KR101433228B1 - Method for analyzing inorganic ion concentration in sample without phosphate ion interference - Google Patents

Abstract

The present invention relates to a method for analyzing inorganic ion concentrations in a sample without interference of a phosphate ion. Provided is a method for determining concentrations in a chlorine ion or a sulfate ion by measuring the change amount of electrical conductivity according to the deposition of the chlorine ion or the sulfate ion without interference of a phosphate ion which exists in a sample by controlling a pH of a sample for soil or water quality analysis. The present invention has an effect of simply and quickly analyzing the water quality and the soil state in a field by using an inorganic ion analysis method and an inorganic ion analysis kit.

Description

[0001] The present invention relates to a method for analyzing the concentration of inorganic ions in a sample without interfering with phosphate ions,

The present invention relates to a method for analyzing the concentration of inorganic ions in a sample without interfering with phosphate ions, and more particularly, to a method for analyzing the concentration of inorganic ions in a sample, A method of analyzing the inorganic ion concentration without interfering with the phosphate ions in the sample including a step of measuring the electrical conductivity after the sample is added to the sample, and a step of drawing a standard curve representing the amount of change in the electrical conductivity according to the concentration of the inorganic ions And the solution containing the sample and the counter ion, the sample is put into the solution containing the counter ion and the electric conductivity of the solution is calculated, and then the amount of change in the electrical conductivity is calculated, and the concentration of the inorganic ion in the sample is substituted A method of measuring an inorganic ion concentration without interfering with a phosphate ion in a sample including a step of determining And a kit for analyzing the inorganic ion concentration without being disturbed by the phosphate ions in the sample.

Measuring the concentration of inorganic ions present in surface water, ground water or soil is an essential step in water quality analysis for drinking water, sewage, wastewater and river management or soil analysis for crop management.

In general, the measurement of inorganic ion concentration for water quality or soil analysis can be performed by using an inductively coupled plasma optical emission spectrometer, an atomic absorption spectrophotometer, liquid chromatography (Liquid Chromatography) The main method is to use instrumental analysis. This device analysis has the merit that it can be analyzed precisely, but it requires a complicated preprocessing process and takes a long analysis time, and only a skilled expert can use it in a limited space such as an analytical laboratory.

Recently, ion selective electrodes using ion selective membranes sensitive to certain chemical species have been developed. The method using ion selective electrode is easy to carry and requires little pretreatment. However, the analysis method using the ion selective electrode is a method in which when various ions coexist or a specific ion concentration is high, The selectivity of the ion selective membrane is lowered and a reliable analytical value can not be obtained. Furthermore, chemical species for which an ion-selective membrane has not been developed can not be analyzed by itself. For example, ion selective membranes sensitive to phosphoric acid, magnesium, and sulfate ions have not been developed and thus there is a problem that measurement of these ions is impossible.

In addition, a classical general analysis method using a titration method, a painting method, or a spectrophotometer should be equipped with a plurality of analytical instruments and instrumental instruments including a chemical balance, a stirrer, a heating device, a dryer, etc., It takes a long time and it is not suitable as an analytical method for field diagnosis.

The chloride ion and the sulfate ion form a precipitate in the presence of a silver ion or a barium ion, respectively, by the following reaction.

Ag ⁺ + Cl ^{- -} > AgCl (precipitation)

Ba ^{2 +} + SO ₄ ^{2 -} → BaSO ₄ (precipitation)

The precipitate generated by the reaction is filtered and dried, and the concentration of the counter ion is calculated from the weight of the precipitate. Alternatively, a small amount of potassium dichromate is added to the aqueous solution containing the chloride ion, and the ion concentration is analyzed by titration until discoloration into silver nitrate . This general method can be measured without expensive analytical equipment, but it is not suitable for on-site analysis because many analytical instruments and instrumental instruments are required.

On the other hand, in response to social demands and technological developments, there have been increasing cases of analyzing water quality and soil condition in the field and taking appropriate prescription or action. There is a growing demand for on-site diagnostics to measure the concentration of inorganic ions directly at water quality analysis sites and agricultural sites, to promptly determine the abnormality, and to make appropriate prescriptions and measures accordingly. For this kind of on-site diagnosis, it is necessary to develop new analytical methods that non-experts can use quickly and simply.

Therefore, various on-site diagnostic methods have been devised which can be quickly measured in the field, one of which is an electrochemical measuring device. Typically, a pH meter or an electrical conductivity meter can be used to measure the concentration of inorganic ions in the field. However, such a measuring apparatus can measure only the total amount of the ions represented by various chemical species present in the aqueous solution, and thus the concentration of specific ions can not be measured.

