Quantification of fullerenes by LC/ESI-MS and its application to in vivo toxicity assays

With production and use of carbon nanoparticles increasing, it is imperative that the toxicity of these materials be determined; yet such testing requires specific and selective analytical methodologies that do not yet exist. Quantitative liquid-liquid extraction was coupled with liquid chromatography/electrospray ionization mass spectrometry for the quantitative determination of fullerenes from C-60 to C-98. Isotopically enriched, C-13(60), was used as an internal standard. The method was applied to determine the loss of C-60 from exposure water solution and uptake of C-60 by embryonic zebrafish. The average recovery of C-60 from zebrafish embryo extracts and 1% DMSO in aqueous-exposure solutions was 90 and 93%, respectively, and precision, as indicated by the relative standard deviation, was 2 and 7%, respectively. The method quantification limit was 0.40 mu g/L and the detection limit was 0.02 mu g/L. During the toxicological assay, loss of C-60 due to sorption to test vials resulted in the reduction of exposure-solution concentrations over 6 h to less than 50% of the initial concentration. Time-course experiments indicated embryo uptake increased over course of the 12-h exposure. A lethal concentration that caused 50% mortality was determined to be 130 mu g/L and was associated with a zebrafish embryo concentration, LD50, Of 0.079 mu g/g of embryo.