A pretreatment method for liquid chromatography-tandem mass spectrometry analysis of chemical contaminants in serum

Abstract

This invention belongs to the field of biological sample contaminant screening, specifically involving a pretreatment method for liquid chromatography-tandem mass spectrometry analysis of chemical contaminants in serum. The pretreatment method includes the following steps: (1) Preparation of Ti / Zr MOF: Zirconium source, 1,3,5-tris(4-carboxyphenyl)benzene, titanium source, and organic acid are placed in a container, dissolved in an aprotic polar solvent, heated to react, cooled, and the white powder product is collected by centrifugation and washing, which is Ti / Zr MOF, and dried for later use; (2) Extraction: The serum sample is mixed with acetonitrile, ultrasonically vortexed, centrifuged, and a portion of the supernatant is taken as the purification solution; (3) Purification: The purification solution in step (2) is mixed with the Ti / Zr MOF in step (1), ultrasonically vortexed, centrifuged, and the supernatant is taken to obtain the purified sample.

Description

Technical Field

[0001] This invention belongs to the field of biological sample contaminant screening, specifically relating to a pretreatment method for liquid chromatography-tandem mass spectrometry analysis of chemical contaminants in serum. Background Technology

[0002] Human biosurveillance (HBM), a core component of environmental and health risk assessment, provides information on the type, quantity, level, and spatiotemporal dynamics of individual and population exposure to chemicals and their metabolites by analyzing human samples (such as tissues, blood, and urine). Importantly, when exposure routes are diverse or sources are unknown, HBM can reflect the total level of human exposure and help elucidate its link to health effects. Therefore, ensuring that sample analysis unbiasedly reflects human exposure to chemicals is crucial. Recent advancements in high-resolution mass spectrometry have enabled simultaneous and reproducible non-targeted analysis of thousands of compounds in biological matrices.

[0003] Serum contains a rich variety of endogenous interfering substances. Other abundant lipids in serum, such as triglycerides and cholesterol esters, cause fewer problems due to their nonpolarity and low extractability in polar solvents. Phospholipids, major components of cell membranes, are abundant in biological samples. They are the main interfering substances in serum causing matrix effects. In liquid chromatography-high resolution mass spectrometry analysis, phospholipids cause strong matrix effects, masking trace and ultra-trace exogenous compounds of biological significance, making them undetectable in non-targeted screening.

[0004] Therefore, sample pretreatment is crucial for the accuracy of non-targeted workflows. It should remove interfering substances without damaging the target analyte or introducing human interference. Removing endogenous compounds from blood samples during pretreatment is an effective solution. In non-targeted monitoring of plasma or serum samples, the most common sample preparation method is protein precipitation using ice-cold methanol or acetonitrile. To further improve the sensitivity and specificity of targeted human biomonitoring, laboratories often use liquid-liquid extraction, solid-phase extraction, and materials capable of removing phospholipids or proteins to reduce ion inhibition. Although these methods can extract the most compounds, they not only use large amounts of organic solvents but also have long operation times and less than ideal purification results.

[0005] Previous patents by the inventors, CN120334437A and CN120761552A, reported methods for serum pretreatment, using MOF materials to adsorb and remove phospholipids from serum samples. However, the removal rate for some phospholipids was not high, such as SMd18:1 / 12:0 and SMd18:1 / 14:0, with removal rates between 80-85%. Because the phosphorus in these phospholipids has strong surface activity, it preferentially occupies the droplet surface during mass spectrometry electrospray ionization, competing with the target analyte for charge and space, thereby inhibiting or enhancing the ionization efficiency of the analyte. This still significantly interferes with the detection of certain trace chemical hazardous substances. Summary of the Invention

