In this work, a single-well electromembrane extraction (EME) device was developed based on a thin (100μm) and flat porous membrane of polypropylene supporting a liquid membrane. The new EME device was operated with a relatively large acceptor solution volume to promote a high recovery. Using this EME device, exhaustive extraction of the basic drugs quetiapine, citalopram, amitriptyline, methadone and sertraline was investigated from both acidified water samples and human plasma. The volume of acceptor solution, extraction time, and extraction voltage were found to be important factors for obtaining exhaustive extraction. 2-Nitrophenyl octyl ether was selected as the optimal organic solvent for the supported liquid membrane. From spiked acidified water samples (600μl), EME was carried out with 600μl of 20mM HCOOH as acceptor solution for 15min and with an extraction voltage of 250V. Under these conditions, extraction recoveries were in the range 89-112%. From human plasma samples (600μl), EME was carried out with 600μl of 20mM HCOOH as acceptor solution for 30min and with an extraction voltage of 300V. Under these conditions, extraction recoveries were in the range of 83-105%. When combined with LC-MS, the new EME device provided linearity in the range 10-1000ng/ml for all analytes (R(2)>0.990). The repeatability at low (10ng/ml), medium (100ng/ml), and high (1000ng/ml) concentration level for all five analytes were less than 10% (RSD). The limits of quantification (S/N=10) were found to be in the range 0.7-6.4ng/ml.

Abstract. The need for a high resolution chromatographic technique for analyzing compounds that are heavy, relatively polar, have low water solubility, and are not adequately separated by regular HPLC methods, has led to the development of a high temperature liquid chromatography system. The increased diffusion coefficients and reduced viscosity at higher temperatures resulted in high separation velocities and allowed long columns to be used. The HTLC system contained 70 cm columns and nonaqueous mobile phases. Packed capillary columns prevented radial temperature gradients which otherwise would reduce the efficiency. The capillary columns were packed with a reversed phase material (ODS) using supercritical carbon dioxide as the slurry fluid. A new method for preparing a ceramic frit inside the column was developed. The frit withstood pressures of at least 600 bar. The robustness of the columns in a nonaqueous environment with elevated temperature was tested and found satisfactory for 1.50 injections with a temperature program at each injection. Isothermal elution or temperature programming in the SO-150°C range reduced the analysis time significantly. Compounds which were completely retained at room temperature eluted with good peak shape at elevated temperature. o 1995 J o h n wiley & son\, Inc

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