JPH02176458A - Inductively coupled plasma mass spectrometer - Google Patents

Abstract

PURPOSE:To ensure the alignment of the axis of a torch readily and to make it possible to perform the optimum tuning of the mass by mixing a specified amount of standard gas into carrier gas, and introducing the mixed gas to the plasma torch. CONSTITUTION:A flow rate control device 22 is controlled at an ON state and a flow rate control device 24 is controlled at an OFF state with a controller 26 during analysis. Therefore, the flow rate of Ar gas from an Ar gas supply source 21 is adequately adjusted with the device 22. The Ar gas is supplied into a inductively coupled plasma mass spectrometer 28 through a fluid mixer 25 and a specimen introducing device 27. When a specimen is tuned, both devices 22 and 24 are controlled at the ON state. Standard gas is supplied from a supplying source 23 together with the Ar as the carrier gas. The alignment of the axis of a plasma torch and the better tuning of an ion lens can be performed for a wider range of mass by the combination of the standard gas (single element gas or other gas).

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a high-frequency inductively coupled plasma mass spectrometer, and in particular, to a high-frequency inductively coupled plasma mass spectrometer that improves the alignment method between a plasma torch and a nozzle of a mass spectrometer detection section. Concerning coupled plasma mass spectrometry.

<Prior art> A high-frequency inductively coupled plasma mass spectrometer uses high-frequency inductively coupled plasma to excite a sample, guide the generated ions to a mass spectrometer through an interface consisting of a nozzle and a skimmer, and electrically detect them. By precisely measuring the amount of ions, the element to be measured in the sample is analyzed with high precision. FIG. 2 is an explanatory diagram of the configuration of a conventional example of such a high frequency inductively coupled plasma mass spectrometer.

In this figure, argon gas is supplied to the outer chamber 1b and the outermost chamber IC of the plasma torch 1 from an argon gas supply source 3 via a gas regulator 2, and to the inner chamber 1a, a laser beam is applied to the sample in the sample tank 4. A high-frequency induction coil 6 wound around a plasma torch 1 is supplied with a high-frequency current by a high-frequency power source 10, and a sample vaporized by irradiation with a laser beam from a light source 5 is carried in by argon gas. is applied, and a high frequency magnetic field (not shown) is formed around the coil 6. On the other hand, the inside of the forechamber book #: 11 sandwiched between the nozzle 8 and the skimmer 9 is suctioned by a vacuum pump 12 to, for example, IT or r.

Furthermore, an ion lens 14 is provided in the center chamber 13.
a, 14b are provided, and the interior of the center chamber 13 is heated by a first oil diffusion pump 15 to, for example, 1O
-4 Torr, and a rear chamber 1 containing a mass filter (e.g. quadruple diameter mass filter) 16
7, for example, 10-'T by the second oil diffusion pump 18.
It is attracted to orr.

When electrons or ions are implanted in the argon gas in the vicinity of the high frequency magnetic field in this state, high frequency induced plasma 7 is instantaneously generated by the action of the high frequency magnetic field. The ions in the plasma 7 pass through a nozzle 8 and a skimmer 9, are focused between ion lenses 14a and 14b (or a doublet quadruple diameter lens), and then pass through a mass filter 16 to increase secondary electrons. The detection signal is sent to the signal processing unit 20 for calculation and processing.
By processing, the analysis value of the element to be measured in the sample can be obtained.

By the way, in the method of atomizing the sample solution with a nebulizer and introducing it into the plasma torch, a standard sample solution with a known component concentration is continuously introduced, and the X-axis of the plasma torch is adjusted so that the signal intensity of the component to be measured is maximized. All you had to do was shift the y-axis and the y-axis.

On the other hand, there is a laser ablation method in which a sample is irradiated with a laser to heat and vaporize the sample, and an ET method in which the sample is vaporized by passing electricity through tungsten or the like installed in a sample cell.
V (Electro 'rhermal Vapa
For analysis methods that do not allow continuous introduction of the sample, such as the solution method, after aligning the torch axis with the solution method, remove the nebulizer spray chamber without moving the torch position, and insert the sample tube into the plasma. It was designed to be connected to the torch, which caused the axis of the plasma torch to shift slightly. Also, the only way is to roughly align the axis while watching the high-frequency inductively coupled plasma, and A>'2,C.

Axis alignment using a background signal such as N has the drawback that the axis cannot be aligned to the center of the high frequency inductively coupled plasma where the detected signal is maximum. In addition, since the signal can only be obtained for a short time, the tuning of the ion lens system uses the background signal A)'・A)",
There was no choice but to use Aro'', O'', N'', etc., and it was not possible to make the optimum adjustment for the target element.

