A rod-shaped MgO solid phase extraction adsorbent and its application in the enrichment and detection of benzo[a]pyrene

Abstract

The invention discloses a rod-shaped MgO solid phase extraction adsorbent and its application in the enrichment and detection of benzo[a]pyrene. The rod-shaped MgO solid phase extraction adsorbent of the invention can remove a large amount of matrix in edible oil, has good purification effect, and has a high recovery rate of benzo[a]pyrene. It is combined with a universal and low-cost liquid chromatography-fluorescence detector to separate and detect benzo[a]pyrene, and can realize low-cost rapid detection of benzo[a]pyrene in large quantities of edible oil samples, and has high detection sensitivity, good accuracy, and good reproducibility.

Description

Technical Field

[0001] The invention belongs to the technical field of rapid detection, and particularly relates to a rod-shaped MgO solid phase extraction adsorbent, which is particularly suitable for the enrichment and rapid detection of benzo[a]pyrene in a large number of edible oil samples. Background Art

[0002] Benzo[a]pyrene, also known as 3,4-benzopyrene (BaP), is a common pollutant in the environment, mainly from incomplete combustion of cigarettes, gas, hot cooking, diesel exhaust and wood smoke particles. BaP is the most representative of all polycyclic aromatic hydrocarbons (PAHs), and its carcinogenicity is significantly higher than other polycyclic aromatic hydrocarbons. It can cause damage to the DNA of peripheral blood lymphocytes, lung cells and liver cells in rats. Since both edible oil and BaP are lipophilic, edible oil is easily contaminated by BaP during processing.

[0003] Edible oil has a complex matrix and high lipid content, and BaP is also very lipophilic. Therefore, to complete the analysis of BaP, it is very necessary to extract and purify it efficiently. At present, liquid-liquid extraction (LLE), solid phase extraction (SPE), magnetic solid phase extraction (MSPE), solid phase microextraction (SPME) and gel permeation chromatography (GPC) are used to extract and purify BaP in edible oil. Among them, SPE is the most widely used sample pretreatment technology because of its high recovery rate, low organic solvent consumption, good reproducibility, simple operation and easy automation. However, the traditional normal phase silica gel solid phase extraction adsorbent and reverse phase C18 column have poor selectivity. Therefore, the development of a new BaP extraction medium has important research value.

[0004] my country's "GB 2762-2022 Limits of Contaminants in Food" clearly stipulates that the limit standard for BaP in edible oil shall not exceed 10μg / kg, and smoked and barbecued meat and grain shall not exceed 5μg / kg. The limit requirements are consistent with the standards set by the European Union and the World Health Organization. Edible oil is consumed in large quantities in my country and is an important part of our daily diet. It can provide essential lipids for human health. Therefore, how to quickly, efficiently and sensitively detect BaP in edible oil is a focus of attention in the field of food safety. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a rod-shaped MgO solid phase extraction adsorbent in view of the deficiencies in the prior art, so as to achieve the selective extraction of benzo[a]pyrene in edible oil, avoid the use of high-cost immunoaffinity columns, benzo[a]pyrene-specific columns and other chemical adsorbents, and have the advantages of being environmentally friendly, low cost, high extraction efficiency, etc. On this basis, a rapid detection method for benzo[a]pyrene in edible oil is constructed.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is as follows:

[0007] A rod-shaped MgO solid phase extraction adsorbent for selective extraction of benzo[a]pyrene, wherein the macroscopic property is powder, and the microscopic morphology is rod-shaped MgO particles with a diameter of 3.5 to 5.0 μm and a length of 50 to 120 μm, presenting a polycrystalline cubic structure. The average pore size of the powder characterized by nitrogen adsorption experiment is 5 to 15 nm, and the BET specific surface area is 80 to 120 m 2 g -1 .

[0008] The present invention also provides a solid phase extraction column for enriching benzo[a]pyrene, which is obtained by filling the above-mentioned rod-shaped MgO solid phase extraction adsorbent.

