FTIR transmission spectrometry for the nondestructive determination of ammonium and sulfate in ambient aerosols collected on teflon filters
Fourier transform infrared (FTIR) transmission spectrometry has been used to determine ammonium and sulfate in ambient aerosol particles collected on Teflon filters. Integrated absorbance as well as maximum absorbance values for ammonium and sulfate are linearly related to X-ray fluorescence measurements of total sulfur. Apparent detection limits of 1.4 μg m-3 for sulfate and 0.5 μg m-3 for ammonium (for sample volumes of 21.6 m3) were estimated for samples from Topeka, Kansas; Portage, Wisconsin; Steubenville, Ohio; and Charlottesville, Virginia. The apparent detection limits were essentially independent of sample loading over the range of 0-20 μg m-3 of total sulfur. The FTIR transmission measurements of these samples are very precise e.g. repetitive measurements vary ± 0.2% and blank variability is 0.13 μg m-3 and 0.20 μg m-3 in terms of sulfate and ammonium, respectively. Contributions to analytical uncertainty include 5-8% uncertainties in X-ray fluorescence measurements for total sulfur and the influence of unspecified site-dependent sample characteristics. The method offers the significant advantages of nondestructive analysis, no sample preparation, molecular speciation and rapid analysis. © 1985.
