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AWWA WQTC69424
- LT2 Laboratory Demonstration of Improved Method 1623 Recovery and Better Microscopic Detection of Cryptosporidium Oocysts
- Conference Proceeding by American Water Works Association, 11/01/2008
- Publisher: AWWA
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The Long Term 2 Enhanced Surface Water Treatment Rule (LT2) requires source watermonitoring with samples analyzed by laboratories demonstrating competence withMethod 1623: Cryptosporidium and Giardia in Water by Filtration/IMS/FA (EPA 2005).Method 1623 is a performance-based method and modifications may be incorporated tolaboratory procedures after successful testing of the variation. Interferences during theimmunomagnetic-separation (IMS) and microscopy steps of the method, such assuspended particles and associated constituents, may reduce the recovery of (oo)cysts.The subject studies suggest that these effects can be mitigated by the following: removingmagnetized particles from the sample; rinsing the captured microbes with phosphate-bufferedsaline (PBS); and, dissociating microbes from the magnetic beads with heatrather than acid. Acceptable performance of these modifications has been demonstratedat the U.S. Environmental Protection Agency (USEPA), Technical Support Center inCincinnati, Ohio with documented accuracy and precision, and results compared withmore than 50 other LT2 laboratories. Includes 4 references, tables, figures.