[0009] The above-mentioned rod-shaped MgO solid phase extraction adsorbent can be used for the enrichment and / or detection of benzo[a]pyrene in edible oil. The specific application method steps are as follows:

[0010] (1) After the edible oil sample to be tested is diluted with n-hexane, the benzo[a]pyrene therein is enriched through the above-mentioned solid phase extraction column to obtain a solid phase extraction column enriched with benzo[a]pyrene;

[0011] (2) cleaning the solid phase extraction column enriched with benzo[a]pyrene to remove interfering substances, and then desorbing the column to obtain a desorption solution enriched with benzo[a]pyrene;

[0012] (3) The desorption liquid is dried with nitrogen and then redissolved, and the obtained redissolved solution is the injection liquid enriched with benzo[a]pyrene (i.e., the injection liquid of the edible oil sample to be tested); the injection liquid is detected by high performance liquid chromatography-fluorescence detector.

[0013] According to the above scheme, in step (1), the volume ratio of the edible oil sample to be tested and n-hexane is in the range of 0.1 to 0.2; the mass ratio between the edible oil sample to be tested and the rod-shaped MgO solid phase extraction adsorbent filled in the solid phase extraction column is 14:(1 to 3), and the most preferred ratio is 7:1.

[0014] According to the above scheme, in step (2), the cleaning solvent is ethyl acetate; the desorption solvent is a dichloromethane solution of methylimidazole, wherein the volume percentage of methylimidazole in dichloromethane is 1-10%, preferably the volume percentage of methylimidazole in dichloromethane is 2-7%, and most preferably 3%; the volume ratio of the cleaning solvent to the mass ratio of the edible oil sample to be tested is in the range of 2-10, preferably 6-8; the volume ratio of the desorption solvent to the mass ratio of the edible oil sample to be tested is in the range of 1.5-15, preferably 4-13.

[0015] According to the above scheme, the re-dissolving solvent in step (3) is a mixed solution of acetonitrile and water, and the volume ratio of the two is in the range of 2 to 8; the volume ratio of the re-dissolving solvent to the edible oil sample to be tested is in the range of 1 to 5.

[0016] According to the above scheme, when the detection is performed by high performance liquid chromatography-fluorescence detector in step (3), the benzo[a]pyrene standard product is first prepared into a series of standard solutions of concentration, and analyzed by high performance liquid chromatography-fluorescence detector, and a standard curve of benzo[a]pyrene is drawn with the concentration of benzo[a]pyrene as the horizontal coordinate and the corresponding peak area as the vertical coordinate; then the injection liquid enriched with benzo[a]pyrene is analyzed by high performance liquid chromatography-fluorescence detector, and the peak area is substituted into the standard curve, so as to obtain the content of benzo[a]pyrene in the injection liquid, and then the content of benzo[a]pyrene residue in the edible oil sample to be tested is converted.

[0017] According to the above scheme, the linear range of benzo[a]pyrene concentration of the standard curve is generally in the range of 0.5 to 20 μg / kg.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] (1) The present invention uses rod-shaped MgO as a solid phase extraction medium to achieve selective extraction of BaP in edible oil.

[0020] (2) The present invention uses a solid phase extraction column filled with rod-shaped MgO to enrich benzo[a]pyrene, avoiding the use of high-cost immunoaffinity columns, BaP special columns and other chemical adsorbents, and the analysis cost is reduced by 2-5 times compared with the traditional method, and has the advantages of being environmentally friendly, low cost, and high extraction efficiency. Compared with the immunoaffinity columns (>80 yuan / piece) and dispersed solid phase extraction adsorbents (>600 yuan / 100g) in the background technology, the rod-shaped MgO solid phase extraction adsorbent of the present invention has a very low cost (less than 100 yuan for 100g), which can greatly save the cost of sample analysis in large-scale sample analysis.

[0021] (3) Based on the rod-shaped MgO solid phase extraction adsorbent, the present invention constructs a large-scale, low-cost BaP analysis method system in edible oil. First, a one-step solid phase extraction technology is used to achieve rapid enrichment and purification of benzo[a]pyrene in edible oil, which can remove a large amount of matrix in edible oil, has good purification effect, and has a high recovery rate of benzo[a]pyrene, avoiding the shortcomings of traditional liquid-liquid extraction, centrifugation and gel permeation chromatography, such as high consumption of organic solvents and cumbersome steps; then, a universal, low-cost high-performance liquid chromatography-fluorescence detection method is combined to separate and detect benzo[a]pyrene, which greatly reduces the cost of sample analysis, can achieve low-cost rapid detection of large quantities of edible oil samples, and has high detection sensitivity and accuracy, good reproducibility, and has a good application prospect in actual sample analysis. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The figure is a specific schematic diagram of the pretreatment method of solid phase extraction of edible oil according to the present invention, wherein the target substance is BaP.

