[Columns and separation mechanism of low pressure ion chromatography]

Ion chromatography which appeared in 1975 has been developed rapidly in recent years. But the working pressure increased with years. In this work, the authors put forward the low pressure ion chromatography (LPIC) and successfully designed several kinds of low pressure ion chromatography with inlet pressure of 1.92 x 10(5)-2.94 x 10(5) Pa. Many cations, such as, alkali metals, NH4+, alkaline earth metals, transition metals, inorganic anions and organic acidic ions can be analyzed rapidly by the technique. The detectable limit of numerous ions reaches 10(-6) g/L. Low working pressure, high performance separation and highly sensitive detection can be realized by LPIC. Among these, the columns play an important part. In this paper, the kinds and species of columns and the analytes are presented. The separation mechanism of low pressure ion chromatography is discussed, which indudes ion exchange equilibrium, complexation equilibrium and ion exclusion reaction. Furthermore, the relation between the exchange capacity of ion exchange media and the concentration of eluent are also discussed. In the meanwhile, the choice of LPIC elution systems and separation conditions are described in this paper too.