Oil phase separation-composite adsorption integrated purification method for complex food detection

Abstract

The application discloses an oil phase separation-composite adsorption integrated purification method for complex food detection, and belongs to the technical field of food detection sample pretreatment. The method adopts an integrated purification assembly comprising a phase separation cavity, a phase selective transfer channel, a quantitative transfer cavity, a composite adsorption cavity and a purification liquid collecting cavity. An oil-containing sample is mixed with an oil phase inducing solvent, an acetonitrile extract and a phase separation salt and centrifuged to form an oil phase and a target extract phase; after a negative pressure is formed in the quantitative transfer cavity, a first valve is opened, a predetermined volume of the target extract phase is transferred to the quantitative transfer cavity and isolated from the oil phase, and then sequentially passes through a C8 bonded porous silica gel layer, an activated magnesium silicate and partially acetylated PSA layer, an anhydrous sodium sulfate layer and a filter layer to obtain a to-be-detected purified liquid. The method can complete phase separation, quantitative transfer, layered adsorption and filter collection in the same assembly, and reduces the possibility of external transfer and oil phase entrainment.

Description

Technical Field

[0001] This invention relates to the field of food sample pretreatment technology, and in particular to an integrated purification method of oil phase separation and composite adsorption for the detection of complex foods. Background Technology

[0002] Edible oils, chili sauces, chili oils, hot pot bases, peanut butter, sesame paste, nut products, and meat products typically contain a high proportion of fats and oils. These fats and oils mainly include triglycerides, but may also include diglycerides, monoglycerides, free fatty acids, phospholipids, sterols, and their derivatives.

[0003] When performing chromatographic or chromatographic-mass spectrometric detection of pesticide residues, veterinary drug residues, mycotoxins, non-edible substances, illegal additives, or other trace targets in the aforementioned foods, oils entrained in the sample extract may enter the purification materials, chromatographic column, and detection system along with the test solution. These oils may increase the load on the purification materials, clog the flow path, contaminate the chromatographic column or detection system, and may also cause ion inhibition or ion enhancement, thereby affecting the accuracy and repeatability of the detection results.

[0004] Existing dispersion solid-phase extraction or solid-phase extraction methods typically involve directly contacting the extract of high-oil samples with hydrophobic adsorbents, polar adsorbents, or mixtures thereof. Since the content of the oil to be treated is usually much higher than the content of trace target analytes, some adsorption sites on the adsorbent material are easily occupied by a large amount of oil, causing the limited amount of adsorbent material to reach or approach its upper limit of adsorption capacity.

[0005] Different foods have varying fat content and lipid composition. When using the same type and amount of adsorbent material, the residual oil content in the target analyte extract can easily vary depending on the type of food and the sample composition. While increasing the amount of adsorbent material can improve the matrix's carrying capacity, it may also increase the non-specific adsorption of the target analyte and the cost of sample pretreatment.

[0006] Furthermore, existing methods typically require manually transferring the target extract phase, after liquid-liquid partitioning, to another clean container. This manual transfer process can easily disturb the phase interface and introduce oily phases, and may also result in sample loss or cross-contamination due to repeated opening, aspiration, and transfer.

[0007] If only a continuously open fluid channel is provided between the phase separation container and the composite adsorption zone, during pressurization, suction, or centrifugation, as the target extract phase continuously leaves the phase separation container, the phase interface may move to the suction inlet, allowing the oil-containing phase to enter the composite adsorption zone. Therefore, in addition to determining the location of the suction inlet, it is also necessary to quantify the target extract phase entering the composite adsorption zone and isolate the phase separation container from the composite adsorption zone after reaching the predetermined transfer volume.

[0008] Different analytes exhibit varying polarity, acid-base dissociation properties, lipid solubility, and interactions with adsorbent materials. Therefore, the composition of the extract and the combined adsorption conditions can be adjusted based on the phase partitioning behavior and adsorption characteristics of different analytes.

[0009] Therefore, it is necessary to provide a purification method that separates the bulk oil-containing phase before composite adsorption, performs phase-selective quantitative transfer of the target extract phase, and then classifies the residual neutral lipids, polar lipids, free fatty acids and water, and can complete phase separation, quantitative transfer, adsorption, filtration and collection in the same component. Summary of the Invention

