Hi Winejia, I think your problem may well be harder than an LC approach as suggest by Darius will solve, as it is possible (probable) that the reaction intermediates are not known structurally so you don't have model spectrum of them. Complex solution equilibrium mixtures are about as tough as it gets for soluble EXAFS problems. The methods that tend to work are Principal component analysis (which is available in sixpack and Athena) This will probably tell you how many species you have in your reactant spectra, and will also tell you by target transformation if a spectrum of a model you have is one of those species. However to identify the unknowns you may need to use a more advanced approach like iterative transformation factor analysis (ITFA) . there is an itfa package available from the RoBL esrf beamline http://www.esrf.eu/UsersAndScience/Experiments/CRG/BM20/Software/ This should be able to give you the spectra of the separate solution spectra which then you can analyse with Artemis. The key things you need to have is more spectra representing in different ratios of the solution species than the total no of solution species, otherwise your problem is underdetermined, preferably quite a lot more. Regards Fred Prof. J F W Mosselmans Principal Beamline Scientist I18 Diamond Light Source Diamond House Harwell Campus Didcot Oxon OX11 ODE UK -- This e-mail and any attachments may contain confidential, copyright and or privileged material, and are for the use of the intended addressee only. If you are not the intended addressee or an authorised recipient of the addressee please notify us of receipt by returning the e-mail and do not use, copy, retain, distribute or disclose the information in or attached to the e-mail. Any opinions expressed within this e-mail are those of the individual and not necessarily of Diamond Light Source Ltd. Diamond Light Source Ltd. cannot guarantee that this e-mail or any attachments are free from viruses and we cannot accept liability for any damage which you may sustain as a result of software viruses which may be transmitted in or with the message. Diamond Light Source Limited (company no. 4375679). Registered in England and Wales with its registered office at Diamond House, Harwell Science and Innovation Campus, Didcot, Oxfordshire, OX11 0DE, United Kingdom