Procedure:
-In Blood
Sample serum or plasma

The reagent usually must be prepared before use according to kits of the chemicals.

1.put 1 ml of working reagent in two test tubes.
2.put 100 µ of serum in one tube and read after exact 30 sec. abs1 at wave length 500 then wait for additional 2 minutes and read again abs2.
3.put 100 µ of standard in the other tube read after exact 30 sec. abs1 then wait for additional 2 minutes and read again abs2.

Calculation:

abs of sample (abs2 - abs1) / abs of standard (abs2 - abs1) * 2 = .......mg / dl

-In urine

the urine must be collected for 24 hrs. then take 1ml urine and put on it 49 ml water then take from the solution 100 µ and repeat as shown above                                                            

Calculation:

abs of sample / abs of standard * 100 = ....... mg / dl.

Normal values

in serum or plasma 0.6 - 1.4 mg / dl
in urine 1 - 1.5 mg / dl