JP6993855B2 - Flow injection analysis method and equipment - Google Patents

Description

The present invention relates to a flow injection analysis (FIA) method and apparatus.

Flow injection analysis is a flow injection analysis in which a continuous flow of liquid is formed in a thin tube, the sample solution is injected into it to cause a reaction with a reagent, and the concentration of reaction products is measured at the end of the tube. It is widely used for quantitative analysis of the target substance inside. The thin tube where the reaction takes place is generally called the reaction coil. For example, Patent Document 1 discloses that analysis by a colorimetric method using diacetylmonooxime is performed by flow injection analysis in order to continuously monitor a trace amount of urea concentration in a sample water.

The quantification by the colorimetric method using diacetylmonooxime is a well-known method for quantifying urea, and is described in, for example, a hygiene test method (Non-Patent Document 1). In the colorimetric method using diacetylmonooxime, other reagents (for example, antipyrine + sulfuric acid solution, semicarbazide hydrochloride aqueous solution, manganese chloride + potassium nitrate aqueous solution, sodium dihydrogen phosphate + sulfuric acid solution, etc.) are used for the purpose of promoting the reaction. Can be used together. When antipyrine is used in combination, diacetylmonooxime is dissolved in an acetic acid solution to prepare a diacetylmonooxime acetic acid solution, and antipyrine (1,5-dimethyl-2-phenyl-3-pyrazolone) is dissolved in, for example, sulfuric acid. An antipyrine-containing reagent solution is prepared, a diacetylmonooxime acetic acid solution and an anlipylin-containing reagent solution are sequentially mixed with sample water, the absorbance at a wavelength of around 460 nm is measured, and quantification is performed by comparison with a standard solution. The method for quantifying urea by the colorimetric method using diacetylmonooxime was originally intended for the quantification of urea in pool water or public bath water, for example, and is described in Patent Document 1 in this method. By measuring the absorbance by applying the flow injection analysis as described above, urea can be continuously quantified in a concentration range of ppb or less to several ppm.

Japanese Unexamined Patent Publication No. 2000-338099

Pharmaceutical Society of Japan, Hygiene Test Method, Commentary 1990.4.2.12.3 (13) 1 (1990 edition, 4th printing supplement (1995), p1028), 1995

When quantifying the target substance in the sample solution by flow injection analysis, stable quantification may not be possible. For example, when a small amount of urea is quantified in the sample water by the method described in Patent Document 1, the result is as if urea is contained in the sample water which is already known to be free of urea. May be obtained.

An object of the present invention is to provide a flow injection analysis method and apparatus for quantifying a target substance in a sample liquid, and to provide a method and an apparatus capable of stably quantifying the target substance.

As a detection means in flow injection analysis, it is widely practiced to measure the absorbance at a specific wavelength according to the reagent to be used and the target substance. The present inventors may interfere with the absorbance measurement due to the reaction of some interfering substance in the sample solution with the reagent to the absorbance measurement, and by treating the sample solution with an ion exchanger. We have found that it can be suppressed and completed the present invention.

Therefore, the flow injection analysis method of the present invention is a flow injection analysis method for continuously quantifying a target substance in a sample solution, in which the sample solution is passed through an ion exchanger and sent toward a reaction coil. A certain amount of the sample liquid that has passed through the ion exchanger is injected into the carrier liquid, and one or more reagents are added to the carrier liquid into which the sample liquid is injected to react with the target substance in the reaction coil. The target substance is quantified by measuring the absorbance of the liquid discharged from the reaction coil.

The flow injection analyzer of the present invention is a flow injection analyzer that continuously quantifies a target substance in a sample liquid, and includes a reaction coil to which a carrier liquid is supplied and an ion exchanger through which the sample liquid is passed. , A sampling valve that injects a certain amount of the sample liquid that has passed through the ion exchanger into the carrier liquid supplied to the reaction coil, and a carrier liquid into which the sample liquid is injected at a position between the sampling valve and the reaction coil. A means for adding the above-mentioned reagents and a detector for measuring the absorbance of the liquid discharged from the reaction coil are provided, and the target substance and one or more reagents are reacted in the reaction coil.

