Determination of optimal volume
Different volumes (30, 40, 50, and 100 μL) of serum samples were left for approximately 24 hours at room temperature to air dry. Tubes with 30, 40, and 50 μL were well dried having a yellowish pellet stuck to the bottom of the tubes. Tubes with 100 μL were not completely dried. Thus, 50 μL volume of bovine serum was chosen to produce DTS panels and all subsequent testing was conducted with the DTS prepared using 50 μl volume of serum.