CN114674952A - Method for detecting sulfonamide antibiotics based on electric field enhanced film solid phase microextraction - Google Patents

Abstract

The invention discloses a method for detecting sulfonamide antibiotics based on electric field enhanced film solid phase microextraction, and belongs to the technical field of analysis and detection. The invention develops a method for enriching and detecting SAs by EE-TFME combined with high performance liquid chromatography by taking MIL-101(Cr) as a TFME film growing on the CC surface in situ through hydrothermal reaction, and is successfully applied to the extraction and determination of SAs in animal-derived foods (milk, honey, pork and chicken). The LOD of the detection limit of SAs detected by the method is 2.5-4.5ng/mL, the LOQ of the quantification limit is 8.0-14.5ng/mL, and the upper limit of the linear range is 200.0 ng/mL; through a standard adding recovery rate experiment and detection of the content of the sulfonamide antibiotics, the standard adding recovery rate is 81.7-114.2%, the matching is good, and the accuracy is high; and the detection method has good adaptability.

Description

Method for detecting sulfonamide antibiotics based on electric field enhanced film solid phase microextraction

Technical Field

The invention relates to a method for detecting sulfonamide antibiotics based on electric field enhanced film solid phase microextraction, belonging to the technical field of analysis and detection.

Background

Sulfonamides (SAs) are synthetic antibiotics with a p-aminophenyl structure, and are widely used in the clinical, animal feed additive, and other industries to inhibit bacterial growth due to their low production cost and broad antimicrobial spectrum. Because of the widespread use of SAs, residual events detected in food products occur more frequently than other antibiotics such as tetracycline and oxazolidinones. More seriously, these residues may cause health hazards to humans, such as allergic reactions, carcinogenesis, teratogenicity, and mutagenicity. Therefore, many countries and regions have established Maximum Residual Limits (MRL) for SAs in foods of animal origin. The food code Committee (CAC), European Union (EU) and China all specify a total SAs MRL of 100. mu.g/kg. The Food and Drug Administration (FDA) specifies that the MRL of sulfadimidine in fat, liver and kidney is 100 mug/kg, and China specifies that the MRL of sulfadimidine in milk is 25 mug/kg. Therefore, there is a pressing need for a rapid, useful and efficient detection method for extracting and quantifying trace amounts of SAs in complex food matrices.

Methods for detecting SAs are numerous, including High Performance Liquid Chromatography (HPLC), electrochemical sensor analysis, and immunochromatographic strips. Wherein, the high performance liquid chromatography has higher reproducibility and high efficiency, and is a reliable method for detecting various SAs. High performance liquid chromatography requires several steps, but they are all efficient pretreatment procedures to extract the SAs from the food matrix. Several pretreatment methods for SAs in food samples have emerged in recent years, including Solid Phase Microextraction (SPME), magnetically dispersed solid phase extraction (MSPE), and liquid-liquid extraction (LLE). In addition, the Thin Film Microextraction (TFME) technology is also receiving increasing attention.

Compared with SPME, TFME has a relatively large extraction phase area, higher sensitivity and faster extraction speed. Compared to MSPE and LLE, TFME can extract the adsorbent directly from the extraction phase and consume less organic solvent. Therefore, it has been successfully applied to the pretreatment of foods and biological samples. The key to the extraction efficiency of the TFME is the coating material, and good extraction effect can be obtained by good materials, such as Metal Organic Frameworks (MOFs). MOFs are a class of hybrid materials with crystalline structure, highly tunable porosity and different functions, and are considered as a promising material for food sample preparation.

Traditional TFMEs rely heavily on passive diffusion of the analyte between the sample matrix and the coating to achieve an extraction equilibrium, which can lead to a time-consuming process of polar or ionic compounds (such as protonated amines). To address this challenge, electric field assisted techniques are increasingly being employed because they can lead to migration of charged targets. Thus, the electric field is potentially useful for enhancing the TFME of SAs with high conductivity thin films. Carbon Cloth (CC) is known as a commercial self-supporting substrate by the conductivity, macroporosity, strong stability (high temperature resistance and strong acid resistance) and excellent flexibility, and paves the way for the extensive application of the CC modified by MOFs in the fields of electrochemical detection, electrocatalysis, supercapacitors and the like.

