辅助气燃烧接口对有机化合物碳同位素测定的影响

Influence of the Combustion Interface Using Auxiliary Gas on the Carbon Isotope Analysis of Organic Compounds

对多种烷烃及芳香化合物采用不同类型的反应管进行了碳同位素分析,旨在阐明燃烧接口对有机化合物色谱行为的影响.结果表明,在反应管中填充较少的催化剂有助于提高化合物的分离度,这可能是由于反应管中载气具有较高的线速度,从而减少了化合物的扩散加宽.然而,不同反应管对分离度的改善作用相对有限.对于不同的反应管,化合物的灵敏度变化主要与开口分流处分流比的变化有关,而这种变化可能是由反应管内载气流速的变化所致.

Combustion reactor is considered to be one of the critical factors in detecting sensitivity and resolution of organic compounds for carbon isotope analysis,yet the reasons are not well understood.This study focused on combustion reactors using additional auxiliary gas,one of the two most commonly used reactors applied in commercial instruments.Various alkanes and aromatic compounds were subjected to carbon isotope analysis with several types of combustion reactor to illustrate in detail the effects of the reactor on the chromatography of organic compounds.Relatively small quantities of catalyst packed into the reactor,which result in a high linear velocity of carrier gas and an eliminated diffusional broadening of the analytes in the reactor,could improve the peak resolutions of various compounds.However,the improvements could be gained on the peak resolutions,by various types of reactors,are limited.In comparison,the sensitivities for organic compounds might vary greatly with a number of factors,which is mainly attributed to the changes in split ratio at the open split that is closely related with the total flow rate of carrier gas in the reactor.