Unexpected outputs: m/z differences and isotope number

[Annatkachev]

Hello,

It seems that CAMERA sometimes produces unexpected outputs.

First, sometimes, the m/z difference are incorrect for the isotope number. I have mostly observed m/z larger than expected. Such as below (in this case 2.004 for M+2 and M+1 difference):

Second, sometimes, the isotope group contains multiple peaks for the same isotope. Strangely, they have different m/z values. Such as below (in this case, two M+2 peaks with 1.003 m/z difference)

Data was processed with XCMS online, for positive ionization mode. I attach a link to a collab notebook with the data and analysis.

https://colab.research.google.com/drive/1OciFt1M3lKrorlX7gnkwH4skJRwnHvFV?usp=sharing

Best regards.

[sneumann]

Hi, indeed that looks unexpected. The collab notebook only has the CSV and subsequent (very nice!) python analysis. I'd need the raw data plus a reproducible R script to check out where that is coming from.
Yours, Steffen