Amperometric determination of the water content in acetone, butter and margarine using a wall-tube platinum microelectrode in a flow injection system

Amperometric determinations of the water content in acetone, butter and mar garine were performed using a wall-tube platinum microelectrode in combinat ion with a flow injection system. For the butter and margarine samples, ace tone containing small amounts of supporting electrolyte was used both as so lvent and mobile phase. Linear calibration curves for oxidation of water in acetone were obtained in the range 0.005-0.3% v/v and the limit of detecti on was determined as 0.003% v/v. The sizes of the currents and the linear r ange were found to be independent of the supporting electrolyte concentrati on in the range 1.0 X 10(-4)-2.0 X 10(-3) M, provided that the detection po tential was altered to ensure the attainment of steady state currents. The results also indicate that the methanol content in acetone can be determine d with the present flow injection system.