Novel method for quantification of individual free fatty acids in milk using an in-solution derivatisation approach and gas chromatography-mass spectrometry

Abstract

a b s t r a c tAn ethyl chloroformate free fatty acid (ECF-FFA) method was developed for quantification of free fatty acids (FFAs) in milk. The method is based on gas chromatography mass spectrometry with ECF insolution derivatisation and was optimised for the comprehensive analysis of FFAs (C 4 eC 18:3 ) in bovine milk. Good estimations of all FFAs, including the most water-soluble short chain free fatty acids were achieved by using in-solution derivatisation, which can be ascribed to the fact that an extraction of the milk samples with an organic phase is avoided. FFA standard solutions and raw milk samples were used to validate the proposed method. Correlation coefficients of >0.999 were obtained for all of the standards. Both the repeatability and the within three days stability of the analytical method were high (RSD <4%) for the quantified FFAs in milk. Method recovery of spiked milk samples with three different levels of FFAs was in the range 94e103%.

Free fatty acids quantification in dairy products

“…A new approach for the quantification of individual FFAs in milk was described by Amer et al . (). They reported the use of ethyl chloroformate to form ethyl esters of milk FFAs in‐solution where pyridine was added as a catalyst.…”

Direct Derivatization vs Aqueous Extraction Methods of Fecal Free Fatty Acids for GC–MS Analysis

“…In the present study, the FFA were derivatized, both directly and after aqueous extraction, into their ethyl esters by the ECF derivatization protocol in the presence of ethanol and with pyridine as a catalyst. The two-step alkyl chloroformate derivatization was selected in this study because it is an aqueous derivatization reaction that can be used both after an aqueous extraction [7] and as direct in-solution derivatization [13,14,16,17]. ECF with ethanol derivatization had the highest peak intensity of derivatives, separation capability, and derivatization purity and was selected as the optimal reaction reagents among other alkyl chloroformate and alcoholic solvents used in the study by Gao et al [11].…”

“…The derivatization was performed according to Qiu et al [13] with minor changes according to the ECF-FFA method recently published by Amer et al [14]. A total of 100 µL of each fatty acid standards solution were added to glass tubes (10 mL), each with a screw top, and mixed with 100 µL of the first fatty acid internal standards solution (see previous section), 440 mL of anhydrous ethanol, 100 µL of pyridine, and 500 µL of deionized (18.2 MU) filtered water (0.22 mm).…”

A gas chromatographic study of the conjugated linoleic acid and other fatty acid contents of raw milk samples from Galicia (NW Spain)

“…; Amer et al . ; González‐Arrojo et al . ) and silver‐ion high‐performance liquid chromatography (Ag + ‐HPLC) (Sehat et al .…”