Chromatography Forum

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.

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

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

How can I figure out if this is the case?

same way you checked the flow cell

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 .