In general, amounts of DNA collecte

In general, amounts of DNA collected from neat saliva deposited on the four substrates appeared to be affected by the substrate,with both nonporous substrates (glass and pitted plastic) providing more DNA than both porous substrates (brick and wood). This finding was anticipated, as more porous substrates would be expected to have less DNA available on the surface. This observation was, however, unique to neat saliva and could be the result of a particular substrate–saliva interaction (which may be due to the low number of replicates tested). It is counter intuitive that this phenomenon was not observed in neat blood and demonstrates that it would be of benefit to examine the interactions different biological fluids have with a range of substrates.