Laser Raman spectroscopy method for rapidly screening sulfur dioxide residues in traditional Chinese medicine and application of laser Raman spectroscopy method

Abstract

The invention relates to the technical field of medicine analysis and treatment detection, in particular to a laser Raman spectroscopy method for rapidly screening sulfur dioxide residues in traditional Chinese medicine and application of the laser Raman spectroscopy method. And finally, the optimal laser Raman spectroscopy is obtained. The method is good in specificity and durability, the detection limit is 400 mg / kg, and the Raman enhanced reagent has no interference on the test, so that the method is good in accuracy and has a wide application prospect.

Description

Technical Field

[0001] The present invention relates to the technical field of pharmaceutical analysis and therapeutic detection, and particularly relates to a laser Raman spectroscopy method for rapidly screening sulfur dioxide residues in traditional Chinese medicines and its application. Background Art

[0002] There are mainly two ways to introduce sulfur dioxide into traditional Chinese medicines: one is endogenous, mainly that environmental sulfur dioxide during the growth process of plants enters traditional Chinese medicines through the atmosphere or soil. The other is exogenous introduction, usually caused by the use of steps such as sulfur fumigation in unreasonable traditional Chinese medicine processing, resulting in excessive sulfur dioxide content in traditional Chinese medicines. Excessive residues of sulfur dioxide and sulfates in various valence states will cause strong irritation to the human body and endanger health. After a small amount of sulfur dioxide enters the body, it can be detoxified through normal body metabolism and excreted from the body through urine. However, if the intake seriously exceeds the standard, it will cause adverse effects on human health such as nausea, vomiting, and affecting calcium absorption. Therefore, in the Pharmacopoeia 2020 Edition, the residue detection limit of sulfur dioxide is strictly required. Among them, the sulfur dioxide residue in Chinese yam, gastrodia elata, asparagus, achyranthes bidentata, trichosanthes root, atractylodes macrocephala, bletilla striata, codonopsis pilosula, white peony root, and kudzu root shall not exceed 400 mg / kg, the sulfur dioxide residue in Chinese yam slices shall not exceed 10 mg / kg, and the sulfur dioxide residue in other traditional Chinese medicines shall not exceed 150 mg / kg. And three methods for determining sulfur dioxide residues are provided in detail, namely acid-base titration method, gas chromatography method, and ion chromatography method. However, the above methods have a slow detection speed and cannot obtain detection results quickly.

[0003] Surface enhanced Raman spectroscopy (SERS) technology, as a fingerprint spectroscopy technology with simple operation, rapidity, and sensitivity, Raman spectroscopy technology has a high application prospect in pesticide residue detection because of its simple detection method, fast detection speed, high sensitivity, and the ability to obtain the molecular vibration energy level spectrogram of the analyte.

[0004] In recent years, surface enhanced Raman spectroscopy (SERS) technology with molecular fingerprint information and trace species detection ability has been successfully used for the highly sensitive detection of trace harmful substances in the field of food safety. For example, the invention patent CN119354944A discloses a method for detecting sulfur dioxide in wine, a detection method based on the bimodal analysis of colorimetry and surface enhanced Raman spectroscopy, which can realize self-calibration of detection results, improve the accuracy of detection results, and enhance the detection efficiency. However, there are few detection methods for sulfur dioxide in traditional Chinese medicines.

[0005] Therefore, aiming at the residue of sulfur dioxide in traditional Chinese medicines and decoction pieces, the present invention uses surface enhanced Raman spectroscopy to establish a laser Raman spectroscopy method for rapidly screening sulfur dioxide residues in traditional Chinese medicines, so as to realize the rapid detection of sulfur dioxide. Summary of the Invention

[0006] In view of the above technical problems, the primary object of the present invention is to provide a laser Raman spectroscopy method for rapidly screening sulfur dioxide residues in traditional Chinese medicines. The method includes:

[0007] (1) Preparation of reference solution

[0008] Accurately weigh anhydrous sodium sulfite and add water to make a sodium sulfite solution as the sulfur dioxide standard solution;

[0009] (2) Preparation of test solution

[0010] Use a tissue grinder to crush the yam sample, weigh 0.2 g - 1.0 g of the sample with a balance and put it into a centrifuge tube, add an extraction solvent, shake well, and centrifuge to obtain the supernatant of the test solution;

