Arrays of SnO2 nanorods as novel solid phase microextraction for trace analysis of antidepressant drugs in body fluids

The arrays of tin oxide nanorods-solid phase microextraction (ATN-SPME) fibre coupled with the high performance liquid chromatography (HPLC) method was developed for simultaneous determination of selective serotonin reuptake inhibitors (SSRI), Citalopram and Fluoxetine, in human urine and plasma samples. The variables of interest in the Direct-SPME (D-SPME) were extraction time, pH, ion strength or salt percentage and desorption time of analytes from the fibre. These factors were optimised by using a Box-Behnken design and the response surface equations were developed. The optimal experimental conditions obtained from this statistical evaluation included: the salt percentage (30%, w/v), NaOH volume (6.5 μl from a 1 M solution), extraction time (10 min) and desorption time (30 min) for drugs in the plasma sample and The salt percentage (30%, w/v), NaOH volume (100 μl from a 1 M solution), extraction time (18 min) and desorption time (23 min) for drugs in the urine sample. A satisfactory reproducibility for the extraction from urine and plasma samples (R.S.D. < 10%) was obtained. The linearity for urine and plasma ranged from 1 to 5 × 105 ng ml−1 with a detection limit of 0.2 ng ml−1 for Citalopram and 0.5 ng ml−1 for Fluoxetine, which covered the typical urinary concentrations obtained for Citalopram and Fluoxetine.