Square-Wave Adsorptive Cathodic Stripping Voltammeteric Determination of Manganese (II) Using a Carbon Paste Electrode Modified with Montmorillonite Clay

Abstract

Manganese is an essential micronutrient for allorganisms; however at high concentrations it has a toxic effect.Manganese toxicity is a serious constraint to crop cultivation since itis taken-up by plants and can easily be passed into the food chain againcausing symptoms of Parkinson’s disease. A fully validated square-waveadsorptive cathodic stripping voltammetry method has been developed fordetermination of Mn (II) as a complex with 2-(5’-bromo-2’-pyridylazo) 5-diethylaminophenolin aqueous solutions using a carbon paste electrode (CPE) modified withmontmorillonite-Na clay. The results showed that the modified CPE (90% (w/w)graphite powder and 10% (w/w) montmorillonite-Na clay) exhibited excellentelectrochemical activity towards the investigated Mn (II) complex in acetatebuffer of pH = 5.0. Factors affecting the performance of the modified carbonpaste electrode and the sensitivity of the described square- wavestripping voltammetry method, including the electrode composition,concentration of ligand, pulse parameters and preconcentration conditions wereexamined. A detection limit (S/N = 3) of 0.015μg·L-1 (2.73 × 10-10 mol·L-1)Mn (II) was achieved when a preconcentration time of 240 s was applied.Insignificant interferences from various inorganic and organic species wereestimated. The described square-wave adsorptive cathodic stripping voltammetrymethod coupled with the modified carbon paste electrode has been successfullyapplied to Mn (II) analysis in different water samples.