The highly regarded International Air Transport Association (IATA) guidance for infectious substances (Packing Instructions 602) and diagnostic specimens (Packing Instructions 650),1 for example, states that each package must contain a primary and a secondary container; both of which must be leakproof and at least one of the containers needs to pass a 95 kPa (13.8 PSI) pressure test.
These regulations for the transport of potentially hazardous substances are designed to ensure that samples reach their destination in good condition and do not present a hazard to those handling the package along the way.
Leakproof containers
Owing to the unknown nature of a patient sample, it is imperative that the container used is suitable for its intended purpose and provides peace of mind that valuable and potentially infectious material will not leak as it is transferred from one location to another. This is extremely important to ensure the safety of clinicians, biomedical scientists and anyone else who may handle the sample.
Safer storage and transportation of samples has been central to the development of Sterilin single-use containers. Sterilin was the first company to offer ‘flow seal’ technology for leak-free medical sample containers to give assurance of total sample containment during use. The seal is manufactured from a non-toxic elastomer, which gives excellent performance – even with repeated use. These leakproof containers are available with either plastic or metal screw caps for volumes from 30 mL to 250 mL.
To ensure the sealing properties of the containers, the stringent quality control process for each product and its component parts involves routine leak testing to ensure that they adhere to the required standards (EN 14254 Medical Specimen Containers for Microbiology Annex D).
95 kPa pressure compliance
When transporting potentially infectious samples by mail, it is important to take every precaution to prevent exposure to the contents. Therefore, the packaging must comply with the necessary transport regulations, such as those recommended by the International Civil Aviation Organization (ICAO) and IATA.
The guidelines for testing inner receptacles in accordance with Section 1.1.6 of the ICAO Technical Instructions (IATA 5.0.2.9) state that “packaging for which retention of liquid is a basic function must be capable of withstanding, without leakage, an internal pressure which produces a pressure differential of not less than 95 kPa (not less than 75 kPa for liquids in Packing Group III of Class 3 or Division 6.1), or a pressure related to the vapour pressure of the liquid to be conveyed, whichever is the greater”.
A pressure of 95 kPa is 0.95 bar (1 bar is equivalent to atmospheric pressure at sea level). An increase of a further 95 kPa in a container is therefore equivalent to almost twice atmospheric pressure – about the same as that used in a pressure cooker.
Now, in addition to offering a range of leak-free containers, Sterilin is the first company to offer a range of 95 kPa-complaint containers that satisfy the internal pressure differential test requirements of the Department for Transport (DfT), the ICAO and IATA.
95 kPa test method
Sterilin 95 kPa-compliant containers are tested and certified to withstand an internal pressure differential of 95 kPa without leaking, which means that they comply with transportation requirements and allow the safe transportation of biological samples through the post without risk of spillage or leakage.
In order to validate a container as able to withstand an internal pressure differential of 95 kPa, a small hole is made in the container wall and a nylon tube is glued into the base using an epoxy resin. The container cap is applied manually to a standard tightness (8 lb. ins) with the aid of a torque meter, and the sealed container is left for 24 hours before testing.
The test involves increasing the pressure inside the container by 95 kPa, applied over a one-minute period, and then the pressure decay is monitored by the apparatus over a further five-minute period. Replicate tubes are tested at 23°C in order to demonstrate that the Sterilin 95 kPa range is compliant with the regulatory requirements.
The 95 kPa-compliant product range includes Sterilin 30 mL polystyrene universals and Sterilin 60 mL polystyrene containers with metal caps. Each of these is available with printed, plain or no labels, depending on individual need.
Premium quality
In addition to these important performance characteristics, Sterilin single-use containers are also renowned for quality. Sterilin plastics are manufactured aseptically in order to protect samples from contamination. The term ‘aseptic’ refers to the methods and procedures of manufacture that are designed to prevent the access of living or dead bacteria, fungi, viruses and other biological agents, so that products or work areas are maintained in a germ-free condition.
The containers are injection moulded at such high temperature (250ºC) and pressure (150–180 bar) that they are biologically sterile when they are released from the mould. They are then transported by conveyor belt in a controlled atmosphere, achieved using laminar air units and high-efficiency particulate air (HEPA) filters, prior to assembly and packaging carried out in a Class 10000 cleanroom.
This method of manufacture negates the requirement for terminal sterilisation of products. However, if this is a customer requirement then Sterilin can also offer sterile-validated products.
Reference
1 IATA Dangerous Goods Regulations (DGR) 51st edn (www.iata.org), 2010.
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