Quantification of fullerene (C60) in aqueous samples and use of C70 as surrogate standard

With the increasing production and use of fullerene nanomaterials, it is imperative that quantitative analytical methods be developed to study their occurrence and behavior in the natural environment so that the risks posed by these materials to ecosystem and human health can be addressed. Liquid–liquid extraction (LLE) and solid-phase extraction (SPE) coupled with HPLC–UV/vis analysis were identified as efficient quantitative methods, with detection limits as low as 4.2 μg/L for C60. The addition of MgCl2 in both LLE and SPE increased the extraction recovery of C60 from 75% to 90% while humic acids and fulvic acids decreased recovery to less than 40%. Humic acid was more effective at lowering C60 recovery than fulvic acid. The recoveries of fullerenes from surface water, treated wastewater and groundwater matrices were statistically equivalent but the recovery of fullerene from seawater was >90%. A method to correct for inconsistent C60 extraction recovery using C70 as a surrogate standard was also developed.