WO2012014257A1

WO2012014257A1 - Total phosphorous quantity determination method

Info

Publication number: WO2012014257A1
Application number: PCT/JP2010/004834
Authority: WO
Inventors: 石井宏
Original assignee: 三浦工業株式会社
Priority date: 2010-07-30
Filing date: 2010-07-30
Publication date: 2012-02-02
Also published as: WO2012014346A1

Abstract

The disclosed method determines the total phosphorous quantity in test water safely and in a short time period by breaking down phosphorous compounds included in test water and converting to phosphate ions, and then determining the quantity of phosphate ions in the test water. In the method, first sulfuric acid and alkali metal salts of peroxodisulfuric acid are added to test water, and the mixture is heated for a prescribed time period at a temperature from 65˚C to boiling temperature. An aqueous solution is added to the test water, said aqueous solution containing at least one hydroxyl group-containing compound selected from the hydroxyl group-containing compound group consisting of hydroxyl carboxylic acids and alditol, a vanadium compound having a vanadium valence of 3-5, a non-reducing oligosaccharide capable of generating a 5 carbon aldose, a 6 carbon aldose or a 6 carbon ketose by means of decomposition, 7-molybdic acid 6-ammonium, and an antimony compound wherein the antimony valence is 3, and after heating the test water to at least 65˚C for a prescribed time period, the light absorbance of the test water for an arbitrary wavelength occurring in the range of 600-950nm is measured.

Description

Determination of total phosphorus

The present invention relates to a method for quantifying total phosphorus, and in particular, quantifies the total phosphorus in test water by decomposing the phosphorus compound contained in the test water and converting it into phosphate ions and then quantifying the phosphate ions in the test water. Regarding the method.

Phosphorus is one of the causative substances related to eutrophication such as ocean water, lake water, river water, and groundwater, so there are regulations on the discharge of factory wastewater. Quantification of phosphate ions is required before discharge. Here, factory effluents not only contain phosphorus as phosphate ions, but may also contain phosphorus elements as various phosphorus compounds. Phosphorus compounds are naturally decomposed after being discharged into the environment, which is the source of phosphorus. It becomes. For this reason, factory wastewater and the like may be required to determine not only phosphate ions but also the total amount of phosphate ions including phosphate ions that can be generated from phosphorus compounds, so-called total phosphorus.

As an official quantification method of total phosphorus contained in water, molybdenum blue (ascorbic acid reduction) absorptiometry described in Non-Patent Document 1 is known. In this quantitative method, a heteropoly compound formed by reacting phosphate ions contained in water with hexaammonium heptamolybdate and potassium antimonyl tartrate (bis ((+)-tartrate) diantimony (III) dipotassium) is produced. Phosphate ions are quantified by measuring the absorbance of test water colored by molybdenum blue produced by reduction with L (+)-ascorbic acid.

In the determination of total phosphorus by molybdenum blue (ascorbic acid reduction) absorptiometry, first, a predetermined amount of test water is collected, and pretreatment is performed to decompose the phosphorus compounds contained in the test water and convert them into phosphate ions. . In this pretreatment, after adding a potassium peroxodisulfate solution, which is an oxidizing agent of a phosphorus compound, to the test water, the test water is treated in a high-pressure steam sterilizer set at 120 ° C. for 30 minutes to oxidize the phosphorus compound. Decomposes and converts to phosphate ion. Next, a predetermined amount of ammonium molybdate-ascorbic acid mixed solution is added to the pretreated test water, shaken, and allowed to stand at 20 to 40 ° C. for about 15 minutes. Then, the absorbance at a wavelength of about 880 nm is measured for this solution, and the phosphate ion concentration (mgPO ₄ ³⁻ / L) of test water is calculated based on a calibration curve prepared in advance from the measured value.

Since the pretreatment of the test water in such a method for determining total phosphorus requires the use of a high-pressure steam sterilizer, that is, a pressure-resistant container, the operation becomes complicated and special safety is also required. In addition, potassium peroxodisulfate used as an oxidizing agent needs to be used in an excessive amount because it decomposes the phosphorus compound at the same time as oxidative decomposition under a temperature environment of 120 ° C. and also proceeds with autolysis.

Therefore, as a pretreatment method that replaces this pretreatment method, Non-Patent Document 2 proposes a method of treating at 100 ° C. for 60 minutes after adding potassium peroxodisulfate to test water. However, in this method, a portion of potassium peroxodisulfate remains in the test water, which may inhibit the reduction of the heteropoly compound by L (+)-ascorbic acid, so the ammonium molybdate-ascorbic acid mixture Before adding the solution, the test water is allowed to cool to 20-40 ° C to suppress the oxidation of potassium peroxodisulfate, or sodium sulfite as a reducing agent is added to the test water in an alkaline state. It is necessary to extinguish potassium disulfate.

However, when the oxidation of potassium peroxodisulfate is suppressed by allowing the test water to cool, it takes a long time to cool the test water, making it difficult to complete a series of quantitative operations in a short time. In addition, when sodium sulfite is added to extinguish potassium peroxodisulfate, harmful sulfur dioxide gas is generated. Therefore, safety measures are required.

Moreover, the above-mentioned method for determining total phosphorus contains a more essential problem. Specifically, as described in Non-Patent Document 1, since the quantification range is a minute range of 1.25 to 25 μg, it cannot be applied when the test water contains a relatively large amount of phosphate ions or phosphorus compounds. There is a bug. In addition, when the test water contains silica such as silicon dioxide, silicic acid and silicate, the quantitative result may be affected by the silica and may be unreliable. Furthermore, when the test water contains chloride ions, chlorine is generated from the chloride ions during the pretreatment of the test water, and this chlorine delays the color development of the test water due to the formation of molybdenum blue, thus obtaining a quantitative result. It may take a long time to complete.

An object of the present invention is to make it possible to quantitate total phosphorus in test water safely and in a short time.

The present invention relates to a method for quantifying the total phosphorus of test water by decomposing the phosphorus compound contained in the test water and converting it into phosphate ions, and then quantifying the phosphate ions of the test water, In this quantification method, the alkali metal salt of peroxodisulfuric acid or ammonium peroxodisulfate and sulfuric acid were added to the test water, and the process was heated for a predetermined time at a temperature from 65 ° C. to the boiling temperature of the test water. At least one hydroxyl group-containing compound selected from the group of hydroxyl group-containing compounds consisting of hydroxycarboxylic acids and alditols against test water, vanadium compounds having a vanadium valence of 3 to 5, aldoses having 5 carbon atoms, aldoses having 6 carbon atoms , Producing carbon 6 aldose, carbon 6 aldose or carbon 6 ketose by decomposition and decomposition Add saccharide compound selected from saccharide compound group consisting of possible oligosaccharides, hexaammonium heptamolybdate or alkali metal salt of molybdic acid and antimony compound with antimony valence of 3 and boil test water from 65 ° C Step 2 of heating for a predetermined time at a temperature up to the temperature, and Step 3 of measuring the absorbance of an arbitrary wavelength in the range of 600 to 950 nm for the test water that has passed through Step 2 are included.

Since this quantification method includes steps 1 to 3 described above, the total phosphorus in the test water can be quantified safely and in a short time.

In this quantification method, the hydroxyl group-containing compound, vanadium compound, saccharide compound, hexamolybdenum hexamolybdate or alkali metal salt of molybdic acid and the antimony compound can be added in two or more steps while providing an interval. .

