Page:NIOSH Manual of Analytical Methods - 1454.pdf/2

 ISOPROPYL ACETATE: METHOD 1454, Issue 1, dated 15 August 1994 - Page 2 of 3 REAGENTS: 1. 2.

3. 4.

5. 6. 7.

EQUIPMENT:

Isopropyl acetate, ACS reagent grade. Eluent: carbon disulfide*, chromatographic grade. NOTE: Add 0.1% (v/v) undecane or p-cymene as an internal standard, if desired. Undecane or p-cymene, ACS reagent grade. Standard solutions: Isopropyl acetate in carbon disulfide in the range of 0.01 to 15 mg per sample. Helium, purified. Hydrogen, prepurified. Air, filtered, compressed.

See SPECIAL PRECAUTIONS

1. Sampler: glass tube, 7 cm long, 6-mm OD, 4mm 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 precedes the front section and a 3-mm urethane foam plug follows the back section. Pressure drop across the tube must be less than 3.4 kPa at 1 L/min. Tubes are commercially available. 2. Personal sampling pump, 0.02 to 0.2 L/min, with flexible connecting tubing. 3. Gas chromatograph, FID, integrator and column (page 1454-1). 4. Vials, 2-mL glass, PTFE-lined caps. 5. Syringe, 10-µL, readable to 0.1 µL. 6. Pipet, 1-mL, readable to 0.1 mL. 7. Volumetric flasks, 10-mL.

SPECIAL PRECAUTIONS: Carbon disulfide is toxic and an acute fire and explosion hazard (flash point = -30 °C); all work done with it must be performed in a fume hood. SAMPLING: 1. 2. 3. 4.

Calibrate each personal sampling pump with a representative sampler in line. Break the ends of the sampler immediately before sampling. Attach sampler to personal sampling pump with flexible tubing. Sample at an accurately known flow rate between 0.02 and 0.2 L/min for a total sample size of 0.1 to 9 L. Cap the samplers with plastic (not rubber) caps and pack securely for shipment.

SAMPLE PREPARATION: 5. 6. 7.

Place the front and back sorbent sections of the sampler tube in separate vials. Discard the glass wool and foam plugs. Add 1.0 mL CS 2 to each container and cap tightly. For the internal standard method, the 1.0 mL CS 2 will contain a known amount of the chosen internal standard. Allow to stand 30 min with occasional agitation.

CALIBRATION AND QUALITY CONTROL: 8.

9.

Calibrate daily with at least six working standards over the range 0.01 to 15 mg analyte per sample. a. Add known amounts of analyte to CS 2 in 10-mL volumetric flasks and dilute to the mark. b. Analyze together with samples and blanks (steps 11 and 12). c. Prepare calibration graph (peak area vs. mg isopropyl acetate). If internal standard is used, plot ratio of peak area of analyte/peak area of internal standard vs. mg isopropyl acetate. 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. a. Remove and discard back sorbent section of a media blank sampler. b. Inject a known amount of analyte or of a standard solution of analyte in CS 2 directly onto front sorbent section with a microliter syringe. NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94