Development And Application Of Column Switching Methods For Analyzing Complex Matrices By Ion Chromatography

As an important branch of chromatography, ion chromatography has been widely used in the fields of environmental monitoring, electronic industry, food and beverage industry, pharmaceutical industry and bioscience, etc. However, with the application of ion chromatography is expanding gradually, the sample will be more complicated. Thus, the method on sample pretreatment of complex matrices is still a challenging task. However, we can solve this problem with column switch technology, for it is a strong and effective mean of sample pretreatment. In this work, different column-switch ion chromatography systems were established and applied to the analysis of complex matrices.Firstly, the concept of ion chromatography and sample preparation methods was reviewed. The chapter focused on three kinds of column switching methods and its applications in sample pretreatment by using ion chromatography.Secondly, an ion chromatography single pump column-switching system was developed for the determination of ammonium in high salt matrices. The simple system included a pump, a suppressor, two valves, two columns, a single eluent, and a conductivity detector. After the first separation in an analytical column, ammonium was collected in the2mL acceptor loop, and the majority of the matrix was eliminated. Ammonium was eluted from the acceptor loop to the analytical columns for the second separation. The proposed method achieved the accurate and precise analysis of ammonium in the sodium matrix without any sample pretreatment.Thirdly, an ion chromatography system with on-line sample pretreatment using valve-switching technique was developed for the simultaneous determination of fluoride, chloride, nitrite, bromide, nitrate, phosphate and sulfate in oils. The oil sample is a complicated sample with organics as main matrix. In this work, a polymer-based reversed-phase column NG1was used as a pretreatment column. Via valve-switching technique, sample solution with target ions were eluted from a concentrate column to analytical columns, with matrix eliminated on-line. The on-line sample pretreatment IC system was convenient and practical for the determination of inorganic anions in oils.Finally, an ion chromatography method has been proposed for the analysis of acrylic acid and p-phthalic acid (PTA) in desizing powder. The proposed method achieved the determination of p-phthalic acid which is insoluble in water using ion chromatography for the first time both at home and abroad. The method could be applied to the determination of acrylic acid and p-phthalic acid effectively and quickly.