Improved aqua regia metal extraction using a loam soil CRM ERC-CC141 and a performant microwave oven

In this study a digestion method for determination of metals (Co, Cr, Cu, Ni, Pb, Zn) in soil aqua regia extracts was performed using a microwave digestion technique combined with ICP-EOS and FAAS techniques. Improved digestion program was applied in three steps at 220ºC maximum temperature for 35 minutes to 1 g of soil with a mixture of HCl and HNO3 (report 6 mL to 2 mL). In experimental studies was used a Certified Reference Material CRM ERC-CC141 loam soil. The recovery percentages in CRM standard were situated for all metals in the range 93.5% to 105% for ICP-EOS determinations and 92% to 107% for FAAS determinations.