JP2019095409A - Flow injection analysis method and device - Google Patents

Abstract

To enable a target substance to be quantitated stably when quantitating a target substance in a sample liquid by flow injection analysis.SOLUTION: In a flow injection analysis method for continuously quantitating a target substance in a sample liquid, the sample liquid is passed through an ion exchanger, a given amount of the sample liquid having passed through the ion exchanger is injected into a carrier liquid being conveyed toward a reaction coil, one or more reagents are added to the carrier liquid having had the sample liquid injected thereinto and reacting it with the target substance in the reaction coil, and the target substance is quantitated by measuring the absorbance of a liquid discharged from the reaction coil.SELECTED DRAWING: Figure 1

Description

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

  Flow injection analysis is used to form a continuous stream of liquid in a thin tube, inject a sample solution into it to cause a reaction with the reagent, and measure the reaction product concentration etc. at the end of the tube. It is widely used for the quantitative analysis of the target substance in it. The thin tube where the reaction takes place is generally referred to as the reaction coil. For example, Patent Document 1 discloses that flow analysis is performed by colorimetric analysis with diacetyl monoxime to continuously monitor a trace amount of urea concentration in sample water.

  The determination by colorimetric method using diacetyl monoxime is well known as a method of determining urea, and is described, for example, in the Sanitary Test Method (Non-patent Document 1). In the colorimetric method using diacetyl monoxime, other reagents (for example, antipyrine + sulfuric acid solution, aqueous solution of semicarbazide hydrochloride, aqueous solution of manganese chloride + potassium nitrate, sodium dihydrogen phosphate + sulfuric acid solution, etc.) for the purpose of accelerating the reaction. Can be used together. When antipyrine is used in combination, diacetyl monooxime is dissolved in an acetic acid solution to prepare a diacetyl monoximetic 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 diacetyl monoximetic acetic acid solution and an anpyriline-containing reagent solution are sequentially mixed with sample water, absorbance at a wavelength of about 460 nm is measured, and quantification is performed using a control with a standard solution. The method of quantitative determination of urea by the colorimetric method using diacetyl monoxime is originally intended for the determination of urea in, for example, pool water or public bath water, but this method is described in Patent Document 1 As a result, by applying flow injection analysis to measure absorbance, urea can be quantified continuously in the concentration range of ppb or less to several ppm.

JP, 2000-338099, A

Japan Pharmaceutical Association, Hygienic Test Act, Commentary 1990.4.1.2.3 (13) 1 (1990 Edition 4th Printing Supplement (1995), p1028), 1995

  When quantifying the target substance in the sample solution by flow injection analysis, it may not be possible to perform stable quantification. For example, when quantifying a trace amount of urea in sample water by the method described in Patent Document 1, the result is as if urea is contained in the sample water already known not to contain urea. It 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 solution, which can stably quantify 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 have found that some interfering substances in the sample solution may react with the reagent and the components formed may interfere with the absorbance measurement, and treating the sample solution with the ion exchanger interferes with the absorbance measurement. They found that they could 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 the target substance in the sample liquid, and the sample liquid is passed through the ion exchanger and sent to the 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 has been injected to react with the target substance in the reaction coil, The target substance is quantified by measuring the absorbance of the solution discharged from the reaction coil.

  The flow injection analysis apparatus of the present invention is a flow injection analysis apparatus for continuously quantifying 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 for injecting a fixed amount of the sample liquid that has passed through the ion exchanger into the carrier liquid supplied to the reaction coil, and the carrier liquid to which the sample liquid is injected at a position between the sampling valve and the reaction coil The addition means for adding the above reagent 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 solution is continuously quantified by flow injection analysis, the sample solution is allowed to pass through the ion exchanger, and then a fixed amount of this sample solution is injected into the carrier solution. Measure the absorbance according to the flow injection analysis procedure and perform quantification. 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 to perform a filter process of filtering and removing insoluble fine particles and the like in the sample solution.

  According to the present invention, when quantifying a target substance in a sample solution by flow injection analysis, it becomes possible to quantify stably.

