Page:NIOSH Manual of Analytical Methods - 5008.pdf/2

 PYRETHRUM: METHOD 5008, Issue 2, dated 15 August 1994 - Page 2 of 4 REAGENTS: 1.

2. 3. 4. 5.

EQUIPMENT:

Pyrethrum*, analytical standard solution(McLaughlin Gormley King Co., Minneapolis, MN; Chem Service, Inc., West Chester, PA; or other supplier). NOTE: Store away from direct light. Active constituents of pyrethrum oxidize in air and photodecompose. Acetonitrile, HPLC grade.* Water, HPLC grade. Isopropanol. Calibration stock solution,* 60 mg/mL, in isopropanol.



1.

2. 3.

4. 5. 6. 7. 8. 9.

Sampler: 37-mm glass fiber filter and cellulose backup pad in filter holder held together with tape or shrinkable band. Personal sampling pump, 1 to 4 L/min, with flexible connecting tubing. High pressure liquid chromatograph with UV absorption detector at 225 nm, integrator and column (page 5008-1). Ointment jars, 2-oz, squat form, with PTFE-lined screw caps. Tweezers. Pipet, TD, 10-mL, with pipet bulb. Volumetric flasks, 10-mL. Syringe, 10-mL, with syringe filter. Syringes or pipets, 5- to 100-µL.

See SPECIAL PRECAUTIONS.

SPECIAL PRECAUTIONS: Acetonitrile and pyrethrum solutions are toxic and flammable. Use gloves, goggles and other appropriate equipment to prevent eye contact or repeated and prolonged skin contact [5]. Wash skin and change clothes if contact occurs. Use in fume hoods and away from ignition sources.

SAMPLING: 1. 2.

Calibrate each personal sampling pump with a representative sampler in line. Sample at an accurately known flow rate between 1 and 4 L/min for a total sample size of 20 to 400 L.

SAMPLE PREPARATION: 3. 4. 5.

Transfer the filter carefully to an ointment jar using tweezers. Add 10.0 mL acetonitrile. Seal and gently swirl the jar to wet the filter. Let stand 30 min with occasional swirling. Filter the sample solution through a syringe filter.

CALIBRATION AND QUALITY CONTROL: 6.

7.

Calibrate daily with at least six working standards over the range 0.01 to 1.8 mg pyrethrum per sample. a. Add known amounts of calibration stock solution, or a dilution thereof, to acetonitrile in 10-mL volumetric flasks and dilute to the mark. b. Analyze together with the samples and blanks (steps 9, 10 and 11). c. Prepare calibration graph (peak area vs. mg pyrethrum/10 mL). Determine recovery (R) at least once for each batch of filters used for sampling in the range of the samples. Prepare three filters at each of five levels plus three media blanks. a. Deposit a known amount of calibration stock solution, or a dilution thereof, onto the filters. Allow filters to air-dry. b. Store samples overnight in ointment jars. NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94