SAs with two amino groups are used as examples of ionic analytes in the present invention, considering their ease of deprotonation at certain pH and potential. The invention explores a new method for applying MIL-101(Cr) modified CC to electric field enhanced TFME (EE-TFME). MIL-101(Cr) grows in situ on CC surface by hydrothermal reaction to improve conductivity and further serves as working electrode for enhanced extraction of sulfadiazine, sulfathiazole, sulfamethoxazole, sulfadimidine, sulfamethoxazole and sulfisoxazole. SAs have similar physical properties and chemical structures, with several modifiable sites and conjugation systems, and six SAs that are often used in practical production, we target six SAs as a typical target. EE-TFME is combined with HPLC to be successfully applied to the extraction and determination of SAs in animal-derived foods (milk, honey, pork and chicken). The invention aims to explore a TFME method for rapidly extracting SAs.

Disclosure of Invention

In order to solve the problems, the invention provides an extraction method for applying an electric field to TFME, SAs are enriched and concentrated on the basis of an MIL-101(Cr) modified CC electrode, and an animal sample treated by MIL-101(Cr)/CC in combination with EE-TFME is used for detection, so that the extraction method is high in speed and accuracy and has practical application prospects.

In the invention, MIL-101(Cr) grows in situ on the surface of CC through hydrothermal reaction to serve as a TFME film, the performance of the film on EE-TFME is further researched, and the EE-TFME is developed to be combined with high performance liquid chromatography and successfully applied to the extraction and determination of SAs in animal-derived food (milk, honey, pork and chicken).

The invention aims to provide a method for enriching and extracting sulfonamide antibiotics, which comprises the following steps:

an MIL-101(Cr) modified carbon cloth MIL-101(Cr)/CC is used as an adsorption extraction agent, and forms an electric field enhanced thin film solid phase micro-extraction device together with a direct current stabilized voltage power supply, a sample cell and a platinum wire electrode; immersing an MIL-101(Cr)/CC and a platinum wire electrode into a sample solution to establish a complete circuit system, firstly applying positive voltage on the MIL-101(Cr)/CC to carry out adsorption, placing the electrode into an eluent after the adsorption is finished, then reversing a positive electrode and a negative electrode, applying negative voltage on the MIL-101(Cr)/CC to carry out elution and desorption, carrying out solid-liquid separation, collecting clear liquid, concentrating and drying to obtain the sulfonamide antibiotics.

In one embodiment of the present invention, the MIL-101(Cr)/CC is prepared by a process comprising:

(1) pretreating Carbon Cloth (CC);

(2) dispersing soluble chromium salt, terephthalic acid and hydrofluoric acid in water to prepare a mixed solution; and adding the treated carbon cloth into the mixed solution, carrying out hydrothermal reaction, collecting the carbon cloth after the reaction is finished, and washing to obtain the MIL-101(Cr)/CC modified carbon cloth by the MIL-101 (Cr).

In one embodiment of the present invention, the process of pretreating the carbon cloth comprises:

washing the carbon cloth with acetone, absolute ethyl alcohol and deionized water respectively, and drying; and then soaking the CC in concentrated nitric acid, cleaning the carbon cloth by using deionized water until no acid exists, and drying.

In one embodiment of the invention, the soluble chromium salt may be selected from chromium nitrate.

In one embodiment of the invention, the soluble chromium salt has a terephthalic acid mass-to-mass ratio of (4-5): 1.

in one embodiment of the present invention, the concentration of the soluble chromium salt in the mixed solution is 80 to 90 mg/mL.

In one embodiment of the present invention, the volume ratio of hydrofluoric acid to water in the mixed solution is 1: (90-100).

