Page:NIOSH Manual of Analytical Methods - 2534.pdf/2

 TETRAMETHYL LEAD (as Pb): METHOD 2534, Issue 2, dated 15 August 1994 - Page 2 of 4 REAGENTS: 1. 2. 3.

EQUIPMENT:

Pentane (reagent grade). Tetramethyl lead.* Calibration stock solution, 0.4 mg/mL (as Pb). Dissolve 5.16 mg tetramethyl lead (ca. 2.6 µL) in pentane to make 10 mL solution. Prepare in duplicate.



See SPECIAL PRECAUTIONS.

1. Sampler: glass tube, 10 cm long, 8-mm OD and 6-mm ID, with plastic caps, containing two sections of 20/50 mesh XAD-2 resin (front = 400 mg, back = 200 mg), separated and contained by silylated glass wool plugs. Pressure drop <3.4 kPa @ 1 L/min airflow. Tubes are commercially available (SKC, Inc. ST226-30-06). 2. Personal sampling pump, 0.01 to 0.2 L/min, with flexible connecting tubing. 3. Gas chromatograph with photoionization detector, integrator, and column (page 2534-1). 4. Vials, 4-mL, glass, and PTFE-lined caps. 5. Volumetric flasks, 10-mL. 6. Syringe, 10-µL, readable to 0.1 µL. 7. Pipets, 1- and 2-mL.

SPECIAL PRECAUTIONS: Tetramethyl lead is extremely poisonous with delayed symptoms [3]. Acute or chronic poisoning may occur if inhaled or absorbed through skin.

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 15 to 100 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 2.0 mL pentane to each vial containing 400 mg sorbent, and 1.0 mL pentane to each vial containing 200 mg sorbent. Cap each vial. NOTE: A suitable internal standard (e.g., 0.1% v/v nonane) may be added to samples and blanks at this step [1]. Allow to stand 30 min with occasional agitation.

CALIBRATION AND QUALITY CONTROL: 8.

9.

Calibrate daily with at least six working standards. a. Add known amounts of calibration stock solution to pentane in 10-mL volumetric flasks and dilute to the mark. Use serial dilutions as needed to obtain tetramethyl lead concentrations in the range 0.2 to 5 µg/mL (as Pb). b. Analyze with samples and blanks (steps 11 and 12). c. Prepare calibration graph [peak area or peak height vs. µg tetramethyl lead (as Pb)]. Determine desorption efficiency (DE) at least once for each lot of sorbent used for sampling in the range of interest. Prepare three tubes at each of five levels plus three media blanks. NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94