Determination of tramadol hydrochloride in water samples by directly suspended droplet three-phase liquid phase microextraction with tetrathiocyanato cobalt(II) as the complexing agent using UV-spectroscopy

Abstract

Suspended droplet three-phase liquid microextraction is a relatively new sample preparation technique for analysis of drugs. In the current study, tramadol hydrochloride was determined using tetrathiocyanato cobalt(II), (NH4)2[Co(SCN)4], as the complexing agent. The maximum of absorption for the formed ternary complex between tramadol hydrochloride and tetrathiocyanato cobalt(II) was observed at 625 nm. In this method, the target compound was extracted from the aqueous phase (5 mL containing 5 μg/mL of sample, pH 11) into an organic phase and then back-extracted into a directly suspended droplet as acceptor phase (3 μL of 1.74 × 10–9 M tetrathiocyanato cobalt(II), pH 2.8). 1-Octanol was used as organic phase. Under the optimized conditions: extraction time 90 s, back-extraction time 8 min and stirring rate 750 rpm, the linear range, the relative standard deviation (RSD, n = 5) and the limit of detection for tramadol hydrochloride were found 0.5–8 μg/mL, 4.9% and 8 ng/mL (n = 5), respectively. Also, the tap water and surface water samples were successfully analyzed using the proposed method and the relative recoveries obtained from the spiked water samples were 98.2 and 97.6%, respectively.