CB (E6.1) 07/2017 Page 99/145
16.1.3 Measuring CO
2
directly with an electronic infrared measuring device
Another possible way of measuring the CO
2
concentration is by electronic sensor systems. Portable
measuring devices are suitable for measuring temperature and CO
2
concentration and can be used both
for reference measurements in certified laboratories, and for service purposes.
16.2 Temperature reference measurement
When performing a temperature reference measurement using an electronic measuring, and temperature
display device, it is important to use a device traceable to an acknowledged standards/calibration
institution (DKD, PTB for Germany) with a valid calibration certificate.
Note: The cable of the sensor must be thin enough to lay it over the door gasket of the incubator without
causing any leakages.
17. Avoiding microbial contamination
The main types of microbial contaminants in cell and tissue culture are bacteria, fungi, yeast,
mycoplasma, and viruses. This chapter gives an overview of potential sources of contamination and
precautions and measures to eliminate them.
17.1 Cells and media
• Primary cultures from the original tissue
• Cells / cell lines from unknown sources or from cell banks: Use only cells of known and tested origin.
Monitoring and routine screening of new cultures.
• Media and sera: Use only sera of known and tested origin (mycoplasma free, e.g., UV or γ radiated).
• Virus suspensions, antibody solutions etc. Use only reagents of known and tested origin.
• Laboratory instruments, media and reagents that were exposed to possible contaminated cultures
must be sterilized / autoclaved / disposed.
• Antibiotics in the cell culture media may prevent bacteria detection: Use antibiotics selectively and
economically.
17.2 Laboratory conditions / equipment around the incubator
Possible sources of contamination in the cell culture lab are airborne germs, lab equipment, building
features, and the lab personnel.
• Keep pipettes and instruments sterile after autoclaving.
• Bio safety cabinets (laminar air flow) should have a minimum of items apart from aspirator tube and
burner. Items shall be positioned within easy reach and separate from each other. Disinfect surfaces
with an alcohol-based disinfectant before and after use, clean the space underneath the bench, and
carry out regular sterility tests of the filters.
• Regular cleaning / disinfection of laboratory equipment such as a centrifuge, microscope, water bath,
refrigerator, and telephone.
• No equipment should be placed on the floor.
• Rough or humid walls are not suitable.
• Identify leaking doors and windows and make them airtight.
• Use air conditioning with special filters.
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