A method for rapid detection of illegally added bisacodyl derivatives in SERS-based gel

Abstract

This invention discloses a rapid detection method for illegally added bisacodyl derivatives in SERS-based gels, comprising the following steps: Step 1: preparing a gold nanoparticle sol; Step 2: preparing a coagulant; Step 3: sample pretreatment to obtain the test solution; Step 4: using the gold nanoparticle sol from Step 1 and the coagulant from Step 2 to detect the test solution. This invention develops a detection method based on surface-enhanced Raman spectroscopy, selecting two types of jelly—strawberry flavor and cola flavor—as carriers, and developing a simple pretreatment method with a detection limit of 20 ppb. This method improves the sensitivity and speed of sample detection, reduces detection costs, facilitates food market inspection and supervision, and can effectively combat such illegal additive activities.

Description

Technical Field

[0001] This invention relates to the field of food testing technology, and in particular to a rapid detection method for illegally added bisacodyl derivatives in SERS-based gels. Background Technology

[0002] With the improvement of social and economic development and living standards, people have been paying more and more attention to weight and health in recent years, and the demand for weight loss products has also increased. However, the domestic market for related products started late, lacks standards, and has an imperfect regulatory system. In addition, driven by profit, unscrupulous merchants often illegally add chemical drugs to ordinary food and health food to achieve the goal of rapid weight loss. The illegally added chemical drug ingredients in food pose a great threat to consumers' health.

[0003] Bisaccharide is a laxative with strictly regulated dosage. Unscrupulous manufacturers constantly create new derivatives as illegal additives to evade regulations, posing a significant threat to public health. The most common carriers of bisaccharide derivatives and other illegal additives include: solid beverages, meal replacement powders, compressed candies, plum cakes, dried fruit, weight-loss capsules, weight-loss jellies, and enzyme jellies. According to cases of illegal additives reported by the State Administration for Market Regulation and local market supervision departments in recent years, weight-loss jellies and enzyme jellies have become popular products. The reason for this may be that bisaccharide has an extremely bitter taste, and capsules and tablets can mask this bitterness, but consumers are highly wary of capsules and have an aversion to them. Jelly (gel products), due to their high content of sugar, flavorings, acidulants, and gelatin, can effectively mask the bitterness of the drug, making it difficult to detect with normal senses, and giving the illusion of a "snack," lowering consumers' guard. Statistics show that jelly products have become one of the main carriers of bisaccharide derivatives and other illegal additives, possibly accounting for more than 40% of such cases.

[0004] Currently, there are almost no methods for detecting the illegal addition of bisacodyl derivatives. Illegal additions such as bisacodyl are mainly detected using liquid chromatography (LC) and liquid chromatography-tandem mass spectrometry (LC-MS / MS). These methods are reliable, stable, and reproducible, but the experimental process is complex, time-consuming, involves large and expensive testing equipment, and requires highly skilled personnel. They are generally used in laboratories and cannot meet the practical needs of rapid on-site screening. In contrast, surface-enhanced Raman spectroscopy (SERS) has extremely high sensitivity and specificity. This technology combines Raman spectroscopy with nanomaterials, utilizing the unique physicochemical properties of nanomaterials to amplify the signal. SERS technology has been widely used in the rapid on-site detection of illegally added chemical drugs and toxic substances in food, and related commercial products have been applied to various detection needs in the food, drug, and environmental protection fields with good results.

[0005] Sample preparation is a crucial step in the analysis of real samples, aiming to separate and enrich target analytes from complex sample matrices while removing interfering substances. Liquid-liquid extraction is the most classic traditional extraction method, requiring large amounts of organic solvents, resulting in high costs and environmental pollution. Solid-phase extraction (SPE) is also a widely used, broad-spectrum, and efficient sample preparation technique. Its principle is to use a solid adsorbent to adsorb the target compound or matrix interfering impurities in the liquid sample, achieving complete or partial separation of the matrix and interfering compounds, thus separating and enriching the target compound. For trace analysis, it significantly improves detection sensitivity. However, it is relatively expensive, and most materials are disposable. Furthermore, method development and optimization are complex; for beginners, establishing a new method can be time-consuming, requiring multiple experiments to find a balance. Therefore, finding a simple, low-cost, and rapid sample preparation method is of great significance. Summary of the Invention

[0006] This invention aims to address the problems of complex and time-consuming experimental procedures and large and expensive detection instruments and equipment involved in the detection of illegally added bisacodyl derivatives in gel products. It provides a rapid detection method for illegally added bisacodyl derivatives in gels based on SERS.

