Page:NIOSH Manual of Analytical Methods - 2521.pdf/2

 METHYLCYCLOHEXANONE: METHOD 2521, Issue 2, dated 15 August 1994 - Page 2 of 4 REAGENTS: 1. 2. 3. 4.

5.

6. 7. 8.

EQUIPMENT:

Acetone, reagent grade.* Analytes: 3-methylcyclohexanone* and 4-methylcyclohexanone*, reagent grade. n-Hexane, chromatographic quality.* Calibration stock solution, 45.7 mg/mL. Dilute 457 mg (0.5 mL at 20 °C) of a 50/50 mixture of 3- and 4-methylcyclohexanone to 10 mL with acetone. Desorption efficiency (DE) stock solution, 274 mg/mL. Dilute 2.74 g (3.0 mL at 20 °C) of a 50/50 mixture of 3- and 4-methylcyclohexanone to 10 mL with hexane. Nitrogen, purified. Hydrogen, prepurified. Air, filtered.



See SPECIAL PRECAUTIONS.

1. Sampler: glass tube, 8.5 cm long, 6-mm OD, 4-mm ID; containing two sections of 50/80 mesh Porapak Q (front = 150 mg; back = 75 mg) separated by a 2-mm urethane foam plug. A silylated glass wool plug precedes the front section and follows the back section. Flame-sealed ends with plastic caps. Pressure drop across the tube at 0.05 L/min airflow must be less than 1.4 kPa. Tubes are commercially available (e.g. SKC Inc. Cat No. ST 226-115). 2. Personal sampling pump, 0.01 to 0.05 L/min, with flexible connecting tubing. 3. Gas chromatograph, FID, integrator and column (page 2521-1). 4. Vials, glass, 2-mL, PTFE-lined caps. 5. Syringes, 10-µL, readable to 0.1 µL, and 25-, 100-, 300-, and 500-µL. 6. Pipet, 1.0-mL, with pipet bulb. 7. Volumetric flasks, 10-mL.

SPECIAL PRECAUTIONS: Acetone, methylcyclohexanone, and n-hexane are highly flammable. All work should be performed in a well-ventilated hood.

SAMPLING: 1. 2. 3. 4.

Calibrate each personal sampling pump with a representative sampler in line. Remove the end caps from the sampler immediately before sampling. Attach sampler to personal sampling pump with flexible tubing. Sample at an accurately known flow rate between 0.01 to 0.05 L/min for a total sample size of 1 to 6 L. Cap the samplers. 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 acetone to each vial. Attach cap to each vial and shake vigorously. Allow to stand 15 min. Analyze within one day after desorption.

CALIBRATION AND QUALITY CONTROL: 8.

Calibrate daily with at least six working standards over the range 0.1 to 4 mg methylcyclohexanone per sample. a. Add known amounts of calibration stock solution to acetone 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 methylcyclohexanone).

NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94