A microwave-assisted digestion method for strontium isotope detection in silkworm cocoons
By combining microwave-assisted digestion with a specific acid washing solution and resin separation, the problem of strontium isotope enrichment and separation in silkworm cocoons has been solved, achieving efficient and accurate strontium isotope detection, which is suitable for tracing the origin of silk artifacts.
Patent Information
- Application Number
- CN202211144754.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2022-09-20
- Publication Date
- 2025-10-31
- Estimated Expiration
- 2042-09-20
AI Technical Summary
Existing technologies are insufficient for effectively enriching strontium isotopes in silkworm cocoons, and conventional digestion methods may contaminate samples, affecting the accuracy of detection.
Microwave-assisted digestion combined with perchloric acid and hydrogen peroxide was used to digest organic matter in silkworm cocoons, and hydrochloric acid and acetic acid were used as eluents. Strontium isotopes were separated using Dowex 50W×8 cation exchange resin and Sr-Spec strontium-specific resin, simplifying the operation process.
It achieves efficient enrichment and separation of strontium isotopes, reduces sample loss, improves detection accuracy, simplifies operation steps, and is suitable for tracing the origin of precious silk artifacts.
Abstract
Description
Technical Field
[0001] This invention relates to the field of cultural relic testing technology, and in particular to a microwave-assisted digestion method for detecting strontium isotopes in silkworm cocoons. Background Technology
[0002] Chinese silk possesses rich cultural connotations and is a symbol of ancient culture. With the rise of the Silk Road, merchants brought Chinese silk to the European market. Through thousands of years of accumulation, Chinese silk has become world-renowned for its texture and elegance. In ancient times, people cultivated mulberry trees and raised silkworms, reeling silk from the cocoons, thus creating silk. In recent years, isotope tracing technology has become an important part of scientific archaeology due to its small sample requirements and high sensitivity. Compared with light stable isotopes, stable strontium isotopes are less prone to isotopic fractionation during plant growth and metabolism, making it a more accurate tracing method. However, due to the low strontium content and the preciousness of silk artifacts, there is an urgent need for a sample pretreatment method that consumes minimal resources and can enrich strontium isotopes. Summary of the Invention
[0003] To address the aforementioned technical problems, this invention provides a microwave-assisted digestion method for detecting strontium isotopes in silkworm cocoons.
[0004] The specific technical solution of this invention is: a microwave-assisted digestion method for strontium isotope detection in silkworm cocoons, comprising the following steps:
[0005] 1) Select intact, uncontaminated silkworm cocoons, remove the silkworm pupae from the cocoons, add the cocoon shells to a mixed solution of deionized water and ethanol, and sonicate to remove impurities from the surface of the cocoons; add the sonicated cocoon shells to deionized water, heat in a water bath, and then remove the cocoon shells and dry them.
[0006] In the above steps, the present invention first uses water bath heating to dissolve sericin in water, thereby removing sericin from the silkworm cocoon, which facilitates the next step of using perchloric acid and hydrogen peroxide to dissolve the organic matter in the silkworm cocoon.
[0007] 2) Ball mill the silkworm cocoon shells to obtain silkworm cocoon shell powder. Add the silkworm cocoon shell powder and 84Sr diluent together to a Teflon tank at a mass ratio of 0.05-0.15g:0.025-0.075g. Add 1.5-2.5ml of 70-72wt% perchloric acid solution. Heat the Teflon tank under open and ventilated conditions until the white smoke dissipates.
[0008] 3) Cool the solution and transfer it to a digestion vessel. Add 2-3 ml of 25-35 wt% hydrogen peroxide solution, seal the vessel, and transfer it to a microwave digester for microwave digestion. After digestion, add 3-5 ml of hydrochloric acid solution to dissolve the solution. After centrifugation, take 1-3 ml of the supernatant solution and label it as solution a.
[0009] In steps 2) and 3), this invention uses a combination of perchloric acid and hydrogen peroxide to digest the organic matter in silkworm cocoons. It uses a small amount of acid, is simple to operate, and can completely digest the cocoon shell powder in a short time. It does not introduce exogenous strontium and contaminate the sample, which is beneficial to the accuracy of strontium isotope detection. Furthermore, this invention uses microwave heating and strong acid to digest the sample, which, compared with conventional hot plate digestion methods, has advantages such as rapid sample dissolution under high temperature and pressure, low sample loss, and convenient operation.
