NON-VOLATILE ACIDS (Sulfuric Acid and Phosphoric Acid): METHOD 7908, Issue 1, dated 20 May 2014 - Page 4 of 5
V = volume, in mL, of the sample test solutions 1 Fd = dilution factor for each sample test solution Fc = conversion factor to convert from anion to acid concentration: Fc = 1.021 for sulfate; Fc = 1.031 for phosphate EVALUATION OF METHOD: Laboratory testing with generated atmospheres of sulfuric acid mist yielded a collection efficiency of greater than 95% over the range 0.5 to 10 mg/m3 of H2SO4 on 0.45 µm pore size PTFE filters [4]. Greater than 95% recovery of sulfuric acid and phosphoric acid was found four weeks after sample collection. On quartz fiber filters, 97 to 100% recovery of sulfuric acid was found four weeks after sample collection, and no breakthrough was observed at sample loadings of up to 1 mg [3]. Mean analytical recovery determined from the analysis of spiked quartz fiber filters has been found to be in the range of 97 to 100% for both acids [3,4]. The component of the coefficient of variation of the method that arises from analytical variability, determined from the analysis of spiked quartz fiber filters, was 0.7% to 3.2% for phosphoric acid and 0.5% to 2.6% for sulfuric acid [3]. An interlaboratory study with 26 participants found negligible biases and interlaboratory relative standard deviations of 12 to 15% for sulfuric acid and phosphoric acid concentrations between 0.05 and 1 mg/m3 [12]. The method has also been field tested for sulfuric acid measurements at sample volumes of up to nearly 2,000 Liters [13]. The analytical figures of merit for the method satisfy performance criteria specified in an applicable consensus standard [14]. The back-up data and user check reports are references 4 and 12 respectively. REFERENCES: [1] ACGIH [2013]. TLVs and BEIs based on the documentation of the Threshold Limit Values for chemical substances and physical agents and Biological Exposure Indices. Cincinnati, Ohio: American Conference of Governmental Industrial Hygienists. [www.acgih.org]. [Data accessed April 2014.] [2] Institut fur Arbeitsschutz der Deutschen Gesetzlichen Unfallversicherung [2013]. GESTIS database on international limit values for hazardous substances (German Social Accident Insurance). Sankt Augustin, FRG: [http://www.dguv.de/ifa/Gefahrstoffdatenbanken/GESTIS-Stoffdatenbank/index-2. jsp]. [Data accessed April 2014.] [3] Breuer D [2002]. Inorganic acid mists (H2SO4, H3PO4). In: Kettrup A, Greim H, eds. Analyses of hazardous substances in air (Deutsche Forschungsgemeinschaft). Vol. 6. Weinheim, FRG: Wiley-VCH. pp. 67-78. [4] Breuer D [1999]. Measurement of vapor-aerosol mixtures. J Environ Monit. 1:299-305. [5] ISO (International Organization for Standardization) [1995]. ISO Guide 98: Guide to the expression of uncertainty in measurement. Geneva, Switzerland: ISO. [6] ISO [2007]. ISO 21438-1: Workplace atmospheres – Determination of inorganic ions by ion chromatography – Part 1: Non-volatile acids (sulfuric acid and phosphoric acid). Geneva, Switzerland: International Organization for Standardization (ISO). [7] Breuer D [2013]. Anorganische säuren, partikulär: phosphorsäure, schwefelsäure (Inorganic acid mists: phosphoric acid, sulfuric acid), in IFA Working Folder, Sheet No. 6173. Berlin, FRG: ErichSchmidt Verlag. ISBN 978-3-503-13084-9. [8] NIOSH [1994]. Acids, inorganic: Method 7903. In: Eller PM, Cassinelli ME, eds. NIOSH Manual of analytical methods, 4th ed., Cincinnati, OH: U.S. Department of Health and Human Services, Center for Disease Control and Prevention, National Institute for Occupational Safety and Health, DHHS (NIOSH). Publication No. 94-113. [www.cdc.gov/niosh/nmam.] [9] NIOSH [2005]. NIOSH Pocket guide to chemical hazards. Barsan ME, ed. Cincinnati, OH: US Department of Health and Human Services, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, DHHS (NIOSH) Publication No. 2005-149.
NIOSH Manual of Analytical Methods (NMAM), Fifth Edition
