JP7212223B2 - Method for measuring nonanal and nonanal detection element - Google Patents

Description

The present invention relates to a method for measuring gaseous nonanal and a nonanal sensing element.

Nonanal is a kind of volatile organic compounds used in fragrances and the like, and has a relatively large molecular weight among aldehydes. Since it is sometimes measured in an indoor environment, it cannot be said that it is unrelated to sick house syndrome. In recent years, it has become clear that the breath of lung cancer patients contains more nonanal than healthy subjects.

For this reason, various sensors, detection tubes, and detection elements have been proposed for simply detecting the concentration of volatile organic compounds in gases. For example, a compact gas sensor that uses a semiconductor to detect the concentration of volatile organic compounds is on the market (see Non-Patent Document 1). However, this sensor cannot identify volatile organic compounds.

Moreover, there is a technique for detecting aldehydes in volatile organic compounds using a Schiff reagent (see Patent Documents 1, 2, and 3). Patent Document 1 describes that formaldehyde can be detected in a gel composition using pararoseaniline hydrochloride and sulfonic acid. Further, Patent Document 2 describes that formaldehyde can be detected using a Schiff reagent composed of basic fuchsine and sulfuric acid or phosphoric acid on a porous body. Further, Patent Document 3 describes that propionaldehyde, nonanal, and benzaldehyde can be detected in a solution or using a porous body using a Schiff reagent composed of basic fuchsine, sulfuric acid, or phosphoric acid. However, in the case of a mixed gas of relatively low-molecular-weight aldehydes such as formaldehyde and nonanal, these measurement techniques must measure both aldehydes, and complex spectral analysis is required to selectively measure nonanal. is required, and it cannot be measured easily and with high sensitivity.

A method using a detector tube is known for simple measurement of volatile organic compounds, but there is no detector tube for measuring nonanal in the method using a detector tube.

JP 2005-003673 A JP 2008-224590 A JP 2011-154014 A Japanese Patent No. 3639123

https://www.new-cosmos.co.jp/product/?fb=b90

As explained above, the related technology can selectively detect nonanal in a gas containing, for example, multiple aldehydes present in the environment, particularly formaldehyde and acetaldehyde, which are likely to be present in the environment, as well as nonanal. However, there was a problem that the measurement could not be performed easily.

The present invention has been made to solve the above-described problems, and an object of the present invention is to facilitate the measurement of nonanal with high selectivity.

The measurement method of the present invention is a method for measuring nonanal contained in a gas to be measured, and comprises a first step of adjusting a solution having a pH of 1 to 4 in which a pararoseaniline derivative is dissolved; a second step of measuring the light transmittance of the sensing element made by impregnating the solution therein prior to exposure to the gas to be measured; a third step of measuring the light transmittance of the exposed sensing element; and placing the exposed sensing element in clean gas for a predetermined time, and then measuring the light transmittance of the still standing sensing element. and a fourth step of performing.

The nonanal sensing element of the present invention is characterized by being produced by impregnating a porous body made of glass with a solution having a pH of 1 to 4 in which a pararoseaniline derivative is dissolved.

According to the present invention, a sensing element (nonanal sensing element) produced by impregnating a porous body with a solution having a pH of 1 to 4 in which a pararoseaniline derivative is dissolved is exposed to a gas to be measured and statically immersed in a clean gas. Selective measurement of nonanal is carried out according to the state of coloration (absorption spectrum) change due to placement, so it has an excellent effect that nonanal can be easily measured even in a gas in which multiple aldehydes such as formaldehyde and acetaldehyde are mixed. can get.

BRIEF DESCRIPTION OF THE DRAWINGS It is process drawing for demonstrating the measuring method of aldehydes in embodiment of this invention. FIG. 4 is a characteristic diagram showing results of measurement of absorbance in Embodiment 1 of the present invention. FIG. 4 is a characteristic diagram showing results of measurement of absorbance in Embodiment 1 of the present invention. FIG. 4 is a characteristic diagram showing results of measurement of absorbance in Embodiment 1 of the present invention. FIG. 10 is a characteristic diagram showing results of measurement of absorbance in Embodiment 2 of the present invention. FIG. 10 is a characteristic diagram showing results of measurement of absorbance in Embodiment 2 of the present invention. FIG. 4 is a characteristic diagram showing the result of change in absorbance over time in Comparative Example 1 of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, such an embodiment does not limit the technical scope of the present invention.

