Physical standard sample for amino acid content in mulberry silk and preparation method thereof

Abstract

The invention provides a preparation method of an amino acid content physical standard sample in mulberry silk, and the amino acid content physical standard sample in mulberry silk is prepared through the steps of cocoon selection, impurity removal, degumming, dehydration and drying, weight increment, cleaning and drying, split charging and the like. The method can be used for effectively analyzing and detecting four main amino acids (serine, glycine, alanine and tyrosine) in the mulberry silk, so that the reliability of a mulberry silk amino acid content detection experiment is ensured, and the accuracy of a mulberry silk amino acid content detection experiment result is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of standard samples, and in particular relates to a physical standard sample of amino acid content in mulberry silk and a preparation method thereof. Background Art

[0002] Since silk cotton is usually priced by weight, in recent years, many unscrupulous merchants have obtained illegal profits by artificially increasing the weight of silk. On the one hand, this has led to unfair market transactions. On the other hand, the ingredients used to increase the weight may pose a safety hazard. Weighted silk cotton causes the silk quilt to fail to meet the oil content, moisture regain and other indicators.

[0003] At present, the weight increase method of silk quilt filling usually adopts the methacrylamide chemical grafting weight increase method, which can give silk fabric a thick and plump feel and increase drape. It cannot be separated from the silk surface by conventional scouring, and the weighted silk is difficult to identify by conventional component testing methods (such as microscopy, dissolution, combustion, etc.), which has a certain degree of concealment. GB / T 24252-2019 "Silk Quilt" stipulates that the silk filling of silk quilts shall not be weighted, and the total amount of the four main amino acids, serine, glycine, alanine and tyrosine, shall not be less than 77%. GB / T 24252-2019 "Silk Quilt" Appendix E method acid hydrolyzes the sample and then derivatizes it before column, and then determines the amino acid content by liquid chromatography to determine the amino acid derivatives. The content of the four main amino acids is used to identify whether the silk quilt has gained weight. This method has been used by most domestic testing institutions as an effective identification method for daily detection of silk cotton weight gain.

[0004] In the testing system of the textile industry, standard samples are an important technical basis for the scientific formulation and effective implementation of text standards, improving product quality, and promoting scientific and technological innovation. At present, there are only liquid solutions or reagent standard substances for these four amino acids at home and abroad, and there is a lack of physical standard samples of the content of the main amino acids (serine, glycine, alanine and tyrosine) in mulberry silk. The silk amino acid detection process involves multiple steps such as hydrolysis, derivatization, extraction and concentration. The process is lengthy, and factors such as human operation and instrument status will affect the test results to varying degrees, bringing many inconveniences to the effective control of the detection process, and causing interference and influence on the experimental results. Summary of the invention

[0005] In view of the deficiencies in the prior art of detecting the amino acid content in mulberry silk, the present invention provides a physical standard sample of the amino acid content in mulberry silk and a preparation method thereof, which are used to effectively analyze and detect the four main amino acids (serine, glycine, alanine and tyrosine) in mulberry silk, ensure the reliability of the mulberry silk amino acid content detection experiment, and improve the accuracy of the mulberry silk amino acid content detection experiment results.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] The first aspect of the present invention is to provide a method for preparing a physical standard sample of amino acid content in mulberry silk, comprising the following steps:

[0008] S1. Select mulberry silk raw materials and remove yellow spots and black spots;

[0009] S2. Prepare a degumming solution and heat it in a water bath, place the mulberry silk raw material after impurities removal in step S1 in the degumming solution, make the degumming solution fully infiltrate the mulberry silk, stir continuously, and perform alkali degumming for 20 to 30 minutes;

[0010] S3. The mulberry silk raw material after alkali degumming in step S2 is washed with warm water and then dehydrated;

[0011] S4. Repeat steps S2 and S3 twice with the dehydrated silk raw material in step S3, followed by dehydration and drying;

[0012] S5. The mulberry silk raw material after drying in step S4 is subjected to weight gain treatment to obtain a weight-gained mulberry silk sample;

[0013] S6. The weight-gained silk sample obtained in step S5 is first washed in a water bath, then washed with cold water, and then dehydrated and dried to obtain a physical standard sample of the amino acid content in the silk;

[0014] S7. Packing the physical standard sample of amino acid content in silk obtained in step S6;

[0015] S8. Check the uniformity and stability of the physical standard sample of the amino acid content in the silk obtained in step S6;

[0016] S9. Determine the values ​​and uncertainty of the serine, glycine, alanine and tyrosine contents in the physical standard sample of amino acid content in the mulberry silk obtained in step S6.

