Page:NIOSH Manual of Analytical Methods - 1004.pdf/3

DICHLOROETHYL ETHER: METHOD 1004, Issue 2, dated 15 August 1994 - Page 3 of 3 b.

10.

Inject a known amount of calibration stock solution directly onto front sorbent section with a microliter syringe. c. Cap the tube. Allow to stand overnight. d. Desorb (steps 5 through 7) and analyze together with working standards (steps 11 and 12). e. Prepare a graph of DE vs. mg DCEE recovered. Analyze three quality control blind spikes and three analyst spikes to insure that the calibration graph and DE graph are in control.

MEASUREMENT: 11.

12.

Set gas chromatograph according to manufacturer's recommendations and to conditions given on page 1004-1. Inject sample aliquot manually using solvent flush technique or with autosampler. NOTE: If peak area is above the linear range of the working standards, dilute with eluent, reanalyze and apply the appropriate dilution factor in calculations. Measure peak area. Divide the peak area of analyte by the peak area of internal standard on the same chromatogram.

CALCULATIONS: 13.

14.

Determine the mass, mg (corrected for DE) of DCEE found in the sample front (W f) and back (W b) sorbent sections, and in the average media blank front (B f) and back (B b) sorbent sections. NOTE: If W b > W f/10, report breakthrough and possible sample loss. Calculate concentration, C, of DCEE in the air volume sampled, V (L):

EVALUATION OF METHOD: Method S357 [2] was issued on May 21, 1976, and validated over the range 45 to 180 mg/m 3 at 24 °C and 762 mm Hg using a 15-L sample [1]. Overall precision, SˆrT, was 0.059 with average recovery 90.7%, representing a non-significant bias. The concentration of DCEE was independently verified by a direct hydrocarbon analyzer. Desorption efficiency was 0.94 in the range 0.7 mg to 2.7 mg per sample. Breakthrough (5% on back section) occurred at 115 min when sampling an atmosphere containing 161 mg/m 3 at 0.9 L/min in dry air.

REFERENCES: [1] Documentation of the NIOSH Validation Tests, NIOSH, S357, U.S. Department of Health, Education, and Welfare, Publ. (NIOSH) 77-185 (1977). [2] NIOSH Manual of Analytical Methods, 2nd ed., V. 3, S357, U.S. Department of Health, Education, and Welfare, Publ. (NIOSH) 77-157-C (1977). [3] User check, UBTL, NIOSH Sequence #4121-J (unpublished, November 21, 1983).

METHOD REVISED BY: G. David Foley and Y. T. Gagnon, NIOSH/DPSE; S357 originally validated under NIOSH Contract CDC-99-74-45.

NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94