JP2641559B2 - Hydride detection paper and hydride detection paper preparation solution - Google Patents

Description

The present invention relates to a detection tape for detecting gaseous hydride, and a preparation solution for producing the same.

(Prior art) For the detection of gaseous hydrides such as arsine and phosphine, a detection tape made by impregnating silver nitrate into filter paper as a carrier is used, and the formation of a silver compound generated by the reduction of silver nitrate by the hydride is subjected to a color reaction. It was done by using as.

According to such a method, while it is possible to easily measure the concentration of hydride which is difficult to detect by other methods,
Due to the chemical instability of silver nitrate, even if it is not exposed to a hydride gas, it turns dark brown due to the action of the hydroxyl groups of the filter paper, and there is a problem that the storage stability is extremely low.

In order to solve such a problem, it has been proposed to improve the weather resistance by nitrating a filter paper constituting a carrier with nitric acid (for example, US Pat. No. 4,420,567 and Japanese Patent Application Laid-Open No. Japanese Patent Application Laid-Open No.-99753), there is a problem that the strength of the cellulose is reduced due to the nitration treatment of the cellulose constituting the filter paper, and there is a possibility that the transfer of the tape by the automatic measuring device may be supported. .

The present invention has been made in view of such a problem, and an object thereof is a novel hydride gas detection tape that does not reduce the strength of the tape carrier while improving weather resistance. Is to provide.

It is another object of the present invention to provide a solution suitable for producing a hydride gas detection tape.

(Means for Solving the Problems) In order to solve such a problem, in the present invention,
In addition to impregnating silver nitrate and glycerin into the filter paper as a carrier, it impregnates para-toluene sulfonic acid, and suppresses the reaction between silver nitrate and cellulose without weakening the cellulose of the filter paper with the para-toluene sulfonic acid. Thus, the mechanical strength of the tape carrier was maintained and improved while maintaining the storage stability.

(Embodiment) Therefore, the details of the present invention will be described below based on an illustrated embodiment.

An adsorbent, for example, fine particles of silicic acid, magnesium oxide, aluminum oxide, or the like is applied to a filter paper as a carrier, and a pretreatment for improving a hydride gas carrying force is performed.

Silver nitrate, which is a color reaction agent that shows a color reaction by reaction with hydride on the filter paper after such pretreatment, and ethylene glycol, which absorbs moisture in the environment and promotes the reaction between silver nitrate and hydride Polyhydric alcohol-based humectants such as propylene glycol, trimethyl glycol, glycerin, and para-inhibiting the reaction between silver nitrate and cellulose.
After dissolving toluene / sulfonic acid in an organic solvent, for example, lower alcohol, this is impregnated into the filter paper which has been subjected to the above pretreatment, and the solvent is volatilized to obtain a detection tape.

When the detection tape thus configured is exposed to the gaseous hydride, first, the gaseous hydride is captured by the adsorbent and the humectant present on the surface of the carrier, and then the hydride gas is captured. Will reduce silver nitrate on the carrier in proportion to the concentration of the hydride gas. In the course of this reaction, the water absorbed by the polyhydric alcohol contributes to the reaction, so that the detection sensitivity, that is, the degree of blackening of silver nitrate is increased.

Thereby, silver nitrate will be blackened in accordance with the concentration of the hydride, and by measuring the degree of the degree of blackening with an optical densitometer or the like, the concentration of the hydride can be quantitatively grasped. .

On the other hand, when the detection tape thus configured is stored while being shielded from hydride,
Since sulfonic acid keeps silver nitrate oxidized,
Silver nitrate will maintain whiteness over an extended period of time without browning.

[Example 1] In 80 ml of methanol or ethanol, 1.0 g of silver nitrate and 15 ml (12 mg) of glycerin are added to dissolve silver nitrate.

Next, 1.0 g of para-toluene-sulfonic acid is added, and methanol or ethanol is further added so that the total amount becomes 1000 ml, to completely dissolve para-toluene-sulfonic acid.

The filter paper coated with the adsorbent in advance is immersed in the solution thus prepared for impregnation. The filter paper pulled from the solution is dried to evaporate the solvent component. As a result, a hydride gas adsorbent, glycerin as a humectant for accelerating the reaction, silver nitrate as a reactant, and para-toluenesulfonic acid as a weather resistance maintaining agent are carried on the carrier.

The detection tape configured in this way, the conventional one,
That is, as compared with the case where nitric acid was used as the weather resistance maintaining agent, the following results were obtained.

(1) Sensitivity test When a hydride gas having a concentration of 178 ppb was measured using the detection tape according to the present invention and a detection tape according to a conventional method,
Assuming that the relative sensitivity of the conventional detection tape is 1, the results shown in Table 1 were obtained.

From this, it was confirmed that sufficient detection sensitivity was obtained without using concentrated nitric acid as in the conventional method.

(2) Light resistance test The detection tape according to the present invention and the detection tape according to the conventional method were left at a position 30 cm immediately below a 20 W fluorescent lamp, and the time until the discoloration of the tape was visually recognized was measured. The results as shown in Table 2 were obtained.

