Simultaneous determination of citalopram, fluoxetine and their main metabolites in human urine samples by solid-phase microextraction coupled with high-performance liquid chromatography

A liquid chromatography method was developed for the determination of some frequently prescribed selective serotonin re-uptake inhibitors (SSRI) – citalopram and fluoxetine – and its main metabolites – demethylcitalopram, didemethylcitalopram and norfluoxetine – in human urine samples, using a previous stage of solid-phase microextraction. All the extraction parameters influencing adsorption (extraction time, temperature, pH, ion strength and organic modifier addition) and desorption (desorption time and desorption solvent mixture composition) of the analytes on the fiber have been studied. A satisfactory reproducibility for extraction from urine samples (R.S.D. < 10%) was obtained. The linearity for urine ranged from 0.05 to 2 mg l−1 with limits of detection close to 0.01 mg l−1, which cover the typical urinary concentrations obtained for citalopram, fluoxetine and their metabolites.