Analytical methods for the determination and mass spectrometric confirmation of 1-methyl-2-nitroso-1,2,3,4-tetrahydro-beta-carboline-3-carboxylic acid and 2-nitroso-1,2,3,4-tetrahydro-beta-carboline-3-carboxylic acid in foods.
A method is described for the determination of the two title compounds that is based on: (a) extraction of the acidified sample with methanol, (b) removal of fats and lipids by partitioning of the extract with n-hexane, (c) clean-up on acidic alumina extraction cartridge, and (d) determination by a post-HPLC column chemical denitrosation-thermal energy analyser (TEA) technique or by conventional HPLC-TEA analysis after derivatization of the compounds with diazomethane. Confirmation was carried out by HPLC-mass spectrometry of the free acids and also by gas chromatography-mass spectrometry of the methyl esters. The formation of both 1-methyl-2-nitroso-1,2,3,4-tetrahydro-beta-carboline-3-carboxylic acid and 2-nitroso-1,2,3,4-tetrahydro-beta-carboline-3-carboxylic acid in nitrosated samples of several Japanese and Chinese pickled vegetables, one soy sauce, and two cheeses was demonstrated.
Sen
N P
NP
Food Research Division, Health Protection Branch, Ottawa, Canada.
Seaman
S W
SW
Baddoo
P A
PA
Weber
D
D
Malis
G
G
D002243:Carbolines / Q000032:analysis*; D002273:Carcinogens / Q000032:analysis*; D002851:Chromatography, High Pressure Liquid; D005504:Food Analysis / Q000379:methods*; D008401:Gas Chromatography-Mass Spectrometry; D013058:Mass Spectrometry; D009153:Mutagens / Q000032:analysis*; D015538:Nitrosation; D009603:Nitroso Compounds / Q000032:analysis*; D015203:Reproducibility of Results
D002243:Carbolines; D002273:Carcinogens; D009153:Mutagens; D009603:Nitroso Compounds; C072727:1-methyl-2-nitroso-1,2,3,4-tetrahydo-beta-carboline-3-carboxylic acid; C072728:2-nitroso-1,2,3,4-tetrahydro-beta-carboline-3-carboline-3-carboxylic acid