Method for detecting glyphosate in baby corn

Abstract

The invention discloses a method for detecting glyphosate in baby corn. The method comprises the following steps: firstly, extracting glyphosate from fresh baby corn by adopting a weakly acidic aqueous solution, then purifying by adopting a mixed anion exchange column to obtain an eluent, blow-drying the eluent, ultrasonically dissolving by using methanol, and passing through a microporous filter membrane to prepare a solution to be detected; and determining the concentration of the glyphosate solution by adopting the composite fluorescent probe. According to the method for detecting the glyphosate in the baby corn, the weak acid aqueous solution is adopted for extracting the glyphosate in the sample, the composite fluorescent probe is adopted for determination, the interference on the detection result is small, and the recovery rate is high. The citric acid and the fumaric acid in the extracting solution are combined for use, and the compounds shown in the formula I and the formula II are combined for use, so that a synergistic effect is achieved.

Description

Technical Field

[0001] This invention belongs to the field of food testing technology, specifically relating to a method for detecting glyphosate in baby corn. Background Technology

[0002] Baby corn is the tender young ear of corn, usually harvested shortly after the corn plant tassels and silks, but before it matures. It resembles a small bamboo shoot or a small pagoda in shape, with a crisp and tender texture, a sweet taste, and a subtle corn aroma. It is rich in dietary fiber, vitamins (such as folic acid and vitamin C), and minerals, while being relatively low in calories. It can be cooked in a variety of ways, including quick stir-frying, cold salads, soups, hot pot, or as a salad dressing, absorbing broth and seasonings very well.

[0003] Accurate detection of glyphosate residues in baby corn is crucial for ensuring food safety and compliance with regulatory standards. The detection process faces multiple interferences from the complex matrix of baby corn and the physicochemical properties of glyphosate itself, directly affecting the accuracy and reliability of the analytical results. These interfering factors mainly include matrix interference, ion inhibition effects, and challenges in sample pretreatment. The matrix composition of baby corn is complex, containing abundant pigments such as carotenoids, lipids, waxes, carbohydrates, proteins, and amino acids. When using organic solvents (such as methanol-water mixtures) to extract the target analyte, these co-extractants are extracted along with glyphosate and its metabolites (such as aminomethylphosphonic acid, AMPA). Especially when using liquid chromatography-tandem mass spectrometry (LC-MS / MS), these coexisting matrix components can significantly inhibit or enhance the ionization efficiency of the target compound, i.e., a matrix effect occurs. Ion inhibition is particularly common, with inhibition rates reaching 50% to 80%. Without effective compensation, this will seriously affect the accuracy of quantification. To overcome matrix interference, targeted sample purification strategies are required. For samples that are relatively clear after extraction, solid-phase extraction (SPE) columns with polymer matrices can be used for purification; however, for samples with turbid extracts and high particulate matter content, physical purification methods such as ultrafiltration may be necessary. While modern LC / MS / MS technology allows for direct analysis, sample preparation still requires meticulous optimization to ensure sensitivity and overcome matrix effects. In addition to the interferences encountered by the aforementioned laboratory detection methods, the application of rapid on-site detection technologies (such as immunochromatographic test strips) also needs to consider matrix interference. Although monoclonal antibody-based test strips can achieve rapid screening in baby corn, with a visual detection limit of 0.2 mg / kg, they can still be affected by non-specific adsorption or cross-reactivity of certain components in the baby corn matrix. In summary, the interfering factors for glyphosate detection in baby corn are multidimensional and complex, permeating the entire process from sample preparation to instrumental analysis. To ensure data reliability, it is essential to systematically optimize and combine appropriate extraction solvents, purification techniques, and fluorescent probes based on the characteristics of the baby corn matrix. In the future, developing more selective purification materials, more stable isotope internal standards, and rapid detection antibodies with stronger anti-interference capabilities will be important directions for further improving the accuracy and efficiency of glyphosate residue detection in complex agricultural products such as baby corn. Summary of the Invention

[0004] The purpose of this invention is to provide a method for detecting glyphosate in baby corn.

[0005] A method for detecting glyphosate in baby corn, comprising the following steps:

[0006] (1) Take fresh baby corn, cut off the inedible parts, chop the edible parts and homogenize them; add 3-5 times the weight of weak acidic aqueous solution, vortex and mix well, and then extract by ultrasonication for 15-20 min; then centrifuge at 2-8℃ and 10000-15000 rpm for 5-15 min and take the supernatant.