In one embodiment of the present invention, the washing in step (2) is performed using an organic solvent such as N, N-dimethylformamide or absolute ethanol.

In one embodiment of the invention, the hydrothermal reaction in step (2) is carried out at 220 ℃ for 8 h.

In one embodiment of the present invention, the positive and negative voltages are each independently selected from 0.1-1.0V. Preferably 0.4-0.6V; further preferably 0.5V.

In one embodiment of the invention, the adsorption time is 5-35 min; preferably 15min-30 min.

In one embodiment of the invention, the medium of the sample solution is a pH4.0 PBS solution.

In one embodiment of the invention, the eluent is one or more of 5% ammonia methanol solution, acetonitrile, ethanol, isopropanol.

In one embodiment of the invention, the elution time is 15min to 30 min.

The invention also provides a method for quantitatively detecting sulfonamide antibiotics by using the high-performance liquid phase, which comprises the following steps of:

(1) preparing a high-performance liquid-phase sample solution: the MIL-101(Cr)/CC is used as an adsorption extracting agent, and forms an electric field enhanced film solid phase micro-extraction device together with a direct current stabilized voltage power supply, a sample cell and a platinum wire electrode; immersing an MIL-101(Cr)/CC and a platinum wire electrode into a sample solution to establish a complete circuit system, firstly applying positive voltage on the MIL-101(Cr)/CC to carry out adsorption, placing the MIL-101(Cr)/CC into eluent after adsorption is finished, then reversing a positive electrode and a negative electrode, applying negative voltage on the MIL-101(Cr)/CC to carry out elution and desorption, removing the eluent after elution, and fixing the volume by using acetonitrile to obtain a high-efficiency liquid phase sample solution;

(2) high performance liquid detection: obtaining a series of liquid chromatogram sample solutions of standard samples with known concentrations according to the step (1), and collecting corresponding high performance liquid chromatograms to obtain peak area values of corresponding target substances; and (4) carrying out linear correlation on the peak area value and the concentration of the target object to obtain a quantitative detection model.

In one embodiment of the present invention, when the high performance liquid chromatography is used for detection by a serial photodiode array detector, the pre-processing further comprises the following steps:

(1) drying nitrogen and fixing volume: placing the separated sample solution to be tested in a nitrogen blow-drying instrument to blow to near dryness, fixing the volume of acetonitrile, and testing the filtering membrane;

(2) preparation of standard sample: diluting samples to be tested with different concentrations by a solvent, treating the samples by an electric field enhanced film solid phase extraction method, eluting, drying and fixing the volume to be used as standard samples for later use.

In one embodiment of the invention, the high performance liquid chromatography column is E clipse Plus C ₁₈5 μm 4.6X 250mm column.

In one embodiment of the present invention, the specific conditions of the high performance liquid phase are:

the invention has the beneficial effects that:

the MIL-101(Cr)/CC electric field enhanced film solid phase microextraction extractant has better adsorption and extraction capacity on sulfonamide antibiotics. Based on the auxiliary action of the electric field and the difference of the interaction strength of various structures in the extracting agent, the adsorption quantity and the extraction recovery quantity of the sulfonamide antibiotics are improved. The detection was carried out using the MIL-101(Cr)/CC treated sample of the invention: the LOD of the detection limit is 2.5-4.5ng/mL, the LOQ of the quantification limit is 8.0-14.5ng/mL, and the upper limit of the linear range is 200 ng/mL; through a standard adding recovery rate experiment and detection of the content of the sulfonamide antibiotics, the standard adding recovery rate is 81.7-114.2%, the matching is good, and the accuracy is high; the detection method has good adaptability, has very accurate detection results for the detection of various samples, and has wide practical application prospect.

Drawings

FIG. 1 is a cold field emission electron micrograph of MIL-101 (Cr)/CC.

FIG. 2 is a plot of cyclic voltammetry for CC and MIL-101 (Cr)/CC.

