Gas chromatographic determination of airborne organic acids via their anilides

Abstract

A gas chromatographic method was developed for the determination of airborne acetic, propionic and butyric acids collected on sampling tubes containing charcoal. On treatment with thionyl chloride followed by aniline, the acids yielded the corresponding anilides, which were quantified by gas chromatography with either flame-ionization or nitrogen–phosphorus detection. The anilides are stable and provide enhanced sensitivity of detection. The characteristic mass spectra of the anilides provide unequivocal structural confirmation of the identity and can also be used for highly sensitive quantification by selected-ion monitoring. The proposed procedure can be used to detect acetic, propionic and butyric acids at levels of 5 and 1 µg using flame-ionization and nitrogen–phosphorus detection, respectively, for a 60 dm³ air sample.