Page:NIOSH Manual of Analytical Methods - 2510.pdf/3

This page needs to be proofread.

1-OCTANETHIOL: METHOD 2510, Issue 2, dated 15 August 1994 - Page 3 of 3

9.

10.

c. Prepare calibration graph (square root of peak height vs. µg 1-octanethiol). Determine desorption efficiency (DE) at least once for each batch of Tenax-GC used for sampling in the calibration range (step 8). 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 5 through 7) and analyze together with working standards (steps 11 and 12). e. Prepare a graph of DE vs. µg 1-octanethiol 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 2510-1. Inject sample aliquot manually using solvent flush technique or with autosampler. Under these conditions, the retention time of 1-octanethiol is about 3.0 min. NOTE: If peak area is above the linear range of the working standards, dilute with acetone, reanalyze and apply the appropriate dilution factor in calculations. Measure peak height.

CALCULATIONS: 13.

14.

Determine the mass, µg (corrected for DE) of 1-octanethiol 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-octanethiol in the air volume sampled, V (L):

EVALUATION OF METHOD: Analytical precision was determined by analyzing spiked sampling media [1]. The average desorption efficiency was 0.94. The breakthrough volume was greater than 15 L for a concentration of 14.6 mg/m at 40 °C and 80% RH. Overall precision, bias and storage stability were determined by sampling and analyzing generated atmospheres. Generated concentrations were independently verified [1]. REFERENCES: [1]

[2]

Spafford, R. B., H. K. Dillon, D. H. Love, and W. K. Fowler. Analytical Methods Evaluation and Validation for Vinylidene Fluoride, Vinyl Bromide, Vinyl Fluoride, Benzenethiol, and n-Octanethiol: Research Report for n-Octanethiol and Benzenethiol, NIOSH Contract No. 210-79-0100, Southern Research Institute, Birmingham, AL, available from NTIS, PB 92-128677, Springfield, VA 22161 (1982). Criteria for a Recommended Standard...Occupational Exposure to n-Alkane Mono Thiols, Cyclohexanethiol, and Benzenethiol, U.S. Department of Health, Education, and Welfare, Publ. (NIOSH) 78-123 (1978).

METHOD WRITTEN BY: R. Alan Lunsford, Ph.D., NIOSH/DPSE; data obtained under NIOSH Contract 210-79-0100. NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94

3

This article is issued from Wikisource. The text is available under Creative Commons Attribution-Share Alike 4.0 unless otherwise noted. Additional terms may apply for the media files.