JP2012042450A - Quantitative method of total phosphorus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To safely quantitate total phosphorus of inspection water in short time.SOLUTION: In the method for quantitating the total phosphorus of the inspection water by decomposing a phosphorus compound contained in the inspection water to be converted into phosphate ions and quantitating the phosphate ions of the inspection water, alkali metal salt of peroxodisulfate and sulfuric acid are added to the inspection water, and heated for predetermined time at temperature from 65°C to boiling temperature. Then, a coloring agent containing at least one hydroxyl group-containing compound selected from a hydroxyl group-containing compound consisting of hydroxycarboxylic acids and alditol, a saccharide compound selected from a saccharide compound group consisting of aldose of carbon number 5, aldose of carbon number 6, ketose of carbon number 6 and a monosaccharide generation compound capable of generating one of the monosaccharides by decomposition and hexaammonium heptamolybdate is added to the inspection water to be heated for predetermined time at 65°C or higher, and after that, absorbance of arbitrary wavelength within a range from 600 to 950 nm is measured for the inspection water.

Description

  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 method for quantifying 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 produced by reacting phosphate ions contained in water with hexaammonium heptamolybdate and potassium antimonyl tartrate (dipotassium bis [(+)-tartrate] antimony (III)) is produced. Phosphate ions are quantified by measuring the absorbance of the 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 then 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 the test water is calculated based on a calibration curve prepared in advance from the measured value.

  The pretreatment of the test water in such a total phosphorus quantification method requires the use of a high-pressure steam sterilizer, that is, a pressure-resistant container, which complicates the operation and requires special safety. 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 in which potassium peroxodisulfate is added to test water and then treated at 100 ° C. for 60 minutes. 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 to 40 ° C. to suppress the oxidative action 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.

  In addition, as described in Non-Patent Document 1, the above-described method for quantifying total phosphorus is a trace amount range of 1.25 to 25 μg, so that the test water contains a relatively large amount of phosphate ions and phosphorus compounds. If the test water contains silica such as silicon dioxide, silicic acid and silicate, the quantitative results may vary under the influence of silica and lack reliability. is there.

Japanese Industrial Standard JIS K 0102, Factory Wastewater Test Method (2008) 46.1.1 and 46.3

2002 Ministry of the Environment contract work result report, water quality analysis method study investigation, pages 5 and 13

  An object of the present invention is to enable the total phosphorus of test water to be quantified 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 alditol, aldose having 5 carbon atoms, aldose having 6 carbon atoms, ketose having 6 carbon atoms and 5 carbon atoms due to decomposition From saccharide compounds consisting of monosaccharide producing compounds capable of producing aldoses of 6 carbon atoms, aldoses of 6 carbon atoms or ketoses of 6 carbon atoms Step 2 in which a coloring agent containing a saccharide compound and hexammonium heptamolybdate or an alkali metal salt of molybdic acid is added and heated for a predetermined time at a temperature from 65 ° C. to the boiling temperature of the inspection water, and the inspection through Step 2 And step 3 for measuring the absorbance of water at an arbitrary wavelength in the range of 600 to 950 nm.

  In this quantitative method, in step 2, the color former 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, aldoses having 5 carbon atoms, aldoses having 6 carbon atoms, ketoses having 6 carbon atoms and aldoses having 5 carbon atoms by decomposition, Add a color former containing a saccharide compound selected from the group of saccharide compounds consisting of aldoses having 6 carbon atoms or monosaccharide producing compounds capable of producing ketose having 6 carbon atoms and hexaammonium heptamolybdate or an alkali metal salt of molybdate. And B for heating for a predetermined time at a temperature from 65 ° C. to the boiling temperature of the inspection water.

  In this color development method, in step B, the color former can be added in two or more steps while providing an interval.

