Mass spectrometry of very large saturated hydrocarbons This paper is dedicated to the memory of Professor Dr Wilhelm J. Richter

Ludányi, Krisztina; Dallos, András; Kühn, Zsolt; Vékey, Károly

doi:10.1002/(sici)1096-9888(199904)34:4<264::aid-jms749>3.3.co;2-h

Cited by 5 publications

(10 citation statements)

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“…Thus, a corrected relative abundance of 11% is obtained for M +· ions with m / z 1095.0, which is astonishingly low compared with typical FD mass spectra 9–12. The [M − n H 2 ] +· signals are not the result of FD‐MS of a mixture of saturated and unsaturated hydrocarbons because the samples under study have also been analyzed by other analytical methods 27…”

Section: Resultsmentioning

confidence: 98%

“…The Apolanes were synthesized in the Laboratoire de Chimie Technique (Ecole Polytechnique Fédérale de Lausanne, Switzerland). Their EI and CI mass spectra have been discussed in a previous study 27. HPLC‐grade solvents were purchased from Sigma‐Aldrich (Steinheim, Germany).…”

Section: Methodsmentioning

confidence: 99%

“…The multiply branched Apolanes C67, C78, C87 and C103 have previously been studied by electron ionization (EI) and chemical ionization (CI) 27. As the determination of the molecular mass and purity of these samples by these methods was found to be difficult, FD‐MS seemed to be a promising alternative.…”

Section: Introductionmentioning

confidence: 99%

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Field desorption mass spectrometry of large multiply branched saturated Hydrocarbons

Gross¹,

Vékey

Dallos

2001

J. Mass Spectrom.

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Large multiply branched saturated hydrocarbons containing 67-103 carbon atoms (molecular masses 941.8-1446.8 Da) were analyzed by field desorption mass spectrometry (FD-MS) with a double-focusing mass spectrometer. FD-MS was found to have detection limits in the 100 fmol range. The FD mass spectra exhibited molecular ions of astonishingly low abundance. However, the fragment ions formed were closely related to the proposed molecular structure, allowing us to set up rules for straightforward structure elucidation of unknowns. In detail, (i) dehydrogenation, (ii) alkyl losses from molecular ions and (iii) subsequent alkene losses were observed. The influence of the electric field strength on dehydrogenation and C-C cleavages was examined by variation of the emitter potential. Additionally, ion dissociations in the ion source and in the first and second field-free regions, respectively, were compared to study the relative importance of field-induced and thermally induced processes.

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Section: Resultsmentioning

confidence: 98%

Section: Methodsmentioning

confidence: 99%

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Field desorption mass spectrometry of large multiply branched saturated Hydrocarbons

Gross¹,

Vékey

Dallos

2001

J. Mass Spectrom.

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“…The production of the [58+14n] series in mass spectra of hydrocarbons has been frequently described 30–34. Majumdar et al .…”

Section: Resultsmentioning

confidence: 99%

Development of a graphite low-temperature plasma source with dual-mode in-source fragmentation for ambient mass spectrometry

Almasian¹,

Yang²,

Xing³

et al. 2010

Rapid Commun. Mass Spectrom.

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A new low-temperature plasma (LTP), based on dielectric barrier discharge (DBD), has been developed as an alternative ionization source for ambient mass spectrometry. For organic samples, the source is able to produce two different fragmentation patterns which are selectable by an electrical switch. The two source modes are different only in the second electrodes: in configuration (A), bar-plate and in configuration (B), coaxial bar-cylinder shapes are used. A disposable graphite probe is used as the first electrode, the same in both configurations, and a copper foil is used as the second electrode. The ionization source is applicable to gas and liquid samples, without any change being necessary in its design. Under optimal conditions, to take ethylbenzene as an example, a detection limit of less than 25 ng was obtained and a relative standard deviation (RSD) of 13.36% has been demonstrated for 50 ng of ethylbenzene (n = 11). We have found several interesting differences in the mass spectra of the tested volatile organic compounds (VOCs) in the two modes, which might be applicable in identification studies. We have investigated the effect of variation of the first electrode material and the second electrode length in mode B. Moreover, in this design the graphite electrode is capable of acting as a sample adsorbent, which is a new sampling method for LTP mass spectrometry (MS). This capability was investigated by adsorption of the selected VOCs onto the surface of the graphite electrode in a headspace solid-phase microextraction (SPME) system, and direct desorption and ionization of the samples by LTPMS.

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“…Generally, the electron energy is set to be around 70 eV (as shown in Table 1) since the cross section of electron impact ionization becomes the maximum for most organic compounds 7, 18. However, it has been reported that the low‐energy EI mass spectra can give detailed structural information since the abundances of the unspecific fragment ions are reduced 19, 20. The mass spectrum at an electron energy of 15 eV is shown in Fig.…”

Section: Experimental Methods and Resultsmentioning

confidence: 99%

Development of a new electron ionization/field ionization ion source for gas chromatography/time‐of‐flight mass spectrometry

Miyamoto

Fujimaki

Ueda

2009

Rapid Comm Mass Spectrometry

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We have developed a combined EI/FI source for gas chromatography/orthogonal acceleration time-of-flight mass spectrometry (GC/oaTOFMS). In general, EI (electron ionization) and FI (field ionization) mass spectra are complementary: the EI mass spectrum contains information about fragment ions, while the FI mass spectrum contains information about molecular ions. Thus, the comparative study of EI and FI mass spectra is useful for GC/MS analyses. Unlike the conventional ion sources for FI and EI measurements, the newly developed source can be used for both measurements without breaking the ion source vacuum or changing the ion source. Therefore, the combined EI/FI source is more preferable than the conventional EI or FI ion source from the viewpoint of the reliability of measurements and facility of operation. Using the combined EI/FI source, the complementarity between EI and FI mass spectra is demonstrated experimentally with n-hexadecane (100 pg): characteristic fragment ions for the n-alkane such as m/z 43, 57, 71, and 85 are obtained in the EI mass spectrum, while only the parent peak of m/z 226 (M+) without any fragment ions is observed in the FI mass spectrum. Moreover, the field desorption (FD) measurement is also demonstrated with poly(ethylene glycol)s M600 (10 ng) and M1000 (15 ng). Signals of [M+H]+, [M+Na]+ and [M+K]+ are clearly detected in the FD mass spectra.

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Mass spectrometry of very large saturated hydrocarbons This paper is dedicated to the memory of Professor Dr Wilhelm J. Richter

Cited by 5 publications

References 0 publications

Field desorption mass spectrometry of large multiply branched saturated Hydrocarbons

Field desorption mass spectrometry of large multiply branched saturated Hydrocarbons

Development of a graphite low-temperature plasma source with dual-mode in-source fragmentation for ambient mass spectrometry

Development of a new electron ionization/field ionization ion source for gas chromatography/time‐of‐flight mass spectrometry

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