Page:NIOSH Manual of Analytical Methods - 1403.pdf/2

 ALC OH OLS IV: MET HO D 140 3, Issue 3, dated 15 M arch 200 3 - Page 2 o f 5 REAGENTS:

EQUIPMENT:

1. Meth ylene C hloride, H PL C chrom ato graphic grad e.* 2. Me than ol, HP LC chro m atog raph ic grade.* 3. Desorption solvent: methylene chloride (HPLC chromatographic grade) containing 5% m eth anol. 4. 2-methoxyethanol, reagent grade. 5. 2-ethoxyethanol, reagent grade. 6. 2-butoxyethanol, reagent grade. 7. Helium, purified and filtered. 8. Hydrogen, filtered. 9. Air, compressed, purified, filtered.

1. Sam pler: glass tu be, 7 cm long, 6-m m OD , 4-mm ID, flame-sealed ends, containing two sectio ns of a ctivate d coconut s hell charcoal (100 m g/50 m g) separated b y a 2-mm ureth ane fo am plug. A silylated glass wool plug precedes the front section and follows the back sectio n. T ubes are com m ercially available from SKC, Inc. 2. Personal sa m pling pum p, 0.01 to 0.05 L/m in, connected with flexible tubing. 3. Gas chromatograph, FID, integrator, and capillary colum n (page 14 03-1). 4. Autosampler vials, 11-mm glass with crimp caps. 5. Syringes, 10-µL, 25-µL, and 1-mL. 6. Volumetric flasks, 10-mL.


 * See SPECIAL PRECAUTIONS

SPECIAL PRECAUTIONS: Methylene chloride is a carcinogen [6]. Methanol is very flamm 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 sam pling pum p with flexible tubing. 3. Sa m ple at an accurately known flow rate between 0.01 and 0.05 L/m in for a total sam ple size of 6 to 50 L (2-m etho xyethano l); 1 to 6 L (2-ethox yethan ol); and 2 to 10 L (2-b utox yethan ol). NOTE: Maximum flow rate for 2-methoxyethanol and 2-butoxyethanol is 0.2 L/min. 4. Ca p the sam plers with plastic (not rub ber) cap s and pa ck sec urely for shipm ent.

SAMPLE PREPARATION: 5. Place the front and back sorbent sections of the sampler tube in separate vials. Place the glass wool preceding the front section into the vial containing the front sorbent section. Discard the remaining foam plugs. 6. Ad d 1.0 m L of the desorptio n solvent into each vial. Attac h crim p caps to each vial. 7. Plac e the sam ple vials in an u ltrasonic ba th for 3 0 m inutes.

CALIBRATION AND QUALITY CONTRO L: 8. Calibrate daily with at least six working standards to cover the analytical range. If necessary, additional stan dard s m ay be a dde d to exten d the calibra tion cu rve. a. Add know n am oun ts of a nalytes to 10-m L volum etric flas ks and dilute to the m ark with so lvent. b. Analyze together with samp les and blanks (steps 11 and 12). c. Prepare c alibration graph (pe ak area vs µg ana lyte). 9. Determine desorption efficiency (DE) at least once for each lo t of charcoal used for sampling in the calibration ranges (step 8). a. Prepare three tubes at each of five levels plus three media blanks. b. Inject a known amount of DE stock solution directly onto the front sorbent section of each charcoal tube with a microliter syringe.

NIOSH Manual of Analytical Methods, Fourth Edition