JPH0744029B2 - Liquid Chromatograph-Atmospheric Pressure Mass Spectrometer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to atmospheric pressure ionization (Atomospheric Pressure Ioni).
The present invention relates to an atmospheric pressure ionization mass spectrometer having an ionization function utilizing a molecular reaction such as chemical ionization, and particularly to an improvement in the case of decomposing molecular ions to detect negative ions.

[Conventional technology]

A liquid chromatography directly coupled mass spectrometer (hereinafter abbreviated as LC / API mass spectrometer) utilizing atmospheric pressure ionization (hereinafter abbreviated as API) is a conventional electron impact ionization (hereinafter abbreviated as EI). ) Is used in the gas chromatograph direct coupling mass spectrometer (hereinafter abbreviated as GC mass spectrometer), it uses a gentle ionization means with less impact in its ionization mechanism, so it should be decomposed when ionizing the sample. It has few features and is easy to observe molecular ions, and has many findings that cannot be obtained by a GC mass spectrometer. On the other hand, on the other hand, although molecular ions are observed, the amount of information is small because the number of decomposed ions is small, which is a difficulty in knowing the molecular structure and the like.

Therefore, the current measurement method is as shown in FIG. 1, in which the electrode 1 provided between the ionization section and the intermediate pressure area section is used.
(This electrode is preferably a micropore electrode, and is also referred to as a first micropore electrode hereinafter), and an electrode 2 (this electrode is a micropore electrode) provided between the intermediate pressure region and the analysis unit. And a voltage (hereinafter, abbreviated as “drift voltage”) that satisfies “first pore electrode voltage> second pore electrode voltage” between the first and second pore electrodes. ) Is applied to accelerate the molecular ions in the intermediate pressure region,
By colliding with a neutral molecule, the molecular ion is intentionally decomposed, and the decomposed ion is introduced into the analysis section to obtain much information.

[Problems to be solved by the invention]

However, in the case of measuring negative ions, when the drift voltage of the first pore electrode voltage> the second pore electrode voltage is applied, the negative ions undergo acceleration opposite to the direction of the analysis section and pass through the second pore electrode. Cannot be done, and therefore negative ions cannot be measured.

An object of the present invention is to provide an LC / API mass spectrometer that can introduce a lot of information by introducing negative ions into the analysis section as well as positive ions.

[Means for solving problems]

The above-mentioned object is provided with a drift voltage switching device and a driving device for operating the drift voltage switching device, and "first pore electrode voltage">"second
"Pore electrode voltage" or "first pore electrode voltage"<"second"
This is achieved by selectively applying one of the "pore electrode voltage" drift voltages.

[Action]

The drift voltage switching device of the present invention, in the positive ion measurement mode by switching the connection between the drift power supply and the first fine hole electrode and the second fine hole electrode in the positive ion measurement mode and the negative ion measurement mode, respectively. Applies a drift voltage such that “first pore electrode voltage> second pore electrode voltage”, and in the negative ion measurement mode, “first pore electrode voltage <
It operates so as to apply a drift voltage that is the “second pore electrode voltage”.

This switching is preferably a control data processing device for controlling the LC / API mass spectrometer or collecting data, or a drive circuit is operated by a signal from a measurement mode switching switch, and a relay of the drift voltage switching circuit is operated. It is done by doing.

This makes it possible to decompose and measure molecular ions in both positive and negative ion measurements.

〔Example〕

 Hereinafter, embodiments will be described with reference to the drawings.

FIG. 2 is a diagram showing the configuration of an embodiment of a drift voltage switching device for measuring negative ions according to the present invention. In this embodiment, one drift power supply 3 in a floating state is used, and a drift voltage switching circuit 4 and its driving circuit 5 apply a voltage between the first fine pore electrode 1 and the second fine pore electrode 2. It is characterized by inverting the voltage.

The drift voltage switching circuit 4 is composed of four relays, and two relays 6 and 7, and two relays 8 and 9 operate. For example, when performing positive ion measurement, the relay 6 and the relay 7 operate simultaneously, and a drift voltage that satisfies “first pore electrode voltage> second pore electrode voltage” is applied. At this time, the relays 8 and 9 do not operate and the contacts are open. On the contrary, when measuring negative ions, the relay 8 and the relay 9 are operated to apply a drift voltage such that “first pore electrode voltage <second pore electrode voltage”.
At this time, the relays 6 and 7 do not operate and the contacts are in an open state.

