CN114674952B - Method for detecting sulfonamide antibiotics based on electric field enhanced thin 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. According to the invention, MIL-101 (Cr) is grown in situ on the surface of CC through hydrothermal reaction to be used as a TFME film, and a method for enriching and detecting SAs by combining EE-TFME with high performance liquid chromatography is developed, so that the method is successfully applied to extraction and determination of SAs in animal-derived foods (milk, honey, pork and chicken). The detection limit LOD for detecting SAs is 2.5-4.5ng/mL, the quantitative limit LOQ is 8.0-14.5ng/mL, and the upper limit of the linear range is 200.0ng/mL; the content of the sulfonamide antibiotics is detected through a labeling recovery rate experiment, the labeling recovery rate is 81.7% -114.2%, the matching is good, and the accuracy is high; and the adaptability of the detection method is good.

Description

Method for detecting sulfonamide antibiotics based on electric field enhanced thin 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 p-aminobenzene structure, and are widely used for inhibiting bacterial growth in clinical and animal feed additives and other industries due to low production cost and broad antibacterial spectrum. Because of the widespread use of SAs, residual events detected in foods occur more frequently than other antibiotics such as tetracyclines and oxazolidinones. More seriously, these residues may cause harm to human health, such as allergic reactions, carcinogenesis, teratogenicity and mutagenic effects. Thus, many countries and regions have established the Maximum Residual Limit (MRL) of SAs in foods of animal origin. The food code Commission (CAC), european Union (EU) and China all specify a total SAs MRL of 100 μg/kg. The U.S. Food and Drug Administration (FDA) prescribes that the MRL of sulfadimidine in fat, liver and kidney is 100 μg/kg, and the MRL of sulfadimidine in milk is 25 μg/kg. Thus, there is an urgent need for a rapid, useful and efficient detection method for extracting and quantifying trace amounts of SAs in complex food matrices.

There are many methods of detecting SAs, including High Performance Liquid Chromatography (HPLC), electrochemical sensor analysis, and immunochromatographic strips. Among them, high performance liquid chromatography has high 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 that can extract SAs from food substrates. Several pretreatment methods for SAs in food samples have emerged in recent years, including Solid Phase Microextraction (SPME), magnetic dispersion solid phase extraction (MSPE), and liquid-liquid extraction (LLE). In addition, thin Film Microextraction (TFME) technology is also gaining widespread attention.

TFME has a relatively large extraction phase area, a high sensitivity and a high extraction rate compared to SPME. TFME can extract the adsorbent directly from the extract phase and consumes less organic solvent than MSPE and LLE. Therefore, it has been successfully applied to pretreatment of foods and biological samples. The key to TFME extraction efficiency is the coating material, which gives good extraction results, such as Metal Organic Frameworks (MOFs). MOFs are a class of hybrid materials with a crystal structure, highly tunable porosity and different functions, and are considered to be a promising food sample preparation material.

Traditional TFME relies largely on passive diffusion of analytes between the sample matrix and the coating to achieve extraction equilibrium, which can lead to time-consuming processes of polar or ionic compounds (e.g. protonated amines). To address this difficulty, electric field assisted techniques are increasingly being employed as they can lead to migration of charged targets. Thus, the electric field is potentially useful for enhancing TFME of sass with high conductivity films. Carbon Cloth (CC) is known as a commercial self-supporting substrate, and is characterized by conductivity, macroporosity, strong stability (high temperature and strong acid resistance) and excellent flexibility, which paves the way for wide application of MOFs-modified CCs in the fields of electrochemical detection, electrocatalysis, supercapacitors and the like.

SAs bearing two amino groups are used as examples of ionic analytes in the present invention, given that they are easily deprotonated at a certain pH and potential. The invention explores a new method for applying MIL-101 (Cr) modified CC to electric field enhanced TFME (EE-TFME). MILs-101 (Cr) grows in situ on the CC surface by hydrothermal reaction to increase conductivity and further serves as a working electrode for enhanced extraction of sulfadiazine, sulfathiazole, sulfamethoxazole, sulfadimidine, sulfamethoxazole and sulfamethoxazole. SAs have similar physical and chemical structures, with several modifiable sites and conjugated systems, and six SAs are often used in actual production, we target six SAs as typical. EE-TFME was successfully used in combination with HPLC for the extraction and determination of SAs in foods of animal origin (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, which is based on an MIL-101 (Cr) modified CC electrode to enrich and concentrate SAs, and utilizes an MIL-101 (Cr)/CC combined EE-TFME treated animal sample to detect, so that the extraction method is fast in speed and high in accuracy, and has a practical application prospect.

