JP3689910B2 - How to create a calibration curve - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sample preparation apparatus suitable for creating a calibration curve for a trace substance (for example, moisture) measurement application in a near-infrared spectrometer, for example, and a calibration curve creation method using the sample preparation apparatus.
[0002]
[Prior art]
For example, in a near-infrared spectrometer, it is necessary to create a calibration curve before actual moisture content measurement. In order to create a calibration curve for a trace moisture concentration of a liquid sample such as an organic solvent, it is necessary to introduce a sample with a known moisture concentration into a measurement cell and collect its spectrum.
[0003]
Conventionally, a sample is collected or prepared in a container such as an Erlenmeyer flask, and the sample is introduced into a measurement cell of a near-infrared spectrometer, and at the same time, the moisture content is measured by a laboratory analysis method such as the Karl Fischer method. I was going.
[0004]
[Problems to be solved by the invention]
By the way, in the above-mentioned prior art, the sample is exposed to the surrounding air at the time of sample collection, preparation, introduction to the measurement cell of the near-infrared spectrometer, and the laboratory analyzer. The moisture content of the inside was absorbed, and the moisture content always increased, causing an error. Even when purging with dry air or nitrogen to reduce the humidity in the air, it is very difficult to avoid an error of about several tens of ppm in terms of moisture concentration.
[0005]
The present invention has been made to solve the above problems, and by using a simple device, a sample having a known moisture concentration is prepared without any influence of moisture absorption from the air, and This makes it possible to introduce the prepared sample into the measuring cell of the near-infrared spectrometer. Accordingly, an object of the present invention is to provide a sample preparation device for accurately producing a calibration curve for trace moisture, which has been difficult in the past, and a calibration curve creation method using the sample preparation device.
[0006]
[Means for Solving the Problems]
To achieve this object, the present invention provides, in claim 1,
1. Putting a sample whose component is known in a container in which a part of the container including the lid is formed of a soft elastic member, and blocking contact with external air;
2. A sample introduction step of introducing the sample in the container into the property measuring means in an airtight state;
3. Measuring the properties of the sample in the container;
4). Returning the sample introduced into the property measuring means into the container;
5. Injecting a predetermined amount of a trace substance in an airtight state through the soft elastic member using a needle constituting a trace substance injection means into the sample returned into the container;
6). A sample introduction step of introducing the sample in the container into which the trace substance is injected into the property measuring means in an airtight state;
7. Measuring the properties of the sample in the container;
8). Returning the sample introduced into the property measuring means into the container;
9. Injecting a predetermined amount of a trace substance in an airtight state into the sample returned to the container;
10. A step of repeating the steps 6 to 9 a plurality of times,
It is characterized by including.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is an explanatory diagram of a sample preparation device showing an example of an embodiment of the present invention. In the figure, 1 is a sample container made of glass or the like (for example, a capacity of 1 L), and 2 is a sample to be measured (for example, an organic solvent) placed in the container 1. Reference numeral 3 denotes a lid, which is airtightly attached so that the sample in the container does not come into contact with external gas (air).
[0013]
A tip of a probe 6 constituting a property measuring means (hereinafter referred to as a measurement cell) 5 is inserted into the lid 3 in an airtight manner through the seal member 4a. Reference numeral 4b denotes a soft elastic member (hereinafter referred to as a septum) made of silicon rubber or soft plastic, which is airtightly attached to the lid 3. 7 is a trace substance injection means (injection cylinder: hereinafter referred to as a microsyringe), which injects a predetermined amount of trace substance with the needle pierced into the septum 4b and the tip reaching the container 1.
[0014]
8 is a stirrer (stirrer) using magnetism, and 9 is a stirrer, and the stirrer arranged in the sample rotates as the magnetic substance in the stirrer rotates to stir the sample. .
[0015]
Next, a calibration curve creation method using the above-described sample preparation apparatus will be described.
1) First, an organic solvent sample 2 whose moisture concentration and volume are accurately known is placed in a sample container 1, and the container 1 is sealed using a lid 3. (For example, 1 L of acetone having a moisture concentration of 0.0 ppm) The measurement cell 5 is attached to the lid 3 in advance.
[0016]
2) The spectrum is measured by the property measuring means 5. (Now, the spectrum of the sample with a moisture concentration of 0.0 ppm can be measured.)
3) Take a small amount of water, for example, 10 μL with the microsyringe 10 and inject it into the sample container 1 through the septum 4b. Since the septum 4b is made of a soft plastic such as silicon rubber, external air does not enter and exit the sample container 1 when the needle of the microsyringe 10 is inserted and removed.
[0017]
4) The stirrer 8 is operated by operating the stirrer 8 for a certain time (for example, several tens of seconds), the sample is stirred, and the injected water is completely dissolved.
5) Calculate the water concentration from the amount of water added and the amount of sample initially added. (For example, the addition amount is 10 μL / sample amount is 1 L = 10 ppm.
[0018]
6) Repeat 3) to 5) and collect the required number of spectra until the required concentration is reached.
When the measurement is completed, the relationship between the water injection amount and the water concentration (ppm) contained in acetone as shown in FIG. 2 is obtained using the collected spectrum, and the laboratory analysis value and the near red color are obtained using an equation for obtaining a calibration curve. A calibration curve as shown in FIG. 3 is created from the relationship between the outputs of the external analyzer.
[0019]
