Development of a high-pressure asher focused microwave system for sample preparation

The development of high-pressure Asher focused microwaves (HPA-FMs), a novel approach to microwave assisted digestion, is described. The system uses focused microwaves, at 2.45 GHz, to improve digestion capability with up to 650 W microwave power concentrated into six quartz pressure vessels containing samples and nitric acid. The device combines microwave heating with high-pressure vessel technology (reactions can be conducted at pressures and temperatures up to 130 bar and 320 °C, respectively). Methodology was developed using powdered biological reference material. The residual carbon content of digested bovine liver sample was determined by Coulometry after combustion in an oxygen stream to evaluate the effectiveness of the decomposition procedure. With this new decomposition device, organic material is totally oxidized with nitric acid in a single-step digestion.