Quantitative analysis method of ethanethiol

Abstract

The invention provides a quantitative analysis method of ethanethiol, which adopts a gas chromatograph for analysis, and selects a DB-WAXetr strong polarity polyethylene glycol capillary column as a chromatographic column; the column temperature is set as follows: the initial temperature is 80 DEG C and is kept for 5 minutes; raising the temperature to 220 DEG C at the temperature raising rate of 20 DEG C / min, and keeping the temperature for 1 minute; the detection method is suitable for TCD and FID detectors, wherein the TCD can accurately and quantitatively analyze the content of low-boiling-point impurities such as methyl mercaptan, water, H2S, ethane, methane, propane and the like; the FID detector can be used for analyzing high-boiling-point impurities such as ethyl sulfide, isopropyl ethyl sulfide, n-butyl ethyl sulfide, thiophene and xylene contained in a sample; through mutual combination and verification of data of the two detectors, an analysis basis is provided for accurate quantification of the content of each component in a high-purity ethanethiol product.

Description

Technical Field

[0001] The invention relates to a gas chromatography analysis method, in particular to a quantitative analysis method for high-purity ethyl mercaptan, which can effectively separate impurities in ethyl mercaptan and is suitable for quantitative analysis of ethyl mercaptan crude products and high-purity ethyl mercaptan products. Background Art

[0002] Ethyl mercaptan is the world's stinkiest substance. Impurities are introduced during the preparation of ethyl mercaptan, and its strong water absorption makes purification difficult. The main impurities are water, methyl mercaptan and ethyl sulfide, and it contains a small amount of multi-carbon impurities. Currently, the more common quantitative detection methods for ethyl mercaptan include gas chromatography, liquid chromatography and infrared spectroscopy, but there are no clear chromatographic conditions such as chromatographic column selection, detector selection, and heating program. Setting chromatographic conditions according to the properties of ethyl mercaptan and each impurity component to achieve effective separation and quantitative analysis of low-content complex impurity components is the key to establishing high-purity ethyl mercaptan analysis standards. Summary of the invention

[0003] In view of the above problems, the present invention provides a quantitative analysis method of ethyl mercaptan, which is analyzed by gas chromatograph. The specific analysis method comprises the following steps: (1) Prepare standard samples and samples to be tested; (2) Analyze the standard sample using gas chromatography and draw a standard curve; (3) Analyze the sample using a gas chromatograph and calculate the ethyl mercaptan content; The gas chromatograph uses DB-WAXetr strong polar polyethylene glycol capillary column as the chromatographic column; The column temperature of the gas chromatograph was set as follows: initial temperature 80°C, maintained for 5 min; then heated to 220°C at a heating rate of 20°C / min, maintained for 1 min; The working conditions of gas chromatograph are: The maximum column box temperature is 260°C, check "cover column maximum value"; Column temperature equilibrium time: 0.25~0.5min; Injection volume: 0.2~1μL; Inlet temperature: 220°C; Inlet pressure: 4.3727 psi; Injection mode: split injection; Split ratio: 5:1; Detector: TCD or FID.

[0004] The method for preparing the sample to be tested in step (1) is as follows: filtering the initial ethyl mercaptan with an organic filter membrane, transferring 0.5-1 mL of the filtered ethyl mercaptan into a sample bottle, and immediately sealing the bottle to obtain the ethyl mercaptan sample to be tested.

[0005] During gas chromatography analysis, samples were injected using an automatic sampler.

[0006] The dimensions of the chromatographic column are: length 30 m, inner diameter 0.32 mm, and film thickness 0.5 μm.

[0007] When the TCD detector is selected, the detector temperature is 225°C, the reference flow rate is 10 mL / min, the tail gas is hydrogen, the tail gas flow rate is 5 mL / min, and the hot wire state is on; When the FID detector is selected, the detector temperature is 225°C, the air flow rate is 400 mL / min, the hydrogen fuel gas flow rate is 30 mL / min, the tail gas is nitrogen, the tail gas flow rate is 25 mL / min, and the flame state is on.

[0008] The organic filter membrane is an organic filter membrane with a pore size of 0.2 μm, and the material of the organic filter membrane is one of PES, PTFE or PVDF; The content of ethyl mercaptan in the ethyl mercaptan sample to be tested is 98.0% to 99.9%, and the impurities include at least one of methyl mercaptan, water, H2S, ethane, methane, propane, ethyl sulfide, isopropyl ethyl sulfide, n-butyl ethyl sulfide, thiophene or xylene.