FIG. 4 is an explanatory view showing the configuration of a sample preparation apparatus showing another embodiment. In addition, the structure which puts the sample 2 in the container 1 containing the stirrer 8 and covers the lid | cover 3 airtightly is the same as that of FIG. Here, a configuration is shown in which a calibration curve is created online using the measurement cell 5 constituting the near-infrared analyzer.
[0020]
In FIG. 4, a tube 10a (for example, Teflon (registered trademark)) is hermetically inserted into the sample of the container 1, and the upper end of the tube is connected to the sample inlet of the measurement cell 5 through a valve 11a. A tube 10b is connected to the sample outlet of the measurement cell, and is connected to the suction port of the syringe 12 via a valve 11b and a tube 10c.
[0021]
Next, a calibration curve creation method using the above-described sample preparation apparatus will be described.
1) First, an organic solvent sample 2 whose moisture concentration and volume are accurately known is placed in the sample container 1, and the container is sealed. (For example, 1 L of acetone with a water concentration of 0.0 ppm)
[0022]
2) With the valves 11 a and 11 b opened, the sample is sucked with the syringe 12, and the sample is sucked until the measurement cell 5 is filled.
3) Close the valves 11a and 11b.
4) Measure the spectrum. (Now, the spectrum of the sample with a moisture concentration of 0.0 ppm can be measured.)
[0023]
5) Open the valves 11a and 11b and push the sample back into the sample container 1 with the syringe 12.
6) Close the valves 11a and 11b.
[0024]
7) Take a small amount of water, for example, 10 μL with the microsyringe 10 and inject it into the sample container 1 through the septum 5b. Since the septum 4b is made of a soft plastic such as silicon rubber, external air does not enter and exit the sample container 1 when the needle of the microsyringe 7 is inserted and removed.
[0025]
8) The stirrer 8 is operated by operating the stirrer 8 for a certain time (for example, several tens of seconds), the sample 1 is stirred, and the injected water is completely dissolved.
11) Calculate the water concentration from the amount of water added and the amount of sample initially added. (For example, the addition amount is 10 μL / the sample amount is 1 L = 10 ppm. Since the sample placed in the measurement cell is returned to the sample container, the sample amount does not change.)
[0026]
12) Repeat steps 2) to 11) and collect the required number of spectra until the required concentration is reached.
When the measurement is completed, a calibration curve is created using an equation for obtaining the relationship shown in FIG. 2 and FIG.
[0027]
According to the above-described preparation apparatus and the calibration curve creation method using the same, an insertion type measurement is performed as compared with the example of FIG. 1 in which a sample is sucked from a sample container using a Teflon (registered trademark) tube, valve, and syringe. The cell (probe) can be directly inserted into the sample container, and sample preparation and spectrum measurement can be performed in the same procedure.
[0028]
Thereby, since the sample is not taken in and out of the measurement cell, the spectrum of the trace moisture sample can be measured without being affected by moisture absorption, and the accuracy of the calibration curve can be improved.
[0029]
The foregoing description of the present invention has only shown certain preferred embodiments for purposes of illustration and illustration. Accordingly, it will be apparent to those skilled in the art that the present invention can be modified and modified in many ways without departing from the essence thereof. For example, in the present embodiment, the trace substance is moisture, but other substances may be used without being limited thereto. The scope of the present invention defined by the description in the appended claims is intended to include modifications and variations within the scope.
[0030]
【The invention's effect】
As described above, according to the present invention, when injecting a trace substance into a sample in a container, the trace substance is injected multiple times through a soft elastic member using a needle constituting the trace substance injection means. since so as to measure the properties of the samples changed in concentration each time, be formulated with trace moisture samples without any contact with the outside air, the concentration is calculated and introducing the sample into the measuring cell it can. As a result, it is possible to measure a sample curve for preparing a calibration curve without being affected by moisture absorption from the air at all, and therefore it is possible to accurately create a calibration curve for trace amounts of moisture, which has been difficult in the past.
[Brief description of the drawings]
FIG. 1 is a configuration explanatory view showing an example of an embodiment of a sample preparation apparatus of the present invention.
FIG. 2 is an explanatory diagram showing the relationship between water injection amount and water concentration (ppm).
FIG. 3 is a diagram showing a calibration curve created from a relationship between a laboratory analysis value and an output of a near-infrared analyzer.
FIG. 4 is a configuration explanatory view showing an example of another embodiment of the sample preparation apparatus of the present invention.
[Explanation of symbols]
1 Sample container 2 Sample to be measured 3 Lid 4a Seal member 4b Soft elastic member (septum)
6 Probe (Teflon (registered trademark))
7 Trace substance injection means (micro syringe)
8 Stirrer (stirrer)
9 Stirrer 10 Tube (Teflon (registered trademark))
11 Valve 12 Syringe

Claims (1)

1. A step of putting a sample having a known component into a container in which a part of the container including the lid is formed of a soft elastic member and blocking contact with external air;
2. A sample introduction step of introducing the sample in the container into the property measuring means in an airtight state;
3. Measuring the properties of the sample in the container;
4). Returning the sample introduced into the property measuring means into the container;
5. Injecting a predetermined amount of a trace substance in an airtight state through the soft elastic member using a needle constituting a trace substance injection means to the sample returned to the container;
6). A sample introduction step of introducing the sample in the container into which the trace substance is injected into the property measuring means in an airtight state;
7. Measuring the properties of the sample in the container;
8). Returning the sample introduced into the property measuring means into the container;
9. Injecting a predetermined amount of a trace substance in an airtight state into the sample returned to the container;
10. A step of repeating the steps 6 to 9 a plurality of times,
A calibration curve creating method characterized by comprising:

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