LIQUID-CHROMATOGRAPHIC DETERMINATION OF METHYLAMINES - DETERMINATION OF TRIMETHYLAMINE IN FISH SAMPLES USING A POROUS GRAPHITIC CARBON STATIONARY-PHASE

A method is described for the separation of methylamine, dimethylamine and trimethylamine on porous graphitic carbon (PGC) using ion interac tion chromatography. The method developed used an aqueous eluent of 5 mM heptane sulphonic acid in 5 mM sodium phosphate buffer at pH 9. Cal ibration graphs were linear in the range 0.1-10 mM for trimethylamine and 5-50 mM for methylamine and dimethylamine; the relative standard d eviation for each amines was 3.1%. The method was applied to the deter mination of trimethylamine in fish tissue and recoveries of 99.7-102.0 % were obtained for the fish extracts. The levels of trimethylamine in freshly defrosted cod were below the detection level of the method, b ut 2.2 mM was found in extracts of samples stored for 14 days at 4 deg rees C.