Resin bead micro-UV-visible absorption spectroscopy.

The construction and design of a microscope coupled with a miniature UV-vis spectrometer is described. This was applied to the study of dyes linked to solid supports and displayed good correlation in spectral shape and lambda(max) values when compared to the dyes in solution, as well as showing a linear relationship between dye loading and UV-vis absorbance. The spectral profiles of these dyes at various pH's were measured and used to determine the pK(a) of the dyes on the beads, which were compared with the pK(a) values of the dyes in solution, thus enabling the dye-loaded beads to act as pH sensors.