Cleaning 6135 LC/MS to remove trace levels of sodium: Methanesulfonic acid?

Hi All,

I have a nucleic acid based application that is incredibly sensitive to even trace (ppb) levels of sodium (and other metals) in the eluents.  We currently use formic or acetic acid to flush our LCs (normal or bioinert 1260) and MSs (6130 or 6135), in addition to using the more recent Agilent passivation procedures that use sodium phosphate for the LC (although we have amended it to ammonium phosphate).  Nevertheless reducing metal levels, especially sodium, to keep adducts in check is a constant battle and we have controls in place on the reagents and water we use, and also on our glassware wash and prep to try to keep this as low as possible.

I recently heard from, ahem, an alternative instrument manufacturer that they have had great success with using solutions of methanesulfonic acid to ion exchange cations (metals and alkylamines) off active surfaces in their LC/MS systems and that's helped them to get some excellent performance with respect to adducts.

Does anyone know if Agilent 1260s (normal and bioinert) and single quad MSs (6130 or 6135) are compatible with aqueous or water/MeCN methanesulfonic acid?  I guess somewhere between 0.1-0.3%v/v (15-50mM ish)?  

The sort of protocol I have in mind is to flush with 50/50 water/MeCN to remove eluents, followed by MsOH in either pure water or a water/MeCN mix.  Then a flush with 90/10 water/MeCN to remove MsOH residues and back into eluents (water/MeCN with alkylammonium acetate buffer).

Be grateful for any thoughts, especially on compatibility with methanesulfonic acid!

Was this helpful?