CHEMILUMINESCENCE, REAL TIME IMAGING OF MICROPARTICLES SEPARATION BY FIELD-FLOW FRACTIONATION: A USEFUL TOOL FOR PROBING RETENTION MECHANISM AT ULTRA-LOW DETECTION LIMITS

摘要

Field-flow fractionation (FFF) is a family of chromatographic-like techniques that are suited to separate and characterise supramolecular analytes in suspension, such as macromolecules, nanoparticles, colloids and micro-sized particles.' Separation is achieved, rather than by interaction with a stationary phase, by applying an external field perpendicular to the carrier flow. The origin of the field (i.e. gravitational, centrifugal, hydrodynamical, electrical, magnetical, thermal) characterises the different FFF sub-techniques. A general limitation of the FFF methods lies in the detection of eluted analytes. Detection in FFF is usually performed through UV-Vis spectrophotometry or complex light scattering detection systems, which are characterized by low sensitivity and intrinsically poor selectivity. All these detection systems usually employ flow-through detector cells that are positioned downstream the separation channel. As a consequence, real-time information on the separation mechanisms while particles are eluting along the separation channel is lacking. Chemiluminescence (CL) represents an ultra-sensitive and highly specific detection tool, which has been already applied to separation techniques (HPLC) and FIA. In addition, CL imaging has been successfully applied for the ultrasensitive localisation of analytes on plastic or biological surfaces.