DETECTION OF RADIONUCLIDES IN CAPILLARY ELECTROPHORESIS USING A PHOSPHOR-IMAGING DETECTOR

A capillary electrophoresis (CE) postcolumn radionuclide detector has been developed that uses a commercial phosphor-imaging detector and ha s been optimized for low-energy beta emitters. Eluant from the separat ion capillary is deposited on a membrane. Emission from radio-active a nalytes on the membrane is integrated using the phosphor-imaging syste m for 10-72 h. Results from the phosphor-imaging system are converted to conventional electropherograms. Modifications to a prior postcolumn CE deposition system have been accomplished by adding a buffer makeup capillary; this increases the electrolyte pH range and improves repro ducibility. The limit of detection (LOD) for S-35-labeled analytes is 0.13 amol (8.7 pM or 0.007 Bq), while the LOD for P-32-labeled analyte s is 4.9 zmol (0.33 pM or 0.002 Bq), with a linear range for S-35-met from 1.5 amol to 1.5 fmol.