[0011] (3) Purification of sample

[0012] Place the supernatant of the test solution obtained in step (2) in a purification material for purification to obtain the purified supernatant of the test solution;

[0013] (4) Addition of surface-enhanced nano reagent

[0014] Add a surface-enhanced nano reagent to the supernatant of the test solution purified in step (3), mix well and transfer it to the sample chamber, and use a Raman spectrometer to measure the surface-enhanced Raman spectrum. Set the excitation energy of the instrument ≥ 350 mW; data acquisition time: 1 s; the test results are displayed in real time;

[0015] (5) Compare the spectral information of the reference solution and the test solution.

[0016] Preferably, the extraction solvent in step (2) is one or more of water, dilute sulfuric acid, and 0.1 mol / L sodium hydroxide.

[0017] Preferably, the extraction solvent in step (2) is 0.1 mol / L sodium hydroxide.

[0018] Preferably, the purification material in step (3) is one or more of an adsorption carbon packet, multi-walled carbon nanotubes, and a mixed powder of multi-walled carbon nanotubes and anhydrous magnesium sulfate.

[0019] Preferably, the purification material in step (3) is one or more of a mixed powder of multi-walled carbon nanotubes and anhydrous magnesium sulfate.

[0020] Preferably, the surface-enhanced nano reagent in step (4) is a colloidal gold solution.

[0021] Preferably, the preparation method of the colloidal gold solution in step (4) is as follows: Take an aqueous solution of chloroauric acid and heat it to boiling. While stirring vigorously, accurately add an aqueous solution of trisodium citrate. The golden yellow aqueous solution of chloroauric acid turns red within 2 minutes, continue boiling, and after cooling, make up to 100 mL with distilled water.

[0022] Preferably, the addition ratio of the surface-enhanced nano reagent to the test sample solution in step (4) is 20:1 - 60:1.

[0023] Preferably, the addition ratio of the surface-enhanced nano reagent to the test sample solution in step (4) is 40:1 - 60:1.

[0024] Preferably, the addition ratio of the surface-enhanced nano reagent to the test sample solution in step (4) is 40:1.

[0025] The second object of the present invention is to provide the application of the laser Raman spectroscopy method in screening for sulfur dioxide residues in traditional Chinese medicines.

[0026] The beneficial effects of the present invention are: (1) The present invention provides a laser Raman spectroscopy method for rapidly screening sulfur dioxide residues in traditional Chinese medicines. The method optimizes the sample sampling amount, extraction solvent, purification material, preparation and dosage of the surface-enhanced nano reagent, and finally obtains the optimal laser Raman spectroscopy method;

[0027] (2) The surface-enhanced Raman spectrum of the blank test solution has no obvious Raman characteristic peak at 630 cm -1 The surface-enhanced Raman spectrum of the test solution containing sulfur dioxide has obvious Raman characteristic peaks at 630 cm -1 indicating that the method has good specificity.

[0028] (3) The surface-enhanced Raman spectrum of the blank test solution has no obvious Raman characteristic peak at 630 cm -1 The surface-enhanced Raman spectrum of the test solution containing sulfur dioxide has obvious Raman characteristic peaks at 630 cm -1 indicating that the method has good durability, and the detection limit is 400 mg / kg.

[0029] (4) The Raman enhancement reagent has no interference on the test, indicating that the method has good accuracy. Description of the Drawings

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required to be used in the embodiments. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings:

[0031] Figure 1 Spectral diagram of test solution for experiments

[0032] Figure 2 Spectral diagram of different sampling amounts

[0033] Figure 3 Spectral diagram of different extraction solvents

[0034] Figure 4 Spectral diagram of purification material investigation Note: 1. Adsorption carbon packet; 2. Multi-walled carbon nanotubes; 3. Multi-walled carbon nanotubes and anhydrous magnesium sulfate

[0035] Figure 5 Spectral diagram of the amount of surface-enhanced nano-reagent taken

[0036] Figure 6 Spectral diagram of specificity test

[0037] Figure 7 Spectral diagram of sulfur dioxide test for Codonopsis pilosula samples

[0038] Figure 8 Spectral diagram of sulfur dioxide test for Dioscorea opposita samples