It is a figure which shows the structure of the flow-injection analyzer of one Embodiment of this invention. 15 is a graph showing the relationship between the number of days of water flow and peak intensity in Example 3.

  Next, embodiments 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 trace amount of urea contained in this sample solution (which can be referred to as sample water here) can be continuously quantified online as a target substance. The invention will now be described by way of example. Of course, the target substance to be quantified in the present invention is not limited to urea, and the sample liquid containing the target substance is not limited to water. In addition, the present invention can be applied to the case of quantifying not batchwise but continuously.

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

  From the upstream side, 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. The filter 51 is for removing insoluble particles contained in the sample water. The ion exchange device 50 has an ion exchanger disposed in a container, and is configured such that sample water passes through the ion exchanger. The ion exchanger provided in the ion exchange device 50 may be only the anion exchanger or may be the cation exchanger, and further, a mixed bed or double bed of the anion exchanger and the cation exchanger It may be Here, the anion exchanger is, for example, at least one of a particulate anion exchange resin, a monolithic anion exchange resin, and an anion exchange fiber. The cation exchanger is, for example, at least one of a particulate cation exchange resin, a monolithic cation exchange resin, and a cation exchange fiber. As described later, in the FIA device of this embodiment, quantification is performed by absorbance measurement, but the ion exchange device 50 is included 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 described later, the pump P4 is connected to the sampling valve 10. However, in order to continuously determine the amount of urea, the on-off valve 22 is always open and the pump P4 is always driven. Thus, the sample water always flows through the sample water pipe 21.

  Next, the sampling valve 10 will be described. The portion downstream of the sampling valve 10 including the sampling valve 10 has a configuration as an FIA device and is actually a portion involved in the determination of urea. The sampling valve 10 has a configuration generally used in the FIA method, and includes a six-way valve 11 and a sample loop 12. The six-way valve 11 has six ports indicated by circled numbers in the figure. 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 is connected to the port 3 via the pump P4. Between port 1 and port 4, a sample loop 12 for collecting a predetermined volume of sample water is connected. One end of a pipe 24 serving as an outlet of the sampling valve 11 is connected to the port 5. Carrier water is water substantially free of urea, and is, for example, pure water.

  Assuming that the communication between the port X and the port Y in the six-way valve 11 is represented by (X-Y), the six-way valve 11 is (1-2), (3-4), (5-6) The first state and the second state of (2-3), (4-5), and (6-1) can be switched. In FIG. 1, the connection between ports in the first state is shown by a solid line, and the connection between ports in the second state is shown by a dotted line. In the first state, the carrier water flows from piping 23 → port 6 → port 5 → piping 24 and flows out from sampling valve 10 to the downstream side. The sample water flows from the sample water piping 21 → port 2 → port 1 → sample loop 12 → port 4 → port 3 and is discharged from the piping 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. Further, the carrier water is pipe 23 → port 6 → port 1 → sample loop 12 → port 4 → port 5 → flow in the pipe 24 and flow out downstream. At this time, the sample water which has already flowed into the sample loop 12 when in the first state and fills the inside of the sample loop 12 flows from the port 5 into the pipe 24 before the carrier water, to the downstream side of the sampling valve 10 Flow. The volume of sample water flowing into the pipe 24 is defined by the sample loop 12. Therefore, by repeatedly switching the first state and the second state (for example, by rotating the six-way valve 11 in the direction of the arrow), a predetermined volume of sample water can be repeatedly fed into the pipe 24. The switching between the first state and the second state can be performed at predetermined time intervals in consideration of a residence time necessary for a reaction described later and a time until the detector 32 detects urea. Moreover, it can also be detected by detecting that the sample water introduced into the detector 32 has been discharged from the detector 32. As described above, by automatically switching between the first state and the second state, urea can be quantified continuously.

