JP2009110853A - Laser ablation inductively coupled plasma mass spectroscope - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laser ablation inductively coupled plasma mass spectroscope capable of reducing variations in ion intensity. <P>SOLUTION: The laser ablation inductively coupled plasma mass spectroscope 1 includes a laser ablation part 3 in which laser is irradiated on a test piece to vaporize the test piece and to make it a test piece gas and the test piece gas is emitted together with a carrier gas, an inductively coupled plasma mass spectrometry part 5 in which the test piece is ionized with the inductively coupled plasma as an ionizing source and mass spectrometry is carried out, and a mixing part 7 having a mixing chamber which is installed between a laser ablation part and the inductively coupled plasma mass spectrometry part and in which the test piece gas and the carrier gas are uniformly mixed. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a laser ablation inductively coupled plasma mass spectrometer.

  One of the mass spectrometry methods is inductively coupled plasma mass spectrometry. In such an analysis method, a solid sample is dissolved, converted into a mist, introduced into a high-temperature inductively coupled plasma, and the sample is ionized. And the obtained ion is introduce | transduced into a mass spectrometer, and qualitative quantification is performed through the separation analysis according to mass to charge ratio.

In addition, as understood from Patent Document 1, among inductively coupled plasma mass spectrometers, a laser ablation inductively coupled plasma mass is used in which a solid sample is directly irradiated with a laser and vaporized using a laser ablation system. There is also an analyzer (LA-ICP-MS).
Japanese Patent Laid-Open No. 11-51904

  By the way, in such a laser ablation inductively coupled plasma mass spectrometer, it is desired to reduce variations in ion intensity. An object of the present invention is to provide a laser ablation inductively coupled plasma mass spectrometer capable of reducing variations in ion intensity.

  In order to solve the above-described problems, a laser ablation inductively coupled plasma mass spectrometer according to the present invention irradiates a sample with a laser, vaporizes the sample to form a sample gas, and releases the sample gas together with a carrier gas. And an inductively coupled plasma mass analyzer that ionizes a sample using a dielectric coupled plasma as an ionization source to perform mass analysis, and is provided between the laser ablation unit and the inductively coupled plasma mass analyzer, and a sample gas and a carrier gas And a mixing section having a mixing chamber for performing uniform mixing with the mixing chamber.

  Preferably, the volume of the mixing chamber is 50 to 100 [ml].

  The mixing unit includes a resin container having an opening and a lid member that closes the opening, the gas inlet receiving the sample gas and the carrier gas discharged from the laser ablation unit in the lid member, and the mixing You may comprise so that the gas outlet which discharge | releases the sample gas and carrier gas received in the chamber to the said inductively coupled plasma mass spectrometry part may be provided.

  The vector component in the gas traveling direction at the gas outlet may include a vector component in a direction opposite or orthogonal to the vector of the gas traveling direction at the gas inlet.

  The gas inlet is inserted with the downstream end of the introduction pipe whose upstream end is communicated with the laser ablation section, and the gas outlet is connected with the inductively coupled plasma mass spectrometer at the downstream end. The portion of the introduction pipe that extends from the lid member into the mixing chamber is longer than the portion of the lead-out pipe that extends from the lid member into the mixing chamber. You may comprise as follows.

  According to the present invention, the sample gas is not supplied directly from the laser ablation unit to the inductively coupled plasma mass analyzing unit, but is introduced into the mixing chamber and then supplied to the inductively coupled plasma mass analyzing unit. In addition, after the carrier gas is uniformly mixed in the mixing chamber, the carrier gas is supplied to the inductively coupled plasma mass spectrometer, thereby reducing variations in ion intensity.

  The other features of the present invention and the operational effects thereof will be described in more detail with reference to the accompanying drawings.

  Embodiments according to the present invention will be described below with reference to the accompanying drawings. In the drawings, the same reference numerals indicate the same or corresponding parts.