FIG. 3 is a graph of impedance comparison of CC and MIL-101 (Cr)/CC.

FIG. 4 is a graph comparing CC, MIL-101(Cr)/CC and MIL-101(Cr)/CC with EE-TFME extracted SAs.

FIG. 5 is a graph comparing the recovery of SAs after different voltages were applied.

FIG. 6 is a graph of the recovery of SAs versus time for different extractions.

FIG. 7 is a graph comparing the recovery of SAs after elution with different eluents.

FIG. 8 is a 2.5 μ g/mL SDM/ST/SMZ/SMD/SMX/SIZ mixed standard HPLC chromatogram.

FIG. 9 is a schematic diagram of a process for detecting sulfonamide antibiotics based on electric field enhanced solid phase microextraction; a is a schematic flow chart of preparing MIL-101 (Cr)/CC; b is a flow diagram for extracting and detecting sulfonamide antibiotics.

Detailed Description

The carbon cloth (carbon fiber cloth, CC) according to the present invention was purchased from taiwan carbon energy company of china.

The high performance liquid chromatography column related to the invention is E clipse Plus C ₁₈5 μm 4.6 × 250mm chromatographic column, and the specific detection conditions are as follows:

the invention relates to

m: mass of sulfonamides obtained after EE-TFME, M: EE-TFME quality of the sulfonamide added previously. Wherein the mass is measured by an external standard method high performance liquid phase: the high performance liquid chromatography detection is carried out on methanol solutions of six SAs with the concentration of 0.1, 0.2, 0.5, 0.8, 1, 2.5 and 5 mu g/mL respectively, and the corresponding standard curves are shown as follows.

Name of substance	Linear equation of state	R2
			SDM	y＝29892.06x-97.45	0.9999
ST	y＝24621.16x-183.02	0.9997
			SMZ	y＝28479.30x-171.92	0.9999
SMD	y＝25298.58x+162.28	0.9999
			SMX	y＝27973.88x-53.65	0.9999
SIZ	y＝26895.27x-94.28	0.9999

Example 1: preparation of MIL-101(Cr) modified carbon cloth (MIL-101(Cr)/CC)

Washing the carbon cloth with acetone, anhydrous ethanol and deionized water for 3 times, each time for 15min, and drying at 60 deg.C for 12 h; next, CC was soaked in concentrated nitric acid for 24h, then the carbon fiber cloth was washed with a large amount of deionized water until acid-free and dried at 60 ℃ for 12 h.

First, 800mg of chromium nitrate, 332mg of terephthalic acid, and 0.1mL of hydrofluoric acid were uniformly dissolved in 9.6mL of deionized water at room temperature with the assistance of ultrasound to form a mixed solution. Then, the mixture was mixed with CC (1X 2 cm)²) Placing the mixture into a stainless steel autoclave lined with polytetrafluoroethylene, preserving heat at 220 ℃ for reaction for 8h, naturally cooling to room temperature, collecting solids, and thoroughly cleaning the obtained solids with DMF and ethanol to obtain the product MIL-101 (Cr)/CC. The cold field emission electron micrograph of the resulting product is shown in FIG. 1.

Example 2: method for enriching SAs by using MIL-101(Cr)/CC electric field to enhance solid phase microextraction

At K₃[Fe(CN)₆]When the cyclic voltammetry current and impedance of MIL-101(Cr)/CC and CC were measured in solution, as shown in FIG. 2, the oxidation-reduction potentials of MIL-101(Cr)/CC and CC were not much different, but the response current of MIL-101(Cr)/CC was much larger, and the corresponding oxidation peak current and reduction peak current were 2.63mA and-3.23 mA respectively, which were increased by 6 times and 3 times respectively compared with 0.41mA and-0.99 mA on CC. R of bare CC as shown in FIG. 3_ct452.6 Ω; when MIL-101(Cr) is loaded on CC, R_ctThe drop to 23.28 Ω demonstrates that MIL-101(Cr) facilitates charge transfer between the electrode and the solution.

