isotopes - negative ion mode

August 15, 2011, 12:39:20 PM

Hello,

In the forum for XCMS-online, there is some discussion about the notation used to indicate isotopes in negative ion mode. My understanding is that the output has been changed to have negative isotopes be marked as [M+1]-

However, I am using R/XCMS/CAMERA (not the online version) to identify isotopes in my samples which have been run in negative ion mode. The resulting list presents data such as: [1][M]+ ... which seems to be the 12C version of a compound that is singly-charged. Would it also be possible to change CAMERA to match the output of xcms online (which is far more intuitive for negative ion mode)?

Thanks,
Krista

Re: isotopes - negative ion mode

Reply #1 – August 17, 2011, 08:20:30 AM

Hi Krista,

the annotation of isotopes was also changed in CAMERA in v1.9.4. It is now the same as xcms online.
You need to update to the lastest version from the devel repository.
http://bioconductor.org/packages/2.9/bi ... AMERA.html

Cheers,
Carsten

Re: isotopes - negative ion mode

Reply #2 – August 17, 2011, 08:38:34 AM

Thanks!
I thought I had the latest version.