JP2007101287A - Sample analysis pretreatment method, ph indicator for sample analysis pretreatment, and kit for the sample analysis pretreatment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily and surely adjust pH of a sample, prior to analysis of the sample, and to remove materials that serve as analysis obstacle. <P>SOLUTION: The pretreatment method for sample analysis includes processes of bringing sample liquid containing material to be analyzed into contact with a pH indicator, performing the pH adjustment of required sample liquid based on the color, bringing the sample liquid into contact with an adsorbent for capturing the target material to be analyzed contained in the sample and the indicator, and capturing the material to be analyzed and the indicator on the adsorbent. The indicator for pretreatment and the kit for pretreatment suitable in use for this method are provided. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a sample analysis pretreatment method, a sample analysis pretreatment pH indicator, and a sample analysis pretreatment kit.

  As an application example of the present invention, for example, when pre-processing a sample, it is possible to reduce the time until the sample is easily optimized by recognizing the condition of the sample using an indicator and using an apparatus that can be visually or easily operated. Shorten. Further, the indicator is collected during the pretreatment, and the indicator is prevented from remaining in the sample obtained after the pretreatment, thereby ensuring the reliability of the measurement result. Here, the indicator is an acid-base indicator, which is a substance having a discoloration range within a certain range of pH of an aqueous solution, showing a different color corresponding to the pH within that range, and measuring the pH and determining the end point of neutralization titration. Is used.

  An example of pretreatment of trace metals such as river water, lake water, and soil by solid phase extraction will be described. In this example, the operation is divided into a process of adjusting the pH of the sample to 5.5 (conditioning), flowing the sample through the solid-phase extraction column, and obtaining the target component (pretreatment).

  In the pretreatment, a sample is first collected and the pH is measured. If the pH is the target 5.5, collect the sample again and use it as the sample for pretreatment. The reason for acquiring the sample again is to prevent contamination because the pH electrode contacts the sample during pH measurement, which may cause contamination and an error in the final analysis value.

  When the pH is not 5.5, a sample is obtained again, estimated from the measured pH, a reagent such as nitric acid or ammonia is added for pH adjustment, and the pH is measured. If the pH does not reach 5.5, these operations are repeated again, and the adjustment is continued until the pH reaches 5.5. When the pH reaches 5.5, the sample is collected again, and the optimum amount of the reagent added at the time of pH adjustment is added to obtain a pretreatment sample.

  In the case of the conventional method, a sample is collected until the optimum pH is reached, and the amount of reagent added is investigated. In addition, the pH of the sample used for pretreatment is indirectly adjusted, and the pH cannot be confirmed due to contamination, etc., so if you do not notice that the reagent could not be added with good reproducibility, the pretreatment failed. Leads to.

  Pass the sample with such anxiety factor through the solid-phase extraction column, capture the target component on the column, elute the target component captured by the eluate, collect the sample solution, Analyze the target component.

  Patent Document 1 discloses that test water, a pH indicator, and an acid are mixed and colorimetrically measured for alkalinity. However, it is disclosed to adsorb metal ions in the test water and perform pretreatment. Not done.

JP 2004-264139 A

  When the sample is pretreated, an operation for adjusting the condition of the sample occurs. In order to adjust the condition, a part of the sample is collected and an operation such as addition of a reagent is performed to check whether or not the optimum condition can be obtained. In this case, the trial and error is repeated until the optimum condition is reached.

  However, in the case where the method for confirming the optimum state is a method performed by an apparatus that requires a complicated operation, a great amount of time is spent until the optimization. In addition, when the amount of the sample is small, these trial and error cannot be performed sufficiently, and sufficient optimization may not be performed.

  When conditioning, a reagent for identifying the state may be added, but depending on the method, the reagent may remain in the sample after completion of the pretreatment, which may affect the measurement results. There are many things that cannot be taken. An object of the present invention is to use a pH indicator to know the pH state of a sample visually or with an apparatus, and then remove the indicator that affects the measurement at a pretreatment stage.

  In the present invention, a sample liquid containing an analysis target substance is brought into contact with a pH indicator, pH adjustment of the necessary sample liquid is performed based on the coloration, and then the target analysis target substance contained in the sample and the indicator The sample analysis pretreatment method includes a step of contacting the sample solution with an adsorbent that captures the sample, and capturing the analyte and indicator in the adsorbent.

