Fourier Transform Infrared Spectroscopy (FTIR) Ammonium Sulfate Analysis on Teflon Air Filters

摘要

This paper reports on the improvement and automation of a method of analyzing ammonium sulfate particles collected on Teflon membrane filters. The filters were analyzed by transmission measurements using Fourier transform infrared spectroscopy after collection with dichotomous air samplers. The spectra of the blank filters are subtracted from the spectra of the loaded filters and an integration of the 1000 to 1135 cm sup -1 absorbance band for sulfate leads to a lower limit of detection of 0.2 mu g/cm sup 2 on 37 mm 2 micron Teflon filters. This corresponds to an ambient concentration of mu g/m sup 3 for a 24 hr, 21.6 m sup 3 air sample. Ammonium sulfate particulate standards were prepared by sampling the output of a laboratory particle generator. Concentrations were then determined by x-ray fluorescence analysis. An automatic sample changer was constructed which accepts the filter carousel from a Sierra/ Anderson model 245 automated dichotomous sampler. The sample changer is controlled by the FTIR computer. The analysis is nondestructive, automated, and requires no sample preparation. (ERA citation 11:038678)