[0009] The beneficial effects of the present invention are as follows: The method of the present invention can realize the quantitative analysis of crude ethyl mercaptan and finished ethyl mercaptan, and can accurately quantify the components and contents of impurities in the sample. The detection method is suitable for TCD and FID detectors, wherein TCD can accurately and quantitatively analyze the contents of low-boiling impurities such as methyl mercaptan, water, H2S, ethane, methane, propane, etc.; the FID detector can analyze high-boiling impurities such as ethyl sulfide, isopropyl ethyl sulfide, n-butyl ethyl sulfide, thiophene, xylene, etc. contained in the sample; by combining and verifying the data of the two detectors, an analytical basis is provided for the accurate quantification of the contents of each component in the high-purity ethyl mercaptan product. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 The TCD standard working curve of ethyl mercaptan obtained in Example 1; Figure 2 The FID standard working curve of ethyl mercaptan obtained in Example 1; Figure 3 The TCD standard working curve of diethyl sulfide obtained in Example 1; Figure 4 The FID standard working curve of diethyl sulfide obtained in Example 1; Figure 5 The chromatogram of ethyl mercaptan obtained in Example 2; Figure 6Chromatogram of ethyl mercaptan obtained in Example 3. DETAILED DESCRIPTION

[0011] The embodiments of the present invention will be described in detail below with reference to examples. The following examples are only used to illustrate the present invention and should not be construed as limiting the scope of the present invention.

[0012] Gas chromatography detection conditions: The gas chromatograph uses DB-WAXetr strong polar polyethylene glycol capillary column as the chromatographic column; The column temperature of the gas chromatograph was set as follows: initial temperature 80°C, maintained for 5 min; then heated to 220°C at a heating rate of 20°C / min, maintained for 1 min; The maximum column box temperature is 260°C, check "cover column maximum value"; Column temperature equilibrium time: 0.25~0.5min; Injection volume: 0.2~1μL; Inlet temperature: 220°C; Inlet pressure: 4.3727 psi; Injection mode: split injection; Split ratio: 5:1; Detector: TCD or FID.

[0013] When the TCD detector is selected, the detector temperature is 225°C, the reference flow rate is 10 mL / min, the tail gas is hydrogen, the tail gas flow rate is 5 mL / min, and the hot wire state is on; When the FID detector is selected, the detector temperature is 225°C, the air flow rate is 400 mL / min, the hydrogen fuel gas flow rate is 30 mL / min, the tail gas is nitrogen, the tail gas flow rate is 25 mL / min, and the flame state is on.

[0014] Example 1 Drawing of the standard working curve of ethyl mercaptan: The standard sample of 0.2 μL, 0.4 μL, 0.6 μL, 0.8 μL and 1 μL was injected by automatic sample injector, and the corresponding standard working curve was drawn according to the injection volume and peak area. The standard working curve drawn by TCD detector is shown in the figure Figure 1 , y=5.19965×10 9 x+0,R 2 =0.99998.

[0015] The standard working curves were drawn based on the injection volume and peak area of ​​0.2 μL, 0.4 μL, 0.6 μL, 0.8 μL and 1 μL of ethanethiol standard samples using an automatic injector. The standard working curve drawn using the FID detector is shown in the figure. Figure 2 , y=1.99849×10 10 x+0,R 2 =0.99995.

[0016] Drawing of standard working curve of diethyl sulfide: The standard working curves were drawn using the TCD detector, with the injection volume and peak area being 0.2 μL, 0.4 μL, 0.6 μL, 0.8 μL and 1 μL of ethyl sulfide standard samples injected by the automatic injector. Figure 3 , y=5.30239×10 9 x+0,R 2 =0.99998.

[0017] The standard working curve was drawn based on the injection volume and peak area. The standard working curve drawn by FID detector is shown in the following figure. Figure 4 , y=3.55572×10 10 x+0,R 2 =0.99995.

[0018] Example 2 Sample pretreatment: Filter the ethyl mercaptan sample with a 0.2 μm PES filter membrane and transfer 1 ml of the liquid into a sample bottle, seal it, and place it on the automatic sampler.

