Add 50ml ammonium acetate (1 molL-1) into the soil sample (5g), then shake it for 30min, the extracted solution is used for directly determination of the exchangeable cations by ICP-AES. By the method, the detection limit of Ca, Mg, K, Na, Mn respectively are 0.0036µgmL-1, 0.0069µgmL-1, 0.0336µgmL-1, 0.00143µgmL-1 and 0.035µgmL-1. After testing the national standard substance (GBW 07416) of soil available composition, the analytical results are nearly in accord with standard values. The RE(n=11) of Ca, Mg, K, Mn are -1.94%, 6.61%, -2.5%, -9.09% and 3.59% respectively, and the RSD of the determined elements as Ca, Mg, K, Na, Mn are 0.96%, 1.80%, 4.65%, 0.54%, 0.71% respectively. |