urine cortisol interference

<p>We are using the uplc TQD for the analysis of the urine free cortisol. Transition peaks: 121 and 97 are used for the quantification and confirmation. However, in the low concentration urine samples, we always found two or sometimes three interference peaks for both transition peaks. (The standard curve and QC samples are always good and no interference peaks).Those interference peaks do not affect the quantification because they are separated with the transition peaks, but we would like to know what they are. Anyone knows that which compound those interference peaks belong to?</p>


  • STC

    It would help if you could provide a mass spectrum of those interferences.

  • DM

    The problem is we could not get a clear mass spectrum using MS scan because several compounds elute at the same retention time. If we can I guess we will know what they are. we are thinking using column separation and purification to get a pure fraction for the identification but that will take forever.