Page:NIOSH Manual of Analytical Methods - 2536.pdf/2

 VALERALDEHYDE: METHOD 2536, Issue 2, dated 15 August 1994 - Page 2 of 5 REAGENTS:

EQUIPMENT:

1. 2.

Toluene, chromatographic quality. 2-(Hydroxymethyl)piperidine. Recrystallize several times from isooctane until there is one major peak (>95% of area) by GC analysis. Store in desiccator. 3. Amberlite XAD-2 (Rohm and Haas or equivalent). Extract 4 h in Soxhlet with 50/50 (v/v) acetone/methylene chloride. Replace with fresh solvent and repeat. Vacuum dry overnight. (Optional if commercial tubes are used.) 4. Valeraldehyde, * 99% purity. 5. Valeraldehyde stock solution, 40 µg/µL (see APPENDIX). Add 400 mg valeraldehyde to toluene and dilute to 10 mL. 6. Valeraldehyde oxazolidine (APPENDIX A) stock solution, 10 mg/mL. Add 0.10 g 9-butyl1-aza-8-oxabicyclo-[4.3.0]nonane to toluene and dilute to 10 mL. 7. Hydrogen, prepurified. 8. Air, filtered, compressed. 9. Helium, purified. 10. Magnesium sulfate, anhydrous.



See SPECIAL PRECAUTIONS.

1. Sampler: glass tube, 10 cm long, 6-mm OD, 4-mm ID, flame-sealed ends with plastic caps, containing two sections of 2-(hydroxymethyl) piperidine-coated XAD-2 (front = 120 mg, back = 60 mg) (APPENDIX B). Sorbent sections are retained and separated by small plugs of silanized glass wool. Pressure drop across the tube at 0.1 L/min must be less than 760 Pa (5.7 mm Hg). Tubes are commercially available (Supelco Inc., ORBO 23 or equivalent). 2. Personal sampling pump, 0.01 to 0.04 L/min, with flexible connecting tubing. 3. Gas chromatograph, flame ionization detector, integrator and column (page 2536-1). 4. Ultrasonic bath. 5. Vials, glass, 4-mL, with septum and plastic screw caps. 6. Flasks, volumetric, 10-, 25-, and 50-mL. 7. Pipets, volumetric, 1-, 2-, and 10-mL with pipet bulb. 8. Pipets, disposable, 2-mL. 9. Syringes, 10-µL (readable to 0.1 µL), 25-, and 50-µL. 10. File. 11. Beakers, 50-mL. 12. Magnetic stirrer. 13. Flasks, round-bottomed, 100-mL. 14. Soxhlet extraction apparatus. 15. Vacuum oxen. 16. Distillation apparatus.

SPECIAL PRECAUTIONS: Valeraldehyde can irritate the mucous membranes [4]. It is flammable, a dangerous fire risk. Work with this compound only in a well-ventilated hood.

SAMPLING: 1. 2. 3.

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 0.04 L/min for a total sample size of 0.5 to 10 L. NOTE: Sampling rate is limited by the speed of the following reaction. Rates above 0.04 L/min may cause appreciable breakthrough owing to incomplete reaction, possibly invalidating the sample.

CH 3(CH 2)3CH=O valeraldehyde

+

C5H9NHCH 2OH → C5H9NHC 2H2O(CH 2)3CH 3 + 2-(hydroxymethyl)toluene/ valeraldehyde oxazolidine piperidine ultrasonic energy

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

H 2O