DETERMINATION OF HETEROCYCLIC AMINES IN FLAME-GRILLED FISH PATTY BY CAPILLARY ELECTROPHORESIS

A simple and reliable capillary zone electrophoretic (CZE) method for quantifying mutagenic and carcinogenic heterocyclic amines (HCAs) in c ooked foods with UV-visible diode-array detection is described. The bu ffer system consisted of 50 mM disodium hydrogen phosphate, 30 mM sodi um chloride, 20 mM citric acid and 26% methanol at pH 2.1. An uncoated silica tubing, 51 cm in length, was used for the CZE separation. The capillary tubing temperature was maintained at 25 degrees C with a con stant voltage of 20 kV. The reproducibility of the method was over 95% for a five-replicate analysis of 10 mu g/l-spiked amino-3,4,7,8-tetra methylimidazo[4,5-f]quinoxaline (4,7,8-TriMeIQx) and the detection lim it was in the low mu g/l range with coefficients of variation between 6 and 18%. An analytical run took only 15 min for 12 known HCAs. Using this procedure, up to 30 samples could be analysed in a single day. T he method is reliable and can be used for screening of various HCAs. I t has been applied to assess the concentrations of heterocyclic amines in otak-otak, a Malay-style grilled fish patty. The major mutagenic c ontaminant found in this foodstuff was 2-aminodipyrido[1,2-a:3',2'-d]i midazole (Glu-P-2) (286-1068 mu g/kg), followed by 2-amino-1-methyl-6- phenylimidazo[4,5-b]pyridine (PhIP) (1.6-13.0 mu g/kg) and 2-amino-3-m ethylimidazo[4,5-f]quinoline (IQ) (14.0-87.5 mu g/kg). Two co-mutagens norharman (NH) and barman (H) were also detected in otak-otak at leve ls of 2.0-13.0 mu g/kg and 12.8-21.3 mu g/kg, respectively. The substa ntial amount of Glu-P-2 detected in otak-otak is probably a result of the ingredients used and the high temperature grilling process.