Korean Patent Laid-Open Publication No. 2003-0053256 discloses a method for controlling the chlorine ion concentration of an open circulating coolant system using an electric conductivity meter, and Korean Patent No. 0195594 discloses a method for measuring ion concentration Method " is disclosed. However, the method for analyzing the inorganic ion concentration in the sample without disturbing the phosphate ion by measuring the change in the electric conductivity as in the present invention has never been disclosed.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned needs, and it is an object of the present invention to provide a method and apparatus for separating an electrolyte solution containing a chloride ion or a sulfate ion causing a precipitation reaction with a counter- And it was confirmed that the amount of change of the electrical conductivity decreased by the precipitation reaction was proportional to the concentration of the ion causing the precipitation reaction. It was confirmed by the pH control of the sample or the reaction solution that the amount of the inorganic ion The present inventors have completed the present invention by developing a method capable of measuring the concentration.

In order to solve the above problems,

a) adjusting the pH of a sample containing inorganic ions to 9 or less;

b) adding the same amount of the pH-adjusted sample to a vessel containing a solution containing a counter ion capable of causing precipitation with inorganic ions and a vessel containing a solution containing no counter ion; And

and c) measuring and comparing the electrical conductivity between the solutions in the two vessels of step b), thereby analyzing the inorganic ion concentration without interfering with the phosphate ions in the sample.

In addition,

a) A sample containing inorganic ions and a sample containing inorganic ions in a container containing a solution containing a counter ion capable of causing precipitation and a solution containing a solution containing no counter ion, ; And

b) measuring the electrical conductivity between the solutions in the two vessels of step a) and comparing the electrical conductivities of the solutions in the two vessels in step a), without analyzing the phosphate ion in the sample.

In addition,

a) drawing a standard curve representing the amount of electrical conductivity change according to the concentration of inorganic ions;

b) measuring the electrical conductivity of the sample containing inorganic ions after adjusting the pH to 9 or less;

c) measuring the electrical conductivity of the solution containing the counterion capable of causing precipitation with inorganic ions;

d) measuring the electrical conductivity of the solution in the container after the pH-controlled sample of step b) is added to the container containing the solution containing the counter ions of step c); And

e) calculating the amount of change in electrical conductivity by the electrical conductivity value measured in step b), c) and d), and then substituting the electrical conductivity change amount into the standard curve of step a) to determine the concentration of the inorganic ion in the sample A method for measuring the concentration of inorganic ions without interfering with phosphate ions in the sample.

In addition,

a) drawing a standard curve representing the amount of electrical conductivity change according to the concentration of inorganic ions;

b) measuring electrical conductivity of the sample containing inorganic ions;

c) measuring the electrical conductivity of the solution containing the counterion capable of causing precipitation with inorganic ions;

d) introducing the sample of step b) into a container containing the solution containing the counter ions of step c), adjusting the pH to 9 or less, and then measuring the electrical conductivity of the solution in the container; And

e) calculating the amount of change in electrical conductivity by the electrical conductivity value measured in step b), c) and d), and then substituting the electrical conductivity change amount into the standard curve of step a) to determine the concentration of the inorganic ion in the sample A method for measuring the concentration of inorganic ions without interfering with phosphate ions in the sample.

The present invention also relates to a buffer solution containing a counterion capable of causing precipitation with inorganic ions and having a pH of 9 or less;

A paper showing a standard curve showing the amount of change in electric conductivity according to the concentration of each inorganic ion, and a paper showing the calculation method of the electric conductivity change; And

A kit for analyzing an inorganic ion concentration without interfering with phosphate ions in a sample including an electric conductivity meter.

According to the present invention, by adjusting the pH of a sample for soil analysis or a sample for water quality analysis, or by adjusting the pH of the reaction solution, the change in electrical conductivity due to the precipitation of chlorine ions or sulfate ions And the concentration of chlorine ions or sulfate ions can be determined. The inorganic ion analysis method of the present invention can easily and quickly analyze water quality and soil condition in the field.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a graph showing changes in electrical conductivity of a solution containing phosphate ions and a solution containing no phosphate ions according to the chloride ion concentration. FIG. The electrical conductivity change was calculated by measuring the electrical conductivity before and after silver ion addition. Cl + No_P_DW: The change of electrical conductivity according to the concentration of chloride ion in a solution without phosphate ion, Cl + P (NA) _DW: The change of electrical conductivity according to chloride ion concentration in solution containing phosphate ion.
FIG. 2 is a graph showing the amount of change in electric conductivity according to sulfate ion concentration in a solution in which phosphoric acid ions are present and in a solution in which no phosphate ions exist. FIG. The electrical conductivity change was calculated by measuring the electrical conductivity before and after the addition of barium ions. SO4 + No_P_DW: Change of electrical conductivity according to sulfate ion concentration in solution without phosphate ion, SO4 + P (NA) _DW: Electrical conductivity change according to sulfate ion concentration in solution containing phosphate ion.
FIG. 3 is a graph showing the presence of phosphate ions according to pH. FIG.
FIG. 4 is a graph showing changes in the electrical conductivity of a solution containing phosphate ions and a solution containing no phosphate ions, the pH of which is adjusted to 4 or less, according to the chloride ion concentration. The electrical conductivity change was calculated by measuring the electrical conductivity before and after silver ion addition. Cl + P (NA) _AA_10: Concentration change of chloride ion concentration in solution (pH 4 or less) in which phosphate ion is not present. The electrical conductivity change according to the.
FIG. 5 is a graph showing the amount of change in electrical conductivity according to sulfate ion concentration in a solution in which phosphoric acid ions are present and in a solution in which pH is adjusted to 4 or less. The electrical conductivity change was calculated by measuring the electrical conductivity before and after the addition of barium ions. SO4 + No_P_AA_10: Change in electrical conductivity according to sulfate ion concentration in a solution (pH 4 or less) in which phosphate ion is not present. SO4 + P (NA) _AA_10: The concentration of sulfate ion in a solution The electrical conductivity change according to the.