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

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

carbon cloth MIL-101 (Cr)/CC modified by MIL-101 (Cr) is used as an adsorption extractant, and the adsorption extractant, a direct current stabilized power supply, a sample cell and a platinum wire electrode form an electric field enhanced thin film solid phase microextraction device; immersing MIL-101 (Cr)/CC and platinum wire electrode into sample solution to build complete circuit system, applying positive voltage on MIL-101 (Cr)/CC to adsorb, placing in eluent after adsorption, reversing positive and negative electrodes, applying negative voltage on MIL-101 (Cr)/CC to desorb, separating solid from liquid, collecting clear liquid, concentrating and drying to obtain sulfonamide antibiotics.

In one embodiment of the invention, the MIL-101 (Cr)/CC preparation process comprises the following steps:

(1) Pretreating Carbon Cloth (CC);

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

In one embodiment of the present invention, the process of pre-treating the carbon cloth includes:

washing the carbon cloth with acetone, absolute ethyl alcohol and deionized water respectively, and drying; and soaking the CC in concentrated nitric acid, cleaning the carbon cloth with 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 invention, the concentration of the soluble chromium salt in the mixture is 80-90mg/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 is performed in step (2) 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 hours.

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

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

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-30min.

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

(1) Preparing a high-performance liquid phase sample liquid: the MIL-101 (Cr)/CC is used as an adsorption extractant, and the adsorption extractant, a direct current stabilized power supply, a sample cell and a platinum wire electrode form an electric field enhanced film solid phase microextraction device; 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 MIL-101 (Cr)/CC for adsorption, placing the sample solution after adsorption is finished, then reversing positive and negative electrodes, applying negative voltage on MIL-101 (Cr)/CC for elution and desorption, removing the eluent after elution, and fixing the volume by acetonitrile to obtain a high-efficiency liquid phase sample solution;

(2) High performance liquid phase detection: obtaining a series of liquid chromatography sample liquids of standard samples with known concentrations according to the step (1), and collecting corresponding high performance liquid chromatography to obtain peak area values of corresponding targets; and linearly correlating the peak area value of the target object with the concentration to obtain a quantitative detection model.

In one embodiment of the present invention, when detecting using a high performance liquid chromatography tandem photodiode array detector, the pre-processing further comprises the steps of:

(1) Drying with nitrogen and fixing volume: placing the separated sample solution to be tested in a nitrogen blow-drying device, blowing to be nearly dry, and fixing the volume of acetonitrile to be tested by a filtering membrane;

(2) Preparation of a standard sample: diluting samples to be tested with different concentrations by using a solvent, eluting, drying by drying and fixing the volume after the samples are treated by using an electric field enhanced film solid-phase extraction method, and taking the samples as standard samples for standby.

In one embodiment of the invention, the high performance liquid chromatography column is E clipse Plus C ₁₈ 5 μm 4.6X1250 mm 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 for sulfonamide antibiotics. Based on the auxiliary effect of the electric field and the difference of interaction strength of various structures in the extractant, the adsorption quantity and extraction recovery quantity of the sulfonamide antibiotics are improved. Samples treated with MIL-101 (Cr)/CC according to the present invention were tested: the detection limit LOD of detection is 2.5-4.5ng/mL, the quantitative limit LOQ is 8.0-14.5ng/mL, and the upper limit of the linear range is 200ng/mL; the content of the sulfonamide antibiotics is detected through a labeling recovery rate experiment, the labeling 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 wider practical application prospect.

Drawings

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

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

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

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

FIG. 5 is a graph showing comparison of SAs recovery after various voltages are applied.

FIG. 6 is a graph showing comparison of SAs recovery after various extraction times.

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

FIG. 8 is a high performance liquid chromatogram of a 2.5 μg/mL SDM/ST/SMZ/SMD/SMX/SIZ mixed standard.

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

Detailed Description

The Carbon Cloth (CC) according to the present invention is purchased from taiwan carbon energy company in china.

The high performance liquid chromatography column related by the invention is E clipse Plus C ₁₈ The specific detection conditions of the chromatographic column with the thickness of 5 mu m and the thickness of 4.6X250 mm are as follows:

the invention relates to

m: quality of sulfonamide obtained after EE-TFME, M: quality of sulfonamides added before EE-TFME. Wherein, the mass is measured by an external standard method high performance liquid phase: high performance liquid phase detection was performed on 0.1,0.2,0.5,0.8,1,2.5,5. Mu.g/mL of six SAs in methanol, respectively, and the corresponding standard curves are shown below.

