in-situ Photo degradation

[The Chemist]

Has anybody come across of photodegradation in DAD cell (Agilent 1290 DAD)?
basically we see (by MS) potential photo degradant under the main component when we go to MS via DAD detector. If we bypass DAD- the extra component is not detected

I was just wondering how common occurence is this

[tom jupille]

Probably more common than anyone realizes, because:
a. the DAD hits the sample with broad-spectrum UV (unlike a variable-wavelength detector where only the detection wavelength is used. But
b. nobody looks for it, and
c. it presumably happens the same way with both calibrators and samples, and so any quantitative effects usually cancel out.

That said, I heard about a situation where a monomer photopolymerized in the cell (the chromatography had separated it from the inhibitor). My recellection is that the cell had to be replaced.