  In addition, the present invention provides two or more indicators that are different from each other in the color pH range but are close to each other, and they coexist in the sample solution and exhibit a characteristic color in the target pH range. The present invention provides an indicator for pretreatment of sample analysis, which is characterized in that it can be used.

  Furthermore, the present invention provides a sample analysis pretreatment kit comprising: an analytical indicator showing a characteristic coloration in a target pH range; and a container holding a polymer capable of capturing metal ions and the indicator. It is to provide.

  According to the present invention, a method, a reagent, and an analysis for adsorbing and capturing a target metal or metal ion in a sample by a simple conditioning method and easily separating a substance that hinders analysis of the target metal or metal ion Kits can be provided.

  Hereinafter, a preferred embodiment of the present invention will be briefly described. In the present invention, it is preferable that the indicator contains two or more indicators having different coloration pH ranges, and they coexist in the sample solution and exhibit characteristic coloration in the target pH range. . Moreover, it is preferable that the said analysis target object is a metal ion.

  The indicators have different coloration pH ranges, but it is preferable that two or more coloration ranges are close to each other, and they coexist in the sample solution and exhibit characteristic coloration in the target pH range. The adsorbent preferably contains a benzene ring and a cation exchange group.

  It is preferable that the cation exchange group of the adsorbent and the metal ion form a complex. It is preferable that the indicator contains a benzene ring and the adsorbent is a polymer containing a benzene ring.

  The determination of the pH of the sample solution by the coloration of the indicator can be made visually. Determination of the pH of the sample solution by coloration of the indicator can be performed with a spectrophotometer or the like.

  In the present invention, conditioning can be carried out by knowing the pH measurement ranges of various pH indicators and selecting an indicator having a target pH value. Examples of pH measurement ranges for pH indicators are shown in Table 1.

  The pH indicators and pH measurement ranges shown in Table 1 are those described in the catalog of ADVANTEC.

  As a particularly preferred embodiment of the present invention, a sample solution containing a metal ion to be analyzed is brought into contact with two or more kinds of pH indicators having different coloration pH ranges, and the necessary pH adjustment of the sample solution is performed based on the coloration. There is a way to do. By using a combination of a plurality of indicators, it is possible to accurately determine the coloration of the target pH value. Furthermore, the sample solution is brought into contact with an adsorbent that captures the target metal ions and the indicator contained in the sample, and the analyte metal ions and the indicator are captured by the adsorbent. And the adsorbent that has captured the analysis target metal ion and the indicator are brought into contact with the eluent of the metal ion, the analysis target metal ion is eluted, and the indicator is captured by the adsorbent. It is a sample analysis pretreatment method including a process.

  It is preferable that the indicator contains two or more kinds of indicators that are different from each other in coloration pH range but are close to each other, and can coexist in a sample solution and exhibit characteristic coloration in a target pH range. . The indicator preferably includes a benzene ring, and the adsorbent is preferably a polymer including a benzene ring and a cation exchange group. According to such a combination, when the metal ions adsorbed and captured by the adsorbent are eluted by the eluent, the indicator can be reliably captured by the affinity between the chemically similar indicator and the adsorbent. And only metal ions can be reliably eluted. The analyte is a heavy metal ion, and the cation exchange group of the adsorbent and the metal ion preferably form a complex. The pH can be determined by coloration of the indicator visually or with a spectrophotometer.

  The present invention provides a sample analysis pretreatment comprising two or more indicators that are different from each other in coloration pH range but are close to each other and capable of exhibiting characteristic coloration in a target pH range. A kit is provided.

  In order to bring the sample into an optimum condition in the pretreatment, an indicator that can identify that the sample is in the optimum condition is added in the present invention, and the optimization of the condition of the sample can be easily judged in a short time. .

  If the indicator remains in the sample, there is a possibility of disturbing the analysis result at the time of measurement. Therefore, a unit or function capable of simultaneously collecting or removing the indicator is incorporated at the stage of sample pretreatment. Even if there is a possibility that the analysis result may be affected by using an indicator during measurement by this method, the reliability of the analysis value can be ensured because it is removed at the pretreatment stage.

