JPS63163146A - Plasma emission spectral analyzer - Google Patents

Abstract

PURPOSE:To reduce measuring time with a significant reduction in the measurement preparation time while lowering the required skillfulness in operation, by arranging a nebulizer and a plasma torch in an analyzer box while a cooler is housed in a matching box. CONSTITUTION:In an analyzer box 3, a matching box 11 houses a cooler 20 at the bottom and a nebulizer 1 divided with a partition is housed to isolate a high-temperature atmosphere generated from a plasma torch 2. Moreover, two needle tubes are fixed in such a manner as to be perpendicular to the body portion of the nebulizer 1, and a sample solution supply section 5 for supplying a sample solution to the nebulizer 1 is housed in a shielding box 6 to eliminate thermal influence of the high-temperature atmosphere as much as possible. With such an arrangement, this minimizes temperature changes in the perimeter of the nebulizer, especially in the perimeter of the sample solution supply section, thereby improving measuring accuracy and frequency of measurement significantly with the stabilization of the calibration curve for a long time. This also can shorten measuring time with a significant reduction in the measurement preparation time.

Description

[Detailed Description of the Invention] [Object of the Invention] (Field of Industrial Application) The present invention provides a plasma emission spectrometer that analyzes liquid samples containing metal elements such as petroleum fuel and lubricating oil with high sensitivity and precision. In particular, the present invention relates to a plasma emission spectrometer having a sample solution supply section in which a liquid sample is atomized by a cross-flow nebulizer (atomizer).

(Prior art and its problems) In a plasma emission spectrometer, a sample solution to be analyzed is atomized in a sample solution supply section before being supplied to a plasma torch wound with an induction coil. Depending on the atomization method, they are broadly classified into (i) coaxial type and (::) cross flow type.

The above coaxial type (i) is one in which the carrier gas argon gas flow and the analysis sample solution flow are guided to an atomizer through a coaxial tube needle and atomized, while the cross flow type (ii) is The tips of the two needles are arranged to be perpendicular to each other in the atomizer, and the argon gas flow of the carrier gas and the analysis sample solution flow are crossed and atomized.

Although the coaxial type (above) is suitable for samples with relatively high concentrations, its measurement accuracy is slightly inferior, and the cross 70-type (above) (i:) has higher measurement accuracy than the coaxial type, so many devices are commercially available and in use. has been done.

Conventionally, cross-flow type plasma emission spectrometers have a nebulizer (atomizer) for the sample solution inside the analyzer box.
It is configured to house a plasma torch (high-frequency plasma flame forming device) formed by winding a high-frequency coil, and a coupler (matching box) for efficiently supplying energy from the high-frequency power source to the plasma.

In addition, Utility Model Application Publication No. 58-9754G, as an analyzer for samples containing radioactive substances, is equipped with a fan 2z and a heat exchanger 23 in a glove box 2, as shown in Fig. 6. With plasma flame forming device stand 2
4, and a nebulizer and plasma torch are housed in this stand.

The sample solution supply section of the nebulizer used in the conventional cross-flow analyzer is made of glass and has a diameter of about 200 μm, as shown in FIG.
31 are disposed perpendicularly to each other, and these needle tubes are fixed with needle tube support fittings 32 and 33.

In this type of conventional cross-flow analyzer, as mentioned above, the plasma torch and matching box, which emit high heat, and the sample solution supply section of the nebulizer are stored in close proximity in the same box. For example, the high frequency plasma flame generated from a plasma torch is 6000 ~
The temperature is as high as 9000°, and the coupler also emits relatively high heat, so the needle tube support fitting of the sample solution supply section of the nebulizer is indirectly exposed to the high temperature atmosphere of the plasma flame and the heat radiated by the coupler. It turns out. This will have an extremely large effect on measurement accuracy. That is, the needle tube support fitting thermally expands in a high-temperature atmosphere, causing significant fluctuations in the data of the calibration curve.

Furthermore, in the operation of this type of analyzer, a preparation time is set mainly to maintain the temperature of the nebulizer in a desired thermal equilibrium state in order to improve measurement accuracy. Usually, about one hour of preparation time is required before measurement, and there are many problems such as not only a long measurement time including adjustment of the calibration curve but also the need for a skilled operator.

