Page:NIOSH Manual of Analytical Methods - 5514.pdf/2

 DEMETON: METHOD 5514, Issue 2, dated 15 August 1994 - Page 2 of 4 REAGENTS: 1. 2. 3. 4. 5.

6. 7. 8. 9.

EQUIPMENT:

Demeton O/Demeton S mixture of known concentration, reagent grade.* Toluene, reagent grade. Methanol, reagent grade. Methylene chloride, reagent grade. Calibration stock solution, ca. 2.4 mg/mL Demeton O and 8.3 mg/mL Demeton S. Dilute 100 µL of commercially available mixture to 10 mL with toluene. Hydrogen, prepurified. Nitrogen, purified. Oxygen, purified. Air, purified.

See SPECIAL PRECAUTIONS.

1. Sampler: cellulose ester membrane filter, 0.8-µm pore size, 37-mm diameter, supported by a stainless steel screen in a polystyrene cassette filter holder followed by a tube, 7 cm long, 8-mm OD, 6-mm ID, packed with two sections (front = 150 mg; back = 75 mg) of 20/50 mesh XAD-2. Two plastic plugs are required for capping the tube after sampling. Tubes are commercially available. (SKC, Inc. 226-30-05, or equivalent). 2. Personal sampling pump, 0.2 to 1 L/min, with flexible connecting tubing. 3. Vial, scintillation, with PTFE-lined cap, graduated at 15 mL. 4. Gas chromatograph with phosphorus-sensitive FPD, integrator, and column (page 5514-1). 5. Syringes, 5-, 10- and 25-µL, for making standard solutions and GC injections. 6. Volumetric flasks, 10-mL. 7. Pipets, 5-mL. 8. Tweezers.

SPECIAL PRECAUTIONS: Demeton is a cholinesterase inhibitor and readily absorbed through the skin; baseline and routine red blood cell cholinesterase monitoring is recommended [3,4].

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

Calibrate each personal sampling pump with a representative sampler in line. Break ends of tubes immediately before sampling. Attach filter cassette to inlet of XAD-2 tube with short piece of tubing. Connect the outlet of sampler to pump. Sample at an accurately known flow rate between 0.2 and 1 L/min for a total sample size of 30 to 500 L. Transfer the filter, the front glass wool plug, and the front sorbent section to the same vial. Cap the tube containing the back sorbent section. Pack the samples securely for shipment.

SAMPLE PREPARATION: 6. 7. 8.

Place the back sorbent section of the XAD-2 tube in a separate vial. Discard the remaining glass wool plugs. Add 5.0 mL toluene to each vial. Cap each vial. Allow to stand 15 min with occasional agitation. Analyze within one day.

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