No, there is no buffer restriction with FIDA. Hurra! Crude matrix like serum, plasma, fermentation media, cell lysate works perfectly fine on FIDA, which increases clinical relevance of the studies made. On top of that, as the viscosity is measured and compensate at every measurement, high percentage of viscous additive (glycerol,DMSO, PEG…) can be added to your buffer prior a FIDA measurement.