Reagent kit, its applications, and methods for indicating temperature and time using it

Abstract

This invention relates to the field of environmental monitoring, specifically to a reagent kit, its application, and a method for indicating temperature and time using it. The reagent kit comprises a composite gel and ascorbic acid; wherein the composite gel is placed in a transparent container. The reagent kit has a simple structure, is inexpensive to manufacture, has stable properties, is portable, and suitable for environmental monitoring of individually packaged products, enabling simultaneous and accurate indication of time and temperature.

Description

Technical Field

[0001] This invention relates to the field of environmental monitoring, specifically to a reagent kit, its application, and a method for indicating temperature and time using it. Background Technology

[0002] As food safety becomes an increasingly important concern, product quality has become a focal point. However, besides strict control over the production process, the transportation and storage of products still require close monitoring. This is because most foods, pharmaceuticals, and biological products typically have specific environmental requirements for transportation and storage; prolonged exposure to high temperatures can easily lead to spoilage. Unlike the rotting of fruits and vegetables, the freshness of some products, such as yogurt, honey, seafood, and biological samples, is not easily determined by visual inspection, making it impossible to intuitively predict whether they have spoiled or become inactive. Consuming spoiled products not only fails to provide their original nutritional value but can also lead to food poisoning, seriously endangering human health. Although most product packaging indicates a sale date or expiration date, these expiration dates are usually estimated based on several simplified assumptions, such as the product being kept at a suitable temperature. Therefore, the shelf life is not the sole criterion for identifying whether a product has spoiled. However, temperature fluctuations during food handling, distribution, transportation, and storage are unavoidable. Therefore, researching and designing time-temperature response sensors for environmental monitoring is of great significance for food and drug safety.

[0003] Currently, a series of sensors for indicating time and temperature have been developed, such as electronic sensing devices made using thermal sensors and temperature recorders, which can closely track changes in ambient temperature. However, digital devices are usually complex in structure and expensive, making them unsuitable for monitoring the ambient temperature of individually packaged products. Enzyme-catalyzed sensors based on thermosensitive enzymes, which rely on color changes caused by the catalytic reaction between the enzyme and its substrate, can effectively reduce costs, but the problem of enzyme inactivation limits the application of this type of sensor. Daniela et al. proposed using irreversible thermochromic benzocyanine dyes to replace biological enzymes for temperature response. However, these methods all indicate time and temperature through color, inevitably leading to information overlap and hindering information reading.

[0004] Therefore, there is an urgent need to develop a product that is simple in structure, inexpensive, stable in properties, and can accurately indicate time and temperature. Summary of the Invention

[0005] The purpose of this invention is to overcome the aforementioned problems in the prior art, and to provide a reagent kit, its application, and a method for indicating temperature and time using it. The reagent kit has a simple structure, low cost, stable properties, and is portable. It can simultaneously and accurately indicate time and temperature, and is suitable for indicating the ambient temperature and elapsed time of individually packaged products.

[0006] To achieve the above objectives, the present invention provides a kit comprising a composite gel and ascorbic acid; wherein the composite gel is placed in a transparent container.

[0007] A second aspect of the invention provides the application of the kit described above in indicating temperature and time.

[0008] A third aspect of the present invention provides a method for indicating temperature T and time x in a reagent kit as described above, the method comprising:

[0009] When the ascorbic acid is added to the composite gel, at a temperature T, after a time x, a discoloration segment appears in the composite gel;

[0010] Temperature T and time x are determined by the color and length of the color-changing segment;

[0011] Where 0≤T≤80℃.

