Sensitive determination of parabens in human urine and serum using methacrylate monoliths and reversed-phase capillary liquid chromatography–mass spectrometry

• Polymeric monoliths were applied to the analysis of parabens in biological samples.
• DLLME technique followed by cLC–MS detection using monolithic columns was successfully combined.
• Rapid and very sensitive determination of parabens in urine and serum samples was achieved.

A method for the determination of parabens in human urine and serum by capillary liquid chromatography (cLC) with UV–Vis and mass spectrometry (MS) detection using methacrylate ester-based monolithic columns has been developed. The influence of composition of polymerization mixture was studied. The optimum monolith was obtained with butyl methacrylate monomer at 60/40% (wt/wt) butyl methacrylate/ethylene dimethacrylate ratio and 50 wt% porogens (composed of 36 wt% of 1,4-butanediol, 54 wt% 1-propanol and 10 wt% water). Baseline resolution of analytes was achieved through a mobile phase of acetonitrile/water in gradient elution mode. Additionally, dispersive liquid–liquid microextraction (DLLME) was combined with both cLC–UV–Vis and cLC–MS to achieve the determination of parabens in human urine and serum samples with very low limits of detection. Satisfactory intra- and inter-day repeatabilities were obtained in UV–Vis and MS detection, although the latter provided lower detection limits (up to 300-fold) than the UV–Vis detection. Recoveries for the target analytes from spiked biological samples ranged from 95.2% to 106.7%. The proposed methodology for the ultra-low determination of parabens in human urine and serum samples is simple and fast, the consumption of reagents is very low, and very small samples can be analyzed.