[0023] Figure 2 XRD pattern (a), FTIR spectrum (b), and scanning electron microscope images (c, d) of the rod-shaped MgO solid phase extraction adsorbent prepared in Example 1.

[0024] Figure 3 Chromatograms of benzo[a]pyrene (a) spiked sample (5 μg / kg), (b) standard sample (2 μg / kg) and (c) blank solvent.

[0025] Figure 4 The recovery rate of benzo[a]pyrene with different mass and dosage of rod-shaped magnesium oxide is shown in Figure 2.

[0026] Figure 5 The recovery results of benzo[a]pyrene with different cleaning solvents are shown in Figure 2.

[0027] Figure 6 The recovery results of benzo[a]pyrene with different desorption solvents.

[0028] Figure 7 The recovery results of benzo[a]pyrene with different desorption solvent volumes.

[0029] Figure 8 Benzo[a]pyrene recovery results with different loading solution volumes. DETAILED DESCRIPTION

[0030] In order to better understand the present invention, the content of the present invention is further explained below in conjunction with the embodiments, but the present invention is not limited to the following embodiments.

[0031] In the present invention, the preparation method of the rod-shaped MgO solid phase extraction adsorbent is as follows: 8.0-12.0 g of Mg(NO3)2·6H2O is dissolved in 40-60 mL of ultrapure water, and heated to 40-60° C. to dissolve to obtain a Mg(NO3)2 solution; then 3-5 g of Na2CO3 and 0.05-0.15 g of Na2SiO3 are added to 50-150 mL of ultrapure water, and heated to 40-60° C. to dissolve to obtain a mixed solution of Na2CO3 and Na2SiO3. Under magnetic stirring (such as 800r / min), the mixed solution of Na2CO3 and Na2SiO3 is quickly mixed with the Mg(NO3)2 solution, and heated at a constant temperature of 40-60°C for 0.5-1.5 hours. The obtained product is washed with ultrapure water and anhydrous ethanol, and then placed in a muffle furnace at 500-600°C and heated at high temperature for 2-4 hours to obtain rod-shaped magnesium oxide particles with a macroscopic morphology of white powder, i.e., rod-shaped MgO solid phase extraction adsorbent.

[0032] In the following examples, BaP standard solution (20.0 mg / L) was purchased from Shanghai Anpu Laboratory Technology Co., Ltd. (Shanghai, China); chromatographically pure acetonitrile, n-hexane, and isopropanol were purchased from Merck, Germany, and other reagents were of analytical grade; different edible oil samples were purchased from the Wuhan market; ultrapure water was prepared by a Milli-Q water purifier (Millipore, Billerica, MA, USA); and BaP edible oil quality control samples were purchased from China Inspection and Certification (Beijing) Testing Co., Ltd.

[0033] In the following examples, 100 μL of BaP standard solution (20.0 mg / L) was accurately drawn and placed in a 10 mL volumetric flask, constant volume was made with n-hexane, and a 200 μg / L standard stock solution was prepared as the standard solution for the addition recovery experiment, protected from light, and stored in a 4°C refrigerator for standby use. The 200 μg / L BaP standard stock solution was diluted with isopropanol to prepare a series of standard solutions (0 to 20.0 μg / L) with mass concentrations of 0, 0.5 μg / L, 1.0 μg / L, 2.0 μg / L, 5.0 μg / L, 10.0 μg / L, and 20.0 μg / L for drawing a standard curve. The standard solution was stored in a 4°C refrigerator protected from light. Experiments have shown that under this condition, all standard products can be stably stored for at least one month.

