Although the requirement to protect operators is

not currently fully implemented in various labora- tories using open class II hoods, it is gradually becoming more enforced and should be taken into consideration when automating the process.

Going beyond standards Of course, to ensure a system has a reliable class II classification, it should be tested to comply with standards – in this case BS EN12469-2000 and ANSI/NSF49. These standards dictate the perfor- mance and testing criteria with which the systems should comply. Enclosures should produce a lami- nar airflow across the deck of the workcell. However, it is important to note that while an empty workcell may achieve this, the addition of robots and instrumentation will disrupt this signif- icantly.While compliance with BS EN 12469-2000 is enough on paper, automation system providers should also understand this and test systems accordingly. It is also wise to look for systems cer- tified by a nationally-recognised test laboratory such as ETLus in the US. Systems are tested to BS EN 12469-2000 by

measuring various air velocities, particle counting and tracer visualisation to meet the class II require- ments. However, careful consideration of the loca- tion of equipment inside the system is also impor- tant (Figure 2). This is because, as mentioned, instrumentation such as stacked equipment can result in poor airflows and disrupt the laminar air- flow potentially causing stagnant pockets of air –

Figure 2

Placement of equipment inside workcells is an important

consideration as it can disrupt laminar flows and cause

pockets of stagnant air, risking contamination

not ideal if these form over an unlidded sample plate. To protect against this, systems should be tested with smoke trace profiling and for cleanli- ness using particle counting around the system. Of course, contamination must be avoided at all

costs and so it follows that cleanliness must be maintained within the workcell. Therefore, equip- ment layouts must also consider maintenance of equipment and spill points, etc. When working with multiple cell lines, the ability to chemically deep clean the system is critical. UV sterility offers minimal effectiveness within large automation sys- tems due to the wavelength of UV compared to the size of the system and associated shadow effects. For this reason, some systems allow for vaporised hydrogen peroxide cleansing which is a valuable benefit.

Flexible designs that achieve security It is clearly important then to select and install an automation system that will provide both product and operator protection. However, a system also needs to be easy to work with. Inevitably, there will be the need to access instruments inside the work- cell when cells are in situ – for example to replace a seal on a plate sealer or reagents for a dispenser, or even just to add sample plates or additional lab- ware. So there has to be adequate protection in place for this. For example, it is not uncommon during cell line

development for cells to be incubated for a month to six weeks to achieve the required outcome.


Drug DiscoveryWorld Summer 2019

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