[0010] 4) The cation exchange resin Dowex 50W×8 and Sr-Spec resin were loaded into the exchange column and labeled as column A and column B, respectively. They were washed with ultrapure water, column A was then washed with hydrochloric acid, and column B was then washed with acetic acid.
[0011] 5) Add solution a to column A, rinse with hydrochloric acid solution to obtain solution b; transfer solution b to a Teflon flask and heat to dryness under ventilation; add 4-6 ml of acetic acid solution to dissolve, centrifuge and take 1-3 ml of the supernatant, label it as solution c; add solution c to column B, rinse with acetic acid solution, label the eluent as solution d, and wait for strontium isotope detection.
[0012] This invention uses hydrochloric acid and acetic acid as eluents, and employs Dowex 50W×8 cation exchange resin and Sr-Spec strontium-specific resin to separate strontium from other ions and enrich the strontium isotope content in the sample. This separation method can effectively separate some interfering ions and Sr. Furthermore, using this method can improve separation efficiency, shorten separation time, and reduce reagent consumption. This is of great significance for measuring strontium isotope ratios using thermal ionization mass spectrometry (TIMS), and can be applied to silk artifacts, thus having significant implications for tracing the provenance of silk artifacts.
[0013] Preferably, in step 1), the volume ratio of deionized water to ethanol is (0.8-1.2):1, and the ultrasonic oscillation time is 10-15 min.
[0014] Preferably, in step 1), the heating temperature is 90-110℃ and the heating time is 1.5-2h; the drying temperature is 50-60℃ and the drying time is 2-4h.
[0015] Preferably, in step 2), the heating temperature is 110-120℃.
[0016] Preferably, in step 3), the digestion vessel is made of modified polytetrafluoroethylene (TFM); the digestion temperature is 150-180℃, the heating time is 20-30 min, and the digestion time is 10-15 min.
[0017] Preferably, in step 3), the concentration of the hydrochloric acid solution is 5-7 mol / L; the centrifugation speed is 3000-4000 r / min, and the time is 10-20 min.
[0018] Preferably, in step 4), the concentration of the hydrochloric acid solution is 2-3 mol / L and the amount used is 1-2 ml; the concentration of the acetic acid solution is 4-5 mol / L and the amount used is 1-2 ml.
[0019] Preferably, in step 5), 0.5-1.5 ml of 5-7 mol / L hydrochloric acid solution and 2-3 ml of 2-3 mol / L hydrochloric acid solution are added, and the mixture is rinsed alternately multiple times.
[0020] Preferably, in step 5), the heating temperature is 105-115℃.
[0021] As a preferred embodiment, the method is characterized in that: in step 5), an acetic acid solution with a concentration of 5-7 mol / L is added to dissolve the acetic acid, the centrifugation speed is 3000-4000 r / min, and the time is 10-20 min; 1-2.5 ml of acetic acid solution with a concentration of 5-7 mol / L and 1-3 ml of acetic acid solution with a concentration of 4-5 mol / L are added, and the mixture is rinsed alternately multiple times.
[0022] Compared with the prior art, the present invention has the following technical effects:
[0023] (1) This invention is a pretreatment method for enriching the strontium isotope content in silkworm cocoons.
[0024] (2) The present invention uses a combination of perchloric acid and hydrogen peroxide to digest organic matter in silkworm cocoons. It uses a small amount of acid and is simple to operate. It can completely digest silkworm cocoon powder in a short time without contaminating the sample, which is beneficial for strontium isotope detection.
[0025] (3) The present invention uses microwave heating and strong acid to digest the sample. Compared with the conventional hot plate digestion method, it has the advantages of rapid sample dissolution under high temperature and high pressure, low sample loss and convenient operation.
