Perfluorinated acid alternatives to trifluoroacetic acid for reversed-phase high-performance liquid chromatography.
Over the past decade trifluoroacetic acid (TFA) has become the ion-pairing agent (IPA) of choice for reversed-phase high-performance liquid chromatography (RP-HPLC) of peptides and proteins. Reagent grade TFA is highly pure, water soluble, transparent at 220 nm and readily volatile. A drawback of this universal appeal is that several alternative perfluorinated carboxylic acids tend to be overlooked when TFA does not work in a particular separation. Examples are given comparing TFA selectivity with those of pentafluoropropionic acid, heptafluorobutyric acid, perfluoropentanoic acid, perfluorohexanoic acid and perfluoroheptanoic acid. We have found that increasing the IPA n-alkyl chain length can resolve sample components that otherwise co-elute in the void volume of TFA-based RP-HPLC. Examples are given for the resolution of an oligoglycine series and enhanced selectivity for a bovine hypothalamic extract.
Biochemistry Dept., Pharmacia and Upjohn Inc., Kalamazoo, MI 49001, USA.
J D
JD
Pearson
M C
MC
McCroskey
D000818:Animals; D002417:Cattle; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D005463:Fluoroacetates / Q000737:chemistry*; D007031:Hypothalamus / Q000737:chemistry; D007202:Indicators and Reagents; D009842:Oligopeptides / Q000032:analysis; D012015:Reference Standards; D013056:Spectrophotometry, Ultraviolet; D014269:Trifluoroacetic Acid / Q000737:chemistry*
D005463:Fluoroacetates; D007202:Indicators and Reagents; D009842:Oligopeptides; D014269:Trifluoroacetic Acid