  The test water to which this color development method can be applied contains, for example, a phosphorus compound. In this case, in step A, an alkali metal salt of peroxodisulfuric acid or ammonium peroxodisulfate and sulfuric acid is added to the test water and the test is started from 65 ° C. By heating for a predetermined time at a temperature up to the boiling temperature of water, the phosphorus compound is decomposed and converted into phosphate ions.

  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, aldoses having 5 carbon atoms, aldoses having 6 carbon atoms, ketoses having 6 carbon atoms and monosaccharide-producing compounds capable of producing aldoses having 5 carbon atoms, aldoses having 6 carbon atoms or ketoses having 6 carbon atoms by decomposition It consists of an aqueous solution containing a saccharide compound selected from the group of saccharide compounds and an alkali metal salt of hexaammonium heptamolybdate or molybdic acid.

  The color former used in the quantification method and color development method according to the present invention and the color former of the present invention may further contain an antimony compound having an antimony valence of 3. Further, the hydroxycarboxylic acids used in these color formers include, for example, citric acid, malic acid, aldaric acid and aldonic acid. The monosaccharide-generating compound is, for example, an oligosaccharide selected from the group consisting of sucrose, maltose, lactose, raffinose, kestose, stachyose, isomaltulose, maltulose and lactulose. 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.

  Since the method for quantifying total phosphorus according to the present invention includes the above-described steps 1 to 3, the total phosphorus in the test water can be quantified safely in a short time.

  In the method for coloring phosphate ions according to the present invention, since a color former containing a predetermined component is used, phosphate ions contained in test water can be colored safely in a short time.

  Furthermore, since the color former according to the present invention 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.

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 figure which shows the calibration curve created in Example 14. The figure which shows the calibration curve created in Example 15. The figure which shows the calibration curve created in Example 16.

  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 of the test water, a predetermined amount of the test water is collected, and a pretreatment is performed 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. For this reason, it is preferable to set the concentration of the peroxodisulfuric acid compound in the test water so that the concentration when the aqueous peroxodisulfate compound solution and sulfuric acid are added to the test water is usually 0.5 to 9 g / L. 1 to 6 g / L is more preferable.

  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 to be 1 to 0.3M.

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

  Next, a color former is added to the inspection water that has undergone step 1 and then 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. The color former used here contains a hydroxyl group-containing compound, a saccharide compound and a molybdenum compound.

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). Aldaric used _herein, HO 2 C- (CHOH) formula n-CO ₂ H (n is an integer of 1 or more, preferably an integer of 1 to 5) was in a water-soluble compound represented by the Examples thereof include tartaric acid having n of 2 and mucoic acid having n of 4. Table Further, aldonic acids used _herein, HO 2 C- (CHOH) formula _n-CH 2 OH (n is an integer of 1 or more, preferably an integer of 1 to 5, more preferably 4 or 5) in 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 of 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 saccharide compounds, aldoses having 5 carbon atoms, aldoses having 6 carbon atoms, ketoses having 6 carbon atoms, and aldoses having 5 carbon atoms, aldoses having 6 carbon atoms, or ketoses having 6 carbon atoms by decomposition can be produced. Those selected from the group of saccharide compounds consisting of 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.

  As the monosaccharide-generating compound, an oligosaccharide or a glycoside capable of generating an aldose having 5 carbon atoms, an aldose having 6 carbon atoms, or a ketose having 6 carbon atoms by decomposition is used. Examples of oligosaccharides include disaccharides sucrose, maltose, lactose, isomaltulose, maltulose, lactulose, galactosucrose, primeverose and vicyanose, trisaccharides raffinose, kestose, gentianose, planteose and umbelliferose, tetrasaccharides Mention may be made of stachyose and pentasaccharide Belvas course. 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. Examples of glycosides include arbutin and salicin. These exemplary glycosides can produce glucose by degradation.

  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.

