Spectrophotometric Determination of Trace Amounts of Nickel ion By Using Tetra(4-hydroxyphenyl) Porphyrin (THPP) and Tetra(4-bromo phenyl)Porphyrin (TBPP)

Abstract

this work , the reaction of THPP and TBPP with nickel ion was studied Spectrophotometrically and kinetics as well as the thermodecomposition of NiTHPP complex with increasing the heating temperature as function of time was determined. The porphyrins were found to be a highly sensitive and selective reagents for direct Spectrophotometric determination of nickel ion at 0.031 µg/5ml for THPP and at 0.236 µg/10 ml level. The soret band of NiTHPP complex lies at 420 nm (€ = 2 x 105 L.M-1. cm-1), and at 414nm (€ =5.7 x 104 L.M-1. cm-1) for NiTBPP complex in DMF solvent. The complexes can be formed within 10 minutes by heating on hot plate (80 C◦). Four determination of standard solutions containing 0.946 µg/5ml Ni(ll) ion with THPP and 0.685 µg/10ml Ni(ll) ion with TBPP gave relative standard deviation RSD 0.074% and 0.065% respectively. Beer's Law is obeyed in the range of 0.01-2.55 µg/5ml and 0.01-2.34 µg/10ml , sandell's index were 0.00367 and 0.001 for the absorbance of 0.001 respectively. The mole ratio of complexes are 1:1, the interference of cations was studied as well. These ligands were used to determine nickel ion in phosphate crude stones sample and gave a satisfactory results.