[Telamond]

So during one of the experiments we were doing, we used two IS, which I found pretty weird.
Is there any use for two IS?

[wpenrose]

You'd have to give more info on the experiment. Sometimes, one internal standard is used to determine yield, the other to calibrate a mass spectrum or a retention time in a gas chromatographic analysis.
eg
http://www.imss.nl/imsc17/abstracts/abstract3fe0.html?ID=411

DB

[JGK]

How many Analytes were you quantifying?

If there were 2 analytes with differing properties, a separate IS may be used for each of the analytes.

[Telamond]

Yes, we had several analytes, it was the metabolites of limonene.
The retention time for them separated was maybe >6 mins as well, so I'd guess that two IS would be needed. IS1 eluted out first and IS2 eluted out last.
What I learned from a lab assistent was that ideally, one would have one IS per analyte, but that seemed a bit overkill as well.

Odd thing was that they wrote in the instructions to only use IS2 for quantification...

Thank you for the replies, both of you.