[0012] The present invention can achieve the following beneficial effects:

[0013] The reagent kit provided by this invention has a simple structure, low cost, stable properties, and is portable, making it suitable for indicating the ambient temperature and elapsed time of individually packaged products. Furthermore, because the reagent kit provides separate expression of time and temperature, it avoids errors caused by the same signal output, thus providing more accurate and reliable indications of time and temperature. Attached Figure Description

[0014] Figure 1a It refers to the color of the color-changing segments at different temperatures in Test Example 1;

[0015] Figure 1b It refers to the color and length of the color-changing segment at different temperatures in Test Example 1;

[0016] Figure 1c These are the extinction spectra of the composite gel at different temperatures in Test Example 1;

[0017] Figure 2a The test example 2 shows the color and length of the color-changing segments at different times.

[0018] Figure 2b This refers to the change in the length of the color-changing segment over time in Test Example 2;

[0019] Figure 3aIt refers to the color and length of the discoloration segments with different agarose contents in Test Example 3;

[0020] Figure 3b This shows the change in the length of the discoloration segment with the agarose content in test example 3;

[0021] Figure 4a The color and length of the discoloration segment in test example 4 with different chloroauric acid contents;

[0022] Figure 4b This shows the change in the length of the discoloration segment as a function of chloroauric acid content in test example 4.

[0023] Figure 5a The test results show the color and length of the discoloration segments at different ascorbic acid concentrations in Example 5.

[0024] Figure 5b This is the change in the length of the discoloration segment as a function of ascorbic acid concentration in test example 5;

[0025] Figure 6a The color and length of the discolored segments after different temperatures and times in Test Example 6;

[0026] Figure 6b This refers to the changes in the color and length of the discolored segment in Test Example 6 as a function of temperature and time.

[0027] Figure 6c This refers to the change in the length of the color-changing segment over time at different temperatures in Test Example 6;

[0028] Figure 7a The test results show the color and length of the discoloration segments after different times at 5℃ in Example 7.

[0029] Figure 7b The test results show the color and length of the discoloration segment after different times at 25°C in Example 7.

[0030] Figure 8a This refers to the color change segment in Test Example 8, where the temperature changes from 5°C to 25°C.

[0031] Figure 8b This is a comparison of the color change segments in Test Example 8 when the temperature is changed from 5°C to 25°C and when the temperature is directly at 25°C. Detailed Implementation

[0032] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0033] In a first aspect, the present invention provides a kit comprising a composite gel and ascorbic acid; wherein the composite gel is placed in a transparent container.

[0034] According to the present invention, the transparent container is not particularly limited and can be any conventional choice in the art. Preferably, the transparent container is an acrylic tube with a diameter of 4-10 mm. The length of the transparent container is not particularly limited and only needs to be sufficient to accommodate the composite gel.

[0035] It is understood that in the kit, the composite gel and ascorbic acid are stored in separate packages. When it is necessary to monitor the ambient temperature and the duration of maintenance at that temperature, the two are mixed together, thereby allowing for free control at the moment when monitoring temperature and time begins, avoiding waste of materials.

[0036] According to the present invention, preferably, the composite gel comprises agarose and chloroauric acid dispersed in the agarose.

[0037] According to the present invention, in order to indicate time and temperature more accurately, the content of chloroauric acid is preferably 0.01-10% (e.g., 0.01%, 0.05%, 0.1%, 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%) based on the mass of the composite gel.

[0038] According to the present invention, in order to more accurately indicate time and temperature, preferably, the content of chloroauric acid is 0.1-4% based on the mass of the composite gel.

[0039] According to the present invention, preferably, the method for preparing the composite gel includes: preparing an agarose solution under heating and stirring conditions, then adding a chloroauric acid solution to the agarose solution, mixing evenly, then injecting it into a transparent container, and cooling to obtain the composite gel.

[0040] The heating temperature is not particularly limited, but preferably, the heating temperature is 60-90℃ (for example, it can be 60℃, 65℃, 70℃, 75℃, 80℃, 85℃, or 90℃).

[0041] The stirring speed is not particularly limited, but preferably, the stirring speed is 300-500 r / min (for example, it can be 300 r / min, 350 r / min, 400 r / min, 450 r / min, or 500 r / min).

