11 Replies Latest reply on Jun 4, 2018 2:23 PM by gchaplain

    5975C GC/MS 219 ION HIGH

    elisteve

      After cleaning the source on a 5975C GC/MS and performing atune, the 219 ion is high, roughly equal to the 69 ion, and sometimes greater. The response of 69 is normal (219 is high, 69 is not low). This instrument is used for volatiles analysis and now will not pass the required bromofluorobenzene tuning criteria, since the 173-177 bfb ions are too high relative to the bfb 95 base ion. 219 cannot be lowered enough through manual tuning. The source, quad and transfer line are at the proper temperatures. Any solution to this? Try re-cleaning?

        • Re: 5975C GC/MS 219 ION HIGH
          ryan_ohearn

          Are you using the BFB Autotune or the BFB Tune?  Sometimes one works better than the other.

          You can also try switching filaments or replacing the filaments and repeller insulators (G1099-20133) and the lens insulator (G3170-20530).

           

            • Re: 5975C GC/MS 219 ION HIGH
              elisteve

              We normally use BFB Autotune. BFB Target Tune also fails with the default settings. The filaments are both new and both act the same. When I cleaned the source I found the lens insulator was cracked so that was replaced. Dynamically ramping the entrance lens voltage and manually setting it to a lower than normal value at ion 219 brings it down. BFB Target tune also ramps the entrance lens and you can manually modify the voltages that result. We've never had to do this before so it seems there is something wrong?

                • Re: 5975C GC/MS 219 ION HIGH
                  ryan_ohearn

                  Sometimes having the 219 higher than 69 happened a lot on the 5973, haven't really seen it much on the 5975/5977 due to different detector back end.  You could try re-cleaning and verifying everything, maybe also squeeze the lens assembly and the source body together when putting back together and tightening the gold screw since the source body is the only electrical connection to the drawout plate and cylinder.  You can use the link below to a cleaning document that has a lot of useful details.

                  How to clean an Agilent GCMS HES Ion Source

                    • Re: 5975C GC/MS 219 ION HIGH
                      elisteve

                      I took it down and cleaned the source again (for the 3rd time). I didn't see anything amiss, but now the 69/219 ratio is normal and bfb tune passes. Not sure what the issue was but it appears to be fixed.

                        • Re: 5975C GC/MS 219 ION HIGH
                          james_jenkins

                          Hi elisteve,

                          I was following your progress , glad it worked out with Ryan's help. One point of information that is important here is that the BFB tunes are built off of the Atune. If there are tuning issues, a quick check is to Atune, then followed by one of the BFB tunes to make sure all are fresh and up to date.

                            • Re: 5975C GC/MS 219 ION HIGH
                              elisteve

                              We still have the issue of 219 ion being the base peak instead of 69 on our 5975C used for EPA volatiles analysis. This occurs during atune and also the BFBAutotune. The only way we can get it to pass a BFB tune is to ramp the Entrance Lens Offset to lower 219 into the range it needs to be. Otherwise the 173 to 177 ions in BFB are too high. We are using the BFBAutotune routine modified to ramp the offset. Even though it generally passes, we would like to correct this issue. Any ideas?

                      • Re: 5975C GC/MS 219 ION HIGH
                        ryan_ohearn

                        On the 5973 and 5975 it isn’t uncommon to have 219 as the base peak instead of 69. Happens a lot more on 73s though because of older HED-detector design.

                         

                        You could try switching the DC polarity of the quads in the ATune and also BFB tunes and saving and seeing if that helps.

                         

                        It usually means the source and quad are transferring more higher mass ions than lighter ones. Which is usually a good thing except when it comes to doing BFB...

                         

                        Thank you,

                         

                        Ryan O'Hearn

                        Field System Engineer - Upstate NY / E. PA

                        Agilent Technologies, Inc.

                        (585) 752-4960

                         

                        Did you know that you can log your service requests with Agilent via the web?

                        www.agilent.com/chem/repair<http://www.agilent.com/chem/repair>

                         

                        Join the online Agilent Community today:

                        https://community.agilent.com<https://community.agilent.com/welcome?CID=13274>

                      • Re: 5975C GC/MS 219 ION HIGH
                        m4esti

                        Hi Elisteve,

                        For tuning for BFB, you might want to try the Alt BFB tuning procedure in the Communities application section. I have used it many times and it does work.

                         

                        Regards,

                         

                        Mitch

                        2 people found this helpful
                        • Re: 5975C GC/MS 219 ION HIGH
                          gchaplain

                          quick question, is there flow going into the MS?

                           

                          Sometimes if the vacuum is too strong it can cause higher masses to get higher responses. So if the flow is low or non-existant then this could be the cause.

                           

                          Or if the method it's tuning on isn't your Standby.M method, or the correct Standby.M method. This has happened a few times to me before giving out of the ordinary tune results.