The present invention according to another aspect relates to a method for coloring phosphate ions contained in test water. This color development method is applied to the test water that is set so that the test water contains sulfuric acid and the test water that has undergone the process A. On the other hand, at least one hydroxyl group-containing compound selected from the group of hydroxyl group-containing compounds consisting of hydroxycarboxylic acids and alditols, vanadium compounds having a vanadium valence of 3 to 5, aldoses having 5 carbon atoms, aldoses having 6 carbon atoms, carbon numbers A saccharide compound selected from the group of saccharides consisting of aldoses having 6 carbons, aldoses having 5 carbon atoms, aldoses having 6 carbon atoms, or oligosaccharides capable of producing ketoses having 6 carbon atoms by decomposition, hexaammonium hexamolybdate or molybdate Add alkali metal salt and antimony compound with antimony valence of 3, and test water from 65 ℃ At temperatures up to the boiling temperature and a step B of heat given time.

In this color development method, since a predetermined compound is added to the test water in the presence of sulfuric acid, phosphate ions contained in the test water can be safely developed in a short time.

In step A of the color development method, for example, an alkali metal salt of peroxodisulfuric acid or ammonium peroxodisulfate and sulfuric acid is added to the test water and heated at a temperature from 65 ° C. to the boiling temperature of the test water for a predetermined time. Is set to contain sulfuric acid.

In this case, in step B, it is preferable to add the hydroxyl group-containing compound, vanadium compound, saccharide compound, hexamolybdenum hexamolybdate or alkali metal salt of molybdic acid and the antimony compound in two or more portions while providing an interval.

The present invention according to yet another aspect relates to a color former for phosphate ions contained in test water, and the color former comprises at least one hydroxyl group selected from a hydroxyl group-containing compound group consisting of hydroxycarboxylic acids and alditol. Containing compounds, vanadium compounds having a valence of vanadium of 3 to 5, aldoses having 5 carbons, aldoses having 6 carbons, aldoses having 5 carbons by decomposition and ketoses having 6 carbons, aldoses having 6 carbons, or 6 carbons It consists of an aqueous solution containing a saccharide compound selected from the group of saccharide compounds consisting of oligosaccharides capable of producing ketose, hexammonium heptamolybdate or an alkali metal salt of molybdate, and an antimony compound having an antimony valence of 3.

Since this color former is composed of an aqueous solution containing a predetermined component, it can be used in the total phosphorus determination method and phosphate ion color development method according to the present invention.

The hydroxycarboxylic acids used in the quantification method, coloring method and coloring agent according to the present invention include, for example, citric acid, malic acid, aldaric acid and aldonic acid. The oligosaccharide is selected from the group consisting of sucrose, maltose, lactose, raffinose, kestose, stachyose, isomaltulose, maltulose and lactulose, for example. The vanadium compound is selected from the group consisting of, for example, vanadium (III) chloride, vanadium oxide sulfate (IV), sodium metavanadate (V) and vanadium oxide (V). The saccharide compound used in the color former of the present invention is preferably a non-reducing oligosaccharide selected from the group consisting of sucrose, raffinose, kestose and stachyose.

Other objects and effects of the present invention will be mentioned in the detailed description below.

FIG. 3 is a diagram showing a calibration curve created in Example 1. FIG. 6 is a diagram showing a calibration curve created in Example 2. FIG. 6 is a diagram showing a calibration curve created in Example 3. The figure which shows the calibration curve created in Example 4. FIG. FIG. 6 is a diagram showing a calibration curve created in Example 5. FIG. 6 is a diagram showing a calibration curve created in Example 6. FIG. 10 is a diagram showing a calibration curve created in Example 7. FIG. 10 is a diagram showing a calibration curve created in Example 8. FIG. 10 shows a calibration curve created in Example 9. FIG. 10 is a diagram showing a calibration curve created in Example 10. FIG. 10 is a diagram showing a calibration curve created in Example 11. The figure which shows the calibration curve created in Example 12. The figure which shows the calibration curve created in Example 13.

The test water capable of quantifying total phosphorus by the quantification method of the present invention is not particularly limited, but in addition to wastewater that is usually provided with phosphorus discharge regulations such as factory wastewater and domestic wastewater, marine water, Natural water such as lake water, river water and groundwater.

When quantifying the total phosphorus in the test water, a predetermined amount of the test water is collected and pretreated to convert the phosphorus compound contained in the test water into phosphate ions. In this pretreatment, first, an alkali metal salt of peroxodisulfuric acid or ammonium peroxodisulfate (hereinafter sometimes referred to as a peroxodisulfuric acid compound) and sulfuric acid are added to test water, and boiling of the test water starts at 65 ° C. under normal pressure. It is heated for a predetermined time at a temperature up to the temperature, preferably from 75 ° C. to the boiling temperature of the inspection water (step 1). As a result, organic and inorganic phosphorus compounds, particularly organic phosphorus compounds, contained in the test water are oxidatively decomposed by the peroxodisulfuric acid compound, and phosphorus elements are converted into phosphate ions.

The alkali metal salt of peroxodisulfuric acid used here is usually potassium peroxodisulfate or sodium peroxodisulfate.

The peroxodisulfuric acid compound is usually added to test water as an aqueous solution dissolved in purified water, for example, pure water, distilled water or ion exchange water. The concentration of this aqueous solution is usually preferably set to 0.4 to 50 g / L, and more preferably set to 3.0 to 40 g / L. The amount of the peroxodisulfuric acid compound aqueous solution added to the test water is preferably set so that the concentration of the peroxodisulfate compound in the test water can sufficiently oxidatively decompose the phosphorus compound contained in the test water. If it is added, the peroxodisulfuric acid compound remains in the inspection water, and there is a possibility of causing false color development in the step 2 described later. Therefore, the concentration of the peroxodisulfuric acid compound in the test water is preferably set so that the concentration of the peroxodisulfuric acid compound aqueous solution and sulfuric acid when added to the test water is usually 0.5 to 9 g / L. It is more preferable to set 1 to 6 g / L.

On the other hand, the amount of sulfuric acid added to the inspection water is preferably set so that the concentration of sulfuric acid when the aqueous peroxodisulfuric acid compound solution and sulfuric acid are added to the inspection water is 0.1 M or more. However, if too much is added, it may be necessary to neutralize sulfuric acid which is excessive for the purpose of forming molybdenum blue (coloration of phosphate ions) in Step 2 to be described later. It is preferable to set it to 1 to 0.3M.

The heating time of the inspection water in this step varies depending on the heating temperature, but it is usually preferable to set it to 20 to 40 minutes.

Next, a hydroxyl group-containing compound, a vanadium compound, a saccharide compound, a molybdenum compound and an antimony compound are added to the test water that has undergone step 1, and subsequently heated for a predetermined time (step 2). This process can be applied to the test water in the high temperature state or the heating continuation state after completion of the process 1 without cooling the test water that has passed through the process 1 by standing cooling or the like.

As the hydroxyl group-containing compound, at least one selected from the group of hydroxyl group-containing compounds consisting of hydroxycarboxylic acids and alditols is used. Hydroxycarboxylic acids include, for example, citric acid, malic acid, aldaric acid and aldonic acid, and salts thereof (eg, alkali metal salts). The aldaric acid used here is a compound represented by the general formula of HO ₂ C— (CHOH) n—CO ₂ H (n is an integer of 1 or more, preferably an integer of 1 to 5) and is water-soluble. Examples thereof include tartaric acid having n of 2 and mucoic acid having n of 4. The aldonic acid used here is represented by the general formula HO ₂ C— (CHOH) n—CH ₂ OH (n is an integer of 1 or more, preferably an integer of 1 to 5, more preferably 4 or 5). For example, n is 1 glyceric acid, n is 4 gluconic acid, and n is 5 glucoheptonic acid. The alditol used here is a compound represented by the general formula HOH ₂ C— (CHOH) n—CH ₂ OH (n is an integer of 1 or more, preferably an integer of 2 to 5) and is water-soluble. Examples thereof include erythritol, where n is 2, xylitol where n is 3, sorbitol where n is 4, and boremitol where n is 5.

