POSTCOLUMN RADIONUCLIDE DETECTION OF LOW-ENERGY BETA-EMITTERS IN CAPILLARY ELECTROPHORESIS

A postcolumn radionuclide detection system for capillary electrophores is (CE) is described. Eluant from an electrophoresis capillary is dire cted onto a peptide binding membrane that has been previously coated w ith a solid scintillator. The membrane is moved in a preselected patte rn relative to the fixed capillary outlet during electrophoresis. Ligh t emission from scintillation is imaged onto a charge-coupled device ( CCD) using a series of 35-mm camera lenses. Detection of two low-energ y beta(-) emitters (S-35 and H-3) not previously reported for capillar y electrophoresis is demonstrated. The separation efficiencies are sim ilar to those obtained with on-line UV detection. The response for S-3 5-labeled methionine is linear (r(2) = 0.996) from 66 amol to 11 fmol. Detection limits are 88 zmol (0.03 Bq) for P-32-labeled analytes, 17 amol (0.94 Bq) for S-35-labeled analytes, and 8 fmol (8.5 Bq) for H-3- labeled analytes.