[0034] Example 1: Synthesis of Rod-Shaped MgO Solid Phase Extraction Adsorbent

[0035] Dissolve 10.26g of Mg(NO3)2·6H2O in 50mL ultrapure water, place in a 250mL three-necked flask, and heat at 50℃ to dissolve. Add 0.10g of sodium silicate (Na2SiO3) to 100mL of 0.4M Na2CO3 and dissolve, and heat to 50℃. Under magnetic stirring (800r / min), the Na2CO3 solution and the Mg(NO3)2 solution are quickly mixed and heated at 50℃ for 1 hour. The product is washed three times with ultrapure water and anhydrous ethanol, and then placed in a muffle furnace at 550℃ and heated for 3 hours to obtain rod-shaped magnesium oxide particles with a macroscopic morphology of white powder, i.e., rod-shaped MgO solid phase extraction adsorbent for selective extraction of benzo[a]pyrene.

[0036] The physical and chemical properties of MgO materials were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and infrared spectroscopy. Figure 2 As shown in a, the XRD pattern of the MgO material has obvious diffraction peaks at 36.92°, 42.98°, 62.35°, 74.66° and 78.66°, corresponding to (111), (002), (202), (113) and (222) planes (JCPDS No. 87-0653), indicating that the MgO material is a polycrystalline cubic structure. At the same time, no other impurity phases were found in the XRD pattern, showing a high-intensity (002) preferred orientation peak, indicating that the synthesized material has a high degree of crystallinity, and the addition of a small amount of NaSiO3 does not affect the crystal structure of the MgO material.

[0037] FTIR spectrum of MgO material prepared by direct precipitation method Figure 2 As shown in b, 411cm -1 Peak and 614cm -1 The peaks correspond to the stretching vibration and bending vibration of the Mg-O bond. The peaks are at about 3268-3452 cm due to the stretching vibration of the OH of the water molecule. -1 A broad band was observed at wave number 1449 cm -1 The FT-IR absorption peak seen at is attributed to the carbonate ion CO3 2- This is due to the fact that even at high temperatures, H2O and CO3 2- The spectral bands produced by the groups are also inevitable and basically consistent with the literature reports.

[0038] Figure 2 c and Figure 2 d shows a typical scanning electron microscope image of the magnesium oxide material prepared in Example 1, wherein Figure 2c is a low-power scanning electron microscope image, showing that the panoramic morphology of the sample is composed of rod-shaped particles with a diameter of 3.5-5.0 μm and a length of 50-120 μm. At the same time, the pore structure and specific surface area of ​​the rod-shaped MgO solid phase extraction adsorbent were characterized by nitrogen adsorption test. The average pore diameter of the MgO material is 11.0 nm, and the BET specific surface area is 102.4 m 2 g -1 The large specific surface area provides abundant action sites and is very suitable as an adsorbent for SPE.

[0039] Example 2: Preparation of a solid phase extraction column for enriching benzo[a]pyrene

[0040] 100 mg of the rod-shaped MgO adsorbent prepared in Example 1 was weighed and loaded into a 3 mL SPE column. The column was continuously tapped to make it uniform without channeling. Both ends of the adsorbent were pressed tightly with a polyethylene sieve plate and a glass rod to obtain a rod-shaped MgO SPE column for enriching benzo[a]pyrene.

[0041] Example 3: Use of rod-shaped MgO solid phase extraction adsorbent for the enrichment and detection of benzo[a]pyrene in edible oil

[0042] This embodiment provides a low-cost method suitable for rapid detection of BaP in large quantities of edible oil samples, which involves the enrichment and detection of benzo[a]pyrene in edible oil. The specific steps are as follows:

[0043] 1) Weigh 0.7 g of edible oil, dilute with 7 mL of n-hexane as the sample solution to be purified, and vortex for 1 min for later use;

[0044] 2) taking the rod-shaped MgO SPE column (100 mg, 3 mL) prepared in Example 2, activating it with 3 mL of n-hexane before use, transferring the sample solution to be purified obtained in step 1) into the rod-shaped MgO SPE column, discarding the effluent, and obtaining an SPE column enriched with benzo[a]pyrene, thereby achieving the enrichment of BaP in the sample solution to be purified;

[0045] 3) The SPE column enriched with benzo[a]pyrene was eluted with 3 mL of ethyl acetate, and then desorbed with 3 mL of dichloromethane (containing 3% methylimidazole) to obtain a desorption solution enriched with benzo[a]pyrene;

[0046] 4) The desorbed solution was blown dry with N2, and re-dissolved with 1.0 mL of acetonitrile-water (80 / 20, v / v). The obtained re-solution was used as the injection solution for rapid determination of BaP in edible oil, which was used for subsequent analysis by high performance liquid chromatography-fluorescence detector;

