Isopropyl Acetate (1460)
ISOPROPYL ACETATE
MW: 102.14
CH3 COOCH(CH3 )2 METHOD: 1454, Issue 1
1460
CAS: 108-21-4
RTECS: AI4930000
EVALUATION: PARTIAL
OSHA : 250 ppm NIOSH: no REL ACGIH: 250 ppm; STEL 310 ppm
Issue 1: 15 March 2003
PROPERTIES: Colorless liquid; BP 89.4 °C; d 0.87 g/mL @20 °C; miscible in most organic solvents; VP 6.33 kPa (47.5 mm Hg)
(1 ppm = 4.18 mg/m3 @ NTP)
SYNONYMS: 2-Propyl Acetate
SAMPLING
MEASUREMENT
SOLID SORBENT TUBE (coconut shell charcoal, 100 mg/50 mg, Lot 2000)
TECHNIQUE:
GAS CHROMATOGRAPHY, FID
ANALYTE:
Isopropyl acetate
FLOW RATE:
0.02 to 0.2 L/min
DESORPTION:
1 mL of carbon disulfide containing 1% methanol
VOL -MIN: -MAX:
0.1 L @ 250 ppm 9L
INJECTION VOLUME: 1 µL
SHIPMENT:
Routine
SAMPLER:
SAMPLE STABILITY:
30 Days @ 5°C
TEMPERATURE -INJECTION: -DETECTOR: -COLUMN:
BLANKS:
2 to 10 field blanks per set
CARRIER GAS:
Helium, 2.8 mL/min
COLUMN:
Capillary, fused silica, 30-m x 0.32mm ID, 1.00 µm film crossbonded® 100% dimethyl polysiloxane or equivalent
CALIBRATION:
Standard solutions of isopropyl acetate in carbon disulfide/ methanol (99:1)
OVERALL PRECISION (Ö rT ): Not Determined
RANGE:
0.6 to 697.6 µg per sample
ACCURACY:
ESTIMATED LOD:
0.2 µg per sample
PRECISION ( þ r ):
0.013
ACCURACY RANGE STUDIED:
Not Studied
BIAS:
Not Determined
Not Determined
250 °C 300 °C 40°C (1 min) to 200°C (10°C/min)
APPLICABILITY: The working range is 0.018 to 20.9 ppm (0.075 to 87.2 mg/m3 ) for an 8-L air sample [3].
INTERFERENCES: None identified.
OTHER METHODS: This method was developed as an update for NMAM 1454, Issue 1 which was based upon NIOSH Method S50 from the 2nd edition of the NIOSH Manual of Analytical Methods [1,2].
NIOSH Manual of Analytical Methods (NMAM), Fourth Edition ISOPROPYL ACETATE: METHOD 1460, Issue 1, dated 15 March 2003 - Page 2 of 3 EQUIPMENT:
REAGENTS: 1. Isopropyl acetate, ACS reagent grade. 2. Elu ent: ca rbon disulfide, ch rom ato graphic grad e.* 3. Me than ol, chrom atog raph ic grade.* 4. Standard solutions: Isopropyl acetate in carbon disulfide/m etha nol (99:1) in th e ran ge o f 0.2 to 700 µg per sample. 5. Helium, purified. 6. Hydrogen, prepurified. 7. Air, filtered, compressed.
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 activated (600 °C) coconut shell charcoal (front = 100 mg; back = 50 mg) separated by a 2-mm urethane foam plug. A silylated glass wool plug precede s the front section and a 3-m m urethane foam plug follows the back section. Pressure drop across the tube m ust be less than 3.4 k Pa at 1 L/m in. Tubes are comm ercially available. 2. Personal sampling pump, 0.02 to 0.2 L/min, with flexible connecting tubing. 3. Gas chromatograph, FID, integrator and Rtx-1® or equivalent capillary column (page 1460-1). 4. Vials, 2-mL glass, PTFE-lined caps. 5. Syringe, 10-, 25-µL, readable to 0.1 µL. 6. Syringe, 1-mL, readable to 0.1 mL. 7. Pipets, 3-, 5-mL, readable to 0.1 mL. 8. Volumetric flasks, 10-mL.
