2.2. This was prepared by using a ratio of 1:1:1 of 0.04 M boric acid, 0.04 M phosphoric
acid and 0.04 M acetic acid, and the pH was adjusted by using
0.2 M sodium hydroxide solution. Serial dilutions were prepared
by adding known aliquots from the stock solution, followed by
5 ml of Britton Robinson buffer, then 1 ml of potassium chloride
solution and finally 0.2 ml of palladium (II) chloride solution. The
volume was then diluted to 10 ml by addition of distilled water.
The mixture was mixed well then left to stand for at least
10 min. The absorbance was then measured spectrophotometrically
at the predetermined kmax 250 nm against a reagent blank.
All measurements were done at a temperature of 25 ± 1 C. Base
line correction was carried out to delete any absorbance reading
of the blank. The assay method was validated.