JPS62129743A - Sample atomizer for flame atomic absorption analysis - Google Patents

Abstract

PURPOSE:To enable direct analysis of a highly dense sample, by providing a disperser which finely granulates a sample solution released in a mist from a nozzle of an atomizer to change the gap between the nozzle and the disperser as desired by a gap changing means. CONSTITUTION:Applying a depression phenomena caused by an auxiliary fuel gas running in a high-speed flow, an atomizer 1 turns a liquid sample 2 in a conical mist 4 with uneven particle size through a tube 3 and releases it into a mixing chamber 5 of a fuel and the auxiliary fuel gas. The misty sample 2 is blown against a spherical disperser 6 as strongly as released, dispersed into fine particles by a phenomenon such as resonance caused there and is introduced into a flame 9 of a burner 8 in the form of a mist 7 in a uniform size. As subjected to a thermal decomposition or the like, the misty sample 7 thus introduced into the flame 9 renders metal elements contained in an atomic vapor and to measure the absorption of light with the wavelength intrinsic to the metal passing through the flame 9. A nozzle section of the atomizer 1 and the disperser 6 are regulated with a gap regulating mechanism 10, thereby making the amount of the sample to be introduced variable.

Description

[Detailed description of the invention]

[Field of Application of the Invention] The present invention relates to a sample spraying device for flame atomic absorption analysis,
Flame atomic absorption spectrometry suitable for reducing atomic absorption sensitivity and making analysis possible, especially when high concentration samples cannot be analyzed due to the narrow dynamic range of the + line in atomic absorption spectrometry. This invention relates to a sample spraying device. [Background of the Invention] As a method for atomizing metal elements in a flame atomic absorption spectrophotometer, Instrumentati, onl, a
boratory Tnc January 1980
129559 p3-16 “Pre-mixing and burner system J”
The sample solution is drawn into the atomized form by an atomizer, discharged into a mixing chamber with fuel and auxiliary fuel gas, and introduced into the flare 11 together with those gases to generate heat. A commonly used method is to decompose metal salts into J-atomic vapor. The atomic absorption sensitivity and the noise of the atomic absorption signal in an atomization apparatus using this method depend most greatly on the state of the mist of the sample heavy equipment emitted from the atomizer, especially on the size of the particles of the mist. If the mist particles emitted from the atomizer are large, the thermal decomposition efficiency over the full width will decrease, resulting in a decrease in atomic absorption sensitivity and an increase in noise. For this reason, flame atomic absorption spectrophotometers, which are trending toward higher sensitivity, have higher
In order to obtain the ratio of atomic absorption sensitivity to noise, that is, S/N, we obtain extremely fine particles of 2 to 10 microns or less, which is the ideal fog size that has high thermal decomposition efficiency and generates little noise. method is used. Use a disperser to make this dew into fine particles. That is, the atomized sample solution discharged from the atomizer is sprayed onto the disperser. Due to the resonance phenomenon caused by the force of the spray, the mist is atomized and introduced into the flake t1. Recent atomic absorption spectrophotometers are capable of not only high-sensitivity analysis but also highly accurate analysis of metal elements with simple operations, so there is a considerable demand for high-concentration sample analysis. However, the calibration curve for atomic absorption spectrometry has the disadvantage that the dynamic range is narrower than that for other metal element analysis methods. Therefore, the calibration curve in the high concentration range is curved in the direction of the S axis, and the absorbance remains constant even when the concentration changes5.
It becomes impossible to know the difference between the layer tops. Therefore, various methods have been studied and implemented for analyzing high-intensity regions using atomic absorption spectrometry. In the case of flame atomic absorption spectrophotometer as a method,
It has become common to use an atomizer that sucks in a sample solution and releases it in the form of a mist into a mixing chamber with fuel and auxiliary fuel gas to reduce the suction amount to reduce the atomic absorption sensitivity. The atomizer used in Atomic Absorption Spectroscopy J is a concentric (11i111) method that applies the depressurization phenomenon caused by flowing auxiliary fuel gas such as air at a high flow rate to suck the sample solution and spray it. It is something. This type of sprayer adjusts the suction (spray) t by changing the flow rate of the auxiliary fuel gas. Therefore, when the suction (injection) rate of the sample solution changes, the flow rate of the auxiliary fuel gas also changes. Naturally, when the flow rate of the auxiliary fuel gas changes, the fuel level m (flow rate ratio of the fuel gas and auxiliary fuel gas) of the frame also changes. In the case of flame atomic absorption spectrometry, the degree of atomic vaporization of the target element and interference by coexisting substances largely depends on the state of the flame. Therefore, there is an optimal flame combustion state depending on the target element and the state of the sample solution. Therefore, each time the atomic absorption sensitivity is adjusted, the flow rate of the fuel gas is also adjusted to
It was necessary to readjust the combustion conditions. In this way, no consideration was given to analytical operability. Further, as described above, the ratio of atomic absorption sensitivity to noise, that is, the S/N, also depends on the size of the dew of the sample solution introduced into the frame. In order to obtain a mist of extremely fine particles of approximately 2 to 10 microns or less that can obtain a high S/N, the atomized sample solution discharged from the atomizer is sprayed onto a surface structure such as a sphere to avoid resonance, etc. There is also a method of lowering the atomic absorption sensitivity by installing a disperser that causes this phenomenon. However, in this method, the thermal decomposition efficiency of the atomized sample solution in the flake 11 is low, resulting in a significant increase in noise. Therefore, it can be seen that no consideration was given to the accuracy of 9 analysis. Furthermore, removing the disperser installed in the mixing chamber of the atomized sample solution, fuel, and auxiliary fuel gas each time an analysis is performed impairs analysis operability. [Object of the Invention] The present invention has been made in view of the above, and its [) purpose is to arbitrarily adjust the atomic absorption sensitivity without increasing noise or changing the combustion state of the flame 11. An object of the present invention is to provide a sample spraying device for flame atomic absorption spectrometry that can expand the dynamic range of a calibration curve. [Summary of the Invention] The present invention is based on the results of various experiments conducted using a sample spray 1# sample solution using a method of spraying a mist sample solution emitted from a sprayer onto a disperser having a spherical structure. It was confirmed that the following phenomenon occurs between the metal element and the disperser: (1) If the disperser is not used, the atomic absorption sensitivity will decrease to about 2/2, although there are some differences depending on the metal element. Therefore, the dynamic range of the calibration curve can be expanded approximately twice. (2) If a disperser is not used, the noise level will increase by at least twice, although there are differences depending on the metal element. Therefore, there is a risk that analysis accuracy will decrease. (3) A disperser is installed in the mixing chamber of the atomized sample solution, fuel, and auxiliary fuel gas for each analysis. Desorption due to concentration warfare significantly reduces analytical operability.

