Inside gel electromembrane extraction: A novel green methodology for the extraction of morphine and codeine from human biological fluids.

In this work, a new mode of gel-electromembrane extraction (G-EME), called "inside" gel-EME (IG-EME) is proposed for the extraction of morphine and codeine as model basic drugs from complex biological samples. Here, an aqueous media that was captured inside the agarose gel membrane, acted as both gel membrane and the acceptor phase (AP) at the same time. In this regard, the membrane served as the separation filter (membrane) and supported liquid acceptor phase (SLAP) as well. With this new development, unwanted changes of the AP volume during the extraction, which is a common issue in the G-EME (due to electroendosmosis (EEO) phenomenon), was addressed properly. Briefly, the setup involved insertion of negative electrode inside the gel membrane and positive electrode into the donor phase (DP). Following that, the IG-EME was easily performed using optimal conditions (pH of the DP: 6.0; membrane composition (agarose concentration: 1% (w/v) in aqueous media with pH 3.0, and 15 mm thickness); voltage: 25 V; and extraction time: 30 min). After extraction, the agarose gel was withdrawn and centrifuged for 5 min with 12000 rpm, to disrupt its framework to release the "trapped aqueous AP" apart from the gel structure. The separated AP was finally injected into the HPLC-UV for the analysis. The limits of detection (LODs) and recoveries in this proposed method were obtained 1.5 ng mL-1 and 67.7 %-73.8 %, respectively. The system feasibility was examined by the quantification of model drugs in the real plasma and urine samples.