Estimation of Creatinine

METHOD OF ESTIMATION - ALKALINE PICRATE METHOD

  • Alkaline picrate method is used to estimate the creatinine concentration in serum. But it measures some non-creatinine chromogens present in plasma. It can be rectified by using Lloyd’s reagent, which measures only the true creatinine.

Principle

  • Creatinine reacts with the picric acid to produce a colored compound, creatinine alkaline picrate. The change in absorbance is proportional to creatinine concentration.

Reagents composition

  • Creatinine dye reagent
    • Picric acid - 8.73 mmol/L
    • Surfactant
  • Creatinine base reagent
    • Sodium hydroxide - 300 mmol/L
    • Sodium phosphate - 25 mmol/Lab

Laboratory procedure

Standard
Sample
Working reagent
1000 µL
1000 µL
Standard
100 µL
-
Sample
-
100 µL
Mix and read the optical density (T1) 6 seconds after the sample or standard addition. Exactly after 6 seconds after the first reading take second reading (T2).

Caculation

Creatinine conc. (mg/dL) = ( T2 – T1) of sample) / (T2 – T1) of   standard ) X 2  
Last modified: Monday, 4 June 2012, 7:19 AM