Abstract The sorption of glycerol trinitrate to PVC bags and administration sets during intravenous infusion has been widely reported. Nitrate interactions during continuous administration using a pre-filled plastic syringe and syringe pump, connected to the injection site using a plastic extension set, are reported in this study. Losses from sorption to PVC, nylon and polyethylene tubing were compared. Factors influencing sorption were also assessed. Results showed that sorption to polypropylene syringes and polyethylene tubing were negligible, while PVC and nylon tubing sorbed GTN and ISDN. Sorption to PVC approached 90% in some instances. Losses were greatest with GTN. The concentration of ethanol influenced sorption while propylene glycol had no detectable effect. Other factors examined were drug concentration, flow rate and tube length. It is recommended that PVC or nylon extension sets should be avoided for intravenous nitrate administration using a syringe pump.