[0042] More preferably, the composite gel is prepared by dissolving agarose powder in deionized water, heating at 70-85°C, and stirring at 350-460 r / min until the powder is completely dissolved. Once the solution is clear and transparent, chloroauric acid solution is added while still hot, and the mixture is stirred vigorously until homogeneous. The hot mixture is then poured into an acrylic tube and allowed to cool and gel.

[0043] According to the present invention, the concentration of ascorbic acid is not particularly limited, but is determined by the ability to cause the composite gel to change color. Preferably, the concentration of ascorbic acid is 10-1000 mmol / L (e.g., 10 mmol / L, 50 mmol / L, 100 mmol / L, 150 mmol / L, 200 mmol / L, 300 mmol / L, 400 mmol / L, 500 mmol / L, 600 mmol / L, 700 mmol / L, 800 mmol / L, 900 mmol / L, 1000 mmol / L).

[0044] Secondly, the present invention provides the application of the kit described above in indicating temperature and time.

[0045] The specific application method is not particularly limited. For example, the kit can be used directly to indicate temperature and time, or the kit can be made into a sensor and then used to indicate temperature and time.

[0046] It is understood that the application scenarios are not particularly limited. For example, the kit can be applied to the detection of temperature and time during the storage and transportation of food or medicine.

[0047] Thirdly, the present invention provides a method for indicating temperature T and time x using the reagent kit described above, the method comprising:

[0048] When the ascorbic acid is added to the composite gel, at a temperature T, after a time x, a discoloration segment appears in the composite gel;

[0049] Temperature T and time x are determined by the color and length of the color-changing segment;

[0050] Where 0≤T≤80℃.

[0051] It is understandable that 80°C is generally not a temperature that storage environments will reach during the storage and transportation of food or medicine. Therefore, the above temperature range is sufficient to test the environmental conditions for the storage and transportation of conventional food or medicine.

[0052] It is understandable that when ascorbic acid comes into contact with chloroauric acid in the composite gel, the following reaction will occur:

[0053] 2AuCl4 - +3C6H8O6=2Au+8Cl - +3C6H6O6+6H +

[0054] With Au 3+ Gradually reduced to nano-gold (Au), the nano-gold grows within the composite gel. The inventors of this invention discovered that the color-changing segments exhibit different macroscopic colors at different temperatures, thus allowing them to determine the temperature T. Furthermore, the nano-gold can be fully and uniformly dispersed and fixed on the composite gel, preventing aggregation due to instability. The color of the already formed color-changing segments is irreversible, remaining stable and unchanged. It is understood that at the same temperature T, the longer the time x, the longer the formed color-changing segment. Moreover, if ascorbic acid is added to the composite gel and subjected to different temperatures, the color-changing segments formed earlier are unaffected by those formed later.

[0055] The inventors of this invention discovered in their research that the absorption peak of the composite gel changes under different ambient temperatures. As the temperature increases, the absorption peak shifts from around 600 nm to around 525 nm, indicating a blue shift. Therefore, as the temperature rises, the color of the color-changing segment gradually transitions from blue to purple, and then gradually to red. For example, at 0°C, the color of the color-changing segment is blue and remains unchanged; at 80°C, the color of the color-changing segment is red and remains unchanged.

[0056] According to the present invention, in order to enable the color-changing segment to extend in only one direction and thus to indicate time more accurately, the method preferably further includes: adding the ascorbic acid from top to bottom to the composite gel.

[0057] According to the present invention, a preferred method for determining temperature T includes comparing the color of the color-changing segment with a colorimetric card to determine temperature T. It is understood that color-changing segments appearing at different temperatures exhibit different macroscopic colors. Therefore, this can be utilized by preparing a colorimetric card corresponding to temperature and color in advance, and comparing the color-changing segment with the colorimetric card to obtain the ambient temperature T.

