Plasticizer detection pretreatment method and device based on magnetic layered double hydroxide

Abstract

The present invention provides a method and device for pre-treatment of plasticizer detection based on magnetic layered double hydroxide, belonging to the technical field of food detection. The method comprises the following steps: 3 O 4 @ZnAl‑LDH / ZIF‑8 was added to the edible oil sample, and hot gas with a temperature of ≥60°C was bubbled into the edible oil sample for 2min‑20min of bubbling adsorption; Fe was separated 3 O 4 @ZnAl‑LDH / ZIF‑8, and add a desorbent to elute to obtain an eluent; after the eluent is dried, a solvent is added to the fixed volume to form a sample to be tested. 3 O 4 @ZnAl‑LDH / ZIF‑8 was added to the edible oil sample, and hot gas with a temperature of ≥60°C was blown into the edible oil sample to utilize Fe 3 O 4 @ZnAl‑LDH / ZIF‑8 can be used to pre-treat edible oil samples, improving the detection efficiency and accuracy of plasticizers. Experiments show that when DBP, DEHP, and DIBP are spiked samples at a spike level of 0.1 mg / kg, the average recovery rate is 85.6%‑103.2%. 3 O 4 @ZnAl‑LDH / ZIF‑8 is used to pre-treat edible oil samples, which is beneficial to shorten the pre-treatment time of edible oil samples and improve the pre-treatment efficiency of edible oil samples.

Description

Technical Field

[0001] The invention belongs to the technical field of food detection, and particularly relates to a plasticizer detection pre-treatment method and device based on magnetic layered double hydroxide. Background Art

[0002] Sesame oil, also known as linseed oil, is mainly a fatty oil extracted from the seeds of the sesame plant of the family Sesame. It contains a large amount of fat, protein, calories, and nutrients such as calcium, iron, and sodium. It has high nutritional value and is beneficial to human health if consumed in moderation. However, in all aspects of sesame oil production, such as the planting, transportation, and storage of raw sesame, the processing of sesame oil, and the packaging and storage of sesame oil, it may be contaminated by plasticizers (phthalates, PAEs).

[0003] Research has proposed a variety of methods for detecting plasticizers in edible oils to continuously reduce the detection limit and improve the detection accuracy. The use of magnetic micro-solid phase extraction materials for pretreatment of edible oil samples has been proven to be an effective pretreatment method for the detection of plasticizers in edible oils. For example, the magnetic COF (Fe3O4@COF (TbBD) proposed by Zhao Yuanli et al. has a low detection limit, good linearity, a wide linear range, a low inter-day and intra-day relative standard deviation (RSD) and a high spike recovery rate; for another example, Zhang Yunxia et al. proposed that the magnetic imprinted polymer Fe3O4@MIPs has better adsorption of plasticizers in edible oils than commercial columns on the market, and can be used for sample pretreatment for the detection of di-n-octyl phthalate plasticizers in edible oils.

[0004] Magnetic layered double hydroxide-metal organic framework Fe3O4@ZnAl-LDH / ZIF-8 is a new composite material developed by Di Xin's team at Ningxia Medical University. Its preparation process and its application in the detection of hormone-interfering substances are recorded in the Chinese invention patent with publication number CN112108120A. The above composite material can detect the target components sensitively, simply and quickly.

[0005] The study hopes to use Fe3O4@ZnAl-LDH / ZIF-8 composite materials in the pre-treatment process of edible oil plasticizer detection. However, practice shows that the method of extracting the target substance as shown in the Chinese invention patent with publication number CN112108120A is poor in adsorption effect and low in detection accuracy. Summary of the invention

[0006] Based on this, the present invention provides a plasticizer detection pretreatment method based on magnetic layered double hydroxide to solve the technical problems in the prior art of poor adsorption effect and low detection accuracy when using Fe3O4@ZnAl-LDH / ZIF-8 composite materials to extract plasticizers from edible oil products.

[0007] The invention also provides a plasticizer detection pre-processing device based on magnetic layered double hydroxide.

