Abstract: After various ions of sample origin have been captured within an ion trap, unnecessary ions other than a target ion having a specific m/z are ejected from the ion trap (S1, S2). Subsequently, an operation for dissociating the target ion within the ion trap by hydrogen radical dissociation (HAD), and an operation for sequentially ejecting the thereby generated product ions by resonance excitation from the low m/z side to a point located immediately before the m/z of the target ion, are repeated multiple times (S3-S7). The ions ejected by resonance excitation are detected with a detector to acquire MS/MS spectrum data, and the data obtained by performing the ejection by resonance excitation multiple times are accumulated to create the final MS/MS spectrum (S5, S8).

Abstract: In a mass spectrum of fragment ions obtained by dissociating peptide-derived ions using the technique of irradiating the ions with hydrogen radicals, either pairs of a-type and c-type ions or those of z-type and z-type ions are characteristically observed. Since the mass difference of those ion pairs is previously known, a pair peak searcher 92 searches for pair peaks having a predetermined mass difference in a mass spectrum created by a mass spectrum creator 91, and adds to the detected pair peaks a piece of information indicating that they are pairs of a-type and c-type ions or those of x-type and z-type ions. When estimating the amino acid sequence of the peptide by a database search, a protein identifier 93 uses the ion-pair information in addition to the m/z value of each peak, whereby the accuracy of the estimation or identification the amino acid sequence can be improved.

Abstract: In a mass spectrum of fragment ions obtained by dissociating peptide-derived ions using the technique of irradiating the ions with hydrogen radicals, either pairs of a-type and c-type ions or those of z-type and z-type ions are characteristically observed. Since the mass difference of those ion pairs is previously known, a pair peak searcher 92 searches for pair peaks having a predetermined mass difference in a mass spectrum created by a mass spectrum creator 91, and adds to the detected pair peaks a piece of information indicating that they are pairs of a-type and c-type ions or those of x-type and z-type ions. When estimating the amino acid sequence of the peptide by a database search, a protein identifier 93 uses the ion-pair information in addition to the m/z value of each peak, whereby the accuracy of the estimation or identification the amino acid sequence can be improved.

Abstract: After various ions of sample origin have been captured within an ion trap, unnecessary ions other than a target ion having a specific m/z are ejected from the ion trap (S1, S2). Subsequently, an operation for dissociating the target ion within the ion trap by hydrogen radical dissociation (HAD), and an operation for sequentially ejecting the thereby generated product ions by resonance excitation from the low m/z side to a point located immediately before the m/z of the target ion, are repeated multiple times (S3-S7). The ions ejected by resonance excitation are detected with a detector to acquire MS/MS spectrum data, and the data obtained by performing the ejection by resonance excitation multiple times are accumulated to create the final MS/MS spectrum (S5, S8).

Abstract: Lipid-derived ions captured within an ion trap are irradiated with hydrogen radicals to induce the reaction of hydrogen extraction (S1, S2). A precursor-ion isolation process is subsequently performed (S3), and the precursor ion is dissociated by low-energy collision-induced dissociation (S4). The thereby generated product ions are subjected to mass spectrometry to create a product-ion spectrum (S5, S6). Since the dissociation achieved by such a procedure does not cause hydrogen rearrangement, a peak pair having a mass difference of +12 Da characteristic of the unsaturated bond site certainly appears on the product-ion spectrum. By searching for this peak pair, the unsaturated bond site can be located (S7, S8). By such a method, a lipid-structure analysis including the determination of the position of the unsaturated bond site in a lipid can be performed in a stable and accurate manner without requiring derivatization or other cumbersome pretreatments.

Abstract: A cloud of ions captured in an ion trap (2) is irradiated with a stream of hydrogen radicals cast through a radical particle introduction hole (26) bored in a ring electrode (21) at a flow rate of 4×1010 [atoms/s]. As a result, a radical induced dissociation which does not rely on the transfer or capture of electrons occurs within the ion trap (2), whereby c/z-type fragment ions are efficiently generated. After the irradiation with the hydrogen radicals, a supplemental collision-induced dissociation process may performed by introducing inert gas into the ion trap (2) and resonantly exciting the ions, in order to further promote the generation of the c/z-type fragment ions. In this manner, according to the present invention, it is possible to achieve radical induced dissociation of singly-charged ions derived from a peptide and use the thereby generated c/z-type fragment ions for mass spectrometry.

Abstract: A cloud of ions captured in an ion trap (2) is irradiated with a stream of hydrogen radicals cast through a radical particle introduction hole (26) bored in a ring electrode (21) at a flow rate of 4×1010 [atoms/s]. As a result, a radical induced dissociation which does not rely on the transfer or capture of electrons occurs within the ion trap (2), whereby c/z-type fragment ions are efficiently generated. After the irradiation with the hydrogen radicals, a supplemental collision-induced dissociation process may performed by introducing inert gas into the ion trap (2) and resonantly exciting the ions, in order to further promote the generation of the c/z-type fragment ions. In this manner, according to the present invention, it is possible to achieve radical induced dissociation of singly-charged ions derived from a peptide and use the thereby generated c/z-type fragment ions for mass spectrometry.