[0010] Based on this, the present invention provides an integrated oil phase separation-composite adsorption purification method for complex food detection. The method employs an integrated purification assembly for sample purification. This integrated purification assembly includes a phase separation chamber, a phase-selective transfer channel, a quantitative transfer chamber, a composite adsorption chamber, and a purification liquid collection chamber, all connected sequentially. The phase-selective transfer channel is equipped with a liquid inlet and a first valve. A second valve is provided between the quantitative transfer chamber and the composite adsorption chamber. The quantitative transfer chamber has a gas channel with a gas valve, and the purification liquid collection chamber has a pressure balancing channel. The method includes the following steps: S1, the oil-containing complex food sample is placed in the phase separation chamber, an oil phase inducing solvent is added and mixed, then acetonitrile extract and phase separation salt are added and mixed, so that the oil and the target analyte in the sample are respectively distributed to the oil-containing phase and the acetonitrile-rich target analyte extraction phase; wherein, the first valve, the second valve and the gas path valve are all kept closed; S2, the mixture obtained in step S1 is centrifuged for the first time to form a phase-separated system that includes at least an oil-containing phase and a target extract phase that are separated from each other, and the liquid inlet is located in the target extract phase and is kept apart from the interface of the adjacent phase and the solid residue. S3, with the second valve closed, open the first valve and the gas valve, and draw through the gas channel to allow a predetermined volume of the target extract phase to enter the quantitative transfer chamber through the phase selective transfer channel; when the liquid level in the quantitative transfer chamber reaches the predetermined volume mark, close the first valve and the gas valve to isolate the quantitative transfer chamber from the phase separation chamber, and retain the oil-containing phase in the phase separation chamber; S4, open the second valve and put the pressure balance channel in the exhaust state or connect it to the negative pressure source. By pressurizing, suctioning or performing a second centrifugation, drive the target extract phase in the quantitative transfer chamber to pass sequentially through the first adsorption layer, the second adsorption layer, the third adsorption layer and the filter layer along the flow direction; wherein, the first adsorption layer includes C8 bonded silica gel, the second adsorption layer includes activated magnesium silicate and partially acetylated N-propylethylenediamine bonded silica gel, the partially acetylated N-propylethylenediamine bonded silica gel is called partially acetylated PSA, and the third adsorption layer includes anhydrous sodium sulfate; S5, allowing the liquid passing through the filter layer to enter the purified liquid collection chamber to obtain the purified liquid to be tested for food testing; Steps S1 to S5 constitute a continuous purification process completed within the same integrated purification component. The target extract phase enters the composite adsorption chamber within the integrated purification component via the phase-selective transfer channel and the quantitative transfer chamber.

[0011] Furthermore, the fat content of the oil-containing complex food sample is not less than 5%, and the oil-containing complex food sample is selected from edible oil, chili sauce, chili oil, hot pot base, peanut butter, sesame paste, nut products, meat products, or combinations thereof.

[0012] Furthermore, the oil-phase inducing solvent is selected from hexane, heptane, isooctane, or a combination thereof, and the amount of the oil-phase inducing solvent added is 0.5 to 2.5 mL per gram of the oil-containing complex food sample.

[0013] Furthermore, the volume fraction of acetonitrile in the acetonitrile extract is 80%–95%, the total volume fraction of formic acid, acetic acid, or a combination thereof is 0.1%–1.0%, and the remainder is water; the amount of acetonitrile extract added is 2–6 mL per gram of the oil-containing complex food sample; for oil-containing complex food samples that require additional water dispersion, 0.3–0.8 mL of water is added to each gram of the oil-containing complex food sample and mixed before adding the oil phase inducing solvent.

[0014] Furthermore, the phase-separating salt comprises anhydrous magnesium sulfate, sodium chloride, and trisodium citrate; based on the total mass of the anhydrous magnesium sulfate, sodium chloride, and trisodium citrate being 100%, the mass percentage of the anhydrous magnesium sulfate is 65%–85%, the mass percentage of the sodium chloride is 10%–30%, and the mass percentage of the trisodium citrate is 2%–10%, and the sum of the mass percentages of the three is 100%; the total amount of the phase-separating salt added is 1.0–1.6 g per gram of the oil-containing complex food sample.

[0015] Furthermore, the mixing time after adding the phase separation salt is 30–120 s; the first centrifugation conditions in step S2 are 2000–6000 × g and 1–5 min; when step S4 is driven by the second centrifugation, the conditions for the second centrifugation are 2000–6000 × g and 1–3 min.

[0016] Furthermore, based on the total mass of the C8-bonded silica gel, activated magnesium silicate, partially acetylated PSA, and anhydrous sodium sulfate being 100%, the mass percentage of the C8-bonded silica gel is 40%–60%, the mass percentage of the activated magnesium silicate is 20%–30%, the mass percentage of the partially acetylated PSA is 10%–20%, and the mass percentage of the anhydrous sodium sulfate is 10%–20%, and the sum of the mass percentages of the four is 100%; the total amount of the four is 100–220 mg relative to each 1 mL of target extract phase entering the quantitative transfer chamber.

[0017] Furthermore, 35%–60% of the titratable surface amine groups in the partially acetylated PSA are converted into amide groups; the average particle size of the C8 bonded silica gel is 40–100 μm and the average pore size is 10–30 nm; the average particle size of the activated magnesium silicate and the partially acetylated PSA are 40–120 μm, respectively; the activated magnesium silicate is obtained by treating magnesium silicate at 130–180 °C for 2–4 h.

[0018] Furthermore, inert sieve plates with pore sizes of 10–20 μm are respectively provided between the first adsorption layer and the second adsorption layer, and between the second adsorption layer and the third adsorption layer; the pore size of the filter layer is 0.22–0.45 μm; the quantitative transfer cavity is a transparent or semi-transparent cavity and is provided with volume graduations.

