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Acidic species were extracted from heavy crude oil by alcohol-alkali solution and ion exchange resin. The acidic species in the obtained extracts and extracted crude oil were characterized by negative-ion ESI FT-ICR MS. The analytical results indicated that some class species, O2, O1, N1, N1O1, N1O2, N1S1 and O2S1 etc., were identified in the negative-ion spectrum, in which O2, O1 and N1 class showed...
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