JP2020122715A - Analysis method and method for preparing sample for the same - Google Patents

Abstract

To provide an analysis method capable of highly accurately analyzing an inorganic component including an alkaline inorganic component contained in an oyster with less effort and smaller risk in a short period of time, and a method for preparing a sample for analysis needed for the analysis.SOLUTION: Edible parts of an oyster are pulverized, nitric acid and hydrogen peroxide are respectively separately added to the edible parts to prepare a mixed solution, the mixed solution is stored in a sealable container to achieve a sealed state, the mixed solution is heated to 200°C or more by microwaves in the sealed state, internal pressure of the sealed state is made higher than atmospheric pressure, an elevated temperature of 200°C or more is kept in the sealed state for at least 15 minutes, the edible parts are acid-decomposed, a sample for analysis is prepared, and a plurality of inorganic components included in the sample for analysis are analyzed by an inductive coupling plasma emission spectral analysis method.SELECTED DRAWING: Figure 22

Description

The present invention relates to a method for analyzing the content of inorganic components of oysters and a method for preparing a sample thereof.

Oysters are rich in zinc, which is an essential mineral, and according to the United Nations Food and Agriculture Organization, oysters are a food of increasing importance in recent years, such as the promotion of aquaculture to counter the rapidly increasing population problem. It is known that oysters abundantly contain essential minerals such as sodium (Na), potassium (K), calcium (Ca), magnesium (Mg) in addition to zinc (Zn). Alkali metals and alkaline earth metals such as sodium, potassium, calcium, and magnesium are important elements for maintaining life activity, and it is very important to know their contents. However, conventionally, it takes a long time to measure an alkaline inorganic component such as an alkali metal or an alkaline earth metal, and an analysis method for highly accurately measuring an alkaline inorganic component in a short time is desired. ing.

The minerals contained in oysters are, according to the Japanese Food Standards Table 2015 Edition (7th Edition), mainly decomposed by the dry ashing method and then analyzed by atomic absorption method or inductively coupled plasma (ICP) emission spectroscopy. Has been analyzed. In the dry ashing method, the sample is generally ignited to about 500° C., which has a high risk of loss of inorganic components and is a time-consuming method.

For sample preparation for elemental analysis, a wet oxidation method is also known, which can be decomposed at a lower temperature and has less risk of loss of inorganic components. Regarding the wet oxidation method of oysters, Kjeldahl decomposition shown in Non-Patent Document 1 requires addition of sulfuric acid (H ₂ SO ₄ ) and perchloric acid (HClO ₄ ) in addition to nitric acid (HNO ₃ ). And, hydrogen peroxide is added later. Non-Patent Document 2 discloses a method of acid-decomposing by microwave using nitric acid and hydrochloric acid (HCl), perchloric acid, and fluoric acid (HF). All of them require the addition of three or more kinds of reagents, and use strong acids such as perchloric acid and fluoric acid, which are potentially explosive, and have the drawback of requiring careful handling. Especially, even if the concentration of fluoric acid is low, it penetrates the skin and bones of the human body, and there is a risk of chronic poisoning such as fluorosis. Quantitation is recommended. In Non-Patent Document 3, a sample for atomic absorption analysis is prepared by wet ashing using nitric acid, but since the details of the wet ashing method are not shown, is it possible to use only nitric acid? It is unclear whether reagents other than nitric acid were used.

Haruyoshi Onozuka, 4 others, “Trace Element Concentrations in Shellfish”, Tokyo Metropolitan Institute of Health Annual Report, Tokyo Metropolitan Institute of Health, 2002, No. 53, p. 253-257 Hirofumi Isoyama, 4 persons, “Determination of Trace Metals in Biological Samples by Inductively Coupled Plasma Atomic Emission Spectrometry with Discrete Nebulization after Microwave Decomposition)", Analytical Sciences, Japan Society for Analytical Chemistry, 1990, Volume 6, Issue 3, p.385-388 Nana Kobe, 5 others, "Body composition of oysters in different production areas", Micronutrient Research, Japan Society of Micronutrients, 2008, Vol. 25, p.125-128

The present invention has been made in view of the above problems, a short time and less labor, an analysis method capable of highly accurately analyzing an inorganic component including an alkaline inorganic component contained in oyster with a lower risk. And a method for preparing an analytical sample necessary for the analysis.

In order to achieve the above object, the first aspect of the present invention comprises (a) a step of pulverizing an edible portion of oysters, and (b) nitric acid and hydrogen peroxide are separately added to the edible portion and mixed. A step of preparing a solution, a step of (c) accommodating the mixed solution in a hermetically sealable container to realize a hermetically sealed state, and (d) a hermetically sealed state in which the mixed solution is heated to 200° C. or higher by microwave heating. A method for preparing a sample for analysis, comprising a step of preparing an analytical sample by increasing the internal pressure above atmospheric pressure, maintaining a temperature rising state of 200° C. or higher for at least 15 minutes in this sealed state, and subjecting the edible portion to acid decomposition The main point is.

In order to achieve the above-mentioned object, a second aspect of the present invention is to analyze the analytical sample prepared in the first aspect by using inductively coupled plasma (ICP) emission spectroscopy, The gist is that the method is an analysis method for carrying out the step of analyzing a plurality of inorganic components.

According to the present invention, an analysis method capable of highly accurately analyzing an inorganic component including an alkaline inorganic component contained in oyster in a short time and with less labor and a lower risk, and an analysis sample required for the analysis Can be provided.

3 is a flowchart of a method for preparing an analytical sample according to an embodiment of the present invention. 5 is a graph showing a temperature transition of the mixed solution at the time of microwave irradiation in Example 1. 3 is a graph showing the zinc concentration analyzed by the ICP emission spectroscopic analysis method according to the embodiment of the present invention for the analysis sample of the inorganic component according to Example 1 and Comparative Example 1. 3 is a graph showing the sodium concentration analyzed by the ICP emission spectroscopic analysis method according to the embodiment of the present invention with respect to the analysis samples of the inorganic components according to Example 1 and Comparative Example 1. 3 is a graph showing the potassium concentration analyzed by the ICP emission spectroscopic analysis method according to the embodiment of the present invention for the analysis sample of the inorganic component according to Example 1 and Comparative Example 1. 5 is a graph showing the calcium concentration analyzed by the ICP emission spectroscopic analysis method according to the embodiment of the present invention for the analysis samples of the inorganic components according to Example 1 and Comparative Example 1. 3 is a graph showing the magnesium concentration analyzed by the ICP emission spectroscopic analysis method according to the embodiment of the present invention with respect to the analysis sample of the inorganic component according to Example 1 and Comparative Example 1. 9 is a graph showing a temperature transition of a mixed solution at the time of microwave irradiation in Comparative Example 5. 9 is a graph showing a temperature transition of a mixed solution at the time of microwave irradiation in Comparative Example 7. 11 is a graph showing a temperature transition of the mixed solution at the time of microwave irradiation in Comparative Example 10. 13 is a graph showing a temperature transition of the mixed solution at the time of microwave irradiation in Comparative Example 12. It is a graph which shows the standard deviation of the analysis result of the zinc concentration in Example 2 and Comparative Examples 2-8. It is a graph which shows the standard deviation of the analysis result of the sodium concentration in Example 2 and Comparative Examples 2-8. It is a graph which shows the standard deviation of the analysis result of the potassium concentration in Example 2 and Comparative Examples 2-8. It is a graph which shows the standard deviation of the analysis result of the calcium concentration in Example 2 and Comparative Examples 2-8. It is a graph which shows the standard deviation of the analysis result of the magnesium concentration in Example 2 and Comparative Examples 2-8. It is a graph which shows the zinc concentration in Example 2 and Comparative Examples 2-8. It is a graph which shows the sodium concentration in Example 2 and Comparative Examples 2-8. It is a graph which shows the potassium concentration in Example 2 and Comparative Examples 2-8. It is a graph which shows the calcium concentration in Example 2 and Comparative Examples 2-8. It is a graph which shows the magnesium concentration in Example 2 and Comparative Examples 2-8. It is a flowchart of the analysis method which concerns on embodiment of this invention. It is a graph which shows the zinc concentration in Example 3 and Comparative Examples 9-13. It is a graph which shows the sodium concentration in Example 3 and Comparative Examples 9-13. It is a graph which shows the potassium concentration in Example 3 and Comparative Examples 9-13. It is a graph which shows the calcium concentration in Example 3 and Comparative Examples 9-13. It is a graph which shows the magnesium concentration in Example 3 and Comparative Examples 9-13. 9 is a graph showing a temperature transition of a mixed solution at the time of microwave irradiation in Example 3.

