JP3038839B2 - High frequency inductively coupled plasma mass spectrometer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a high frequency inductively coupled plasma mass spectrometer (hereinafter abbreviated as “ICP-MS”), and more specifically, to improve the operability of a sample introduction unit. ICP-MS.

<Prior art> ICP-MS excites a sample using high frequency inductively coupled plasma, guides generated ions to a mass spectrometer through an interface composed of a nozzle and a skimmer, and electrically detects the amount of the ions. By performing accurate measurement, the element to be measured in the sample is analyzed with high accuracy.
FIG. 5 is a diagram illustrating the configuration of a conventional example of such an ICP-MS. In this figure, an outer tube 1b and an outermost tube 1c of a plasma torch 1 are supplied with argon gas from an argon gas supply source 3 via a gas controller 2, and an inner tube 1a is supplied with a sample tank 4
The sample inside is atomized by the nebulizer 5 and then carried in by argon gas. A high-frequency power is supplied to a high-frequency induction coil 6 wound around the plasma torch 1 by a high-frequency power supply 10, and a high-frequency magnetic field (not shown) is formed around the coil 6. On the other hand, the inside of the fore chamber 11 sandwiched between the nozzle 8 and the skimmer 9
The pressure is reduced to, for example, 1 Torr by the vacuum pump 12.
Also, an ion lens system 14a,
14b, the inside of the center chamber 13 is decompressed to, for example, 10 ⁻⁴ Torr by the first oil diffusion pump 15, and a mass filter (for example, a quadrupole mass filter) 16 is provided.
The inside of the rear chamber 17 containing the oil is a second oil diffusion pump
For example, the pressure is reduced to 10 ⁻⁵ Torr.

When electrons or ions are implanted in the argon gas in the vicinity of the high-frequency magnetic field in this state, the high-frequency inductively coupled plasma 7 is instantaneously generated by the action of the high-frequency magnetic field. The ions in the plasma 7 pass through the nozzle 8 and the skimmer 9 and are then focused through the ion lens systems 14a and 14b.
Here, as the ion lens systems 14a and 14b, for example, a double quadrupole lens that blocks light from the high-frequency inductively coupled plasma 7 and passes only ions is used, and the ions that have passed through the ion lens system are mass-filtered. The detection element analysis value in the sample is obtained by being guided to the secondary electron multiplier 19 through 16 and detected, and the detection signal is sent to the signal processing unit 20 and calculated and processed. Has become.

On the other hand, in ICP-MS, to maintain high analytical performance,
It is very important to align the axis of the plasma torch with the axis of the nozzle within a range of about ± 0.1 mm. For this reason, conventionally, a sample is constantly introduced, and while moving the plasma torch in the X-axis direction and the Y-axis direction so that the center of the flow of the sample flowing in the plasma torch coincides with the center of the nozzle, the sample The above-mentioned axis alignment is performed so that the component signal of the above-mentioned component becomes maximum.

<Problems to be Solved by the Invention> However, the axis alignment method based on the component signal in the sample as described above can be used only in the case of solution analysis in which the sample is constantly introduced (the so-called nebulizer method). hand,
There is a drawback that it cannot be used in the case of a laser ablation method for introducing a sample transiently or a heating vaporization introducing method.

For this reason, conventionally, after adjusting the torch position by the above-mentioned nebulizer method, the nebulizer and the spray chamber provided behind the plasma torch are removed, and another sample introduction device is connected. However, in this method, the position of the plasma torch is often moved during the operation, and there is a major drawback that the performance (in particular, sensitivity) of ICP-MS cannot be sufficiently brought out. In addition, when a substance for axis alignment is mixed into a carrier gas having almost the same distribution as the sample components in the high-frequency induction plasma,
A standard gas generator and a flow control device for standard gas are required, and there is also a disadvantage that peripheral equipment must be changed on a large scale or newly installed simply by slightly changing the sample introduction method to adjust the equipment. there were.

The present invention has been made in view of the drawbacks of the conventional example, and an object of the present invention is to provide an ICP capable of easily aligning a plasma torch with a nozzle even when a sample is transiently introduced. -To provide MS.

<Means for Solving the Problems> A feature of the present invention that solves the above problems is that ions generated by exciting a sample using high-frequency inductively coupled plasma are mass-transduced through an interface including a nozzle and a skimmer. In an analyzer for analyzing an element to be measured in the sample by guiding to and detecting an analyzer detector, a sample introduction device and a gas mixing device are provided, and these devices are arranged in parallel or between a gas regulator and a plasma torch. While connected in series, the carrier gas from the gas regulator is configured to be guided to these devices, and at the time of axis alignment, the carrier gas supplied from the gas regulator is passed through the gas mixing device to the plasma torch. Guiding and introducing the atmosphere into the carrier gas in the gas mixing device, the position of the plasma torch and the nozzle Is to adjust.

<Example> Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is an explanatory view of a main part showing a main part of an embodiment of the present invention. In the figure, the same symbols as those in FIG. 5 are used with the same meanings, and duplicate explanations are omitted here. 24 is a sample introduction device, 25 is a gas mixing device, 26 is the first to fourth connection ports 26a.
26d and a first switching valve having a blind plug 26e;
Is a second switching valve having connection ports 27a to 27d and blind plug 27e. FIG. 2 is a cross-sectional view of a specific configuration of the gas mixing device, in which 21 is a connector, 22a and 22b are sealing members made of, for example, O-rings, 23 is a carrier gas introduction tube leading to a plasma torch, and 51 is a nebulizer An inner tube 52 is a capillary tube whose tip is open to the atmosphere.

