(Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn), DTPA
These metals are extracted by shaking 10 g of air dried soil for 2 hours in 20 mL of 0.005 M DTPA (diethylenetriaminepentaacetic acid). The filtrate is analyzed for Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn by ICP-OES. A soil to solution ratio of 1:5 or 1:10 is used for peats and mucks.
(See Method References No. 31 & 21)