As the vanadium compound, vanadium having a valence of 3 to 5 is used. Examples of vanadium compounds that can be used include vanadium chloride (III), vanadium oxide sulfate (IV), sodium metavanadate (V), and vanadium oxide (V). Two or more of these vanadium compounds may be used in combination.

In addition, as the vanadium compound, vanadium having a valence of 2 can be used (for example, vanadium (II) chloride). As a source of trivalent or tetravalent vanadium, a compound having a valence of vanadium is quickly converted to trivalent or tetravalent vanadium when added to the test water in this step. Can be used.

The saccharide compound is composed of an aldose having 5 carbon atoms, an aldose having 6 carbon atoms, a ketose having 6 carbon atoms, and an oligosaccharide capable of producing an aldose having 5 carbon atoms, an aldose having 6 carbon atoms or a ketose having 6 carbon atoms by decomposition. Those selected from the group of saccharide compounds are used. Examples of aldoses having 5 carbon atoms include ribose, arabinose and xylose. Examples of aldoses having 6 carbon atoms include altrose, glucose, mannose and galactose. Examples of ketoses having 6 carbon atoms include fructose and sorbose.

Examples of oligosaccharides that can generate aldoses having 5 carbon atoms, aldoses having 6 carbon atoms or ketoses having 6 carbon atoms by decomposition include, for example, disaccharides sucrose, maltose, lactose, isomaltulose, maltulose, lactulose, galacto Mention may be made of sucrose, primeverose and vicyanose, the trisaccharide raffinose, kestose, gentianose, planteose and umbelliferose, the tetrasaccharide stachyose and the pentasaccharide Verbasse. These exemplary oligosaccharides, upon decomposition, produce xylose (5 carbon aldose), glucose (6 carbon aldose), galactose (6 carbon aldose) or fructose (6 carbon ketose). Can do.

As the molybdenum compound, hexaammonium heptamolybdate or an alkali metal salt, alkaline earth metal salt or heavy metal salt of molybdic acid is used. Of these, it is preferable to use hexaammonium heptamolybdate or an alkali metal salt of molybdic acid. Examples of alkali metal salts of molybdate include sodium molybdate, potassium molybdate and lithium molybdate. Examples of alkaline earth metal salts of molybdate include calcium molybdate and magnesium molybdate. Examples of the heavy metal salt of molybdate include zinc molybdate and aluminum molybdate.

As the antimony compound, an antimony compound having an antimony valence of 3 is used. Examples of the antimony compound having an antimony valence of 3 include potassium antimonyl tartrate, antimony trioxide (that is, antimony (III) oxide), and a halide salt of antimony. As the halide salt of antimony, it is preferable to use antimony trichloride (that is, antimony (III) chloride) that hardly generates harmful substances by hydrolysis.

As the antimony compound, an antimony compound having an antimony valence of 5 can also be used. Since this antimony compound is naturally converted into an antimony compound having an antimony valence of 3 in an aqueous solution, it can be used as a source of the antimony compound having an antimony valence of 3. Examples of the antimony compound having an antimony valence of 5 usable here include antimony pentoxide (that is, antimony (V) oxide) and an antimony halide salt having a valence of 5. As the halide salt of antimony having a valence of 5, it is preferable to use antimony pentachloride (that is, antimony chloride (V)) that does not easily generate harmful substances by hydrolysis.

In this step, the hydroxyl group-containing compound, vanadium compound, saccharide compound, molybdenum compound and antimony compound are usually added to the inspection water as an aqueous solution dissolved in purified water. Under the present circumstances, each aqueous solution of a hydroxyl-containing compound, a vanadium compound, a saccharide compound, a molybdenum compound, and an antimony compound can be prepared, and each aqueous solution can be added separately with respect to test water. Moreover, the aqueous solution of a saccharide compound and the aqueous solution which contains a hydroxyl-containing compound, a vanadium compound, a molybdenum compound, and an antimony compound simultaneously can be prepared separately, and these aqueous solutions can be added separately with respect to test water. Since the aqueous solutions used in these addition methods are all stable, they can be prepared and stored in advance and used as appropriate.

However, the hydroxyl group-containing compound, vanadium compound, saccharide compound, molybdenum compound and antimony compound are preferably added to the test water as an aqueous solution containing these simultaneously. This aqueous solution (hereinafter sometimes referred to as a mixed aqueous solution, which corresponds to the phosphate ion color former according to the present invention) includes, for example, a hydroxyl group-containing compound, a vanadium compound, a saccharide compound, a molybdenum compound, and an antimony compound. Each aqueous solution is prepared and can be prepared by mixing immediately before each aqueous solution is added to the test water, and also includes an aqueous solution of a saccharide compound and an aqueous solution containing a hydroxyl group-containing compound, a molybdenum compound and an antimony compound simultaneously. Can be prepared separately and mixed immediately before adding both aqueous solutions to the test water.

In the case of using a non-reducing oligosaccharide capable of generating an aldose having 5 carbon atoms, an aldose having 6 carbon atoms or a ketose having 6 carbon atoms by decomposition as the saccharide compound, the oligosaccharide, the hydroxyl group-containing compound, the vanadium compound, molybdenum It is also possible to prepare a mixed aqueous solution by simultaneously dissolving the compound and the antimony compound in purified water. This mixed aqueous solution can be stably stored for a long period of time because the reaction between solutes does not substantially react. The non-reducing oligosaccharide used in this case is usually sucrose, raffinose, kestose or stachyose, and these oligosaccharides are decomposed by glucose (carbon number 6 aldose), galactose (carbon number 6 aldose). ) Or fructose (6 carbon ketoses).

When using an alkaline earth metal salt of molybdic acid as the molybdenum compound, an appropriate amount of sulfuric acid or hydrochloric acid should be added to promote dissolution of the alkaline earth metal salt of molybdic acid during the preparation of the various aqueous solutions described above. Can do. When antimony trioxide is used as the antimony compound, an appropriate amount of hydrochloric acid can be added in order to promote dissolution of antimony trioxide during the preparation of the various aqueous solutions described above.

In this step, the phosphate ion originally contained in the test water and the phosphate ion generated by the oxidative decomposition of the phosphorus compound in step 1 react with the added molybdenum compound and antimony compound to form a heteropoly compound. . And the produced | generated heteropoly compound is reduce | restored with the saccharide compound added at this process in the acidic environment by the sulfuric acid added at the process 1. FIG. More specifically, when the saccharide compound is an aldose having 5 carbon atoms, an aldose having 6 carbon atoms, or a ketose having 6 carbon atoms, the heteropoly compound is reduced thereby. When the saccharide compound is an oligosaccharide, the heteropoly compound is reduced by an aldose having 5 carbon atoms, an aldose having 6 carbon atoms, or a ketose having 6 carbon atoms generated by the decomposition. In this case, when a reducing oligosaccharide such as maltose, lactose, isomaltulose, maltulose, lactulose and primeverose is used, the heteropoly compound produced also by the reducing oligosaccharide itself can be reduced. Reduction of such a heteropoly compound generates molybdenum blue (coloration of phosphate ions), and the molybdenum blue changes the color of the inspection water.

Here, the peroxodisulfuric acid compound remaining in the test water without being consumed for the oxidative decomposition of the phosphorus compound in Step 1 is decomposed by the saccharide compound and quickly disappears before the heteropoly compound is formed. Specifically, when the saccharide compound is an aldose having 5 carbon atoms, an aldose having 6 carbon atoms, or a ketose having 6 carbon atoms, these monosaccharides decompose and disappear the peroxodisulfuric acid compound remaining in the test water. To do. On the other hand, when the saccharide compound is an oligosaccharide, the peroxodisulfuric acid compound remaining by the aldose having 5 carbon atoms, the aldose having 6 carbon atoms, or the ketose having 6 carbon atoms generated by the decomposition of the oligosaccharide is decomposed and disappears. . When an oligosaccharide is used as the saccharide compound, the remaining peroxodisulfuric acid compound can be decomposed by the oligosaccharide itself. As a result, the peroxodisulfuric acid compound remaining in the test water without being consumed for the oxidative decomposition of the phosphorus compound is prevented from interfering with the reduction of the heteropoly compound.

