SO2 SORPTION CHARACTERISTICS OF AIR SAMPLING FILTER MEDIA USING A NEWLABORATORY TEST

A significant factor in the selection of filter media used for air sam pling is the formation of artifacts due to the sorption of sulfur and nitrogen oxides on the filter. These artifacts can erroneously increas e measured particulate concentrations. A technique is developed to mea sure the uptake of SO2 and other gases and vapors on air sampling filt er media. The static chamber technique features in-chamber measurement s of SO2 concentrations using FTIR spectrometry. The filter uptake, pa rtition coefficient, and diffusion coefficient are estimated from the loss of gaseous SO2 in the chamber. The technique provides rapid and p recise results over a wide range of filter characteristics and avoids problems related to the extraction of target analytes from the filter. A total of 12 types of filters are evaluated, including glass fiber, Teflon-coated glass fiber, nylon, quartz fiber, Teflon, Super, Nylasor b, and acrylic copolymer membranes. Results indicate that Teflon, quar tz and acrylic copolymer filters have minimal sorption of SO2 while qu artz fiber, Super and Nylasorb filters have high to moderate uptake of SO2. Copyright (C) 1997 Elsevier Science Ltd.