In addition, when no external electric field is applied, CC and MIL-101(Cr) are respectively used for extracting SAs, as shown in FIG. 4, compared with the recovery rate, the extraction effect of the CC modified by the MIL-101(Cr) is obviously better than that of the naked CC, and further, the external electric field is applied to the MIL-101(Cr)/CC at the same time, compared with the extraction effect of the SAs applied by the external electric field, the recovery rate of the SAs after the electric field is applied is improved.

The extraction and enrichment processes are as follows:

the electric field enhanced film solid phase micro-extraction device consists of a direct current stabilized voltage power supply, a sample cell, a platinum wire electrode and an MIL-101(Cr)/CC, wherein the MIL-101(Cr)/CC and the platinum wire electrode are immersed into a standard solution or a sample solution to establish a complete circuit system.

Applying a positive electrode voltage of 0.5V to MIL-101(Cr)/CC, adsorbing 25mL of 0.01 mu g/mL of a sulfonamide standard substance mixed solution (pH4.0 PBS solution), reversing the positive electrode and the negative electrode after 15min, keeping the voltage of 0.5V unchanged, eluting for 15min by using 10mL of 5% ammonia methanol solution, blowing nitrogen to be nearly dry, fixing in 1mL of acetonitrile, detecting an extracted sample after constant volume by using HPLC, and taking a peak area as a detection signal to obtain a recovery rate result. As shown in table 1.

TABLE 1 results of recovery of SAs enriched by MIL-101(Cr)/CC electric field enhanced solid phase microextraction

SDM	ST	SMZ	SMD	SMX	SIZ
						98.1％	95.9％	96.5％	94.0％	90.6％	95.0％

Example 3: extraction/separation condition optimization

(1) Selection of applied external voltage:

with reference to the method in example 2, the voltage was varied, otherwise unchanged:

applying positive electrode voltage (0.1-1.0V) to MIL-101(Cr)/CC, adsorbing 25mL of 0.01 mu g/mL of sulfonamide standard substance mixed solution, reversing the positive electrode and the negative electrode after 15min, setting the voltage at 0.5V, eluting with 10mL of 5% ammonia methanol solution for 15min, blowing nitrogen to be nearly dry, fixing the volume in 1mL of acetonitrile, detecting an extracted sample after fixing the volume by using HPLC, and taking the peak area as a detection signal.

As shown in table 2 and fig. 5, the extraction efficiency of the target increased with increasing applied potential from 0.1 to 0.5V, which indicates that in a certain range with increasing voltage, an electric double layer is formed at the electrode/solution interface, and the charge is forced to move towards the electrode with the opposite charge, resulting in the electro-adsorption of ions. However, when the applied voltage exceeds 0.5V, the extraction efficiency gradually decreases. On one hand, under higher voltage, SAs is directly oxidized on the surface of an MIL-101(Cr)/CC electrode, and OH generated on the surface of the electrode indirectly oxidizes sulfanilamide substances to generate sulfanilic acid, p-aminophenol or aniline and other substances, so that the extraction efficiency is reduced; on the other hand, as the voltage increases, a compressive double-layer effect may occur, which may result in a thinner adsorption layer and a lower adsorption effect. Therefore, an applied potential of 0.5V was selected as an optimum value.

TABLE 2 recovery results at different voltages

(2) With reference to the method of example 2, the desorption was carried out directly with the eluent without reversal of the positive and negative electrodes after only 15min of the adsorption extraction:

after adsorption and extraction for 15min, the positive and negative electrodes are not reversed, different eluents are directly used for desorption, the result is measured and compared with the result obtained by reversing the positive and negative electrodes (as shown in table 3), the elution effect of six sulfonamides in a pure organic solvent is almost not influenced, but in an aqueous solution, the elution effect obtained by not reversing the positive and negative electrodes is obviously weaker than the elution effect obtained by reversing the positive and negative electrodes, which shows that the implementation of the reversal of the positive and negative electrodes is beneficial to enhancing the elution effect of the sulfonamides in the process.

