Method for measuring moisture absorption capacity of moisture absorption film
By calculating the moisture absorption amount of the hygroscopic film under constant conditions, the relative standard deviation of the sample was calculated, and the problem of inconsistent measurement results in the prior art was solved, and a high accuracy and repetitive hygroscopic measurement was achieved.
Patent Information
- Application Number
- CN202510954020.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-11
- Publication Date
- 2025-08-08
- Estimated Expiration
- Not applicable · inactive patent
AI Technical Summary
The existing hygroscopic measurement methods for hygroscopic films have poor repetition and accuracy, which are greatly affected by changes in ambient temperature and humidity, resulting in inconsistent measurement results.
The measurement is carried out in a closed detection environment of constant temperature and humidity. The relative standard deviation of the moisture absorption amount of a single sample is calculated multiple times, so that the moisture absorption amount of the moisture absorption film is calculated after ensuring that the relative standard deviation is within a predetermined threshold range.
It improves the accuracy and repeatability of the measurement of moisture absorption amount of hygroscopic films, ensures that the measurement results are close to the actual value, and is suitable for the measurement of different hygroscopic films, and is convenient to operate.
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Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of measuring the moisture absorption of hygroscopic materials, in particular to a method for measuring the moisture absorption of a hygroscopic film. Background Art
[0002] Penem antibiotics are highly effective but also have poor stability and are sensitive to moisture. They easily degrade in water, leading to a significant increase in related substances and polymers in the product. Unstable product quality can pose safety risks, especially for children, and this is a growing concern. For example, pediatric faropenem sodium granules undergo hydrolysis upon contact with water at room temperature, leading to a significant increase in degradation products. This can significantly alter the product's properties and odor, and can cause related substances and polymers to exceed permitted limits in the short term.
[0003] Research has found that the stability of granular products is correlated with the packaging material. The packaging material should have a certain degree of hygroscopicity. For example, a hygroscopic film (packaging material) can be used to absorb free water from the product granules. However, the hygroscopicity of the film should be appropriate. If the hygroscopicity is too low, it will be ineffective, while if it is too high, it will absorb the crystalline water from faropenem sodium, which will change the crystalline water and reduce stability.
[0004] Therefore, to ensure that the hygroscopic film meets the hygroscopic requirements of pharmaceutical packaging, it is particularly important to be able to accurately measure the hygroscopic film's hygroscopic capacity. Common methods for measuring the hygroscopic film's hygroscopic capacity include the rapid water boiling method, the room temperature adsorption method, and the solid temperature and humidity method. The rapid water boiling method has the following problems: different drying times using a hair dryer or oven have a significant impact on the measurement results, resulting in poor repeatability and significant differences in the measurement results for the same sample between different people; the room temperature adsorption method has the following problems: it is naturally absorbing moisture in an indoor environment, and different indoor humidity levels can lead to significant differences in the measurement results. For example, if the indoor humidity is low, the result will be significantly lower; the solid temperature and humidity method has the following problems: the sample temperature is too high, and the hygroscopic film absorbs moisture and dries simultaneously, making it difficult to reach saturation, resulting in a significant difference between the measurement results and the actual value. Summary of the Invention
[0005] In view of the shortcomings of the prior art, the present invention provides a method for measuring the moisture absorption of a hygroscopic film, which can effectively improve the accuracy of the measurement results of the moisture absorption of the hygroscopic film.
[0006] The present invention is achieved through the following technical solutions: The present invention provides a method for measuring the moisture absorption of a hygroscopic film, comprising the following steps: S1, select a closed testing environment with constant conditions; S2, selecting a predetermined number of samples, obtaining the individual area and mass before moisture absorption of each sample, and the total mass m1 and total area S of the predetermined number of samples before moisture absorption; S3, storing a predetermined number of the samples in the testing environment and then taking them out to obtain the mass of each sample after moisture absorption and the total mass m2 of the predetermined number of samples after moisture absorption; S4, obtaining the moisture absorption amount of each sample based on the area, mass before moisture absorption, and mass after moisture absorption of each sample, and calculating the relative standard deviation of the moisture absorption amount of a predetermined number of samples, If the relative standard deviation is within a predetermined threshold range, the moisture absorption amount of the moisture absorption film is calculated based on the total mass m1 before moisture absorption, the total mass m2 after moisture absorption, and the total area.
[0007] Furthermore, in step S1, the constant condition includes: the temperature and humidity in the detection environment are constant.
[0008] Furthermore, the constant temperature of the detection environment is 23°C~27°C.
[0009] Furthermore, the constant humidity of the detection environment is 60% to 70%.
[0010] Furthermore, in step S2, the predetermined number is 5 to 7 pieces.