(Problems to be Solved by the Invention) In view of the above-mentioned problems, the inventor has conducted extensive studies and found that
In a cross-flow type plasma emission spectrometer, in order to eliminate as much as possible the effects of the high temperature atmosphere generated and emitted from the plasma torch and matching box, a cooling device is installed inside the matching box, and the plasma torch and nebulizer are heated. In particular, by thermally isolating the part that supplies the sample solution to the nebulizer from the needle tube fixed with a support fitting, that is, the sample solution supply part, maintaining measurement accuracy and shortening measurement preparation time. The present inventors have discovered that the following can be achieved, and have completed the present invention.

[Structure of the invention]

(Means for Solving the Problems) To summarize the present invention, the present invention includes a nebulizer that atomizes an analysis sample solution by a cross-flow method and a plasma torch that generates a high-frequency plasma flame in a plasma emission spectrometer box. The present invention provides an apparatus for plasma emission spectrometry, in which a cooling device is housed in a matching box of the analyzer box.

(Example) Hereinafter, an example of the plasma emission spectrometer according to the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a cross-sectional view of a cross-flow type plasma emission spectrometer according to the present invention.

In the analyzer box 3, the matching box 1
1 has a cooling device 20 stored in its lower part and a nebulizer.
1 (which is composed of a main body portion and a sample solution supply section 5 to be described later) is partitioned and stored with a partition plate 4 so as to isolate the high temperature atmosphere generated from the plasma torch 2. Although the cooling device is exemplified by the ventilation fan 21, it may also be a heat exchanger, and in this case it is preferably installed at the top or side of the matching box. . The cooling system is operated so that the temperature of the matching box is 25-30°C.

Furthermore, a sample solution supply part 5 is fixed to the main body of the nebulizer 1 with a needle tube support fitting so that two needle tubes are perpendicular to each other, and supplies the sample solution to the nebulizer.
is housed in a shielding box 6 so as to eliminate as much as possible the thermal influence of the high-temperature atmosphere. Although the shielding box is not essential, by housing the sample solution supply section 5 of the nebulizer in the shielding box 6, the sample solution supply section 5 can be removed from the matching box 11, which dissipates relatively high heat.
This will effectively isolate and scale the area. The shielding box 6 is installed through the opening of the analyzer box 3, and the matching box II has openings at the bottom and top, and its structure is shown in FIG.

The tab 22 at the top opening of the matching box is approximately 45°
It is bent to allow the cooling air from the ventilation fan to escape from the side of the plasma torch to the outside of the analyzer.

The shielding box 6 is preferably a thin plate box whose sides are open to the outside air so as to open the sample solution supply section 5 of the nebulizer housed in the analyzer box to the outside air. The box is preferably made of a thin plate made of a material that has a heat-resistant and heat-insulating effect, such as a heat-resistant ceramic plate, a steel plate,
Silica board etc. are used. On the bottom surface opposite to the side opening are a nebulizer insertion hole 7 into which the main body of the nebulizer is inserted, and around the top opening are a fixing plate 8 and a protective fence 9 for attaching the shielding box 6 to the opening of the analyzer box 3. is provided. Note that a protective plate may be used instead of the protective fence as long as it does not accumulate heat.

Various standard solutions were analyzed using a cross-flow type plasma emission spectrometer having the structure shown in FIGS. 1 and 2.

Measurement accuracy is determined by repeatability (takes 9596 confidence intervals of fluctuations in measured values as a result of repeated measurements with the same device by the same person) and changes over time in the calibration curve, but ±
The accuracy of the analyzer was evaluated by tracking the measurement time until it reached 2%.

The results are shown in Figure 3 and Table 1.

Table 1 (Stability of calibration curve) The figure before modification in Figure 3 refers to a high-frequency plasma emission spectrometer (manufactured by Jarrell Ash Co., Ltd.; 800) and after modification are the results obtained when modified according to the present invention.

From FIG. 3, it can be seen that in the plasma emission spectrometer according to the present invention, the characteristics of the sample spray amount (ml/mln) and the temperature around the sample solution supply part of the atomizer are extremely stable over time.

Also, from Table 1, the calibration curve of the analyzer according to the present invention is
It turns out that it is extremely stable. In other words, with the conventional method, the calibration curve is unstable during measurement, so the calibration curve must be checked every 10 to 15 minutes, and if the result exceeds ±2% of the standard value, it must be calibrated. , it was necessary to repeat the measurement.