In the present invention, when the target substance in the sample liquid is continuously quantified by flow injection analysis, the sample liquid is passed through an ion exchanger, and then a certain amount of this sample liquid is injected into the carrier liquid, which is a normal method. The absorbance is measured and quantified according to the procedure of flow injection analysis. At this time, it is preferable to provide a filter at a position on the inlet side or the outlet side of the ion exchanger and perform a filter treatment for filtering out insoluble fine particles and the like in the sample liquid.

According to the present invention, when the target substance in the sample liquid is quantified by the flow injection analysis, the quantification can be stably performed.

It is a figure which shows the structure of the flow injection analyzer of one Embodiment of this invention. It is a graph which shows the relationship between the number of days of water flow and the peak intensity in Example 3. FIG.

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows the configuration of a flow injection analysis (FIA) apparatus according to an embodiment of the present invention. Here, raw water used for pure water production or pure water is used as a sample solution, and a small amount of urea contained in this sample solution (here, it can be said to be sample water because it is water) is continuously quantified online as a target substance. The present invention will be described by taking a case as an example. Of course, the target substance to be quantified in the present invention is not limited to urea, and the sample solution containing the target substance is not limited to water. The present invention can also be applied when quantifying in batch rather than continuously.

As shown in FIG. 1, a line 20 of raw water used for pure water production is provided, and in this line 20, raw water is sent by a pump P0. A sample water pipe 21 branching from the raw water line 20 is provided. The sample water pipe 21 is a pipe for sample water branched from raw water, and the tip of the sample water pipe 21 is connected to a sampling valve 10 (also referred to as an injector or an injection valve). Details of the sampling valve 10 will be described later.

The sample water pipe 21 is provided with a filter 51, an ion exchange device 50, an on-off valve 22, and a flow meter FI from the upstream side. The filter 51 removes insoluble particles contained in the sample water. The ion exchange device 50 has an ion exchanger arranged in a container, and is configured so that sample water passes through the ion exchanger. The ion exchanger provided in the ion exchange device 50 may be only an anion exchanger or only a cation exchanger, and further, an anion exchanger and a cation exchanger in a mixed bed or a double bed. May be. Here, the anion exchange body is, for example, at least one of a granular anion exchange resin, a monolithic anion exchange resin, and an anion exchange fiber. The cation exchanger is, for example, at least one of a granular cation exchange resin, a monolithic cation exchange resin, and a cation exchange fiber. As will be described later, in the FIA apparatus of this embodiment, the quantification is performed by measuring the absorbance, but the ion exchange apparatus 50 is contained in the sample water and interferes with the absorbance measurement for quantifying the target substance (here, urea). It is provided to remove any interfering substances from the sample water. Although the filter 51 is provided on the inlet side of the ion exchange device 50 in FIG. 1, the filter 50 may be provided on the outlet side of the ion exchange device 50, that is, between the ion exchange device 50 and the on-off valve 22.

As will be described later, the pump P4 is connected to the sampling valve 10, but the on-off valve 22 is always open and the pump P4 is constantly driven in order to continuously quantify urea. As a result, the sample water always flows through the sample water pipe 21.

Next, the sampling valve 10 will be described. The portion downstream from the sampling valve 10, including the sampling valve 10, has a configuration as an FIA apparatus and is actually a portion related to the determination of urea. The sampling valve 10 has a configuration generally used in the FIA method, and includes a hexagonal valve 11 and a sample loop 12. The six-way valve 11 includes six ports indicated by circled numbers in the illustration. The sample water pipe 21 is connected to the port 2. Further, a pipe 23 to which carrier water is supplied via the pump P1 is connected to the port 6, and a pipe 25 for draining the sample water via the pump P4 is connected to the port 3. A sample loop 12 for collecting a predetermined volume of sample water is connected between the port 1 and the port 4. One end of the pipe 24, which is the outlet of the sampling valve 11, is connected to the port 5. The carrier water is water that does not substantially contain urea, for example, pure water.