[0007] To achieve the above-mentioned technical objectives, the technical solution provided by this invention is as follows: A rapid detection method for illegally added bisacodyl derivatives in SERS-based gels includes the following steps: Step 1: Preparation of gold nanoparticle sol; Step 2: Prepare the coagulant; Step 3: Sample pretreatment to obtain the test solution; Step 4: Use the gold nanoparticle sol from Step 1 and the coagulant from Step 2 to test the test solution.

[0008] Bisacodyl derivatives are rich in benzene rings and various unsaturated bonds. These structures have high electron cloud density, making them easily polarized by incident light, resulting in strong and characteristic Raman scattering. Bisacodyl can be firmly chemisorbed onto the surface of AuNPs via nitrogen or oxygen atoms, greatly amplifying the signal. Pectin and sugar molecules have weak affinity for AuNPs and are difficult to adsorb onto their surfaces; they cannot enter the enhancement region of SERS, resulting in extremely weak signals. Although pigments themselves may be Raman-active molecules, their adsorption capacity to AuNPs is generally much weaker than that of bisacodyl. In the competitive adsorption process, bisacodyl occupies most of the active sites on the AuNP surface. Therefore, the signal of pigment molecules is not effectively amplified and does not interfere with the detection of bisacodyl derivatives.

[0009] Furthermore, the preparation method of the nano-gold sol in step 1 includes: adding 1% sodium citrate solution according to the ratio of chloroauric acid solution: citric acid solution = 100:1, stirring and heating until the liquid turns purple-red, cooling to room temperature, and the resulting nano-gold sol is stored at room temperature and away from light.

[0010] Furthermore, the concentration of the chloroauric acid solution is 0.01%; the gold nanoparticle sol also needs to be centrifuged at 6000-10000 rpm to remove the supernatant, and after resuspending at an equal volume, the obtained product is the purified gold nanoparticle sol, which should be stored at room temperature and protected from light.

[0011] Furthermore, in step 2, the coagulant is an aqueous solution of 1M sulfuric acid.

[0012] Further, the sample pretreatment includes the following steps: take 100g of sample (take all of the sample if the sample is less than 100g), and thoroughly mix it into a slurry; take 1mL of the slurry sample, centrifuge at 6000 rpm for 5-10 min, and the upper liquid is the test solution.

[0013] The present invention has the following beneficial effects: 1. Surface-enhanced Raman spectroscopy was used to detect illegally added bisacodyl derivatives, with a detection limit of ≤20 ppb.

[0014] 2. Pretreatment of gel products by methods such as crushing and centrifugation can eliminate interference from matrix effects and enable the detection of bisacodyl derivatives.

[0015] 3. Sulfuric acid aqueous solution, as a flocculant, can specifically promote the adsorption and aggregation of bisacodyl derivatives and gold nanoparticles, generating more hot spots and thus producing stronger Raman spectral signals.

[0016] 4. This invention can be completed within 10 minutes, requires very little from the experimenter, and can meet the detection requirements for the illegal addition of saccharin derivatives in outdoor and other locations. Attached Figure Description

[0017] Figure 1 The image shows the supernatant liquid after two types of jelly (A and B) have been crushed and centrifuged.

[0018] Figure 2 The image shows the surface-enhanced Raman spectrum of a bisacodyl derivative.

[0019] Figure 3 A represents the standard curve for bisacodyl derivatives: the vertical axis represents 1169 cm⁻¹. -1 The intensity of the characteristic peak is shown on the x-axis, which represents the concentration of the bisacodyl derivative standard in ppb; B is the limit of detection for the bisacodyl derivative.

