The microbiology lab screens all blood donations for a range of different infectious diseases (including Hepatitis B, C and E, HIV, HTLV, and syphilis) on either an Abbott Architect i2000SR or a Roche Cobas 6800 analyzer. In addition, about 25,000 antenatal samples each year are screened for similar diseases as well as immunity to Rubella.
After testing, these samples are frozen and then stored at below -25 deg C. The samples are stored for up to 2 years just in case investigation is required on a transfusion suspected of an associated infection transmitted in a blood component.
Up until the PathFinder 350A units were installed, samples were archived in 96 well microplates, which were covered by an adhesive microplate cover. These were tedious to prepare and required a lot of paperwork for each batch of plates to be archived.
But the main issue with the prior method of storage was the uncertainty over the integrity of the sample. Once the sample was transferred to a microtitre plate, its positive sample identification was lost. What’s more, it wasn’t possible to detect any errors in the transfer process. There was also the real possibility of cross-contamination of adjacent samples in the microplate, either in the transfer process or during recovery of the sample after freezing.