Temperature effect of tapered element oscillating microbalance (TEOM) system measuring semi-volatile organic particulate matter

Autores UPV
Año
Revista JOURNAL OF ENVIRONMENTAL MONITORING

Abstract

The tapered element oscillating microbalance (TEOM) system is widely used to measure continuous particle mass concentrations in air quality networks. However, the semi-volatile aerosol material is lost under normal operation conditions (50 °C). This study has evaluated the error in the organic fraction of the TEOM-measured secondary organic aerosols formed from the degradation of biogenic pollutants. Experiments were carried out under controlled, water-free conditions in a fully equipped, high volume atmospheric simulator - the European PhotoReactor (EUPHORE). The ozonolysis of ¿-pinene, ß-pinene and limonene provided a reproducible source of organic aerosol. Particulate matter concentration profiles were registered for different TEOM operating temperatures. When these values were compared with values from a filter-based gravimetric method and a scanning mobility particle sizer (SMPS), they showed that the differences between monitoring systems increased with increasing TEOM temperature. According to our results, when the TEOM is operated at 50 °C, it fails to measure 32-46% of the organic particulate material, depending on the aerosol precursor. This study has also identified and quantified the multi-oxygenated organic compounds lost in the TEOM monitoring by using a method based on the gas chromatography-mass spectrometry technique. Important losses have been calculated for relevant ambient aerosol compounds such as pinonic acid, pinonaldehyde, norpinone and limonalic acid. In conclusion, the present study has demonstrated that a high operating temperature of the TEOM monitor reduces the humidity interference but underestimates the semi-volatile organic fraction. © The Royal Society of Chemistry.