Synthesis and Application of p-Carboxyarsenazo for Spectrophotometric Determination of Cu(II) in Environment Water

p-Carboxyarsenazo (CASA) color reagent was synthesized by simple diazotization reaction, and the chromomeric reaction between CASA with Cu(Ⅱ) has been studied by spectrophotometry. In pH=4.6 NaAc-HAc buffer solution, Cu(Ⅱ) reacted with CASA to form a red complex and exhibits an absorption maximum at 614 nm, Beer’s law is obeyed for 0-160 μg/L of copper in solution, the apparent molar absorptivity obtained is 1.57×104 L/(mol.cm), and the relative standard deviation (R.S.D.) is 1.6%. The proposed method exhibited high sensitivity and selectivity for Cu(Ⅱ). The results obtained by this method in the determination of environment water samples were accurate, sensitive and repeatable