[0006] Given the technical problem that the removal rate of phospholipids in serum samples still needs improvement in existing technologies, the purpose of this invention is to provide a pretreatment method for LC-MS / MS analysis of residual chemical pollutants in serum. This invention uses a self-made Ti / Zr MOF as a phospholipid adsorbent, which exhibits excellent adsorption and removal efficiency for various phospholipids, including those with low adsorption rates from other MOFs. It can achieve deep and efficient removal of all types of phospholipids, thus enabling rapid detection of trace pesticides and veterinary drugs. The method of this invention is simple to operate, uses a small amount of organic solvent, and has good purification effect, making it widely applicable to the residual analysis of chemical pollutants in serum. Furthermore, the low cost and ease of scalability of the adsorbent material prepared in this invention facilitate industrial production. To solve the above technical problems, this invention provides the following technical solution:

[0007] A pretreatment method for liquid chromatography-tandem mass spectrometry analysis of chemical contaminants in serum includes the following steps:

[0008] (1) Preparation of Ti / Zr MOF: Zirconium source, 1,3,5-tris(4-carboxyphenyl)benzene, titanium source and organic acid are placed in a container, and a non-protic polar solvent is added to dissolve them. The reaction is heated and cooled. The white powder product is collected by centrifugation and washing, which is Ti / ZrMOF. It is then dried for later use.

[0009] (2) Extraction: Mix serum sample with acetonitrile, sonicate, centrifuge, and take part of the supernatant as the purification solution;

[0010] (3) Purification: The solution to be purified in step (2) is mixed with the Ti / Zr MOF in step (1), ultrasonically vortexed, centrifuged, and the supernatant is taken to obtain the purified sample.

[0011] Furthermore, after step (3), there is step (4): the purified sample is separated and determined by UPLC-MS / MS to obtain the removal efficiency of total phospholipids and the removal efficiency of each phospholipid.

[0012] Furthermore, after step (3), there is step (5): the purified sample is separated and determined by UPLC-MS / MS, and quantified by external standard method to test the content of chemical pollutants.

[0013] Detecting trace chemical contaminants, such as pesticides and veterinary drugs, in serum samples requires thorough removal of phospholipids; otherwise, the detection results will be severely affected. While searching for MOFs with higher adsorption and removal efficiency for phospholipids, the inventors were surprised to find that the aforementioned Ti / Zr MOF material achieved a removal rate exceeding 99% for 20 types of phospholipids—a performance not currently possessed by other MOF materials. This superior removal efficiency for all types of phospholipids can completely remove phospholipids from serum, significantly reducing the matrix effect caused by phospholipids and minimizing interference in the detection of trace chemical hazards. Furthermore, the aforementioned Ti / Zr MOF material adsorbs phospholipids from samples at a faster rate, completing the adsorption and removal of phospholipids in a shorter time.

[0014] Further, in step (1), the zirconium source is selected from at least one of zirconium chloride and zirconium nitrate; the titanium source is selected from at least one of titanium butoxide, titanium isopropoxide, tetrabutyl titanate, and tetrapropyl titanate.

[0015] Further, in step (1), the molar ratio of the total amount of zirconium source and titanium source to 1,3,5-tris(4-carboxyphenyl)benzene is 1:1.5-2.5, preferably 1:1.8-2.2, more preferably 1:1.9-2.1, and most preferably 1:1.95-2.05, such as 1:2; the amount of zirconium source and titanium source satisfies that Zr accounts for 5%-50% of the total amount of Zr and Ti, preferably 10%-25%.

[0016] Furthermore, the aprotic polar solvent is selected from at least one of N,N-dimethylformamide, N,N-diethylformamide, and N,N-dimethylacetamide; the organic acid is selected from at least one of acetic acid, formic acid, benzoic acid, and trifluoroacetic acid; the volume ratio of the organic acid to the molar ratio of 1,3,5-tris(4-carboxyphenyl)benzene is 0.2-0.5 mL: 1 mmol, for example, 0.25-0.3 mL: 1 mmol; the heating reaction is carried out at 100-140 °C for 6-12 h.

[0017] Further, in step (2), the ultrasonic vortex time is 3-10 min; the centrifugation speed is 8000-14000 rpm; the centrifugation temperature is 0-4℃; and the centrifugation time is 3-10 min.

