Method for detecting content of tetrahydrofuran in soil and application of method

Abstract

The invention discloses a method for detecting the content of tetrahydrofuran in soil, which comprises the following steps: S1, weighing the soil, placing the soil in a purging bottle, adding water and a stirrer, adding an internal standard sample, and preparing for detection; and S2, carrying out detection by adopting a gas chromatograph-mass spectrometer. According to the method, the tetrahydrofuran in the soil is detected by purging and trapping, particularly the low-content tetrahydrofuran in the soil is detected, and the method has relatively high sensitivity and low detection limit. The sample inlet temperature of 250 DEG C is adopted, so that the separation time in a chromatographic column is prolonged, the detection sensitivity of tetrahydrofuran in soil can be improved, and the detection accuracy is improved. By adopting the chromatographic column with the specification of 20m * 0.18 mm * 1mu m, the accuracy of tetrahydrofuran detection can be improved, and the interference of impurities is reduced. The method has a linear relation within the concentration range of 100-500 [mu] g / L, the relative standard deviation is low, and the adding standard recovery rate is high.

Description

Technical Field

[0001] The present invention relates to testing or analyzing materials by measuring the chemical or physical properties of the materials, and particularly relates to a detection method for the content of tetrahydrofuran in soil and its application Background Art

[0002] Tetrahydrofuran is a chemical reagent commonly used in the chemical industry. Inevitably, there will be problems of leakage, volatilization, and spillage during daily production. After long-term production, the soil around chemical equipment may be contaminated by organic solvents. However, due to the small amount of reagent infiltration and the long time, the content of tetrahydrofuran in soil samples will not be too high. Using traditional detection methods, accurate detection of low-content tetrahydrofuran cannot be achieved. Therefore, it is crucial to develop a detection method for the content of tetrahydrofuran in soil with a low detection limit and high accuracy

[0003] Chinese invention patent CN112362772A discloses a detection method for residual organic solvents in soil. A headspace gas chromatography-mass spectrometry instrument is used to detect soil samples, and the content of residual organic solvents in soil samples is quantitatively calculated by the external standard method. The sample treatment method is simple and the detection process is convenient to operate, but the detection limit is low and it is not suitable for the detection of low-content organic solvents. Chinese invention patent CN106526018B discloses a method for detecting residual organic solvents in soil by gas chromatography-mass spectrometry. The soil to be detected is pretreated with anhydrous Na 2 SO 4 to obtain an extract, and then the extract is measured by gas chromatography-mass spectrometry. Anhydrous MgSO 4 is added to the extract before passing through the chromatographic column, and the residual amount of organic solvents in soil can be detected quickly, conveniently, accurately, and sensitively. However, the detection limit for tetrahydrofuran is relatively high and trace detection cannot be achieved Summary of the Invention

[0004] In order to develop a detection method for the content of tetrahydrofuran in soil with a low detection limit and high accuracy, the first aspect of the present invention provides a detection method for the content of tetrahydrofuran in soil, comprising the following steps:

[0005] S1: Weigh the soil and place it in a purge bottle, add water and a stir bar, add an internal standard sample, and prepare for detection;

[0006] S2: Use a gas chromatography-mass spectrometry instrument for detection.

[0007] The lowest detectable content of tetrahydrofuran in the soil ≤ 0.6 μg / kg.

[0008] During the experiment, the inventor found that purge and trap has high sensitivity, low detection limit and high repeatability for detecting tetrahydrofuran in soil, especially for detecting low-content tetrahydrofuran in soil. It is speculated that the possible reason is: when the content of tetrahydrofuran in soil is low, by using purge and trap, tetrahydrofuran in soil is extracted by continuous gas and then analyzed and determined. Compared with the static extraction of headspace collection, purge and trap can collect as much tetrahydrofuran in soil as possible, so as to realize the detection of low-content tetrahydrofuran.

[0009] As an implementation manner, the weight-volume ratio of the soil to the water is (3 - 8) g : (5 - 15) mL.

[0010] As an implementation manner, the weight-volume ratio of the soil to the water is 5 g : 10 mL.

[0011] As an implementation manner, the concentration of the internal standard sample is 400 - 800 μg / L.

[0012] As an implementation manner, the concentration of the internal standard sample is 400 μg / L.

[0013] As an implementation manner, the internal standard is fluorobenzene.

[0014] As an implementation manner, the inlet temperature of the gas chromatography-mass spectrometry (GC-MS) instrument is 240 - 260 °C.

[0015] As an implementation manner, the inlet temperature of the gas chromatography-mass spectrometry (GC-MS) instrument is 250 °C.

[0016] As an implementation manner, the split ratio of the gas chromatography-mass spectrometry (GC-MS) instrument is (5 - 15) : 1.

[0017] As an implementation manner, the split ratio of the gas chromatography-mass spectrometry (GC-MS) instrument is 10 : 1.

[0018] As an implementation manner, the length of the chromatographic column of the gas chromatography-mass spectrometry (GC-MS) instrument is 20 - 60 m, the inner diameter is 0.18 - 0.32 mm, and the film thickness is 1 - 1.8 μm.

