A method for detecting aldehyde and ketone compounds in soil and solid waste based on derivatization-microextraction-mass spectrometry

Abstract

The application discloses a kind of detection methods of aldehyde ketone compounds in soil and solid waste based on derivatization-microextraction-mass spectrometry, S1: sample rapid extraction, take soil or solid waste sample, add acetonitrile-water mixed extractant containing formic acid, and obtain sample extract by filtration;S2: online rapid derivatization: sample extract and oxime derivative reagent are mixed to generate aldehyde ketone oxime derivative solution;S3: selective microextraction enrichment, aldehyde ketone oxime derivative solution is introduced into layered packing microextraction column, and selective enrichment is carried out;S4: thermal desorption, after enrichment, microextraction column is heated and thermally desorbed;S5: gas chromatography-mass spectrometry detection, desorption is sent into gas chromatography-mass spectrometer detection;S6: qualitative and quantitative analysis, qualitative identification is carried out based on aldehyde ketone compound characteristic mass spectrum database, the content of aldehyde ketone compound in sample is calculated, and detection result is output.The application can improve mass spectrometry response efficiency, and significantly improve detection efficiency.

Description

Technical Field

[0001] This invention belongs to the field of environmental monitoring and analysis technology, and specifically relates to a method for detecting aldehydes and ketones in soil and solid waste based on derivatization-microextraction-mass spectrometry. Background Technology

[0002] Aldehydes and ketones are a class of volatile toxic and harmful substances widely present in the environment, mainly including formaldehyde, acetaldehyde, acrolein, butyraldehyde, pentanal, and benzaldehyde. They pose strong carcinogenic, teratogenic, and mutagenic risks and have been included in my country's list of priority controlled pollutants. Aldehydes and ketones are highly polar, water-soluble, and easily diffuse, and can enter ecosystems through soil and solid waste. Long-term exposure will seriously harm the human respiratory, nervous, and immune systems. Therefore, establishing rapid, sensitive, and accurate detection methods for aldehydes and ketones in soil and solid waste is of significant practical importance for environmental quality assessment, pollution source tracing, risk management, and emergency response to sudden pollution events.

[0003] Currently, the detection methods for aldehydes and ketones in soil and solid waste at home and abroad mainly include gas chromatography, liquid chromatography, derivatization-chromatography combined with other methods, and some rapid screening technologies. However, existing methods generally suffer from problems such as cumbersome pretreatment, long processing time, insufficient sensitivity, weak resistance to matrix interference, large solvent consumption, and difficulty in automation and on-site application, making it difficult to meet the needs of batch and rapid detection of trace and complex matrix samples.

[0004] Traditional gas chromatography (GC) for the direct determination of aldehydes and ketones suffers from severe peak tailing, poor resolution, and asymmetrical peak shapes due to the high polarity, significant differences in volatility, and easy adsorption of aldehydes and ketones. Furthermore, the detection limits are typically at the 0.1-1 μg / g level, making it difficult to meet the requirements for trace detection. While liquid chromatography (LC) allows for direct sample injection, it lacks highly sensitive universal detectors. Ultraviolet detectors have weak responses and poor selectivity, and fluorescence detectors require specific structures for aldehydes and ketones, limiting their application and hindering the effective detection of ultra-trace aldehydes and ketones in complex matrices. More importantly, both conventional chromatographic methods rely on complex pretreatment processes, including Soxhlet extraction, liquid-liquid extraction, distillation, concentration, and purification. These processes are cumbersome, require high operational skills, involve long pretreatment times for single samples, consume large amounts of organic solvents, are prone to secondary contamination, and introduce significant errors and poor repeatability through manual operation, making high-throughput and automated analysis difficult.

[0005] To improve the chromatographic behavior and detection sensitivity of aldehydes and ketones, existing technologies generally employ derivatization pretreatment, with 2,4-dinitrophenylhydrazine (DNPH) being the most widely used. However, the DNPH derivatization system has significant drawbacks: First, the reaction rate is slow, typically requiring 1-2 hours to complete, and necessitates strict control under light-protected and acidic conditions; second, the derivatized products exhibit poor stability, easily decomposing at room temperature and susceptible to the effects of light, temperature, and matrix composition, leading to large fluctuations in recovery rates (70%-90%) and poor repeatability of detection results; third, it has weak resistance to matrix interference, with organic matter, humic acid, heavy metals, and other components in soil and solid waste easily reacting with DNPH or its derivatized products, further reducing recovery rates and increasing background interference; fourth, the derivatized products have low mass spectrometric response, making it difficult to achieve highly sensitive detection. Furthermore, traditional solid-phase extraction and liquid-liquid extraction enrichment techniques for complex matrix samples suffer from poor selectivity, low enrichment folds, easy adsorption losses, and difficulty in online integration, further limiting the sensitivity and automation level of detection methods.

