Abstract: Objective To focus on the main factors that may influence the stability of ethanol in blood then try to establish the best conditions for preserving ethanol in blood.Methods Four crucial parameters,including temperature(-20,4,20 ℃) ,preservative(NaF,No preservative,Na2O2) ,percentage of air chamber in container(0%,25%,50%) ,and ethanol concentration in blood(0.2,0.8,2.0 mg/mL) were investigated.Blood samples were stored under different conditions designed by orthogonal design L9(34) method.Quantification of ethanol in blood was carried out by headspace gas chromatography with FID detector.The results were statistically evaluated by analysis of variance.Result Significant changes of ethanol concentrations were observed in the samples stored in 20 ℃ without any reserveative,while there were no obvious changes in the samples under other storage conditions.Conclusion The best condition for keeping ethanol in blood stable is 4 ℃ with preservative and with 50% of air chamber in container.The temperature is main effective factor in the four factors.

Key words: blood, ethanol, headspace gas chromatography, stability, orthogonal design