Spectrophotometric determination of selenium (IV) using methdilazine hydrochloride

Methdilazine hydrochloride is proposed as a selective and sensitive reagent for the spectrophotometric determination of selenium (IV). The reagent for ms a red radical cation by selenimum (IV) in hydrochloric acid medium and e xhibits an absorption maximum at 513 nm. Beer's law is valid over the conce ntration range 0.1-2.3 mg1(-1) of selenium (IV). Sandell's sensitivity of t he reaction is found to be 3.57 ng cm(-2) and the molar extinction coeffici ent is 9.32 x 10(4)1 mol(-1) cm(-1) at 513 nm. The effects of acidity, reag ent concentration, temperature and diverse ions upon the absorbance of the red species are critically assessed. The proposed method has been applied f or the determination of selenium in alloys.