Hemoglobin exists in different forms, each of which contains a certain amount of iron. Hemoglobin can be found in human blood in two forms - reduced hemoglobin (oxyhemoglobin) and deoxyhemoglobin. Reduced hemoglobin is bright red in color and is capable of carrying oxygen in tissues. When the blood is saturated with oxygen, iron combines with oxygen to form oxyhemoglobin, which has a bright red color. Deoxyhem also contains iron, but without bound oxygen.
In case of quinine poisoning, an excess number of red blood cells (erythrocytes) is produced. During this process, additional iron atoms are formed and attached to one of the electrons in the hemoglobin of red blood cells. This leads to the fact that the iron metal in hemoglobin acquires a high voltage, it becomes more concentrated