JP2001098299A - Cleaning fluid for molecular film sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a cleaning effect on a substance having strong adsorbability by using a cleaning fluid for a molecular film sensor. SOLUTION: A remarkably high cleaning effect on a substance having strong adsorbability is obtained by using a cleaning liquid that a salt substance and an alkaline substance are mixed in a dilute solution of an organic solvent and a measurement is made with a high reproducibility. Particularly, the cleaning liquid H-L wherein the organic solvent is a dilute solution of 25-40% of ethyl alcohol, and a concentration of 8-100 mm of potassium hydroxide as the alkaline substance and 1-1,500 mM of potassium chloride as the salt substance are mixed, are safe as the cleaning liquid for a molecular film sensor by using it in a test of a food or the like and a high cleaning effect is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention cleans a molecular membrane sensor having a molecular film of an amphipathic substance or a bitter substance, and having a membrane potential that changes according to components in the liquid when immersed in the liquid. Liquid cleaning solution for a molecular film, and more particularly to a technique for improving the detergency of a substance adsorbed on a molecular film.

[0002]

2. Description of the Related Art As a sensor used for measuring taste and the like, there is a molecular film sensor using a molecular film of an amphipathic substance or a bitter substance.

[0003] This molecular membrane sensor utilizes the action of changing the membrane potential according to the components in the liquid when it is put into a liquid. When this sensor is used to actually measure a sample liquid, Is the amount of change in the potential of the membrane when immersed in the sample liquid or the membrane when immersed in the reference liquid and then again when immersed in the reference liquid. The amount of change in the potential of the sample liquid is obtained, and the components in the sample liquid are analyzed based on the amount of change.

[0004] When such measurement is continuously performed a plurality of times on the same sample or continuously on a plurality of different sample solutions, the components of the sample solution measured previously are adsorbed on the molecular membrane sensor. Doing so will affect the next measurement.

[0005] For this reason, it is desirable to wash the molecular membrane sensor each time measurement is performed to remove adsorbed substances from the molecular membrane sensor.

As a method of cleaning the molecular film sensor,
The applicant of the present application has proposed in Japanese Patent Application Laid-Open No. 8-271473 that the following six types of cleaning liquids are used.

(A) Diluent of an organic solvent such as ethanol (b) Washing liquid obtained by mixing an acid substance such as hydrochloric acid with a diluent of an organic solvent such as ethanol (c) Sodium chloride or the like (D) Washing liquid in which an acid substance such as hydrochloric acid and a salt substance such as sodium chloride are mixed in a diluting liquid of an organic solvent such as ethanol. (E) Sodium hydroxide is added in a diluting liquid of an organic solvent such as ethanol. (F) Diluent of acid such as hydrochloric acid

By using these cleaning liquids, it is possible to clean the molecular film, which has been considered difficult in the past, and the sensitivity of the molecular film sensor to a substance exhibiting a taste is improved, and the reproducibility of measurement is improved. was there.

[0009]

However, as the experiment is further repeated, it becomes negatively charged and becomes a positive polarity molecular film such as astringent tannin which is often contained in tea and red wine. It has been found that the above-mentioned cleaning solution is not sufficiently effective for a substance exhibiting strong adsorptivity, and the reproducibility of measurement is insufficient.

An object of the present invention is to provide a cleaning solution for a molecular membrane sensor having a high cleaning effect on such a substance having a high adsorptivity.

[0011]

In order to achieve the above object, a cleaning solution for a molecular membrane sensor according to the present invention has a molecular film of an amphipathic substance or a bitter substance and is immersed in the liquid. In a cleaning solution for a molecular membrane sensor whose membrane potential changes according to the components in the liquid, a salt substance and an alkali substance are mixed with a diluting liquid of an organic solvent. I have.

Further, the cleaning solution for a molecular membrane sensor according to the second aspect of the present invention is the cleaning solution for a molecular membrane sensor according to the first aspect of the present invention.
The organic solvent is a diluted solution of 25 to 40% ethanol, and potassium hydroxide is mixed as the alkaline substance at a concentration of 8 mM to 100 mM, and potassium chloride as the salt substance is mixed at a concentration of 1 mM to 1500 mM. .

