acetone for 5 min and combining the filtrates in a separating funnel.to the combined filtrates 75 ml petroleum ether was added and the organic phase was washed three time with 50 ml water.remaining water was removed with anhydrous sodium sulphate and the volume was made uo to 100 ml with petroleum ether. The optical of the layer was measured with a spectrophotometer at 450 and 503 nm using petro ether as a blank the concentrations of