Electromembrane extraction of basic drugs from untreated human plasma and whole blood under physiological pH conditions

The present work describes the first systematic study of electromembrane extraction (EME) from biological matrices under physiological conditions. Six basic drugs with protein binding in the range of 20-97% were extracted from untreated human plasma and whole blood through a supported liquid membrane (SLM) consisting of 1-ethyl-2-nitrobenzene impregnated in the walls of a hollow fiber, and into an acidified aqueous solution inside the lumen of the fiber. The electrical potential difference over the membrane reduced the protein binding of the drugs and transported the free drug fraction over the membrane. Recoveries in the range 25-65% were obtained with 10-min extraction time and an applied voltage of only 10 Vover the SLM. Interday precision better than 20% RSD and linearity in the range 0.5-10 mu g/mL were obtained for nortriptyline and methadone. Extraction from untreated whole blood was also demonstrated with recoveries in the range 19-51%.