Near-infrared spectroscopic analysis measurement cell

Abstract

To provide a technique for a measuring cell capable of measuring a component of a viscous sample such as the unrefined sake by a near-infrared spectroscopic analysis method without filtering the sample as it is with a small amount of the sample, easily injecting the sample and stably measuring the component with high accuracy.SOLUTION: An adapter is inserted into a void portion having the fixed thickness after injecting a viscous sample to be measured by a square transparent container with a gap portion of a certain thickness and a transparent window portion for light transmission on one side. The near-infrared spectroscopic analysis is performed in a reflection method using a measurement cell in which a reflection plate is inserted into the side of the measurement container having the transparent window of the adapter.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a measurement cell for analyzing components of a viscous sample such as sake mash using a near-infrared spectroscopic analyzer. [Background technology]

[0002] Conventionally, a viscous sample such as sake mash has been filtered through a filtration device, placed in a predetermined cell, and subjected to near-infrared spectroscopic analysis using the transmitted light method. However, this method requires filtration, and the number of filter papers required can be an issue, resulting in inconsistent analytical values. In addition, the filtration process takes time, and the components of the sample in the viscous liquid of sake mash or the like evaporate during the filtration, making it impossible to measure accurate component values. Another problem is that a relatively large amount of sample is required.

[0003] Therefore, a method has been proposed in which a viscous sample such as sake mash is placed directly into a measurement cell without filtration and near-infrared spectroscopic analysis is performed using a relatively small amount of sample in a reflected light system.

[0004] The method described in Reference 1 uses a ceramic cell with a porous surface, which is immersed in a sake mash sample, and after the sample is removed, it is placed on a standard open cup and subjected to near-infrared spectroscopic analysis using reflected light. This method had the drawback that the measurement cell was porous, making it difficult to clean after measuring the sample, and the residue of sake mash would remain and accumulate in the porous parts, making it impossible to accurately measure the sake mash components in the sample. Furthermore, it is difficult to produce a porous body with consistent specifications by firing, and there is also the problem that the measured values ​​vary for each ceramic cell. Furthermore, the ceramic cell becomes discolored over time, posing a durability problem.

[0005] The method described in Reference 2 involves immersing a porous sample collection body made of ceramic or the like similar to that described in Reference 1 in sake mash to collect a sake mash sample, and then measuring the components of the sake mash using reflectance near-infrared spectroscopy. This also has the same drawbacks as those described in Reference 1. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent Publication No. 7-270283 [Non-patent literature]

[0007] [Non-Patent Document 1] Journal of Bioengineering, Vol. 76, No. 6, 233-237, 1998 Summary of the Invention [Problem to be solved by the invention]

[0008] To provide a measurement cell for near-infrared spectroscopic analysis which can measure a viscous sample such as sake mash by simply placing it in a measurement cell without pretreatment such as filtration, and which simplifies the measurement work, improves measurement efficiency, and provides high measurement accuracy, and which is easy to clean after each measurement and does not change over time. [Means for solving the problem]

[0009] In order to achieve the above-mentioned object, the measurement cell of the present invention is a rectangular measurement container having a gap of a certain thickness with a transparent window portion for light transmission on one side, and during measurement, a viscous sample such as sake mash is injected into the gap of a certain thickness, and then an adapter is inserted, and a reflector is inserted into the side of the adapter having the transparent window of the measurement container to reduce the thickness of the layer of the measurement sample before measurement.

[0010] Furthermore, a notch may be provided on the upper longitudinal side of the adapter to accommodate excess viscous sample such as sake mash that is not required for measurement.

[0011] The adapter may also be provided with spring-loaded ball set screws at multiple locations, and the reflector may be supported from the adapter side by the balls of the ball set screws. A spring-loaded ball set screw is a type of screw that has a ball at its tip and is pressed by a spring, as shown in Figure 3. [Effects of the Invention]

[0012] Because near-infrared light does not easily penetrate viscous samples such as sake mash, accurate measurements can be achieved by thinning the layer thickness during measurement and using the reflected light method, but it is not easy to inject and fill a viscous sample into the narrow space of the measurement sample holder. According to the present invention, the sample is injected into a wide cell when injecting it into the measurement cell, making it easy to inject even viscous samples such as sake mash, and the injection time is short, greatly improving workability.