SPECIAL PRECAUTIONS: Carbon disulfide is toxic and an acute fire and explosion hazard (flash point = !30 °C ); all work don e with it m ust be pe rform ed in a fum e ho od. M etha nol is flam m able.
SAMPLING: 1. Calibrate each personal sampling pump with a representative sampler in line. 2. Break the ends of the sampler imm ediately before sampling. Attach sampler to personal sampling pump with flexible tubing. 3. Sam ple at a n ac curately kn own flow ra te betwee n 0.02 an d 0.2 L/m in for a total sam ple size of 0.1 to 9 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. Plac e the front (and glass woo l) and bac k sorbe nt sections of the sam pler tub e in se para te vials. Discard the foam plugs. 6. Add 1.0 mL CS 2 / metha nol (99:1) to eac h co ntaine r and cap tightly. 7. Allow to stand 30 min with occasional agitation.
CALIBRATION AND QUALITY CONTRO L: 8. Calibrate daily with at least six working standards over the range from below the LOD to 10 times the LOQ. If necessary, additional standards may be added to extend the calibration curve. a. Add known amounts of isopropyl acetate to solvent in 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 ropyl ac etate). 9. Determine desorption efficiency (DE) at least once per year for each lot of charcoal used for sampling in the calibration range (step 8). Prepare three tubes at each of five concentrations plus three media blanks. NIOSH Manual of Analytical Methods (NMAM), Fourth Edition ISOPROPYL ACETATE: METHOD 1460, Issue 1, dated 15 March 2003 - Page 3 of 3 a. Rem ove and disca rd back sorbent sec tion of a med ia blank sam pler. b. Inject a known amount of isopropyl acetate or of a standard solution of isopropyl acetate in solvent 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 analyte recovered. 10. Analyze three quality control blind spikes and three analyst spikes to insure that the calibration graph and DE gra ph are in control.
MEASUREMENT: 11. Set gas chromatograph according to manufacturer's recomm endations and to conditions given on pag e 14 60-1 . Inject sam ple aliqu ot m anu ally using solve nt flush technique o r with autos am pler. NOTE: If pea k area is abo ve the linear ra nge of the working standard s, dilute w ith solve nt, reanalyze, and apply the appropriate dilution factor in calculations. 12. Measure peak area.
CALCULATIONS: 13. Determ ine the ma ss µg (co rrected for DE ) of isopropyl acetate found in the sam ple front (W f) and back (W b) sorbent sections, and in the averag e m edia blank front (B f) and back (B b) sorbent sections. NO TE: If W b > W f /10, report breakthrough and possible sample loss. 14. Calculate conce ntration, C, of analyte in the air volume sam pled, V (L):
NOTE:
- g/L=m g/m 3
EVALUATION OF METHOD: The current m ethod developm ent effort wa s th e re sult of req uests to evaluate and im prove problem atic gas chromatography methods as part of the NMAM methods update project. Initial evaluations confirmed that Anasorb CSC (coconut shell charcoal) tubes were still the most suitable media for the sampling and analysis of isopropyl acetate. The average DE recoveries for isopropyl acetate, at substantially lower analyte concentration ranges (17 to 698 µg versus 3.75 to 15.4 mg [1,2]) were improved over the previous method (98.4% [3] versus 86.2%[1,2]) when CS 2/m etha nol (99:1) w as u sed as the de sorption s olven t. The LOD for isopropyl acetate was lowered to 0.6 µg/sample [3] from the 10 µg/sample [1,2] reported in the previous method. A 30-day storage stability study was completed for isopropyl acetate with an average recovery of 99.9% [3].
REFERENCES: [1] [2] [3]
NIO SH [1977]. NIO SH Ma nua l of Analytical Metho ds, 2nd e d., V. 2, S50 , U.S. Departm ent of He alth and Human Services. DHEW (NIOSH) Publication No. 77-157-B. NIO SH [1977]. Do cum enta tion of NIO SH Valida tion T ests , NIO SH Contrac t No. CD C-9 9-74 -45. Department of Health, Education and W elfare. (NIOSH) Publication 77-185. Pende rgrass, SM [2000]. Isopropyl Acetate Backu p Data R eport, (unpublished, Novem ber).
METHOD WRITTEN BY: Stephanie Pendergrass, NIOSH / DART
NIOSH Manual of Analytical Methods (NMAM), Fourth Edition