  FIG. 1 is a diagram showing a configuration of a laser ablation inductively coupled plasma mass spectrometer according to the present embodiment. The laser ablation inductively coupled plasma mass spectrometer 1 includes a laser ablation unit 3, an inductively coupled plasma mass analyzer 5, and a mixing unit 7.

  The laser ablation unit 3 includes an ablation chamber 9 and a carrier gas introduction path 11. The ablation chamber 9 is a space that accommodates the sample 13. A transmission window made of quartz or the like is provided in the upper part of the ablation chamber 9, and laser transmission into the ablation chamber 9 from above is allowed. The carrier gas introduction path 11 is a flow path communicating with the ablation chamber 9, and introduces a carrier gas, in this embodiment, argon gas, into the ablation chamber 9.

  The inductively coupled plasma mass analyzer 5 includes an ICP torch 15 and a mass spectrometer 17. The ICP torch 15 ionizes the sample gas using the inductively coupled plasma as an ionization source. The ICP torch 15 is supplied with argon gas. The mass spectrometer 17 is provided downstream of the ICP torch 15 via the sampling cone 19, skimmer cone 21, and ion lens 23, and performs mass analysis of the ionized sample.

  The mixing unit 7 is disposed downstream of the laser ablation unit 3 and upstream of the inductively coupled plasma mass analysis unit 5. The mixing unit 7 includes a resin container 25 having an opening and a lid member 27 that closes the opening. The internal space of the resin container 25 functions as a mixing chamber 29. The volume of the mixing chamber 29 is preferably 50 to 100 [ml].

  The lid member 27 is provided with a gas inlet 31 and a gas outlet 33. In other words, the gas inlet 31 and the gas outlet 33 are formed in the same direction of the resin container 25, that is, the direction in which the opening exists. Thus, the vector component in the gas traveling direction at the gas outlet 33 includes a vector component in the direction opposite to the vector in the gas traveling direction at the gas inlet 31.

  The gas inlet 31 is inserted with the downstream end of the introduction pipe 35 whose upstream end communicates with the ablation chamber 9. As a result, the gas inlet 31 receives the sample gas and the carrier gas emitted from the laser ablation unit 3. In the gas outlet 33, the upstream end side of the outlet pipe 37 whose downstream end is connected to the ICP torch 15 is inserted. As a result, the gas outlet 33 releases the sample gas and the carrier gas received in the mixing chamber 29 to the inductively coupled plasma mass spectrometer 5.

  More specifically, the introduction pipe 35 and the outlet pipe 37 are both inserted into the lid member 27, and the portion of the inlet pipe 35 that extends from the lid member 27 into the mixing chamber 29 is the lid member 27 in the outlet pipe 37. It is longer than the portion extending into the mixing chamber 29.

  Next, the operation of the laser ablation inductively coupled plasma mass spectrometer configured as described above will be described. First, the sample 13 is placed in the ablation chamber 9. More specifically, a well-known XYZ axis stage may be provided on the bottom of the ablation chamber 9 and the sample 13 may be set on the stage. Then, the sample 13 is irradiated with a laser to vaporize the sample and generate a sample gas.

  The sample gas is discharged from the laser ablation unit 3 together with the argon gas as the carrier gas, and is received in the mixing chamber 29 of the mixing unit 7 through the introduction tube 35. The sample gas and the carrier gas are uniformly mixed in the mixing chamber 29, then discharged from the mixing unit 7, and supplied to the inductively coupled plasma mass analysis unit 5 through the outlet tube 37. The sample gas is ionized in the inductively coupled plasma mass analyzer 5 using the inductively coupled plasma as an ionization source and introduced into the mass spectrometer 17 for qualitative quantification.

