Phosphoric acid reactivity with IP reagent

[mike_s]

Does anyone know if phosphoric acid can react with the ion pairing reagent Sodium 1-decanesulfonate? I am seeing several late-eluting system peaks that get bigger and more plentiful from one day to the next. 100% Milli-Q water injection, C18 column, Water/ACN are other components of mobile phase gradient. Any alternate ideas of what is happening or ways to prevent this would be appreciated. Thanks!

[tom jupille]

My first guess would be microbial metabolic products.