National Institute for Occupational Safety and Health

“ Aldehyde stock solutions should be used within 30 minutes of preparation or kept chilled in an ice bath.
NIOSH Manual of Analytical Methods (NMAM) , Fourth Edition ALIPHATIC ALDEHYD ES: METHO D 2018, Issue 1, dated 15 March 2003 - page 3 of 10
SPECIAL PRECAUTIONS: Acetaldehyde is a severe eye irritant, lachrymator, mutagen, confirmed animal carcinogen, human cancer suspect agent and possible sensitizer [9] . Contact of acetaldehyde with air may cause the formation of explosive peroxides, and contact of the peroxides with heat or flam e m ay cause fires or exp losion s. ”

“ Attach sampler to the sampling pump with flexible tubing. Th e W ate rs sam pler is bi-directional and can be c onn ecte d at either en d. NOTE: If sampling is to be performed in intense sunlight, protection of the DNPH -coated silica gel bed in the sampler from intense light would be suggeste d in ord er to prevent possible photodecomposition of the DNPH reagent [11] and the aldehyde derivatives. If desirable, wrap a portion of the sampler with aluminum foil or black electrical tape. 4. ”

“ Also, liquid standards (standard solutions of aldehyde-DNPH de rivatives in acetonitrile) were stored at 5 °C in the dark in vials with airtight caps (see Table 6) . Limits of detection and quantitation were determined by least squares calculations with series of s ix standard solutions of aldehydeDN PH d erivatives in acetonitrile (see T able 4) . This method also was evaluated for butyraldehyde-DNPH and free butryaldehyde on Supelco S10 LpDNPH samplers. ”

“ Prepare a series of dilutions (working standards) from 0.01 to 10 or 20 μg/mL (ranges of equivalent concentrations of free aldehydes from values be low the detection lim its to values c orrespo nding to upper lim its of the analytical range) . The working stand ards (standard solutions) are stable for more than a month when stored at 5 oC in the dark in airtight containers ”

“ SAMPLE PREPARATION: 7. a. Elute the aldehyde derivatives from the cartridge samplers with 10-m L qu an tities of a ce ton itrile. Collect effluent (ca. 9.5 mL) from each sampler in a separate 10-mL volumetric flask. b. Add acetonitrile to the 10-mL m ark of the volumetric flask for each sample. NOTE: Carbonyl content of acetonitrile can be determined by passing 10 mL of the solvent through a cartridge of DNPH-coated silica gel and analyzing by HPLC. Contents of aldehydes of interest should be below the respective LODs.
CALIBRATION AND QUALITY CONTRO L: 8. ”

“ METHO D 2018, Issue 1, dated 15 March 2003 - page 4 of 10 9. Determine recoveries (R) of aldehydes from samplers in the calibration range (step 8) . Prepare three sorbent beds at each of five concen tration levels for each aldehyde plus three m edia blanks. Re covery is exp ecte d to be near 100% for acetaldehyde, propionaldehyde, and valeraldehyde and about 86% for isovaleraldehyde. a. Prepare series of dilutions of fresh fortification stock solutions in the range of 50 to 300 μg/mL in 20m L vials (one dilution fo r eac h fortification level for eac h alde hyde) . ”

“ 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. ”