[0017] Furthermore, the degumming solution in step S2 includes 3-6 g / L of sodium bicarbonate and 4-7 g / L of silk refining agent.

[0018] Furthermore, the bath ratio of the alkali degumming method in step S2 is 1:40-60.

[0019] Furthermore, the water bath temperature of the alkali degumming process in step S2 is 80-100°C.

[0020] Furthermore, the washing temperature of the warm water washing in step S3 is 40-60°C.

[0021] Furthermore, the weight gain treatment in step S5 specifically includes the following steps: after injecting 25 to 40 L of water into the silk weight gain reactor, adding 700 to 1200 g of silk weight gain agent, adjusting the solution pH to 2 to 3 with glacial acetic acid, heating to 70 to 100 ° C to obtain a mulberry silk weight gain liquid; placing the mulberry silk raw material dried in step S4 in the mulberry silk weight gain liquid, starting to stir at a stirring rate of 200 to 500 r / min, stirring for 5 to 10 minutes, adding 20 to 40 g of initiator, stirring continuously during the addition process, then keeping warm for 80 to 100 minutes, draining the solution, and obtaining a weight gain mulberry silk sample.

[0022] Furthermore, the silk weighting agent is methacrylamide and the initiator is potassium persulfate.

[0023] Furthermore, in step S6, the water bath cleaning temperature is 40-60°C, and the cold water cleaning temperature is 15-25°C.

[0024] Furthermore, the sample packaging method in step S7 is: cut the physical standard sample of amino acid content in mulberry silk obtained in step S6 into pieces of 1 to 2 mm in length, mix them evenly, and then package them, with 1.5 to 2.0 g of sample in each bag; the inner bag is packaged with food-grade polypropylene and the bag mouth is melt-sealed; the outer packaging is sealed with an aluminum foil bag for a second time.

[0025] The second aspect of the present invention is to provide a physical standard sample of amino acid content in mulberry silk, which is prepared based on the preparation method of the physical standard sample of amino acid content in mulberry silk.

[0026] Compared with the prior art, the present invention has at least the following beneficial effects:

[0027] The physical standard sample of amino acid content in mulberry silk and the preparation method thereof provided by the present invention can effectively analyze and detect the contents of four main amino acids (serine, glycine, alanine and tyrosine) in mulberry silk. In the process of detecting amino acids in mulberry silk, the physical standard sample of amino acid content of the present invention is used for comparison with the sample to be tested, which can ensure the reliability of the mulberry silk amino acid content detection experiment and improve the accuracy of the experimental results of the mulberry silk amino acid content detection experiment.

[0028] The physical standard sample of amino acid content in mulberry silk and the preparation method thereof provided by the present invention can be used for comparison of test data between laboratories, strengthening the quality control of mulberry silk in silk quilts, quality control of silk weight gain identification tests, etc., laying a good foundation for the sustainable development of the field of physical standard samples of mulberry silk. DETAILED DESCRIPTION

[0029] The present invention will be further described by specific examples. It should be understood that these examples are only used to illustrate the present invention and are not used to limit the scope of the present invention.

[0030] It should be noted that the mulberry silk raw material used in the embodiment of the present invention is cocoons purchased from the market, and the silk refining agent used in alkali degumming is a commercially available degreasing silk refining agent containing inorganic salts and surfactants.

[0031] The method for determining the content of the main amino acids (serine, glycine, alanine and tyrosine) in the present invention is Appendix E of GB / T 24252-2019 "Silk Quilt".

[0032] The information of the standard substances of serine, glycine, alanine and tyrosine in the present invention is shown in Table 1.

[0033] Table 1. Information on serine, glycine, alanine and tyrosine

[0034] Compound Name Chemical Abstracts Number (Cas No.) Molecular weight DL-Serine 302-84-1 105.09 Glycine 56-40-6 75.07 Alanine 56-41-7 89.09 DL-Tyrosine 556-03-6 181.19

[0035] The method for preparing a physical standard sample of amino acid content in mulberry silk of the present invention comprises the following steps:

[0036] S1. Select mulberry silk raw materials and remove yellow spots and black spots;

[0037] S2. Prepare a degumming solution (3 to 6 g / L of sodium bicarbonate and 4 to 7 g / L of silk refining agent) and heat it in a water bath. Place the mulberry silk raw material after impurities removal in step S1 in the degumming solution at a bath ratio of 1:40 to 60, so that the degumming solution fully infiltrates the mulberry silk. Stir continuously. The water bath temperature is 80 to 100 ° C. and alkali degumming is performed for 20 to 30 minutes.