  Here, in the inductively coupled plasma mass spectrometer, it is desired to reduce variations in ion intensity. The present inventor paid attention to the state of the gas introduced into the ICP torch and homogeneously mixed the sample gas and the carrier gas. Therefore, it was considered that variation in ionic strength could be reduced. Specifically, the gas is not supplied directly from the laser ablation unit to the inductively coupled plasma mass spectrometer through the pipe, but is once introduced into the mixing chamber having a larger space than the pipe and then inductively coupled plasma. It was decided to supply to the mass spectrometer. Furthermore, as an influence on the mixing state, the relationship between the mode of gas reception into the mixing chamber and the mode of gas release from the mixing chamber was investigated.

  The results will be described with reference to (a) to (j) of FIG. First, (j) in FIG. 2 is an existing mode in which the laser ablation unit and the inductively coupled plasma mass spectrometry unit are directly connected by a pipe without providing a mixing unit.

  2 (g) to (i) are embodiments in which the gas traveling direction at the gas inlet is the same as the gas traveling direction at the gas outlet, and (g) is the axis of the gas inlet and the gas outlet. (H) is an aspect in which the axis of the gas inlet and the axis of the gas outlet are substantially in a straight line, and (i) is an aspect of the axis of the gas inlet and the gas outlet. In this embodiment, there are a plurality of shielding plates arranged in a staggered manner in the mixing chamber with the shaft core being substantially in a straight line.

  (B) and (c) are embodiments in which the gas traveling direction at the gas inlet is perpendicular to the gas traveling direction at the gas outlet, and (b) is the position of the upstream end of the outlet pipe 37. A mode in which the downstream end of the introduction pipe 35 is on the front side in the gas traveling direction, (c) is a mode in which the position of the upstream end of the outlet pipe 37 is on the rear side in the gas traveling direction with respect to the downstream end of the introduction pipe 35. .

  Furthermore, (a), (d), (e), and (f) are modes in which the introduction pipe 35 and the outlet pipe 37 are both inserted into the lid member 27. Among these, (a) shows a mode in which the introduction pipe 35 is longer than the outlet pipe 37 with respect to a portion extending from the lid member 27 into the mixing chamber 29. (D) shows a mode in which both the introduction pipe 35 and the lead-out pipe 37 are long with respect to a portion extending from the lid member 27 into the mixing chamber 29. (E) shows a mode in which the outlet pipe 37 is longer than the inlet pipe 35 with respect to a portion extending from the lid member 27 into the mixing chamber 29. (F) shows a mode in which both the introduction pipe 35 and the outlet pipe 37 are short with respect to a portion extending from the lid member 27 into the mixing chamber 29.

  For each of these various embodiments, mass spectrometry was performed and data was collected every 0.1 seconds. The results are shown below as relative standard deviation of ionic strength, that is, RSD (standard deviation / average value of data). In each embodiment, components having different masses are extracted in a relative magnitude relationship, and RSD is obtained for each component having a different mass.

  As is clear from the above table, aspects (g), (h) and (i) did not show significant improvement over aspect (j) which is an existing aspect. On the other hand, modes (a), (b), (c), (d), (e) and (f) have an RSD value of less than half that of mode (j) which is an existing mode. A great improvement was seen. In particular, it can be seen that, in the aspect (a) according to the present embodiment, the variation in ionic strength is extremely low regardless of the mass.

  The effect of the mixing chamber volume was also tested. The start time and washout time were measured in a manner in which the volume of the mixing chamber was different. The start time refers to the time from the start of laser irradiation to the mixing chamber until the signal stabilizes after the signal is detected by the inductively coupled plasma mass spectrometer, and the washout time is the laser irradiation. Is stopped, and after the signal drops in the inductively coupled plasma mass spectrometer, the time until the signal stabilizes is said. When the volume of the mixing chamber was measured at 30 [ml], 50 [ml], 100 [ml], 250 [ml], and 400 [ml], the following results were obtained.

