JPH0731496Y2 - ICP mass spectrometer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to an apparatus used in ICP (high frequency inductively coupled plasma) mass spectrometry.

[Outline of device]

In the mass spectrometric measurement, if there is an extremely large excessive intensity input such as a sample with a high concentration, the maximum instantaneous intensity is assumed in the case of the mass spectrum profile measurement in order to protect the channeltron. Is
Assuming a strength value equivalent to that, a protection mechanism is installed to prevent further strength output as the maximum allowable strength output value converted into CPS in each measurement. At the same time, while not measuring, the channel axis is protected by setting the mass axis to a standby mass number with a low output and waiting.

As the output intensity value when the allowable value is exceeded, the maximum allowable intensity value set for each is output.

[Conventional technology and problems to be solved by the invention]

Since the conventional ICP mass spectrometer does not have a channeltron protection mechanism against excessive intensity input, it can be adequately adapted for normal normal use, but due to incorrect operation etc., there was an input that exceeded its maximum allowable value. In this case, impurities and the like taken in along with the ions adhere to the inner wall thereof, which hinders the generation of electrons and remarkably shortens the life of the channeltron.

For this reason, the purpose of the present invention is to provide a protection device for preventing excessive input from reaching the channeltron.
It is to provide an ICP mass spectrometer.

[Means for Solving the Problems]

In order to achieve the above-mentioned object, the main means adopted by the present invention are: a discriminator connected to the output side of a channeltron, an integrator connected to this, and an output of the integrator. The ICP is equipped with a protection means that compares the input input value with a preset input value and issues a measurement stop command to the mass spectrometric section when the integrator output exceeds the input input value.
It is a mass spectrometer.

[Action]

Ions that have passed through the mass spectrometric section from the ICP section are introduced into the channeltron. Then, the collision with the channeltron wall is repeated and the electrons are converted into electrons. Thus, the output of the channeltron is sent to the integrator circuit after the noise is removed by the discriminator. The output integrated by the integrating circuit is introduced into the protection circuit of the present invention.

The protection circuit is preset with a certain allowable input value and is compared with the output of the introduced integrator. And
When the input integrated value exceeds the set value, a stop command is issued to the mass spectrometric unit to stop the measurement.

As a result, even if an excessive amount of ions are output from the ICP torch part for some reason, it is prevented from reaching the channeltron, so that the channeltron can be prevented from being contaminated and problems such as measurement inability can be avoided.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 is a schematic configuration diagram of an ICP mass spectrometer to which the present invention is applied, 1 is a channeltron for the purpose of protection, 2 is a mass spectrometer, 3 is an ion lens, 4 is a skimmer cone, and 5 is Sampling cone, 6 is the ICP torch part.

In FIG. 1, the ions sprayed from the ICP torch unit 6 pass through a sampling cone 5, a skimmer cone 4 and an ion lens 3 which form an ion attraction unit, and further pass through a mass analysis unit 2 to a channeltron 1. Sent in.

FIG. 2 shows an embodiment for explaining the protection mechanism of the present invention, in which 21 is a preamplifier, 22 is a discrete amplifier, 23 is an integrating circuit, and 24
Is A / D and 25 is a CPU.

At the time of measurement, the CPU preliminarily commands the measured mass number to the mass spectrometer each time, the mass spectrometer sets the measured mass number by changing the applied voltage, and makes only the mass ions reach the channeltron.

The ions taken into the channeltron 1 collide with the inner wall of the channeltron, generate electrons while repeating the collision, are amplified to about 10 ⁶ CPS, and are sent to the preamplifier.
Furthermore, in order to remove noise with the discriminating amplifier, a signal with a certain discriminating level or less (variable) or a peak value of 3 msec or less is removed (see FIG. 3).

After that, those consecutively input signals are integrated and CP
Send to U as intensity output.

The CPU receives these intensity outputs, converts them into CPS, and sets them to a certain level.
If an intensity of CPS or more (variable) is detected, it is regarded as an abnormal input, and the CPU (software) stops the measurement of its mass immediately to protect the channeltron and does not perform the subsequent mass measurement. Issue a control command.

This prevents a large amount of ions from being taken into the channeltron.

Since there is always an input to the channeltron even when the measurement is not in progress, a relatively low input standby mass number is set in the CPU to implement it as an additional function of the protection mechanism.

In mass spectrum profile measurement, the allowable intensity value is assumed from its maximum instantaneous intensity, allowing the user to set the intensity value freely, and is initialized when the device is started and the program is started by the computer. It

During the measurement, the mass number in a certain range will be repeatedly scanned and measured.If an element component with an extremely high concentration appears at a certain mass at that time, if this value exceeds the allowable strength value, this protection mechanism will work. , The measured value of the sampled mass channel is output as a setting allowable value, the measurement is stopped, and the load on the channeltron is reduced.

Similarly, in the quantitative integration measurement, the CPS-converted allowable intensity value for integration value different from that for profile measurement is set as system information. When measuring, if the data integration value of several channels in one mass divided into eight with the center of mass of each single element or multiple elements exceeds the set allowable strength value, the allowable strength value is calculated as data. It outputs and stops the measurement of the channel measured at that time and protects the channeltron. As is clear from the above description, by providing the protection mechanism both during the measurement and during the standby, it is possible to suppress the deterioration and the performance deterioration of the channeltron.

[Effect of device]

Excessive input to the Channeltron is not a problem during normal use, but it is often a burden when handling extremely high-concentration samples or when performing special operations such as instrument adjustment. Calling does not always happen.
Repeated application of these burdens leads to a rapid decline in device performance. Therefore, by setting the allowable input value of the channeltron and suppressing excessive input,
A highly reliable ICP mass spectrometer can be obtained.

[Brief description of drawings]

FIG. 1 is a conceptual configuration diagram of an ICP mass spectrometer targeted by the present invention, FIG. 2 is a block diagram illustrating an embodiment of the present invention,
FIG. 3 is a diagram for explaining the operation of the discriminator shown in FIG. 1 ... Channeltron 2 ... Mass spectroscope 3 ... Ion lens 4 ... Skimmer cone 5 ... Sampling cone 6 ... ICP torch 21 ... Preamplifier 22 ... Discreamp 23 ... Integrator circuit 24 ... A / D 25 …… CPU

Claims (1)

[Scope of utility model registration request] 1. An ICP torch part for generating ions, a sampling cone for drawing in the ions, a skimmer cone and an ion lens, and the sampling cone,
A mass spectrometer that passes only a predetermined mass of the ions that have passed through a skimmer cone and an ion lens, and a CPU that sets a predetermined mass of the ions that passes through the mass analysis unit
A channeltron that detects the ions that have passed through the mass spectrometer; a discreamp that removes noise from the output from the channeltron; an integrator circuit that integrates the output from the discreamp; and an integrator circuit. In an ICP mass spectrometer comprising a CPU for inputting an output, the CPU, when measuring ions of a predetermined mass, based on an allowable intensity value of the output of the set integration circuit, the output of the integration circuit is the allowable A means for outputting a control command to immediately stop the measurement of the ion mass when the intensity is exceeded,
When the ICP mass spectrometer is in a standby state for measurement, it has means for setting a predetermined mass so that ions having a mass number such that a relatively low input is passed through the mass spectrometer.
ICP mass spectrometer.