Abstract
Formic acid is often used for pH adjustment in RP–LC mobile phases. However, under certain circumstances, formic acid can also behave as an organic co-solvent. This study illustrates two scenarios when the effects of formic acid as co-solvent will be most noticeable. One scenario is for water-rich mobile phases, in which the addition of formic acid will cause small but significant decreases in retention of neutral analytes. The other scenario is in gradient chromatography. It is demonstrated that, during acetonitrile solvent gradients, desorption of formic acid from the column stationary phase occurs simultaneously, potentially causing a spike in UV detector baselines at the beginning of gradients. A pK a value of formic acid obtained in 50% acetonitrile is also reported and the impact of organic solvent on the dissociation of formic acid is discussed.
Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