[0011] Furthermore, in step S2, the length of a single sample is 10 cm to 20 cm, and the width is 10 cm to 20 cm.
[0012] Furthermore, the step S2 specifically includes: The predetermined number of samples are respectively subjected to size measurement and precise weighing to obtain the area and mass before moisture absorption of each sample, as well as the total mass m1 and total area S of the predetermined number of samples before moisture absorption.
[0013] Furthermore, the step S3 specifically includes: S31, storing a predetermined number of the samples in the testing environment, wherein the samples are spaced apart and do not touch each other during storage, and removing the samples after 60 hours to 72 hours; S32, accurately weighing the predetermined number of samples after being taken out, obtaining the mass of each sample after moisture absorption, and the total mass m2 of the predetermined number of samples after moisture absorption.
[0014] Furthermore, in step S4, the calculation formula for the moisture absorption of each sample is: Moisture absorption = (mass after moisture absorption - mass before moisture absorption) / single area, unit: g / m 2 ; The calculation formula of the moisture absorption of the hygroscopic film is: Moisture absorption of hygroscopic film = (total mass after moisture absorption m2 - total mass before moisture absorption m1) / total area S, unit: g / m 2 .
[0015] Furthermore, in step S4, the predetermined threshold range is less than or equal to 5.0%.
[0016] Compared with the prior art, the advantages of the present invention are: 1. The method for measuring the moisture absorption of a hygroscopic film provided by the present invention performs the measurement in a closed detection environment under constant temperature and humidity conditions, thereby ensuring that the moisture absorption value of the sample measured in the detection environment is close to the actual value, thereby improving the accuracy of the measurement result.
[0017] 2. The method for measuring the moisture absorption of a hygroscopic film provided by the present invention expresses the degree of dispersion of the moisture absorption experimental results of multiple samples by calculating the relative standard deviation of the moisture absorption values of multiple single samples. After ensuring that the relative standard deviation is within a predetermined threshold range (less than or equal to 5%), the calculated measurement results are obtained. As a result, the final sample moisture absorption result is highly close to the theoretical value, effectively ensuring the accuracy of the sample moisture absorption obtained by the final calculation.
[0018] 3. The present invention provides a method for measuring the moisture absorption of hygroscopic films. By measuring the weight difference between a predetermined number of samples before and after storage in a testing environment, the moisture absorption of the film samples is calculated. This method offers excellent test repeatability and high accuracy, making it suitable for measuring the moisture absorption of various hygroscopic films (packaging materials). Furthermore, the present invention is convenient to operate, and the testing environment can be easily selected. DETAILED DESCRIPTION
[0019] The following is a non-limiting detailed description of the technical solution of the invention in conjunction with preferred embodiments.
[0020] The present invention provides a method for measuring the moisture absorption of a hygroscopic film, comprising the following steps: S1, select a closed testing environment with constant conditions; S2, selecting a predetermined number of samples, obtaining the individual area and mass before moisture absorption of each sample, and the total mass m1 and total area S of the predetermined number of samples before moisture absorption; S3, storing a predetermined number of the samples in the testing environment and then taking them out to obtain the mass of each sample after moisture absorption and the total mass m2 of the predetermined number of samples after moisture absorption; S4, obtaining the moisture absorption amount of each sample based on the area, mass before moisture absorption, and mass after moisture absorption of each sample, and calculating the relative standard deviation of the moisture absorption amount of a predetermined number of samples, If the relative standard deviation is within a predetermined threshold range, the moisture absorption amount of the moisture absorption film is calculated based on the total mass m1 before moisture absorption, the total mass m2 after moisture absorption, and the total area.
[0021] Specifically, the method for measuring the moisture absorption of a hygroscopic film according to an embodiment of the present invention requires that the measurement be performed in a sealed test environment under constant conditions. Preferably, the constant conditions in the embodiment of the present invention are to maintain constant temperature and humidity in the test environment, thereby ensuring that the moisture absorption value of the sample measured in the test environment is close to the actual value, thereby improving the accuracy of the measurement results. Preferably, the constant temperature range of the test environment is 23°C to 27°C, and the constant humidity range of the test environment is 60% to 70%.
[0022] Next, 5 to 7 samples are selected and individually sized and precisely weighed to determine the area and pre-moisture absorption mass of each sample, as well as the total pre-moisture absorption mass m1 and total area S of a predetermined number of samples. When the number of 5 to 7 hygroscopic film samples is 5 to 7, the characteristics of numerous samples are sufficiently representative, enabling accurate measurement of the sample's moisture absorption capacity. The measurement workload is also reduced, effectively improving measurement efficiency. Preferably, the hygroscopic film sample has a length of 10 to 20 cm and a width of 10 to 20 cm. It should be noted that in the hygroscopic absorption capacity determination method of the present invention, the hygroscopic film sample does not expand or contract during moisture absorption, i.e., the area of the hygroscopic film does not change before and after moisture absorption.
