Page:NIOSH Manual of Analytical Methods - 1617.pdf/3

 PHENYL ETHER: METHOD 1617, Issue 1, dated 15 August 1994 - Page 3 of 4

CALIBRATION AND QUALITY CONTROL: 10.

11.

12.

Calibrate daily with at least six working standards over the range of 7 to 210 µg per sample. a. Add known amounts of calibration stock solution to carbon disulfide in 10-mL volumetric flasks and dilute to the mark. b. Analyze working standards together with samples and blanks (steps 13 and 14). c. Prepare a calibration graph of area vs. µg of analyte per sample. Determine desorption efficiency (DE) for each lot of charcoal tubes used for sampling in the concentration 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 phenyl ether (or a solution of phenyl ether in hexane) directly onto front (100 mg) sorbent section with a microliter syringe. c. Cap the tube. Allow to stand overnight. d. Desorb (steps 7 through 9) and analyze together with standards (steps 13 and 14). e. Prepare a graph of desorption efficiency vs. µg phenyl ether per sample. Analyze three quality control blind spikes and three analyst spikes to ensure that the calibration graph and DE graph are in control.

MEASUREMENT: 13.

14.

Set instrument according to manufacturer's recommendations and to conditions given on page 1617-1. Inject sample aliquot manually using solvent flush technique or with autosampler. NOTE: If peak area is above linear range of the working standards, dilute an aliquot with carbon disulfide, reanalyze, and apply the appropriate dilution factor in calculations. Measure peak area.

CALCULATIONS: 15.

16.

Determine mass, µg (corrected for DE), of analyte found in the sample front (W f) and back (W b) sorbent sections and in the average media blanks 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 3.0 to 13.3 mg/m 3 with 10-L samples collected from dry (0% RH) air [1,2]. Overall sampling and measurement precision, SˆrT, was 0.07, with average recovery of 100.6%. The test atmosphere concentration of phenyl ether was monitored with a Beckman model 402 total hydrocarbon analyzer. Desorption efficiency (DE) at 7 µg per sample was 80% and approximately 90% in the range 32 to 120 µg per sample. Sample recovery (corrected for DE) was 100.2% over the range 32 to 120 µg. No breakthrough was seen after 4 h when a concentration of 13.1 mg/m 3 was sampled at a flow rate of 0.185 L/min. Sample stability was not determined.

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