[0019] As an implementation manner, the length of the chromatographic column of the gas chromatography-mass spectrometry (GC-MS) instrument is 20 - 40 m, the inner diameter is 0.18 - 0.24 mm, and the film thickness is 1 - 1.5 μm.

[0020] As an implementation manner, the length of the chromatographic column of the gas chromatography-mass spectrometry (GC-MS) instrument is 20 m, the inner diameter is 0.18 mm, and the film thickness is 1 μm.

[0021] The inventors further found that by using an inlet temperature of 250 °C and extending the separation time in the chromatographic column, the detection sensitivity of tetrahydrofuran in soil can be improved, and the detection accuracy can be enhanced. The reason may be that the gas after purge and trap still contains impurity gases such as bromochloromethane, chloroform, and 1,1,1-trichloroethane, which cause interference. Using a lower heating rate can promote the dispersion of the collected gas in the chromatographic column. Moreover, the chromatographic column has a longer length and high column efficiency, enabling the precise separation of tetrahydrofuran and improving the detection accuracy and precision.

[0022] As an embodiment, the injection interfering substances detected by the gas chromatography-mass spectrometry include, but are not limited to, bromochloromethane, chloroform, and 1,1,1-trichloroethane.

[0023] As an embodiment, the gradient temperature program of the chromatographic column of the gas chromatography-mass spectrometry is as follows: the column temperature is maintained at 30 - 40 °C for 1 - 5 min, and then heated to 200 °C at a rate of 10 - 20 °C / min, and maintained at 200 °C for 0.1 - 0.3 min.

[0024] As an embodiment, the gradient temperature program of the chromatographic column of the gas chromatography-mass spectrometry is as follows: the column temperature is maintained at 33 - 37 °C for 3 - 5 min, and then heated to 200 °C at a rate of 13 - 16 °C / min, and maintained at 200 °C for 1 - 3 min.

[0025] As an embodiment, the gradient temperature program of the chromatographic column of the gas chromatography-mass spectrometry is as follows: the column temperature is maintained at 35 °C for 4 min, and then heated to 200 °C at a rate of 15 °C / min, and maintained at 200 °C for 1 min.

[0026] As an embodiment, the mass spectrometry of the gas chromatography-mass spectrometry is a single quadrupole mass spectrometry, the temperature of the quadrupole is 140 - 160 °C, and the temperature of the ion source is 220 - 240 °C.

[0027] As an embodiment, the temperature of the quadrupole is 150 °C, and the temperature of the ion source is 230 °C.

[0028] As an embodiment, the full scan range of the mass spectrometry of the gas chromatography-mass spectrometry is 35 - 260 m / z.

[0029] The collected gas also contains a relatively high content of oxygen. By using a scan range of 35 - 260 m / z in the mass spectrometry, the impurity interference of oxygen can be excluded, the detection precision of tetrahydrofuran is improved, and the detection limit of tetrahydrofuran is reduced.

[0030] As an embodiment, the detection concentration range of tetrahydrofuran is 100 - 500 μg / L.

[0031] The second aspect of the present invention provides an application of a method for detecting the content of tetrahydrofuran in soil, which is applied to the soil detection within chemical enterprises and within a radius of 5 km around chemical enterprises.

[0032] As an implementation mode, the soil to be detected includes, but is not limited to, the soil near the storage tank area, the production workshop area, and the sewage collection tank.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] (1) For the method for detecting the content of tetrahydrofuran in soil according to the present invention, purge and trap is used to detect tetrahydrofuran in soil, especially for detecting low-content tetrahydrofuran in soil, which has high sensitivity and low detection limit.

[0035] (2) For the method for detecting the content of tetrahydrofuran in soil according to the present invention, an inlet temperature of 250 °C is adopted, and the separation time in the chromatographic column is extended, which can improve the detection sensitivity of tetrahydrofuran in soil and improve the detection accuracy.

[0036] (3) For the method for detecting the content of tetrahydrofuran in soil according to the present invention, a chromatographic column with a specification of 20 m × 0.18 mm × 1 μm can improve the detection accuracy of tetrahydrofuran and reduce the interference of impurities such as bromochloromethane, chloroform, and 1,1,1-trichloroethane.

[0037] (4) For the method for detecting the content of tetrahydrofuran in soil according to the present invention, a scanning range of 35 - 260 m / z can exclude the interference of oxygen impurities and improve the detection precision of tetrahydrofuran.

[0038] (5) For the method for detecting the content of tetrahydrofuran in soil according to the present invention, it has a linear relationship within the concentration range of 100 - 500 μg / L, with a low relative standard deviation and a high spiked recovery rate. Specific embodiments

[0039] Example

[0040] A method for detecting the content of tetrahydrofuran in soil includes the following steps:

[0041] S1: Weigh the soil and place it in a purge bottle, add water and a stir bar, and add an internal standard sample to prepare for detection;

[0042] S2: Use a gas chromatography - mass spectrometry (GC - MS) instrument for detection.

