Increasing the sensitivity of asymmetrical flow field-flow fractionation: Slot outlet technique.

A new enrichment approach is described to improve the sensitivity of the asymmetrical flow field-flow fractionation, with and without ICPMS online coupling for elemental detection. For the slot outlet technique, a part of the laminar carrier stream is removed through an additional pump. This allowed an enrichment of the colloidal particles in the separation channel up to a factor of 14. Additional improvements of the separation efficiency permitted us to separate colloids with differences in their molecular masses of only 2 kDa. Different polymer standards, proteins, and synthesized tracer colloids, as well as real samples (wastewater, liquid manure, serums) were used to assess the performance of the new technique.