jimtrue.com : school : CJT2141 : 06: Inorganic Analysis
Posted by Jim True on February 12, 2003 6:00 AM. Last Updated October 22, 2006 9:23 PM
Disclaimer for all material noted here is at the bottom of this web page.
75% of the Earth's crust is made up of Oxygen and Silicon, less than 10 percent
is Carbon.
Trace elements - Ammunition, Tools, Inorganic
Brass - Copper & Zinc (CuZn... alloy)
Barium, Lead, Antimony, Bismuth
3 Different Instruments used in InOrganic Analysis:
1 - Emission Spectroscopy (p.151) - takes a sample, burns it up, puts out a
line spectrum on a piece of film (barcode). fingerprint of each element has to
be pulled out of the Emission Spectrograph. Will not separate, all ONE big
spectrum.
Qualitative, what is it?
Quantitative, how much is there
Qualitative - gives us what is there in the the Emission spectrograph, no
percentage of what is there.
2. Atomic Absorption Spectroscopy - Quantitative; take the sample and burn it
up with specific chemicals, only looking for specific elements. Can only look
for ONE element at a time. What it will tell you the percentage of that element
in that compound.
Use Emission Spectroscopy to identify elements there; Atomic Absorption to
determine how much of each element in the sample.
3. Neutron Activation Analysis - can look for 20 to 30 different element's
percentage at the same time. One drawback - need neutrons - need a nuclear
reactor to get the neutrons. MOST EXPENSIVE.
FDLE has the first two. Gunshot Residue cases. Colleges use Neutron Activation
Analysis.
SubAtomic Particles -
+ Proton,
0 Neutron and
- Electron
Isotope, atom of the same element with different number of neutrons in it's
nucleus.
One other method available, X-Ray Diffraction, can do both Qualitative &
Quantitative, but ONLY ON materials in CRYSTALLINE form. Technique is often
combined with Scanning Electron Microscope. (Look at a particle and analyse the
particle at the same time). Will not measure anything that is not AT LEAST 5%
or more of the compound. Positively Identify.
Know the Subatomic parts, Know the analysis methods and their limitations.
Disclaimer: These are MY notes taken from classroom lectures while I'm in the classroom. While I'm perfectly happy to share my notes with my classmates and I know I take very good notes, you should still make every effort to attend the class and TAKE YOUR OWN NOTES. I will not transcribe everything the instructor says in the classroom, and I will NEVER post pre-exam reviews. My notes will not replace the value of actually attending class and taking your own class notes.I also cannot attest to their accuracy, other than they are what was provided in the lecture; you should not reference my notes as "expert opionion" by any means, and if you notice an error or omission, please do me the favor of e-mailing me with the correction and I will re-post my notes. End of Disclaimer.