Selection of conditions for the molecular size speciation of vanadium and nickel complexes in oil by size-exclusion chromatography coupled with inductively coupled plasma-atomic emission spectrometry

Past to Future: Application of Gel Permeation Chromatography from Petroleomics and Metallopetroleomics to New Energies Applications: A Minireview

“…THF is of great importance in petroleomics since it prevents the metals Ni and V from being adsorbed in the GPC column. 44 Also asphaltene aggregates seem not to break down in this medium according to theoretical, 45 and experimental studies, even at low concentration of 25 ppm. 46 Considering the results of the previous works, the choice of solvent and the choice of pore size of the columns seems to be the most important parameters that influence the retention times and profile shape.…”

“…A strong increase of the high-molecular weight (HMW) fraction has been observed on a THF diluted sample, hence evidencing the formation of larger Ni and V aggregates over time with an even more pronounced aggregation behavior for Ni porphyrins. As a matter of fact, it was also showed that the use of pure THF was more suitable for the analysis of these types of samples, as all components in the crude oils might not be fully solubilized in xylene which could lead to adsorption on stationary phase hence retained in the columns, as reported by De Waal et al 44 Combining these results with those obtained by Gascon et al 46 showing that, even at high dilution factor, this HMW part of the GPC chromatogram is corresponding mainly to some aggregated molecules. Gonzalez et al 71 also evidenced the formation of higher entities such as asphaltenes clusters which would originate from the association of asphaltene nanoaggregates.…”

“…Moreover, Table reveals that THF is the most commonly used mobile phase. THF is of great importance in petroleomics since it prevents the metals Ni and V from being adsorbed in the GPC column . Also asphaltene aggregates seem not to break down in this medium according to theoretical, and experimental studies, even at low concentration of 25 ppm .…”

Molecular Fingerprints and Speciation of Crude Oils and Heavy Fractions Revealed by Molecular and Elemental Mass Spectrometry: Keystone between Petroleomics, Metallopetroleomics, and Petrointeractomics

“…Thus, more material can be collected for further MS analysis of the fractions, and the identification of individual molecular species can be performed to improve the characterization in terms of the molecular size and structure. 105,106 SEC is used for the analysis of heavy fractions via element-specific detection, such as ICP-AES [107][108][109] or ICP-MS. 78,102,103,110 The analysis of SARA fractions, separated on a silica gel chromatographic column, has been performed off-line via GPC ICP-MS by Vargas et al for the quantification of V, Ni and S compounds in petroleum products (vacuum residues). The low molecular weight fractions were found to have the lowest content of highly polar compounds.…”

“…This separation technique, also known as GPC in organic applications, is very popular for petroleum analysis due to the importance of the size distribution of the aggregates on the optimization of the catalyst pore size for the hydrotreatment. ,,,, This technique also provides the characteristic size distribution profiles of the samples. , Prep-scale GPC columns allow narrow molecular weight fractions to be obtained at higher solvent flow rates and sample injection volumes than those employed in conventional GPC columns. Thus, more material can be collected for further MS analysis of the fractions, and the identification of individual molecular species can be performed to improve the characterization in terms of the molecular size and structure. , SEC is used for the analysis of heavy fractions via element-specific detection, such as ICP-AES − or ICP-MS. ,,, The analysis of SARA fractions, separated on a silica gel chromatographic column, has been performed off-line via GPC ICP-MS by Vargas et al for the quantification of V, Ni, and S compounds in petroleum products (vacuum residues). The low molecular weight fractions were found to have the lowest content of highly polar compounds. ,, …”