Page:NIOSH Manual of Analytical Methods - 6015.pdf/3

 AMMONIA: METHOD 6015, Issue 2, dated 15 August 1994 - Page 3 of 7 SPECIAL PRECAUTIONS: Phenol is both corrosive and poisonous from ingestion, inhalation, or absorption through the skin [10]. Avoid skin contact and inhalation of vapors. Sodium hydroxide, sulfuric acid, and sodium hypochlorite (bleach) are all corrosive. Avoid contact with skin or inhalation of vapors. Chloroform is believed to be carcinogenic [10], with reports of mutagenic and teratogenic effects in animals. Handle in a hood and avoid skin contact. Sodium nitroprusside (sodium nitroferricyanide) is highly toxic. Use extreme caution to avoid ingestion or inhalation of dust.

SAMPLING: 1. 2. 3. 4.

Calibrate each personal sampling pump with a representative sampler in line. Sample at an accurately known flow rate between 0.1 and 0.2 liter/minute 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.

6.

Remove the plastic caps. Transfer the front and back sections of sulfuric acid-treated silica gel to separate 80-mL vials. Discard glass wool plugs. Analyze the two sections separately. NOTE: Firm tapping of the tube may be necessary to effect complete transfer of the sulfuric acid-treated silica gel. Add 20 mL of ammonia-free deionized water to each vial. Cap and shake vigorously. Desorption is complete in 45 minutes. Adjust the pH of each sample to 5.0 to 6.5 with sodium hydroxide. NOTE: Analyses should be completed within one day after the ammonia is desorbed.

CALIBRATION AND QUALITY CONTROL: 7.

Calibrate daily with at least six working standards over the range 0.05 to 1 µg/mL. Using the stock solution, prepare standards such as the following in 100-mL volumetric flasks (prepare fresh daily): a. Add known amounts of calibration stock solution to deionized water in 100-mL volumetric flasks and dilute to the mark. Prepare fresh daily. NH 3, µg/mL

mL Stock Solution/100 mL

0.05 0.10 0.20 0.40 0.80 1.00

0.05 0.10 0.20 0.40 0.80 1.00

b. c. 8.

Analyze working standards together with samples and blanks (steps 9 through 12). The instrument automatically generates calibration graph (peak height versus concentration). Sample concentrations will be printed out directly from this graph. Analyze three quality control blind spikes and three analyst spikes to ensure that the calibrating graph is in control.

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