[0020] Figure 4 A: Surface-enhanced Raman spectra of jelly sample 1 with different concentrations of bisacodyl derivatives; B: Surface-enhanced Raman spectra of jelly sample 2 with different concentrations of bisacodyl derivatives. Detailed Implementation

[0021] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0023] Example 1 A rapid detection method for illegally added bisacodyl derivatives includes the following steps: Step 1: Take 0.01% chloroauric acid aqueous solution in a round-bottom flask, stir and heat to boiling, add 1% sodium citrate solution according to the ratio of chloroauric acid solution: citric acid solution = 100:1, stir and heat until the liquid turns purple-red, cool to room temperature, and the resulting product is the gold nanoparticle sol, which should be stored at room temperature and protected from light; centrifuge the gold nanoparticle sol at 10,000 rpm, remove the supernatant, and resuspend it at an equal volume to obtain the purified gold nanoparticle sol, which should be stored at room temperature and protected from light; Step 2: Prepare an aqueous solution of 1M sulfuric acid. The resulting solution is the coagulant. Store at room temperature and away from light. Step 3: Take 2 mL of sample into a centrifuge tube and crush it with a dropper; Step 4: Take 100g of sample (take the entire sample if the sample weight is less than 100g), and thoroughly mix it into a slurry; take 1mL of the slurry sample, centrifuge at 6000 rpm for 5-10 min, and the upper liquid is the test solution; Step 5: Analyze the test solution using the gold nanoparticle sol from step a and the coagulant from step a. Negative spiked samples (positive samples) should be analyzed at 1008 cm⁻¹. -1 1169 cm -1 The sample exhibits a distinct Raman spectral peak, and the intensity increases with increasing content; the negative sample shows no obvious characteristic peak.

[0024] like Figure 1 The image shows the supernatant after two types of jelly (strawberry flavor and cola flavor) have been crushed and centrifuged.

[0025] Surface-enhanced Raman spectra of bisacodyl derivatives are shown below Figure 2 As shown, when the Raman spectrum is at 1008 cm⁻¹ -1 and 1169 cm -1 If Raman characteristic peaks appear in the sample, it indicates the presence of bisacodyl derivatives; otherwise, it is considered that the sample does not contain the analyte or the content is below the method detection limit.

[0026] Figure 2 Surface-enhanced Raman spectra of bisacodyl derivatives.

[0027] like Figure 3 As shown in Figure A, the linear range of the surface-enhanced Raman spectrum of the bisacodyl derivative is 50-2000 ppb. Figure 3 B is the spectrum of the detection limit of 20 ppb and the negative control.

[0028] like Figure 4 For A and B, within a certain range, the main difference when adding different concentrations of bisacodyl derivatives lies in the change of peak intensity with concentration.

[0029] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

[0030] The above detailed embodiments are a description of the present invention. It should not be considered that the specific embodiments of the present invention are limited to these descriptions. For those skilled in the art, several simple deductions and substitutions can be made without departing from the concept of the present invention, and all of these should be considered to fall within the protection scope of the present invention.

Claims

1. A rapid detection method for the illegal addition of bisacodyl derivatives to SERS-based gels, characterized in that, Includes the following steps: Step 1: Preparation of gold nanoparticle sol; Step 2: Prepare the coagulant; Step 3: Sample pretreatment to obtain the test solution; Step 4: Use the gold nanoparticle sol from Step 1 and the coagulant from Step 2 to test the test solution.

2. The rapid detection method for illegally added bisacodyl derivatives in a SERS-based gel according to claim 1, characterized in that, The preparation method of nano-gold sol in step 1 includes: adding 1% sodium citrate solution according to the ratio of chloroauric acid solution: citric acid solution = 100:1, stirring and heating until the liquid turns purple-red, cooling to room temperature, and the resulting nano-gold sol is stored at room temperature and away from light.

3. The rapid detection method for illegally added bisacodyl derivatives in a SERS-based gel according to claim 2, characterized in that, The concentration of the chloroauric acid solution is 0.01%. The gold nanoparticle sol needs to be centrifuged at 6000-10000 rpm to remove the supernatant. After resuspending the sol by equal volume, the result is the purified gold nanoparticle sol, which should be stored at room temperature and protected from light.

4. The rapid detection method for illegally added bisacodyl derivatives in a SERS-based gel according to claim 1, characterized in that, In step 2, the coagulant is an aqueous solution of 1M sulfuric acid.

5. The rapid detection method for illegally added bisacodyl derivatives in a SERS-based gel according to claim 1, characterized in that, Sample pretreatment includes the following steps: take the sample and thoroughly mix it into a slurry; take 1 mL of the slurry sample and centrifuge it at 6000 rpm for 5-10 min, the upper liquid is the test solution.

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