Qualitative and quantitative method for dimethyl sulfoxide in soil and solid waste

Abstract

The application relates to a qualitative and quantitative method for dimethyl sulfoxide in soil and solid waste, which comprises the following steps: (1) taking a sample to be measured and adding anhydrous sodium sulfate to cover the sample, and sealing the headspace bottle; (2) analyzing the sample to be measured in the headspace bottle by means of gas chromatography-mass spectrometry, measuring the peak area of the spectrum diagram of dimethyl sulfoxide in the sample to be measured, and combining a standard curve to calculate the content of dimethyl sulfoxide in the sample to be measured. The method has good applicability to various soil samples, is simple in pretreatment, high in detection sensitivity, has a detection limit of 0.02 mg / kg, and meets the detection requirements of all soil and solid waste samples with a water content of less than 30%.

Description

Technical Field

[0001] This invention belongs to the field of dimethyl sulfoxide (DMSO) detection technology, and relates to a qualitative and quantitative method for DMSO in soil and solid waste. Background Technology

[0002] Because dimethyl sulfoxide (DMSO) is readily soluble in water and difficult to separate from moisture in soil and solid waste, there are currently no qualitative and quantitative methods for DMSO in soil media, both domestically and internationally. Gas chromatography-mass spectrometry (GC-MS) is the mainstream qualitative and quantitative method, but there is also a lack of GC-MS applications for DMSO both domestically and internationally.

[0003] For example, Zhu Chunyan and Hou Wenjie (Determination of dimethyl sulfoxide content in the solvent recovered from the synthesis of 4,4′-bis(hydroxymethyl)biphenyl[J]. Fine Chemical Intermediates, 2009, 39(1):4.DOI:CNKI:SUN:HNHG.0.2009-01-024.) directly diluted the sample and used high performance liquid chromatography to determine the content of dimethyl sulfoxide in the solvent recovered after the synthesis of 4,4′-bis(hydroxymethyl)biphenyl. This method is not suitable for the qualitative and quantitative determination of dimethyl sulfoxide in soil and solid waste.

[0004] Wang Min, Zhang Honghai, Yang Guipeng (Concentration distribution of dimethyl sulfoxide (DMSO) in the surface seawater of the Yellow and Bohai Seas in summer [J]. Environmental Science, 2013, 34(1):6.DOI:CNKI:SUN:HJKZ.0.2013-01-008.) The dimethyl sulfoxide in seawater was reduced to dimethyl sulfide by NaBH4, and then the content of dimethyl sulfoxide in seawater was indirectly determined by cold trap purge-collection gas chromatography. The pretreatment was complicated, and the indirect method for determining the content of dimethyl sulfoxide in seawater is not suitable for the qualitative and quantitative determination of dimethyl sulfoxide in soil and solid waste.

[0005] Zhu Yanzhi, Ma Luping, Lü Yuting, et al. (High-performance capillary electrophoresis for the determination of residual dimethyl sulfoxide in meningococcal conjugate vaccine stock solution [J]. Progress in Microbiology and Immunology, 2018, 46(3):5. DOI:10.13309 / j.cnki.pmi.2018.03.003.) used capillary zone electrophoresis to determine the content of dimethyl sulfoxide in meningococcal conjugate vaccine stock solution, but it is not suitable for the qualitative and quantitative determination of dimethyl sulfoxide in soil and solid waste.

[0006] Wu Guofen (Microcoulometric Determination of Dimethyl Sulfoxide in Polysulfone Resin [J]. Chemical World, 1984(07):14-15.DOI:CNKI:SUN:HXSS.0.1984-07-005.) proposed a method for determining trace amounts of sulfur-containing organic impurities in sulfur-containing polymers. A stepwise precipitation separation method was used to remove polymers and monomers from the sample, eliminating interference. Then, a rapid microcoulometric sulfur determination method was applied to determine the dimethyl sulfoxide content in the sample solution. However, this method involves complex pretreatment and is an indirect method for determining the dimethyl sulfoxide content in polysulfone resins, making it unsuitable for the qualitative and quantitative determination of dimethyl sulfoxide in soil and solid waste. Summary of the Invention

[0007] The purpose of this invention is to provide a qualitative and quantitative method for dimethyl sulfoxide (DMSO) in soil and solid waste, for the qualitative and quantitative determination and analysis of DMSO in solid samples such as soil and solid waste with a moisture content of less than 30%.

[0008] The objective of this invention can be achieved through the following technical solutions:

[0009] A qualitative and quantitative method for the determination of dimethyl sulfoxide in soil and solid waste, comprising the following steps:

[0010] (1) Take the sample to be tested and add it into the headspace vial, then add anhydrous sodium sulfate to cover the sample and seal the headspace vial;

[0011] (2) The sample to be tested in the headspace vial was analyzed by gas chromatography-mass spectrometry to measure the peak area of ​​the spectrum of dimethyl sulfoxide in the sample to be tested. Then, the content of dimethyl sulfoxide in the sample to be tested was calculated by combining the standard curve.

