Method for determining xanthate compound in soil

Abstract

The invention belongs to the technical field of pollutant determination, and relates to a method for determining xanthate compounds in soil, which comprises the following steps: S1, freeze-drying soil to be determined, grinding, sieving, adding an extracting agent, oscillating and centrifuging, and taking supernate; adding a purifying agent into the supernate for dispersive solid-phase extraction, centrifuging, filtering the supernate, taking filtrate, and adjusting the pH value for later measurement; and S2, determining the content of the xanthate compound in the filtrate by adopting a high performance liquid chromatography-tandem mass spectrometry method. The method is high in recovery rate, good in precision, high in sensitivity, resistant to complex matrix interference and suitable for simultaneous determination of different xanthate compounds (ethyl xanthate EtX), (isopropyl xanthate IpX) and (butyl xanthate and BuX) in soil with different physicochemical properties, and the method has the advantages of high sensitivity, high sensitivity, high accuracy and the like. The method is suitable for the simultaneous determination of different xanthate compounds (ethyl xanthate EtX), (isopropyl xanthate IpX) and (butyl xanthate and BuX) in soil with different physicochemical properties. And an efficient solution is provided for research on pollution characteristics and risk levels of xanthate compounds in complex soil.

Description

Technical Field

[0001] This invention relates to the field of soil pollutant detection technology, and more specifically, to a method for determining xanthate compounds in soil. Background Technology

[0002] Xanthates are a class of sulfur-containing organic compounds widely used in mining flotation processes as flotation collectors, separating target minerals by adsorption onto the mineral surface. However, their extensive use leads to residual xanthates entering the surrounding soil environment through wastewater discharge and tailings accumulation. Studies have shown that xanthates readily decompose in soil into toxic byproducts such as carbon disulfide and alcohols, significantly inhibiting soil microbial activity, nitrogen cycling, and crop growth, and even threatening human health through the food chain. For example, ethyl xanthate (EtX) and isopropyl xanthate (IpX) have been shown to inhibit the growth and activity of *Thiobacillus ferrooxidans*, with the inhibitory effect on the strain gradually increasing with increasing dosage. Research has found that xanthate compounds at a concentration of 30 μg / L significantly interfere with the embryonic development of salmonid fish and have teratogenic effects on grass carp embryos and eggs. Therefore, xanthate compounds are considered biological teratogens. Butyl xanthate (BuX), due to its stronger hydrophobicity, is more likely to remain persistently in the soil and migrate into the groundwater system.

[0003] Xanthate compounds can accumulate in soil or aquatic organisms and be amplified through the food chain, posing potential hazards to humans. Long-term exposure may lead to the accumulation of toxins in organisms, affecting their growth, reproduction, and survival. Xanthate compounds are also effective inhibitors and selective inactivators of some mammalian cytochrome CYP isomers (i.e., rat CYP2B1 and human CYP2B6). After binding to enzymes (inhibiting enzymes), xanthate compounds catalyze their conversion into active intermediates that are covalently bound to and inactivated by the enzyme molecule. When injected into rats at a concentration of 1 mg / kg, the thrombin content in the body decreased; at a concentration of 10 mg / kg, reflexive activity was impaired. Quantitative structure-activity relationship analysis results showed that the inactivation efficacy of xanthate compounds is related to their chemical structure; xanthate compounds with longer alkyl chains or more branched chains have higher inactivation efficacy. Furthermore, under slightly acidic conditions, they can decompose to release neurotoxic carbon disulfide. Carbon disulfide can enter the brain through the bloodstream, causing neurological symptoms.

[0004] More importantly, the current exceedance rate of soil pollution sites in mining areas exceeds 33.4%, and the usage of flotation reagents continues to increase. Their residues can damage soil structure, inhibit microbial activity (such as nitrifying bacteria), and may threaten human health through crop accumulation. However, xanthate readily binds to organic matter and metal ions in soil, and existing analytical methods are severely affected by sulfur-containing compounds, making accurate trace-level determination difficult. This has led to a significant lag in research on related environmental behavior and ecological risks. Therefore, there is an urgent need to establish reliable and efficient analytical methods to accurately assess pollution levels, reveal the environmental fate of organic flotation reagents, and effectively manage their risks in soil ecosystems, thereby ensuring ecological safety and human health. Summary of the Invention

[0005] This invention provides a method for determining xanthate compounds in soil, based on DSPE-HPLC / MS-MS, which simplifies sample preparation by omitting the cumbersome SPE procedure and enables the simultaneous extraction and determination of three xanthates in soil.

