We must used in preparation of test solution a pharmaceuticalpreparation contain both BA and BPO so to do this we used expired lotion (Ben – oxide acne lotion) which is expired since august/2010 with stirring for 30 mint we mixed 2g of lotion (5g BPO/ 100g base) i.e.100 mg BPO using magnetic stirrer with 60 ml ether in stepper flask. Filter wash the flask and filter paper with ether, add to the filtrate, complete volume to 100 ml of ether in volumetric flask.