Assuming that the communication between the port X and the port Y in the hexagonal valve 11 is expressed as (XY), the hexagonal valve 11 is (1-2), (3-4), (5-6). The first state and the second state (2-3), (4-5), and (6-1) can be switched. In FIG. 1, the connection relationship between the ports in the first state is shown by a solid line, and the connection between the ports in the second state is shown by a dotted line. In the first state, the carrier water flows in the order of pipe 23 → port 6 → port 5 → pipe 24 and flows out from the sampling valve 10 to the downstream side. The sample water flows from the sample water pipe 21 → port 2 → port 1 → sample loop 12 → port 4 → port 3 and is discharged from the pipe 25. When the first state is switched to the second state, the sample water flows from the sample water pipe 21 → port 2 → port 3 and is discharged from the pipe 25, and the carrier water flows from the pipe 23 → port 6 → port. It flows in the order of 1 → sample loop 12 → port 4 → port 5 → piping 24, and flows out to the downstream side. At this time, the sample water that has already flowed in in the first state and fills the inside of the sample loop 12 flows from the port 5 to the pipe 24 prior to the carrier water and flows to the downstream side of the sampling valve 10. It flows. The volume of sample water flowing through the pipe 24 is defined by the sample loop 12. Therefore, by repeatedly switching between the first state and the second state (for example, by rotating the hexagonal valve 11 in the direction of the arrow in the figure), a predetermined volume of sample water can be repeatedly sent to the pipe 24. The switching between the first state and the second state can be performed at predetermined time intervals in consideration of the residence time required for the reaction described later and the time until urea is detected by the detector 32. It is also possible to detect that the sample water introduced into the detector 32 has been discharged from the detector 32 and perform switching. In this way, by automatically switching between the first state and the second state, urea can be continuously quantified.

In this device, the FIA method is applied to the quantification of urea by the colorimetric method using diacetylmonooxime. Therefore, as a reaction reagent used for the quantification of urea, a diacetylmonooxime acetic acid solution (hereinafter, also referred to as reagent A) and an antipyrine-containing reagent solution (hereinafter, also referred to as reagent B) are used. Here, a case where an antipyrine-containing reagent solution is used as a reagent used in combination with diacetylmonooxime will be described, but the reagent used in combination with diacetylmonooxime is not limited to the antipyrine-containing reagent solution. Reagents A and B are stored in storage tanks 41 and 42, respectively.

The present inventors prepared these reagents, and when they were kept at room temperature for a long period of time (for example, several days or more) for continuous quantification of urea, the peak intensity in the absorbance measurement decreased, and this peak. It has been found that the decrease in strength can be prevented by refrigerating the reagent (particularly reagent B). In order to perform stable quantification, it is preferable that the peak intensity in the absorbance measurement does not decrease. Therefore, in the FIA apparatus of the present embodiment, the storage tanks 41 and 42 are provided in the refrigerating section 40. Reagent A is prepared by dissolving diacetylmonooxime in an acetic acid solution, but when the refrigerating section 40 is provided, the preparation itself is performed in the storage tank 41, or reagent A is stored in the storage tank 41 after its preparation. do. Similarly, reagent B is prepared by dissolving antipyrine in, for example, sulfuric acid, but the preparation itself is performed in the storage tank 42, or reagent B is stored in the storage tank 42 after its preparation. The refrigerating section 40 shields the storage tanks 41 and 42 from light and cools the storage tanks 41 and 42, whereby the temperatures of the reagents A and B in the storage tanks 41 and 42 are kept at 20 ° C. or lower, preferably 3 ° C. or higher and 20 ° C. Hereinafter, it is more preferably maintained at 5 ° C. or higher and 15 ° C. or lower. The storage tank 41 for storing the reagent A does not necessarily have to be arranged in the refrigerating section 40 as long as it can be stored in a light-shielded manner. Even if the refrigerating temperature of the reagent is less than 5 ° C., it does not matter as long as crystals do not precipitate in the reagent. According to the hygiene test method (Non-Patent Document 1), an antipyrine sulfuric acid solution in which antipyrine is dissolved in sulfuric acid can be used for 2 to 3 months if it is stored in a brown bottle, and it is redissolved even if crystals are precipitated and returned to room temperature. Although it is stated that refrigerated storage is not suitable because it does not, the present inventors have confirmed by experiments that the antipyrine sulfuric acid solution prepared according to the hygiene test method does not crystallize even at 3 ° C.

