Dear Everyone, I did S K-edge XANES spectra for a variety of standard mixtures (disulphide and thiophene) with known different concentrations. I also attached the ATHENA project file here. My problem is: some of the fitting results I acquired using LCF do really not represent the actual weight percentage. The condition of my standards mixtures is as follow: For sample S3: ~59% disulphide and 41% thiophene. The reported value from LCF is 81.6% disulphide and 18.4% thiophene. For sample S4: ~79% disulphide and 21% thiophene. The reported value from LCF is 95% disulphide and 5% thiophene. I am not really sure what I did wrong, but I really hope the experts here can help me with this issue. Regards, Niken