[Embodiment 1]
First, Embodiment 1 of the present invention will be described. A method for measuring nonanal will be described below together with fabrication of the sensing element according to the first embodiment.

First, the fabrication of the sensing element will be described. As shown in FIG. 1(a), pararoseaniline hydrochloride, which is a pararoseaniline derivative, is dissolved in hot water, and after cooling, hydrochloric acid and anhydrous sodium sulfite are added. A sensing solution 101 consisting of the added solution is produced in container 102 . The pH of this sensing solution is 3±0.5 (first step). The pH range of the detection solution is adjusted by hydrochloric acid to be in the range of 1 or more and 4 or less (1 to 4). Anhydrous sodium sulfite has the effect of making pararoseaniline hydrochloride colorless. Next, as shown in FIG. 1B, a porous body 103 made of porous glass having an average pore diameter of 4 nm is immersed in a detection solution 101 . The porous body 103 has a chip size of, for example, 8 (mm)×8 (mm) and a thickness of 1 (mm). The average pore size of the porous body 103 is preferably 20 nm or less. Also, although the porous body is plate-shaped here, it is not limited to this, and may be formed into a fiber-like shape.

When the porous body 103 is made of glass (borosilicate glass), by setting the average pore diameter to 20 nm or less, light can be transmitted in the visible region (400 to 800 nm) in the measurement of the transmission spectrum in the visible UV wavelength region. . However, it has been found that when the average pore diameter exceeds 20 nm, a rapid decrease in transmittance is observed in the visible region (see Patent Document 4). For this reason, the average pore size of the porous body should be 20 nm or less. The specific surface area of the porous body 103 in this embodiment is 100 m ² or more per 1 g.

The porous body 103 described above is immersed in the detection solution 101 for 24 hours, and the pores of the porous body 103 are impregnated with the detection solution. , and dried by standing in a nitrogen gas stream for 24 hours to fabricate the sensing element 103a. Therefore, a sensing agent containing pararoseaniline hydrochloride is introduced into the sensing element 103a, and the sensing agent having a pH of 3±0.5 is carried in the porous pores of the sensing element 103a.

Next, a method for measuring nonanal using the sensing element 103a will be described.

First, the transmittance of light in the thickness direction of the sensing element 103a is measured to obtain the absorbance (second step). Next, as shown in FIG. 1(d), the sensing element 103a is exposed, for example, for 24 hours in a gas 104 to be measured, in which nonanal gas is present at a concentration of 250 ppb. This exposure is done at room temperature. Thereafter, the exposed sensing element 103a is taken out from the gas 104 to be measured, and as shown in FIG. Ask (third step). Thereafter, the exposed sensing element 103a is allowed to stand in clean air free of nonanal and aldehydes for at least 24 hours, and then the transmittance of light in the thickness direction of the sensing element 103a is measured to obtain the absorbance (first four steps). After obtaining the absorbance in this way, nonanal contained in the gas is quantified from the obtained absorbance spectrum (absorption spectrum) and the absorbance. The absorption spectrum is characteristic of the product from the reaction with nonanal and exhibits an absorption with an absorption maximum at 585 nm.

FIG. 2 shows the results of the absorbance measurement described above. As shown in FIG. 2, there is a large difference between the post-exposure absorption spectrum and the pre-exposure absorption spectrum in the wavelength range of approximately 550 to 650 nm centered around the wavelength of 585 nm. Subtracting the pre-exposure absorption spectrum from the post-exposure absorption spectrum reveals an absorption maximum at approximately 585 nm, which is characteristic of the product from the reaction with nonanal.

Moreover, this absorption does not attenuate even after standing in a clean gas, and the absorbance increases. The absorbance increases over about 70 hours and gives a constant value (it does not decrease after the increase), but since it gives 90% of the constant value after 48 hours, nonanal can be quantified with high accuracy using the absorbance value after 48 hours. It is possible. FIG. 2 exemplifies the absorption spectrum after standing for 32 hours, and shows a state in which the absorbance is higher than the absorption spectrum after exposure. The absorption having an absorption maximum at 538 nm existing before exposure is the absorption of pararoseaniline.

