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These procedures were designed and tested for internal use by OSHA personnel. Mention of any company name or commercial product does not constitute endorsement by OSHA.
|OSHA Standard:||3.0 ppm Hydrogen Bromide, HBr
2.0 ppm Nitric Acid, HNO3
1.0 mg/m3 Phosphoric Acid, H3PO4
1.0 mg/m3 Sulfuric Acid, H2SO4
|Collection Procedure:||A known volume of air is drawn through a silica gel tube. H2SO4, H3PO4 and other particulates are collected on the glass fiber plug while HBr and HNO3 are collected on the silica gel sorbant.|
|Recommended Air Volume:||96 liters|
|Recommended Sampling Rate:||0.2 liters per minute|
|Analytical Procedure:||The glass fiber plug and the silica gel tubes are desorbed with standard eluent and analyzed by Ion Chromatography (IC).|
|Detection Limit||See Section 2.3.|
|Precision and Accuracy:||0.035 for HBr
0.037 for HNO3
0.066 for H3PO4
0.079 for H2SO4
|Date: December 1985|
Methods Development Team
Industrial Hygiene Chemistry Division
OSHA Salt Lake Technical Center
Sandy UT 84070-6406
This method describes the collection and analysis of airborne acids using Ion Chromatography. The method measures the total concentration of four airborne anions. The corresponding acids may be collected on a single sampler and determined simultaneously. Acids which can be collected and analyzed this way are HBr, H3PO4, HNO3, and H2SO4.
Prior to the use of this method, HBr was collected in 0.01 N NaOH, HNO3 was collected in deionized (DI) water, H2SO4 and H3PO4 were collected on 0.8 micron MCEF filters, and all were analyzed by IC.
Hydrogen bromide is used in the manufacture of organic and inorganic bromides and hydrobromic acid, as a reducing agent, and as a catalyst in controlled oxidations. HBr is also used in the alkylation of aromatic compounds, and in the isomerization of conjugated diolefins.
Most nitric acid is used in fertilizer as ammonium nitrate and in the manufacture of explosives. Nitric acid is also used in the synthesis of a large number of industrial organic compounds. Relatively small quantities of this acid are used for stainless steel pickling and metal etching, and to make rocket propellants.
Most phosphoric acid is used as ammonium phosphate in fertilizer and in the manufacture of superphosphates. Phosphoric acid is also used in rustproofing, electropolishing, engraving, lithographic work, coagulation of rubber latex, as an additive in glass manufacture, and as a catalyst in the manufacture of some pharmaceuticals.
Sulfuric acid is used in the fertilizer industry for the production of superphosphates and ammonium sulfate. The chemical industry consumes sulfuric acid in the manufacture of phosphoric acid by the wet process. Sulfuric acid is used in the manufacture of paper and aluminum sulfate, and is used extensively for water purification. The petroleum industry uses sulfuric acid in the alkylation process and in the refining of petroleum distillates for removal of sulfur and gum-forming compounds. Other important industrial applications consuming large amounts of sulfuric acid include steel pickling and the manufacture of titanium pigments, rayon, dyes, intermediates, and detergents.
Hydrogen bromide is a colorless, corrosive, nonflammable gas with an acrid odor. HBr fumes in moist air forming clouds which have a sour taste. Commercial grades are approximately 48% pure.
Nitric acid is a colorless liquid (depending upon purity and freshness). The acid produces fumes in moist air and has a strong choking odor. Long exposure to light causes nitric acid to beccme discolored (brownish). Commercial grades are approximately 70 - 71% pure.
Phosphoric acid is a dense, colorless liquid which is toxic and is a strong irritant to tissue.
Sulfuric acid is a dense oily liquid, colorless to dark brown (depending on purity). Commercial grades are approximately 96% pure. Sulfuric acid is a strong oxidant, which is toxic, a strong irritant to tissue, very corrosive, and has a great affinity for water.
315 - 338°C
|PO4-3||= 0.25 ug|
|Br -||= 0.20 ug|
|NO3-||= 0.125 ug|
|SO4=||= 0.25 ug|
These detection limits were calculated based on a sample volume of 10 mL and an injection volume of 100 uL. The detection limits for each analyte were calculated in the presence of the other three analytes. The detection limit may be improved by using a larger injection volume (for auto sampler only), or by using a smaller volume than 10 mL to desorb the sample.
Sensitivity: 30 umho full scale
Eluent: 0.003 M Na2CO3 and 0.0024 M NaHCO3
Flow Rate: 138 mL/hr approximately 30% on vernier
Concentrator Column: 3 mm I.D. × 50 mm
Anion Separator Column: 3 mm I.D. × 250 mm
Suppressor Column: 10 mm I.D. × 100 mm
Run Time: Approximately 30 minutes, depending upon analytical conditions.
The blank corrected sample values are then calculated using the Auto Colorimetric Program.
Sample Number, Peak Area or Height, L Air Volume, mL Solution Volume, mL Aliquot Volume.
(µg calculated)(mL sample vol)(GF*)(dilution factor)
(liters of air)(mL aliquot)
GF* = Gravimetric Factor =
|1.013 for HBr
1.016 for HNO3
1.021 for H2SO4
1.032 for H3PO4
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