[0007] (2) The supernatant obtained in step (1) is purified using a mixed anion exchange column to obtain the eluent;

[0008] (3) The eluent obtained in step (2) is dried gently with nitrogen at 35-45℃, then dissolved in methanol by ultrasonication, and filtered through a 0.3-0.6μm microporous membrane to prepare the test solution;

[0009] (4) Prepare stock solutions of the composite fluorescent probes with a concentration of 5 μmol / L. Take 3 mL of the fluorescent probe stock solution into a cuvette each time, and add the following solutions in the range of 0-60 μmol·L⁻¹. -1 The glyphosate standard solution was placed at room temperature for 5 min, and the fluorescence emission spectrum of the probe was measured under 340 nm excitation light. The intensity value of the fluorescence emission peak at 530 nm was recorded to obtain the linear relationship between fluorescence intensity and glyphosate concentration.

[0010] (5) Add the test solution prepared in step (3) to the composite fluorescent probe stock solution. Under the action of 340 nm excitation light, measure the fluorescence emission peak intensity value of the fluorescent probe at 530 nm and substitute it into the linear relationship in step (4) to calculate the concentration of the glyphosate solution to be tested.

[0011] The inedible parts mentioned in step (1) include the outermost husk, corn silk and the basal connecting stem.

[0012] The weakly acidic aqueous solution in step (1) is an aqueous solution containing 0.5-2 wt% citric acid and 0.1-0.5 wt% fumaric acid.

[0013] The conditions for ultrasonic extraction in step (1) are: temperature 20-40℃, ultrasonic power 100-300W, frequency 40kHz-80kHz, and time 20-40min.

[0014] The purification steps using the mixed-type anion exchange column described in step (2) are as follows: 5-15 mL of supernatant is loaded onto the activated mixed-type anion exchange column and washed sequentially with 2-4 mL of water, 2-4 mL of methanol, and 2-4 mL of ammonia-methanol solution. The column is passed through at a stable flow rate of 2 mL / min. The effluent is discarded. The column is then washed sequentially with 2-4 mL of water and 2-4 mL of elution solution at a flow rate of 2 mL / min. The effluent is discarded. The solid-phase extraction column is dried. The column is then eluted with 2-4 mL of elution solution, and the eluent is collected.

[0015] The composite fluorescent probe is composed of equimolar combinations of the compounds shown in Formula I and Formula II:

[0016]

[0017] Formula I; Formula II.

[0018] The linear relationship is y = 782.6x + 4786.3 (R 2 =0.996).

[0019] The beneficial effects of this invention are as follows: The method for detecting glyphosate in corn shoots of this invention uses a weakly acidic aqueous solution to extract glyphosate from the sample and employs a composite fluorescent probe for determination, resulting in minimal interference with the detection results and high recovery rate. The combined use of citric acid and fumaric acid in the extract, along with the combined use of compounds represented by Formula I and Formula II, provides a synergistic effect. Detailed Implementation

[0020] To facilitate understanding of the present invention, a more comprehensive description will be given below. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the present invention.

[0021] Example 1

[0022] A method for detecting glyphosate in baby corn, comprising the following steps:

[0023] (1) Take fresh baby corn, cut off the inedible parts (outermost husks, corn silk and base connecting stem), chop the edible parts and homogenize them; add 4 times the weight of weak acidic aqueous solution, vortex and mix well, and then extract by ultrasound for 18 min; then centrifuge at 4℃ and 12000rpm for 10 min, and take the supernatant; the weak acidic aqueous solution is an aqueous solution containing 1wt% citric acid and 0.3wt% fumaric acid; the conditions for ultrasonic extraction are: at a temperature of 30℃, ultrasonic power of 200W, frequency of 60kHz, and time of 30 min;

[0024] (2) The supernatant obtained in step (1) is purified using a mixed-type anion exchange column to obtain the eluent; the purification step using the mixed-type anion exchange column is as follows: 10 mL of supernatant is loaded onto the activated mixed-type anion exchange column and washed sequentially with 3 mL of water, 3 mL of methanol, and 3 mL of ammonia-methanol solution. The column is passed through at a stable flow rate of 2 mL / min. The effluent is discarded. The column is then washed sequentially with 3 mL of water and 3 mL of washing solution at a flow rate of 2 mL / min. The effluent is discarded. The solid-phase extraction column is dried. The column is eluted with 3 mL of elution solution and the eluent is collected.