[0006] In a first aspect, the present invention provides a method for determining xanthate compounds in soil, comprising the following steps: S1. After freeze-drying the soil to be tested, grind and sieve it, add the extractant, shake and centrifuge, and take the supernatant; add the purifying agent to the supernatant for dispersion solid-phase extraction, centrifuge, filter the supernatant, take the filtrate, and adjust the pH for testing. S2. The content of xanthate compounds in the filtrate was determined by high performance liquid chromatography-tandem mass spectrometry.

[0007] Preferably, the extractant is at least one of methanol, acetonitrile, water, and ammonia, and the purifying agent is C. 18 At least one of graphite carbon black and N-propylethylenediamine.

[0008] Preferably, the extractant is a mixture of ammonia and methanol, and the amount of extractant added is 30% to 50%; the extractant is a mixture of methanol and ammonia, and the volume ratio of ammonia to methanol is 30 to 40: 70 to 100, and the extractant is subjected to ultrasonic extraction 2 to 4 times.

[0009] Preferably, the amount of the purifying agent added is 5~10 mg / mL.

[0010] Preferably, the oscillation conditions are: a rotation speed of 2500~3500 rpm and an oscillation time of 8~15 min; the centrifugation conditions are: a rotation speed of 6000~8000 rpm and a centrifugation time of 10~20 min.

[0011] Preferably, the filter membrane material used in the filtration process is selected from at least one of PTFE, PES, PA and GHP; the pore size of the filter membrane is 0.22 μm.

[0012] Preferably, the pH is 6.5 to 11; formic acid is added to adjust the pH.

[0013] Preferably, high performance liquid chromatography-tandem mass spectrometry (HPLC-MS / MS) is used, wherein the chromatographic conditions are as follows: HPH-C18 column is used as the chromatographic column, mobile phase A is methanol solution and mobile phase B is ammonia solution; the injection volume is 5-8 μL, the column flow rate is 300-400 μL / min, and the gradient elution program is as follows: initially use 100% mobile phase B and maintain for 1-1.5 min, reduce to 0% mobile phase B and maintain for 2.9-3 min at 1.1-1.5 min, restore to 100% mobile phase B at 4.1-4.5 min, the target pollutant is eluted within 5 min, and the total run time is 10-12 min; The mass spectrometry conditions were as follows: a negative ESI source was used as the ionization source, and the operating conditions and parameters of the ESI were as follows: spray voltage was -4500 V, curtain gas pressure was 30 psi, nebulizer gas pressure was 60 psi, drying gas temperature was 500 ℃, and the monitoring mode was multiple reaction monitoring.

[0014] Preferably, the xanthate compound is at least one selected from ethyl xanthate, isopropyl xanthate, and butyl xanthate.

[0015] Preferably, the detection limit of the xanthate compound is 0.05~0.72 μg / kg, and the spiked recovery rate is 73.2%~104.9%.

[0016] In summary, the present invention has the following beneficial effects: The extraction solvents selected in this invention are methanol, acetonitrile, water, and ammonia. These solvents are chosen because they are highly polar compounds, relatively stable under alkaline conditions, and readily hydrolyzed, thus matching the physicochemical properties of xanthates. Xanthates (such as ROCSS-Na⁺) ​​are highly polar or even ionic compounds, poorly soluble in nonpolar organic solvents (such as n-hexane and dichloromethane), but readily soluble in water and polar organic solvents. Methanol, acetonitrile, and water are all highly polar solvents, effectively dissolving and extracting xanthates from soil. Extraction efficiency using water alone may be limited by soil adsorption; adding methanol or acetonitrile can disrupt hydrogen bonds or electrostatic interactions between the target compound and soil particles, improving recovery rates. Ammonia further provides an alkaline environment, inhibiting xanthate hydrolysis. Ammonia maintains the extraction system in an alkaline state, significantly inhibiting hydrolysis and preserving the integrity of the target compound. Compared to toxic solvents such as chloroform and benzene, methanol, acetonitrile, water, and ammonia have lower toxicity, better meeting laboratory safety and environmental protection requirements, and are particularly suitable for screening large batches of soil samples.

