Direct ultrasound-assisted methylation of fatty acids in serum for free fatty acid determinations

A method for simultaneous determination of 16 free fatty acids (FFAs) in serum is described. The method involves conversion of FFAs to fatty acid methyl esters (FAMEs) using the heat of ultrasonic waves followed by gas chromatography and mass spectrometry (GC–MS) analysis. Optimum levels of the variables affecting the yield of FAMEs were investigated. The results indicate that the optimal levels are 55 °C, 60 W, 10% H2SO4/CH3OH, and 50 min. Recoveries ranged from 85.32% to 112.11%, with a detection limit ranging from 0.03 to 0.08 μg mL–1. The linearity, using the linear correlation coefficient, was higher than 0.9914.

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Comparison of gas chromatography-combustion-mass spectrometry and gas chromatography-flame ionization detector for the determination of fatty acid methyl esters in biodiesel without specific standards

Journal of Chromatography A ◽

10.1016/j.chroma.2016.06.033 ◽

2016 ◽

Vol 1457 ◽

pp. 134-143 ◽

Cited By ~ 8

Author(s):

Laura Alonso Sobrado ◽

Laura Freije-Carrelo ◽

Mariella Moldovan ◽

Jorge Ruiz Encinar ◽

J. Ignacio García Alonso

Keyword(s):

Mass Spectrometry ◽

Gas Chromatography ◽

Fatty Acid ◽

Fatty Acid Methyl Esters ◽

Methyl Esters ◽

Flame Ionization Detector ◽

Ionization Detector ◽

Flame Ionization ◽

Acid Methyl

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Composition Characterization of Fatty Acid Zinc Salts by Chromatographic and NMR Spectroscopic Analyses on Their Fatty Acid Methyl Esters

Journal of Analytical Methods in Chemistry ◽

10.1155/2019/7594767 ◽

2019 ◽

Vol 2019 ◽

pp. 1-11

Author(s):

Kwang Seo Park ◽

Yun Ju Kim ◽

Eun Kyung Choe

Keyword(s):

Mass Spectrometry ◽

Fatty Acids ◽

Gas Chromatography ◽

Fatty Acid ◽

Free Fatty Acids ◽

Fatty Acid Methyl Esters ◽

Methyl Esters ◽

Gas Chromatography Mass Spectrometry ◽

Acid Methyl ◽

Zinc Salts

To implement EU REACH- (Registration, Evaluation, and Authorization of Chemicals-) like chemical legislations in various countries of which the purpose is human and environment safety, the first step is substance identification followed by the hazard and risk assessments. Although both structural and composition identifications are required, the latter can more importantly result in the essential data to fill out the required substance information such as purity and concentrations of constituents, as well as impurities. With fatty acid zinc salts (FAZSs) as an exemplary industrial chemical of which chromatographic and nuclear magnetic resonance (NMR) analyses were impossible due to their insolubility in water and any organic solvents, the composition characterization was tried by preparing their fatty acid methyl esters (FAMEs) using the conc. HCl/methanol/toluene method. This acid-catalyzed methyl esterification was optimized with zinc stearate as a surrogate substance. Gas chromatography-mass spectrometry (GC-MS) and NMR analyses on methyl-esterified products revealed that the optimum conditions were at 90°C for 10 min or 45°C for 30 min with two equivalent HCl as well as at 45°C for 10 min with five equivalent HCl. Almost all zinc stearates were converted into the corresponding fatty acids with 97–99% conversion rates. Free fatty acids (FFAs) were detected in extracted ion chromatograms of pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) in the methyl-esterified products with incomplete conversions of 73∼79%. The optimized conc. HCl/methanol/toluene method of direct one-step reaction from FAZSs was compared with the two-step NaOH saponification/BF3-methanol method after acidic hydrolysis of FAZSs. The mechanism of fatty acid zinc salts into free fatty acids and fatty acid methyl esters was suggested with the evidence of the formation of Zn(OH)2.

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Evaluation of Non-polar Composition in Plumbago Zeylanica Leaves by Gas Chromatography and Mass Spectrometry

Folia Medica ◽

10.3897/folmed.62.e47647 ◽

2020 ◽

Vol 62 (2) ◽

pp. 308-313

Author(s):

Jayesh Dhalani ◽

Gaurang Dubal ◽

Chirag Rathod ◽

Pankaj Nariya

Keyword(s):

Mass Spectrometry ◽

Fatty Acids ◽

Gas Chromatography ◽

Fatty Acid ◽

Fatty Acid Methyl Esters ◽

Methyl Esters ◽

Chemical Compounds ◽

Mass Spectrometry Analysis ◽

Plumbago Zeylanica ◽

Acid Methyl

Background:Plumbago zeylanica plant belongs to Plumbaginaceae. The plant is reported for many pharmacological activities. Aim: The objective of the study was to identify fatty acids and non-polar chemical compounds in Plumbago zeylanica leaves. Materials and methods: Petroleum ether extract was prepared using soxhlet apparatus. Saponifiable and unsaponifiable matter was separated with saponification process. To identify fatty acids in saponifiable matter further esterification was performed. Gas chromatography and mass spectrometry analysis was performed of both saponifiable and unsaponifiable fractions. All the fatty acid methyl esters and non-polar chemical compounds were identified using NIST library data. Results: A total of 14 compounds were identified with comparison of NIST data. From that, 8 fatty acid methyl esters and 6 non-polar chemical compounds were identified. Here we have analyzed fatty acids and non-polar chemical compounds by the same GC-MS method. Conclusions: The present analysis showed that Plumbago Zeylanica leaves contain 8 fatty acids and 6 non-polar chemical compounds. Principal determination of the research was development of efficient method to identify non-polar compound from plant by single injection using chromatographic technique.

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