Determination of parabens in human milk and other food samples by capillary electrophoresis after dispersive liquid–liquid microextraction with back-extraction

• DLLME was coupled to CE to determine four parabens in human milk and food samples.
• DLLME–CE reduces organic solvents and extraction time significantly.
• DLLME–CE requires minimum variation in the extraction procedure for food samples.
• Parabens were not detected in the analysed food samples.
• Low LODs, good recoveries and interference-free electropherograms were obtained.

Dispersive liquid–liquid microextraction (DLLME) with back-extraction was used prior to capillary electrophoresis (CE) for the extraction of four parabens. Optimum extraction conditions were: 200 μL chloroform (extraction solvent), 1.0 mL acetonitrile (disperser solvent) and 1 min extraction time. Back-extraction of parabens from chloroform into a 50 mM sodium hydroxide solution within 10 s facilitated their direct injection into CE. The analytes were separated at 12 °C and 25 kV with a background electrolyte of 25 mM borate buffer containing 5.0% (v/v) acetonitrile. Enrichment factors were in the range of 4.3–10.7 and limits of detection ranged from 0.1 to 0.2 μg mL−1. Calibration graphs showed good linearity with coefficients of determination (R2) higher than 0.9957 and relative standard deviations (%RSDs) lower than 3.5%. DLLME–CE was demonstrated to be a simple and rapid method for the determination of parabens in human milk and food with relative recoveries in the range of 86.7–103.3%.