One end of the pipe 26 is connected to the storage tank 41, and the other end of the pipe 26 is connected to the pipe 24 by the mixing portion 43. The pipe 26 is provided with a pump P2 for sending the reagent A to the pipe 24 at a predetermined flow rate. Similarly, one end of the pipe 27 is connected to the storage tank 42, and the other end of the pipe 27 is connected to the pipe 24 by the mixing portion 44. The pipe 27 is provided with a pump P3 for sending the reagent B to the pipe 24 at a predetermined flow rate. The mixing units 43 and 44 have a function of uniformly mixing the reagent A and the reagent B with respect to the flow of the liquid in the pipe 24, respectively. The other end of the pipe 24 is connected to the inlet of the reaction coil 31 provided in the reaction constant temperature bath 30. The reaction coil 31 causes a color reaction between urea and diacetylmonooxime in the presence of antipyrine, and its length and the flow velocity inside the reaction coil 31 are the residence time required for the reaction. It is appropriately selected according to the above. The reaction constant temperature bath 30 raises the temperature of the reaction coil 31 to a temperature suitable for the reaction. For example, the reaction coil 31 is heated to a temperature of 50 ° C. or higher and 150 ° C. or lower, preferably 90 ° C. or higher and 120 ° C. or lower. ..

At the end, that is, the outlet of the reaction coil 31, a detector 32 for measuring the absorbance of the color developed in the liquid by the color development reaction is provided for the liquid flowing out of the reaction coil 31. The detector 32 is used to determine, for example, the peak intensity or peak area of the absorbance at a wavelength of around 460 nm. By using the absorbance when the carrier water is flowing as the baseline and obtaining the calibration curve from the absorbance with respect to a standard solution having a known urea concentration, the concentration of urea in the sample water can be obtained from the absorbance with respect to the sample water. At the outlet of the detector 32, a back pressure coil 33 that applies back pressure to the pipeline from the pump P1 to the detector 32 via the sampling valve 10, the pipe 24, and the reaction coil 31 is provided. A pressure gauge PI is connected to a position between the outlet of the detector 32 and the inlet of the back pressure coil 33. The drainage of this FIA device flows out from the outlet of the back pressure coil 33.

In the apparatus of this embodiment, the FIA method is used, and urea in the sample water can be continuously measured online by a colorimetric method using diacetylmonooxime. At this time, by passing the sample water through the ion exchanger and then introducing it into the FIA apparatus, even if the sample water contains some substance that may affect the absorbance measurement by the detector 32, the substance is an ion. Since it is removed by the exchange device 50, continuous quantification of a trace amount of urea can be stably performed, as will be clarified from the examples described later. Further, as the reagent A (diacetylmonooxime acetic acid solution) and the reagent B (antipyrine-containing reagent solution) used for the reaction, particularly the reagent B, which was maintained at 20 ° C. or lower after the preparation of these reagents, was used. , It becomes possible to stably quantify urea for a long period of time.

Next, the results of experiments conducted by the inventors to show the effect of the present invention will be described.

