Although most types of glass are sterilisable by either steam or dry heat, certain techniques are recommended for specific types of glass. Most USP Type I borosilicate glass is suitable, when proper techniques are followed, for sterilisation and de-pyrogenation. Type III is not recommended for repeated steam sterilisation, although this may be appropriate on a single use basis. Recommended autoclave cycles are 121°C @ 15 psi for 20 minutes. Closures should be left loose on the containers. Proper care must be given when venting back to atmosphere or there may be damage to the containers.
Dry heat sterilisation can be achieved at a temperature of 160°C for 2 to 3 hours, but glass containers are capable of withstanding sterilization temperatures up to 500°C without noticeable degradation of the glass. Repeated dry heat sterilization of containers containing a fair amount of moisture may be susceptible to glass flaking. Inversion of the container and good ventilation would prevent this from occurring. Inspect glass containers for chips, cracks and scratches before each use and discard if damage is evident, as breakage may occur during sterilization if used.
Glass containers may also be sterilized using gas or chemicals.
Ethylene oxide (EtO), formaldehyde or peroxide gas is generally used when heat and pressure cannot be used due to material limitations. Chemical disinfectants normally used are quaternary ammonium compounds, iodophors, formalin, benzalkonium chloride and ethanol.
Glass containers may also be sterilized using irradiation, however, the process changes the colour of the glass, which may not be acceptable for most applications. There is glass tubing available that will not change colour when irradiated. This would be available for those interested in large quantity orders of tubing vials only.