Determination of iron with 2-(2-hydroxy-5-methoxyphenylazo)-4-methylthiazole

Studies on 2-(2-hydroxy-5-methoxypheylazo)-4-methylthiazole as an analytical reagent. V

Abstract

2-(2-Hydroxy-5-methoxyphenylazo)-4-methylthiazole reacts with ferrous ion and forms waterinsoluble violet-colored chelate compound. This is soluble in organic solvents, such as isoamylalcohol, benzene and chloro-form, and these solutions have violet color. The isoamyl-alcohol solution has absorption maxima at 777, 559, and 391 mμ (Fig. 1). The absorption at 777 mμ is convenient for detirmination of iron. The iron chelate at pH 5. 57.0 can be extracted completely by isoamyl-alcohol as indicated in Fig. 2, and the sensitivity is found to be 0.004γ/cm². The abosorption curves of isoamyl-alcohol extract of the reagent-ferrous iron system are all close to around 513 mμ, indicating the formation of only one kind of chelate (Fig. 5). From the results of continuous variation method (Fig. 3) and slope ratio method, the chelate is found to consist from iron and reagent in the ratio of 1: 2 (Fig 4). The disturbance by the presence of copper, nickel and cobalt is found to be great and phosphoric acid showed also disturbing influence but tartaric acid had no disturbing influence.