A novel liquid chromatography–mass spectrometric method for the simultaneous determination of trimethylamine, dimethylamine and methylamine in fishery products

A novel multianalyte method has been developed to determine the concentration of trimethylamine (TMA), dimethylamine (DMA) and methylamine (MA) in fish. The optimal points of the key parameters (pH 8, 60 °C and 60 min of reaction time) were determined for the reaction with tert-butyl bromoacetate. An HILIC column was used to elute all the compounds in only 12 min and selective quantitation of the compounds was achieved. The methodology was validated in trout, hake and Atlantic horse mackerel and was used to study the shelf life of fish under refrigeration. A good correlation with the picrate method was obtained and the proposed methodology has been proved to be robust, specific and sensible with a limit of detection of 0.08 mg N-TMA kg(-1) in freshwater fish and 1 mg N-TMA kg(-1) in marine fish. In addition, TMA has been proved to be a good spoilage indicator also in freshwater fish.