Greetings! We are currently doing a study about the elemental composition of ambient particles in the atmosphere. Basically, here's what we do: (1) Get samples of particulates using an air sampler with known flow rate. The particulates are deposited on a filter. One filter is used per sampling. (2) Determine the concentration of the particulates using gravimetric analysis and the flow rate of the sampler. (3) Determine the shape and elemental composition of 24 particles (chosen randomly) per filter using Scanning Electron Microscope and Energy Dispersive Analysis. Question: Is there a way to obtain the elemental concentration of certain elements per filter using EDX analysis and the particulate concentration? An EDX analysis yields only atomic and weight percentages per particle. And I only analyze 24 particles, a very small fraction of the total number of particles deposited on the filter. I need to get the elemental concentration of selected elements per filter since our adviser wants us to use Positive Matrix Factorization (PMF) for source apportionment. PMF needs elemental concentration per filter, not atomic/weight percentages of some particles in a filter, as input. If the answer to the previous answer is no, is there an alternative method for source apportionment where my data can be used as inputs? Thank you very much for your help and for reading this post.