Page:NIOSH Manual of Analytical Methods - 2004.pdf/3

 DIMETHYLACETAMIDE and DIMETHYLFORMAMIDE: METHOD 2004, Issue 2, dated 15 August 1994 - Page 2 of 4

REAGENTS: 1. 2. 3. 4.

5. 6. 7.

EQUIPMENT:

Methanol, reagent grade.* Analyte: dimethylacetamide, reagent grade, or dimethylformamide, reagent grade.* Acetone, reagent grade.* Desorption efficiency (DE) stock solution, 0.05 mg/mL. Prepare solutions of dimethylacetamide or dimethylformamide fresh daily in acetone. Hydrogen, prepurified. Air, filtered, compressed. Nitrogen, purified.
 * See SPECIAL PRECAUTIONS.

1. Sampler: glass tube, 7 cm long, 6-mm OD, 4-mm ID, with plastic caps, containing two sections of 20/40 mesh silica gel (front = 150 mg; back = 75 mg) separated by a 2-mm urethane foam plug. A silylated glass wool plug precedes the front section and a 3-mm urethane foam plug follows the back section. The pressure drop across the tube must be less than 3.4 kPa (2.5 cm Hg) at an airflow of 1 L/min. Tubes are commercially available. 2. Personal sampling pump, 0.01 to 1 L/min, with flexible connecting tubing. 3. Gas chromatograph, FID, integrator, and column (page 2004-1). 4. Vials, 2-mL, PTFE-lined crimp cap, or automatic sampler vials. 5. Microliter syringes, 10-µL and other convenient size for making standards. 6. Pipets, 1.0 mL. 7. Volumetric flasks, 10-mL. 8. Ultrasonic bath.

SPECIAL PRECAUTIONS: Acetone and methanol are flammable and a dangerous fire and explosion risk. They are moderately toxic by ingestion and inhalation. Dimethylacetamide and dimethylformamide are strong irritants to skin and tissue and moderate fire risks. SAMPLING: 1. 2. 3. 4.

Calibrate each personal sampling pump with a representative sampler in line. Break ends of sampler immediately before sampling. Attach sampler to personal sampling pump with flexible tubing. Sample at an accurately known flow rate between 0.01 to 1 L/min for a total sample size of 15 to 80 L. Cap the samplers. Pack securely for shipment.

SAMPLE PREPARATION: 5. 6. 7.

Place the front and back sorbent sections of the sampler tube in separate vials. Discard the glass wool and foam plugs. Add 1.0 mL methanol to each vial. Attach crimp cap to each vial. Agitate for 60 min in an ultrasonic bath.

CALIBRATION AND QUALITY CONTROL: 8.

Calibrate daily with at least six working standards over the ranges 0.05 to 4 mg dimethylacetamide or dimethylformamide per sample. a. Add known amounts of analyte (neat or diluted with methanol) to methanol in 10-mL volumetric flasks and dilute to the mark. NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94