Determination of organophosphate ester flame retardants and plasticizers in soil samples by microwave-assisted extraction coupled with silica gel/alumina multilayer solid-phase extraction and gas chromatography-mass spectrometry

Abstract

In the present study, the performances of the commonly used solid phase extraction (SPE) materials, i.e. alumina, Florisil and silica gel, for separating organophosphate esters (OPEs) from potential co-extracted interferents such as polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), polycyclic aromatic hydrocarbons (PAHs) and organochlorine pesticides (OCPs), were evaluated. Silica gel/alumina (Si/Al) multilayer SPE for OPE sample preparation could effectively reduce matrix effects. A novel and selective method, based on sample preparation by microwave-assisted extraction (MAE) and Si/Al multilayer SPE cartridge cleanup, for the determination of OPEs in soil samples by gas chromatography-mass spectrometry (GC/MS), was developed. The method quantification limits for OPEs ranged from 0.09 to 2.39 ng g⁻¹. A good linearity (r² > 0.991) between MQLs and 1000 × MQLs was achieved. The developed method was successfully applied to determine OPEs in soil samples collected from the campus of Sun Yat-sen University, China. Of the 11 OPEs analyzed, triethyl phosphate (TEP), tri-n-butyl phosphate (TnBP), tris(2-chloroethyl) phosphate (TCEP), tris(1-chloro-2-propyl) phosphate (TCPP), tributoxyethyl phosphate (TBEP) and triphenylphosphate (TPhP) were present in all of the soil samples, and dominated by TBEP, TCEP, TnBP and TCPP. As compared to the results of other studies, the campus soils of Sun Yat-sen University, China, were moderately polluted by OPEs.