Organophosphorus flame retardants (OPFRs) are widely used in consumer and industrial products as replacements for brominated and chlorinated based flame retardants in textiles, plastics, electronics and other materials. Recent monitoring studies have found OPFRs present in both environmental and biological samples, with several compounds exhibiting toxic and carcinogenic effects. Here we present the development of an analytical method for the determination of 13 OPRFs in water and implementation for the analysis of a range of samples collected from the environment.
OPFRs were extracted from water samples (100 mL) using SPE (Oasis HLB) and an aliquot (100 µL) of the acetonitrile eluent from the SPE stage was injected directly into the 2D LC system, avoiding the need for any evaporation and solvent exchange. The 2D LC system was configured with a primary column for “trap and elute” prior to chromatographic separation on the UPLC analytical column. At column dilution with an aqueous solvent prior to transfer to the analytical column ensured that chromatographic peak shape was maintained even with injection of a large volume of organic solvent. A range of conditions (pH and organic solvents) were evaluated to provide optimum conditions.
The 2D-LC system was coupled to quadrupole-time of flight (Q-Tof) mass spectrometer. Data was acquired using a type of non-targeted analysis, known as MSE. The use of full spectral acquisition, cycled between low and elevated collision energy, carried out with high mass resolving power, provided a comprehensive, unbiased dataset with information on accurate mass and isotope patterns for both precursor and fragment ions. After componentisation, this data can be interrogated in three main ways. First, an existing library was searched that contained data (including retention time) from the previous analysis of OPFRs reference standards. This might be limited in scope for emerging contaminants, so to screen for additional constituents in samples a further search was made of the same data using external databases (e.g. ChemSpider) for other known OPFRs. A third option is available for complete unknowns to look for specific features (e.g. halogen match, neutral loss, mass defect) which might also include searching for common fragment ions and further MS/MS analysis. In contrast to determination by tandem quadrupole systems the QTof offers the capability to perform these data reviews retrospective to the acquisition.
The performance of the method, with regards to sensitivity, accuracy, precision and identification criteria, will be presented.