Aldehydes, Screening (2539)
ALDEHYDES, SCREENING Table 1
MW: Table 1
METHOD: 2539, Issue 2
2539
CAS: Table 1
RTECS: Table 1
EVALUATION: PARTIAL
PROPERTIES:
OSHA : Table 1 NIOSH: Table 1 ACGIH: Table 1
Issue 1: 15 May 1989 Issue 2: 15 August 1994
Table 1
COMPOUNDS: acetaldehyde; acrolein; butyraldehyde ; crotonaldehyde; formaldehyde; furfural; hepta nal; hexanal; isobutyraldehyde; isovaleraledhyde; propionaldehyde; valeraldehyde. SYNONYMS: Table 1 SAMPLING SAMPLER:
SOLID SORBENT TUBE (10% 2-(hydroxymethyl) piperidine on XAD-2, 120 mg/60 mg)
FLOW RATE:
0.01 to 0.05 L/min
VOLUME:
5L
SHIPMENT:
@ 25 °C or lower
SAMPLE STABILITY:
at least 1 week @ 25 °C
FIELD BLANKS:
2 to 10 field blanks per seat
MEDIA BLANKS:
6 per set
MEASUREMENT TECHNIQUE:
GAS CHROMATOGRAPHY, FID & GC/MS
ANALYTE:
oxazolidine prepared from aldehyde
DESORPTION:
1 mL toluene; 60 min ultrasonic
INJECTION VOLUME:
1:L splitless; split vent time 30 sec
TEMPERATURE-INJECTION: -DETECTOR: -COLUMN:
CARRIER GAS:
He, 0.5 mL/min; makeup flow, 29 mL/min
COLUMN:
capillary, 15 m x 0.32-mm, 1.0-:m film 6% cyanopropyl-phenyl, DB-1301 or equivalent
CALIBRATION:
standard solutions of aldehydes spiked on sorbent
ACCURACY RANGE STUDIED:
not studied
BIAS:
not determined
OVERALL PRECISION (Ö r T ):
not determined
ACCURACY:
not determined
250 °C 280 °C 1 min @ 70 °C, 6 °C/min to 100 °C for 2 min; 30 °C/min to 260 °C
RANGE AND PRECISION:
not determined
ESTIMATED LOD: 2 :g aldehyde per sample APPLICABILITY: This is a screening technique to determine the presence of aldehydes and should not be used for quantitation. Further confirmation of aldehyde identification should be performed by gas chromatography/ mass spectrometry (See Table 2 fo r structural ion dat a). Methods fo r quantitation of some aldeh ydes listed in th is method are available in the NIOSH Manual of Analytical Methods (See OTHER METHODS). All aldehydes tested have detected by this method in bulk field samples. INTERFERENCES: High-boiling naphtha mixtures, such as kerosene and mineral spirits may have components with retention times similar to the oxazolidines and may be interferences in the gas chromatographic analysis. A second column (DB -5, DB-WAX ) may be neede d to separate so me of the earlie r C 3 -C 4 aldehydes from excess HMP reagent. OTHER METHODS: This method incorporates sampling technology used in NIOSH methods 2501 (acrolein), 2541 (formaldehyde), 2529 (furfural), 2531 (glutaraldehyde) [1], and 2526 (valeraldehyde), and OSHA methods 68 (acetaldehyde) and 52 (acrolein/formaldehyde) [2].
NIOSH Manual of Analytical Methods (NMAM), Fourth Edition ALDEHYDES, SCREENING: METHOD 2539, Issue 2, dated 15 August 1994 - Page 2 of 10 EQUIPMENT:
REAGENTS: 1. 2.
3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23.
Toluen e, chrom atograp hic quality. 2-(Hydro xyme thyl) piperidine. R ecrystallize seve ral tim es fr om isooc tane until th ere is one major peak (>95% of area) by GC analysis. Store in desiccator. Amberlite XAD-2 (Rohm and Haas or equivalent). Form aldeh yde, * 3 7% (w/v) solut ion in water. Formaldehyde stock solution, 1 :g/:L (see APPEND IX A). Acetaldehyde *. Acrolein*. Propionaldeh yde*. Butyraldehyde*. Isobutyraldehyde*. Crotonaldeh yde*. Valeraledehyde *. Isovaleraldehyde*. Hexana l*. Heptana l*. Furfural*. Sulfuric acid, 0.02 N. Sodium hydroxide, 0.01 N. Sodium sulfite, 1.13 M. Water, deionezed, then distilled. Hydrogen, prepurified. Air, filtered, com presse d. Helium, purified.
