I used the EDX to map the element distribute of biological specimen, such as Calcium. Does this mapping show me the distribute of protein -bound calcium or free (ionic) calcium? I checked some literatures but did not get a clear answer.
In general, it is a wrong way for soft biological samples. The precision of the method is not enough for soft tissues. It is acceptable (with accurate operation and using standards) for hard tissues - bones and teeth, but not for muscles, brain, liver, etc.
@Denis Korneev
Thanks for replying. I understand it is not a good method but I couldn't find a better way to show the element distribute in the cells. There are some literatures showing the element mapping on different types of cells.
@ Zihui Wang
Nevertheless, EDX just cannot help in this case. Sad but true. Just fundamental limitations.
Sometimes people make EDX mapping and interpret it too optimistic. The difference between "elements distribution in the cell" and noise/artifacts is very tiny... ;-)
In my opinion, scanning electrochemical microscopy and nanocapillary techniques are more suitable in this case.
Good luck!
As EDX is not providing an insight into the valence state / binding of an element, besides the above mentioned limitations regarding resolution, I would be careful to draw any conclusions. Here you need a method able to distinguish between different chemical states and suitable to analyze biological samples without destroying the sample chemistry / structure instantly
EDX will only show that calcium IS present, but cannot be used to differentiate between the two. XPS is a better tool to look at valence states/binding, although correct sample prep is crucial for biological samples- refer the literatur.
@Roshini Ramachandran Thanks for your suggestion. I will take care in the sample preparation.
As I konw, TEM EELS can identify the chemical valence of element, especially the light one.
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