Determination of trimethylamine in fish by flow injection analysis

Increased trimethylamine (TMA) levels in tissues are considered to be characteristic of marine fish spoilage. A direct method has been developed for the determination of TMA in aqueous solutions and in fish muscle extracts, which involves the extraction of a small quantity of tissue (1 g) in perchloric acid and the subsequent analysis of the extract by an inexpensive flow injection/gas-diffusion system. Interferences from other volatile amines present in the extract were suppressed by the use of formaldehyde. The calibration was found to be linear between 0-200 μmole l-1 (r = 0.999) with an R.S.D. of 1.15% (n = 10) at 50 μmole l-1 TMA and a limit of detection of 6 μmole l-1 (= 0.53 μg TMA g-1 of wet tissue under these conditions and in this study).