Page:NIOSH Manual of Analytical Methods - 1601.pdf/3

1,1-DICHLORO-1-NITROETHANE: METHOD 1601, Issue 2, dated 15 August 1994 - Page 3 of 3 a. b.

10.

Remove and discard back sorbent section of a media blank sampler. 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 1,1-dichloro-1-nitroethane 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 1601-1. 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 1,1-dichloro-1-nitroethane 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 1,1-dichloro-1-nitroethane in the air volume sampled, V (L):

EVALUATION OF METHOD: Method S213 [2] was issued on November 21, 1975, and validated over the range 27 to 115 mg/m 3 at 23 °C and 763 mm Hg using a 17-L sample [1]. Overall precision, SˆrT, was 0.055, with average recovery 97.7%, representing a non-significant bias. SKC Lot 104 charcoal was the collecting medium. The concentration of analyte was independently verified by calibrated syringe pump. Desorption efficiency was 0.910 in the range 0.5 mg to 2.0 mg analyte per sample. Breakthrough (5% on back section) occurred at 193 min when sampling an atmosphere containing 116 mg/m 3 1,1-dichloro-1-nitroethane at 0.79 L/min in dry air.

REFERENCES: [1] Documentation of the NIOSH Validation Tests, NIOSH, S213, U.S. Department of Health, Education, and Welfare, Publ. (NIOSH) 77-185 (1977). [2] NIOSH Manual of Analytical Methods, 2nd ed., V. 3, S213, U.S. Department of Health, Education, and Welfare, Publ. (NIOSH) 77-157-C (1977). METHOD REVISED BY: G. David Foley and Y. T. Gagnon, NIOSH/DPSE; S213 originally validated under NIOSH Contract CDC-99-74-45.

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