[0047] 5) A series of BaP standard solutions with mass concentrations of 0.5 μg / L, 1.0 μg / L, 2.0 μg / L, 5.0 μg / L, 10.0 μg / L and 20.0 μg / L are analyzed by high performance liquid chromatography-fluorescence detector, and a standard curve of benzo[a]pyrene is drawn with the concentration of benzo[a]pyrene as the abscissa and the corresponding peak area as the ordinate; then 1 mL of the injection solution obtained in step 4) is analyzed by high performance liquid chromatography-fluorescence detector, and the peak area is substituted into the standard curve to obtain the content of benzo[a]pyrene in the injection solution, and then the content of benzo[a]pyrene residue in the edible oil sample to be tested is converted.

[0048] In this embodiment, as well as in subsequent embodiments, the detection conditions of the high performance liquid chromatography-fluorescence detector (HPLC-FLD) are as follows: chromatographic conditions are as follows: chromatographic column, Inertsil ODS-3 (250×4.6 mm, 5 μm); mobile phase, V (acetonitrile): V (water) = 88:12, flow rate, 1.0 mL / min; fluorescence detector: excitation wavelength (λex): 384 nm, emission wavelength (λem): 406 nm; column temperature: 40°C; injection volume: 10 μL.

[0049] In this embodiment, the linear equation of BaP in the linear range of 0.5-20 μg / kg is Y=144627X+5441.03, and the square of the regression coefficient of the linear equation (R 2 ) was 0.9999, and the detection limit and quantification limit calculated by 3 times and 10 times the signal-to-noise ratio were 0.10μg / kg and 0.33μg / kg, respectively.

[0050] Example 4

[0051] In order to evaluate the accuracy and precision of the low-cost method for rapid detection of BaP in large quantities of edible oil samples provided by the present invention, the recovery rate of the method was investigated in this example. The specific steps are as follows:

[0052] (1) Weigh 0.7 g of edible oil sample and place it in a 10 mL centrifuge tube, add low, medium and high concentrations of BaP as the edible oil sample to be tested, dilute the edible oil sample to be tested with 3 mL of n-hexane, and vortex for 1 min for later use;

[0053] (2) The rod-shaped MgO SPE column (100 mg, 3 mL) prepared in Example 2 was activated with 3 mL of n-hexane, and the edible oil sample to be tested obtained in step 1) was transferred into the rod-shaped MgO SPE column, and the effluent was discarded to obtain an SPE column enriched with benzo[a]pyrene;

[0054] (3) The SPE column enriched in benzo[a]pyrene obtained in step (2) was eluted with 3 mL of ethyl acetate, and then desorbed with 3 mL of dichloromethane (containing 3% methylimidazole) to obtain a desorption solution enriched in benzo[a]pyrene;

[0055] (4) The desorption solution obtained in step (3) was dried with N2, and redissolved in 1.0 mL of acetonitrile-water (80 / 20, v / v). The resulting redissolved solution was the injection solution for rapid determination of BaP in edible oil;

[0056] (5) The injection liquid obtained in step (4) was analyzed by HPLC-FLD, and the peak area was substituted into the standard curve corresponding to Example 3 to calculate the concentration of benzo[a]pyrene in the injection liquid; then, the recovery rate of BaP addition was obtained by dividing the calculated value by the added value.

[0057] In addition, experiments were conducted with 6 groups of parallel samples prepared separately within one day, and the intra-day relative standard deviation was calculated based on the test results obtained; experiments were conducted with samples prepared separately for 6 consecutive days, and the inter-day relative standard deviation was calculated based on the test results obtained. The results are shown in Table 1.

[0058] Table 1: Recovery and intra-day and inter-day precision of three concentrations of Bap added to edible oil

[0059]

[0060]

[0061] As shown in Table 1, the recoveries of low, medium and high spiked concentrations of BaP in edible oil are between 85.3% and 96.5%, and the intra-day and inter-day relative standard deviations are between 2.3% and 9.0%, indicating that the method has good accuracy and precision and can meet the requirements of daily detection of BaP in edible oil. This shows that the low-cost method established by the present invention, which is suitable for rapid detection of BaP in large quantities of edible oil samples, has good reproducibility.