[0006] Meanwhile, existing detection technologies heavily rely on large laboratory instruments. Samples need to be transported, stored, and pre-treated before analysis, typically taking several days from sampling to obtaining results. This poor timeliness fails to meet the needs of rapid on-site screening of contaminated sites, real-time monitoring of solid waste treatment processes, and rapid response to sudden pollution incidents. With the continuous advancement of soil pollution prevention and control, standardized management of solid waste, and the construction of ecological and environmental emergency response capabilities in China, higher requirements are being placed on detection methods for aldehydes and ketones: rapid, sensitive, accurate, low-cost, automated, and on-site. However, existing technologies cannot simultaneously meet these requirements. There is an urgent need to develop a new method integrating rapid derivatization, efficient microextraction, online enrichment, and mass spectrometry detection to overcome existing technological bottlenecks and provide reliable technical support for the monitoring and control of aldehydes and ketones in soil and solid waste.

[0007] The information disclosed in this background section is intended only to enhance the understanding of the overall background of the invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0008] The purpose of this invention is to provide a method for detecting aldehydes and ketones in soil and solid waste based on derivatization-microextraction-mass spectrometry, thereby overcoming the defects in the prior art.

[0009] To achieve the above objectives, this invention provides a method for detecting aldehydes and ketones in soil and solid waste based on derivatization-microextraction-mass spectrometry, comprising the following steps: S1: Rapid sample extraction. Take soil or solid waste samples, add acetonitrile-water mixed extractant containing formic acid, and extract using a combination of stirring and ultrasound. Filter to obtain the sample extract. S2: Online rapid derivatization: The sample extract is mixed with oxime derivatization reagents and reacted at a constant temperature in a microreactor to generate an aldehyde-ketone oxime derivative solution; S3: Selective microextraction enrichment: Aldehyde oxime derivative solutions are passed through a layered packing microextraction column and selectively enriched sequentially through hydrophilic-lipophilic balanced packing, molecularly imprinted polymer packing, and metal-organic framework packing. S4: Thermal desorption, the enriched microextraction column is heated for thermal desorption; S5: Gas chromatography-mass spectrometry detection: The desorbed material is sent into the gas chromatography-mass spectrometer, and characteristic ion signals are collected under the set chromatographic and mass spectrometric conditions. S6: Qualitative and quantitative analysis, based on the characteristic mass spectrometry database of aldehyde and ketone compounds for qualitative identification, using the internal standard method to calculate the content of aldehyde and ketone compounds in the sample, and outputting the detection results.

[0010] Preferably, the volume ratio of acetonitrile to water in step S1 is 7:3-9:1.

[0011] Preferably, the volume fraction of formic acid in the acetonitrile-water mixture in step S1 is 0.05%-0.2%.

[0012] Preferably, the oxime derivatizing agent in step S2 is 4-(trimethylsilyl)methoxyamino-7-nitrobenzofuran.

[0013] Preferably, in step S2, the volume ratio of the sample extract to the oxime derivatization reagent is 1:1, the reaction temperature is controlled at 35-45℃, and the reaction time is 2-6 min.

[0014] Preferably, the temperature of thermal desorption in step S4 is 250-300°C.

[0015] Preferably, the gas chromatography in step S5 uses a DB-5MS column.

[0016] Preferably, in step S5, the mass spectrometry detection uses an EI ion source and selectable ion monitoring (SIM) mode to acquire the characteristic ion signals of the target analyte.

[0017] Preferably, the method is applicable to the detection of aldehydes and ketones in soil, solid waste, and sludge environments.

[0018] Compared with the prior art, one aspect of the present invention has the following beneficial effects: (1) The present invention uses 4-(trimethylsilyl)methoxyamino-7-nitrobenzofuran as an oxime derivatization reagent, which has high reaction efficiency and stable product, and has the effect of enhancing electrospray ionization efficiency, thereby improving mass spectrometry response efficiency and significantly improving detection efficiency; (2) The present invention uses a multilayer packed microextraction column to selectively enrich aldehyde and ketone derivatives, with a high enrichment factor, which can effectively reduce the interference of complex matrix in soil and solid waste, with a low detection limit and excellent detection sensitivity. (3) This invention can be used in various complex substrates such as soil, solid waste, and sludge. It uses the internal standard method for quantitative analysis, and the results are accurate and reliable, meeting the needs of environmental monitoring, risk assessment and emergency testing. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of a method for detecting aldehydes and ketones in soil and solid waste based on derivatization-microextraction-mass spectrometry according to the present invention. Detailed Implementation

[0020] The specific embodiments of the present invention will be described in detail below, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments.

[0021] Unless otherwise expressly stated, throughout the specification and claims, the term "comprising" or its variations such as "including" or "comprises" shall be understood to include the stated elements or components without excluding other elements or other components.

