JPS6058821B2 - Sample atomization device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a sample atomization device, and is particularly useful in flameless atomic absorption spectrometry when using samples that contain a large amount of organic matter such as blood and have a certain degree of viscosity, for which the measurement conditions are relatively complicated to set. The present invention relates to a sample atomization device suitable for use in measurements.

Most graphite cubes in sample atomization devices used in conventional flameless atomic absorption spectroscopy have a cylindrical shape.

In the case of a cylindrical structure, the sample is injected into the atomic absorption part, which is the optical path of the resonant emission line emitted from the hollow cathode lamp. That is, the sample is dried and incinerated on the optical axis of the resonant emission line, and the target element is atomized. Furthermore, the temperature during heating of the cuvette has a temperature distribution such that the center is the highest temperature and the temperature decreases toward the ends. For this reason, the measurement conditions, especially the drying stage, may be inappropriate, the amount of sample injected may be too large, or depending on the condition of the sample, the injected sample may reach the relatively low-temperature end of the cuvette. Due to diffusion and non-uniform heating temperature of the sample, the types of compounds of the target element become complicated during the ashing stage, and during atomization, this may cause fractional evaporation of the target element or temperature fluctuations. The atomic absorption peaks may be separated due to time difference evaporation due to the distribution, resulting in a decrease in measurement accuracy. Furthermore, when measuring samples that contain a large amount of organic matter and have high viscosity, such as blood or serum, bumping and bubbling occur during the drying stage, causing the sample to scatter to the edges of the cuvette, reducing measurement accuracy. It often happens. For this reason, when measuring this type of sample in particular, it is necessary to take great care in setting the temperature and time of the drying stage, but the operation is complicated and difficult. Bumping can be prevented by changing the heating method or lowering the temperature, but this requires a long heating time. Although it depends on the condition of the sample, it takes several minutes to a sufficient amount of time to dry. This makes it impossible to take advantage of the speed, which is one of the characteristics of frameless atomic absorption spectrometry. In addition, this type of sample has poor drying efficiency and the surface dries relatively quickly while the internal drying process is delayed, making it difficult to determine the end of drying, and the sample may move to the ashing stage without sufficient drying. This may cause rapid evaporation and cause the sample to scatter. Furthermore, it is almost impossible to prevent the phenomenon of foaming. When the sample foams, the foamed sample diffuses to the end of the cuvette where the temperature is relatively low, and due to the uneven heating temperature during the ashing stage due to the temperature distribution of the cuvette during heating, the compound of the target element is formed. When there are multiple types of elements, the target element may be evaporated separately during atomization, or evaporation may occur at different times due to temperature distribution, resulting in separate atomic absorption peaks and reduced measurement accuracy. An object of the present invention is to provide a sample atomization device that can perform measurements quickly and with high precision.

Therefore, the present invention provides a graphite cube for heating and atomizing a sample, a pair of graphite cones for supplying current to the graphite cube, a sample injection part removably provided in the graphite cube, and It is composed of porous graphite particles filled in the injection part.

1 and 2 illustrate one embodiment of the present invention.

FIG. 1 shows the sample injection section 1 removed from the atomic absorption section 2. In FIG. At the bottom of the sample injection section 1, there is a 0.2~2? It is provided with ventilation holes 4 of the same diameter. Further, the inside of the sample injection section 1 is filled with porous graphite particles 3 having a diameter larger than that of the vent hole 4 . A predetermined amount of sample is weighed and injected into the sample injection section 1 prepared for the number of samples.

