Screening of Chromogenic Reagents for Determination of Heavy Metals by UV-Visible Spectrophotometry

Abstract

The aim of this study is to determine the quantity of metal present in a sampleusing UV-Vis spectrophotometry and various chromogenic reagents. The screening ofsuitable chromogenic reagents involved complexation between the chromogenic reagent
and the heavy metal (present in various concentrations) and the construction of acalibration curve that then determined the presence of the heavy metal. Seven reagentswere used, these being methylene blue, 4-nitrophenyl acetate, methyl orange, methyl red
and polycarboxylate ligand compounds, together with three heavy metals (Cr, Pb and Ni).The results showed that all chromogenic reagents could be complexed with metals andthat the rate of absorbance significantly increased when the concentration of the metalwas raised. Unfortunately, this failed to give satisfactory results since the expectedcalibration curve was not obtained and thus it could not be used to determine thepresence of heavy metals (R2< 0.995).