[0039] Figure 9 Spectral diagram of sulfur dioxide test for Pueraria lobata samples

[0040] Figure 10 Spectral diagram of sulfur dioxide test for Paeonia lactiflora samples

[0041] Figure 11 Spectral diagram of sulfur dioxide test for Atractylodes macrocephala samples

[0042] Figure 12 Spectral diagram of sulfur dioxide test for Bletilla striata samples

[0043] Figure 13 Spectral diagram of sulfur dioxide test for Pinellia ternata samples

[0044] Figure 14 Spectral diagram of sulfur dioxide test for Gastrodia elata samples

[0045] Figure 15 Spectral diagram of sulfur dioxide test for different batches of Codonopsis pilosula samples Detailed implementation manners

[0046] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0047] To make the above objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0048] In the following examples, the sources of some reagents and materials are as follows: sodium hydroxide (Sinopharm Chemical Reagent Co., Ltd.), anhydrous sodium sulfite (National Institutes for Food and Drug Control), sulfur dioxide standard solution (Shanghai Yuanye); sulfuric acid (Sinopharm Chemical Reagent Co., Ltd.), anhydrous magnesium sulfate (Sinopharm Chemical Reagent Co., Ltd.), gold nanocolloid solution (Xianfeng Nano), purified water (Watsons), chloroauric acid (Sinopharm Chemical Reagent Co., Ltd.), trisodium citrate (Sinopharm Chemical Reagent Co., Ltd.), multi-walled carbon nanotubes, adsorption carbon packets.

[0049] Instrumentation: Balance: sensitivity not exceeding 0.1 g; tissue grinder; high-speed centrifuge: rotation speed not less than 8000 rpm; adjustable pipette: 10 μL; RS1000TC rapid detector for harmful residues in traditional Chinese medicine (Vision): excitation wavelength 785 ± 1 nm, line width < 0.2 nm, energy ≤ 450 mW, spectral resolution ≤ 15 cm-1.

[0050] It should be noted that in the following examples, unless otherwise specified, the methods described are all conventional methods, and the reagents described are all commercially available.

[0051] Convert sulfur dioxide into sodium sulfite, and the surface-enhanced Raman spectrum of sodium sulfite produces Raman characteristic peaks at 630 cm -1 This method can be used to detect sulfur dioxide. Codonopsis pilosula containing sulfur dioxide is extracted with an aqueous sodium hydroxide solution, and sulfur dioxide reacts with sodium hydroxide to form sodium sulfite. After purification, the sample extract is mixed with a surface-enhanced nano reagent, and the surface-enhanced Raman spectrum will show the Raman characteristic peak of sodium sulfite at 630 cm -1 Using this method, it can be judged whether sulfur dioxide is contained in Codonopsis pilosula.

[0052] Example 1

[0053] 1. Solution Preparation

[0054] 1.1 Preparation of reference solution

[0055] Accurately weigh an appropriate amount of anhydrous sodium sulfite, and add water to make a solution containing about 4 mg of sodium sulfite per ml as the sulfur dioxide standard solution.

[0056] 1.2 Preparation of 0.1 mol / L sodium hydroxide solution

[0057] Take 0.2 g of solid sodium hydroxide and dilute it with water to 50 mL to prepare 0.1 mol / L aqueous sodium hydroxide solution.

[0058] 1.3 Preparation of dilute sulfuric acid solution

[0059] Take 5.7 mL of sulfuric acid and dilute it with water to 100 mL to obtain it.

[0060] 1.4 Preparation of surface-enhanced nano-reagent

[0061] Colloidal gold: Take 100 mL of 0.01% chloroauric acid (AuCl3·HCl·4H2O) aqueous solution and heat it to boiling. Under vigorous stirring, accurately add 1.0 mL of 1% trisodium citrate (Na3C6H5O7) aqueous solution. The golden-yellow chloroauric acid aqueous solution turns red within 2 min, continue to boil for 15 min, and make up to 100 mL with distilled water after cooling.

[0062] 2. Raman spectroscopy determination method

[0063] (1) Preparation of test solution

[0064] Use a tissue grinder to crush no less than 5 g of yam samples. Weigh 0.5 g of the sample with a balance and put it into a 15 ml centrifuge tube. Add 5 mL of extraction solvent, shake well for 60 seconds, and centrifuge at 1000 rpm for 5 minutes to obtain the supernatant of the test solution.

