Method for detecting psychotropic drugs in environmental sludge based on acid pretreatment and application

Abstract

The application provides a method for detecting psychotropic drugs in environmental sludge based on acid pretreatment, which comprises the following steps: S1: obtaining a sludge sample to be detected, performing pressurized fluid extraction on the sludge sample to be detected after freeze-drying to obtain an extraction solution, performing solid-phase extraction on the extraction solution to obtain an eluate, and redissolving the eluate to obtain a solution to be detected, wherein the pressurized fluid extraction is performed under the condition of 5 ‰ formic acid water without heating; and S2: performing liquid chromatography mass spectrometry on the solution to be detected to obtain a mass spectrum, wherein the psychotropic drug is one of eptazocine, codeine, AMP, MAMP, MDA, monoacetylmorphine, MDMA, PMMA, fentanyl, norfentanyl, ketamine, norfentanyl, benzoyl eptazocine, cocaine and tramadol, and the method realizes detection of multiple psychotropic drugs in environmental sludge.

Description

Technical Field

[0001] This application relates to the field of drug detection, and in particular to a method and application for detecting psychotropic drugs in environmental sludge based on acidic pretreatment conditions. Background Technology

[0002] In recent years, with the escalation of global drug manufacturing, trafficking, and abuse, psychotropic drugs have been continuously released into the environment, posing potential harm to the ecological environment and human health. The production process of psychotropic drugs often discharges harmful chemicals and wastewater containing various toxic components such as heavy metals, acid and alkali solutions, and organic solvents, which can directly pollute soil, water sources, and air.

[0003] Due to the illegality and low prevalence of drug abuse, traditional drug abuse investigation methods struggle to obtain accurate data. Current practices typically involve testing wastewater for psychotropic drugs, with less focus on the long-term residues and cumulative effects of drug use in sludge, particularly drug components deposited in sludge generated during wastewater treatment. In reality, drugs and their metabolites in wastewater flow rapidly and are diluted, while substances excreted by drug users eventually accumulate in sludge produced during wastewater treatment. Sludge, as a solid deposit in wastewater, can preserve drug use records over a long period. Furthermore, the high fluidity of wastewater means that wastewater testing often reflects the entire wastewater treatment area, making it difficult to pinpoint specific neighborhoods or blocks. However, sludge is relatively stable and contains a large amount of metabolites from human-consumed drugs. By analyzing drug residues in municipal sludge, combined with information such as human metabolic rates, it is possible to infer the usage of these drugs and the health and usage habits of relevant populations. Detecting psychotropic drugs in sludge can more objectively, quickly, and accurately reflect drug abuse behavior in the local population.

[0004] Of course, there are still many ways to test human urine for drugs. In this case, the drug is excreted in the urine after being metabolized by the human body. Usually, the concentration of drug residues in urine is relatively high. After extracting and separating the urine and performing derivatization treatment, it is relatively easy to detect the residual drugs. However, when human urine enters the sewage collection system and is mixed with municipal sludge, the drug residues in it are usually diluted hundreds or even thousands of times, and the concentration is usually only at the nanogram level. Therefore, it is more difficult to analyze drug residues from sludge than from urine. Moreover, sludge contains a more complex matrix than sewage. The high content of organic matter, microorganisms and inorganic particles interferes with the extraction and detection of psychotropic drugs.

[0005] In conclusion, there is currently a lack of highly sensitive detection methods for psychotropic drugs in sludge. Summary of the Invention

[0006] This application provides a method and application for the detection of psychotropic drugs in environmental sludge based on acidic pretreatment. By combining pressure extraction, solid-phase extraction and triple quadrupole tandem mass spectrometry, rapid and accurate detection of psychotropic drugs in environmental sludge can be achieved.