[0013]

Embodiments of the present invention will be described below with reference to the drawings. By repeating further experiments, the inventors use a mixture of a salt solution and an alkali material in a diluent of an organic solvent as a cleaning solution for a substance strongly adsorbed to a molecular membrane sensor such as tannin or the like. As a result, they found that the cleaning effect was significantly improved.

The details of the experiment will be described below.
For this experiment, the system shown in FIG. 1 was used.

This system comprises a container 11 for containing a reference solution, a sample solution or a washing solution, a reference electrode 12, a molecular film sensor 15, and a voltage for detecting the voltage of the molecular film sensor 15 with reference to the potential of the reference electrode 12. Voltage detector 20,
A / D for converting the output of voltage detector 20 to a digital value
It comprises a converter 21, an arithmetic unit 22 for performing arithmetic processing on the output of the A / D converter 21, and an output unit 23 for outputting the processing result of the arithmetic unit 22.

Here, the surface of the reference electrode 12 is covered with a buffer layer 13 obtained by solidifying 100 mM of potassium chloride with agar, and is connected to the voltage detector 20 by a lead wire 12a.

The molecular film sensor 15 to be cleaned is
A molecular film 17 is fixed on the surface of a base material 16 made of acrylic or the like, and an electrode 19 is provided on the opposite surface of the molecular film 17 via a buffer layer 18 identical to the buffer layer 13 of the reference electrode 12. The electrode 19 is connected to a voltage detector 20 by a lead 15a.

The molecular film 17 is formed by mixing an amphipathic substance or bitter substance such as lipid, a plasticizer, and a polymer material. In this example, the molecular film has a positive polarity. And 50 mg of TDA (tetradodecyl ammonium bromide) having a carbon chain length of 12 (R = 12) in the lipid of the quaternary ammonium salt, and DO as a plasticizer.
PP (dioctylphenylphosphonate) 0.6m
l and PCV (polyvinyl chloride) 800 as a polymer material
mg of THF (tetrahydrofuran)
Dissolve it in 10 ml and place it in a flat-bottomed container (eg, 85 mm
In a Petri dish of φ), heat at about 30 ° C for 2 hours,
The one having a thickness of 200 μm obtained by volatilizing F is used.

The components of the cleaning solution are ethanol as an organic solvent, potassium chloride (KCl) as a salt substance and potassium hydroxide (KOH) as an alkali substance. L was prepared.

(A) A mixture of 100 mM KOH and 100 m of KCl in a 30% ethanol solution. (B) 8% KOH in a 25% ethanol solution.
A mixture of 1 mM of KCl and 1 mM of KCl.
A mixture of 00 mM and 300 mM KCl. (D) 5% KOH was added to a 20% ethanol solution.
1 mM KOH mixed with 1 mM KOH (E)
A mixture of 00 mM and 1000 mM KCl. (F) 8% KOH was added to a 35% ethanol solution.
A mixture of 0 mM and 1000 mM KCl. (G) 1% KOH in a 30% ethanol solution
A mixture containing 0 mM (conventional washing solution).
A mixture of 0 mM and 1 mM of KCl (I) 1% of KOH was added to a 30% solution of ethanol.
A mixture of 0 mM and 10 mM of KCl (J) KOH was added to a 30% solution of ethanol.
A mixture of 0 mM and 100 mM KCl. (K) 1% KOH in a 30% solution of ethanol
0 mM and 1000 mM of KCl mixed (L) KOH was added to a 30% solution of ethanol.
0 mM and 1500 mM KCl

Further, an aqueous solution of KCl (30 mM) and tartaric acid (0.3 mM) was used as a reference solution, and the following six kinds of sample liquids to be measured were used.

