Development of a strategy for sampling, preservation, and analysis of classical and emerging flame retardants and plasticizers in air samples

This study presents a methodology for sampling, preserving, and analyzing 15 organophosphate esters (OPEs), 11 phthalate esters (PEs), and 6 alternative plasticizers (APs) in indoor air. Accurate quantification is essential, given their widespread use in household items and adverse health effects associated with exposure. Solid-phase extraction (SPE) cartridges, collecting both gaseous and particulate phases, connected to a low-volume pump were used for the collection of air samples. Stability tests confirm that storing samples at 4 °C is most optimal to maintain analyte integrity for at least 2 weeks. The analytes were extracted and then purified online using turbulent flow chromatography, before analysis via liquid chromatography-tandem mass spectrometry (TFC-LC-MS/MS). Quantification was carried out by applying the isotopic dilution method with labelled standards. Recoveries ranged from 50 to 136%, with reproducibility below 21%. The relative standard deviation (RSD) varied from 2 to 31%, only exceeding the 20% threshold for certain OPEs at lower concentrations. Limits of detection (mLODs) varied between 0.02-0.89 ng/m³, 0.02-20.0 ng/m³, and 0.07-1.47 ng/m³ for OPEs, PEs, and APs, respectively. The study demonstrates that this methodology is effective, cost-efficient, and suitable for monitoring a total of 33 flame retardants and plasticizers in indoor air. It minimizes material costs and sample handling time by allowing direct analysis without pretreatment. Results from indoor air samples collected in a case study revealed that OPEs attributed to less than 20% of the chemical profile, while triethyl citrate (TEC) was detected at concentrations up to 28.9 ng/m³, confirming the method's applicability for the added APs.