[0025] (3) The eluent obtained in step (2) was dried slowly with nitrogen at 40°C, then dissolved in methanol by ultrasonication, and filtered through a 0.45 μm microporous membrane to prepare the test solution;

[0026] (4) Prepare stock solutions of the composite fluorescent probes with a concentration of 5 μmol / L. Take 3 mL of the fluorescent probe stock solution into a cuvette each time, and add the following solutions in the range of 0-60 μmol·L⁻¹. -1 A glyphosate standard solution was incubated at room temperature for 5 min. Under 340 nm excitation light, the fluorescence emission spectrum of the probe was measured, and the intensity of the fluorescence emission peak at 530 nm was recorded to obtain a linear relationship between fluorescence intensity and glyphosate concentration. The composite fluorescent probe is composed of equimolar combinations of the compounds shown in Formula I and Formula II.

[0027]

[0028] Formula I; Formula II;

[0029] The linear relationship is y = 782.6x + 4786.3 (R 2 =0.996);

[0030] (5) Add the test solution prepared in step (3) to the composite fluorescent probe stock solution. Under the action of 340 nm excitation light, measure the fluorescence emission peak intensity value of the fluorescent probe at 530 nm and substitute it into the linear relationship in step (4) to calculate the concentration of the glyphosate solution to be tested.

[0031] Example 2

[0032] A method for detecting glyphosate in baby corn, comprising the following steps:

[0033] (1) Take fresh baby corn, cut off the inedible parts (outermost husks, corn silk and base connecting stem), chop the edible parts and homogenize them; add 3 times the weight of weak acidic aqueous solution, vortex and mix well, and then extract by ultrasound for 15 min; then centrifuge at 4℃ and 12000rpm for 8 min, and take the supernatant; the weak acidic aqueous solution is an aqueous solution containing 1.5wt% citric acid and 0.45wt% fumaric acid; the conditions for ultrasonic extraction are: at a temperature of 25℃, ultrasonic power of 180W, frequency of 50kHz, and time of 25 min;

[0034] (2) The supernatant obtained in step (1) is purified using a mixed-type anion exchange column to obtain the eluent; the purification step using the mixed-type anion exchange column is as follows: 10 mL of supernatant is loaded onto the activated mixed-type anion exchange column and washed sequentially with 3 mL of water, 3 mL of methanol, and 3 mL of ammonia-methanol solution. The column is passed through at a stable flow rate of 2 mL / min. The effluent is discarded. The column is then washed sequentially with 3 mL of water and 3 mL of washing solution at a flow rate of 2 mL / min. The effluent is discarded. The solid-phase extraction column is dried. The column is eluted with 3 mL of elution solution and the eluent is collected.

[0035] (3) The eluent obtained in step (2) was dried slowly with nitrogen at 38°C, then dissolved in methanol by ultrasonication, and filtered through a 0.35 μm microporous membrane to prepare the test solution;

[0036] (4) Prepare stock solutions of the composite fluorescent probes with a concentration of 5 μmol / L. Take 3 mL of the fluorescent probe stock solution into a cuvette each time, and add the following solutions in the range of 0-60 μmol·L⁻¹. -1 A glyphosate standard solution was incubated at room temperature for 5 min. Under 340 nm excitation light, the fluorescence emission spectrum of the probe was measured, and the intensity of the fluorescence emission peak at 530 nm was recorded to obtain a linear relationship between fluorescence intensity and glyphosate concentration. The composite fluorescent probe is composed of equimolar combinations of the compounds shown in Formula I and Formula II.

[0037]

[0038] Formula I; Formula II;

[0039] The linear relationship is y = 782.6x + 4786.3 (R 2 =0.996);

[0040] (5) Add the test solution prepared in step (3) to the composite fluorescent probe stock solution. Under the action of 340 nm excitation light, measure the fluorescence emission peak intensity value of the fluorescent probe at 530 nm and substitute it into the linear relationship in step (4) to calculate the concentration of the glyphosate solution to be tested.

