Gel electromembrane extraction using rotating electrode: A new strategy for mass transfer enhancement of basic drugs from real human urine samples

This study proposed a new method of EME based on agarose gel named rotating electrode gel electromembrane extraction (RE-G-EME) for extraction and determination of naloxone, naltrexone, and nalbuphine as basic drugs from real human urine samples. In this new method, a rotating electrode connected to the armature was used to agitate the acceptor phase (AP). With this new development, the extraction efficiency enhanced due to increasing analytes mass transfer from gel membrane interface toward the AP. The effective parameters on the extraction efficiency were optimized and the maximum recoveries of the analytes were obtained under the optimal extraction conditions (3.0% (w/v) agarose with pH 5.0 as gel membrane; voltage: 25 V; pH of the donor phase (DP): 6.0; pH of the AP: 4.0; stirring rate of the DP: 750 rpm; electrode rotation speed within AP: 125 rpm; extraction time: 25 min). The method offered limits of detection (LODs) and extraction recoveries in the range of 0.3-1.5 ng mL(-1), and 74.3% - 87.0%, respectively. Also, the repeatability of the proposed method was measured for four repeated experiments and was in the acceptable range of 4.3% - 8.1%. To understand the influence of agitation of the AP on the extraction efficiency, a comparative study was carried out between conventional G-EME and RE-G-EME methods. The results showed that, for short the extraction times (t < 10 min), extraction efficiency of G-EME was almost the same as that of RE-G-EME. However, at longer extraction times (25 min), the extraction efficiency of RE-G-EME was significantly higher than that of G-EME. Finally, the proposed method was successfully applied to determine concentrations of model drugs in real urine samples with relative recoveries of 81.1-96.1% indicating good reliability of the proposed method.