  In this apparatus, the FIA method is applied to the determination of urea by colorimetric method using diacetyl monoxime. Therefore, a diacetyl monoximetic acid solution (hereinafter also referred to as reagent A) and an antipyrine-containing reagent solution (hereinafter also referred to as reagent B) are used as reaction reagents used for the determination of urea. Although the case where an antipyrine containing reagent solution is used as a reagent used together with diacetyl monoxime is described here, the reagent used together with diacetyl monoxime is not limited to the antipyrine containing reagent solution. Reagents A and B are stored in storage tanks 41 and 42, respectively.

  After preparation of these reagents, the peak intensity in absorbance measurement decreases when kept at room temperature for a long period (for example, several days or more) for continuous determination of urea, and this peak It has been found that a reduction in strength can be prevented by refrigeration of the reagent (especially reagent B). Since it is preferable that the peak intensity in absorbance measurement does not decrease in order to perform stable determination, the storage tanks 41 and 42 are provided in the refrigeration unit 40 in the FIA device of the present embodiment. The reagent A is prepared by dissolving diacetyl monoxime in an acetic acid solution. However, when the refrigeration unit 40 is provided, the preparation itself is performed in the storage tank 41, or the reagent A is stored in the storage tank 41 after its preparation. Do. Similarly, the reagent B is prepared by dissolving antipyrine in, for example, sulfuric acid, but the preparation itself is performed in the reservoir 42, or the reagent B is stored in the reservoir 42 after its preparation. The refrigeration unit 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 20 ° C. or less, preferably 3 ° C. to 20 ° C. The temperature is maintained at 5 ° C. or more and 15 ° C. or less, more preferably. The storage tank 41 for storing the reagent A may not necessarily be disposed in the refrigeration unit 40 as long as it can be stored in a light-shielded state. Even if the refrigeration temperature of the reagent is less than 5 ° C., it is acceptable if precipitation of crystals does not occur in the reagent. According to the hygiene test method (Non-patent document 1), antipyrine sulfate 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 crystals are precipitated and re-dissolve even if returned to room temperature. Although it is described that refrigerated storage is not suitable because it does not, the present inventors confirmed by experiments that the antipyrine sulfuric acid solution prepared according to the hygienic test method does not crystallize even at 3 ° C.

  One end of a pipe 26 is connected to the storage tank 41, and the other end of the pipe 26 is connected to the pipe 24 by a mixing unit 43. The pipe 26 is provided with a pump P2 for feeding the reagent A into the pipe 24 at a predetermined flow rate. Similarly, one end of a pipe 27 is connected to the storage tank 42, and the other end of the pipe 27 is connected to the pipe 24 by a mixing unit 44. The pipe 27 is provided with a pump P3 for feeding the reagent B into the pipe 24 at a predetermined flow rate. The mixing units 43 and 44 each have a function of uniformly mixing the reagent A and the reagent B with the flow of liquid in the pipe 24. The other end of the pipe 24 is connected to the inlet of the reaction coil 31 provided in the reaction constant temperature chamber 30. The reaction coil 31 causes a coloring reaction between urea and diacetylmonoxime in the presence of antipyrine, and the length and the flow rate inside the reaction coil 31 indicate the residence time required for the reaction. It is selected appropriately according to The reaction thermostat 30 heats the reaction coil 31 to a temperature suitable for the reaction, and for example, heats the reaction coil 31 to a temperature of 50 ° C. to 150 ° C., preferably 90 ° C. to 120 ° C. .

