FOURIER-TRANSFORM INFRARED AND ION-CHROMATOGRAPHIC SULFATE ANALYSIS OF AMBIENT AIR SAMPLES

Fourier transform infrared (FTIR) spectrometry has been evaluated as a method for determining the sulfate concentration of ambient aerosol particulate samples. Samples were collected on Teflon filters. The filters were analyzed for sulfate by both FTIR and ion chromatography (IC). There is good agreement between sulfate analysis by IC and analysis of the FTIR transmission spectra of the air filters during the first 5 1/2 days of the Carbonaceous Species Methods Intercomparison Study in which the ambient sulfate concentrations were above the 5.8 μg/cm2lower limit of detection of the FTIR technique. A method to improve the FTIR lower limit of detection is discussed. The difficulties incurred during background subtraction of the infrared spectra are described. © 1990 Elsevier Science Publishing Co., Inc.