JPH0756789B2 - Mass spectrometric method by laser ionization mass spectrometer - Google Patents
Mass spectrometric method by laser ionization mass spectrometerInfo
- Publication number
- JPH0756789B2 JPH0756789B2 JP61076275A JP7627586A JPH0756789B2 JP H0756789 B2 JPH0756789 B2 JP H0756789B2 JP 61076275 A JP61076275 A JP 61076275A JP 7627586 A JP7627586 A JP 7627586A JP H0756789 B2 JPH0756789 B2 JP H0756789B2
- Authority
- JP
- Japan
- Prior art keywords
- sample
- mass
- laser
- measurement
- time
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
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- Other Investigation Or Analysis Of Materials By Electrical Means (AREA)
- Electron Tubes For Measurement (AREA)
Description
【発明の詳細な説明】 〈産業上の利用分野〉 本発明は、レーザ光を試料に照射してイオン化し得られ
た質量スペクトルから試料分子の組成等を分析するレー
ザイオン化質量分析計を用いた質量分析方法に関し、更
に詳しくは、液体を含む試料を、効率的に分析すること
のできる方法に関する。DETAILED DESCRIPTION OF THE INVENTION <Industrial Field of Application> The present invention uses a laser ionization mass spectrometer that analyzes the composition of sample molecules from a mass spectrum obtained by irradiating a sample with laser light and ionizing the sample. The present invention relates to a mass spectrometric method, and more particularly to a method capable of efficiently analyzing a sample containing a liquid.
〈従来の技術〉 質量分析計において難揮発性で熱的不安定な有機物質を
イオン化する場合、フラグメンテーションを起させずに
親イオンを発生させる方法のひとつにレーザ光を照射す
る方法がある。この場合、固体試料は、水，エタノー
ル，アセトン等の適当な溶媒に溶かし、金属等の試料ホ
ルダー上に滴下した後、乾燥させ、薄膜状にして用いら
れる。しかし、この状態では、親イオンの生成量が微小
で、また、長時間のイオン生成は期待できない。<Prior Art> When ionizing a poorly volatile and thermally unstable organic substance in a mass spectrometer, one of the methods for generating parent ions without causing fragmentation is irradiation with laser light. In this case, the solid sample is dissolved in an appropriate solvent such as water, ethanol, or acetone, dropped on a sample holder such as a metal, and then dried to be used as a thin film. However, in this state, the amount of parent ions produced is very small, and long-term ion production cannot be expected.
本出願人は、イオンの生成量を増大させ、しかもその継
続時間を長くするため、試料溶液に金属微粒子と例えば
グリセリン等の低蒸気圧液体を添加する方法を既に提案
した。しかし、この様な試料作成法によっても、高質量
数物質においてはその親イオンの生成時間は限られてい
る。The present applicant has already proposed a method of adding metal fine particles and a low vapor pressure liquid such as glycerin to a sample solution in order to increase the production amount of ions and prolong the duration thereof. However, even with such a sample preparation method, the generation time of the parent ion is limited in the high mass number substance.
〈発明が解決しようとする問題点〉 通常、飛行時間型質量分析計においては、原理的には１
回の測定で全質量スペクトルが得られるはずであるが、
高質量数イオン等の微少イオンに対しては、何回かの測
定を積算してスペクトルを得ることが行なわれる。この
場合、上述のように親イオンの生成時間が限定されてい
ると、むやみに積算回数を増大しても、親イオン以外の
フラグメントイオンや他のイオンばかり検出され、親イ
オンの検出が困難になる。また、親イオンの検出ができ
ても、非常にSN比の悪いスペクトルしか得られない。<Problems to be Solved by the Invention> Generally, in a time-of-flight mass spectrometer, in principle, 1
The total mass spectrum should be obtained in a single measurement,
For small ions such as high mass number ions, several measurements are integrated to obtain a spectrum. In this case, if the generation time of the parent ion is limited as described above, even if the number of integrations is increased unnecessarily, only fragment ions other than the parent ion and other ions are detected, and it becomes difficult to detect the parent ion. Become. Moreover, even if the parent ion can be detected, only a spectrum with a very poor SN ratio can be obtained.