  At the end of the reaction coil 31, that is, at the outlet, a detector 32 is provided for measuring the absorbance of the color generated in the liquid by the color reaction for the liquid flowing out of the reaction coil 31. For example, the peak intensity or peak area of the absorbance near the wavelength of 460 nm is determined by the detector 32. The concentration of urea in the sample water can be determined from the absorbance for the sample water by using the absorbance when the carrier water is flowing as a baseline and determining the calibration curve from the absorbance for the standard solution whose urea concentration is known. At the outlet of the detector 32, a back pressure coil 33 is provided which applies a back pressure to a line from the pump P1 to the detector 32 through the sampling valve 10, the pipe 24 and the reaction coil 31. 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 the present embodiment, the urea in the sample water can be continuously measured on-line continuously by the colorimetric method using diacetyl monoxime, utilizing the FIA method. At this time, if sample water is passed through the ion exchanger and then introduced into the FIA device, even if any substance that may affect the absorbance measurement at the detector 32 is contained in the sample water, that substance is ionized. Since it is removed by the exchange device 50, continuous determination of trace amounts of urea can be stably performed, as will be apparent from the examples described later. Furthermore, by using, as the reagent A (diacetyl monoximetic acid solution) and the reagent B (antipyrin containing reagent solution) used for the reaction, in particular, the reagent B maintained at 20 ° C. or lower after preparation of those reagents It becomes possible to perform stable determination of urea continuously over 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, a portion from the line 20 to the flow meter FI is not provided, and the sample water is directly supplied to the sampling valve 10. Separately from this, an ion exchange apparatus 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 strongly basic anion exchange resin are mixed at a volume ratio of 1: 1. Further, in this example, 2 g of diacetyl monoxime is dissolved in 100 mL of 10% acetic acid to prepare reagent A (diacetyl monoximetic acid solution), 0.2 g of antipyrine is taken, and it is dissolved in 9 mol / L sulfuric acid. As a reagent B (antipyrin-containing reagent solution) was prepared, and immediately after preparation, the reagents were stored in the storage tanks 41 and 42, respectively, and each reagent was continuously supplied from the storage tanks 41 and 42 to the pipe 24.

  Sample water A (raw water for an ultrapure water production system in a semiconductor factory), which is water containing urea and other impurities as sample water, and SV = 10 (L / Lh), that is, the above ion exchange system Water obtained by passing the sample water A so that the flow rate per hour is 10 times the volume of the ion exchange resin (referred to as ion exchange resin treated water) and further urea relative to the ion exchange resin treated water Water (urea decomposition treated water) obtained by the decomposition treatment was used. The urea decomposition treatment was performed by adding 6 ppm of hypobromous acid as a urea decomposition agent to ion-exchange resin-treated water, and reacting at a reaction temperature of 25 ° C. for a reaction time of 24 hours. The urea concentration in each of these sample waters was measured using the assembled FIA device. When measuring the urea concentration, supply a standard solution of urea to the FIA device in advance and measure the absorbance with the detector 32 to create a calibration curve, and apply the result of the absorbance measurement for each sample water to the calibration curve 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 hypobromous acid, urea was added so that the concentration would be 10 ppb with respect to pure water containing no urea, and simulated water was obtained. Example 1 Similarly to the above, ion-exchange resin-treated water and urea-digested water were generated from this simulated water, and the urea concentration was measured for the simulated water, ion-exchange resin-treated water and urea-digested water similarly to 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 coincide with each other, it is understood that no urea is removed by the treatment with the ion exchange resin. Further, it is understood from the result of the urea decomposition treated water that the decomposition treatment of urea using hypobromous acid can remove the urea until the urea concentration becomes less than 1 ppb (below the detection limit).

(Comparative example 1)
After adding 6 ppm of hypobromous acid as a urea decomposing agent to the sample water A in Example 1, reacting at a reaction temperature of 25 ° C. for a reaction time of 24 hours and performing urea decomposition treatment, Example 1 and When the urea concentration was measured under the same conditions, the urea concentration after urea decomposition was measured to be 2.5 ppb.

  From the results of Example 1 and Reference Example 1 and Comparative Example 1 described 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 believed to be due to the contribution of some interferent that has absorption near the wavelength 460 nm and interferes with the determination of urea by absorbance measurement. As shown in Reference Example 1, this indicates that the urea concentration can be reduced to the detection lower limit or less by the urea decomposition treatment, and the result of Comparative Example 1 shows the detection result only by the components other than urea, that is, the interfering substances. However, it is also supported by the fact that the result of Comparative Example 1 is equal to the difference between the detection results of the urea concentration in sample water A and the ion exchange resin treated water in Example 1 within the range of measurement error. Ru. Therefore, from the results of Example 1, the interfering substances that interfered with the absorbance measurement for the determination of urea are removed by the treatment with the ion exchange resin, whereby the urea concentration measured for the ion exchange resin treated water is It can be seen that it represents the actual urea concentration for water A.