[0018] Furthermore, in step (2), the volume ratio of serum sample to acetonitrile is 1:3-5, for example, 1:4; the shaking time is 5-20s, for example, 10-15s;

[0019] Further, in step (3), the mass-to-volume ratio of Ti / Zr MOF to the purification solution is 5-30 mg:1 mL, preferably 10-20 mg:1 mL. The ultrasonic vortexing time is 0.5-10 min; the centrifugation speed is 10000-14000 rpm; the centrifugation temperature is 0-4℃, and the centrifugation time is 5-15 min.

[0020] Further, step (4) involves monitoring the characteristic fragment ion of the phosphoric acid choline head group (precise mass number ~184.0733, C5H). 15 NO4P + The precursor ion scan (PIS) was performed at m / z=184.

[0021] Further, in step (4), the phospholipids include lysophosphatidylethanolamine (LPE), lysophosphatidylcholine (LPC), phosphatidylcholine (PC), and sphingomyelin (SM); further, the lysophosphatidylethanolamine (LPE) is selected from LPE 16:0 and LPE 18:0; the lysophosphatidylcholine (LPC) is selected from LPC 15:0, LPC 16:0, LPC 18:1, and LPC 18:0; the phosphatidylcholine (PC) is selected from PC 14:0 / 16:0, PC p-16:0 / 16:0, PC 16:0 / 16:0, PC 16:0 / 18:1, PC 16:0 / 18:0, PC p-18:0 / 18:0, PC 18:2 / 18:2, PC 18:1 / 18:1, and PC 18:0 / 18:2; the sphingomyelin (SM) is selected from SM d18:1 / 14:1, SM d18:1 / 14:0, SM d18:1 / 16:0, SM d18:1 / 18:1, and SM d18:1 / 18:0.

[0022] Through extensive experimentation, the inventors discovered that most MOFs have limited adsorption and removal performance for SM d18:1 / 12:0 and SMd18:1 / 14:0 phospholipids. However, the presence of these phospholipids does indeed affect the detection of some organic compounds. The inventors unexpectedly found that using the aforementioned Ti / Zr MOF as a phospholipid adsorbent resulted in excellent adsorption and removal performance for 20 types of phospholipids, including SM d18:1 / 12:0 and SM d18:1 / 14:0, which have low adsorption efficiency with other MOFs. However, using a single metal, replacing Zr or Ti with other metals, or replacing 1,3,5-tris(4-carboxyphenyl)benzene with other ligands could not achieve the excellent adsorption and removal performance of the obtained MOFs for all types of phospholipids.

[0023] Further, in step (4), the chromatographic column used in the ultra-high performance liquid chromatography (UHPLC) is an ACQUITY CSH C18 (2.1 mm × 100 mm, 1.7 μm); and / or the mobile phase used in the UHPLC is: 5-10 mM ammonium formate + 0.1-0.5 wt% formic acid in acetonitrile / water solution, with acetonitrile volume percentage in the acetonitrile / water solution being 40%-60% (A) and 5-10 mM ammonium formate + 0.1% formic acid in isopropanol / acetonitrile solution, with isopropanol volume percentage in the isopropanol / acetonitrile solution being 70%-90% (B); the gradient elution program is 40%-43% B (0-2.0 min), 43%-50% B (2.0-2.1 min), 50%-54% B (2.1-12.0 min), 54%-70% B (12.0-12.1 min), 70%-99% B (12.1-18.0 min), 99%-40% B (18.0-18.1 min), 40% B (18.1-20.0 min); flow rate 0.3 mL / min; column temperature 40-45℃; injection volume 3-5 μL.

[0024] Further, in step (5), for pesticides, the ultra-high performance liquid chromatography (UHPLC) uses an ACQUITY UPLC HSS T3 column (2.1 mm × 100 mm, 1.8 μm); for veterinary drugs, the UHPLC uses an ACQUITY UPLC BEH C18 column (2.1 mm × 100 mm, 1.7 μm).

