Abstract: A syringe for sequentially injecting a plurality of liquids into an intravenous (IV) infusion component that has a connector fitting includes a syringe vessel having a preferably needleless injection port that is engageable with the connector fitting of the IV component. A syringe plunger is slidably disposed in the syringe vessel, and at least one barrier plunger is slidably disposed in the syringe vessel between the injection port and the syringe plunger. The barrier plunger is formed with a pathway for fluid communication therethrough, and a valve is positioned in the pathway of the barrier plunger to block fluid communication through the pathway. A nipple extends inwardly from the injection port for opening the valve of the barrier plunger when the barrier plunger is urged against the nipple. A first liquid is disposed in the syringe vessel between the barrier plunger and the injection port and a second liquid is disposed in the syringe vessel between the two plungers.