Embodiments of the present invention will be described below with reference to the drawings. In the following description of the drawings, the same or similar reference numerals are given to the same or similar parts. However, it should be noted that the drawings are schematic. Therefore, the specific decomposition method, component analysis method, and the like should be judged more variously in consideration of the purpose of the technical idea that can be understood from the following description.

The following embodiments of the present invention exemplify devices, materials, and methods for embodying the technical idea of the present invention, and the technical idea of the present invention is the material of the device and the material. The shapes, structures, arrangements, etc. are not specified below. The technical idea of the present invention is not limited to the contents described in the embodiments of the present invention, and various modifications are made within the technical scope defined by the organic combination of the matters specifying the invention described in the claims. Can be added.

(Method for preparing analytical sample)
As shown in the flowchart of FIG. 1, the method for preparing an analytical sample according to the embodiment of the present invention includes a homogenizing step of crushing the edible portion of the oyster in step S101, and a sealing step in step S101 in step S103. The edible part of crushed oysters is stored in a simple container, and nitric acid (HNO ₃ ) and hydrogen peroxide (H ₂ O ₂ ) are added to the edible part of crushed oysters to prepare a mixed solution. Then, in step S105, the container containing the mixed solution prepared in step S103 is covered and sealed, and then the prepared mixed solution is irradiated with microwaves and heated to 200° C. or higher to be sealed. The procedure involves a microwave irradiation step of preparing a sample for analysis by raising the internal pressure of the state above atmospheric pressure, maintaining the temperature rising state at 200° C. or higher for at least 15 minutes in this sealed state.

The homogenizing method in step S101 is not particularly specified, but since it is used for the analysis of inorganic components of alkali metals and alkaline earth metals, it is desirable to use a method that does not touch metal parts such as instruments and tools as much as possible. For example, when using a kitchen knife, it is better to avoid using a metal material such as stainless steel or titanium, and a non-metal material such as ceramic is preferable. The degree of homogenization may be such that, when several grams are arbitrarily collected as a sample, each part such as the scallop, intestine, esophagus, stomach, gills and the like of the edible portion of the oyster is uniformly contained. The "edible portion" of oyster in the present specification refers to all parts such as scallops and internal organs excluding the shell of oyster.

Nitric acid and hydrogen peroxide in step S103 is not mixed before the decomposition solution injection step, after storing the edible portion of the homogenized oysters in a sealable container, the oysters stored in the sealable container First, nitric acid and then hydrogen peroxide are added to the edible portion in this order as separate solutions and mixed for the first time. In step S103, nitric acid and hydrogen peroxide are used as decomposition solutions. After adding nitric acid and hydrogen peroxide as separate solutions to the edible portion of oyster in a sealable container, the mixed solution is composed of the homogenized edible portion of oyster, nitric acid and hydrogen peroxide. It is preferable that the volume ratio of nitric acid and hydrogen peroxide, which are decomposition solutions, be about 6:1. By way of example, with respect to about 2g sample (edible part), nitric acid 6 mL = 6 cm ^3, hydrogen peroxide is preferably used 1 mL = 1 cm ^3. The prepared mixed solution may be agitated or shaken in an airtight container, but without performing the operation, the airtight container may be capped to bring it into an airtight state and immediately proceed to the next step.

The "microwave" in step S105 is preferably a microwave of 2.45 GHz included in the frequency band in which water molecules vibrate and rotate. The microwave of 2.45 GHz can be generated by a high power oscillator such as a magnetron of 300 W to 10 kW which is easily available on the market. The output of the microwave generator is controlled so that the sample temperature of the mixed solution obtained in the decomposition liquid injection step is maintained at 200°C or higher in a closed state so that the sample temperature is kept in a closed state. Microwave heating is performed at 200° C. or higher for at least 15 minutes. Regarding microwave heating, preferably, the sample temperature is 200° C. to 240° C. for 30 minutes or more, more preferably the sample temperature is 210° C. to 235° C. for 25 minutes or more, and even more preferably 220. It is 20 minutes or more in the state of °C to 235 °C. The “sample temperature” in the present specification refers to the temperature of the mixed solution obtained in the decomposition solution injection step. A non-contact type thermometer such as a pyrometer or a contact type thermometer may be used for temperature measurement. In the examples described below, the temperature of the sample surface is measured by detecting infrared rays of the sample using a non-contact type radiation thermometer, but the measuring method is not limited to this.

It does not matter how long it takes for the sample temperature of the mixed solution to reach 200°C or higher, but the temperature rises stepwise, such as holding it for several minutes or more at either 150°C or 190°C or both of them. It is desirable to heat. The material of the container for containing the mixed solution for use in microwave heating is preferably a heat-resistant and pressure-resistant material capable of transmitting electromagnetic waves. For example, heat-resistant glass such as quartz glass, fluororesin, silicon resin, or the like. The material of the part that comes into direct contact with the mixed solution or the generated gas has a heat resistance temperature of 200°C or higher and chemical resistance, such as polytetrafluoroethylene (PTFE) or tetrafluoroethylene/perfluoroalkoxyethylene. Polymerized resin (PFA) and the like are preferable. The container (vessel, etc.) that directly contacts the mixed solution may be separated from the heat-resistant and pressure-resistant container that has the sealing function for housing the container, or the container itself that directly contacts the mixed solution may have the sealing function and the heat-resistant and pressure-resistant function. May have.

When the mixed solution becomes a solution containing nitric acid and hydrogen peroxide, salts and ions absorb the microwave energy more effectively, so that Joule heating by electromagnetic waves in a sealed container becomes possible, The heating efficiency is higher than in the case of pure water. According to Iwanami Shoten's Physics and Chemistry Dictionary 5th Edition (2004), the boiling point of pure nitric acid at atmospheric pressure (101.325 kPa) is 83°C, and the boiling point of an azeotropic mixture of water and nitric acid is 120.5°C. .. The boiling point of 90% hydrogen peroxide at atmospheric pressure is 141°C, and the boiling point of the azeotrope of water and hydrogen peroxide is 150.2°C. The mixed solution composed of the edible portion of oysters, nitric acid and hydrogen peroxide is heated in a closed container and becomes a high pressure state above atmospheric pressure, so that the boiling point rises and the liquid state state is maintained. As the microwave heating progresses, water in the mixture evaporates, and the concentration of various components changes, which causes a boiling point increase. However, the evaporated water is cooled in the upper part of the container in which the mixed solution is placed and sealed, and most of it becomes liquid again and returns to the mixed solution in the lower part of the container, so that the liquid component is completely evaporated from the mixed solution. Almost never. The decomposition of the edible portion of oysters proceeds under the closed state of reflux. The "sealed state" in the present specification means a state in which there is no exchange of substances inside and outside the container because there is no gap in the container. That is, the liquid itself of the mixed solution or the substance derived from the mixed solution such as volatilized gas can be maintained at a high pressure above atmospheric pressure so as not to leak out of the container, and the substance outside the container does not enter the container. Refers to. However, the container may be provided with a mechanism such as a safety valve of a pressure cooker in which a slight amount of generated gas is leaked in an excessive pressure state. After completion of microwave irradiation, the mixed solution is allowed to cool and cool, and diluted appropriately to obtain a sample for analysis of inorganic components. Although the method and time of cooling and cooling are not limited, for example, the sample for analysis can be prepared in a short time of about 50 minutes after the start of microwave irradiation.

