title: Direct Derivatization vs Aqueous Extraction Methods of Fecal Free Fatty Acids for GC-MS Analysis.
abstract: A comprehensive and accurate determination of free fatty acids (FFA) is required for fecal metabolomic investigations. The present study compares three aqueous extraction methods (1) ULTRA-TURRAX(®), (2) whirl mixing and (3) basic ULTRA-TURRAX extraction of fecal FFA with a direct derivatization approach using ethyl chloroformate as the derivatization reagent before determination by gas chromatography-mass spectrometry. The direct derivatization method resulted in significantly higher estimations (P < 0.01) of short- and long-chain fatty acids than was the case when applying the aqueous extraction methods using ULTRA-TURRAX, whirl mixing, or basic ULTRA-TURRAX extraction before the derivatization step. Thus, avoiding an aqueous extraction before derivatization reduces the loss of volatile short-chain FFA and the less water-soluble long-chain FFA.
authors.affiliation: Department of Food Science, Aarhus University, Blichers Allé 20, Tjele, 8830, Denmark.
authors.forename: Bashar
authors.initials: B
authors.lastname: Amer
authors.forename: Caroline
authors.initials: C
authors.lastname: Nebel
authors.forename: Hanne C
authors.initials: HC
authors.lastname: Bertram
authors.forename: Grith
authors.initials: G
authors.lastname: Mortensen
authors.forename: Trine K
authors.initials: TK
authors.lastname: Dalsgaard
mesh_terms: D000818:Animals; D005230:Fatty Acids, Nonesterified / Q000737:chemistry / Q000302:isolation & purification*; D005243:Feces / Q000737:chemistry*; D005563:Formic Acid Esters / Q000737:chemistry; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods* / Q000662:veterinary; D055432:Metabolomics / Q000379:methods; D012997:Solvents / Q000737:chemistry; D013552:Swine
chemical_list: D005230:Fatty Acids, Nonesterified; D005563:Formic Acid Esters; D012997:Solvents; C007658:ethyl chloroformate