[0026] (4) In this invention, hydrochloric acid is used as the eluent, and Dowex 50W×8 cation exchange resin is used to initially separate strontium from other ions. Acetic acid is used as the eluent, and Sr-Spec resin is used to further separate and enrich the strontium isotope content in the sample. Detailed Implementation
[0027] The present invention will be further described below with reference to embodiments.
[0028] Example 1
[0029] 1) Take a whole, uncontaminated silkworm cocoon, remove the silkworm pupa, put the cocoon shell into a 50ml beaker, add 20.00ml of a mixed solution of deionized water and ethanol (volume ratio 1:1), and sonicate for 15 minutes to remove dust from the surface of the cocoon. Repeat the operation 3 times.
[0030] 2) Place the silkworm cocoon shells into a 100 ml beaker, add 50.00 ml of deionized water, and heat in a water bath at 100°C for 1.5 hours.
[0031] 3) Remove the cocoon shell and dry it at 60℃ for 2 hours.
[0032] 4) Grind the silkworm cocoon shells with a ball mill, weigh 0.05g of the silkworm cocoon shells, add 0.025g of 84Sr diluent to a Teflon container, add 1.5ml of 70wt% perchloric acid solution, and heat on a heating plate at 120℃ until the white smoke dissipates.
[0033] 5) After cooling, transfer the solution to a TFM digestion vessel, add 2 ml of 30 wt% hydrogen peroxide solution, and cover with the lid.
[0034] 6) Place the food in a microwave digester for digestion at a temperature of 150°C for 20 minutes and a digestion time of 10 minutes.
[0035] 7) After digestion, add 3 ml of 6 mol / L hydrochloric acid solution to dissolve, centrifuge at 3500 r / min for 15 min, and take 1 ml of the supernatant solution.
[0036] 8) Pack the cation exchange resin Dowex 50W×8 and Sr-Spec resin into the exchange column, labeled as column A and column B respectively. Wash each column three times with ultrapure water. Then wash column A twice with 1 ml of 2.5 mol / L hydrochloric acid and column B twice with 1 ml of 4.5 mol / L acetic acid.
[0037] 9) Add solution a to column A, then add 0.5 ml of 6 mol / L hydrochloric acid solution and 2 ml of 2.5 mol / L hydrochloric acid solution, and rinse alternately 3 times. Label this solution as solution b.
[0038] 10) Transfer liquid b to a Teflon tank and heat it at 110°C on a heating plate until it evaporates to dryness.
[0039] 11) Add 4 ml of acetic acid solution to dissolve, centrifuge at 3500 r / min for 15 min, and take 1.5 ml of the supernatant, which is labeled as solution c.
[0040] 12) Add solution c to column B, then add 1.5 ml of 6 mol / L acetic acid solution and 1 ml of 4.5 mol / L acetic acid solution, and rinse 3 times alternately. The rinsing solution is labeled as solution d and is ready for testing.
[0041] 13) The strontium isotope ratio of the treated sample was measured by thermal ionization mass spectrometry (TIMS). The average value of three measurements was 87Sr / 86Sr=0.710924, and the test error was less than 5%.
[0042] Example 2
[0043] 1) Take a whole, uncontaminated silkworm cocoon, remove the silkworm pupa, put the cocoon shell into a 50ml beaker, add 20.00ml of a mixed solution of deionized water and ethanol (volume ratio 1:1), and sonicate for 15 minutes to remove dust from the surface of the cocoon. Repeat the operation 3 times.
[0044] 2) Place the silkworm cocoon shells into a 100 ml beaker, add 50.00 ml of deionized water, and heat in a water bath at 100°C for 1.5 hours.
[0045] 3) Remove the cocoon shell and dry it at 60℃ for 2 hours.
[0046] 4) Grind the silkworm cocoon shells with a ball mill, weigh 0.1g of the silkworm cocoon shells, add 0.05g of 84Sr diluent to a Teflon container, add 2ml of 70wt% perchloric acid solution, and heat on a heating plate at 120℃ until the white smoke dissipates.
[0047] 5) After cooling, transfer the solution to a TFM digestion vessel, add 2.5 ml of 30 wt% hydrogen peroxide solution, and cover with the lid.
[0048] 6) Place the food in a microwave digester for digestion at a temperature of 165°C, a heating time of 24 minutes, and a digestion time of 13 minutes.
