Volatile fatty acids(VFAs) are typical malodorous substances

which are at trace levels in the ambient air.A method of gas chromatography-mass spectrometry(GC-MS) was established for the simultaneous determination of seven VFAs ie.acetic acid

propanoic acid

isobutyric acid

butyric acid

acrylic acid

isovaleric acid and valeric acid in ambient air.Ambient air samples were firstly collected with impregnated silica gel tube

then ultrasonically extracted with ultrapure water

finally partitioned with methyl tert-butyl ether

concentrated and set to a certain volume.The target compounds were determined by GC-MS

and quantified by internal standard method.Results showed that the calibration curves for seven VFAs were linear(r2≥0.995) in their respective concentration ranges with the detection limits of 0.11-4.78 μg/m3.The recoveries were in the range of 62.3%-110% with relative standard deviations of 2.2%-12%.The method is simple

accurate and sensitive

and is suitable for the determination of VFAs in ambient air.