The Use of 2,3-dichloro-1,4-naphthaquinone for the Spectrophotometric Determination of Some Primary Aliphatic Amines in Aqueous Solution

Abstract<br /> A simple and accurate spectrophotometric method was developed for the quantitative determination of some primary aliphatic amines in aqueous solution, i.e. ethanolamine, n-butylamine and n-hexylamine. The method is based on the interaction of these amines in aqueous medium with 2,3-dichloro-1,4-naphthaquinone (DClNQ) reagent in the presence of bicarbonate buffer solution to form an orange coloured products measurable at maximum wavelength of 475 nm. Beer’s law is obeyed over the concentration range of 1-30, 5-20 and 3-30g/ml for ethanolamine, n-butylamine and n-hexylamine respectively. The DClNQ products were formed in the ratio of 1:1 amine: DClNQ, and their stability constants were ranged between 1.92105 and 4.14105 L.mol-1. The method was successfully applied for the determination of ethanolamine in its pharmaceutical preparation.