Page:NIOSH Manual of Analytical Methods - 6016.pdf/2

 AMMONIA by IC: METHOD 6016, Issue 1, dated 15 May 1996 - Page 2 of 4 REAGENTS:

EQUIPMENT:

1. Water, deionized, filtered. 2. Sulfuric acid (H2SO4), 0.01 N:* Add 0.28 mL conc. H2SO4 to 500 mL deionized water in 1-L volumetric flask. Dilute to 1 L with deionized water. 3. Hydrochloric acid (HCl), 1 N:* Add 82.5 mL conc. HCl to 500 mL deionized water in 1-L volumetric flask. Dilute to 1 L with deionized water. 4. 2,3-diaminopropionic acid monohydrochloride (DAP-HCl) 5. L-histidine monohydrochloride monohydrate (Lhistidine-HCl) 6. Eluent (48 mM HCl/4 mM DAP-HCl/4 mM L-histidine-HCl): Place 0.560 g DAP-HCl and 0.840 g L-histidine-HCl in a 1-L volumetric flask. Add 48 mL of 1 N HCl, dilute to volume with deionized water. Prepare monthly. 7. Alternate eluent (12 mM HCl/0.25 mM DAP-HCl/0.25 mM L-histidine-HCl): Dilute 252 mL strong eluent and 36 mL 1 N HCl to 4 L with deionized water. Prepare fresh for each use. 8. Tetramethylammonium hydroxide (TMAOH), 25%, (Aldrich Chemical Co. Milwaukee, WI). 9. Regenerant solution: Dilute 57.4 mL of 25% TMAOH to 4 L with deionized water. 10. Ammonia stock solution, 1000 µg/mL as NH3 (1059 µg/mL as NH4+): Dissolve 3.1409 g ammonium chloride in deionized water. Dilute to 1 L.

1. Sampler: a. Prefilter: 37-mm mixed cellulose ester membrane filter, 0.8-µm pore size, stainless steel or porous plastic screen in two piece cassette filter holder. b. Sulfuric acid-treated silica gel, glass tube, unsealed and fire-polished, 6.0 cm long, 6mm OD, 4-mm ID, containing two sections of 20/40 mesh sulfuric acid-treated silica gel (200 mg front/100 mg back) separated and held in place with plugs of silylated glass wool, and capped with plastic caps. Tubes are commercially available. 2. Personal sampling pump, 0.1 to 0.5 L/min, with flexible tubing. 3. Ion Chromatograph with conductivity detector, cation column and guard, and cation micromembrane suppressor (see p 6016-1). 4. Syringes, 10-mL, polyethylene, Luer tip. 5. Centrifuge tubes, 15-mL, graduated, plastic with screw caps. 6. Volumetric flasks, 10-, 50-, 100-mL, and 1-L. 7. Syringe filters, 13-mm, 0.8-µm, membrane filter. 8. Micropipets, disposable tips. 9. Analytical balance (sensitivity to 0.01 mg).

SPECIAL PRECAUTIONS:Concentrated acids are corrosive to skin. Handle acid in a fume hood. Wear protective gloves. SAMPLING: 1. 2. 3. 4.
 * See SPECIAL PRECAUTIONS

Calibrate each personal sampling pump with a representative sampler in line. Sample at an accurately known flow rate between 0.1 and 0.5 L/min for a total sample size of 0.1 to 96 L. Cap the sampling tubes with plastic (not rubber) caps immediately after sampling. Pack securely for shipment.

SAMPLE PREPARATION: 5. Remove caps from sampling tubes. Transfer the front and back sections of sulfuric acid-treated silica gel to separate 15-mL graduated centrifuge tubes. NOTE: Firm tapping of the tube may be necessary to effect complete transfer of the sulfuric acid-treated silica gel. 6. Add 10 mL of deionized water to each centrifuge tube. Cap and shake vigorously. Allow to stand 45 minutes with occasional shaking. (Desorption is complete in 45 minutes.) NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 5/15/96