What is CROSS TALK?

[thohry]

Hi all,

Could anyone explain to me the term "Cross Talk" in LC/MS. I read in the manual of Agilent 6410 QQQ and it says the new collision cell reduces cross talk. Thanks in advance.

[oscarBAL]

Hello Thohry; I don't know how to explain my self in inglish properly; but inmagine you are working MRM multi target components using UPLC for example... your first Q is working too fast betwen very short Dwell timas and interchanel delays; then if first Q and the collision cell are not very well sincronized (or if you collision cell is not able to handle ions properly) you colud have accomulation of ions form diferents MRM that could generatd equals daugther.
you can see a nice definition on these web site:
https://www.waters.com/webassets/cms/li ... 0917en.pdf
http://www.thermo.com/eThermo/CMA/PDFs/ ... _26364.pdf

I think this is one of the resons why Waters have developed the Twave and scan wave, for the colission Cell and Agilent use Octapoles, and ABI use curved cells.

Please somebody correctme if I am wrong.

Regards.

Oscar

[Loekie]

Crosstalk is the effect that you get a false positive signal on a next transition from a different precursor to the same product ion. It is easy to test. have two transitions in the list with different precursor ions and the same product ions. Make the second transition a dummy and impossible transition. inject only one compound in high concentration only one transition should give a signal.

If X-talk occurs it is more pronounced with the shorter dwell times. These days with the current instruments X-talk should not be there anymore. If you have X-Talk your instrument is not beahing right.

X-Talk is unwanted and can lead to false positives leading to all kinds of problems.

Loekie