Next, measurement of formaldehyde using the detection element 103a will be described.

First, the transmittance of light in the thickness direction of the sensing element 103a is measured to obtain the absorbance (second step). Next, as shown in FIG. 1(d), the sensing element 103a is exposed, for example, for 24 hours in a gas 104 to be measured, in which formaldehyde gas is present at a concentration of 150 ppb. This exposure is done at room temperature. Thereafter, the exposed sensing element 103a is taken out from the gas 104 to be measured, and as shown in FIG. Ask (third step). After that, the exposed sensing element 103a is allowed to stand in clean air free of aldehydes for at least 1 hour (preferably about 5 hours), and then the light transmittance in the thickness direction of the sensing element 103a is measured. Determine the absorbance (fourth step). After obtaining the absorbance in this way, the obtained absorbance spectrum (absorption spectrum) and the absorbance are compared with nonanal.

FIG. 3 shows the results of the absorbance measurement described above. Subtracting the pre-exposure absorption spectrum from the post-exposure absorption spectrum reveals an absorption maximum at approximately 585 nm, which is characteristic of the product from reaction with formaldehyde. That is, the spectrum of absorbance immediately after exposure shows an absorbance with an absorption maximum at 585 nm with characteristic features of the product of reaction with formaldehyde. However, this absorption attenuates after one hour of standing in clean gas, and the absorbance at 585 nm is similar to that before exposure. FIG. 3 exemplifies the absorption spectrum after standing for 1 hour, and the absorbance around 585 nm has returned to the same level as the absorption spectrum before exposure. The absorption having an absorption maximum at 538 nm existing before exposure is the absorption of pararoseaniline.

In the case of formaldehyde, the absorption of the product due to the reaction with formaldehyde, which shows absorption at 585 nm, can be confirmed immediately after exposure, but cannot be confirmed after standing in clean air. This is because the reaction between formaldehyde and pararoseaniline is reversible, and when they are exposed to formaldehyde-containing air, a product is produced by the reaction of the two. is thought to return to the reactant. It should be noted that the slight difference in absorbance between before exposure and after standing for 1 hour in FIG. 3 is considered to be due to the difference in water content. Therefore, when trying to measure nonanal in a gas containing a mixture of formaldehyde and nonanal, the reaction product with nonanal is stable as it is by allowing the sensing element to stand still for a predetermined period of time after exposure. , the product from the reaction with formaldehyde is unstable, and nonanal can be measured with better selectivity.

Next, measurement of acetaldehyde using the detection element 103a will be described.

First, the transmittance of light in the thickness direction of the sensing element 103a is measured to obtain the absorbance (second step). Next, as shown in FIG. 1(d), the sensing element 103a is exposed, for example, for 24 hours to a gas 104 to be measured in which acetaldehyde gas is present at a concentration of 150 ppb. This exposure is done at room temperature. Thereafter, the exposed sensing element 103a is taken out from the gas 104 to be measured, and as shown in FIG. Ask (third step). Thereafter, the exposed sensing element 103a is allowed to stand in clean air free of aldehydes for 1 hour, and then the transmittance of light in the thickness direction of the sensing element 103a is measured to obtain the absorbance (fourth step). . After obtaining the absorbance in this manner, comparison with nonanal is performed from the obtained absorbance spectrum and absorbance.

FIG. 4 shows the results of the absorbance measurement described above. As shown in FIG. 4, the absorbance spectrum immediately after exposure was the same as before exposure, and no new absorption appeared. The pH is an important factor in the reaction between aldehydes and Schiff's reagent, and in the case of acetaldehyde, it is considered that the pH was in the region where it was difficult to form a reaction product. Therefore, when trying to measure nonanal in a gas containing a mixture of acetaldehyde and nonanal, only nonanal reacts with the detection solution in the porous glass, and the product is stable as it is, but acetaldehyde Since the reaction with does not occur, it is possible to measure nonanal with better selectivity.

[Embodiment 2]
Next, Embodiment 2 of the present invention will be described. The method for measuring nonanal will be described below together with the fabrication of the sensing element according to the second embodiment.

