We will be spiking the whole blood (WB) with a known sequence of known length. We want to check the recovery of that particular fragment of DNA from its respective plasma using a standard cell-free DNA (cfDNA) isolation kit (QiaAmp in my case). I am interested particularly in

• Any prior processing of synthetic DNA before spiking into WB ( as we know that cfDNA are bonded to some complexes in WB)
• Type of blood used for spiking: Healthy blood, blood from a blood bank, or composite blood ( two or more blood samples are mixed)
• Any laboratory conditions such as mixing protocol, temperature, incubation time