Determination of Uric Acid
Principle:
Uric acid in alkaline solution reduces phosphotungestate to tungesten blue. phosphotungestic acid is used as a deproteinizing and color reagent.
Normal value: Males: 2-7 mg/dl
Females: 2-6 mg/dl
Reagents:
Reagent I: deproteinizing and color reagent
Reagent II: uric acid standard
Additional reagent: sodium carbonate.
Sample preparation:
Serum or Plasma.
Deproteinization of the sample:
1- Pipette into centrifuge tubes 3 ml of reagent 1 + 0.3 ml serum or heparinized plasma.
2-Mix well, let stand for 10 minutes at room temperature and centrifuge.
Colour Reaction:
Carefully pour into dry test tubes.
Wave length: 680-710 nm.
Incubation temperature: 25°c.
Measurement: against blank.
Pipette into test tubes:
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Blank
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Standard
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Serum
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Distilled water
|
0.2 ml
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|
|
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Reagent I
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2ml
|
2 ml
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|
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Standard
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0.2 ml
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|
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Supernatant
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|
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2.2 ml
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|
Sodium carbonate
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1ml
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1ml
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1ml
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Mix vigorously, let to stand for 20 min. at 25 °C. Measure the absorbance of Sample and Standard against Blank.
Calculation:
Uric Acid concentration in mg% = A sample / A standard x 10
Interpretation:
Increased excretion of uric acid occurs in gout.