In the embodiment of the present invention having such a configuration, at the time of axis alignment, the switching valves 26 and 27 are brought into the connection state indicated by the broken lines in FIG. In this state, the carrier gas supplied from the gas controller 2 is supplied to the first and fourth connection ports 26a and 26a of the first switching valve 26.
d → the gas mixing device 25 → the plasma torch 1 via the third and second switching valves 27c and 27b of the second switching valve 27. At the time of analysis, the switching valves 26 and 27 are connected to the solid line in FIG.
The carrier gas supplied from the gas controller 2 is supplied to the first and second connection ports 26a and 26b of the first switching valve 26 → the sample introduction device 2
4 → the plasma torch 1 via the first and second switching valves 27a and 27b of the second switching valve 27. In this way, the sample guided to the inner tube 1a of the plasma torch 1 is subjected to the analysis of the components to be measured in the same manner as in the conventional example described in detail with reference to FIG.

By the way, at the time of the shaft alignment, the carrier gas (for example, Aγ gas) introduced into the gas mixing device 25 through the fourth connection port 26d of the first switching valve 26 passes through the nebulizer 5 in FIG. Then, it is guided to the carrier gas introduction tube 23. For this reason, the so-called ejector effect of the nebulizer 5 causes the atmosphere to flow into the capillary tube 52.
Then, the liquid is sucked into the connector 21 through the inner pipe 51, and then guided to the carrier gas introduction tube 23. Further, the carrier gas and the atmosphere guided to the carrier gas introduction tube 23 in this manner are supplied to the third and second switching valves 27c and 27c of the second switching valve 27.
The plasma torch 1 is reached via 27b. Here, since the flow rate of the carrier gas is kept constant by the gas controller 2, the amount of air introduced into the plasma torch 1 is also kept constant. In addition, the amount of air introduced is
By changing the inner diameter and length of the sample, it can be set to an arbitrary amount. Usually, a sample introduction pipe for introducing a solution can be used as it is as the capillary tube 52.

As described above, the atmosphere is introduced into the carrier gas, and the positions of the torch and the nozzle are adjusted while continuously measuring the components (for example, carbon) in the atmosphere. In addition, the ICP-M
Tuning of other parameters of S is also possible, and as a result, the original performance (for example, component qualitative ability) of ICP-MS can be sufficiently exhibited.

FIG. 3 and FIG. 4 are explanatory diagrams of a main part configuration of another embodiment of the present invention. In the drawings, reference numeral 28 denotes first to fourth connection ports 28a to 28d.
And a switching valve 29 in which the internal flow path is alternately switched between a solid line connection state and a broken line connection state, and 29 is an on-off valve mounted on the capillary tube 52. The embodiment as shown in FIGS. 3 and 4 is used when the air may be temporarily mixed into the sample introduction system, such as laser ablation.

<Effect of the Invention> As described in detail above, the present invention uses a high-frequency inductively coupled plasma to excite a sample and guide ions to a mass spectrometer detector via an interface including a nozzle and a skimmer to detect the ions. In the analyzer for analyzing the element to be measured in the sample, a sample introduction device and a gas mixing device are provided, and these devices are connected in parallel or in series between a gas controller and a plasma torch, and the gas controller And the carrier gas supplied from the gas controller is guided to the plasma torch via the gas mixing device at the time of axis alignment, and the carrier gas is introduced into the gas mixing device. Is configured to introduce air into the
The positions of the plasma torch and the nozzle are adjusted.

Since the tuning component is mixed into the sample line, there is an advantage that the axis alignment can be performed easily and accurately as compared with the conventional example. In addition, since a commonly used nebulizer is used, there is an advantage that a flow control mechanism is not required in the sample introduction line.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a main part of an embodiment of the present invention, FIG. 2 is a cross-sectional view of a specific structure of a gas mixing device, FIG. 3 and FIG. FIG. 5 is an explanatory diagram of the overall configuration of the ICP-MS. 1 ... plasma torch, 3 ... argon gas supply source, 4 ... sample tank, 5 ... nebulizer, 7 ... high frequency inductively coupled plasma, 8 ... nozzle, 9 ... skimmer, 16 ... mass filter, 19 …… Secondary electron multiplier, 20 …… Signal processing unit 21… Connectors 22a, 22b …… Seal member, 23 …… Carrier gas introduction tube, 52 …… Capillary tube 24 …… Sample introduction device, 25 …… Gas mixing device, 26, 27… switching valve,

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) H01J 49/00-49/48 G01N 21/00 G01N 27/62

Claims (1)

(57) [Claims] 1. An element to be measured in a sample is analyzed by introducing ions generated by exciting a sample using a high-frequency inductively coupled plasma to a mass spectrometer detector through an interface composed of a nozzle and a skimmer. In a spectrometer, a sample introduction device and a gas mixing device are provided, these devices are connected in parallel or in series between a gas controller and a plasma torch, and a carrier gas from the gas controller is guided to these devices. At the time of axis alignment, the carrier gas supplied from the gas controller is guided to the plasma torch via the gas mixing device, and the gas mixing device introduces air into the carrier gas. A high-frequency inductively coupled plasma mass spectrometer, wherein the positions of the plasma torch and the nozzle are adjusted.