Page:NIOSH Manual of Analytical Methods - 2541.pdf/2

 FORMALDEHYDE: METHOD 2541, Issue 2, dated 15 August 1994 - Page 2 of 5 EQUIPMENT:

REAGENTS: 1. Toluene, chromatographic quality. 2. 2-(Hydroxymethyl)piperidine (2-HMP). Recrystallize several times from isooctane until there is one major peak (>95% of area) by GC analysis. Store in desiccator. 3. Formalin solution, 37%*. 4. Formaldehyde* stock solution, 1 mg/mL (see Appendix A). 5. Sulfuric acid, 0.02 N. 6. Sodium hydroxide, 0.01 N. 7. Sodium sulfite (Na 2SO 3), 1.13 M. Prepare fresh immediately before use. 8. Water, deionized, distilled 9. Hydrogen, prepurified. 10. Air, filtered. 11. Helium, purified 12. Magnesium sulfate.



See SPECIAL PRECAUTIONS

1. Sampler: glass tube, 10 cm long, 6-mm OD, 4-mm ID, with flame-sealed ends and plastic caps, containing two sections of 2-(hydroxymethyl) piperidine-coated XAD2 (see APPENDIX B) (front = 120 mg; back = 60 mg) retained and separated by small plugs of silanized glass wool. Pressure drop across the tube at 0.10 L/min airflow must be less than 760 kPa (5.7 mm Hg). Tubes are commercially available (Supelco ORBO-23; SKC 226118; or equivalent). 2. Personal sampling pump, 0.01 to 0.10 L/min, with flexible connecting tubing. 3. Gas chromatograph, flame ionization detector, integrator and column (page 2541-1). 4. Ultrasonic water bath. 5. Vials, glass, 2-mL, with PTFE-lined crimp caps. 6. Flasks, volumetric, 10-, 25-, and 50-mL. 7. Pipets, volumetric, 1-, 2-, and 10-mL with pipet bulb. 8. Syringes, 10-mL (readable to 0.1 mL), 25-, and 50-mL. 9. File. 10. Beakers, 50-mL. 11. pH meter. 12. Magnetic stirrer. 13. Burets, 50-mL. 14. Flasks, round-bottomed, 100-mL. 15. Soxhlet extraction apparatus. 16. Vacuum oven. 17. Distillation apparatus.

SPECIAL PRECAUTIONS: Formaldehyde is viewed as a potential occupational carcinogen SAMPLING: [4,5]. 1.

2. 3.

4.

Calibrate each personal sampling pump with a representative sampler in line. Break ends of the sampler immediately before sampling. Attach sampler to personal sampling pump with flexible tubing. Sample at an accurately known flow rate between 0.01 and 0.10 L/min for a total sample size of 1 to 36 L. NOTE: Formaldehyde reacts with 2-(hydroxymethyl)piperidine on the sorbent bed during sampling. Sampling rate is limited by the speed of this reaction. Sampling above 0.10 L/min may cause appreciable breakthrough owing to incomplete reaction, possibly invalidating the sample. Further discussion of this reaction is included in Ref. [6]. Cap the samplers and pack securely for shipment.

SAMPLE PREPARATION: 5. 6.

Score each sampler with a file in front of the first sorbent section. Break sampler at score line. Remove and place front glass wool plug and front sorbent section NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94