A Study for the Evaluation of Quantitative Reaction Conditions Between As(V) and Ti(III) for the DP Polarographic Determination of Electroinactive As(V) and Application

Abstract

In this investigation a differential pulse polarographic method (DPP) is established to
determine the electroinactive arsenic (V), which is formed after the wet digestion of the
natural samples. For this purpose, As(V) formed is reduced into As(III) using Ti(III).
According to the literature survey this redox reaction between As(V) and Ti(III) has been
used first time in this work. In order to have the reaction quantitative the optimum reaction
conditions such as Ti(III)/ As(V) concentration ratio, reaction pH, waiting time for reaction
and temperature had to be investigated. It was found that Ti(III)/ As(V) concentration ratio
had to be larger than 3-5 times, HCl concentration 0.4 to 1.0 M, reaction temperature 60 -
90 ºC and waiting interval 3-5 minutes. Under the experimentally decided conditions the
reduction was very fast and quantitative. No interference was observed from most common
ions. The LOD was found as 1.5×10-7 M. The newly developed method is applied for the
determination of arsenic in beer. The reduction procedure takes place directly in
polarographic cell. This newly developed method can safely be used for the speciation of
As(III) and As(V) and for total arsenic quantity determination in natural samples