ISOPROPYL GLYCIDYL ETHER: METHOD 1620, Issue 1, dated 15 August 1994 - Page 3 of 3 9.
10.
Determine desorption efficiency (DE) at least once for each lot of charcoal used for sampling in the range of interest. Prepare three tubes at each of five levels plus three media blanks. a. Remove and discard back sorbent section of a media blank sampler. b. Inject known amount (1 to 20 µL) of isopropyl glycidyl ether or standard solution of isopropyl glycidyl ether in CS 2 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 with working standards (steps 11 and 12). e. Prepare a graph of DE vs. mg isopropyl glycidyl ether recovered. Analyze three quality control blind spikes and three analyst spikes to ensure that the calibration graph and recovery graph are in control.
MEASUREMENT: 11.
12.
Set gas chromatograph according to manufacturer's recommendations and to conditions given on page 1620-1. 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 an aliquot of the desorbed liquid with CS 2, reanalyze, and apply the appropriate dilution factor in calculations. Measure peak area.
CALCULATIONS: 13.
14.
Determine the mass, mg (corrected for DE) of isopropyl glycidyl ether 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 isopropyl glycidyl ether in the air volume sampled, V (L):
EVALUATION OF METHOD: Method S77 was issued on February 14, 1975 [2] and was validated over the range 121 to 484 mg/m 3 for 10-L air samples from dynamically generated test atmospheres [1]. The average recoveries ranged from 93 to 95%. The isopropyl glycidyl ether concentrations were independently measured by means of a total hydrocarbon analyzer. Breakthrough was not observed after sampling 44 L from a test atmosphere containing 484 mg/m 3 of isopropyl glycidyl ether. Desorption efficiency decreased from 92.4% to 77.5% with decreasing loading from 4.8 to 1.2 mg isopropyl glycidyl ether per sample. Sample stability was not determined; however, refrigeration of the sample upon receipt by the laboratory is recommended. REFERENCES: [1]
[2]
Documentation of the NIOSH Validation Tests, S77, U.S. Department of Health, Education, and Welfare, Publ. (NIOSH) 77-185 (1977). Available as GPO Stock #017-033-00231-2 from Superintendent of Documents, Washington, DC 20402. NIOSH Manual of Analytical Methods, 2nd ed., Vol. 2, S77, U.S. Department of Health, Education, and Welfare, Publ. (NIOSH) 77-157-B (1977).
METHOD REVISED BY: R.A. Glaser, NIOSH/DPSE. Method S77 was originally validated under NIOSH Contract CDC-99-74-45. NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94
