Establishment of a sensitive derivatization method for analysis of organophosphate diesters (OPDEs), and their target and nontarget screening in Taihu Lake sediment

The current scope of environmental monitoring studies primarily focuses on organophosphate triesters (OPTEs), neglecting their potential transformation products, i.e. organophosphate diesters (OPDEs). Furthermore, there is a notable absence of comprehensive screening strategies for all potential OPDEs in environmental samples. Herein, we pioneered an effective and precise screening strategy, incorporating target, suspect, and functional group-dependent nontarget screening, founded on ultrahigh performance liquid chromatography-Q Exactive hybrid quadrupole-Orbitrap high-resolution mass spectrometry (UHPLC-Q-Orbitrap HRMS), and this strategy was applied to analyze n  = 74 sediment samples, comprising 23 surface sediment samples and 51 sediment core samples, collected from Taihu Lake in eastern China during 2019. Through this analysis, we successfully identified 29 OPDEs, marking the first documentation of their presence in this region. Additionally, our study yielded noteworthy insights: 1) most OPDEs exhibited no significant correlations with their parent compounds, indicating their intricate origins within Taihu Lake; 2) two newly identified substances, distearyl phosphate (DSP) and diheptadecyl phosphate (DHP), were widespread and likely introduced through various rivers, potentially originating from chemical industry facilities or manufacturers situated along the rivers in the Taihu Lake basin; 3) vertical analysis revealed the pervasive presence of long-chain alkyl OPDEs in sediment cores from Taihu Lake, consistent with their high hydrophobicity. Collectively, this study has introduced an effective screening strategy successfully applied to comprehensively assess OPDEs in Taihu Lake sediments. This methodology holds promising potential for extension to various other environmental matrices or samples.