In the analyzer according to the present invention, the calibration curve is stable over a long period of time, and the number of samples that can be measured while the calibration curve is stable is 4, compared to 4 before the modification. can be increased to 16 points or more.

In addition, measurement preparation time (waiting time) is essential in order to bring the temperature of the nebulizer to the desired thermal equilibrium state during measurement, whereas the previous method required 60 minutes of preparation time. In the apparatus of the present invention, this time can be shortened to about 20 minutes, and the measurement time can be significantly improved.

Next, another embodiment of the plasma emission spectrometer according to the present invention will be described.

FIG. 4 is a sectional view of another embodiment of the plasma emission spectrometer according to the present invention. The difference from the one in FIG. 1 is that the nebulizer 1 is disposed in the center of the analyzer box 3. Therefore, even if the partition plate 4 is provided between the nebulizer 1 and the plasma torch, the sample solution supply section 5 of the nebulizer 1 is placed under a harsher thermal environment than that in FIG.

Therefore, in order to eliminate this harsh thermal environment as much as possible, two cooling devices are installed in the matching box, and a ventilation fan IO shown in FIG. 5 is installed in place of the shielding box shown in FIG. A shielding box 6 is used.

Various standard solutions were separated using a cross-flow type plasma emission spectrometer having the structure shown in FIGS. 4 and 5. The results are shown in Table 2.

Table 2 As is clear from Table 2, conventional products (such as IcP-575 manufactured by Japan Jarel Ash Co., Ltd.
It can be seen that the calibration curve of the analyzer according to the present invention is extremely stable.

[Effects of the Invention] Since the plasma emission spectrometer of the present invention is designed to eliminate the influence of the high temperature atmosphere of the plasma torch as much as possible, temperature changes around the nebulizer, especially around the sample solution supply section of the nebulizer, are extremely small. Therefore, the calibration curve is stable over a long period of time, and the measurement accuracy and M1 constant number can be greatly improved.

Furthermore, since the measurement Qtt time (waiting time) required to maintain the nebulizer at a desired thermal equilibrium temperature before measurement can be significantly shortened, the measurement time can be shortened.

Furthermore, the analyzer according to the present invention reduces the skill level of handling operations.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a plasma emission spectrometer according to an embodiment of the present invention, and FIG. 2 is a perspective view of a cooling device attached to the analyzer of FIG. 1. FIG. 3 is a diagram illustrating changes over time in the amount of sample sprayed and the ambient temperature of the sample solution supply section when tested using the analyzer shown in FIG. 1. Fourth
The figure is a sectional view of another embodiment of the plasma emission spectrometer according to the present invention, and FIG. 5 is a perspective view of a cooling device attached to the analyzer of FIG. 4. FIG. 6 is a side view of a conventional high-frequency plasma analyzer, and FIG. 7 is an enlarged view of the main parts of the sample solution supply section of the nebulizer. 1... Nebulizer (atomizer) 2... Plasma torch 3... Analyzer box 4... Partition plate 5... Sample solution supply section 6... Shield box 7... Nebulizer insertion hole 8... Fixed plate 9... Protective rods 10, 21... Ventilation fan 11... Matching box 20... Cooling device patent applicant Toa Fuel Industries Co., Ltd. agent Patent attorney Kubo 1) Kohei Figure 1 Shield ε box No. 3121 rs Figure 4

Claims (1)

[Claims] 1. A nebulizer that atomizes an analysis sample solution and a plasma torch that generates a high-frequency plasma flame are installed in a plasma emission spectrometer box, and a cooling device is installed in a matching box of the analyzer box. A device for plasma emission spectrometry, characterized in that the device is housed. 2. The apparatus for plasma emission spectrometry according to claim 1, characterized in that the analysis sample solution supply section of the nebulizer is housed in a shielding box. 3. The apparatus for plasma emission spectrometry according to claim 2, wherein the side surface of the shielding box is open to the outside air. 4. The apparatus for plasma emission spectrometry according to claim 1, wherein the cooling device is a ventilation fan. 5. The apparatus for plasma emission spectrometry according to any one of claims 1 to 4, wherein the sample solution supply section of the nebulizer is of a cross-flow type.