sample in a cold pack or prepare a container with ice water capable of maintaining refrigerated temperatures and large enough for immersion of the barrel of the capped/sealed syringe.
Potassium is only stable for 20 minutes on ice. Longer delays will cause falsely elevated results.
Art.Blod.Gas & NA/K/Ion.Ca w/Hgb (not SCHW/DTC)
Blood Gas Art/NAKICHgb