Page:NIOSH Manual of Analytical Methods - 5013.pdf/2

 DYES, BENZIDINE-, o-TOLIDINE-, o-DIANISIDINE-: METHOD 5013, Issue 2, dated 15 August 1994 - Page 2 of 5

EQUIPMENT:

REAGENTS: 1. 2. 3. 4. 5. 6.

7. 8. 9. 10.

11.

12.

Water, deionized and distilled. Methanol, HPLC Grade. Benzidine.* o-Tolidine.* o-Dianisidine.* Calibration stock solutions. Dilute the following amounts to 10 mL with methanol. Stable one month at 4 °C. a. Benzidine, 15.6 mg b. o-Tolidine, 15.3 mg c. o-Dianisidine, 5.6 mg Disodium hydrogen phosphate, Na 2HPO 4. Potassium dihydrogen phosphate, KH 2PO 4. Sodium hydrosulfite, Na 2S2O 4. HPLC mobile phase buffer. Dilute 3.39 g KH 2PO 4 and 4.30 g Na 2HPO 4 to 1 L with water. Prepare daily. Reduction buffer. a. Solution A. Dilute 1.179 g KH 2PO 4 and 4.30 g Na 2HPO 4 to 1 L with water. Prepare daily. b. Solution B. Dilute 11.79 g KH 2PO 4 and 43.00 g Na 2HPO 4 to 1 L with water. Prepare daily. Reducing solution. Dilute 200 mg Na 2S2O 4 to 10 mL with the appropriate reduction buffer of Solution A or B (see Table 1) immediately before use.

1. Sampler: PTFE filter, 5-µm, 37-mm (Millipore Mitex or equivalent), with backup pad in a three-piece plastic cassette filter holder. 2. Personal sampling pump, 1 to 3 L/min, with flexible connecting tubing. 3. High pressure liquid chromatograph equipped with 280-nm UV detector, integrator and column (page 5013-1), Waters Model RCM 100 Radial Compression Module with Waters Radial Pak C 18 column or equivalent. 4. Syringe or autosampler for HPLC injection. 5. Syringes, volumetric, 10-, 25- and 50-µL. 6. Flasks, volumetric, 10- and 100-mL, 1-L. 7. Vials, 4-mL, with screw caps. 8. Pipets, volumetric, 1-mL. 9. Tweezers. 10. Beakers, 50-mL. 11. Ultrasonic water bath.


 * See SPECIAL PRECAUTIONS.

SPECIAL PRECAUTIONS: NIOSH recommends that benzidine- and benzidine-congener-based dyes be recognized and handled as human carcinogens because they can be reduced to the free aromatic amine in living systems and eliminated by the usual metabolic pathways [4,6]. Benzidine is a recognized human carcinogen and regulated by the Occupational Safety and Health Administration. o-Tolidine and o-dianisidine are currently suspect carcinogens and should be handled accordingly [4,6]

SAMPLING: 1. 2.

Calibrate each personal sampling pump with a representative sampler in line. Sample at an accurately known flow rate between 1 and 3 L/min for a total sample size of 150 to 500 L.

SAMPLE PREPARATION: 3. 4. 5.

Remove the filter from the cassette with clean tweezers and place it face up in a 50-mL beaker. Add 1.0 mL H 2O to the beaker and swirl to wet the entire deposit. Add another 1.0 mL H 2O to the beaker and swirl. NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94