[0038] S3. The mulberry silk raw material after alkali degumming in step S2 is washed with warm water at 40 to 60°C and then dehydrated;

[0039] S4. Repeat steps S2 and S3 twice with the dehydrated silk raw material in step S3, followed by dehydration and drying;

[0040] S5. After injecting 25-40L of water into the silk weighting reactor, add 700-1200g of methacrylamide, adjust the solution pH to 2-3 with glacial acetic acid, and heat to 70-100°C to obtain a mulberry silk weighting liquid; place the mulberry silk raw material dried in step S4 in the mulberry silk weighting liquid, start stirring, and start stirring at a rate of 200-500r / min. After stirring for 5-10min, add 20-40g of potassium persulfate as an initiator, stir continuously during the addition process, and then keep warm for 80-100min, drain the solution, and obtain a weighted mulberry silk sample;

[0041] S6. The weighted silk sample obtained in step S5 is first washed in a water bath (40-60° C.), then washed with cold water (15-25° C.), and then dehydrated and dried to obtain a physical standard sample of amino acid content in silk;

[0042] S7. Cut the physical standard sample of amino acid content in mulberry silk obtained in step S6 into pieces of 1-2 mm in length, mix them evenly, and then pack them into bags, with 1.5-2.0 g of sample in each bag; use food-grade polypropylene for inner packaging, and seal the bag mouth with a melt; use an aluminum foil bag for the outer packaging, which is sealed for the second time.

[0043] S8. Check the uniformity and stability of the physical standard sample of amino acid content in the silk obtained in step S6:

[0044] (1) According to the requirements of GB / T 15000.3-2008 "Guidelines for Standard Samples (3) General principles and statistical methods for determining the value of standard samples", the uniformity of the physical standard sample of amino acid content in mulberry silk prepared in Example 1 was tested by one-way analysis of variance.

[0045] A random number table was created using Excel software, and 15 bags of samples were randomly selected from the physical standard samples of amino acid content in the prepared mulberry silk according to the random numbers in the table, and the uniformity of the content of the main amino acids (serine, glycine, alanine and tyrosine) in the samples was tested; each bag of samples was tested twice under repeated conditions, for a total of 30 times; the samples for repeated tests were sampled separately, and the sampling amount was 0.1g.

[0046] (2) According to the requirements of GB / T 15000.3-2008 “Guidelines for Standard Samples (3) General Principles and Statistical Methods for Determining the Value of Standard Samples”, the t-test method was used to test the long-term stability of the content of the standard sample prepared in Example 1; the long-term stability test lasted for a total of 3 years, namely 0, 3, 6, 9, 12, 18, 24 and 36 months; at each time point, 3 bags of samples were randomly selected from the inventory samples, each bag of samples was tested twice, and the sampling volume was 0.1 g. The total average of the 6 test results was taken as the stability test result of the characteristic quantity value at that time point.

[0047] S9. Determine the values ​​and uncertainty of serine, glycine, alanine and tyrosine contents in the physical standard sample of amino acid content in mulberry silk obtained in step S6:

[0048] (3) According to the requirements of GB / T 15000.3-2008 “Guidelines for Standard Samples (3) General principles and statistical methods for standard sample values”, the standard samples prepared in Example 1 were valued; the results of the standard samples were expressed as standard values ​​and uncertainties.

[0049] The determination method uses 8 laboratories to determine the value together. Three bags were sent to each laboratory, and each laboratory was required to repeat the test twice for each bag of samples, and a total of 6 repeated tests were completed within 5 days. The test results were subjected to Cochran test, normal distribution test and Grubbs test. The uncertainty of the characteristic value of the standard sample is mainly composed of the determination uncertainty (u char ), uncertainty of uniformity between samples (u bb ), long-term stability uncertainty component (u lts ) and short-term stability uncertainty components such as sample transportation (u sts )constitute.

