OWML: QA/QC

Quality Assurance/Quality Control Manual: Ohio Water Microbiology Laboratory

Microscope
There are two Zeiss microscopes used to perform microscopy.  The Zeiss Axio Imager microscope has the capability to perform fluorescence microscopy and differential interference contrast (DIC).  Additionally, it is equipped with a digital camera.  This microscope is used for specialized laboratory work and for enumerating Cryptosporidium oocysts and Giardia cysts by USEPA Method 1623.  The microscope has three objectives:  20X, 40X and 100X (oil), as well as an ocular micrometer.  Furthermore, the microscope is equipped with excitation/band-pass filters for the immunofluorescence assay (FA) and 4’, 6-diamidino-2-pheylindole (DAPI) analysis. The microscope also has optics for DIC analysis under the 100X objective.  It is kept in a room capable of being almost completely darkened.

The older Zeiss microscope is used for general laboratory work, Gram Stains, and Actinomycetes analysis.  It is equipped for fluorescence microscopy, so it can also be used to enumerate Cryptosporidium oocysts and Giardia cysts, if necessary.  It has five objectives:  10X, 25X, 40X, 63X and 100X (oil), as well as an ocular micrometer.

• The mercury bulb power supply for the Zeiss Axio Imager has an automated timer to monitor the number of hours the bulb has been on.  After 150-200 hours, the mercury bulb should be changed.  Note: the maximum life expectancy of the bulb is 300 hours.  Call the manufacturer’s local representative or a professional company for assistance.  The bulb must be disposed of in accordance with legal regulations, not in domestic waste.  Contact the Carl Zeiss microscopy service for assistance.  Record the mercury bulb number and date of installation in the LIMS.
   
• The mercury bulb power supply for the older Zeiss microscope has a log book to record the number of hours the bulb has been in use.  As explained above, the bulb should be changed after 150-200 hours and the appropriate information recorded in the LIMS.
   
• The ocular micrometer is calibrated for each objective at the time of purchase of the microscope by the manufacturer’s local representative.  If a new objective is purchased for the microscope, the micrometer will need to be calibrated for this objective.

The cleaning procedures are the same for both microscopes.

• The microscope is cleaned by a professional company yearly.  Record this maintenance in the LIMS.
   
• After each use, clean the objectives and stage with lens paper and lens cleaner.   A Q-tip and lens cleaner can be used to help remove oil from the end of the objective, as well as keep the oculars clean.  Keep the dust protection cover on the microscopes while not in use and let the lamp housing cool before putting on the cover.
   
• As needed, blow dust off of the microscope (especially the condenser, field aperature, and the oculars) with compressed air.