[0025] Further, in step (5), for pesticides, the mobile phase used in the ultra-high performance liquid chromatography is: 2-5 mM ammonium formate + aqueous solution containing 0.01-0.1 wt% formic acid (A) and 2-5 mM ammonium formate + methanol containing 0.01-0.1 wt% formic acid (B); the gradient elution program is 3% B (0-1.0 min), 3%-15% B (1.0-1.5 min), 15%-50% B (1.5-2.5 min), 50%-70% B (2.5-18.0 min), 70%-98% B (18.0-23.0 min), 98% B (23.0-27.0 min), 98%-3% B (27.0-27.1 min), 3% B (27.1-30.0 min); the flow rate is 0.3 mL / min; the column temperature is 40°C, and the injection volume is 2 mL / min. μL. For veterinary drugs, the mobile phase used in the ultra-high performance liquid chromatography method is: 0.5-1 mM ammonium fluoride + 0.1% (v / v) formic acid water (A) and acetonitrile / methanol (v / v=1 / 1) (B); flow rate: 0.3 mL / min. The gradient elution program is as follows: 3% B (0-2.0 min), 3%-15% B (2.0-5.0 min), 15% B (5.0-10.0 min), 15%-30% B (10.0-15.0 min), 30%-50% B (15.0-20.0 min), 50%-100% B (20.0-24.0 min), 100% B (24.0-28.0 min), 100%-3% B (28.0-28.5 min), 3% B (28.5-29.0 min); the flow rate is 0.3-0.5 mL / min; the column temperature is 35-45°C, for example, 40°C; and the injection volume is 3-5 μL.

[0026] The present invention also provides the use of organometallic framework Ti / Zr MOF in adsorbing and removing phospholipids in liquid samples. The organometallic framework Ti / Zr MOF is prepared by a method including the following steps: placing zirconium source, 1,3,5-tris(4-carboxyphenyl)benzene, titanium source and organic acid in a container, adding an aprotic polar solvent to dissolve, heating to react, cooling, collecting the white powder product by centrifugation and washing, which is Ti / Zr MOF, and drying for later use.

[0027] Further, the zirconium source is selected from at least one of zirconium chloride and zirconium nitrate; the titanium source is selected from at least one of titanium butoxide, titanium isopropoxide, tetrabutyl titanate, and tetrapropyl titanate; the molar ratio of the total amount of zirconium source and titanium source to 1,3,5-tris(4-carboxyphenyl)benzene is 1:1.5-2.5, preferably 1:1.8-2.2, more preferably 1:1.9-2.1, and most preferably 1:1.95-2.05, such as 1:2; the amount of zirconium source and titanium source satisfies that Zr accounts for 5%-50% of the total amount of Zr and Ti, preferably 10%-25%; the aprotic polar solvent is selected from at least one of N,N-dimethylformamide, N,N-diethylformamide, and N,N-dimethylacetamide; the organic acid is selected from at least one of acetic acid, formic acid, benzoic acid, and trifluoroacetic acid; the heating reaction is carried out at 100-140℃ for 6-12 h.

[0028] Furthermore, the liquid sample is selected from serum; even further, the concentration of the organometallic framework Ti / Zr MOF in the liquid sample is 5-30 mg / mL, preferably 10-20 mg / mL.

[0029] Compared with the prior art, the present invention achieves the following beneficial effects:

[0030] I. This invention prepares an organometallic framework (MOF) containing Ti and Zr. Compared with other known MOFs that adsorb phospholipids in the prior art, the Ti / Zr MOF of this invention has an excellent adsorption and scavenging rate of over 99% for all types of phospholipids, and the total phospholipid removal efficiency is stable at 99.4%.

[0031] Second, the Ti / Zr MOF adsorbent of the present invention only needs to be in contact with the serum extract for 30 seconds to achieve a high scavenging rate of phospholipids and quickly reach adsorption equilibrium. The time consumption of the phospholipid adsorption step is shortened, which greatly improves the throughput of processing large batches of serum samples and makes the operation simpler and faster.

[0032] Third, this invention achieves comprehensive detection of 538 pesticides and veterinary drugs at an ultra-low spiking level of 10 μg / kg. The matrix effect factors of most pesticide and veterinary drug compounds are between 0.7 and 1.3, exhibiting only slight matrix inhibition or enhancement. This meets the non-targeted screening needs for ultra-trace pesticide and veterinary drug exposure in human serum and fills the gap in the insufficient detection capability of existing technologies for low concentrations.