Further, silica such as silicon dioxide, silicic acid and silicate contained in the inspection water is inhibited from reacting with phosphate ions by the action of the hydroxyl group-containing compound to form a complex. For this reason, the phosphate ion in the test water reacts with the molybdenum compound and the antimony compound to stably generate a heteropoly compound and can develop color by generating molybdenum blue. That is, phosphate ions are suppressed from being affected by silica in the color development due to the formation of molybdenum blue.

Furthermore, in the case where the test water contains chloride ions, there is a possibility that chlorine that causes the generation of molybdenum blue to be delayed is generated in Step 1, and the generated chlorine is a saccharide added to the test water in this step. Consumed by the compound. In addition, such a chlorine consumption reaction is accelerated in the presence of a vanadium compound. As a result, in this step, even when chlorine is contained in the inspection water, the production of molybdenum blue proceeds promptly, and it is possible to move quickly to the next step.

The concentration of the hydroxyl group-containing compound in the test water (the concentration at the time of addition) is preferably set to an amount that can sufficiently suppress the color development due to the formation of molybdenum blue from being affected by silica. From this point of view, the concentration of the hydroxyl group-containing compound in the test water is usually preferably set to 0.5 to 10 g / L, and more preferably set to 1 to 7 g / L.

The concentration of the vanadium compound in the test water (concentration at the time of addition, and the converted concentration excluding water molecules when hydrate is used) is sufficient to accelerate the consumption of chlorine by the saccharide compound added to the test water It is preferable to set to an appropriate amount. From this viewpoint, the concentration of the vanadium compound in the test water is usually preferably set to 0.05 to 10 g / L, and more preferably set to 0.1 to 3.0 g / L.

The concentration of the saccharide compound in the test water (the concentration at the time of addition, and when oligosaccharide is used, the concentration of aldose having 5 carbons, aldose having 6 carbons, or ketose having 6 carbons produced by the decomposition) It is an amount necessary for eliminating the peroxodisulfuric acid compound remaining in water, and when chlorine is produced in Step 1, it is an amount necessary for consuming the chlorine, and the produced heteropolysulfate It is preferable to set the concentration of the compound to be sufficiently reducible. From this viewpoint, the concentration of the saccharide compound in the test water is usually preferably set to 2 to 60 g / L, and more preferably set to 5 to 40 g / L.

The concentration of the molybdenum compound in the test water (the concentration at the time of addition, and when using a hydrate, the concentration converted excluding water molecules) is usually preferably set to 0.3 to 3.0 g / L. More preferably, it is set to 0.5 to 2.0 g / L. In addition, the concentration of the antimony compound in the test water (the concentration at the time of addition, and the concentration converted without water molecules when a hydrate is used) is usually set to 0.01 to 0.24 g / L. It is more preferable that the setting is 0.02 to 0.13 g / L. However, the concentration ratio (A: B) between the antimony compound (A) and the molybdenum compound (B) in the test water is preferably set to 1: 8 to 100, and preferably 1:10 to 50. It is more preferable to set.

The concentration of each of the hydroxyl group-containing compound, vanadium compound, saccharide compound, molybdenum compound and antimony compound in the test water is usually determined by the concentration of these compounds in each aqueous solution added to the test water and the amount of each aqueous solution added. It can be controlled by adjusting.

In this step, the hydroxyl group-containing compound, vanadium compound, saccharide compound, molybdenum compound, and antimony compound can be added in portions to the test water while providing an interval in two or more steps. For example, after Step 1, a part of the total amount of each aqueous solution of these compounds to be added to the test water can be added, and the remainder of the total amount of each aqueous solution can be added when a predetermined time has elapsed. The predetermined time of the divided addition interval is usually preferably set to 1 to 30 minutes. In such a divided addition, the amount added at the time of the first addition may change due to the molybdenum compound coming into contact with the peroxodisulfate compound remaining in the test water, and the coloration of phosphate ions may be impaired. Therefore, it is preferable to set the amount less than the amount added at the second and subsequent additions. For example, 20% of the total amount of each aqueous solution is preferably added at the first addition, and the remaining 80% of each aqueous solution is added at the second addition.

The heating temperature of the inspection water in the step 2 can be set to the same temperature range as the heating in the step 1, but it is usually preferable to set the same as the heating temperature in the step 1. In addition, the heating time of the inspection water in this step (the heating time after the last addition in the case of the above-mentioned divided addition) varies depending on the heating temperature, but is a time sufficient for completing the coloration of phosphate ions. is there. This time can be normally set to a short time of about 5 to 30 minutes since the influence of chlorine derived from chloride ions contained in the inspection water is eliminated.

The

above steps

1 and 2 can be operated safely under normal pressure and can be safely carried out because no harmful gas is generated. In addition, since it is not necessary to cool the inspection water by standing cooling or the like when moving from step 1 to step 2, the inspection water after step 1 is completed can be transferred to step 2 smoothly and quickly. Further, even when chlorine is generated in Step 1, since this chlorine is quickly consumed by the saccharide compound in the presence of the vanadium compound, it is difficult to delay the color development of the test water by molybdenum blue. For this reason, from the start of step 1 to the completion of step 2, it can usually be completed in a short time of about 30 to 90 minutes.

Next, the absorbance at an arbitrary wavelength in the range of 600 to 950 nm is measured for the test water discolored by molybdenum blue (step 3). Then, based on a calibration curve prepared by examining the relationship between the absorbance and the phosphate ion concentration in advance, the phosphate ion amount of the test water, that is, the total phosphorus amount is determined from the absorbance measurement value.

The method for quantifying total phosphorus according to the present invention can be safely carried out without using a special reaction apparatus such as a pressure vessel that requires attention in handling, and it is not necessary to cool inspection water between processes. Therefore, a series of processes can be smoothly advanced without interruption, and can be completed in a short time. For this reason, this quantification method is easy to apply to automation. In particular, when a mixed aqueous solution is used in step 2, the mixed aqueous solution can be added to the test water at the same time by adding only the required compound, and can be stored, making it easier to apply to automation. .

In the method for determining total phosphorus according to the present invention, when a calibration curve is prepared, the linear relationship between the phosphate ion concentration and the absorbance at an arbitrary wavelength in the range of 600 to 950 nm is relatively high. Since it is well established up to the range of the phosphate ion concentration, the upper limit of quantification of phosphate ions contained in the test water is expanded to a range of 4 mg [P] / L or more. Therefore, this quantification method can also be applied to test water having a high content of phosphate ions and phosphorus compounds.

Step 2 in the quantification method of the present invention can be used as a method for coloring phosphate ions in test water containing phosphate ions. For example, when it is necessary to simply determine whether or not the test water contains phosphate ions, this determination can be easily performed in a short time by using this coloring method.

However, the inspection water to which this coloring method is applied needs to be set in advance to contain sulfuric acid (step A). Test water containing sulfuric acid can be prepared simply by adding sulfuric acid to the test water. In this color development method, when Step 2 of the quantification method of the present invention is applied to test water set to contain sulfuric acid (Step B), phosphate ions contained in the test water are colored by the generation of molybdenum blue. Therefore, when this color development method is applied to test water, and coloration of phosphate ions is observed in the test water, it can be determined that the test water contains phosphate ions. When color development of phosphate ions is not observed, it can be determined that the test water does not contain phosphate ions.

