I am working with some people that are using Watson and MacQuan to quantify LC/MS/MS data. It would appear that, for the standard curve that is reported, iterations are performed and the final standard curve is based upon the response vs. the calculated standard concentrations, as opposed to the "theoretical" standard concentrations, i.e,. what you weighed in. I have never seen this before and am wondering if this is a common practice with LC/MS/MS data. Any information about this will be greatly appreciated.