In order to achieve the object of the present invention,

a) adjusting the pH of a sample containing inorganic ions to 9 or less;

b) adding the same amount of the pH-adjusted sample to a vessel containing a solution containing a counter ion capable of causing precipitation with inorganic ions and a vessel containing a solution containing no counter ion; And

and c) measuring and comparing the electrical conductivity between the solutions in the two vessels of step b), thereby analyzing the inorganic ion concentration without interfering with the phosphate ions in the sample.

In the present invention, the sample containing the inorganic ions in step a) has a pH of 9 or less, preferably pH 1 to 9, more preferably pH 1 to 7, more preferably pH 1 to 5, most preferably Can be adjusted to a pH of 1 to 3, but is not limited thereto. The pH may be adjusted by treating the acid, preferably by treatment with acetic acid, but is not limited thereto as long as it does not interfere with the precipitation reaction between the inorganic ion and the counter ion and can lower the pH stably.

In the present invention, the solution containing the counterion capable of causing the precipitation of the inorganic ion in the step b) and the solution not containing the counterion ion is preferably pH 9 or less, preferably pH 1 to 9, more preferably pH 1 to 7, more preferably pH 1 to 5, most preferably pH 1 to 3, but is not limited thereto. The pH may be adjusted by treating the acid, preferably by treatment with acetic acid, but not limited thereto, as long as it does not interfere with the precipitation reaction between the inorganic ion and the counter ion and can lower the pH stably.

Generally, the silver ion (Ag ⁺ ) reacts with the chloride ion (Cl ^- ) and precipitates in the form of AgCl. When the phosphate ion is present in the reaction solution, the silver ion can also bind to the phosphate ion. The phosphate ion that causes the precipitation reaction with silver ion is PO4 ^{3 -} type ion, and HPO ₄ ^2- , H ₂ PO ₄ ^- and H ₃ PO ₄ It does not cause a precipitation reaction with ions of the form. PO4 ^{3 -} form phosphate is present in the alkaline state, and at pH 9 or below, it is not PO4 ^{3 -} , but HPO ₄ ^{2 -} , H ₂ PO ₄ ^- and H ₃ PO ₄ Form ions, and therefore, do not cause a precipitation reaction with silver ions. Accordingly, in the present invention, in order to minimize the change in electric conductivity by the phosphate ion, the pH is preferably 9 or less, preferably 1 to 9, more preferably 1 to 7, more preferably 1 to 5, most preferably It is necessary to adjust the pH to 1-3.

In the present invention, the electrical conductivity of step c) may be measured using any method and apparatus known in the art.

Electrical conductivity refers to the degree of electrical conductivity and is sometimes referred to as Conductivity or Specific Conductivity. The electrical conductivity is measured by flowing a current through two special electrode plates. The electrical conductivity is closely related to the amount of TDS (Total Dissolved Solids) contained in the solution. The more electrically charged ions are in the solution, the greater the electrical conductivity of the solution. In other words, as the ion concentration in the solution increases, the electrical conductivity of the solution increases, so that the electrical conductivity is an indicator of the ion concentration in the solution. However, since the electrical conductivity of a solution varies depending on the type of ion such as the amount of the ion, the amount of the ion, and the size of the ion, the electrical conductivity measured in the solution in which various ions exist is referred to as a specific ion concentration It can not be said. Therefore, the present inventors measured the concentration of inorganic ions to cause the precipitation reaction by adding a counter ion into the solution and measuring the amount of change of the electric conductivity according to the addition, so that the concentration of the specific ion can be more accurately measured I have developed a way to do that.

The method for analyzing the inorganic ion concentration of the present invention will be described in detail with reference to an example in which the inorganic ion is chlorine. Specifically, a sample containing chlorine ions is adjusted to pH 9 or less and then a silver ion- And then measuring the electrical conductivity of the solution. Of the two reaction solutions, a reaction solution containing silver ions will be measured in such a manner that chloride ion is precipitated by silver ions and electric conductivity is low. On the other hand, the reaction solution containing no silver ions will have a relatively high electric conductivity by chlorine ions. In addition, the higher the concentration of chlorine ions in the sample, the greater the difference in electrical conductivity between the two reaction solutions. The lower the concentration of chlorine ions, the smaller the difference in electrical conductivity between reaction liquids, can confirm.

