Analytical methods utilizing energy/particle interaction assessment techniques, useful for monitoring and screening applications, including determinations of individuals suitable for inclusion in clinical trial test subjects, monitoring of the inception and progression of disease states, determinations of the character of drug/target interactions for drug discovery, determinations of best modes of therapeutic intervention in the treatment or prevention of disease and adverse physiological conditions, and monitoring of loci, e.g., environments including materials, food, air, etc., which are subject to presence or incursion of deleterious biological agents. The energy medium used in the energy/particle interaction can include laser energy, and the assessment technique can include the use of Electrophoretic Quasi Elastic Light Scattering (EQELS), Photon Correlation Spectroscopy (PCS) or Capillary Zone Electrophoresis (CZE).