Enhanced microextraction of endocrine disrupting chemicals adsorbed on airborne fine particulate matter with gas chromatography-tandem mass spectrometric analysis.

A novel double-microextraction approach, combining dispersive liquid-liquid microextraction (DLLME) and vortex-assisted micro-solid-phase extraction (VA-µ-SPE) was developed. The procedure was applied to extract endocrine disrupting chemicals (EDCs) consisting of three phthalate esters (PEs) and bisphenol A (BPA) associated with PM (airborne particulate matter with aerodynamic diameter ≤ 2.5 µm). Gas chromatography-tandem mass spectrometry (GC-MS/MS) was used for determination of the analytes. These analytes were first ultrasonically desorbed from PM in a 10% acetone aqueous solution. DLLME was used to first preconcentrate the analytes; the sample solution, still in the same vial, was then subjected to VA-µ-SPE. The synergistic effects provided by the combination of the microextraction techniques provided advantages such as high enrichment factors and good cleanup performance. Various extraction parameters such as type and volume of extractant solvent (for DLLME), and type of sorbent, extraction time, desorption solvent, volume of desorption solvent and desorption time (for µ-SPE) were evaluated. Multi-walled carbon nanotubes were found to be the most suitable sorbent. This procedure achieved good precision with intra- and inter-day relative standard deviations of between 1.93 and 9.95%. Good linearity ranges (0.3-100 ng/mL and 0.5-100 ng/mL, depending on analytes), and limits of detection (LODs) of between 0.07 and 0.15 ng/mL were obtained. The method was used to determine the levels of PEs and BPA in ambient air, with concentrations ranging between below the limits of quantification and 0.48 ng/m. DLLME-VA-µ-SPE-GC-MS/MS was demonstrated to be suitable for the determination of these EDCs present in PM.