Extremely noisy baseline (agilent 1100)

[Frutasamir]

Greetings

We have an Agilent 1100 with DAD.

We were having a big problem with lamp intensity so we changed the flow cell and its components.

We performed all the tests in ChemStation and it passed all of them except for the baseline noise at 254 nm.

However, we decided to continue with using it since we are in need of sample analysis.

When we put the column and used an isocratic program of acetonitrile/water (15/85) the baseline noise at < 230 nm was extremely high (+- 30/50 mAU), and we need to use those wavelengths.

Our lamp has 1800 hours of use.

What do you suggest the problem and the solution might be?

Thank you in advance.

[Fernando]

Dear Frutasamir

Since I think you changed the cell for me, is the lamp that you have to change, it only has 1800 hours of use but try it.

Greetings

Fernando

[tkubowicz]

Hello

I'd recommend:

1.Disconnect your column from flowpath
2.Flush system with water
3.Make sure there is water in detector cell
4.Run tests for detector:
-intensity test
-filter test
-optionaly cell test

Noise and drift test should be performed on water and restriction capillary instead of column (noise can be from column or solvents)

If intesity test fails check new lamp or check achromatic lens.

Regards

Tomasz Kubowicz

[RHWoodman]

Hi, Frutasamir,

I've seen this before, and contamination of the system would be my first suspicion. tkubowicz has some good ideas for testing the system. You should do those first; however, Fernando also has a point. I have seen lamps fail with as few as 1200 hours, when 2000 hours of life was expected. If you run the tests recommended by tkubowicz and still don't know what's wrong with your instrument, try changing the lamp.

Best Regards,

RHWoodman

[JI2002]

How did the problem start? The baseline became very noisy all of the sudden or gradually? If it's the former, it's not likely caused by lamp. Anything changed since last time the system worked?

[Mike H.]

Remove the flowcell and do the intensity test again.