Page:NIOSH Manual of Analytical Methods - 5041.pdf/2

 CAPSAICIN and DIHYDROCAPSAICIN: METHOD 5041, Issue 1, dated 15 May 1996 - Page 2 of 4 REAGENTS:

EQUIPMENT:

1. 2. 3. 4. 5.

1.

Capsaicin, 98% pure.* Dihydrocapsaicin, 90% pure.* Water, distilled. Acetonitrile, chromatographic quality.* Capsaicin calibration and recovery stock solution, 0.8 mg/mL: Dissolve 20 mg of capsaicin in acetonitrile to make 25 mL solution. Store at 5 C. Prepare fresh bimonthly. 6. Dihydrocapsaicin calibration and recovery stock solution, 0.8 mg/mL: Dissolve 20 mg dihydrocapsaicin in acetonitrile to make 25 mL solution. Store at 5 C. Prepare fresh bimonthly.


 * See SPECIAL PRECAUTIONS

Sampler: 13-mm glass fiber filter in 2-piece filter holder (Swinnex, Millipore Corp., or equivalent). 2. Personal sampling pump, 1 to 3 L/min, with flexible connecting tubing. 3. HPLC, fluorescence detector, ex 281nm, em 312 nm; recorder, integrator, and column (page 5041-1). 4. Vials, 4-mL, with PTFE-lined caps. 5. Graduated cylinder, 1-L, readable to 10 mL. 6. Volumetric flasks, 25- and 10-mL. 7. Syringes: 10-mL; 500-µL, readable to 10 µL; 100-µL, readable to 1 µL; 10 µL, readable to 0.1 µL. 8. Ultrasonic water bath. 9. Film, plastic, flexible, water resistant. 10. Syringe filters, 3-mm PTFE membrane, 0.45-µm pore size, in polypropylene housing. 11. Tweezers. 12. Dust mask.

SPECIAL PRECAUTIONS: Capsaicin and dihydrocapsaicin are toxic, are classified as mutagens, and can destroy certain sensory nerve cells [9,10]. Inhalation of aerosols of these compounds will result in prolonged coughing or sneezing. Exposure by inhalation can take place during weighing operations; thus, a dust mask is recommended. Skin contact will cause a burning sensation. Ingestion can cause intolerable burning and gastrointestinal disorders. Acetonitrile is toxic and is a fire hazard (flash point = 12.8 C).

SAMPLING: 1. Calibrate each personal sampling pump with a representative sampler in line. 2. Attach the sampler to the personal sampling pump with flexible tubing. 3. Sample at an accurately known flow rate between 1 and 3 L/min for a total sample size of 7 to 1000 L. NOTE: Limit the maximum loading of particulate matter on the filter to approximately 0.5 mg. 4. Seal ends of sampler with plastic film. Ship to laboratory in insulated container with bagged refrigerant. SAMPLE PREPARATION: 5. 6. 7. 8.

Transfer the 13-mm glass fiber filter to a 4-mL vial. Add 2 mL of acetonitrile to the vial and cap securely. Place the sample vial into an ultrasonic bath and agitate for 10 min. Filter the sample solution through a PTFE membrane filter.

CALIBRATION AND QUALITY CONTROL: 9. Calibrate daily with at least six working standards over the range of interest: 0.008 to 10 µg/mL for capsaicin; 0.01 to 10 µg/mL for dihydrocapsaicin. a. Prepare working standards from calibration stock solution in acetonitrile. NOTE: Working standards may be stored in tightly sealed vials at 5 C for at least 9 weeks. b. Analyze together with samples and blanks (steps 12 and 13). c. Prepare calibration graphs for capsaicin and dihydrocapsaicin (peak area or height vs. µg of analyte). 10. Determine recoveries (R) at least once for each lot of glass fiber filters in the calibration range (step 9). NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 5/15/96