Novel ways of increasing the performance of the stationary phases for ion chromatography — ASN Events
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Novel ways of increasing the performance of the stationary phases for ion chromatography (#53)

Alexandra Zatirakha 1 , Olga Shchukina 1 , Alexey Loshin 1 , Alexandr Smolenkov 1 , Pavel Nesterenko 2 , Oleg Shpigun 1
  1. Lomonosov Moscow State University, Moscow, Russia
  2. Australian Centre for Research on Separation Science (ACROSS), University of Tasmania , Hobart, Australia

The development of the efficient and selective anion exchangers remains one of the most important tasks in modern ion chromatography (IC). The chromatographic performance of the anion exchangers depends on various parameters including the type and the porous structure of matrix, the particle size and the particle size distribution, the type of the functional group and the bonding chemistry. In the present work novel methods of obtaining the high performance anion exchangers for IC based on silica and polystyrene-divinylbenzene (PS-DVB) matrices are proposed.

Both approaches include the moving of functional sites away from the matrix surface. In case of polymeric matrix this step is combined with hydrophilisation of the spacer, functional group or both, which helps to eliminate non ionic interactions of polarisable anions, such as nitrite, nitrate and bromide, with the aromatic rings of the matrix and also leads to the improvement of separation selectivity as compared with traditional trimethylammonium functionalised resins.

In case of silica matrix the proposed method includes the covalent modification of silica surface with amino polymers through the long spacers, which also helps to eliminate the impact of the active silica surface and its porosity. Such an approach also provides the advantage of the obtained resins over the well-known polyelectrolyte anion exchangers, which is higher stability of the covalently attached polymer layer.

The obtained PS-DVB-based anion exchangers with the particle size of 3,3 μm allow the separation of 7 inorganic anions (fluoride, chloride, nitrite, bromide, nitrate, phosphate and sulphate) in less than 10 minutes in isocratic mode with the efficiency up to 60000 theoretical plates per meter, while in gradient mode the complete separation is achieved in only 6 minutes. Novel silica-based anion exchangers (particle size – 6 μm) also demonstrate good selectivity and efficiency and allow the separation of at least 10 anions with the efficiency up to 50000 theoretical plates per meter.