Gives methods of microwave assisted digestion with hydrofluoric (HF), nitric (HNO[3]) and hydrochloric (HCL) acid mixture. Solutions produced by the methods are suitable for analysis e.g. by atomic absorption spectrometry (FLAAS, HGAAS, CVAAS, GFAAS), inductively coupled plasma emission spectrometry (ICP-OES) and inductive coupled plasma mass spectrometry (ICP-MS).