[0065] (2) Purification of the sample

[0066] Place the supernatant of the test solution obtained in step (1) in the purification material for purification to obtain the purified supernatant of the test solution.

[0067] (3) Addition of surface-enhanced nano-reagent

[0068] Add the surface-enhanced nano-reagent to the supernatant of the test solution purified in step (2). After thorough mixing, transfer it to the sample chamber and use a Raman spectrometer to measure the surface-enhanced Raman spectrum. Set the excitation energy of the instrument ≥ 350 mW; data acquisition time: 1 s; the test results are displayed in real time.

[0069] 3. Optimization experiment

[0070] 3.1 Investigation of interference of experimental test solutions

[0071] Apply the solutions prepared in step 1.2 (extract 2), 1.3 (extract 1), and 1.4 (surface-enhanced nano-reagent) to the above-mentioned determination method, and observe the interference of each solution.

[0072] The results are as Figure 1 shown. There are no Raman characteristic peaks in the surface-enhanced Raman spectra of the 3 test solutions at 630 cm -1 It shows that the extraction solutions used in the experiment and the added surface-enhanced nano-reagent itself have no interference on the determination process of sulfur dioxide residue.

[0073] 3.2 Selection of Sample Sampling Amount

[0074] Raman spectroscopy measurement conditions: Set the instrument excitation energy ≥ 350 mW; data acquisition time: 1 s; test results are displayed in real time. Sequentially take 400 μL of surface-enhanced nano reagent and 10 μL of test solution and place them in a sample vial. After thorough mixing, transfer them to the sample chamber and use a Raman spectrometer to measure the surface-enhanced Raman spectrum.

[0075] Preparation of test solution: Use a tissue grinder to crush not less than 5 g of Codonopsis pilosula samples. Weigh 0.2 g, 0.5 g, and 1.0 g of the samples separately with a balance and put them into 15 ml centrifuge tubes. Add 5 mL of 0.1 mol / L sodium hydroxide solution, shake well for 60 seconds, and centrifuge at 1000 rpm for 5 minutes. Take 1 mL of the supernatant and transfer it to a 2 mL centrifuge tube containing 0.16 g of purification material, shake well for 30 seconds, and centrifuge at 8000 rpm for 1 minute. Then take 0.5 mL of the supernatant and transfer it to another 2 mL centrifuge tube containing 0.1 g of purification material, shake well for 30 seconds, and centrifuge at 8000 rpm for 1 minute. The supernatant is to be tested.

[0076] As Figure 2 shown, when the sampling amount is 0.2 g, the peak of sulfur dioxide is small, affecting the reading of the test results. When the sampling amount is 1.0 g, the peak shape of sulfur dioxide is the best, but the response of other miscellaneous peaks is relatively high. When the sampling amount is 0.5 g, the peak shape of sulfur dioxide is better, and the response of other miscellaneous peaks is relatively low. Therefore, the final selected sample sampling amount is 0.5 g.

[0077] 3.3 Selection of Extraction Solvent

[0078] Raman spectroscopy measurement conditions: Set the instrument excitation energy ≥ 350 mW; data acquisition time: 1 s; test results are displayed in real time. Sequentially take 400 μL of surface-enhanced nano reagent and 10 μL of test solution and place them in a sample vial. After thorough mixing, transfer them to the sample chamber and use a Raman spectrometer to measure the surface-enhanced Raman spectrum.

[0079] Preparation of test solution: Use a tissue grinder to crush not less than 5 g of Codonopsis pilosula samples. Weigh 0.5 g of the sample, weigh 3 samples in parallel, and put them into 15 ml centrifuge tubes respectively. Add 5 mL of 0.1 mol / L sodium hydroxide solution, 5 mL of dilute sulfuric acid solution, and 5 mL of aqueous solution respectively, shake well for 60 seconds, and centrifuge at 1000 rpm for 5 minutes. Take 1 mL of the supernatant and transfer it to a 2 mL centrifuge tube containing 0.16 g of purification material, shake well for 30 seconds, and centrifuge at 8000 rpm for 1 minute. Then take 0.5 mL of the supernatant and transfer it to another 2 mL centrifuge tube containing 0.1 g of purification material, shake well for 30 seconds, and centrifuge at 8000 rpm for 1 minute. The supernatant is to be tested.