[0023] In some embodiments, step S3 may include: S31, storing a predetermined number of samples in a testing environment, with each sample separated from each other and not in contact, and removing the samples after 60 hours to 72 hours; S32, accurately weighing the predetermined number of samples after taking out to obtain the mass of each sample after moisture absorption and the total mass m2 of the predetermined number of samples after moisture absorption.
[0024] Specifically, when 5 to 7 samples are stored in a test environment, the samples are spaced apart and do not touch each other, which ensures that the surface of each sample is fully exposed to the test environment, so that moisture can be absorbed normally, thereby improving the accuracy of the measurement. In addition, since the hygroscopic film sample contains calcium oxide and molecular sieves, during the placement process, the calcium oxide and molecular sieves absorb moisture from the test environment. If the placement time is less than 60 hours, the calcium oxide and molecular sieves in the sample do not meet the standard for complete moisture absorption, resulting in a low measurement result. If the placement time is longer than 72 hours, the calcium oxide and molecular sieves in the sample have already completely absorbed moisture, which lengthens the experiment time and reduces the measurement efficiency.
[0025] Finally, the moisture absorption of each sample was calculated based on the area, mass before moisture absorption, and mass after moisture absorption of each sample. The calculation formula for the moisture absorption of each sample is: Moisture absorption = (mass after moisture absorption - mass before moisture absorption) / single area, unit: g / m 2 ; Then calculate the relative standard deviation (RSD) of the moisture absorption values measured for 5 to 7 samples. The calculation formula is:
[0026] Among them, the standard deviation (SD) reflects the degree of deviation of the data from the mean value, and its calculation formula is:
[0027] Where, X i is a single measurement value, i.e. the moisture absorption of a single sample. It is the average value of moisture absorption of multiple samples, where n is 5, 6 or 7.
[0028] In other words, the method for measuring the moisture absorption of a hygroscopic film according to the present embodiment adds the step of measuring and evaluating the moisture absorption of each sample individually. In other words, by calculating the relative standard deviation of the moisture absorption values for multiple samples (i.e., 5 to 7 samples, each tested once), the dispersion of the moisture absorption test results for the multiple samples can be expressed, thereby measuring the precision of the measurement results. After ensuring that the relative standard deviation is within a predetermined threshold (less than or equal to 5%), the moisture absorption of the hygroscopic film is calculated based on the total mass before moisture absorption m1, the total mass after moisture absorption m2, and the total area of the multiple samples. The calculation formula is: Moisture absorption of hygroscopic film = (total mass after moisture absorption m2 - total mass before moisture absorption m1) / total area S, unit: g / m 2 . As a result, the final sample moisture absorption result is highly close to the theoretical value, effectively ensuring the accuracy of the final calculated sample moisture absorption. It should be noted that in drug quality analysis, RSD is the core indicator for measuring the precision of the detection method, which aims to provide a reliable data basis for the measurement results. If the RSD exceeds the predetermined threshold range, it indicates that the system is unstable and the current data is invalid. The cause needs to be investigated and retested. Furthermore, the predetermined threshold range is less than 2%.
[0029] The present invention provides a method for measuring the moisture absorption of hygroscopic films. By measuring the weight difference between a predetermined number of samples before and after storage in a testing environment, the method calculates the moisture absorption of the film samples. This method offers excellent test repeatability and high accuracy, making it suitable for measuring the moisture absorption of various hygroscopic films (packaging materials). Furthermore, the method is convenient to operate, and the testing environment can be easily selected.
[0030] The moisture absorption capacity measuring method of the present invention is described in detail below through examples.
[0031] Example 1 The method of the present invention was used to conduct tests on specificity (under different temperature and humidity conditions), repeatability (measured by the same experimenter at different test times), and reproducibility (measured by different experimenters in different laboratories). The results are as follows: Table 1: Humidity absorption measurement at 20°C
[0032] Table 2: Humidity absorption measurement at 25°C
[0033] Table 3: Humidity absorption measurement at 30°C
[0034] As shown in Tables 1, 2 and 3, the specificity test results of the determination method of the present invention show that the determination results at different humidity levels are basically consistent, the repeatability test results of the determination method of the present invention show that there is no difference in the determination results between different people, and the reproducibility test results of the determination method of the present invention show that the determination results between different laboratories are basically consistent.