[0041] Example 3

[0042] A method for detecting glyphosate in baby corn, comprising the following steps:

[0043] (1) Take fresh baby corn, cut off the inedible parts, chop the edible parts and homogenize them; add 5 times the weight of weak acidic aqueous solution, vortex and mix well, and then extract by ultrasound for 20 min; then centrifuge at 4℃ and 12000rpm for 10 min and take the supernatant; the inedible parts include the outermost husk, corn silk and the base connecting stalk; the weak acidic aqueous solution is an aqueous solution containing 0.8wt% citric acid and 0.25wt% fumaric acid; the conditions for ultrasound extraction are: at a temperature of 40℃, ultrasound power of 280W, frequency of 70kHz and time of 22 min;

[0044] (2) The supernatant obtained in step (1) is purified using a mixed-type anion exchange column to obtain the eluent; the purification step using the mixed-type anion exchange column is as follows: 10 mL of supernatant is loaded onto the activated mixed-type anion exchange column and washed sequentially with 3 mL of water, 3 mL of methanol, and 3 mL of ammonia-methanol solution. The column is passed through at a stable flow rate of 2 mL / min. The effluent is discarded. The column is then washed sequentially with 3 mL of water and 3 mL of washing solution at a flow rate of 2 mL / min. The effluent is discarded. The solid-phase extraction column is dried. The column is eluted with 3 mL of elution solution and the eluent is collected.

[0045] (3) The eluent obtained in step (2) was dried slowly with nitrogen at 40°C, then dissolved in methanol by ultrasonication, and filtered through a 0.45 μm microporous membrane to prepare the test solution;

[0046] (4) Prepare stock solutions of the composite fluorescent probes with a concentration of 5 μmol / L. Take 3 mL of the fluorescent probe stock solution into a cuvette each time, and add the following solutions in the range of 0-60 μmol·L⁻¹. -1 A glyphosate standard solution was incubated at room temperature for 5 min. Under 340 nm excitation light, the fluorescence emission spectrum of the probe was measured, and the intensity of the fluorescence emission peak at 530 nm was recorded to obtain a linear relationship between fluorescence intensity and glyphosate concentration. The composite fluorescent probe is composed of equimolar combinations of the compounds shown in Formula I and Formula II.

[0047]

[0048] Formula I; Formula II;

[0049] The linear relationship is y = 782.6x + 4786.3 (R 2 =0.996);

[0050] (5) Add the test solution prepared in step (3) to the composite fluorescent probe stock solution. Under the action of 340 nm excitation light, measure the fluorescence emission peak intensity value of the fluorescent probe at 530 nm and substitute it into the linear relationship in step (4) to calculate the concentration of the glyphosate solution to be tested.

[0051] Comparative Example 1

[0052] A method for detecting glyphosate in baby corn, comprising the following steps:

[0053] (1) Take fresh baby corn, cut off the inedible parts (outermost husks, corn silk and base connecting stem), chop the edible parts and homogenize them; add 4 times the weight of 1.3wt% citric acid aqueous solution, vortex and mix well, and then extract by ultrasound for 18 min; then centrifuge at 4℃ and 12000rpm for 10 min, and take the supernatant; the conditions for ultrasound extraction are: at a temperature of 30℃, ultrasound power of 200W, frequency of 60kHz, and time of 30 min.

[0054] (2) The supernatant obtained in step (1) is purified using a mixed-type anion exchange column to obtain the eluent; the purification step using the mixed-type anion exchange column is as follows: 10 mL of supernatant is loaded onto the activated mixed-type anion exchange column and washed sequentially with 3 mL of water, 3 mL of methanol, and 3 mL of ammonia-methanol solution. The column is passed through at a stable flow rate of 2 mL / min. The effluent is discarded. The column is then washed sequentially with 3 mL of water and 3 mL of washing solution at a flow rate of 2 mL / min. The effluent is discarded. The solid-phase extraction column is dried. The column is eluted with 3 mL of elution solution and the eluent is collected.

[0055] (3) The eluent obtained in step (2) was dried slowly with nitrogen at 40°C, then dissolved in methanol by ultrasonication, and filtered through a 0.45 μm microporous membrane to prepare the test solution;

[0056] (4) Prepare stock solutions of the composite fluorescent probes with a concentration of 5 μmol / L. Take 3 mL of the fluorescent probe stock solution into a cuvette each time, and add the following solutions in the range of 0-60 μmol·L⁻¹. -1 A glyphosate standard solution was incubated at room temperature for 5 min. Under 340 nm excitation light, the fluorescence emission spectrum of the probe was measured, and the intensity of the fluorescence emission peak at 530 nm was recorded to obtain a linear relationship between fluorescence intensity and glyphosate concentration. The composite fluorescent probe is composed of equimolar combinations of the compounds shown in Formula I and Formula II.