  In the present invention, it is possible to freely select an indicator excellent in the ability to identify the condition of the sample for the pretreatment indicator, and the optimum state can be visually confirmed. Become.

  In addition, when the number of samples is small, the conventional method adds a reagent that adjusts the condition by trial and error, so the sample is required for the number of times of trial and error, so it takes time and it is not easy to find the optimal condition. There are cases in which conditioning is unsuccessful because of complicated work. However, in the present invention, since the condition state can be identified by the sample actually used for the pretreatment, the error at the time of reagent addition can be eliminated. In addition, the target component can be separated, the indicator can be reliably captured, and the indicator is separated from the captured sample, so that the indicator does not remain in the sample after the pretreatment, thus ensuring the reliability of the analysis value. be able to.

  As an example for explaining the present invention, an example in which a trace metal in river water is pretreated by a solid phase extraction method is shown.

  When sample pretreatment is performed, the sample condition is adjusted and pretreatment is performed. Usually, it takes a lot of time to check the condition. In addition, when the target component is a metal element, it is considered that contamination occurs by performing various operations (for example, pH measurement with a pH meter). Therefore, a part of the sample is collected in several times, and the reagent is removed. Add and determine optimal conditions. A sample is taken again based on this condition, and the determined reagent amount is added to obtain an optimum condition. In the present invention, by checking the condition of the sample by a simple method such as visual observation, the conditioning operation can be simplified, and the indicator for confirmation of the condition is eliminated in the pretreatment process. Does not appear. In particular, since the condition of the sample itself to be pretreated is confirmed, it is possible to prevent pretreatment failure due to insufficient conditioning.

  The present invention simplifies the conditioning operation for pretreatment, and further, since the conditioning indicator can be removed in the pretreatment process, interference by the indicator can be suppressed during analysis. In addition, since the condition of the sample itself used for the pretreatment can be confirmed easily and in a short time, an artificial error in conditioning can be prevented.

  According to the present invention, in the process of pre-processing a sample, an indicator that can easily determine the condition of the sample is used, and operations such as determining the condition visually can be simplified. Moreover, the influence on the analysis can be eliminated by removing the indicator in the pretreatment process. Further, since the condition of the sample to be pretreated can be confirmed and used for the pretreatment, even when the amount of the sample is small, appropriate conditioning can be performed without repeating trial and error. As a result, an artificial error in the preprocessing stage can be prevented, and the reliability of the analysis value is improved.

  FIG. 1 shows a flow of sample conditioning before pretreatment in the present invention. First, a sample is collected (S1), and a pH indicator (methyl red) that causes a color change around pH 5.5 is added (S2). In this case, as a selection condition for the pH indicator, one that easily adsorbs to the polymer as the adsorbent, such as a structure containing a benzene ring, is used.

  The chemical structure of methyl red in the low pH region is as shown in (Formula 1), the chemical structure at a high pH value is as shown in (Formula 2), and the pH measurement range is 5.4-7.0. It is. On the other hand, a styrene resin such as a styrene-divinylbenzene copolymer provided with a cation exchange group is suitable as a polymer as an adsorbent.

  Next, visual confirmation (S3) is performed, and if it can be determined that the pH is 5.5 based on the color of the sample solution, it is used as a pretreatment sample (S5). If the color of the sample solution is not pH 5.5, a reagent such as nitric acid or ammonia is added (S4), visual confirmation is performed again (S3), and the sample solution is continued until the color becomes pH 5.5.

  If it can be determined from the color of the sample solution that the pH is 5.5, it is used as a pretreatment sample (S5). The advantage of this method is that it is sufficient to collect a sample once, and it is possible to apply even a small amount of sample, and furthermore, it is possible to actually confirm the condition of the sample to be actually pretreated. However, since a pH indicator (such as methyl red) remains in the sample, it is necessary to remove the pH indicator from the sample at the end of the pretreatment.

  A pH indicator such as methyl red is often an organic component containing a benzene ring. Such a substance is easily adsorbed by a highly hydrophobic substance such as a styrene resin. In the present invention, using such characteristics, the target component can be eluted from the adsorbent and separated from the indicator in the pretreatment stage so that the indicator does not remain in the solution at the end of the pretreatment.

