What is the maximum percent formic acid solution that can be used with an LC/MS? - WKB198101

ENVIRONMENT

• LC/MS
• Formic acid
• Analysis mobile phase vs. cleaning solution

ANSWER

The maximum percent formic acid recommended for normal LC/MS analysis is 0.1% best, 0.2% if needed.

ADDITIONAL INFORMATION

The LC/MS signal is a balance of mobile phase ions in solution competing with the analyte of interest. More acid or additives in the mobile phase can suppress the response of the analytes of interest.

More than 0.2% poses a detriment to column and system performance. Routine running at 3-5% formic acid in mobile phase will damage MS interface parts that are metal. Exposure to hot acid that is electrified by probe corrodes the metal parts more quickly than low levels of acid.

The cleaning solutions used with higher percentages of formic acid are NEVER flushed into the columns or the mass spectrometer. This is only for short-term cleaning and only for the LC system.