[0057]

[0058] Formula I; Formula II;

[0059] The linear relationship is y = 782.6x + 4786.3 (R 2 =0.996);

[0060] (5) Add the test solution prepared in step (3) to the composite fluorescent probe stock solution. Under the action of 340 nm excitation light, measure the fluorescence emission peak intensity value of the fluorescent probe at 530 nm and substitute it into the linear relationship in step (4) to calculate the concentration of the glyphosate solution to be tested.

[0061] Comparative Example 2

[0062] A method for detecting glyphosate in baby corn, comprising the following steps:

[0063] (1) Take fresh baby corn, cut off the inedible parts (outermost husks, corn silk and base connecting stem), chop the edible parts and homogenize them; add 4 times the weight of an aqueous solution containing 1.3wt% fumaric acid, vortex and mix well, and then extract by ultrasound for 18 min; then centrifuge at 4℃ and 12000rpm for 10 min, and take the supernatant; the conditions for ultrasound extraction are: at a temperature of 30℃, ultrasound power of 200W, frequency of 60kHz, and time of 30 min.

[0064] (2) The supernatant obtained in step (1) is purified using a mixed-type anion exchange column to obtain the eluent; the purification step using the mixed-type anion exchange column is as follows: 10 mL of supernatant is loaded onto the activated mixed-type anion exchange column and washed sequentially with 3 mL of water, 3 mL of methanol, and 3 mL of ammonia-methanol solution. The column is passed through at a stable flow rate of 2 mL / min. The effluent is discarded. The column is then washed sequentially with 3 mL of water and 3 mL of washing solution at a flow rate of 2 mL / min. The effluent is discarded. The solid-phase extraction column is dried. The column is eluted with 3 mL of elution solution and the eluent is collected.

[0065] (3) The eluent obtained in step (2) was dried slowly with nitrogen at 40°C, then dissolved in methanol by ultrasonication, and filtered through a 0.45 μm microporous membrane to prepare the test solution;

[0066] (4) Prepare stock solutions of the composite fluorescent probes with a concentration of 5 μmol / L. Take 3 mL of the fluorescent probe stock solution into a cuvette each time, and add the following solutions in the range of 0-60 μmol·L⁻¹. -1 A glyphosate standard solution was incubated at room temperature for 5 min. Under 340 nm excitation light, the fluorescence emission spectrum of the probe was measured, and the intensity of the fluorescence emission peak at 530 nm was recorded to obtain a linear relationship between fluorescence intensity and glyphosate concentration. The composite fluorescent probe is composed of equimolar combinations of the compounds shown in Formula I and Formula II.

[0067]

[0068] Formula I; Formula II;

[0069] The linear relationship is y = 782.6x + 4786.3 (R 2 =0.996);

[0070] (5) Add the test solution prepared in step (3) to the composite fluorescent probe stock solution. Under the action of 340 nm excitation light, measure the fluorescence emission peak intensity value of the fluorescent probe at 530 nm and substitute it into the linear relationship in step (4) to calculate the concentration of the glyphosate solution to be tested.

[0071] Comparative Example 3

[0072] A method for detecting glyphosate in baby corn, comprising the following steps:

[0073] (1) Take fresh baby corn, cut off the inedible parts (outermost husks, corn silk and base connecting stem), chop the edible parts and homogenize them; add 4 times the weight of weak acidic aqueous solution, vortex and mix well, and then extract by ultrasound for 18 min; then centrifuge at 4℃ and 12000rpm for 10 min, and take the supernatant; the weak acidic aqueous solution is an aqueous solution containing 1wt% citric acid and 0.3wt% fumaric acid; the conditions for ultrasonic extraction are: at a temperature of 30℃, ultrasonic power of 200W, frequency of 60kHz, and time of 30 min;

[0074] (2) The supernatant obtained in step (1) is purified using a mixed-type anion exchange column to obtain the eluent; the purification step using the mixed-type anion exchange column is as follows: 10 mL of supernatant is loaded onto the activated mixed-type anion exchange column and washed sequentially with 3 mL of water, 3 mL of methanol, and 3 mL of ammonia-methanol solution. The column is passed through at a stable flow rate of 2 mL / min. The effluent is discarded. The column is then washed sequentially with 3 mL of water and 3 mL of washing solution at a flow rate of 2 mL / min. The effluent is discarded. The solid-phase extraction column is dried. The column is eluted with 3 mL of elution solution and the eluent is collected.

