Ionic Stationary Phase Used In SPME And Capillary Ion Chromatography

Ion Chromatography (IC) is a conventional analytical technique for the determination of ionic and ionizable compounds. Because of its sensitive, rapid and convenient, IC has a wide range of applications in the environment, food, daily necessities, health care and other fields. With the development of modern analytical chemistry, the diversification of the sample types, it has been a new hotspot to determine the trace ions or the ions in the complex matrix. However, since the IC uses the eluents with terminal pH, which may destroy the solid phase of the pretreatment materials, there has little sample preparation methods for the IC.A simply way was proposed to prepare solid-phase microextraction fiber with cation-exchange functional coating by the thermally initiated radical polymerization of poly(butadiene-maleic acid)(PBMA) copolymer onto a silica capillary. The capacity of the fiber coating could be easily controlled by fabricating successive layers of PBMA. The performance of the fiber combined with ion chromatography was evaluated by choosing Mg2+and Ca2+as model analytes. An SPME-IC method was established. The linear dynamic range of this method was2.0-60.0ppb for Mg2+, and2.0-80.0ppb for Ca2+with good linearity (R2>0.98). Relative to direction injection,13-51-fold enrichment factors for Mg2+and Ca2+were obtained respectively. The mean recoveries for the spiked Mg2+and Ca2+in tap water were99.7and92.8%, respectively, indicating good precision of the method.A capillary monolithic column-based microscale suppressor has been developed. The monolithic column was prepared by using glycidyl methacrylate (GMA) and ethylene dimethacrylate (EDMA) as monomer and crosslinker, respectively. Then quaternary ammonium and sulphonate groups could be introduced via epoxy ring open reaction, to get OH-(anion suppressor) and H-monolithic column (cation suppressor). By optimization of synthesis procedures,450neq/cm of ion exchange capacity was obtained for anion suppressor. The microscale suppressor was evaluated by a homemade capillary ion chromatography system for the analysis of inorganic monovalent metal cations via30mM HNO3eluent. The original background conductivity of6.6mS/cm can be reduced to be1.4μS/cm (background conductance was-90nS), which was much close to that of pure water (-56nS). By such suppressor, four model cations were well separated. In addition, cation suppressor was also demonstrated much suppression effect.