what is the lifetime of a Deuterium lamp?

Discussions about HPLC, CE, TLC, SFC, and other "liquid phase" separation techniques.

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The HPLC user manual says the life time of a deuterium lamp is about 1000 hours, it also says, "if the light output becomes too low and adjusting the attenuators does not help, replace the lamp". I take it as "you can use it as long as the output is OK'.

Our lamp has 1200 hours on it, when the least attenuated, the output is 70000 intensity counts, which is one 10th of the expected. However, we can still get satisfactory response for the current experiments.

Should I replace the lamp? How many hours do you have before get rid of it?

It's partly a function of the wavelengths you run at. The lower you need, the more problems you are likely to see. A lamp that's useless at 210nm may work nearly perfectly at 340nm and be acceptable at 280nm.

Generally, they *should* go 1000 hours, of course, there's variation. Sometimes you'll get 700h, sometimes 2000h.

Sounds like it's time for you to order one.
Thanks,
DR
Image

Thanks. This is the first time I take charge of maintenance. But I do have some experience in several other research groups. In my previous experience, I never saw people replace lamp, and nobody cares to turn off lamps at the end of day, they flush the system overnight with lamps on. Seems to me lamps can work forever. Did they replace seceretely while I wasn't there?


DR wrote:
It's partly a function of the wavelengths you run at. The lower you need, the more problems you are likely to see. A lamp that's useless at 210nm may work nearly perfectly at 340nm and be acceptable at 280nm.

Generally, they *should* go 1000 hours, of course, there's variation. Sometimes you'll get 700h, sometimes 2000h.

Sounds like it's time for you to order one.

Oh, by the way, I think I know who you are. Are you David?

DR wrote:
It's partly a function of the wavelengths you run at. The lower you need, the more problems you are likely to see. A lamp that's useless at 210nm may work nearly perfectly at 340nm and be acceptable at 280nm.

Generally, they *should* go 1000 hours, of course, there's variation. Sometimes you'll get 700h, sometimes 2000h.

Sounds like it's time for you to order one.

Just a couple of additions to DR's comments.

Some deuterium lamps used to have limited shelf-lives, so don't stock up on too many, unless you know they store well.
If your lamp gives fewer hours than specified, ask for a considerable discount on the replacement lamp.
Whether there is a feedback feature that drives the lamp harder at lower wavelengths depends on the detector's electronics, in my experience Agilent 1050 and 1100 VWD and 1100 DAD lamps seem to last longer if used around 230 - 250 nm. Although energy peaks around 240 nm, solvent often absorb at the lower wavelengths.
Deuterium lamps have reasonable energy delivery over the range 210 - 340 nm, but the energy drops off significantly outside that region and solvents may also absorb at the lower wavelengths. Some detector electronic feedback may drive the lamp harder, especially if only those wavelengths are being measured.

Please keep having fun,

Bruce Hamilton

I have seen lamps lasting +7000 hours (the manual stated average lifetime to be 1500 hours).

And then I have seen lamps failing at 1500 hours (the manual in this case stated average lifetime to be 1500 hours, pretty accurate to say the least).

Lamps usually stay on over night but will be switched off on weekends if no runs are scheduled.
--
Robert Haefele

thank you so much guys.

No problem.


-Not David.
Thanks,
DR
Image

If the analyte signal is sufficiently large, then a sub-standard lamp energy output may not be a practical problem - in many cases. This issue becomes important when trace amounts are considered. That is when the S/N ratio is greatly reduced, leading to more noise being observed on the baseline. Reliability in peak integration may even suffer. Correct me if I'm wrong, but this has the potential to effectively alter the response factor by a large margin.

As for turning off detector lamp after analysis: One can always create a sequence file to include a method which simply turns the lamp and pump off. Even wash the column if so wish (some people may not like this). Then queue this sequence file straight after your current run sequence - that is, if you are running a sequence for unattended automation :-)

Good luck.

Dear all:
We normally replace the UV lamps after >3000 hours. They are not cheap ($600-800 each), but they must be replaced as part of PM.

Once, we kept the UV lamp on the Dionex LC much longer, just to see how long it would last. It had lamp intensity reduced to ~280,000 counts (original ~800,000 counts/s) when we decided to change. It lasted for ~4500 hours. We normally use low UV (210-245nm).

One day all that extra free hours will be charged...
That´s why I Love replace Power supply PCB for D2 Lamps.
:lol:


Alfred88 wrote:
Dear all:
We normally replace the UV lamps after >3000 hours. They are not cheap ($600-800 each), but they must be replaced as part of PM.

Once, we kept the UV lamp on the Dionex LC much longer, just to see how long it would last. It had lamp intensity reduced to ~280,000 counts (original ~800,000 counts/s) when we decided to change. It lasted for ~4500 hours. We normally use low UV (210-245nm).

manufacturers will generally state the life time that they will warrant. this can vary from 1000 to 2000 hours these days.
in general we use it until it burn out and cannot be turned on again or until it does not check out the specs of the PQ tests of the manufacturer which ever comes first.
it will generally be a combination of light intensity, noise and drift.
this can range from 4000 to 8000 hours in my experience.

some vendors do not do those tests at all. if you need to do traces analyses or impurity checks then you will need to have some sort of procedure in order to check the noise of your instrument which is very much due to the lamp as it gets older. we have had a case where in a robustness part of the validation one instrument saw things that another one could not because the second one had an old lamp with low energy and high background noise.

if you are looking at peaks that have a strong signal, at least above 100 mAU/mV then i can't see where it will matter to you; you can simply wait untill the lamp dies

Slightly outside the topic:

The mirrors in the UV-detectors will go bad after approx 3-5 years. In that case the lamp energy will never be high - even with a brand new lamp.

On one of our Dionexsystems - the lamp energy was doubled when new mirrors were installed (using the same old lamp).

You did not mention which instrument you have. If it is an Agilent 1100 or 1200, use the Diagnosis features for the detector to measure the various spectral parameters. The results will tell you if you are within the specs set by Agilent.

The safest approach is to replace at regular intervals, even if the equipment is working properly. But this is almost never the cheapest approach. You can use the Early Maintenance Feedback (EMF) feature in the Agilent systems to keep track of usage, but as others have noted, this may not be helpful for lamps, since their lifetimes are not predictable.

The only other option would be to continue monitoring lamp performance on a more regular basis. Once a month, or even more often if necessary. If you see a steady decline of a short period, or if you see a further decrease of, say, 10 - 15%, then maybe it is time to replace the lamp now. If the decline is very slow, then maybe you have some more time, but I would agree with everyone else that you should buy a new lamp soon. The problem is that once the lamp really starts to fail, it will go quickly. So you can try catch it when it just starts to fail, but you do increase your risk of a complete failure.
Merlin K. L. Bicking, Ph.D.
ACCTA, Inc.

Hi

We made the experience that switching on/off the D2 Lamp often will have significant influence on the lifetime of the lamp....the less swithing the longer the lifetime....

But if your lamp reached the 1000hs its a good time to have one in stock....

Best regards
Chris
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