TABLE 3 results of recovery rate of each eluent without reversal of positive and negative electrodes

(3) Selection of extraction time:

with reference to the procedure of example 2, the extraction time was varied, otherwise:

applying positive electrode voltage of 0.5V to MIL-101(Cr)/CC, adsorbing 25mL of 0.01 mu g/mL of sulfonamide standard substance mixed solution for 5-35min, reversing the positive electrode and the negative electrode after extraction, setting the voltage at 0.5V, eluting for 15min by using 10mL of 5% ammonia methanol solution, blowing nitrogen to be nearly dry, fixing the volume in 1mL of acetonitrile, detecting the extracted sample after constant volume by using HPLC, and taking the peak area as a detection signal. As shown in Table 4 and FIG. 6, the analyte equilibrium was almost 15min at 0.5V applied voltage, and the recovery rate varied from 4% to 7%, wherein the recovery rates of sulfathiazole, sulfamethazine and sulfisoxazole showed a slight decrease of about 4%, which is probably due to electrochemical oxidation of three substances to generate other substances but the recovery rates of six substances were almost constant as a whole. Therefore, the optimum adsorption time was 15 min.

TABLE 4 recovery results for different extraction times

Time of extraction

SDM

ST

SMZ

SMD

SMX

SIZ

5

30.4％

27.6％

29.8％

32.6％

31.6％

29.6％

10

67.8％

42.3％

49.6％

51.7％

58.3％

49.9％

15

98.1％

95.9％

96.5％

94.0％

90.6％

95.0％

20

89.5％

77.8％

76.7％

91.8％

83.7％

80.0％

25

86.4％

84.1％

83.7％

89.4％

90.2％

74.9％

30

88.9％

73.4％

90.8％

89.9％

86.2％

82.2％

35

90.1％

77.3％

84.6％

96.0％

83.8％

82.6％

(4) Selection of eluent

Applying a positive electrode voltage of 0.5V to MIL-101(Cr)/CC, adsorbing 25mL of 0.01 mu g/mL of a sulfonamide standard substance mixed solution (pH4.0), reversing the positive electrode and the negative electrode after 15min, setting the voltage at 0.5V, eluting with 10mL of acetonitrile, ethanol, acetone, dichloromethane, methanol, 5% ammonia methanol solution, PBS solution (pH9.0) and isopropanol for 15min, blowing nitrogen to be nearly dry, allowing the nitrogen to be contained in 1mL of acetonitrile, and detecting an extracted sample after constant volume by using HPLC (high performance liquid chromatography), wherein the peak area is used as a detection signal. As can be seen from table 5 and fig. 7, the extraction capacity of MIL-101(Cr)/CC for the target substance was the lowest under alkaline conditions, so it can be assumed that appropriate alkaline conditions promote desorption of the analyte from the MOF and increase its solubility in the organic solvent. In addition, the open metal sites of MIL-101(Cr)/CC exposed to the solvent environment have a greater affinity for polar solvents. Acetone is less polar in the selected organic solvent and therefore has relatively the lowest desorption efficiencies of 33.7%, 13.3%, 32.6%, 27.3%, 4.4% and 59.5%, respectively. In addition, the elution process in the experiment reverses the voltage of the two poles, and meanwhile, the selected water is a PBS (pH9.0) solution, so that after the voltage is reversed, like charges between the target object and the electrode repel each other, so that the elution effect in water is better, but the elution effect is still not as good as that of a 5% ammonia methanol solution. Finally 5% ammonia methanol was used as desorption solvent.

