SPADA Book - April 11, 2017

Technical Suggestion • While line 8 is true it is not part of the specificity  testing which should be done early on in testing.  This soil should be tested with other gold standard  methods to insure the target sequence is absent.  Then and only then can it be tested with the assay  being developed. If the assay is positive in a soil  declared negative the assay fails because it is  giving a false positive response.  Testing with the  target spiked at 2X plus a native DNA control  without soil DNA will identify the presence of  inhibitors.  

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Technical Suggestion

• DNA containing soil inhibitors can be tested at 1X  and dilutions up to 50X to overcome any inhibitor  response.  The assay could be very specific (and  sensitive) allowing field samples to be diluted  prior to testing to overcome those inhibitory  substances.  Removal of inhibitors is different than  testing for specificity and is a function of the DNA  extraction method.

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