[0008] The technical solution of the present invention to solve the above technical problems is as follows:

[0009] A plasticizer detection pretreatment method based on magnetic layered double hydroxide comprises the following steps:

[0010] S01. Add Fe3O4@ZnAl-LDH / ZIF-8 into the edible oil sample, and bubble hot gas with a temperature of ≥60°C into the edible oil sample for bubbling adsorption for 2min-20min;

[0011] S02. Separate Fe3O4@ZnAl-LDH / ZIF-8, and add a desorbent to elute to obtain an eluent;

[0012] S03. After the eluent is dried, a solvent is added to make up the volume to form a sample to be tested.

[0013] Preferably, in step S02, after separating Fe3O4@ZnAl-LDH / ZIF-8, a detergent is first added for elution, and the eluent is discarded; then a desorbent is added for elution, and the eluent is collected.

[0014] Preferably, in step S01, hot gas with a temperature of 60° C.-90° C. is blown into the edible oil sample, and the hot gas is selected from at least one of nitrogen, air, carbon dioxide, argon and oxygen.

[0015] Preferably, the desorbent is selected from at least one of acetonitrile, ethanol, methanol, ethyl acetate, n-hexane and acetone.

[0016] A plasticizer detection pre-treatment device based on magnetic layered double hydroxide, comprising:

[0017] An extraction cup, the upper end of which is open and provided with a cover; the cover is provided with a desorbent feed pipe for introducing a desorbent into the extraction cup;

[0018] A hot gas feed pipe, one end of which is connected to the bottom of the extraction cup, and the other end of which is connected to a gas source, and a gas heater and a first stop valve are provided on the hot gas feed pipe;

[0019] a solid-liquid separator, the solid-liquid separator being disposed on the cover body via a connecting rod, the solid-liquid separator being capable of retaining the solid-phase composite material added to the extraction cup in the extraction cup and discharging the liquid added to the extraction cup; and

[0020] The eluent test tube trough is connected to the discharge end of the extraction cup and is used for placing a test tube for collecting the eluent.

[0021] Preferably, the plasticizer detection pretreatment device based on magnetic layered double hydroxide further comprises a waste liquid collection tank, which is connected to the discharge end of the extraction cup and is used to collect waste liquid.

[0022] Preferably, the solid-liquid separator comprises an electromagnet disposed on the cover body via a connecting rod, and the electromagnet is electrically connected to a relay switch.

[0023] Preferably, a pressurized gas feed pipe is further provided on the cover body, one end of the pressurized gas feed pipe is connected to the extraction cup, and the other end is connected to a gas source, and a second stop valve is provided on the pressurized gas feed pipe.

[0024] Preferably, a drying gas feed pipe is provided on the eluent test tube tank, the other end of the drying gas feed pipe is connected to a gas source, and a third stop valve is provided on the drying gas feed pipe.

[0025] Preferably, a solvent feed pipe is also provided on the eluent test tube tank, and a fourth stop valve is provided on the solvent feed pipe.

[0026] Compared with the prior art, the present invention has at least the following advantages:

[0027] The present invention provides a plasticizer detection pretreatment method based on magnetic layered double hydroxide, wherein Fe3O4@ZnAl-LDH / ZIF-8 is added to an edible oil sample, and hot gas with a temperature of ≥60°C is blown into the edible oil sample, thereby using Fe3O4@ZnAl-LDH / ZIF-8 to achieve pretreatment of the edible oil sample, thereby improving the detection efficiency and accuracy of the plasticizer. Experiments show that when DBP, DEHP, and DIBP are used as spiked samples, the average recovery rate is 85.6%-103.2% when the spiked level is 0.1 mg / kg. At the same time, using Fe3O4@ZnAl-LDH / ZIF-8 to pretreat the edible oil sample is beneficial to shortening the pretreatment time of the edible oil sample and improving the pretreatment efficiency of the edible oil sample.

