Method development for the LC-MS/MS determination of C60 and C70 fullerenes and their functionalized derivatives in airborne particulate matter, settled dust and soot

Abstract

Fullerenes are organic contaminants of growing concern due to their increasing use for industrial purposes, in addition to their emission by natural and anthropogenic combustion sources.Their analysis is made tricky by their unique chemical structure and their acute hydrophobicity. Thus, analytical developments are required for further environmental evaluation of their occurrence. This article presents such a development for the analysis of C60 and C70 fullerenes together with three of their functionalized derivatives in airborne particulate matter, settled dust and soot from diesel exhaust.Pressurized Liquid Extraction was performed with toluene and acetonitrile as extraction solvents, and gave mean extraction recoveries from 75% to 95% for the five fullerenes investigated.Liquid Chromatography was optimized in terms of stationary phase and mobile phase to obtain a good separation of the compounds. Optimal separation of the compounds by liquid chromatography were obtained using a C18 stationary phase and a mixture of toluene - acetonitrile as mobile phase in gradient mode.The mass spectrometry detection method was also optimized with a comparison of three ionization sources: Electrospray ionization (ESI), Atmospheric Pressure Chemical Ionization (APCI) and Atmospheric Pressure PhotoIonization (APPI). APPI gave the most sensitive and repeatable detection with instrumental limits of quantification (LOQ) down to 10 pg injected. MS/MS was used in pseudo-MRM mode to enhance signal intensity.The optimized LC-APPI-MS/MS method was then validated and applied to indoor PM10 and household dust samples, and to a Diesel Particulate Matter Reference Material. None of these samples showed concentrations of fullerenes above the method quantification limits.