Page:NIOSH Manual of Analytical Methods - 5005.pdf/2

 THIRAM: METHOD 5005, Issue 2, dated 15 August 1994 - Page 2 of 3 REAGENTS: 1. 2. 3. 4. 5.

EQUIPMENT:

Acetonitrile, HPLC grade.* Water, distilled, deionized. Thiram, reagent grade.* Air or nitrogen, compressed, for drying syringes. Calibration stock solution, 0.75 mg/mL. Dissolve an accurately weighed 7.5 mg Thiram in acetonitrile and dilute to 10 mL. Prepare fresh daily in duplicate.



See SPECIAL PRECAUTIONS.

1. Sampler: 1-µm PTFE membrane filter (Millipore FA or equivalent), 37-mm diameter, two-piece polystyrene cassette filter holder with backup pad, sealed with tape or a shrinkable band. Filter holders made of Tenite should not be used. 2. Personal sampling pump, 1 to 4 L/min, with flexible connecting tubing. 3. Liquid chromatograph, UV detector at 254 nm,integrator and column (page 5005-1). 4. 13 mm x 5 µm PTFE filters and stainless steel filter holder to protect the LC column. 5. Vials, 20-mL, glass, PTFE-lined screw caps. 6. Syringe, 1-mL, with Luer-Lok fitting. 7. Pipets, 10-mL, with pipet bulb. 8. Tweezers. 9. Volumetric flasks, 10-mL.

SPECIAL PRECAUTIONS: Acetonitrile is toxic and flammable; work with it only in a hood. Thiram is an irritant of skin and mucous membranes, a skin sensitizer, and suspected teratogen [5].

SAMPLING: 1. 2. 3.

Calibrate each personal sampling pump with a representative sampler in line. Sample at 1 to 4 L/min for a total sample size of 10 to 400 L. Do not exceed 2 mg total dust loading on the filter. Collect a bulk sample (1 to 5 g) in a glass vial with PTFE-lined cap; ship separately from filters.

SAMPLE PREPARATION: 4. 5. 6. 7.

Remove filter from cassette with tweezers and place in 20-mL vial. Add 10 mL acetonitrile. Cap the vial. Rinse the inside top of cassette with 10 mL acetonitrile into a 20-mL vial. Cap the vial. Agitate samples during the 30-min desorption period.

CALIBRATION AND QUALITY CONTROL: 8.

Calibrate daily with at least six working standards over the range 0.005 to 3 mg Thiram per sample. a. Add known amounts of calibration stock solution to acetonitrile in 10-mL volumetric flasks and dilute to the mark. b. Analyze together with samples and blanks (steps 9 and 10). c. Prepare calibration graph (peak area vs. mg Thiram).

MEASUREMENT: 9. 10.

Set liquid chromatograph to conditions on page 5005-1. Inject 10-µL sample aliquot. Rinse and dry syringe between injections. Measure peak area. NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94