The inorganic component analysis sample obtained according to the embodiment of the present invention is then subjected to elemental analysis of the inorganic components, particularly alkali metals and alkaline earth metals, by ICP emission spectroscopy or the like. Therefore, the sample needs to be acid-decomposed in the microwave irradiation step included in the method for preparing an analytical sample according to the embodiment of the present invention to the extent that it can contribute to elemental analysis. The sample temperature by microwave heating is important for sufficient acid decomposition. When the maximum temperature of the sample temperature of the mixed solution is about 150° C. or 190° C. in the closed state, acid decomposition is insufficient even if the heating time is lengthened, and variations in data are likely to occur in the subsequent elemental analysis. Microwave irradiation is required for at least 15 minutes at least at a sample temperature of 200° C. or more in a sealed state. Regarding microwave heating, preferably, the sample temperature in the liquid phase of the mixed solution is 200° C. to 240° C. for 30 minutes or more, and more preferably the sample temperature is 210° C. to 235° C. for 25 minutes or more. Yes, and even more preferably, at a temperature of 220°C to 235°C for 20 minutes or more. As for the heating method, microwave heating, which is the internal heating method, is used instead of the external heating method to efficiently heat, thereby enabling heating that achieves a pressure higher than atmospheric pressure in a closed tube (sealed container). The presence of the liquid phase of the mixed solution can be maintained at a temperature above the boiling point at atmospheric pressure. Since microwave heating is an internal heating method, the temperature of the mixed solution in the closed tube can be raised in a short time, and acid decomposition of the edible portion of oysters can be performed in a short time.

(Inorganic component analysis method)
The analysis method according to the embodiment of the present invention, as shown in the flowchart of FIG. 22, a homogenizing step of crushing the oyster edible portion in step S101, and the oyster edible portion in a sealable container in step S103. Store, further, a decomposition solution injection step of preparing a mixed solution by adding nitric acid and hydrogen peroxide to the edible portion of the oyster in the hermetically-sealed container, and capping the hermetically-sealed container in step S105, A microwave irradiation step of preparing a sample for analysis by irradiating the mixed solution with microwaves in a sealed state and rapidly heating to 200° C. or higher and maintaining a temperature rising state of 200° C. or higher in the sealed state for at least 15 minutes; In step S107, the edible portion of oysters is taken out from the sealable container as a sample for analysis, and a procedure including ICP emission spectroscopy for analyzing a plurality of inorganic components contained in the sample for analysis is followed. That is, in the analysis method according to the embodiment of the present invention, an ICP emission spectroscopic analysis is performed on the analysis sample obtained by the flowchart showing the method for preparing the analysis sample shown in FIG. 1 to analyze a plurality of inorganic components. Is the way.

In the ICP emission spectroscopic analysis according to the embodiment of the present invention, a plurality of alkali metals such as sodium and potassium, and alkaline earth metals such as calcium and magnesium, which are contained in the inorganic components which have conventionally been difficult to measure in a short time, are included. Elements can be simultaneously analyzed with high accuracy in a short time. Conventionally, in the case of using acid treatment under atmospheric pressure using a reagent such as step S103, alkali-based inorganic components such as alkali metal and alkaline earth metal are lost by reaction with acid, and alkali-based However, there is a problem that it becomes difficult to detect the inorganic component. However, in the ICP emission spectroscopic analysis according to the embodiment of the present invention, the reaction by nitric acid and hydrogen peroxide molecules in a high energy state at a temperature higher than the boiling point of atmospheric pressure is performed by the microwave rapid heating in the closed state of step S105. Since it is used, the alkaline inorganic component is less likely to be lost, so that the alkaline inorganic component can be analyzed with high accuracy and in a short time. It is also possible to analyze zinc. It is also possible to analyze elements other than alkali metals, alkaline earth metals and zinc.

By performing the homogenization step of step S101, the decomposition liquid injection step of step S103, and the microwave irradiation step in a high pressure state in a closed tube of step S105, the reaction with high-energy molecules is performed, and alkali metal or alkaline earth metal It is possible to decompose the edible portion of oyster with less reagent and with less risk, without losing alkaline inorganic components such as. Further, by performing the ICP emission spectral analysis shown in step S107 on the obtained analytical sample, there is less variation in the data for inorganic components, particularly for alkali metals and alkaline earth metals such as sodium, potassium, calcium, and magnesium. Highly accurate analysis results can be obtained in a short time.

Hereinafter, the present invention will be specifically described with reference to Examples, but this is merely for the purpose of illustration, and the present invention includes the trade names, production areas, purchase destinations, and the like shown in the following Examples. It is not limited to these examples.
[Example 1]

(Uniformization step)
For the oysters used as the raw material for the method for preparing the sample for analysis of the present invention, commercially available oysters from Miyagi Prefecture (scientific name: Crassostrea gigas) were obtained, stored in a freezer, and thawed before use. The edges of the two thawed oyster shells were cut with food scissors, a ceramic spatula was inserted into the gap between the two shells, and the mouth of the shell was opened. Next, the edible part of the oyster was separated from the shell using a spatula. The edible portion was pulverized with a food mixer (trade name: food processor 1.0 L, DLC-100J, manufactured by Quiginate Co., Ltd.; the same applies below) to homogenize the edible portion. The homogenized edible portion of the oyster was obtained in a wet weight of about 50 to 60 g.

(Decomposition liquid injection step)
About 2 g (wet weight) of the edible portion of the homogenized oyster was weighed and placed in a vessel, and subsequently nitric acid (concentration 69 to 70%, for precision analysis, manufactured by Kanto Chemical Co., Inc.; the same applies hereinafter) in this vessel. A mixed solution was prepared by adding 6 mL and 1 mL of hydrogen peroxide (concentration: 30.0%, for atomic absorption, manufactured by Kanto Chemical Co., Inc.; the same below) first in the order of nitric acid and then hydrogen peroxide. A total of 3 samples of the mixed solution were prepared, and the edible portion of the oyster in each sample was 2.47 g, 2.13 g, and 2.26 g. The color of the mixed solution was yellowish brown.

(Microwave irradiation step)
The lid of the vessel of each sample was closed, the vessel was stored in a heat-resistant and pressure-resistant container capable of being hermetically sealed, and the heat-resistant and pressure-resistant container was capped with a dedicated tool to seal the heat-resistant and pressure-resistant container. It was set in a microwave oven (trade name: microwave sample decomposing device, manufactured by Analytic Queena Japan Co., Ltd.; the same applies below) and irradiated with microwaves. The heating program for the microwave oven is as follows. That is, 10 minutes after the start of microwave irradiation to the heat-resistant pressure-resistant container, the temperature is raised to 150° C., the temperature is kept at 150° C. for 5 minutes, the temperature is raised to 190° C. for 10 minutes thereafter, and the temperature is kept at 190° C. for 5 minutes. In the subsequent 10 minutes, the temperature was raised to 230° C., the temperature was maintained at 230° C. for 20 minutes, and the microwave irradiation treatment on the heat resistant and pressure resistant container was finished. The relationship between the microwave irradiation time and the actual sample temperature transition is as shown in FIG. 2, and it can be seen that the temperature raising process is performed almost according to the temperature raising program. Regarding the sample temperature according to Example 1, the temperature was 200° C. or higher for 32 minutes, 210° C. or higher for 25 minutes, 220° C. or higher for 20 minutes, and the maximum temperature was 231° C. As shown in FIG. 2, for a few minutes after the start of microwave irradiation, the lower limit of sample temperature detection in the microwave oven is 50° C., and the deviation of the temperature in the sample occurs due to the deviation of the microwave irradiation. Therefore, the sample temperature is not stable. A few minutes after the start of microwave irradiation, microwave heating progresses and the movement of molecules in the sample is activated, so that temperature deviation is less likely to occur in the sample, and the detected sample temperature value is stable. Turn into. After the microwave irradiation was finished, the mixture was allowed to cool for 10 minutes, immersed in water at 5° C. or less for cooling for about 30 minutes to 1 hour, and then the vessel was taken out from the heat and pressure resistant vessel. With respect to each sample in the vessel, ultrapure water having a specific resistance of 18 MΩ·cm or more at 25° C. (for example, ultrapure water prepared by Q-POD (registered trademark) device manufactured by Merck Millipore, Inc.; the same applies below) was measured to a volume of 50 mL. Up to a total of 3 samples were obtained as samples for analysis of inorganic components according to Example 1. The color of the solution of the sample for analysis of the inorganic component according to Example 1 was colorless and transparent.