[0007] To achieve the above objectives, this technical solution provides a method for detecting psychotropic drugs in environmental sludge based on acidic pretreatment, comprising the following steps:

[0008] S1: Obtain the sludge sample to be tested, freeze-dry the sludge sample to be tested, and then perform pressurized fluid extraction to obtain the extract. Perform solid-phase extraction on the extract and then elute to obtain the eluent. Redissolve the eluent to obtain the solution to be tested. The pressurized fluid extraction conditions are 5‰ formic acid water and no heating.

[0009] S2: The solution to be tested is subjected to liquid chromatography-mass spectrometry to obtain a mass spectrum. Based on the mass-to-charge ratio of the base peak of the mass spectrum, it is determined whether the current sludge sample to be tested contains psychotropic drugs. The chromatographic conditions are: mobile phase A is methanol, mobile phase B is 0.1% formic acid water, gradient elution; the psychotropic drugs are one or more of the following: cotinine, codeine, AMP, MAMP, MDA, monoacetylmorphine, MDMA, PMMA, fluoroquinolone, normethamidophenone, ketamine, norfentanyl, benzoylecone, cocaine, and tramadol.

[0010] It should be noted that traditional methods for detecting psychotropic drugs in wastewater do not require pressurized fluid extraction; most methods directly perform solid-phase extraction or large-volume online solid-phase extraction. This method, however, detects psychotropic drugs in sludge. Compared to the wastewater environment, sludge samples have a more complex matrix and lower concentrations of psychotropic drugs. This is because sludge is composed of various components such as water, microorganisms, organic matter, and inorganic particles. Its complex matrix may lead to strong adsorption and masking of target compounds. Furthermore, some psychotropic drugs in sludge may be partially degraded or absorbed by microorganisms. Therefore, this method performs pressurized fluid extraction on the sludge sample before solid-phase extraction, and the conditions for pressurized fluid extraction have been optimized.

[0011] The reagents tested in this protocol, including cotinine, codeine, AMP, MAMP, MDA, monoacetylmorphine, MDMA, PMMA, fluoroquinolone, normethonone, ketamine, norfentanyl, benzoylecone, cocaine, and tramadol, are suitable for acid-based pretreatment. In step S1, the pretreatment of the sludge sample to be tested is performed as follows:

[0012] In some embodiments, the sludge sample to be tested is placed in a low-temperature environment and frozen for a period of time, and then the frozen sludge sample is dehydrated and dried.

[0013] In pressurized fluid extraction of psychotropic drugs from sludge, the moisture content of the sludge sample significantly affects the absolute recovery rate of the deuterated internal standard of psychotropic drugs in the extract. Generally, the higher the moisture content of the sludge sample, the lower the absolute recovery rate of the deuterated internal standard of psychotropic drugs. This is because water has a high surface tension, making it more difficult for the extract to penetrate the interparticle spaces. Furthermore, the moisture in the sample dilutes the extract, altering its pH and affecting the extraction efficiency. Therefore, this method requires freeze-drying the sludge sample to ensure that the moisture content is below 5%. Preferably, the moisture content of the freeze-dried sludge sample is controlled to be below 1%.

[0014] This method controls the moisture content of the sludge sample for fluid extraction by freeze-drying. However, due to the volatility of psychotropic drugs, the longer the freeze-drying time, the greater the loss of the target psychotropic drug. Conversely, insufficient freeze-drying time leads to high moisture content in the sludge, reducing extraction efficiency. In this embodiment, the freeze-drying time is set to be greater than 2 hours. Specifically, the sludge sample is pre-frozen in a -50°C high-low temperature chamber for 2 hours, and then dehydrated using a vacuum freeze dryer for 2 hours.

[0015] This method involves pressurized fluid extraction of freeze-dried sludge to obtain the extract. Compared to QuEChERS extraction and purification and shake extraction, pressurized fluid extraction is the most effective method for extracting psychotropic drugs. Due to the large variety of psychotropic drugs and their significant differences in physicochemical properties, many of which are easily degraded under environmental conditions and have properties between volatile and semi-volatile, overall extraction is challenging. After validating different extraction methods, this method found that QuEChERS was not ideal for extracting psychotropic drugs, with the absolute recovery rate of the internal standard generally below 10%. Shaking extraction also showed very low overall spiked recovery rates for psychotropic drugs, and in some cases, some target substances could not be extracted.

