Factors That May Cause Contamination During Filtration

2. Comment on class result with respect to differences in filter types, differences in filter assemblies, and overall on the confidence you would have in using this type of sterilisation process in preparation of pharmaceutical products. List the factors that may cause contamination during filtration. (20 marks)
Factors that may contribute to contamination:
• Not disinfecting work area
• Fibres from filter, clothing etc.
• Potential chemical release from filter, syringe etc.
• Assembly of Swinnex filter
• Incorrectly washing hands
• Touching needle or filter end
• Not covering agar plate and broth tubes before and after use
To avoid contamination as best as possible, if washing hands according to SOP1 is not possible, wearing gloves and spraying with 70% ethanol is also acceptable for the procedure. Furthermore, not touching the ends of the needle and filter are absolutely essential in avoiding contamination thus applying them to the syringe whilst the ends are still in their sterile packaging will aid the prevention of contamination. When not in use placing the syringe on its plunger creates a smaller surface area for the contaminants to attach to as well. Loosening the lids of the broth tubes before placing in the Biohazard cabinet ensures easier removal when required thus less exposure time of the opened end to the environment allowing contaminants in.
The Swinnex filter compared to the commercial filter had a higher rate of failure due to the lower number of tests done on it but the total number of contaminated plates and tubes only slightly varied from the commercial filters. This is most likely due to errors occurring in aseptic technique and the fact that Swinnex filters must be assembled in a Swinnex holder each time yo...

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8. Why is steam sterilisation used to sterilise the potassium chloride ampoules? (8 marks)
Steam sterilisation is the process where “dry saturated steam comes into contact with a cooler surface, that causes water condensation and immediate release of the latent heat” (Rohanizadeh, 2016). This process was carried out in an autoclave and is the preferred method of sterilisation as the ampoules are sealed and made from glass. Being sealed causes a high amount of pressure to build up inside the ampoule, though in an autoclave they will not burst due to the high pressure in the autoclave equalizing and compensating for the high pressure in the ampoule. If a dry heat method of sterilisation was used, e.g. an oven, the ampoules would burst due to evaporation of the solution occurring, and no compensation or equalised pressure availability, like we see in the autoclave.