(ICP emission spectroscopy)
The sample for analysis of the inorganic component according to Example 1 was diluted 10 times with ultrapure water, yttrium (Y) as an internal standard substance was added to a final concentration of 2 ppm, and an ICP emission spectrophotometer (ICPE- 9820, manufactured by Shimadzu Corporation, the same applies hereinafter), and the content of zinc (Zn) was analyzed. In addition, the sample for analysis of the inorganic component according to Example 1 was diluted 100 times with ultrapure water, and yttrium (Y) as an internal standard substance was added so as to have a final concentration of 2 ppm. Each content of sodium (Na) and potassium (K), calcium (Ca), and magnesium (Mg) was analyzed by the apparatus.

The average value of the analysis results of the inorganic component according to Example 1 is 9.0 mg of zinc, 486.1 mg of sodium, 250.8 mg of potassium, 156.7 mg of calcium, and magnesium per 100 g (wet weight) of the edible portion. Was 69.0 mg. The standard deviation of each data (except the table, the figures are rounded off to three significant figures and the same applies to the following), zinc is 0.0378, sodium is 0.679, potassium is 3.35, and calcium is 31. 8, magnesium was 0.798.
[Comparative Example 1]

Using the same raw material as in Example 1, after the homogenization step according to Example 1 of the present invention, about 2 g (wet weight) of the edible portion of the homogenized oyster was weighed and placed in a vessel, followed by nitric acid. 6 mL was added to prepare a mixed solution according to Comparative Example 1. A total of 3 samples of the mixed solution according to Comparative Example 1 were prepared, and the edible portion of the oyster in each sample according to Comparative Example 1 was 2.08 g, 2.39 g, and 2.29 g. After the vessel was housed in a heat and pressure resistant container, the heat resistant and pressure resistant container was covered to realize a hermetically sealed state. For each sample, a microwave irradiation step was performed on the heat and pressure resistant container according to Example 1 of the present invention to obtain a total of 3 samples for analysis of inorganic components according to Comparative Example 1. In the microwave irradiation step, the actual sample temperature transition was almost the same as that in FIG. The maximum temperature of the sample temperature according to Comparative Example 1 was 233°C. The color of the solution of the sample for analysis of the inorganic component according to Comparative Example 1 was colorless and transparent. The analysis sample of the inorganic component according to Comparative Example 1 was subjected to the ICP emission spectroscopic analysis according to Example 1 of the present invention to measure the inorganic component.

The average value of the analysis results of the inorganic component according to Comparative Example 1 is 9.2 mg of zinc, 491.3 mg of sodium, 248.9 mg of potassium, 138.9 mg of calcium, and 138.9 mg of magnesium per 100 g (wet weight) of the edible portion. Was 69.1 mg. The standard deviation of each data was 0.543 for zinc, 15.2 for sodium, 7.42 for potassium, 55.1 for calcium, and 3.06 for magnesium.

3 to 7, the vertical axis indicates the concentration of each inorganic component (mg/per 100 g of edible portion), and the bar graph with the diagonal line to the left that is located at the leftmost is the Japanese Food Standards Table 2015 version (7th edition). Concentration of each inorganic component of "raw oyster" in Fig. 3, the white bar graph in the center is the concentration of each inorganic component in Comparative Example 1, and the bar graph in the rightmost diagonal line with the downward sloping line is each inorganic substance in Example 1. The component concentration is shown. The vertical widths of the I-shaped bars on the upper ends of the bar graphs of Comparative Example 1 and Example 1 of FIGS. 3 to 7 visually represent the standard deviation. However, the bar graphs of Example 1 in FIGS. 3 and 4 were omitted because the standard deviation was too small to show the width.

The average values and standard deviations of the concentrations of the respective inorganic components of the samples for analyzing the inorganic components according to Example 1 and Comparative Example 1 are shown in Table 1 below. In the top row of Table 1, "Zn" indicates zinc, "Na" indicates sodium, "K" indicates potassium, "Ca" indicates calcium, and "Mg" indicates magnesium. The same applies to Tables 2 and 3 below.

According to FIGS. 3 to 7 and Table 1, the dispersion of data in Example 1 in which hydrogen peroxide was added as a decomposition solution was higher than that in Comparative Example 1 at all component concentrations of zinc, sodium, potassium, calcium, and magnesium. It can be seen that the standard deviation representing is small. That is, Example 1 has a higher accuracy as an analysis method and higher reliability than Comparative Example 1.

According to Example 1, the quantitative analysis of alkali metal and alkaline earth metal in the oyster sample can be carried out in a shorter time than in the prior art and at the same time with high accuracy. In particular, the method is suitable for quantitative analysis of four kinds of elements such as sodium, potassium, calcium and magnesium. In Example 1, since a strong acid such as perchloric acid or fluoric acid, which has a risk of explosion, is not used, it is possible to perform the analysis more safely with less labor.
[Example 2]

(Uniformization step)
As the oysters used as a raw material for the method for preparing the sample for analysis of the present invention, commercially available oysters from Akita Prefecture (scientific name: Crossostrea nippona) were obtained, stored in a freezer, and thawed before use. The edges of the thawed two oyster shells were cut with food scissors, a ceramic spatula was inserted into the gap between the two shells, and the mouth of the shell was opened. Next, the edible part of the oyster was separated from the shell using a spatula. The edible portion was crushed with a food mixer to make the edible portion uniform. About 50 to 60 g of the homogenized edible oyster was obtained by wet weight.

(Decomposition liquid injection step)
About 2 g (wet weight) of the homogenized edible oyster was weighed and placed in a vessel, followed by nitric acid (6 mL and hydrogen peroxide 1 mL, first nitric acid and then hydrogen peroxide, in this order, mixed solution. A total of 3 samples of the mixed solution were prepared, and the edible parts of oysters in each sample were 1.67 g, 1.85 g, and 1.50 g. It was

(Microwave irradiation step)
The lid of the vessel of each sample was closed, the vessel was stored in a heat-resistant pressure-resistant container, and the heat-resistant pressure-resistant container was closed by using a dedicated tool to cover the heat-resistant pressure-resistant container. It was set in a microwave oven and irradiated with microwaves. The heating program for the microwave oven is as follows. That is, the temperature is raised to 150° C. in 10 minutes after the start of microwave irradiation, kept at 150° C. for 5 minutes, raised to 190° C. in the subsequent 10 minutes, and kept at 190° C. for 5 minutes. In the subsequent 10 minutes, the temperature was raised to 230° C., the temperature was maintained at 230° C. for 20 minutes, and the irradiation treatment was finished. The relationship between the microwave irradiation time and the actual sample temperature transition is as shown in FIG. 28, and it can be seen that the temperature raising process is performed almost according to the temperature raising program. Regarding the sample temperature according to Example 2, the temperature was 200° C. or higher for 35 minutes, 210° C. or higher for 28 minutes, 220° C. or higher for 23 minutes, and the maximum temperature was 233° C. After the microwave irradiation was finished, the mixture was allowed to cool for 10 minutes, soaked in water at 5° C. or lower together with the heat-resistant pressure-resistant container taken out, cooled for about 30 minutes to 1 hour, and then the vessel was taken out from the heat-resistant pressure-resistant container. Each sample in the vessel was made up to 50 mL with ultrapure water to obtain a total of 3 samples for analysis of inorganic components according to Example 2. The color of the solution of the sample for analysis of the inorganic component according to Example 2 was colorless and transparent.

(ICP emission spectroscopy)
The sample for analysis of the inorganic component according to Example 2 was diluted 10-fold with ultrapure water, yttrium (Y) as an internal standard substance was added so as to have a final concentration of 2 ppm, and zinc was analyzed with an ICP emission spectrometer. The content of (Zn) was analyzed. In addition, the sample for analysis of the inorganic component according to Example 2 was diluted 100 times with ultrapure water, yttrium (Y) as an internal standard substance was added so that the final concentration was 2 ppm, and ICP emission spectroscopy analysis was performed in the same manner. Each content of sodium (Na) and potassium (K), calcium (Ca), and magnesium (Mg) was analyzed by the apparatus.