[0028] The present invention also provides a plasticizer detection pretreatment device based on magnetic layered double hydroxide, comprising an extraction cup, a hot gas feed pipe for bubbling into the extraction cup, a solid-liquid separation part for separating the solid phase and the liquid phase in the extraction cup, and an eluent test tube slot for placing a test tube for collecting the eluent. The edible oil sample to be detected and the magnetic layered double hydroxide (Fe3O4@ZnAl-LDH / ZIF-8) are placed in the extraction cup together, and hot gas with a temperature of ≥60°C is bubbled into the extraction cup through the hot gas feed pipe. On the one hand, bubbling is performed to fully mix the edible oil sample and the magnetic layered double hydroxide. On the other hand, the hot gas is used to destroy the liquid film on the surface of the magnetic layered double hydroxide to promote the adsorption of the plasticizer by the magnetic layered double hydroxide. After the bubbling adsorption is completed, the magnetic layered double hydroxide in the extraction cup is separated from the edible oil sample, and the edible oil sample is discharged from the extraction cup. Then, a desorbent is added into the extraction cup to elute the magnetic layered double hydroxide adsorbed with the plasticizer, and the eluate is collected in a test tube placed in the eluate test tube slot. The plasticizer detection pretreatment device based on magnetic layered double hydroxide provided by the present invention not only realizes the pretreatment of edible oil samples using magnetic layered double hydroxide, but also completes at least two solid-liquid separation steps in the pretreatment process of edible oil samples through the extraction cup, thereby optimizing the operation process and further improving the pretreatment efficiency of edible oil samples. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 Schematic diagram of the equipment flow of a plasticizer detection pretreatment device based on magnetic layered double hydroxide in one embodiment.

[0030] Figure 2 This is a trend chart of the maximum spiked recoveries calculated for Experimental Examples 1 to 5.

[0031] In the figure: a plasticizer detection pretreatment device 10 based on magnetic layered double hydroxide, an extraction cup 100, a cover 110, a desorbent feed pipe 120, a detergent feed pipe 130, a pressure gas feed pipe 140, a second stop valve 141, a tapered portion 150, a pressure relief pipe 160, a seventh stop valve 161, a hot gas feed pipe 200, a gas heater 210, a first stop valve 220, a solid-liquid separator 300, a connecting rod 301, a relay switch 310, an eluent test tube tank 400, a blow-drying gas feed pipe 410, a third stop valve 411, a solvent feed pipe 420, a fourth stop valve 421, and a waste liquid collection tank 500. DETAILED DESCRIPTION

[0032] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present invention can be combined with each other. The technical solution of the present invention will be further described below in conjunction with the drawings of the embodiments of the present invention, and the present invention is not limited to the following specific implementation methods.

[0033] It should be understood that the same or similar reference numerals in the drawings of the embodiments correspond to the same or similar components. In the description of the present invention, it should be understood that if the terms "upper", "lower", "front", "back", "left", "right", "top", "bottom" and the like indicate an orientation or positional relationship based on the orientation or positional relationship shown in the drawings, it is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the terms describing the positional relationship in the drawings are only used for illustrative purposes and cannot be understood as a limitation on this patent. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0034] In a specific embodiment, a plasticizer detection pretreatment method based on magnetic layered double hydroxide comprises the following steps:

[0035] S01. Add Fe3O4@ZnAl-LDH / ZIF-8 into the edible oil sample, and bubble hot gas with a temperature of ≥60°C into the edible oil sample for bubbling adsorption for 2min-20min.

[0036] It should be noted that the above-mentioned Fe3O4@ZnAl-LDH / ZIF-8 is prepared by the method described in the Chinese invention patent publication number CN112108120A.

[0037] Preferably, hot gas at a temperature of 60° C. to 90° C. is bubbled into the edible oil sample, and the hot gas is selected from at least one of nitrogen, air, carbon dioxide, argon, and oxygen. For example, hot nitrogen at a temperature of 75° C. is bubbled into the edible oil sample. The bubbling time is preferably 2 min to 10 min, more preferably 5 min to 10 min.

[0038] S02. Separate Fe3O4@ZnAl-LDH / ZIF-8, add a desorbent to elute, and obtain an eluent.

[0039] After the bubbling adsorption is completed, the solid Fe3O4@ZnAl-LDH / ZIF-8 adsorbed with the plasticizer component is separated from the edible oil sample to be tested, and a desorbent is added for elution to obtain an eluate.

[0040] The method of separating Fe3O4@ZnAl-LDH / ZIF-8 from the edible oil sample to be tested may optionally include centrifugal separation, filtration separation, external magnetic field separation, etc. Based on the magnetic properties of Fe3O4@ZnAl-LDH / ZIF-8, it is preferred to separate Fe3O4@ZnAl-LDH / ZIF-8 and the edible oil sample by external magnetic field separation.