[0058] According to the present invention, preferably, the method further includes: substituting the length of the discoloration segment into the diffusion equation at temperature T to obtain time x;

[0059] The diffusion equation is as follows:

[0060] y = y0 + A|xx c | P

[0061] Where y is the length of the color-changing segment (mm), x is the time (h), and y0, x c A and P are parameters that vary with temperature;

[0062] Wherein, when the concentration of the ascorbic acid is 80-150 mmol / L, and the content of the chloroauric acid is 0.25-0.4% based on the mass of the composite gel, and when 0≤T≤60℃, the parameters y0, x c The relationships between A and P and temperature T are as follows:

[0063]

[0064] The applicant of this application, through nonlinear fitting of the relationship between the length of the color-changing segment and time at different temperatures, found that this relationship is consistent with the power0 equation, that is, the length y of the color-changing gel segment at different temperatures T has the above power function relationship with time x, and its coefficient of determination R 2 The value can reach above 0.997, indicating that the relationship obtained by the above nonlinear fitting is relatively reliable.

[0065] The present invention will be described in detail below through embodiments. In the following embodiments, the grade or model and manufacturer of the main drugs and instruments are shown in Tables 1 and 2, respectively.

[0066] Table 1

[0067]

[0068]

[0069] Table 2

[0070]

[0071] Example 1

[0072] Dissolve 80 mg of agarose powder in 9.5 mL of deionized water. Heat and stir at 80 °C (420 rpm) until the powder is completely dissolved and the solution is clear and transparent. While still hot, add 500 μL of 20 mmol / L HAuCl4 solution and stir vigorously until the two are thoroughly mixed. Next, pour the hot mixture into an acrylic tube and allow it to cool and gel. Store the resulting composite gel at room temperature until needed.

[0073] The acrylic tubes used all have a diameter of 4mm and a length of 20cm.

[0074] The agarose content is 0.8% and the chloroauric acid content is 0.34% by mass of the composite gel.

[0075] The ascorbic acid and the composite gel are stored separately, and the concentration of the ascorbic acid is 100 mmol / L.

[0076] Ascorbic acid and the composite gel are encapsulated in a kit, which is denoted as S.

[0077] Example 2

[0078] The kit was prepared according to the method of Example 1, except that the agarose content was 0.4% based on the mass of the composite gel, and the kit was designated as AG-0.4.

[0079] Example 3

[0080] The kit was prepared according to the method of Example 1, except that the agarose content was 1.2% based on the mass of the composite gel, and the kit was designated as AG-1.2.

[0081] Example 4

[0082] The kit was prepared according to the method of Example 1, except that the agarose content was 1.6% based on the mass of the composite gel, and the kit was designated as AG-1.6.

[0083] Example 5

[0084] The kit was prepared according to the method of Example 1, except that the agarose content was 2.0% based on the mass of the composite gel, and the kit was designated as AG-2.0.

[0085] Example 6

[0086] The kit was prepared according to the method of Example 1, except that the content of chloroauric acid was 0.034% based on the mass of the composite gel, and the kit was designated as CA-0.034.

[0087] Example 7

[0088] The kit was prepared according to the method of Example 1, except that the content of chloroauric acid was 0.17% based on the mass of the composite gel, and the kit was designated as CA-0.17.

[0089] Example 8

[0090] The kit was prepared according to the method of Example 1, except that the content of chloroauric acid was 1.7% based on the mass of the composite gel, and the kit was designated as CA-1.7.

[0091] Example 9

[0092] The kit was prepared according to the method of Example 1, except that the content of chloroauric acid was 3.4% based on the mass of the composite gel, and the kit was designated as CA-3.4.

[0093] Example 10

[0094] The kit was prepared according to the method of Example 1, except that the concentration of ascorbic acid was 10 mmol / L, and the kit was designated as AA-10.

[0095] Example 11

[0096] The kit was prepared according to the method of Example 1, except that the concentration of ascorbic acid was 50 mmol / L, and the kit was designated as AA-50.

