Page:NIOSH Manual of Analytical Methods - 2553.pdf/3

KET ON ES II: MET HO D 255 3, Issue 1, dated 15 M arch 200 3 - Page 3 o f 4

10.

b. Inject a known amount of DE stock solution directly onto the front sorbent section of each Anasorb CMS with a microliter syringe. c. Allow the tubes to air equilibrate for several minutes, then cap the ends of each tube and allow to stan d overnight. d. Deso rb (steps 5-7) and a nalyze together with standards and blanks (steps 11 and 12). e. Prepare a graph of DE versus µg analyte recovered. Analyze three quality control blind spikes and three analyst spikes to ensure that the calibration graph and DE gra ph are in control.

MEASUREMENT: 11.

12.

Set gas chromatograph according to manufacturer’s recomm endations and to conditions given on page 2553-1. Inject a 1-µL sample aliquot manually using the solvent flush technique or with an auto sam pler. NOTE: If pea k area is abo ve the linear ra nge of the working standard s, dilute w ith solve nt, reanalyze and apply the appropriate dilution factor in the calculations. Measure peak areas.

CALCULATIONS: 13.

14.

Determ ine the ma ss, µg (correc ted for DE) of an alyte found in the sam ple front (W f) and back (W b) sorbent sec tions, and in the average m edia blank front (B f) and back (B b) sorben t sec tions. NO TE: If W b > W f/10, report breakthrough and possible sample loss. Calculate conce ntration, C, of analyte in the air volume sam pled, V(L):

NO TE : :g/L= m g/m 3

EVALUATION OF METHOD: This method updates NMAM 1301, which was identified as a problematic gas chromatographic method from a survey of external users of the NIOSH Manual of Analytical Methods. This new method, by use of capillary column chrom atography coupled with an improved solid sorbent sampler and modified desorption solvent, resulted in improvements in LOD/LOQ, sample recovery and storage stability compared to NMAM 1301. The average D E recovery was im proved for all analytes at levels lowe r than those rep orted in NMAM 1301, ranging from 95% for mesityl oxide to 100% for 3-heptanone. All samples were stable for 30 days with recoveries ranging from 94% for camphor to 99% for 2-heptanone. The complete summ ary of results is in Table 2.

REFERENCES: [1] [2]

Pende rgrass S M [1 999 ]. Ketones II Method Develop m ent B ack up D ata R epo rt, unpublish ed d ata, NIOSH/DART. NIOS H [1994]. Ketones II: Method 1301. In: Eller PM , Cassinelli ME, eds. NIOS H M anual of Analytical Metho ds, 4 th ed. C incinn ati, OH : National Ins titute for O ccu pation al Safety and Health, DHHS (NIOSH) Publication No. 94-113.

NIOSH Manual of Analytical Methods (NMAM), Fourth Edition