UREA Berthelot
₵650.00
UREA Berthelot
Urease/Salycilate
Enzymatic colorimetric method
ENDPOINT
PRINCIPLE
Urea is hydrolyzed by urease into ammonia and carbon dioxide. The ammonia generated reacts with alkaline hypochlorite and sodium salicylate in presence of sodium nitroprusside as coupling agent to yield a green cromophore. The intensity of the color formed is proportional to the concentration of urea in the sample.
REAGENT COMPOSITION
R1 Enzyme reagent: Urease >500 U/mL. Stabilizers.
R2 Buffered chromogen: Phosphate buffer 20 mmol/L pH
6.9, EDTA 2 mmol/L, sodium salycilate 60 mmol/L,
sodium nitroprusside 3.4 mmol/L.
R3 Alkaline hypochlorite: Sodium hypochlorite 10 mmol/L,
NaOH 150 mmol/L.
CAL Urea standard: Urea 50 mg/dL (8.3 mmol/L)
Organic matrix based primary standard. Concentration
value is traceable to Standard Reference Material 909b.
STORAGE AND STABILITY
Store at 2-8ºC
REAGENT PREPARATION
Working reagent. Mix 1 volume of R1 + 24 volumes of R2. Stable
for 4 weeks at 2-8ºC and for 7 days at 15-25ºC.
SAMPLES
Serum or heparinized plasma free of hemolysis and urine (see
Notes). Other anticoagulants (ammonium heparinate or double
oxalate of potassium and ammonium ) must not be used.
Urea in serum, plasma or urine is stable 7 days at 2-8ºC. Freeze
for longer storage.
MATERIALS REQUIRED
- Photometer or colorimeter capable of measuring absorbances at 600 +/- 10 nm.
- Constant temperature incubator set at 37ºC.
- Cuvettes with 1-cm pathlength.
- Pipettes to measure reagent and samples.
UREA reagents per box
