Spectrophotometric determination of trimethylamine nitrogen in raw waters using picric acid

Abstract

A sensitive and selective spectrophotometric method has been developed for the determination of trimethylamine nitrogen (TMA-N) based on the formation of a coloured complex by the reaction of TMA-N with picric acid in toluene. The wavelength of maximum absorbance of the complex is 410 nm and the system obeys the Beer-Lambert law between 0 and 2.5 p.p.m. of TMA-N. A molar absorptivity (ε) of 1.0 × 10⁴ l mol^–1 cm^–1 and a Sandell's sensitivity of 5.9 × 10^–3µg cm^–2 were obtained. The method has been satisfactorily applied to the determination of TMA-N in raw waters.