|MadSci Network: Environment|
1) take a bit of the contaminated sand, weigh it exactly, do an extraction
(e.g. by shaking) with petrol ether or hexane etc.
take the extract and condense to dryness...carefully!!!! no flame allowed for danger of fire !!!!!(definitely ask your supervisor how to do that exactly with the equipment that you have) weigh the residue after the evaporation.
amounts of sand needed will be very much dependemd on the precision of Your ballances and the amount you spiked in the beginning.
The feasability of this approach is also very much dependent on what you use to "clean" the sand.
2) take a bit of the non contaminated sand, do the same procedure. The difference should be the residue of your oil.
For a more advanced analysis:
First Cooking oil consists of basically 100% triglycerides. Crude oil (or
petrol, gas however you want to name it) consists mainly of alkanes, alkenes
and PAHs. So there will be major differences in cleaning and in
weighing will certainly do no good :-).
The easiest thing to do is put a representative sample on an infrared spectrometer, do an evaluation on the alkyl CH-vibration That should be doing fine for crude oil and cooking oil.
Second thing (bit more reliable, but needs more instruments and training) Do an extract of the sand with e.g. Dichloromethane od hexane. concentrate and inject to a Gaschromatograph with flame ionisation detection or (preferably mass spectrometric detection) do a calibration on Triuglycerides (or alkanes depending on you problem). If you definitely want to go for cooking oil (for whatever reason) it might be better to first cleave the triglycerides by treatment with sodium hydroxide, and do a methylation afterwards. go than to GC procedures. Robert, this is a brief summary. There dozens of methods, and you will find methods in any analytical textbook.
As I do not know more about your background an possibilities, I will leave it like this for the moment, kind regards
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