MTBE Response!

[anabolic1980]

Hello ALL!
Analyzing MTBE via EPA 8260B and past week MTBE has disappeared from the chromatogram. If I do a direct inject (bypassing the P/T system), MTBE shows up. If I then purge a sample after I do a direct inject, MTBE will be present for about 1-2 samples then disappear again. I tried another new trap with same issue. This system has been in use 5 years with no problem like this. Any help is greatly appreciated! Tekmar Velocity/ HP 5890 split 20:1/ 5971 mass spec.

Tyler

[Chandresh K. Soni]

It May be the problem of your column.
may be the column resolution or selectivity is reduced hence this problem arises.

[AICMM]

anabolic1980,

I would be more likely to suspect that your purge and trap or transfer line are activated. You might try purging some methanol or ethanol to dry things out, or simply warm everthing up 20-30 degrees for some hours. If this does not work, based on your post, the next thing to do would be to change out columns.

Best regards.

[Bigbear]

When you say direct inject do you use the test injection port for your Velocity? This tests the sample path from the top of the dry flow trap when you inject durring desorb. When you have this installed you can inject a sample while the unit is in dry purge. This will isolate the purge plumbing from the system. When I had this problem it was from the blank dry trap which had become active.

Good luck