[0043] The inlet temperature of the gas chromatography - mass spectrometry instrument is 250 °C.

[0044] The split ratio of the gas chromatography - mass spectrometry instrument is 10:1.

[0045] The chromatographic column of the gas chromatography - mass spectrometry (GC - MS) instrument has a length of 20 m, an inner diameter of 0.18 mm, and a film thickness of 1 μm.

[0046] The gradient temperature program of the chromatographic column of the gas chromatography - mass spectrometry instrument is as follows: the column temperature is maintained at 35°C for 4 min, then heated to 200°C at a rate of 15°C / min, and held at 200°C for 1 min.

[0047] The mass spectrometry of the gas chromatography - mass spectrometry instrument is a single quadrupole mass spectrometry. The temperature of the quadrupole is 150°C, and the temperature of the ion source is 230°C.

[0048] The full - scan range of the mass spectrometry of the gas chromatography - mass spectrometry instrument is 35 - 260 m / z.

[0049] Standard curve drawing:

[0050] Prepare water standard solutions of tetrahydrofuran with concentrations of 100 μg / L, 200 μg / L, 300 μg / L, 400 μg / L, and 500 μg / L. Conduct detection with a gas chromatography - mass spectrometry instrument, and the test results are shown in Table 1.

[0051] Table 1

[0052] Concentration (μg / L) 100 200 300 400 500 Response value 3284 7220 13391 18647 24793 Internal standard response value 73621 77049 92678 89955 98423

[0053] The internal standard is fluorobenzene, and the concentration is 400 μg / L.

[0054] The standard curve is Y = 0.021128X - 0.010058, R 2 = 0.997

[0055] Precision determination:

[0056] Repeat the test of the tetrahydrofuran solution with a concentration of 200 μg / L 6 times, and the test results are shown in Table 2.

[0057] Table 2

[0058]

[0059]

[0060] Blank spiking test: Spike the blank matrix and test the response value and recovery rate after spiking. The test results are shown in Table 3. The blank matrix is quartz sand, and the usage amount is 5 g.

[0061] Table 3

[0062]

[0063] Soil sample detection: The soil is the surface soil of a chemical enterprise

[0064] The weight - volume ratio of the soil and water is 5 g: 10 mL. The test results are shown in Table 4.

[0065] Table 4

[0066]

[0067]

[0068] Determination of the spiked recovery rate of soil samples: The test results are shown in Table 5.

[0069] Table 5

[0070]

[0071] Determination of the detection limit: The test results are shown in Table 6.

[0072] Table 6

[0073]

[0074]

[0075] Determination of error: Prepare 3 groups of tetrahydrofuran samples with a concentration of 200 μg / L, test the detection error, and the test results are shown in Table 7.

[0076] Table 7

[0077]

Claims

1. A method for detecting tetrahydrofuran content in soil, characterized in that: The following steps are involved: S1: Weigh the soil and place it in a purge bottle, add water and a stir bar, add the internal standard sample, and prepare for testing; S2: Detection by gas chromatography-mass spectrometry; The minimum detected content of tetrahydrofuran in the soil is ≤0.6 μg / kg.

2. The method for detecting tetrahydrofuran content in soil according to claim 1, characterized in that: The weight-to-volume ratio of the soil and water is (3-8) g: (5-15) mL.

3. The method for detecting tetrahydrofuran content in soil according to claim 1, characterized in that: The concentration of the internal standard sample is 400-800 μg / L.

4. The method for detecting tetrahydrofuran content in soil according to claim 1, characterized in that: The injection port temperature of the gas chromatography-mass spectrometry instrument is 240-260°C.

5. The method for detecting tetrahydrofuran content in soil according to claim 1, characterized in that: The chromatographic column of the gas chromatography-mass spectrometry instrument has a length of 20-60 m, an inner diameter of 0.18-0.32 mm, and a film thickness of 1-1.8 μm.

6. The method for detecting tetrahydrofuran content in soil according to claim 1, characterized in that: The gradient temperature increase program of the chromatographic column of the gas chromatography-mass spectrometry instrument is: the column temperature is maintained at 30-40°C for 1-5 minutes, then increased to 200°C at a speed of 10-20°C / min, and maintained at 200°C for 1-3 minutes.

7. The method for detecting tetrahydrofuran content in soil according to claim 1, characterized in that: The mass spectrometer of the gas chromatography-mass spectrometer is a single quadrupole mass spectrometer, the temperature of the quadrupole is 140-160°C, and the temperature of the ion source is 220-240°C.

8. The method for detecting tetrahydrofuran content in soil according to claim 7, characterized in that: The full scanning range of the mass spectrum of the gas chromatography-mass spectrometry instrument is 35-260m / z.

9. The method for detecting tetrahydrofuran content in soil according to claim 1, characterized in that: The detection concentration range of the tetrahydrofuran is 100-500 μg / L.

10. An application of the method for detecting tetrahydrofuran content in soil according to any one of claims 1 to 9, characterized in that: Applied to soil testing within chemical enterprises and within a 5km radius of chemical enterprises.

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