The examination of scanning instruments used in electrophoresis

A simple method is described, using photosensitive paper, by which the optical performance of any scanning instrument may be assessed. The results of making such an examination of four commercial instruments are given. One instrument only was found, which, without modification, was capable of affording continuous scanning. Light scatter was found to be a major disadvantage in the transmission-type of instrument. Examination of an automatic version of a reflectance scanner suggested that the optical cover was not sufficiently discriminating for quantitative work.