344 research outputs found
Naphthidines as redox indicators in titrations with vanadate
Naphthidine, naphthidinedisulphonic acid, 3,3'-dimethylnaphthidine and 3,3'-di-methylnaphthidinedisulphonic acid have been studied as redox indicators in titrations with vanadate. Sharp colour changes are obtained at the equivalence points in titrations of 0.05-0.01 N solutions of iron(II), hydroquinone, molybdenum(V) and uranium(IV) under appropriate conditions of acidity with oxalic or phosphoric acid as indicator catalyst. The transition potentials are reported. © 1978
Rapid Spectrophotometric Determination of Thallium with Mepazine Hydrochloride
179-180Mepazine hydrochloride reacts with thallium(III) at room temperature in phosphoric acid medium to give and orange-red species with an absorption maximum at 512 nm. The reaction obeys Beer’s law over the concentration range 0.1-13.0 μg/ml of thallium(III) with an effective spectrophotometric range of 1.8-11.0 μg/ml. The molar absorptivity is 1.60 x 104 dm3 mol-1 cm-1. The efficacy of the method is shown by the successful determination of thallium in synthetic thallium alloys
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