Page:NIOSH Manual of Analytical Methods - 1026.pdf/2
p-CH LOR OB ENZ OT RIFLU OR IDE: ME TH OD 1026, Issue 1, dated 1 5 Ma rch 2003 - Page 2 of 3 REAGENTS: 1. 2. 3. 4. 5. 6. 7.
EQUIPMENT:
p-Chlorobenzotrifluoride, 98%. Carbon d isulfide, low benzene grade*. Me thanol, HPLC grade *. Helium, purified. Air, prefiltered and purified. Hydrogen, purified. Calibration stock: Dilute 5 µL of p-CBTF in 10 mL solvent. Prepare remaining standards by serial dilutions.
- See SPECIAL PRECAUTIONS
1. Sam pler: glass tube, 7 cm long, 6-mm ID, 4mm ID, flame-sealed ends, containing two sections of activated 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 3mm urethane foam plug follows the back section. Tubes are comm ercially available. 2. Personal sampling pump, 0.01 to 0.2 L/min, with flexible tubing. 3. Gas chromatograph, FID, integrator, and Rtx1, or equivalent, fused silica capillary column. 4. Autosampler vials, glass, 1.8 mL, with PTFElined caps. 5. Syringes, 10-µL to 1-mL. 6. Volumetric flasks, 10-mL and 250-mL. 7. Pipets, various sizes.
SPECIAL PRECAUTIONS: Carbon disulfide is toxic and flamm able. Methanol is moderately toxic and flam m able. Perform all work in a ch em ical hood and w ear a ppro priate prote ctive equipm ent. p-CBTF is an irritant compound.
SAMPLING: 1. Calibrate each personal sampling pump with a representative sample tube in line. 2. Break ope n the end s of th e sa m ple tub e im m ediately prior to s am pling. Attach sam ple tub e to personal sampling pump with flexible tubing. 3. Sam ple at a n ac curately kn own flow ra te betwee n 0.01 an d 0.2 L/m in for a total sam ple size of 0.1 to 10 L. 4. Ca p bo th ends of the s am ple tub es a nd p ack sec urely for shipm ent.
SAMPLE PREPARATION: 5. Pla ce the initial glass wool plug and front so rbent se ctio n of the sam ple tube in an autos am pler vial. Place the back sorbent section of the sample tube in a separate autosampler vial. Discard the polyurethane foam separator and the remaining glass wool plug. 6. Add 1.0 m L of c arbo n disu lfide/m etha nol (99:1) s olven t to eac h vial an d ca p se curely. 7. Allow to stand fo r 30 m inutes with oc cas ional agitation.
CALIBRATION AND QUALITY CONTRO L: 8. Calibrate daily with at least six working calibration standards from below the LOD to 10 times the LO Q. If nece ssa ry additional standa rds m ay be a dde d to exten d the calibra tion cu rve. a. Add k nown a m ounts of calibration stock solution to carbon disulfide/methan ol (99:1) in 10-mL volumetric flasks and dilute to the mark. b. Analyze together with samp les and blanks (steps 10 and 11). c. Prepare calibration graph (peak area vs. µg p-CBT F). 9. Dete rm ine the desorption efficiency (DE) at least once for each batch of c harcoal used for sam pling in the calibration range (step 8). a. Prepare three tubes at each of five levels plus three media blanks.
NIOSH Manual of Analytical Methods (NMAM), Fourth Edition