GC-MS Fingerprinting of Fatty Acids of Freshwater Mollusc Lamellidens Marginalis using Different Columns, TR-WAX and TR-FAME.

Abstract

GC-MS is an important instrument in lipid profiling and lipid biomarker identification. The choice of columns and detectors is important in analysis and identification of the biomolecules. In the present study, GC-MS fingerprinting of fatty acids (FAs) in different tissues of freshwater mollusc Lamellidens marginalis was carried out in GC-MS with two different columns, TR-FAME and TR-WaxMS, to examine if choice of columns and detectors influence the identifications of the lipids. These sentinel organisms are used in aquatic pollution monitoring studies as they accumulate toxic environmental contaminants to levels well above those present in the surrounding environment thus providing information on the spatio-temporal pollution trends. FAs identified in different tissues include the saturated FAs palmitic acid (C16:0), margaric acid (C17:0), stearic acid (C18:0), monounsaturated FAs (MUFAs) oleic acid (C18:1), eicosenoic acid (C20:1) and polyunsaturated fatty acid (PUFAs) linoleic acid (C18:2). More numbers of FAs were detected in TR-FAME column than TR-WaxMS column. Several non-fatty acid compounds like butylated hydroxyl toluene (BHT) and dibutyl phthalate were also identified in the FAME (fatty acid methyl ester) preparation using NIST (MS) library. It was interesting to note that the FA peaks (6/14) were outnumbered by the non-fatty acid peaks (8/14). Such compounds could be taken as unidentified FAs unless powerful detectors like MS are available and can lead to erroneous inferences. The study showed that the choice of columns and detectors influenced the identification of the compounds. The information generated on fatty acid profiles of this bivalve could serve as baseline data for this species in searching for lipid biomarkers for aquatic pollution monitoring studies.