[0033] Fourth, the protein precipitation and extraction steps of the present invention only require the use of pure acetonitrile, without the need for dilution with water or the addition of modifiers such as formic acid, which simplifies the reagent preparation process and avoids the additional matrix interference introduced by formic acid. Attached Figure Description

[0034] Figure 1This is a scanning electron microscope image of the Ti / Zr MOF material synthesized in Preparation Example 1.

[0035] Figure 2 This is the XRD pattern of the Ti / Zr MOF material synthesized in Example 1.

[0036] Figure 3 The N2 adsorption-desorption curves and pore size distribution of the Ti / Zr MOF material synthesized in Example 1 are shown.

[0037] Figure 4 This is a graph showing the effect of different adsorbent dosages on the total removal rate of phospholipids.

[0038] Figure 5 This is a graph showing the effect of different adsorption times on the total removal rate of phospholipids.

[0039] Figure 6 This refers to the removal rate of 20 types of phospholipids. Detailed Implementation

[0040] The following will further illustrate the above-described embodiments of the present invention with reference to specific examples. However, those skilled in the art will understand that the following examples are only for illustrating the present invention, and all technologies based on the above content of the present invention fall within the scope of the present invention.

[0041] Preparation Example 1

[0042] 9 mmol ZrCl4, 1 mmol titanium butoxide, and 20 mmol 1,3,5-tris(4-carboxyphenyl)benzene (i.e., the molar ratio of ZrCl4 titanium butoxide to 1,3,5-tris(4-carboxyphenyl)benzene is 9:1:20) were added to 5 mL acetic acid and placed in a Pierrex glass bottle. 100 mL of N,N-dimethylformamide (DMF) was added to dissolve the product. The reaction was carried out at 120 °C for 10 h. After cooling to room temperature, the product was washed several times with N,N-dimethylformamide (DMF) and acetone. The product was collected as a white powder by centrifugation and then dried under vacuum for later use.

[0043] Figure 1 This is a scanning electron microscope (SEM) image of the Ti / Zr MOF material synthesized in Preparation Example 1. It can be seen that the prepared Ti / ZrMOF exhibits a regular octahedral structure.

[0044] Figure 2 This is the XRD pattern of the Ti / Zr MOF material synthesized in Example 1. All prepared Ti / Zr MOFs exhibited distinct crystal signal peaks, with no TiO2 peak appearing, indicating successful synthesis of Ti / Zr MOFs without TiO2 formation.

[0045] Figure 3The figures show the N2 adsorption-desorption curves and pore size distribution of the Ti / Zr MOF material synthesized in Example 1. Nitrogen adsorption experiments were conducted at 77 K, and the BET specific surface area of ​​the Ti / Zr MOF was 351.21 m². 2 ·g -1 It has a mesoporous cage with a diameter of 4.1 nm.

[0046] Preparation Example 2

[0047] The other conditions and operations were the same as in Preparation Example 1, except that the molar ratio of ZrCl4, titanium butoxide, and 1,3,5-tris(4-carboxyphenyl)benzene was 7.5:2.5:20.

[0048] Preparation Example 3

[0049] The other conditions and operations were the same as in Preparation Example 1, except that the molar ratio of ZrCl4, titanium butoxide, and 1,3,5-tris(4-carboxyphenyl)benzene was 0.95:0.05:20.

[0050] Preparation Example 4

[0051] The other conditions and operations were the same as in Preparation Example 1, except that the molar ratio of ZrCl4, titanium butoxide, and 1,3,5-tris(4-carboxyphenyl)benzene was 5:5:20.

[0052] Comparative Preparation Example 1

[0053] Without the addition of ZrCl4, the molar ratio of titanium butoxide to 1,3,5-tris(4-carboxyphenyl)benzene is 1:2.

