sentences:  Following are the materials which are commonly used for porous gel beads in size exclusion chromatography 
  
  In real-life situations, particles in solution do not have a fixed size, resulting in the probability that a particle that would otherwise be hampered by a pore passing right by it.Also, the stationary-phase particles are not ideally defined; both particles and pores may vary in size.Elution curves, therefore, resemble Gaussian distributions.