(A) Salt sample (KCl 300 mM, tartaric acid 0.3 mM aqueous solution) (b) Acid sample (KCl 30 mM, tartaric acid 3 mM aqueous solution) (c) MSG sample (KCl 30 mM, tartaric acid 0.3)
mM, MSG (10 mM aqueous solution of L-sodium hydrogen glutamate monohydrate)) (d) Quinine sample (KCl 30 mM, tartaric acid 0.1 mM)
3 mM, quinine (quinine hydrochloride dihydrate) 0.1 m
M aqueous solution) (e) Tannin sample (KCl 30 mM, tartaric acid 0.1 mM)
(F) An aqueous solution of 3 mM, tannic acid 0.05%) (f) Isoalpha acid sample (KCl 30 mM, tartaric acid 0.1%)
3 mM, aqueous solution of iso-alpha acid 1/10000)

Then, relative value measurement and CPA measurement were performed on each of the sample solutions. Here, the relative value measurement is a measurement performed according to the procedure shown in FIG.

That is, the molecular film sensor 15 and the reference electrode 12 are immersed in the reference solution to determine the voltage Va (i) of the molecular film sensor 15 with reference to the potential of the reference electrode 12. And the reference electrode 12 are immersed in the sample solution to determine the voltage Vb (i) of the molecular film, and the difference (relative value) between the voltages
After calculating V (i) = Vb (i) to Va (i), the process of taking the molecular film sensor 15 and the reference electrode 12 in and out of the cleaning liquid and performing cleaning is repeated three times, and the voltage V (1) to
V (3) is obtained, and its average value, standard deviation (error), and the ratio of the standard deviation to the average value are calculated.

The CPA measurement is a measurement performed according to the procedure shown in FIG. That is, the molecular film sensor 15 and the reference electrode 12 are immersed in the reference liquid to determine the voltage Va (i) of the molecular film sensor 15 with reference to the potential of the reference electrode 12. 12 is immersed in a sample solution for a certain period of time, then taken out and put into a washing solution for pre-washing, removing the weakly adsorbing substance on the surface of the molecular film to leave the strongly adsorbing substance. Reference electrode 12
Is again immersed in the reference solution to determine the voltage Va (i) 'of the molecular film, and the difference between the voltages (CPA value) V (i) = Va (i)'
After obtaining? V (i), the process of taking the molecular film sensor 15 and the reference electrode 12 into and out of the cleaning liquid and performing main cleaning is repeated three times to obtain the voltages V (1) to V (3). The average value, the standard deviation (error), and the ratio of the standard deviation to the average value are calculated.

However, when actually conducting the experiment, these two measurements are not separately performed, but the measurement of the reference solution → the measurement of the sample solution (calculation of the relative value) → the preliminary washing → the remeasurement of the reference solution ( The process of (CPA value calculation) → main cleaning is repeated three times, and the average, deviation, and ratio of the relative value and the CPA value are obtained.

Here, the cleaning of the molecular film sensor 15 is performed as follows.
This is performed by taking the molecular film sensor 15 into and out of the cleaning liquid a plurality of times, but as shown in FIG.
Cleaning can also be performed by applying ultrasonic vibration for a predetermined period of time in a state of soaking. In the pre-cleaning, the number of times of taking in and out of the cleaning liquid and the time of ultrasonic vibration are shortened as compared with the case of the main cleaning.

FIG. 4 shows the results of performing the above measurement on the tannin sample using each of the cleaning solutions A to L.

In FIG. 4, focusing on the ratio of the standard deviation (error) to the average value, the ratio of the error of the conventional cleaning liquid G is 14.89% in the relative value and 31.55% in the CPA value. On the other hand, in the cleaning liquids A to C, E, F, and H to L containing KCl other than the cleaning liquid D,
The relative value is greatly reduced to 6.91% at the maximum and the CPA value to 4.42% at the maximum.
It can be seen that the cleaning effect on tannin is much higher than the conventional cleaning liquid G containing no.

The cleaning solution D has a KCl concentration of 1 mM with respect to the cleaning solution B having a high cleaning effect.
, But the concentrations of ethanol and KOH are both low.