- See SPECIAL PRECAUTIONS
1.
2. 3.
4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17.
Sampler: glass tube, 10 cm long, 6-mm OD, 4-m m ID ; flam e-se aled e nds and p lastic caps, containing two sections of 40/60 mesh, 2-(hydroxymethyl) piperidine-coated XAD-2 (front = 120 mg; back = 60 mg: see APPENDIX A) retained and separated by sma ll plugs of silan ized glass wool. Pres sure drop acro ss th e tub e at 0 .10 L /min airflow must be less than 760 kPa (5.7 mm Hg) . Tub es ar e com me rcially a vailab le (Supe lco, Inc. O RBO -23 or eq uivalent). Personal sampling pump, 0.01 to 0.05 L/min, with flexible connecting tubing. Gas chromatograph, flame ionization detector (FID), integrator and column (page 2539-1). GC/MS system for confirmation. Ultrasonic bath. Vials , glas s, 1-m L, with PTF E-line d crim p caps. Flasks, volumetric, 10-mL. Pipets, molumetric, 1-mL with pipet bulb. Syringes, 10-:L (readable to 0.1-:L), 25-, and 50-:L. File. Beakers, 50-mL. pH me ter. Magnetic stirrer. Burets, 50-mL. Flasks, round-bottomed, 100-mL. Soxhlet extraction apparatus. Vacuum oven. Distillation apparatus.
SPECIAL PRECAUTIONS: Aldehydes can irritate the mucous membranes and act on the central nervous system [3]. Certain aldehydes are also suspect carcinogens. Work with these compounds 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. For general screening, sample at 0.01 to 0.05 L/min for a maximum sample volume of 5 L. NOTE: Aldehydes react with the 2-(hydroxymethyl)piperidine to form an oxazolidine derivative in the sorb ent b ed d urin g sa mp ling. S am pling rate is lim ited b y the spe ed o f this reaction. Owing to the lower reactivities of some aldehydes, sampling even at 0.02 L/min may cause breakthrough because of incomplete reaction.
SAMPLE PREPARATION:
NIOSH Manual of Analytical Methods (NMAM), Fourth Edition ALDEHYDES, SCREENING: METHOD 2539, Issue 2, dated 15 August 1994 - Page 3 of 10 4. 5. 6. 7.
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 sec tion in a via l. Tra nsfe r ba ck s ectio n w ith re ma ining glas s wo ol plu gs to a se con d via l. Add 1.0 m L tolu ene to ea ch v ial. C rim p ca p tigh tly on to ea ch v ial. Agitate vials in an ultrasonic bath for 60 min.
CALIBRATION AND QUALITY CONTROL: 8.
9.
Prepare qualitative oxazolidine standard samples. a. Prepare aldehyde standard stock solutions. NOTE: Alde hyd es c an o xidiz e to o ther com pou nds on e xpo sure to air . Th is will introduce bias into the method, so use of freshly-opened bottles of aldehydes is recommended. (1) Inject an aliquo t of form aldeh yde s tock so lution dire ctly onto the so rben t. (2) Take sp ecial care with ace taldehyde b ecause of its volatility. To prepa re acetaldehyde standard solutions, weigh a 10-mL capped volumetric flask containing about 5 mL toluene. With a cooled pipette, transfer about 1 mL of acetaldehyde into the weighed flask, recap and reweigh. Dilute to the mark. (3) For the other aldehydes, add measured aliquots (ca. 12 :L) of each to toluene in 10-mL volumetric flasks and dilute to the mark. From the density of each aldehyde, determine the amount of each aldehyde present in each solution (ca. 1 :g/:L). b. Inject 10 :L of the standard aldehyde solutions separately onto blank tubes from the same lot as the field samples. c. Analyze (steps 4 through 7 and 10 through 12) along with blanks for qualitative identification of derivative peaks by retention times. Determine limit of detection (LOD) for individual aldehydes by GC/FID with standards covering the range 0.5 to 10 :g per sam ple. Do this onc e, wh en first se tting up the m ethod to determine approximate sensitivities for the various aldehyde derivatives. Subsequently, analyze only low-level formaldehyde standard samples with each set of samples as an internal check that the analytical system is working. a. Weigh 120-m g portions of unused sorbent from media blanks into vials. Keep at least three 120-mg portions of this sorbent for determination of the background levels of each aldehyde. b. Add 0.5- to 10-:L aliq uots of the indiv idua l alde hyd e sta nda rd so lution s to o btain standard samples in the range 0.5 to 10 :g pe r 12 0 m g po rtion of so rbe nt. C ap v ials and allow to stand overnight at room temperature. c. Desorb the standard samples of aldehydes (steps 6 and 7) and analyze (steps 10 throu gh 12 ) along with bla nks. d. Determine lowest spike to be detected (peak area greater than three times the background or lowest standard observable) to estimate LOD for each aldehyde. NOTE: Because the working standards are prepared on media blanks, no additional blank correction or desorption efficiency correction is necessary.