In addition, when the color development method as described above is applied to the test water, and the color development of phosphate ions is not observed in the test water, it is determined whether or not the test water contains a phosphorus compound by applying this color development method. It can also be determined. In this case, in step A, step 1 in the quantification method of the present invention is applied to the test water. As a result, the test water is set so as to contain sulfuric acid, and when the phosphorus compound is contained, the phosphorus compound is converted into phosphate ions. Then, when the process B is applied to the test water that has undergone the process A, and color development of phosphate ions is observed in the test water, it can be determined that the test water contains a phosphorus compound. If no coloration of phosphate ions is observed in water, it can be determined that the test water does not contain a phosphorus compound.

Thus, when the process A is performed by applying the process 1 of the present invention to the test water, in the process B, the hydroxyl group-containing compound, the vanadium compound, It is preferable to add the saccharide compound, the molybdenum compound and the antimony compound separately to the test water while providing an interval in two or more steps.

The unit of mg [P] / L indicates the number of milligrams of phosphorus contained in 1 L of water.
Reagents and spectrophotometers The reagents and spectrophotometers used in the following examples and the like are as follows.
Phosphorus standard solution (for water quality test): Wako Pure Chemical Industries, Ltd. Code 160-19241
Silicon standard solution: Wako Pure Chemical Industries, Ltd. Code 192-06031
Chloride ion standard solution: Wako Pure Chemical Industries, Ltd. Code 032-16151
1M sulfuric acid (for volumetric analysis): Wako Pure Chemical Industries, Ltd. Code 198-09595
Sodium hydroxide (reagent special grade): Wako Pure Chemical Industries, Ltd. Code 198-13765
Hydrochloric acid (special grade reagent): Wako Pure Chemical Industries, Ltd. Code 080-01066
Potassium peroxodisulfate (for nitrogen and phosphorus measurement): Wako Pure Chemical Industries, Ltd. Code 169-1189
Ammonium peroxodisulfate (special grade reagent): Wako Pure Chemical Industries, Ltd. Code 012-03285
Hexamolybdate hexaammonium tetrahydrate (special grade reagent): Wako Pure Chemical Industries, Ltd. Code 018-06901
Lithium molybdate: Wako first grade code 125-03501 from Wako Pure Chemical Industries, Ltd.
Potassium molybdate: Wako Pure Chemical Industries, Ltd. Code 165-04002
Molybdenum (VI) disodium dihydrate (reagent special grade): Wako Pure Chemical Industries, Ltd. Code 190-02475
Potassium antimonyl tartrate trihydrate (reagent special grade): Wako Pure Chemical Industries, Ltd. Code 020-12832
Antimony (III) oxide (chemical): Wako Pure Chemical Industries, Ltd. Code 018-04402
Antimony (III) chloride (special reagent grade): Wako Pure Chemical Industries, Ltd. Code 011-0492
DL-tartaric acid: Wako special grade code 203-00052 from Wako Pure Chemical Industries, Ltd.
Mucus acid: Tokyo Chemical Industry Co., Ltd. Code M0466
Sodium gluconate: Wako Special Code 193-13195 from Wako Pure Chemical Industries, Ltd.
Sodium glucoheptonate dihydrate: Tokyo Chemical Industry Co., Ltd. Code G0214
DL-glyceric acid (40% aqueous solution): Tokyo Chemical Industry Co., Ltd. Code D0602
DL-malic acid: Wako Special Code 139-00565 from Wako Pure Chemical Industries, Ltd.
Citric acid: Wako Special Code 030-05525 from Wako Pure Chemical Industries, Ltd.
meso-erythritol: Wako first grade code 056-00242 from Wako Pure Chemical Industries, Ltd.
Xylitol: Wako Pure Chemical Industries, Ltd. Wako Premium Code 244-00542
Sorbitol: Wako first grade code 194-03752 from Wako Pure Chemical Industries, Ltd.
Sodium metavanadate (V): Wako Pure Chemical Industries, Ltd. Code 190-07010
Vanadium oxide (V): Wako Pure Chemical Industries, Ltd. Code 222-00122
Vanadium oxide (IV) n hydrate: Wako Pure Chemical Industries, Ltd. Code 223-01132
Vanadium chloride (III): Sigma-Aldrich Japan Co., Ltd. Code 208272
D-fructose: Wako Special Grade code 127-02765 from Wako Pure Chemical Industries, Ltd.
D-arabinose: Wako Special Grade code 013-04572 from Wako Pure Chemical Industries, Ltd.
D-glucose (special grade reagent): Wako Pure Chemical Industries, Ltd. Code 047-10059
Sucrose (special grade reagent): Wako Pure Chemical Industries, Ltd. Code 196-00001
D-Raffinose pentahydrate (reagent special grade): Wako Pure Chemical Industries, Ltd. Code 180-00012
D-maltose monohydrate: Wako special grade code 130-00615 from Wako Pure Chemical Industries, Ltd.
Lactose monohydrate (special grade reagent): Wako Pure Chemical Industries, Ltd. Code 128-00095
D-galactose (special grade reagent): Wako Pure Chemical Industries, Ltd. Code 071-00032
1-kestose (for biochemistry): Wako Pure Chemical Industries, Ltd. Code 112-00433
Stachyose n hydrate: Wako Pure Chemical Industries, Ltd. Code 196-12564
Isomaltulose: Palatinose monohydrate (for biochemistry) from Wako Pure Chemical Industries, Ltd. Code 169-12991
Martulose monohydrate: Tokyo Chemical Industry Co., Ltd. Code M1138
Lactulose (for biochemistry): Wako Pure Chemical Industries, Ltd. Code 126-03732
Adenosine-5′-triphosphate disodium salt trihydrate (for biochemistry): Wako Pure Chemical Industries, Ltd. Code 018-16911
Phenyl disodium phosphate dihydrate: Wako Pure Chemical Industries, Ltd. Wako Special Code 044-04262
Sodium diphosphate decahydrate (special grade reagent): Wako Pure Chemical Industries, Ltd. Code 195-03025
Ascorbic acid (special grade reagent): Wako Pure Chemical Industries, Ltd. Code 014-04801
Spectrophotometer: Shimadzu Corporation trade name “UV-1600PC”

Phosphate ion solution The phosphate ion solution used in the following examples and the like is as follows.
Five types of phosphate ion solutions having phosphate ion concentrations of 0, 1.0, 2.0, 3.0, and 4.0 mg [P] / L were prepared. For phosphate ion solutions with a phosphate ion concentration of 0 mg [P] / L, distilled water was used as it was, and for other phosphate ion solutions, the phosphate standard concentration was adjusted by diluting the phosphorus standard solution with distilled water. .

Experimental example 1
The following sample water and oxidizer aqueous solution were prepared. The D-glucose used for the preparation of the

sample waters

2, 3 and 4 assumes an organic substance as a contaminant.
<Sample water>
Sample water 1:
A phosphate ion solution having a phosphate ion concentration of 5 mg [P] / L.
Sample water 2:
An aqueous solution obtained by dissolving sodium diphosphate decahydrate and D-glucose in distilled water (sodium diphosphate equivalent concentration is 5 mg [P] / L, D-glucose concentration is 40 mg / L).
Sample water 3:
An aqueous solution obtained by dissolving adenosine-5′-triphosphate disodium salt trihydrate and D-glucose in distilled water (adenosine-5′-triphosphate disodium equivalent concentration is 5 mg [P] / L D-glucose concentration is 40 mg / L).
Sample water 4:
Aqueous solution obtained by dissolving phenyl disodium phosphate dihydrate and D-glucose in distilled water (phenyl disodium phosphate equivalent concentration is 5 mg [P] / L, D-glucose concentration is 40 mg / L) .