[0054] Comparative Preparation Example 2

[0055] Without the addition of titanium butoxide, the molar ratio of ZrCl4 to 1,3,5-tris(4-carboxyphenyl)benzene is 1:2.

[0056] Comparative preparation example 3

[0057] ZrCl4 was replaced with an equimolar amount of CeCl4.

[0058] Comparative preparation example 4

[0059] Titanium butoxide is replaced with an equimolar amount of tetramethoxytin.

[0060] Comparative preparation example 5

[0061] 1,3,5-tris(4-carboxyphenyl)benzene is replaced with an equimolar amount of 4,4',4'-(benzene-1,3,5-triyltris(azadiyl))tribenzoic acid (CAS: 1258012-29-1).

[0062] Comparative preparation example 6

[0063] 1,3,5-tris(4-carboxyphenyl)benzene is replaced with an equimolar amount of 2,4,6-tris(4-carboxyphenyl)-1,3,5-triazine (CAS: 61414-16-2).

[0064] Test on the effect of MOFs on phospholipid adsorption and removal:

[0065] An experiment was conducted on the MOF material prepared in Example 1 to remove phospholipids by adsorption.

[0066] The mass spectrometry parameters of the 20 phospholipids are shown in Table 1 below.

[0067] Table 1. Phospholipid spectral parameters of 20 types

[0068]

[0069] Phospholipid analytes were separated chromatographically using an ACQUITY CSH C18 column (2.1 mm × 100 mm, 1.7 μm). The mobile phases used in the ultra-high performance liquid chromatography (UHPLC) were: 10 mM ammonium formate + 0.1% formic acid in acetonitrile / water (6:4, v / v) (A) and 10 mM ammonium formate + 0.1% formic acid in isopropanol / acetonitrile (9:1, v / v) (B); the gradient elution programs were: 40%-43% B (0-2.0 min), 43%-50% B (2.0-2.1 min), 50%-54% B (2.1-12.0 min), 54%-70% B (12.0-12.1 min), 70%-99% B (12.1-18.0 min), 99%-40% B (18.0-18.1 min), and 40% B (18.1-20.0 min); the flow rate was 0.3 mL / min; the column temperature was 45°C; and the injection volume was 5 μL.

[0070] Mix 200µL of serum sample with 800µL of acetonitrile solution, vortex for 30s, sonicate for 5min, and centrifuge at 12000rpm / min at 4℃. Take a portion of the supernatant for purification.

[0071] Different amounts of Ti / Zr MOF were added to 0.5 mL of acetonitrile extract of serum samples.

[0072] The formula for calculating the removal rate is as follows:

[0073]

[0074] Peak area is the peak area of ​​the characteristic peak in the liquid chromatogram. The retention time is different for each phospholipid, as shown in Table 1.

[0075] Figure 4This is a graph showing the effect of different adsorbent dosages on the total removal rate of phospholipids. It can be seen that the phospholipid removal efficiency increases as the adsorbent dosage increases from 5 to 30 mg / mL. -1 The rate of increase was rapid during the process, and at 10 mg·mL -1 It reaches a stable state at this time, with the removal rate stabilizing at 99.40%.

[0076] Figure 5 This graph shows the effect of different adsorption times on the total removal rate of phospholipids. When the adsorbent is mixed with serum and contacted for 30 seconds, a removal efficiency of 99.26% can be achieved. Extending the contact time to 10 minutes does not lead to further improvement, indicating that the system can quickly reach adsorption equilibrium. Considering the actual operational efficiency of sample pretreatment, the adsorption time was ultimately determined to be 30 seconds for subsequent experiments. Figure 6 The removal rate of 20 phospholipids by the Ti / Zr MOF in Preparation Example 1 is shown. We were surprised to find that the Zr / TiMOF of this invention achieved a removal rate of over 99% for all 20 phospholipids, with a shorter adsorption time. This is very rare among known MOF materials that can be used to adsorb phospholipids. This confirms the highly efficient adsorption capacity of Zr / Ti MOF for phospholipids, which is beneficial for pretreatment work in the detection of trace compounds in complex matrix samples such as serum.

