Electro-assisted liquid phase microextraction for the determination of parabens and their main metabolites in maternal urine and amniotic fluid samples

In this study, an electro assisted liquid phase microextraction (EA-LPME) procedure to determine seven parabens (methyl, ethyl, propyl, isopropyl, butyl, isobutyl, and benzyl paraben) and three of their key hydroxy metabolites (4-hydroxy, 3,4-dihydroxy, and 3,4,5-trihydroxy benzoic acid) was optimised in maternal urine and amniotic fluid obtained at delivery from pregnant women. The samples were analysed by ultra-high-performance liquid chromatography coupled with electrospray ionisation tandem mass spectrometry (UPLC-ESI-MS/MS). PHBs and their metabolites were extracted from a pH 4 donor solution (10 mL) into a pH 13 acceptor solution (50 µL) using 1-octanol as the supported liquid membrane (SLM) and 30 V for 40 min at 400 rpm. Under optimal operational conditions, enrichment factors between 10 and 90 were achieved, and low quantitation limits within 0.022–0.20ng mL⁻¹ and 0.025–0.18 ng mL⁻¹, were obtained for amniotic fluid and urine, respectively. The proposed analytical procedure was satisfactorily applied for the determination of target compounds in seven paired maternal urine and amniotic fluid samples to evaluate the possible placental transfer of these compounds from mothers to babies.