The injected sample is adsorbed by the porous graphite grains 3 and does not flow down from the vent hole 4. Then, they are thoroughly dried all at once using another drying method, such as an old-fashioned dryer or an electric dryer. The sample has a large contact area with graphite due to the porous graphite particles 3, which increases the drying efficiency, suppresses foaming of the sample, and shortens the drying time. After the batch drying is completed, the graphite cone 5 is sandwiched between a pair of graphite cones 5 with a constant force such as a spring. The sample injection section 1 is inserted and mounted into the sample injection section mounting hole 8 provided at the upper center of the atomic absorption section 2, which is mounted in this state. This state is shown in FIG. Resonance line 7 emitted from a hollow cathode lamp
passes through the inside of the atomic absorption section 2. Atomic absorption part 2. After attaching the sample injection part 1 to the sample, first, by passing a current corresponding to the optimum temperature for ashing the sample, the atomic absorption part 2 and the sample injection part 1 are heated by the generated Joule heat, and the sample is heated. is turned into ashes. Even in the ashing stage, the efficiency is increased due to the graphite grains 3 filled in.Next, a current corresponding to the optimum temperature for atomizing the target element is passed.Similarly, the atomic absorption part 2 and the sample injection part 1 is heated and the target element is atomized.The generated atomic vapor 9 of the target element is heated at a constant pressure,
Atomic absorption photometry is performed by being guided to the atomic absorption section 2 by a carrier gas 6 that passes through the sample injection section 1 at a constant flow rate and flows into the atomic absorption section 2 from the vent hole 4. Sequentially,
Change the sample injection part 1 and repeat the measurement. When this method is used, it is difficult to set the conditions because bumping and foaming occurs especially during the drying stage, and it is quite difficult to set the conditions and requires a long time. In the case of measurement, the drying step is omitted and the effect is that high-precision measurement can be performed quickly and with a simple operation. In addition, in this method, the relationship between current and temperature during heating of the graphite cube is caused by the resistivity of the atomic absorption part 2, so drying, ashing, and atomic absorption photometry of the sample using conventional techniques can be performed at the same time.・In the case of cuvettes carried out on-site, changing the cuvette will cause the relationship between current and temperature to change (7), making it impossible to use; however, according to the present invention, the atomic absorption part caused by the relationship between current and temperature Since 2 uses the same sample injection part 1 and only changes the sample injection part 1, the relationship between current and temperature can always be kept almost constant. When the number of samples is small or when measuring a general aqueous solution sample, the sample injection section 1 is attached to the atomic absorption section 2 as shown in Figure 2, and a fixed amount of the sample is inserted into the sample injection section 1. Weigh out and inject.

The sample is adsorbed by the porous graphite grains 3 filled inside the sample injection section 1, so that it can be prevented from flowing down from the ventilation hole 4 into the atomic absorption section 2. Set and measure the current and time corresponding to the optimal temperature for drying the sample, ashing it, and atomizing the target element. In this case, the sample has a larger contact area with graphite due to the porous graphite particles 3 filled inside the sample injection part 1, so that drying efficiency is increased and bubbling can be prevented during the drying stage. Therefore, there is an effect that the conditions for the drying stage can be easily set. Further, the temperature during heating of the atomic absorption part 2 has a temperature distribution such that the temperature is highest at the center and becomes lower as it approaches the ends, that is, the contact part with the graphite cone 5, similar to the conventional cube. However, even if the sample generates bubbles during the drying stage, the sample will not be diffused into the atomic absorption section 2, which has a temperature distribution, due to the porous graphite particles 3 filled in the sample injection section 1. . Therefore, by being installed at the center of the atomic absorption section 2, which has the highest temperature, the sample is heated relatively uniformly during the drying and ashing stages inside the sample injection section 1, which has no temperature distribution. As a result, the target element does not form multiple compounds in the ashing stage, and therefore, in the atomization stage, there is no fractional evaporation or time difference evaporation due to temperature distribution, which has the effect of allowing highly accurate measurements. Furthermore, as shown in Fig. 1, the sample injection section 1 is removed from the atomic absorption section 2, the sample is injected, and after drying using another drying means, the sample injection section 1 is attached to the atomic absorption section 2. In either case, a method in which the sample is injected with the sample injection part 1 attached to the atomic absorption part 2 and then dried, incinerated and atomized is carried out. Also, the sample is injected into the sample injection part 1 which is off the optical axis of the resonant emission line 7 emitted from the hollow cathode lamp, and is dried and incinerated, so that unnecessary sample injection for atomic absorption analysis is performed. There are effects such as blocking of the resonance emission line 7 due to bubbling of the sample and no recording of abnormal or ordinary absorption due to refraction or the like. Note that the porous graphite particles 3 improve not only the drying efficiency but also the ashing efficiency. Therefore, less smoke is generated during the atomization stage, which has the effect of lowering background absorption. Figures 3, 4 and 5
The figure shows a comparison of examples of measured spectra according to the prior art and the present invention.