[4] If the flow rate of the auxiliary fuel gas is changed to reduce the amount of sample solution sucked (sprayed) by the atomizer, the atomic absorption sensitivity will decrease. Therefore, the dynamic range of the calibration curve can be expanded. (5) If the flow rate of the auxiliary fuel gas is changed to increase the amount of sample solution sucked (sprayed) by the nebulizer, the atomic absorption sensitivity will decrease, so the dynamic range of the calibration curve can be expanded. However, in this case, there is a risk that the accuracy of one analysis will decrease because the noise increases significantly. (6) Varying the flow rate of the auxiliary fuel gas to suck the sample solution into the atomizer (spray m > 3k) will cause fluctuations in the combustion state of the flare 11. Atomic vaporization of lI elements and interference by coexisting substances will occur. Since the degree of combustion greatly depends on the combustion state of the flame, there is an optimal combustion state of the flame 11. Therefore, fluctuations in the combustion state of the flame pose a risk of reducing analysis accuracy. WI) Every time the amount is adjusted, it is necessary to change the fuel gas flow rate to adjust the combustion state of the flame to suit the analysis, which reduces analytical operability. (7) Atomic absorption sensitivity depends on the nozzle of the atomizer. The atomic absorption sensitivity varies relatively slowly within a range of 2 to 3 times depending on the gap. Therefore, the dynamic range of the calibration curve can be expanded by 2 to 3 times. (8) The magnitude of noise due to the gap between the nozzle part of the sprayer and the disperser remains unchanged. Therefore, the 1 analysis accuracy will not decrease. (9) Frame due to the gap between the nozzle part of the sprayer and the disperser The combustion state of the analyzer remains unchanged.Therefore, there is no reduction in analytical accuracy and analytical operability.(10) Atomic absorption sensitivity can be adjusted arbitrarily by simply changing the gap between the nozzle part of the atomizer and the disperser. From these facts, the nozzle part of the atomizer that sucks in the sample solution and releases it as a mist, and the resonance and other phenomena that occur when the mist is sprayed, further atomize the mist and reduce the heat of the sample in the frame. The flame atomic absorption spectrometry sample spray device has a mechanism that can arbitrarily change the gap between the flame atomic absorption spectrometer and the dispersion device, which increases analysis efficiency and suppresses noise generation. In the direct analysis of highly concentrated samples, which is often required due to the narrow dynamic range of the Detection + IC line, it is effective in expanding the dynamic range and enabling analysis by lowering the atomic absorption sensitivity. Figure 3 is a diagram showing an example of the relationship between the gap between the nozzle part of the atomizer and the spherical disperser and the atomic absorption sensitivity.
From the relationship line C between the gap between the atomizer and the disperser and the atomic absorption sensitivity (absorbance), it can be seen that the atomic absorption sensitivity depends on the gap; the smaller the gap, the lower the atomic absorption sensitivity, and the larger the gap, the lower the atomic absorption sensitivity. This was done by focusing on the fact that the sensitivity increases and the maximum sensitivity is constant from a certain gap.
A sprayer that sucks in a sample solution and releases it in the form of a mist, and a disperser that sprays the sample solution in the form of a mist emitted from the nozzle of the sprayer to further atomize the mist and unify its size. jiff is characterized in that it is equipped with a gap changing means that makes it possible to adjust the atomic absorption sensitivity by arbitrarily changing the gap between the nozzle part of the sprayer and the disperser. [Embodiments of the Invention] The present invention will be described in detail below with reference to the embodiment shown in FIG. 1 and FIG. 2. FIG. 1 is a block diagram showing an embodiment of the Fra-11 atomic absorption spectrometry sample injection device of the present invention, showing the nozzle part of the atomizer that sucks in a liquid sample and releases it in the form of a mist, and the nozzle part of the atomizer that sucks in a liquid sample and releases it in the form of a mist. In order to increase the thermal decomposition efficiency of the sample in the flange, the gap between the sprayer and the disperser can be changed arbitrarily.The atomizer is a concentric type, and the disperser is spherical. Here's what's going on. The atomizer 1, which utilizes the depressurization phenomenon caused by the auxiliary fuel gas flowing at high speed, converts the liquid sample 2 through the tube 3 into a conical mist fi4 with non-uniform particle sizes, and generates the fuel and the auxiliary fuel gas. into the mixing chamber 5. The mist-like sample 2 is blown onto a spherical-structured disperser 6 by the force of the discharge, and dispersed by phenomena such as resonance that occur there, becoming fine particles and becoming a mist 7 with a uniform size. and burner 8 with fuel and auxiliary fuel gas.