The average value of the analysis results of the inorganic components according to Example 2 is 24.1 mg of zinc, 676.1 mg of sodium, 91.7 mg of potassium, 85.3 mg of calcium, and magnesium per 100 g (wet weight) of the edible portion. Was 91.1 mg. The standard deviation of each data was 0.0292 for zinc, 2.92 for sodium, 0.292 for potassium, 0.219 for calcium, and 0.386 for magnesium.
[Comparative example 2]

Using the same raw material as in Example 2, after the homogenizing step according to Example 2 of the present invention, about 2 g (wet weight) of the edible part of the homogenized oyster was weighed and placed in a vessel, and then nitric acid was added. 6 mL was added to prepare a mixed solution according to Comparative Example 2. A total of 3 samples of the mixed solution according to Comparative Example 2 were prepared, and the edible portion of oysters in each sample according to Comparative Example 2 was 1.87 g, 2.41 g, and 2.34 g. The microwave irradiation step according to Example 2 of the present invention was performed on each sample to obtain a total of 3 samples for analysis of inorganic components according to Comparative Example 2. In the microwave irradiation step, the actual sample temperature transition was almost the same as in FIG. The maximum temperature of the sample temperature according to Comparative Example 2 was 233°C. The color of the solution of the sample for analysis of the inorganic component according to Comparative Example 2 was colorless and transparent. The analysis sample of the inorganic component according to Comparative Example 2 was subjected to ICP emission spectroscopic analysis according to Example 2 of the present invention to measure the inorganic component.

The average value of the analysis results of the inorganic components according to Comparative Example 2 is 43.9 mg of zinc, 764.3 mg of sodium, 97.3 mg of potassium, and 1.030.3 mg of calcium per 100 g (wet weight) of the edible portion. , Magnesium was 85.1 mg. The standard deviation of each data was 4.10 for zinc, 61.9 for sodium, 0.156 for potassium, 677 for calcium and 0.158 for magnesium.
[Comparative Example 3]

Using the same raw materials as in Example 2, the mixed solution according to Comparative Example 3 was prepared through the homogenization step and the decomposition solution injection step according to Example 2 of the present invention. A total of 3 samples of the mixed solution according to Comparative Example 3 were prepared, and the edible portions of oysters in each sample according to Comparative Example 3 were 1.66 g, 1.53 g, and 1.63 g. Microwave irradiation was not performed on each sample, and the mixed solution according to Comparative Example 3 was made up to 50 mL with ultrapure water to obtain a total of 3 samples for analysis of inorganic components according to Comparative Example 3. The color of the solution of the sample for analysis of the inorganic component according to Comparative Example 3 was yellowish brown. The analysis sample of the inorganic component according to Comparative Example 3 was subjected to ICP emission spectroscopic analysis according to Example 2 of the present invention to measure the inorganic component.

The average value of the analysis results of the inorganic components according to Comparative Example 3 is 27.1 mg of zinc, 602.4 mg of sodium, 101.0 mg of potassium, and 1,841.6 mg of calcium per 100 g (wet weight) of the edible portion. And magnesium was 44.4 mg. The standard deviation of each data was 0.343 for zinc, 17.0 for sodium, 3.46 for potassium, 746 for calcium, and 5.21 for magnesium.
[Comparative Example 4]

Using the same raw material as in Example 2, after the homogenizing step according to Example 2 of the present invention, about 2 g (wet weight) of the edible part of the homogenized oyster was weighed and placed in a vessel, and then nitric acid was added. 6 mL was added to prepare a mixed solution according to Comparative Example 4. A total of 3 samples of the mixed solution according to Comparative Example 4 were prepared, and the edible portions of oysters in each sample according to Comparative Example 4 were 1.66 g, 1.56 g, and 1.56 g. Microwave irradiation was not performed on each sample, and the mixed solution according to Comparative Example 4 was made up to 50 mL with ultrapure water to obtain a total of 3 samples for analysis of inorganic components according to Comparative Example 4. The color of the solution of the sample for analysis of the inorganic component according to Comparative Example 4 was yellowish brown. The analysis sample of the inorganic component according to Comparative Example 4 was subjected to the ICP emission spectroscopic analysis according to Example 2 of the present invention to measure the inorganic component.

The average value of the analysis results of the inorganic components according to Comparative Example 4 is 28.8 mg of zinc, 619.7 mg of sodium, 102.4 mg of potassium, and 122.8 mg of calcium per 100 g (wet weight) of the edible portion. And magnesium was 54.0 mg. The standard deviation of each data was 1.78 for zinc, 1.99 for sodium, 0.970 for potassium, 930 for calcium and 15.3 for magnesium.
[Comparative Example 5]

The same raw material as in Example 2 was used to prepare a mixed solution according to Comparative Example 5 through the homogenization step and the decomposition solution injection step according to Example 2 of the present invention. A total of 3 samples of the mixed solution according to Comparative Example 5 were prepared, and the edible parts of oysters in each sample according to Comparative Example 5 were 2.13 g, 1.66 g, and 2.01 g. The lid of the vessel of each sample was closed, the vessel was stored in a heat and pressure resistant container, and the heat and pressure resistant container was closed by using a special tool to cover the heat and pressure resistant container. It was set in a microwave oven and irradiated with microwaves. The heating program for the microwave oven is as follows. That is, the temperature was raised to 150° C. in 10 minutes after the start of microwave irradiation, maintained at 150° C. for 5 minutes, and the irradiation treatment was finished. The relationship between the microwave irradiation time and the actual sample temperature transition is as shown in FIG. 8, and it can be seen that the temperature raising process is performed almost according to the temperature raising program. The maximum sample temperature of Comparative Example 5 was 143°C. After the microwave irradiation was finished, the mixture was allowed to cool for 10 minutes, immersed in water at 5° C. or less for cooling for about 30 minutes to 1 hour, and then the vessel was taken out from the heat and pressure resistant vessel. Each sample in the vessel was made up to 50 mL with ultrapure water to obtain a total of 3 samples for analysis of inorganic components according to Comparative Example 5. The color of the solution of the sample for analysis of the inorganic component according to Comparative Example 5 was light yellow-green and transparent. The analysis sample of the inorganic component according to Comparative Example 5 was subjected to the ICP emission spectroscopic analysis according to Example 2 of the present invention to measure the inorganic component.

The average value of the analysis result of the inorganic component according to Comparative Example 5 is 27.4 mg of zinc, 610.0 mg of sodium, 100.8 mg of potassium, 275.1 mg of calcium, and magnesium per 100 g (wet weight) of the edible portion. Was 73.4 mg. The standard deviation of each data was 0.329 for zinc, 16.9 for sodium, 3.19 for potassium, 99.2 for calcium, and 3.28 for magnesium.
[Comparative Example 6]

Using the same raw material as in Example 2, after the homogenizing step according to Example 2 of the present invention, about 2 g (wet weight) of the edible part of the homogenized oyster was weighed and placed in a vessel, and then nitric acid was added. A mixed solution according to Comparative Example 6 was prepared by adding 6 mL. A total of 3 samples of the mixed solution according to Comparative Example 6 were prepared, and the edible parts of oysters in each sample according to Comparative Example 6 were 1.67 g, 1.54 g, and 1.56 g. The microwave irradiation step according to Comparative Example 5 of the present invention was performed on each sample to obtain a total of 3 samples for analysis of inorganic components according to Comparative Example 6. In the microwave irradiation step, the actual sample temperature transition was almost the same as in FIG. The maximum sample temperature according to Comparative Example 6 was 150°C. The color of the solution of the sample for analysis of the inorganic component according to Comparative Example 6 was light yellow-green and transparent. Regarding the sample for analysis of the inorganic component according to Comparative Example 6, the ICP emission spectral analysis according to Example 2 of the present invention was performed to measure the inorganic component.

