Page:NIOSH Manual of Analytical Methods - 1600.pdf/3

 CARBON DISULFIDE: METHOD 1600, Issue 2, dated 15 August 1994 - Page 3 of 4 SAMPLE PREPARATION: 5. 6. 7.

Detach and discard drying tube. Place front and back sorbent sections of sampler tube in separate vials. Discard glass wool and foam plugs. Pipet 1.0 mL toluene into each vial. Cap each vial. Allow to stand 60 min with occasional agitation. NOTE: Keep desorbed samples and standards away from sources of CS 2 to avoid contamination.

CALIBRATION AND QUALITY CONTROL: 8.

9.

10.

Calibrate daily with at least six working standards. a. Add known amounts of calibration stock solution to toluene in 10-mL volumetric flasks and dilute to the mark to prepare solutions in the range 0.02 to 0.5 mg CS 2/mL. b. Analyze together with samples and blanks (steps 11 and 12). c. Prepare calibration graph ([peak area] 1/2 vs. mg CS 2). NOTE: The FPD has a small linear range. Additional working standards may be required [9]. 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 a known amount (1 to 20 µL) 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. mg CS 2 recovered. Analyze three quality control blind spikes and three analyst spikes to insure that the calibration graph and DE graph are in control. NOTE: At low levels (<0.1 mg CS 2 per sample), DE may be low and variable.

MEASUREMENT: 11.

12.

Set gas chromatograph according to manufacturer's recommendations and to conditions given on page 1600-1. Inject sample aliquot manually using solvent flush technique or with autosampler. NOTE 1: The retention time for toluene is ca. 30 min, which may be shortened by temperature programming. NOTE 2: If peak area is above the linear range of the working standards, dilute an aliquot of desorbed sample with toluene, reanalyze, and apply the appropriate dilution factor in calculations. Measure peak area.

CALCULATIONS: 13.

14.

Determine the mass (corrected for DE), mg, of CS 2 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 CS 2 in the air volume sampled, V (L):

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