TABLE 5 results of recovery of different eluents

(5) Selecting an extraction adsorption mode:

the method comprises the following steps: MIL-101(Cr)/CC obtained in example 1 or CC alone (1X 2 cm)²) Directly adsorbing 25mL of 0.01 mu g/mL sulfonamide standard substance mixed solution, eluting for 15min by using 10mL of 5% ammonia methanol solution, blowing nitrogen to be nearly dry, fixing in 1mL of acetonitrile, detecting an extraction sample after constant volume by using HPLC, and taking a peak area as a detection signal.

The second method comprises the following steps:

applying positive voltage of 0.8V to MIL-101(Cr)/CC, adsorbing 25mL of 0.01 mu g/mL of sulfonamide standard substance mixed solution, reversing the positive electrode and the negative electrode after 15min, setting the voltage at 0.5V, eluting for 15min by using 10mL of 5% ammonia methanol solution, blowing nitrogen to be nearly dry, fixing the volume in 1mL of acetonitrile, detecting an extracted sample after constant volume by using HPLC, and taking a peak area as a detection signal.

The results of the extraction enrichment are shown in Table 6.

TABLE 6 recovery results for different extractive enrichment regimes

Example 4: extraction separation of sulfonamide antibiotics-construction of quantitative model:

(1) pretreatment of extraction and separation of a standard sample: a series of SAs with different concentrations, 2.0-250.0ng/mL, were processed by EE-TFME method to make a standard curve, and then extracted with the extractant prepared in example 1.

The electric field enhanced film solid phase micro-extraction device consists of a direct current stabilized voltage power supply, a sample cell, a platinum wire electrode and MIL-101 (Cr)/CC. The MIL-101(Cr)/CC and platinum wire electrode were immersed in the standard or sample solution to establish a complete circuit system, and a positive voltage of 0.5V was applied to the MIL-101(Cr)/CC to promote migration of negatively charged SAs formed by deprotonation in the electric field. Extracting for 15min in PBS (phosphate buffer solution) with the pH value of 4.0, taking out MIL-101(Cr)/CC from the vial, reversing the positive power supply and the negative power supply, keeping the voltage unchanged, continuously desorbing in 5% ammonia methanol solution for 15min, blowing the nitrogen for drying, diluting to 1mL with acetonitrile, using the acetonitrile for HPLC analysis, and using the obtained peak area as an analysis signal of the sulfonamide.

(2) Quantitative detection model:

the peak area is linearly related to the concentration of the corresponding standard sample, and the linearity, detection limit (LOD, S/N is 3), quantification limit (LOQ, S/N is 10), and analytical characteristics such as precision within and during the day of the method, which are established based on MIL-101(Cr)/CC, are analyzed to verify the effectiveness of the method, and the results are shown in Table 7. The linear range of the method is 10.0-200.0ng/mL, and the coefficient (R) is determined²) Between 0.9912 and 0.9967, an LOD of between 2.5 and 4.5ng/mL and an LOQ of between 8.0 and 14.5ng/mL, and the reproducibility of the method was also studied, the precision was expressed using the Relative Standard Deviation (RSD), and the RSD was less than 7.8% and 9.1% in the day and the day, respectively, indicating that the method had good reproducibility.

TABLE 7 quantitative test results

Wherein y represents a peak area and x represents a concentration of the target in the sample.

Example 5 method flexibility: detection of sulfonamides in different animal foods

Pork and chicken samples were homogenized and stored at-20 ℃. 8g of sample was mixed with 20mL of 6% acetonitrile acetate and 5g of Na₂SO₄Mix and vortex for 5min and centrifuge at 8500rpm for 10min at 4 ℃. 8g of honey sample was mixed with 16mL of Na in a centrifuge tube₂Mixing EDTA-Mclvaine buffer solution. An 8g sample of milk was mixed with 10mL acetonitrile in a centrifuge tube. The milk sample was vortexed for 1min and then centrifuged at 8500rpm for 10min at 4 ℃.

