Chromatography Forum

Hi guys.

I'm using for a while now a Waters Acquity UPLC with Xevo TQD mass spectrometry to analize Mycotoxins.
The equipment was out of use for 2 month becouse of problems with the turbo pump on the mass spectrometer.
Now that the mass spec is fixed i was running some test and i noticed that the sensitivity was very low compared to analisys done in march.
The standards are new and even when injected pure in to the LC system they showed a very small peak.
The specialist from waters who fixed the mass spec did some infusions into the mass spec with standards to evaluate the sensitivity and to him it seemed normal.
Anyone with some ideia to what is happening?

Regards,

Hi guys.

I'm using for a while now a Waters Acquity UPLC with Xevo TQD mass spectrometry to analize Mycotoxins.
The equipment was out of use for 2 month becouse of problems with the turbo pump on the mass spectrometer.
Now that the mass spec is fixed i was running some test and i noticed that the sensitivity was very low compared to analisys done in march.
The standards are new and even when injected pure in to the LC system they showed a very small peak.
The specialist from waters who fixed the mass spec did some infusions into the mass spec with standards to evaluate the sensitivity and to him it seemed normal.
Anyone with some ideia to what is happening?

Regards,

If the standards are new I would get another set with a different lot number to compare. Could be the material itself if the sensitivity lower than what you've historically observed in combination with a smaller peak than you'd expect on LC. That would be the first thing I'd investigate.

How is the peak shape compared to March?
Do all mycotoxins have a lower sensitivity or just a couple of them?
Is there something else that you can inject and compare with earlier results, preferably on the same column?
Do you have another system to test if the mycotoxin standard you're injecting is OK?

Loss in sensibility

Yes, loss in sensibility can result in loss of sensitivity.

Hi guys.

I'm certain that's not the standard, because I injected an extracted sample that I'm sure to have mycotoxins, and no one spiked.
I even changed the mass spec ions to evaluate if anything changed, and even though no one appeared in my chromatogram.
Everything in the system is the same as we used couple month ago. Unless the mass spec whit is running on a new turbo pump.

Ps: column was changed and did not make difference.