[0019] Furthermore, in step S3, the volume of the target extract phase transferred to the quantitative transfer chamber is 0.5–2.0 mL, and does not exceed half of the total volume of the target extract phase obtained after phase separation; the liquid inlet is located in the middle of the liquid layer of the target extract phase, and the distance between it and the adjacent phase interface or solid residue on the upper and lower sides of the target extract phase is not less than 2 mm; in step S5, the collection volume of the purified liquid to be tested is not less than 80% of the volume of the target extract phase entering the quantitative transfer chamber. Beneficial effects

[0020] Compared with the method of using separate phase separation containers, pipetting tools and adsorption purification tubes, the present invention continuously completes phase separation, quantitative transfer of target analyte extraction phase, composite adsorption purification and purification liquid collection in the same component, which significantly reduces the external transfer of samples between different containers and significantly simplifies the purification operation process.

[0021] The liquid inlet is set within the liquid layer corresponding to the target analyte extraction, and the single transfer volume is limited by the quantitative transfer chamber. After the predetermined transfer volume is reached, the first valve isolates the quantitative transfer chamber from the phase separation chamber, which helps to reduce the possibility of oil-containing phase, aqueous phase or solid residue entering the composite adsorption chamber due to phase interface movement.

[0022] C8-bonded porous silica gel, activated magnesium silicate, partially acetylated PSA, and anhydrous sodium sulfate are layered along the liquid flow direction to separately treat residual neutral lipids, partially polar lipids, organic acids or other polar matrix interfering substances, and moisture in the target extract phase. This layered arrangement reduces the mixing of different adsorbent materials during storage and use, and ensures that the target extract phase passes through the different materials in a predetermined order.

[0023] Partially acetylated PSA reduces some of the available surface amino sites, thus achieving both the removal of polar matrix interferences and the reduction of the possibility of over-adsorption of some acidic targets.

[0024] The gas passage, gas valve, pressure balance passage, first valve and second valve work together to enable the purification method to drive liquid flow using positive pressure, negative pressure or centrifugal method, thereby improving the adaptability between different operating conditions. Attached Figure Description

[0025] Figure 1 A schematic diagram of the integrated purification component used to implement the purification method of the present invention.

[0026] Reference numerals: 10—Phase separation chamber; 11—Oil-containing phase; 12—Target extract phase; 13—Aqueous phase or solid residue; 20—Phase selective transfer channel; 21—Liquid inlet; 22—First valve; 30—Quantitative transfer chamber; 32—Gas channel; 33—Gas valve; 40—Second valve; 50—Compound adsorption chamber; 51—First adsorption layer; 52—Second adsorption layer; 53—Third adsorption layer; 54—Filter layer; 60—Purified liquid collection chamber; 61—Pressure balance channel. Detailed Implementation

[0027] To facilitate understanding by those skilled in the art, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments: In this invention, "oil-containing phase 11" refers to the liquid phase enriched with oils and oil-inducing solvent after phase separation. Oil-containing phase 11 may simultaneously contain oils, oil-inducing solvent, and other hydrophobic matrix components. "Target analyte extraction phase 12" refers to the liquid phase after phase separation, using acetonitrile as the main organic solvent and used to carry the target analyte. "Aqueous phase or solid residue 13" includes the water-rich liquid phase formed after phase separation, precipitated phase-separated salts, food solid residue, or a combination thereof. "Oil-inducing solvent" refers to a low-polarity organic solvent with high compatibility with oils and capable of forming a recognizable phase interface with the target analyte extraction phase. The oil-inducing solvent may be selected from n-hexane, n-heptane, isooctane, or a combination thereof.

[0028] After the oil-phase inducing solvent is added to the sample, it can promote the enrichment of triglycerides and other hydrophobic matrix components into the oil-containing phase 11, so that the oil-containing phase 11 and the target extract phase 12 form a recognizable phase interface, thereby helping to reduce the amount of oil entering the composite adsorption chamber 50 along with the target extract phase 12. The type and amount of oil-phase inducing solvent can be selected according to the lipophilicity and phase partition characteristics of the target analyte.

[0029] The average pore size of the C8-bonded porous silica gel described in this invention is 10–30 nm. Unless otherwise stated, the average pore size can be determined by nitrogen adsorption-desorption method, and the average particle size refers to the volume median particle size D50 measured by laser particle size analysis.

[0030] PSA is short for N-propylethylenediamine-bonded silica gel. The surface amino groups in PSA materials can interact with organic acids, some pigments, and other polar interfering substances in food matrices. Unacetylated PSA has more available amino groups, which may increase the retention of some acidic target substances while treating polar matrix interfering substances.

[0031] Acetylation treatment can reduce the basicity and interaction ability of some amino sites. Partially acetylated PSA is used to retain a certain polar matrix treatment capacity while reducing the possibility of over-adsorption of some target substances. An acetylation degree of 35%–60% is used as a preferred material parameter to adjust the balance between polar matrix treatment capacity and target substance adsorption.

