Can you please help me out with my problems?

1. I prepared carbon dots from biotic materials and wants to determine the Quantum yield, I prepared a 1mg/ml quinine sulphate solution in 0.1 M sulfuric acid. Can I just assume that both solutions have 1.33 refractive index and take absorbance of both solutions or intensities and use the values in the quantum yield equation?

my carbon dots is a clear liquid with some having characteristics color, how do I determine the concentration of the carbon dots?

Thank you very much.