Substance name	Linear equation	R 2
			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, absolute ethyl alcohol and deionized water for 3 times, 15min each time, and drying at 60 ℃ for 12h; next, CC was soaked in concentrated nitric acid for 24 hours, and then the carbon fiber cloth was washed with a large amount of deionized water to be acid-free, and dried at 60 ℃ for 12 hours.

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

Example 2: enrichment of SAs by solid phase microextraction enhanced by MIL-101 (Cr)/CC electric field

At K ₃ [Fe(CN) ₆ ]As shown in FIG. 2, the cyclic voltammetric currents and the impedance of MIL-101 (Cr)/CC and CC are measured in the solution, and the oxidation-reduction potentials of MIL-101 (Cr)/CC and CC are not greatly different, but the response current of MIL-101 (Cr)/CC is larger, the corresponding oxidation peak current and the corresponding reduction peak current are respectively 2.63mA and-3.23 mA, and compared with 0.41mA and-0.99 mA on CC, the oxidation peak current and the reduction peak current are respectively increased by 6 times and 3 times. As shown in fig. 3, R of bare CC _ct 452.6Ω; when MIL-101 (Cr) is loaded on CC, R _ct Reducing to 23.28Ω demonstrated that MILs-101 (Cr) facilitates charge transfer between the electrode and the solution.

In addition, when the external electric field is not applied, the SAs are extracted by using the CC and the MIL-101 (Cr), as shown in fig. 4, the recovery rate is compared, the extraction effect of the CC modified by the MIL-101 (Cr) is obviously better than that of the bare CC, and further, under the same time, the external electric field is applied to the MIL-101 (Cr)/CC, the extraction effect of the external electric field on the SAs is compared, and the recovery rate of the SAs is improved after the electric field is applied.

The extraction and enrichment process comprises the following steps:

the electric field enhanced film solid phase microextraction device consists of a direct current stabilized power supply, a sample cell, a platinum wire electrode and 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, so that a complete circuit system is established.

Applying positive voltage of 0.5V to MIL-101 (Cr)/CC, adsorbing 25mL of 0.01 mug/mL of sulfonamide standard mixed solution (pH 4.0PBS solution), reversing positive and negative electrodes after 15min, keeping the voltage of 0.5V unchanged, eluting with 10mL of 5% ammonia methanol solution for 15min, then blowing nitrogen to near dryness, fixing volume in 1mL of acetonitrile, detecting an extracted sample after fixing volume by using HPLC, and taking peak area as a detection signal to obtain a recovery rate result. As shown in table 1.

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

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:

referring to the method in example 2, the voltage was changed, and the others were unchanged:

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

As shown in table 2 and fig. 5, the extraction efficiency of the target increases with increasing applied potential from 0.1 to 0.5V, which means that with increasing voltage, an electric double layer is formed at the electrode/solution interface, and the charge is forced to move toward the electrode with opposite charge, resulting in electro-adsorption of ions. However, when the applied voltage exceeds 0.5V, the extraction efficiency gradually decreases. On one hand, it is supposed that SAs is directly oxidized on the surface of an MIL-101 (Cr)/CC electrode under higher voltage, and sulfanilamide substances are indirectly oxidized by OH generated on the surface of the electrode to generate substances such as sulfanilic acid, para-aminophenol or aniline, so that the extraction efficiency is reduced; on the other hand, as the voltage increases, a compressive double electric layer effect may be generated, resulting in thinning of the adsorption layer, and thus, a reduction in adsorption effect. Thus, an applied potential of 0.5V was selected as the optimum value.

TABLE 2 recovery results at different voltages

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(2) Referring to the method in example 2, only after 15min of adsorption extraction, the positive and negative electrode inversion was not performed, and desorption was directly performed with eluent:

the positive and negative electrode inversion is not carried out after 15min of adsorption extraction, different eluents are directly used for desorption, the result is measured and compared with the result of carrying out the positive and negative electrode inversion (shown in table 3), the effect of eluting six sulfanilamide substances in a pure organic solvent is hardly influenced, but in an aqueous solution, the effect of eluting without carrying out the positive and negative electrode inversion is obviously weaker than the effect of carrying out the positive and negative electrode inversion, which indicates that the effect of eluting the sulfanilamide medicine in the process is favorably enhanced by carrying out the positive and negative electrode inversion.

