SUPERCRITICAL-FLUID EXTRACTION GAS-CHROMATOGRAPHIC ANALYSIS OF ORGANIC-COMPOUNDS IN ATMOSPHERIC AEROSOLS

An integrated sampling and supercritical fluid extraction (SFE) cell has been designed for whole-sample analysis of organic compounds on tropospheric aerosol particles. The low-volume, polymer-free, temperature-controlled extraction cell has been interfaced with a sampling manifold for aerosol collection in the field. After sample collection, the entire SFE cell was removed, transferred, and coupled to a gas chromatograph; after on-line extraction, the cryogenically focused sample was separated and the volatile compounds were detected with either a mass spectrometer or a name ionization detector. A 20-min extraction at 450 atm and 90 degrees C with pure supercritical CO2 is sufficient for quantitative extraction of most volatile compounds in aerosol samples, A comparison between SFE and thermal desorption, the traditional whole-sample technique for analyses of this type, was performed using ambient aerosol samples, as well as samples containing known amounts of standard analytes.