UPLC/TQD injection problem

MikeT

<p>Greetings</p><p></p><p>I need some advice on an injection issue I had with our UPLC/TQD the other day. Basically I was not getting any peaks at all for this anti-psychotic screen I've been developing. It is a screen for ten different drugs and one internal standard (Clozapine-D4). The injection mode is FL, 10 uL (10 uL loop). It uses an ammonium acetate/ACN gradient mobile phase. ESI+. Anyway I made sure injection mode was on LC, looked for bubbles in the sample syringe. Tried injecting a test mix, nothing. Tried a sample needle seal leak test and syringe leak test and they passed.</p><p></p><p>After a while I gave up, shut the instrument down and went to lunch. Came back and tried another method and now get peaks. Reloaded my anti-psychotic project and got those peaks as well. </p><p></p><p>What could cause this? Also how can I position the sample needle to visually inspect it for damage? It looks like it is sampling correctly but I cannot see the needle tip.</p><p></p><p>TIA</p><p></p><p>Mike</p>

lizh

Mike:

It is interesting to me that you stated "tried another instrument method". I would compare the intrument methods and see what the differences were.

There is a capability in ACQUITY UPLC to create a service profile (under the console troubleshooting menu) and this includes a listing of all the log files, which we could inspect, for MassLynx, or for Empower, you can look at the console logs directly. Are you using Empower or MassLynx to control?

I suspect a syringe speed setting and/or priming issue - which I think you supect this too.

Let us know,

Liz

MikeT

We are using MassLynx. What do I do with the service profile once I create it?

thx

Mike

lizh

Mike

Can you look for the log file (Program Files/Waters Instruments/LogDatabase) adn take a look at the list of messages from when you were working, does anything jump out.

Many TX

Liz

MikeT

Hi Liz

The only alarm error received is "Zp-axis h/w needle lost steps (520)." This was when starting a run right after I did needle seal test (which passed).

The main difference between methods is the Psycho method I've been working on is a gradient vs isocratic (same mobile phase), ESI+ vs ESI-, and a different column is used. There were no pressure issues though and I was getting spray at the probe.

Mike

lizh

Mike

Then that does not sound like an instrument issue, it sounds like smething else. Any other suspicious occurances since then?

Liz

MikeT

Occasionally I get the error "Degasser communications HW error." Last happened on 4-15-10. Have to reset the BSM. Seems to be ok after resetting.

Mike

lizh

Hello,

I spoke to Global Service Support and they said that when this error is typically generated we suspect a failure at the electronics level. This could be caused by loose cable connections or related to the circuit board.

So depending on your level of comfort - this can be left to a Waters Service Engineer to check, the normal recommendation would be to turn off power to the BSM and unplug the instrument from the power source. Remove the right side panel to the instrument. Reseat cables on the degasser circuit board and check cables at Personality PCB A (QSPI Interface). If problem persists the issue could be related to a bad Degasser PCB.

Let us know,

Regards

Liz

MikeT

Thanks Liz, I called service and they said to keep an eye on it and they'll send someone if or when it happens more consistantly. I'm not comfortable taking off the cover and resetting the cables myself.

Mike