[0050] Example 1

[0051] The method for preparing the physical standard sample of amino acid content in mulberry silk of this embodiment comprises the following steps:

[0052] S1. Select 500g of mulberry silk raw material and remove yellow spots and black spots;

[0053] S2. Take 25L of water, add 100g of sodium carbonate and 125g of silk refining agent to prepare a degumming solution, heat the water bath to 100°C, place the mulberry silk raw material after impurity removal in step S1 in a 100°C degumming solution with a bath ratio of 1:50, so that the degumming solution fully infiltrates the mulberry silk, stir continuously, and perform alkali degumming for 30min;

[0054] S3. The mulberry silk raw material after alkali degumming in step S2 is washed with warm water at 50°C and then placed in a dehydrator for dehydration;

[0055] S4. Repeat steps S2 and S3 twice with the dehydrated silk raw material in step S3, followed by dehydration and drying;

[0056] S5. After injecting 30L of water into the silk weighting reactor, 900g of methacrylamide was added, and the solution was adjusted to pH 2.5 with glacial acetic acid, and then heated to 80°C to obtain a mulberry silk weighting liquid; 300g of the mulberry silk raw material dried in step S4 was placed in the mulberry silk weighting liquid, and stirring was started at a stirring rate of 300r / min. After stirring for 5min, 30g of potassium persulfate was added as an initiator, and stirring was continued during the addition process, followed by keeping warm for 90min, and the solution was drained to obtain a weighted mulberry silk sample;

[0057] S6. The weight-gained silk sample obtained in step S5 is first washed in a 50°C water bath, then washed with cold water at 25°C, dehydrated in a dehydrator, and then dried in an oven at 60°C to obtain a physical standard sample of the amino acid content in the silk;

[0058] S7. Cut the physical standard sample of amino acid content in mulberry silk obtained in step S6 into pieces of 1 mm in length, mix them evenly, and then pack them into bags, with 2.0 g of sample in each bag; the inner bag is packed with food-grade polypropylene (PP) and the bag mouth is melt-sealed; the outer bag is packed with an aluminum foil bag for a second melt-sealing.

[0059] In this embodiment, Appendix E of GB / T 24252-2019 "Silk Quilt" was used to determine the content of main amino acids (serine, glycine, alanine and tyrosine) in the mulberry silk sample, which was 48.8%.

[0060] Example 2

[0061] The method for preparing the physical standard sample of amino acid content in mulberry silk of this embodiment comprises the following steps:

[0062] S1. Select 500g of mulberry silk raw material and remove yellow spots and black spots;

[0063] S2. Take 20L of water, add 60g of sodium carbonate, 80g of silk refining agent, configure a degumming solution, heat it in a water bath to 80°C, place the mulberry silk raw material after impurity removal in step S1 in a degumming solution at 80°C, the bath ratio is 1:40, so that the degumming solution fully infiltrates the mulberry silk, stir continuously, and perform alkali degumming for 20min;

[0064] S3. The mulberry silk raw material after alkali degumming in step S2 is washed with warm water at 40°C and then placed in a dehydrator for dehydration;

[0065] S4. Repeat steps S2 and S3 twice with the dehydrated silk raw material in step S3, followed by dehydration and drying;

[0066] S5. After injecting 25L of water into the silk weighting reactor, 700g of methacrylamide was added, and the solution was adjusted to pH 2.0 with glacial acetic acid, and then heated to 90°C to obtain a mulberry silk weighting liquid; 300g of the mulberry silk raw material dried in step S4 was placed in the mulberry silk weighting liquid, and stirring was started at a stirring rate of 200r / min. After stirring for 5min, 20g of potassium persulfate was added as an initiator, and stirring was continued during the addition process, followed by keeping warm for 80min, and the solution was drained to obtain a weighted mulberry silk sample;

[0067] S6. The weight-gained silk sample obtained in step S5 is first washed in a 50°C water bath, then washed with cold water at 15°C, dehydrated in a dehydrator, and then dried in an oven at 60°C to obtain a physical standard sample of the amino acid content in the silk;

[0068] S7. Cut the physical standard sample of amino acid content in mulberry silk obtained in step S6 into pieces of 1.5 mm in length, mix them evenly, and then pack them into bags, with 1.5 g of sample in each bag; the inner bag is packed with food-grade polypropylene (PP) and the bag mouth is melt-sealed; the outer bag is packed with an aluminum foil bag for a second melt-sealing.

[0069] In this embodiment, Appendix E of GB / T 24252-2019 "Silk Quilt" was used to determine the content of main amino acids (serine, glycine, alanine and tyrosine) in the mulberry silk sample, which was 41.2%.

