I have analysed my air samples filter papers in SEM/EDX.
The compostion of elemets reported were in weight % and atmoic %.
But how do i convert those weight% reports to concentration values with reference to the pollutant concentration of that specific sample.
Dear Marimuthu,
you should know the weight of your filter paper (or at least the weight per area of your paper) at the beginning of the filter process. After finishing the filter process you should weight the sample again; and you have simple access to the weight fraction wfpollutant of pollutant and that of the filter paper (wffilterpaper) of your sample ( wfpollutant + wffilterpaper=1).
So weight%(with respect to pollutant) = weight%(fromEDX)/wfpollutant .
If you know the total content of different elements in terms of atomic percent you can convert them to their corresponding weights. Once you know the weight you can convert them to concentration.
Dear Gerhard
Say my initial weight of filter paper is 142.046 mg and final weight of filter paper is 142.302 mg.
I get EDX results in weight composition of elements.
E 1 = 10%
E 2 = 35%
E 3 = 67%
Then as per your suggestions,
Weight of individual element,
E 1 = (10% / 142.302)
E 2 = (35% / 142.302)
Dear Debasis
Thanks for your suggestions.
Once I get my results, will get back to you with my converted results.
Kindly help me in verifying them.
Dear Marimuthu,
you have to divide the EDX percentage by the weight fraction wfpollutant of the pollutant with respect to the whole sample.
I repeat your numbers:
Initial weight of filter 142.046 mg,
final weight of filter paper is 142.302 mg,
thus the pollutant contribution is:142,302mg-142,046mg=0,256mg
Thus the weight fraction of the pollutant with respect to the weight of the whole sample is:
wfpollutant = 0,256mg/142,302mg=0,0018.
Your EDX percentage now scales by 1/0,0018.
So for the 10, 35 and 67% ( pay attention: the sum exceeds 100%) of weight relative to the sample you will have
10%/0,0018=5555%,
35%/0,0018=19400%
and 67%/0,0018=37220% with respect to the pollutant.
But these results are imposssible, if the elemental signal only arises from the pollutant !!!!
If you are sure, that the detected elements arise solely from the pollutant, then the % EDX weights are relative to the pollutant and
absolute weights w1,2,3 be calculated simply by multiplication with the pollutant weight/100.
I will reflect on these calculations.
By the way: which of the elements you have been looked for?
Dear Gerhard
Thanks for your valuable answers.
Here we work on slot basis. My slot is by next week.
Im doing blind run analysis to determine the presence of various elements.
So once i get the results and after performing calculations as suggested by you, I will come back to you.
Please do the needful.
Dear Marimuthu,
when you mention that your slot is by next week,
so I assume, that your numbers mentioned above (10%, 35% and 67%) are only examples of numbers and no real results from any measurement.
So I am eager to see the real elemental %weights of your pollutant samples.
Good luck.
Dear Gerhard
Exactly they are assumed values for the calculation and conversion purpose.
Sure will discuss once the results are obtained.
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