Stir bar sorptive extraction and thermal desorption – gas chromatography/mass spectrometry for determining phosphorus flame retardants in air samples

Abstract

Stir bar sorptive extraction and thermal desorption coupled with gas chromatography/mass spectrometry (SBSE-TD-GC/MS) was utilized to determine phosphorus flame retardants (PFRs) in air samples. The one variable at a time (OVAT) approach was used to select the optimal conditions of the parameters that affect the SBSE procedure during thermal desorption. Desorption was carried out at 300 °C at a desorption flow rate of 76 mL min⁻¹ for 10 minutes with the transfer line set at 320 °C. The analytes were cryofocused at −40 °C and then cryo-desorbed at 320 °C for 2 minutes. The optimal desorption conditions were then used to validate the method. The method validation showed good linearity (r² > 0.9960), good precision (CVs ≤ 20%), low limits of detection (8.7–14.0 pg), good recoveries (>70%) and high reliability. Passive air sampling based on polydimethylsiloxane (PDMS) coated stir bars together with high volume-active air sampling (HV-AAS) (for comparison and calibration) was used to ascertain the appropriateness of the proposed method to determine the concentrations of PFRs in real air samples. The concentration results obtained by the two sampling techniques were comparable for compounds, whose passive samplers' accumulated masses were above the limits of quantitation and showed good uptake linearity over a specific period of time during the deployment. This work therefore affirms that the proposed method performs well and thus can be a suitable and cheaper alternative to active air sampling for gas phase PFRs.