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

Simple tetrahydro-beta-carbolines (THbetaCs) and beta-carbolines (betaCs) are naturally occurring alkaloids in foods and food processing. This paper reviews the methods employed for their analysis. Procedures for THbetaC and betaC 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 THbetaCs with methyl chloroformate, or anhydrides are accomplished before GC-MS. Quantitative analysis of THbetaCs and betaCs 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 THbetaCs and betaCs. Fragmentation by collision induced dissociation or tandem mass spectrometry helps to complete trace identification. The occurrence of biologically relevant THbetaCs and betaCs in foods highlights the interest of accomplishing their analysis. Foods containing those compounds represent a source of possible THbetaCs and betaCs in humans.