In such an acceleration test, it was found that the detection tape according to the present invention has a light resistance of about 20% as compared with the conventional tape. This is a larger difference under normal use conditions.

(3) Mechanical strength test The tensile strength and the elongation of the detection tape according to the present invention and the detection table obtained by the conventional manufacturing method were measured by a paper sheet tester manufactured by Instron Corporation, and the results shown in Table 3 were obtained.

From these facts, the tape of the present invention not only shows improvement in detection sensitivity and weather resistance than the conventional product, but also has a remarkably improved mechanical strength. Inconveniences such as tape breakage, which is a problem, can be solved.

Further, the tape according to the present invention and the conventional product tape,
After containing in a desiccator containing a desiccant and forcibly dehumidifying under reduced pressure for 24 hours, the sensitivity before dehumidification was set to 1, and the relative sensitivity was examined. The results shown in Table 4 were obtained.

From this, it has been found that the tape according to the present invention enables highly reliable measurement while maintaining the detection sensitivity constant irrespective of changes in environmental humidity.

Furthermore, when the detection tape of the present invention is measured for hydride gas and left blackened for about 24 hours, the brown portion is decolorized to a white color to the extent that it cannot be distinguished from the background portion. Was found. Accordingly, by cyclically transferring the detection tape, the replacement period of the detection tape can be extended, and the maintenance of the hydride measuring device can be simplified.

[Example 2] Next, in order to examine the optimal amount of para-toluene-sulfonic acid used, the concentration of silver nitrate in the prepared solution was fixed at 1% by weight, and the concentration of the humectant was fixed at 15% by weight.
The concentration of para-toluene-sulfonic acid was varied, and the hydride detection sensitivity and the 6-month storage stability at each concentration were investigated. The results shown in Table 5 were obtained (the relative sensitivity was the detection sensitivity immediately after tape preparation). Is set to 1).

As a result, the concentration of para-toluene-sulfonic acid was reduced to 0.5 W
By setting it to T% or more, it is possible to obtain a shelf life of about six months, which is a practical period, but since para-toluene-sulfonic acid is saturated at about 3%, it may be set to 0.5 to 3%. It has been found.

Further, when the optimum concentration of the humectant was examined, para-toluene-sulfonic acid was not dissolved in the solvent containing no polyhydric alcohol as the humectant.

In addition, when the relative detection sensitivity, that is, the relative degree of blackening was investigated by changing the concentration of the humectant, as shown in FIG. 1, the tape adjusted by using 12% by weight in the solvent stage showed the highest detection sensitivity. After this, the detection sensitivity gradually decreased. From these facts, it is possible to detect a hydride in a tape made of a solution containing 0.4% to 50% by weight of a humectant, and practically, a tape containing 5% to 30% by weight of a humectant is desirable.

In other words, a certain amount of humectant is required to secure the sensitivity, but if the concentration of the humectant is too high, the sensitivity may be reduced due to a loss of contact with the analyte and silver nitrate. become.

In this example, glycerin is used as a humectant, but other polyhydric alcohols such as ethylene glycol, propylene glycol, and trimethylene glycol have the same effect, and Although alcohol was used as the solvent, it was confirmed that the same action was exerted even when another hydrophilic organic solvent for dissolving each component, such as acetone, was used.

In this embodiment, silver nitrate, polyhydric alcohol-based humectant, and para-toluene-sulfonic acid are all dissolved in an organic solvent before coating. It is apparent that the same effect can be obtained by preparing a liquid, a second liquid in which a polyhydric alcohol humectant and para-toluene / sulfonic acid are dissolved in an organic solvent, and applying the liquid in two steps.

(Effects of the Invention) As described above, in the present invention, a carrier containing cellulose as a main component is coated and impregnated with an adsorbent, silver nitrate, a humectant, and para-toluenesulfonic acid. The reduction effect of silver nitrate due to the hydroxyl groups of cellulose is suppressed as much as possible by para-toluene-sulfonic acid to prevent color development during storage, thereby enabling long-term storage, as well as environmental humidity changes. Irrespective of the above, the measurement accuracy can be maintained by maintaining the detection sensitivity as constant as possible.

Also, traces after color development can be eliminated after a certain period of time due to the oxidizing action of para-toluene-sulfonic acid, and can be reused.

Further, in the present invention, the detection tape preparation solution was prepared using silver nitrate 0.1.
5 to 2.0 wt%, humectant 5 to 30 wt%, and para-toluene
Since 0.5 to 3.0% by weight of sulfonic acid is dissolved in the organic solvent, a powerful drug such as concentrated nitric acid is not required, and safety in the production process can be improved.

[Brief description of the drawings]

FIG. 1 is a diagram showing the relationship between the polyhydric alcohol humectant and the detection sensitivity in the present invention.

Claims (2)

(57) [Claims] An adsorbent, silver nitrate, a polyhydric alcohol-based humectant, and para-toluene.
Hydride detection paper coated and impregnated with sulfonic acid. 2. Silver nitrate 0.5-2.0 wt%, polyhydric alcohol humectant 5-30 wt%, para-toluene-sulfonic acid 0.5
A hydride detection paper preparation solution prepared by dissolving about 3.0 wt% in an organic solvent.