Page:NIOSH Manual of Analytical Methods - 1026.pdf/3

 p-CH LOR OB ENZ OT RIFLU OR IDE: ME TH OD 1026, Issue 1, dated 1 5 Ma rch 2003 - Page 3 of 3 b. c. d. e.

Inject a known amount of analyte stock solution directly onto the front sorbent section of each charcoal tube. Allow the tub es to air equ ilibrate for several m inutes, then cap the ends of the tubes an d allow to stan d overnight. Deso rb (steps 5-7) and a nalyze together with standards and blanks (steps 10 and 11). Prepare a graph of DE vs. µg p-CB TF reco vere d.

MEASUREMENT: 10. Set gas chromatograph according to manufacturer’s recomm endations and to conditions given on page 1026-1. Inject a 1-µL sample aliquot manually using the solvent flush technique or with an autosam pler. NOTE: If peak area is above the linear range of the working standards, dilute with carbon disulfide/methanol (99:1), reanalyze and apply the appropriate dilution factor in the calculations. 11. Measure peak areas.

CALCULATIONS: 12. Determ ine the ma ss, µg (correc ted for DE), for p-chlorobenzotrifluoride found in the sam ple front (W f) and bac k (W b) sorbent sections, and in the averag e m edia blank front (B f) and back (B b) sorbent sec tions. NOTE: If W b > W f/10, report breakthrough and possible sample loss. 13. Calculate conce ntration, C, of p-chlorobenzotrifluoride in the air volume sam pled, V (L):

EVALUATION OF METHOD: This m ethod developm ent was ba sed upo n an health hazard evaluation request where p-chlorobenzotrifluoride was being us ed as a clean ing solvent for auto m obile parts. After an evaluatio n of va rious solid sorbent tubes and solvent/solvent m ixtu res, c oconut s hell charcoal tubes and carbon disulfide/m eth anol (99:1) solvent were selected for use in this method development. The desorption efficiency (DE) was determined for p-chlorobenzotrifluoride at 4 levels ranging from 27.1 µg to 541.2 µg. The average DE de termined for pchlorobenzotrifluoride was 100.6%. The LOD was determined to be 0.6 µg/sample. The analytical method precision, as determined from the pooled relative standard de viation (S r), was determined to be 0.01 31. Para-chlorobenzotrifluoride was determined to have acceptable storage stability (102.6%) for 30 days [1] at a level 0.1 times the recomm ended exposure level suggested by the manufacturer. [2]

REFERENCES: [1] Pende rgrass SM [2000]. Backu p Data for p-Ch lorobenzo trifluoride Me thod Develop m ent, NIOS H/CE MB, Cincinnati, OH ., (NIOSH , unpublished report July). [2] OC C [1998]. Ma terial safety data sheet for p-chlorobenzotrifluoride. Dallas, Texas: Occidental Chem ical Co rporatio n, M ay.

METHOD WRITTEN BY: Stephanie M. Pendergrass, NIOSH/ DART.

NIOSH Manual of Analytical Methods (NMAM), Fourth Edition