Discussion Category:  Fluorescence Spectrophotometers

Low S/N ratio problem

I just bought a new Xe lamp for the fluorometer, but I can not reach the 200 to 1 ratio in the sens check, I did the coarse adjustment and the fine adjustment. 

The cuvette that I am using is brand new and the water is dd and it is filtered.

So I was wondering what could be the reason of not reaching that ratio, as well as the drift (too high)?

 

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Ana05
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chromatology

The first cause of not reaching the s/n is lamp alignment. Did you really observe the requested figure as per the HITACHI book? I find the fine adjustment does not help, just the coarse may be better.

Cleaning the excitation and emission lenses sometimes helps. I have seen a case where the s/n doubled after wiping but it was a severe case of smoke condensed on the lenses.   

It is much easier to do on the F2500 with more than double the s/n, I actually routinely get s/n of over 600 on an F2500.

Regards

 

Richard

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chromatology

Lamp alignment is very critical in this equipment, you need to get the  picture as described  in the book. Also to water has to be pure and your PMT must be in good shape, is this the original PMT? This means it is at least 20 years old, you should consider changing it, if all other steps were done without attaining 200 S/N ratio.

 

 Regards

Richard 

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