(Example 2)
As an ion exchange apparatus in the apparatus used in Example 1, a strongly basic anion exchange resin (Amber Corporation Amberjet 4002 OH) alone (that is, single bed) filled, a strongly acidic cation exchange resin (Organo Corporation Amberjet) Three types were prepared: one filled with H. 1024 H alone, and one filled with a mixed bed resin (ESP-1 manufactured by Organo Corporation) in which a strongly acidic cation exchange resin and a strongly basic anion exchange resin were mixed. Then, as sample water, sample water B (raw water of an ultrapure water production apparatus in a semiconductor factory) different from sample water A was used. The sample obtained by passing sample water B through anion exchange resin is treated as anion exchange resin treated water, and the sample obtained through passing sample water B through cation exchange resin is treated as cation exchange resin treated water, sample water Let B be passed through mixed bed resin to obtain mixed bed resin treated water. The urea concentration was measured in the same manner as in Example 1 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. The amount of liquid passing through the ion exchange apparatus was SV = 10 (L / Lh). 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。

Also from Example 2, it is understood that by using the treatment with the ion exchange resin, it is possible to remove an interfering substance which has absorption near the wavelength of 460 nm and interferes with the determination of urea by absorbance measurement. 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 respect to sample water It is understood that it is preferable to use a resin containing at least an anion exchange resin as the ion exchange resin when carrying out the treatment with the resin.

(Example 3)
Next, the apparatus shown in FIG. 1 was assembled to demonstrate the effect of refrigerated reagents. However, the portion 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.

  The standard solution prepared to have a urea concentration of 60 ppb was continuously supplied to the sampling valve 10 as sample water. And the continuous monitoring of the urea concentration was performed about this standard solution. Here, it was examined how the urea concentration obtained as the measurement value of the detection peak of the absorbance in the detector 32 changes when the measurement is continuously performed on the standard solution. In this example 3, 2 g of diacetyl monoxime is dissolved in 100 mL of 10% acetic acid to prepare reagent A (diacetyl monoximetic acid solution), 0.2 g of antipyrine is taken, it is dissolved in 9 mol / L sulfuric acid, and the total amount is 100 mL. As a reagent B (antipyrin-containing reagent solution) was prepared, and immediately after preparation, the reagents were stored in the storage tanks 41 and 42, respectively, and each reagent was continuously supplied from the storage tanks 41 and 42 to the pipe 24. After each reagent was injected into the reservoirs 41 and 42 at the beginning of the continuous measurement, the reagent was not replenished during the continuous measurement. In addition, the storage tank 41 of the reagent A was maintained at normal temperature. With respect to the reagent B, experiments were conducted in two ways, one at a storage temperature of 10 ° C. and one at a storage temperature of 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 as 100% when measuring the 60 ppb urea standard solution immediately after preparing the reagents A and B and storing them in the storage tanks 41 and 42 respectively. Shows how it changed with the passage of time.

  As shown in FIG. 2, when the antipyrine-containing reagent solution (reagent B) is maintained at 25 ° C., the peak intensity gradually decreases, and the peak intensity is 72% during a 10-day operation for continuous measurement. Down to. That is, it has been impossible to stably determine the amount of urea. On the other hand, when the antipyrine-containing reagent solution is stored under refrigeration and maintained at 10 ° C, it is found that the peak intensity does not decrease even after 10 days of continuous operation, and continuous determination of urea can be stably performed over a long period of time The

