2 Replies Latest reply on Sep 28, 2018 2:14 AM by johnbradley

    Dilution factor applied to a single analyte from a composite injection

    johnbradley

      Hi all.

       

      I have a situation where I need to inject a control prep with 65 analytes in it. However I've now realized the prep of the control solution is incorrect for just one analyte in the composite mix. I know that the Masshunter quant software can be used to apply a dilution factor to an injection, and that this would correct for any errors in concentration that were made for all analytes in the composite, but my question is, is it is possible to apply a dilution factor to just one analyte in the composite, since only one analyte is present at the incorrect concentration. If dilution factor cannot be used, is there something else that would allow me to apply a multiplier to the response for just that analyte.

       

      Any ideas welcome, thanks for your help.

       

      John.

       

      ross

        • Re: Dilution factor applied to a single analyte from a composite injection
          ryoboyle

          Hello,

           

          If this is just the concentration of one of your analytes in one of cal standards that needs to be updated, then you can do so from the Concentration Setup section of the Method Edit view. You can update the concentration for the affected level, or you could just un-check the 'Enable' checkbox for the affected level so that it is ignored during the analysis.

            • Re: Dilution factor applied to a single analyte from a composite injection
              johnbradley

              Thanks for the reply.

              So we did hit upon the idea of updating the quant method to reflect the true value of the mis-prep'd analyte, this does go some way to alleviating my problem, but doesn't entirely fix it (more detail below if you're interested). What I really need is a way of getting the software to apply a multiplier of 0.5 the response of the problem analyte.

               

              Details (it's complicated to explain, but I'll try lay it out as best I can)

               

              We run a screening method with a one point calibration curve. There are 65 analytes of different drug classes, Amphetamines, Benzos etc. The one point cal is at a different concentration for each drug class, Amphetamines are at 200ng/mL, Benzos at 50ngmL. etc etc. In addition to my Cal, we run in-house controls, control solutions consist of the same analytes, prepared at the same concentration as the Calibrator solution, but we add different volumes of the control solution to our control sample prep to produce a negative or positive control. Our negative control is run at -50% of the calibrator, our positive control is run at +50%. An example of the prep would be as follows,

               

              CALIBRATOR                               NEGATIVE CONTROL              POSITIVE CONTROL

              10uL Calibrator solution                 0uL calibrator solution                0uL calibrator solution

              0uL control                                   5uL control solution                   15uL control solution

              20uL ISTD solution                        20uL ISTD solution                    20uL ISTD

              20uL methanol                              25uL methanol                         15uL MeOH

               

              In my case I've prepared Analyte X at 10ng/mL in the Calibrator, but 20ng/mL (by mistake) in the control, all other analytes are prepared correctly. This means I can go ahead and use my control prep adding 50% less volume than the Calibrator for my negative control, and 50% more volume than the calibrator for my positive control, but analyte X will now give me 10ng/mL in my negative control (same as calibrator), and 30ng/mL in my positive control. If I could apply a multiplier to the responses of the controls, this mistake could be corrected for, and my Cal curve displaying the QC injections would essentially be correct.