Study On Color Reaction Of Antimony With 2-(3,5-dibromo-2-pyridylazo)-5-diethylaminophenol (3,5-br2-padap) In The Presence Of Emulsifier Op

This paper describes a method by which the antimony in soil samples can be determined spectrophotometrically, employing 3,5-br2-PADAP and emulsifier OP. The optimum acidity of the color reaction is in the range of 0.12 to 0.25 M hydrochloric acid. The blue-green complex formed exhibits an absorption maximum at 630 nm with a molar absorptivity of 5.2 × 104 L. mol−1 cm−1. Beer's law is obeyed in the range of 0 to 25 μg of antimony per 10 ml of solution. The effect of experimental variables and interferences of foreign ions are reported. The digestive method of soil samples has also been studied. The method has been successful for determining antimony in soil.