Page:NIOSH Manual of Analytical Methods - 2500.pdf/2

 METHYL ETHYL KETONE: METHOD 2500, Issue 2, dated 15 May 1996 - Page 2 of 4 REAGENTS:

EQUIPMENT:

1.

1.

2. 3. 4. 5.

Elu ent: Carbon disulfide *, chrom ato graphic quality, containing 0.1% (v/v) benzene* or other suitable internal standard. Methyl ethyl ketone Nitrogen or helium, purified. Hydrogen prepurified. Air, filtered.

2.
 * See SPECIAL PRECAUTIONS

3. 4. 5.

Sampler: glass tube, 7 cm long, 6-mm OD, 4-mm ID. Two sections of 20/40 mesh beaded carbon separated by 2-mm foam plug (front = ~15 0 m g, back = ~75 m g). Tub es are com m ercially available: Anasorb 747 (SKC 226-81), Anasorb CMS (SKC 226-121), Carboxen-564 (Supelco ORBO90), o r equ ivalent. Personal sampling pump, 0.01 to 0.2 L/min, with flexible connecting tubing. Gas chromatograph, FID, integrator and colum n (page 25 00-1). Vials, glass, 2-mL, PTFE -lined crimp caps. Syringe, 10-:L, readable to 0.1 :L.

SPECIAL PRECAUTIONS: Carbon disulfide is toxic and an acute fire and explosion hazard (flash point = !30 °C). W ork with it only in a hood. Benzene is a human carcinogen.

SAMPLING: 1. 2. 3. 4.

Calibrate each personal sampling pump with a representative sampler in line. Break the ends of the sampler imm ediately before sampling. Attach sampler to personal sampling pump with flexible tubing. Sam ple at an accurately known flow rate between 0.01 and 0.2 L/min for a total sample size of 0.25 to 12 L. Ca p the sam plers with plastic (not rub ber) cap s and pa ck sec urely for shipm ent.

SAMPLE PREPARATION:

5. 6. 7.

NO TE: Store s am ples in a freezer. Place the front and back sorbent sections of the sampler tube in separate vials. Discard the glass wool and foam plugs. Ad d 1.0 m L eluent to each vial. Attach crim p cap to each vial. Allow to stand 30 min with occasional agitation.

CALIBRATION AND QUALITY CONTRO L: 8.

9.

Calibrate daily with at least six working standards over the range 4 to 500 :g MEK per sample. a. Add known amounts of MEK to eluent in 10-mL volumetric flasks and dilute to the mark. b. Analyze together with samp les and blanks (steps 11 and 12). c. Prepare calibration graph (ratio of peak area of analyte to peak area of internal standard vs.
 * g ME K).

Determine desorption efficiency (DE) at least once for each batch of sorbent used for sampling in the calibration range (step 8). Prepare three tubes at each of five levels plus three media blanks. a. Rem ove and disca rd back sorbent sec tion of a med ia blank sam pler. b. Inject a known amount of MEK directly onto front sorbent section with a microliter syringe. c. Ca p the tube. Allow to stand overnight.

NIOSH Manual of Analytical Methods (NMAM), Fourth Edition