[0016] QuEChERS is commonly used for extracting pesticide residues from food and agricultural products, achieving rapid purification through salting out and phase separation techniques. However, for compounds like psychotropic drugs, their physicochemical properties differ significantly from pesticides, making them unsuitable for QuEChERS' standard extraction solvents and conditions. Furthermore, the QuEChERS method cannot effectively release and stabilize psychotropic drugs when processing such sludge, resulting in a large amount of these drugs failing to be extracted or being destroyed during processing. While oscillatory extraction typically relies on solvent soaking and mechanical stirring to promote the dissolution and transfer of the target compound, this method is insufficient to break the strong interactions within the solid phase, especially for psychotropic drugs that are easily degraded in the environment and whose physicochemical properties fall between volatile and semi-volatile. Therefore, this scheme selects pressurized fluid extraction to extract psychotropic drugs from the sludge sample. By selecting a suitable solvent, it is possible to more effectively penetrate the solid matrix, increase the solubility of the target compound, and thus improve extraction efficiency.

[0017] In some embodiments, the pressurized fluid extraction is performed under conditions of 5‰ formic acid water without heating, and the cycle is repeated 3 times.

[0018] In this embodiment of the scheme, the freeze-dried sludge sample to be tested is placed in an extraction tank containing the extraction solution for pressurized fluid extraction. Considering that this scheme is for extracting psychotropic drugs, which have certain instability, easy degradation and strong volatility, the pressurized fluid extraction condition is set to be non-heating in order to reduce the impact on psychotropic drugs.

[0019] Furthermore, the extractant used in pressurized fluid extraction has a significant impact on the extraction efficiency. Different drugs exhibit significant differences in solubility, acidity, alkalinity, and other physicochemical properties. Therefore, this protocol requires selecting the most suitable extractant, which is 5‰ formic acid aqueous solution. This is because most of these psychotropic narcotic drugs are weakly alkaline, and using an aqueous solution containing trace amounts of formic acid as the extractant yields the best extraction results. 5‰ formic acid aqueous solution can maintain the stability of the target compound in the sample to a certain extent, preventing chemical transformation or decomposition due to pH changes during extraction, especially for compounds that are more stable under acidic conditions, such as cotinine, codeine, and ketamine. The 5‰ concentration ensures sufficient polarity for target analyte extraction while avoiding excessively high organic solvent ratios that could weaken the interaction between the extraction solvent and the matrix (sludge), thus affecting extraction efficiency. The selection of 5‰ formic acid aqueous solution also considers its good compatibility with the mobile phase (methanol and 0.1% formic acid aqueous solution) in liquid chromatography-mass spectrometry, which helps improve the continuity and stability of the analysis and reduces baseline fluctuations or signal suppression caused by solvent effects.

[0020] This method involves obtaining an extract through pressurized fluid extraction, followed by solid-phase extraction and elution to obtain an eluent. In this embodiment, the extract is injected into an activated solid-phase extraction column, the column is rinsed with pure water, and then the column is pneumatically pushed to dryness. Subsequently, the solid-phase extraction column is eluted with methanol to obtain the eluent.

[0021] Because the content of psychotropic drugs in environmental sludge is extremely low and the matrix is ​​very complex, this scheme combines solid-phase extraction (SPE) with liquid chromatography-tandem mass spectrometry (LC-MS / MS) to effectively improve the efficiency of drug extraction and detection, achieving high sensitivity and speed. This ensures detection sensitivity, reduces matrix interference, and enables screening of drugs in sludge. In this embodiment, Poly-Sery HLB Pro is selected as the SPE column. Considering that Poly-Sery HLB Pro solid-phase extractant has good retention and recovery capabilities for compounds with a wide range of polarities, it can effectively adsorb and retain these target compounds of different polarities, improving extraction efficiency and recovery rate. Furthermore, its chemical stability and mechanical strength ensure good performance even under repeated use and high-pressure conditions.

