Differentiation of Dimethyl Acetals Derived from Plasmalogens and Fatty Acid Methyl Esters from Edible Gastropods by Covalent Adduct Chemical Ionization Mass Spectrometry

Seafood provides important nutrients to our diets, particularly omega-3 polyunsaturated fatty acids (PUFAs). Compared with other common seafood, sea snails represent an underutilized resource that may be exploited to help meet global PUFA demands. However, sea snails exhibit complex fatty acid (FA) profiles, making an accurate and detailed characterization a considerable analytical challenge. By employing an advanced mass spectrometry (MS) technique, i.e., covalent adduct chemical ionization (CACI), we characterized the FA profiles of five commonly consumed sea snail species. A straightforward method was established to distinguish monounsaturated fatty acid methyl esters (FAMEs) from isobaric dimethyl acetals (DMA), verifiable by retention-time models. FAME double-bond positional isomers were further identified by CACI-MS/MS diagnostic ions. Sea snails are abundant in plasmalogens at 82–333 mg/100 g food and long-chain omega-3 PUFA up to 174 mg/100 g food. Therefore, sea snails, particularly saltwater varieties, show promise as mainstream seafood because of their high nutritional values.