Heats of vaporization of esters by the gas chromatography–calorimetry method

1980 ◽  
Vol 58 (24) ◽  
pp. 2796-2799 ◽  
Author(s):  
Richard Fuchs ◽  
L. Alan Peacock
Keyword(s):  
Fatty Acids ◽  
Gas Chromatography ◽  
Fatty Acid Methyl Esters ◽  
Butyl Acetate ◽  
Recent Literature ◽  
Methyl Esters ◽  
Heat Of Solution ◽  
Acid Methyl ◽  
Glyceryl Triacetate ◽  
Heats Of Vaporization

A recently developed gc–calorimetry procedure involving a combination of gas chromatography and heat of solution measurements has been used to measure heats of vaporization of 17 esters, including methyl 2,2-dimethylpropanoate, butyl acetate, glyceryl triacetate, diethyl phthalate, methyl 9-octadecenoate, and 12 methyl esters of C3- to C15-fatty acids. Comparison with measurements of ΔHv reported in the literature indicates that the gc–calorimetry method often has smaller uncertainties in measurements (0.25 to 1.00 kJ mol−1) and more consistent methylene increments for the series of fatty acid methyl esters. Two of the experimental ΔHv measurements which differ appreciably from recent literature values have been verified by vaporization calorimetry.

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

2010 ◽  
Vol 88 (9) ◽  
pp. 898-905 ◽  
Author(s):  
Liyan Liu ◽  
Ying Li ◽  
Rennan Feng ◽  
Changhao Sun
Keyword(s):  
Mass Spectrometry ◽  
Fatty Acids ◽  
Gas Chromatography ◽  
Fatty Acid ◽  
Fatty Acid Methyl Esters ◽  
Methyl Esters ◽  
Ultrasonic Waves ◽  
Acid Methyl ◽  
Ultrasound Assisted

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.

A comparison of structural–functional equation models to identify fatty acids on three common gas chromatography columns

2018 ◽  
Vol 10 (15) ◽  
pp. 1747-1759 ◽  
Author(s):  
A. T. L. Wotherspoon ◽  
K. L. Reeves ◽  
J. Crawford
Keyword(s):  
Fatty Acids ◽  
Functional Equation ◽  
Gas Chromatography ◽  
Fatty Acid Methyl Esters ◽  
Functional Relationship ◽  
Structural Information ◽  
Methyl Esters ◽  
Acid Methyl ◽  
Chromatography Columns ◽  
Gas Chromatography Columns

Reported herein is a series of new structural–functional relationship equations which provide relevant structural information of unknown fatty acid methyl esters (double-bonds, chain-length, and omega-bond position) based upon temperature induced shifts in equivalent chain length's (ECLs).

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

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.

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

Folia Medica ◽  
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.

Tutorial for the Characterization of Fatty Acid Methyl Esters by Gas Chromatography with Highly Polar Capillary Columns

2020 ◽  
Author(s):  
Pierluigi Delmonte ◽  
Andrea Milani ◽  
John K G Kramer
Keyword(s):  
Fatty Acids ◽  
Gas Chromatography ◽  
Fatty Acid ◽  
Vegetable Oils ◽  
Fatty Acid Methyl Esters ◽  
Methyl Esters ◽  
Capillary Columns ◽  
Marine Oils ◽  
Optimal Separation ◽  
Acid Methyl

Abstract The fatty acid composition of fats and oils is commonly determined by gas chromatography after preparing fatty acid methyl esters (FAME). Capillary columns coated with polyethylene glycol emerged as the preferred separation tool for the quantification of the polyunsaturated fatty acids contained primarily in marine oils. However, their selectivity is inadequate for measuring the trans fatty acids (TFA) contained in refined vegetable oils, dairy fats, and marine oils. Highly polar 100% poly(biscyanopropyl siloxane) capillary columns provide the necessary selectivity, but small differences in the phase polarity caused by column age, conditioning, or manufacturing variations affect the reproducibility of their separations of these complex samples. In this study, a simple procedure is described to compensate for small variations in column selectivity by adjusting the elution temperature. The balance between the dipole-induced dipole interactions and dispersive interactions was determined by measuring selectivity factors [SF(i)] corresponding to the elution of an unsaturated FAME such as 18:3n-3 relative to two saturated FAME such as 20:0 and 22:0. Knowing the SF(i) provided by the installed capillary column at a given elution temperature, and the SF(i) of the target separation, we propose a simple calculation to determine the necessary elution temperature adjustment to achieve (or restore) the desired separation. After determining the SF(i) which provides the optimal separation of TFA, the novel methodology was applied to the separation of refined vegetable oils, butter fats, and marine oils.