[0017] 2. The purifying agent in this invention is C. 18Graphite carbon black and N-propylethylenediamine effectively remove key interfering substances such as lipids, organic acids, pigments, and metal ions from soil while maximally retaining polar and unstable xanthates, further achieving high recovery rates and low limits of detection. 18 It is a nonpolar adsorbent, primarily removing hydrophobic interfering substances such as lipids, sterols, nonpolar pigments, and long-chain fatty acids. Xanthates are strongly polar / ionic compounds, and in C... 18 The upper retention is very weak, and it is almost not adsorbed, resulting in high recovery rate and effectively reducing the pollution of MS by organic matter in the soil. This further protects the chromatographic column and ion source, extending the instrument's lifespan. Graphite black is a strong adsorbent for planar impurities, particularly adept at removing pigments, sterols, and some polycyclic aromatic hydrocarbons. Graphite black has strong adsorption for planar molecules or conjugated structures, while xanthates (ROCSS⁻) have a certain degree of planarity and can be partially adsorbed, leading to a decrease in recovery rate. However, if the dosage is properly controlled, it can minimize the loss of target substances while removing pigments. In soil samples, if pigment interference is not severe, it can be added in a low proportion or used selectively. N-propylethylenediamine is a weak anion exchanger and polar adsorbent, mainly removing organic acids (such as fatty acids and phenolic acids), sugars, amino acids, some pigments, and metal ions (through chelation). Soil often contains a large amount of organic acids and metal ions (such as Fe³⁺ and Cu²⁺), which can catalyze the decomposition of xanthates into CS₂. N-propylethylenediamine can chelate metal ions and neutralize acidic substances, thereby indirectly stabilizing xanthates. At the same time, N-propylethylenediamine has a weak adsorption on xanthates themselves, and has little impact on the recovery rate.

[0018] 3. The method of this invention has the advantages of high efficiency and strong anti-interference ability, and is suitable for xanthate detection in complex soil matrices to meet the needs of accurate monitoring of soil pollution in mining areas. The entire process is protected by alkaline conditions, solving the problem of easy degradation of xanthates.

[0019] 4. The method of the present invention has high recovery rate, good precision, high sensitivity, and is resistant to interference from complex matrices. It is suitable for the simultaneous determination of ethyl xanthate, isopropyl xanthate and butyl xanthate in soils with different physicochemical properties.

[0020] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit the scope of protection of the present invention. Attached Figure Description

[0021] Figure 1 This invention relates to the effect of different extractants on the extraction recovery rate of target xanthium in different organic soils, (a) soil organic matter content is 33.1 g / kg, (b) soil organic matter content is 6.38 g / kg.

[0022] Figure 2This invention relates to the effect of different ammonia-water ratios on the extraction recovery rate of the target xanthate in different organic soils, (a) with soil organic matter content of 33.1 g / kg and (b) with soil organic matter content of 6.38 g / kg.

[0023] Figure 3 This invention relates to the effects of different extractant dosages and extraction times on the extraction recovery rate of the target xanthium in different organic soils, (a) with soil organic matter content of 33.1 g / kg and (b) with soil organic matter content of 6.38 g / kg.

[0024] Figure 4 This invention relates to the effect of different purifying agents on the extraction and recovery rate of target xanthate in different organic soils, (a) soil organic matter content is 33.1 g / kg, (b) soil organic matter content is 6.38 g / kg.

[0025] Figure 5 This invention relates to the effect of different filter membrane materials on the recovery rate of three xanthates.

