I have noticed on the CAP DAT surveys from 2013 that about 12 or so facilities are using buffered gel cards when performing their C3 DAT using anti-C3b/C3d reagent. We are in the process of validating this method and was wondering if anyone out there who is doing this has a validation/ comparison and SOP to share with us. We just want to make sure we are on the right track. We especially want to know what is used for controls. Thank you!