PROPYLENE DICHLORIDE: METHOD 1013, Issue 2, dated 15 August 1994 - Page 3 of 4
8. Add 1.0 mL eluent to each vial. Attach crimp cap to each vial immediately. 9. Allow to stand 30 min in an ultrasonic bath. CALIBRATION AND QUALITY CONTROL: 10. Calibrate daily with at least six working standards over the range 0.1 to 400 µg propylene dichloride per sample. a. Add known amounts of calibration stock solution, or a serial dilution thereof, to eluent in 10-mL volumetric flasks and dilute to the mark. b. Analyze together with samples and blanks (steps 13 and 14). c. Prepare calibration graph (peak height vs. µg propylene dichloride). 11. Determine desorption efficiency (DE) at least once for each batch of charcoal used for sampling in the calibration range (step 10). 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 serial dilution thereof, directly onto front sorbent section with a microliter syringe. c. Cap the tube. Allow to stand overnight. d. Desorb (steps 6 through 9) and analyze together with working standards (steps 13 and 14). e. Prepare a graph of DE vs. µg propylene dichloride recovered. 12. Analyze three quality control blind spikes and three analyst spikes to ensure that the calibration graph and DE graph are in control. MEASUREMENT: 13. Set gas chromatograph according to manufacturer’s recommendations and to conditions given on page 1013-1. Inject sample aliquot manually using solvent flush technique or with autosampler. NOTE: If peak height is above the linear range of the working standards, dilute with eluent, reanalyze, and apply the appropriate dilution factor in calculations. 14. Measure peak height. CALCULATIONS: 15. Determine the mass, µg (corrected for DE), of propylene dichloride found in the sample front ( ) and back ( ) sorbent sections, and in the average media blank front ( ) and back ( ) sorbent sections. NOTE: If > /10, report breakthrough and possible sample loss. 16. Calculate concentration, , of propylene dichloride in the air volume sampled, (L): , mg/m³. EVALUATION OF METHOD: Method P&CAM 321 was issued on June 15, 1980 [2] and was validated over the range 0.37 to 384 µg propylene dichloride per charcoal tube [1]. The for replicate measurements from generated atmospheres was 0.064 for 17 samples. Recoveries ranged from 97% to 103%. The pooled relative standard deviation for the analysis of spiked samplers was 0.031. The breakthrough volume was found to be about 20 L with sampling rates of 0.07 to 0.17 L/min at 1,2-dichloropropane concentrations of 62 to 85 mg/m³ at RH >90% and ca. 6 L at concentrations of 738 to 865 mg/m³. Desorption efficiency averaged 0.95 in the range 0.5 to 520 µg 1,2-dichloropropane per sampler.
NIOSH Manual of Analytical Methods (NMAM), Fourth Edition
