PHENYL ETHER-DIPHENYL MIXTURE: METHOD 2013, Issue 1, dated 15 August 1994 - Page 3 of 3
10.
11.
b. Analyze with samples and blanks (steps 12 and 13). c. Prepare calibration graph (peak area vs. µg phenyl ether-diphenyl mixture. Determine desorption efficiency (DE) at least once for each lot of sorbent 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 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 6 through 8) and analyze with working standards (steps 12 and 13). e. Prepare a graph of DE vs. µg mixture recovered. Analyze three quality control blind spikes and three analyst spikes to ensure that the calibration graph and DE graph are in control.
MEASUREMENT: 12.
13.
Set gas chromatograph according to manufacturer's recommendations and to conditions given on page 2013-1. 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 benzene, reanalyze and apply the appropriate dilution factor in calculations. Measure peak area for each analyte peak and sum together for each sample or standard.
CALCULATIONS: 14.
15.
Determine the mass, µg (corrected for DE) of phenyl ether-diphenyl mixture 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 mixture in the air volume sampled, V (L):
EVALUATION OF METHOD: This method was validated over the range 3.86 to 15.7 mg/m 3 using 10-L samples collected from dry air (0% RH) [2]. Overall sampling and measurement precision, SˆrT, was 0.089, with average recovery of 100.1%, representing a non-significant bias. Recovery of analyte from silica gel tubes was 100.0% in the range 4.0 to 15.7 µg per sample after desorption efficiency correction. Desorption efficiency ranged from 89 to 101% over 7 to 102 µg/sample. No breakthrough was seen when a concentration of 14.9 mg/m 3 was collected at 0.18 L/min for 4 hours. Sample storage stability was not determined. REFERENCES: [1] [2] [3]
Documentation of NIOSH Validation Tests, NIOSH Contract No. CDC-99-74-45. NIOSH Manual of Analytical Methods, 2nd. ed. V. 2, S73, U. S. Dept. Health, Education, and Welfare, Publ. (NIOSH) 77-157-B (1977). NIOSH/OSHA Occupational Health Guidelines for Chemical Hazards, U.S. Department of Health and Human Services, Publ. (NIOSH) 81-123 (1981), available as GPO Stock #17-033-00337-8 from Superintendent of Documents, Washington, D.C. 20402.
METHOD REVISED BY: Y.T. Gagnon, NIOSH/DPSE. NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94
