SULFUR DIOXIDE: METHOD 6004, Issue 2, dated 15 August 1994 - Page 4 of 4 EVALUATION OF METHOD: The sampler was adapted from that of Pate, et al. [9]. In experiments in which SO 2 was generated by permeation tube and collected in impingers containing H 2O 2, untreated 0.8-µm cellulose ester membrane filters were shown to allow complete passage of SO 2 [10]. In subsequent sampling of an atmosphere containing ca. 10 ppm SO 2 at 1 L/min for 30 min, two treated filters were placed in series following a cellulose ester membrane filter. Recoveries were: 0.667 mg SO 2 from the first treated filter, 0.02 mg SO 2 from the second treated filter, and less than 0.003 mg SO 2 in the backup impinger containing 0.3 N H2O 2 [11]. Cellulose ester filters spiked with 0.2 mg H 2SO 4 gave the following recoveries: 83.5% using H2O extraction, 98.5% using hot H 2O extraction, and 82.5% using 0.01 M HCl for extraction. A study on filter impregnating solutions compared NaHCO 3 and KOH. The chromatograms of samples from the KOH-treated filters had noticeably flattened and broadened peak shapes as well as retention times reduced by approximately 10% when compared to the chromatograms of H 2SO 4 spiked on filters impregnated with NaHCO 3[1]. REFERENCES: [1] Williamson, G.Y. NIOSH/MRSB Sequence 7452-B (unpublished, July 6, 1992). [2] Williamson, G.Y. NIOSH/MRSB Sequence 7452-C (unpublished, July 22, 1992). [3] NIOSH Manual of Analytical Methods, 2nd ed., Vol. 5, P&CAM 268, U.S. Department of Health and Human Services, Publ. (NIOSH) 79-141 (1979). [4] Ibid., 2nd ed., Vol. 1, P&CAM 146, Publ. (NIOSH) 77-157-A (1977). [5] Ibid., 2nd ed., Vol. 1, P&CAM 163, Publ. (NIOSH) 77-157-A (1977). [6] Ibid., 2nd ed., Vol. 4, S308, Publ. (NIOSH) 78-175 (1978). [7] Ibid., 2nd ed., Vol. 1, P&CAM 160, Publ. (NIOSH) 77-157-A (1977). [8] Ibid., 2nd ed., Vol. 1, P&CAM 204, Publ. (NIOSH) 77-157-A (1977). [9] Pate, J.B., J.P. Lodge, Jr., and M.P. Neary. The Use of Impregnated Filters to Collect Traces of Gases in the Atmosphere, Anal. Chim. Acta, 28:341 (1963). [10] Grote, A.A. (NIOSH, unpublished results, 1973). [11] Eller, P.M. and M.A. Kraus. Methods for the Determination of Oxidized Sulfur and Nitrogen Species in Air, Internal Report, (unpublished, July 29, 1977).
METHOD REVISED BY: Peter M. Eller, Ph.D., and Mary Ellen Cassinelli, NIOSH/DPSE.
NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94