  In this step, the color former is usually added to the inspection water as an aqueous solution in which a hydroxyl group-containing compound, a saccharide compound and a molybdenum compound are dissolved in purified water. The color former composed of such an aqueous solution can be added to the inspection water in various forms. The first form of an example of the color former is an aqueous solution containing simultaneously a hydroxyl group-containing compound, a saccharide compound and a molybdenum compound in purified water. The 2nd form of the example of a color former consists of each aqueous solution of a hydroxyl-containing compound, a saccharide compound, and a molybdenum compound. The third form of the color former includes a first aqueous solution containing a saccharide compound and a second aqueous solution containing a hydroxyl group-containing compound and a molybdenum compound at the same time. Here, since each aqueous solution of the second and third forms is stable, it can be prepared and stored in advance, and can be used as needed when necessary.

  The color former of the first form can be used by adding it to the test water as it is, but it is usually preferable to prepare it immediately before the addition to the test water in order to ensure the stability of each component. It can be prepared by using the storable color former of the second form or the third form and mixing each of the aqueous solutions immediately before addition to the test water. The color formers of the second form and the third form can be used by adding each of the aqueous solutions separately to the test water, but by mixing each aqueous solution immediately before the addition to the test water, One form of color former can also be added to the test water.

  The color former is preferably of the first form because phosphate ions can be more stably colored in test water.

  When the non-reducing oligosaccharide capable of producing a aldose having 5 carbon atoms, an aldose having 6 carbon atoms, or a ketose having 6 carbon atoms is used as a saccharide compound by decomposition, the color former of the first form contains the oligosaccharide and hydroxyl group A compound prepared by simultaneously dissolving a compound and a molybdenum compound in purified water is preferable. Such a color former of the first form can be stably stored for a long period of time because the reaction between the solutes does not substantially react, so it can be prepared in advance and used when necessary. 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).

  The color former may further contain an antimony compound. In this case, in the coloration of phosphate ions, which will be described later, the intensity thereof may be increased, so that the quantitative accuracy of the amount of phosphate ions in test water, that is, the amount of total phosphorus may be increased. 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.

  An antimony compound having an antimony valence of 5 can also be used as the antimony compound. 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.

  The antimony compound can be added to the inspection water as an aqueous solution dissolved in purified water like the other components for the color former, and is used in the color former in any of the first, second and third forms. be able to. The storable color former of the first form using non-reducing oligosaccharides should be stored stably for a long time because the reaction between the solutes does not substantially proceed even when the antimony compound is contained. Can do. When an antimony compound is used in the color former of the third form, the antimony compound is preferably included in the second aqueous solution because it may impair the storage stability of the aqueous solution. Even when the second aqueous solution contains an antimony compound, it can be stably stored.

  In the color former, when an alkaline earth metal salt of molybdic acid is used as the molybdenum compound, an appropriate amount is used in order to promote dissolution of the alkaline earth metal salt of molybdate during the preparation of the various aqueous solutions described above for the color former. Sulfuric acid or hydrochloric acid can be added. 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 for the color former.

  In this step, phosphate ions originally contained in the test water and phosphate ions generated by oxidative decomposition of the phosphorus compound in step 1 react with the added molybdenum 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. Further, when the saccharide compound is a monosaccharide-generating compound, the heteropoly compound is reduced by the aldose having 5 carbon atoms, the aldose having 6 carbon atoms, or the ketose having 6 carbon atoms generated by the decomposition. In this case, when the monosaccharide-producing compound is a reducing oligosaccharide, such as maltose, lactose, isomaltulose, maltulose, lactulose, and primeverose, the heteropoly compound produced by the reducing oligosaccharide itself is reduced. obtain. 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 rapidly 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 a monosaccharide-generating compound, the remaining peroxodisulfuric acid compound is decomposed by the aldose having 5 carbon atoms, the aldose having 6 carbon atoms, or the ketose having 6 carbon atoms produced by the decomposition of the monosaccharide-generating compound. Disappears. When the monosaccharide-generating compound is an oligosaccharide, the remaining peroxodisulfate 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 test water reacts with a molybdenum compound, produces | generates a heteropoly compound stably, and can color by the production | generation of 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. 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.