[0013] After the viscous sample is poured into the wide cell up to about halfway from the bottom, an adapter and a reflector are inserted to reduce the layer thickness, so pressure is applied to the thick, viscous sample, filling every corner of the narrow measurement sample storage area sufficiently and in a short time, thereby improving measurement accuracy and workability. Furthermore, only a small amount of sample is required for measurement, so the sample can be injected into the cell using a dropper, for example, which is very easy to use.

[0014] Furthermore, even if an excess of the viscous sample to be measured, such as sake mash, is placed in the measurement cell, the thickness of the layer of the viscous sample will be reduced by inserting the adapter and reflector, causing the excess viscous sample to rise to the upper side of the measurement cell. However, if a notch is provided on the upper side of the adapter, the excess viscous sample will be contained in the notch. Therefore, there is no need to be too particular about the amount of viscous sample such as sake mash that is poured into the measurement cell, greatly improving workability.

[0015] As mentioned above, the sample layer thickness is thinned and measured using the reflected light method, so the layer thickness must be precisely adjusted. This is because the sample layer thickness is originally thin, so any error in layer thickness adjustment will have a significant effect on the measured value. For this reason, spring-loaded ball setscrews with high positioning performance are used in multiple places on the adapter. The spring-loaded ball setscrews constantly press the reflector, so the position of the reflector does not fluctuate and the layer thickness is kept constant.

[0016] Furthermore, for viscous samples such as sake mash, the layer thickness must be optimally adjusted according to the sample's properties, and the use of a spring-loaded ball set screw is also effective for this purpose. This is particularly important for samples such as sake mash, whose solubility changes over time, making it all the more important to optimally adjust the layer thickness to suit the sample's properties.

[0017] Furthermore, even if the same viscous sample such as sake mash is repeatedly taken in and out of the measurement cell and the absorbance spectrum is measured, the presence of a ball set screw will keep the sample layer thickness constant, thereby reducing variation in the absorbance spectrum.

[0018] Furthermore, since the sample is viscous, a slight pressure can be applied to the sample by adjusting the ball set screw using the reflector, which allows the sample to be filled more reliably into every corner of the narrow sample storage area, which also contributes to highly accurate analysis.

[0019] Furthermore, the measurement cell, adapter, and reflector all have smooth surfaces, making them easy to clean and preventing sticky liquids such as thick sake mash from getting into the small holes or porous structure, improving measurement accuracy. Furthermore, unlike porous ceramic sample holders, for example, it has durability. [Brief explanation of the drawings]

[0020] [Figure 1] 1 is an explanatory diagram of a measurement cell showing an embodiment of the present invention. [Figure 2] 1 is a diagram of an adapter showing an embodiment of the present invention. [Figure 3]10 is an explanatory diagram showing an embodiment of the present invention in which a reflector is supported from the adapter side by a ball set screw. FIG. [Figure 4] FIG. 1 is a schematic explanatory diagram showing a measurement cell of the present invention set in a near-infrared spectrometer. [Figure 5] 1 is an example of a near-infrared absorbance spectrum of sake mash in an example of the present invention. [Figure 6] 1 is an example of an absorbance spectrum of sake mash when a spring-loaded ball set screw is used in an embodiment of the present invention. [Figure 7] 10 is an example of the absorbance spectrum of sake mash when the spring-loaded ball set screw is removed from an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0021] Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. The embodiment is not limited to this embodiment, and can be appropriately modified within the scope of the present invention. FIG. 1 is a diagram of a measurement cell representing one embodiment of the present invention. (A) is a front view, (B) is a plan view, and (C) is a right side view.

[0022] The resin measurement cell 1 has a gap of approximately 12 mm in thickness and width, into which the thick, viscous sake mash sample is poured using, for example, a dropper. The approximately 12 mm gap allows for easy pouring. A resin adapter 2 and a 2 mm-thick reflector 4 are then inserted, and the gap between the inner surface of the glass surface 5 and the reflector 4—that is, the thickness of the measurement sample storage section 7—is approximately 2 mm. The adapter 2 has a notch 3 at the top for storing excess sake mash beyond what is needed for measurement. The adapter 2 also has a ball set screw 6 for adjusting the sake mash layer thickness during measurement, making it possible to adjust the layer thickness.

