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Norman Chambers

Sudden sensitivity loss on QTRAP5500?

Chris Cook Bradley  Follow

Hi Jacqueline,
did you test the ESI voltage at the tip of your probe? In many cases sudden problems indicate a hardware problem. Check the power supply of the ESI-source. You can easily measure the voltage with a multimeter and a high voltage tester (http://www.amprobe.com/Amprobe/usen/Electrical-Testers/High-Voltage-Test---TIC-Tracer/AMP-HV231-10A.htm?PID=73249). Voltage readbacks of the software are often misleading because they are not correct. Some years ago we had a similar problem with the ESI probe of a Waters TOF system. The cause was a hair crack in the probe. Via this hair crack we had loss of voltage and therefore a decreased signal intensity.

If the ESI source is not the problem, you have to measure the voltages of your ion guide/filters. This is maybe a little bit tricky but with a good technical service manual you can check it. But be careful: Inside a mass spectrometer is an area of high voltage!

Another two reasons for massive sensitivity loss: clogged sample cone or a clogged splitter capillary

Regards Markus

P.S.: Related to this topic I've found some links:

https://www.chromforum.org/viewtopic.php?t=11650

https://sciex.com/support/knowledge-base-articles/lost-sensitivity-on-your-triple-quad-or-qtrap-you-may-need-to-optimize-your-cem-detector-parameter-1481142998734

https://www.researchgate.net/post/There_is_a_4000_QTRAP_intensity_decrease_What_is_the_reason





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Colin Little  Follow

Hi Jacqueline.
I agree with Markus, this is throuble could be clogged capillary. You could remove capillar for your probe and conect it in a hplc pump outside, aply 1,0 ml/min flow. If you don't see the spray, it´s this your problem.
I hope this help you.

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Chris Calone  Follow

Hi Jacqueline,
did you test the ESI voltage at the tip of your probe? In many cases sudden problems indicate a hardware problem. Check the power supply of the ESI-source. You can easily measure the voltage with a multimeter and a high voltage tester (http://www.amprobe.com/Amprobe/usen/Electrical-Testers/High-Voltage-Test---TIC-Tracer/AMP-HV231-10A.htm?PID=73249). Voltage readbacks of the software are often misleading because they are not correct. Some years ago we had a similar problem with the ESI probe of a Waters TOF system. The cause was a hair crack in the probe. Via this hair crack we had loss of voltage and therefore a decreased signal intensity.

If the ESI source is not the problem, you have to measure the voltages of your ion guide/filters. This is maybe a little bit tricky but with a good technical service manual you can check it. But be careful: Inside a mass spectrometer is an area of high voltage!

Another two reasons for massive sensitivity loss: clogged sample cone or a clogged splitter capillary

Regards Markus

P.S.: Related to this topic I've found some links:

https://www.chromforum.org/viewtopic.php?t=11650

https://sciex.com/support/knowledge-base-articles/lost-sensitivity-on-your-triple-quad-or-qtrap-you-may-need-to-optimize-your-cem-detector-parameter-1481142998734

https://www.researchgate.net/post/There_is_a_4000_QTRAP_intensity_decrease_What_is_the_reason





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Charles Foy  Follow

Many people experience sudden allergies, which are persistent sneezing, tearing, and nose without cold or cold. This is often due to the sensitivity of the body to an external effect that enters the body through the nose openings causing various allergic symptoms, Allergy symptoms disappear when the allergen disappears or leaves the area full of these effects.

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Carol Dixon  Follow

Hi Jacquline, did you already open a ticket at Sciex helpdesk ?
you can do it via our website www.sciex.com or contact Sciexnow via email: sciexnow@sciex.com

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Daniel Silvers  Follow

Hello everybody,
first of all, thanks to all for your answers.

At least I can exclude a clogged ESI capillary, as we observe a continuous and stable spray.
Measuring the Voltage wouldn't be that easy at the moment, as we simply don't have a high voltage tester and need to organize this one first. However, if the voltage of the probe isn't correct, wouldn't I then expect a constantly decreased intensity (and not a gradual decrease with samples over time)?

Of course I also contacted the Sciex helpdesk, but they only recommend to perform a drift test so far to check for contamination of Q0. This is what we already did and - as expceted - testing again also didn't suspect for contamination in this region.

Markus, thank you also for the links. The last two I already knew and we also checked for sensitivity loss of the detector. But accoridng to the test results, increase in detector voltage isn't necessary.

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