[0080] As Figure 3 shown, when the aqueous solution is used as the extraction solution, the extraction rate of sulfur dioxide is relatively low, and the peak of sulfur dioxide is very small. Therefore, the aqueous solution is not considered as the extraction solution. When the dilute sulfuric acid solution and 0.1 mol / L sodium hydroxide solution are used as the extraction solutions, the peak shapes of sulfur dioxide are both good. However, the response of the miscellaneous peaks in the dilute sulfuric acid is relatively high, and sulfuric acid is an easily produced drug reagent. Therefore, the 0.1 mol / L sodium hydroxide solution is finally selected as the extraction solvent.

[0081] 3.4 Selection of purification materials

[0082] Preparation of test solution: Use a tissue grinder to crush no less than 5 g of Chinese yam samples. Weigh 0.5 g of the sample with a balance and put it into a 15 ml centrifuge tube. Add 5 mL of 0.1 mol / L sodium hydroxide solution, shake well for 60 seconds, and centrifuge at 1000 rpm for 5 minutes. Take 1 mL of the supernatant into a 2 mL centrifuge tube containing 0.16 g of adsorption carbon packet, multi-walled carbon nanotubes, and a mixed powder of multi-walled carbon nanotubes and anhydrous magnesium sulfate, shake well for 30 seconds, and centrifuge at 8000 rpm for 1 min. Then take 0.5 mL of the supernatant into another 2 mL centrifuge tube containing 0.1 g of adsorption carbon packet, multi-walled carbon nanotubes, and a mixed powder of multi-walled carbon nanotubes and anhydrous magnesium sulfate, shake well for 30 seconds, and centrifuge at 8000 rpm for 1 min. The supernatant is to be tested.

[0083] As Figure 4 shown, when the adsorption carbon packet and multi-walled carbon nanotubes are used alone as purification materials, the color of the sample is relatively deep, and the decolorization and purification are incomplete. However, the solution of the mixed powder of multi-walled carbon nanotubes and anhydrous magnesium sulfate is clear and transparent, and the purification effect is the best. Therefore, the mixed powder of multi-walled carbon nanotubes and anhydrous magnesium sulfate is finally selected as the purification material. 3.5 Selection of the dosage of surface-enhanced nano-reagent

[0084] Preparation of test solution: Use a tissue grinder to crush no less than 5 g of Codonopsis pilosula samples. Weigh 0.5 g of the sample with a balance and put it into a 15 ml centrifuge tube. Add 5 mL of 0.1 mol / L sodium hydroxide solution, shake well for 60 seconds, and centrifuge at 1000 rpm for 5 minutes. Take 1 mL of the supernatant into a 2 mL centrifuge tube containing 0.16 g of the purification material, shake well for 30 seconds, and centrifuge at 8000 rpm for 1 min. Then take 0.5 mL of the supernatant into another 2 mL centrifuge tube containing 0.1 g of the purification material, shake well for 30 seconds, and centrifuge at 8000 rpm for 1 min. The supernatant is to be tested.

[0085] Raman spectroscopy measurement conditions: Set the instrument excitation energy ≥ 350 mW; data acquisition time: 1 s; test results are displayed in real time. Sequentially take 200 μL, 400 μL, and 600 μL of the surface-enhanced nano reagent and place them in a sample vial, then add 10 μL of the test solution respectively. After thorough mixing, transfer them into the sample chamber and use a Raman spectrometer to measure the surface-enhanced Raman spectrum.

[0086] As Figure 5 shown, when the sampling amount of the surface-enhanced Raman reagent is 200 μL, the enhancement effect of the sulfur dioxide peak is poor and the peak of sulfur dioxide is very small, so it is not selected. When the sampling amounts of the surface-enhanced Raman reagent are 400 μL and 600 μL, the peak shapes of sulfur dioxide are similar, but when it is 600 μL, the responses of other miscellaneous peaks increase. Therefore, the final sampling amount of the surface-enhanced Raman reagent selected is 400 μL.