[0022] In some embodiments, the solid-phase extraction column is activated with methanol at a flow rate of no more than 1 mL / min, and then rinsed with pure water to obtain an activated solid-phase extraction column. The extract is added to the activated solid-phase extraction column at a flow rate of 4 mL / min, and the solid-phase extraction column is rinsed with pure water at a flow rate of 2 mL / min. Subsequently, the solid-phase extraction column is eluted with methanol at a flow rate of no more than 1 mL / min to obtain an eluent.

[0023] It should be noted that the flow rate during solid-phase extraction (SPE) affects the extraction results. This protocol sets the extraction solution to be added to the activated SPE column at a flow rate of 4 mL / min. The aim is to rapidly and effectively transfer psychotropic drugs from the extractant to the SPE column while minimizing drug retention or loss before the column. For samples containing large amounts of matrix or solvent, a moderately high flow rate helps reduce column pressure and accelerate processing, but it must be ensured that adsorbed impurities or target substances are not washed away. A lower elution flow rate helps to more thoroughly remove non-specifically adsorbed impurities, such as salts, pigments, and small molecule interfering substances, while maintaining the adsorption of psychotropic drugs on the column. Activating the SPE column with methanol at a flow rate not exceeding 1 mL / min helps ensure sufficient contact and wetting of all adsorbent surfaces, allowing the SPE column to reach its optimal adsorption state. A methanol elution flow rate not exceeding 1 mL / min also facilitates the efficient release of psychotropic drugs adsorbed on the SPE column. A slow flow rate ensures a gentler elution process, allowing sufficient time for the targeted psychotropic drugs to desorb from the adsorbent and be completely eluted. At the same time, it reduces column pressure, maintains the stability of the eluent, and avoids incomplete elution or uneven dispersion of the eluent due to excessively fast flow rates.

[0024] In some embodiments, the eluent is concentrated by nitrogen blowing and then injected with 20% methanol-water to obtain the test solution. In a specific embodiment, nitrogen gas is turned on at 40°C to concentrate the eluent to near dryness until fine liquid pits appear on the surface of the eluent, and then the volume is adjusted with 20% methanol-water to obtain the test solution.

[0025] In the detection step of the sludge sample to be tested in step S2:

[0026] This method involves injecting the test solution into a liquid chromatograph for separation, using mass spectrometry for detection, observing the separation of each psychotropic drug on the chromatographic column to determine gradient elution conditions, obtaining the mass-to-charge ratio (m / z) information of the quasi-molecular ions in the primary mass spectrometry of each psychotropic drug, determining the retention time of each component, and using the quasi-molecular ions of each psychotropic drug as the parent ions for optimization of the secondary mass spectrometry, optimizing the fragmentation voltage and collision energy to obtain the corresponding daughter ions generated by the fragmentation of each parent ion.

[0027] In this embodiment, a triple quadrupole LC-MS / MS system was selected, with an ACQUITY UPLC HSS T3 (2.1×100mm×1.8μm) column chosen. The triple quadrupole LC-MS / MS system was specifically chosen because its two-stage mass screening (selection of precursor and daughter ions) significantly reduces background interference and dramatically improves detection sensitivity and specificity. This is crucial for trace analysis, especially for detecting psychotropic drugs in sludge samples with complex matrices. The ACQUITY UPLC HSS T3 (2.1×100mm×1.8μm) column was chosen because the HSS T3 column is suitable for separating polar compounds; its 1.8-micron particle size reduces the diffusion path and improves separation efficiency, making it particularly suitable for the rapid and efficient separation of target analytes in complex samples. It provides clean chromatographic peaks for mass spectrometry analysis. Compared to traditional HPLC, UPLC (ultra-high performance liquid chromatography) offers faster separation speeds and higher column efficiency, significantly shortening the analysis cycle and increasing laboratory throughput.