[0097] Example 12

[0098] The kit was prepared according to the method of Example 1, except that the concentration of ascorbic acid was 500 mmol / L, and the kit was designated as AA-500.

[0099] Example 13

[0100] The kit was prepared according to the method of Example 1, except that the concentration of ascorbic acid was 1000 mmol / L, and the kit was designated as AA-1000.

[0101] Comparative Example 1

[0102] The kit was prepared according to the method of Example 1, except that the ascorbic acid was replaced with the reducing agent sodium citrate, and the kit was designated as D-1.

[0103] Test Example 1

[0104] Nine kits from Example 1 were used. One kit did not contain ascorbic acid in the composite gel (designated as the Blank group). The ascorbic acid from the other eight kits was added to the composite gel from top to bottom. The kits were then placed at 0°C, 5°C, 15°C, 25°C, 37°C, 50°C, 65°C, and 80°C, respectively. After 3 hours, the color of the discoloration segment was observed. Figure 1a As shown. The composite gels were subjected to temperatures of 0℃, 5℃, 15℃, 25℃, 37℃, and 50℃ for 3 hours. The length of the discoloration segment was observed. Figure 1b As shown. The extinction spectrum of the composite gel was tested at 50℃, as shown. Figure 1c .

[0105] Figure 1aIn the Blank group, no color change occurred. From 0℃ to 80℃, the color of the color-changing segment gradually transitioned from blue to purple, and then gradually to red. At 80℃, the color-changing segment was essentially red. Therefore, different temperatures can result in different color-changing segments, and thus the corresponding temperature can be determined by the color of the color-changing segment.

[0106] Figure 1b Color changes and Figure 1a The changes are consistent throughout. Furthermore, when the time is consistently 3 hours, the length of the color-changing segment at higher temperatures is longer than that at lower temperatures. This is because higher temperatures increase the molecular motion rate, leading to a faster downward diffusion of ascorbic acid. Therefore, different temperature environments correspond to different time x and color-changing segment length y relationships, i.e., diffusion equations. Once the temperature T is determined, the corresponding diffusion equation at that temperature can be found. Substituting y into the diffusion equation yields the elapsed time x.

[0107] Therefore, the kit of Example 1 can be used to determine temperature T and time x.

[0108] Test Example 2

[0109] Take 6 kits from Example 1, add ascorbic acid from top to bottom to the composite gel, and incubate at 25°C for 1h, 2h, 3h, 4h, 5h, and 6h respectively. Observe the length γ and color of each discoloration segment. Figure 2a and Figure 2b As shown.

[0110] Figure 2a In the image, all six color-changing segments exhibit the same color, a bluish-purple hue. As time progresses, the length y of each color-changing segment gradually increases. From... Figure 2b As can be seen, at a given temperature T, the length y of the gel color-changing segment is positively correlated with time x. Therefore, time x can be determined by the length y of the color-changing segment.

[0111] Test Example 3

[0112] Take the kits from Examples 1-5, add ascorbic acid from top to bottom to the composite gel, and incubate at 25°C for 1 hour. Observe the length γ and color of each discoloration segment. Figure 3a and Figure 3b As shown.

[0113] Figure 3a In the middle, when the agarose content is low, the color of the color-changing segment is slightly lighter, but not noticeably. Overall, all five speed-changing segments show a bluish-purple color with no significant difference. Figure 3bAs can be seen, the color-changing segment length y is slightly longer when the agarose content is low. However, the unit of measurement for the color-changing segment length y is millimeters. Therefore, in reality, there is no significant difference in the color-changing segment length under different agarose contents. This indicates that the kit provides good repeatability for time and temperature indications under different agarose contents, demonstrating reliable accuracy.

[0114] Therefore, the kits of Examples 1-5 showed no significant difference in indicating time and temperature under different agarose contents. If the kit of Example 1 can be used to determine temperature T and time x, then the kits of Examples 2-5 can also be used to determine temperature T and time x.

