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DETERMINATION OF Cu, Cd, Mn, Ni, Zn <br />Fe, Pb IN SOILS BY DTPA EXTRACTION <br />(Walsh, L. M. and Beaton, T. D. 1973 Soil Testing and Plant Analysis) <br />Reagents <br />DTPA - Diethylene triamine pentaacetic acid. <br />41o Nay DTPA, TEA -Triethanolamine, Calcium chloride, HC1 conc. <br />All water shall be distilled-deionized (d & d) <br />DTPA-TEA extracting solution - 0.005M DTPA, O.1h1 TEA, <br />O.O1M CaC12, pH 7.3. <br />a. Pour approximately 800 ml of d 5 d water into a 1 <br />liter beaker. <br />b. Add 4.Sm1 DTPA and swirl to mix. <br />c. Add 13.3 ml TEA and swirl to mix. <br />d. Add l.llg CaC12 and swirl to dissolve. <br />• e. Adjust pH of this solution to 7.3 with conc. HC1 <br />and bring to volume in a 1 liter volumetric flask <br />with d & d water. <br />Standards <br />Pipet appropriate aliquots of 1000 ppm stocks into a 1 liter <br />volumetric flask and dilute to volume with DTPA extracting <br />solution. <br />High ppm Low ppm <br />Fe 4 1 <br />Cu 4 1 <br />Zn 2 1 <br />Pb ~: 1 <br />Cd 2 1 <br />Ni •~ 1 <br />Mn 4 1 <br />Al 4 1 <br />Procedure <br />a. Weigh lOg of soil into a centrifuge tube. <br />• b. Pipet 20.Om1 of DTPA-TEA extractant to each sample <br />and prepare blank. <br />c. Stopper centrifuge tube tightly with Nalgene stopper <br />and shake vigorously for 2 hours. <br />6-103 <br />