Determination of the amino acid tryptophan and the biogenic amine tryptamine in foods by the heavy atom induced-room temperature phosphorescence methodology.
Very simple and selective methods are presented to determine the amino acid tryptophan (Trp) and the biogenic amine tryptamine (Tryp), both compounds with an indole-type molecular structure by the methodology named Heavy Atom Induced-Room Temperature Phosphorescence (HAI-RTP) which constitutes the first time that HAI-RTP has been used to detect compounds with non-naphthalenic structures in their molecules. Different variables affecting the phosphorescence signal (heavy atom perturber and sodium sulfite concentration) were carefully studied. The analytical curves give a linear dynamic range of 15-100 ng ml(-1) and a detection limit of 4 ng ml(-1) for Trp and 94-400 ng ml(-1) and 28 ng ml(-1) for Tryp. The methods have been successfully applied to the analysis of complex food matrices such as the presence of tryptophan in yoghurt and tryptamine in bottled beer. A single alkaline hydrolysis to release Trp from yoghurt proteins and two methods for extracting Tryp from beer samples are proposed and optimised. A total Trp content of 374 mg of Trp per kg of yoghurt was quantified by the standard addition method of calibration and a recovery of 90% was obtained for 250 ng ml(-1) of Tryp in spiked non-alcoholic beer samples.
Department of Analytical Chemistry, Faculty of Sciences, University of Granada, C/Fuentenueva s/n., 18071 Granada, Spain.
Beatriz
B
Cañabate-Díaz
Antonio Segura
AS
Carretero
Carmen
C
Cruces-Blanco
Alberto
A
Fernández-Gutiérrez
D001515:Beer / Q000032:analysis; D005506:Food Contamination / Q000032:analysis*; D049449:Luminescence; D013057:Spectrum Analysis / Q000379:methods; D014363:Tryptamines / Q000032:analysis*; D014364:Tryptophan / Q000032:analysis*; D015014:Yogurt / Q000032:analysis
D014363:Tryptamines; C030820:tryptamine; D014364:Tryptophan