Quantification of fullerene nanoparticles suspensions in water based on optical scattering

Fullerenes, and in particular the C60, have been intensively investigated in the last decades mainly because of their vast range of potential applications in biomedicine and materials science. These molecules are inherently hydrophobic, tending thus to form clusters and aggregates in polar solvents resulting in colloidal suspensions. In this work was developed a quantification method for C60 nanoparticles (nano-C60) in colloidal aqueous suspensions based on optical light scattering (nephelometry). This method can be done in a conventional spectrofluorimeter either on the excitation wavelengths or on the second-order satellite lines that arise from the diffraction gratings. The detection limit of the proposed method was about (0.0090+/-0.0008) mg L(-1), in a linear concentration range from 0.007 to 0.360 mg L(-1). A comparison of this scattering technique with spectrophotometry based on molecular absorption shows that for the former, even at the second-order lines, the threshold concentrations detected are about 20 times lower that the latter.