GC–MS analysis of phenolic compounds in fuels after conversion to trifluoroacetate esters

Abstract

The GC-MS characteristics of trifluoroacetate esters of phenolic compounds are discussed. Linear temperature programmed retention indices and total ion current MS response factors of over 120 phenolic esters are reported.The main GC advantages from analysis of trifluoroacetate esters as compared to plain phenols are enhanced volatility and improved resolution. For example, the elution temperature of a given phenol is typically 50 "C greater than that of the corresponding trifluoroacetate ester. Also, while retention of compounds with two trifluoroacetate groups is only moderately greater than mono esters, underivatized dihydroxy compounds are very difficult to elute from any GC column. Complete resolution of isomeric Co-, Ci-and Cn-alkylphenol esters is readily achieved on conventional fused silica GC columns; resolution of the corresponding underivatized compounds requires specialized GC columns with low temperature limits.In general, mass spectra of trifluoroacetate esters are more characteristic of a given structure than those of the corresponding phenols and may be more rigorously interpreted towards structural elucidation. A table in the report summarizes some of the more important spectral features used in compound identification.Example applications in analysis of coal-, shale-and petroleum-derived materials are presented. Selected ion monitoring is used to determine individual phenolic components in whole distillates; reconstructed ion chromatograms are used to illustrate distributions of selected species as a function of fuel storage and thermal stress.

Analysis of Polycyclic Aromatic Hydrocarbons and Their Oxygen‐Containing Derivatives and Metabolites in Soils

“…All target OPAHs have been identified and proposed as biological or abiotic degradation products of biphenyl, naphthalene, 1‐methylnaphthalene, 2‐methylnaphthalene, fluorene, acenaphthylene, acenaphthene, phenanthrene, and anthracene. 4,5‐Dihydroxyphenanthrene was analyzed because of its similarity to other identified dihydroxy phenanthrene metabolites of phenanthrene and its detection in fuels (Tittmann and Lingens, 1980; Cerniglia, 1984; Cerniglia, 1992; Green et al, 1994; Mahajan et al, 1994; Wang et al, 1995; Casellas et al, 1997; Meckenstock et al, 2004; Bamforth and Singleton, 2005; Zeinali et al, 2008). All solvents were picograde from Promochem (Wesel, Germany).…”

Determination of Sulfides and Thiols in Petroleum Distillates Using Solid-Phase Extraction and Derivatization with Pentafluorobenzoyl Chloride

“…Optimization of Derivatization Conditions. Although thiol derivatives can be formed using trifluoroacetic anhydride, N -methyl- N - tert -butyldimethylsilyltrifluoroacetamide, and 4-fluorobenzoyl chloride, PFBC was selected for reasons stated below. Trifluoroacetylated thiols coeluted with sulfides and exhibited noncharacteristic mass spectra.…”

“…In cases where analysis of fraction III (phenols, other polar types) was desired, it was performed using a previously described procedure for GC/MS analysis of phenols as their trifluoroacetate esters . The GC/MS conditions for this analysis were the same as specified above.…”

Determination of Alkylphenols after Derivatization to Ferrocenecarboxylic Acid Esters with Gas Chromatography-Atomic Emission Detection

“…There are several methods for the analysis of low molecular weight (C 0 −C 3 ) alkylphenols in organic matrixes. ,− For speciation of individual alkylphenols, the isolation of the phenol fraction is usually the first step, followed by high-performance liquid chromatography (HPLC) or gas chromatography (GC). Most isolation schemes employ a combination of aqueous alkaline extraction of the sample and, after acidification, back extraction into an organic solvent to prepare an extract suitable for GC or HPLC analysis. ,− Some methods involve fractionation of the sample into compound classes by adsorption column chromatography, , thin-layer chromatography, or solid-phase extraction (SPE) 22 while others use anion chromatography to isolate the acidic fraction of the oil, followed by ion-pair chromatography to separate phenolic from other acidic compounds . Determination of the individual alkylphenols with HPLC and electrochemical detection is easy to perform, but the chromatographic resolution is poor so that only C 0 - and C 1 -alkylphenols can be analyzed without coelution .…”

“…An acceptable resolution of the C 2 - and C 3 -alkylphenols can only be achieved through the high separating power of GC techniques, but then a derivatization of the isolated alkylphenol fraction is usually required. The analytes can be transformed into trimethylsilyl ethers, acetates, or trifluoroacetates, followed by GC analysis with flame ionization detection or mass spectrometry (GC/MS). Despite many different methods published, alkylphenol analysis is still a challenging task and is therefore far from being a routine parameter in, for example, crude oil analysis.…”