[0026] Figure 6 The recovery rates of three xanthates under different pH conditions of this invention are shown. Detailed Implementation

[0027] The present invention will be further described in detail below with reference to the embodiments. It should be noted that: unless otherwise specified, the conditions in the following embodiments are carried out according to conventional conditions or the conditions recommended by the manufacturer. Unless otherwise specified, the raw materials used in the following embodiments can be obtained from commercially available sources.

[0028] Experimental instruments and equipment Table 1 Experimental Instruments Experimental instruments model Purchase manufacturer Electronic balance S1-234 Denver Instrument Germany Oven 101-3AB Tianjin Tester Instruments Co., Ltd. High-speed centrifugal chiller 3K15 Sigma Medical ultrasonic cleaner SB25-12DTS Ningbo Xinyi Ultrasonic Equipment Co., Ltd. freeze dryer LGJ-18C Beijing Sihuan Instrument Factory Co., Ltd. High performance liquid chromatography-mass spectrometry Q-Trap3200 Waters Vortex mixer IKA MS3 Shanghai Jingke Multi-tube vortex oscillator UMV-1 Beijing Yousheng United Technology Co., Ltd. pH meter E-201-pH Composite Electrode Leici Soil sample pretreatment: Five soil samples with different physicochemical properties were collected from the top 0-20 cm soil layer in different regions of China (Jiangxi, Xinxiang, Wuhan, Xining, and Yangzhou). The collected soil samples were homogenized, freeze-dried, ground through a 20-mesh sieve, placed in polyethylene bags, and labeled as S1-S5, and stored in a refrigerator at 4°C away from light for later use.

[0029] The target compound was not detected in any of the five soil samples mentioned above. These samples were used for subsequent method optimization and validation. Their physicochemical properties are shown in Table 2 below. Table 2 Soil physicochemical properties

[0030] Note: 1) OM represents organic matter content (g / kg); 2) CEC represents cation exchange capacity (cmol / kg) Example

[0031] Example 1

[0032] A method for determining xanthate compounds in soil includes the following steps: S1. Sample preparation: Freeze, dry, grind and mix the collected soil samples; S2. Sample extraction and purification: Take 10 g of freeze-dried soil sample into a 50 mL polypropylene centrifuge tube, add 4 mL of 30% ammonia-methanol solution, shake (2500 rpm) for 8 min, centrifuge at 8000 rpm for 10 min, take the supernatant into a 10 mL polypropylene centrifuge tube, repeat the above operation once, combine the supernatants, add 50 mg of C18 purification agent, vortex for 1 min, centrifuge at 8000 rpm for 10 min, take 1 mL and filter through a 0.22 μm PES membrane, add 5 μL of formic acid to adjust the pH to 10.5 for analysis.

[0033] S3. Sample Determination: The pretreated sample from step S2 was determined using high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS-MS). Chromatographic conditions: injection volume was 5 μL, and the analytical column was an HPH-C18 column (2.1 mm × 50 mm, id, 2.7 μm, Agilent). The mobile phase consisted of (A) methanol and (B) ammonia (pH=10.5). In the gradient elution program, mobile phase (b) started at 100% and lasted for 1 min, rapidly decreased to 0% at 1.1 (lasting 2.9 min), and then recovered to 100% at 4.1 min (lasting 4.9 min). All target contaminants were eluted within 5 min, with a total run time of 10 min and a flow rate of 300 μL / min. Mass spectrometry conditions: a negative ESI source was selected as the ionization source. The ESI operating conditions and parameters are as follows: 4500 V spray voltage (IS), curtain gas pressure = 30 psi, high impact gas, atomizing gas (Gas 1) pressure = 60 psi, dryer (Gas 2) pressure = 55 psi, dryer temperature 500 °C. The scanning mode is multiple reaction monitoring (MRM), as shown in Table 3.

[0034] Table 3. Mass spectrometric parameters of three xanthate compounds detected by LC-MS / MS compound Retention time Qualitative ions Quantitative ions Declustering voltage Collision voltage EtX 0.55 121.1 / 44.9 121.1 / 42.8 -20 -19 IpX 0.64 135.1 / 58.8 135.1 / 56.7 -65 -17 BuX 1.03 148.7 / 72.9 148.7 / 70.9 -25 -14 Example 2 The difference from Example 1 is that the extractant is water.

