Pressurized liquid extraction of organophosphate triesters from sediment samples using aqueous solutions

A novel procedure for the extraction of seven organophosphate triesters (OPs), used as flame retardants and plasticizers, from sediment samples has been developed. It is based on the pressurized liquid extraction of the analytes with aqueous solutions, combined with a further concentration step using solid-phase extraction (SPE) and followed by gas chromatography coupled to mass spectrometry (GC-MS) determination. The effects of different variables on the yield and selectivity of the sample preparation process are systematically evaluated. The optimal responses were observed extracting 2g of sediment with a water:acetonitrile (75:25) solution at 90 degrees C and 1500 psi for 5 min. The obtained extract was made up to 200 mL with ultrapure water and passed through an OASIS HLB, 60 mg cartridge. Analytes were recovered with 2 mL of ethyl acetate and this extract concentrated to a lower volume, ca. 0.2 mL. Recoveries of the proposed extraction method ranged from 77 to 111%, with relative standard deviations below 10%, for spiked river and marine sediment samples with total carbon contents (TC) up to 4.0%. The limits of quantification (LOQs) of the method varied between 0.5 and 5 ng g(-1). Analysis of non-spiked sediment samples revealed the presence of low levels for some of the investigated species, with the highest concentration (47 ng g(-1)) corresponding to tris(2-chloroethyl) phosphate (TCEP).