MEASUREMENT: 10.
11.
Set gas chromatograph to manufacturer's recommendations and to conditions given on page 2539-1. Inject 1-:L sam ple aliqu ot. NOTE: If the am oun t of oxa zolidine in the a liquot ex ceed s the c apa city of the colum n, dilute the sample with toluene. Compare retention times of unknown peaks in samples to the retention times for the oxa zolid ines as d eter min ed b y the qua litative stan dar d sa mp les. (S ee A ppe ndix B for sam ple
NIOSH Manual of Analytical Methods (NMAM), Fourth Edition ALDEHYDES, SCREENING: METHOD 2539, Issue 2, dated 15 August 1994 - Page 4 of 10 chrom atogram ). a. Analyze samples with GC retention times matching any oxazolidine by GC/MS using the same GC columns and conditions if possible. Alternate columns such as a DB-WAX (formaldehyde, acetaldehyde, propanal) or DB-1 (remaining aldehydes) may also be used for GC/MS confirmation depending on which aldehyde is suspected. b. Determine the presence of oxazolidines by monitoring for specific ions known to be present in the derivative spectra. See Table 2 for characteristic ion table and Appendix C for re fere nce ma ss s pec tra. R eten tion t ime s by GC /MS mu st als o m atch auth entic oxazolidine standards. NOTE 1:
12.
This method may also sample aldehydes other than those listed. The presence of these other aldehydes can be confirmed by examination of the mass spectral data and observation of peaks at m/e 126 and at the molecular ion minus one mass unit. The molecular ion for a particular aldehyde is equal to the molecular weight of the original aldehyde plus 97. Fragmentation patterns are also important for the identification of the oxazolidines. NOTE 2: The absence of some C 3-C 5 aldehydes, such as propionaldehyde, isobutyraldehyde and crotonaldehyde, does not necessarily mean that these compounds are not present in the air sampled. These compounds are not efficiently trapped by the sorbent, and will readily breakthrough the sampler sorbent beds. NOTE 3: Higher molecular weight aldehydes, such as isovaleraldehyde, hexanal and hep tanal, p roba bly will be mo re efficien tly collecte d on th e sorb ent ow ing to their low er va por pre ssu re. T hus , abs enc e of th ese com pou nds in sa mp le results may be indicative of the absence of these compounds in the environment sampled. Rep ort the p resen ce of a particu lar alde hyde if: a. There is a detectable peak by GC-FID at the correct retention time for that aldehyde derivative. b. The correct mass spectrum for the derivative is obtained by GC/MS at the proper retention time.
REFERENCES: [1] [2] [3] [4]
NIOSH Manual of Analytical Methods, 3rd ed., P.M. Eller, Ed., DHHS (NIOSH) Publication No. 84-100 (1984). Occupational Safety and Health Administration, "OSHA Analytical Method Manual," American Confere nce of G overnm ental Industrial Hygien ists, Cincinnati, OH (19 85). Kennedy, E. R., P. F. O'Connor, Y. T. Gagnon. Determination of Acrolein in Air as an Oxa zolidine Deriva tive by G as C hrom atogr aph y. A n al . C h em ., 56, 2120-21 23 (1984 ). Kennedy, E. R., Y. T. Gagnon, J. R. Okenfuss, A. W. Teass. The Determination in Air of Selected Low-molecular Weight Aldehydes as Their Oxazolidines by Capillary Gas Chro ma togra phy. Appl. Ind. Hyg., 3, 274-279 (1988).
METHOD WRITTEN (REVISED) BY: Ardith A. Grote and Eugene R. Kennedy, Ph.D., NIOSH/DPSE.
