Speciation of Inorganic Arsenic in Waters by Potentiometric Flow Analysis with On-Line Preconcentration

• Type: Article in International Scientific Journal
• Date: 2005

Authors

J. A. Rodríguez (Author) Other; E. Barrado (Author) Other; M. Vega (Author) Other; J. L. F. C. Lima (Author) FFUP

Journal

Title: Electroanalysis

Vol. 17 No. 5

Pages: 504-511

ISSN: 1040-0397

Publisher: Wiley-Blackwell

Indexing

ISI Web of Knowledge - 7 Citations

ISI Web of Science

Scopus - 10 Citations

Scientific classification

FOS: Medical and Health sciences > Other medical sciences

CORDIS: Health sciences

Other information

Authenticus ID: P-000-4DY

Resumo (PT): Keywords Arsenic • Speciation • Groundwater • Flow analysis • Potentiometry • Ion-selective electrode • On-line preconcentration A potentiometric flow system has been developed for the direct determination of arsenic(V) in water samples after on-line preconcentration in a minicolumn packed with a new adsorbent material selective to As(V). Iron oxyhydroxide embedded in silica gel was synthesized and used simultaneously as adsorbent material in the minicolumn and as selective component in a tubular potentiometric electrode. In the first step, the sample solution is mixed on-line with phosphate buffer of pH 7 and pumped through the minicolumn to adsorb As(V). The insertion of the minicolumn in the mobile section of a homemade injector-commutator allows to relocate the minicolumn to desorb the retained As(V) in the second step. The desorption is maximum in the presence of 0.1 M phosphate of pH 12. Maximum response of the tubular selective membrane is achieved in phosphate buffer of pH 7. On-line oxidation of As(III) to As(V) by iodine (I3-) in the presence of phosphate buffer of pH 7 allows the determination of total As as As(V) and then the speciation of inorganic arsenic, since As(III) can be estimated as the difference between total As and As(V). In the optimized experimental conditions, a linear range of 40-500 g L-1 for As(V), and detection limits of 30.6 and 38.6 g L-1 for As(V) and total As, respectively, were obtained.The flow system has been successfully applied to the determination of inorganic arsenic species in groundwater samples collected in areas affected by arsenic contamination. Relative standard deviation of replicated determinations of As in groundwater samples was always below 5%. <br> <br> Keywords Arsenic • Speciation • Groundwater • Flow analysis • Potentiometry • Ion-selective electrode • On-line preconcentration <br> <a target="_blank" href="http://www3.interscience.wiley.com/journal/109880290/abstract">Texto integal </a> <br> <br>

Abstract (EN): Keywords Arsenic • Speciation • Groundwater • Flow analysis • Potentiometry • Ion-selective electrode • On-line preconcentration A potentiometric flow system has been developed for the direct determination of arsenic(V) in water samples after on-line preconcentration in a minicolumn packed with a new adsorbent material selective to As(V). Iron oxyhydroxide embedded in silica gel was synthesized and used simultaneously as adsorbent material in the minicolumn and as selective component in a tubular potentiometric electrode. In the first step, the sample solution is mixed on-line with phosphate buffer of pH 7 and pumped through the minicolumn to adsorb As(V). The insertion of the minicolumn in the mobile section of a homemade injector-commutator allows to relocate the minicolumn to desorb the retained As(V) in the second step. The desorption is maximum in the presence of 0.1 M phosphate of pH 12. Maximum response of the tubular selective membrane is achieved in phosphate buffer of pH 7. On-line oxidation of As(III) to As(V) by iodine (I3-) in the presence of phosphate buffer of pH 7 allows the determination of total As as As(V) and then the speciation of inorganic arsenic, since As(III) can be estimated as the difference between total As and As(V). In the optimized experimental conditions, a linear range of 40-500 g L-1 for As(V), and detection limits of 30.6 and 38.6 g L-1 for As(V) and total As, respectively, were obtained.The flow system has been successfully applied to the determination of inorganic arsenic species in groundwater samples collected in areas affected by arsenic contamination. Relative standard deviation of replicated determinations of As in groundwater samples was always below 5%. <br> <br> Keywords Arsenic • Speciation • Groundwater • Flow analysis • Potentiometry • Ion-selective electrode • On-line preconcentration <br> <a target="_blank" href="http://www3.interscience.wiley.com/journal/109880290/abstract"> Full text</a> <br> <br>

Language: Portuguese

Type (Professor's evaluation): Scientific