[0035] Example 3 The difference from Example 1 is that the extractant is acetonitrile.

[0036] Example 4 The difference from Example 1 is that the extractant is a mixture of acetonitrile and ammonia in a volume ratio of 30:70.

[0037] Example 5 The difference from Example 1 is that the extractant is methanol.

[0038] Example 6 The difference from Example 1 is that the volume ratio of ammonia to methanol in the extractant is 90:10.

[0039] Example 7 The difference from Example 1 is that the purifying agent is graphite carbon black.

[0040] Example 8 The difference from Example 1 is that the purifying agent is N-propylethylenediamine.

[0041] Test results: Five soil samples with different physicochemical properties (collected from different regions of China: Jiangxi, Xinxiang, Wuhan, Xining and Yangzhou) were used as test samples, and recovery experiments were conducted at different concentration levels (10 and 100 µg / kg).

[0042] like Figure 1 As shown in Examples 1 and 2-5, different extractants exhibit varying extraction efficiencies for the target xanthate in soils with different organic matter contents (OM values ​​of 6.38 and 33.1 g / kg, respectively). Among the extractants, ammonia-methanol (MeOH-NH3·H2O, 90:10, v / v) demonstrates the highest extraction efficiency, achieving recoveries of 40.8-58.8% for the target xanthate in soils with different organic matter content, with a standard deviation (RSD) < 2%. Other extractants generally show recoveries below 20%. This is related to the fact that MeOH-NH3·H2O can disrupt organic matter adsorption and promote the dissolution of the target substance through a polar-alkaline synergistic effect, while other solvents suffer from low efficiency due to a lack of pH adjustment or insufficient polarity. Therefore, this method uses MeOH-NH3·H2O as the extractant.

[0043] Depend on Figure 2 As shown in Examples 1 and 6, the highest recovery rate was observed when the ammonia concentration was 30%: 45%–55% in high-organic-matter soils and 60%–80% in low-organic-matter soils, significantly superior to other concentrations. Low ammonia concentrations (<30%) resulted in insufficient elution capacity, leading to a lower recovery rate, while high concentrations (>30%) caused pH increases that led to the degradation of the target compound, also limiting extraction efficiency. Furthermore, the recovery rate was generally lower in high-organic-matter soils than in low-organic-matter soils, indicating that soil organic matter adsorption reduces the extraction efficiency of the extractant for the target compound. Therefore, a 30% ammonia concentration MeOH-NH3·H2O was chosen.

[0044] Depend on Figure 3 It was found that, under the same dosage, increasing the number of extraction cycles significantly improved the recovery rate of the target compound, but further increasing the extraction time did not significantly improve the extraction efficiency. Compared with 5 + 5 mL (8 min / cycle) of extractant, 4 + 4 mL of extractant (8 min / cycle) achieved satisfactory recovery rates of the target compound in both types of soil (80% ~ 100%, RSD ≤ 3%). Longer extraction times and larger extractant volumes may lead to over-extraction, increasing the content of co-extracted impurities and resulting in a more pronounced matrix effect, thus affecting the extraction efficiency. Therefore, this method selected an extractant volume of 4 + 4 mL and a single extraction time of 8 min.

[0045] Depend on Figure 4 It can be seen from Examples 1 and 7-8 that: C 18 The purification effect on different target compounds in soil was optimal, with a target compound recovery rate of 80%–100% (RSD <3%), significantly better than GCB and PSA. Compared with C18, the other two purification adsorbents, GCB and PSA, had lower removal efficiency for soil matrix components, especially for soils with high organic matter content, with a target compound recovery rate of 55%–75% (RSD < 3%). This may be because C18, an octadecyl-bonded silica adsorbent, has good adsorption and removal of hydrophobic substances; GCB, a graphitized carbon black adsorbent, has good adsorption and removal of substances containing benzene rings, such as chlorophyll and carotenoids; and PSA, an N-propylethylenediamine adsorbent, has good ion exchange performance and good purification effect on polar organic acids and polar pigments, including sugars and fatty acids.