Abstract: A mass spectrometry using helium as cooling gas is performed to obtain a first mass spectrum (S1), and another mass spectrometry using argon, which is heavier than helium, as cooling gas is performed to obtain a second mass spectrum for the same sample (S2). Due to the difference between the two gases in terms of the effect of promoting dissociation of modifications, an ion peak originating from a target compound from which all the modifications have been dissociated will appear with a higher intensity on the second mass spectrum. The peak patterns of the two mass spectra are compared to locate the all-dissociated ion peak while excluding unnecessary peaks (S3). Based on that peak, the assignment of each peak is determined (S4).

Abstract: A mass spectrometry using helium as cooling gas is performed to obtain a first mass spectrum (S1), and another mass spectrometry using argon, which is heavier than helium, as cooling gas is performed to obtain a second mass spectrum for the same sample (S2). Due to the difference between the two gases in terms of the effect of promoting dissociation of modifications, an ion peak originating from a target compound from which all the modifications have been dissociated will appear with a higher intensity on the second mass spectrum. The peak patterns of the two mass spectra are compared to locate the all-dissociated ion peak while excluding unnecessary peaks (S3). Based on that peak, the assignment of each peak is determined (S4).

Abstract: Ions supplied in the form of a pulse are introduced into an ion trap through an ion entering orifice while a rectangular voltage of a frequency higher than the frequency at which the best trap is accomplished is applied to a ring electrode from a trap voltage generating unit. With this, since a well of a pseudo ion potential is formed in a radial direction in the ion trap, the spread of ions of low m/z values introduced previously is suppressed. A part of ions is introduced into the ion trap, and thereafter the frequency of the rectangular voltage applied to the ring electrode is lowered stepwise to the frequency at which the best trap is accomplished. As a result, the ions of the low m/z values introduced previously can be efficiently trapped, and introduction of ions of high m/z values reaching the ion trap later is not hindered.

Abstract: While applying a square wave voltage to the ion electrode (21) so that ions already captured in the ion trap (20) do not disperse, the timing of irradiating a laser light for ion generation is controlled in such a manner that ions reach the ion inlet (25) at a predetermined timing of a cycle of the voltage. In the case of a positive ion (cation) for example, the timing of laser light irradiation is adjusted in such a manner that the target ions reach the ion inlet (25) in the low level period of a cycle of the square wave voltage. By injecting ions in addition to the ions already captured in the ion trap (20) in this manner, the amount of ions can be increased, and by performing a mass separation and detection after that, the signal intensity in one mass analysis can be increased. Accordingly, by decreasing the number of repetitions of the mass analysis for summing up mass profiles, the measuring time can be shortened.

Abstract: While applying a square wave voltage to the ion electrode (21) so that ions already captured in the ion trap (20) do not disperse, the frequency of the square wave voltage is temporarily increased at the timing when the ions generated in response to the short time irradiation of a laser light reach the ion inlet (25). This decreases the Mathieu parameter qz, and the potential well becomes shallow, which makes it easy for ions to enter the ion trap (20). Although the ions that have been already captured become more likely to disperse, the frequency of the square wave voltage is decreased before they deviate from the stable orbit. Thus, the dispersion of the ions can also be avoided. Accordingly, while the number of captured ions is not decreased, new ions are further added, and thereby the amount of ions can be increased. By performing a mass separation and detection after that, the signal intensity in one mass analysis can be increased.

Abstract: While applying a square wave voltage to the ion electrode (21) so that ions already captured in the ion trap (20) do not disperse, the timing of irradiating a laser light for ion generation is controlled in such a manner that ions reach the ion inlet (25) at a predetermined timing of a cycle of the voltage. In the case of a positive ion (cation) for example, the timing of laser light irradiation is adjusted in such a manner that the target ions reach the ion inlet (25) in the low level period of a cycle of the square wave voltage. By injecting ions in addition to the ions already captured in the ion trap (20) in this manner, the amount of ions can be increased, and by performing a mass separation and detection after that, the signal intensity in one mass analysis can be increased. Accordingly, by decreasing the number of repetitions of the mass analysis for summing up mass profiles, the measuring time can be shortened.

Abstract: The present invention provides a method for improving the sensitivity of mass spectrometry for biological molecules. The present invention also provides a method for a rapid and simple analysis of biological samples by making use of the method for improving the sensitivity of mass spectrometry. A method for labeled amidation, comprising the step of reacting an amidating reagent labeled with 15N, an isotope of nitrogen, with the carboxyl group of a biological molecule. A method for analyzing a biological molecule, comprising the steps of performing amidation to a carboxyl group of a biological molecule to obtain an amidated form of the biological molecule, and subsequently subjecting the amidated form of the biological molecule to mass spectrometry. A labeled amidated form of a biological molecule wherein a carboxyl group of the biological molecule is amidated as 15N-labeled amide group.