National Institute for Occupational Safety and Health

“ Breakthrough cap acities were de term ined in dry air. Storage stability was assessed at 7, 14, and 30 days. Measurement precisions (Table 4) were determined by spiking sampling media with amounts corresponding to one-half, one, and two times the OSH A standard for nominal air volumes. Desorption efficiencies for spiked sam plers con taining only one co m pou nd e xce ede d 75 % [2,3,4,8 ] . Issue 3: The desorption efficiency, at levels ranging from 10 times the LOQ to 0.1 times the REL, was determined by spiking known am oun ts of analytes (in CS 2) on coconut shell charcoal tubes. ”

“ This method may be used for simultaneous measurements; however, interactions between analytes may reduce breakthrough volumes and alter analyte recovery.
INTERFERENCES: At high humidity, the breakthrough volumes may be reduced. Other volatile organic solvents such as alcohols, ketones, ethers, and halogenated hydrocarbons are potential interferences. ”

“ Determine the desorption efficiency (DE) at least once for each batch of charcoal used for sampling in the calibra tion ran ge (s tep 8) . a. Prepare three tubes at each of five levels plus three media blanks. b. Rem ove and disca rd the back sorbent sec tion of a med ia blank sam pler.
NIOSH Manual of Analytical Methods (NMAM) , Fourth Edition HYD RO CAR BO NS, BP 36-216 °C : MET HO D 150 0, Issue 3, dated 15 M arch 200 3 -Page 3 of 8 c. Inject a know n am ount of stock solution (5 to 25 μL) directly onto the front sorbent section with a microliter syringe. d. ”