[0041] The desorbent is a solvent that can dissolve the plasticizer. For example, the desorbent is selected from at least one of acetonitrile, ethanol, methanol, ethyl acetate, n-hexane, and acetone. Preferably, the desorbent is acetonitrile or n-hexane or a mixed solution of n-hexane and acetone. For example, the desorbent is an acetone and n-hexane solution in a volume ratio of 1:3.

[0042] In some preferred embodiments, before adding a desorbent to Fe3O4@ZnAl-LDH / ZIF-8 adsorbed with plasticizer components, a detergent is first added for elution, and the eluent is discarded. Then a desorbent is added for elution, and the eluent is collected. The detergent is selected from a solvent with low polarity, such as n-hexane or petroleum ether. Preferably, the detergent is selected from n-hexane.

[0043] S03. After the eluent is dried, a solvent is added to make up the volume to form a sample to be tested.

[0044] After the obtained eluent is dried, a solvent is added to fix the volume to form a test sample to be analyzed by chromatography. The solvent is selected according to the detection requirements of the chromatography, for example, the solvent is selected from one or a mixture of methanol, acetonitrile, and n-hexane.

[0045] In a specific embodiment, 1g of Fe3O4@ZnAl-LDH / ZIF-8 is added to 10ml of edible oil sample, and hot nitrogen at a temperature of 75°C is introduced for bubbling. After 5 minutes, the bubbling ends. Fe3O4@ZnAl-LDH / ZIF-8 is separated by an external magnetic field, first eluted with 2ml of n-hexane, and the eluent is discarded. Then, the plasticizer adsorbed on Fe3O4@ZnAl-LDH / ZIF-8 is eluted twice with a mixed solution of acetone and n-hexane in a volume ratio of 1:3, and the eluent is collected. After the eluent is dried, n-hexane is added to make up the volume, and then tested. In the above process, the total pretreatment time for an edible oil sample is less than or equal to 20 minutes, which effectively improves the pretreatment efficiency of the edible oil sample.

[0046] In the present invention, Fe3O4@ZnAl-LDH / ZIF-8 is added to the edible oil sample, and hot gas with a temperature of ≥60°C is blown into the edible oil sample, so that Fe3O4@ZnAl-LDH / ZIF-8 is used to pre-treat the edible oil sample, thereby improving the detection efficiency and accuracy of plasticizers. Experiments show that when DBP, DEHP, and DIBP are used as spiked samples, the average recovery rate is 85.6%-103.2% when the spiked level is 0.1 mg / kg. At the same time, using Fe3O4@ZnAl-LDH / ZIF-8 to pre-treat the edible oil sample is beneficial to shorten the pre-treatment time of the edible oil sample and improve the pre-treatment efficiency of the edible oil sample.

[0047] Please see Figure 1 In another specific embodiment of the present invention, a plasticizer detection pretreatment device 10 based on magnetic layered double hydroxide is used to pretreat edible oil samples using magnetic layered double hydroxide (Fe3O4@ZnAl-LDH / ZIF-8, hereinafter referred to as "magnetic layered double hydroxide") to detect the plasticizer content in the edible oil samples. The plasticizer detection pretreatment device 10 based on magnetic layered double hydroxide includes an extraction cup 100, a hot gas feed pipe 200, a solid-liquid separation element 300 and an eluent test tube tank 400.

[0048] The upper end of the extraction cup 100 is open and is provided with a cover 110. The cover 110 is provided with a desorbent feed pipe 120 for introducing a desorbent into the extraction cup 100. One end of the hot gas feed pipe 200 is connected to the bottom of the extraction cup 100, and the other end is connected to a gas source. The hot gas feed pipe 200 is provided with a gas heater 210 and a first stop valve 220.

[0049] The solid-liquid separator 300 is disposed on the cover 110 via a connecting rod 301. The solid-liquid separator 300 can retain the solid-phase composite material added to the extraction cup 100 in the extraction cup 100 and discharge the liquid added to the extraction cup 100. The eluent test tube tank 400 is connected to the discharge end of the extraction cup 100 and is used to place a test tube for collecting the eluent.

