Direct injection and automated pressurized extraction coupled to high-resolution mass spectrometry for the quantification of organophosphate flame retardants in water, soil and dust.

Organophosphate flame retardants (OPFRs) are widely used additives that are not chemically bound to consumer products, enabling their continuous release into the environment. This study presents an integrated multi-matrix analytical platform combining automated pressurized solvent extraction (PSE) with liquid chromatography-high-resolution mass spectrometry (LC-HRMS) in SWATH acquisition mode for the determination of nine OPFRs in agricultural soil and indoor dust, together with a direct injection method for reclaimed water samples. The automated PSE method provided recoveries of 70-120% (RSD < 20%) and limits of quantification (LOQs) of 1-50 ng/g in dust and agricultural soils, while direct injection achieved LOQs of 0.2-10 ng/mL (RSD < 20%) for reclaimed waters. The workflow was applied to reclaimed water (n = 92), irrigated soils (n = 22), and indoor dust (n = 10) collected between 2024 and 2026. Reclaimed water samples analysed from an Almeria reclaimed water treatment plant (RWTP) showed that tris(2-butoxyethyl) phosphate (TBOEP) was consistently detected (∼0.7 ng/mL, n = 67), whereas triphenyl phosphate (TPP) was frequently detected below the LOQ. Although concentrations in water were low, both compounds predominated in irrigated soils (2-53 ng/g). Indoor dust represented a major contamination reservoir, with tris(1,3-dichloro-2-propyl) phosphate (TDClPP) and TPP detected in all samples at concentrations up to, 5.0, and 1.1 μg/g, respectively and TBOEP with an estimated concentration of 0.4 μg/g. This work combines automated PSE in soil and dust with direct injection for water and LC-HRMS acquisition (SWATH, with targeted MRMHR for dust) for nine OPFRs. The SWATH data allow retrospective screening, as illustrated by the tentative identification of azoxystrobin in agricultural soil, and the platform is expandable to additional emerging contaminants, increasing its applicability to future environmental monitoring studies.