[0062] Example 5

[0063] In this example, 8 kinds of edible oil samples were analyzed as the edible oil samples to be tested, and the applicability of the method was investigated by using the actual blank sample spike recovery method. Enrichment and detection were performed according to Example 4, and the peak areas were substituted into the linear equations corresponding to Example 3 to calculate the concentration of BaP in each edible oil sample to be tested; then, the BaP addition recovery rate was obtained by dividing the calculated value by the added value. The BaP recovery rate results of different types of edible oils are shown in Table 2.

[0064] Table 2: Addition recovery and relative standard deviation of actual sample analysis

[0065]

[0066] Note: The concentration added to the sample is 5 μg / kg.

[0067] As shown in Table 2, the recoveries of eight actual edible oil samples were between 77.8% and 92.5%, and the relative standard deviation was less than 9.4%, indicating that this method has good applicability and has good application prospects in actual sample analysis.

[0068] Example 6

[0069] In this example, BaP in a quality control sample of edible oil is rapidly detected. The specific steps are carried out with reference to Example 3 to prepare an injection solution for rapid determination of BaP in edible oil.

[0070] The sample solution of this example was analyzed under HPLC-FLD conditions, and the results were as follows: the measured value of BaP quality control sample of edible oil was 9.44 μg / kg, the actual content of BaP was 11.53 μg / kg, and the recovery rate was 81.9%, indicating that the method has strong applicability and has a good application prospect in actual sample analysis.

[0071] Comparative Example 1

[0072] This comparative example was carried out with reference to Example 3, and the effects of different dosages (50, 80, 100 and 150 mg) of rod-shaped MgO solid phase extraction adsorbent on the extraction efficiency of BaP were compared. The results are shown in FIG. Figure 4 As shown. As the amount of adsorbent increases from 50 mg to 100 mg, the recovery rate of BaP also gradually increases. When the amount of adsorbent is 100 mg, the extraction efficiency reaches the maximum value. If the amount of adsorbent continues to increase, the recovery rate will decrease slightly. Therefore, the embodiment of the present invention selects 100 mg of rod-shaped MgO solid phase extraction adsorbent for use.

[0073] Comparative Example 2

[0074] This comparative example was carried out with reference to Example 3, and the effects of different cleaning solvent types (n-hexane, ethyl acetate and ethanol) on the extraction efficiency of BaP were compared. The results are shown in FIG. Figure 5 As shown. With the increase of solvent polarity, the recovery rate of BaP slightly decreases. Even with the use of high-polarity ethanol, the recovery rate of BaP is still around 80%, indicating that there is a strong interaction between the rod-shaped MgO solid phase extraction adsorbent and BaP. In order to ensure a high recovery rate and good purification effect, the present invention selects ethyl acetate with medium polarity as the cleaning solvent to remove as much sample matrix as possible under the mode of normal phase extraction mechanism.

[0075] Comparative Example 3

[0076] This comparative example was carried out with reference to Example 3, and the effects of different desorption solvents (dichloromethane containing 0%, 1%, 3%, 5%, and 7% methylimidazole) on the extraction efficiency of BaP were compared. The results are shown in FIG. Figure 6 As shown. From 0% to 3%, the recovery rate of the target substance increases with the increase of methylimidazole content. From 3% to 7%, the recovery rate increases slightly and then decreases with the increase of methylimidazole. Therefore, the present invention selects 3% methylimidazole dichloromethane solution as the desorption solvent.

[0077] Comparative Example 4

[0078] This comparative example was carried out with reference to Example 3, and the effects of different desorption solvent dosages (1, 3, 5, 7 mL) on the extraction efficiency of BaP were compared. The results are shown in FIG. Figure 7 As shown. When the desorption solvent dosage is 3 mL, the recovery rate tends to be the maximum, and as the desorption solvent is further increased, the recovery rate is slightly reduced. This may be because 3 mL of desorption solvent can completely desorb BaP on the adsorbent. Increasing the dosage of desorption solvent will prolong the concentration time and may cause the loss of the target. Therefore, the embodiment of the present invention selects 3 mL as the optimal desorption solvent volume.

