We are doing a study where we have to collect blood and then spin down the sample twice, once at a low speed and once at a higher speed. We are trying to standardize centrifuge speeds between sites, and one site's only centrifuge has fixed speeds and times, so the lowest speed that it can spin at is 10 minutes at 3,100 xg. Since we are testing cfmt-DNA, we are worried that this speed might be too high and cause destruction of the RBCs and therefore release bound mtDNA into the plasma.