[0023] Near-infrared light is irradiated through a transparent glass window 5 provided in the measurement cell 1, passes through the sake mash to be measured that has been poured into the measurement sample container 7, is reflected by the reflector 4, and is sent to the near-infrared spectroscopic analysis section 16 via the optical fiber connector section 15 of the near-infrared spectroscopic analysis device 12 shown in Figure 4. The reflector 4 is a stainless steel plate with a shot blasted surface to diffuse and reflect light. However, it is not limited to stainless steel, and other metals can also be used.

[0024] The gap between the inner surface of the glass 5 and the reflector 4 can be adjusted by a spring-loaded ball screw 6 attached to the adapter 2. This is the layer thickness of the sake mash to be measured. 7 is the measurement sample holder.

[0025] After pouring sake mash into the approximately 12 mm gap in the measurement cell 1, the adapter 2 and reflector 4 are inserted. As mentioned above, the sake mash will form a layer approximately 2 mm thick, so any excess sake mash will rise to the top of the measurement cell 2 and be collected in the notch 3 in the adapter 2.

[0026] FIG. 2 shows the adapter 2, where (A) is a front view, (B) is a plan view, and (C) is a right side view. Pour sake mash into the measurement cell 1 up to the center, then insert the resin adapter 2 from above the measurement cell 1. This will diffuse the sake mash throughout the measurement cell 1, and then insert the reflector 4, allowing measurement. Two spring-loaded ball set screws 6 push the reflector from behind, keeping the distance from the inner surface of the glass of the measurement cell 1 constant. This in turn keeps the thickness of the sake mash layer to be measured precisely constant, reducing measurement error. Furthermore, in the case of sake mash, the state of the mucus changes over time depending on the state of dissolution, so it is advisable to be able to precisely adjust the layer thickness according to the state of the mucus.

[0027] Furthermore, the spring-loaded ball screw 6 can apply a slight pressure to the sake mash contained in the measurement sample container 7, thereby filling the measurement sample container 7 with sake mash to every corner. The notch 3 at the top acts as a reservoir to prevent overflow even if too much sake mash is poured into the measurement cell.

[0028] Figure 3 is an explanatory diagram showing how the reflector 4 is supported from the side of the adapter 2. (A) is a front view, and (B) is a left side view. A spring-loaded ball setscrew 6 is attached to the adapter 2, and the position of the ball 8 at the tip can be adjusted by turning the screw 17. The ball 8 is pressed by a spring 9, which presses and supports the reflector 4. The gap between the adapter 2 and the reflector 4 is, for example, about 0.5 mm. Ball set screws 6 are provided in two locations on the adapter 2. A glass plate 5 is attached to the measurement cell 1, and a measurement sample storage section 7 between the reflecting plate 4 and the glass plate 5 is filled with sake mash. The incident near-infrared light 10 is transmitted through the glass plate 5 and the layer of sake mash, reflected by the reflector 4, and passes through the glass plate 5 as reflected light 11, exiting the cell 1 and being sent to the near-infrared spectroscopic analysis section 16. The reflected light 11 is diffusely reflected by the diffusely reflective reflector 4.

[0029] 4 is a schematic explanatory diagram showing the measurement cell 1 set in a near-infrared spectroscopic analyzer 12. The near-infrared spectroscopic analyzer 12 houses the measurement cell 1 and comprises a light source 13, a cone-shaped optical chamber 14, an optical fiber connector 15, a near-infrared spectroscopic analysis unit 16, etc. The light reflected from the sake mash injected into the measurement sample storage section 7 passes through the optical fiber connector section 15 and enters the near-infrared spectroscopic analysis section 16, where it is spectroscopically analyzed at near-infrared wavelengths of 725 nm to 1050 nm, and data on the absorbance spectrum of the sake mash is obtained.

[0030] Figure 5 is an example of a graph of the absorbance spectrum of sake mash. The horizontal axis represents wavelength (unit: nm) and the vertical axis represents absorbance. Curve A is an example of measurement according to the present invention, in which the adapter 2 and reflector 4 are inserted into the measurement cell 1. Curve B is an example of measurement in which only the adapter 2 is inserted, without the reflector 4. Curve C is an example of measurement in which neither the adapter 2 nor the reflector 4 is inserted.