In addition,

a) A sample containing inorganic ions and a sample containing inorganic ions in a container containing a solution containing a counter ion capable of causing precipitation and a solution containing a solution containing no counter ion, ; And

b) measuring the electrical conductivity between the solutions in the two vessels of step a) and comparing the electrical conductivities of the solutions in the two vessels in step a), without analyzing the phosphate ion in the sample.

In the present invention, the reaction solution in which a solution containing a counter ion capable of causing precipitation of inorganic ions in the step a) and a sample containing an inorganic ion are added to a solution containing no counter ion, But is not limited to, a pH of 1 to 9, more preferably a pH of 1 to 7, more preferably a pH of 1 to 5, and most preferably a pH of 1 to 3. The pH may be adjusted by treating the acid, preferably by treatment with acetic acid, but not limited thereto, as long as it does not interfere with the precipitation reaction between the inorganic ion and the counter ion and can lower the pH stably.

In the present invention, the electrical conductivity of step b) may be measured using any method and apparatus known in the art.

In one embodiment of the invention, the sample may be, but is not limited to, soil, surface water or ground water.

The soil sample can be prepared by adding an appropriate solvent or buffer to the soil sample collected from the soil and then preparing the ion by elution. Preferably, the soil sample can be prepared by adding water to the soil sample and then eluting the water ion. Preferably, the soil sample can be prepared by adding distilled water to the soil sample, followed by dissolving the water-soluble inorganic ion, but the present invention is not limited thereto.

The surface water refers to the water on the surface of the earth and usually refers to the water of a river or lake, and the ground water refers to water that flows through the gaps between rocks or underground strata. The surface water or ground water samples can be used for analysis by directly using the sampled sample, diluted in distilled water or buffer, but not limited thereto.

In one embodiment of the present invention, the inorganic ion may be a chloride ion or a sulfate ion, but is not limited thereto. The counter-ion capable of causing precipitation with the inorganic ion is a silver ion when the inorganic ion is chloride ion, and may be a barium ion when the inorganic ion is sulfate ion, but is not limited thereto. The inorganic ion present in the sample may be a silver ion or a barium ion, but is not limited thereto. The counter ion capable of causing precipitation with the inorganic ion may be a chloride ion when the inorganic ion is a silver ion and may be a sulfate ion when the inorganic ion is a barium ion, but the present invention is not limited thereto.

In addition,

a) drawing a standard curve representing the amount of electrical conductivity change according to the concentration of inorganic ions;

b) measuring the electrical conductivity of the sample containing inorganic ions after adjusting the pH to 9 or less;

c) measuring the electrical conductivity of the solution containing the counterion capable of causing precipitation with inorganic ions;

d) measuring the electrical conductivity of the solution in the container after the pH-controlled sample of step b) is added to the container containing the solution containing the counter ions of step c); And

e) calculating the amount of change in electrical conductivity by the electrical conductivity value measured in step b), c) and d), and then substituting the electrical conductivity change amount into the standard curve of step a) to determine the concentration of the inorganic ion in the sample A method for measuring the concentration of inorganic ions without interfering with phosphate ions in the sample.

In the present invention, the electric conductivity standard curve of the step a) can be obtained by the method described in the following description and the electric conductivity change amount calculation method. The description of the pH adjustment of the sample in the step b) is as described above, and the description of the electrical conductivity measurement of the steps b), c) and d) is also as described above.

The method for measuring the inorganic ion concentration of the present invention will be described specifically with reference to the case where the inorganic ion is chlorine. For example, a standard solution for each concentration in which chlorine ions are present at 0, 200, 400, 600, 800 and 1000 ppm is prepared, The electrical conductivity (EC_A) of the standard solution and the electrical conductivity (EC_B) after adding the solution containing silver ions to each standard solution are measured. Also, the electrical conductivity (EC_C) of the same solution as the solution containing the added silver ions is measured. Calculate the change in electrical conductivity using each measured value and create a standard curve. The electric conductivity change amount (dEC) calculation method is as follows.

dEC = [EC_A * (amount of total reaction solution before addition of even ion / amount of total reaction solution after addition of even ion) + EC_C * (amount of added equivalent ion solution / amount of total reaction solution after addition of even ion) EC_B

When the pH of the standard solution is adjusted to 9 or less even when the phosphate ion is added to the chloride ion standard solution, the same standard curve as the standard curve prepared by the above method can be obtained.

