A CCD SYSTEM FOR UV IMAGING OF BIOMOLECULES

An imaging system based on a cooled scientific grade charge coupled de vice (CCD) is under development for the imaging of biomolecules such a s amino acids and proteins. The CCD has been incorporated, along with a deuterium lamp, into a vertical electrophoresis unit to allow UV ima ging of separated biomolecules. The UV absorption of the various elect rophoretic materials has been measured over a range of wavelengths, in dicating that the optimum imaging wavelength lies between 260 and 280 nm. At these wavelengths, the CCD displays a quantum efficiency (QE) o f around 12%. Measurements of system noise indicate that this QE figur e is sufficiently high to allow signal changes of a few hundred photon s to be measured, allowing very small amounts of the biomolecular mate rial to be identified, The spatial resolution of the system, at around 30 mu m, is an order of magnitude higher than the current imaging sys tems. We show how this will dramatically reduce the time required for accurate analysis of biomolecular fragments.