Electromembrane extraction of barbiturates using tributyl phosphate as an efficient supported liquid membrane.

In this fundamental work, tributyl phosphate (TBP) with zero hydrogen-bond acidity was for the first time discovered as an efficient supported liquid membrane (SLM) for EMEof acidic drugs (barbiturates) due to its high polarity-polarizability. This discovery indicated that strong dipole-dipole interaction induced by high polarity-polarizability played an important role for efficient EME of acidic drugs. In addition, three barbiturates were successfully extracted for the first time from human whole blood and urine samples by EME with recoveries up to 90%. Interestingly, efficient EME of barbiturates from biological samples required much lower extraction voltage than that from buffer samples. This was due to the significant contribution from LPME during the EME process, when EME was conducted from the samples with just partially ionized analytes. EME combined with HPLC-UV and LC-MS were validated using whole blood and urine, respectively. In all cases, the linearity (R2) was >0.99 within the reported linear range. Repeatability at three concentrations was satisfactory (<12%), and the limits of detection (LOD, S/N = 3) were in the ranges of 0.44-4.30 ng mL-1 and 0.14-0.69 μg mL-1 for EME-LC-MS and EME-HPLC-UV, respectively. Finally, the validated methods were successfully applied for the identification and quantification of barbiturates in whole blood and urine samples for a forensic case, indicating that EME could be used in routine toxicological analysis. Thus, we believe that EME has great potential as a green, efficient and alternative sample preparation method not only in the field of analytical chemistry but also in the fields of forensic science and clinical medicine.