Urea determination in milk by a differential pH technique

Luzzana, M.; Giardino, Raffaella

doi:10.1051/lait:1999221

Cited by 27 publications

(20 citation statements)

References 7 publications

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“…This value is within the 95% confidence limit. With an analysis method based on pH difference and with 0.85-1.50% variation coefficient, Luzzana and Giardino [8] found the repeatability of the MUN measurement better than that found in the present study.…”

Section: Trialcontrasting

confidence: 86%

“…In addition, milk urea level can be determined through IR spectrophotometric measurement, on the basis of the amount of light absorbed at a given wavelength. Furthermore, there is the standard method where measurement can be made on the basis of pH difference [7] and methods similar to the standard method [8] are used in milk urea nitrogen determination. There are also devices specially developed for milk urea nitrogen measurement.…”

Section: Introductionmentioning

confidence: 99%

“…Luzzana and Giardino [8] developed a method for measuring MUN on the basis of pH difference, determined the repeatability and recovery of the method as 0.85 and 99.4% respectively, and reported that the developed method is simple, accurate, fast and in harmony with the standard method. Wang et al [12] compared 3 separate methods by using Foss 4000, diacetyl monoxime and urea nitrogen kit, and reported that there were no difference among the results of MUN conducted on 50 samples of milk.…”

Section: Introductionmentioning

confidence: 99%

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Farklı Süt Üre Azotu Analiz Metotlarının Karşılaştırılması

İnal¹,

GÜRBÜZ²,

Çoşkun³

et al. 2015

Kafkas Univ Vet Fak Derg

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The objective of this study was to develop a reliable and cheap method to determine of milk urea nitrogen and compare some other instrumental methods. Two trials were conducted. In first trial, a milk urea nitrogen testing method was designed by modifying some methods developed for ammonia nitrogen testing method. Several studies were performed for the validation of method. By using standard solutions some applications such as determinability, recovery, repeatability, test of various analyzers and devices, limit of quantification were performed. Recovery of added urea averaged 99.38 %. In second trial, 105 individual milk samples from a dairy farm was analyzed for milk urea nitrogen by modified indophenol, infrared, and MiniFoodLab methods. The means of milk urea nitrogen obtained from three different methods were 23.87, 21.59, and 23.92 mg/dl, respectively. There was a positive correlation between modified indophenol and infrared methods. Keywords: Milk urea nitrogen, Enzymatic Assay Farklı Süt Üre Azotu Analiz Metotlarının Karşılaştırılması ÖzetBu çalışmanın amacı süt üre azotu tayini için ekonomik ve güvenilir bir metodu geliştirmek ve bazı metotlarla karşılaştırmaktı. İki deneme halinde yürütüldü. Birinci denemede süt üre azotu analizi, amonyak ve üre analizi için geliştirilmiş bazı metotlar modifiye edilerek geliştirildi ve yöntemin doğrulanması ile ilgili çeşitli analizler yapıldı. Bu kapsamda standart eriyikler kullanılarak tespit edilebilirliği, geri alınabilirliği, süt örneklerinin tekrarlanabilirliği, değişik ölçümcülerin ve cihazların test edilmesi, tayin sınırının belirlenmesi gibi uygulamalar yapıldı. İlave edilen ürenin geri kazanımı % 99.38 idi. İkinci denemede bir çiftlikten elde edilen 105 adet bireysel süt örneği modifiye indofenol yöntemi, IR ölçüm yöntemi, MiniFoodLab ölçüm yöntemi ile üre azotu bakımından analiz edildi. Bu üç yöntemle elde edilen analiz sonuçları sırasıyla 23.87, 21.59 ve 23.92 mg/dl idi. Modifiye indofenol yöntemi ile IR yöntemi arasında orta seviyede pozitif bir korelasyon tespit edildi.

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Section: Trialcontrasting

confidence: 86%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Farklı Süt Üre Azotu Analiz Metotlarının Karşılaştırılması

İnal¹,

GÜRBÜZ²,

Çoşkun³

et al. 2015

Kafkas Univ Vet Fak Derg

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“…Fat and protein in the sample must be removed. The purpose of the present work is to demonstrate that the differential pH technique [9], already in use in a great number of milk testing laboratories for urea determination [8], can also be used for lactose and lactulose determination in milk for its excellent repeatability and linearity without sample preparation procedures.…”

Section: Introductionmentioning

confidence: 99%

Milk lactose and lactulose determination by the differential pH technique

Luzzana

Agnellini

Cremonesi

et al. 2003

Lait

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-A differential pH technique for lactose and lactulose determination in milk samples (UHT, pasteurised, sterilised and fresh milk) is presented. With enzymatic reactions, causing a pH variation directly proportional to the lactose and lactulose contents in samples, in less than two and four minutes, respectively, the lactose and lactulose can be analysed without sample preparation procedures. The automatic methods are very simple, precise and accurate, with an excellent linearity for lactose (R 2 = 0.9999) and lactulose (R 2 = 0.9997) throughout the whole range of concentrations and good repeatability (the coefficient of variation was lower than 0.5%). With the optimised experimental conditions, a sensitivity of 0.1 mmol·L -1 lactulose was obtained.Lactose / lactulose / differential pH technique / milk / enzymatic assay Résumé -Détermination de la teneur en lactose et lactulose des échantillons de lait par la technique de pH-métrie différentielle. L'emploi de la pH-métrie différentielle pour doser le lactose et le lactulose dans des échantillons de lait (UHT, lait pasteurisé, lait stérilisé et lait cru) est proposé. Le lactose et le lactulose peuvent être dosés, en moins de deux et quatre minutes respectivement et sans traitement de l'échantillon, avec des réactions enzymatiques qui causent une variation du pH directement proportionnelle à la concentration des deux substrats dans les échantillons. Les méthodes sont automatisées et elles sont simples, précises et très exactes, avec une excellente linéarité pour le lactose (R 2 = 0,9999) et le lactulose (R 2 = 0,9997) dans toute la gamme de concentration et une très bonne répétabilité (coefficient de variation < 0,5 %). En optimisant toutes les conditions expérimentales, la méthode a obtenu une sensibilité de 0,1 mmol·L -1 pour le lactulose.Lactose / lactulose / pH-métrie différentielle / lait / essai enzymatique

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“…The technique measures differences in the order of 10 -3 units of pH using two micro glass electrodes of high sensitivity, reason why the study and definition of the system are essential for the standardization of new procedures. This technique has been used to measure substrates and enzymatic activities in biological systems with high precision and quickly (Compagnone et al 1995;Luzzana and Giardino, 1999;Gast and Pingoud, 2001;Luzzana et al 2001;Tagarelli et al 2004).…”

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confidence: 99%