[0079] Comparative Example 5

[0080] This comparative example was carried out with reference to Example 3, and the effects of different loading solution volumes (i.e., adding 1 to 10 mL of n-hexane to dilute in step 1) on the extraction efficiency of BaP were compared. The results are shown in FIG. Figure 8 As shown in the figure, with the increase of the loading solution volume, the extraction recovery rate decreased slightly. In order to ensure a high recovery rate and reduce the interference of the matrix, it is better to use 7mL of loading solution.

[0081] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principles of the present invention shall be equivalent replacement methods and shall be included in the protection scope of the present invention.

Claims

1. Application of rod-shaped MgO solid phase extraction adsorbent in the enrichment and / or detection of benzo[a]pyrene in edible oil, characterized in that: The specific application steps are as follows: (1) After the edible oil sample to be tested is diluted with n-hexane, benzo[a]pyrene in the edible oil sample to be tested is enriched by a solid phase extraction column filled with a rod-shaped MgO solid phase extraction adsorbent to obtain a solid phase extraction column enriched with benzo[a]pyrene; (2) The solid phase extraction column enriched in benzo[a]pyrene is cleaned to remove interferences, and then desorbed to obtain a desorption solution enriched in benzo[a]pyrene; wherein the cleaning solvent is ethyl acetate; the desorption solvent is a dichloromethane solution of methylimidazole, and the volume percentage of methylimidazole to dichloromethane is 1 to 10%; (3) drying the desorption solution and then redissolving it, and the obtained redissolution is the injection solution enriched with benzo[a]pyrene; and the injection solution is detected by high performance liquid chromatography-fluorescence detector; The rod-shaped MgO solid phase extraction adsorbent is a rod-shaped MgO particle with a diameter of 3.5-5.0 μm and a length of 50-120 μm, presenting a polycrystalline cubic structure and a BET specific surface area of ​​80-120 m 2 g -1 .

2. The use of the rod-shaped MgO solid phase extraction adsorbent according to claim 1 in the enrichment and / or detection of benzo[a]pyrene in edible oil, characterized in that: In step (2), the ratio of the volume of the cleaning solvent to the mass of the edible oil sample to be tested is in the range of 2 to 10, and the ratio of the volume of the desorption solvent to the mass of the edible oil sample to be tested is in the range of 1.5 to 15, wherein the volume is measured in mL and the mass is measured in g.

3. The use of the rod-shaped MgO solid phase extraction adsorbent according to claim 1 in the enrichment and / or detection of benzo[a]pyrene in edible oil, characterized in that: In step (1), the volume ratio of the edible oil sample to be tested and n-hexane is in the range of 0.1 to 0.

2.

4. The use of the rod-shaped MgO solid phase extraction adsorbent according to claim 1 in the enrichment and / or detection of benzo[a]pyrene in edible oil, characterized in that: In step (3), the re-dissolving solvent is a mixed solvent of acetonitrile and water in a volume ratio of 2 to 8; the volume ratio of the re-dissolving solvent to the edible oil sample to be tested is in the range of 1 to 5.

5. The use of the rod-shaped MgO solid phase extraction adsorbent according to claim 1 in the enrichment and / or detection of benzo[a]pyrene in edible oil, characterized in that: When the detection is performed by high performance liquid chromatography-fluorescence detector in step (3), the benzo[a]pyrene standard product is first prepared into a series of standard solutions of concentration, which are analyzed by high performance liquid chromatography-fluorescence detector, and a standard curve of benzo[a]pyrene is drawn with the concentration of benzo[a]pyrene as the horizontal coordinate and the corresponding peak area as the vertical coordinate; then, the injection solution enriched with benzo[a]pyrene is analyzed by high performance liquid chromatography-fluorescence detector, and the peak area is substituted into the standard curve to obtain the content of benzo[a]pyrene in the injection solution, and then the content of benzo[a]pyrene residue in the edible oil sample to be tested is converted.

6. The use of the rod-shaped MgO solid phase extraction adsorbent according to claim 5 in the enrichment and / or detection of benzo[a]pyrene in edible oil, characterized in that: The linear range of the benzo[a]pyrene concentration of the standard curve is within the range of 0.5 to 20 μg / kg, and the detection limit and quantification limit are respectively below 0.15 μg / kg and 0.40 μg / kg.

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