[0050] The edible oil sample to be tested and the magnetic layered double hydroxide are placed together in the extraction cup 100, and hot gas with a temperature of ≥60°C is blown into the extraction cup 100 through the hot gas feed pipe 200. On the one hand, bubbling is performed to fully mix the edible oil sample and the magnetic layered double hydroxide. On the other hand, the hot gas is used to destroy the liquid film on the surface of the magnetic layered double hydroxide to promote the adsorption of the plasticizer by the magnetic layered double hydroxide. After the bubbling adsorption is completed, the magnetic layered double hydroxide in the extraction cup 100 is separated from the edible oil sample, and the edible oil sample is discharged from the extraction cup 100. Then, a desorbent is added to the extraction cup 100 to elute the magnetic layered double hydroxide adsorbed with the plasticizer, and the eluent is collected in a test tube placed in the eluent test tube tank 400. The plasticizer detection pretreatment device 10 based on magnetic layered double hydroxide provided by the present invention not only realizes the pretreatment of edible oil samples using magnetic layered double hydroxide, but also completes at least two solid-liquid separation steps in the pretreatment process of edible oil samples through the extraction cup 100, thereby optimizing the operation process and further improving the pretreatment efficiency of edible oil samples.

[0051] Specifically, the cover 110 and the solid-liquid separator 300 are removed to facilitate the addition of the edible oil sample to be tested and the magnetic layered double hydroxide adsorption material into the extraction cup 100. After adding the sample, the cover 110 is closed, and the solid-liquid separator 300 is located below the liquid level of the sample to be tested. Hot air is blown into the extraction cup 100 through the hot gas feed pipe 200, so that the edible oil sample to be tested and the magnetic layered double hydroxide are fully mixed, and the magnetic layered double hydroxide can efficiently adsorb the plasticizer components in the edible oil sample to be tested. After bubbling for a period of time, the bubbling is stopped and the material is unloaded. During the unloading process, the liquid phase material, such as sample edible oil, detergent, desorbent, etc., is discharged, and the solid magnetic layered double hydroxide is intercepted by the solid-liquid separator 300, so as to complete two to three solid-liquid separation processes in the extraction cup 100, simplify the operation process, and improve the pre-treatment efficiency of the edible oil sample.

[0052] In one specific embodiment, the solid-liquid separator 300 includes a filter bag having micropores that allow liquid substances such as sample edible oil, detergent and desorbent to pass through and can retain magnetic layered double hydroxide. When in use, the magnetic layered double hydroxide is wrapped in the filter bag, and the filter bag is placed in the edible oil sample. Under the bubbling effect of hot air, the plasticizer in the edible oil sample is adsorbed by the magnetic layered double hydroxide. After the adsorption is completed, the edible oil sample is discharged from the extraction cup 100, and the magnetic layered double hydroxide is retained in the filter bag. After the edible oil sample is discharged, detergent and desorbent are added respectively to wash and desorb the magnetic layered double hydroxide.

[0053] In order to further improve the separation efficiency of magnetic layered double hydroxide, reduce costs, and save the pre-treatment time of edible oil samples, the solid-liquid separator 300 includes an electromagnet arranged on the cover 110 through a connecting rod 301, and the electromagnet is electrically connected to a relay switch 310. When in use, the electromagnet is in a power-off state, and the magnetic layered double hydroxide is mixed in the edible oil sample. Under the bubbling action of hot air, the plasticizer in the edible oil sample is adsorbed by the magnetic layered double hydroxide. After the adsorption is completed, the electromagnet is energized and continuously bubbled, so that the magnetic layered double hydroxide is adsorbed by the electromagnet, and then the edible oil sample is discharged from the extraction cup 100. After the edible oil sample is discharged, detergent and desorbent are added respectively, and the magnetic layered double hydroxide is washed and desorbed. During the washing and desorption process, the electromagnet can be in a power-off state and bubbled to improve the efficiency of washing and desorption. After washing and desorption are completed, the electromagnet is powered on to better separate the magnetic layered double hydroxide from the liquid phase.

[0054] In a preferred embodiment, a detergent feed pipe 130 is further provided on the cover body 110 for introducing detergent into the extraction cup 100 to rinse the magnetic layered double hydroxide adsorbed with the plasticizer component.

[0055] In a preferred embodiment, the plasticizer detection pretreatment device 10 based on magnetic layered double hydroxide further includes a waste liquid collection tank 500, which is connected to the discharge end of the extraction cup 100 and is used to collect waste liquid. After the bubbling adsorption is completed, the edible oil sample after solid-liquid separation and the eluent generated after eluting the magnetic layered double hydroxide are discharged into the waste liquid collection tank 500.

