Analysis of phthalic acid esters in sea water and sea sand using polymer-coated magnetic nanoparticles as extraction sorbent.

In this work, poly(dopamine)-coated magnetic nanoparticles (Fe3O4@pDA) have been used as sorbents for the magnetic dispersive solid-phase extraction (m-dSPE) of a group of 10 phthalic acid esters (dipropyl phthalate, DPP, dibutyl phthalate, DBP, dicyclohexyl phthalate, DCHP, bis(2-ethylhexyl)phthalate, DEHP, di-n-octyl phthalate, DNOP, diisodecyl phthalate, DIDP, butylbenzyl phthalate, BBP, diisononyl phthalate, DINP, diisopentyl phthalate, DIPP, di-n-pentyl phthalate, DNPP) and one adipate (di(2-ethylhexyl) adipate, DEHA) from sea water and sea sand extracts employing DBP-d4 and DHP-d4 as internal standards. After m-dSPE, analysis was carried out by gas chromatography mass spectrometry. Mean recovery values (which were determined at three concentration levels) ranged between 70 and 120%, with relative standard deviation values ≤ 20%, for nearly all analytes in both matrices. Matrix-matched calibration curves revealed the presence of matrix effects for certain PAEs, specially for sea sand, though linearity was assayed with determination coefficients (R2) above 0.991 for all target analytes. The limits of quantification of the method were in the range 1.8-319 ng/L for sea water and 0.020-4.0 ng/g for sea sand. Several samples of each type collected at different sites of the coast of Tenerife were also analysed. Only DEHA, DNOP and DIPP were detected in some of the sea sand samples at concentrations ≤ 44 ng/g.