[0075] (3) The eluent obtained in step (2) was dried slowly with nitrogen at 40°C, then dissolved in methanol by ultrasonication, and filtered through a 0.45 μm microporous membrane to prepare the test solution;

[0076] (4) Prepare a stock solution of fluorescent probe with a concentration of 10 μmol / L. Take 3 mL of fluorescent probe stock solution into a cuvette each time, and add the fluorescent probe stock solution with a concentration range of 0-60 μmol·L⁻¹ sequentially. -1 A glyphosate standard solution was incubated at room temperature for 5 min. Under 340 nm excitation light, the fluorescence emission spectrum of the probe was measured, and the intensity of the fluorescence emission peak at 530 nm was recorded to obtain a linear relationship between fluorescence intensity and glyphosate concentration. The fluorescent probe is shown in Formula I.

[0077]

[0078] Formula I;

[0079] The linear relationship is y = 756.4x + 4357.7 (R 2 =0.995);

[0080] (5) Add the test solution prepared in step (3) to the fluorescent probe stock solution. Under the action of 340 nm excitation light, measure the fluorescence emission peak intensity value of the fluorescent probe at 530 nm and substitute it into the linear relationship in step (4) to calculate the concentration of the glyphosate solution to be tested.

[0081] Comparative Example 4

[0082] A method for detecting glyphosate in baby corn, comprising the following steps:

[0083] (1) Take fresh baby corn, cut off the inedible parts (outermost husks, corn silk and base connecting stem), chop the edible parts and homogenize them; add 4 times the weight of weak acidic aqueous solution, vortex and mix well, and then extract by ultrasound for 18 min; then centrifuge at 4℃ and 12000rpm for 10 min, and take the supernatant; the weak acidic aqueous solution is an aqueous solution containing 1wt% citric acid and 0.3wt% fumaric acid; the conditions for ultrasonic extraction are: at a temperature of 30℃, ultrasonic power of 200W, frequency of 60kHz, and time of 30 min;

[0084] (2) The supernatant obtained in step (1) is purified using a mixed-type anion exchange column to obtain the eluent; the purification step using the mixed-type anion exchange column is as follows: 10 mL of supernatant is loaded onto the activated mixed-type anion exchange column and washed sequentially with 3 mL of water, 3 mL of methanol, and 3 mL of ammonia-methanol solution. The column is passed through at a stable flow rate of 2 mL / min. The effluent is discarded. The column is then washed sequentially with 3 mL of water and 3 mL of washing solution at a flow rate of 2 mL / min. The effluent is discarded. The solid-phase extraction column is dried. The column is eluted with 3 mL of elution solution and the eluent is collected.

[0085] (3) The eluent obtained in step (2) was dried slowly with nitrogen at 40°C, then dissolved in methanol by ultrasonication, and filtered through a 0.45 μm microporous membrane to prepare the test solution;

[0086] (4) Prepare stock solutions of fluorescent probes with a concentration of 10 μmol / L. Take 3 mL of fluorescent probe stock solution into a cuvette each time, and add the fluorescent probes in the range of 0-60 μmol / L. -1A glyphosate standard solution was incubated at room temperature for 5 min. Under 340 nm excitation light, the fluorescence emission spectrum of the probe was measured, and the intensity of the fluorescence emission peak at 530 nm was recorded to obtain the linear relationship between fluorescence intensity and glyphosate concentration. The fluorescent probe is shown in Formula II.

[0087]

[0088] Formula II;

[0089] The linear relationship is y = 821.4x + 4889.3 (R 2 =0.994);

[0090] (5) Add the test solution prepared in step (3) to the fluorescent probe stock solution. Under the action of 340 nm excitation light, measure the fluorescence emission peak intensity value of the fluorescent probe at 530 nm and substitute it into the linear relationship in step (4) to calculate the concentration of the glyphosate solution to be tested.

