Extraction of pyridine derivatives from human urine using electromembrane extraction coupled to dispersive liquid–liquid microextraction followed by gas chromatography determination

In the present work, some of pyridine derivatives were analyzed for the first time in complicated biological fluids by coupling electromembrane extraction with dispersive liquid–liquid microextraction (EME–DLLME). 3-Methylpyridine, 2,4-lutidine, quinoline and 4-dimethylaminopyridine (DMAP) were extracted from urine and water samples. Effective parameters on the efficiencies of EME and DLLME were optimized by one variable at a time method and face-centered central composite design (FCCCD), respectively. The supported liquid phase (SLM) employed for the extraction of the analytes was a mixture of 90% 2-nitrophenyl octyl ether (NPOE) and 10% di-(2-ethylhexyl) phosphate (DEHP) which was immobilized in the pores of a piece of hollow fiber. An electric field was applied to carry over the analytes into acceptor solution. The acceptor solution was transferred to 1 mL of an alkaline solution (pH=13) and then DLLME procedure was performed. Preconcentration factors in the range of 40–263 and satisfactory repeatabilities (2.3<RSD%<5.3) were obtained in different matrices. The method offered a good linearity with coefficient of determination greater than 0.9948 and was utilized for determination and quantification of pyridine compounds in smokers׳ urine samples. The proposed technique can be introduced as a simple, fast and inexpensive method for diagnosis of smokers.