LAUSR

Abstract Naphthenic acids are cycloaliphatic carboxylic acids that are naturally-occurring constituents of petroleum. Analytical mass spectrometric methods aimed at carboxylic acids tend to involve deprotonation to generate carboxylate anions, but also produce detectable ions of every acidic component of the mixture. A charged tag carbodiimide is able to facilitate detection of model naphthenic acids as well as low levels of naphthenic acids in petroleum fractions via tandem electrospray ionization mass spectrometry. This approach exhibits greater selectivity than deprotonation, and a picture of the acidic components of a petroleum fraction emerges after a quick derivatization step and without the use of chromatographic separation. The method may prove useful in the context of characterizing the naphthenic acid components of complicated matrices.