Subsequently, the sample in which chlorine ions are present is adjusted to pH 9 or less, and the electrical conductivity (EC_A) of the sample is measured. Also, the electrical conductivity (EC_C) of a solution containing silver ions to be added to cause a precipitation reaction is measured. Then, a solution containing the silver ion is added to the sample having the pH adjusted, and the electrical conductivity (EC_B) is measured. After calculating the electrical conductivity change using the three electrical conductivity values measured above, substituting the standard conductivity curve into the standard curve obtained above, it is possible to relatively accurately measure the chloride ion concentration in the sample without interfering with the phosphate ion.

In addition,

a) drawing a standard curve representing the amount of electrical conductivity change according to the concentration of inorganic ions;

b) measuring electrical conductivity of the sample containing inorganic ions;

c) measuring the electrical conductivity of the solution containing the counterion capable of causing precipitation with inorganic ions;

d) introducing the sample of step b) into a container containing the solution containing the counter ions of step c), adjusting the pH to 9 or less, and then measuring the electrical conductivity of the solution in the container; And

e) calculating the amount of change in electrical conductivity by the electrical conductivity value measured in step b), c) and d), and then substituting the electrical conductivity change amount into the standard curve of step a) to determine the concentration of the inorganic ion in the sample A method for measuring the concentration of inorganic ions without interfering with phosphate ions in the sample.

In the present invention, the electric conductivity standard curve of the step a) can be obtained by the method described in the above description and the electric conductivity change amount calculation method. The description of the pH control of the solution in step d) is as described above, and the description of the measurement of the electrical conductivity of steps b), c) and d) is also as described above.

The method for measuring the inorganic ion concentration of the present invention is the same as that described above, for example, when the inorganic ion is chlorine as an example. Specifically, the electric conductivity measurement method, the electric conductivity variation calculation method, and the electric conductivity variation standard curve creation method are the same as described above.

Next, in order to confirm the chloride ion concentration in the sample to be measured, the electric conductivity (EC_A) of the sample in which the chloride ion exists is measured, and the electric conductivity (EC_C) of the solution containing the silver ion is measured. The sample is added to a solution containing the silver ion and allowed to react. In this case, when phosphate ions are present in the sample, an error occurs in the amount of change in the electrical conductivity. Therefore, the reaction solution is adjusted to pH 9 or less so that the silver ion in the reaction solution to which the sample is added can not react with the phosphate ion . After the electrical conductivity (EC_B) of the reaction solution is measured, the electrical conductivity change amount is calculated using the three electrical conductivity values. When the electrical conductivity change amount is substituted into the standard curve obtained above, the chlorine ion concentration in the sample can be measured relatively accurately without interfering with the phosphate ion.

In one embodiment of the invention, the sample may be, but is not limited to, soil, surface water or ground water.

In one embodiment of the present invention, the inorganic ion may be a chloride ion or a sulfate ion, but is not limited thereto. The counter-ion capable of causing precipitation with the inorganic ion is a silver ion when the inorganic ion is chloride ion, and may be a barium ion when the inorganic ion is sulfate ion, but is not limited thereto. The inorganic ion present in the sample may be a silver ion or a barium ion, but is not limited thereto. The counter ion capable of causing precipitation with the inorganic ion may be a chloride ion when the inorganic ion is a silver ion and may be a sulfate ion when the inorganic ion is a barium ion, but the present invention is not limited thereto.

In addition,

A buffer solution containing a counterion capable of causing precipitation with inorganic ions and having a pH of 9 or less;

A paper showing a standard curve showing the amount of change in electric conductivity according to the concentration of each inorganic ion, and a paper showing the calculation method of the electric conductivity change; And

A kit for analyzing an inorganic ion concentration without interfering with phosphate ions in a sample including an electric conductivity meter.

In one embodiment of the present invention, the kit may further comprise a buffer capable of eluting inorganic ions in the sample. The buffer solution for eluting the inorganic ions is preferably pH 9 or less, more preferably pH 1 to 9, more preferably pH 1 to 7, even more preferably pH 1 to 5, most preferably pH 1 to 3 , But is not limited thereto. In addition, the kit may further comprise a buffer solution, a sample or a buffer, and a pH indicator such as a pH indicator or a litmus paper, which can measure the pH of the sample reaction solution.

The calculation method of the electrical conductivity change amount in the kit of the present invention is as follows.

dEC = [EC_A * (amount of total reaction solution before addition of even ion / amount of total reaction solution after addition of even ion) + EC_C * (amount of added equivalent ion solution / amount of total reaction solution after addition of even ion) EC_B

(EC_A: electrical conductivity of the reaction solution before addition of even-numbered ions, EC_B: electrical conductivity of the reaction solution after addition of even ions, EC_C: electrical conductivity of the added equivalent ion solution)

In the kit of the present invention, the electrical conductivity meter may be any electrical conductivity meter known in the art, preferably a portable electrical conductivity meter, but it may be a device capable of measuring the electrical conductivity of the sample and the reaction solution .

Hereinafter, the present invention will be described in detail by way of examples. However, the following examples are illustrative of the present invention, and the present invention is not limited to the following examples.