[0028] In some embodiments, the elution conditions for gradient elution, where mobile phase A is methanol and mobile phase B is 0.1% formic acid water, are shown in Table 1 below:

[0029] Table 1 Elution Conditions

[0030]

[0031] In some embodiments, the injection volume is 5.0 μL; column temperature: 40 °C; flow rate: 0.4 ml / min.

[0032] In some embodiments, the mass spectrometry conditions are set as follows: electrospray ionization (ESI); ion source temperature: 550°C; detection method: multiple reaction monitoring (MRM); scanning method: positive / negative ion scanning.

[0033] In addition, it should be noted that the method for detecting psychotropic drugs in environmental sludge based on acidic pretreatment provided in this scheme can not only qualitatively detect psychotropic drugs, but also quantitatively detect psychotropic drugs through the internal standard method, in which case the internal standard is the deuterated isotope internal standard of each psychotropic drug.

[0034] It should be noted that, in this study, when the deuterated isotope internal standard and psychotropic drugs are present individually, the absolute recovery rates of the deuterated internal standard and the target substance do not change significantly after treatment when the deuterated isotope internal standard and psychotropic drugs are present simultaneously. This indicates that there is no "hydrogen-deuterium exchange" reaction in the environmental sludge, so the deuterated isotope internal standard can be selected as the quantitative internal standard.

[0035] Secondly, this solution provides an application of the method for detecting psychotropic drugs in environmental sludge based on acidic pretreatment mentioned in the first aspect, and applies it to the detection of psychotropic drugs in environmental sludge.

[0036] This method, by detecting psychotropic drugs in environmental sludge, can promptly and accurately reflect local consumption levels. The detection method offers advantages such as convenient sampling and analysis, low time consumption, low cost, and strong objectivity. It can accurately reflect the actual consumption of different psychotropic drugs, reflecting short-term consumption trends such as daily changes in consumption within small communities. Furthermore, it can determine the consumption status of psychotropic drugs and predict their usage trends, making it suitable for large-scale investigations into drug prevalence and abuse.

[0037] Compared with existing technologies, this technical solution has the following characteristics and beneficial effects:

[0038] This scheme integrates pressurized fluid extraction and solid-phase extraction, employing acidic pretreatment to extract psychotropic drugs from environmental sludge. It further utilizes high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS / MS) for efficient detection of psychotropic drugs in sludge. Furthermore, this scheme optimizes the extraction conditions for both pressurized fluid extraction and solid-phase extraction to achieve the best extraction results for psychotropic drugs. Through testing actual sludge samples, it establishes a method for detecting common psychotropic drugs in environmental sludge, enabling rapid and accurate quantitative detection of the samples. This provides technical support to public security departments and makes a significant contribution to improving the drug enforcement and prevention system. Attached Figure Description

[0039] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0040] Figure 1 This is a schematic diagram showing the results of the absolute recovery rate of internal standards for psychotropic drugs extracted by pressurized fluid extraction at different extraction temperatures.

[0041] Figure 2 This is a schematic diagram showing the results of the absolute recovery rate of internal standards for psychotropic drugs at different times of extraction.

[0042] Figure 3 This is a schematic diagram showing the results of the absolute recovery rate of internal standards for psychotropic drugs with different environmental sludge moisture content.

[0043] Figure 4 and Figure 5 This is the standard chromatogram for the detection of psychotropic drugs in environmental sludge according to this scheme. Detailed Implementation

[0044] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numerals in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with one or more embodiments of this specification. Rather, they are merely examples of apparatuses and methods consistent with some aspects of one or more embodiments of this specification as detailed in the appended claims.

