The electrochemical pretreatment of carbon electrodes through the oxidation and reduction of the electrode surface is a widely used procedure to improve electrode response; however, there still remain many unanswered questions about the nature of the pretreatment process.

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A rapid, simple, and completely automated method for the analysis of cocaine and its metabolites in urine has been developed. The method utilizes online solid-phase extraction (SPE) with liquid chromatographic separation and tandem mass spectrometric detection (MS-MS). An efficient online SPE procedure was developed using Hyspheretrade mark MM anion sorbent. A gradient chromatography method with a Gemini C6-Phenyl (50 x 3.00-mm i.d., 5 microm) column was used for the separation of all compounds. Detection was by positive ion mode electrospray ionization MS-MS. Multiple reaction monitoring (MRM) was used to enhance the selectivity and sensitivity of the method. Two MRM transitions were monitored for each analyte and one transition for each internal standard. Linearity was analyte-dependent but generally ranged from 7 to 1000 ng/mL. The limits of detection for the method ranged from 3 to 23 ng/mL and the limits of quantitation ranged from 7 to 69 ng/mL. Quality control (QC) samples were analyzed for each analyte in triplicate at 50, 200, and 800 ng/mL. The bias and precision were determined using a simple analysis of variance (ANOVA: single factor). The results demonstrated bias as < 5% and % precision as < 9% for all components at each QC level.