New Method for Analysis of Trimethylamine Oxide Using Ferrous Sulfate and EDTA

Abstract
In the analysis of trimethylamine oxide (TMAO) in fish tissues, an equimolar mixture of ferrous sulfate (FeSO4) and disodium ethylenediaminetetraacetic acid (EDTA) (0.1 M) in acetate buffer (0.8 M, pH 4.5) was found to be a satisfactory replacement for titanium chloride (TiCl3). The TiCl3 method for TMAO was usually conducted at 80°C; the FeSO4‐EDTA reaction at 50°C appeared complete in 5 min and yielded comparable results. The use of an acetate buffer alleviated any interference from the trichloroacetic acid used for extraction of TMAO and trimethylamine (TMA) from fish tissue.