SPADA Meeting Book

the soil prior to these types of experiments. During the laboratory experiments and 546 evaluations, multiple soil matrixes could be tested in order to evaluate a range of possible 547 conditions that could impact detectors or assays. Field experiments are specific to 548 understanding what could happen after a release and tend to focus on one soil matrix. 552 method or system will depend on the method or system being tested. General guidance 553 includes testing a minimum of three replicates of each sample and including positive and 554 negative controls. Laboratory experiments also need to include multiple soil types. It is 555 recommended to test at least 5 different soils with the varying characteristics listed in 556 Table 1. Online resources, such as the web soil survey (Table 2), provide tools to search 557 for locations to collect the various soils with the desired approximate pH, clay content 558 and organic content. Academic institutions with soil science departments may also be 559 useful in obtaining specific soils (Table 2). 560 Prior to experimentation using a soil matrix as a testing variable in a laboratory 561 environment, pH, water content, water holding capacity, organic carbon content, texture 562 and CEC of each soil should be measured. Other characteristics that may affect the 563 experiments should also be included. If it is important to start an experiment quickly after 564 sample collection, then soil pH and water content should be measured immediately, and 565 the remaining characteristics measured at a later time. Soil pH and dry weight should be 566 monitored during the course of the experiment as these could affect the performance of a 567 biothreat agent detection method or system. If a soil is too moist, the soil can be dried to a 568 549 550 551 10.1 Laboratory Test and Evaluation Set-up The laboratory experimental set-up for testing and evaluating a biothreat agent

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