FIG. 3 is an example of a measured spectrum according to the conventional technique. In the conventional technique, a sample is injected onto the optical axis of a resonant emission beam emitted from a hollow cathode lamp, and the sample is dried and incinerated to atomize the target element. Therefore, a shock peak 11 appears due to the interruption of the resonance emission line during sample injection. Further, during the drying stage, when the sample bubbles, an absorption peak 12 is recorded because the resonance emission line is blocked or refracted. These absorptions are unnecessary for atomic absorption spectrometry. In particular, setting the conditions for the drying stage may be complicated and require a long time depending on the sample. Furthermore, when the sample bubbles during the drying stage, the sample diffuses through the interior of the cuvette, which has a temperature distribution, to the end where the temperature is relatively low. In this case, the heating temperature of the sample in the ashing stage becomes non-uniform due to temperature distribution, resulting in a plurality of types of compounds of the target element. Therefore, fractional evaporation occurs during the atomization stage. In addition, time difference evaporation occurs due to temperature distribution, resulting in abnormal atomic absorption 13 in which the atomic absorption spectrum is stepped or separated, reducing sensitivity and measurement accuracy. FIG. 4 is an example of a measured spectrum when a sample is injected with the sample injection section attached to the atomic absorption section according to the present invention.

Injection of the sample, drying, ashing, and atomization of the target element are performed at a sample injection part that is outside the resonance emission line, so unnecessary absorption peaks due to sample injection and bubbling are not recorded. In addition, even if the sample bubbles, it will not be diffused into the atomic absorption part that has a temperature distribution, making it easier to set the conditions for the drying stage and shortening the drying time. Since the heating temperature is uniform, the target element is atomized without causing fractional evaporation or time difference evaporation, so that normal atomic absorption 14 with high sensitivity and high precision can be obtained at all times. Figure 5 is also an example of a measured spectrum obtained by removing the sample injection section from the atomic absorption section, injecting the sample, and drying all the samples at once using another drying method, which is according to the present invention. be.

In this case, the drying step, which requires complicated setting of conditions, can be omitted, so that the measurement can be completed in a short time. Normal atomic absorption 14 is obtained. FIG. 6 shows another embodiment of the present invention. The difference from FIGS. 1 and 2 is that a lid 10 is provided on the top of the sample injection section 1, and the inside of the sample injection section 1 is sealed. That's true.

In the case of this embodiment, the atomic vapor of the target element generated during the atomization step is introduced into the atomic absorption section 2 through the vent hole 4 by thermal expansion inside the sample injection section 1 at high temperatures, and the atomic vapor is introduced into the atomic absorption section 2 through the vent hole 4. Absorption photometry is performed. This has the effect of eliminating the need for carrier gas. The measurement effects in this example are the same as those in FIGS. 1 and 2. According to an embodiment of the present invention, especially when measuring a sample that contains a large amount of organic matter such as blood or serum and has a high viscosity, the drying step, which requires the most complicated measurement conditions, can be replaced by other drying methods, such as natural drying or drying. The measurement operation becomes easier by being able to use an electric dryer or the like instead.

In addition, even if the sample bubbles during the drying stage, the sample will not be dispersed and can be heated uniformly during the ashing and atomization stages, so the target element will not undergo fractional evaporation or differential evaporation, resulting in always high accuracy. measurements can be made. Furthermore, drying,
Since the ashing efficiency is increased, drying becomes easier and background absorption during the atomization stage can be reduced. Furthermore, since the sample is injected and dried at a location away from the optical axis of the resonant emission line, absorption peaks that are unnecessary for atomic absorption analysis may occur due to blocking and refraction of the resonant emission line due to bubbles during sample injection, and the occurrence of unnecessary absorption peaks in the baseline. This has the advantage of being able to obtain an ideal measurement spectrum without disturbance. According to the present invention, measurements can be performed quickly and with high precision.

[Brief explanation of the drawing]

1 and 2 are cross-sectional views showing embodiments of the present invention; FIGS. 3, 4, and 5 are comparative views showing examples of measured spectra according to the conventional technology and the present invention; and FIG. FIG. 3 is a sectional view showing a modification of the present invention. 1... Sample injection section, 2... Atomic absorption section.

Claims (1)

[Claims] 1. A graphite cube for heating and atomizing a sample, a pair of graphite cones for supplying current to the graphite cube, a sample injection part removably provided in the graphite cube, and a sample injection part filled in the sample injection part. A sample atomization device characterized by comprising porous graphite grains.