Spectrophotometric Determination of Selenium (IV) Using 4,5-diamino-o-xylene as a New Chromogenic Reagent

A simple, rapid, and sensitive spectrophotometric method for the determination of selenium (IV) based on the formation of a 1:2 complex with 4,5-diamino-o-xylene (DAX) as a new sensitive and selective chromogenic reagent is developed. The DAX reacts with selenium (IV) in the presence of citric acid to form a complex in the pH range of 1.0 2.2. The experimental conditions for determining selenium including the influences of pH, reagent concentration and time were evaluated and optimized. Under the optimum experimental conditions, the molar absorptivity of the complex was 1.27×104 L/mol–1 cm–1 at 340 nm. Beer's law is obeyed in the range of 1≃12 µg/mL–1. The limits of detection and quantization were 0.948 µg mL-1 and 3.16 µg/mL-1 respectively. The interfering effect of some cations and anions was also studied. This method can be applied to the direct and easy determination of selenium species as organic, inorganic, Se(VI) and Se(IV) in a variety of real samples.