[0012] Furthermore, the mass ratio of the sample to anhydrous sodium sulfate was 2:1.

[0013] Furthermore, the sample size for testing was 10g.

[0014] Furthermore, during the analysis, the operating parameters of the headspace autosampler were as follows: heating chamber temperature 95℃; quantitative loop temperature 110℃; transfer line temperature 130℃; sample vial equilibration time 20.00 min; injection duration 1.00 min; GC cycle time 28.00 min.

[0015] Furthermore, the headspace autosampler is a 7697A headspace autosampler.

[0016] Furthermore, during the analysis, the operating parameters of the gas chromatography-mass spectrometry (GC-MS) instrument were as follows: column: DB-wax, 30m × 0.25mm × 0.25μm; injection port temperature: 250℃; split injection, split ratio: 5:1; temperature program: 40℃ for 2 min, ramp to 250℃ at 20℃ / min, hold for 3 min; carrier gas: 99.999% pure helium; column flow rate: 1 mL / min; electron impact source (EI), quadrupole temperature: 150℃; ion source temperature: 230℃; MS transfer line temperature: 250℃; ionization energy: 70 eV; scan mode: Scan; solvent delay time: 0 min.

[0017] Furthermore, the gas chromatograph-mass spectrometer is a 7890B-5977A gas chromatograph-mass spectrometer.

[0018] Furthermore, the process of plotting the standard curve is as follows:

[0019] A series of dimethyl sulfoxide methanol standard solutions with increasing concentrations were prepared, sealed in headspace vials, and the test samples in the headspace vials were analyzed by gas chromatography-mass spectrometry. The peak areas of the spectral peaks of the dimethyl sulfoxide methanol standard solutions at different concentrations were measured, and a standard curve based on the peak area and the concentration of the dimethyl sulfoxide methanol standard solution was plotted.

[0020] Furthermore, the operating parameters of the headspace autosampler and gas chromatograph-mass spectrometer are kept consistent during the analysis of the test sample and the plotting of the standard curve.

[0021] Furthermore, the sample to be tested is soil or solid waste containing dimethyl sulfoxide.

[0022] Existing liquid chromatography (LC) methods can measure dimethyl sulfoxide (DMSO) in water, but soil and solid waste matrices are complex. During the extraction and enrichment of DMSO, water-soluble impurities are also enriched, making purification difficult. Therefore, LC methods are insufficient for analyzing DMSO in soil and solid waste. This invention introduces a headspace sampler coupled with gas chromatography-mass spectrometry (GC-MS). (DMSO extraction methods in soil, such as liquid-liquid extraction, cannot separate water, are time-consuming and labor-intensive, and crucially, water cannot be analyzed using GC-MS; other techniques, such as purge-and-trap pretreatment, involve adding water, resulting in poor contamination resistance.) Furthermore, anhydrous sodium sulfate is used for subsequent detection, and instrument conditions have been screened and optimized. This is because dimethyl sulfoxide (DMSO) is readily soluble in water, and both water and DMSO can easily remain in the sample. Extraction is affected by many factors. Firstly, different sample moisture contents lead to different extraction conditions and low efficiency. Therefore, sodium sulfate is used to adsorb moisture (for example, 5 grams of anhydrous sodium sulfate can absorb 6.338 grams of water, which is much greater than the moisture content of a 10g sample). Secondly, the headspace heating chamber temperature is 95℃, which, without boiling water, increases the volatilization of DMSO (DMSO boiling point: 189℃, water boiling point: 100℃) and improves instrument response. Furthermore, moisture and DMSO can easily remain in the instrument tubing, damaging the instrument and potentially causing cross-contamination. Excess sodium sulfate ensures moisture adsorption, reducing the amount of moisture entering the instrument and minimizing the possibility of cross-contamination.

[0023] Compared with existing technologies, the present invention exhibits good peak shape and a high linear correlation coefficient R when determining dimethyl sulfoxide in soil and solid waste. 2 The relative standard deviation of the spiked value is greater than 0.999, and the relative standard deviation is <20%. The average recoveries of different soil samples with different concentrations are 90.2%–112%, with relative standard deviations of 0.8%–15.9%, demonstrating good applicability to various soil samples. This method has simple pretreatment, high detection sensitivity, and a detection limit of 0.02 mg / kg, meeting the requirements for the detection of all environmental soil samples. Attached Figure Description

[0024] Figure 1 The images show the chromatogram and mass spectrum of dimethyl sulfoxide on a DB-wax column. Detailed Implementation

[0025] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0026] In the following embodiments, unless otherwise specified, the raw materials or processing techniques are conventional commercially available raw materials or conventional processing techniques in the art.

