Supercritical fluid extraction (SFE) of 4(5)-methylimidazole (4-MeI) and 2-acetyl-4(5)-(1,2,3,4)-tetrahydroxybutyl-imidazole (THI) from ground-coffee with high-performance liquid chromatographic-electrospray mass spectrometric quantification (HPLC/ESI-MS). 2006

L Lojková, and B Klejdus, and J Moravcová, and V Kubán
Department of Chemistry and Biochemistry, Mendel University of Agriculture and Forestry Brno, Zemedelská 1, CZ-613 00 Brno, Czech Republic.

Two polar analytes, 4(5)-methylimidazole (4-MeI) and 2-acetyl-4(5)-(1,2,3,4)-tetrahydroxybutyl-imidazole (THI), were extracted with supercritical carbon dioxide (CO2) modified with aqueous methanol. The method was applied to a roasted coffee powder with good recovery rates. Method efficiency was compared with that of solid-phase extraction using SCX Disc cartridges and validated for spiked solid matrix. The analytes were determined using isocratic liquid chromatography-mass spectrometry (LC/MS) on an Atlantis HILIC Silica column (150 x 2.1 mm, 3 microm) with 80% methanol and 20% 0.01 mol l-1 ammonium formate as the mobile phase. The limit of quantification was around 1.5 pg for 4-MeI and 2.0 pg for THI. The linearity of the calibration curves was satisfactory as indicated by correlation coefficients of >0.999. The coefficient of variation for the intra-day and inter-day precisions was <4% (n = 6). Accuracy was in the range 98-101%; recovery rates were > or = 98 and > or = 99% for THI and 4-MeI, respectively. Several samples of Arabica coffee from various locations and commercially available 'off-the-shelf' coffee products (Arabica/Robusta mixtures) were analysed to test the method.

UI MeSH Term Description Entries
D007093 Imidazoles Compounds containing 1,3-diazole, a five membered aromatic ring containing two nitrogen atoms separated by one of the carbons. Chemically reduced ones include IMIDAZOLINES and IMIDAZOLIDINES. Distinguish from 1,2-diazole (PYRAZOLES).
D002851 Chromatography, High Pressure Liquid Liquid chromatographic techniques which feature high inlet pressures, high sensitivity, and high speed. Chromatography, High Performance Liquid,Chromatography, High Speed Liquid,Chromatography, Liquid, High Pressure,HPLC,High Performance Liquid Chromatography,High-Performance Liquid Chromatography,UPLC,Ultra Performance Liquid Chromatography,Chromatography, High-Performance Liquid,High-Performance Liquid Chromatographies,Liquid Chromatography, High-Performance
D003069 Coffee A beverage made from ground COFFEA beans (SEEDS) infused in hot water. It generally contains CAFFEINE and THEOPHYLLINE unless it is decaffeinated.
D005504 Food Analysis Measurement and evaluation of the components of substances to be taken as FOOD. Analysis, Food,Analyses, Food,Food Analyses
D005506 Food Contamination The presence in food of harmful, unpalatable, or otherwise objectionable foreign substances, e.g. chemicals, microorganisms or diluents, before, during, or after processing or storage. Food Adulteration,Adulteration, Food,Adulterations, Food,Contamination, Food,Contaminations, Food,Food Adulterations,Food Contaminations
D021241 Spectrometry, Mass, Electrospray Ionization A mass spectrometry technique used for analysis of nonvolatile compounds such as proteins and macromolecules. The technique involves preparing electrically charged droplets from analyte molecules dissolved in solvent. The electrically charged droplets enter a vacuum chamber where the solvent is evaporated. Evaporation of solvent reduces the droplet size, thereby increasing the coulombic repulsion within the droplet. As the charged droplets get smaller, the excess charge within them causes them to disintegrate and release analyte molecules. The volatilized analyte molecules are then analyzed by mass spectrometry. ESI Mass Spectrometry,Electrospray Ionization Mass Spectrometry,Mass Spectrometry, ESI,Spectrometry, ESI Mass
D025924 Chromatography, Supercritical Fluid A CHROMATOGRAPHY method using supercritical fluid, usually carbon dioxide under very high pressure (around 73 atmospheres or 1070 psi at room temperature) as the mobile phase. Other solvents are sometimes added as modifiers. This is used both for analytical (SFC) and extraction (SFE) purposes. Supercritical Fluid Chromatography,Supercritical Fluid Extraction,Extraction, Supercritical Fluid,SFC (Supercritical Fluid Chromatography),SFE (Supercritical Fluid Extraction),Fluid Chromatography, Supercritical,Fluid Extraction, Supercritical

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