The best choice by far would be microwave closed vessel digestion. Be sure that the vessels do not open during the process to release the excessive pressure or you will loose the volatile elements. Some manufacturers equip their microwave ovens with vessels that open when the pressure inside reaches certain level. This prevents the vessels from explosion but volatile elements are lost. When developing the digestion program, start with lower sample weight and see what pressure is inside the vessels. If it is significantly lower than the vessels specification increase it a little bit until you find the optimum between instrument detection limit, vessels maximum pressure and sample homogenisation

Different dry and wet digestion methods could be used

Also microwave assisted method also used