Then the sample were boiled for 30 minutes until a final volume was reached. The boiled sample solution were cooled and diluted with 20 ml of distill water, and 1 drop of phenolpthalein indicator solution were added to it. then the faint pink colour were neutralize with 5 ml of NaOH and distill water were added to the sample solution to make it up to 100 ml. 50 ml of the digested sample were measured and 1 drop of phenolphthalein and 8 ml of combined reagent were added to it and mixed. Then the absorbance and concentration of the sample solution were measured at 880 nm.