PT Tube / Pro PT Tube Tube info. It aims to obtain plasma specimen for coagulation function test, it contains buffered sodium citrate solution with the concentration of 3.2% (0.109mol/L).The mixing ratio of blood to sodium citrate is 9:1. Shelf Life 3-6 Months ( Normal PT Tube ) 3-6 Months ( Plasma Coated Pro PT Tube ) Tube Material GLASS – PLASTIC Cap Color Blue Cap Color Invert the tube from 3-4 times Gently Available Sizes