Investigation of organophosphate esters in fresh water, salt and brine samples by GC-TOF MS

Abstract

Advanced analytical methodology based on gas chromatography coupled to a high resolution time-of-flight mass analyzer (GC-TOF MS) is proposed for investigation of organophosphate esters (OPEs) in environmental water, marine salts and brine samples. The target screening was carried out for 12 OPEs by evaluating the presence of up to four m/z ions for every compound. The identification criteria were the presence of, at least, two m/z ions at the expected retention time, measured at their accurate mass, and the agreement of the Q/q_i ratio when compared to reference standards. This procedure allows the detection and reliable identification of the compounds in the samples at very low concentration levels (ng g⁻¹). The developed methodology was applied to commercial marine salt, brines and different environmental water samples obtaining positive findings for several OPEs such as tri(chloro-propyl)phosphate, tributyl phosphate, triphenyl phosphate among other organophosphate compounds. Thanks to the full-spectrum acquisition performed in GC-TOF MS, it is possible to make a retrospective data evaluation without the need for performing additional analysis. This allowed in this work re-evaluation of data acquired in a previous GC-TOF MS non-target analysis of some marine salt and water samples with the result of discovering several of the OPEs investigated in those samples.