[0056] In some embodiments, a pressure gas feed pipe 140 is further provided on the cover body 110, one end of the pressure gas feed pipe 140 is connected to the extraction cup 100, and the other end is connected to a gas source, and a second stop valve 141 is provided on the pressure gas feed pipe 140. After the edible oil sample and the magnetic layered double hydroxide are bubbled in the extraction cup 100 for a period of time, the adsorption ends, and at this time, the material in the extraction cup 100 needs to be discharged to proceed to the next step. When discharging, the second stop valve 141 is opened, and gas is introduced into the extraction cup 100 through the pressure gas feed pipe 140 to accelerate the discharging process, and after discharging, the extraction cup 100 is purged to ensure that the material is completely discharged. The gas source connected to the pressure gas feed pipe 140 may be different from the gas source connected to the hot gas feed pipe 200. Preferably, in order to save space and reduce the size of the equipment, the gas source connected to the pressure gas feed pipe 140 may be the same as the gas source connected to the hot gas feed pipe 200.

[0057] In some embodiments, a blow-drying gas feed pipe 410 is provided on the eluent test tube slot 400, and the other end of the blow-drying gas feed pipe 410 is connected to a gas source, and a third stop valve 411 is provided on the blow-drying gas feed pipe 410. After the eluent is discharged into the test tube placed in the eluent test tube slot 400, nitrogen or air is introduced into the eluent test tube slot 400 to blow dry the eluent. The gas source connected to the blow-drying gas feed pipe 410 may be different from the gas source connected to the hot gas feed pipe 200. Preferably, in order to save space and reduce the volume of the equipment, the gas source connected to the blow-drying gas feed pipe 410 may be the same as the gas source connected to the hot gas feed pipe 200. Preferably, the blow-drying gas feed pipe 410 is arranged at the discharge end of the gas heater 210, so as to use the gas heater 210 to heat the gas, accelerate the blow-drying process of the eluent, and further improve the pre-treatment efficiency.

[0058] A solvent feed pipe 420 is also provided on the eluent test tube tank 400, and a fourth stop valve 421 is provided on the solvent feed pipe 420, so that after the desorption liquid in the test tube placed in the desorption liquid test tube tank 400 is blown dry, a solvent is added to the test tube to dissolve the residue for chromatographic determination of the content and type of the plasticizer.

[0059] In some embodiments, to facilitate discharge, a tapered portion 150 is disposed at the lower end of the extraction cup 100 .

[0060] In some embodiments, the cover 110 is further provided with a pressure relief pipe 160, and a seventh stop valve 161 is provided on the pressure relief pipe 160. During the process of blowing hot air into the extraction cup 100, the pressure is released through the pressure relief pipe 160, and the pressure in the extraction cup 100 is controlled to be 0.01Mpa-0.03Mpa, so as to be more conducive to the adsorption of the plasticizer by the magnetic layered double hydroxide.

[0061] In another specific embodiment of the present invention, a method for pre-treatment of plasticizer detection based on magnetic layered double hydroxide is also provided. The method is implemented by a plasticizer detection pre-treatment device 10 based on magnetic layered double hydroxide provided in a specific embodiment of the present invention, and comprises the following steps:

[0062] T01. Add the edible oil sample to be tested and the magnetic layered double hydroxide to the extraction cup 100;

[0063] T02. Bubbling hot gas at a temperature of ≥60°C into the extraction cup 100 for 2-20 minutes;

[0064] T03. Discharging the edible oil sample to be tested, and causing the magnetic layered double hydroxide to be trapped in the extraction cup 100;

[0065] T04. A desorbent is introduced into the extraction cup 100, and bubbling is continued for 5 min-20 min to perform elution, and the eluate is collected;

[0066] T05. After the eluent is dried, add solvent to make up the volume to form the sample to be tested.

[0067] Preferably, in step T03, after the adsorption is completed, the solid-liquid separator 300 (electromagnet) is energized to continue bubbling, so that the magnetic layered double hydroxide is adsorbed by the solid-liquid separator 300 and then the edible oil sample to be tested is discharged.

