In this method different concentrations of essential oil (2.0,1.0,0.5,0.25 and 0.125 mg/ml) were taken in different tubes and volume of all the working solutions is made upto 1ml by adding distilled water, in these added 2.5 ml Phosphate buffer (0.2M,pH-6.6)and 2.5 ml of potassiumferricyanide (1%)