(Example 1)
The FIA apparatus shown in FIG. 1 was assembled. However, the portion from the line 20 to the flow meter FI was not provided, and the sample water was directly supplied to the sampling valve 10. Separately from this, an ion exchange device filled with an ion exchange resin ESP-1 manufactured by Organo Corporation was separately provided. The ion exchange resin ESP-1 is a mixed bed ion exchange resin in which a strongly acidic cation exchange resin and a strong basic anion exchange resin are mixed at a volume ratio of 1: 1. In this example, 2 g of diacetylmonooxime is dissolved in 100 mL of 10% acetic acid to prepare reagent A (diacetylmonooxime acetic acid solution), 0.2 g of antipyrine is taken, and the total amount is 100 mL. Reagent B (anti-sulfuric acid-containing reagent solution) was prepared as a reagent B (reagent solution containing anti-sulfuric acid), and immediately after the preparation, those reagents were stored in the storage tanks 41 and 42, respectively, and each reagent was continuously supplied from the storage tanks 41 and 42 toward the pipe 24.

As the sample water, sample water A (raw water of an ultrapure water production device in a semiconductor factory) which is water containing urea and other impurities, and SV = 10 (L / L—h) for the above ion exchange device, that is, Water obtained by passing sample water A so that the flow rate per hour is 10 times the volume of the ion exchange resin (called ion exchange resin treated water), and further urea with respect to the ion exchange resin treated water. Water obtained by performing the decomposition treatment (urea decomposition treated water) was used. The urea decomposition treatment was carried out by adding 6 ppm of hypobromous acid as a urea decomposition agent to the ion exchange resin-treated water and reacting the mixture at a reaction temperature of 25 ° C. and a reaction time of 24 hours. Urea concentrations in each of these sample waters were measured using the assembled FIA device. When measuring the urea concentration, a standard solution of urea is supplied to the FIA device in advance, the absorbance is measured by the detector 32 to create a calibration curve, and the result of the absorbance measurement for each sample water is applied to the calibration curve to obtain the urea concentration. It was determined. The results are shown in Table 1.

（参考例１）
次亜臭素酸塩による尿素分解処理での尿素の分解率を検討するために、尿素を含まない純水に対して濃度が１０ｐｐｂとなるように尿素を添加して模擬水とし、さらに実施例１と同様にこの模擬水からイオン交換樹脂処理水と尿素分解処理水とを生成し、実施例１と同様に、模擬水、イオン交換樹脂処理水及び尿素分解処理水について尿素濃度の測定を行った。結果を表２に示す。

(Reference example 1)
In order to examine the decomposition rate of urea in the urea decomposition treatment with hypobromite, urea was added to pure water containing no urea so that the concentration was 10 ppb to prepare simulated water, and further, Example 1 Ion exchange resin treated water and urea decomposition treated water were generated from this simulated water in the same manner as in Example 1, and the urea concentrations of the simulated water, the ion exchange resin treated water and the urea decomposition treated water were measured in the same manner as in Example 1. .. The results are shown in Table 2.

尿素のみを含む模擬水とイオン交換樹脂処理水とでの尿素濃度の測定結果が一致していることから、イオン交換樹脂による処理では尿素は全く除去されないことがわかる。また、尿素分解処理水の結果から、次亜臭素酸を用いる尿素の分解処理により、尿素濃度が１ｐｐｂ未満（検出限界以下）となるまで尿素を除去できることがわかる。

Since the measurement results of the urea concentration in the simulated water containing only urea and the ion exchange resin treated water are in agreement, it can be seen that urea is not removed at all by the treatment with the ion exchange resin. Further, from the results of the urea decomposition treated water, it can be seen that urea can be removed by the urea decomposition treatment using hypobromous acid until the urea concentration becomes less than 1 ppb (below the detection limit).