[0115] Test Example 4

[0116] Take the kits from Examples 1 and 6-9, add ascorbic acid from top to bottom to the composite gel, and incubate at 25°C for 1 hour. Observe the length γ and color of each discoloration segment. Figure 4a and Figure 4b As shown.

[0117] from Figure 4a and Figure 4b As can be seen, under the same conditions, with the increase of chloroauric acid content, the color of the discoloration segment gradually deepens, and the length y gradually shortens. This is because Au 3+ The higher the chloroauric acid content, the more gold nanoparticles are produced by reduction, and the more obvious the color change. However, because more ascorbic acid is consumed per unit volume, the color change duration is shorter. In actual testing, to determine the time and temperature based on the stable color-time-temperature relationship, it is only necessary to control the chloroauric acid content at a specific value, such as 0.34%, for comparison. As can be seen from the figure, a clear and uniform color change is visible to the naked eye when the chloroauric acid content reaches 0.34%. Therefore, to ensure both a clear and uniform color change and accurate determination of time and temperature, while also preventing material waste, a chloroauric acid content of 0.34% is sufficient.

[0118] Therefore, in practical applications, simply setting the chloroauric acid content to a specific value is sufficient to accurately determine the time and temperature. The kits in Examples 6-9 can also be used to determine temperature T and time x.

[0119] Test Example 5

[0120] Take the kits from Examples 1 and 10-13, add ascorbic acid from top to bottom to the composite gel, and incubate at 25°C for 1 hour. Observe the length γ and color of each discoloration segment. Figure 5a and Figure 5b As shown.

[0121] from Figure 5a and Figure 5b As can be seen, the length y of the discoloration segment increases with the increase of the added ascorbic acid concentration. This is because the greater the amount of ascorbic acid per unit area, the larger the concentration gradient in the composite gel, and the faster the diffusion rate, resulting in a longer discoloration segment per unit time. Therefore, this trend can be used to adjust the diffusion rate of ascorbic acid, selecting an appropriate concentration according to different needs to adapt to different application scenarios.

[0122] Therefore, the kits in Examples 10-13 can also be used to determine temperature T and time x.

[0123] Test Example 6

[0124] Multiple kits from Example 1 were used, and ascorbic acid was added to the composite gel from top to bottom. The discoloration was investigated at different times (0-12h) and different temperatures (0-50℃). The results are as follows: Figure 6a , Figure 6b and Figure 6c As shown.

[0125] from Figure 6a As can be seen, the color-changing segment appears blue at 0℃, and gradually approaches red as the temperature increases.

[0126] from Figure 6b As can be seen, the variation trend of the color-changing segment length y of the composite gel is generally consistent at different temperatures, gradually increasing with time. However, at the same time interval, the color-changing segment length y of the composite gel is longer in the high-temperature environment than in the low-temperature environment. This is because higher temperatures accelerate molecular motion, leading to a faster downward diffusion of ascorbic acid. Therefore, different temperature environments correspond to different time-color-changing segment length y relationships. Figure 6c Similar conclusions can be drawn.

[0127] Test Example 7

[0128] Multiple kits from Example 1 were used, and ascorbic acid was added to the composite gel from top to bottom. The changes in the color-changing segment from 0 to 35 days were investigated at 0℃, 5℃, 15℃, 25℃, 35℃, and 50℃. The diffusion equations were obtained by fitting the curves of the color-changing segment length over time. The diffusion equations at the above temperatures all conformed to the form of the following equation.

[0129] y = y0 + A|xx c | P

[0130] At the above temperatures, parameters y0 and x c A and P are respectively:

[0131]

[0132] The determination coefficient R of the diffusion equation at the above temperature 2 As shown below:

[0133]

[0134] As can be seen from the above, the coefficient of determination of the diffusion equation at each temperature is greater than 0.997, indicating that the fitted equation can accurately describe the relationship between the length of the color-changing segment and time at different temperatures.

