An apparatus for characterising a biomolecule, the apparatus comprising a sample inlet channel configured to introduce a sample fluid including the biomolecule to the apparatus; an auxiliary inlet channel configured to introduce an auxiliary fluid to the apparatus; a distribution channel in fluid communication with the sample inlet channel and the auxiliary inlet channel; wherein the distribution channel is adapted to generate a lateral distribution of the biomolecule; a measurement module configured to detect a signature profile of the biomolecule to obtain a measured dataset of the detected biomolecule; wherein the measured dataset includes one or more of the following: auto fluorescence background measurements, flow profile, concentration, stoichiometry interactions, molecular weight of interacting biomolecules, total ligand concentration, binding sites, size, charge, modification such as post translational modification and/or the hydrodynamic radius; a storage location configured to store and maintain a stored dataset comprising a plurality of parameters that are associated with the measured dataset obtained from the measurement module; and an analysis module configured to receive the stored dataset from the storage location and correlate the stored dataset with the measured dataset from the measurement module to provide a correlation value, wherein the analysis module is further configured to use the correlation value to determine at least two characteristics of the biomolecule simultaneously using Bayesian analysis; and wherein the at least two characteristics are the concentration and the affinity or avidity of the biomolecule. a sample inlet channel configured to introduce a sample fluid including the biomolecule to the apparatus; an auxiliary inlet channel configured to introduce an auxiliary fluid to the apparatus; a distribution channel in fluid communication with the sample inlet channel and the auxiliary inlet channel; wherein the distribution channel is adapted to generate a lateral distribution of the biomolecule; a measurement module configured to detect a signature profile of the biomolecule to obtain a measured dataset of the detected biomolecule; wherein the measured dataset includes one or more of the following: auto fluorescence background measurements, flow profile, concentration, stoichiometry interactions, molecular weight of interacting biomolecules, total ligand concentration, binding sites, size, charge, modification such as post translational modification and/or the hydrodynamic radius; a storage location configured to store and maintain a stored dataset comprising a plurality of parameters that are associated with the measured dataset obtained from the measurement module; and an analysis module configured to receive the stored dataset from the storage location and correlate the stored dataset with the measured dataset from the measurement module to provide a correlation value, wherein the analysis module is further configured to use the correlation value to determine at least two characteristics of the biomolecule simultaneously using Bayesian analysis; and wherein the at least two characteristics are the concentration and the affinity or avidity of the biomolecule. <EOS>