The following procedure is a first draft of the procedure used by Jim and I in an attempt to label BSA with TRITC. This is likely to be updated with photos of the procedure in the future.
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Prepare reaction buffer by dissolving 1.7g sodium bicarbonate in 200mL of water for a 100mM concentration. Begin to stir with a magnetic stir plate and dip pH meter into solution before adding sodium hydroxide slowly until pH is approximately steady at 9.
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Dissolve TRITC in DMSO at 1mg/mL
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Prepare protein solution by dissolving BSA in reaction buffer at 6mg/mL. Pipette TRITC solution into protein solution in 35uL per 1mL TRITC to protein ratio, mix thoroughly, and wrap in tin foil to chill in refrigerator with buffer for at least two hours, or overnight.
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Prepare dialysis tube in buffer by stirring until bag is opened. Pipette BSA solution into bag and seal both ends with dialysis clips. Leave dialysis to occur overnight with constant stirring.
Cool, Jess Snyder, a former Ph.D graduate from the McGrath Lab, did this a couple of years back.
Did you happen to characterize the concentration of labeled BSA that you got and the mole ratio of the fluorophores to BSA (number of TRITC on each BSA)?