Page:NIOSH Manual of Analytical Methods - 1402.pdf/3

 ALCOHOLS III: METHOD 1402, Issue 2, dated 15 August 1994 - Page 3 of 4 a. b.

10.

Remove and discard back sorbent section of a media blank sampler. Inject a known amount of analyte or DE 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. 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 1402-1. 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. Divide the peak area of analyte by the peak area of internal standard on the same chromatogram.

CALCULATIONS: 13.

14.

Determine the mass, mg (corrected for DE) of analyte 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: Methods S52 (allyl alcohol), S55 (diacetone alcohol), S54 (cyclohexanol), S58 (isoamyl alcohol) and S60 (methyl isobutyl carbinol) were issued on January 17, 1975 [3], and validated using 10-L air samples of atmospheres generated in dry air by calibrated syringe drive from the pure substances [1]. No stability studies were done. Precision and recovery were as shown below, representing non-significant bias in each method:

Overall Method Precision [1,3] (SˆrT) S52 S55 S54 S58 S60

0.111 0.104 0.080 0.077 0.080

Recovery (%) 98.8 91.8 98.9 107.6 101.8

Range Studied mg/m 3 mg per sample 1.8 to 8.4 140 to 510 95 to 380 195 to 680 45 to 175

0.02 to 0.1 1.1 to 4.7 1 to 4 1.8 to 7 0.5 to 2

Breakthrough @ 2X OSHA >48 L >48 L >48 L 34 L >48 L

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

Avg. DE 0.90 0.78 0.99 0.99 0.99

Measurement Precision (Sr) 0.023 0.054 0.015 0.020 0.035