[0049] 7) After digestion, add 4 ml of 6 mol / L hydrochloric acid solution to dissolve, centrifuge at 3500 r / min for 15 min, and take 2 ml of the supernatant solution.
[0050] 8) Pack the cation exchange resin Dowex 50W×8 and Sr-Spec resin into the exchange column, labeled as column A and column B respectively. Wash each column three times with ultrapure water. Then wash column A twice with 1.5 ml of 2.5 mol / L hydrochloric acid and column B twice with 1.5 ml of 4.5 mol / L acetic acid.
[0051] 9) Add solution a to column A, then add 1 ml of 6 mol / L hydrochloric acid solution and 2.5 ml of 2.5 mol / L hydrochloric acid solution, and rinse 3 times alternately. Label this solution as solution b.
[0052] 10) Transfer liquid b to a Teflon tank and heat it at 110°C on a heating plate until it evaporates to dryness.
[0053] 11) Dissolve in 5 ml of acetic acid solution, centrifuge at 3500 r / min for 15 min, and take 2.5 ml of the supernatant, which is labeled as solution c;
[0054] 12) Add solution c to column B, then add 2 ml of 6 mol / L acetic acid solution and 2 ml of 4.5 mol / L acetic acid solution, and rinse 3 times alternately. The rinsing solution is labeled as solution d and is ready for testing.
[0055] 13) The strontium isotope ratio of the treated sample was measured by thermal ionization mass spectrometry (TIMS). The average value of three measurements was 87Sr / 86Sr=0.711409, and the test error was less than 5%.
[0056] Example 3
[0057] 1) Take a whole, uncontaminated silkworm cocoon, remove the silkworm pupa, put the cocoon shell into a 50ml beaker, add 20.00ml of a mixed solution of deionized water and ethanol (volume ratio 1:1), and sonicate for 15 minutes to remove dust from the surface of the cocoon. Repeat the operation 3 times.
[0058] 2) Place the silkworm cocoon shells into a 100 ml beaker, add 50.00 ml of deionized water, and heat in a water bath at 100°C for 1.5 hours.
[0059] 3) Remove the cocoon shell and dry it at 60℃ for 2 hours.
[0060] 4) Grind the silkworm cocoon shells with a ball mill, weigh 0.15g of the silkworm cocoon shells, add 0.075g of 84Sr diluent to a Teflon container, add 2.5ml of 70wt% perchloric acid solution, and heat on a heating plate at 120℃ until the white smoke dissipates.
[0061] 5) After cooling, transfer the solution to a TFM digestion vessel, add 3 ml of 30 wt% hydrogen peroxide solution, and cover with the lid.
[0062] 6) Place the food in a microwave digester for digestion at a temperature of 175°C, a heating time of 28 minutes, and a digestion time of 15 minutes.
[0063] 7) After digestion, add 4.5 ml of 6 mol / L hydrochloric acid solution to dissolve, centrifuge at 3500 r / min for 15 min, and take 2.5 ml of the supernatant solution.
[0064] 8) Pack the cation exchange resin Dowex 50W×8 and Sr-Spec resin into the exchange column, labeled as column A and column B respectively. Wash each column three times with ultrapure water. Then wash column A twice with 1.5 ml of 2.5 mol / L hydrochloric acid and column B twice with 1.5 ml of 4.5 mol / L acetic acid.
[0065] 9) Add solution a to column A, then add 1 ml of 6 mol / L hydrochloric acid solution and 2.5 ml of 2.5 mol / L hydrochloric acid solution, and rinse 3 times alternately. Label this solution as solution b.
[0066] 10) Transfer liquid b to a Teflon tank and heat it at 110°C on a heating plate until it evaporates to dryness.
[0067] 11) Add 5.5 ml of acetic acid solution to dissolve, centrifuge at 3500 r / min for 15 min, and take 3 ml of the supernatant, which is labeled as solution c.
[0068] 12) Add solution c to column B, then add 2.5 ml of 6 mol / L acetic acid solution and 3 ml of 4.5 mol / L acetic acid solution, and rinse 3 times alternately. The rinsing solution is labeled as solution d and is ready for testing.
