National Institute for Occupational Safety and Health

“ The recovery of DEA calculated from the methanol concentration varied from 70-95% in different generation runs. After studies were complete, the initial mixing chamber was rinsed with 2 m M HSA and was found to contain 52 mg DEA, and a rinse of the sampling chamber contained 23 mg DEA, indicating that DEA was lost in the generator during sample generation, and explaining the variation in recovery vs. that calculated from the methanol concentration. In the first run, four samples were generated to test the generation system. ”

“ Usual laboratory safety procedures should be exercised.
SAMPLING: 1. 2. 3. 4. 5. 6.
Calibrate each personal sampling pump with a representative sampler in line. Fill the impinger with 15 mL of 2 m M HSA. Mark the initial liquid level. Attach impinger to sampling pump with flexible tubing. Insert a glass wool trap between the impinger and sampling pump to prevent splashover. Sample at an accurately known flow rate between 0.5 and 1 L/min for a total sample size of 5 to 300 L. Fill the sample solution in the impinger to the 15-mL mark with distilled water. ”

“ Filter all samples, eluents, and water flowing through the ion chromatograph to avoid plugging system valves or columns. Transfer a portion of sample solution to a syringe fitted with an inline membrane filter, for direct injection or for transfer to autosampler vials. Inject 50-μL sample aliquot. For manual operation, inject 2 to 3 mL of sample from syringe (through inline filter) to ensure complete rinse of the sample loop. Measure peak height. If sample peak height exceeds the linear calibration range, dilute with eluent, reanalyze, and apply the appropriate dilution factor in calculations. ”