[0068] Preferably, hot gas with a temperature of 60° C. to 90° C. is bubbled into the extraction cup 100, and the hot gas is selected from at least one of nitrogen, air, carbon dioxide, argon, and oxygen. For example, hot nitrogen with a temperature of 75° C. is bubbled into the extraction cup 100. The bubbling time is preferably 2 min to 10 min, more preferably 5 min to 10 min.

[0069] The desorbent is a solvent that can dissolve the plasticizer. For example, the desorbent is selected from at least one of acetonitrile, ethanol, methanol, ethyl acetate, n-hexane, and acetone. Preferably, the desorbent is acetonitrile or n-hexane or a mixed solution of n-hexane and acetone. For example, the desorbent is an acetone and n-hexane solution in a volume ratio of 1:3.

[0070] In some preferred embodiments, before adding the desorbent to the extraction cup 100, a detergent is first added for elution, and the eluent is discarded. Then, a desorbent is added for elution, and the eluent is collected. The detergent is selected from a solvent with low polarity, such as n-hexane or petroleum ether. Preferably, the detergent is selected from n-hexane.

[0071] Preferably, after the obtained eluent is dried, a solvent is added to fix the volume to form a test sample to be analyzed by chromatography. The solvent is selected according to the detection requirements of the chromatography, for example, the solvent is selected from one or a mixture of methanol, acetonitrile, and n-hexane.

[0072] The technical solution and technical effects of the present invention are further illustrated below through specific experimental examples.

[0073] Comparative Example 1

[0074] Sesame oil without detected plasticizer components (tested based on the method provided in GB 5009.271-2016) was used to prepare 0.1 mg / kg standard solutions of DBP, DEHP, and DIBP respectively.

[0075] Take 10 ml of the above standard solution and add it to a glass tube. Weigh 1.00 g of Fe3O4@ZnAl-LDH / ZIF-8 and add it to the above standard solution. Vortex for 10 minutes, magnetically separate Fe3O4@ZnAl-LDH / ZIF-8, elute with 2 ml of acetonitrile, and discard the eluent. Then ultrasonically elute Fe3O4@ZnAl-LDH / ZIF-8 twice with a mixture of acetone and n-hexane in a volume ratio of 1:3, and collect the eluent. After the eluent is dried, it is fixed to volume with n-hexane, and the contents of DBP, DEHP, and DIBP are determined by high performance liquid chromatography (HPLC), and the spike recovery rate is calculated. The calculation results are shown in Table 1.

[0076] Comparative Example 2

[0077] Sesame oil without detected plasticizer components (tested based on the method provided in GB 5009.271-2016) was used to prepare 0.1 mg / kg standard solutions of DBP, DEHP, and DIBP respectively.

[0078] Take 10 ml of the above standard solution respectively, add it to the extraction cup 100, weigh 1.00 g of Fe3O4@ZnAl-LDH / ZIF-8 and add it to the above standard solution. During the adsorption process, introduce nitrogen at room temperature, bubble for 10 minutes, magnetically separate Fe3O4@ZnAl-LDH / ZIF-8, elute with 2 ml of acetonitrile, and discard the eluent. Then, bubble and elute Fe3O4@ZnAl-LDH / ZIF-8 twice with a mixture of acetone and n-hexane in a volume ratio of 1:3, and collect the eluent. After the eluent is dried, n-hexane is used to make up the volume, and the contents of DBP, DEHP, and DIBP are determined by high performance liquid chromatography (HPLC), and the spike recovery rate is calculated. The calculation results are shown in Table 1.

[0079] Experimental Example 1

[0080] During the adsorption process, hot nitrogen gas at a temperature of 35° C. was introduced, and the rest was the same as in Comparative Example 2.

[0081] Experimental Example 2

[0082] During the adsorption process, hot nitrogen gas at a temperature of 50° C. was introduced, and the rest was the same as in Comparative Example 2.

[0083] Experimental Example 3

[0084] During the adsorption process, hot nitrogen gas at a temperature of 60° C. was introduced, and the rest was the same as in Comparative Example 2.

[0085] Experimental Example 4

[0086] During the adsorption process, hot nitrogen gas at a temperature of 75° C. was introduced, and the other procedures were the same as those in Comparative Example 2.

[0087] Experimental Example 5

[0088] During the adsorption process, hot nitrogen gas at a temperature of 90° C. was introduced, and the rest was the same as in Comparative Example 2.