[0046] Depend on Figure 5 It was found that, after filtering blank spiked samples with GHP or PTFE membranes, the losses of ethyl xanthate and butyl xanthate were relatively small (recovery ≥90%, RSD < 2%), while the loss of isopropyl xanthate was relatively large (recovery ≤85%, RSD < 2%). When using PA membranes, the recoveries of all three xanthates (<75%) were low, significantly affecting the determination of the three target compounds. When using PES membranes, satisfactory performance was observed for all three xanthates, with recoveries ≥95% and RSD < 0.5%. Therefore, polyethersulfone (PES) membranes were selected for subsequent studies.

[0047] Depend on Figure 6It can be seen that when the pH value increases to 6.5, the recovery rate increases significantly, and the recovery rate of all three target compounds reaches 100%. As the pH value of the water sample further increases, the recovery rate of the target compounds does not change significantly, but an abnormal increase (105%~120%) occurs when pH ≥ 9.5. Therefore, adjusting the pH of the water sample to 6.5 is beneficial to the determination of the three xanthate compounds.

[0048] (1) Preparation of standard curves for target xanthate compounds in various soils: Working solutions of target xanthate compounds at a series of concentrations (10, 20, 50, 100, 500, 1000 μg / L) were prepared using 30% ammonia-methanol solution for solvent standard curves. Working solutions of target xanthate compounds at a series of concentrations (10, 20, 50, 100, 500, 1000 μg / L) were prepared using different soil matrix extracts (obtained by optimized extraction methods) for matrix standard curves. The above working solutions were determined by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS / MS), and standard curves were plotted with xanthate mass concentration as the abscissa and corresponding peak area as the ordinate. The linear range of the method was evaluated by linear regression analysis, and the limit of detection was determined based on a signal-to-noise ratio of 3 (S / N = 3).

[0049] (2) Validation of the selectivity of the target xanthate compounds: Different soil samples were taken and subjected to the process described in Example 1 to obtain soil extraction matrices. The target xanthate compound standard stock solution was diluted with the matrix extract to prepare matrix spiked samples. Chromatographic separation and determination were performed by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS / MS). The selectivity was determined based on the retention time of the target compound and the degree of matrix interference under the characteristic m / z conditions in the obtained chromatograms. The chromatograms of the blank matrix and the spiked samples were compared to confirm that no matrix interference peaks existed within the retention time window of the target compound. Experimental data showed that the peaks of the target compound were symmetrical and well separated in all matrices, indicating that this method has high selectivity.

[0050] (4) Validation of the recovery rate and precision of the target xanthate compound: Different types of soil samples were taken and the standard stock solution of the target xanthate compound was added to them respectively to obtain soil samples with different concentrations of spiked (10, 100 μg / L). After pretreatment according to the method in Example 1, the samples were determined by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS / MS) and quantitative analysis was performed by external standard method. The recovery rate was obtained by comparing the measured concentration of the spiked sample with its spiked concentration. The precision was expressed by the relative standard deviation of the measured values ​​of the spiked sample with the same concentration (5 parallel samples were set up for the same concentration).

[0051] As shown in Table 4, the target xanthate compound exhibits good linearity (R0) in the concentration range of 10–1000 μg / L.2 > 0.998). In the solvent, the detection limits for the three target compounds were 0.02–0.45 μg / kg; in the five soil matrix solutions, the detection limits for the target compounds were 0.05–0.72 µg / kg. This demonstrates that the method described in this invention can determine the content of various complex soil matrices. Furthermore, no interfering peaks were detected in the solvent and matrix blank samples under the characteristic m / z conditions of the target compound retention time, indicating that the established method has high selectivity.

[0052] Table 4. Standard curves and detection limits of different xanthate compounds in solvent and matrix solutions.

[0053] Table 5 shows that the accuracy and precision of the established method for extracting target xanthate compounds from five soils with different physicochemical properties were evaluated through spiked recovery experiments at different concentration levels (10 and 100 µg / kg). The results showed that the recoveries of the target xanthate compounds in the soil samples at different concentrations (10 and 100 µg / kg) ranged from 73.2% to 104.9%, with relative standard deviations (RSDs) less than 8%. These results meet the requirements of the EU pesticide residue analysis quality control procedure (DG SANCO / 12459 / 2011) (recovery rate 70%–120%, RSD less than 20%). This indicates that the optimized pretreatment method established in Example 1 is capable of handling complex matrices, has good applicability in different soil samples, and demonstrates high accuracy and precision for the analysis of target xanthates.

