Page:NIOSH Manual of Analytical Methods - 2523.pdf/3

 1,3-CYCLOPENTADIENE: METHOD 2523, Issue 2, dated 15 August 1994 - Page 3 of 4 CALIBRATION AND QUALITY CONTROL: 8.

9.

10.

Calibrate daily with at least six working standards over the range 0.01 to 1.2 mg 1,3-cyclopentadiene (0.03 to 3 mg analyte) per sample. a. Add known amounts of calibration stock solution, or a dilution thereof, to ethyl acetate in 10-mL volumetric flasks and dilute to the mark. b. Analyze together with samples and blanks (steps 11 and 12). c. Prepare calibration graph (peak area vs. mg analyte). Determine recovery at least once for each lot of coated sorbent 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 (1 to 20 µL) of calibration stock solution, or a dilution thereof, directly onto front sorbent section with a microliter syringe. c. Cap the tube. Allow to stand overnight. d. Prepare (steps 5 through 7) and analyze together with working standards (steps 11 and 12). e. Prepare a graph of recovery vs. mg analyte recovered. Analyze three quality control blind spikes and three analyst spikes to ensure that the calibration graph and recovery graph are in control.

MEASUREMENT: 11.

12.

Set gas chromatograph according to manufacturer's recommendations and to conditions given on page 2523-1. Inject sample aliquot manually using solvent flush technique or with autosampler. t r = 6.5 min under these conditions. NOTE: If peak area is above the linear range of the working standards, dilute with ethyl acetate, reanalyze, and apply the appropriate dilution factor in calculations. Measure peak area.

CALCULATIONS: 13.

14.

Determine the mass, mg (corrected for recovery) 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 1,3-cyclopentadiene in the air volume sampled, V (L) applying the factor 0.403 (MW of 1,3-cyclopentadiene/MW of analyte) for conversion of adduct to 1,3cyclopentadiene:

EVALUATION OF METHOD: P&CAM 294 [2] was issued in 1978 and evaluated over the range 73.4 to 370 mg/m 3 [1,3]. The average recovery for 3-L air samples was 1.036 which represents a non-significant bias. Test atmospheres were generated using a syringe pump delivering 3a,4,7,7a-tetrahydro-4,7-methano-1H-indene (dicyclopentadiene) to a glass pyrolysis tube which thermally decomposed (375 °C) the dimer to monomer. The concentrations of 1,3-cyclopentadiene were confirmed by collecting samples from the generator in bubblers containing 15 mL solution of 74 mg/mL maleic anhydride in ethyl acetate and analysis by GC/FID. Samples were stored at room temperature for one week and found to be stable. Recovery averaged 0.99 in the range 0.75 to 3 mg analyte (equivalent to 0.3 to 1.2 mg 1,3-cyclopentadiene) per sample. Breakthrough capacity exceeded 3.8 mg NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94