Study And Application Of Monolithic Stationary Phases In Ion Chromatography (IC)

In recent years, ion chromatography (IC) has been further developed in some new research fields:fast & ultra-fast analysis; new stationary phases with higher efficiency and better selectivity; miniaturization of the whole system. For these progresses, the monolithic stationary phases have possessed key position with the special advantages like ease for preparation and modification, low flow resistance and attractive hydrodynamic characteristics, etc.Silica-based monolithic column coated with surfactant was used for pharmaceutical analysis in traditional IC. The process and mechanism of coating with good reproducibility and stability were studied. Due to the low pressure under a higher flow rate, the coated column can be applied for fast separation and determination of anions and ionized compounds in drug samples.Reactive continuous rods of macroporous poly (glycidyl methacrylate-co ethylene dimethacrylate) have been prepared by "in-situ" copolymerization of the monomers in the presence of porogens. Different sizes of anion-exchange monolithic columns (traditional ones 4.6 mm I.D. and capillaries 530 & 320μm I.D.) were obtained by the modification of the matrix with trimethylamine. With the optimized reaction conditions, these columns were used for separation of anions in commercial & capillary IC system; respectively. The GMA-based matrix also can be modified with sodium sulfite for cation-exchange column that can be used in capillary IC for the separation of cations by flow rate gradient elution. Based on the above techniques, quaternary ammonium functionalized latex was applied for the preparation of anion-exchange capillary monolithic column. With the optimized chromatographic conditions, the latex-coated column was used for separation of common anions.A novel capillary IC system was established composed with a LC pump (flow rate lower toμL/min), micro injector with a 500 nL injection volume, a prepared capillary monolithic column and different detectors. With a capillary UV detection cell, anions and cations were determined by direct or indirect UV detection, respectively. Two kinds of conductivity detectors-contact conductivity detector and the contactless one, were introduced into the system for determination of ions. It's compared and evaluated with different detection ways as well as the whole micro-IC system, which was successfully used for analysis of real samples such as water samples and milk powder samples.