Low sensitivity in ion trap

[zupahfly]

Hello,

I currently work with an Saturn 2000 Ion trap for detection and quantification of chloroanisoles. A few weeks back it started to loose sensitivity gradually without any alteration to the method or conditions (for example, a peak of 2,4,6 TCA 1 ng/L had 1K counts, and now i can't detect it below 100 ng/L).

I've cleaned the silchrome rings as i always did and it remained the same. I've increased target TIC from 5000 to 20000 and still the same. I've increased emission current to 80 uamps and i got i slight better response, but still not enough...

Should i replace the silchrome rings? they're a bit old and a bit "greyish" instead of blue...

Thank you

[Arne]

I assume this is GCMS? Cleaning the ionization volume and replacing the filament might help. Also, maybe you are loosing the compounds due to column activity. Trim 1m or so off the column.

[zupahfly]

Hi,

Thanks for your reply. I've done all your suggestions and i still have low sensitivity... My final solution might be replacing the electrodes?

Best regards

[Jonezy_Lothos]

Sounds like a leak. Check for leaks in all the right places (septa, column connections...)

Also, how are you introducing the sample into the GC? Purge and traps like to leak periodically and direct inject auto samplers can clog.

I like to do a full maintenance overhaul when it gets that bad.
1. change the column if its been over 6 months
2. change the glass liner and O-ring
3. new septa
4. change the trap (if using a P&T)
5. Leak check everything

Leak checking is probably the one thing that is often over looked. Getting a good leak detector (and using it ) can save you money in the long run