JPH11173979A - Atomic absorption spectrophotometer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an atomic absorption spectrophotometer in which the spraying efficiency of a sample liquid is optimized and whose absorption sensitivity is enhaced. SOLUTION: The ring-shaped part 22a of a holding member 22 is fitted to the outer circumference of a blowoff port 12c via a nut 21 which is screwed to a nebulizer 12. A disperser 15 is held in front of the blowoff port 12c by two upper and lower arm parts 22b which are extended from the ring-shaped part 22a. When the nut 21 is turned counterclockwise, the holding member 22 is pressed by the nut 21 so as to be slid to the right direction, and a relative distance (d) between the end face of the blowoff port 12c and the left end part of the disperser 15 is changed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an atomic absorption spectrophotometer, and more particularly, to a flame type atomic absorption spectrophotometer for atomizing a sample by introducing an atomized sample solution into a chemical flame.

[0002]

2. Description of the Related Art In an atomic absorption spectrophotometer, it is necessary to vaporize a sample into an atomic vapor. The atomization method includes a flame method using a chemical flame and a flameless method using no chemical flame. FIG. 3 is a schematic configuration diagram of a conventional premix burner used in the flame method.

A nebulizer 12 is supported at one end of the spray chamber 10 by a nebulizer support 20, and a capillary tube 11 is fitted into the nebulizer 12. When the auxiliary gas such as air supplied to the nebulizer 12 through the auxiliary gas pipe 13 is jetted from the jet port 12a, the sample liquid is sucked up through the capillary pipe 11 by the negative pressure. The sample liquid is sprayed by the combustion support gas, becomes fine particles, and collides with the disperser 15 disposed in front of the ejection port 12a.
The disperser 15 is a spherical body made of glass or a corrosion-resistant metal, and a large sample droplet hits the disperser 15 and adheres to the surface thereof and drops. As a result, only fine droplets having a relatively uniform size are mixed with a fuel gas such as acetylene gas supplied through the fuel gas pipe 14, and
It is blown out into the spray chamber 10. This mixed gas is supplied to the spray chamber 1
The sample is ejected from a slit-like opening 17a of a burner head 17 provided at the upper portion on the other end side of the sample 0, and the sample component is atomized in a frame 18 formed thereby. The sample liquid dropped from the inner wall of the disperser 15 and the spray chamber 10 is discharged from the drain 16. In addition, the fuel gas is not limited to the above configuration, and the fuel gas can be introduced from an appropriate position in the spray chamber 10.

[0004]

As described above, the disperser 15 has a function of dropping large droplets and adjusting the size of fine droplets. The inventors of the present application have found through experiments that the relative distance between the disperser 15 and the end face of the jet port 12a has a great effect on the atomization efficiency of the sample liquid and, consequently, the light absorption sensitivity. However, in the conventional premix burner, the accuracy of the relative distance cannot be increased because the disperser 15 is fixed to the nebulizer support 20 by the curved rod-shaped support member 19. For this reason, the absorbance sensitivity is not the best, the dispersion of the absorbance sensitivity is large among a plurality of spectrophotometers, or the nebulizer 1
2 had poor reproducibility before and after detachment.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide an atomic absorption spectrophotometer capable of obtaining high absorption sensitivity by improving the accuracy of the relative distance. Is to provide.

[0006]

SUMMARY OF THE INVENTION The present invention, which has been made to solve the above-mentioned problems, is directed to an atomic absorption spectrophotometer for introducing a sample solution sprayed by using a supporting gas into a frame to atomize sample components. A) a capillary tube through which the sample solution passes; and b) an annular auxiliary combustion gas outlet formed coaxially with the capillary tube around the capillary tube outlet end, and conical with the nozzle. A nebulizer having an expanding outlet, c) a spherical collision body disposed in front of the air outlet, and d) slidable in the direction of extension of the capillary tube with respect to the nebulizer while holding the spherical collision body. And a collision body holding member attached to the vehicle.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In an atomic absorption spectrophotometer according to the present invention, when a combustion assisting gas is supplied to a nebulizer, the combustion assisting gas is ejected from an ejection port and spreads in a conical outlet. Since the inside of the outlet becomes a negative pressure, the sample liquid is sucked through the capillary tube and spouted from the outlet end with the help of the combustion supporting gas. The sprayed sample liquid collides with a spherical collision object in front, and a large-sized droplet is sieved. Therefore, the atomization efficiency depends on the relative distance between the end face of the outlet and the spherical impactor. Since the relative distance changes when the collision object holding member is slid, the relative distance can be finely adjusted so that, for example, the light absorption sensitivity becomes the best.

Specifically, for example, a thread groove is cut on the outer peripheral wall of the nebulizer on the circumference concentric with the capillary tube, and the impact body holding member is slid on the outer peripheral wall at the tip of the nebulizer via a nut screwed into the thread groove. Insert freely. Thus, when the nut is rotated in the direction of the nebulizer tip, the impact body holding member is pushed by the nut, and adjustment can be made in the direction in which the relative distance increases.

[0009]

According to the nebulizer of the atomic absorption spectrophotometer according to the present invention, the relative distance between the end face of the outlet and the spherical collider can be adjusted so that the atomization efficiency or the atomization efficiency becomes optimum. Absorption sensitivity can be obtained. Also, since you can adjust multiple nebulizers individually,
Variations in their performance can be reduced. Further, since the position of the spherical collision object is fixed with respect to the nebulizer, once the relative distance is determined, the accuracy of the relative distance is stably maintained. Therefore, good reproducibility can be obtained before and after the nebulizer is attached and detached. Further, since this adjusting mechanism has a very simple structure, it has high reliability and little increase in cost.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the atomic absorption spectrophotometer according to the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing a detailed structure of an injection portion in a premixed burner of an atomic absorption spectrophotometer according to the present embodiment.

