AOAC SPADA Meeting

SOIL TESTING

• Recommendations to evaluate candidate assays using soil  samples was added to Part 2 of the Environmental Factors  appendix in 2017: • 2.2:  Soil Testing • “Airborne soil particles may constitute a significant challenge  to the analysis of collected aerosol samples by polymerase  chain reaction (PCR) assays.  Soils contain genomic materials  or nucleic acid fragments of countless archaebacterial,  bacterial, and eukaryotic organisms.  Some of the more  common soil organisms can be anticipated.  Soils may also  contain unanticipated components that interfere with  extraction, denaturation, polymerization, or annealing  reactions. Therefore, determining the effect of a variety of  representative soils on the robustness of a PCR assay is an  important first step.”  • However, instructions in the Soil Testing section are  extremely limited because  there was not a consensus on  how to conduct soil testing , nor what kinds of soil samples  to use (T&E; assay development; industry/gov’t )

WHY IMPORTANT Currently:

• Lack of uniformity for assay development and comparison of performance  across vendors for the USG

• Limited soil representations 

• Unknown soil composition as relates to bio assay performance testing 

• The community does not evaluate an assays performance using consistent  standard soil samples and standard methodology for testing

• Testing for cross reactivity and inhibition limited to the near neighbors 

• Testing interferents conducted with identified operational interferents (i.e.  diesel exhaust, sea salt, etc.) during DT, DT/OT and O