First, the fabrication of the sensing element will be described. As shown in FIG. 1(a), pararoseaniline hydrochloride, which is a pararoseaniline derivative, is dissolved in hot water, and after cooling, hydrochloric acid, anhydrous sodium sulfite, and acetic acid is added to the sensing solution 101 is prepared in the container 102 . The pH of this solution is 2±0.5 (first step). The pH range of the detection solution is adjusted with hydrochloric acid and acetic acid so as to be in the range of 1 or more and 4 or less (1 to 4). Anhydrous sodium sulfite has the effect of making pararoseaniline hydrochloride colorless. Next, as shown in FIG. 1B, a porous body 103 made of porous glass having an average pore diameter of 4 nm is immersed in a detection solution 101 . The porous body 103 has a chip size of, for example, 8 (mm)×8 (mm) and a thickness of 1 (mm). The average pore size of the porous body 103 is preferably 20 nm or less. Also, although the porous body is plate-shaped here, it is not limited to this, and may be formed into a fiber-like shape.

When the porous body 103 is made of glass (borosilicate glass), by setting the average pore diameter to 20 nm or less, light can be transmitted in the visible region (400 to 800 nm) in the measurement of the transmission spectrum in the visible UV wavelength region. . However, it has been found that when the average pore diameter exceeds 20 nm, a rapid decrease in transmittance is observed in the visible region (see Patent Document 4). For this reason, the average pore size of the porous body should be 20 nm or less. The specific surface area of the porous body 103 in this embodiment is 100 m ² or more per 1 g.

The porous body 103 described above is immersed in the detection solution 101 for 24 hours, and the pores of the porous body 103 are impregnated with the detection solution. , and dried by standing in a nitrogen gas stream for 24 hours to fabricate the sensing element 103a. Therefore, the sensing agent containing pararoseaniline hydrochloride is introduced into the sensing element 103a, and the sensing agent having a pH of 2±0.5 is carried in the porous pores of the sensing element 103a.

Next, a method for measuring nonanal using the sensing element 103a will be described.

First, the transmittance of light in the thickness direction of the sensing element 103a is measured to obtain the absorbance (second step). Next, as shown in FIG. 1(d), the sensing element 103a is exposed, for example, for 24 hours in a gas 104 to be measured, in which nonanal gas is present at a concentration of 250 ppb. This exposure is done at room temperature. Thereafter, the exposed sensing element 103a is taken out from the gas 104 to be measured, and as shown in FIG. Ask (third step). Thereafter, the exposed sensing element 103a is allowed to stand in clean air free of nonanal and aldehydes for 24 hours, and then the transmittance of light in the thickness direction of the sensing element 103a is measured to determine the absorbance (fourth step). After obtaining the absorbance in this manner, nonanal contained in the gas is quantified from the obtained absorbance spectrum and absorbance. The absorbance spectrum has characteristics unique to nonanal, with an absorption peak at 585 nm.

FIG. 5 shows the results of the absorbance measurement described above. As shown in FIG. 5, there is a large difference between the post-exposure absorption spectrum and the pre-exposure absorption spectrum in the wavelength range of approximately 550 to 650 nm centered around the wavelength of 585 nm. Subtracting the pre-exposure absorption spectrum from the post-exposure absorption spectrum reveals an absorption maximum at approximately 585 nm, which is characteristic of the product from the reaction with nonanal.

Moreover, this absorption does not attenuate even after standing in a clean gas, and the absorbance increases. The absorbance increases over about 70 hours and gives a constant value (does not decrease after the increase), but since it gives 90% of the constant value after 48 hours, nonanal can be quantified with high accuracy using the absorbance value after 48 hours. It is possible. FIG. 5 exemplifies the absorption spectrum after standing for 45 hours, and shows a state in which the absorbance is higher than the absorption spectrum after exposure. The absorption having an absorption maximum at 538 nm existing before exposure is that of pararoseaniline.

Next, measurement of formaldehyde using the detection element 103a will be described.

First, the transmittance of light in the thickness direction of the sensing element 103a is measured to obtain the absorbance (second step). Next, as shown in FIG. 1(d), the sensing element 103a is exposed, for example, for 24 hours in a gas 104 to be measured, in which formaldehyde gas is present at a concentration of 150 ppb. This exposure is done at room temperature. Thereafter, the exposed sensing element 103a is taken out from the gas 104 to be measured, and as shown in FIG. Ask (third step). Thereafter, the exposed sensing element 103a is allowed to stand in clean air free of aldehydes for 5 hours, and then the transmittance of light in the thickness direction of the sensing element 103a is measured to obtain the absorbance (fourth step). . After obtaining the absorbance in this manner, comparison with nonanal is performed from the obtained absorbance spectrum and absorbance.