[0070] Example 3

[0071] The method for preparing the physical standard sample of amino acid content in mulberry silk of this embodiment comprises the following steps:

[0072] S1. Select 500g of mulberry silk raw material and remove yellow spots and black spots;

[0073] S2. Take 30L of water, add 180g of sodium carbonate, 210g of silk refining agent, configure a degumming solution, heat it in a water bath to 90°C, place the silk raw material after impurity removal in step S1 in a 90°C degumming solution, the bath ratio is 1:60, so that the degumming solution fully infiltrates the silk, stir constantly, and perform alkali degumming for 30min;

[0074] S3. The mulberry silk raw material after alkali degumming in step S2 is washed with warm water at 60°C and then placed in a dehydrator for dehydration;

[0075] S4. Repeat steps S2 and S3 twice with the dehydrated silk raw material in step S3, followed by dehydration and drying;

[0076] S5. After injecting 30L of water into the silk weighting reactor, 1200g of methacrylamide was added, and the solution was adjusted to pH=3.0 with glacial acetic acid, and then heated to 100°C to obtain a mulberry silk weighting liquid; 300g of the mulberry silk raw material dried in step S4 was placed in the mulberry silk weighting liquid, and stirring was started at a stirring rate of 200r / min. After stirring for 10min, 50g of potassium persulfate was added as an initiator, and stirring was continued during the addition process, followed by keeping warm for 100min, and the solution was drained to obtain a weighted mulberry silk sample;

[0077] S6. The weight-gained silk sample obtained in step S5 is first washed in a 50°C water bath, then washed with cold water at 25°C, dehydrated in a dehydrator, and then dried in an oven at 60°C to obtain a physical standard sample of the amino acid content in the silk;

[0078] S7. Cut the physical standard sample of amino acid content in mulberry silk obtained in step S6 into pieces of 2.0 mm in length, mix them evenly, and then pack them in batches, with 1.0 g of sample in each bag; the inner bag is packed with food-grade polypropylene (PP) and the bag mouth is melt-sealed; the outer bag is packed with an aluminum foil bag for secondary melt-sealing.

[0079] In this embodiment, Appendix E of GB / T 24252-2019 "Silk Quilt" was used to determine the content of main amino acids (serine, glycine, alanine and tyrosine) in the mulberry silk sample, which was 56.7%.

[0080] Example 5

[0081] The uniformity and stability of the physical standard samples of amino acid content in the mulberry silk prepared in Examples 1 to 3 were tested: Test method: Appendix E of GB / T 24252-2019 Silk Quilt

[0082] 1. Uniformity test

[0083] According to the requirements of GB / T 15000.3-2008 "Guidelines for Standard Samples (3) General principles and statistical methods for determining the value of standard samples", the uniformity of the physical standard sample of amino acid content in mulberry silk prepared in Example 1 was tested using a single factor analysis of variance.

[0084] A random number table was created using Excel software, and 15 bags of samples were randomly selected from the physical standard samples of amino acid content in the prepared mulberry silk according to the random numbers in the table, and the uniformity of the content of the main amino acids (serine, glycine, alanine and tyrosine) in the samples was tested; each bag of samples was tested twice under repeated conditions, for a total of 30 times; the samples for repeated tests were sampled separately, with a sampling volume of 0.1 g. The test results are shown in Table 2.

[0085] Table 2. Test results of uniformity of the standard samples of amino acid content in mulberry silk obtained in Example 1

[0086]

[0087] It can be seen from the data in Table 2 that the statistical calculation F value of the uniformity of the content of the main amino acids (serine, glycine, alanine and tyrosine) in the physical standard sample of the amino acid content in mulberry silk prepared in Example 1 is less than the corresponding test critical value of 2.42, indicating that when the sampling amount is 0.1 g and the significance level is 0.05, there is no significant difference in the content of the main amino acids (serine, glycine, alanine and tyrosine) in the physical standard sample of the amino acid content in mulberry silk between units and within units, indicating that the physical standard sample of the amino acid content in mulberry silk prepared in Example 1 has good uniformity.

[0088] The same method was used to verify that the uniformity of the physical standard sample of amino acid content in mulberry silk prepared in Example 2 was 1.72, and the uniformity of the physical standard sample of amino acid content in mulberry silk prepared in Example 3 was 1.80. The statistically calculated F values ​​were all less than the corresponding test critical value of 2.42, indicating that when the sampling amount was 0.1 g and the significance level was 0.05, there was no significant difference between the physical standard samples of amino acid content in mulberry silk prepared in Example 2 and Example 3 and within the unit, indicating that the physical standard samples of amino acid content in mulberry silk prepared in Example 2 and Example 3 had good uniformity.