  The sample whose pH is adjusted in the flow of FIG. 1 is a column in which a functional group capable of capturing metal is added to a styrene resin. The metal element as a target component is a functional group, and the pH indicator is captured by the resin itself and eluted. FIGS. 2A to 2C show a method in which only the metal element of the target component is eluted with the liquid.

  FIG. 2A shows a sample for pretreatment that has been conditioned according to the flow shown in FIG. 1, and is passed from a sample container 1 to a column 2 filled with an adsorption resin of a styrene resin having a functional group for capturing a metal. It is a figure to do. Below the column 2 is provided a waste liquid tank 3 for receiving contaminant components such as calcium and sodium removed in the pretreatment.

  FIG. 2B is a diagram in which a pretreatment sample is passed through the column 2. Since the pH indicator is an organic substance, it is adsorbed by the styrene resin packed in the column 2 and remains as the adsorption layer 8 on the upper layer of the adsorption resin. Similarly, since the target component has a mechanism of being trapped by the resin, it remains in the resin, and the narrow component flows out to the waste liquid tank 3.

  FIG. 2 (c) is a diagram in which a sample subjected to pretreatment by eluting the target component (metal element) is collected. In the case of metal, an acid solution such as nitric acid is often used as the eluent in the eluent container 6. Although the acid solution is passed through the column 2, the acid solution does not have the ability to elute the pH indicator adsorbed on the styrene resin. As a result, only the target component metal elutes, and the pH indicator and the target component are ionized. Can be separated. The eluent is stored in the eluent container 7.

  The actual results are shown in Table 2. When the sample was passed through the column, the pH indicator was adsorbed on the upper layer of the resin. Although nitric acid for elution of the metal element trapped in the resin was passed through, the pH indicator was an organic substance, so that it was not eluted. However, since the captured metal is eluted, the metal element of the target component is eluted from the eluate, and the result of measuring the concentration as a percentage of the theoretical value (recovery rate) is almost 100 ±. The result was 10%, which was a good result. Further, the pH indicator remained in the column, and separation could be performed in the pretreatment process.

  By using the present invention, an indicator for knowing the state of conditioning of a sample can be freely selected. In addition, since the state of the sample can be determined by a simple operation such as visual observation once collected, the conditioning time can be shortened. Furthermore, since it is possible to know the state of the sample that is actually pretreated, mistakes due to conditioning can be prevented. Further, since these indicators can be excluded from the target sample in the pretreatment stage, they are not disturbed by the indicator during the measurement.

  According to the embodiment of the present invention, when performing sample pretreatment, an indicator for knowing the state of conditioning of a sample can be freely selected. In addition, since the state of the sample can be determined by a simple operation such as visual observation once collected, the conditioning time can be shortened.

  Furthermore, since it is possible to know the state of the sample that is actually pretreated, mistakes due to conditioning can be prevented. In addition, since these indicators can be eliminated in the pretreatment stage, the indicator is not disturbed during the measurement, and the reliability of the analysis value is improved.

  In the present invention, a plurality of pH indicators having different pH measurement ranges can be appropriately combined to narrow down the color gamut of the pH indicator, and conditioning with higher accuracy can be performed. For example, the pH measurement range of methyl red is 5.4-7.0, but if only methyl red is used, it may be difficult to determine the color change between red (low pH range) and yellow (high pH range). obtain. Therefore, a combination of bromocresol green (Equation 3) and (Equation 4), which shows yellow in the low pH range, blue in the high pH range, and has a color change range around pH 5.5, can be used to change the pH value. More accurate determination can be made. Bromcresol green has the structure shown in (Formula 3) in the low pH range, and has the structure shown in (Formula 4) in the high pH range. The color gamut of part romcresol green is pH 4.0-5.6.

  By using a combination of the above methyl red and bromcresol green, it has a characteristic color range in a narrower range, and conditioning can be performed accurately.

  The present invention is applied to water quality analysis of rivers, lakes and the like, particularly analysis of metals or metal ions and analysis of metals or metal ions such as soil. It is particularly effective for analyzing heavy metals or heavy metal ions with a very small content.

