Page:NIOSH Manual of Analytical Methods - 2524.pdf/2

 DIMETHYL SULFATE: METHOD 2524, Issue 2, dated 15 August 1994 - Page 2 of 4 REAGENTS: 1. 2. 3.

4.

EQUIPMENT:

Dimethyl sulfate, 99%.* Diethyl ether,* anhydrous, preserved with ethanol. Calibration stock solution, 12 µg/µL. Add 120 mg (90 µL) dimethyl sulfate to a pre-weighed 10-mL volumetric flask. Re-weigh and dilute to the mark with diethyl ether. Helium, purified.



See SPECIAL PRECAUTIONS.

1. Sampler: glass tube, 7 cm long, 6-mm OD, 4-mm ID, flame-sealed ends with plastic caps, containing two sections of 50/80 mesh Porapak P (front = 100 mg; back = 50 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. Pressure drop across the tube at 0.2 L/min airflow must be less than 3.4 kPa. Tubes are commercially available. NOTE: Some batches of Porapak P initially gave poor recovery. Good recoveries were obtained after the sorbent had been heated at 180 °C in a vacuum oven for 16 hrs. 2. Personal sampling pump, 0.01 to 0.2 L/min, with flexible connecting tubing. 3. Gas chromatograph, electrolytic conductivity detector (sulfur mode), integrator, and column (see page 2524-1). NOTE: A new column must be primed before attempting quantitative work by repeatedly injecting aliquots of calibration stock solution until the detector response to dimethyl sulfate reaches a plateau. 4. Vials, 2-mL, PTFE-lined crimp caps. 5. Syringes, 10-µL and other convenient sizes for preparing standards, readable to 0.1-µL. 6. Volumetric flasks, 10-mL. 7. Pipets, 1-mL.

SPECIAL PRECAUTIONS: Dimethyl sulfate is a suspect carcinogen, and both the liquid and vapor are extremely severe irritants to skin, eyes, and mucous membranes. It is an insidious hazard -- warning properties are poor and symptoms are delayed up to 10 h or more [3,4]. All transfers involving dimethyl sulfate should be performed in a fume hood. Personal protective equipment should be used to prevent any bodily exposure even to the vapor. Diethyl ether is an extreme fire (flash point = -45 °C) and explosion hazard (possible peroxide formation); work with it only in a hood.

SAMPLING: 1. 2. 3. 4.

Calibrate each personal sampling pump with a representative sampler in line. Break the ends of the sampler immediately before sampling. Attach sampler to personal sampling pump with flexible tubing. Sample at an accurately known flow rate between 0.01 and 0.2 L/min for a total sample size of 0.25 to 12 L. Cap the samplers. Pack securely for shipment.

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