Unknown negative ions

[Chromgeek]

I am currently analysing chlorate on a single quad LCMS.

I am using negative ESI in SIM mode for m/z 83. I have a nice peak for chlorate however on analysing tap water something else appears (eluting at a different time). I am happy this isn't a channeling affect of the column as the standards run fine.

Does anyone know what other negative ions could be in tap water which have a m/z 83?

[sav]

Perchlorate?

isCID: 99m/z [M-H]- > 83m/z [M-16-H]-

Try scan mode and check 99m/z and isotope peaks of 83m/z.