Page:NIOSH Manual of Analytical Methods - 2018.pdf/2

 ALIPHATIC ALDEHYD ES: METHO D 2018, Issue 1, dated 15 March 2003 - page 2 of 10 REAGENTS: 1. Aldehyde-DN PH deriva tives, >99% pure (available from Supelco, Inc., or Aldrich Chem ical Co.). 2. Acetonitrile, high purity solvent for HPLC and pes ticide analysis, low ca rbon yl content.* 3. Calibration stock solutions. Accurately weigh 10 mg of DNPH derivatives in separate 10mL volumetric flasks. Add acetonitrile to the 10-mL m ark of each flask. Store at 5 oC in airtight containers 30 days or less. 4. Acetalde hyde, 99% pure .* 5. Propionaldehyde, 97% pure .* 6. Valeralde hyde, 97% pure .* 7. Isovaleraldehyde, 97 % pure .* 8. W ater, deionized (DI water). 9. Acetaldehyde fortification stock solution, 2.40 mg/m L. Measure 155 µL of cold (0 oC) acetaldehyde with a cold (0 oC) 500-µL syringe. D issolve in 35 m L of cold DI water in a 50-mL volumetric flask. Add DI water (-20 oC) to the 50-mL m ark. Use within 15 m in of preparation.** 10. Propionaldehyde fortification stock solution, 2.40 mg/mL. Dissolve 154 µL of 97% propionaldehyde in 35 mL of acetonitrile in a 50-m L flask. Add ac etonitrile to the 50-mL m ark.*** 11. Valeraldehyde fortification stock solution, 2.40 mg/mL. Dissolve 154 µL of 97% valeraldehyde in acetonitrile in a 50-mL volumetric flask. Add acetonitrile to the 50m L m ark.*** 12. Isovaleraldehyde fortification stock solution, 2.40 mg/mL. Dissolve 152 µL of 97% isovaleraldehyde in acetonitrile in a 50-mL volumetric flask. Add acetonitrile to the 50m L m ark.***

EQUIPMENT: 1. Sam pler: Plastic holder containing 0.35 g of 150 to 250-µm (60-100 mesh) silica gel coate d with 1.0 m g of 2,4-dinitrophenylhydrazine which has been acidified. Pressure drop across sampler should be less than 28 inches o f water (7 k Pa) at 1.5 L/m in. Sam plers are comm ercially available [Supelco S10 Lp DN PH cartridge, cat. No. 2-10 14; a similar type of sampler is manufactured by W aters Corp. (Sep-Pak XPoSure Aldehyde Sam pler, pa rt No. W AT 047 205 )]. 2. Personal sampling pump, 0.1 to 1.5 L/min, with flexible connecting tubing. 3. Vials, 20-mL, 4-mL, glass, PFTE-lined rubber septa in caps for airtight seals. 4. Liquid chrom atograph with UV detector, recorder, integrator, and column. (See page 201 8-1.) 5. Syringes, 100-µL, 500-µL, and 10-mL. 6. Volumetric flasks, 5-mL, 10-mL, and 50-mL. 7. Ozone scrubber (optional), available from W aters Corp., Milford, MA. 8. Aluminum foil, or black electrical tape (optional).

See SPECIAL PRECAUTIONS

freezer compartment of a refrigerator for at least 45 m inutes. Mak e sure there is no w ater in th e ne edle which wo uld fre eze and clog the needle. within 30 minutes of preparation or kept chilled in an ice bath.
 * Cool a 500-:L syringe by placing in the
 * Aldehyde stock solutions should be used

NIOSH Manual of Analytical Methods (NMAM), Fourth Edition