[0032] The degree of acetylation of partially acetylated PSA is calculated using the following formula: D = (N0 - N1) / N0 × 100% In the formula, D represents the degree of acetylation; N0 represents the titratable surface amino group content per unit mass of PSA before acetylation; and N1 represents the titratable surface amino group content per unit mass of material after acetylation.

[0033] In this invention, the mass and mass percentage of trisodium citrate are based on anhydrous trisodium citrate. When trisodium citrate hydrate is used, its equivalent mass of anhydrous trisodium citrate is calculated according to its hydrated state. Example 1: The integrated purification component used in the purification method

[0034] like Figure 1 As shown, the integrated purification component used in implementing the method of the present invention includes a phase separation chamber 10, a phase selective transfer channel 20, a quantitative transfer chamber 30, a composite adsorption chamber 50, and a purification liquid collection chamber 60, which are arranged sequentially along the liquid flow direction and form a fluid passage.

[0035] Phase separation chamber 10 is used to contain complex food samples containing oils, oil-phase inducing solvents, acetonitrile extract, and phase separation salts. Samples and reagents can be loaded into phase separation chamber 10 through its openable end, and it remains sealed during mixing, centrifugation, and transfer. The conventional opening and closing and sealing structure used is not... Figure 1 As shown in the image.

[0036] The phase separation chamber 10 is provided with at least a transparent or semi-transparent area that allows observation of the phase interface. After mixing and the first centrifugation, an oil-containing phase 11, a target extract phase 12, and an aqueous phase or solid residue 13 are formed in the phase separation chamber 10.

[0037] One end of the phase-selective transfer channel 20 forms a liquid inlet 21. The liquid inlet 21 extends into the phase separation chamber 10 and is positioned within the height range of the target extract phase 12. The other end of the phase-selective transfer channel 20 is connected to the quantitative transfer chamber 30.

[0038] The first valve 22 is disposed on the phase selective transfer channel 20 and is used to control the opening and closing of the phase separation chamber 10 and the quantitative transfer chamber 30.

[0039] The quantitative transfer chamber 30 is a transparent or semi-transparent chamber and has graduations for indicating the volume of liquid. Figure 1 The short horizontal lines within the quantitative transfer cavity 30 represent the scale lines, but the number and spacing of the scale lines are not limited.

[0040] The quantitative transfer chamber 30 is provided with a gas channel 32, and a gas valve 33 is provided on the gas channel 32. By changing the external connection state of the gas channel 32, the quantitative transfer chamber 30 can be connected to a negative pressure source, the atmosphere, or a positive pressure gas source.

[0041] A second valve 40 is provided between the quantitative transfer chamber 30 and the composite adsorption chamber 50. The second valve 40 is used to close the liquid passage between the quantitative transfer chamber 30 and the composite adsorption chamber 50 during the process of the target extract phase 12 entering the quantitative transfer chamber 30, and to open the liquid passage after quantitative measurement and pressure balance are completed.

[0042] The composite adsorption chamber 50 is provided with a first adsorption layer 51, a second adsorption layer 52, a third adsorption layer 53 and a filter layer 54 in sequence along the flow direction of the target extract phase 12.

[0043] The first adsorption layer 51 includes C8-bonded porous silica gel with an average pore size of 10-30 nm, used to treat the residual neutral hydrophobic matrix components in the target extract phase 12.

[0044] The second adsorption layer 52 includes activated magnesium silicate and partially acetylated PSA. The partially acetylated PSA is N-propylethylenediamine-bonded silica gel that has undergone partial acetylation treatment. Activated magnesium silicate is used to treat some polar lipids, pigments, or other polar matrix components; partially acetylated PSA is used to treat some organic acids and polar matrix interfering substances, and to reduce the possibility of over-adsorption of some acidic target substances by unmodified PSA.

[0045] The third adsorption layer 53 includes anhydrous sodium sulfate, which is used to absorb some of the residual moisture in the target extract phase 12.

[0046] An inert, liquid-permeable separator can be placed between adjacent adsorption layers to limit the mixing of different adsorption materials. Figure 1 The horizontal lines between the layers indicate the separation interface, and the inert separator is not separately marked with an icon number.

[0047] The filter layer 54 is used to trap adsorbent material particles and solid particles in the sample. The pore size of the filter layer 54 can be 0.22–0.45 μm.

[0048] The purification liquid collection chamber 60 is located downstream of the filter layer 54. The purification liquid collection chamber 60 is provided with a pressure balancing channel 61. The pressure balancing channel 61 can be connected to the atmosphere to discharge gas during positive pressure or centrifugal drive; it can also be connected to a negative pressure source to draw the target extract phase 12 from downstream of the composite adsorption chamber 50.

[0049] Gas passage 32 and pressure balance passage 61 can be equipped with gas-permeable and liquid-blocking components to reduce the possibility of liquid entering the external gas path. The gas-permeable and liquid-blocking components are not located in... Figure 1 It is shown separately in the text. Example 2, Purification Method

[0050] When using the above-mentioned integrated purification component for sample purification, follow these steps.