[0089] 2. Stability test

[0090] According to the requirements of GB / T 15000.3-2008 "Guidelines for Standard Samples (3) General principles and statistical methods for determining the value of standard samples", the t-test method was used to test the long-term stability of the content of the standard sample prepared in Example 1; the long-term stability test was conducted for a total of 3 years, namely 0, 3, 6, 9, 12, 18, 24 and 36 months; 3 bags of samples were randomly selected from the inventory samples at each time point, each bag of samples was tested twice, and the sampling volume was 0.1 g. The total average of the 6 test results was taken as the stability test result of the characteristic quantity value at that time point. The test results are shown in Table 3.

[0091] Table 3. Stability test results of the physical standard samples of amino acid content in mulberry silk prepared in Example 1

[0092]

[0093] From the data in Table 3, it can be seen that |b1| of the physical standard samples of amino acid content in mulberry silk prepared in Example 1 is less than t(0.95, 6)×s(b1). This shows that there is no significant difference in the content of the main amino acids (serine, glycine, alanine and tyrosine) in the physical standard samples of amino acid content in mulberry silk during the 36-month experimental period.

[0094] The same method was used to verify the stability of the standard samples prepared in Example 2 and Example 3. The slopes were not significant, and no instability was observed in the standard samples prepared in Example 2 and Example 3. The results showed that the standard samples prepared in Example 2 and Example 3 had good stability.

[0095] Example 6

[0096] The contents of serine, glycine, alanine and tyrosine in the physical standard sample of amino acid content in mulberry silk prepared in Example 1 were determined and their uncertainties were evaluated.

[0097] According to the requirements of GB / T 15000.3-2008 "Guidelines for Standard Sample Work (3) General Principles and Statistical Methods for Determining the Value of Standard Samples", the physical standard sample of the amino acid content in mulberry silk prepared in Example 1 was determined; the results of the physical standard sample of the amino acid content in mulberry silk were expressed as the standard value and uncertainty.

[0098] The method of determining the value was to use 8 laboratories to determine the value. Three bags were sent to each laboratory, and each laboratory was required to repeat the test twice for each bag of samples, and a total of 6 repeated tests were completed within 5 days. The test results are shown in Table 4.

[0099] Table 4. Summary of collaborative determination data of the actual standard samples of amino acid content in mulberry silk obtained in Example 1

[0100]

[0101] The test results in Table 4 were subjected to Cochran's test, normal distribution test and Grubbs' test, and the results are shown in Tables 5-7.

[0102] Table 5. Summary of Cochrane test results

[0103] Number of trials Number of laboratories Calculated value of C C(0.05，8，6) C(0.01，8，6) 6 8 0.254 0.360 0.423

[0104] Table 6. Summary of normal distribution test results

[0105]

[0106] Table 7. Summary of Grubbs test results

[0107]

[0108] From the data in Tables 4 to 7, it can be seen that after Cochran's test and Grubbs' test, the value test data of the physical standard sample of the amino acid content in mulberry silk prepared in Example 1 has no outliers and suspicious values. After the normal distribution test, the calculated value of the statistic W of the collaborative value data of the standard sample is 0.964, which is greater than the critical value W(0.95, 48)=0.947, so the test results of this collaborative value follow the normal distribution.

[0109] In this embodiment, the synthetic standard uncertainty u of the physical standard sample of amino acid content in mulberry silk CRM Mainly consider the uncertainty of the fixed value u char , uniformity uncertainty u bb and the long-term stability uncertainty u lts Three servings.

[0110] The formula is:

[0111]

[0112] The calculation results of the combined uncertainty are shown in Table 8.

[0113] Table 8. Summary of synthetic uncertainty results

[0114] <![CDATA[u char (%)]]> <![CDATA[u bb (%)]]> <![CDATA[u lts (%)]]> <![CDATA[u CRM (%)]]> 0.53 0.36 1.10 1.31

[0115] In this embodiment, the results of the physical standard samples of the main amino acids (serine, glycine, alanine and tyrosine) in mulberry silk are expressed as standard values ​​and uncertainties. The standard values ​​of the physical standard samples of the main amino acids (serine, glycine, alanine and tyrosine) in mulberry silk are the total average values ​​of the collaborative determination results, and the expanded uncertainty is: U CRM = k × u CRM , expansion factor = 2. After rounding, the standard values ​​and uncertainties of the physical standard samples of the main amino acids (serine, glycine, alanine and tyrosine) in mulberry silk are shown in Table 9.

