Page:NIOSH Manual of Analytical Methods - 1302.pdf/2

 N-METHYL-2-PYRROLIDINONE: METHOD 1302, Issue 1, dated 15 January 1998 - Page 2 of 3 REAGENTS:

EQUIPMENT:

1. 2. 3. 4. 5. 6. 7.

1. Sampler: Glass tube, 70 mm, 6-mm OD, containing two sections of coconut shell charcoal (100 mg front, 50 mg back section) separated by polyurethane foam plug. A glass wool plug precedes the front section and a polyurethane foam plug follows the back section. Tubes are commercially available (SKC 226-01, Supelco ORBO-32). 2. Personal sampling pump, 0.05 to 2 mL/min, with flexible connecting tubing. 3. Gas chromatograph, nitrogen phosphorous detector and/or flame ionization detector, integrator, and amine capillary column, Restek Rtx-5 or equivalent (page 1302 -1). 4. Vials, autosampler, with PTFE-lined caps. 5. Microliter syringes, 10-µL and other sizes as needed, readable to 0.1 µL. 6. Flasks, volumetric, various sizes. 7. Pipets, various sizes.

N-methyl-2-pyrrolidinone, reagent grade.* Methanol, chromatographic grade. * Methylene chloride, chromatographic grade* Helium, purified. Hydrogen, prepurified. Air, filtered. Desorption Solvent. 5% methanol in 95% methylene chloride. 8. Calibration Stock Solution. Add N-methyl-2-pyrrolidinone to desorption solvent in a 10-mL volumetric flask. Protect from light.


 * See SPECIAL PRECAUTIONS

SPECIAL PRECAUTIONS: N-methyl-2-pyrrolidinone is an irritant with possible teratogenic properties. Methanol is flammable and a dangerous fire risk. Methylene chloride is a potential occupational carcinogen. Wear appropriate protective clothing and work with these compounds in a well ventilated hood.

SAMPLING: 1. Calibrate each personal sampling pump with a representative sampler in line. 2. Break ends of tubes immediately before sampling. Attach sampler to personal sampling pump with flexible tubing. 3. Sample at an accurately known flow rate of 0.05 to 0.2 L/min for a total sample size of 0.5 to 125 L. 4. Cap the samplers and pack securely for shipment. Protect samplers from prolonged exposure to light. SAMPLE PREPARATION: 5. Place front sorbent section including glass wool plug and back sorbent section in separate autosampler vials. Discard foam plugs. 6. Add 1 mL desorption solvent to each vial and cap. 7. Let each vial stand with occasional agitation for 30 min to aid desorption. CALIBRATION AND QUALITY CONTROL: 8. Calibrate daily with at least six working standards over the range from below the LOD to 10 times the LOQ. The calibration graph may be extended if sample concentrations dictate. a. Add known amounts of calibration stock solution to solvent in 10-mL volumetric flasks and dilute to the mark. Prepare additional standards by serial dilution. Prepare fresh daily. b. Analyze together with samples and blanks (steps 11 and 12). c. Prepare calibration graph (peak area or height vs. µgN-methyl-2-pyrrolidinone). 9. Determine desorption efficiency (DE) at least once for each lot of charcoal tubes used for sampling in the calibration range (step 8). a. Prepare three samplers at each of six levels plus three media blanks. b. Remove the back section of the charcoal tubes. Inject a known amount of calibration stock NIOSH Manual of Analytical Methods (NMAM), Fourth Edition