FIG. 6 shows the results of the absorbance measurement described above. Subtracting the pre-exposure absorption spectrum from the post-exposure absorption spectrum reveals an absorption maximum at approximately 600 nm, which is characteristic of the product from reaction with formaldehyde. That is, the absorbance spectrum immediately after exposure shows an absorption with an absorption maximum at 600 nm with features unique to the product of reaction with formaldehyde. However, this absorption attenuates after standing in clean gas for 5 hours, becomes less than the absorbance at 600 nm before exposure, and is not stable. FIG. 6 exemplifies the absorption spectrum after standing for 5 hours, and shows a state where the absorbance around 600 nm is lower than the absorption spectrum before exposure. The absorption having an absorption maximum at 538 nm existing before exposure is the absorption of pararoseaniline.

In the case of formaldehyde, absorption of the product appearing at 600 nm can be confirmed immediately after exposure, but cannot be confirmed after standing in clean air. This is because the reaction between formaldehyde and pararoseaniline is reversible, and when they are exposed to formaldehyde-containing air, a product is produced by the reaction of the two. is thought to return to the reactant. The difference in absorbance between before exposure and after standing for 5 hours in FIG. 6 is considered to be due to the difference in water content. Therefore, when trying to measure nonanal in a gas containing a mixture of formaldehyde and nonanal, if the sensing element is allowed to stand after exposure, the reaction product with nonanal is stable as it is, but formaldehyde The product of the reaction with is unstable, and nonanal can be measured with better selectivity.

Next, measurement of acetaldehyde using the detection element 103a will be described.

First, the transmittance of light in the thickness direction of the sensing element 103a is measured to obtain the absorbance (second step). Next, as shown in FIG. 1(d), the sensing element 103a is exposed, for example, for 24 hours to a gas 104 to be measured in which acetaldehyde gas is present at a concentration of 150 ppb. This exposure is done at room temperature. Thereafter, the exposed sensing element 103a is taken out from the gas 104 to be measured, and as shown in FIG. Ask (third step). Thereafter, the exposed sensing element 103a is allowed to stand in clean air free of aldehydes for 1 hour, and then the transmittance of light in the thickness direction of the sensing element 103a is measured to obtain the absorbance (fourth step). . After obtaining the absorbance in this manner, comparison with nonanal is performed from the obtained absorbance spectrum and absorbance. The absorbance spectrum immediately after exposure was the same as before exposure, and no new absorption appeared. The pH is an important factor in the reaction between aldehydes and Schiff's reagent, and in the case of acetaldehyde, it is considered that the pH was in the region where it was difficult to form a reaction product. Therefore, when trying to measure nonanal in a gas containing a mixture of acetaldehyde and nonanal, only nonanal reacts with the detection solution in the porous glass, and the product is stable as it is, but acetaldehyde Since the reaction with does not occur, it is possible to measure nonanal with better selectivity.

Thus, a sensing element is prepared by impregnating a porous glass with a solution having a pH of 1 to 4 in which a pararoseaniline derivative is dissolved and drying, and the absorbance (first absorption spectrum) before exposure is measured. After that, it is exposed to the gas to be measured, and the absorbance (second absorption spectrum) after the exposure is measured. After that, the exposed sensing element is allowed to stand in clean gas for 1 to 48 hours, and the absorbance (third absorption spectrum) after the standing is measured. Nonanal can be easily measured with high selectivity by comparing the first to third absorption spectra.

[Comparative Example 1]
Next, Comparative Example 1 of the present invention will be described. In the following, the production of the sensing element in Comparative Example 1 and the results of exposure to formaldehyde will be described.

First, the fabrication of the sensing element will be described. As shown in FIG. 1(a), pararoseaniline hydrochloride, which is a pararoseaniline derivative, is dissolved in hot water, and after cooling, hydrochloric acid, anhydrous sodium sulfite and A sensing solution 101 consisting of a solution to which phosphoric acid has been added is prepared in a container 102 . The pH of this solution is 0.5±0.5 (pH range less than 1) (first step). Next, as shown in FIG. 1B, a porous body 103 made of porous glass having an average pore diameter of 4 nm is immersed in a detection solution 101 . The porous body 103 has a chip size of, for example, 8 (mm)×8 (mm) and a thickness of 1 (mm).

