Page:NIOSH Manual of Analytical Methods - 6015.pdf/2

 AMMONIA: METHOD 6015, Issue 2, dated 15 August 1994 - Page 2 of 7 REAGENTS:

EQUIPMENT:

1. Water, distilled and deionized. Special precaution must be taken to ensure that distilled water is free of ammonia, by passing it through an ion exchange column comprised of a mixture of both strongly acidic cation and strongly basic anion exchange resins. Regenerate the ion exchange column according to the instructions of the manufacturer. NOTE: All solutions must be made using ammonia-free water. 2. Sulfuric acid, conc., reagent grade. 3. Phenol. 4. Sodium hydroxide, reagent grade. 5. Brij-35. 6. Ammonium chloride. 7. Chloroform. 8. Sulfuric acid 5 N. Air scrubber solution (AAII). Carefully add 140 mL of concentrated sulfuric acid to approximately 500 mL of ammonia-free distilled water. Cool to room temperature and dilute to 1 L with ammonia-free water. 9. Sodium phenolate. In a 1-liter flask, dissolve 83 g phenol (or 80 mL 90% liquid phenol) in 500 mL distilled water. In small increments, cautiously add with agitation, 32 g NaOH (96 g 50% NaOH for TRAACS). Periodically cool flask under water faucet. When cool, dilute to 1 L with distilled water. Filter if necessary. Store in amber glass bottle. For AAII add 0.5 mL Brij-35. 10. Sodium hypochlorite solution: Dilute one volume of a bleach solution containing 5.25% NaOCl (such as "Clorox") with an equal volume of deionized water. Available chlorine level should approximate 2 to 3%. 11. Disodium ethylenediamine-tetraacetate (EDTA) (5%): Dissolve 50 g EDTA (disodium salt) and six pellets NaOH in 1 L of deionized water. (For TRAACS, dissolve 41 g EDTA, 1 g 50% NaOH, and 3-6 mL Brij-35.) 12. Sodium nitroprusside (0.05% Na 2Fe(CN) 5NO · 2H 2O): Dissolve 0.5 g sodium nitroprusside in 1 L deionized water (or 1.1 g for TRAACS). NOTE: Sodium nitroprusside solution is lightsensitive. Store in and use from a brown bottle. 13. Calibration stock solution (100 mg NH 3/L): Dissolve 0.3144 g anhydrous ammonium chloride, NH 4Cl, dried at 105 °C, in deionized water, and dilute to 1 L. Add 1 mL chloroform as a preservative.

1. Sampler: a. Prefilter (to remove particulate interferences): 37-mm cellulose ester membrane filter (0.8-µm pore size) supported by stainless steel screen in two piece cassette filter holder. b. Sulfuric acid-treated silica gel sampling tubes. Glass tube with both ends unsealed and fire-polished, 6.0 cm long with a 6-mm O.D. and a 4-mm I.D. containing two sections of 20/40 mesh sulfuric acid-treated silica gel (200 mg front/100 mg back) separated by a 2-mm portion of glass wool. Plugs of silylated glass wool are placed at the ends of the tube. The pressure drop across the tube must be <13 inches of water at a flow rate of 0.2 L/min (see APPENDIX). The glass tubes should be rinsed and dried with acetone before packing. The tubes are capped with plastic caps. Tubes are commercially available. 2. Personal sampling pump calibrated, 0.1 to 0.2 L/min, with flexible tubing. 3. Technicon AutoAnalyzer Unit (AAII) (or TRAACS 800 equivalent) consisting of an autosampler, and analytical cartridge (AAII), proportioning pump, colorimeter equipped with 15-mm, 30-mm, or 50-mm tubular flow cell and 630- to 660-nm filters, a data collection system, and recorder. 4. pH Meter and pH electrode. 5. Plastic vials, 80-mL or 50-mL. 6. Polyethylene centrifuge tubes. 7. Magnetic stirrer and stirring bars. 8. Pipets: delivery type of convenient sizes. 9. Volumetric flasks: 1-L and 50-mL and other convenient sizes for preparing standard solutions. 10. Stopwatch. 11. Manometer.

NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94