into frame 9. The atomized sample 7 introduced into the flake tz 9 undergoes thermal decomposition, etc., and the metal elements contained therein become atomic vapors. Therefore, the absorption sensitivity of light having a wavelength specific to the metal passing through the frame 9 is measured. The gap between the nozzle part that emits the mist of the sprayer and the disperser 6 is set to 0.5 to 1.0 by the gap adjustment mechanism 10. This allows for arbitrary adjustment between On and On. Since the amount of atomized sample introduced into the flare L 9 changes depending on the gap between the nozzle part of the atomizer 1 and the disperser 6, it is possible to change the absorption sensitivity. If the interval vX is set narrowly, the frame will be 1.
Since the sensitivity of the fog introduced into 9 is reduced, the atomic absorption sensitivity is reduced. When the gap is widened, more mist is introduced into the frame 9, so that the atomic absorption sensitivity is improved. Note 1
Samples that are not introduced into the frame 9, such as mist with large particles removed by the disperser 6, are discarded as waste liquid through the waste liquid outlet 11. Figure 2 shows that the gap between the nozzle part of the sprayer 1 and the disperser 6 is II.
FIG. 4 is a diagram showing an example of comparing the states of the calibration curves in the case of n and 51 m. Since the calibration curve a when the gap is 5 m has high sensitivity, the degree of curvature in the concentration axis direction in the high concentration region is large. Therefore, even if the concentration changes in the concentration range of 50 ppm or more, Kll! The determined absorbance is a constant value,
It is impossible to know the difference in concentration. In the case of the calibration curve when the gap is 1 rrn, the atomic absorption sensitivity is 1/2 ~
It decreases to 1/3. Therefore, the state in which the calibration curve curves in the concentration axis direction is different from the calibration +ItHca in the case of the gap 5■. In the case of the calibration curve a at the gap F5nw++, it is impossible to determine the concentration of 41g over 50 ppm;
In the case of the calibration curve at m, there is a difference in absorbance up to 120 ppna, so it is possible to know the concentration. In other words, the dynamic range of the calibration curve is expanded two to three times. According to this embodiment, the gap between the sprayer 1 and the disperser 6 is set to 0.6 mm.
5 By simply adjusting within the range of I~10+nm, the combustion state of the flame can be maintained without changing.
It is possible to arbitrarily change the atomic absorption sensitivity within a range of 2 to 3 times without reducing analytical accuracy, and it is effective when it is necessary to expand the dynamic range of the calibration curve by 2 to 3 times. [Effects of the Invention] As explained above, according to the present invention, the dynamic range of the calibration curve can be increased by arbitrarily adjusting the atomic absorption sensitivity without increasing noise or changing the combustion state of the flame.
It has the effect of being able to be expanded up to 3 times, and directly analyzing a sample with 2 to 3 times higher concentration without reducing the concentration by diluting the 8 sample liquids.

[Brief explanation of drawings]

Fig. 1 is a configuration diagram showing one embodiment of the sample injection device for flake T1 atomic absorption spectrometry analysis of the present invention, and Fig. 2 shows the configuration when the gap between the nozzle part of the sprayer and the disperser is changed to IMI and 5 clear. The third diagram is a diagram showing an example of the relationship between the gap between the nozzle part of the atomizer and the spherical disperser and the atomic absorption sensitivity.

Claims (1)

[Claims] 1. A sample solution containing a metal element is mixed with fuel and auxiliary fuel gas in the form of a mist and introduced into the flame, and the metal element contained in the sample solution is converted into atomic vapor by thermal decomposition. In a flame atomic absorption spectrophotometer for measuring concentration, there is a sprayer that sucks in the sample solution and releases it in the form of a mist, and a sprayer that sprays the sample solution in the form of a mist released from the nozzle of the sprayer to further atomize the mist. and a disperser that unifies the size thereof, and gap changing means that makes it possible to adjust the atomic absorption sensitivity by arbitrarily changing the gap between the nozzle part of the sprayer and the disperser. A sample spray device for flame atomic absorption spectrometry.