Nitrate Storage Stability Tests

A distinction must be made between chemical and physical stability. While physical stability is important, particularly in the evaluation of solid propellants, the chemical stability is of prime importance in the estimation of the course of decomposition of nitrate esters. The nitrate esters which are processed for use as propellants - unlike nitro compounds, which are relatively stable under these conditions - undergo a steady decomposition, which is due to imperfect purification of the starting materials and to the effect of other parameters such as temperature and air humidity. The rate of this decomposition is auto-catalyzed by the acidic decomposition products and may in certain cases produce spontaneous ignition. In order to reduce the decomposition rate as much as possible, suitable stabilizers are added to the powders, which are capable of accepting the acid cleavage products with formation of the corresponding nitro compounds (- Stabilizers). The stability is controlled by means of several tests (- Hot Storage Tests). 

The stability of the bienzymatic NaR-SODl-CNT-PPy-Pt electrode was evaluated by monitoring the current response three times a day in the presence of 100 nM nitrite and 300 nM nitrate over four weeks, and the rest of the time it was stored at 4 °C. The SODl and NaR were quite stable, as inferred from their electrocatalytical activity of 92% and 89.6%, respectively, after one month of storage and 83% and 76%, respectively, after two months of storage. RepeatabiHty of the bienzymatic biosensor was tested by... 

---