Agilent 1290 DAD has low intensity at UV wavelengths

[davidupp]

We have an Agilent 1290 Infinity UHPLC setup. Our DAD is a G4212A.

A few weeks ago I started seeing low intensity (<50 counts) at wavelengths lower than 250 nm. The lamp had 1700 hours of burn time, so that seemed to be the problem. After installing a new lamp (purchased 2 weeks ago from Agilent) and performing calibration, which it passed, the intensity counts at low wavelengths was still essentially 0. I borrowed a new flow cell from a working instrument to see if that was the issue, but once again I'm seeing no intensity at <250 nm.

I'm all out of ideas here. I spoke with Agilent and they think it might be an electronics issue, but that seems weird to me because all other wavelengths look great.

Any other ideas or things I can try?

Thanks in advance.

[vmu]

The part of the diode array that measures low wavelengths might be damaged.

[davidupp]

The part of the diode array that measures low wavelengths might be damaged.

How can I figure out if this is the case?

[DR]

same way you checked the flow cell

[ATAlR]

Is this DAD with cartridge cell (G4212a/b?), if yes you have to use Max-light cartridge cell, and with degassed water at flow of 1mL/min trough the cell. Without the flow my detector also show results below 100 counts while with flow it pass test with 4000+ counts .