Convenient preparation of picolinyl derivatives from fatty acid esters

Abstract

It is essential to have simple rapid methods for the determination of fatty acid structures. Traditionally, fatty acids are analysed by gas chromatography using their methyl ester derivatives (FAME). However, their corresponding mass spectra exhibit molecular ions but are usually devoid of ions indicative of structural features and, notably, the position of double bounds on the aliphatic chains [1]. In the most useful approach to structure determination, the carboxyl group is derivatised with a reagent containing a nitrogen atom. Recently, a convenient method for preparing picolinyl esters from intact lipids has been published [2]. However, some problems occurred in our laboratory when this method was used, leading to some modifications and optimisation. Thus, hexane and water have been added while sodium bicarbonate has been removed in order to lower contamination. Temperature and length of the reaction have then been optimised in order to get 100% derivatisation for different kinds of lipids (45 7C and 45 min for FAME). Finally, a comparison of the response factors has confirmed the better sensitivity of the picolinyl derivative against FAME (five times more).

Fatty acids and stable isotopes as indicators of early-life feeding and potential maternal resource dependency in the bull shark Carcharhinus leucas

“…Selected samples were analyzed with a Restek FAMEWAX column (Crossbond ® polyethylene glycol stationary phase, 30 m length, 0.25 mm internal diameter, 0.25 µm film thickness), with an oven program of 6°C min −1 from 100 to 230°C, followed by a 10 min hold, to confirm structural assignment because coelutions of polyunsaturated fatty acids were minimal with the FAMEWAX column. Following quantification of the FAMEs, double bond positions in predominant unsaturated fatty acids were further confirmed through analysis of picolinyl esters following the method of Dubois et al (2006).…”

Rapid Preparation of Fluorescent 9‐Anthrylmethyl Esters for Fatty Acid Analysis of Small Amount of Triacylglycerols

“…The present method is based on the methodology developed for rapid preparation of fatty acid picolinyl esters [9,11], C 2 -C 4 n-alkyl esters and 2-methoxyethyl esters [10]. However, some improvements were also required.…”

“…Mild reaction conditions allowed complete derivatization, i.e., picolinyl ester from TAG and phospholipids, 2 min at room temperature [9]; and 2-methoxyethyl and n-alkyl esters from TAG, 15 min at 40°C [10]. Dubois et al [11] reported complete derivatization of methyl esters to picolinyl esters in 45 min at 45°C. Because 9-anthrylmethyl esters are also esters of a primary alcohol, this methodology is applicable to their synthesis.…”

LC/ESI-MS/MS detection of FAs by charge reversal derivatization with more than four orders of magnitude improvement in sensitivity

“…An alternative strategy for enhanced sensitivity is to improve the ionization effi ciency of FAs via specifi c derivatization with reagents that introduce either readily chargeable or fi xed charge groups such as tertiary or quaternary amines, respectively. Many derivatives of this nature have been reported including: pyrolidides (19)(20)(21), picolinyl esters ( 22,23 ), dimethyloxazolines (24)(25)(26)(27)(28), benzofurazans ( 29 ), pyridiniums ( 30 ), and cholines ( 31 ). The advantages of these derivatives include improved MS sensitivity and reproducible chromatography profi les.…”