Electrophoresis Electrophoresis (ELP) is used for separating out the globulins and is required for determining which globulins are comprising the globulin fraction. Serum is the preferred sample, as fibrinogen in plasma samples can mimic a monoclonal gammopathy when elevated, and often obscures changes in other beta or gamma globulins. ELP can also be performed on body fluids such as peritoneal or pleural fluid, CSF and urine. ELP on peritoneal fluid is often performed as an ancillary diagnostic test for FIPV infection. A gamma globulin % of > 32% or total globulins > 50% in peritoneal or pleural fluid is highly predictive of FIPV infection. CSF electrophoresis is performed rarely to assess for intrathecal globulin production. Urine electrophoresis is performed as an ancillary diagnostic test for detection of Bence-Jones proteins (see below). Because of low protein concentrations, both CSF and urine often require concentration for ELP, therefore submission of large volumes (> 5 ml) is required for these tests.