Suspect and nontarget screening of known and unknown organophosphate esters (OPEs) in soil samples

Ninety-five soil samples (n = 95) were analyzed using an integrated suspect and non-target organophosphate ester (OPE) screening strategy. This suspect and non-target screening strategy allowed us to fully or tentatively identify 26 OPEs or OPE-like substances. Among these 26 newly identified contaminants, bisphenol A bis(diphenylphosphate) (BPABDP) exhibited the highest detection frequency of 83.2 %, with a concentration range of ND - 385 ng/g dry weight (dw). We also observed that BPABDP was significantly correlated with all other OPEs (p < 0.001 in all pairs), suggesting that BPABDP is widely used as a plasticizer and flame retardant in various commercial products. Another interesting finding was the discovery of four novel OPE structures with tentatively proposed chemical structures. Among these four non-target OPEs, (tert-butyl) phenyl bis(2,4-di-tert-butylphenyl) phosphate (TBPBDTBPP) shared a backbone structure very similar to that of the well-known OPE, tris(2,4-di-tert-butylphenyl) phosphate (TDTBPP). Detection frequency of this newly discovered OPE was high, up to 69.5 %, and it was significantly correlated with isodecyl diphenyl phosphate (IDDP), BPABDP, diphenyl 2-isopropylphenyl phosphate (2IPPDPP), and tricresyl phosphate (TCrP, p < 0.05 in all pairs), respectively. This study reported the most comprehensive suite of OPEs in soil samples, and 16 out of them were recognized in soil for the first time.