  In this step, the color former added to the inspection water is the concentration of each component in each aqueous solution and the inspection of each aqueous solution so that the concentration of each component in the inspection water at the time of addition of the color former to the inspection water is as follows: It is preferable to adjust the amount added to water.

  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 viewpoint, 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 saccharide compound in the test water (the concentration at the time of addition, and when a monosaccharide-generating compound is used, the concentration of aldose having 5 carbon atoms, aldose having 6 carbon atoms, or ketose having 6 carbon atoms produced by decomposition) is It is preferable to set the concentration to be sufficient for reducing the peroxodisulfuric acid compound remaining in the test water and sufficiently reducing the produced heteropoly compound. From this viewpoint, the concentration of the saccharide compound in the inspection 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. Moreover, when using an antimony compound, the concentration of the antimony compound in the test water (concentration at the time of addition, and when using a hydrate, the converted concentration excluding water molecules) is usually 0.01 to 0.24 g. / L is preferably set, and more preferably 0.02 to 0.13 g / L. However, in the test water, the concentration ratio (A: B) between the antimony compound (A) and the molybdenum compound (B) is preferably set to 1: 8 to 100, and preferably 1:10 to 50. It is more preferable to set.

  In this step, the color former 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 the color former to be added to the test water can be added, and the remainder of the total amount of the color former can be added when a predetermined time has elapsed. Usually, the predetermined time of the divided addition interval is 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 contact of the molybdenum compound 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, it is preferable to add 20% of the total amount of the color former at the first addition and add the remaining 80% of the color former 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, although the heating time of the inspection water in this process (when the color former is added in a divided manner as described above, the heating time after the last addition) varies depending on the heating temperature, the coloration of phosphate ions is completed. It is enough time. This time can be normally set to a short time of about 5 to 30 minutes because the influence of chlorine derived from chloride ions contained in the inspection water is excluded.

  The above steps 1 and 2 can be operated 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 allowing it to cool when the process 1 is shifted from the process 1 to the process 2, the test water after the completion of the process 1 can be transferred to the process 2 smoothly and quickly. It can be completed in a short time.

  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 the color former used in step 2 is of the first form (provided that a non-reducing oligosaccharide is used as the saccharide compound), the color former is a component required for the test water only by its addition. Can be added at the same time 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 addition, when the phosphate ion derived from the phosphorus compound is colored with respect to the test water containing the phosphorus compound, the phosphorous compound is converted into the phosphate ion by applying Step 1 of the quantification method of the present invention, and the test is performed. It can also be set so that the water contains sulfuric acid.

  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 executed by applying the process 1 of the present invention to the test water, in the process B, as in the process 2 of the quantification method of the present invention, the color former is used twice or more. It is preferable to divide and add to the inspection water while providing separate intervals.

