bhavadasan, MK, Singh, A & Ganguli, NC 1982 Heat stability of buffalo milk as affected by the addition of urea and glyceraldehyde. New Zealand Journal of Dairy Science & Technology 17 185–190Google Scholar
Rajput, YS, Bhavadasan, MK & Ganguli, NC 1984 Effect of urea on heat-induced acidity and milk coagulation. New Zealand Journal of Dairy Science & Technology 19 49–54Google Scholar
Ramakrishnaiah, & Bhat, GS 1986 Significance of urea level in heat stability of cow and buffalo milk. Indian Journal of Dairy Science 39 60–64Google Scholar
Verma, N & Singh, M 2003 A disposable microbial based biosensor for quality control in milk. Biosensors and Bioelectronics 18 1219–1224CrossRefGoogle ScholarPubMed
Wolfschoon-Pombo, A, Klostermeyer, H, Buchberger, J & Graml, R 1981 Urea in the NPN-fraction of cows' milk – determination, content and influences. Milchwissenschaft 36 462–466Google Scholar