Page:NIOSH Manual of Analytical Methods - 1460.pdf/2
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