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
1M sulfuric acid (for volumetric analysis): Wako Pure Chemical Industries, Ltd. Code 198-09595
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
Hexammonium hexamolybdate tetrahydrate (special reagent grade): 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 antimony tartrate trihydrate (special grade reagent): Wako Pure Chemical Industries, Ltd. Code 020-12832
Antimony oxide (III) (chemical use): Wako Pure Chemical Industries, Ltd. Code 018-04402
Antimony (III) chloride (reagent special 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 class code 056-00242 from Wako Pure Chemical Industries, Ltd.
Xylitol: Wako Special Code 244-00542 from Wako Pure Chemical Industries, Ltd.
Sorbitol: Wako first grade code 194-03752 from Wako Pure Chemical Industries, Ltd.
D-fructose: Wako special grade code 127-02765 of Wako Pure Chemical Industries, Ltd.
D-arabinose: Wako Special Code 013-04572 from Wako Pure Chemical Industries, Ltd.
D-glucose (special reagent grade): Wako Pure Chemical Industries, Ltd. Code 047-100592
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): Wako Pure Chemical Industries, Ltd. Code 128-00095
D-galactose (reagent special grade): 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 196-12864
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 Special Grade Code 044-04262 from Wako Pure Chemical Industries, Ltd.
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. 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 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:
An 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 oxidant aqueous solutions 1 to 6 was added to 5 mL of each of the sample waters 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) spectrophotometric 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 into phosphate ions by oxidative degradation among the phosphorous 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. D-glucose used for the preparation of the sample waters 5 and 6 is assumed to be 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 a concentration of 1 mg adenosine-5'-triphosphate. [P] / L, phenyl disodium phosphate concentration adjusted to 1 mg [P] / L, and D-glucose concentration 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 5 mL of each sample water, 0.8 mL of a 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 was added to each sample water after cooling to dilute it twice, and in the same manner as in Experimental Example 1, according to molybdenum blue (ascorbic acid reduction) spectrophotometric method described in 46.1.1 of JIS K 0102 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) Adenosine-5′-triphosphate disodium trihydrate in distilled water so that the concentration of D-glucose (assuming organic substances as impurities) is 20 mg / L and the silica concentration is 100 mg [Si] / L Product, disodium phenyl phosphate dihydrate, D-glucose and silicon 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.

  To sample water 7, 1.4 mL of 1M sulfuric acid and 1.0 mL of potassium peroxodisulfate having a concentration of 30 g / L were added and heated at 95 ° C. for 40 minutes using a block heater. Subsequently, 1.0 mL of a color former was added while the sample water 7 was heated to 95 ° C., and left for 22 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.

  It was 1.49 when the light absorbency of 830 nm was measured about the sample water 7 after completion | finish of a heating. The absorbance of the same wavelength was measured for the sample water 8 treated in the same manner, and it was 0.99. Since the sample water 7 containing silica has an absorbance about 1.5 times that of the sample water 8 not containing silica, the measurement result of total phosphorus is greatly affected by silica.

Examples 1-12
(Create a calibration curve)
Table 3 shows that 1 mL of sulfuric acid is 1.4 mL for 5 mL of each of the five types of phosphate ion solutions having phosphate ion concentrations of 0, 1.0, 2.0, 3.0, and 4.0 mg [P] / L. The peroxodisulfuric acid compound aqueous solution 1.0mL shown was added, and it heated at 95 degreeC for 30 minute (s) using the block heater.

  Next, the state heated to 95 ° C. was maintained, and 1.0 mL of a color former was added and left for 22 minutes. The color former used here was prepared by dissolving the components shown in Table 3 in distilled water so as to have the concentrations shown in the same table.

  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. 1 to 12, 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)
The following test water was prepared.
Test water A:
Adenosine-5′-triphosphate disodium trihydrate concentration is 65 mg / L (1.00 mg [P] / L), phenyl disodium phosphate dihydrate concentration is 82 mg / L (1.00 mg [P ] / L), D-glucose (assuming organic matter as a contaminant) in distilled water to a concentration of 20 mg / L, adenosine-5'-disodium triphosphate trihydrate, phenyl diphosphate Sodium dihydrate and D-glucose were dissolved, and 5 mL of test water having a total phosphorus concentration of 2.00 mg [P] / L was prepared.

Test water B:
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, except that the silicon standard solution was further dissolved so that the silica concentration was 90 mg / L. In the preparation of the test water, a silicon standard solution neutralized by adding 1 M sulfuric acid was used because the silicon standard solution was alkaline.

Test water C:
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 B, except that the silicon standard solution was dissolved so that the silica concentration was 60 mg / L.

Test water D:
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 B, except that the silicon standard solution was dissolved so that the silica concentration was 50 mg / L.

Test water E:
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 B, except that the silicon standard solution was dissolved so that the silica concentration was 70 mg / L.

