Mass spectrometric study on the source of error in quantification of fatty acids

Abstract

Identification and quantification of fatty acids are important in fields of lipidomics and metabolomics. Although exogenous fatty acid contaminants, which leads to inaccurate quantification, have been neglected in lipidome analyses, unexpected contamination can be occurred from plasticware and glassware during the sample preparation. Therefore, quantitative measurement of the contaminants is necessary for reducing an error associated with accurate determination of the amount of endogenous fatty acids in biological samples. Fatty acid contaminants were investigated with respect to different types of sample containing tubes, extraction solvents, and sample preparation. The contaminants were analyzed by high-performance liquid chromatography electrospray ionization quadrupole time-of-flight mass spectrometry in technical triplicate. The target molecules were palmitic acid and stearic acid that account for the largest portion of the contaminants. As a result, among sample containing tubes, glassware washed using methanol revealed the minimum contamination of fatty acids. By evaluation of different types of extraction solvents, chloroform showed the least contamination. Also, the amount of contaminants generated in the sonication step was about 57 times higher than that in the pipetting step, which is expected to be the most abundant source of the contamination.