ISOPROPYL ACETATE: METHOD 1454, Issue 1, dated 15 August 1994 - Page 3 of 3
10.
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 analyte 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 1454-1. 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.
CALCULATIONS: 13.
14.
Determine the mass mg (corrected for DE) of isopropyl acetate 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 analyte in the air volume sampled, V (L):
EVALUATION OF METHOD: This method was evaluated over the range 446 to 1870 mg/m 3 at 23 °C and pressure of 770 mm Hg using 8-L samples [3]. Overall sampling and measurement precision, SˆrT, was 0.067, with average recovery of 96%. A sample stability evaluation has not been performed, nor has the sample stability been determined. The accuracy of ±29.4% does not meet the NIOSH criterion of ±25%.
REFERENCES: [1] [2] [3]
NIOSH Manual of Analytical Methods, 3rd ed., V. 2, S50, U.S. Department of Health and Human Services, (1984). Analytical Report for Organics on Charcoal Tubes, DataChem Sequence #3031-S, Unpubl. NIOSH (1981) Documentation of NIOSH Validation Tests, NIOSH Contract No. CDC-99-74-45. Department of Health, Education and Welfare. (NIOSH) Publication 77-185 (1977).
METHOD REVISED BY: Larry B. Jaycox, Ph.D., NIOSH/DPSE.
NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94
