Page:NIOSH Manual of Analytical Methods - 3511.pdf/2

 MONOMETHYLANILINE: METHOD 3511, Issue 1, dated 15 August 1994 - Page 2 of 3 EQUIPMENT:

REAGENTS: 1. 2. 3. 4.

Monomethylaniline *, ACS reagent grade. Sulfuric acid, 0.05 M, ACS reagent grade. Sodium hydroxide,* 4 M. Calibration stock solution.

See Special Precautions

1. Sampler: Midget bubbler containing 10 mL 0.05 M sulfuric acid. 2. Personal sampling pump, 0.2 to 1 L/min, with flexible polyethylene or PTFE tubing. 3. pH paper or meter 4. Vials, glass, 20-mL with PTFE-lined caps. 5. Gas chromatograph with a flame ionization detector, recorder, integrator and column (page 3511-1). 6. Graduated cylinders, 10-mL 7. Syringes, 10- and 500-µL. 8. Volumetric flasks, 10-mL. 9. Pipets, 1- and 10-mL glass, delivery, with pipet bulb.

SPECIAL PRECAUTIONS: Monomethylaniline is toxic by inhalation, ingestion, and skin absorption [3,4]. Sodium hydroxide is corrosive to tissue. Wear gloves and work in a hood.

SAMPLING: 1. 2. 3. 4. 5. 6.

Calibrate each personal sampling pump with a representative sampler in line. Attach outlet of impinger to the sampling pump. Place an empty bubbler or impinger in line behind the sampler to catch any splashover during sampling. Sample 11 to 100 L of air at an accurately known flow rate in the range 0.2 to 1.0 L/min. The temperature and pressure of the atmosphere being sampled should be recorded. Transfer samples to 20 mL vial for shipping. Place in a suitable shipping container to prevent damage or spilling during transit. Collect a bulk sample (ca. 1 g) in a glass vial and ship it separately.

SAMPLE PREPARATION: 7. 8. 9.

Bring the volume of each sample to 10 mL with 0.05 M sulfuric acid. Add 1 mL 4 M sodium hydroxide and mix thoroughly. The pH of the resulting solution should be greater than 10. Analyze sample immediately to avoid loss of amine as the free base.

CALIBRATION AND QUALITY CONTROL: 10.

11.

Prepare at least six working standards (0 to 300 µg/ mL of monomethylaniline). a. Add appropriate aliquots of calibration stock solution to 0.05 M sulfuric acid. Follow neutralization procedure as in step 8. b. Analyze working standards together with samples and blanks (steps 13 through 15). c. Prepare a calibration graph of area vs. amount of monomethylaniline, µg per mL. Determine recovery for each batch of sulfuric acid made up in the concentration range of interest. Prepare four 10 mL portions of sulfuric acid at each of five monomethylaniline levels plus three media blanks. a. Put a 10 mL portion of sulfuric acid in a 20-mL vial. b. Spike aliquot of calibration solution into 10 mL of 0.05 M sulfuric acid with a microliter syringe. c. Cap and let stand overnight. NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94