A GC-TCD method for measuring the liquid water mass of collected aerosols

Chung Te Lee, Shih Yu Chang

Research output: Contribution to journalArticlepeer-review

17 Scopus citations

Abstract

This work presents a gas chromatographic method that uses a thermal conductivity detector (GC-TCD) to measure the liquid water mass (LWM) of collected aerosols. The method is a modification of the previously developed EA-TCD method (Journal of Aerosol Science 29, 827). A microcomputer was incorporated into the system to control the analytical procedures, improve the measurement precision, and make possible a continuous operation. To validate the method, the aerosol LWMs of NaCl, Na2SO4, NH4NO3, (NH4)2SO4, NH4Cl, and Na2CO3 were measured at room temperature under relative humidities (RHs) varying between 20% and 90%, in both humidifying and dehumidifying conditions. Estimates of aerosol LWMs for varying aerosol chemical compositions and RHs by various measurement methods and predictive models are comprehensively compared. The comparison shows that the GC-TCD measurements agree closely with those of the other methods. The GC-TCD measurements are closer to the ISORROPIA model predictions than those of the AIM2 model. Most notably, our method determines, for the first time, the hygroscopic behavior of Na2CO3 aerosol yielding the deliquescence relative humidity and crystallization relative humidity at 78% and 39% RH, respectively. The hygroscopic characteristics of various NaCl mole fractions in mixed NaCl-Na2SO4 aerosols, determined by GC-TCD, are used to show the discrepancy between the measurements and the model's prediction.

Original languageEnglish
Pages (from-to)1883-1894
Number of pages12
JournalAtmospheric Environment
Volume36
Issue number11
DOIs
StatePublished - 2002

Keywords

  • Aerosol liquid water mass
  • GC-TCD measurement system
  • Hygroscopic aerosol
  • NaCO aerosol
  • NaCl-NaSO mixed aerosols

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