[0089] The spiked recoveries of DBP, DEHP and DIBP in the above examples were calculated respectively, as shown in Table 1.

[0090] Table 1 Statistics of spike recovery

[0091]

[0092] Please refer to Table 1. Comparative Examples 1 and 2 show that the standard homogenization method (bubbling or vortexing) is used to use Fe3O4@ZnAl-LDH / ZIF-8. The recovery rate of the spike is low and cannot meet the detection requirements. Experimental Examples 1 and 2 show that when bubbling is performed with low-temperature gas, the recovery rate of the spike is still low and cannot meet the detection requirements. The inventor accidentally discovered that when bubbling is performed with a higher temperature gas (hot gas ≥60°C), the recovery rate of the spike reaches more than 90%, which can meet the detection requirements for the plasticizer content in edible oil.

[0093] Please also see Figure 2 The inventors further verified the effect of the temperature of the bubbling gas on the detection of plasticizer content in edible oil products using Fe3O4@ZnAl-LDH / ZIF-8. When the bubbling gas is at a lower temperature, the sample spike recovery rate is improved, but not significantly. When the temperature of the bubbling gas reaches 60°C, the sample spike recovery rate changes significantly, and further increasing the temperature is conducive to improving the sample spike recovery rate.

[0094] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A plasticizer detection pretreatment method based on magnetic layered double hydroxide, characterized in that: The following steps are involved: S01. Add Fe3O4@ZnAl-LDH / ZIF-8 into the edible oil sample, and bubble hot gas with a temperature of ≥60°C into the edible oil sample for 2min-20min of bubbling adsorption; S02. Magnetic separation of Fe3O4@ZnAl-LDH / ZIF-8, adding acetonitrile for elution, discarding the eluent; and adding a desorbent for elution to obtain an eluent; the desorbent is a mixture of acetone and n-hexane in a volume ratio of 1:3; S03. After the eluent is dried, a solvent is added to the fixed volume to form a sample to be tested; Provided is a plasticizer detection pretreatment device based on magnetic layered double hydroxide, which is used to implement the plasticizer detection pretreatment method based on magnetic layered double hydroxide, comprising: An extraction cup, the upper end of which is open and provided with a cover; the cover is provided with a desorbent feed pipe for introducing a desorbent into the extraction cup; A hot gas feed pipe, one end of which is connected to the bottom of the extraction cup, and the other end of which is connected to a gas source, and a gas heater and a first stop valve are provided on the hot gas feed pipe; A solid-liquid separator, the solid-liquid separator comprising an electromagnet disposed on the cover body via a connecting rod, the electromagnet being electrically connected to a relay switch; the solid-liquid separator can retain the solid-phase composite material added to the extraction cup in the extraction cup, and can discharge the liquid added to the extraction cup; as well as The eluent test tube trough is connected to the discharge end of the extraction cup and is used for placing a test tube for collecting the eluent.

2. The plasticizer detection pretreatment method based on magnetic layered double hydroxide according to claim 1, characterized in that: In step S01, hot gas with a temperature of 60° C. to 90° C. is blown into the edible oil sample, and the hot gas is selected from at least one of nitrogen, air, carbon dioxide, argon, and oxygen.

3. The plasticizer detection pretreatment method based on magnetic layered double hydroxide according to claim 1, characterized in that: The plasticizer detection pretreatment device based on magnetic layered double hydroxide also includes a waste liquid collection tank, which is connected to the discharge end of the extraction cup and is used to collect waste liquid.

4. The plasticizer detection pretreatment method based on magnetic layered double hydroxide according to claim 1, characterized in that: The cover body is also provided with a pressurized gas feed pipe, one end of which is connected to the extraction cup, and the other end is connected to a gas source, and a second stop valve is provided on the pressurized gas feed pipe.

5. The plasticizer detection pretreatment method based on magnetic layered double hydroxide according to claim 1, characterized in that: A drying gas feed pipe is arranged on the eluent test tube tank, the other end of the drying gas feed pipe is connected to a gas source, and a third stop valve is arranged on the drying gas feed pipe.

6. The method for pre-treatment of plasticizer detection based on magnetic layered double hydroxide according to claim 5, characterized in that: The eluent test tube tank is also provided with a solvent feed pipe, and the solvent feed pipe is provided with a fourth stop valve.

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