Simplification of heavy matrices by liquid-liquid extraction: Part I -How to separate LMW, MMW and HMW compounds in maltene fractions of V, Ni and S compounds

A method using liquid-liquid extractions has been developed for matrix simplification and evaluated by gel permeation chromatography hyphenated with inductively coupled plasma and mass spectrometry (GPC ICP MS). In this method, maltenes were dissolved in n-heptane (HEP), and extractions with methanol (MeOH), acetonitrile (ACN) and dimethylformamide (DMF) were performed. The extraction with ACN is more efficient than that of MeOH for the removal of compounds with LMW containing V (our reference element) and more selective than that of DMF (with this solvent, compounds with LMW and MMW are extracted). Thus, a sequential extraction was performed by applying ACN to selectively remove LMW compounds, followed by extractions with DMF in the resulting maltene to separate the MMW compounds from the HMW compounds remaining in the final remnant maltene. The results show, for the first time in the literature, that it is possible to separate the three V and Ni species of compounds present in maltenes based on their mo...