<Oxidizing agent aqueous solution>
Oxidizing agent aqueous solution 1:
A potassium peroxodisulfate aqueous solution having a concentration of 40 g / L (a potassium peroxodisulfate aqueous solution having a concentration described in JIS K 0102 46.1.1 (hereinafter referred to as “JIS method concentration”)).
Oxidizing agent aqueous solution 2:
A potassium peroxodisulfate aqueous solution having a concentration of 20 g / L (a potassium peroxodisulfate aqueous solution having a concentration of 50% of the JIS method concentration).
Oxidizing agent aqueous solution 3:
A potassium peroxodisulfate aqueous solution having a concentration of 8 g / L (a potassium peroxodisulfate aqueous solution having a concentration of 20% of the JIS method concentration).
Oxidizing agent aqueous solution 4:
A potassium peroxodisulfate aqueous solution having a concentration of 4 g / L (a potassium peroxodisulfate aqueous solution having a concentration of 10% of the JIS method concentration).
Oxidizing agent aqueous solution 5:
A potassium peroxodisulfate aqueous solution having a concentration of 2 g / L (a potassium peroxodisulfate aqueous solution having a concentration of 5% of the JIS method concentration).
Oxidizing agent aqueous solution 6:
A potassium peroxodisulfate aqueous solution having a concentration of 0.4 g / L (a potassium peroxodisulfate aqueous solution having a concentration of 1% of the JIS method concentration).

1 mL of one of the oxidizer aqueous solutions 1 to 6 was added to 5 mL of each of the sample water 1 to 4, and 1 mL of 1M sulfuric acid was further added, and then each sample water was heated at 95 ° C. for 40 minutes using a block heater. . Each sample water was diluted 5 times with distilled water, and each sample water was colored according to the molybdenum blue (ascorbic acid reduction) absorptiometric method described in 46.1.1 of JIS K 0102, and the absorbance at 890 nm was obtained. It was measured. That is, 0.2 mL of a 5: 1 mixed solution of ammonium molybdate solution and ascorbic acid solution specified in the same method was added to diluted sample water and left at 25 ° C. for about 15 minutes, and then the absorbance at 890 nm was measured. It was measured. The results are shown in Table 1.

In Table 1, the oxidative degradation rate of sample waters 2 to 4 is the ratio of absorbance to the absorbance measured for sample water 1, and is converted to phosphate ions by oxidative degradation among the phosphorus compounds contained in sample water. Shows the percentage of food. According to the oxidative degradation rate in Table 1, the phosphorus compound contained in the sample water is 90% or more when an aqueous solution (oxidant aqueous solution 4) having a potassium peroxodisulfate concentration of 4 g / L or more is used. When an aqueous solution (oxidant aqueous solution 3) having a concentration of 8 g / L or more is used, 95% or more is decomposed and converted into phosphate ions. From this, potassium peroxodisulfate in the oxidizing agent aqueous solution can effectively oxidatively decompose the phosphorus compound contained in the sample water even when the concentration is set to about 1/5 or less of the JIS method concentration. .

Experimental example 2
The following sample water was prepared. The D-glucose used for the preparation of the sample waters 5 and 6 assumes an organic substance as a contaminant.
Sample water 5:
Dissolving adenosine-5'-triphosphate disodium trihydrate, phenyl disodium phosphate dihydrate and D-glucose in distilled water to reduce the concentration of adenosine-5'-triphosphate disodium to 1 mg An aqueous solution in which [P] / L, phenyl disodium phosphate concentration is adjusted to 1 mg [P] / L, and D-glucose concentration is adjusted to 50 mg / L.
Sample water 6:
An aqueous solution in which sodium diphosphate decahydrate and D-glucose are dissolved in distilled water to adjust the sodium diphosphate concentration to 2 mg [P] / L and the D-glucose concentration to 50 mg / L.

To each 5 mL of sample water, 0.8 mL of potassium peroxodisulfate aqueous solution having a concentration of 30 g / L and 1.2 mL of 1M sulfuric acid were added. And each sample water was heated for 40 minutes at 95 degreeC using the block heater, Then, it cooled with water rapidly. Distilled water is added to each sample water after cooling to dilute it twice, and in the same manner as in Experimental Example 1, according to the molybdenum blue (ascorbic acid reduction) spectrophotometric method described in JIS K 0102 46.1.1. Each sample water was colored and the absorbance at 890 nm was measured. Moreover, about the case where the heating time of each sample water by a block heater was shortened, the sample water was similarly developed and the light absorbency of 890 nm was measured. The results are shown in Table 2.

In Table 2, the relative decomposition rate means the decomposition rate of the phosphorus compound at each heating time when the decomposition rate of the phosphorus compound contained in each sample water is 100% when the heating time is 40 minutes, This is calculated based on the ratio of the absorbance to the absorbance when the heating time is 40 minutes. According to Table 2, it can be seen that the phosphorus compound in the sample water is decomposed by 90% or more in 25 minutes and 98% or more in 30 minutes.

Experimental example 3
The following sample water was prepared.
Sample water 7:
Adenosine-5′-triphosphate disodium trihydrate concentration of 65 mg / L (1 mg [P] / L), phenyl disodium phosphate dihydrate concentration of 82 mg / L (1 mg [P] / L) , D-glucose (assuming organic substances as contaminants) concentration of 20 mg / L, silica concentration of 50 mg [Si] / L, and chloride ion concentration of 75 mg / L in adenosine-5 ′ Disodium triphosphate trihydrate, phenyl disodium phosphate dihydrate, D-glucose, silicon standard solution and chloride ion standard solution were dissolved, and 5 mL of sample water was prepared. This sample water has a total phosphorus concentration of 2 mg [P] / L. In the preparation of the sample water, since the silicon standard solution is alkaline, a silicon standard solution neutralized by adding 1 M sulfuric acid was used, and the silica concentration was adjusted as described above.

Sample water 8:
Without using the silicon standard solution, 5 mL of sample water having a total phosphorus concentration of 2 mg [P] / L was prepared in the same manner as Sample Water 7.

1 mL of 1M sulfuric acid and 1.0 mL of potassium peroxodisulfate having a concentration of 30 g / L were added to the sample water 7 and heated at 95 ° C. for 30 minutes using a block heater. Subsequently, 1.0 mL of a color former was added in a state where the sample water 7 was heated to 95 ° C., and left for 40 minutes. The color former used here is a solution in which sucrose, hexaammonium heptamolybdate tetrahydrate and potassium antimonyl tartrate trihydrate are dissolved in distilled water, and the concentration of sucrose is 100 g / L, hexamolybdate hexahydrate. The concentration of ammonium tetrahydrate was adjusted to 7 g / L, and the concentration of potassium antimonyl tartrate trihydrate was adjusted to 0.5 g / L. The time from when the color former was added to when the sample water started to change color was about 30 minutes. This is because it took time for chlorine produced from chloride ions to be consumed by sucrose and monosaccharides produced by its decomposition.

The absorbance at 830 nm of the sample water 7 after the heating was measured was 1.36. The absorbance at the same wavelength was measured for sample water 8 treated in the same manner (similar to sample water 7, the time from when the color former was added to when the sample water started to change color). .02. Since the sample water 7 containing silica has an absorbance about 1.3 times that of the sample water 8 not containing silica, the measurement result of total phosphorus is greatly affected by silica.

Examples 1 to 10
(Create a calibration curve)
For each 2.5 mL of the five phosphate ion solutions having phosphate ion concentrations of 0, 1.0, 2.0, 3.0, and 4.0 mg [P] / L, 0.7 mL of 1M sulfuric acid was obtained. The peroxodisulfuric acid compound aqueous solution 0.5mL shown in 3 was added, and it heated at 95 degreeC for 30 minute (s) using the block heater.

Next, while maintaining the state heated to 95 ° C., 0.5 mL of a color former was added and left for 20 minutes. The color former used here is alkaline by dissolving the components shown in Table 3 in distilled water so as to have the concentrations shown in the same table, and adding an aqueous sodium hydroxide solution adjusted to 0.5 M to make it colorless. It has been adjusted to.

