title: Application of gas chromatography coupled to chemical ionisation mass spectrometry following headspace solid-phase microextraction for the determination of free volatile fatty acids in aqueous samples.
abstract: Gas chromatography coupled to positive and negative ion chemical ionisation mass spectrometry was evaluated for the determination of free volatile fatty acids (VFAs) from aqueous samples by headspace solid-phase microextraction. Negative ion chemical ionisation in the selected ion monitoring mode using ammonia as reagent gas provided acceptable sensitivity and the highest selectivity for the determination of C2-C7 fatty acids using a polydimethylsiloxane-Carboxen fibre. Detection limits in the range of 150 microg l(-1) for acetic acid and from 2 to 6 microg l(-1) for the remaining carboxylic acids were achieved. The reproducibility of the method was between 9 and 16%. The developed analytical procedure was applied to the analysis of VFAs in raw sewage. The absence of interfering peaks provided a more accurate determination of acetic, propionic, butyric and isovaleric acids than a similar analytical scheme but using a flame ionisation detector.
authors.affiliation: Environmental Chemistry Department, IIQAB-CSIC, Barcelona, Spain.
authors.forename: M
authors.initials: M
authors.lastname: Abalos
authors.forename: J M
authors.initials: JM
authors.lastname: Bayona
mesh_terms: D005230:Fatty Acids, Nonesterified / Q000032:analysis*; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012722:Sewage / Q000737:chemistry*; D014835:Volatilization
chemical_list: D005230:Fatty Acids, Nonesterified; D012722:Sewage