Multivariate optimization of a microextraction by packed sorbent-programmed temperature vaporization-gas chromatography-tandem mass spectrometry method for organophosphate flame retardant analysis in environmental aqueous matrices

In this work, organophosphate ester flame retardant (OPFRs) assay in environmental waters was addressed by using microextraction by packed sorbent (MEPS) and gas chromatography-tandem mass spectrometry (GC-MS/MS). Ten OPFRs with different physicochemical properties were taken into account as target compounds for a comprehensive method evaluation. Five MEPS cartridges (i.e., C2, C8, C18, Silica, and DVB) and seven solvents (i.e., methanol, ethyl acetate, methyl tert-butyl ether, hexane, acetonitrile, dichloromethane, and trichloromethane) were surveyed. The analysis was performed by using a gas chromatograph equipped with a programmed temperature vaporization injector (PTV). Univariate and multivariate approaches were exploited in order to optimize the parameters affecting the MEPS extraction and the PTV injection of the analytes into the gas chromatographic system. The optimal working conditions were achieved using DVB as sorbent material and acetonitrile as elution solvent. Internal standard calibration was carried out using TBP-d27 and TCEP-d12. Satisfactory values of accuracy and precision were generally obtained as well as limit of detection (2.7-99 pg/mL for tap water; 2.9-97 pg/mL for river water; 3-107 pg/mL for wastewater) and limit of quantification (0.01-0.2 ng/mL). The proposed protocol was evaluated on real case scenarios by analyzing tap water, river water and simulated wastewater samples. The developed method is not only eco-friendly due to the low use of organic solvents but also simple and automatable since the MEPS extraction procedure can be implemented in the autosampler routine.