Analysis of foods for heterocyclic aromatic amine carcinogens by solid-phase extraction and high-performance liquid chromatography

Abstract

Carcinogenic and mutagenic heterocyclic aromatic amines (HAA) are natural products often present at ng/g levels in muscle meats when they are cooked at temperatures over 150°C. Using solid-phase extraction and high performance liquid chromatography (HPLC) with photodiode array UV detection, samples were analyzed for the following heterocyclic amines: DiMeIQx(2-amino-3,4,8-trimethylimidazo[4,5-f]quinoxaline); IQ(2-amino-3-methylimidazo[4,5-f]quinoline); MeIQx(2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline); and PhIP(2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine). Quality control samples, analyzed periodically over two years in a blind study, show relative standard deviations ranging from 22 to 38% for the compounds found, variations typical for analysis at ng/g levels. Amounts range from undetectable levels (less than 0.1 ng/g) to hundreds of ng/g of PhIP for frying or grilling at high meat surface temperatures. Beef, chicken, pork and lamb can all have greater than 10 ng/g of PhIP. Ground chicken breast meat has lower amounts of heterocyclic amines than intact muscle pieces of the same size cooked identically. Restaurant prepared samples that we analyzed contained undetectable levels up to 14 ng/g total heterocyclic amines for a beef steak sample. Not extracted with the above method are related mutagenic heterocyclic amines, which have been reported in cooked foods in our laboratory and others. Method development using ion exchange on an SCX solid-phase extraction cartridge shows promise in providing a method for the quantitation of these mutagenic dimethyl-, trimethyl- and furo-imidazopyridines where a practical analysis method is needed.