Structural identification of isomers present in technical perfluorooctane sulfonate by tandem mass spectrometry.
The structures of isomeric by-products of technical perfluorooctane sulfonate (PFOS, C8F17SO3-) were characterized by high-performance liquid chromatography coupled to mass spectrometry. Ion trap (IT) as well as triple quadrupole (TQ) tandem mass spectrometry (MS/MS) identified ten PFOS isomers with best results being achieved by ion trap MS/MS. In addition to the linear isomer, the main by-products were isomers with geminal diperfluoromethyl groups and perfluoromethyl-substituted compounds. Purified fractions of the perfluoromethyl isomers allowed the elucidation of structures and the assignment of the retention times of perfluoroisopropyl-, 5-perfluoromethyl-, 4-perfluoromethyl-, 3-perfluoromethyl- and 1-perfluoromethyl-PFOS. The concentration of 2-perfluoromethyl-PFOS was too low in technical PFOS for a proper identification. Retention times of the geminal substituted diperfluoromethyl isomers could not be properly assigned due to co-elutions. The number and position of the CF3 groups can be derived from the MS/MS spectra, which allow an unequivocal identification of the isomers. TQ-MS/MS also allowed us to identify most of the isomers.
The University of Basel, Organic and Analytical Chemistry Institut, Neuhaustrasse 31, Basel 4057, Switzerland.
Ingrid
I
Langlois
Michael
M
Oehme
D017738:Alkanesulfonic Acids / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid; D004784:Environmental Monitoring / Q000379:methods*; D005466:Fluorocarbons / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D013237:Stereoisomerism
D017738:Alkanesulfonic Acids; D005466:Fluorocarbons; C076994:perfluorooctane sulfonic acid