<Problems to be Solved by the Invention> The present invention has been made in view of the problems of the prior art. The object of the present invention is to provide a high frequency inductively coupled plasma mass spectrometer that can be easily and reliably used.

Means for Solving the Problems> The present invention uses high-frequency inductively coupled plasma generated by a plasma torch to excite a sample, introduces the generated ions into a vacuum, and passes them through an ion optical system and a mass filter to a mass spectrometer detector. In an analyzer that analyzes elements to be measured in a sample by guiding and detecting them, an argon gas supply source, a standard gas supply source, a flow rate controller for argon gas, a flow rate controller for standard gas, and a fluid The above problem is solved by providing a mixer, a controller for controlling the flow rate control device, and a sample introducing section, and mixing a certain amount of standard gas into the carrier gas and guiding it to the plasma 1--1. be.

<Example> Hereinafter, the present invention will be explained in detail using sections. 1st
The figure is an explanatory diagram of the main part configuration of the embodiment of the present invention, and in the figure, 21
is an argon gas supply source, 22 is a flow rate control device for argon gas, such as a mass flow controller, 23 is a standard gas supply source, 24 is a flow rate control device for standard gas, 25
is a fluid mixer having connection ports 25a to 25c, 26 is a controller that controls the flow rate controllers 22 and 24, and 27 is a sample cell or ETV for laser ablation.
28 is a high frequency inductively coupled plasma mass spectrometer. The overall configuration and operation of the high-frequency inductively coupled plasma mass spectrometer are the same as those of the conventional example described in detail with reference to FIG. 2, and therefore redundant explanation will be omitted here.

In the embodiment of the present invention having the essential configuration as shown in FIG. 1, only argon gas is supplied as a carrier gas during analysis. That is, the flow rate control device 2224 is controlled by the controller 26, and the flow rate control unit! 22 is turned on, the flow rate control device 24 is turned off. At this point, the argon gas from the argon gas supply source 21 is
, 7F11/min, and is supplied to the fluid mixer 25, and then passed through the sample introduction device 27 and supplied to the high frequency inductively coupled plasma mass spectrometer 28. On the other hand, during sample tuning, a mixed gas of argon gas and standard gas is supplied as a carrier gas. That is,
Flow control devices 22 and 24 are controlled by controller 26 and both are turned on. Therefore, the argon gas from the argon gas supply source 21 is
The fluid mixer 25 is adjusted to a flow rate of 7Wi'/min.
At the same time, the standard gas from the standard gas supply source 23 is adjusted to a flow rate of V2 ml/min by the flow rate controller 24, and is supplied to the fluid mixer 25 and mixed to form the stream 1.
V7Fjl/min (i.e. v1+V2=V)
, and then supplied to a high frequency inductively coupled plasma mass spectrometer 28 through a sample introduction device 27. In this state, the standard gas can be a single element gas (such as a single element gas <
H31 etc.). As a result, for example, when using CH3I, all you have to do is align the plasma torch and tune the ion lens while observing the signals that stabilize at 129 amu and 131 amu.Also, you can combine several I heavy gases to make them appear at the same time. By switching and introducing , better tuning becomes possible over a wide mass range.

<Effects of the Invention> According to the present invention as described in detail above, torch combinations can be easily and reliably performed even in analysis methods that can only obtain transient signals, such as laser ablation and BTV measurements. The advantage is that it can be done. Furthermore, since tuning can be performed at a desired mass number, optimal tuning for that mass is possible.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the main part configuration of an embodiment of the present invention, and FIG. 2 is an explanatory diagram of the overall configuration of a high frequency inductively coupled plasma mass spectrometer. 1... Plasma torch, 2... Flow rate control unit, 3... Argon gas supply source, 4...
...Sample tank, 5...Laser light source, 6...
...High frequency induction coil, 7...High frequency inductively coupled plasma, 8...Nozzle, 9...Skimmer 11...Fore chamber 13...
・Center chamber 16... Mass filter, 17... Rear chamber 20... Signal processing section,

Claims (1)

[Claims] The sample is excited using high-frequency inductively coupled plasma generated by a plasma torch, and the generated ions are introduced into a vacuum and guided to a mass spectrometer detector through an ion optical system and a mass filter for detection, thereby detecting the element to be measured in the sample. An analyzer for analysis includes an argon gas supply source, a standard gas supply source, a flow rate control device for argon gas, a flow rate control device for standard gas, a fluid mixer, and a controller that controls the flow rate control device. A high frequency inductively coupled plasma mass spectrometer, comprising: a sample introduction section, and a carrier gas mixed with a certain amount of a standard gas and introduced into the plasma torch.