Unstable ambient environment

Another concern with radioactive sources is the care needed to prevent chemically reactive conditions in the IMS drift tube for example, elevated drift tube temperatures in the air atmosphere and acid gases may eventually cause oxidation of the metal foil and the formation of nickel oxides or salts. These salts or oxides are mechanically unstable and may be released into the ambient environment if the drift tube is vented without a particulate filter. A paper filter fitted on the drift tube effluent will trap radioactive particulate matter. Finally, proper disposal of drift tubes equipped with radioactive sources requires permits and can be expensive. 

Oxygen is omnipresent in our environment and the deterioration of rubbers and plastics by peroxidation is the normal cause of property deterioration in most polymers under ambient conditions. Peroxidation is a free radical chain reaction, shown in summary in reactions 3.1 and 3.2. Under normal conditions it is initiated by hydroperoxides that are formed in each cycle of the peroxidation chain sequence (reaction 3.1). Hydroperoxides are very unstable compounds due to the weakness of the peroxide bond which readily undergoes thermolysis when heated (reaction 3.3). This reaction is powerfully catalysed by transition metal ions. 

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