〈問題点を解決するための手段〉 本発明のレーザイオン化質量分析計による質量分析方法
は、レーザ質量分析計を用いた分析に際して、液体を含
む試料表面にレーザ光を照射して得られる反射光の強度
を検出し、その検出結果の時間的変化が、あらかじめ定
められた状態よりも安定した時点でイオンの測定を開始
することによって特徴づけられる。<Means for Solving Problems> A mass spectrometric method by a laser ionization mass spectrometer of the present invention is a reflected light obtained by irradiating a sample surface containing a liquid with a laser beam during analysis using a laser mass spectrometer. Is detected, and the change in the detection result with time is characterized by starting the measurement of ions at a time point more stable than a predetermined state.
〈作用〉 本発明は、液体を含む試料にレーザ光を照射したときの
親イオンの生成量が、レーザ照射による試料の乾燥の程
度に依存していること事実の把握に基づき、従来のよう
に多数回の測定を積算してスペクトルを得るのではな
く、親イオンの生成量が増大する時間帯を推測し、その
時間帯に測定を行うことで、SN比の良好な測定結果を得
ようとするものである。<Operation> The present invention is based on the understanding that the amount of parent ions produced when a sample containing a liquid is irradiated with laser light depends on the degree of drying of the sample by laser irradiation, and In order to obtain a good S / N ratio measurement result, it is necessary to estimate the time zone in which the amount of parent ions produced increases and perform the measurement during that time zone, instead of accumulating multiple measurements to obtain a spectrum. To do.
すなわち、試料に金属微粒子とグリセリン等を添加する
という方法によって、高質量親イオンの生成が可能であ
るが、その生成時間は限られている。第３図に例示する
ように、親イオン強度は、試料の導入から一定の時間帯
において急激に増大し、その後は低下する。このように
親イオンの生成時間が限られる原因は確定的ではない
が、実験事実として、グリセリン等の低蒸気圧液体が完
全に蒸発してしまう直前、つまり半渇きの状態で親イオ
ンの生成量が常に増大することが確認された。That is, a method of adding metal fine particles and glycerin or the like to a sample can generate a high mass parent ion, but the generation time is limited. As illustrated in FIG. 3, the parent ionic strength sharply increases in a certain time period from the introduction of the sample and then decreases. The reason why the generation time of the parent ion is limited in this way is not definite, but it is an experimental fact that the amount of parent ion generated immediately before the low vapor pressure liquid such as glycerin is completely evaporated, that is, in the state of half-third It has been confirmed that is constantly increasing.
一方、液体を含む試料の乾燥度は、試料の表面にレーザ
光を照射したときに得られる反射光強度の時間的安定度
に相関性を示す。On the other hand, the dryness of the sample containing the liquid shows a correlation with the temporal stability of the reflected light intensity obtained when the surface of the sample is irradiated with laser light.
そこで、本発明では、試料の表面に照射されたレーザ光
の反射光強度を検出し、その検出結果の時間的変化が定
められた状態よりも安定した時点でイオンの測定を開始
することにより、親イオンの生成量が増大する時間帯で
の効率的な測定が可能となる。Therefore, in the present invention, by detecting the reflected light intensity of the laser light applied to the surface of the sample, by starting the measurement of ions at a time when the temporal change of the detection result is more stable than the predetermined state, Efficient measurement is possible during the time period when the amount of parent ions produced increases.
〈実施例〉 第１図は本実施例のレーザイオン化質量分析計の構成を
示す。１は試料をイオン化するためのパルスレーザ光、
２と３は光学系、４は試料、５は試料ホルダ、６はイオ
ン引出し電極、７は分析部である。８はレーザ光源、９
はレンズ、10は光検出器である。<Example> FIG. 1 shows the configuration of a laser ionization mass spectrometer of this example. 1 is a pulsed laser beam for ionizing the sample,
2 and 3 are optical systems, 4 is a sample, 5 is a sample holder, 6 is an ion extraction electrode, and 7 is an analysis unit. 8 is a laser light source, 9
Is a lens, and 10 is a photodetector.
