Analysis of the bioactive alkaloids tetrahydro-β-carboline and β-carboline in food

Simple tetrahydro-β-carbolines (THβCs) and β-carbolines (βCs) are naturally occurring alkaloids in foods and food processing. This paper reviews the methods employed for their analysis. Procedures for THβC and βC isolation and clean-up to remove interfering compounds are carried out by liquid–liquid extraction, and/or better solid-phase extraction under both reversed-phase (C18) and cation-exchange mechanisms. Chemical derivatizations of THβCs with methyl chloroformate, or anhydrides are accomplished before GC–MS. Quantitative analysis of THβCs and βCs is made by RP-HPLC (C18) with fluorescence detection providing good selectivity and sensitivity. For the same reasons, HPLC–MS is increasingly applied to these compounds. Electrospray and atmospheric pressure chemical ionization easily produce protonated molecules (M+H)+ of both THβCs and βCs. Fragmentation by collision induced dissociation or tandem mass spectrometry helps to complete trace identification. The occurrence of biologically relevant THβCs and βCs in foods highlights the interest of accomplishing their analysis. Foods containing those compounds represent a source of possible THβCs and βCs in humans.