Determination of vanadium in air-borne particulate matters by a catalytic photometric method

Particulate matters were collected on a membrane filter (MF Millipore RA, pore size 1.2 μm, diam. 47 mm) by use of a low volume air sampler at flow rate of 20 liter/min for several hours, the filter with particulates was digested with 5 ml of HNO3(1 + 1) and 1 ml of hydrogen peroxide (30%) by heating on a hotplate for 30 min and then was completely decomposed with 2.5 ml of sulfuric acid (2 N) and 1 ml of hydrogen peroxide (60%). After filtration the filtrate was diluted to 50 ml in a volumetric flask. An aliquot (containing vanadium less than 120 ng) of this solution was transfered to a glass beaker (100 ml) and diluted to ca. 50 ml with water after addition of sulfuric acid (2 N) and hydrogen peroxide (3%) to make the resultant solution 0.1 N in sulfuric acid and 0.1% in hydrogen peroxide. Vanadium was then separated from most other elements by a combined cation- and anion-exchange method and was determined by the catalytic method based on gallic acid-bromate reaction. The method allows the determination of vanadium as low as 3 ng without interference from other elements commonly found in the air-borne particulates and is able to give information of the variation of vanadium concentration in a day. (auth.)