Nebulizer 12 composed of a plurality of members
A small-diameter capillary tube 11 is fitted into the center of the tube, and an auxiliary combustion gas passage 12b extending in the axial direction is formed concentrically with the capillary tube 11. Capillary tube 11
The outlet end reaches the vicinity of the tip of the nebulizer 12, and a ring-shaped outlet 12a is formed around the outlet end so as to be continuous with the auxiliary combustion gas passage 12b. Further, the spout 1
A conical outlet 12c is formed continuously from 2a. A combustion support gas pipe 13 is screwed to the lower surface of the nebulizer 12, and the inside of the combustion support gas pipe 13 and the combustion support gas passage 12b communicate with each other.

The first cylindrical outer wall portion 12d of the nebulizer 12
Has a male thread cut into it, and a nut 21 is screwed into the male thread. First cylindrical outer wall 1
An annular portion 22 of the disperser holding member 22 is attached to the second cylindrical outer wall portion 12e, which is thinner than 2d, via a nut 21.
a is inserted. Two upper and lower arms 22 b extend from the annular portion 22 a of the disperser holding member 22, and the arms 22 b sandwich the spherical disperser 15. An O-ring 23 made of an elastic material is fitted into the gap between the nut 21 and the second cylindrical outer wall portion 12e.
Is pressed from the inner peripheral side to form the first cylindrical outer wall portion 12.
The rattle of the nut 21 against d.
The movement is smooth. Further, the space between the two is kept liquid-tight to prevent the liquid from entering from the spray chamber side. In addition,
The disperser holding member 22 may be formed of a corrosion-resistant resin material or the like so as to slide smoothly on the second cylindrical outer wall portion 12e.

The operation of the premix type burner having the above-described structure is as follows. An auxiliary gas such as air introduced into the nebulizer 12 through the auxiliary gas pipe 13 is vigorously jetted from the jet port 12a through the auxiliary gas channel 12b. Outlet 12c
Since the auxiliary combustion gas rapidly expands inside, the inside of the outlet 12 c becomes negative pressure, and the sample liquid is sucked through the capillary tube 11. When the sucked sample liquid reaches the exit end of the capillary tube 11, it is sprayed into the outlet 12c on the jet flow of the auxiliary gas. Since the outlet 12c has a conical shape, the droplets that have flowed out from the end face of the outlet 12a efficiently collide with the disperser 15 that is disposed close to the front without being scattered widely. The size of the droplet of the sample liquid ejected varies, but the large-sized droplet is disperser 15.
When it collides with, it adheres to its surface. On the other hand, fine droplets having a certain size or less pass through the gap between the disperser 15 and the end face of the outlet 12c and spread into the spray chamber.

The relative distance d between the end face of the outlet 12c and the disperser 15 can be adjusted as follows. First, the nut 21 is sufficiently rotated clockwise to move the nut 21 to the maximum left position in FIG. In this state, the disperser holding member 22 is pushed leftward until the left end surface of the annular portion 22a of the disperser holding member 22 contacts the nut 21. Then, the disperser 15 enters a state in which the left end thereof slightly enters the inside of the outlet 12c. Thereafter, when the nut 21 is rotated little by little in a counterclockwise direction, the nut 21 moves rightward,
The annular portion 22a of the disperser holding member 22 is pushed and slid in the same direction. As a result, the left end of the disperser 15 exits from the outlet 12c and moves further away from the end face of the outlet 12c.

FIG. 2 is a graph summarizing the results obtained by actually measuring the relationship between the relative distance d and the absorbance of five samples using the premixed burner having the above structure. As apparent from FIG. 2, the absorbance is greatly affected by the relative distance d. Under the conditions of the actual measurement, the absorbance is the best when the relative distance d is 0.1 mm. According to the configuration of the above embodiment, since the relative distance d can be adjusted with extremely high accuracy, it is possible to easily adjust the absorbance to an optimum or a condition close thereto.

It should be noted that the above embodiment is merely an example, and it is apparent that the embodiment can be appropriately modified and modified within the scope of the present invention.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a detailed structure of an injection portion in a premixed burner of an atomic absorption spectrophotometer according to an embodiment of the present invention.

FIG. 2 is a graph showing the measured results of the relationship between the relative distance d between the outlet end face and the disperser and the absorbance.

FIG. 3 is a schematic configuration diagram of a conventional premix type burner.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Spray chamber 11 ... Capillary tube 12 ... Nebulizer 12a ... Injection port 12b ... Combustion gas flow path 12c ... Outlet 12d ... 1st cylindrical outer wall part 12e ... 2nd cylindrical outer wall part 15 ... Disperser 21 ... Nut 22 ... Disperser Holding member 22a: annular portion 22b: arm portion

Claims (1)

[Claims] 1. An atomic absorption spectrophotometer for atomizing a sample component by introducing a sample solution sprayed by using a supporting gas into a frame, comprising: a) a capillary tube through which the sample solution passes; and b) an outlet of the capillary tube. A nebulizer having an auxiliary combustion gas outlet formed coaxially with the capillary tube around the end thereof and having a conical outlet continuously extending from the outlet, and c) an adjoining front of the outlet. A) a colliding body that is disposed in the same manner as above; d) a colliding body holding member that holds the sphere colliding body and is slidably attached to the nebulizer in a direction in which the capillary tube extends. Absorption spectrophotometer.