Isolation and Characterization of Metalloporphyrins from a Heavy Crude Oil by Soxhlet Adsorption Chromatography and HPLC-SEC

Element speciation analysis of petroleum and related materials

“…47,48 An alternative to the SARA method is the sequential Soxhlet extraction. 27,45,49 Crude oil is first dissolved/diluted with CH 2 Cl 2 , and mixed with alumina powder. Extractions are sequentially performed with acetonitrile (a deep red coloured fraction), methanol (orange coloured fraction), n-heptane (brown coloured fraction) and benzene (dark fraction).…”

“…The benzene extract accounted for 50% of metals. 49 As it did not absorb in the UV, the metals were supposed to be present in the form of nonporphyrin species. The recovery of the procedure was reported to exceed 96%.…”

“…The elution from a silica gel column by changing/increasing the polarity from hexane to methylene chloride or methanol could separate the vanadyl porphyrins 61 from the nickel porphyrins. 24,49,62 The more polar vanadyl porphyrins could be purified further on an alumina column 27,52 or on a thin layer plate 15,24 by elution with methylene chloride. Fig.…”

“…This technique was widely used because it does not need any particular sample preparation and allows the fractionation of heavy oil fractions. 19,29,49,63 The analysis of fractions can also attempt a more detailed characterization of the species, e.g. by GC-AED.…”

Fractionation and speciation of nickel and vanadium in crude oils by size exclusion chromatography-ICP MS and normal phase HPLC-ICP MS

“…3,[20][21][22] Reversed-phase HPLC with UV detection has been routinely used for the separation of metalloporphyrins. 12,14,23 Curiously, the coupling of HPLC-ICP MS, which is now established as the principal tool for speciation analysis owing to its high sensitivity, isotopic specificity, multielement detection capability and versatility, 24 has not, to our knowledge, been successfully applied to petroleum samples. 9 The likely reason is the poor compatibility of ICP MS with the nonpolar organic mobile phase such as xylene, required in chromatography of petroleum samples.…”