MEASURING METHOD OF NONIONIC SURFACE ACTIVE AGENT

PURPOSE:To make it possible to perform accurate detection and determination of a minute amount of nonionic surface active agent, by treating a sample solution including the nonionic surface active agent alone or with a fluorescent derivative agent, thereafter separating the solution using a chromatograph system, and measuring the fluorescent light of the eluate. CONSTITUTION:Among nonionic active agents, a sample of a nonionic active agent, which emits fluorescent light by itself such as polyoxyethylene alkyl phenyl ether, is separated alone by using a chromatograph system. With respect to the agent, which does not emit fluorescent light such as polyoxyalkyl ether, a fluorescent derivative agent such as, e.g., 1-anthroylnitrile, which chemically bonds with a terminal OH of the surface active agent, is made to react with the sample solution. Thereafter, the solution is separated by the chromatograph system, and the fluorescent light of the eluent is measured. With respect to the mixture of the agent with no fluorescent light itself and the agent with fluorescent light, the agent with fluorescent light is separated and measured at first. Thereafter the fluorescent derivative is made to react with the agent with no fluorescent light and measurement can be performed. The fluorescent derivative agent is added to the mixture, and it can be simultaneously separated and the measurement can be performed. Thus the minute amount can be detected and determined accurately.