Test water F:
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), D-glucose (assuming organic substances as impurities) in distilled water to a concentration of 20 mg / L, adenosine-5′-triphosphate disodium trihydrate, phosphoric acid Dissolve phenyl disodium dihydrate and D-glucose, and prepare 5 mL of test water having a total phosphorus concentration of 3.00 mg [P] / L.

Test water G:
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 F, except that the silicon standard solution was further dissolved so that the silica concentration was 80 mg / L. In the preparation of the test water, a silicon standard solution neutralized by adding 1 M sulfuric acid was used because the silicon standard solution was alkaline.

Test water H:
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 G, except that the silicon standard solution was further dissolved so that the silica concentration became 70 mg / L.

Test water I:
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 G, except that the silicon standard solution was further dissolved so that the silica concentration was 50 mg / L.

Test water J:
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), D-glucose (assuming organic substances as impurities) in distilled water to a concentration of 20 mg / L, adenosine-5′-triphosphate disodium trihydrate, phosphoric acid Dissolve phenyl disodium dihydrate and D-glucose, and prepare 5 mL of test water having a total phosphorus concentration of 1.00 mg [P] / L.

Test water K:
5 mL of test water having a total phosphorus concentration of 1.00 mg [P] / L was prepared in the same manner as test water J, except that the silicon standard solution was further dissolved so that the silica concentration was 60 mg / L. In the preparation of the test water, a silicon standard solution neutralized by adding 1 M sulfuric acid was used because the silicon standard solution was alkaline.

Test water L:
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), D-glucose (assuming organic matter as a contaminant) in distilled water to a concentration of 20 mg / L, adenosine-5'-disodium triphosphate trihydrate, phenyl diphosphate Sodium dihydrate and D-glucose were dissolved, and 5 mL of test water having a total phosphorus concentration of 4.00 mg [P] / L was prepared.

Test water M:
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 L, except that the silicon standard solution was further dissolved so that the silica concentration was 100 mg / L. In the preparation of the test water, a silicon standard solution neutralized by adding 1 M sulfuric acid was used because the silicon standard solution was alkaline.

(Total phosphorus determination of test water)
To the test water shown in Table 4, 1.4 mL of 1M sulfuric acid and 1.0 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., 1.0 mL of a color former (the same as that used for preparing the calibration curve) was added and left for 22 minutes.

  About the test water after completion | finish of a heating, the light absorbency of the wavelength shown in Table 4 was measured, and the total phosphorus density | concentration was quantified based on the analytical curve created from the measured value. The results are shown in Table 4.

Examples 13-16
(Create a calibration curve)
Table 5 shows 1 mL of 1M sulfuric acid for 5 mL of each of the five types of phosphate ion solutions having phosphate ion concentrations of 0, 1.0, 2.0, 3.0, and 4.0 mg [P] / L. The peroxodisulfuric acid compound aqueous solution 1.0mL shown was added, and it heated at 95 degreeC for 30 minute (s) using the block heater.

  Next, the state heated to 95 ° C. was maintained, 0.2 mL of color former was added, and the mixture was allowed to stand for 2 minutes. Subsequently, 0.8 mL of a color former was further added while maintaining the state heated to 95 ° C., and left for 20 minutes. The color former used here was prepared by dissolving the components shown in Table 5 in distilled water so as to have the concentrations shown in the same table.

  For each phosphate ion solution treated as described above, the absorbance at the wavelengths shown in Table 6 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. 13 to 16, 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)
In addition to the same test waters A, B, F and G used in Examples 1-12, the following test waters were prepared.
Test water N:
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, except that the silicon standard solution was further dissolved so that the silica concentration was 100 mg / L. In the preparation of the test water, a silicon standard solution neutralized by adding 1 M sulfuric acid was used because the silicon standard solution was alkaline.

(Total phosphorus determination of test water)
To the test water shown in Table 6, 1.4 mL of 1M sulfuric acid and 1.0 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., 0.2 mL of a color former was added and left for 2 minutes. Further, 0.8 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 20 minutes. The color former added here is the same as that used in preparing the calibration curve.