Example  1. Chloride ion analysis

200, 400, 600, 800 and 1000 ppm of final chloride ion concentration was prepared using NaCl, and 200 ㎕ of each standard solution of chloride ion concentration was added to two sets of test tubes. Two sets of test tubes containing 200 μl of the standard solution were added with 2,800 μl of distilled water and the electrical conductivity of each of the test tubes in one set of two sets of test tubes was measured (EC_A). To the other set of test tubes 200 μl of 35 mM AgNO ₃ was added and after 10 minutes the electrical conductivity of each in vitro solution was determined (EC_B). The electrical conductivity of 35 mM AgNO ₃ was measured (EC_C). The measured electrical conductivity values were used to calculate the electrical conductivity change. The electric conductivity change amount (dEC) calculation method is as follows.

dEC = {[EC_A * (amount of total reaction solution before adding even ion / amount of total reaction solution after addition of even ion) + EC_C * (amount of added equivalent ion solution / amount of total reaction solution after addition of even ion) - EC_B}

That is, in this embodiment, the calculation formula of the electric conductivity change for chlorine ion is {[EC_A * (3,000 / 3,200) + EC_C * (200 / 3,200)] - EC_B}.

Since soil and surface water often contain a large amount of phosphoric acid, experiments were conducted to confirm whether the method for measuring chloride ion concentration of the present invention is affected by phosphoric acid.

The standard solutions (0, 200, 400, 600, 800 and 1000 ppm) of chloride ion concentration containing phosphate ions with PO ₄ ^{3 -} concentration of 200 ppm were prepared using NaCl and Na ₂ HPO ₄ , 200 μl of each standard solution of chlorine ion concentration containing 200 ppm of PO ₄ ^{3 -} was added. Two sets of test tubes containing standard solutions of chloride ion concentration containing phosphate ions were added to 2,800 μl of distilled water, respectively, and the electrical conductivity of each test tube solution in one set of two sets of test tubes was measured (EC_A). To the other set of test tubes 200 μl of 35 mM AgNO ₃ was added and after 10 minutes the electrical conductivity of each in vitro solution was determined (EC_B). The electrical conductivity of 35 mM AgNO ₃ was measured (EC_C). The measured electrical conductivity values were used to calculate the electrical conductivity change.

As a result of the calculation of the standard curve based on the calculated change in the electrical conductivity, it was confirmed that the change in the electrical conductivity before and after the silver ion addition was proportional to the concentration of the chloride ion regardless of the presence or absence of the phosphate ion. However, it was confirmed that the relation of the standard curve varies depending on the presence or absence of the phosphate ion (Fig. 1). On the other hand, it was confirmed that the same standard curve appears regardless of the presence or absence of nitrate ion or potassium ion in the standard solution of chloride ion concentration containing nitrate ion or potassium ion (data not shown).

Example  2. Sulfate ion analysis

200, 400, 600, 800 and 1000 ppm of final sulfate ion concentrations were prepared by using Na ₂ SO ₄ and 200 μl of each standard solution for sulfate ion concentration was added to two sets of test tubes. Two sets of test tubes containing 200 μl of the standard solution were added with 2,800 μl of distilled water and the electrical conductivity of each of the test tubes in one set of two sets of test tubes was measured (EC_A). To the other set of test tubes 200 μl of 20 mM BaCl ₂ was added and after 10 minutes the electrical conductivity of each in vitro solution was determined (EC_B). The electrical conductivity of 20 mM BaCl ₂ was measured (EC_C). The measured electrical conductivity values were used to calculate the electrical conductivity change. The electric conductivity change calculation method is the same as that of the chlorine ion.

Since soil and surface water often contain a large amount of phosphoric acid, experiments were conducted to confirm whether the method for measuring sulfate ion concentration of the present invention is affected by phosphoric acid.

The standard solutions (0, 200, 400, 600, 800 and 1000 ppm) of sulfate ion concentration containing phosphate ions with PO ₄ ^{3 -} concentration of 200 ppm were prepared using Na ₂ SO ₄ and Na ₂ HPO ₄ . test tubes of PO ₄ ³ 200 ppm in the set ^- a sulfate ion concentration by the standard solution containing a were each added 200 ㎕. Two sets of test tubes containing standard solutions of sulfate ion concentration containing phosphate ions were added to each of 2,800 μl of distilled water, and the electrical conductivity of each solution in each test tube of two sets of test tubes was measured (EC_A). To the other set of test tubes 200 μl of 20 mM BaCl ₂ was added and after 10 minutes the electrical conductivity of each in vitro solution was determined (EC_B). The electrical conductivity of 20 mM BaCl ₂ was measured (EC_C). The measured electrical conductivity values were used to calculate the electrical conductivity change.

