Answer:
Drawing a purple top tube, which typically contains the anticoagulant EDTA, before a green top tube, which typically contains the anticoagulant heparin, could potentially result in a falsely elevated potassium level. This is because EDTA can cause the release of potassium from red blood cells, leading to a falsely high potassium level in the plasma or serum. Therefore, it is important to follow the proper phlebotomy order of draw when collecting multiple tubes to avoid contamination and errors in laboratory test results.