Dendritic Polymers as Bonded Stationary Phases in Capillary Electrochromatography

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Dendrimers are an interesting new class of polymers. Their unusual chemical and physical properties have great potential in many applications. Polyamidoamine starburst dendrimers (PAMAM-SBDs) have shown promising results as a pseudostationary phase in Micellar Electrokinetic Capillary Chromatography (MECC). However, few chromatographic applications have been explored using dendrimers. The objective of our study is to explore the potential of using poly(aryl ether) dendritic polymers as a bonded stationary phase in open tubular Capillary Electrochromatography (CEC).

The syntheses of the first generation (G1) and second generation (G2) poly(aryl ether) alcohols have been achieved in this study. The dendritic polymers can be chemically bonded onto the inner wall of a fused silica capillary column by using 3-(triethoxysilyl)propyl isocyanate as an anchoring agent. Four different bonded phases were studied: the G1 and G2 poly(aryl ether) dendrimers, a C18 alkyl chain, and 4-pyridylcarbinol. Model separations of different analytes were examined over a range of pH values with a variety of buffer electrolytes.

The suppression in electroosmotic flow (EOF) was observed using thiourea as a neutral marker. A decrease in EOF with G1 coating versus a C18 coating was obtained over the pH range 4 – 9.3. The EOF was completely suppressed when the capillary was coated with second generation of poly(aryl ether) carbamate. The permanent surface modification method in this report proved to be stable over the pH range of 4.0 – 9.3. Improved selectivity and retention were observed with polyaromatic and basic compounds.