I am currently using DHR as a surrogate for LDL, in terms of determining the functionality of HDL in oxidization of LDL. I am have a TON of problems obtaining consistent data, even between control runs. I have discovered it is important to make fresh buffer and use a new aliquot of DHR for every run, but beyond doing that I am not sure what else to try to stabilize my assay. I have attached a table that shows the control data I have been getting over the last few weeks and the absolute values are all over the place. I have not changed any part of the assay or protocol other than doing serial dilutions of DHR and HDL to determine the best concentration pairs. In addition, when I attempt to run the assay with heparinized samples, the control slopes in those runs are not similar to values I have gotten when performing a standard curve with only controls and no samples.