[0077] Table 2 shows the total phospholipid removal rate and the removal rate of SM d18:1 / 12:0 by MOF materials in the different preparation examples and the comparative preparation examples, with an adsorption time of 30 s and a MOF dosage of 10 mg·mL. -1 .

[0078] Table 2 Phospholipid Removal Rate Test

[0079]

[0080] Application examples

[0081] In the spiked recovery experiment, (1) 0.2 mL of serum sample was mixed with 0.8 mL of acetonitrile solution, and pesticides or veterinary drugs were added at a concentration of 10 µg·kg⁻¹. -1 Spike, vortex for 10s, sonicate for 5min, centrifuge at 14000rpm at 4℃ for 5min, and take 0.5mL of supernatant for purification. (2) Mix the solution to be purified obtained in step (1) with 5mg of Ti / Zr MOF prepared in Preparation Example 1, sonicate for 30s, vortex for 0.5min, and centrifuge at 10000rpm at 4℃ for 5min to obtain the test solution.

[0082] For pesticide pollutants, the ultra-high performance liquid chromatography (UHPLC) used an ACQUITY UPLC HSS T3 column (2.1 mm × 100 mm, 1.8 μm). The mobile phases used in UHPLC were: 2 mM ammonium formate + 0.01% (v / v) formic acid in water (A) and 2 mM ammonium formate + 0.01% (v / v) formic acid in methanol (B). The gradient elution program was: 3% B (0-1.0 min), 3%-15% B (1.0-1.5 min), 15%-50% B (1.5-2.5 min), 50%-70% B (2.5-18.0 min), 70%-98% B (18.0-23.0 min), 98% B (23.0-27.0 min), 98%-3% B (27.0-27.1 min), and 3% B (27.1-30.0 min). The flow rate was 0.3 mL / min; the column temperature was 40°C; and the injection volume was 2 μL.

[0083] For veterinary drug contaminants, the mobile phase used in ultra-high performance liquid chromatography is: 0.5 mM ammonium fluoride + 0.1% (v / v) formic acid water (A) and acetonitrile / methanol (v / v=1 / 1) (B); flow rate: 0.3 mL / min. The gradient elution program was 3% B (0-2.0 min), 3%-15% B (2.0-5.0 min), 15% B (5.0-10.0 min), 15%-30% B (10.0-15.0 min), 30%-50% B (15.0-20.0 min), 50%-100% B (20.0-24.0 min), 100% B (24.0-28.0 min), 100%-3% B (28.0-28.5 min), and 3% B (28.5-29.0 min); the flow rate was 0.3 mL / min; the column temperature was 40℃; and the injection volume was 3 μL.

[0084] Mass spectrometry analysis was performed using a Waters Xevo TQ-XS triple quadrupole mass spectrometer, operated in multiple reaction monitoring (MRM) mode. Key parameters are as follows: ion source: electrospray ionization (ESI); ionization mode: positive ion mode; ion source temperature: 400℃.

[0085] The pesticides with serial numbers 1-356 and veterinary drugs with serial numbers 357-538 in Table 3 were tested according to the above procedure. The results are shown in Table 3 below.

[0086] Table 3 Analysis of pesticide and veterinary drug detection

[0087]

Claims

1. A pretreatment method for liquid chromatography-tandem mass spectrometry analysis of chemical contaminants in serum, characterized in that, Includes the following steps: (1) Place zirconium source, 1,3,5-tris(4-carboxyphenyl)benzene, titanium source, and organic acid in a container, add an aprotic polar solvent to dissolve, heat to react, cool, and collect the white powder product by centrifugation and washing. This product is Ti / Zr MOF, which is then dried for later use. The molar ratio of the total amount of zirconium and titanium sources to 1,3,5-tris(4-carboxyphenyl)benzene is 1:1.8-2.

2. The amount of zirconium and titanium sources used should satisfy the requirement that Zr accounts for 10%-25% of the total amount of Zr and Ti. (2) Extraction: Mix serum sample with acetonitrile, sonicate, centrifuge, and take part of the supernatant as the purification solution; (3) Purification: The solution to be purified in step (2) is mixed with the Ti / Zr MOF in step (1), ultrasonically vortexed, centrifuged, and the supernatant is taken to obtain the purified sample.