The average value of the analysis results of the inorganic components according to Comparative Example 6 is 28.2 mg of zinc, 592.9 mg of sodium, 97.1 mg of potassium, 143.5 mg of calcium, and magnesium per 100 g (wet weight) of the edible portion. Was 80.1 mg. The standard deviation of each data was 0.305 for zinc, 3.23 for sodium, 1.31 for potassium, 12.9 for calcium, and 0.697 for magnesium.
[Comparative Example 7]

Using the same raw materials as in Example 2, the mixed solution according to Comparative Example 7 was prepared through the homogenization step and the decomposition liquid injection step according to Example 2 of the present invention. A total of 3 samples of the mixed solution according to Comparative Example 7 were prepared, and the edible portion of the oyster in each sample according to Comparative Example 7 was 1.90 g, 2.30 g, and 1.94 g. The lid of the vessel of each sample was closed, the vessel was stored in a heat and pressure resistant container, and the heat and pressure resistant container was closed by using a special tool to cover the heat and pressure resistant container. It was set in a microwave oven and irradiated with microwaves. The heating program for the microwave oven is as follows. That is, the temperature is raised to 150° C. in 10 minutes after the start of microwave irradiation, kept at 150° C. for 5 minutes, raised to 190° C. in the subsequent 10 minutes, kept at 190° C. for 5 minutes, and the irradiation treatment is finished. Met. The relationship between the microwave irradiation time and the actual sample temperature transition is as shown in FIG. 9, and it can be seen that the temperature raising process is performed almost according to the temperature raising program. The maximum sample temperature of Comparative Example 7 was 191°C. After the microwave irradiation was finished, the mixture was allowed to cool for 10 minutes, immersed in water at 5° C. or less for cooling for about 30 minutes to 1 hour, and then the vessel was taken out from the heat and pressure resistant vessel. Each sample in the vessel was made up to 50 mL with ultrapure water to obtain a total of 3 samples for analysis of inorganic components according to Comparative Example 7. The color of the solution of the analysis sample of the inorganic component according to Comparative Example 7 was light yellow-green and transparent, which was lighter than the color of the solution of the analysis sample of the inorganic component according to Comparative Examples 5 and 6. The analysis sample of the inorganic component according to Comparative Example 7 was subjected to ICP emission spectroscopic analysis according to Example 2 of the present invention to measure the inorganic component.

The average value of the analysis results of the inorganic components according to Comparative Example 7 is 31.8 mg of zinc, 605.6 mg of sodium, 99.1 mg of potassium, 214.8 mg of calcium, and 214.8 mg of magnesium per 100 g (wet weight) of the edible portion. Was 73.0 mg. The standard deviation of each data was 1.03 for zinc, 3.03 for sodium, 1.33 for potassium, 16.3 for calcium, and 1.47 for magnesium.
[Comparative Example 8]

Using the same raw material as in Example 2, after the homogenizing step according to Example 2 of the present invention, about 2 g (wet weight) of the edible part of the homogenized oyster was weighed and placed in a vessel, and then nitric acid was added. 6 mL was added to prepare a mixed solution according to Comparative Example 8. A total of 3 samples of the mixed solution according to Comparative Example 8 were prepared, and the edible parts of oysters in each sample according to Comparative Example 8 were 1.89 g, 1.62 g, and 1.69 g. The microwave irradiation step according to Comparative Example 7 of the present invention was performed on each sample to obtain a total of 3 samples of the inorganic component analysis samples according to Comparative Example 8. In the microwave irradiation step, the actual sample temperature transition was almost the same as in FIG. The maximum sample temperature according to Comparative Example 8 was 190°C. The color of the solution of the analysis sample of the inorganic component according to Comparative Example 8 was colorless and transparent, and was lighter than the color of the solution of the analysis sample of the inorganic component according to Comparative Examples 5 and 6. The analysis sample of the inorganic component according to Comparative Example 8 was subjected to ICP emission spectroscopic analysis according to Example 2 of the present invention to measure the inorganic component.

The average value of the analysis results of the inorganic components according to Comparative Example 8 is 30.0 mg of zinc, 589.3 mg of sodium, 98.8 mg of potassium, 295.1 mg of calcium, and magnesium per 100 g (wet weight) of the edible portion. Was 70.1 mg. The standard deviation of each data was 0.216 for zinc, 23.6 for sodium, 3.73 for potassium, 77.2 for calcium, and 1.84 for magnesium.

17 to 21, the vertical axis represents the content of each inorganic component (component concentration, mg/100 g of the edible portion), and the horizontal axis represents the maximum program temperature (° C.) during microwave irradiation. The four white circles in FIGS. 17 to 21 indicate the component concentrations and the maximum temperatures of Comparative Example 4, Comparative Example 6, Comparative Example 8, and Comparative Example 2, in order from the left of each figure, and the four black circles. Shows the component concentrations and maximum temperatures of Comparative Example 3, Comparative Example 5, Comparative Example 7, and Example 2 in order from the left of each figure. Since Comparative Examples 3 and 4 in FIGS. 17 to 21 having a maximum temperature of around 20° C. are comparative examples in which the microwave irradiation step is not performed, “20 (° C.)” which is room temperature is shown as the maximum temperature.

12 to 16, the vertical axis represents the standard deviation, and the horizontal axis represents the maximum program temperature (° C.) during microwave irradiation. 12 to 16 show the standard deviations of Comparative Example 4, Comparative Example 6, Comparative Example 8 and Comparative Example 2 in order from the left side of the figures, and the bar charts with diagonally downward-sloping lines from the left side of each figure. The standard deviations of Comparative Example 3, Comparative Example 5, Comparative Example 7, and Example 2 are shown in order. Since Comparative Examples 3 and 4 shown in the two bar graphs of the maximum temperature of 20° C. in FIGS. 12 to 16 are comparative examples in which the microwave irradiation step is not performed, the room temperature “20 (° C.)” is set as the maximum temperature. Indicated.

Table 2 below shows average values and standard deviations of the concentrations of the respective inorganic components of the samples for analyzing the inorganic components according to Example 2 and Comparative Examples 2 to 8.

12 to 16, for Example 2, Comparative Example 3, Comparative Example 5, and Comparative Example 7 in which hydrogen peroxide was added as a decomposition liquid, the higher the maximum program temperature during microwave irradiation, the higher It can be seen that the standard deviation tends to be small for the components. According to FIGS. 12 to 16, for Comparative Example 2, Comparative Example 4, Comparative Example 6, and Comparative Example 8 in which hydrogen peroxide was not added as a decomposition liquid, a remarkable tendency due to a change in the maximum temperature of the program temperature during microwave irradiation. Is not particularly seen. 12 to 16 and Table 2, comparing Example 2 and Comparative Example 2 in which the highest program temperature is 230° C., the standard deviation of Example 2 is smaller than that of potassium and magnesium. Regarding potassium and magnesium, the standard deviations of Example 2 are about twice as large as those of Comparative Example 2.

In Comparative Example 7 in which the maximum program temperature during microwave irradiation is 190° C., the standard deviation of the zinc concentration is larger than in Comparative Example 3 in which the same temperature is 20° C. and Comparative Example 5 in which the same temperature is 150° C. In Comparative Example 7, acid decomposition during microwave irradiation is insufficient.
[Example 3]

(Uniformization step)
As the oysters used as a raw material for the method for preparing the sample for analysis of the present invention, commercially available oysters from Miyagi Prefecture were obtained, stored in a freezer, and thawed before use. The edges of the two thawed oyster shells were cut with food scissors, a ceramic spatula was inserted into the gap between the two shells, and the mouth of the shell was opened. Next, the edible part of the oyster was separated from the shell using a spatula. The edible portion was crushed with a food mixer to make the edible portion uniform. The homogenized edible portion of the oyster was obtained in a wet weight of about 50 to 60 g.

(Decomposition liquid injection step)
Approximately 2 g (wet weight) of the homogenized edible oyster was weighed and placed in a vessel, and then 6 mL of nitric acid and 1 mL of hydrogen peroxide were added first in the order of nitric acid and then hydrogen peroxide to form a mixed solution. Prepared. A total of 3 samples of the mixed solution were prepared, and the edible portion of the oyster in each sample was 1.91 g, 2.33 g, and 2.11 g. The color of the mixed solution was yellowish brown.

