JP3405218B2 - Atomic absorption spectrophotometer - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an atomic absorption spectrophotometer for atomizing a sample by a flameless atomization method, and more particularly, to such an atomic absorption spectrophotometer. It relates to an atomization furnace in an absorption spectrophotometer. 2. Description of the Related Art In order to perform analysis with an atomic absorption spectrophotometer, it is necessary to atomize a sample in a molecular state. The atomization method includes flame atomization, in which the sample is heated to a high temperature using a burner flame (flame), and flameless, in which the sample is heated and atomized using a micro electric furnace. There is. In the flameless atomization method, a graphite atomization furnace that atomizes a sample by injecting a sample into a graphite tube and applying a large current to the tube and heating the tube is mainly used. FIG. 5 is a sectional view showing the structure of a conventional atomization furnace. Both ends of the graphite tube 9 into which the center sample is injected are tapered, and a graphite cap 1a having a tapered portion on its inner surface and a graphite holder 1b are pressed and engaged. The graphite cap 1a and the graphite holder 1b are electrodes, and are press-fitted into cooling blocks 2a and 2b each having an electrode ring for supplying electric power. For power supply to the graphite tube 9, current flows from one of the cooling blocks 2a or 2b,
This is performed by a flow path returning to the power supply from the cooling block 2b or 2a at the other end through the graphite tube 9, whereby the graphite tube 9 is heated by Joule heat to atomize the sample. Each cooling block 2a, 2b
Is assembled on the base 11 via insulating plates 10a and 10b, and window plates 13a and 13b made of quartz glass are fitted, so that light from a light source can pass in the axial direction of the graphite tube 9. It has become. In order to further control the temperature of the reactor, the graphite tube 9
A temperature sensor (photosensor) 12 for measuring the temperature of the graphite cap 1a is mounted on the cooling block 2a, and a small hole 13 for observing radiation light from the heated graphite tube 9 is provided in the graphite cap 1a.
Is drilled. As described above, the graphite cap 1a and the graphite holder 1b are fitted into the respective cooling blocks 2a and 2b by the graphite tube 9a.
In order to allow a large current (500 to 400 A) to flow, the fitting tolerance is set to a close fit of about H7 and k6 so that the contact resistance between the two is reduced. In addition, the handle 5 was used as a tool. Referring to FIG. 6, the assembling method will be described. The cup 4 is applied to the cooling block 2a from the left side, the graphite cap 1a is inserted from the right side into the screw portion provided at the center of the cup 4, and the cup 4 is further gripped. By turning the handle 5 from the right side and screwing into the screw portion, the graphite cap 1a is pushed by the handle 5 and pressed into the cooling block 2a to be assembled. [0005] The atomization furnace in the conventional atomic absorption spectrophotometer is constructed and assembled as described above, but is press-fitted using a cup and a handle as a tool in the conventional method. When the graphite cap rotates and the orientation with the cooling block is not determined by the method, the small hole drilled in the graphite cap does not face correctly at the position of the temperature sensor (photo sensor) mounted on the cooling block described above. There was a problem that occurs. SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and has been described in connection with a case in which a graphite cap does not rotate in a predetermined direction when the graphite cap is attached to or detached from a cooling block for replacing the graphite cap of a nuclear reactor. It is an object of the present invention to provide an atomic absorption spectrophotometer provided with an atomization furnace that can be securely attached to a device and that can be securely removed. In order to achieve the above object, an atomic absorption spectrophotometer according to the present invention provides a graphite cap with a pin hole and a guide groove, and a pin engaged with the guide groove. Is installed in the cooling block. Therefore, the graphite cap and the pin and the guide groove of the cooling block, which are constituent elements of the present invention, cooperate with each other so that the direction of the graphite cap and the cooling block is always determined in a predetermined direction when assembling the reactor. Hereinafter, an atomic absorption spectrophotometer according to the present invention will be described with reference to the drawings. FIG. 1 is a diagram of a graphite cap and a cooling block according to the present invention. FIG. 2 is a cross-sectional view showing the relationship between related components before and after the graphite cap is attached, and FIG. 3 is a sectional view showing the relationship between related components before and after the graphite cap is removed. FIG. 4 is an external view of a guide which is one of tools used at this time. The components of the nuclear reactor, their shapes, and their functions in use are the same as those described in detail in the description of the conventional method in FIG. In the present invention, as shown in FIG. 1, the graphite cap 1a is provided with two pin holes 14 into which pins 6 of a guide 3 to be described later are fitted on the end face on the side fitted with the cooling block 2a. A guide groove 8 that fits the pin 7 embedded in 2a is machined to the required length in the axial direction at a predetermined position of the fitting portion. A pin 7 that fits into the guide groove 8 of the graphite cap 1a is embedded in a predetermined position in the inner diameter of the cooling block 2a. FIGS. 2 and 3 show tools prepared for attaching and detaching the graphite cap 1a.