  About the test water after completion | finish of a heating, the light absorbency of the wavelength shown in Table 6 was measured, and the total phosphorus density | concentration was quantified based on the analytical curve created from the measured value. The results are shown in Table 6.

Claims (13)

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 alditols, aldose having 5 carbon atoms, aldose having 6 carbon atoms, ketose having 6 carbon atoms and Saccharide compounds selected from the group of saccharide compounds consisting of monosaccharide-producing compounds capable of producing aldoses having 5 carbon atoms, aldoses having 6 carbon atoms or ketoses having 6 carbon atoms by decomposition, and alkali metals such as hexaammonium heptamolybdate or molybdate Adding a color former containing salt, and heating at a temperature from 65 ° C. to the boiling temperature of the test water for a predetermined time; and
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 method for determining total phosphorus according to claim 1, wherein the color former further comprises an antimony compound having an antimony valence of 3.   3. The method for quantifying total phosphorus according to claim 1 or 2, wherein in step 2, the color former is added in two or more steps while providing an interval.   The hydroxycarboxylic acids include citric acid, malic acid, aldaric acid and aldonic acid, and the monosaccharide-forming compound is selected from the group consisting of sucrose, maltose, lactose, raffinose, kestose, stachyose, isomaltulose, maltulose and lactulose. The method for quantifying total phosphorus according to any one of claims 1 to 3, which is a selected oligosaccharide. 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, aldose having 5 carbon atoms, aldose having 6 carbon atoms, ketose having 6 carbon atoms and Saccharide compounds selected from the group of saccharide compounds consisting of monosaccharide-producing compounds capable of producing aldoses having 5 carbon atoms, aldoses having 6 carbon atoms or ketoses having 6 carbon atoms by decomposition, and alkali metals such as hexaammonium heptamolybdate or molybdate Adding a color former containing salt, and heating for a predetermined time at a temperature from 65 ° C. to the boiling temperature of the test water; and
Method for coloring phosphate ions containing   The method of claim 5, wherein the color former further comprises an antimony compound having an antimony valence of 3.   The method of coloring a phosphate ion according to claim 5 or 6, wherein, in step B, the color former is added in two or more steps with an interval provided.   The test water contains a phosphorus compound, and in step A, an alkali metal salt of peroxodisulfuric acid or ammonium peroxodisulfate and sulfuric acid are added to the test water and the temperature is 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, wherein the phosphorus compound is decomposed by heating to be converted into phosphate ions.   The hydroxycarboxylic acids include citric acid, malic acid, aldaric acid and aldonic acid, and the monosaccharide-producing compound is selected from the group consisting of sucrose, maltose, lactose, raffinose, kestose, stachyose, isomaltulose, maltulose and lactulose. The method for coloring phosphate ions according to claim 5, which is a selected oligosaccharide. 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, aldoses having 5 carbon atoms, aldoses having 6 carbon atoms, ketoses having 6 carbon atoms and aldoses having 5 carbon atoms by decomposition, carbon numbers A saccharide compound selected from the group of saccharide compounds consisting of aldoses of 6 or monosaccharide-producing compounds capable of producing ketoses of 6 carbon atoms and an aqueous solution containing hexaammonium heptamolybdate or an alkali metal salt of molybdic acid,
Phosphate ion coloring agent.   The color developer for phosphate ions according to claim 10, wherein the aqueous solution further contains an antimony compound having an antimony valence of 3.   The hydroxycarboxylic acids include citric acid, malic acid, aldaric acid and aldonic acid, and the monosaccharide-producing compound is selected from the group consisting of sucrose, maltose, lactose, raffinose, kestose, stachyose, isomaltulose, maltulose and lactulose. The color former of phosphate ion according to claim 10 or 11, which is a selected oligosaccharide.   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. Or a phosphate ion coloring agent according to 11;

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