National Institute for Occupational Safety and Health

Summary

National Institute for Occupational Safety and Health NIOSH Manual of Analytical Methods… (1994)

If possible, generate the correction curve data on the same day that coal mine dust samples are analyzed since curve param eters may vary somewhat from day to day. A curve through the points should be linear but will not pass through the origin since the peak at 915 cm ! 1 is more intense than the peak at 800 cm ! 1 and sm all am oun ts of kaolinite do not interfere with the quartz analysis. NOTE 1: Ka olinite correctio n calibration curve is required when s am ples are ashed in an LTA since kaolinite is not destroyed under these circum stances a nd has a s interfering peak at 800 cm !
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National Institute for Occupational Safety and Health NIOSH Manual of Analytical Methods… (1994)

Insert the sample into the beam of the spectrophotometer. Place the other half of the DM-450 filter on another holder, secure with a magnet and insert it into the reference beam. NOTE: For the best precision, the referenc e filter should be half of the same DM -450 filter which contains the redeposit. However, for routine analysis, the same 2-propanol-treated blank can be used for all filters with the sam e lot numb er. Run an infrared scan, in linear absorbance mode from 1000 to 650 cm ! 1. Draw an app ropriate baseline under the absorbance band at 800 cm ! 1 from ca. 820 to 670 cm ! 1.
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National Institute for Occupational Safety and Health NIOSH Manual of Analytical Methods… (1994)

Accuracy depends on obtaining uniform deposition of samples and standards across the filter surface and obtaining re prod ucible aliquo ts from the quartz s usp ens ion. This requires som e skill. The quartz calibration curve should be prepared before analyzing samples as a check on the analyst's ability to prepare uniform deposits. Repeatability should be <10% on re plicate standard s with m ore than 4 0 μg qua rtz. Perform an IR scan for each standard filter using the other half of the filter in the reference beam (steps 10 through 12) .
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