実際の測定に入る前に、試料４の表面の状態を検出する
ために、レーザ光源８で発生した例えばHe−Neレーザ光
をレンズ９で集光して試料４に照射する。このときの試
料４からの反射光を光検出器10にて検出する。Before the actual measurement, in order to detect the state of the surface of the sample 4, for example, He—Ne laser light generated by the laser light source 8 is condensed by the lens 9 and irradiated on the sample 4. The photodetector 10 detects the reflected light from the sample 4 at this time.
第２図はこの反射光強度の時間変化を示す。まず、試料
４を導入した直後は、試料４は液状であり、レーザ光は
その表面にて反射されるため、反射光強度は大である。
しかし、これに続く期間ΔT1では、蒸発が強く起ってい
るため、その表面の状態は刻々と変化する。したがっ
て、反射光強度の変化は大きい。さらに、期間ΔT2にお
いて、蒸発が進んでくると液面からの反射が減少し、金
属粉末による散乱の影響により強度は減少するが、やや
安定性を増す。その後、完全に液体が蒸発してしまう
と、金属粉末によって散乱される割合が多くなるが、反
射光（散乱光）強度は一定になる。FIG. 2 shows the time variation of the reflected light intensity. First, immediately after the sample 4 is introduced, the sample 4 is in a liquid state and the laser light is reflected on the surface thereof, so that the reflected light intensity is high.
However, in the subsequent period ΔT 1 , the evaporation is strongly occurring, and therefore the state of the surface changes from moment to moment. Therefore, the change in reflected light intensity is large. Further, during the period ΔT 2 , as the evaporation proceeds, the reflection from the liquid surface decreases and the strength decreases due to the influence of scattering by the metal powder, but the stability slightly increases. After that, when the liquid is completely evaporated, the ratio of scattering by the metal powder increases, but the reflected light (scattered light) intensity becomes constant.
親イオンの生成は、期間ΔT2において起る。したがっ
て、光検出器10からの反射光強度信号をレコーダ（図示
せず）等で観測しておき、期間ΔT2の状態のようになる
と、実際の測定を開始する。The production of parent ions occurs in the period ΔT 2 . Therefore, the reflected light intensity signal from the photodetector 10 is observed by a recorder (not shown) or the like, and when the state is in the period ΔT 2 , the actual measurement is started.
実際の測定時には、パルスレーザ光１が光学系2,3を経
て試料４に照射され、発生した親イオンは分析部７に導
かれる。At the time of actual measurement, the pulse laser beam 1 is irradiated onto the sample 4 via the optical systems 2 and 3, and the generated parent ions are guided to the analysis unit 7.
このように、期間ΔT2になると測定を行なうことで、親
イオンが生成していない期間ΔT1でのスペクトルの積算
を防ぐことができ、励起レーザ光１をむやみに照射する
ことなく、効率の良い測定が可能になる。As described above, by performing the measurement in the period ΔT 2 , it is possible to prevent the spectrum from being integrated in the period ΔT 1 in which the parent ion is not generated, and the excitation laser beam 1 is not radiated unnecessarily and the efficiency is improved. Good measurement is possible.
なお、試料が完全に乾燥してしまうと、親イオンは生じ
なくなり、第２図の時刻T3以降のように反射光強度が全
く一定になるので、ここで測定を終了すればよい。When the sample is completely dried, parent ions are not generated and the reflected light intensity becomes completely constant as at time T 3 and after in FIG. 2, so the measurement may be ended here.
なお、本実施例では励起レーザ光と異なった方向からレ
ーザ光を入射させたが、通常励起レーザ光と同軸で入射
されるガイドレーザ光の散乱光を検出するようにしても
よい。In the present embodiment, the laser light is incident from a direction different from that of the excitation laser light, but scattered light of the guide laser light that is incident on the same axis as the normal excitation laser light may be detected.
