Solid phase microextraction with poly(deep eutectic solvent) monolithic column online coupled to HPLC for determination of non-steroidal anti-inflammatory drugs.

Polymer monolithic column based on a green deep eutectic solvent (DES) was prepared for in-tube solid phase microextraction of non-steroidal anti-inflammatory drugs (NSAIDs) in aqueous samples. DES composed of choline chloride and itaconic acid was adopted as functional monomer to synthesize a polymeric monolith inside polydopamine-functionalized poly(ether ether ketone) (PEEK) tube. The obtained monolithic column was characterized with fourier transform infrared spectrometry, X-ray photoelectron spectrometer and field emission scanning electron microscope. An online SPME-HPLC method was developed by connecting the PEEK tube to the HPLC system. Parameters including sampling rate, desorption time, sample pH value and sample volume that can affect the performance of this method were investigated. Under the optimized conditions, the proposed SPME-HPLC method showed high extraction efficiency (enrichment factors about 100), good linearity (R ≥ 0.9997) and good reproducibility (relative standard deviation < 4.32%) for determination of three NSAIDs in aqueous solution. The limits of quantification were found to be in a range of 0.05-0.25 ng mL-1 . The SPME-HPLC method was also successfully applied to detect NSAIDs in lake water and human plasma samples.