Monitoring the liquid/liquid extraction of naphthenic acids in brazilian crude oil using electrospray ionization FT-ICR mass spectrometry (ESI FT-ICR MS)

► Non-continuum liquid-liquid extraction of naphthenic acids at different pHs from two crude oil samples. ► The residue and the acid fraction were characterized using ESI(−) FT-ICR MS, FTIR and sulfur analysis. ► We observe a decreasing TAN in the original oil with increasing pH (7 → 14), reaching a value of almost zero at pH 14. ► The most abundant naphthenic acids extracted are those with short alkyl chain lengths (