For each phosphate ion solution treated as described above, the absorbance at the wavelengths shown in Table 4 was measured, and a calibration curve for determining the phosphate ion concentration from the absorbance was prepared. The results are shown in FIGS. According to FIGS. 1 to 10, this calibration curve shows high linearity at least in the range where the phosphate ion concentration is 0 to 4 mg [P] / L.

(Test water preparation)
The following test water was prepared. In the preparation of test water using a silicon standard solution, the silicon standard solution neutralized by adding 1 M sulfuric acid was used because the silicon standard solution was alkaline.

Test water A:
Adenosine-5′-triphosphate disodium trihydrate concentration is 65 mg / L (1.00 mg [P] / L), and phenyl disodium phosphate dihydrate concentration is 82 mg / L (1.00 mg [P ] / L), adenosine-5′-triphosphate disodium in distilled water so that the concentration of D-glucose (assuming organic substances as impurities) is 20 mg / L and the chloride ion concentration is 100 mg / L. Trihydrate, phenyl disodium phosphate dihydrate, D-glucose and chloride ion standard solution were dissolved, and 2.5 mL of test water having a total phosphorus concentration of 2.00 mg [P] / L was prepared. .

Test water B:
Except that the silicon standard solution was further dissolved so that the silica concentration was 45 mg / L, 2.5 mL of test water having a total phosphorus concentration of 2.00 mg [P] / L was prepared in the same manner as test water A.

Test water C:
2.5 mL of test water with a total phosphorus concentration of 2.00 mg [P] / L was used in the same manner as test water A, except that the chloride ion standard solution was used so that the chloride ion concentration was 150 mg / L. Prepared.

Test water D:
Except that the silicon standard solution was dissolved so that the silica concentration was 30 mg / L, 2.5 mL of test water having a total phosphorus concentration of 2.00 mg [P] / L was prepared in the same manner as test water C.

Test water E:
2.5 mL of test water having a total phosphorus concentration of 2.00 mg [P] / L is the same as test water A except that the chloride ion standard solution is used so that the chloride ion concentration becomes 200 mg / L. Prepared.

Test water F:
2.5 mL of test water having a total phosphorus concentration of 2.00 mg [P] / L was prepared in the same manner as test water E, except that the silicon standard solution was dissolved so that the silica concentration was 35 mg / L.

Test water G:
2.5 mL of test water with a total phosphorus concentration of 2.00 mg [P] / L was used in the same manner as test water A, except that the chloride ion standard solution was used so that the chloride ion concentration became 75 mg / L. Prepared.

Test water H:
Except that the silicon standard solution was dissolved so that the silica concentration was 40 mg / L, 2.5 mL of test water having a total phosphorus concentration of 2.00 mg [P] / L was prepared in the same manner as the test water G.

Test water I:
Except that the silicon standard solution was dissolved so that the silica concentration was 35 mg / L, 2.5 mL of test water having a total phosphorus concentration of 2.00 mg [P] / L was prepared in the same manner as the test water G.

Test water J:
Adenosine-5′-triphosphate disodium trihydrate concentration of 97.5 mg / L (1.50 mg [P] / L), phenyl disodium phosphate dihydrate concentration of 123 mg / L (1.50 mg) [P] / L), adenosine-5′-triphosphate in distilled water so that the concentration of D-glucose (assuming organic substances as impurities) is 20 mg / L and the chloride ion concentration is 30 mg / L. Dissolve disodium trihydrate, phenyl disodium phosphate dihydrate, D-glucose and chloride ion standard solution, and add 2.5 mL of test water with a total phosphorus concentration of 3.00 mg [P] / L Prepared.

Test water K:
Except that the silicon standard solution was dissolved so that the silica concentration was 40 mg / L, 2.5 mL of test water having a total phosphorus concentration of 3.00 mg [P] / L was prepared in the same manner as test water J.

Test water L:
2.5 mL of test water having a total phosphorus concentration of 3.00 mg [P] / L is the same as test water J except that the chloride ion standard solution was used so that the chloride ion concentration was 100 mg / L. Prepared.

Test water M:
2.5 mL of test water having a total phosphorus concentration of 3.00 mg [P] / L was prepared in the same manner as the test water L, except that the silicon standard solution was dissolved so that the silica concentration was 35 mg / L.

Test water N:
2.5 mL of test water with a total phosphorus concentration of 3.00 mg [P] / L was used in the same manner as test water J, except that the chloride ion standard solution was used so that the chloride ion concentration was 150 mg / L. Prepared.

Test water O:
Except that the silicon standard solution was dissolved so that the silica concentration was 40 mg / L, 2.5 mL of test water having a total phosphorus concentration of 3.00 mg [P] / L was prepared in the same manner as the test water N.

Test water P:
Adenosine-5′-triphosphate disodium trihydrate concentration of 32.5 mg / L (0.50 mg [P] / L), phenyl disodium phosphate dihydrate concentration of 41 mg / L (0.50 mg) [P] / L), adenosine-5′-triphosphate in distilled water so that the concentration of D-glucose (assuming organic substances as impurities) is 20 mg / L and the chloride ion concentration is 200 mg / L. Dissolve disodium trihydrate, phenyl disodium phosphate dihydrate, D-glucose and chloride ion standard solution, and add 2.5 mL of test water with a total phosphorus concentration of 1.00 mg [P] / L Prepared.

Test water Q:
Except that the silicon standard solution was dissolved so that the silica concentration was 30 mg / L, 2.5 mL of test water having a total phosphorus concentration of 1.00 mg [P] / L was prepared in the same manner as the test water P.

Test water R:
Adenosine-5′-triphosphate disodium trihydrate concentration is 130 mg / L (2.00 mg [P] / L), phenyl disodium phosphate dihydrate concentration is 164 mg / L (2.00 mg [P ] / L), adenosine-5′-triphosphate disodium in distilled water so that the concentration of D-glucose (assuming organic substances as impurities) is 20 mg / L and the chloride ion concentration is 50 mg / L. Trihydrate, phenyl disodium phosphate dihydrate, D-glucose and chloride ion standard solution were dissolved, and 2.5 mL of test water having a total phosphorus concentration of 4.00 mg [P] / L was prepared. .

Test water S:
Except that the silicon standard solution was dissolved so that the silica concentration was 50 mg / L, 2.5 mL of test water having a total phosphorus concentration of 4.00 mg [P] / L was prepared in the same manner as the test water R.

(Total phosphorus determination of test water)
To the test water shown in Table 4, 0.7 mL of 1M sulfuric acid and 0.5 mL of a peroxodisulfuric acid compound aqueous solution shown in Table 3 were added and heated at 95 ° C. for 30 minutes using a block heater. Next, with the test water heated to 95 ° C., 0.5 mL of a color former (the same as that used when preparing the calibration curve) was added and left for 20 minutes. Table 4 shows the time from when the color former is added to when the test water starts to develop color (color development start time).

For the test water after heating, the absorbance at the wavelengths shown in Table 4 was measured, and the total phosphorus concentration was quantified based on a calibration curve created from the measured values. The results are shown in Table 4.

Examples 11-13
(Create a calibration curve)
For each 2.5 mL of the five phosphate ion solutions having phosphate ion concentrations of 0, 1.0, 2.0, 3.0, and 4.0 mg [P] / L, 0.7 mL of 1M sulfuric acid was obtained. The peroxodisulfuric acid compound aqueous solution 0.5mL shown in 5 was added, and it heated at 95 degreeC for 30 minute (s) using the block heater.

Next, while maintaining the state heated to 95 ° C., 0.1 mL of a color former was added and left for 2 minutes. Subsequently, while maintaining the state heated to 95 ° C., 0.4 mL of a color former was further added and left for 18 minutes. The color former used here is alkaline by dissolving the components shown in Table 5 in distilled water so as to have the concentrations shown in the same table, and adding an aqueous sodium hydroxide solution adjusted to 0.5 M to make it colorless. It has been adjusted to.

