<p><span>Hello People,</span></p><p></p><p><span>I look after the UPLC in my lab.</span></p><p></p><p><span>1) UPLC detector lamp has passed the 2000hrs.</span></p><p></p><p><span>Will that affect the performance?</span></p><p></p><p><span>Do i need to change the lamp?</span></p><p></p><p><span>How many maximum hours can you get out of detector lamp?</span></p><p></p><p><span>2) In my training I have been asked to take the fittings off from the detector inlet once you finish the analysis and then switch the lamp off.</span></p><p></p><p><span>What if you don't follow above practive?</span></p><p></p><p><span>Hope to hear the answers from you soon.</span></p><p></p><p><span>Many thanks in advance </span></p><p><span>Pankaj shah</span></p>


  • lizh


    There are no "right" answers on this one! Is your detector a PDA or a TUV? It like asking how long a column will last!

    This is a good question and I hope my service colleagues will correct me. We warranty Waters lamps for 1,000 hours so after that noise will degrade. However, I would not chnage a lamp until your noise and signal to noise is affecting your results.

    If your mobile phase is transparent (ie does not have lost of modifiers such as TFA in it) and you are working in the area where the (210 to 350nm) where the lamp spectrum is good you can keep your lamp. All of Waters UV detectors UPLC and HPLC have mechanisms that minimize lamp degradation over time, until there comes a point that the s/w can no longer work so you will see a noisy baseline.

    Effectively, for assays when S/N is less important the peaks of interest have concentrations that are high all will be well. For impurity studies where S/N is critical the lamp will need to be replaced more often.

    So how long can you go? The answers is simply - it depends on your lab.

    In the Console software you can monitor the number of hours on your lamp (you do have to reset when you change the lamp so be careful that this was done), and you can reference energy and I would do that for your present lamp. I would then measure the noise on my baseline ( it can be done automatically in Empower) where no peaks elute and choose thes ame wavelength to do this. 230 nm is most often chosen as this is where the lamp energy is highest.

    Then you will be monitoring 3 factors:

    (1) The lamp hours

    (2) The raw energy (unaffected by mobile phase)

    (3) The actual noise - this is affected by the mobile phase and the system

    This will give you an idea about when you should think about replacing when you start to see noise go up.

    Once you have done this experiment over this lamp's lifetime you can just apply this knowledge to all lamps going forward. I would do separately for a PDA vs. a TUV as the work that they do can differ and the so the S/N performance requirements will differ too,

    Hope that this helps. let me know if need more specifcs on the Console and how to calcualte noise (actually there is a nice discussion thread about that too).