18 Replies Latest reply on Jan 15, 2019 8:00 PM by alfausett

    Warning: calibrated compound not found (GC-7890b)

    meelad

      Dear All,

       

      I analysed samples and standards with GC-7890b for CH4, N2O and CO2. I could see the peaks for each gas in each sample during running and everything was normal.

      When the work of machine has been finished, I checked the result out, I can't see peaks and I saw this message for each sample: Warning: calibrated compound not found!

      Could you please give me advice about this problem? Do you think I can fix it?

       

      Thank you so much,

      Milad

        • Re: Warning: calibrated compound not found (GC-7890b)
          abdur

          Is it possible that your retention times shifted causing the peaks to fall out of their windows?

          • Re: Warning: calibrated compound not found (GC-7890b)
            hebgent

            Hi Milad,

            Your problem is very strange.  What version of OpenLab are you using?  Is this the only method this happens with?

            Could you attach the method and data files?  It would be very helpful if I could take a close look at both.

            Tim

              • Re: Warning: calibrated compound not found (GC-7890b)
                meelad

                Dear Tim [hebgent],

                 

                Thank you so much for your reply.

                I have attached the method and data files. Please find them. In this file, 7890-0505 HS Samples_unsaved changes.M is the method, high1.D is standard and 1D.0D is my sample.

                Previously we didn't see this problem.

                 

                Milad

                  • Re: Warning: calibrated compound not found (GC-7890b)
                    alfausett

                    Hi Milad,

                     

                    Is this a factory-tested analyzer?  The naming convention of the method is similar to a targeted analyzer that shipped with a factory tested method.  I'm guessing maybe for Greenhouse Gases?  From time to time, the valve timings and flows need to be verified due to column age and other variables.   

                     

                    These systems have an adjustable needle valve just outside the valve box that can be sensitive to bumps.  I recommend following the setup instructions in the manual to measure flows in multiple valve positions and re-establishing the valve timings.  The manual ships on a CD-ROM with the valve diagram, checkout method, data, and other system-specific details.  Often, the service person performing the installation will put a copy on the PC for easy access. 

                     

                    Also, double-check the method setpoints to verify none of the pressure sources have been accidentally turned off.  Also check your valve actuator air and verify the valves are actually firing during the injection and throughout the run.  Leaks or plugs are always a possibility.  This system probably has a headspace, so plugged probes are common along with leaks around the transfer line.  Running the headspace leak and restriction test from the headspace front panel will help you troubleshoot the headspace independent of the GC. 

                     

                    There is a possibility the column(s) need to be replaced as well. 

                     

                    Keep us posted!

                     

                    Abbey

                      • Re: Warning: calibrated compound not found (GC-7890b)
                        meelad

                        Dear Abbey,

                         

                        Sorry for the late response,

                        Thank you so much for your explanation, it is like a guideline.

                        I checked out all process and everything looks fine. I just restart the program and windows and ran machine again. Surprisingly machine works and everything is okay. I am not sure what happened!

                         

                        Thank you so much for your time,

                        Milad

                          • Re: Warning: calibrated compound not found (GC-7890b)
                            alfausett

                            Fantastic!  I'm so happy we were able to get your peaks back.  Often with analyzers, one of the multiple pressure supply modules gets turned off when a cylinder is exchanged, or some type of maintenance is performed.  It is very easy to miss one of the set points when you aren't looking for so many. 

                             

                            Those manuals are invaluable for troubleshooting, but a re-boot and re-load is a great place to start.  Great work!  There is also a lot of great advice from our peers on this thread, should you run into trouble in the future. 

                             

                            Best,

                            Abbey

                        • Re: Warning: calibrated compound not found (GC-7890b)
                          hebgent

                          Hi Milad,

                          I looked at the method and data files and don't see anything wrong with them.  It is a bit unusual that you have the front detector listed as signal 2 and the back detector as signal 1 but there is no reason you can't specify it that way.

                          Since you are using a headspace there are all sorts of things that can cause no peaks (plugged lines / leaking lines / bad valves).  Can you confirm that you see peaks for the signals on the "Online Plot".  The data files look very much like blanks.

                          Tim

                      • Re: Warning: calibrated compound not found (GC-7890b)
                        meelad

                        Dear all,

                         

                        Thank you so much for your messages and your efforts to solve my problem.

                         

                        Best regards,

                        Milad