From this, KOH and KC were added to ethanol.
1), the concentration of ethanol is at least 25 percent and the concentration of KOH is at least 8 mM.
It is presumed necessary. If the concentrations of ethanol and KOH are too high, the molecular membrane may be eroded.
A range of M is considered appropriate.

On the other hand, the KCl concentration can be in a wide range (from 1 mM to
Although a high washing effect was obtained at 1500 mM), a more detailed examination revealed that washing solutions H to L having a concentration of ethanol of 30%, a KOH concentration of 10 mM, and a KCl concentration different from each other showed a relative effect. In the case of the value, the error ratio increases as the concentration of KCl increases, whereas in the case of the CPA value, the concentration of KCl
The error ratio is low up to 0 mM, but the concentration is 1500 mM.
, The ratio of error slightly increases.

It is also known that even if KCl is at a high concentration, there is little possibility of corroding a molecular film like ethanol and KOH.

Therefore, under the condition that the concentration of ethanol is 30% and the concentration of KOH is 10 mM, it is considered that the concentration of KCl is desirably 1000 mM or less (for example, about 100 mM).

However, if the molecular film sensor 15 is immersed in the cleaning solution containing KCl and then immersed in the reference solution, the KC
The potential of the membrane changed by 1 returns to the normal potential when immersed in the reference solution, but the time required to return to the normal potential becomes longer depending on the concentration of KCl in the cleaning solution. It is safer not to use a high-concentration one because it may reduce the efficiency of the measurement.

FIGS. 5 to 9 show the results obtained when the conventional cleaning solution G was used and when the cleaning solutions H to L containing KCl were used.
7 is a graph showing CPA measurement results of various types of samples.

As is apparent from these measurement results, K
In the CPA measurement using the conventional cleaning solution G containing no Cl, the CPA value obtained when the tannin-containing sample solution was measured was higher than the CPA value obtained when the sample solution containing a substance other than tannin was measured. Although the level of the value greatly changes and the sensitivity to tannin is selectively obtained, the variation width ΔV with respect to the level difference is obtained.
Is very large, indicating that the reproducibility of the measurement is low.

On the other hand, each of the cleaning liquids H to L containing KCl
In the case where is used, the level of the CPA value when measuring the sample solution containing tannin is more greatly changed with respect to the level of the CPA value when measuring the sample solution containing a substance other than tannin, Higher selective sensitivity is obtained, and the variation width ΔV with respect to the level difference is the same as that of the conventional cleaning solution G containing no KCl.
Is significantly smaller than the case of using, indicating that the reproducibility of the measurement is much higher.

As described above, by using a washing liquid obtained by mixing a salt substance and an alkali substance with a diluting liquid of an organic solvent such as ethanol, a substance having strong adsorptivity such as tannin can be effectively removed from the molecular film. The measurement can be performed with high reproducibility.

The cleaning effect of the cleaning solution obtained by mixing the salt substance and the alkali substance with the dilute solution of the organic solvent such as ethanol is due to the synergistic action of the organic solvent, the alkali substance and the salt substance.

That is, for many adsorbed substances which are strongly hydrophobic and are adsorbed on the hydrophobic portion of the molecular membrane, the washing action by the hydrophobicity of the organic solvent is effective, and the negatively charged substance adsorbed on the molecular membrane is charged. As for the adsorbed substance, the coordination bond between the ammonium group and the bromide ion of the molecular membrane is dissociated by the alkali substance, and as a result, the adsorbed substance is removed together with the bromide ion. The adsorbed substance is removed by the displacement action,
Very effective cleaning can be performed even on an adsorbed substance that is difficult to separate easily.