[0035] Example 2 The moisture absorption of three selected hygroscopic film samples was measured using the present method and the current conventional method. The differences between the different measurement methods and the theoretical values were calculated. The results are as follows: Table 4: Evaluation of the test results of the determination method of the present invention and the conventional determination method
[0036] As shown in Table 4, the measurement results obtained by the measurement method of the present invention have smaller errors than those obtained by several conventional methods and are closer to the theoretical values.
[0037] Example 3 The moisture absorption capacity of commercially available hygroscopic films was tested using the present method and the current conventional method. The RSD between the single-piece measurement results and the RSD between repeated measurement results were examined. The results are shown in the following table: Table 5: RSD between the single-plate determination results of the determination method of the present invention and the current conventional determination method and RSD evaluation of the repeated determination results
[0038] It should be noted that in this example, the single-piece measurement result refers to the RSD value of the single moisture absorption measurement results of 5 samples of the commercially available hygroscopic film (packaging material), and the repeated measurement result refers to the RSD value of the two measurement results (each measurement result refers to the average of the single moisture absorption measurement results of the 5 samples).
[0039] As shown in Table 5, the RSDs of the single-piece determination results and repeated determination results of the determination method of the present invention are better than those of other determination methods. The RSDs of the single-piece determination results of other methods are quite different. In summary, the comparative results of Examples 1, 2, and 3 demonstrate that the results of the moisture absorption determination method of this application are highly consistent with the theoretical values, with the RSD of the results within a ±5% error range, while the differences between the results and the theoretical values of other determination methods are more significant. Furthermore, the moisture absorption determination method of this application outperforms other determination methods in terms of the relative standard deviation (RSD) of both single-piece and replicate measurements. Furthermore, this method is applicable to both low and high moisture absorption conditions.
[0040] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.
Claims
1. A method for measuring the moisture absorption of a hygroscopic film, characterized in that: The following steps are involved: S1, select a closed testing environment with constant conditions; S2, selecting a predetermined number of samples, obtaining the individual area and mass before moisture absorption of each sample, and the total mass m1 and total area S of the predetermined number of samples before moisture absorption; S3, storing a predetermined number of the samples in the testing environment and then taking them out to obtain the mass of each sample after moisture absorption and the total mass m2 of the predetermined number of samples after moisture absorption; S4, obtaining the moisture absorption amount of each sample based on the area, mass before moisture absorption, and mass after moisture absorption of each sample, and calculating the relative standard deviation of the moisture absorption amount of a predetermined number of samples, If the relative standard deviation is within a predetermined threshold range, the moisture absorption amount of the moisture absorption film is calculated based on the total mass m1 before moisture absorption, the total mass m2 after moisture absorption, and the total area.
2. The method for measuring the moisture absorption of a hygroscopic film according to claim 1, wherein: In step S1, the constant condition includes: the temperature and humidity in the detection environment are constant.
3. The method for measuring the moisture absorption of a hygroscopic film according to claim 2, wherein: The constant temperature of the detection environment is 23°C~27°C.
4. The method for measuring the moisture absorption of a hygroscopic film according to claim 2, wherein: The constant humidity of the testing environment is 60% to 70%.
5. The method for measuring the moisture absorption of a hygroscopic film according to claim 1, wherein: In step S2, the predetermined number is 5 to 7 pieces.
6. The method for measuring the moisture absorption of a hygroscopic film according to claim 1, wherein: In step S2, the length of each sample is 10 cm to 20 cm, and the width is 10 cm to 20 cm.
7. The method for measuring the moisture absorption of a hygroscopic film according to claim 1, wherein The step S2 specifically includes: The predetermined number of samples are respectively subjected to size measurement and precise weighing to obtain the area and mass before moisture absorption of each sample, as well as the total mass m1 and total area S of the predetermined number of samples before moisture absorption.
8. The method for measuring the moisture absorption of a hygroscopic film according to claim 1, wherein The step S3 specifically includes: S31, storing a predetermined number of the samples in the testing environment, wherein the samples are spaced apart and do not touch each other during storage, and removing the samples after 60 hours to 72 hours; S32, accurately weighing the predetermined number of samples after being taken out, obtaining the mass of each sample after moisture absorption, and the total mass m2 of the predetermined number of samples after moisture absorption.
9. The method for measuring the moisture absorption of a hygroscopic film according to claim 1, wherein: In step S4, the calculation formula for the moisture absorption of each sample is: Moisture absorption = (mass after moisture absorption - mass before moisture absorption) / single area, unit: g / m 2 ; The calculation formula of the moisture absorption of the hygroscopic film is: Moisture absorption of hygroscopic film = (total mass after moisture absorption m2 - total mass before moisture absorption m1) / total area S, unit: g / m 2 .
10. The method for measuring the moisture absorption of a hygroscopic film according to claim 1, wherein: In step S4, the predetermined threshold range is less than or equal to 5.0%.
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