(Comparative Example 1)
To the sample water A in Example 1, 6 ppm of hypobromous acid as a urea decomposition agent was added, and the mixture was reacted at a reaction temperature of 25 ° C. and a reaction time of 24 hours to perform a urea decomposition treatment, and then the urea decomposition treatment was performed. When the urea concentration was measured under the same conditions, the urea concentration after the urea decomposition treatment was measured to be 2.5 ppb.

From the results of Example 1, Reference Example 1 and Comparative Example 1 above, the difference between the urea concentration detected for the sample water A and the urea concentration detected for the ion exchange resin-treated water in Example 1 Is considered to be due to the contribution of some interfering substance that has absorption near the wavelength of 460 nm and interferes with the determination of urea by absorbance measurement. This means that, as shown in Reference Example 1, the urea concentration can be reduced to the detection lower limit or lower by the urea decomposition treatment, and the result of Comparative Example 1 shows the detection result only by the component other than urea, that is, the interfering substance. However, it is also supported by the fact that the result of Comparative Example 1 is equal to the difference in the detection result of the urea concentration between the sample water A and the ion exchange resin-treated water in Example 1 within the range of the measurement error. Urea. Therefore, from the results of Example 1, interfering substances that interfere with the absorbance measurement for quantification of urea are removed by treatment with an ion exchange resin, whereby the urea concentration measured for the ion exchange resin treated water is a sample. It can be seen that it represents the actual urea concentration for water A.

(Example 2)
As the ion exchange device in the apparatus used in Example 1, a strong basic anion exchange resin (Amberjet 4002OH manufactured by Organo Co., Ltd.) is filled alone (that is, a single bed), and a strong acid cation exchange resin (Amberjet manufactured by Organo Co., Ltd.) is filled. Three types were prepared: one filled with 1024H) alone and one filled with a mixed bed resin (ESP-1 manufactured by Organo Co., Ltd.) in which a strong acid cation exchange resin and a strong basic anion exchange resin were mixed. Then, as the sample water, sample water B (raw water of the ultrapure water production apparatus in the semiconductor factory) different from the sample water A was used. The water obtained by passing sample water B through an anion exchange resin is used as anion exchange resin-treated water, and the water obtained by passing sample water B through a cation exchange resin is used as cation exchange resin-treated water. The water obtained by passing B through the mixed bed resin is used as mixed bed resin treated water. The urea concentration was measured for each of the sample water B, the anion exchange resin treated water, the cation exchange resin treated water, and the mixed bed resin treated water in the same manner as in Example 1. The amount of liquid flowing through the ion exchange device was SV = 10 (L / L—h). The results are shown in Table 3.

実施例２からも、イオン交換樹脂による処理を用いることによって、波長４６０ｎｍ付近に吸収を有して吸光度測定による尿素の定量に妨害を与える妨害物質を除去できることがわかる。イオン交換樹脂として強塩基性カチオン交換樹脂を用いた場合には、強酸性アニオン交換樹脂や混床樹脂を用いる場合に比べて妨害物質の影響を受けやすい傾向にあり、試料水に対してイオン交換樹脂による処理を行う際に、イオン交換樹脂として少なくともアニオン交換樹脂を含むものを用いることが好ましいことがわかる。

From Example 2, it can be seen that by using the treatment with an ion exchange resin, an interfering substance having absorption near a wavelength of 460 nm and hindering the determination of urea by absorbance measurement can be removed. When a strongly basic cation exchange resin is used as the ion exchange resin, it tends to be more susceptible to interfering substances than when a strongly acidic anion exchange resin or mixed bed resin is used, and ion exchange with sample water. It can be seen that when the treatment with the resin is performed, it is preferable to use a resin containing at least an anion exchange resin as the ion exchange resin.

(Example 3)
Next, in order to demonstrate the effect of refrigerating the reagent, the apparatus shown in FIG. 1 was assembled. However, the part from the line 20 to the flow meter FI was not provided. Therefore, the ion exchange device 50 and the filter 51 are not provided.

