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

Simple tetrahydro-beta-carbolines (TH beta Cs) and beta-carbolines (beta Cs) are naturally occurring alkaloids in foods and food processing. This paper reviews the methods employed for their analysis. Procedures for TH beta C and beta C 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 (C-18) and cation-exchange mechanisms. Chemical derivatizations of TH beta Cs with methyl chloroformate, or anhydrides are accomplished before GC-MS. Quantitative analysis of TH beta Cs and beta Cs is made by RP-HPLC (C-18) 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 TH beta Cs and beta Cs. Fragmentation by collision induced dissociation or tandem mass spectrometry helps to complete trace identification. The occurrence of biologically relevant TH beta Cs and beta Cs in foods highlights the interest of accomplishing their analysis. Foods containing those compounds represent a source of possible TH beta Cs and beta Cs in humans. (C) 2000 Elsevier Science B.V. All rights reserved.