  As is apparent from the above table, in the aspect of the volume of 30 [ml], the washout time was very good at 10 seconds or less, but the start time was less than 50 seconds (exceeding 20 seconds). As a result. When the volume was 250 [ml], both the start time and the washout time were less than 50 seconds (exceeding 20 seconds), which was a bad result. In the aspect of the volume of 400 [ml], both the start time and the washout time were 50 seconds or more, which was a worse result. On the other hand, when the volume was 50 [ml] and 100 [ml], both the start time and the washout time were 20 seconds or less, and good results were obtained. Therefore, considering the start time and the washout time, the volume of the mixing chamber 29 is preferably 50 to 100 [ml].

  As described above, according to the laser ablation inductively coupled plasma mass spectrometer according to the present embodiment, the gas is not supplied directly from the laser ablation part to the inductively coupled plasma mass spectrometer via the pipe, Once guided to the mixing chamber, which has a larger space than the pipe, and then supplied to the inductively coupled plasma mass analyzer, the sample gas and carrier gas are mixed homogeneously in the mixing chamber and then supplied to the inductively coupled plasma mass analyzer. As a result, variations in ionic strength can be reduced.

  Although the contents of the present invention have been specifically described with reference to the preferred embodiments, various modifications can be made by those skilled in the art based on the basic technical idea and teachings of the present invention. It is self-explanatory.

  For example, the present invention relates to the mixing section and is not limited to the embodiment shown in FIG. In the present invention, as illustrated in the modes (b) to (f) of FIG. 2, the vector component in the gas traveling direction at the gas outlet has a direction opposite or orthogonal to the vector of the gas traveling direction at the gas inlet. In addition, the extending mode of the introduction pipe or the lead-out pipe into the mixing chamber can be appropriately modified and implemented.

It is a figure which shows the structure of the laser ablation inductively coupled plasma mass spectrometer which concerns on embodiment of this invention. It is a figure which shows the aspect made into object by the dispersion | variation investigation of ionic strength.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Laser ablation inductively coupled plasma mass spectrometer 3 Laser ablation part 5 Inductively coupled plasma mass spectrometer 7 Mixing part 25 Resin container 27 Cover member 29 Mixing chamber 31 Gas inlet 33 Gas outlet 35 Introducing pipe 37 Deriving pipe

Claims (5)

A laser ablation unit that irradiates a sample with a laser, vaporizes the sample to form a sample gas, and releases the sample gas together with a carrier gas;
An inductively coupled plasma mass spectrometry unit that performs mass spectrometry by ionizing a sample using a dielectric coupled plasma as an ionization source;
A laser ablation inductively coupled plasma mass spectrometer provided with a mixing unit provided between the laser ablation unit and the inductively coupled plasma mass spectrometer and having a mixing chamber for uniformly mixing a sample gas and a carrier gas.   2. The laser ablation inductively coupled plasma mass spectrometer according to claim 1, wherein the mixing chamber has a volume of 50 to 100 [ml]. The mixing unit includes a resin container having an opening, and a lid member that closes the opening.
A gas inlet for receiving the sample gas and the carrier gas emitted from the laser ablation unit and a gas for releasing the sample gas and the carrier gas received in the mixing chamber to the inductively coupled plasma mass analysis unit in the lid member The laser ablation inductively coupled plasma mass spectrometer according to claim 2, further comprising an outlet.   4. The laser ablation inductively coupled plasma mass spectrometer according to claim 3, wherein the vector component in the gas traveling direction at the gas outlet includes a vector in a direction opposite or orthogonal to the vector of the gas traveling direction at the gas inlet. The gas inlet is inserted with the downstream end of the introduction pipe whose upstream end is communicated with the laser ablation section, and the gas outlet is connected with the inductively coupled plasma mass spectrometer at the downstream end. The upstream end side of
The laser ablation induction according to claim 3 or 4, wherein a portion of the introduction pipe that extends from the lid member into the mixing chamber is longer than a portion of the outlet pipe that extends from the lid member into the mixing chamber. Coupled plasma mass spectrometer.

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