HILIC - BEH Amide storage soln.
I have an assay using BEH Amide (HILIC) column and fairly clean samples (salines that have been SPE'd....no proteins). Gradient elution using mobile phase composed of various %'s of [ACN+0.1%FA] and [MilliQ+0.1%FA]. The column gets fairly constant use (at least 3 times per week). For my shutdown method I just wash with 50:50 of MPA:MPB, so the point is that the column is ALWAYS under 0.1%FA conditions, even during "storage". Does anyone think this may be a problem? My RT's are rock solid day in and day out, but I am seeing some *wild* fluctuations in peak area day-to-day and am wondering if this is related in any way to storage conditions. My thoughts were to keep the stationary phase under one consistent pH condition at all times. But am I missing something?