Automated and manual direct methods for the determination of urea in blood or serum are described. These methods determine urea by the colored product formed when urea, in relatively weak acid solution, reacts with diacetyl monoxime in the presence of thiosemicarbazide and ferric ion. Results are compared with those obtained by urease conversion of urea to ammonia and measurement of the ammonia...

The use of a-isonitrosopropiophenone, CS& *CO * CNOH. CH3, as a reagent for the calorimetric determination of urea has been mentioned in a previous communication (1). The present report outlines a simple method for the calorimetric determination of urea in blood filtrates and urine by means of this reagent and compares the values obtained by this method with those given by the urease ((2), (3) ...

The use of a-isonitrosopropiophenone, CS& *CO * CNOH. CH3, as a reagent for the calorimetric determination of urea has been mentioned in a previous communication (1). The present report outlines a simple method for the calorimetric determination of urea in blood filtrates and urine by means of this reagent and compares the values obtained by this method with those given by the urease ((2), (3) ...

Urea is the major nitrogenous end product of protein metabolism in mammals. Here, we describe a quantitative, sensitive method for urea determination using a modified Jung reagent. This assay is specific for urea and is unaffected by ammonia, a common interferent in tissue and cell cultures. We demonstrate that this convenient colorimetric microplate-based, room temperature assay can be applied...

BACKGROUND A reference measurement procedure is needed to demonstrate the traceability of results of urea measurements in human serum. We developed a measurement procedure using the principle of isotope dilution gas chromatography/mass spectrometry. METHODS [(13)C,(15)N(2)]Urea as internal standard was added to a serum sample and equilibrated with endogenous nonlabeled urea. For the preparati...

Kinetic methods are described for determination of total, heat-stable, and urea-stable lactate dehydrogenase (EC 1.1.1.27) activity on the centrifugal analyzer. In the urea-stable method we present, 2.6 molar urea is used to differentiate lactate dehydrogenase originatingfrom heart and liver.This urea concentration, greater than that used by most other investigators, better differentiates betwe...