[0051] S1, the complex food sample containing oil is placed in the phase separation chamber 10. An oil-phase inducing solvent is added and mixed, allowing the solvent to contact the oil in the sample. Then, acetonitrile extract and phase separation salt are added and mixed, distributing the oil and the target analyte to the oil-containing phase 11 and the target analyte extraction phase 12, respectively. During this process, the first valve 22, the second valve 40, and the gas path valve 33 remain closed.

[0052] S2, the resulting mixture is centrifuged for the first time to form a phase-separated system comprising at least an oil phase 11 and a target extract phase 12. For samples containing a large amount of water or solid components, an aqueous phase or solid residue 13 may also be formed. The operating conditions after phase separation should ensure that the liquid inlet 21 is within the liquid layer of the target extract phase 12 and is kept at a distance from the interfaces of adjacent phases and solid residues.

[0053] S3, with both the first valve 22 and the second valve 40 closed, the gas passage 32 is connected to the negative pressure source through the gas passage valve 33. After a negative pressure is formed in the quantitative transfer chamber 30, the first valve 22 is opened, allowing the target extract phase 12 to enter the quantitative transfer chamber 30 through the liquid inlet 21 and the phase selective transfer channel 20.

[0054] When the liquid level in the quantitative transfer chamber 30 reaches the predetermined volume scale line, the first valve 22 is closed first to isolate the phase separation chamber 10 from the quantitative transfer chamber 30; then the gas passage 32 is connected to the atmosphere to balance the pressure in the quantitative transfer chamber 30.

[0055] S4, after completing the above isolation and pressure balancing, open the second valve 40. Drive the target extract phase 12 in the quantitative transfer chamber 30 through the composite adsorption chamber 50 using any of the following methods: When using positive pressure mode, connect gas passage 32 to positive pressure gas source and put pressure balance passage 61 in the state of exhausting gas to the atmosphere; When using negative pressure mode, the gas channel 32 is connected to the atmosphere, and the pressure balance channel 61 is connected to the negative pressure source; When using centrifugation, both the gas channel 32 and the pressure balance channel 61 are connected to the atmosphere, and the integrated purification component is centrifuged.

[0056] The target extract phase 12 passes sequentially through the first adsorption layer 51, the second adsorption layer 52, the third adsorption layer 53, and the filter layer 54.

[0057] S5, the liquid passing through the filter layer 54 enters the purified liquid collection chamber 60 to obtain the purified liquid to be tested. The purified liquid to be tested can be used directly for the corresponding test, or it can be diluted, concentrated, or solvent-replaced according to the test method. Example 3, Preparation of partially acetylated PSA

[0058] Dry the PSA at 100°C for 2 hours, cool it to room temperature, and then seal and store it.

[0059] Weigh 0.500 g of dried PSA and add it to 25.00 mL of a 0.050 mol / L hydrochloric acid standard solution. The solvent for the hydrochloric acid standard solution is methanol and water in a 1:1 volume ratio. Shake at room temperature for 60 min, then filter and bring the filtrate to a final volume of 25.00 mL.

[0060] Take 5.00 mL of the filtrate and titrate it with 0.050 mol / L sodium hydroxide standard solution. Use a hydrochloric acid standard solution without PSA and treated with the same steps as a blank. Calculate the titratable surface amine content per unit mass of PSA using the following formula: N=C×(Vb-Vs)×Vt / (Va×m) In the formula: N represents the titratable surface amino group content per unit mass of material, expressed in mmol / g. C represents the concentration of the sodium hydroxide standard solution, in mol / L. Vb is the volume of sodium hydroxide standard solution consumed in the blank titration, in mL; Vs is the volume of sodium hydroxide standard solution consumed in the sample titration, in mL; Vt is the total volume of the filtrate after dilution, in mL; Va is the volume of filtrate taken during titration, in mL; m represents the mass of the material being tested, expressed in grams (g).

[0061] The titratable amount of surface amino groups measured before acetylation treatment is denoted as N0.

[0062] The PSA with determined NO was dispersed in anhydrous acetonitrile. Acetic anhydride was added at a molar ratio of 0.35:1 to 0.65:1 to titratable surface amino groups, and the mixture was stirred at 20–35 °C for 2–6 h.

[0063] After the reaction was complete, the solid material was separated and washed successively with acetonitrile and methanol. The washed solid material was then vacuum dried at 60°C to obtain acetylated PSA.

[0064] The titratable surface amino group content N1 of the treated material was determined using the same acid-base back titration method as before acetylation, and the degree of acetylation was calculated as D = (N0 - N1) / N0 × 100%. Materials with an acetylation degree between 35% and 60% were used as partially acetylated PSA.

[0065] The molar ratio of acetic anhydride is used to adjust the degree of acetylation reaction. The final degree of acetylation is determined by the titratable amount of surface amine groups before and after treatment. Example 4, Treatment of Adsorbent Material

[0066] C8-bonded porous silica gel with an average particle size of 40–100 μm and an average pore size of 10–30 nm was selected.

[0067] Magnesium silicate with an average particle size of 40–120 μm was selected, and the magnesium silicate was treated at 130–180 °C for 2–4 h. After cooling, it was sealed and stored to obtain activated magnesium silicate.