[0031] In the case of curve C, which is measured without inserting adapter 2 or reflector 4, the absorbance is clearly too high, and the measured values ​​become unstable when the same sample is repeatedly measured. In the case of curve B, where only adapter 2 is inserted and reflector 4 is not inserted, the absorbance becomes too low, and the measurement values ​​become unstable even when the same sample is measured repeatedly. In the end, curve A of the present invention, in which both the adapter 2 and the reflector 4 are inserted, has a moderate absorbance, the measured values ​​are the most stable in repeated measurements of the same sample, and the absorbance spectrum is the most stable.

[0032] FIG. 6 shows an example of the absorbance spectrum of sake mash in an example of the present invention. The horizontal axis represents the wavelength of near-infrared light (unit: nm), and the vertical axis represents absorbance. With the same sake mash placed in measurement cell 1, reflector 4 was removed for each measurement, and the mixture was stirred three times with adapter 2. Then, adapter 2 and reflector 4 were reinserted and the absorbance spectrum was measured. This process was repeated 10 times. As a result, as shown in graph A, there was almost no difference in the absorbance spectrum.

[0033] FIG. 7 shows an example of measuring the absorbance spectrum after removing the spring-loaded ball set screw 6 from the embodiment of the present invention. As in FIG. 6, the horizontal axis represents the wavelength of near-infrared light (unit: nm), and the vertical axis represents absorbance. Graph A is an example of the absorbance spectrum of sake mash. Graph B shows the absorbance spectrum measured with the same sake mash as in Graph A, but with reflector 4 removed and the mash stirred three times with adapter 2, and then with adapter 2 and reflector 4 reinserted. This was repeated 10 times, but there was a variation about the same as the width between graphs A and B.

[0034] Using the measurement cell of the present invention, a calibration curve is created from the absorbance spectrum data of multiple samples with different components, etc., and the corresponding chemical analysis data of the samples, such as alcohol content, sake meter value (or Baume), acidity, amino acid content, etc.

[0035] Furthermore, samples other than viscous samples such as sake mash, such as alcohol obtained by filtering it, can be measured without the measurement cell of the present invention, which requires the insertion of the adapter 2 and reflector 4, but can also be measured with the measurement cell of the present invention. In this case, there is also the advantage that less sample is required for measurement. [Industrial Applicability]

[0036] The present invention provides a measurement cell that enables viscous samples such as sake mash to be measured directly by near-infrared spectroscopy without filtration, which is extremely useful for quality control in food production and the like, and is highly applicable industrially. [Explanation of symbols]

[0037] 1 measuring cell 2 adapters 3 Adapter cutout 4 Reflector 5. Clear Glass 6 Ball set screw 7. Measurement sample storage section 8 Ball Set Screw Ball 9 Ball set screw spring 10 Incident light 11 Reflected light 12 Near-infrared spectrometer 13 Light source 14 Cone-type light chamber 15 Optical fiber connector 16 Near-infrared spectroscopy section 17 Threaded portion of ball set screw A, B, C absorbance spectra (A), (B), (C) Fig.

Claims

1. A measurement cell for near-infrared spectroscopic analysis, characterized in that it is a rectangular measurement container having a gap of a certain thickness and a transparent window portion for transmitting light on one side, and after a viscous sample to be measured is poured, an adapter is inserted into the gap of said thickness, and a reflector is inserted into the side of the adapter having the transparent window of the measurement container, so that a measurement sample holding portion for holding a part of the viscous sample to be measured after the pouring is provided between the surface of the transparent window of the measurement container on the gap portion of said thickness and the reflector.

2. 2. A measurement cell for near-infrared spectroscopic analysis according to claim 1, wherein the viscous sample to be measured is sake mash.

3. 3. The near-infrared spectroscopic analysis measuring cell according to claim 1, wherein a notch is provided on the upper side of the adapter in the longitudinal direction thereof for accommodating an excess sample other than the sample required for measurement.

4. 2. A measuring cell for near-infrared spectroscopic analysis according to claim 1, wherein spring-loaded ball set screws are provided at a plurality of positions on the adapter, and the reflector is supported by being pressed from the adapter side by the balls of the spring-loaded ball set screws.

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