2. The pretreatment method according to claim 1, characterized in that, After step (3), there is step (4): the purified sample is separated and determined by UPLC-MS / MS to obtain the removal efficiency of total phospholipids and the removal efficiency of each phospholipid.

3. The pretreatment method according to claim 1, characterized in that, After step (3), there is step (5): the purified sample is separated and determined by UPLC-MS / MS, and the content of chemical pollutants is tested by external standard method.

4. The pretreatment method according to claim 1, characterized in that, In step (1), the zirconium source is selected from at least one of zirconium chloride and zirconium nitrate; the titanium source is selected from at least one of titanium butoxide, titanium isopropoxide, tetrabutyl titanate, and tetrapropyl titanate.

5. The pretreatment method according to claim 1, characterized in that, The aprotic polar solvent is selected from at least one of N,N-dimethylformamide, N,N-diethylformamide, and N,N-dimethylacetamide; the organic acid is selected from at least one of acetic acid, formic acid, benzoic acid, and trifluoroacetic acid; the volume ratio of the organic acid to the molar ratio of 1,3,5-tris(4-carboxyphenyl)benzene is 0.2-0.5 mL: 1 mmol; the heating reaction is carried out at 100-140 °C for 6-12 h.

6. The pretreatment method according to claim 1, characterized in that, In step (2), the ultrasonic vortexing time is 3-10 min; the centrifugation speed is 8000-14000 rpm; the centrifugation temperature is 0-4℃; the centrifugation time is 3-10 min; the volume ratio of serum sample to acetonitrile is 1:3-5; the shaking time is 5-20 s; and / or, In step (3), the mass-to-volume ratio of Ti / Zr MOF to the purification solution is 5-30 mg: 1 mL, the ultrasonic vortex time is 0.5-10 min, the centrifugation speed is 10000-14000 rpm, the centrifugation temperature is 0-4℃, and the centrifugation time is 5-15 min.

7. The pretreatment method according to claim 2, characterized in that, Step (4), phospholipids include lysophosphatidylethanolamine, lysophosphatidylcholine, phosphatidylcholine, and sphingomyelin.

8. The pretreatment method according to claim 7, characterized in that, The lysophosphatidylethanolamine is selected from LPE16:0 and LPE18:0; the lysophosphatidylcholine is selected from LPC15:0, LPC16:0, LPC18:1, and LPC18:0; the phosphatidylcholine is selected from PC14:0 / 16:0, PC p -16:0 / 16:0, PC 16:0 / 16:0, PC 16:0 / 18:1, PC 16:0 / 18:0, PC p -18:0 / 18:0, PC 18:2 / 18:2, PC 18:1 / 18:1, PC 18:0 / 18:2; the sphingomyelin is selected from SMd18:1 / 14:1, SM d18:1 / 14:0, SM d18:1 / 16:0, SM d18:1 / 18:1, SM d18:1 / 18:

0.

9. The application of organometallic frameworks (Ti / Zr MOFs) in the adsorption and removal of phospholipids in liquid-phase samples, characterized in that... The organometallic framework Ti / Zr MOF is prepared by a method including the following steps: zirconium source, 1,3,5-tris(4-carboxyphenyl)benzene, titanium source, and organic acid are placed in a container, dissolved in an aprotic polar solvent, heated to react, cooled, and the white powder product is collected by centrifugation and washing, which is Ti / Zr MOF, and dried for later use. The zirconium source is selected from at least one of zirconium chloride and zirconium nitrate; the titanium source is selected from at least one of titanium butoxide, titanium isopropoxide, tetrabutyl titanate, and tetrapropyl titanate; the molar ratio of the total amount of zirconium source and titanium source to 1,3,5-tris(4-carboxyphenyl)benzene is 1:1.8-2.2; the amount of zirconium source and titanium source used satisfies that Zr accounts for 10-25% of the total amount of Zr and Ti.

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