||Applicable for the analysis of quartz in coal
dust. Samples are ashed, mixed with KBr and pressed into a pellet for presentation in the
instrument. Cristobalite, tridymite, amorphous silica, and many silicates in common
minerals and glasses interfere in the IR analysis of quartz silica because they have
common absorption bands. The clay silicate common to coal is accounted for and the effect
of the interference is subtracted. Silicates are very common representing nearly 95% of
the volume of the earth's crust. Applicability to non-coal matrices should be
determined on a case-by-case basis. Muffle furnace ashing method may require acid pre-wash
to remove CaCO3. Calls for use of NIST-traceable Standard Reference Material (SRM) or
Min-U-Sil 5 (Pennsylvania Glass Sand Co., Berkley Springs, WV).
[130 KB PDF]
|Similar to MSHA P-7 and based on NIOSH P&CAM
110 with mixing of sample with KBr and pressing into a pellet for presentation in the
instrument. Can be used to analyze quartz or cristobalite or tridymite or
quartz-and-cristobalite. The latter mixture requires use of an alternate, less sensitive
absorption band. Silicates can be removed using a phosphoric acid cleanup procedure. Calls
for use of NIST-traceable Standard Reference Material (SRM).
|NIOSH P&CAM 110
||Similar to MSHA P-7. Earlier version of NIOSH
7602. Does not specify use of Standard Reference Material. Replaced by NIOSH 7602.
[120 KB PDF]
|Similar to MSHA P-7 with redeposit of the sample
on a filter for presentation in the instrument. Calls for use of NIST-traceable Standard
Reference Material (SRM). Infrared light scattering depends on the amount of respirable
dust present (both crystalline silica and matrix) and may be stronger than when using a
KBr pellet. Such scattering affects the baseline and may lead to non-linear response.