The drive circuit 5 is a circuit for operating four relays 6, 7, 8 and 9 two by two in response to signals from the control data-processing device 10 or the positive / negative ion measurement mode switching switch 11. For example, if a "H" level signal is sent from the control data processor 10 as the positive ion measurement mode, the relay
Relays 8 and 9 operate when signals 6 and 7 are sent and "L" level signals are sent in the negative ion mode.

Since the drift power source 3 normally operates in a state of floating at an ion acceleration voltage (about 3 KV to 4 KV), it is in a floating state, and the collision energy for decomposing molecular ions differs depending on the sample to be measured. , The drift voltage can be changed by the drift voltage setting dial 12 (0V ~ 250
V) is ready for you.

In this embodiment, only the switching of the drift power source 3 is described, but in order to detect the molecular ion or the ion decomposed from the molecular ion in the ion detector 13, the needle power source 18 is not operated in the positive ion measurement mode. A voltage of 5 KV to 10 KV is applied to the needle 21, and a voltage of -5 KV to -10 KV is applied in the negative ion measurement mode. Further second
The ion acceleration voltage applied to the pore electrode 2 is 3 KV to 4 KV in the positive ion measurement mode and −3 KV in the negative ion measurement mode.
A voltage of -4 KV is applied, and in the analysis unit, positive ions can be measured in the positive ion measurement mode, and negative ions can be measured in the negative ion measurement mode. Needless to say. Moreover, the application of these voltages or the setting of the measurement state are both performed in synchronization with the signal from the control data processing device 10 or the positive / negative ion measurement mode switching switch.

〔The invention's effect〕

According to the present invention, it is possible to switch and apply a positive drift voltage and a negative drift voltage between the first fine pore electrode and the second fine pore electrode with one drift power supply, and also in the measurement of negative ions. Much information can be obtained similar to positive ion measurements.

[Brief description of drawings]

FIG. 1 is a diagram showing a method of applying a drift voltage when measuring positive ions, FIG. 2 is a diagram showing a drift voltage switching device of the present invention, FIG. 3 is a diagram showing a measurement example of positive ions, and FIG. The figure is a diagram showing an example of measurement of negative ions. 1 ... First pore electrode, 2 ... Second pore electrode, 3 ... Drift power supply, 4 ... Drift voltage switching circuit, 5 ... Driving circuit, 6,7,8,9 ... Relay, 10 ...... Control data processing device, 11 …… Switch for switching positive / negative ion measurement mode,
12 …… Drift voltage setting dial, 13 …… Ion detector, 14 …… Analysis tube, 15 …… Magnet power supply, 16 …… Magnet coil, 17 …… Ion acceleration power supply, 18 …… Needle power supply, 19 …… Liquid chromatograph, 20 ... Magnet.

Claims (1)

[Claims] 1. A sample from a liquid chromatograph is ionized in an ionization section at about atmospheric pressure, and is ionized via an intermediate pressure section.
It is configured to lead to a high-vacuum analysis unit for mass spectrometry,
Furthermore, a first electrode provided between the ionization section and the intermediate pressure section, a second electrode provided between the intermediate pressure section and the analysis section, and a first electrode provided in the analysis section. Three
In the liquid chromatograph-atmospheric pressure mass spectrometer, the voltage of the second electrode is lower than the voltage of the third electrode, and the voltage of the first electrode is the second electrode.
First voltage supply means capable of supplying a negative voltage to the first electrode and the second electrode so as to be lower than the voltage of the third electrode, and the voltage of the second electrode is the third electrode. Second voltage capable of supplying a positive voltage to the first electrode and the second electrode such that the voltage of the first electrode is higher than that of the first electrode and the voltage of the first electrode is higher than the voltage of the second electrode. Voltage supply means and switching means for selectively switching the voltage from one of the first voltage supply means or the second voltage supply means to be supplied to the first electrode and the second electrode. Liquid chromatography-atmospheric pressure mass spectrometer characterized by having