Improved abundance sensitivity of molecular ions in positive-ion APCI MS analysis of petroleum in toluene

Kim, Young Hwan; Kim, Sunghwan

doi:10.1016/j.jasms.2009.11.001

Cited by 75 publications

(68 citation statements)

References 32 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…28,[37][38][39] Dissolution of asphaltenes for mass spectrometry experiments requires a careful choice of a solvent. 28,40 Ionization bias is another concern because of the highly complex composition of asphaltenes. 41 Electrospray ionization is suitable for ionizing polar constituents of asphaltenes with a high heteroatom content, while atmospheric pressure chemical ionization (APCI) and atmospheric pressure photo ionization are more suitable for ionizing the nonpolar constituents.…”

Section: Introductionmentioning

confidence: 99%

Structural Comparison of Asphaltenes of Different Origins Using Multi-stage Tandem Mass Spectrometry

et al. 2015

View full text Add to dashboard Cite

In this work, six petroleum asphaltene samples of different geographical origins were studied using atmospheric pressure chemical ionization (APCI) in positive ion mode in a linear quadrupole ion trap mass spectrometer (LQIT). APCI doped with carbon disulfide reagent was selected as the ionization method as it has been previously demonstrated to generate stable molecular ions with no fragmentation for asphaltene molecules. The mass spectra measured using this approach revealed the apparent molecular weights (MWs) of the molecules in the asphaltene samples. The results show that petroleum asphaltenes from the American continent, Europe and China have similar apparent molecular weight distributions, ranging from 200 up to 1450 Da, with slightly different apparent average MWs ranging from 570 to 700 Da. Further, molecular ions with eight randomly selected mass-to-charge ratios (m/z) ranging from m/z 500 up to m/z 808 were isolated for each asphaltene sample and subjected to collisionally activated dissociation (CAD) at the same collision energy to examine their structures. The CAD mass spectra (MS 2 experiment) provided information on the maximum total number of carbons in the alkyl chains and the smallest possible size of the aromatic cores in the ionized molecules. Additionally, MS 3 experiments were performed to investigate the fragmentation patterns of the fragment ions generated in the MS 2 experiments. The results obtained support the island structural model for these asphaltenes. Moreover, molecules of greater MWs are shown to have more carbons in alkyl chains (ranging from 17 to 41) but the minimum core size is fairly constant.

show abstract

Section: Introductionmentioning

confidence: 99%

Structural Comparison of Asphaltenes of Different Origins Using Multi-stage Tandem Mass Spectrometry

et al. 2015

View full text Add to dashboard Cite

show abstract

“…These ions collide with the vaporized solvent molecules to form secondary reactant ions, usually protonated methanol and cluster ions of the type H + (H 2 O) n and H + (CH 3 OH) n [24]. Protonation of the analyte molecules is usually observed in positive-mode APCI, although molecular ions and their fragments (including M-H + ) can also be formed [28,29]. …”

Section: Introductionmentioning

confidence: 99%

Laser-Induced Acoustic Desorption/Atmospheric Pressure Chemical Ionization Mass Spectrometry

Gao

Borton

Owen

et al. 2011

J. Am. Soc. Mass Spectrom.

View full text Add to dashboard Cite

Laser-induced acoustic desorption (LIAD) was successfully coupled to a conventional atmospheric pressure chemical ionization (APCI) source in a commercial linear quadrupole ion trap mass spectrometer (LQIT). Model compounds representing a wide variety of different types, including basic nitrogen and oxygen compounds, aromatic and aliphatic compounds, as well as unsaturated and saturated hydrocarbons, were tested separately and as a mixture. These model compounds were successfully evaporated into the gas phase by using LIAD and then ionized by using APCI with different reagents. From the four APCI reagent systems tested, neat carbon disulfide provided the best results. The mixture of methanol and water produced primarily protonated molecules, as expected. However, only the most basic compounds yielded ions under these conditions. In sharp contrast, using APCI with either neat benzene or neat carbon disulfide as the reagent resulted in the ionization of all the analytes studied to predominantly yield stable molecular ions. Benzene yielded a larger fraction of protonated molecules than carbon disulfide, which is a disadvantage. A similar but minor amount of fragmentation was observed for these two reagents. When the experiment was performed without a liquid reagent (nitrogen gas was the reagent), more fragmentation was observed. Analysis of a known mixture as well as a petroleum cut was also carried out. In summary, the new experiment presented here allows the evaporation of thermally labile compounds, both polar and nonpolar, without dissociation or aggregation, and their ionization to predominantly form stable molecular ions.

show abstract

“…Atmospheric pressure chemical ionization (APCI) is another important ionization source for modern MS techniques, and has been used to study a wide range of compounds [32][33][34][35][36][37]. As HDX MS with CI is effective, it is reasonable to expect that APCI would also be an effective ionization method for HDX.…”

Section: Introductionmentioning

confidence: 99%

Optimization and Application of APCI Hydrogen–Deuterium Exchange Mass Spectrometry (HDX MS) for the Speciation of Nitrogen Compounds

Acter

Cho

Kim

et al. 2015

J. Am. Soc. Mass Spectrom.

Self Cite

View full text Add to dashboard Cite

Abstract. A systematic study was performed to investigate the utility of atmospheric pressure chemical ionization hydrogen-deuterium exchange mass spectrometry (APCI HDX MS) to identify the structures of nitrogen-containing aromatic compounds. First, experiments were performed to determine the optimized experimental conditions, with dichloromethane and CH 3 OD found to be good cosolvents for APCI HDX. In addition, a positive correlation between the heated capillary temperature and the observed HDX signal was observed, and it was suggested that the HDX reaction occurred when molecules were contained in the solvent cluster. Second, 20 standard nitrogen-containing compounds were analyzed to investigate whether speciation could be determined based on the different types of ions produced from nitrogencontaining compounds with various functional groups. The number of exchanges occurring within the compounds correlated well with the number of active hydrogen atoms attached to nitrogen, and it was confirmed that APCI HDX MS could be used to determine speciation. The results obtained by APCI HDX MS were combined with the subsequent investigation of the double bond equivalence distribution and indicated that resins of shale oil extract contained mostly pyridine type nitrogen compounds. This study confirmed that APCI HDX MS can be added to previously reported chemical ionization, electrospray ionization, and atmospheric pressure photo ionization-based HDX methods, which can be used for structural elucidation by mass spectrometry.

show abstract

Improved abundance sensitivity of molecular ions in positive-ion APCI MS analysis of petroleum in toluene

Cited by 75 publications

References 32 publications

Structural Comparison of Asphaltenes of Different Origins Using Multi-stage Tandem Mass Spectrometry

Structural Comparison of Asphaltenes of Different Origins Using Multi-stage Tandem Mass Spectrometry

Laser-Induced Acoustic Desorption/Atmospheric Pressure Chemical Ionization Mass Spectrometry

Optimization and Application of APCI Hydrogen–Deuterium Exchange Mass Spectrometry (HDX MS) for the Speciation of Nitrogen Compounds

Contact Info

Product

Resources

About