tailieunhanh - Spectrophotometric determination of arsenic in environmental and biological samples

A simple and sensitive spectrophotometric method has been developed for the determination of arsenic using variamine blue as a chromogenic reagent. The method is based on the reaction of arsenic(III) with potassium iodate in acid medium to liberate iodine, which oxidizes variamine blue to form a violet coloured species having an absorption maximum at 556 nm. | Indian Journal of Chemical Technology Vol. 13 January 2006 pp. 36-40 Spectrophotometric determination of arsenic in environmental and biological samples B Narayana Tom Cherian Mendalin Mathew Chand Pasha Department of Post Graduate Studies and Research in Chemistry Mangalore University Mangalagangothri 574 199 India Email nbadiadka@ Received 29 April 2005 revised received 25 October 2005 accepted 21 November 2005 A simple and sensitive spectrophotometric method has been developed for the determination of arsenic using variamine blue as a chromogenic reagent. The method is based on the reaction of arsenic III with potassium iodate in acid medium to liberate iodine which oxidizes variamine blue to form a violet coloured species having an absorption maximum at 556 nm. Beer s law is obeyed in the range pg mL-1 of As III . The molar absorptivity Sandell s sensitivity detection limit and quantitation limit were found to be L mol-1cm-1 2 pg cm-2 and pg mL-1 respectively. The optimum reaction conditions and other analytical parameters were evaluated. The proposed method has been successfully applied for the determination of arsenic in various environmental and biological samples. Keywords Arsenic Spectrophotometry Iodate Variamine blue IPC Code Int. G01J3 00 Arsenic compounds are widely used and have long been recognized as toxicants1-3. Trace concentrations of arsenic can also affect the physical and mechanical properties of metals and alloys4. Arsenic may accumulate in soils and sediments due to the use of arsenical pesticides fertilizers irrigation and oxidation of volatile arsine in air dust from the burning of fossils fuels as well as disposal of industrial municipal and animal wastes5. Arsenic is a constituent of many foods such as meat fish poultry grains and cereals6. It is used in medicine glass manufacture pigment production rodent poisons insecticides fungicides printing tanning etc. In excessive amounts .