[0045] To determine the optimal extraction conditions for psychotropic drugs according to this protocol, the experiment was designed to determine the optimal extraction conditions by spiked recovery rate.

[0046] The reagents selected for this protocol are: methanol: chromatographic grade; freshly prepared ultrapure water; formic acid: analytical grade; psychotropic narcotic drug standards and internal standard standards;

[0047] Main instruments selected: Triple quadrupole liquid chromatography-mass spectrometry (LC-MS / MS) system with electrospray ionization (ESI) source; chromatographic column: ACQUITYUPLC HSS T3, 2.1×100mm×1.8μm; freeze dryer; pressurized fluid extractor; nitrogen blower; rotary evaporator; vortex mixer; parallel concentrator; fully automated solid-phase extraction system; balance: sensitivity 0.1mg and 0.01g; general laboratory instruments and equipment;

[0048] Example 1

[0049] Select standard and deuterated internal standard of psychotropic narcotic drugs such as cotinine, codeine, AMP, MAMP, MDA, monoacetylmorphine, MDMA, PMMA, fluoroquinolone, normethamidophenone, ketamine, norfentanyl, benzoylecone, cocaine, and tramadol;

[0050] 10g of blank sludge containing a known concentration of deuterated internal standard, a psychotropic drug, was placed in an aluminum box as a sample. The sample was pre-frozen in a -50℃ high and low temperature test chamber for 2 hours, and then dehydrated and dried using a vacuum freeze dryer for 2 hours. The freeze-dried sample was transferred to an extraction cell, and the parameters of the pressurized fluid extraction apparatus were set as follows: 5‰ formic acid water, extraction temperature: none or 40℃, number of cycles: 3, to obtain the sample extract. A Poly-Sery HLB Pro SPECartridge (60mg, 3mL) solid-phase extraction column was fixed on the solid-phase extraction device, and 6mL of methanol was added to activate the solid-phase extraction column at a flow rate of 1mL / min by adjusting the flow rate control valve. Then, 6mL of ultrapure water was added to rinse the solid-phase extraction column. All of the sample extract was added to the activated Poly-Sery HLB Pro SPECartridge. In a Cartridge (60 mg, 3 mL) solid-phase extraction column, the column was eluted at a flow rate of 4 mL / min, followed by rinsing with 4 mL of pure water at a flow rate of 2 mL / min. The column was then purged with gas until dry, and the eluent was discarded. The column was then eluted with 6 mL of methanol at a flow rate not exceeding 1 mL / min. The eluent was collected and concentrated under nitrogen at 40°C until fine puddles appeared on the solvent surface. The purified eluent was then concentrated to near dryness by nitrogen blowing and brought to a final volume of 250 μL with 20% methanol-water mixture. After mixing and filtration, the solution was analyzed.

[0051] The elution conditions for gradient elution of the mobile phase in the triple quadrupole LC-MS / MS system are set as shown in Table 1 below. Elution injection volume: 5.0 μL; column temperature: 40℃; flow rate: 0.4 ml / min.

[0052] Table 1 Elution Conditions

[0053] Time / min Water (0.1% formic acid) / % Methanol / % 0 100 0 0.5 100 0 3 90 10 6 78 22 7.5 30 70 10 5 95 13 5 95 13.1 100 0 15 100 0 .

[0054] Mass spectrometry conditions set: electrospray ionization (ESI); ion source temperature: 550℃; detection mode: multiple reaction monitoring (MRM); scanning mode: positive / negative ion scanning.

[0055] Results Analysis: This experiment used 40℃ and no heating to extract various toxic residues from sludge, and the absolute recovery rate of the internal standard was used as the indicator. The results are as follows: Figure 1 As shown, by Figure 1 As can be seen, temperature has little effect on the extraction effect. Therefore, during extraction, a lower extraction tank temperature should be selected as much as possible without affecting the extraction efficiency. Ultimately, the extraction tank was not heated.

