Isophorone (2556)
ISOPHORONE C9 H14 O
MW: 138.21
METHOD: 2556, Issue 1
OSHA : NIOSH: ACGIH:
CAS: 78-59-1
2556 RTECS: GW7700000
EVALUATION: PARTIAL
25 ppm 4 ppm; Group III Pesticide C 5 ppm (animal carcinogen)
PROPERTIES:
Issue 1: 15 March 2003
liquid; d 0.923 g/mL @ 25 °C; BP 213 °C; VP 26 kPa (0.2 mm Hg 260 ppm) @ 20 °C
SYNONYMS: 3,5,5-trimethyl-2-cyclohexen-1-one
SAMPLING SAMPLER:
SOLID SORBENT TUBE (XAD-4, 80 mg/40 mg)
FLOW RATE:
0.01 to 1 L/min
VOL-MIN: -MAX:
2 L @ 25 ppm 25 L
SHIPMENT:
Ship cold.
MEASUREMENT TECHNIQUE:
GAS CHROMATOGRAPHY, FID
ANALYTE:
Isophorone
EXTRACTION:
1 mL diethyl ether; stand 30 min and rotate 1.5 hours
INJECTION VOLUME: 1 µL
SAMPLE STABILITY:
At least 14 days @ 5 °C
BLANKS:
2 to 10 field blanks per set
ACCURACY
RANGE STUDIED:
Not Determined.
ACCURACY:
Not Determined.
BIAS:
Not Determined.
OVERALL PRECISION (S r T ):
Not Determined.
TEMPERATURE -INJECTOR: -DETECTOR: -COLUMN:
240 °C 300 °C 50 °C (0.5 min) to 225°C (10 °C/min)
CARRIER GAS:
He, 3.0 mL/min
COLUMN:
Capillary, fused silica 30-m x 0.32mm ID; 1 µm film crossbond carbowax- PEG for acidic compounds
CALIBRATION:
isophorone in diethyl ether
RANGE:
6 to 831 µg per sample [1]
ESTIMATED LOD:
1.0 µg per sample [1]
PRECISION (þ r ):
0.01 [1]
APPLICABILITY: The working range for this method is 0.042 to 5.88 ppm (0.24 to 33.2 mg/m3 ) for a 25-L air sample. High humidity may greatly decrease breakthrough volume.
INTERFERENCES: None identified.
OTHER METHODS: This method was developed for air sampling at lower concentrations of isophorone. NMAM Method 2508, for isophorone, is based on the 2nd edition method S367 [2,3]. This older method uses a petroleum-based charcoal sorbent tube and packed-column gas chromatography.
NIOSH Manual of Analytical Methods (NMAM), Fourth Edition ISOP HO RO NE: M ETH OD 2556, Issue 1, dated 1 5 Ma rch 2003 - Page 2 of 4 EQUIPMENT:
REAGENTS: 1. 2. 3. 4. 5.
Dieth yl Ether, c hrom atog raph ic grade.* Isop horo ne.* Helium, prepurified and filtered. Hydrogen, prepurified and filtered. Air, filtered.
See SPECIAL PRECAUTIONS.
1. Sampler: glass tube, 7 cm long, 6-mm OD, 4- mm ID, flame-sealed ends, containing two sections of 20/40 mesh XAD-4 (80 mg front/40 m g back ) separated by a 2-m m urethane foam plug. A silylated glass wool plug precede s the front section and a 3-m m urethane foam plug follows the back sec tion. Pre ssu re drop a cross th e tube at 1 L/min must be less than 3.4 kPa. Tubes are comm ercially available. 2. Personal sampling pump, 0.01 to 1 L/min, with flexible connecting tubing. 3. Gas chromatograph, FID, integrator, basedeactivated inlet liner, and column Stabilwax-DA or equivalent (see page 25 56-1). 4. Vials, 2-mL, PTFE -lined caps. 5. Syringes, 250-, 25-, 10-:L, rea dab le to 0.1 µL. 6. Volumetric flasks, 10-mL. 7. Pipets, 3- and 5-mL, with pipet bulb. 8. Cold packs for shipping. 9. Mecha nical rotary m ixer.
SPECIAL PRECAUTIONS: Diethyl ether is h ighly volatile an d an acu te fire and e xplosion haza rd. W ork with it only in a hood. Isophorone is a lachrymator [2]. W ork with it should be done in a hood and caution should be taken while it is being used.
SAMPLING: 1. Calibrate each personal sampling pump with a representative sampler in line. 2. Break the ends of the sam pler im m ediately befo re sa m pling. Attach sampler to personal sam pling pum p with flexible tubing. 3. Sa m ple at an accurately known flow rate betwe en 0 .01 and 1 .0 L/m in for a total sam ple size of 2 to 25 L. 4. Ca p the sam plers with plastic (not rub ber) cap s and pa ck sec urely for shipm ent.