[0069] 13) The strontium isotope ratio of the treated sample was measured by thermal ionization mass spectrometry (TIMS). The average value of three measurements was 87Sr / 86Sr=0.711227, and the test error was less than 5%.
[0070] Unless otherwise specified, the raw materials and equipment used in this invention are all commonly used in the field; unless otherwise specified, the methods used in this invention are all conventional methods in the field.
[0071] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, alterations, and equivalent transformations made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.
Claims
1. A microwave-assisted digestion method for detecting strontium isotopes in silkworm cocoons, characterized in that: Includes the following steps: 1) Select intact, uncontaminated silkworm cocoons, remove the silkworm pupae from the cocoons, add the cocoon shells to a mixed solution of deionized water and ethanol, and sonicate to remove impurities from the surface of the cocoons; add the sonicated cocoon shells to deionized water, heat in a water bath, and then remove the cocoon shells and dry them. 2) Ball mill the silkworm cocoon shells to obtain silkworm cocoon shell powder. Add the silkworm cocoon shell powder and 84Sr diluent together to a Teflon tank at a mass ratio of 0.05-0.15g:0.025-0.075g. Add 1.5-2.5ml of 70-72wt% perchloric acid solution. Heat the Teflon tank under open and ventilated conditions until the white smoke dissipates. 3) Cool the solution and transfer it to a digestion vessel. Add 2-3 ml of 25-35 wt% hydrogen peroxide solution, seal the vessel, and transfer it to a microwave digester for microwave digestion. After digestion, add 3-5 ml of hydrochloric acid solution to dissolve the solution. After centrifugation, take 1-3 ml of the supernatant solution and label it as solution a. 4) The cation exchange resin Dowex 50W×8 and Sr-Spec resin were loaded into the exchange column and labeled as column A and column B, respectively. They were washed with ultrapure water, column A was washed with hydrochloric acid, and column B was washed with acetic acid. 5) Add solution a to column A, add 0.5-1.5 ml of 5-7 mol / L hydrochloric acid solution and 2-3 ml of 2-3 mol / L hydrochloric acid solution, and wash alternately several times to obtain solution b; transfer solution b to a Teflon flask and heat to dryness under ventilation; add 4-6 ml of 5-7 mol / L acetic acid solution to dissolve, centrifuge at 3000-4000 r / min for 10-20 min; after centrifugation, take 1-3 ml of the supernatant and label it as solution c; add solution c to column B, add 1-2.5 ml of 5-7 mol / L acetic acid solution and 1-3 ml of 4-5 mol / L acetic acid solution, and wash alternately several times. Label the eluent as solution d for strontium isotope detection.
2. The microwave-assisted digestion method as described in claim 1, characterized in that: In step 1), the volume ratio of deionized water to ethanol is (0.8-1.2):1, and the ultrasonic oscillation time is 10-15 min.
3. The microwave-assisted digestion method as described in claim 1 or 2, characterized in that: In step 1), The heating temperature is 90-110℃, and the heating time is 1.5-2 hours; The drying temperature is 50-60℃, and the drying time is 2-4 hours.
4. The microwave-assisted digestion method as described in claim 1, characterized in that: In step 2), the heating temperature is 110-120℃.
5. The microwave-assisted digestion method as described in claim 1, characterized in that: In step 3), The digestion vessel is made of modified polytetrafluoroethylene; The digestion temperature is 150-180℃, the heating time is 20-30 min, and the digestion time is 10-15 min.
6. The microwave-assisted digestion method as described in claim 1 or 5, characterized in that: In step 3), The concentration of the hydrochloric acid solution is 5-7 mol / L; The centrifugation speed is 3000-4000 r / min, and the time is 10-20 min.
7. The microwave-assisted digestion method as described in claim 1, characterized in that: In step 4), The concentration of the hydrochloric acid solution is 2-3 mol / L, and the volume used is 1-2 ml; The concentration of the acetic acid solution is 4-5 mol / L, and the volume used is 1-2 ml.
8. The microwave-assisted digestion method as described in claim 1, characterized in that: In step 5), the heating temperature is 105-115℃.