u/MobilePhase1987

Hello I was wondering if anyone could help me figure out what is wrong with my SRM method. When I run a full scan on my pesticide sample (picture 1) there are two distinct peaks for Endrin and Dieldrin. However after I set up my SRM method using the ions with the highest intensities, both peaks basically disappear (picture 2). I have tried to develop this method using transition pairings from literature I've found from our standard supplier as well as from ThermoFisher and I still encounter the same issues. Both scans were done with the exact same instrument method so I think it's pretty safe to rule out instrument settings. If anyone has any ideas please let me know.

Hello I am have issues developing an MRM method for pesticide testing, mainly with one compound: 4,4'-DDT. I do not have any issue finding the Q1 ions 235 and 237 however when I run a product ion scan our instrument isn't picking up any product ions as shown in picture 1. I can find all the Q1 and Q3 ions in all other compounds (picture 2) except for 4,4'-DDT and I was wondering if anyone could offer some advice on how to proceed. I have included the transition table for DDT as provided by our standard supplier (picture 3) for reference. It is really confusing because in the fullscan discovery (picture 4) you can see both the Q1 ions (235 and 237) as well as the Q3 ions (165 and 199). Any advice would be appreciated.

Hello I am trying to set up an SRM method however I am running into an issue where one compound, DDT, does not have any product ions. All the other compounds are good to go except for DDT. It's very strange considering the precursor ions are clearly there in picture 2, but none of them yielded any product ions. I'm using Thermo TraceFinder on a TSQ 8000 if that helps. Any advice would be greatly appreciated.

Hello I'm trying to run my sample but I'm running into big issues with what I think is column bleed (picture 2). I had an issue with leaking so I removed the guard column from the GCMS and am now only running the analytical column. I have read that conditioning a column with a leak could damage it and I am wondering if that is the case here because I would always find a leak at the connector between the analytical column and the guard column after running some samples and I wonder if the column is damaged. When I run the air/water spectra (picture 1) I notice what I think are pretty high levels of water and Argon. Is this indicative of a leak or something else? I have attached our most recent tuning report and it did pass the leak check for what it's worth. I was just wondering if anyone had a solution to bring down that high background from minute 18 and on. Thanks in advance.