Method/principle of analysis
Seven grams of salt, normally Potassium Sulphate (K2SO4), and a metallic catalyst, usually Copper (Cu) in the form of its Sulphate salt CuSO4.45H2O, are then added.
The salt is added to increase the boiling point of the acid so as to ensure full decomposition of the sample.
The catalyst is used to regulate, in this case to increase, the speed of the reaction to avoid lengthy procedures.
The samples are then placed into a digestion block which normally has been pre-heated to a temperature~420 C. Digestion is usually completed after about one hour.