Why stop-and-start for Tempo nanoLC?

[csgan]

Hi guys,

We have an Eksigent powered Tempo nanoLC attached to our ABI QStar Elite with a New Objective nanospray source. This nanoLC frequently stop-and-start at the end of each runs to reset the amplifier (Not sure why). This has affected the spray pattern, and the tip was dead within days. I understand from some of my collegues elsewhere using this nanoLC do not have such problems. I suppose this stop-and-start occurrence does not affect those Nanobore LC using a separate Picotip with a separate analytical column.

Our nanospray set-up is a Picofrit column with an integral tip at the end. This set-up cannot withstand the sudden drop in pressure even though the voltage is in place. This is the common phenomenon we see across all our platform here irrespective to any type of LC.

Would appreciate some guidance and feedback if you have similar set-up.

Cheers.

[sassman]

Hi csgan, I am jealous of your system. I have never used a nano-spray source. The only time that I have seen a capillary or needle die quickly is usually from clogging. Do you have dissolved salts in the mobile phase or in the sample, and are both filtered? I have also seen damage to a capillary and needle tip from arcing between the needle and spray plate. This may happen when you are not watching, so try to watch what is happening in the source.

[csgan]

Hi sassman,

Thanks for sharing your experience. We don't use any salt in our mobile phase. For our sample, we were testing with standard protein mixture dissolved in 0.1% FA. I am also thinking it might be arcing between the needle and spray plate. Everytime the nanoLC stop-and-start after each run, pressure droped to almost zero, then recovered after few minutes. But after this restart, liquid droplet started to form (even though the voltage is on all the time) and didn't spray properly after a few more runs. It certainly frustrating for us!

Cheers.

[avitan]

Dear Csgan

As far as I know, Eksigent nanoLC pump piston should restroke itself sometimes. If this happens too often than it might be a sign of some problem. For instance: air bubbles in pump, damaged checkvalve, clogged inner filter, internal leak.