Patent ID: 7446874
Filing Date: 2008-11-04
Classification: G01N

Abstract:
1. A method for quantitative determination of arsenic concentration in a water sample in the field, wherein the water sample comprises phosphates that have an order of magnitude or more higher concentration than the arsenic concentration, the method comprising: (a) adding an acid reagent to the water sample to acidify the water and also reduce arsenic; (b) adding an oxidizing reagent to a test water sample aliquot to oxidize arsenic in the aliquot to an arsenate state; (c) adding a color reagent to the test water sample aliquot and a reference acidified water sample aliquot, whereby phosphates in the reference aliquot and both phosphates and arsenates in the test aliquot and are converted into color complexes; (d) using optical probes to measure light absorbance of the color complexes formed in each aliquot; and (e) using the measured light absorbances for the two aliquots to calculate the arsenic concentration in the water sample.