NIOSH nitrogen

Incineration or heating to decomposition releases toxic nitrogen oxides (Sittig, 1985) and cyanides (Lewis, 1990). Wet oxidation of acrylonitrile at 320 °C yielded formic and acetic acids (Randall and Knopp, 1980). Polymerizes readily in the absence of oxygen or on exposure to visible light (Windholz et al., 1983). If acrylonitrile is not inhibited with methylhydroquinone, it may polymerize spontaneously or when heated in the presence of alkali (NIOSH, 1997). 

Occupational Exposure to Oxides of Nitrogen (Nitrogen Dioxide and Nitric Oxide). DHEW (NIOSH) Pub No 76-149, pp 46-50, 75-76. Washington, DC, US Government Printing Office, 1976... 

U.S. EPA Method TO7 describes the determination of N-nitrosodimethylamine in ambient air (U.S. EPA, 1986). The method is similar to the NIOSH method discussed above and uses Thermosorb/N as adsorbent. The air flow is 2 L/min and the sample volume recommended is 300 L air. The analyte is desorbed with methylene chloride and determined by GC/MS or an alternate selective GC system, such as TEA, HECD, or thermoionic nitrogen-selective detector. The latter detector and the TEA are more sensitive and selective than the other detectors. Therefore, the interference from other substances is minimal. Other nitrosamines in air may be determined in the same way. 

The column used in NIOSH study is a 2 mm ID packed glass column containing 1.5% OV-17 plus 1.95% QF-1 on 80/100 mesh Chromosorb WHP. Other equivalent column may be used. The flow rate of carrier gas nitrogen may be set at 40 to 50 mL/min (on a packed column). 

Separation of hydrazine and dimethylhydrazines from environmental samples is by acid extraction when necessary. Air samples are usually collected in a bubbler with acid or on an acid-coated silica gel (NIOSH 1977a, 1977b, 1984). When GC is employed, detection may be by electron capture detector (ECD), FID, nitrogen-specific detector (NSD), thermionic ionization detector (TID), and/or MS as described above (Section 6.1). 

Methods for Determining Parent Compounds and Degradation Products in Environmental Media. Methods for determining ammoniacal nitrogen in environmental media are well developed and adequate. Standardized methods are available from EPA, NIOSH, and other sources. Analytical methods are also well developed for oxidation products of ammonia. Since there are multiple sources of these compounds in the environment, their analysis is not generally used to study the disappearance of ammonia. 

NIOSH Pocket Guide to Chemical Hazards Nitrogen Dioxide. Occupational Health Safety Administration. http //www.cdc.gov/niosh/npg/npgdo4g4.html (accessed on October 20, 2005). 

Sodium hydroxide solutions are tested for their total alkalinity by titration with standard acid. Alkaline dusts in air may be estimated by flowing air through a 1-mm poly(tetrafluoroethylene) membrane filter, extracting the hydroxides with 0.01 N HCl under nitrogen, followed by acid-base titration using a pH electrode (NIOSH 1984, Method 7401). This method also measures the total alkaline dusts in air that includes caustic potash. 

Analysis of dimethyl- and diethylamine in air may be performed in accordance to NIOSH Method 2010 (NIOSH 1984, Suppl. 1989). About 3-30 L of air at a fiow rate of 10-1000 mL/min is passed through a silica gel (20/40 mesh, 150 mg front and 75 mg back) sorbent tube. The analytes are desorbed with dilute sulfuric acid in 10% aqueous methanol (3-h ultasonication) and injected into a GC equipped with a FID. A packed column, 4% Carbowax M over 0.8% KOH on Carbosieve B (60/80 mesh) was used in the NIOSH laboratory. A nitrogen-specific detector may be used for amine analysis instead of an FID, using a DB-5 fused-silica capillary column. This method may be applied for the analyses of other aliphatic amines in air and also for certain ethanolamines (NIOSH 1984, Suppl. 1989, Method 2007). Alternatively, ethanolamines may be analyzed by NIOSH Method 3509 (NIOSH 1984, Suppl. 1989). These compounds present in air (5-300 L of air) are... 

About 10-30 L of air at a flow rate of 20-200 mL/min is passed over a silica gel sorbent tnbe, desorbed with 95% ethanol for 1 honr in an ultrasonic bath, and injected into a GC eqnipped with an FID. Chromosorb 103 (80/100 mesh) is snitable for the pnrpose. A nitrogen-specific GC detector may be used instead of an FID. Anisidines in air (25-300 L at a flow rate of 500-1000 mL/min) may be collected over a XAD-2 solid sorbent tube, desorbed with 5 mL of methanol, and analyzed by HPLC, UV detection at 254 nm (NIOSH 1984, Method 2514). A stainless steel-packed colnmn containing Bondapak C or eqnivalent is snitable for the pnrpose. o-Tolidine and o-dianisidine in air may be analyzed by an HPLC-UV technique similar to benzidine by NIOSH (1984) Method 5013 (see Section 9.14). 

Hydrazine in air may be analyzed by NIOSH Method 3503. About 10-100 L of air at a flow rate of 0.2-1 L/min is passed through a bubbler containing 0.1 M HCl. The analyte is complexed with p-dimethylaminobenzalde-hyde and is measured by visible absorption spectrophotometry at a wavelength of 480 nm. It may also be determined by a GC method using a nitrogen-phosphorus detector in the nitrogen mode, or by a flame ionization detector. 

Benzidine (p-dlaminodiphenyl [CAS 92-87-5]) Extremely well absorbed by inhalation and through skin. Causes bladder cancer in exposed workers (lARC 1). S,A1 OSHACA NIOSH CA White or reddish solid crystals. Breakdown products include oxides of nitrogen. Found in dye-stuffs, mb-ber industry, and analytical laboratodes. 

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