The porous body 103 described above is immersed in the detection solution 101 for 24 hours, and the pores of the porous body 103 are impregnated with the detection solution. , and dried by standing in a nitrogen gas stream for 24 hours to fabricate the sensing element 103a. Therefore, a sensing agent containing pararoseaniline hydrochloride is introduced into the sensing element 103a, and the sensing agent having a pH of less than 1 is carried in the porous pores of the sensing element 103a.

Next, a method for measuring nonanal using the sensing element 103a will be described.

First, the transmittance of light in the thickness direction of the sensing element 103a is measured to obtain the absorbance (second step). Next, as shown in FIG. 1(d), the sensing element 103a is exposed, for example, for 24 hours in a gas 104 to be measured, in which nonanal gas is present at a concentration of 250 ppb. This exposure is done at room temperature. Thereafter, the exposed sensing element 103a is taken out from the gas 104 to be measured, and as shown in FIG. Ask (third step). Thereafter, the exposed sensing element 103a is allowed to stand in clean air free of nonanal and aldehydes for 24 hours, and then the transmittance of light in the thickness direction of the sensing element 103a is measured to determine the absorbance (fourth step). After obtaining the absorbance in this manner, nonanal contained in the gas is quantified from the obtained absorbance spectrum and absorbance. The absorbance spectrum has characteristics unique to nonanal, with an absorption peak at 617 nm. Also, this absorption increases over about 70 hours after standing in a clean gas and then decreases. This increases the error involved in nonanal measurements. FIG. 7 shows the relationship between standing time and absorbance.

Next, measurement of formaldehyde using the detection element 103a will be described.

First, the transmittance of light in the thickness direction of the sensing element 103a is measured to obtain the absorbance (second step). Next, as shown in FIG. 1(d), the sensing element 103a is exposed to the gas 104 to be measured in which, for example, formaldehyde gas is present at a concentration of 150 ppb, for example, for one hour. This exposure is done at room temperature. Thereafter, the exposed sensing element 103a is taken out from the gas 104 to be measured, and as shown in FIG. Ask (third step). Thereafter, the exposed sensing element 103a is allowed to stand in clean air free of aldehydes for 1 hour, and then the transmittance of light in the thickness direction of the sensing element 103a is measured to obtain the absorbance (fourth step). . After the absorbance is obtained in this manner, comparison with nonanal is performed from the obtained absorbance spectrum after standing and the absorbance. The spectrum of the absorbance immediately after exposure shows an absorption with an absorption maximum at 620 nm with characteristic features of formaldehyde. This absorption remained unattenuated even after standing in clean gas. Therefore, the interference of formaldehyde could not be eliminated by using this sensing element.

The present invention is not limited to the above-described embodiments, and may be modified in design without departing from the spirit of the invention, including various modifications and alterations that can be conceived by a person having ordinary knowledge in the field of the invention. is also included in the present invention.

101: sensing solution, 102: container, 103: porous body, 103a: sensing element, 103b: sensing element after exposure, 104: gas to be measured

Claims (4)

A method for measuring nonanal contained in a gas to be measured,
A first step of adjusting a solution of pH 1 to 4 in which the pararoseaniline derivative is dissolved;
a second step of measuring the light transmittance of a sensing element fabricated by impregnating the pores of a porous body made of glass with the solution before exposure to a gas to be measured;
a third step of exposing the sensing element to a gas to be measured and then measuring the light transmittance of the exposed sensing element;
and a fourth step of placing the exposed sensing element in a clean gas for a predetermined time, and then measuring the light transmittance of the still standing sensing element. Nonanal in the gas to be measured is selectively measured based on the comparison of each light transmittance measured in the second step, the third step and the fourth step. Item 1. The method for measuring nonanal according to item 1. The method for measuring nonanal according to claim 1, wherein the solution having a pH of 1 to 4 is adjusted using hydrochloric acid. The method for measuring nonanal according to claim 1, wherein the solution having a pH of 1 to 4 is adjusted using acetic acid.

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