A standard solution having a urea concentration of 60 ppb can be continuously supplied to the sampling valve 10 as sample water. Then, the urea concentration was continuously monitored for this standard solution. Here, it was investigated how the urea concentration obtained as the measured value of the detection peak of the absorbance in the detector 32 changes when the standard solution is continuously measured. In this Example 3, 2 g of diacetylmonooxime is dissolved in 100 mL of 10% acetic acid to prepare Reagent A (diacetylmonooxime acetic acid solution), 0.2 g of antipyrine is taken, and the total amount is 100 mL. Reagent B (anti-sulfuric acid-containing reagent solution) was prepared as a reagent B (reagent solution containing anti-sulfuric acid), and immediately after the preparation, those reagents were stored in the storage tanks 41 and 42, respectively, and each reagent was continuously supplied from the storage tanks 41 and 42 toward the pipe 24. After injecting each reagent into the storage tanks 41 and 42 at the beginning of the continuous measurement, the reagent was not replenished during the continuous measurement. Further, the storage tank 41 of the reagent A was maintained at room temperature. For Reagent B, experiments were conducted in two cases, one was when the storage temperature after preparation was 10 ° C and the other was when the storage temperature was 25 ° C. The change in urea concentration was confirmed by the peak intensity of absorbance at a wavelength of 460 nm. The results are shown in FIG. In FIG. 2, the measured values when the same standard solution is measured, with the peak intensity when measuring the urea standard solution of 60 ppb immediately after preparing the reagents A and B and storing them in the storage tanks 41 and 42, respectively, as 100%. Shows how has changed over time.

As shown in FIG. 2, when the antipyrine-containing reagent solution (reagent B) was maintained at 25 ° C., the peak intensity gradually decreased, and the peak intensity was 72% during the 10-day operation for continuous measurement. Has dropped to. That is, the quantification of urea could not be performed stably. On the other hand, it was found that when the antipyrine-containing reagent solution was stored in a refrigerator and maintained at 10 ° C., the peak intensity did not decrease even after 10 days of continuous operation, and the continuous quantification of urea could be stably performed over a long period of time. rice field.

(Example 4)
Reagent B (antipyrine-containing reagent solution) was prepared in the same manner as in Example 3, and then stored at 5 ° C., 10 ° C., 15 ° C., 20 ° C. and 25 ° C. for 10 days, respectively. Then, after this storage, the reagent B was supplied to the apparatus of Example 3. Immediately after supplying Reagent B to the device, a standard solution having a urea concentration of 60 ppb was measured using this device, and its peak intensity was determined. At that time, the peak intensity when the standard solution was measured immediately after the preparation of the reagent B was set to 100%. The reagent A (diacetylmonooxime acetic acid solution) was prepared in the same manner as in Example 3 and then stored at room temperature. The results are shown in Table 4.

表４に示されるように、保管温度が５℃の場合と１０℃の場合にはピーク強度の低下はほとんど見られず、１５℃で保管した場合には、約１割程度のピーク強度の低下が見られた。２０℃で保管した場合には約２割のピーク強度の低下であったが、２５℃では３割近くピーク強度が低下した。これらから、微量の尿素濃度を連続的に測定するためには、反応に用いる試薬（ジアセチルモノオキシム酢酸溶液及びアンチピリン含有試薬液）のうち少なくともアンチピリン含有試薬液を冷蔵保存すべきであること、その場合、アンチピリン含有試薬液の温度を２０℃以下に維持することが好ましく、３℃以上２０℃以下に維持することがさらに好ましく、５℃以上１５℃以下に維持することがより好ましいことが分かった。