[0022] Example 1:

[0023] A method for detecting aldehydes and ketones in soil and solid waste based on derivatization-microextraction-mass spectrometry includes the following steps: S1: Rapid sample extraction. Weigh 2.0g of surface soil sample from a chemical plant site and place it in an extraction bottle. Add 10mL of acetonitrile-water mixed extraction reagent, wherein the volume ratio of acetonitrile to water is 8:2, and the mixed extraction reagent contains 0.1% formic acid by volume. Add 50μL of deuterated aldehyde-ketone mixed internal standard solution. Insert the integrated extraction probe and start the stirring-ultrasonic combined extraction for 3min. Filter the extract through a 0.22μm organic phase filter membrane to obtain the sample extract. S2: Online rapid derivatization was performed by mixing the sample extract with a 0.1% (w / w) solution of 4-(trimethylsilyl)methoxyamino-7-nitrobenzofuran at a volume ratio of 1:1; the mixture was then introduced into a spiral tubular microreactor, and the reaction temperature was controlled at 40℃ with a residence time of 3 min to complete the derivatization and obtain an aldehyde-ketone oxime derivative solution; the molecular structure of 4-(trimethylsilyl)methoxyamino-7-nitrobenzofuran is as follows: ; S3: Selective microextraction enrichment, the aldehyde and ketone oxime derivative solution is passed into the microextraction column at a flow rate of 1 mL / min; the column is filled from top to bottom with 10 mm of hydrophilic and lipophilic balanced packing material, 15 mm of molecularly imprinted polymer packing material, and 15 mm of metal-organic framework packing material to achieve selective enrichment of C1-C4 short-chain aldehydes and ketones, benzaldehydes and long-chain aldehydes and ketones. S4: Thermal desorption. The enriched microextraction column is rapidly heated to 280°C and held for 2 minutes to completely thermally desorb the aldehyde-ketone oxime derivatives. S5: Gas chromatography-mass spectrometry (GC-MS) detection; desorbed substances are directly introduced into the GC-MS instrument; chromatographic conditions: DB-5MS column (30m × 0.25mm × 0.25μm); temperature program: 50℃ for 1 min, then increased to 280℃ at 20℃ / min and held for 5 min; mass spectrometry conditions: EI ion source, electron energy 70eV, selected ion monitoring (SIM) mode for characteristic ion acquisition; S6: Qualitative and quantitative analysis, retrieve the characteristic mass spectrometry database of aldehyde and ketone compounds, and perform qualitative identification based on retention time and characteristic ion fragments; calculate the content of aldehyde and ketone compounds in the sample using the deuterated aldehyde and ketone internal standard method, and output the detection results.

[0024] In this embodiment, formaldehyde was detected at 0.25 μg / g with a relative standard deviation (RDS) of 4.2%, acetaldehyde at 0.18 μg / g with a RDS of 4.5%, and benzaldehyde at 0.05 μg / g with a RSD of 5.3%.

[0025] Example 2:

[0026] A method for detecting aldehydes and ketones in soil and solid waste based on derivatization-microextraction-mass spectrometry includes the following steps: S1: Rapid sample extraction. Weigh 2.0g of municipal solid waste incineration fly ash sample and pretreat with 0.1mol / L hydrochloric acid to remove carbonate interference. Add 10mL of acetonitrile-water mixed extractant, where the volume ratio of acetonitrile to water is 8:2, and the mixed extractant contains 0.1% formic acid by volume. Add 50μL of deuterated aldehyde-ketone mixed internal standard solution. Insert the integrated extraction probe and start stirring-ultrasonic extraction for 3min. Filter the extract through a 0.22μm organic phase filter membrane to obtain the sample extract. S2: Online rapid derivatization: The sample extract was mixed with 0.1% (w / w) 4-(trimethylsilyl)methoxyamino-7-nitrobenzofuran solution at a volume ratio of 1:1; the mixture was then introduced into a spiral tubular microreactor, and the reaction temperature was controlled at 40℃ and the residence time was 3 min to complete the derivatization and obtain an aldehyde-ketone oxime derivative solution. S3: Selective microextraction enrichment, the aldehyde and ketone oxime derivative solution is passed into the microextraction column at a flow rate of 1 mL / min; the column is filled from top to bottom with 10 mm of hydrophilic and lipophilic balanced packing material, 15 mm of molecularly imprinted polymer packing material, and 15 mm of metal-organic framework packing material to achieve selective enrichment of C1-C4 short-chain aldehydes and ketones, benzaldehydes and long-chain aldehydes and ketones. S4: Thermal desorption. The enriched microextraction column is rapidly heated to 280°C and held for 2 minutes to completely thermally desorb the aldehyde-ketone oxime derivatives. S5: Gas chromatography-mass spectrometry (GC-MS) detection; desorbed substances are directly introduced into the GC-MS instrument; chromatographic conditions: DB-5MS column (30m × 0.25mm × 0.25μm); temperature program: 50℃ for 1 min, then increased to 280℃ at 20℃ / min and held for 5 min; mass spectrometry conditions: EI ion source, electron energy 70eV, selected ion monitoring (SIM) mode for characteristic ion acquisition; S6: Qualitative and quantitative analysis, retrieve the characteristic mass spectrometry database of aldehyde and ketone compounds, and perform qualitative identification based on retention time and characteristic ion fragments; calculate the content of aldehyde and ketone compounds in the sample using the deuterated aldehyde and ketone internal standard method, and output the detection results.

