title: Establishment of reliable mass spectra and retention indices library: identification of fatty acids in human plasma without authentic standards.
abstract: Gas chromatography mass spectrometry (GC-MS) is routinely employed to analyze small molecules in various samples. The more challenge of GC-MS data processing is to identify the unknown compounds in samples. Mass spectra and retention indices library searching are commonly used method. However, the current libraries are often built through collecting data from different groups. To unknown compounds with similar mass spectra and retention indices (e.g. geometric (cis/trans) isomers), the inaccurate results sometime are supplied. In this case, the costly standard compounds have to be used in every analysis. In this report, taking identification of fatty acids as an example, we proposed a strategy of establishment of special database constructed by equivalent chain length (ECL) values in uniform conditions and mass spectra of fatty acid methyl esters (FAMEs). The mass spectral characteristics were firstly used to identify all expected straight saturated fatty acids, and subsequently calculate the ECL for fatty acids in the sample. Finally, the ECL values of fatty acids in the sample were compared with those of fatty acids in the customized database to identify their structures. The results showed that the method developed in this report could effectively identify similar unknown compounds (FAMEs in the human plasma) after validated by the authentic standards.
authors.affiliation: College of Chemistry and Chemical Engineering, Central South University, Changsha 410083, China.
authors.forename: Liangxiao
authors.initials: L
authors.lastname: Zhang
authors.forename: Binbin
authors.initials: B
authors.lastname: Tan
authors.forename: Maomao
authors.initials: M
authors.lastname: Zeng
authors.forename: Hongmei
authors.initials: H
authors.lastname: Lu
authors.forename: Yizeng
authors.initials: Y
authors.lastname: Liang
mesh_terms: D002138:Calibration; D016208:Databases, Factual; D005227:Fatty Acids / Q000097:blood*; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods; D006801:Humans; D012015:Reference Standards; D054852:Small Molecule Libraries
chemical_list: D005227:Fatty Acids; D054852:Small Molecule Libraries