>Dear all, > >I am loocking for the formula to calculate the detection limits of analyses >using microprobe. Could anybody suggest me any reference?. Francisco, you can find well presented and detailed discussions on detection limits and counting statistics in: Jenkins, Gould & Gedcke 1995: Quantitative x-ray spectrometry. 2nd ed.,Dekker, New York, ISBN 0-8247-9554-7 and Bertin 1984: Priciples and practice of x-ray spectrometric analysis. 4nd ed., Plenum A good web link is the microprobe web page of James Wittke: http://jan.ucc.nau.edu/~wittke/Microprobe/Statistics.html Hope I helped. cheers, -Peter -- Peter Appel, [log in to unmask]