[0056] Example 2

[0057] Similar to Example 1, the difference is that the parameters of the pressurized fluid extractor are set as follows: 5‰ formic acid water; or 1‰ formic acid water, or neutral water; extraction temperature: none; number of cycles: 3.

[0058] Results Analysis: This experiment used 5‰ formic acid solution, 1‰ formic acid solution, or neutral water to extract various toxic residues from sludge. The absolute recovery rate of the internal standard was used as the indicator for testing, and the results are as follows: Figure 2 As shown in Figure 2, the extraction effect of 5‰ formic acid solution is the best.

[0059] Example 3

[0060] Take 10g of dried sludge, add different volumes of ultrapure water to prepare sludge samples with water contents of 0%, 5%, 10% and 20%, and then add a deuterated internal standard containing a known concentration of psychotropic drug. The subsequent steps are carried out in the same manner as in Example 1.

[0061] Results Analysis: In this experiment, samples with moisture contents of 0%, 5%, 10%, and 20% were selected for extraction of various drug residues. The absolute recovery rate of the internal standard was used as the indicator for testing, and the results are as follows: Figure 3 As shown, by Figure 3 It can be seen that the extraction effect of psychotropic drugs is best when the water content of the sample is less than 5%.

[0062] Example 4

[0063] Other conditions are the same as in Example 1, except that: the parameters of the pressurized fluid extractor are set as follows: 5‰ formic acid water, extraction temperature: none, number of cycles: 3, and sludge mixed with psychotropic narcotic drug standards such as cotinine, codeine, AMP, MAMP, MDA, monoacetylmorphine, MDMA, PMMA, fluoroquinolone, normethamidophenone, ketamine, norfentanyl, benzoylecone, cocaine, and tramadol are selected for instrument testing.

[0064] Results Analysis: The mass spectrum obtained in this embodiment is as follows: Figure 4 and Figure 5 As shown, by Figure 4 and Figure 5 It is known that this method can simultaneously detect cotinine, codeine, AMP, MAMP, MDA, monoacetylmorphine, MDMA, PMMA, fluoroquinolone, normethamidophenone, ketamine, norfentanyl, benzoylecone, cocaine, and tramadol.

[0065] Example 5

[0066] Other conditions were the same as in Example 1, except that the parameters of the pressurized fluid extractor were set as follows: 5‰ formic acid water, extraction temperature: none, number of cycles: 3, and standard solutions containing 10 ng / mL of the corresponding internal standard of psychotropic drugs were selected at concentrations of 0.10, 0.20, 0.40, 1.00, 5.00, 10.0, 20.0 and 50.0 ng / mL, with cotinine as an artificial marker, and its concentration was 100 times that of the other mixed standards.

[0067] Results analysis: In this experiment, a standard curve was plotted using the measurement results corresponding to the peak area ratio of the internal standard at different concentrations of the same psychotropic narcotic drug. The correlation coefficient r of the standard curve ranged from 0.9967 to 0.9999. The results of the peak area ratio are shown in Table 2 below:

[0068] Table 2. Peak area ratio results for different concentrations of psychotropic drugs.

[0069]

[0070] Example 6

[0071] Other conditions are the same as in Example 1, except that the parameters of the pressurized fluid extractor are set as follows: 5‰ formic acid water, extraction temperature: none, number of cycles: 3, and a sludge sample with a concentration of 10 ng / kg corresponding to the internal standard of psychotropic drugs is selected for full-process determination.

[0072] Results Analysis: The limit of detection (LOD) for psychotropic narcotic drugs was 10 ng / kg, and the limit of quantitation (LOQ) was 40 ng / kg. The results of the method LOD and LOQ are shown in Table 3 below.

[0073] Table 3. Limits of Detection and Limits of Quantification by Method

[0074]

[0075] Example 7

[0076] Other conditions were the same as in Example 1, except that the parameters of the pressurized fluid extractor were set as follows: 5‰ formic acid water, extraction temperature: none, number of cycles: 3, and sludge samples with three different concentrations of 25 ng / kg (cotinine 2500 ng / kg), 250 ng / kg (cotinine 25000 ng / kg), and 1000 ng / kg (cotinine 100000 ng / kg) were selected for full-process determination.

