Development and characterization of a solvent extraction–gas chromatographic/mass spectrometric method for the analysis of perfluorooctanesulfonamide compounds in solid matrices

A method utilizing solvent extraction and analysis by gas chromatography–positive chemical ionization mass spectrometry (SE–GC–PCI-MS) was developed for the analysis of three neutral hydrophobic perfluorooctanesulfonamide compounds [perfluorooctanesulfonamide (PFOSA), N-ethyl perfluorooctanesulfonamide (N-EtPFOSA), and N,N-diethyl perfluorooctanesulfonamide (N,N-Et2PFOSA)]. These compounds are suspected metabolic precursors of perfluorooctane sulfonate. The SE–GC–PCI-MS method was used to analyze all three perfluorooctanesulfonamides in fast food, fish, and Arctic marine mammal liver samples. The SE–GC–PCI-MS method produced relatively higher recoveries of the analytes (averaging 83 ± 6%, 84 ± 9%, and 89 ± 19% for N,N-Et2PFOSA, N-EtPFOSA, and PFOSA, respectively) with lower coefficients of variation, and less susceptibility to matrix effects, than ion pair extraction–liquid chromatography–tandem mass spectrometric methods. Method detection limits (MDLs) were 100, 120, and 250 pg/g for N,N-Et2PFOSA, N-EtPFOSA, and PFOSA, respectively. The three compounds were found at concentrations ranging from below the MDL to 22 ng/g wet weight in fast food, fish, and Arctic marine mammal liver samples.