As a result of the calculation of the standard curve based on the calculated change in the electric conductivity, it was confirmed that the change in the electric conductivity before and after the addition of barium ion is proportional to the concentration of sulfate ion regardless of the presence or absence of the phosphate ion. However, it was confirmed that the relation of the standard curve varies depending on the presence of the phosphate ion (FIG. 2). On the other hand, the same standard curve was obtained regardless of the presence or absence of nitrate ion or potassium ion in the standard solution of sulfate ion concentration containing nitrate ion or potassium ion (data not shown).

The change in the electrical conductivity represented by the phosphate ion is due to the precipitation reaction of the phosphate ion with the silver ion or barium ion. Therefore, the pH of the reaction solution was adjusted to suppress the interference of the phosphate ion during the precipitation reaction. Phosphate ions are present in different forms depending on the pH, and are present as forms (HPO ₄ ^2- , H ₂ PO ₄ ^- and H ₃ PO ₄ ) in which the precipitation reaction with silver ions or barium ions is impossible at pH 9 or below 3). When the reaction solution was adjusted to pH 9 or less, it was determined that specific precipitation of chloride ion and silver ion and specific precipitation of sulfate ion and barium ion could be caused.

Example  3. pH  Analysis of Chloride in Control Solution

200, 400, 600, 800 and 1000 ppm of final chloride ion concentration was prepared using NaCl, and 200 ㎕ of each standard solution of chloride ion concentration was added to two sets of test tubes. The electroconductivity of each solution in each test tube of two sets of test tubes was measured by adding 2,800 μl of 0.15% acetic acid solution (preparation of a reaction solution below pH 4) to two sets of test tubes containing 200 μl of the standard solution (EC_A ). To the other set of test tubes 200 μl of 35 mM AgNO ₃ was added and after 10 minutes the electrical conductivity of each in vitro solution was determined (EC_B). The electrical conductivity of 35 mM AgNO ₃ was measured (EC_C). The measured electrical conductivity values were used to calculate the electrical conductivity change. The electric conductivity change amount calculation method is the same as described above.

Next, an experiment was conducted to confirm whether the method for measuring the chloride ion concentration of the present invention was affected by phosphoric acid in a reaction solution whose pH was adjusted to 4 or less.

The standard solutions (0, 200, 400, 600, 800 and 1000 ppm) of chloride ion concentration containing phosphate ions with PO ₄ ^{3 -} concentration of 200 ppm were prepared using NaCl and Na ₂ HPO ₄ , 200 μl of each standard solution of chlorine ion concentration containing 200 ppm of PO ₄ ^{3 -} was added. To each of the two sets of test tubes containing the phosphate ion-containing standard solution of chloride ion concentration, 2,800 μl of 0.15% acetic acid solution was added (to prepare a reaction solution having a pH of 4 or less), and one set of each test tube solution Was measured (EC_A). To the other set of test tubes 200 μl of 35 mM AgNO ₃ was added and after 10 minutes the electrical conductivity of each in vitro solution was determined (EC_B). The electrical conductivity of 35 mM AgNO ₃ was measured (EC_C). The measured electrical conductivity values were used to calculate the electrical conductivity change.

As a result of the calculation of the standard curve based on the calculated change in electrical conductivity, it was found that when the pH was adjusted with acetic acid, the change in the electrical conductivity before and after the addition of silver ions was proportional to the chloride ion concentration, (FIG. 4).

Example  4. pH  Analysis of sulfate ion in regulating solution

200, 400, 600, 800 and 1000 ppm of final sulfate ion concentrations were prepared using Na ₂ SO ₄ and 200 μl of each standard solution of chloride ion concentration was added to two sets of test tubes. The electroconductivity of each solution in each test tube of two sets of test tubes was measured by adding 2,800 μl of 0.15% acetic acid solution (preparation of a reaction solution below pH 4) to two sets of test tubes containing 200 μl of the standard solution (EC_A ). To the other set of test tubes 200 μl of 20 mM BaCl ₂ was added and after 10 minutes the electrical conductivity of each in vitro solution was determined (EC_B). The electrical conductivity of 20 mM BaCl ₂ was measured (EC_C). The measured electrical conductivity values were used to calculate the electrical conductivity change. The electric conductivity change amount calculation method is the same as described above.

Then, an experiment was conducted to confirm whether the method for measuring the sulfate ion concentration of the present invention is affected by phosphoric acid in a reaction solution whose pH is adjusted to 4 or less.

The standard solutions (0, 200, 400, 600, 800 and 1000 ppm) of sulfate ion concentration containing phosphate ions with PO ₄ ^{3 -} concentration of 200 ppm were prepared using Na ₂ SO ₄ and Na ₂ HPO ₄ . test tubes of PO ₄ ³ 200 ppm in the set ^- a sulfate ion concentration by the standard solution containing a were each added 200 ㎕. Two sets of test tubes containing the standard solution of the sulfate ion concentration containing phosphate ions were added to 2,800 μl of 0.15% acetic acid solution, and the electrical conductivity of each test tube solution in one set of two sets of test tubes was measured (EC_A ). To the other set of test tubes 200 μl of 20 mM BaCl ₂ was added and after 10 minutes the electrical conductivity of each in vitro solution was determined (EC_B). The electrical conductivity of 35 mM AgNO ₃ was measured (EC_C). The measured electrical conductivity values were used to calculate the electrical conductivity change.