[0087] After the above experimental optimization, the final selected sample sampling amount is 0.5 g, 0.1 mol / L sodium hydroxide solution as the extraction solvent, a mixed powder of multi-walled carbon nanotubes and anhydrous magnesium sulfate as the purification material, and the sampling amount of the surface-enhanced Raman reagent is 400 μL. Therefore, the method described in the following examples is:

[0088] (1) Preparation of test solution

[0089] Use a tissue grinder to crush no less than 5 g of yam samples. Weigh 0.5 g of the sample with a balance and put it into a 15 ml centrifuge tube. Add 5 mL of 0.1 mol / L sodium hydroxide solution, shake thoroughly for 60 seconds, and centrifuge at 1000 rpm for 5 minutes to obtain the supernatant of the test solution.

[0090] (2) Purification of the sample

[0091] Place the supernatant of the test solution obtained in step (1) into the mixed powder of multi-walled carbon nanotubes and anhydrous magnesium sulfate for purification to obtain the purified supernatant of the test solution.

[0092] (3) Addition of surface-enhanced nano reagent

[0093] Add 400 μL of colloidal gold solution to the supernatant of the test solution purified in step (2). After thorough mixing, transfer it into the sample chamber and use a Raman spectrometer to measure the surface-enhanced Raman spectrum. Set the instrument excitation energy ≥ 350 mW; data acquisition time: 1 s; test results are displayed in real time.

[0094] Example 2. Methodological verification

[0095] 1. Specificity test

[0096] Take appropriate amounts of blank solution without sulfur dioxide, reference solution, and test solution, and inject and measure according to the Raman spectroscopy conditions under the above optimal conditions.

[0097] The results are shown in Figure 6 As shown, the surface-enhanced Raman spectrum of the blank test solution has no obvious Raman characteristic peaks at 630 cm -1 The surface-enhanced Raman spectrum of the test solution containing sulfur dioxide has obvious Raman characteristic peaks at 630 cm -1 There are obvious Raman characteristic peaks. Thus, it can be seen that the blank has no interference, indicating that the method has good specificity.

[0098] 2. Durability test

[0099] To investigate the durability of the method, traditional Chinese medicine powders that are easily contaminated by sulfur dioxide, such as the powders of Codonopsis pilosula, Bletilla striata, Pinellia ternata, Paeonia lactiflora, Atractylodes macrocephala, Gastrodia elata, Dioscorea opposita, Pueraria lobata, etc., were selected. Samples were prepared according to the above-mentioned test solution extraction method, and the corresponding reference solution was prepared according to the reference solution preparation method. Under the corresponding chromatographic conditions, appropriate amounts of blank solution, reference solution, and test solution were taken and injected for determination under the Raman spectral conditions under the above optimal conditions.

[0100] The results are shown in Figures 7-14 , the surface-enhanced Raman spectrum of the blank test solution has no obvious Raman characteristic peaks at 630 cm -1 The surface-enhanced Raman spectrum of the test solution containing sulfur dioxide has obvious Raman characteristic peaks at 630 cm -1 There are obvious Raman characteristic peaks (signal-to-noise ratio > 3) (the positions of the Raman characteristic peaks are marked by dotted lines), indicating that the method has good durability.

[0101] 3. Detection limit

[0102] In the Chinese Pharmacopoeia (2020 Edition), the requirements for the residual detection limit of sulfur dioxide are that for Dioscorea opposita, Gastrodia elata, Asparagus cochinchinensis, Achyranthes bidentata, Trichosanthes kirilowii, Atractylodes macrocephala, Bletilla striata, Codonopsis pilosula, Paeonia lactiflora, and Pueraria lobata, it should not exceed 400 mg / kg; for Dioscorea opposita slices, it should not exceed 10 mg / kg; and for other traditional Chinese medicines, the sulfur dioxide residue should not exceed 150 mg / kg. The purpose of establishing this method is to establish a rapid screening qualitative method. Therefore, considering the interference factors such as the environment in the actual detection process, the detection limit was finally determined to be 400 mg / kg.

[0103] 4. Accuracy

[0104] Six batches of samples whose sulfur dioxide residue contents had been measured by acid-base titration were taken, and the test solution and reference solution were prepared according to the above method, and then injected for determination under the spectral conditions under the optimal conditions.