[0068] Partially acetylated PSA with an average particle size of 40–120 μm and a degree of acetylation of 35%–60% was selected.

[0069] Anhydrous sodium sulfate can be treated at 350–450°C for 1–3 hours before use and then cooled and stored in a dry environment.

[0070] Based on a total mass of 100% of C8-bonded porous silica gel, activated magnesium silicate, partially acetylated PSA, and anhydrous sodium sulfate, the following ranges shall be used for filling: C8-bonded porous silicone 40%–60%; Activated magnesium silicate 20%–30%; Partially acetylated PSA 10%–20%; Anhydrous sodium sulfate 10%–20%.

[0071] The total amount of the above four materials is 100-220 mg relative to 1 mL of target extract phase 12 in the quantitative transfer chamber 30.

[0072] Along the flow direction of the target extract phase 12, C8 bonded porous silica gel is first packed to form a first adsorption layer 51; then a homogeneous mixture of activated magnesium silicate and partially acetylated PSA is packed to form a second adsorption layer 52; subsequently, anhydrous sodium sulfate is packed to form a third adsorption layer 53; and finally, a filter layer 54 is set.

[0073] An inert, liquid-permeable separator is placed between adjacent adsorption layers. The pore size of the inert separator is 10–20 μm. After filling, the integrated purification module is sealed and stored under dry conditions to reduce the absorption of ambient moisture by anhydrous sodium sulfate and other adsorbent materials. Example 5: Procedure for handling edible oil samples

[0074] An integrated purification module with a quantitative transfer volume of 1.0 mL is used. 150 mg of composite adsorption material is filled in the composite adsorption chamber 50.

[0075] Place 2.00g of edible oil sample into phase separation chamber 10, add 3.0mL of n-heptane and mix. Then add 8.0mL of 90% acetonitrile aqueous solution containing 0.5% formic acid, followed by phase separation salt consisting of 1.8g of anhydrous magnesium sulfate, 0.5g of sodium chloride and 0.2g of trisodium citrate (calculated as anhydrous), and mix for 90s.

[0076] Centrifuge at 4000×g for 2 min to form an oil phase 11, a target extract phase 12, and a salt layer or solid residue at the bottom of the mixture. The target extract phase 12 covers the liquid inlet 21 and keeps the liquid inlet 21 spaced from the adjacent interface.

[0077] Keep the first valve 22 and the second valve 40 closed, and connect the gas passage 32 to the negative pressure source via the gas valve 33. After a negative pressure is formed in the quantitative transfer chamber 30, open the first valve 22 to transfer 1.0 mL of the target extract phase 12 into the quantitative transfer chamber 30. Once the predetermined volume is reached, close the first valve 22 first, and then connect the gas passage 32 to the atmosphere.

[0078] Open the second valve 40 to connect the gas channel 32 and the pressure balance channel 61 to the atmosphere. Centrifuge at 4000×g for 1 min to allow the target extract phase 12 to pass through the first adsorption layer 51, the second adsorption layer 52, the third adsorption layer 53 and the filter layer 54 in sequence and enter the purification liquid collection chamber 60. Example 6: Procedure for handling chili sauce samples

[0079] An integrated purification module with a quantitative transfer volume of 1.5 mL was used. 250 mg of composite adsorbent material was filled into the composite adsorption chamber 50.

[0080] Place 5.00 g of homogenized chili sauce sample in phase separation chamber 10, add 3.0 mL of water and mix to disperse the sample. Add 4.0 mL of n-heptane and 12.0 mL of 90% acetonitrile aqueous solution containing 0.5% acetic acid, then add a phase separation salt consisting of 4.0 g of anhydrous magnesium sulfate, 1.0 g of sodium chloride, and 0.5 g of trisodium citrate (calculated as anhydrous). Mix for 90 s.

[0081] Centrifuge at 4500×g for 3 min to form a phase-separated system comprising at least an oil phase 11, a target extract phase 12, and an aqueous phase or solid residue 13. The target extract phase 12 covers the liquid inlet 21, and the liquid inlet 21 is kept separate from adjacent interfaces and solid residue.

[0082] Keep the first valve 22 and the second valve 40 closed, and connect the gas passage 32 to the negative pressure source via the gas valve 33. After a negative pressure is formed in the quantitative transfer chamber 30, open the first valve 22 to transfer 1.5 mL of the target extract phase 12 into the quantitative transfer chamber 30. After the predetermined volume is reached, first close the first valve 22, and then connect the gas passage 32 to the atmosphere.

[0083] Open the second valve 40 to connect the gas channel 32 and the pressure balance channel 61 to the atmosphere. Centrifuge at 4000×g for 1 to 2 minutes to allow the target extract phase 12 to pass through the composite adsorption chamber 50 and enter the purification liquid collection chamber 60. Example 7: Operation method of hot pot base sample

[0084] An integrated purification module with a quantitative transfer volume of 1.0 mL is used. 180 mg of composite adsorption material is filled in the composite adsorption chamber 50.

