[Determination of three chlorophenols in red wine by sweeping-micellar electrokinetic chromatography coupled with...

A method of dispersive liquid-liquid microextraction (DLLME) and reversed phase liquid-liquid microextraction (RP-LLME) procedures coupled with sweeping-micellar electrokinetic chromatography (sweeping-MEKC) was established to extract and determine the three chlorophenols (CPs) including pentachlorophenol (PCP), 2, 4, 6-trichlorophenol (TCP) and 2,4-dichlorophenol (DCP) in red wine. The influences of the parameters of two extraction steps and the electrophoresis conditions were investigated. The optimum extraction conditions were as follows: for DLLME, 3.5 mL red wine sample (pH 3.0, 120 g/L NaCl), 300 microL hexane (extraction solvent), extraction for 3 min, centrifugation for 3 min at 5 000 r/min; for RP-LLME, 25 microL 0.16 mol/L NaOH solution, extraction for 2 min, centrifugation for 2 min at 5 000 r/min. The optimum running buffer (pH 2.3) was an aqueous solution containing 25 mmol/L NaH3PO4, 100 mmol/L sodium dodecyl sulfate (SDS) and 30% (v/v) acetonitrile. The optimum on-line concentration conditions were as follows: sample matrix, 80 mmol/L NaH2PO4; hydrodynamic injection of 20 s at 20.67 kPa (3 psi). Under the optimum conditions, the excellent linearity was obtained over the range of 0.5-100 microg/L (r > or = 0.991 0) for PCP and TCP, and 1.5-80 microg/L (r > or = 0.985 1) for DCP. The limits of detection (S/N = 3) were in the range of 0.035-0. 114 microg/L. The average recoveries were in the range of 75.2%-104.7% with the relative standard deviations (RSDs) not more than 6.17%. The results indicated that the proposed method may find wide applications for the determination of trace CPs in various sample matrixes and other weak acidic organic contaminants.