[0019] Chromatographic conditions: DB-WAXetr strong polar polyethylene glycol capillary column (30m*320μm*0.5μm), column temperature 80℃ (maintained for 5min)-220℃ (maintained for 1min), heating rate 20℃ / min, TCD detector, detector temperature 225℃, reference flow 10mL / min, tail gas (hydrogen) flow 5mL / min, injection port temperature 220℃, split ratio 5:1, injection volume 0.5μL. (Results are shown in Table 1, Figure 5 ) Example 3 Sample pretreatment: Filter the ethyl mercaptan sample with a 0.2 μm PES filter membrane and transfer 1 ml of the liquid into a sample bottle, seal it, and place it on the automatic sampler.

[0020] Chromatographic conditions: DB-WAXetr strong polar polyethylene glycol capillary column (30m*320μm*0.5μm), column temperature 80℃ (maintained for 5min)-220℃ (maintained for 1min), heating rate 20℃ / min, FID detector, detector temperature 225℃, air flow rate 400mL / min, hydrogen gas flow rate 30mL / min, tail gas nitrogen, tail gas flow rate 25mL / min, injection port temperature 220℃, split ratio 5:1, injection volume 0.5μL. (Results are shown in Table 2, Figure 6 ) Table 1 Corresponding analysis data of Example 2

[0021] Table 2 Corresponding analysis data of Example 3

[0022] From the above data, it can be seen that by selecting DB-WAXetr strong polar polyethylene glycol capillary column and choosing appropriate detection parameters, both TCD detector and FID detector can detect methyl mercaptan, ethyl mercaptan, methanol, ethyl sulfide and other components, and the content of substances detected by the two detection methods is basically the same; in addition, TCD detector can also detect substances such as carbon disulfide and water, and FID detector can also detect substances such as isopropyl ethyl sulfide and thiophene. By combining the two detection methods, the test results can be mutually verified, and more trace impurity contents can be detected.

Claims

1. A quantitative analysis method for ethanethiol, characterized in that, The analysis was performed using a gas chromatograph, and the specific analysis method included the following steps: (1) Prepare standard samples and samples to be tested; (2) Analyze the standard sample using gas chromatography and draw a standard curve; (3) Analyze the sample using a gas chromatograph and calculate the ethyl mercaptan content; The gas chromatograph uses DB-WAXetr strong polar polyethylene glycol capillary column as the chromatographic column; The column temperature of the gas chromatograph was set as follows: initial temperature 80° C., maintained for 5 min; then heated to 220° C. at a heating rate of 20° C. / min, maintained for 1 min.

2. A quantitative analysis method for ethanethiol according to claim 1, characterized in that, The working conditions of gas chromatograph are: Maximum column box temperature 260°C; Column temperature equilibrium time: 0.25~0.5min; Injection volume: 0.2~1μL; Inlet temperature: 220°C; Inlet pressure: 4.3727 psi; Injection mode: split injection; Split ratio: 5:1; Detector: TCD or FID.

3. A quantitative analysis method for ethanethiol according to claim 1, characterized in that, The method for preparing the sample to be tested in step (1) is as follows: filtering the initial ethyl mercaptan with an organic filter membrane, transferring 0.5-1 mL of the filtered ethyl mercaptan into a sample bottle, and immediately sealing the bottle to obtain the ethyl mercaptan sample to be tested.

4. A quantitative analysis method for ethanethiol according to claim 1, characterized in that, During gas chromatography analysis, samples were injected using an automatic sampler.

5. A quantitative analysis method for ethanethiol according to claim 1, characterized in that, The dimensions of the chromatographic column are: length 30 m, inner diameter 0.32 mm, and film thickness 0.5 μm.

6. A quantitative analysis method for ethanethiol according to claim 2, characterized in that, When the TCD detector is selected, the detector temperature is 225°C, the reference flow rate is 10 mL / min, the tail gas is hydrogen, the tail gas flow rate is 5 mL / min, and the hot wire state is on; When the FID detector is selected, the detector temperature is 225°C, the air flow rate is 400 mL / min, the hydrogen fuel gas flow rate is 30 mL / min, the tail gas is nitrogen, the tail gas flow rate is 25 mL / min, and the flame state is on.

7. A quantitative analysis method for ethanethiol according to claim 3, characterized in that, The organic filter membrane is an organic filter membrane with a pore size of 0.2 μm, and the material of the organic filter membrane is one of PES, PTFE or PVDF.

8. A quantitative analysis method for ethanethiol according to claim 3, characterized in that, The content of ethyl mercaptan in the ethyl mercaptan sample to be tested is 98.0% to 99.9%, and the impurities include at least one of methyl mercaptan, water, H2S, ethane, methane, propane, ethyl sulfide, isopropyl ethyl sulfide, n-butyl ethyl sulfide, thiophene or xylene.

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