The absorbance at the wavelengths shown in Table 6 was measured for each phosphate ion solution treated as described above, and a calibration curve for determining the phosphate ion concentration from the absorbance was prepared. The results are shown in FIGS. According to FIGS. 11 to 13, this calibration curve shows high linearity at least in the range of the phosphate ion concentration of 0 to 4 mg [P] / L.

(Test water preparation)
In addition to the same test waters C, E and L used in Examples 1-10, the following test waters T, U and V were prepared. In the preparation of each test water, the silicon standard solution neutralized by adding 1 M sulfuric acid was used because the silicon standard solution was alkaline.

Test water T:
2.5 mL of test water having a total phosphorus concentration of 3.00 mg [P] / L was prepared in the same manner as test water L, except that the silicon standard solution was further dissolved so that the silica concentration was 40 mg / L.

Test water U:
Except that the silicon standard solution was further dissolved so that the silica concentration was 50 mg / L, 2.5 mL of test water having a total phosphorus concentration of 2.00 mg [P] / L was prepared in the same manner as test water C.

Test water V:
2.5 mL of test water having a total phosphorus concentration of 2.00 mg [P] / L was prepared in the same manner as test water E, except that the silicon standard solution was further dissolved so that the silica concentration was 45 mg / L.

(Total phosphorus determination of test water)
To the test water shown in Table 6, 0.7 mL of 1M sulfuric acid and 0.5 mL of a peroxodisulfuric acid compound aqueous solution shown in Table 5 were added and heated at 95 ° C. for 30 minutes using a block heater. Next, with the test water heated to 95 ° C., 0.1 mL of a color former was added and left for 2 minutes. Further, 0.4 mL of a color former was added while the test water was heated to 95 ° C., and heating at the same temperature was continued for 18 minutes. The color former added here is the same as that used in preparing the calibration curve. Table 6 shows the time (color development start time) from when the color former is added a second time until the test water starts to develop color.

For the test water after completion of heating, the absorbance at the wavelengths shown in Table 6 was measured, and the total phosphorus concentration was quantified based on a calibration curve created from the measured values. The results are shown in Table 6.

The present invention can be implemented in various other forms without departing from the spirit or main features thereof. Therefore, the above-described embodiment or example is merely an example in all respects and should not be interpreted in a limited manner. The scope of the present invention is indicated by the scope of claims, and is not restricted to the text of the specification. Further, all modifications and changes belonging to the equivalent scope of the claims are within the scope of the present invention.

Claims

A method for quantifying the total phosphorus of the test water by decomposing the phosphorus compound contained in the test water and converting it into phosphate ions, and then quantifying the phosphate ion of the test water,
Adding an alkali metal salt of peroxodisulfuric acid or ammonium peroxodisulfate and sulfuric acid to the test water, and heating at a temperature from 65 ° C. to the boiling temperature of the test water for a predetermined time;
At least one hydroxyl group-containing compound selected from the group of hydroxyl group-containing compounds consisting of hydroxycarboxylic acids and alditol, vanadium compound having a vanadium valence of 3-5, aldose having 5 carbon atoms, for the test water having undergone step 1; A saccharide compound selected from the group of saccharide compounds consisting of aldoses having 6 carbons, ketoses having 6 carbons and aldoses having 5 carbons by decomposition, aldoses having 6 carbons or ketoses having 6 carbons, Adding an ammonium metal molybdate or an alkali metal salt of molybdate and an antimony compound having an antimony valence of 3, and heating at a temperature from 65 ° C. to the boiling temperature of the test water for a predetermined time;
Step 3 for measuring the absorbance of any wavelength in the range of 600 to 950 nm for the test water that has undergone Step 2;
For the determination of total phosphorus, including
The hydroxycarboxylic acids include citric acid, malic acid, aldaric acid, and aldonic acid, and the oligosaccharide includes sucrose, maltose, lactose, raffinose, kestose, stachyose, isomaltulose, maltulose, and lactulose. The method for quantifying total phosphorus as described in 1.
The quantification of total phosphorus according to claim 2, wherein the vanadium compound is selected from the group consisting of vanadium chloride (III), vanadium oxide sulfate (IV), sodium metavanadate (V) and vanadium oxide (V). Method.
In step 2, the hydroxyl group-containing compound, the vanadium compound, the saccharide compound, the hexammonium heptamolybdate or the alkali metal salt of molybdic acid and the antimony compound are added in two or more portions while providing an interval. 4. The method for quantifying total phosphorus according to any one of items 1 to 3.
A method for coloring phosphate ions contained in test water,
Step A for setting the inspection water to contain sulfuric acid;
At least one hydroxyl group-containing compound selected from the group of hydroxyl group-containing compounds consisting of hydroxycarboxylic acids and alditols, vanadium compounds having a vanadium valence of 3-5, aldoses having 5 carbon atoms, for the test water having undergone step A, A saccharide compound selected from the group of saccharide compounds consisting of aldoses having 6 carbons, ketoses having 6 carbons and aldoses having 5 carbons by decomposition, aldoses having 6 carbons or ketoses having 6 carbons, Adding an aqueous solution containing hexammonium molybdate or an alkali metal salt of molybdate and an antimony compound having an antimony valence of 3, and heating at a temperature from 65 ° C. to the boiling temperature of the test water for a predetermined time;
Method for coloring phosphate ions containing
The hydroxycarboxylic acids include citric acid, malic acid, aldaric acid, and aldonic acid, and the oligosaccharide includes sucrose, maltose, lactose, raffinose, kestose, stachyose, isomaltulose, maltulose, and lactulose. The method for coloring phosphate ions as described in 1.
7. The phosphate ion according to claim 6, wherein the vanadium compound is selected from the group consisting of vanadium chloride (III), vanadium oxide sulfate (IV), sodium metavanadate (V) and vanadium oxide (V). Coloring method.
In step A, an alkali metal salt of peroxodisulfuric acid or ammonium peroxodisulfate and sulfuric acid are added to the test water and heated at a temperature from 65 ° C. to the boiling temperature of the test water for a predetermined time. The method for coloring phosphate ions according to any one of claims 5 to 7, which is set to include.
9. In step B, the hydroxyl group-containing compound, the vanadium compound, the saccharide compound, the hexamolybdate hexammonium salt or the alkali metal salt of molybdic acid and the antimony compound are added in two or more portions at intervals. The method for coloring phosphate ions as described in 1.
A coloring agent for phosphate ions contained in test water,
At least one hydroxyl group-containing compound selected from the group of hydroxyl group-containing compounds consisting of hydroxycarboxylic acids and alditols, vanadium compounds having a vanadium valence of 3 to 5, aldoses having 5 carbon atoms, aldoses having 6 carbon atoms, 6 carbon atoms Saccharide compound selected from the group of saccharide compounds consisting of aldose having 5 carbon atoms, aldose having 6 carbon atoms or oligosaccharide capable of producing ketose having 6 carbon atoms by ketose and decomposition, hexaammonium heptamolybdate or alkali metal of molybdate A salt and an aqueous solution containing an antimony compound having an antimony valence of 3,
Phosphate ion coloring agent.
The hydroxycarboxylic acids include citric acid, malic acid, aldaric acid and aldonic acid, and the oligosaccharides include sucrose, maltose, lactose, raffinose, kestose, stachyose, isomaltulose, maltulose and lactulose. The color former of phosphate ion as described in 1.
The hydroxycarboxylic acids include citric acid, malic acid, aldaric acid, and aldonic acid, and the saccharide compound is a non-reducing oligosaccharide selected from the group consisting of sucrose, raffinose, kestose, and stachyose. The color former of phosphate ion as described in 1.
The vanadium compound is selected from the group consisting of vanadium (III) chloride, vanadium oxide (IV) sulfate, sodium metavanadate (V), and vanadium oxide (V). Phosphoric ion coloring agent.