Some of the color tubes that phlebotomists use include additives, which are blue for sodium citrate, green for heparin, lavender for EDTA and grey for sodium fluoride, notes University of California at Davis Health Department. Other tube colors include red, yellow, gold and black.
Phlebotomists must draw blood using the tubes in a specific order to prevent any cross-contamination among the different additives, states the University of Utah. One common tube sequence is yellow, light blue, red, red-gray, dark green, light green, lavender, light yellow and gray. The yellow tube is used for a blood culture, while the red tube is used for blood draws that do not need additives.