Journal of the Mass Spectrometry Society of Japan

REGULAR PAPER

Collision-Induced Dissociation (CID) Spectra versus Collision Energy Using a Quadrupole Ion Trap Mass Spectrometer IV

—Dissociation of Ionized Maleamide and Fumaramide—

Susumu TAJIMA, Masaaki UBUKATA, Masao FUJISHIGE

2004 Volume 52 Issue 2 Pages 57-62
Published: 2004
Released on J-STAGE: October 28, 2005

DOIhttps://doi.org/10.5702/massspec.52.57

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The unimolecular decompositions of the geometrical isomers maleamide (cis-NH₂COCH=CHCONH₂; 1, MW: 114) and fumaramide (trans-NH₂COCH=CHCONH₂; 2, MW: 114) have been investigated by use of collision-induced dissociation (CID) spectra versus collision energy. These ions, 1^+· and 2^+·, show as primary fragmentation channels the losses of NH₂ and CONH to give the ions m/z 98 and 71, respectively, but the relative abundance of these ions is different with each other. This will be attributable to amide-amide interaction in cis-isomer. The fragment ions m/z 71 correspond to the molecular ion of acrylamide, CH₂=CHCONH₂, which is formed by hydrogen atom migration from NH₂ to ethylenic carbon in the molecular ions 1^+· and 2^+·, followed by CONH loss. The additional dissociation channels are observed for 2^+·, the losses CO and CONH₂ to give the ions at m/z 86 and 70, respectively. These two reactions were weak for 1^+·. These ions, except for m/z 71 ion, retain the structure difference between the geometrical isomers. The [M-NH₂]⁺ ions decompose further by the losses of H₂O and CO to generate the ions at m/z 80 and 70, respectively. The former reaction for 1 is different from that for 2. This reaction accompanies with double hydrogen atom transfers, and was not described in previous report.

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NOTE

Ortho Effects in Bis-phosphoric Esters of the Dihydroxy- and Aminohydroxybenzenes Observed by ESI-MS/MS

Chen XIAOLAN, Qu LINGBO, Lu JIANSHA, Guo LEI, Yu YOUZHU, Zhao YUFEN

2004 Volume 52 Issue 2 Pages 63-67
Published: 2004
Released on J-STAGE: October 28, 2005

DOIhttps://doi.org/10.5702/massspec.52.63

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Derivatives of phenols, such as o-aminophenol, m-aminophenol, p-aminophenol, o-dihydroxybenzene, m-dihydroxybenzene, and p-dihydroxybenzene were phosphorylated by diethyl phosphite (DEPH) using simplified Atherton-Todd method and then the resulting di-phosphorylated compounds were injected into an ion-trap mass spectrometer and exposed to MS/MS analysis. Results showed that the cleavage pathways of these phosphorylated compounds were closely related to the relative positions of the phosporylating groups. Comparatively stable five-membered ring ions were produced when the two phosphorylated functional groups were in the ortho position. These stable five-membered ring ions can be considered as indicators for ortho functional groups of phenols.

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COMMUNICATION

Comparative Study of Laser Spray and Electrospray Using an Orthogonal Time-of-Flight Mass Spectrometer

Atsushi TAKAMIZAWA, Susumu FUJIMAKI, Shigemitsu OKAZAKI, Kenzo HIRAOKA

2004 Volume 52 Issue 2 Pages 68-71
Published: 2004
Released on J-STAGE: October 28, 2005

DOIhttps://doi.org/10.5702/massspec.52.68

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A preliminary study on the laser spray and electrospray was made using an orthogonal time-of-flight mass spectrometer. Explosive vaporization and mist formation occurred when an aqueous solution effusing out from the tip of the stainless steel capillary was irradiated from the opposite side of the capillary by a 10.6 μm infrared laser. Little ion signals could be detected when the plume was sampled through the ion sampling orifice. When a high voltage (∼3 kV) was applied to the stainless steel capillary, strong ion signals appeared. The ion intensities were found to be more than one order of magnitude stronger than those obtained by the conventional electrospray for aqueous solutions of arginine and lysozyme. The present method is regarded as the electric-field assisted MALDI in which the LC solvents (water etc.) act as liquid matrices. The laser spray will be a versatile method for the biological mass spectrometry because this method is compatible with the natural solvent, water.

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INTEGRATED PAPER

Studies of Post-source Decay of Carbohydrates and Their Structure Analyses

Tohru YAMAGAKI

2004 Volume 52 Issue 2 Pages 72-83
Published: 2004
Released on J-STAGE: October 28, 2005

DOIhttps://doi.org/10.5702/massspec.52.72

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When we analyze oligosaccharides by mass spectrometry, the fragment ions at glycosyl linkages show their sequences. However, it is difficult to distinguish between the linkage isomers or to analyze the types of glycosyl linkages. We have studied the post-source decay (PSD) of oligosaccharides in MALDI-MS, and we focused our attention on the abundance of the PSD ions to distinguish the linkage isomers. For example, the PSD ions produced by the cleavage of the α1→4 glycosyl linkage had higher abundance than those of α1→6 glycosyl linkage. The PSD ions produced by the cleavage of sialyl 2→3 linkages showed higher abundance than those of sialyl 2→6 linkages, and so on. These analyses of the linkage isomers of oligosaccharides have been performed systematically by MALDI-TOF mass spectrometry equipped with curved-field reflectron.

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