[0027] In addition, the specific instruments and reagents used are as follows:

[0028] Instruments: Gas chromatograph-mass spectrometer: Agilent 7890B-5977A, 7697A headspace autosampler; Column: DB-wax (30m×0.25mm×0.25μm).

[0029] Reagents: Dimethyl sulfoxide (HPLC grade, Shanghai Anpu Experimental Technology Co., Ltd.); Anhydrous sodium sulfate (AR grade, Sinopharm Chemical Reagent Co., Ltd.).

[0030] Samples: blank soil, loam, miscellaneous fill soil, and industrial contaminated soil from a certain location (self-collected).

[0031] Example 1:

[0032] This embodiment provides a qualitative and quantitative method for the analysis of dimethyl sulfoxide in soil and solid waste, specifically including the following steps:

[0033] (1) Sample pretreatment

[0034] Method: Weigh 10g of sample into a headspace vial, quickly add 5g of anhydrous sodium sulfate to cover the sample, and then quickly seal the headspace vial for testing.

[0035] (2) Instrumental Analysis

[0036] Different soil samples were analyzed using GC-MS under the following conditions:

[0037] 7697A Headspace Automated Sampler: Temperature settings: Heating chamber temperature: 95℃, Quantitative loop temperature (℃): 110℃, Transfer line temperature (℃): 130℃; Time settings: Sample vial equilibration: 20.00 min; Injection duration: 1.00 min; GC cycle time: 28.00 min;

[0038] 7890B-5977A Gas Chromatography-Mass Spectrometer: Column: DB-wax (30m × 0.25mm × 0.25μm); Injector temperature: 250℃; Split injection, split ratio 5:1; Temperature program: 40℃ for 2 min, ramp to 250℃ at 20℃ / min, hold for 3 min; Carrier gas: Helium (99.999%); Column flow rate: 1 mL / min. Electron impact source (EI), quadrupole temperature: 150℃; Ion source temperature: 230℃; MS transfer line temperature: 250℃; Ionization energy: 70 eV; Scan mode: Scan / SIM; Solvent delay time: 0 min.

[0039] (3) Analyze the peak area of ​​dimethyl sulfoxide in each sample and combine it with the standard curve to calculate the specific content of dimethyl sulfoxide in each sample.

[0040] Additionally, based on the instrument conditions in step (2) of the above embodiments, another 100 μL of a 11 mg / L dimethyl sulfoxide solution was added to the headspace vial, with all other conditions remaining the same. The Scan chromatogram was compared as follows: Figure 1 As shown. By Figure 1 It is evident that the peak shape of the dimethyl sulfoxide spectrum is good under the conditions of this instrument.

[0041] A series of dimethyl sulfoxide (DMSO) methanol standard solutions with concentration gradients of 0.220 mg / kg, 0.330 mg / kg, 0.440 mg / kg, 1.10 mg / kg, 1.65 mg / kg, 5.50 mg / kg, 7.00 mg / kg, 11.0 mg / kg, 20.0 mg / kg, 33.0 mg / kg, 100 mg / kg, and 330 mg / kg were prepared. Quantitative analysis was performed using Scan. A standard curve was plotted with DMSO concentration on the x-axis and DMSO peak area (quantitative ion response value) on the y-axis. The average relative response factor was plotted. The calculation results are shown in Table 1. 10g of blank soil was used as the blank matrix, and dimethyl sulfoxide standard solution (target analyte content 0.11mg / kg) was added. Seven samples were repeatedly measured, and the detection limit was calculated. The results are shown in Table 1.

[0042] Table 1. Standard curve and detection limit of dimethyl sulfoxide (DMSO)

[0043]

[0044] Table 1 shows that the linear correlation coefficient R of dimethyl sulfoxide is... 2 Greater than 0.999 The relative standard deviation (RSD) was <20%, and the detection limit was 0.0200 mg / kg, which fully meets the requirements for the determination of trace amounts of dimethyl sulfoxide in soil.

[0045] To compare the applicability of this method to samples with different properties, such as loam, fill, and industrial contaminated soil, spiked experiments were conducted at different concentrations. 10 g of loam, fill, and industrial contaminated soil were taken and dimethyl sulfoxide standard solution was added to make the target analyte concentrations in loam, fill, and industrial contaminated soil 1.4 mg / kg, 4.4 mg / kg, and 66 mg / kg, respectively. Sample pretreatment was performed according to the aforementioned method, and the results were measured in parallel six times. The results are shown in Table 2.

[0046] Table 2. Spike experiments on different concentrations of water samples with different quality.