[0054] Table 5. Spiking recoveries (n=5) and relative standard deviations (RSD, %) of three xanthate compounds in five soils with different physicochemical properties. 100 94.7 4.5 5.5 90.6 2.2 3.0 81.6 0.6 0.8 Note: 1) Intraday precision variation; 2) Inter-day precision variation To verify the feasibility of the method of this invention, the content of xanthate compounds in soil samples collected from the vicinity of typical mineral processing sites (Tongren Mining Area in Guizhou Province and Dabaoshan Mining Area in Shaoguan, Guangdong Province) was determined using this method. The sample analysis was carried out according to the specific procedure of Example 1, and the samples analyzed included the actual samples and their spiked control samples (10 μg / kg). The results are shown in Tables 6 and 7. The recoveries of the actual samples were 60%–86.5%, with a standard deviation of <15%. This result is slightly lower than the requirements of the EU pesticide residue analysis quality control procedure (DG SANCO / 12459 / 2011) (70–20%), but is acceptable for the analysis of xanthates in complex actual samples. Xanthate compounds were detected to varying degrees in all actual samples. In the Guangdong mining area, ethyl xanthate (EtX) was dominant, with the total concentration of the three xanthates ranging from 22.9 to 78.6 μg / kg. EtX had the highest content (9.7–59.3 μg / kg), significantly higher than the other two xanthates, indicating that ethyl xanthate-type flotation reagents are mainly used in the current mineral processing activities in this mining area. In contrast, the total xanthate concentration range in the abandoned mining area of ​​Guizhou was wider (0.7–61.36 μg / kg), but isopropyl xanthate (IpX) and butyl xanthate (BuX) were dominant at most sites. Furthermore, the BuX concentration exhibited significant spatial differentiation, indicating that the spatial distribution of historical pollution sources dominated the diffusion and decay pattern of residual xanthate. This embodiment demonstrates the high feasibility and practical applicability of the method described in this invention.

[0056] Table 6. Spiked recoveries of xanthate in soil samples from actual mining areas (10 μg / kg)

[0057] Table 7. Xanthate concentration in actual samples from the mining area Sample EtX IpX BuX sum <![CDATA[G1 1) ]]> - 0.58±0.02 0.12±0.07 0.7 G2 - 0.97±0.4 - 0.97 G3 - 0.49±0.03 - 0.49 G4 - 0.54±0.08 0.24±0.07 0.78 G5 - - 3.08±0.19 3.08 G6 - - 5.74±0.64 5.74 G7 - - 8.52±0.20 8.52 G8 - - 29.68±3.36 29.68 G9 - - 31.00±3.56 31 G10 - - 33.68±1.84 33.68 G11 - - 39.20±4.40 39.20 G12 - - 61.36±4.48 61.36 <![CDATA[D1 2) ]]> 31.3±1.8 4.9±0.02 7.2±0.27 43.4 D2 11.0±0.2 6.0±0.23 7.4±0.33 23.4 D3 11.8±0.33 6.5±0.11 14.4±0.86 32.7 D4 14.4±0.02 12.2±0.02 12.1±0.02 38.7 D5 10.9±0.54 5.2±0.61 6.9±0.35 23 D6 10.6±0.02 5.1±0.02 7.2±0.02 22.9 D7 9.7±0.73 5.7±0.27 7.5±0.5 22.9 D8 12.9±0.67 5.3±0.09 6.7±0.04 24.9 D9 14.8±0.10 8.5±0.02 7.5±0.5 30.8 D10 33.2±0.42 16.9±0.53 7.8±0.32 57.9 D11 41.8±1.36 13.9±0.2 7.4±0.15 63.1 D12 59.3±1.08 9.6±0.67 9.7±0.81 78.6 1) Soil samples G1-G12 were taken from the Tongren mining area in Guizhou Province; 2) Soil samples D1-D12 were taken from the Dabao Mountain mining area in Guangdong Province. In summary, this invention provides a highly efficient analytical method for the simultaneous determination of three xanthate compounds in soil. The method uses an ammonia-methanol mixed solvent as the extractant and employs a multiple extraction method (4 + 4 mL extractant, 8 min / extraction), utilizing dispersion solid-phase extraction to determine the xanthate compounds in soil. 18 The adsorbent-purified extract was analyzed using high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS / MS). A series of gradient standard curves were constructed using crop substrates, and quantification was performed using the external standard method. This method is reliable, precise, highly sensitive, and resistant to interference from complex substrates, providing a reliable analytical approach for studying the pollution characteristics and risk levels of xanthate compounds in complex soils.

