Polarization, steric, and focusing micro-thermal field-flow fractionation principles, theory, instrumentation, and applications in polymers and particles analysis

The benefits of the miniaturization of the separation channel for Thermal field-flow fractionation (TFFF) are analyzed theoretically and studied experimentally. It is found that the operational variables influencing the efficiency and resolution of the separation can be optimized and that the concept of a micro-TFFF is meaningful. A miniaturized TFFF channel was proposed and constructed. It has been demonstrated experimentally that micro-TFFF allows one to carry out high-performance separations under carefully chosen experimental conditions. This new technique is highly competitive in comparison with size-exclusion chromatography (SEC) of macromolecules with molar masses up to roughly one million gram per mole. However, the versatility of micro-TFFF is superior to SEC for macromolecules of ultra-high molar masses, as well as colloidal sub-micron, and micron-sized particles of synthetic, natural, or biological origin. The free choice of the carrier liquids without any modification of the separation system affords an advantage to micro-TFFF. The experimental implementation and application to polymer and particle analysis confirmed the potential of micro-TFFF.