(Microwave irradiation step)
The lid of the vessel of each sample was closed, the vessel was stored in a heat and pressure resistant container, and the heat and pressure resistant container was closed by using a special tool to cover the heat and pressure resistant container. It was set in a microwave oven and irradiated with microwaves. The heating program for the microwave oven is as follows. That is, the temperature is raised to 150° C. in 10 minutes after the start of microwave irradiation, kept at 150° C. for 5 minutes, raised to 190° C. in the subsequent 10 minutes, and kept at 190° C. for 5 minutes. In the subsequent 10 minutes, the temperature was raised to 230° C., the temperature was maintained at 230° C. for 20 minutes, and the irradiation treatment was finished. In the microwave irradiation step, the actual sample temperature transition is almost the same as that in FIG. 2, and it can be seen that the temperature raising process is performed almost according to the temperature raising program. Regarding the sample temperature according to Example 3, the temperature was 200° C. or higher for 34 minutes, 210° C. or higher for 28 minutes, 220° C. or higher for 23 minutes, and the maximum temperature was 232° C. After the microwave irradiation was finished, the mixture was allowed to cool for 10 minutes, immersed in water at 5° C. or less for cooling for about 30 minutes to 1 hour, and then the vessel was taken out from the heat and pressure resistant vessel. Each sample in the vessel was made up to 50 mL with ultrapure water to obtain a total of 3 samples for analysis of inorganic components according to Example 3. The color of the solution of the sample for analysis of the inorganic component according to Example 3 was colorless and transparent.

(ICP emission spectroscopy)
The sample for analysis of the inorganic component according to Example 3 was diluted 10-fold with ultrapure water, yttrium (Y) as an internal standard substance was added so as to have a final concentration of 2 ppm, and zinc was measured with an ICP emission spectrometer. The content of (Zn) was analyzed. In addition, the sample for analysis of the inorganic component according to Example 3 was diluted 100-fold with ultrapure water, yttrium (Y) as an internal standard substance was added so that the final concentration was 2 ppm, and ICP emission spectroscopy analysis was performed in the same manner. Each content of sodium (Na) and potassium (K), calcium (Ca), and magnesium (Mg) was analyzed by the apparatus.

The average value of the analysis results of the inorganic components according to Example 3 is 13.4 mg of zinc, 635.3 mg of sodium, 50.5 mg of potassium, 382.7 mg of calcium, and magnesium per 100 g (wet weight) of the edible portion. Was 256.3 mg. The standard deviation of each data was 0.123 for zinc, 13.2 for sodium, 1.97 for potassium, 6.21 for calcium and 1.73 for magnesium.
[Comparative Example 9]

Using the same raw material as in Example 3, after performing the homogenizing step according to Example 3 of the present invention, about 2 g (wet weight) of the edible portion of the homogenized oyster was weighed and placed in a vessel, followed by nitric acid. 6 mL was added to prepare a mixed solution according to Comparative Example 9. A total of 3 samples of the mixed solution according to Comparative Example 9 were prepared, and the edible portion of the oyster in each sample according to Comparative Example 9 was 2.13 g, 2.10 g, and 2.31 g. The microwave irradiation step according to Example 3 of the present invention was performed on each sample to obtain a total of 3 samples for analysis of inorganic components according to Comparative Example 9. In the microwave irradiation step, the actual sample temperature transition was almost the same as that in FIG. The maximum sample temperature according to Comparative Example 9 was 232°C. The color of the solution of the sample for analysis of the inorganic component according to Comparative Example 9 was colorless and transparent. The analysis sample of the inorganic component according to Comparative Example 9 was subjected to ICP emission spectroscopic analysis according to Example 3 of the present invention to measure the inorganic component.

The average value of the analysis results of the inorganic component according to Comparative Example 9 is 13.5 mg of zinc, 630.5 mg of sodium, 53.2 mg of potassium, 346.0 mg of calcium, and magnesium per 100 g (wet weight) of the edible portion. Was 258.5. The standard deviation of each data was 0.284 for zinc, 6.87 for sodium, 2.67 for potassium, 3.35 for calcium, and 2.89 for magnesium.
[Comparative Example 10]

Using the same raw materials as in Example 3, the mixed solution according to Comparative Example 10 was prepared through the homogenization step and the decomposition liquid injection step according to Example 3 of the present invention. A total of 3 samples of the mixed solution according to Comparative Example 10 were prepared, and the edible portion of the oyster in each sample according to Comparative Example 10 was 2.37 g, 1.65 g, and 1.94 g. The lid of the vessel of each sample was closed, the vessel was stored in a heat and pressure resistant container, and the heat and pressure resistant container was closed by using a special tool to cover the heat and pressure resistant container. It was set in a microwave oven and irradiated with microwaves. The heating program for the microwave oven is as follows. That is, the temperature was raised to 150° C. in 10 minutes after the start of microwave irradiation, maintained at 150° C. for 50 minutes, and the irradiation treatment was finished. The relationship between the microwave irradiation time and the actual sample temperature transition is as shown in FIG. 10, and it can be seen that the temperature raising process is performed almost according to the temperature raising program. The maximum sample temperature of Comparative Example 10 was 152°C. After the microwave irradiation was finished, the mixture was allowed to cool for 10 minutes, immersed in water at 5° C. or less for cooling for about 30 minutes to 1 hour, and then the vessel was taken out from the heat and pressure resistant vessel. Each sample in the vessel was made up to 50 mL with ultrapure water to obtain a total of 3 samples for analysis of inorganic components according to Comparative Example 10. The color of the solution of the sample for analysis of the inorganic component according to Comparative Example 10 was light yellow-green and transparent. The analysis sample of the inorganic component according to Comparative Example 10 was subjected to ICP emission spectroscopic analysis according to Example 3 of the present invention to measure the inorganic component.

The average value of the analysis result of the inorganic components according to Comparative Example 10 is 9.8 mg of zinc, 459.4 mg of sodium, 43.0 mg of potassium, 504.8 mg of calcium, and magnesium per 100 g (wet weight) of the edible portion. Was 265.5 mg. The standard deviation of each data was 0.492 for zinc, 31.1 for sodium, 9.78 for potassium, 144 for calcium, and 3.00 for magnesium.
[Comparative Example 11]

Using the same raw material as in Example 3, after the homogenizing step according to Example 3 of the present invention, about 2 g (wet weight) of the edible portion of the homogenized oyster was weighed and placed in a vessel, and then nitric acid was added. 6 mL was added to prepare a mixed solution according to Comparative Example 11. A total of 3 samples of the mixed solution according to Comparative Example 11 were prepared, and the edible portion of the oyster in each sample according to Comparative Example 11 was 1.77 g, 1.70 g, and 1.66 g. The microwave irradiation step according to Comparative Example 10 of the present invention was performed on each sample to obtain a total of 3 samples of the inorganic component analysis samples according to Comparative Example 11. In the microwave irradiation step, the actual sample temperature transition was almost the same as in FIG. The maximum sample temperature according to Comparative Example 11 was 152°C. The color of the solution of the sample for analysis of the inorganic component according to Comparative Example 11 was light yellow-green and transparent. With respect to the sample for analyzing the inorganic component according to Comparative Example 11, the ICP emission spectral analysis according to Example 3 of the present invention was performed to measure the inorganic component.

