ESR Tube / ESR Fast Tube info. It’s used for Erythrocyte Sedimentation Rate Test, it contains buffered sodium citrate solution with the concentration of 3.8% (0.129mol/L)..The citrate: blood ratio (according to the Westergren method) is 1:4, so the tubes contain 0.4 ml of stable 3.8% sodium citrate solution. Shelf Life 24 Months Tube Material GLASS – PLASTIC Cap Color Black Cap Color invert the tube from 6-8 times Gently Available Sizes