The digestion system is used for destruction of organic matter in natural, waste and potable water, foodstuff and biological samples for further determination of heavy metals in these samples by other analytical methods. Apart for operations of digestion and evaporation, the analyzer also may be used for hydrolysis, extraction using polar and nonpolar organic solvents, and also for microwave synthesis. Pressure control
When heated the oxidation reagents reacts with organic matrix of the sample, forming carbon dioxide and nitrogen oxides. Intensive gas release in the beginning of digestion process makes further ashing in close vessels more difficult. Pressure increase leads to decrease of heating, and the temperature and rate of digestion process goes down. Also closed vessels can contain only a limited mass of gas that limits the total digested sample weight (for example, weight of a sample that contains carbohydrates may be not higher than 0.01mg). Minotavr-2 features pressure control module that monitors excessive gas release and automatically switches off heating for a few seconds and release excessive pressure. The digestion continues automatically at the most effective rate as soon as the normal digestion pressure is restored. Preset optimal digestion conditions and slow gas release allow avoiding sample losses during pressure release cycles. Pressure control system also allows increasing sample volume (up to 2 grams) that increase representability of the sample and leads to less strict requirements for sensitivity for further elemental analysis method, and may be used not only for atomic absorption or atomic emission methods but also for photometry/luminescence measurements. Automatic evaporation
Evaporation of liquids is important for preparation of samples and removal of excess of acids after completion of digestion (in the cases if pH value of the sample is important for further analysis). In order to avoid loss of elements due to overheating, the volume of the residue is monitored and the heating is switched off automatically upon reaching preset amount of residue. For some solutions with high salt content it is possible to evaporate the sample to dry residue. The fact that evaporation and digestion is made in the same container also leads to sample loss during sample manipulation. Safety
Minotavr-2 minimizes the consequences to the personnel of the lab from working with acids. Strong acids are not used during digestion and the vapors of nitric acid are removed by the scrubber to a collector. The container with sample at high pressure is placed into a titanium protective shell with gas release channels. The container may be extracted from the system only after full pressure release. At the same time, pressure control module allows to achieve the optimal digestion temperature even at relatively low pressure (8 atm). Protection form microwave field is ensured by a special wave guide system that exclude possible leaks out of the microwave module and meets safety requirements in all the operation modes of the system. | 
