Determination of trimethylamine oxide in seawater and small volumes of seafood tissue extract using flow injection analysis

A method is described for the indirect determination of trimethylamine oxide (TMAO) in small volumes of seawater (300 μl) and in seafood tissue extracts (100 μl). After simple TMAO reduction to trimethylamine (TMA), the samples were directly injected into the flow injection system enabling the TMAO to be measured as TMA. Calibration of the method with acidic TMAO standard solutions in the range of 10–200 μmol l−1 (n = 10) and with seawater TMAO standard solutions in the range of 10–100 μmol l−1 (n = 8) gave linear calibration curves (r = 0.999 in each case). The minimum detectable level for the method was 6 μmol l−1 while using the acidic standard solutions and 2.5 μmol l−1 for seawater TMAO standard solutions. Relative standard deviations were found to be <2% in all instances.