Shimadzu Corporation

Sadao Takeuchi

Takahiro Harada

Kiyoshi Ogawa

Mitsutoshi Setou

Li Ding

Osamu Furuhashi

Roger Giles

Hiroaki Waki

Yoshikazu Yoshida

Shuichi Shimma

The present invention provides a mass spectrometer having an ion lens capable of transporting an ion having a large mass to charge ratio with a high level of ion-passing efficiency even under a low-vacuum atmosphere. In conventional atmospheric pressure ionization mass spectrometers or similar mass spectrometers, applying an excessively high voltage to the ion lens undesirably causes an electric discharge. Therefore, the passing efficiency for an ion having a large mass to charge ratio cannot be adequately improved, which leads to a poor detection sensitivity. To solve this problem, the mass spectrometer according to the present invention includes a voltage controllerthat controls a variable radiofrequency (RF) voltage generatorso that both the amplitude and the frequency of the RF voltage applied to the lens electrodes of an ion lensare changed according to the mass to charge ratio of an ion to be analyzed. This control enables the ion lensto focus an ion and transport it to the subsequent stage with a high level of passing efficiency even in the case of analyzing an ion having a large mass to charge ratio. Thus, the detection sensitivity is improved. The aforementioned control is conducted on the basis of the control data stored in a voltage control data storage. These data are obtained in advance by a measurement of a sample containing a substance having a known mass to charge ratio, in which the intensity of the signal of an ion detector is maintained while the analysis conditions are changed.

Mass spectrometer

A sample platewith a sampleplaced thereon is initially set on a stage, and a visual image of the sample is taken with a CCD camera. This image is stored in an image data memory. Then, an operator removes the sample plate, sprays a matrix for a MALDI process onto the sampleand replaces the plate onto the stage. After that, when a predetermined operation is made, a clear image of the sample taken before the application of the matrix is shown on a display unit. On this image, the operator specifies a point or area for the analysis. The samplemay have been displaced due to the removal and replacement of the plate. Accordingly, an image analyzercalculates the direction and magnitude of the displacement, for example, by recognizing the position of the markings provided on the sample plate. A displacement correctorcomputes coordinate values in which the displacement is corrected. Thus, even if a displacement occurs, the mass analysis can be accurately performed on the point or area of the actual sample as specified on the clear visual image taken before the application of the matrix.

In a mass spectrometer for carrying out mass analysis while microscopically observing a two-dimensional area of a sample, the observation position for selecting a target portion while observing an image of the samplecaptured with a CCD camerais separated from the analysis position for carrying out the mass analysis of the sampleby delivering laser light from the laser-delivering unitonto the sample. The sampleis placed on a stage, which can be precisely moved between the observation position and the analysis position by a stage-driving mechanism. An observation optical systemcan be set close to the sampleat the observation position, without impeding the flight of the ions generated from the sampleduring the analysis or interfering with a laser-condensing optical system. Thus, the spatial resolution for observation is improved without deteriorating the ion-detecting efficiency.

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Nagaokakyo, Japan

Sadao Takeuchi