[0085] Mix the hot pot base ingredients thoroughly, and place 2.00g of the sample into the phase separation chamber 10. Add 4.0mL of n-heptane and 10.0mL of 90% acetonitrile aqueous solution containing 0.5% formic acid, then add the phase separation salt consisting of 2.2g of anhydrous magnesium sulfate, 0.6g of sodium chloride, and 0.2g of trisodium citrate (calculated as anhydrous). Mix for 120s.

[0086] Centrifuge at 4000×g for 3 min to form a phase-separated system comprising at least an oil-containing phase 11 and a target extract phase 12. The target extract phase 12 covers the liquid absorption inlet 21, and the liquid absorption inlet 21 is kept at a distance from the interface of the adjacent phase or solid residue.

[0087] Keep the first valve 22 and the second valve 40 closed, and connect the gas passage 32 to the negative pressure source via the gas valve 33. After a negative pressure is formed in the quantitative transfer chamber 30, open the first valve 22 to transfer 1.0 mL of the target extract phase 12 into the quantitative transfer chamber 30. Once the predetermined volume is reached, close the first valve 22 first, and then connect the gas passage 32 to the atmosphere.

[0088] Then, the second valve 40 is opened, and under the condition that both the gas channel 32 and the pressure balance channel 61 are connected to the atmosphere, the sample is centrifuged at 4000×g for 1 to 2 minutes, so that the target extract phase 12 passes through the composite adsorption chamber 50 and enters the purification liquid collection chamber 60. Example 8, Composite Adsorption Material

[0089] In one filling method, with the total mass of the four materials being 100%, formulation A includes 55% C8-bonded porous silica gel, 22% activated magnesium silicate, 11% partially acetylated PSA, and 12% anhydrous sodium sulfate.

[0090] In another filling method, based on the total mass of the four materials as 100%, Formulation B includes 50% C8-bonded porous silica gel, 25% activated magnesium silicate, 13% partially acetylated PSA and 12% anhydrous sodium sulfate.

[0091] In another filling method, with the total mass of the four materials being 100%, formulation C includes 45% C8 bonded porous silica gel, 28% activated magnesium silicate, 12% partially acetylated PSA, and 15% anhydrous sodium sulfate.

[0092] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit the scope of protection of the present invention. Those skilled in the art can adjust, substitute, or combine the above embodiments without departing from the concept of the present invention, and the resulting technical solutions should still fall within the scope of protection of the present invention. The scope of protection of the present invention is defined by the claims.

Claims

1. An integrated purification method for oil phase separation and composite adsorption for complex food detection, characterized in that, Sample purification is performed using an integrated purification module; The integrated purification component includes a phase separation chamber, a phase selective transfer channel, a quantitative transfer chamber, a composite adsorption chamber, and a purification liquid collection chamber, which are arranged sequentially along the liquid flow direction to form a fluid passage. One end of the phase-selective transfer channel is connected to the phase separation chamber through a liquid inlet, and the other end is connected to the quantitative transfer chamber. A first valve is provided on the phase-selective transfer channel to control its opening and closing. The quantitative transfer chamber is a transparent or semi-transparent cavity with volume graduation lines. The quantitative transfer chamber is equipped with a gas channel and a gas valve for controlling the opening and closing of the gas channel. The gas channel can be selectively connected to a negative pressure source, the atmosphere, or a positive pressure gas source. A second valve is provided between the quantitative transfer chamber and the composite adsorption chamber; The composite adsorption chamber is provided with a first adsorption layer, a second adsorption layer, a third adsorption layer and a filter layer in sequence along the liquid flow direction; The first adsorption layer comprises C8-bonded porous silica gel; the second adsorption layer comprises activated magnesium silicate and partially acetylated PSA, wherein the partially acetylated PSA is N-propylethylenediamine-bonded silica gel that has undergone partial acetylation treatment; the third adsorption layer comprises anhydrous sodium sulfate. The purified liquid collection chamber is equipped with a pressure balance channel, which can be in an exhaust state or connected to a negative pressure source. The purification method includes the following steps: S1, place the oily complex food sample into the phase separation chamber, add the oil phase inducing solvent and mix, then add the acetonitrile extract and phase separation salt and mix, so that the oil and the target analyte in the sample are respectively distributed to the oil-containing phase and the acetonitrile-rich target analyte extraction phase; wherein, the first valve, the second valve and the gas path valve are all kept closed; S2, the mixture obtained in step S1 is centrifuged for the first time to form a phase-separated system that includes at least an oil-containing phase and a target extract phase that are separated from each other, so that the liquid inlet is located within the liquid layer of the target extract phase and is kept apart from the interface of the adjacent phase and the solid residue. S3, with both the first and second valves closed, the gas passage is connected to the negative pressure source via the gas valve; after a negative pressure is formed in the quantitative transfer chamber, the first valve is opened, allowing a predetermined volume of the target extract phase to enter the quantitative transfer chamber via the phase-selective transfer channel; when the liquid level in the quantitative transfer chamber reaches the predetermined volume mark, the first valve is closed first, and then the gas passage is connected to the atmosphere to balance the pressure in the quantitative transfer chamber, isolating the quantitative transfer chamber from the phase separation chamber, and retaining the oil-containing phase in the phase separation chamber; S4, open the second valve, and drive the target extract phase in the quantitative transfer chamber to flow sequentially through the first adsorption layer, the second adsorption layer, the third adsorption layer and the filter layer by positive pressure, negative pressure or centrifugation. When using a positive pressure method, the gas channel is connected to a positive pressure gas source, and the pressure balance channel is in a state of exhausting gas to the atmosphere. When using negative pressure, the gas channel is connected to the atmosphere, and the pressure balance channel is connected to the negative pressure source; When using centrifugation, both the gas passage and the pressure balance passage are connected to the atmosphere; S5, allowing the liquid passing through the filter layer to enter the purified liquid collection chamber to obtain the purified liquid to be tested for food testing; Steps S1 to S5 constitute a continuous purification process completed within the same integrated purification component. The target extract phase enters the composite adsorption chamber within the integrated purification component via the phase-selective transfer channel and the quantitative transfer chamber.