[0077] Results Analysis: The relative deviation of precision ranged from 0.8% to 13.2%. The precision test results are shown in Table 4 below. Table 4: Precision Test Results

[0078]

[0079]

[0080] Example 8

[0081] Other conditions are the same as in Example 1, except that the parameters of the pressurized fluid extractor are set as follows: 5‰ formic acid water, extraction temperature: none, number of cycles: 3 times. Sludge samples are taken and 0.25ng (25ng cotinine), 2.5ng (250ng cotinine), and 10ng (1000ng cotinine) of psychotropic drugs and cotinine standard are added respectively for full-process determination.

[0082] Results Analysis: Spiking tests were performed on actual samples, and the recovery rate was 80%–120%. The accuracy test results are shown in Table 5 below.

[0083] Table 5 Accuracy Test

[0084]

[0085]

[0086]

[0087] The above embodiments are merely illustrative of several implementation methods of this application, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of this application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A method for detecting psychotropic drugs in environmental sludge based on acidic pretreatment, characterized in that, Includes the following steps: S1: Obtain the sludge sample to be tested, freeze-dry the sludge sample to be tested, and then perform pressurized fluid extraction to obtain the extract. Perform solid-phase extraction on the extract and then elute to obtain the eluent. Redissolve the eluent to obtain the solution to be tested. The pressurized fluid extraction conditions are 5‰ formic acid water and no heating. The sludge sample to be tested is placed in a low-temperature environment and frozen for a period of time. The frozen sludge sample to be tested is then dehydrated and dried. The water content of the freeze-dried sludge sample to be tested is less than 5%, and the freeze-drying time is set to be greater than 2 hours. Poly-Sery HLB Pro was selected as the solid-phase extraction column. The solid-phase extraction column was activated with methanol at a flow rate of no more than 1 mL / min, and then rinsed with pure water to obtain an activated solid-phase extraction column. The extract was added to the activated solid-phase extraction column at a flow rate of 4 mL / min, and the solid-phase extraction column was rinsed with pure water at a flow rate of 2 mL / min. Then, the solid-phase extraction column was eluted with methanol at a flow rate of no more than 1 mL / min to obtain the eluent. S2: The solution to be tested is analyzed by liquid chromatography-mass spectrometry to obtain a mass spectrum. Based on the mass-to-charge ratio of the base peak of the mass spectrum, it is determined whether the current sludge sample to be tested contains psychotropic drugs. The chromatographic conditions are: mobile phase A is methanol, mobile phase B is 0.1% formic acid water, gradient elution; the psychotropic drugs are: cotinine, codeine, AMP, MAMP, MDA, monoacetylmorphine, MDMA, PMMA, fluoroquinolone, normethamidophenone, ketamine, norfentanyl, benzoylecone, cocaine, and tramadol. The triple quadrupole liquid chromatography-mass spectrometry (LC-MS) system was selected, and the ACQUITY UPLC HSS T3 column was chosen. The mass spectrometry conditions were set as follows: electrospray ionization source; ion source temperature: 550 ℃; detection mode: multiple reaction monitoring; scanning mode: positive / negative ion scan. The elution conditions for gradient elution are shown in the table below: 。 2. The method for detecting psychotropic drugs in environmental sludge based on acidic pretreatment according to claim 1, characterized in that, The eluent was concentrated by nitrogen blowing and then injected with 20% methanol-water solution to obtain the test solution.

3. The method for detecting psychotropic drugs in environmental sludge based on acidic pretreatment according to claim 1, characterized in that, Quantitative detection of psychotropic drugs was performed using the internal standard method, with the internal standard being the deuterated isotope of each psychotropic drug.

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