Page:NIOSH Manual of Analytical Methods - 5521.pdf/2

 ISOCYANATES: METHOD 5521, Issue 2, dated 15 August 1994 - Page 2 of 6 REAGENTS: 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.

11. 12. 13. 14.

15. 16. 17.

EQUIPMENT:

1-(2-Methoxyphenyl)piperazine*, 98%. Acetic anhydride, reagent grade. Methanol, HPLC grade. Acetonitrile, HPLC grade. Water, deionized, distilled. Sodium acetate, anhydrous Acetic acid, glacial. Nitrogen, 99.995%. Toluene, HPLC grade. Sampling medium, 1-(2-methoxyphenyl)piperazine in toluene, 43 mg/L. (see APPENDIX A) Ureas derived from the isocyanate. (See APPENDIX B). Dimethyl sulfoxide, reagent grade. Mobile phase, acetonitrile and buffer solution to achieve appropriate mobile phase. Buffer solution. Dissolve 15 g anhydrous sodium acetate in 1 L distilled-deionized water. Add 1 L methanol. Add glacial acetic acid to bring pH to 6.0. Urea calibration stock solution, 0.01 µg/µL urea in methanol. Reagent calibration stock solution, 1.0 µg/µL 1-(2-methoxyphenyl)-piperazine in methanol. Helium, prepurified.


 * See SPECIAL PRECAUTIONS

1. Sampler: Midget impinger, 25-mL 2. Personal sampling pump, 1.0 L/min, with flexible connecting tubing free of phthalate plasticizer. NOTE: Avoid collection of plasticizer in the toluene during sampling. FluranTM tubing is an acceptable, PVC tubing is not. 3. Liquid chromatograph (HPLC) with electrochemical (ECHD) detector (+0.80 V vs. Ag/AgCl), recorder, integrator and column (page 5521-1) 4. Ultrasonic water bath. 5. Vials, 4-mL glass, with screw caps and 20-mL glass, screw caps with cone-shaped polyethylene liner and shrinkable sealing bands. 6. Pasteur pipets, 7-cm glass, disposable. 7. Flasks, volumetric, glass, 10-mL 8. Syringes, sizes appropriate for preparing standard solutions. 9. Pipets, 5- and 15-mL glass, delivery, with pipet bulb. 10. Hot plate, spark free, 60 °C. 11. Evaporator, Mini-Vap, 6-port or equivalent. 12. pH meter. 13. Vacuum oven. 14. Buchner funnel, fritted glass, medium porosity, 100-mL. 15. Vacuum pump. 16. Flask, filtration, 500-mL.

SPECIAL PRECAUTIONS: Preparation of urea derivatives, samples, and standards should be done in a hood to avoid exposure to isocyanate and solvent vapors. Isocyanates are known respiratory irritants.[4] Toxicity of 1-(2-methoxyphenyl)piperazine is unknown.

SAMPLING: 1. 2. 3. 4.

5. 6.

Calibrate each personal sampling pump with a representative sampler in line. Transfer 15 mL sampling medium to an impinger. Connect the assembled impinger to a sampling pump. Sample 5 to 500 L of air at 1.0 L/min. NOTE 1: Toluene evaporates during sampling; when level of solution drops below 10 mL, restore volume to 15 mL with toluene. NOTE 2: The reagent in the sampling medium reacts with isocyanates to form ureas: CH3OC6H4NC4H8NH + R-N=C=O → CH3OC6H4NC4H8NC(=O)NHR Prepare blank samples by transferring 15 mL sampling medium to 20-mL vials. Transfer the sample solution to a 20-mL vial for shipment. Rinse both impinger parts with 2 to 3 mL toluene and add rinsings to the sample. Secure vial's screw cap with sealing band. Refrigerate samples as soon as possible. If samples are to be shipped, carefully pack the vials to avoid breakage or spillage of sample.

NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94