[0091] Experimental example:

[0092] Following the methods of Examples 1-3 and Comparative Examples 1-4, the standard addition method was used for actual sample detection. Glyphosate solutions of different concentrations (10 μmol / L, 30 μmol / L) were added to the fluorescent probe. Under 340 nm excitation light, the fluorescence emission peak intensity of the fluorescent probe at 530 nm was measured. This value was then substituted into the linear relationship in the respective examples and comparative examples to calculate the concentration of the glyphosate solution to be tested, and the recovery rate (%) was calculated. The experimental results were statistically analyzed using SPSS 24.0 software. Quantitative data were analyzed using... (mean ± standard deviation) represents the mean. The Kolmogorov-Smirnov test was used to test the normality of the data. For normally distributed data, a t-test was used to compare the differences in means between two groups, with P < 0.05 considered statistically significant. The results are shown in Table 1.

[0093] Table 1. Results of determination at an addition level of 10 μmol / L

[0094]

[0095] Note: * indicates that compared with Example 1 group, P<0.05.

[0096] Table 2 Results of determination at an addition amount of 30 μmol / L

[0097]

[0098] Note: * indicates that compared with Example 1 group, P<0.05.

[0099] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method for detecting glyphosate in baby corn, characterized in that, Follow these steps: (1) Take fresh baby corn, cut off the inedible parts, chop the edible parts and homogenize them; add 3-5 times the weight of weak acidic aqueous solution, vortex and mix well, and then extract by ultrasound for 15-20 minutes. Then centrifuge at 2-8℃ and 10000-15000rpm for 5-15 minutes and collect the supernatant; (2) The supernatant obtained in step (1) is purified using a mixed-type anion exchange column to obtain the eluent; (3) The eluent obtained in step (2) is dried gently with nitrogen at 35-45℃, then dissolved in methanol by ultrasonication, and filtered through a 0.3-0.6μm microporous membrane to prepare the test solution; (4) Prepare stock solutions of the composite fluorescent probes with a concentration of 5 μmol / L. Take 3 mL of the fluorescent probe stock solution into a cuvette each time, and add the following solutions in the range of 0-60 μmol / L. -1 The glyphosate standard solution was placed at room temperature for 5 min, and the fluorescence emission spectrum of the probe was measured under 340 nm excitation light. The intensity value of the fluorescence emission peak at 530 nm was recorded to obtain the linear relationship between fluorescence intensity and glyphosate concentration. (5) Add the test solution prepared in step (3) to the composite fluorescent probe stock solution. Under the action of 340 nm excitation light, measure the fluorescence emission peak intensity value of the fluorescent probe at 530 nm and substitute it into the linear relationship in step (4) to calculate the concentration of the glyphosate solution to be tested.

2. The method for detecting glyphosate in corn shoots according to claim 1, characterized in that, The inedible parts mentioned in step (1) include the outermost husk, corn silk, and the basal connecting stem.

3. The method for detecting glyphosate in baby corn according to claim 1, characterized in that, The weakly acidic aqueous solution in step (1) is an aqueous solution containing 0.5-2 wt% citric acid and 0.1-0.5 wt% fumaric acid.

4. The method for detecting glyphosate in corn shoots according to claim 1, characterized in that, The conditions for ultrasonic extraction in step (1) are: temperature 20-40℃, ultrasonic power 100-300W, frequency 40kHz-80kHz, and time 20-40min.

5. The method for detecting glyphosate in baby corn according to claim 1, characterized in that, The purification steps using the mixed-type anion exchange column described in step (2) are as follows: 5-15 mL of supernatant is loaded onto the activated mixed-type anion exchange column and washed sequentially with 2-4 mL of water, 2-4 mL of methanol, and 2-4 mL of ammonia-methanol solution. The column is passed through at a stable flow rate of 2 mL / min. The effluent is discarded. The column is then washed sequentially with 2-4 mL of water and 2-4 mL of elution solution at a flow rate of 2 mL / min. The effluent is discarded. The solid-phase extraction column is dried. The column is then eluted with 2-4 mL of elution solution, and the eluent is collected.

6. The method for detecting glyphosate in corn shoots according to claim 1, characterized in that, The composite fluorescent probe is composed of equimolar combinations of the compounds shown in Formula I and Formula II: Formula I; Formula II.

7. The method for detecting glyphosate in baby corn according to claim 1, characterized in that, The linear relationship is y = 782.6x + 4786.3 (R 2 =0.996).

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