| Author | Message | ||
     Howard Mark (hlmark) Senior Member Username: hlmark Post Number: 127 Registered: 9-2001 |
Raph - as David said, it sounds like you're good to go. Personally, however, I don't like mysteries. I think you should still check with your instrument manuf to verify that the amount of decrease you experienced is within the realm of "normal". \o/ /_\ | ||
| raphael beauget (raph) New member Username: raph Post Number: 3 Registered: 4-2007 |
Thanks for your help ! Indeed, there are daily tests : Throughpout Test and Noise test ! The noise of spectrum has not changed with the new lamp, however the throughtpout check, who is the ratio between the background and the reference, has increase. As the energy is low but accurate, I have take a new reference spectrum and the results of System Suitability have corrects. Sincerely, Raphael | ||
| Howard Mark (hlmark) Senior Member Username: hlmark Post Number: 126 Registered: 9-2001 |
Raph - hard to say. The amount of energy decrease may be within the manufacturer's specifications for lamp energy. Or the original lamp may have been unusually "hot". Or the detector may be sufficiently linear and the referencing so accurate that there's very little change in the absorbance, due to the difference in lamp energy. Or the difference may show up in other places. If you've run noise and other QC tests on the instrument on a routine basis (as many manufacturers recommend and some SOPs require) then running the usual set of diagnostic tests will reveal if any of those test parameters have changed. If the lamp energy is low, then I would expect the S/N to have decreased. Then the question becomes: is it still within specifications? If not, and you can't fix it, then you'll need a field service visit. The bottom line, though, is that there's only one source of detailed information regarding the way the instrument is supposed to work, and that's the manufacturer. Sooner or later you're going to have to contact them, so you might as well do it right away and get definitive answers to these questions. \o/ /_\ | ||
| David W. Hopkins (dhopkins) Senior Member Username: dhopkins Post Number: 115 Registered: 10-2002 |
Hi Raphael, The good news is that your applications of identification of excipients still are functioning. So far, you have no problem, and it is probable that you will continue without problems. The lower energy may mean that you have to operate at a higher gain, and that may increase the noise level of the spectra somewhat. Have you tested the noise following your maintenance? However, the way the reference scan is ratioed to the sample scan should compensate for any changes in the output of the lamp. Therefore I would not expect any problems with your classification or quantitative models. Any increases in noise will be ignored by your models, hopefully. Best wishes, Dave | ||
| raphael beauget (raph) New member Username: raph Post Number: 2 Registered: 4-2007 |
Thanks for your answer ! The old lamp don't work and while changing the lamp, I don't think I have hit, move or jostle something. After the maintenance the instrument have been aligned by the computer. I've tried to use the NIRS for identification of excipients and all excipients have been correctly identified ! I thought low energy have more consequences on spectrum and so a bad identification particularly for the models generate with PCA. What do you think about it ? | ||
| Howard Mark (hlmark) Senior Member Username: hlmark Post Number: 125 Registered: 9-2001 |
Raph - if the old lamp still works, try putting it back in and see if the energy returns to it's original level. If it does, then it may mean that the the new lamp is defective. Make sure that all electrical connections are tight and making good contact. It's also possible that the new lamp was put in without being properly aligned. If the instrument instructions include an alignment or adjustment procedure, then you should follow those instructions, to see if that doesn't improve the performance. Otherwise, something else may have changed in the instrument. Are you sure you didn't hit, move or jostle some other part while changing the lamp (especially any lenses or mirrors that might be near the lamp)? In any case, you should ask somebody at the manufacturer for recommendations about user troubleshooting. \o/ /_\ | ||
| raphael beauget (raph) New member Username: raph Post Number: 1 Registered: 4-2007 |
Hi everybody ! Currently, I'm in work-placement in industry. I work with NIRS and I'm a novice ! I have replace the source yesterday and after the energy is very lower than before the maintenance. However, I have changed the dessicant and realized the purge of the system. Do you have any idea as concerned the origin of the problem ! Sorry for my bad english, Thanks Raphael |