Page:NIOSH Manual of Analytical Methods - 2503.pdf/2

 MEVINPHOS (PHOSDRIN): METHOD 2503, Issue 2, dated 15 August 1993 - Page 2 of 4 REAGENTS: 1. 2. 3.

4. 5. 6. 7.



EQUIPMENT:

Mevinphos, analytical grade.* Toluene, reagent grade. Calibration stock solution, 5 mg/mL. Dilute 50 mg of Mevinphos to 10 mL with toluene. Prepare in duplicate. Helium, purified. Hydrogen, prepurified. Air, filtered. Extracted resin. Chromosorb 102 20/40 mesh (Johns Manville Corp. or equivalent) extracted i n S o x h l e t a p p a r a t u s with 1:1 methanol:acetone solution for 2 hrs and dried at 115 °C under vacuum for 1 hr.

1. Sampler: glass tube, 10-cm long, 8-mm OD, 6-mm ID, flame sealed ends containing two sections of extracted resin (front = 100 mg; back = 50 mg) separated and retained by silylated glass wool plugs. Pressure drop across the tube at 1 L/min airflow must be less than 3.4 kPa. Tubes are commercially available. 2. Personal sampling pump, 0.2 to 1 L/min, with flexible connecting tubing. 3. Gas chromatograph, flame photometric detector with phosphorus filter, integrator and column (page 2503-1). 4. Vials, 2-mL, PTFE-lined caps. 5. Syringes, 1- to 100-µL. 6. Volumetric flasks, 10-mL. 7. Pipet, 1-mL, with pipet bulb.

See SPECIAL PRECAUTIONS.

SPECIAL PRECAUTIONS: Mevinphos is a cholinesterase inhibitor and can be absorbed through the skin. Wear protective gloves and suitable protective clothing when handling the pure material [1].

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 0.2 and 1 L/min for a total sample size of 15 to 240 L. Cap the samplers with plastic (not rubber) caps and 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 toluene to each vial. Attach cap to each vial. Allow to stand 30 min with occasional agitation.

CALIBRATION AND QUALITY CONTROL: 8.

Calibrate daily with at least five working standards over the range 0.2 to 55 µg Mevinphos per sample. a. Add known amounts of calibration stock solution to toluene in 10-mL volumetric flasks and dilute to the mark. b. Analyze together with samples and blanks (steps 11 and 12). c. Prepare calibration graph (peak area vs. µg Mevinphos).

NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/93