The method was used to determine SAs in six animal derived foods (honey, milk, pork and chicken) and each was spiked with 50 and 100 μ g/kg of SAs to evaluate its practical applicability. SDM was detected in milk and pork, whereas SMD was detected in pork at a concentration of 24.4. + -. 3.3. mu.g/kg (both below the European Union's MRL and national standards). The recovery rate of six SAs in the sample is between 81.7% and 114.2%, and RSDs is less than 8.6%. This also verifies the accuracy of the developed method. See table 8 for details.

TABLE 8 concentration of SAs in actual samples (. mu.g/kg), RSD (%, n-3), and normalized recovery (%)

Claims (10)

1. The method for enriching and extracting sulfonamide antibiotics is characterized by comprising the following steps of:

an MIL-101(Cr) modified carbon cloth MIL-101(Cr)/CC is used as an adsorption extraction agent, and forms an electric field enhanced thin film solid phase micro-extraction device together with a direct current stabilized voltage power supply, a sample cell and a platinum wire electrode; immersing an MIL-101(Cr)/CC and a platinum wire electrode into a sample solution to establish a complete circuit system, firstly applying positive voltage on the MIL-101(Cr)/CC to carry out adsorption, placing the electrode into an eluent after the adsorption is finished, then reversing a positive electrode and a negative electrode, applying negative voltage on the MIL-101(Cr)/CC to carry out elution and desorption, carrying out solid-liquid separation, collecting clear liquid, concentrating and drying to obtain the sulfonamide antibiotics.

2. The method of claim 1, wherein the MIL-101(Cr)/CC is prepared by a process comprising:

(1) pretreating Carbon Cloth (CC);

(2) dispersing soluble chromium salt, terephthalic acid and hydrofluoric acid in water to prepare a mixed solution; and adding the treated carbon cloth into the mixed solution, carrying out hydrothermal reaction, collecting the carbon cloth after the reaction is finished, and washing to obtain the MIL-101(Cr)/CC modified carbon cloth by the MIL-101 (Cr).

3. The process of claim 1, wherein the soluble chromium salt has a terephthalic acid mass-to-mass ratio of (4-5): 1.

4. the method of claim 1, wherein the concentration of the soluble chromium salt in the mixed liquor is 80-90 mg/mL.

5. The method of claim 1, wherein the volume ratio of hydrofluoric acid to water in the mixed solution is 1: (90-100).

6. The method of claim 1, wherein the hydrothermal reaction in step (2) is carried out at 220 ℃ for 8 hours.

7. The method of claim 1, wherein the positive and negative voltages are each independently selected from 0.1-1.0V. Preferably 0.4-0.6V.

8. The method of claim 1, wherein the medium of the sample solution is a pH4.0 PBS solution.

9. The method of claim 1, wherein the eluent is one or more of 5% ammonia methanol solution, acetonitrile, ethanol, isopropanol.

10. A method for high performance liquid quantitative detection of sulfonamide antibiotics is characterized by comprising the following steps:

(1) preparing a high-performance liquid-phase sample solution: the MIL-101(Cr)/CC as the adsorption extracting agent in claim 2, which forms an electric field enhanced thin film solid phase micro-extraction device together with a DC stabilized voltage power supply, a sample cell and a platinum wire electrode; immersing MIL-101(Cr)/CC and a platinum wire electrode into a sample solution to establish a complete circuit system, firstly applying positive voltage on the MIL-101(Cr)/CC to carry out adsorption, placing the MIL-101(Cr)/CC into eluent after adsorption is finished, then reversing the positive electrode and the negative electrode, applying negative voltage on the MIL-101(Cr)/CC to carry out elution desorption, removing the eluent after elution, and carrying out constant volume treatment by using acetonitrile to obtain a high-efficiency liquid phase sample solution;

(2) high performance liquid detection: obtaining a series of liquid chromatogram sample solutions of standard samples with known concentrations according to the step (1), and collecting corresponding high performance liquid chromatograms to obtain peak area values of corresponding target substances; and (4) carrying out linear correlation on the peak area value and the concentration of the target object to obtain a quantitative detection model.

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