[0116] Table 9. Standard values ​​and uncertainty results

[0117]

[0118] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent transformation or modification made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a physical standard sample of amino acid content in mulberry silk, characterized in that: The following steps are involved: S1. Select mulberry silk raw materials and remove yellow spots and black spots; S2. Prepare a degumming solution and heat it in a water bath, place the mulberry silk raw material after impurities removal in step S1 in the degumming solution, make the degumming solution fully infiltrate the mulberry silk, stir continuously, and perform alkali degumming for 20 to 30 minutes; S3. The mulberry silk raw material after alkali degumming in step S2 is washed with warm water and then dehydrated; S4. Repeat steps S2 and S3 twice with the dehydrated silk raw material in step S3, followed by dehydration and drying; S5. The mulberry silk raw material after drying in step S4 is subjected to weight gain treatment to obtain a weight-gained mulberry silk sample; S6. The weight-gained silk sample obtained in step S5 is first washed in a water bath, then washed with cold water, and then dehydrated and dried to obtain a physical standard sample of the amino acid content in the silk; S7. Packing the physical standard sample of amino acid content in silk obtained in step S6; S8. Check the uniformity and stability of the physical standard sample of the amino acid content in the silk obtained in step S6; S9. Determine the values ​​and uncertainty of the serine, glycine, alanine and tyrosine contents in the physical standard sample of amino acid content in the mulberry silk obtained in step S6.

2. The method for preparing a physical standard sample of amino acid content in mulberry silk according to claim 1, characterized in that: The degumming solution in step S2 includes 3-6 g / L of sodium bicarbonate and 4-7 g / L of silk refining agent.

3. The method for preparing a physical standard sample of amino acid content in mulberry silk according to claim 1, characterized in that: The bath ratio of the alkali degumming method in step S2 is 1:40-60.

4. The method for preparing a physical standard sample of amino acid content in mulberry silk according to claim 1, characterized in that: The water bath temperature of the alkali degumming process in step S2 is 80-100°C.

5. The method for preparing a physical standard sample of amino acid content in mulberry silk according to claim 1, characterized in that: The washing temperature of the warm water washing in step S3 is 40-60°C.

6. The method for preparing a physical standard sample of amino acid content in mulberry silk according to claim 1, characterized in that: The weight increase treatment in step S5 specifically includes the following steps: after injecting 25 to 40 L of water into the silk weight increase reactor, adding 700 to 1200 g of silk weight increase agent, adjusting the solution pH to 2 to 3 with glacial acetic acid, heating to 70 to 100° C., and obtaining a mulberry silk weight increase liquid; placing the mulberry silk raw material dried in step S4 in the mulberry silk weight increase liquid, starting to stir at a stirring rate of 200 to 500 r / min, and after stirring for 5 to 10 minutes, adding 20 to 40 g of initiator, stirring continuously during the addition process, and then keeping warm for 80 to 100 minutes, draining the solution, and obtaining a weight increase mulberry silk sample.

7. The method for preparing a physical standard sample of amino acid content in mulberry silk according to claim 6, characterized in that: The silk weighting agent is methacrylamide, and the initiator is potassium persulfate.

8. The method for preparing a physical standard sample of amino acid content in mulberry silk according to claim 1, characterized in that: In step S6, the water bath cleaning temperature is 40-60°C, and the cold water cleaning temperature is 15-25°C.

9. The method for preparing a physical standard sample of amino acid content in mulberry silk according to claim 1, characterized in that: The sample packaging method in step S7 is as follows: the physical standard sample of amino acid content in mulberry silk obtained in step S6 is cut into pieces of 1 to 2 mm in length, mixed evenly, and then packaged, with 1.5 to 2.0 g of sample in each bag; the inner bag is packaged with food-grade polypropylene and the bag mouth is melt-sealed; the outer packaging is sealed with an aluminum foil bag for a second time.

10. A physical standard sample of amino acid content in mulberry silk, characterized in that: The physical standard sample of amino acid content in mulberry silk is prepared based on any one of the preparation methods of claims 1-9.

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