Limitation of UV-Vis Absorption Analysis for Determination of Aqueous Colloidal Fullerene (nC_(60)) at High Ionic Strength

摘要

The Ultraviolet (UV) absorbance method is being widely used for the determination of the aqueous colloidal form of fullerene (nC_(60)) concentration. The objective of this study is to investigate whether the method is reliable with existence of ions and under high ionic strength conditions. The concentrations of nC_(60) with electrolytes are analyzed using both UV absorbance and a total organic carbon (TOC) analyzer for comparison. The results show that the UV absorbance considerably decreases with the increasing ionic strength due to the scattering in such condition, while the TOC values are relatively stable. Consequentially there was deviation between UV-converted concentration values and TOC-measured concentration values. Our results suggest that UV absorbance method may underestimate the aqueous concentration of nC_(60) under certain circumstances where the ionic strength effect is a common occurrence. Thus, the predicted mobility of nC_(60) based on the UV absorbance may be overly optimistic under such conditions, and the TOC measurement may be an alternative or a supplement.