TABLE 1. GENERAL INFORMATION Compound Limits (ppm)
d(g/mL) VP(mm Hg) NIOSH Manual of Analytical Methods (NMAM), Fourth Edition
Exposure ALDEHYDES, SCREENING: METHOD 2539, Issue 2, dated 15 August 1994 - Page 5 of 10 (Synonyms) Formaldehyde (formic aldehyde; formalin; CAS #50-00-0 RTECS LP8925000
Formula CH2 O
MW 30.03
Acetaldehyde (acetic aldehyde; ethyl aldehyde; CAS #75-07-0 RTECS AB1925000
C2 H4 O
44.05
0.788 (@ 16°C)
21
Propionaldehyde (propanal; CAS # 123-38-6) RTECS UE0350000
C3 H6 O
58.08
0.807
Acrolein (2-propenal; allyl aldehyde; CAS #107-02-8) RTECS AS1050000
C3 H4 O
56.06
Butyraldehyde (butanal; CAS # 123-72-8) RTECS ES2275000
C4 H8 O
Isobutyraldehyde (2-methylpropanal dimethylacetaldehyde; CAS #78-84-2) RTECS NQ4025000
NIOSH Carc.a ; 0.016 C 0.1 Group I Pesticide
ACGIH C 0.3 Suspected Carcinogen
200
Carc.a 18 ppm LOQ
100 150 STEL
49
--
--
--
258
0.839
52.5
0.1
0.1 0.3 STEL Group I Pesticide
0.1 0.3 STEL
210
72.10
0.802
75
--
--
--
92
C4 H8 O
72.10
0.794
64
--
--
--
170
Crotonaldehyde (2-butenal; ß-methyl acrolein; CAS # 123-73-9) RTECS GP9625000
C4 H6 O
70.09
0 853
104
2
2
2
30
n-Valeraldehyde (pentanal; CAS # 110-62-3) RTECS YV3600000
C5 H1 0 O
86.13
0.810
102
no standard
50
50
50
Isovaleraldehyde (3-methylbutanal; isopentanal; CAS # 590-86-3) RTECS ES3450000
C5 H1 0 O
86.13
0.785
92
--
--
--
50
Hexanal (caproaldehyde; CAS # 66-25-1) RTECS MN7175000
C6 H1 2 O
100.16
0.834
131
--
--
--
10
Heptanal (enanthal;
C7 H1 4 O
114.18
0.809
153
--
--
--
3
--
2 (skin)
CAS #111-71-7) RTECS MI6900000 Furfural (2-furancarboxaldehyde; CAS # 98-01-1) RTECS LT7000000 a
@ 20 °C --
BP(°C) -19.5
OSHA 3; C 5; P 10/30 min
(@ 30°C) C5 H4 O2
96.08
1.16 (@ 25°C)
162
- Carcinogen
NIOSH Manual of Analytical Methods (NMAM), Fourth Edition
5 (skin)
(@ 20 °C) 20 (-88°C) 740 ALDEHYDES, SCREENING: METHOD 2539, Issue 2, dated 15 August 1994 - Page 6 of 10 TABLE 2. MASS SPECTRAL DATA FOR ALDEHYDE DERIVATIVES OF 2-(HYDROXYMETHYL)PIPERIDINE (HMP)
Aldehyde
Formula
Formaldehyde Acetaldehyde Propionaldehyde Acrolein Butyraldehyde Isobutyraldehyde Crotonaldehyde Valeraldehyde Isovaleraldehyde Hexanal Heptanal Furfural
C7 H1 3 NO C8 H1 5 NO C9 H1 7 NO C9 H1 5 NO C1 0 H1 9 NO C1 0 H1 9 NO C1 0 H1 7 NO C1 1 H2 1 NO C1 1 H2 1 NO C1 2 H2 3 NO C1 3 H2 5 NO C1 1 H1 5 NO2
HMP DERIVATIVE Base Peak m/z 97 126 126 126 126 126 126 126 126 126 126 192
Other Characteristic Ions m/z 126, 127* 140, 141* 154, 155* 152, 153* 168, 169* 168, 169* 166, 167* 182, 183* 182, 183* 196, 197* 210, 211* 95, 163, 193*
- indicates molecular ion.