Are provided with a guide 3, a cup 4, and a handle 5. The cup 4 is provided with a screw portion at the center, and the handle 5 is provided with a female screw at the center thereof. As shown in FIG. 4, the guide 3 has a cylindrical shape. The outer diameter is fitted to the inner diameter of the cooling block 2a, and the inner diameter is fitted to the threaded portion of the cup 4. Two pins 6 are embedded in one end face, and a guide groove 8 is formed in the bottom. Next, a procedure for attaching and detaching the graphite cap 1a will be described. First, when mounting is performed, the guide 3 is inserted into the cooling block 2a from the right side along the pins 7 of the cooling block 2a as shown in FIG. 2A, and the threaded portion of the cup 4 is inserted into the guide 3 from the left side. Then, the graphite cap 1a is inserted into the screw portion of the cup 4 from the right side, the pin 6 of the guide 3 is fitted into the pin hole of the graphite cap 1a, and the handle 5 is screwed into the screw portion from the right side. When the handle 5 is rotated with the right hand while holding the cup 4 with the left hand, the guide groove 8 guides the pin 7 while the guide 3 and the graphite cap 1a are connected, and is mounted in the cooling block 2a. When the flange portion of the graphite cap 1a hits the cooling block 2a as shown in FIG. 2 (b), the handle 5 cannot be further turned and is securely mounted. To disassemble the tool, first turn the handle 5 in the reverse direction to remove the tool to the right, and pull out the cup 4 and the guide 3 to the left. A method for removing the graphite cap 1a will be described with reference to FIGS. 3 (a) and 3 (b). As shown in FIG. 3A, the guide 3 is inserted from the left side, and the pin 6 is fitted into the pin hole of the graphite cap 1a. The cup 4 is inserted from the right side, and the handle 5 is screwed in from the left side. When the handle 4 is turned with the left hand while holding the cup 4 with the right hand, the guide groove 8 moves rightward with the guide groove 8 guided by the pin 7 while the guide 3 and the graphite cap 1a are connected, and is removed from the cooling block 2a. Get out. The disassembly of the tool is only reversed left and right when mounted. These tools can also be used as they are when attaching and detaching the graphite holder 1b to and from the cooling block 2b. Further, pins 6, 7 and guide grooves 8
Is not limited to the illustrated position, and may be formed anywhere if the small hole 13 of the graphite cap 1a is fixed at a predetermined position with respect to the cooling block 2a, and the shape of the tool may be arbitrarily deformed. Things. The atomic absorption spectrophotometer of the present invention is constructed as described above, and has a guide pin and a guide groove, a graphite cap pin hole and a guide groove, and a cooling block pin. When the graphite cap is attached to the cooling block, the small hole for taking out the radiant light from the graphite tube drilled in the cooling block can be correctly adjusted without paying attention to the insertion direction of the graphite cap when attaching the graphite cap to the cooling block. Since it is uniquely directed to the direction of the sensor, no skill is required for the assembling work, and the assembling work time can be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view showing a graphite cap and a cooling block of an atomization furnace of an atomic absorption spectrophotometer of the present invention. FIG. 2 is a diagram showing a procedure for attaching a graphite cap to an atomization furnace of the atomic absorption spectrophotometer of the present invention. FIG. 3 is a view showing a procedure for removing a graphite cap of an atomization furnace of the atomic absorption spectrophotometer of the present invention. FIG. 4 is a view showing a guide which is one of the graphite cap attaching / detaching tools of the present invention. FIG. 5 is a diagram showing an atomization furnace of an atomic absorption spectrophotometer. FIG. 6 is a view showing attachment and detachment of a conventional graphite cap. [Description of Signs] 1a Graphite cap 2a Cooling block 3 Guide 4 Cup 5 Handle 6 Pin 7 Pin 8 Guide groove 14 Pin hole

────────────────────────────────────────────────── ─── Continued on the front page (58) Fields investigated (Int.Cl. ⁷ , DB name) G01N 21/00-21/01 G01N 21/17-21/61 Practical file (PATOLIS) Patent file (PATOLIS)

Claims (1)

(57) [Claims 1] A tube for heating a sample by passing an electric current, a graphite cap which is engaged with the tube and forms an electrode, and is engaged with the graphite cap by a pin. In an atomic absorption spectrophotometer comprising a guide and a cooling block for cooling the graphite cap, a pin hole and a guide groove for fitting the guide in the graphite cap are provided in the graphite cap, and a pin engaging with the guide groove is provided in the cooling block. An atomic absorption spectrophotometer characterized by being installed.