The use of nonpolar matrices for matrix‐assisted laser desorption/ionization mass spectrometric analysis of high boiling crude oil fractions

Abstract

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) with nonpolar matrices has been investigated for its applicability to the characterization of atmospheric resid crude oil fractions. The data obtained by use of nonpolar matrices was compared with that from polar matrices as well as from direct LDI-MS and field ionization mass spectrometry. Nonpolar matrices, such as anthracene or 9-cyanoanthracene, yield only a single radical molecular cation upon LDI. Thus, no interfering matrix-related ions are present during the MALDI-TOFMS analysis of the crude oil sample. Nonpolar matrices yield molecular mass distributions from linear mode MALDI-TOFMS that are comparable to distributions found with LDI-MS. An advantage of nonpolar matrices is the increased production of analyte ions, which allows reflectron mode MALDI-TOFMS to be performed. Nonpolar matrices are also shown to be less sensitive to solvent and sample preparation conditions than conventional polar matrices. These results suggest that nonpolar matrices may be favorable alternatives to more traditional polar or acidic matrices commonly used in the MALDI mass spectral characterization of crude oil related samples.

Contribution of mass spectrometry in assessing quality of petroleum fractions

“…All three fractionation techniques produced similar trends, showing greater polarity of the fractions to correlate with the increased molecular mass. Robins and Limbach (2003) implicated non-polar matrices for a MALDI TOF analysis of high boiling crude oil fractions. The result they obtained was compared with that from polar matrices as well as from direct LDI-MS and field ionization mass spectrometry.…”

Analysis of Polar Components in Crude Oil by Ambient Mass Spectrometry

“…The matrix absorbs the energy supplied by the pulsed laser to assist the ionization of analytes. Although the MALDI analysis is performed under vacuum, a characterization of the chemical components in crude oil has been reported (Robins et al, 2003). Unlike the traditional polar and acidic matrices, such as sinapinic acid, -cyano-3-hydroxycinnamic acid, and 2, 5-dihydroxybenzoic acid, non-polar matrices, including anthracite and 9-cyanoanthracene, are more effective for characterizing crude oil fractions as they provide higher quality MALDI mass spectra.…”

Laser desorption ionization FT-ICR mass spectrometry and CARSPLS for predicting basic nitrogen and aromatics contents in crude oils

“…MALDI became an established mass spectrometry method for macromolecular compounds. LDI/MALDI coupled to time of flight mass spectrometry (TOF) has been applied in petroleomics for the characterization of petroporphyrins [12], crude oils [13], and their fractions [14,15], in addition to the determination of the molecular-weight distributions (MWDs) of asphaltenes [16][17][18][19][20][21].…”