JP2000088756A - Sheet for detecting nitrogen dioxide - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sheet for detecting nitrogen dioxide by color reaction with stable sensitivity. SOLUTION: N-(1-naphthyl)ethylenediamine dichlorine acid salt, sulphonyl acid, paratoluenesulfone acid, alcohol humectant, preferably ethyleneglycol, are developed into a carrier sheet material, and an azoic dye is generated by nitrogen dioxide. Also, a fine-powder silica gel for accelerating reaction or alumina is preferably carried by the above sheet material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas detection sheet for detecting nitrogen dioxide present in a gas such as air by a color reaction.

[0002]

2. Description of the Related Art Nitrogen dioxide present in the atmosphere is usually
Although an electrochemical gas sensor is used, it has a certain sensitivity to gases other than nitrogen dioxide, so that there is a problem that a measurement error occurs particularly in detecting a low concentration of nitrogen dioxide. On the other hand, in order to detect nitrogen dioxide with high selectivity, it is conceivable to use a detection tube for nitrogen dioxide detection in which orthotolidine is supported on silica gel or the like, but it is necessary to replace the detection tube every time measurement is performed. There is a problem that it is difficult to automate the measurement.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has been made in consideration of the above-mentioned problems. To provide a seat.

[0004]

In order to solve such a problem, the present invention provides N- (1-naphthyl) ethylenediamine dichloride, sulfanilic acid, paratoluenesulfonic acid, and an alcohol-based humectant. Expanded to supporting sheet material.

[0005]

An azo dye is produced in proportion to the concentration of nitrogen dioxide in the air to form a reaction mark.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described below based on embodiments. A humectant such as N- (1-naphthyl) ethylenediamine dichloride, sulfanilic acid, paratoluenesulfonic acid, ethylene glycol or glycerin is dissolved in a volatile solvent, for example, methanol to prepare a color developing solution.

[0007] The color developing solution is impregnated into a supporting sheet material, for example, a filter paper made of cellulose, and the ethanol is volatilized while being heated if necessary. As the supporting sheet material, a material in which fine powder such as silica gel or alumina is mixed in advance in order to promote the reaction is used, or the fine powder such as silica gel or alumina is mixed in the coloring solution and supported on the sheet material. It is desirable.

After the methanol has been volatilized, N- (1-naphthyl) ethylenediamine dichlorate, sulfanilic acid, paratoluenesulfonic acid,
The humectant is spread and held on the sheet material.

In the detection sheet thus configured,
When a sampling gas containing nitrogen dioxide is exposed for a certain period of time,
An azo dye proportional to the concentration of nitrogen dioxide is formed on the surface of the sheet material to form a reaction mark. In particular, since para-toluenesulfonic acid having a large molecular weight is used as an acid as a stabilizer for miscellaneous gases, a long-term storage and a small amount of volatilization with respect to the gas flow by sampling are also small.
Sensitivity can be maintained stably. The concentration of nitrogen dioxide can be measured by measuring the optical density of the reaction mark using an absorption band of an azo dye produced by the reaction, for example, light having a wavelength of about 545 nm.

This sheet material can be cut into a tape and used as a detection tape for an automatic measuring device, or cut as a piece of paper and used as a detection material for a detection badge.

In particular, when the tape 1 is processed, the tape 1 is housed in a cassette 2 as shown in FIG. 1 (a), and the tape transport mechanism 3 moves the tape 1 to a sampling head 6 having a light emitting element 4 and a light receiving element 5 for a predetermined time. It can be transported every time,
Nitrogen dioxide can be measured automatically. The sampling head 6 is connected to the environment to be measured via a sampling pipe 7 and is configured to seal the tape 1 in cooperation with a suction head 9 connected to a suction pump via a pipe 8. I have.

By operating the suction pump for a certain period of time, a predetermined amount of air passes through the tape 1 and a reaction mark proportional to the concentration of nitrogen dioxide is formed on the tape 1.
Formed. The concentration of nitrogen dioxide can be measured by detecting the relative optical density of the reaction trace using the light emitting element 4 and the light receiving element 5.

FIG. 2 shows an example of a calibration curve of the above-mentioned sheet for detecting nitrogen dioxide. In FIG. 2, symbol A denotes ethylene glycol as a humectant, and symbol B denotes a concentration of 0.1 ppm when glycerin is used. As is clear from this figure, the measurement sensitivity of the sample using ethylene glycol as the humectant is about twice as high as that using glycerin.

In the above embodiment, the fluid to be measured is caused to pass through the sheet material and reacted.
As shown in (b), a cap body 10 for sealing one surface of the tape 1 has an inlet 11 on one side and an outlet 1 on the other end.
2, the same measurement can be performed even when the fluid to be measured flows through one surface of the sheet material by using a sampling head constituted by providing the light emitting element and the light receiving element described above.

Although a filter paper made of cellulose as a raw material is used as a material constituting the sheet material, a sheet material having a solvophilic property and capable of holding a humectant such as glycerin, for example, a porous material is used. The same effect is exerted by using the prepared polymer sheet material.

Further, as an easily volatile solvent, ethanol which dissolves N- (1-naphthyl) ethylenediamine dichlorate, sulfanilic acid, paratoluenesulfonic acid, a humectant and does not react with these is used. Polyhydric alcohol-based materials such as ethylene glycol can be used as the humectant.

[0017]

As described above, in the present invention, since N- (1-naphthyl) ethylenediamine dichloride, sulfanilic acid, paratoluenesulfonic acid and a humectant are developed on the supporting sheet material, By reacting with nitrogen, an azo dye proportional to the concentration of nitrogen dioxide is generated, and nitrogen dioxide can be detected with stable sensitivity as the optical density of the reaction trace.

[Brief description of the drawings]

FIGS. 1 (a) and 1 (b) are a diagram showing an embodiment of a measuring device which uses a sheet for detecting dioxide dioxide by shaping it into a tape, and a diagram showing another embodiment of a sampling head, respectively. .

FIG. 2 is a diagram showing a relationship between a sampling time and a response value of the sheet for detecting nitrogen dioxide of the present invention.

Claims (3)

[Claims] 1. A nitrogen dioxide detection sheet in which N- (1-naphthyl) ethylenediamine dichloride, sulfanilic acid, p-toluenesulfonic acid, and an alcohol-based humectant are spread on a supporting sheet material. 2. The nitrogen dioxide detecting sheet according to claim 1, wherein the alcohol-based humectant is ethylene glycol. 3. The sheet for detecting nitrogen dioxide according to claim 1, wherein fine silica gel or alumina for reaction promotion is supported on the sheet material.