TABLE 3 recovery results of each eluent without reversing the positive and negative electrodes

(3) Selection of extraction time:

referring to the procedure in example 2, the extraction time was varied, the others were unchanged:

applying positive voltage of 0.5V to MIL-101 (Cr)/CC, adsorbing 25mL of 0.01 mug/mL of sulfonamide standard mixed solution for 5-35min, reversing positive and negative electrodes after extraction, setting the voltage at 0.5V, eluting with 10mL of 5% ammonia methanol solution for 15min, blowing nitrogen to near dryness, fixing volume in 1mL of acetonitrile, detecting an extracted sample after volume fixing by HPLC, and taking peak area as a detection signal. As a result, as shown in Table 4 and FIG. 6, at an external voltage of 0.5V, the balance of the analyte was almost 15min, and then the recovery rate was changed to a value of 4% -7%, wherein the recovery rates of sulfathiazole, sulfamethidine and sulfaisoxazole were slightly decreased to about 4%, which was probably due to electrochemical oxidation of three substances to generate other substances, but the recovery rates of six substances were almost unchanged as a whole. Therefore, the optimal adsorption time is 15min.

TABLE 4 recovery results at various extraction times

Extraction time

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

A positive voltage of 0.5V was applied to MIL-101 (Cr)/CC, 25mL of a 0.01. Mu.g/mL sulfonamide standard mixed solution (pH 4.0) was adsorbed, the positive and negative electrodes were reversed after 15min, the voltage was set at 0.5V, elution was performed with 10mL of acetonitrile, ethanol, acetone, methylene chloride, methanol, 5% methanolic ammonia solution, PBS (pH 9.0), isopropanol for 15min, nitrogen was blown to near dryness, the volume was set in 1mL of acetonitrile, the volume-fixed extracted sample was detected by HPLC, and the peak area was the detection signal. As can be seen from table 5 and fig. 7, the ability of MILs-101 (Cr)/CC to extract the target is minimal under alkaline conditions, so it is speculated that appropriate alkaline conditions promote desorption of the analyte from the MOF and increase its solubility in the organic solvent. In addition, open metal sites of MILs-101 (Cr)/CC exposed to solvent environments have greater affinity for polar solvents. Acetone is less polar in the chosen organic solvent and therefore has the lowest desorption efficiency relative to 33.7%,13.3%,32.6%,27.3%,4.4% and 59.5%, respectively. In addition, in the elution process in the experiment, the voltage of the two poles is reversed, and meanwhile, the selected water is PBS (pH 9.0) solution, so that after the voltage is reversed, the charges with the same polarity between the target and the electrode are mutually repelled, so that the elution effect in water is better, but still is inferior to that of a 5% ammonia methanol solution. Finally, 5% ammonia methanol was used as the desorption solvent.

TABLE 5 recovery results for different eluents

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(5) The extraction and adsorption mode is selected:

the method comprises the following steps: MIL-101 (Cr)/CC obtained in example 1 or simple CC (1X 2 cm) ² ) Directly adsorbing 25mL of 0.01 mug/mL of the sulfonamide standard mixed solution, eluting with 10mL of 5% ammonia methanol solution for 15min after 15min, blowing nitrogen to near dryness, fixing the volume in 1mL of acetonitrile, detecting the extracted sample after fixing the volume by using HPLC, and taking the peak area as a detection signal.

The second method is as follows:

firstly, applying positive voltage of 0.8V to MIL-101 (Cr)/CC, adsorbing 25mL of 0.01 mug/mL of sulfonamide standard substance mixed solution, reversing positive and negative electrodes after 15min, setting the voltage at 0.5V, eluting with 10mL of 5% ammonia methanol solution for 15min, blowing nitrogen to near dryness, 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.

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

TABLE 6 recovery results for different extraction and enrichment modes

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

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

The electric field enhanced film solid phase microextraction device consists of a direct current stabilized power supply, a sample cell, a platinum wire electrode and MIL-101 (Cr)/CC. Immersing MILs-101 (Cr)/CC and platinum wire electrodes in a standard or sample solution creates a complete electrical circuit system, and applying a positive voltage of 0.5V across MILs-101 (Cr)/CC promotes migration of negatively charged SAs formed by deprotonation in an electric field thereto. Extracting in PBS solution with pH of 4.0 for 15min, taking MIL-101 (Cr)/CC out of the bottle, reversing positive and negative power supply, keeping voltage unchanged, continuing desorbing in 5% ammonia methanol solution for 15min, blow-drying with nitrogen, and fixing volume with acetonitrile to 1mL for HPLC analysis, wherein the obtained peak area is used as analysis signal of sulfonamide.

