Chiang Mai Journal of Science

A microextraction technique based on vortex-assisted liquid-liquid microextraction with back extraction (VALLME-BE) combined with high-performance liquid chromatography-UV-Vis detector (HPLC-UV) was successfully developed for extraction and preconcentration of nonsteroidal anti-inflammatory drugs (NSAIDs). The procedure was carried out by adding butyl acetate into the working standard for VALLME step, followed by the back-extraction into sodium hydroxide for further preconcentration and clean-up. Under optimum conditions (NSAIDs concentration; 0.5 μg L−1; volume of sample; 10 mL; pH 3; volume of butyl acetate; 225 μL; vortex time; 105 s; 2250 rpm; back extraction; 20 μL NaOH (0.05 M); vortex speed; 2250 rpm; 60 s). The proposed technique provided good linearity (R2 ≥ 0.9809), repeatability (% RSD 3.4 – 16.1%) with the limit of detection (LOD) and limit of quantification (LOQ) of 0.015 - 0.134 μg L−1 and 0.047 - 0.407 μg L−1, respectively. Under this condition, the enrichment factors for the four NSAIDs were achieved between 219.2 and 379.7-folds. The developed VALLME-BE procedure resulted in a more selective and sensitive technique for the determination of NSAIDs in environmental water samples.