In this part of the study, we used human whole blood and blood plasma to demonstrate the applicability of ULF NMR relaxometry for biological samples. Blood with all its components intact (white and red blood cells, platelets, and plasma, collected using a tube that contains an anticoagulant solution) is called whole blood. Blood plasma (45% of the whole blood) is the cell-free supernatant, which can be obtained by centrifuging whole blood. The high water content of whole blood and plasma allowed us to readily observe proton signals under ULF conditions.