Quantification of conjugated protein?

I am working on protein labelling.I am searching for how to measure the concentration of conjugated protein.(after filtration to remove unconjugated dye). i know a correction factor is also required as protein concentration is determined at 280nm, because the dyes also absorb at 280nm.The correction factor is the A280 of the dye divided by the Amax of the dye.how can i calculate the A280 of dye in conjugate?What can I do?thermo recommend me to use 0.26 as CF,but as dye concentration will be different for each experiment, Correction factor will be different? I am looking for a precise method to calculate degree of labelling.