Development of electro solid-phase microextraction and application to methamphetamine analysis

A new electro solid-phase microextraction (El-SPME) technique using homemade pencil-lead fibers has been developed as an effective means of selective extraction of methamphetamine before analysis by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). The methamphetamine was extracted by use of a laboratory-made El-SPME cell with three electrodes-the pencil-lead SPME fiber, Ag/AgCl, and platinum as working, reference, and auxiliary electrodes, respectively. A negative potential was applied to the homemade pencil-lead fiber during extraction. Experimental conditions, for example type of pencil-lead fiber, conditions for modification of the Fiber, extraction time, applied potential, pH, and gas chromatographic conditions were optimized. Methamphetamine was identified by GC-MS. Screening of the extracted compounds showed that the proposed El-SPME technique is much more selective than direct SPME using a commercially available polyacrylate Fiber. Under the optimum conditions the calibration plot for the compound was linear in the range 50-3,200 ng mL(-1) and the detection limit was 34 ng mL(-1).