[0047]

[0048] The results showed that the average recoveries of the target analyte at concentrations of 1.4 mg / kg, 4.4 mg / kg, and 66 mg / kg in loam, fill, and industrial contaminated soil ranged from 94.3% to 112%, with relative standard deviations of 0.8% to 15.9%. This indicates that the method has good accuracy and precision and is well applicable to samples with different properties, such as loam, fill, and industrial contaminated soil.

[0049] Take another 10g of positive soil sample (containing dimethyl sulfoxide) and retest according to the method in Example 1. The test results and accuracy are shown in Table 3.

[0050] Table 3 Retesting of Positive Samples

[0051]

[0052]

[0053] The results of retesting positive samples showed that the relative standard deviation of the method detection results was less than 20%, and most of them were less than 10%. The detection results of the method established in this invention are accurate and reliable. The gas chromatography-mass spectrometry method used in this paper is accurate in qualitative and quantitative analysis, convenient, and reduces time, consumables and labor costs.

[0054] Based on the above, this invention provides a method for determining dimethyl sulfoxide (DMS) in soil using gas chromatography-mass spectrometry (GC-MS). Experimental results show that DMS has a good peak shape and high detection sensitivity. Standard curves and spiked experiments with different concentrations on different soil samples demonstrate that this method has good linearity, accuracy, and precision, and is well-suited for samples with different properties, such as loam, fill, and industrial contaminated soil, meeting the detection requirements for DMS in various soil samples. Retesting of positive samples and method comparison show that this method is accurate in both qualitative and quantitative analysis, and the experimental method is convenient, improving pretreatment efficiency and reducing labor, consumable, and time costs.

[0055] Experimental results show that this method exhibits good linearity, excellent recovery rate, extremely low detection limit, reliability, and good reproducibility. Furthermore, the method is simple to implement, provides more accurate qualitative analysis, and has extremely low costs for consumables and instruments.

[0056] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A qualitative and quantitative method for dimethyl sulfoxide in soil and solid waste, characterized in that, Includes the following steps: (1) Take the sample to be tested and add it into the headspace vial, then add anhydrous sodium sulfate to cover the sample and seal the headspace vial; (2) The sample to be tested in the headspace vial was analyzed by gas chromatography-mass spectrometry to measure the peak area of ​​the spectrum of dimethyl sulfoxide in the sample to be tested. Then, the content of dimethyl sulfoxide in the sample to be tested was calculated by combining the standard curve. The mass ratio of the sample to anhydrous sodium sulfate was 2:

1. During the analysis, the operating parameters of the headspace autosampler were as follows: oven temperature 95℃; quantitative loop temperature 110℃; transfer line temperature 130℃; sample vial equilibration time 20.00 min; injection duration 1.00 min; GC cycle time 28.00 min. During the analysis, the operating parameters of the gas chromatography-mass spectrometry (GC-MS) instrument were as follows: column: DB-wax, 30 m × 0.25 mm × 0.25 μm; injection port temperature: 250℃; split injection, split ratio: 5:1; temperature program: 40℃ for 2 min, ramp to 250℃ at 20℃ / min, hold for 3 min; carrier gas: 99.999% pure helium; column flow rate: 1 mL / min; electron impact source (EI), quadrupole temperature: 150℃; ion source temperature: 230℃; MS transfer line temperature: 250℃; ionization energy: 70 eV; scan mode: Scan; solvent delay time: 0 min. The sample to be tested is soil or solid waste containing dimethyl sulfoxide.

2. A method for qualitative and quantitative determination of dimethyl sulfoxide in soil and solid waste as claimed in claim 1, wherein, The sample size to be tested is 10g.

3. The qualitative and quantitative method for dimethyl sulfoxide in soil and solid waste according to claim 1, characterized in that, The headspace autosampler is a 7697A headspace autosampler.

4. The qualitative and quantitative method for dimethyl sulfoxide in soil and solid waste according to claim 1, characterized in that, The gas chromatograph-mass spectrometer is a 7890B-5977A gas chromatograph-mass spectrometer.

5. The qualitative and quantitative method for dimethyl sulfoxide in soil and solid waste according to claim 1, characterized in that, The process of plotting the standard curve is as follows: A series of dimethyl sulfoxide methanol standard solutions with increasing concentrations were prepared, sealed in headspace vials, and the test samples in the headspace vials were analyzed by gas chromatography-mass spectrometry. The peak areas of the spectral peaks of the dimethyl sulfoxide methanol standard solutions at different concentrations were measured, and a standard curve based on the peak area and the concentration of the dimethyl sulfoxide methanol standard solution was plotted.

6. The qualitative and quantitative method for dimethyl sulfoxide in soil and solid waste according to claim 5, characterized in that, The operating parameters of the headspace autosampler and gas chromatograph-mass spectrometer were kept consistent during the analysis of the sample and the plotting of the standard curve.

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