scholarly journals Application of the “fast” gas chromatography method for regular analysis of fatty acids in milk and dairy products

2020 ◽  
Vol 82 (1) ◽  
pp. 164-168
Author(s):  
N. A. Zhizhin
Keyword(s):  
Fatty Acids ◽  
Gas Chromatography ◽  
Fatty Acid Composition ◽  
Fatty Acid ◽  
Stationary Phase ◽  
Acid Composition ◽  
Fatty Acid Methyl Esters ◽  
Methyl Esters ◽  
Analysis Time ◽  
Acid Methyl

The paper presents one of the approaches for identifying fatty acids using gas chromatography, which significantly reduces the analysis time, and is equally effective when compared with the traditional method of studying the fatty acid composition. The determination of the composition of fatty acids today is a guarantee of quality in identifying various conformations and modifications of milk fat, the bioactive properties of individual acids of the omega-3 and omega-6 families, etc. Moreover, this method is time-consuming, therefore, the goal of this work is to optimize the parameters of this methodology for quick and regular analysis of fatty acid composition in laboratories and dairy enterprises. The analysis of the fatty acid composition was carried out using two columns with different stationary phases. A comparative evaluation of the analytical characteristics was carried out on two capillary chromatographic columns: SP-2560 100 ? 0.25 mm ID, 0.2 ?m with a stationary phase FFAP (traditional) and a gas chromatographic column BPX-70: stationary phase 70% cyanopropylphenyl dimethylpolysiloxane, 10 m ? 0.1 m ? 0.20 ?m. Detection was carried out using a flame ionization detector. A mixture of Supelco® 37 FAME Mix fatty acid methyl esters and Sigma-Aldrich methyl decanoate analytical standard was used as the standard. For data processing, the NetChrom software was used, the composition of fatty acid methyl esters was calculated by the internal normalization method. The analysis time of the first column was 49.07 minutes, for the second 8.44, respectively. The use of a stationary phase column of cyanopropylphenyl dimethylpolysiloxane significantly reduced the analysis time when eluting a complex composition of fatty acids. The studies were carried out using modern analytical techniques and arbitration methods of analysis in the laboratory of technochemical control of the All-Russian Scientific Research Institute of the Dairy Industry. This adapted analysis method will be of interest to specialists in the field of laboratory research and processing enterprises.

scholarly journals Upon the opportunity to apply ART2 Neural Network for clusterization of biodiesel fuels

2016 ◽  
Vol 3 (1) ◽  
pp. 19-25
Author(s):  
T. Petkov ◽  
Z. Mustafa ◽  
S. Sotirov ◽  
R. Milina ◽  
M. Moskovkina
Keyword(s):  
Neural Network ◽  
Mass Spectrometry ◽  
Artificial Neural Network ◽  
Gas Chromatography ◽  
Fatty Acid Methyl Esters ◽  
Methyl Esters ◽  
Gas Chromatography Mass Spectrometry ◽  
Acid Methyl ◽  
Chemometric Approach ◽  
Biodiesel Fuels

Abstract A chemometric approach using artificial neural network for clusterization of biodiesels was developed. It is based on artificial ART2 neural network. Gas chromatography (GC) and Gas Chromatography - mass spectrometry (GC-MS) were used for quantitative and qualitative analysis of biodiesels, produced from different feedstocks, and FAME (fatty acid methyl esters) profiles were determined. Totally 96 analytical results for 7 different classes of biofuel plants: sunflower, rapeseed, corn, soybean, palm, peanut, “unknown” were used as objects. The analysis of biodiesels showed the content of five major FAME (C16:0, C18:0, C18:1, C18:2, C18:3) and those components were used like inputs in the model. After training with 6 samples, for which the origin was known, ANN was verified and tested with ninety “unknown” samples. The present research demonstrated the successful application of neural network for recognition of biodiesels according to their feedstock which give information upon their properties and handling.

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