Spectrophotometric Determination of Trace Arsenic in Water Samples Using a Nanoparticle of Ethyl Violet with a Molybdate−Iodine Tetrachloride Complex as a Probe for Molybdoarsenate
- 14 October 2006
- journal article
- Published by American Chemical Society (ACS) in Analytical Chemistry
- Vol. 78 (22), 7682-7688
- https://doi.org/10.1021/ac061074h
Abstract
A new spectrophotometric method was developed for the determination of low ppb levels of arsenic in water. We found that Ethyl Violet with molybdate−iodine tetrachloride complex forms nanoparticles under acidic conditions, which provide a sensitive probe for molybdoarsenate. The nanoparticles form stable particles with a diameter micrometers in size in the presence of heteropolyacid, and the resulting particles give a purple color to the apparently homogeneous solution, the intensity of which depends on the arsenic concentration. The nanoparticle itself is unstable due to conversion of the dye to a colorless carbinol species under acidic conditions without heteropolyacid. Although triphenylmethane dyes have been the subject of a number of investigations, there do not appear to be any reports on the dye particles for trace determination. The calibration curve is linear up to 20 μg L-1 arsenic, and the detection limit is 0.5 μg L-1 (6.6 × 10-9 mol L-1). The coefficient of variation for spectrophotometry at 10 μg L-1 is 5.8% (n = 8). Furthermore, it is possible to detect concentrations as low as 1 μg L-1 arsenic visually using this method. The interferences from phosphorus and silica were eliminated using an anion exchange column and sodium fluoride as a masking agent, respectively. The proposed method has been successfully applied to water samples in abandoned mine water, groundwater, and river water. There was good agreement between the results obtained by the proposed method and those by hydride generation atomic absorption spectrometry. Since this method is specific for As(V), it is applicable to the speciation of arsenic oxidation states. Our method has enormous practical potential for simple and field detection of arsenic, requiring no complex apparatus or skilled laboratory support.Keywords
This publication has 12 references indexed in Scilit:
- Spectrophotometric Determination of Arsenic in Water Samples Based on Micro Particle Formation of Ethyl Violet- MolybdoarsenateAnalytical Sciences, 2006
- Speciation-Capable Field Instrument for the Measurement of Arsenite and Arsenate in WaterAnalytical Chemistry, 2005
- Study of MCPA and MCPP Herbicides Mobility in Soils from North‐West Croatia as Affected by Presence of FertilizersJournal of Environmental Science and Health, Part B, 2003
- Effectiveness and Reliability of Arsenic Field Testing Kits: Are the Million Dollar Screening Projects Effective or Not?Environmental Science & Technology, 2002
- Arsenic calamity in the Indian subcontinent What lessons have been learned?Talanta, 2002
- Arsenic in groundwater and health problems in BangladeshWater Research, 1999
- Equilibrium and Kinetic Studies on the Formation of Triphenylmethanols from Triphenylmethane DyesBulletin of the Chemical Society of Japan, 1994
- Rapid determination of trace amounts of phosphate and arsenate in water by spectrophotometric detection of their heteropoly acid-malachite green aggregates following pre-concentration by membrane filtrationThe Analyst, 1987
- A new micromethod for the colorimetric determination of inorganic phosphateClinica Chimica Acta; International Journal of Clinical Chemistry, 1966
- Kristallviolett. Eine quantitative Untersuchung über die Protolysenverhältnisse in Wasserlösungen.Acta Chemica Scandinavica, 1958