[0105] The results are shown in Figure 15 , the surface-enhanced Raman spectra of 3 negative Codonopsis pilosula samples have no Raman characteristic peaks at 630 cm -1 All. The surface-enhanced Raman spectra of 3 Codonopsis pilosula samples with sulfur dioxide content ≥ 400 mg / kg have Raman characteristic peaks at 630 cm -1All have obvious Raman characteristic peaks. The Raman enhancement reagent has no interference on the test. It shows that the accuracy of this method is good.

[0106] Through the determination of 8 different traditional Chinese medicines and 6 batches of Codonopsis pilosula samples, it is found that this method can be used for the rapid screening and control of sulfur dioxide residues in traditional Chinese medicines.

[0107] In summary, the present invention provides a laser Raman spectroscopy method for rapidly screening sulfur dioxide residues in traditional Chinese medicines. The method optimizes the sample sampling amount, extraction solvent, purification material, preparation and dosage of surface-enhanced nano-reagent, and finally obtains the optimal laser Raman spectroscopy method; the surface-enhanced Raman spectrum of the blank test solution is at 630 cm -1 There is no obvious Raman characteristic peak, and the surface-enhanced Raman spectrum of the test solution containing sulfur dioxide is at 630 cm -1 There is an obvious Raman characteristic peak, indicating that the specificity of this method is good. The surface-enhanced Raman spectrum of the blank test solution is at 630 cm -1 There is no obvious Raman characteristic peak, and the surface-enhanced Raman spectrum of the test solution containing sulfur dioxide is at 630 cm -1 There is an obvious Raman characteristic peak, indicating that the durability of this method is good, and the detection limit is 400 mg / kg. The Raman enhancement reagent has no interference on the test, indicating that the accuracy of this method is good.

Claims

1. A laser Raman spectroscopy method for rapid screening of sulfur dioxide residues in traditional Chinese medicines, characterized in that, The method described above includes: (1) Preparation of reference solution Accurately weigh anhydrous sodium sulfite, and add water to make a sodium sulfite solution, which is used as the sulfur dioxide standard solution. (2) Preparation of test solution Use a tissue grinder to crush the yam sample, weigh 0.2 g - 1.0 g of the sample with a balance and put it into a centrifuge tube, add the extraction solvent, shake well, and centrifuge to obtain the supernatant of the test solution. (3) Purification of the sample Place the supernatant of the test solution obtained in step (2) in a purification material for purification to obtain the purified supernatant of the test solution. (4) Addition of surface-enhanced nano reagent Add the surface-enhanced nano reagent to the purified supernatant of the test solution obtained in step (3), mix well and transfer it to the sample chamber, and use a Raman spectrometer to measure the surface-enhanced Raman spectrum. Set the excitation energy of the instrument to be ≥ 350 mW; data acquisition time: 1 s; the test results are displayed in real time. (5) Compare the spectral information of the reference solution and the test solution.

2. The laser Raman spectroscopy method according to claim 1, wherein The extraction solvent described in step (2) is one or more of water, dilute sulfuric acid, and 0.1 mol / L sodium hydroxide solution.

3. The laser Raman spectroscopy method according to claim 1, characterized in that, The purification material described in step (3) is one or more of an adsorption carbon packet, multi-walled carbon nanotubes, and a mixed powder of multi-walled carbon nanotubes and anhydrous magnesium sulfate.

4. The laser Raman spectroscopy method according to claim 1, wherein The surface-enhanced nano reagent described in step (4) is a colloidal gold solution.

5. The laser Raman spectroscopy method according to claim 4, characterized in that, The preparation method of the colloidal gold solution described in step (4) is as follows: Heat the aqueous solution of chloroauric acid to boiling, and accurately add the aqueous solution of trisodium citrate under vigorous stirring. The golden-yellow aqueous solution of chloroauric acid turns red within 2 min, continue to boil, and make up to 100 mL with distilled water after cooling.

6. The laser Raman spectroscopy method according to claim 1, characterized in that, The addition ratio of the surface-enhanced nano reagent described in step (4) to the test solution is 20:1 - 60:

1.

7. The laser Raman spectroscopy method according to claim 1, characterized in that, The addition ratio of the surface-enhanced nano reagent described in step (4) to the test solution is 40:1 - 60:

1.

8. The application of the laser Raman spectroscopy method according to any one of claims 1 - 7 in screening for sulfur dioxide residues in traditional Chinese medicines.

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