〈発明の効果〉 以上説明したように本発明においては、測定時間を長く
して親イオンの検出を行なうのではなく、親イオンの生
成量が増大する時間帯を、試料に照射されたレーザ光の
反射光強度の時間的変化の状態から推定し、その結果に
基づいてイオンの測定開始タイミングを決定するから、
大量の親イオンが生成されている時間帯において確実に
その親イオンを測定することができ、効率的でしかもSN
比の良好な測定が可能となる。さらに、測定時間を短縮
できるとともに、試料の消費量が少なくて済む。<Effects of the Invention> As described above, in the present invention, the measurement of the parent ion is not performed for a long time, but the sample is irradiated with the laser beam during the time period when the amount of the parent ion produced increases. Since it is estimated from the state of the temporal change of the reflected light intensity of, and the measurement start timing of ions is determined based on the result,
The parent ion can be reliably measured during the time when a large amount of parent ion is generated, which is efficient and SN
A good ratio measurement is possible. Further, the measurement time can be shortened and the sample consumption can be reduced.
第１図は本発明実施例を適用して質量分析を行う際の装
置構成の例を示す図、第２図は本発明の実施例の反射光
強度の時間変化を示す図、第３図はレーザイオン化質量
分析計における親イオン強度の時間変化を示す図であ
る。 １…パルスレーザ光 2,3…光学系 ４…試料 ７…分析部 ８…レーザ光源 ９…レンズ 10…光検出器FIG. 1 is a diagram showing an example of an apparatus configuration when performing mass spectrometry by applying the embodiment of the present invention, FIG. 2 is a diagram showing a time change of reflected light intensity of the embodiment of the present invention, and FIG. It is a figure which shows the time change of the parent ion intensity in a laser ionization mass spectrometer. 1 ... Pulse laser light 2,3 ... Optical system 4 ... Sample 7 ... Analysis part 8 ... Laser light source 9 ... Lens 10 ... Photodetector
Claims (1)
ンを質量／電荷の比にしたがってより分けるレーザイオ
ン化質量分析計を用いた質量分析方法であって、液体を
含む試料表面にレーザ光を照射して得られる反射光の強
度を検出し、その検出結果の時間的変化が、あらかじめ
定められた状態よりも安定した時点でイオンの測定を開
始することを特徴とする、レーザイオン化質量分析計に
よる質量分析方法。1. A mass spectrometric method using a laser ionization mass spectrometer, in which parent ions generated by irradiating a sample with laser light are separated according to a mass / charge ratio. Laser ionization mass spectrometry, characterized in that the intensity of the reflected light obtained by irradiating with is detected, and the time change of the detection result starts the measurement of ions when it is more stable than a predetermined state. Mass spectrometric method.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP61076275A JPH0756789B2 (en) | 1986-03-31 | 1986-03-31 | Mass spectrometric method by laser ionization mass spectrometer |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP61076275A JPH0756789B2 (en) | 1986-03-31 | 1986-03-31 | Mass spectrometric method by laser ionization mass spectrometer |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS62232847A JPS62232847A (en) | 1987-10-13 |
| JPH0756789B2 true JPH0756789B2 (en) | 1995-06-14 |
Family
ID=13600708
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP61076275A Expired - Lifetime JPH0756789B2 (en) | 1986-03-31 | 1986-03-31 | Mass spectrometric method by laser ionization mass spectrometer |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0756789B2 (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5118937A (en) * | 1989-08-22 | 1992-06-02 | Finnigan Mat Gmbh | Process and device for the laser desorption of an analyte molecular ions, especially of biomolecules |
| JPH0456057A (en) * | 1990-06-22 | 1992-02-24 | Nippon Telegr & Teleph Corp <Ntt> | Mass spectrometer for laser ionized neutral particle |
| JPH0458447A (en) * | 1990-06-25 | 1992-02-25 | Nippon Telegr & Teleph Corp <Ntt> | Laser ionization neutral particle mass analytical device |
| US6953928B2 (en) * | 2003-10-31 | 2005-10-11 | Applera Corporation | Ion source and methods for MALDI mass spectrometry |
| US7435951B2 (en) * | 2005-06-08 | 2008-10-14 | Agilent Technologies, Inc. | Ion source sample plate illumination system |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5748316A (en) * | 1980-09-09 | 1982-03-19 | Giken Eng:Kk | High speed dehydrator |
| JPS60121664A (en) * | 1983-12-02 | 1985-06-29 | Murata Mfg Co Ltd | Mass spectrometer |
-
1986
- 1986-03-31 JP JP61076275A patent/JPH0756789B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPS62232847A (en) | 1987-10-13 |
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