(2) Quantitative detection model:

the validity of the method was verified by analyzing characteristic parameters such as linearity, detection limit (LOD, S/n=3), quantification limit (LOQ, S/n=10) and the daily and daytime precision established based on MILs-101 (Cr)/CC by linear correlation of peak areas with the concentrations of the corresponding standard samples, and the results are shown in table 7. The linear range of the method is 10.0-200.0ng/mL, and the determination coefficient (R ² ) Between 0.9912 and 0.9967, LOD between 2.5 and 4.5ng/mL and LOQ between 8.0 and 14.5ng/mL, the reproducibility of the method was also investigated, and Relative Standard Deviation (RSD) was used to indicate its precision, with RSD of less than 7.8% and 9.1% between day and day, respectively, indicating good reproducibility of the method.

TABLE 7 quantitative determination results

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

Example 5 method adaptation: detection of sulfonamide antibiotics in different animal foods

Pork and chicken samples were homogenized and stored at-20 ℃.8g sample with 20mL of 6% acetonitrile acetate and 5g Na ₂ SO ₄ After mixing, vortexing for 5min, centrifuging at 8500rpm for 10min at 4 ℃. In a centrifuge tube, 8g of the honey sample was mixed with 16mL of Na ₂ EDTA-Mclvaine buffer solution. 8g milk samples were mixed with 10mL acetonitrile in a centrifuge tube. After vortexing for 1min, the milk samples were 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 was labeled with 50 and 100 μg/kg SAs to evaluate their practical applicability. SDM was detected in milk and pork, whereas SMD was detected in pork at a concentration of 24.4+ -3.3 μg/kg (both below European Union MRL and national standards). The recovery of six SAs in the samples was between 81.7% and 114.2% with RSDs less than 8.6%. This also verifies the accuracy of the developed method. See in particular table 8.

TABLE 8 concentration of SAs in actual samples (. Mu.g/kg), RSD (%, n=3) and standard recovery (%)

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Claims (10)

1. A method for enriching and extracting sulfonamide antibiotics, which is characterized by comprising the following steps:

carbon cloth MIL-101 (Cr)/CC modified by MIL-101 (Cr) is used as an adsorption extractant, and the adsorption extractant, a direct current stabilized power supply, a sample cell and a platinum wire electrode form an electric field enhanced thin film solid phase microextraction device; 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 MIL-101 (Cr)/CC for adsorption, placing the sample solution after adsorption is finished, then reversing positive and negative electrodes, applying negative voltage on MIL-101 (Cr)/CC for elution and desorption, carrying out solid-liquid separation, collecting clear liquid, concentrating and drying to obtain the sulfonamide antibiotics;

the sulfonamide antibiotic is SDM, ST, SMZ, SMD, SMX, SIZ;

the eluent is 5% ammonia methanol solution.

2. The method of claim 1, wherein the MILs-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; adding the treated carbon cloth into the mixed solution, performing hydrothermal reaction, collecting the carbon cloth after the reaction is finished, and washing to obtain MIL-101 (Cr)/CC modified carbon cloth MIL-101 (Cr)/CC.

3. The process according to claim 2, wherein the mass ratio of soluble chromium salt to terephthalic acid is (4-5): 1.

4. the method of claim 2, wherein the concentration of the soluble chromium salt in the mixture is 80-90mg/mL.

5. The method according to claim 2, wherein the volume ratio of hydrofluoric acid to water in the mixed solution is 1: (90-100).

6. The method of claim 2, wherein the hydrothermal reaction in step (2) is a soak reaction 8h at 220 ℃.

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

8. The method of claim 1, wherein the positive and negative voltages are independently selected from 0.4-0.6V.

9. The method of claim 1, wherein the medium of the sample solution is a ph4.0 PBS solution.

10. The method for quantitatively detecting the sulfonamide antibiotics by the high-efficiency liquid phase is characterized by comprising the following steps of:

(1) Preparing a high-performance liquid phase sample liquid: an MIL-101 (Cr)/CC as claimed in claim 2 is used as an adsorption extractant, and the adsorption extractant, a direct current stabilized voltage supply, a sample cell and a platinum wire electrode form an electric field enhanced film solid phase microextraction device; 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 MIL-101 (Cr)/CC for adsorption, placing the sample solution after adsorption is finished, then reversing positive and negative electrodes, applying negative voltage on MIL-101 (Cr)/CC for elution and desorption, removing the eluent after elution, and fixing the volume by acetonitrile to obtain a high-efficiency liquid phase sample solution; the sulfonamide antibiotic is SDM, ST, SMZ, SMD, SMX, SIZ; the eluent is 5% ammonia methanol solution;

(2) High performance liquid phase detection: obtaining a series of liquid chromatography sample liquids of standard samples with known concentrations according to the step (1), and collecting corresponding high performance liquid chromatography to obtain peak area values of corresponding targets; and linearly correlating the peak area value of the target object with the concentration to obtain a quantitative detection model.

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