(Example 4)
After preparing the reagent B (antipyrin-containing reagent solution) in the same manner as in Example 3, it was stored at 5 ° C., 10 ° C., 15 ° C., 20 ° C., and 25 ° C. for 10 days. Then, after this storage, Reagent B was supplied to the apparatus of Example 3. Immediately after the reagent B was supplied to the apparatus, a standard solution with a urea concentration of 60 ppb was measured using this apparatus to determine its peak intensity. At that time, the peak intensity was 100% when the standard solution was measured immediately after preparation of the reagent B. The reagent A (diacetyl monoximetic 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, when the storage temperature is 5 ° C. and 10 ° C., almost no drop in peak intensity is observed, and when stored at 15 ° C., the peak intensity drops 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 antipyrin-containing reagent solution among the reagents (diacetyl monoximetic acetic acid solution and the antipyrin-containing reagent solution) used for the reaction should be stored under refrigeration. In the case, it was found that the temperature of the antipyrin-containing reagent solution is preferably maintained at 20 ° C. or less, more preferably 3 ° C. or more and 20 ° C. or less, and still more preferably 5 ° C. or more and 15 ° C. or less .

(Example 5)
The same test as in Example 4 was conducted, except that the reagent A (diacetyl monoximetic acid solution) in Example 4 was stored at the same storage temperature as the reagent B (antipyrin-containing reagent solution) in Example 4. .

  When both reagent A and reagent B were refrigerated and measurement was performed, only the reagent B was refrigerated and measurement was performed (Table 4).

Reference Signs List 10 sampling valve 11 six-way valve 12 sample loop 31 reaction coil 32 detector 33 back pressure coil 40 refrigeration unit 41, 42 storage tank 43, 44 mixing unit 50 ion exchange device 51 filter P0 to P4 pump

Claims (10)

A flow injection analysis method for continuously quantifying a target substance in a sample liquid, comprising:
Pass the sample solution into the ion exchanger,
Injecting a predetermined amount of the sample solution that has passed through the ion exchanger into a carrier solution fed toward the reaction coil;
One or more reagents are added to the carrier solution into which the sample solution has been injected, and reaction with the target substance is performed in the reaction coil,
The flow injection analysis method of quantifying the said target substance by measuring the light absorbency of the liquid discharged | emitted from the said reaction coil.   2. The flow injection analysis according to claim 1, wherein the sample solution supplied to the ion exchanger or the sample solution before being poured into the carrier solution after passing through the ion exchanger is subjected to a filter treatment. Method.   The flow injection analysis method according to claim 1 or 2, wherein the target substance in the sample solution is urea, and the one or more reagents are a diacetylmonoxime-containing reagent and an antipyrin-containing reagent.   The flow injection analysis method according to any one of claims 1 to 3, wherein the ion exchanger comprises at least one of particulate anion exchange resin, monolithic anion exchange resin, and anion exchange fiber.   The flow injection analysis method according to any one of claims 1 to 4, wherein the at least one reagent is refrigerated after the preparation of the one or more reagents. A flow injection analyzer that quantifies a target substance in a sample solution,
A reaction coil to which carrier liquid is continuously supplied;
An ion exchanger through which the sample solution is passed;
A sampling valve for injecting a fixed amount of the sample solution which has passed through the ion exchanger into the carrier solution supplied to the reaction coil;
Addition means for adding one or more reagents to the carrier liquid into which the sample liquid has been injected at a position between the sampling valve and the reaction coil;
A detector for measuring the absorbance of the liquid discharged from the reaction coil;
A flow injection analyzer comprising: the target substance and the one or more reagents in the reaction coil.   The flow injection analyzer according to claim 6, further comprising a filter at least one of a pipe connected to the inlet of the ion exchanger and a pipe connecting the outlet of the ion exchanger and the sampling valve.   8. The flow injection analyzer according to claim 6, wherein the ion exchanger comprises at least one of particulate anion exchange resin, monolithic anion exchange resin, and anion exchange fiber.   The flow injection analyzer according to any one of claims 6 to 8, wherein the target substance in the sample solution is urea, and the one or more reagents are a diacetylmonoxime-containing reagent and an antipyrin-containing reagent. A reservoir for storing at least one of said prepared reagents;
Cooling means for cooling the storage tank;
The flow injection analyzer according to any one of claims 6 to 9, comprising:

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