One of the most common uncertainties when starting a new assay is how to select the best fluorescent label from all of the available options.

An optimal selection is based on reviewing the spectral properties of each dye, in relation to the instrument to be used. Each instrument has features to consider such as excitation source, optical filters, and sensitivity.

The most important dye characteristics to review when choosing an appropriate dye, are absorption- and emission spectra, the fluorescence Stokes shift, the extinction coefficient, pH-sensitivity, stability to photobleaching as well as the quantum yield.