ELSD Noise

<p>Hello,</p><p></p><p>We have Acquity ELSD in the system and the baseline is noisy. The fluctuation in normal cases are 2-5 LSU but sometimes goes up to 20. How can we reduce and fix the baseline?</p><p>The column is HILIC Amide, the eluent is 70/30 AcN/Water with 0.2% TEA.</p><p></p><p>Thanks,</p><p>JT </p>


  • My experience (and keep in mind that I've only had the ELS detector for about a month) is that the baseline is just the jumpy. ELS are not the best detectors, but do well for what you're looking on (I'm thinking you're testing sugars or something like that), especially if you look for them in a higher concentration then you would on like a PDA or something like that. I know that's not much help, but that's been my experience with the ELSD.

  • Depending on flow and temperature it is possible that there may be saturation of the drift tube or particulate contamination which could cause this high baseline noise. If you have not done so I would start by shutting off the mobile phase flow and increasing the drift tube temperature to 100 degrees C for at least an hour or two. Then return to the normal temperature, but do not start the flow. With the gas on you should monitor the baseline and if it has improved then you can start the mobile phase again. If it has not improved then I would suggest removing the column and start flowing 100 % water through the detector with the drift tube at 100 degrees C. Then you should run a linear gradient over 1 hour to 100 % methanol and back to water. In the past this I have seen this process clean some drift tubes that just steaming with water would not.

  • What is your peakwidth en howmay samplepoints/second do you take. We had the same problem and after optimizing the gas and temp setting we really solved it by simply reducing the samplepoints/second. For UV we normally use around 20 - 40 which is in most cases more than needed but gives no problem with UV. For ELSD we now use 5 - 10. With the 20 - 40 we often saw spikes and "hairy" peaks. For a good integration you need around 15 - 25 points on a peak.

  • lizh


    I just wondered, as I was checking up on the threads how this method is coming. if you omitted the TEA, if possible, what happens?