Abstract: Objective To develop a method for quantitative collection of exhaled gas in anesthetized dogs at given time following intravenous administration of octafluoropropane(OFP)-containing human albumin micropheres for assessing the gas kinetics of OFP.Methods OFP-containing albumin micropheres were administered intravenously at 0.4,0.8 and 1.2 ml/kg,respectively,in anesthetized and ventilated dogs.The exhaled air samples were analyzed by gas chromatography-tandem mass spectrometry(GC-MS-MS).Results The correlation curve between the area under curve(AUC)and administered dose was roughly linear(Y=1162.5X-417.38,r2=0.949 9).The total recovery rate was(119.49±27.62)% which was not significantly different from the rate of 100%(P>0.05).GC-MS-MS was accurate,sensitive,precise and applicable for OFP determination.Conclusion The sampling method is useful for characterizing OFP pharmacokinetics in dogs,and also applicable for studying the pharmacokinetics of other gas-containing drugs.