Endrin breakdown

Hi, I am running a 7890A with dual ECD's for multiple methods including 504, 505, 515, 552, 8081, and 8082. We got a super inert splitless injection port and weldment because we were having a lot of Endrin breakdown problems, and it seems to help but not eliminate the Endrin breakdown. I replaced our gas trap in January ( triple trap for oxygen, moisture and hydrocarbons ) using Nitrogen as our carrier and make-up gas. Seems like I almost always have to cut 1/2 loops off each analytical column and 1/2 loop off the guard column to have any chance of getting < 15% Endrin breakdown. Usually DDT breakdown is OK. I have frequently been cooling the injection port down to rinse and swab with MeCL2, Acetone, MeOH and Hexane, with some success. But it is not unusual to see 40-50% Endrin breakdown after a PCB run or 515 Herbicide run.

  Any ideas? We are using a pulsed splitless injection, Have lowered the injection port temp to 180, and use a drilled hole uniliner (Topaz from Restek). Not sure if there is something I am missing.

  Thanks, DaveD

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  • I am using a Topaz drilled hole uniliner from Restek as my injection port liner, A 5m. 0.32mm ID guard column, and 0.32mm ID RTX-CLP, RTX CLPII 30m. column pair from Restek. I always replace the Uniliners with new ones before running any pesticides. Yesterday I had a 19 injection run of drinking water 505 pesticides, and the initial Endrin breakdown check was 27.6% on the front column and 19.3% on the back column. At the end of the 19 injection run (all clean drinking water standards and samples) I re-ran the breakdown check and it was 60% on the front column and 45% on the back column.  My guess is there is either water in some of my extracts of gas impurities causing my Endrin breakdown to skyrocket after a short run of clean extracts.

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