As a result of the calculation of the standard curve based on the calculated change in the electric conductivity, the change in the electrical conductivity before and after the addition of barium ion was proportional to the concentration of sulfate ion regardless of the presence or absence of phosphate ion. Also, it was confirmed that the respective standard curves coincide with each other (FIG. 5).

Further, based on the standard curves of the electrical conductivity change amount and the electrical conductivity change amount according to the chlorine ion concentration and the electrical conductivity change amount according to the chloride ion concentration presented in the present invention, the change in the electrical conductivity of the soil analysis sample or the water quality analysis sample is measured, The concentration of chloride ion and the concentration of sulfate ion can be confirmed.

Claims (12)

a) adjusting the pH of a sample containing inorganic ions to 9 or less;
b) adding the same amount of the pH-adjusted sample to a vessel containing a solution containing a counter ion capable of causing precipitation with inorganic ions and a vessel containing a solution containing no counter ion; And
and c) measuring and comparing the electrical conductivity between the solutions in the two vessels of step b), thereby analyzing the inorganic ion concentration without disturbing the phosphate ions in the sample. a) A sample containing inorganic ions and a sample containing inorganic ions in a container containing a solution containing a counter ion capable of causing precipitation and a solution containing a solution containing no counter ion, ; And
and b) measuring and comparing the electrical conductivity between the solutions in the two vessels of step a), thereby analyzing the inorganic ion concentration without interfering with the phosphate ions in the sample. 3. The method according to claim 1 or 2, wherein the sample is soil, surface water or ground water. 3. A method for analyzing inorganic ion concentration without interfering with phosphate ions in a sample. The method according to claim 1 or 2, wherein the inorganic ion is a chlorine ion or a sulfate ion. A method for analyzing an inorganic ion concentration without interfering with a phosphate ion in a sample. The method according to claim 1 or 2, wherein the counter ion capable of causing precipitation with the inorganic ion is a silver ion when the inorganic ion is chloride ion and a barium ion when the inorganic ion is sulfate ion. A method of analyzing the inorganic ion concentration without interfering with the phosphate ions in the sample. a) drawing a standard curve representing the amount of electrical conductivity change according to the concentration of inorganic ions;
b) measuring the electrical conductivity of the sample containing inorganic ions after adjusting the pH to 9 or less;
c) measuring the electrical conductivity of the solution containing the counterion capable of causing precipitation with inorganic ions;
d) measuring the electrical conductivity of the solution in the container after the pH-controlled sample of step b) is added to the container containing the solution containing the counter ions of step c); And
e) calculating the amount of change in electrical conductivity by the electrical conductivity value measured in step b), c) and d), and then substituting the electrical conductivity change amount into the standard curve of step a) to determine the concentration of the inorganic ion in the sample A method for measuring the concentration of inorganic ions without interfering with phosphate ions in a sample. a) drawing a standard curve representing the amount of electrical conductivity change according to the concentration of inorganic ions;
b) measuring electrical conductivity of the sample containing inorganic ions;
c) measuring the electrical conductivity of the solution containing the counterion capable of causing precipitation with inorganic ions;
d) introducing the sample of step b) into a container containing the solution containing the counter ions of step c), adjusting the pH to 9 or less, and then measuring the electrical conductivity of the solution in the container; And
e) calculating the amount of change in electrical conductivity by the electrical conductivity value measured in step b), c) and d), and then substituting the electrical conductivity change amount into the standard curve of step a) to determine the concentration of the inorganic ion in the sample A method for measuring the concentration of inorganic ions without interfering with phosphate ions in a sample. 8. The method according to claim 6 or 7, wherein the sample is a soil, surface water or groundwater, and the inorganic ion concentration is measured without interfering with phosphate ions in the sample. The method according to claim 6 or 7, wherein the inorganic ion is a chlorine ion or a sulfate ion, wherein the inorganic ion concentration is measured without interfering with phosphate ions in the sample. The method according to claim 6 or 7, wherein the counter ion is a silver ion when the inorganic ion is chlorine ion and a barium ion when the inorganic ion is sulfate ion. A method for measuring the concentration of inorganic ions. A buffer solution containing a counterion capable of causing precipitation with inorganic ions and having a pH of 9 or less;
A paper showing a standard curve showing the amount of change in electric conductivity according to the concentration of each inorganic ion, and a paper showing the calculation method of the electric conductivity change; And
A kit for analyzing the concentration of inorganic ions without interfering with phosphate ions in a sample containing an electrical conductivity meter. The kit according to claim 11, further comprising a buffer capable of eluting inorganic ions in the sample, the inorganic ion concentration being analyzed without interference of phosphate ions in the sample.

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