Acrylamide is an unsaturated amide formed when carbohydrate-rich foods, such as roasted coffee, are subjected to high temperatures during thermal processing or cooking. The toxicological properties of acrylamide include neurotoxicity, genotoxicity, carcinogenicity, and reproductive toxicity. Coffee is a complex matrix because of the large number of components and the analysis of acrylamide is a considerable challenge because of its low molecular weight, high reactivity, lack of chromophore(s) and diagnostic ions in its MS spectrum. Established ISO methods [1] employ SPE-HPLC-MS-MS in an effort to perform its preconcentration, separation and identification. However, this method is time consuming and cannot be automated easily. An alternative to HPLC is GC-MS; however, most GC-MS methods require acrylamide preconcentration and derivatization. This study describes two approaches for the determination of acrylamide at trace-level in coffee brew and powder employing microextraction techniques based on Ionic Liquids (ILs) and Polymeric Ionic Liquids (PILs). A simple and rapid sampling and analysis method combining direct-immersion Solid-Phase Microextraction (SPME) with structurally-tuned PIL sorbent coated fibers with GC-MS was developed [2, 3]. Ninhydrin was employed as a quenching reagent during extraction to prevent the neo-formation of acrylamide from asparagine in the GC inlet. By tailoring the PIL structure, it was possible to reach limit of quantification for acrylamide in the sub-ppb range and the matrix compatibility of the PIL sorbent was proved by achieving results of quantification in coffee powders and brews comparable to the ISO method. A simple and rapid IL-based in situ Dispersive Liquid-Liquid Microextraction (DLLME) method was also developed and coupled to headspace GC-MS for the analysis of acrylamide in coffee brews with analytical performance and limits of detection compatible to the SPME method [4]. Given the high selectivity of structurally-tuned ionic liquids towards acrylamide, the popularity of GC-MS and the possibility of automation of the microextraction techniques, these two methods provide a new route for trace determination of acrylamide in coffee brew and powder, and can easily be extended to other food matrices.
Determination of acrylamide in roasted coffee powders and brews at ultra-trace level by GC-MS using microextraction techniques based on Ionic Liquids
Cecilia Cagliero;Carlo Bicchi;Arianna Marengo;Barbara Sgorbini;Patrizia Rubiolo
2021-01-01
Abstract
Acrylamide is an unsaturated amide formed when carbohydrate-rich foods, such as roasted coffee, are subjected to high temperatures during thermal processing or cooking. The toxicological properties of acrylamide include neurotoxicity, genotoxicity, carcinogenicity, and reproductive toxicity. Coffee is a complex matrix because of the large number of components and the analysis of acrylamide is a considerable challenge because of its low molecular weight, high reactivity, lack of chromophore(s) and diagnostic ions in its MS spectrum. Established ISO methods [1] employ SPE-HPLC-MS-MS in an effort to perform its preconcentration, separation and identification. However, this method is time consuming and cannot be automated easily. An alternative to HPLC is GC-MS; however, most GC-MS methods require acrylamide preconcentration and derivatization. This study describes two approaches for the determination of acrylamide at trace-level in coffee brew and powder employing microextraction techniques based on Ionic Liquids (ILs) and Polymeric Ionic Liquids (PILs). A simple and rapid sampling and analysis method combining direct-immersion Solid-Phase Microextraction (SPME) with structurally-tuned PIL sorbent coated fibers with GC-MS was developed [2, 3]. Ninhydrin was employed as a quenching reagent during extraction to prevent the neo-formation of acrylamide from asparagine in the GC inlet. By tailoring the PIL structure, it was possible to reach limit of quantification for acrylamide in the sub-ppb range and the matrix compatibility of the PIL sorbent was proved by achieving results of quantification in coffee powders and brews comparable to the ISO method. A simple and rapid IL-based in situ Dispersive Liquid-Liquid Microextraction (DLLME) method was also developed and coupled to headspace GC-MS for the analysis of acrylamide in coffee brews with analytical performance and limits of detection compatible to the SPME method [4]. Given the high selectivity of structurally-tuned ionic liquids towards acrylamide, the popularity of GC-MS and the possibility of automation of the microextraction techniques, these two methods provide a new route for trace determination of acrylamide in coffee brew and powder, and can easily be extended to other food matrices.
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