[0058] The above description is merely an exemplary embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for determining xanthate compounds in soil, characterized in that, Includes the following steps: S1. After freeze-drying the soil to be tested, grind and sieve it, add the extractant, shake and centrifuge, and then take the supernatant. Add a purifying agent to the supernatant for dispersion solid-phase extraction, centrifuge, filter the supernatant, take the filtrate, adjust the pH for testing; S2. The content of xanthate compounds in the filtrate was determined by high performance liquid chromatography-tandem mass spectrometry.

2. The method for determining xanthate compounds in soil according to claim 1, characterized in that, The extractant is at least one of methanol, acetonitrile, water, and ammonia water, and the purifying agent is C. 18 At least one of graphite carbon black and N-propylethylenediamine.

3. The method for determining xanthate compounds in soil according to claim 1, characterized in that, The extractant is a mixture of ammonia and methanol, and the amount of extractant added is 30% to 50%; the extractant is a mixture of methanol and ammonia, and the volume ratio of ammonia to methanol is 30 to 40: 70 to 100, and the extractant is ultrasonically extracted 2 to 4 times.

4. The method for determining xanthate compounds in soil according to claim 1, characterized in that, The amount of the purifying agent added is 5~10 mg / mL.

5. The method for determining xanthate compounds in soil according to claim 1, characterized in that, The oscillation conditions are: a rotation speed of 2500~3500 rpm and an oscillation time of 8~15 min; the centrifugation conditions are: a rotation speed of 6000~8000 rpm and a centrifugation time of 10~20 min.

6. The method for determining xanthate compounds in soil according to claim 1, characterized in that, The filter membrane material used in the filtration process is selected from at least one of PTFE, PES, PA and GHP; the pore size of the filter membrane is 0.22 μm.

7. The method for determining xanthate compounds in soil according to claim 1, characterized in that, The pH is 6.5-11; formic acid is added to adjust the pH.

8. The method for determining xanthate compounds in soil according to claim 1, characterized in that, High-performance liquid chromatography-tandem mass spectrometry (HPLC-MS / MS) was employed. The chromatographic conditions were as follows: an HPH-C18 column was used; mobile phase A was methanol solution and mobile phase B was ammonia solution; the injection volume was 5–8 μL; the column flow rate was 300–400 μL / min; and the gradient elution program was as follows: initially using 100% mobile phase B for 1–1.5 min, then reducing to 0% mobile phase B for 1.1–1.5 min and maintaining for 2.9–3 min, then restoring to 100% mobile phase B for 4.1–4.5 min, with the target pollutant eluted within 5 min. The total run time was 10–12 min. The mass spectrometry conditions were as follows: a negative ESI source was used as the ionization source, and the operating conditions and parameters of the ESI were as follows: spray voltage was -4500V, curtain gas pressure was 30 psi, nebulizer gas pressure was 60 psi, drying gas temperature was 500 ℃, and the monitoring mode was multiple reaction monitoring.

9. The method for determining xanthate compounds in soil according to claim 1, characterized in that, The xanthate compound is at least one of ethyl xanthate, isopropyl xanthate, and butyl xanthate.

10. The method for determining xanthate compounds in soil according to claim 1, characterized in that, The detection limits for the xanthate compounds were 0.05–0.72 μg / kg, and the recoveries were 73.2%–104.9%.

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