A versatile method for the quantitative determination of ^β N-alkanoyl-5-hydroxytryptamides in roasted coffee

Since literature reports suggest ^β N-alkanoyl-5-hydroxytryptamides to account for stomach irritations perceived by sensitive subjects after coffee consumption, there is increasing interest in the concentrations of these substances in coffee and coffee products. A versatile analytical method for the accurate quantitative analysis of ^β N-alkanoyl-5-hydroxytryptamides in coffee by means of reversed-phase high-performance liquid chromatography with fluorescence detection and synthetic ^β N-heptadecanoyl-5-hydroxytryptamide as the internal standard was developed. Spiking coffee samples with known amounts of ^β N-alkanoyl-5-hydroxytryptamides followed by quantitative analysis revealed recovery rates of 99-103%. On the basis of the results of liquid chromatography-mass spectometry/mass spectometry experiments as well as co-chromatography with the synthetic reference compounds, the previously unknown ^β N-heneicosanoyl-5-hydroxytryptamide and ^β N-tricosanoyl-5-hydroxytryptamide were detected for the first time in coffee.