Spectrophotometry Determination of Microgram Amounts of Chromium (III) In Waste Warter By Liquid-Solid Extraction

In 1 mol/L NaAC-Cl 3COOH medium at 3.5±0.1,Chrouium (Ⅲ) is quatitatively extracted and separated by liquid-solid extraction with 2-(5-bromine-2-pyridylazo)-5-diethylaminopheonol (5-Br-PADAP) and molten naphtahlene.This method of coloration complex compound is used in the microgram amount determination of chromium by spectrophotometry.The apparent molar absorptive coefficient is 4.7×10 4 L/mol·cm at 590 nm,and the constitute of complex is established as Cr:Cl 3AC -:5-Br-PADAP=1:2:1.This system obeys Beer's Law in the range of 0～10μg Cr/5ml (CHCl 3).