选择７种水中挥发性苯系物作为研究对象，提出了两次相平衡／液上气相色谱法测定水中挥发性有机物的方法。推导了气液等体积平衡，只分析气相就可测定水相浓度的理论关系式，研制了可变相平衡器。实测水中７种挥发性苯系物的回收率在８８％～１２０％之间，相对标准偏差和相对误差小于２０％，检出限范围在２～３μｇ／Ｌ。方法可以满足环境监测的要求 Seven kinds of volatile benzene compounds in water were selected as the research object. Two phase equilibrium / liquid chromatography methods for the determination of volatile organic compounds in water were proposed. Derived the gas and liquid volume balance, only the gas phase can be measured on the determination of the concentration of the theoretical formula, developed a variable phase balancer. The recoveries of seven volatile benzene compounds in the measured water ranged from 88% to 120%, the relative standard deviations and relative errors were less than 20%, and the detection limits ranged from 2 to 3 μg / L. Methods to meet the requirements of environmental monitoring