Chromatography Forum

In my extraction method I use sodium sulfate and sodium acetate, It make problems for mass detection, what I have to do?I use ammunium formate in eluent.

Do you use Na2SO4/AcONa in extraction solvent (i.e. does it remain in the phase that you inject)? If so, due to a huge amount of Na+ ("huge" in MS sense, that is), I sincerely doubt you can do anything. Only to shift to some non-alkaline metal based additive. Using ammonium salts as additives may favor the formation of [M+NH4]+ adducts, but at least they fragment well.

If you are extracting the analyte *from* the sample with Na2SO4/AcONa as an additive, and some minute amounts of Na+ transfer to the extract, you may try desalting the extract afterwards (SPE, L/L extraction etc.). If working in positive mode, adding some acid (e.g. formic) might favor the formation of [M+H]+.

Dear Dr orcic,
Yes I use Na2SO4/AcONa. I change salts to MgSO4 and I find the peaks, Tank you.
You wrote ' If working in positive mode, adding some acid (e.g. formic) might favor the formation of [M+H]+' you means at which step formic acid adding will help me?

Apologies for being imprecise... you add HCOOH to your mobile phase. The optimal concentration should be determined by experiment, since pH influences both sensitivity (by favoring protonated/deprotonated species) and chromatography (if your compounds are weak acids/bases).

Dr orcic, Tank you for information.