The average value of the analysis result of the inorganic components according to Comparative Example 11 is 10.2 mg of zinc, 480.5 mg of sodium, 57.8 mg of potassium, 426.6 mg of calcium, and magnesium per 100 g (wet weight) of the edible portion. Was 251.7 mg. The standard deviation of each data was 0.626 for zinc, 29.5 for sodium, 5.85 for potassium, 76.0 for calcium, and 15.7 for magnesium.
[Comparative Example 12]

Using the same raw materials as in Example 3, the mixed solution according to Comparative Example 12 was prepared through the homogenization step and the decomposition liquid injection step according to Example 3 of the present invention. A total of 3 samples of the mixed solution according to Comparative Example 12 were prepared, and the edible portion of the oyster in each sample according to Comparative Example 12 was 2.05 g, 1.93 g, and 2.04 g. The lid of the vessel of each sample was closed, the vessel was stored in a heat and pressure resistant container, and the heat and pressure resistant container was closed by using a special tool to cover the heat and pressure resistant container. It was set in a microwave oven and irradiated with microwaves. The heating program for the microwave oven is as follows. That is, the temperature is raised to 150° C. in 10 minutes after the start of microwave irradiation, kept at 150° C. for 5 minutes, raised to 190° C. in the subsequent 10 minutes, kept at 190° C. for 35 minutes, and the irradiation treatment is finished. Met. The relationship between the microwave irradiation time and the actual sample temperature transition is as shown in FIG. 11, and it can be seen that the temperature raising process is performed almost according to the temperature raising program. The maximum temperature of the sample temperature according to Comparative Example 12 was 193°C. After the microwave irradiation was finished, the mixture was allowed to cool for 10 minutes, immersed in water at 5° C. or less for cooling for about 30 minutes to 1 hour, and then the vessel was taken out from the heat and pressure resistant vessel. Each sample in the vessel was made up to 50 mL with ultrapure water to obtain a total of 3 samples for analysis of inorganic components according to Comparative Example 12. The color of the solution of the analysis sample of the inorganic component according to Comparative Example 12 was light yellow-green and transparent, which was lighter than the color of the solution of the analysis sample of the inorganic component according to Comparative Examples 10 and 11. For the sample for analysis of the inorganic component according to Comparative Example 12, the ICP emission spectral analysis according to Example 3 of the present invention was performed to measure the inorganic component.

The average value of the analysis results of the inorganic components according to Comparative Example 12 is 10.3 mg of zinc, 447.0 mg of sodium, 52.6 mg of potassium, 339.2 mg of calcium, and magnesium per 100 g (wet weight) of the edible portion. Was 265.0 mg. The standard deviation of each data was 0.265 for zinc, 16.4 for sodium, 7.05 for potassium, 60.8 for calcium, and 13.8 for magnesium.
[Comparative Example 13]

Using the same raw material as in Example 3, after the homogenizing step according to Example 3 of the present invention, about 2 g (wet weight) of the edible portion of the homogenized oyster was weighed and placed in a vessel, and then nitric acid was added. 6 mL was added to prepare a mixed solution according to Comparative Example 13. A total of 3 samples of the mixed solution according to Comparative Example 13 were prepared, and the edible portion of the oyster in each sample according to Comparative Example 13 was 1.82 g, 1.87 g, and 2.18 g. The microwave irradiation step according to Comparative Example 12 of the present invention was performed on each sample to obtain a total of 3 samples of the inorganic component analysis samples according to Comparative Example 13. In the microwave irradiation step, the actual sample temperature transition was almost the same as in FIG. The maximum sample temperature of Comparative Example 13 was 193°C. The color of the solution of the analysis sample of the inorganic component according to Comparative Example 13 was light yellow-green and transparent, which was lighter than the color of the solution of the analysis sample of the inorganic component according to Comparative Examples 10 and 11. The analysis sample of the inorganic component according to Comparative Example 13 was subjected to the ICP emission spectroscopic analysis according to Example 3 of the present invention to measure the inorganic component.

The average value of the analysis results of the inorganic components according to Comparative Example 13 is 9.6 mg of zinc, 594.1 mg of sodium, 52.3 mg of potassium, 413.1 mg of calcium, and magnesium per 100 g (wet weight) of the edible portion. Was 188.8 mg. The standard deviation of each data was 0.305 for zinc, 213 for sodium, 3.91 for potassium, 111 for calcium, and 56.3 for magnesium.

23 to 27, the vertical axis represents the content of each inorganic component (component concentration, mg/100 g of edible portion), and the horizontal axis represents the maximum program temperature (° C.) during microwave irradiation. The three white circles in FIGS. 23 to 27 indicate the component concentrations and the maximum temperatures of Comparative Example 11, Comparative Example 13, and Comparative Example 9 in order from the left of each figure, and the three black circles are the respective figures. The component concentrations and maximum temperatures of Comparative Example 10, Comparative Example 12, and Example 3 are shown in order from the left. Regarding Example 3 and Comparative Example 9 in FIG. 23, Example 3 and Comparative Example 9 in FIG. 24, Comparative Example 12 and Comparative Example 13 in FIG. 25, and Example 3 and Comparative Example 9 in FIG. Since the white circles and the black circles overlap in close proximity, only the black circles appear to be shown.

The average values and standard deviations of the concentrations of the respective inorganic components of the samples for analyzing the inorganic components according to Example 3 and Comparative Examples 9 to 13 are shown in Table 3 below.

From Table 3, for Example 3, Comparative Example 10 and Comparative Example 12 in which hydrogen peroxide was added as a decomposition liquid, the higher the maximum program temperature during microwave irradiation, the smaller the standard deviation of each inorganic component. It turns out that there is a tendency to become. In Table 3, comparing Example 3 and Comparative Example 9 in which the highest temperature is 230° C., the standard deviation is smaller in Example 3 except for sodium and calcium. Regarding sodium and calcium as well, the standard deviations of Example 3 are within the range of numerical values within twice as compared with Comparative Example 9.

In Comparative Example 12 in which the maximum program temperature during microwave irradiation is 190° C., the standard deviation of the magnesium concentration is larger than in Comparative Example 10 in which the maximum temperature is 150° C. In Comparative Example 12, acid decomposition during microwave irradiation is insufficient.

The types of oysters that are found in the Japanese market and are mainly edible are oysters (Crassostrea) such as oysters and oysters. According to the analysis method of the present invention, the content of inorganic components of oysters such as oysters and oysters, particularly alkali metals and alkaline earth metals, can be simultaneously analyzed with high accuracy and in a short time. Further, according to the method for preparing an analytical sample of the present invention, a sample for simultaneous analysis of the inorganic components of oysters of oysters and oysters, especially the contents of alkali metals and alkaline earth metals with high accuracy in a short time is prepared. can do.

(Other embodiments)
As described above, the present invention has been described by the above-mentioned single embodiment, a plurality of examples, etc., but it should be understood that the discussion and drawings forming a part of this disclosure limit the present invention. Absent. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

As described above, it goes without saying that the present invention includes various embodiments and the like not described here. Therefore, the technical scope of the present invention is defined only by the matters specifying the invention according to the claims, which can be construed as appropriate from the above description.

S101: homogenization step, S103: decomposition solution injection step, S105: microwave irradiation step, S107: inductively coupled plasma emission spectroscopy

Claims (6)

Crushing the edible portion of oysters,
A step of preparing a mixed solution by separately adding nitric acid and hydrogen peroxide to the edible portion,
Storing the mixed solution in a sealable container to realize a sealed state,
The mixed solution is microwave-heated to 200° C. or higher in the closed state, the internal pressure of the closed state is made higher than the atmospheric pressure, and the temperature rising state of 200° C. or higher is maintained in the closed state for at least 15 minutes. And a step of preparing a sample for analysis by decomposing the edible portion with an acid, the method for preparing a sample for analysis. The method for preparing an analytical sample according to claim 1, wherein the temperature of the temperature rising state is 200° C. to 240° C., and the time of the temperature rising state is 30 minutes or more. The method for preparing an analytical sample according to claim 1 or 2, wherein the volume ratio of the nitric acid to the hydrogen peroxide is 6:1. Crushing the edible portion of oysters,
A step of preparing a mixed solution by separately adding nitric acid and hydrogen peroxide to the edible portion,
Storing the mixed solution in a sealable container to realize a sealed state,
In the hermetically sealed state, the mixed solution is microwave heated to 200° C. or higher, the internal pressure of the hermetically sealed state is made higher than atmospheric pressure, and the temperature rising state of 200° C. or higher is maintained in the hermetically sealed state for at least 15 minutes. An analysis method comprising: a step of acid-decomposing an edible portion to prepare a sample for analysis; and a step of analyzing a plurality of inorganic components contained in the sample for analysis by inductively coupled plasma optical emission spectroscopy. The analysis method according to claim 4, wherein the temperature of the temperature rising state is 200°C to 240°C, and the time of the temperature rising state is 30 minutes or more. The analytical method according to claim 4 or 5, wherein the volume ratio of the nitric acid to the hydrogen peroxide is 6:1.

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