a combined liquid threephase microextraction and differential pulse voltammetric method for preconcentration and detection of ultratrace amounts of buprenorphine using a modified pencil electrode a combination of polytetrafluorethylene membranebased liquid threephase microextraction and voltammetry was used for the microseparation and determination of buprenorphine type of the organic solvent used ph levels of the donor and acceptor phases salt concentration extraction time stirring rate and electrochemical parameters as the essential factors affecting the liquid threephase microextraction of buprenorphine were investigated differential pulse voltammetry exhibited two linear dynamic ranges of 101090 pmol l1 and 0109 nmol l1011 mol l1 of buprenorphine and the detection limit was found to be as low as 06 pmol l1 of buprenorphine also the effects of a number of common substances potentially interfering with selectivity were studied the results indicate that the proposed method is highly selective and sensitive for buprenorphine detection in real samples such as human urine and plasma of both drugaddict and nonaddict human subjects