A combined liquid three-phase micro-extraction and differential pulse voltammetric method for preconcentration and detection of ultra-trace amounts of buprenorphine using a modified pencil electrode

A combination of polytetrafluorethylene membrane-based liquid three-phase micro-extraction and voltammetry was used for the micro-separation 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 three-phase micro-extraction of buprenorphine were investigated. Differential pulse voltammetry exhibited two linear dynamic ranges of 1.0–109.0 pmol L−1 and 0.109 nmol L−1–0.11 µmol L−1 of buprenorphine and the detection limit was found to be as low as 0.6 pmol L−1 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 drug-addict and non-addict human subjects.