Estimating molecular masses of petroleum-derived fractions: High mass (>2000u) materials in maltenes and asphaltenes from Maya crude oil.
Molecular mass ranges and average masses of fractions from a heavy Mexican crude oil (Maya) have been studied, using mainly size exclusion chromatography (SEC) and laser desorption-mass spectrometry (LD-MS). Method development focused on the use of planar chromatography and size exclusion chromatography (SEC), to isolate narrow bands of material from solubility-separated fractions of the crude oil. The procedure provides a planar chromatography based method for studying mass ranges in complex hydrocarbon mixtures. It allows the calculation of 'best estimate' values for number and mass-averages. These can then be used in average structural parameter (ASP) calculations, for studying structural features of the samples. The method is applicable to both coal and petroleum-derived samples. The molecular mass estimates arrived at in this work for petroleum-derived samples are considerably higher than those reported by other workers for similar samples. The results presented here provide strong evidence for the presence of ions approaching m/z 10,000 in the Maya asphaltene. The maltene fraction was found to contain a small amount of ions with mass (m/z) in excess of 2000.
Morgan
T J
TJ
Department of Chemical Engineering and Chemical Technology, Imperial College London, London SW7 2AZ, United Kingdom. Trevor.Morgan@ec.europa.eu
George
A
A
Alvarez-Rodriguez
P
P
Millan
M
M
Herod
A A
AA
Kandiyoti
R
R
D002850:Chromatography, Gel / Q000379:methods*; D008800:Mexico; D008970:Molecular Weight; D010578:Petroleum / Q000032:analysis*; D012995:Solubility; D013050:Spectrometry, Fluorescence; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
D010578:Petroleum