SAMPLE PREPARATION: 5. Place the front (and glass w ool plug) and back s orbent s ection s of the sam pler tube in separate vials. Discard the foam plugs. 6. Ad d 1.0 m L dieth yl ether to each vial. Attac h crim p cap to each vial. 7. Allow to stand 30 min with occasional agitation and place on a rotary mixer for 1.5 hours.
CALIBRATION AND QUALITY CONTRO L: 8. Calibrate daily with at least six working standards over the range 6 to 831µg isophorone per sample. a. Add known amounts of isophorone to a 10-mL volumetric flasks and dilute to the mark. b. Analyze together with samp les and blanks (steps 11 and 12). c. Prepare calibra tion gra ph (p eak area vs. µg isop horo ne).
NIOSH Manual of Analytical Methods (NMAM), Fourth Edition ISOP HO RO NE: M ETH OD 2556, Issue 1, dated 1 5 Ma rch 2003 - Page 3 of 4 9. Determine desorption efficiency (DE) at least once for each batch of XAD-4 used for sampling in the calibration range (step 8). Prepare three tubes at each of five levels plus three media blanks. a. Rem ove and disca rd back sorbent sec tion of a med ia blank sam pler. b. Inject a known amount of isophorone directly onto front sorbent section with a microliter syringe. c. Ca p the tube. Allow to stand overnight. d. Deso rb (steps 5 through 7 ) and analyze together with working standards (steps 11 and 12). e. Prepare a graph of DE vs. µg isophorone recovered. 10. Analyze three quality control blind spikes and three ana lyst spikes to insure that the calibration graph and DE graph are in control.
MEASUREMENT: 11. Set gas chromatograph according to manufacturer's recomm endations and to conditions given on page 255 6-1. Inject sam ple aliqu ot m anu ally using solve nt flush technique o r with autos am pler. NOTE: If peak area is above the linear range of the working standard s, dilute w ith diethyl ether, rea nalyze and apply the appropriate dilution factor in calculations. 12. Measure peak area.
CALCULATIONS: 13. Determine the mass, µg (corrected for DE ) of isophorone fo und in the sam ple front (W f) and back (W b) sorbent sec tions, and in the average m edia blank front (B f) and back (B b) sorbent sections. NOTE: If W b > W f/10, report breakthrough and possible sample loss. 14. Calculate conce ntration, C, of isopho rone in the air volume sa m pled, V (L):
EVALUATION OF METHOD: NIOSH method NMAM 2508 for isophorone reported an average DE recovery of 86% over the high concentration range of 849 to 3400 µg [1]. W hile the results are considered acceptable, at th e lowe r levels encountered in current analyses, the recoveries would most likely fall below those considered acceptable. Therefore, a m eth od developm ent effort was initiated to im prove the re covery an d analysis of isophorone at thes e lower leve ls. In 1987, Levin and Carleborg reported that isophorone was quantitatively recovered from XAD polymer using diethyl ether as the desorption solvent at the 750 µg level [4]. Initial results using this approach were plagued by varying recoveries and poor peak resolution which was so lved by using a Stabilwax-DA fused silica capillary colum n and a base-deactivated inlet liner in th e gc injec tion port. T he base-deactivate d inlet liner should be replaced after 35-40 injections. Additionally, the samples were placed on a rotary mixer fo r 1.5 hours after the addition of the diethyl ether. These changes resulted in an average recovery of 94.1% over the range of 55 to 831µg and the LOD being lowered to 1 µg/sample. Isophorone samples, when spiked at levels 0.15 times the REL, were stable (89% recovery) for 30 days when stored at 5°C.
NIOSH Manual of Analytical Methods (NMAM), Fourth Edition ISOP HO RO NE: M ETH OD 2556, Issue 1, dated 1 5 Ma rch 2003 - Page 4 of 4 REFERENCES: [1] Pendergrass SM , Mo ody E [2000] Ba ckup D ata R epo rt for Iso pho rone : Method 2556. NIOSH, DART, CEM B (unpub lished). [2] NIOSH [1994]. NMAM M ethod 2508: Isophorone. In: Eller PM, Cassinelli ME, eds. NIOSH M anual of Analytical Me thod s, 4 th edition. Cincinnati, OH: U.S. Deptartment of Health and Human Servic es, Pu blic He alth Servic e, C ente rs for Diseas e Contro l and P reve ntion, N ationa l Institute fo r Occu pation al Safety and Health. DHHS(NIOSH) Publication No. 94-113. [3] NIO SH [1977]. NIO SH Ma nua l of Analytical Metho ds, 2nd. ed., V. 3, S367, U.S. Department of Health, Education, and W elfare, Publ. (NIOSH) 77-157-C. [4] Levin JO, Carleborg L [1987]. Evaluation of Solid Sorbents for Sampling Ketones in W ork-Room Air, Ann. Occup. Hyg., Vol. 21(1):31-38.
METHOD WRITTEN BY: Stephanie Pendergrass and Erin Moody, NIOSH/DART.
NIOSH Manual of Analytical Methods (NMAM), Fourth Edition