[0027] In this embodiment, formaldehyde was detected at 0.32 μg / g with a relative standard deviation (RDS) of 4.5%, acetaldehyde at 0.28 μg / g with a RDS of 3.9%, and benzaldehyde at 0.1 μg / g with a RSD of 5.3%.

[0028] The foregoing description of specific exemplary embodiments of the invention is for illustrative and explanatory purposes. These descriptions are not intended to limit the invention to the precise forms disclosed, and it will be apparent that many changes and variations can be made in accordance with the foregoing teachings. The exemplary embodiments were chosen and described in order to explain the specific principles of the invention and its practical application, thereby enabling those skilled in the art to implement and utilize various different exemplary embodiments of the invention, as well as various different choices and variations. The scope of the invention is intended to be defined by the claims and their equivalents.

Claims

1. A method for detecting aldehydes and ketones in soil and solid waste based on derivatization-microextraction-mass spectrometry, characterized in that, Includes the following steps: S1: Rapid sample extraction. Take soil or solid waste samples, add acetonitrile-water mixed extractant containing formic acid, and extract using a combination of stirring and ultrasound. Filter to obtain the sample extract. S2: Online rapid derivatization: The sample extract is mixed with oxime derivatization reagents and reacted at a constant temperature in a microreactor to generate an aldehyde-ketone oxime derivative solution; S3: Selective microextraction enrichment: Aldehyde oxime derivative solutions are passed through a layered packing microextraction column and selectively enriched sequentially through hydrophilic-lipophilic balanced packing, molecularly imprinted polymer packing, and metal-organic framework packing. S4: Thermal desorption, the enriched microextraction column is heated for thermal desorption; S5: Gas chromatography-mass spectrometry detection: The desorbed material is sent into the gas chromatography-mass spectrometer, and characteristic ion signals are collected under the set chromatographic and mass spectrometric conditions. S6: Qualitative and quantitative analysis, based on the characteristic mass spectrometry database of aldehyde and ketone compounds for qualitative identification, using the internal standard method to calculate the content of aldehyde and ketone compounds in the sample, and outputting the detection results.

2. The method for detecting aldehydes and ketones in soil and solid waste based on derivatization-microextraction-mass spectrometry according to claim 1, characterized in that, In step S1, the volume ratio of acetonitrile to water is 7:3-9:

1.

3. The method for detecting aldehydes and ketones in soil and solid waste based on derivatization-microextraction-mass spectrometry according to claim 2, characterized in that, In step S1, the volume fraction of formic acid in the acetonitrile-water mixture is 0.05%-0.2%.

4. The method for detecting aldehydes and ketones in soil and solid waste based on derivatization-microextraction-mass spectrometry according to claim 1, characterized in that, In step S2, the oxime derivatization reagent used is 4-(trimethylsilyl)methoxyamino-7-nitrobenzofuran.

5. The method for detecting aldehydes and ketones in soil and solid waste based on derivatization-microextraction-mass spectrometry according to claim 1, characterized in that, In step S2, the volume ratio of sample extract to oxime derivatization reagent is 1:1, the reaction temperature is controlled at 35-45℃, and the reaction time is 2-6 min.

6. The method for detecting aldehydes and ketones in soil and solid waste based on derivatization-microextraction-mass spectrometry according to claim 1, characterized in that, The temperature for thermal desorption in step S4 is 250-300℃.

7. The method for detecting aldehydes and ketones in soil and solid waste based on derivatization-microextraction-mass spectrometry according to claim 1, characterized in that, In step S5, gas chromatography uses a DB-5MS column.

8. The method for detecting aldehydes and ketones in soil and solid waste based on derivatization-microextraction-mass spectrometry according to claim 1, characterized in that, In step S5, mass spectrometry detection uses an EI ion source and selectable ion monitoring (SIM) mode to acquire characteristic ion signals of the target analyte.

9. The method for detecting aldehydes and ketones in soil and solid waste based on derivatization-microextraction-mass spectrometry according to claim 1, characterized in that, The method is applicable to the detection of aldehydes and ketones in soil, solid waste, and sludge environments.

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