[martyn11post]

Hi,

I've got these results from SEM-EDS analysis:
Elmt   Spect. Element  Atomic
        Type     %       %   
O  K     ED     9.73    17.00 
Na K     ED    25.33    30.80 
Si K     ED     4.81     4.78 
Cl K     ED    60.13    47.41 
Total         100.00   100.00

I've been trying to work out the percentage of NaCl. But if I calculate it off the element% figures I have an excess of Cl  . I was told these were the figures to use. Except if I perform the calculation off the atomic% I get a more realistic figure. I believe the atomic% is element%/Atomic wt. and then normalised to 100%.

Also am I right in thinking elements below Na are less accurate? I realise H - Boron cannot be analysed.

Many thanks,
Martyn