Determination of trace volatile fatty acids in ambient air by capillary gas chromatography–mass spectrometry in SIM mode

Abstract

A simple, rapid and sensitive method was developed and validated for the analysis of C₂–C₅ volatile fatty acids (VFAs) in ambient air. This method involves preconcentration of VFAs with a sodium carbonate-impregnated silica gel tube, ultrasonic extraction with pure water, partition of VFAs to diethyl ether and determination using gas chromatography with a mass selective detector in the selected ion monitoring mode. A water-resistant free fatty acid phase capillary column was used to directly separate C₂–C₅ VFAs without the time-consuming derivatisation process. The limits of detection ranged from 0.001 to 0.003 µg m⁻³ and the limits of quantification ranged from 0.003 to 0.010 µg m⁻³. The validated method was successfully applied to the analysis trace-level VFAs in ambient air and in air samples from a landfill with perceived odour pollution.

Keywords:

• volatile fatty acids (VFAs)
• GC–MS
• selected ion monitoring mode (SIM)
• FFAP column

Acknowledgements

Supports from Natural Science Foundation of China (Project No. 40673074), Guangdong Scicence & Technology Commission (Project No. 2007A032301002) and Guangzhou Bureau of Science and Technology (Project No. 2006Z1-E0101) are gratefully acknowledged.