Free iron in cells can react with O₂ to produce superoxide, peroxide and hydroxyl radicals known as Reactive Oxygen Species (ROS).  Remarkably, the cell has a free iron pool known as the Labile Iron Pool (LIP) that supplies iron to requiring enzymes. Measurements of the LIP range between 0.1 – 10 micromolar and are often measured via a fluorescence assay known as the Calcein Assay. Calcein is added to cells and binds Fe²⁺, quenching fluorescence. Then a specific Fe²⁺ chelator is added, and the increase of fluorescence is attributed to cytosolic Fe²⁺.  We propose that if ferritin releases Fe²⁺ during this cellular assay, the LIP will show an artificially high iron content. I report in vitro reactions of Calcein and ferritin in the presence of physiologically relevant reducing agents to determine how much iron is released from ferritin under conditions similar to the cellular assay.