A new and simple procedure for the polarographic speciation and determination of trace inorganic As(III) and As(V) species

Authors : Ülkü ÜNAL, Güler SOMER

Pages : 779-792

Doi:10.3906/tar-1205-20

View : 17 | Download : 9

Publication Date : 0000-00-00

Article Type : Research Paper

Abstract :A new and simple differential pulse polarographic method was developed for the trace determination of Asinsert ignore into journalissuearticles values(III); and Asinsert ignore into journalissuearticles values(V); species in the same sample. Among several electrolytes, 0.1 M HCl was found to be the most suitable. Asinsert ignore into journalissuearticles values(III); had 3 peaks in this medium, and the peak at --0.82 V was chosen because of its peak shape and response to standard additions. In this medium, the limit of detection for Asinsert ignore into journalissuearticles values(III); was found to be 1.5 \times 10-7 M. Since Asinsert ignore into journalissuearticles values(V); is not electroactive, it had to be reduced first into Asinsert ignore into journalissuearticles values(III);. For this purpose, KI in an acidic and hot medium was found to be suitable. For Asinsert ignore into journalissuearticles values(V);, the limit of detection was 1.0 \times 10-7 M. The interference effects of the most common cations, such as Feinsert ignore into journalissuearticles values(III);, Cuinsert ignore into journalissuearticles values(II);, Pbinsert ignore into journalissuearticles values(II);, and Zninsert ignore into journalissuearticles values(II);, and of anions such as sulfate, chloride, and nitrate ions, were investigated. None of these ions had an overlapping peak with the peaks of Asinsert ignore into journalissuearticles values(III); in this medium. However, it was found that only Feinsert ignore into journalissuearticles values(III); could oxidize Asinsert ignore into journalissuearticles values(III);. This creates problems in Asinsert ignore into journalissuearticles values(V); determination, since Asinsert ignore into journalissuearticles values(III);, which was formed from the reduction of Asinsert ignore into journalissuearticles values(V);, will be oxidized by Feinsert ignore into journalissuearticles values(III); and Asinsert ignore into journalissuearticles values(V); determination will not be correct. This problem was eliminated with KI, added for the reduction of Asinsert ignore into journalissuearticles values(V);. Asinsert ignore into journalissuearticles values(III); and Asinsert ignore into journalissuearticles values(V); concentrations for a sample containing 1 \times 10-5 M Asinsert ignore into journalissuearticles values(III); and 1 \times 10-5 M Asinsert ignore into journalissuearticles values(V); could be determined with high accuracy. This method was applied to the tap water of Ankara.
Keywords : Arsenic speciation, differential pulse polarography, determination, elimination of interference, arsenic in tap water