Study of multiple solid-phase microextraction combined off-line with high performance liquid chromatography Application in the analysis of pharmaceuticals in urine

Solid-phase microextraction (SPME) was applied to the extraction of five common pharmaceuticals: quinine, naproxen, haloperidol, ciprofloxacin and paclitaxel. SPME combined off-line with HPLC analysis was studied independently for each analyte. Polydimethylsiloxane and polyacrylate fibres were used for the direct immersion SPME from isotonic analyte solutions and spiked human urine samples. Analyte desorption occurred in HPLC autosampler inserts containing 200 (mu)L of methanol; next 80 (mu)L of the resulting solution were injected on the HPLC. Extraction optimisation involved parameters such as addition of salts, pH value and saturation time. The pharmaceuticals were assayed independently by multiple extraction from isotonic aqueous solutions and urine samples. A protocol of multiple SPME provided higher yields for the four of the five examined analytes. The results showed the potential of using multiple SPME (but also single SPME) combined off-line to HPLC in bio-pharmaceutical analysis.