Dear LCGC,

I have an LC/MS with a D2 lamp that has 16,000 hours on it. Up until recently, it would still pass the intensity test of the instrument. Though it apparently performs what is needed, I am replacing it.

* What are the disadvantages of letting a lamp go beyond it's recommended time and wait for it to fail the intensity test?

The instrument is primarily used by post-doc organic chemists who check the MSD for a M+1 peak consistent with their intended product, but once in awhile the uv signal is used for quantitation, % purity, and uv characterization.

If I implement procedures that will increase the operating cost (ie. change every 2000 hours instead of when it fails the test), I want to give my boss validation for doing so. As well as explain to the post-docs why uv lamp time should be more conserved.

thanks

16000 hrs is incredible... we run 24x7 and rarely get more than 7000 hrs. What brand of lamp are you using?

disadvantage...
Unless you check the instensity test daily, how would you know when it has failed?

advantage...
costs savings of extended use past any preset change time.

it's the Agilent D2 long life lamp, Part# 5181-1530 list price $828. I think this lamp actually came with the instrument (it's an LC/MS 1100) when first purchased.

to clarify something: we do not look below 240nm and therefore ignore a fail on the 220nm.

when I became the new primary caretaker, the lamp already had about 8000 hours and I've never seen it pass the lowest wavelength (though never had pure water in the flowcell).

thanks readski. I take it from your message that others do extend beyond lamp life counter.