2. The method according to claim 1, characterized in that, The fat content of the complex food sample containing oil is not less than 5%, and the complex food sample containing oil is selected from edible oil, chili sauce, chili oil, hot pot base, peanut butter, sesame paste, nut products, meat products or combinations thereof.

3. The method according to claim 1, characterized in that, The oil-phase inducing solvent is selected from hexane, heptane, isooctane, or a combination thereof, and the amount of the oil-phase inducing solvent added is 0.5 to 2.5 mL per gram of the oil-containing complex food sample.

4. The method according to claim 1, characterized in that, The acetonitrile extract contains 80%–95% acetonitrile by volume, and formic acid, acetic acid, or a combination thereof contains 0.1%–1.0% by volume, with the remainder being water. The amount of acetonitrile extract added is 2–6 mL per gram of the oil-containing complex food sample. For oil-containing complex food samples that require additional water dispersion, 0.3–0.8 mL of water is added to each gram of the oil-containing complex food sample and mixed before adding the oil phase inducing solvent.

5. The method according to claim 1, characterized in that, The phase separation salt comprises anhydrous magnesium sulfate, sodium chloride, and trisodium citrate, wherein the amount of trisodium citrate used is based on anhydrous trisodium citrate; based on the total mass of the anhydrous magnesium sulfate, sodium chloride, and anhydrous trisodium citrate as 100%, the mass percentage of the anhydrous magnesium sulfate is 65%–85%, the mass percentage of the sodium chloride is 10%–30%, and the mass percentage of the anhydrous trisodium citrate is 2%–10%, and the sum of the mass percentages of the three is 100%; the total amount of the phase separation salt added is 1.0–1.6 g per gram of the oily complex food sample.

6. The method according to claim 1, characterized in that, The mixing time after adding the phase separation salt is 30-120s; the first centrifugation conditions in step S2 are 2000-6000×g for 1-5min; when centrifugation is used in step S4, the centrifugation conditions are 2000-6000×g for 1-3min.

7. The method according to claim 1, characterized in that, Based on the total mass of the C8-bonded porous silica gel, activated magnesium silicate, partially acetylated PSA, and anhydrous sodium sulfate being 100%, the mass percentage of the C8-bonded porous silica gel is 40%–60%, the mass percentage of the activated magnesium silicate is 20%–30%, the mass percentage of the partially acetylated PSA is 10%–20%, and the mass percentage of the anhydrous sodium sulfate is 10%–20%, and the sum of the mass percentages of the four is 100%; the total amount of the four is 100–220 mg relative to 1 mL of target extract phase entering the quantitative transfer chamber.

8. The method according to claim 1, characterized in that, In the partially acetylated PSA, 35%–60% of the titratable surface amine groups are converted to amide groups; the average particle size of the C8-bonded porous silica gel is 40–100 μm, and the average pore size is 10–30 nm; the average particle size of the activated magnesium silicate and the partially acetylated PSA are 40–120 μm, respectively; the activated magnesium silicate is obtained by treating magnesium silicate at 130–180 °C for 2–4 h.

9. The method according to claim 1, characterized in that, An inert, liquid-permeable separator is provided between adjacent adsorption layers, the pore size of which is 10–20 μm; the pore size of the filter layer is 0.22–0.45 μm; and the gas channel and / or the pressure balance channel are provided with a gas-permeable and liquid-blocking component.

10. The method according to claim 1, characterized in that, In step S3, the volume of the target extract phase transferred to the quantitative transfer chamber is 0.5 to 2.0 mL, and does not exceed one-half of the total volume of the target extract phase obtained after phase separation; the liquid inlet is located in the middle of the liquid layer of the target extract phase, and the distance between it and the adjacent phase interface or solid residue on the upper and lower sides of the target extract phase is not less than 2 mm; In step S5, the collection volume of the purified liquid to be tested shall not be less than 80% of the volume of the target extract phase entering the quantitative transfer chamber.

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