文档介绍：MINERALS
Ashing
A. Dry Ashing
1. 550oC until light-gray ash or to constant wt.
2. Cool in dessicator
3. Weigh soon after reaching room temperature
Advantages:
1. Safe
2. Multiple samples
3. Only oven and dishes needed
 
Disadvantages:
Contamination
Wet Ashing
Oxidation pounds
Time: Completely oxidized
Advantages: Complete digestion
Disadvantages:
1. Explosion or corrosion
2. Requires time
Step 1: Ashing
Step 2: Solublize ash in Conc. HCl - boil and evaporate solution to dryness.
Step 3: Re-dissolve residue in N HCl.
Step 4: Conc. or dilute as desired
Step 5: Determination of ponents.
Elemental Analysis
1. Spectrometric Methods
2. Emission Spectroscopy - Flame Photometry Method
3. Atomic Absorption Spectrometry
METHODS FOR DETERMINING MINERAL CONSTITUENTS
Formation of plex with some ligand.
Example: Fe++ (Ferrous Ion) with phenanthroline (orthophenanthrolines).
1. Spectrophotometric Method
A pair of unshared electrons can coordinate certain metallic ions to plexes.
In the case of ferrous ion, the plex is quite stable and is intensely red in color.
plex is sometimes called Ferroin.
Measure the intensity of emitted radiation
2. Flame Emission Spectroscopy
Flame Emission Spectroscopy
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M+ -> M0 -> M* -> M0
3. Atomic Absorption Spectrometry
Hollow
Cathode
Lamp
Graphite
Furnace
Slit
Monochromator
Slit
Detector
Atomic Absorption spectroscopy involves the study of the absorption of radiant energy by neutral atoms in the gaseous state.