APPENDIX A: SORBENT PREPARATION (optional if commercially prepared tubes are used ): Extrac t Amb erlite XAD S-2 for 4 h in Soxh let with 50/50 (v/v) aceto ne/m ethylene ch loride. Rep lace with fresh solvent and repeat. Vacuum dry overnight. Add 1 g purified 2-(hydroxymethyl)piperidine in 50 mL toluene fo r each 9 g extrac ted XA D-2 so rbent. Allow this mix ture to stan d 1 h with o ccasio nal swirling. Remo ve the solvent by rotary evaporation at 37 °C and dry at 130 kPa (1 m m Hg) at am bient temperature for ca. 1 h. To determine the amount of background for each batch, extract several 120-mg portions of the coated sorbent with toluene and analyze (steps 6 through 12). No blank peak is expected for any aldehydes other than formaldehyde and possibly acetaldehyde. SYNTHESIS OF ALDEHYDE OXAZOLIDINES: Plac e a so lution of pu rified 2-hyd roxym ethylp iperid ine (0 .57 g , 5 m mo l) in 10 mL of tolu ene in a 50-mL round-bottomed flask. Use several 20 mL portions of toluene to rinse residual 1-(hydrox ymethyl)p iperidine fro m the containe r used fo r weighing . Add anh ydrous m agnes ium su lfate (2.5 g) to the round-bottomed flask to dry the aldehyde solution as it is added and to remove the water which forms during the reaction. Add a solution of 10 mole of aldehyde in 10 mL of toluene to the 2-hydrox ymethylpip eridine so lution dropw ise with stirring over 1 h. S tir the solution o vernight, the n filter to remove the magnesium sulfate. Remove the toluene and excess aldehyde from the solution at reduced pressure by rotary evaporation. PREPARATION AND STANDARDIZATION OF FORMALDEHYDE STOCK SOLUTION (ca. 1 mg/m L): Dilute 2.7 m L 37% aque ous form alin so lution to 1 L w ith dis tilled, d eioniz ed w ater. This solut ion is s table for at least three months. Standardize by placing 5.0 mL of freshly prepared 1.13 M sodium sulfite solution in a 5 0-m L beak er and s tir magn etically. Adjust p H to betw een 8.5 a nd 10 w ith base o r acid. Record the pH. Add 10.0 mL stock formaldehyde solution. The pH should be greater than 11. Titrate the solution back to its original pH with 0.02 N sulfuric acid (1 mL acid 0.60 0 m g HC HO ; abo ut 17 mL acid needed). If the endpoint pH is overrun, back titrate to the endpoint with 0.01 N sodium hydroxide . Calcula te the con centration , C s (mg/mL), of the formaldehyde stock solution:
where:
30.0 = 30.0 g/equivalent of formaldehyde N a = nor ma lity of su lfuric acid NIOSH Manual of Analytical Methods (NMAM), Fourth Edition ALDEHYDES, SCREENING: METHOD 2539, Issue 2, dated 15 August 1994 - Page 7 of 10 V a = volume of sulfuric acid (mL) used for titration N b = normality of NaOH V b = volume of NaOH (mL) used for back titration V s = volume of form aldehyde stock solution (10.0 mL).
NIOSH Manual of Analytical Methods (NMAM), Fourth Edition ALDEHYDES, SCREENING: METHOD 2539, Issue 2, dated 15 August 1994 - Page 8 of 10 APPENDIX B: Sample chromatogram of aldehyde oxazolidines on DB-1301 column using conditions listed on page 2539-1.
NIOSH Manual of Analytical Methods (NMAM), Fourth Edition ALDEHYDES, SCREENING: METHOD 2539, Issue 2, dated 15 August 1994 - Page 9 of 10 AP PE ND IX C : Refe rence ma ss sp ectra o f oxaz olidines of alde hyde s individ ually sp iked o nto O RB O - 23 t u b e s. GC /MS c o n d i tio n s : H P 5890 gas chromatograph interfaced (direct) to H P 59 70 m as s - s elec ti v e d e te c to r (7 0 e V ); 3 0 -m DB -1 col umn, 0.25-mm I.D ., 1.0-µm fi lm; 70 °C for 1 mi n, 15 ° C/ m in t o 300 ° C ; in te rfa c e te m p e ra tu re, 280 °C ; i njector, 250 °C , 1 µL spli tless i njection; scan 20- 400 am u .
NIOSH Manual of Analytical Methods (NMAM), Fourth Edition ALDEHYDES, SCREENING: METHOD 2539, Issue 2, dated 15 August 1994 - Page 10 of 10 A P P E ND I X C : (C o n ti n u e d )
NIOSH Manual of Analytical Methods (NMAM), Fourth Edition