Spectrophotometric Determination Of Copper (Ii) In Soil From Ahero Rice Irrigation Schemes Using Hydroxytriazene

Abstract

A simple, rapid, sensitive and cost effective spectrophotometric technique for the determination of copper (II) using 3-hydroxy-3-m-tolyl-1-O-carboxyphenyltriazene has been reported. The complex formed was greenishyellow having stoichiometry of 1:1 (Cu (II): hydroxytriazene) at a pH range of 6.0-6.6. The measurements were carried out at a working wavelength of 405nm with a molar absorptivity of 2.8×104Lmol-1 cm-1and sandell’s sensitivity of 2.26ng/cm2 . Lambert –Beer’s law is obeyed over a range of 1.27-7.63mg/L of copper. The correlation coefficient of the standard calibration curve was 0.997. The complex formed between copper (II) and hydroxytriazene was greenish –yellow with composition of 1:1(Cu (II): hydroxytriazene). The relative standard deviation (n=10) for standard dilution of 635.46mgL-1 copper (II) was 0.92%. The change in Gibb’s free energy at 270Cwas determined using Purohit’s, Harvey and Manning’s method and found to be respectively. The study showed that, the following cations and anions do not interfere when present at equivalent amount of copper: Cl- ,Br- , CH3COO- , CO3 2- , PO4 3- ,SO4 2- , C2O4 2- , I- , S2O3 2- , NO2- , SO3 2- ,S2- ,HPO4 2- , F- , NO3 - , WO4 2- , MO7O24 6- , NH4 + , Na+ , k + , Ba2+ , Cd2+ , Mg2+ , Ca2+ . However, UO2+ , Mn2+ , Pb2+ , Hg2+ , Sn2+ , Th4+,ZrO2+,Co2+ , Zn2+, Ni2+ interferes with copper (II) determination at equivalent amount, hence the need for the masking agent. The present method was applied to the determination of copper (II) in agricultural soil samples.