FIG. 3 is a flow diagram of a conditioning method for pretreatment of the present invention. Is a schematic diagram showing a sample conditioning method, (a) shows a state before passing through the sample, (b) shows after passing through the sample, and (c) shows a state after elution of the target component.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Sample and indicator container, 2 ... Pretreatment solid phase extraction column, 3 ... Waste liquid tank, 5 ... Adsorption resin, 5 '... Adsorption resin after elution of metal ions, 6 ... Eluent container, 7 ... Eluent container .

Claims (20)

  Adsorption in which a sample liquid containing an analysis target substance is brought into contact with a pH indicator, the pH of the necessary sample liquid is adjusted based on the coloration, and then the target analysis target substance and the indicator contained in the sample are captured. A sample analysis pretreatment method comprising a step of contacting the sample solution with an agent and capturing the substance to be analyzed and the indicator in the adsorbent.   The indicator comprises two or more kinds of indicators having different coloration pH ranges, and they coexist in a sample solution and exhibit characteristic coloration in a target pH range. The sample analysis pretreatment method according to 1.   The sample analysis pretreatment method according to claim 1, wherein the analysis object is a metal ion.   The indicator is different in coloration pH range, but the coloration range is two or more kinds close to each other, and they coexist in the sample liquid and exhibit characteristic coloration in the target pH range. The sample analysis pretreatment method according to claim 1.   The sample analysis pretreatment method according to claim 1, wherein the adsorbent is a polymer containing a benzene ring and a cation exchange group.   The sample analysis pretreatment method according to claim 1, wherein the analysis object is a heavy metal ion.   6. The sample analysis pretreatment method according to claim 5, wherein a cation exchange group and a metal ion of the adsorbent form a complex.   The sample analysis pretreatment method according to claim 1, wherein the indicator contains a benzene ring, and the adsorbent is a polymer containing a benzene ring.   The sample analysis pretreatment method according to claim 1, wherein the pH of the sample solution is visually determined by coloring the indicator.   2. The sample analysis pretreatment method according to claim 1, wherein the pH of the sample solution is determined with a photometer by coloration of the indicator.   A sample solution containing a metal ion to be analyzed is brought into contact with two or more pH indicators having different coloration pH ranges, and the necessary pH adjustment of the sample solution is performed based on the coloration. Contacting the sample liquid with an adsorbent that captures the analysis target metal ions and the indicator, capturing the analysis target metal ions and the indicator on the adsorbent, and flowing out unnecessary substances, and the analysis target metal A sample analysis pretreatment method comprising the steps of contacting an adsorbent capturing ions and an indicator with an eluent of the metal ions, eluting the metal ions to be analyzed, and capturing the indicator on the adsorbent. .   The indicator has two or more kinds of indicators that are different from each other in coloration pH range but are close to each other, and can coexist in a sample solution and exhibit characteristic coloration in a target pH range. The sample analysis pretreatment method according to claim 11.   The sample analysis pretreatment method according to claim 11, wherein the indicator contains a benzene ring, and the adsorbent is a polymer containing a benzene ring and a cation exchange group.   The sample analysis pretreatment method according to claim 11, wherein the metal to be analyzed is a heavy metal ion.   The sample analysis pretreatment method according to claim 11, wherein a cation exchange group and a metal ion of the adsorbent form a complex.   The sample analysis pretreatment method according to claim 11, wherein the pH is determined visually by coloration of the indicator.   12. The sample analysis pretreatment method according to claim 11, wherein the pH is determined by coloration of the indicator with a spectrophotometer.   Two or more kinds of indicators that are different in coloration pH range but close to each other, and can coexist in the sample solution and exhibit characteristic coloration in the target pH range Indicator for analysis pretreatment.   A sample analysis pretreatment kit comprising: an analysis indicator that exhibits a characteristic coloration in a target pH range; and a container that holds a metal ion and a polymer capable of capturing the indicator.   The sample analysis pretreatment according to claim 19, wherein the analysis indicator comprises two or more indicators that are different in coloration pH range but are close to each other and can exhibit characteristic coloration in a target pH range. For kit.

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