As shown in Table 4, there is almost no decrease in peak intensity when the storage temperature is 5 ° C and 10 ° C, and when stored at 15 ° C, the peak intensity decreases by about 10%. It was observed. When stored at 20 ° C, the peak intensity decreased by about 20%, but at 25 ° C, the peak intensity decreased by nearly 30%. From these, in order to continuously measure a trace amount of urea concentration, at least the antipyrine-containing reagent solution among the reagents (diacetylmonooxime acetic acid solution and antipyrine-containing reagent solution) used for the reaction should be stored in a refrigerator. In this case, it was found that the temperature of the antipyrine-containing reagent solution is preferably maintained at 20 ° C. or lower, more preferably 3 ° C. or higher and 20 ° C. or lower, and more preferably 5 ° C. or higher and 15 ° C. or lower. ..

(Example 5)
The same test as in Example 4 was performed except that the reagent A (diacetylmonooxime acetic acid solution) of Example 4 was stored at the same storage temperature as the reagent B (antipyrine-containing reagent solution) of Example 4. ..

When both Reagent A and Reagent B were refrigerated for measurement, the same results as the results of refrigerating only Reagent B for measurement (Table 4) were obtained.

10 Sampling valve 11 Hexagonal valve 12 Sample loop 31 Reaction coil 32 Detector 33 Back pressure coil 40 Refrigerating section 41,42 Storage tank 43,44 Mixing section 50 Ion exchange device 51 Filter P0 to P4 Pump

Claims (6)

It is a flow injection analysis method that continuously quantifies the target substance in the sample liquid.
Pass the sample solution through the ion exchanger and
A certain amount of the sample liquid that has passed through the ion exchanger is injected into the carrier liquid that is being sent toward the reaction coil.
One or more reagents are added to the carrier liquid into which the sample liquid is injected to react with the target substance in the reaction coil.
The target substance is quantified by measuring the absorbance of the liquid discharged from the reaction coil .
The target substance is urea, the one or more reagents are a diacetylmonooxime-containing reagent solution and an antipyrine-containing reagent solution, and at least the antipyrine-containing reagent solution among the one or more reagents is 5 ° C. after preparation. A flow injection analysis method in which the reagent, which has been refrigerated so as to be maintained at a temperature of 15 ° C. or lower, is added to the carrier liquid into which the sample liquid has been injected . The flow injection analysis according to claim 1, wherein the sample liquid supplied to the ion exchanger or the sample liquid after passing through the ion exchanger and before being injected into the carrier liquid is filtered. Method. The flow injection analysis method according to claim 1 or 2 , wherein the ion exchanger contains at least one of a granular anion exchange resin, a monolithic anion exchange resin, and an anion exchange fiber. A flow injection analyzer that quantifies the target substance in the sample liquid.
A reaction coil to which the carrier liquid is continuously supplied, and
An ion exchanger through which the sample liquid is passed and
A sampling valve that injects a certain amount of the sample liquid that has passed through the ion exchanger into the carrier liquid supplied to the reaction coil.
An addition means for adding one or more reagents to the carrier liquid into which the sample liquid is injected at a position between the sampling valve and the reaction coil.
A detector that measures the absorbance of the liquid discharged from the reaction coil,
The one or more reagents are a diacetylmonooxime-containing reagent solution and an antipyrine-containing reagent solution, and a storage tank for storing at least the antipyrine-containing reagent solution among the one or more reagents prepared and supplied to the addition means. ,
A cooling means for cooling the storage tank for storing the antipyrine-containing reagent solution so as to maintain the temperature at 5 ° C. or higher and 15 ° C. or lower.
Equipped with
A flow injection analyzer that reacts the target substance with the one or more reagents in the reaction coil. The flow injection analyzer according to claim 4 , further comprising a filter in at least one of a pipe connecting to the inlet of the ion exchanger and a pipe connecting the outlet of the ion exchanger and the sampling valve. The flow injection analyzer according to claim 4 or 5 , wherein the ion exchanger contains at least one of a granular anion exchange resin, a monolithic anion exchange resin, and an anion exchange fiber.

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