**2.11.2 Technique**

2mls of buffer substrate was measured into each of the 2 test tubes and placed in water bath at 370C for a few minutes. To one of the test tube (patients' test tube) was added 0.lml of serum and the tubes were incubated for exactly 15 minutes. They were removed from the bath and 0.8ml of 0.5M sodium hydroxide and 1.2ml of 0.5M (the blank) was added to both tubes, 1ml of amino- antipyrine reagent and 1ml of potassium ferricyanide were added. For the standard, 1ml of buffer and 1ml of phenol standard containing 0.01mg of phenol was taken. For the standard blank, 1.1ml of buffer and 1ml of water was taken to both tubes, and then sodium hydroxide, bicarbonate amino-antipyrine and ferricyanide was added as above. It was read with a spectrophotometer set at 520 millimicrons. Serum alkaline phosphatase (King- Amstrong unit per 100mls) was derived from the formula:

Serum alkaline phosphatase = Reading of unknown - Reading of blank x 10

Reading of standard - Reading of standard blank

Total serum alkaline phosphatase values of 25-95 IU/L was taken as normal