In the above description, the molecular membrane sensor 15 made of TDA having a carbon chain length R of 12 among the quaternary ammonium salts is to be cleaned, but a substance such as tannin negatively charged is strong. What exhibits the adsorptivity is a molecular film composed of an amphipathic substance or a bitter substance having a positive polarity, and the substance constituting the molecular film includes the above-mentioned T film.
Among the quaternary ammonium salts other than DA, TOMA (trioctylmethylammonium chloride), DODMA
(Dioctadecyldimethylammonium bromide), T
MSA (trimethyl stearyl ammonium chloride)
Oleylamine and the like besides quaternary ammonium salts are also available. For a molecular membrane sensor using these substances, the above-mentioned cleaning solution can be expected to have a high cleaning effect.

In the above description, ethanol is used as the organic solvent, KCl is used as the salt substance, and KO is used as the alkaline substance.
Although H was used, it can be inferred from the above-described cleaning action that an organic solvent other than ethanol (eg, methanol), KCl
Even when a salt substance other than the above (for example, NaCl) or an alkaline substance other than KOH (for example, NaOH) is used, the same high cleaning effect as described above can be expected.

However, for each of these substances, it is necessary to consider the measurement target of the molecular film sensor. For example, when used for inspection of beverages and foods, it is necessary to avoid harmful substances, as described above, ethanol as an organic solvent,
It is safer to use KCl as the salt substance and KOH as the alkaline substance.

[0045]

As described above, the cleaning solution for a molecular film sensor of the present invention is prepared by mixing a salt substance and an alkali substance with a diluent of an organic solvent. A remarkably high cleaning effect is obtained for a substance exhibiting strong adsorptivity, and measurement can be performed with high reproducibility.

The washing solution in which the organic solvent is a diluted solution of ethanol having a concentration of 25 to 40%, in which potassium hydroxide is mixed at a concentration of 8 mM to 100 mM as an alkali substance and potassium chloride is mixed at a concentration of 1 mM to 1500 mM as a salt substance,
A safe and high cleaning effect can be obtained as a cleaning liquid for a molecular membrane sensor used for inspection of foods and the like.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a system used in an experiment.

FIG. 2 is a flowchart showing the procedure of the experiment.

FIG. 3 is a flowchart showing the procedure of the experiment.

FIG. 4 is a diagram showing experimental results.

FIG. 5 is a diagram showing experimental results.

FIG. 6 is a view showing experimental results.

FIG. 7 is a diagram showing experimental results.

FIG. 8 is a diagram showing experimental results.

FIG. 9 is a view showing experimental results.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Container 12 Reference electrode 15 Molecular film sensor 17 Molecular film 20 Voltage detector 21 A / D converter 22 Arithmetic unit 23 Output unit

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[Procedure amendment]

[Submission date] December 7, 1999 (1999.12.
7)

[Procedure amendment 1]

[Document name to be amended] Drawing

[Correction target item name] All figures

[Correction method] Change

[Correction contents]

FIG.

FIG. 2

FIG. 4

FIG. 3

FIG. 7

FIG. 9

FIG. 5

FIG. 6

FIG. 8

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G01N 27/38 301 G01N 27/30 351 27/416 27/46 M 341M (72) Inventor Yoshikazu Kobayashi Tokyo 5-10-27 Minami-Azabu, Minato-ku Anritsu Corporation (72) Inventor Katsushi Sato 5-10-27 Minami-Azabu, Minato-ku, Tokyo Anritsu Corporation F-term (reference) 4H003 BA12 DA12 DA20 DB01 EA19 EA21 ED02 ED28

Claims (2)

[Claims] 1. A molecular membrane sensor for cleaning a molecular membrane sensor having a molecular membrane of an amphipathic substance or a bitter substance, wherein a membrane potential changes according to a component in the liquid when immersed in the liquid. A cleaning liquid for a molecular membrane sensor, wherein a salt substance and an alkaline substance are mixed in a diluting liquid of an organic solvent. 2. The method according to claim 1, wherein the organic solvent is a 25 to 40 percent ethanol diluent, wherein potassium hydroxide is mixed with the alkaline substance at a concentration of 8 mM to 100 mM, and potassium chloride is mixed at a concentration of 1 mM to 1500 mM as the salt substance. The cleaning solution for a molecular membrane sensor according to claim 1, wherein: