Thermo Scientific NITON XL3t 500 User Manual page 60

Cleaning Your Equipment:
Coning and Quartering
1-46 NITON XL3 Analyzer User's Guide
• Stir gently and warm the sample in a pan over a hot plate or burner.
You may need to divide your sample at various times during preparation.
Coning and quartering is a method for dividing the sample into
homogenous quarters.
• Pour the dry material slowly and carefully onto a flat sheet or pan,
forming a symmetrical cone. Divide the cone into equal piles using a
flat thin-bladed tool, such as a knife or ruler. Divide these in half
again.
• Now you have four samples, each one-quarter the size of the original
and each more homogenous than the original.
• Grind the sample to break up dirt clods and/or paint chips.
WARNING! Grinding and sifting dried samples produces dust. Even clean
soil contains silica, which may be hazardous when airborne. Prepare all
samples in a ventilated area; wear a mask, gloves, and an apron; and spread a
drop cloth.
Sift using the #10 (2mm) mesh and separate out the larger pieces (stones,
organic matter, metallic objects, etc. Examine the larger particles by eye but
do not include in the sample. Grind the sample again so its particles will be
finer and more homogenous. Use mortar and pestle, or an electrically
powered grinding mill. Sift at least 10 grams of the sample through #60
(250 µm) and #120 (125 µm) mesh. Re-grind the un-passed material until
the entire fraction is able to pass. Mix the resulting sample.
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