Agilent 1100 HPLC DAD

[MitchHowell]

Hi guys,

I have this strange problem lately.

I use the DAD to run colorant samples in Agilent HPLC. The DAD turned red intermittently. No error message is displayed in log, just RUN HALTED in log. The DAD led turned red.

My analysts extended the run for another 20 mins and the problem seemed solved for several months. Recently, the problem came back even with extended run.

The same method runs on another Agilent 1100 DAD does not have this problem. What's wrong with it?

1. DAD lamp?
2. dirty flow cell?
3. faulty optical unit inside DAD?
4. Mainboard?
5. Problem with colorant samples as spectrum is stored during run?

Thanks for advice.

Mitch

[R13]

Well, if You are using Chemstation - there should be a message in instrument control window about the reason.

Basically it indicates the fault which can be detected by the instrumnt electronically, which rules out No 2 and 5 on Your list.

Othervise it can be something trivial like leak or something serious like internal electronics failure. Without more information about circumstances, freequency of the fault is difficult to diagnose without standing next to the instrument. It is like Your TV at home would stop working and service would try to diagnose it via e-mail.....

[LCbob]

Hi
In follow up to R13's reply, if you have a controller G1323x, look under error messages and it will indicate why it stopped. If it is an undefined error, look at the error messages for each module, they may have had a problem that stopped the DAD.
Lastly has your degasser red lighted? There is cable that can be installed between the degasser and the pump that can cause the system to error.

[lmh]

Also if you are using Chemstation, as well as looking at the error message in the instrument control window, check the log books!
There are two log-books. The most relevant is that belonging to the sequence that was running at the time. Go to view, log-book, and open log-book; you'll find the book in the folder where the results for that sequence were placed. These log-book entries give far more detail about what caused an error than the on-screen information, and are useful when one error triggers a lot of other errors.

[KDF]

I agree with checking the log. It should tell whether there has been a lamp overrun.

I will offer one bit of related experience I had with colorants. I once tested some concentrated food coloring in a preparative system to measure delay times. The original solution appeared particulate free although it filtered out most of the transmitted light. I would run samples and get very concentrated peaks [way off scale] then a long period of drifting baseline to come back to zero. It turned out that the colorant masked the turbidity of the solution and part of the dye stuck on the column frit and would continue to build up and only redissolve at a slow rate. Simple filtering of the sample with a filter smaller than the frit porosity solved the problem.

If this is your case and you are simply autozeroing after each run,you might be running out of lamp intensity as the colorant builds up. The same thing might happen if the mobile phase is not compatible with the colorant.