[0135] Taking 5℃ and 25℃ as examples, the discoloration after 0-33 days at 5℃ and 0-25 days at 25℃ are as follows: Figure 7a , Figure 7b The results at other temperatures are not shown. As can be seen from the figure, the composite gel encapsulated in a 20cm long acrylic tube can be monitored for 33 days at 5℃ and for 25 days at 25℃, demonstrating its ability to monitor temperature over long periods. Furthermore, increasing the length of the acrylic tube can further extend the monitoring time limit to meet longer monitoring requirements. This makes it suitable not only for environmental temperature indication of short-shelf-life products such as milk and bread, but also for monitoring the environmental temperature of substances that can be stored for extended periods, such as serum and biological samples.

[0136] Test Example 8

[0137] Multiple kits from Example 1 were used. Ascorbic acid was added to the composite gel from top to bottom. The gel was first placed at 5°C for 4 hours, then moved to 25°C for 8 hours. The changes in the color change segment over time after the temperature change were observed. The results are as follows: Figure 8a and Figure 8b As shown in the figure. In another kit, ascorbic acid was added to the composite gel from top to bottom, and then the gel was placed directly in a 25°C environment for 8 hours. The changes in the color change segment over time were recorded.

[0138] from Figure 8a As can be seen, the composite gel exhibits two different color-changing segments after temperature changes. The color-changing segments formed at 5℃ are all blue, while the color-changing segments formed at 25℃ are bluish-purple. This indicates that increasing the temperature does not change the color of the already colored gel segments, and the composite gel does indeed have the ability to remember temperatures.

[0139] from Figure 8bIn the figure, the curve shows the change in the length of the color-changing segment formed at 25℃ in the composite gel after temperature variation with time. The points marked on the curve represent the lengths of the color-changing segments at different times when directly cultured at 25℃. It was found that the increments of the color-changing segments with time were the same for both types of gels, indicating that the relationship between the length of the color-changing gel segment and time remains applicable under temperature variations.

[0140] Test Example 9

[0141] Take 6 kits from Comparative Example 1. One kit does not include ascorbic acid in the composite gel as the Blank group. The other five kits have ascorbic acid added to the composite gel from top to bottom. They are then placed at 0℃, 15℃, 37℃, 50℃ and 65℃ respectively. After 3 hours, the color change segment is observed.

[0142] Observations revealed that no discoloration segment appeared in the Blank group and the other five groups that added ascorbic acid, so the length and color of the discoloration segment could not be used to indicate time and temperature.

[0143] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for indicating temperature and time using a kit, characterized by, The kit comprises a composite gel and ascorbic acid, the composite gel is placed in a transparent container, the composite gel comprises agarose and chloroauric acid dispersed in the agarose, and the method comprises: adding said ascorbic acid to said complex gel, at a temperature T, over a time , a discolored section appears in the complex gel; Determination of temperature T and time by color and length of color change segment ; Wherein, 0≤T≤80℃; According to the diffusion equation at temperature T, the length of the color-changing section is substituted into the diffusion equation at temperature T to obtain time x; The diffusion equation is wherein, L is the length of the color-changing segment, mm, t is time, h, 0, c A and P are temperature-dependent parameters; wherein, when the concentration of ascorbic acid is 80-150 mmol / L, the content of chloroauric acid is 0.25-0.4% based on the mass of the composite gel, 0≤T≤60℃, the parameter 0、 c , A and P are related to temperature T as follows: 。 2. The method of claim 1, wherein, The method further comprises: adding the ascorbic acid to the composite gel from top to bottom.

3. The method of claim 1 or 2, wherein, The method for determining temperature T comprises: comparing the color of the color-changing section with a colorimetric card to determine temperature T.

4. The method of claim 1 or 2, wherein, The preparation method of the composite gel comprises: preparing an agarose solution under the condition of heating and stirring, then adding a chloroauric acid solution to the agarose solution, stirring until uniform, then pouring into a transparent container, and cooling to obtain a composite gel.

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