Method for measuring content of 2-ethylhexyl chloroformate

Abstract

The invention provides a method for measuring the content of 2-ethylhexyl chloroformate. The determination method comprises the following steps: S1, setting the working conditions of a gas chromatograph: the pressure of carrier gas is 5.2676-6.0577 psi, the temperature of a vaporizing chamber is 200-230 DEG C, the column temperature is 50-280 DEG C, and the temperature of a detector is 250-280 DEG C; step S2, detecting the chloroformic acid-2-ethylhexyl ester sample by adopting a gas chromatograph, and collecting data; and step S3, calculating the content of the chloroformic acid-2-ethylhexyl ester. According to the application, the pressure of the carrier gas, the temperature of the vaporizing chamber, the column temperature and the temperature of the detector are set in the range, so that each component in the chloroformic acid-2-ethylhexyl ester sample can be better separated, and the precision and the accuracy of a detection result can be improved. And the determination method provided by the invention is safe to operate and pollution-free.

Description

Technical Field

[0001] The invention relates to the field of analytical technology, and in particular to a method for determining the content of 2-ethylhexyl chloroformate. Background Art

[0002] The enterprise standard for the determination method of 2-ethylhexyl chloroformate content is as follows: standard number: Q / 12HG6890-2018, and the detection method is: chemical titration (precipitation titration). Specifically, free chlorine: the sample reacts with water to release hydrogen chloride free in the water, and the free chlorine reacts quantitatively with excess silver nitrate to form a silver chloride precipitate, and then the amount of remaining silver nitrate is determined using an ammonium thiocyanate standard solution with ammonium ferric sulfate as an indicator, thereby calculating the content of free chlorine. Total chlorine: the sample is added with sodium hydroxide to produce an alkaline hydrolysis reaction of the ester to generate the corresponding alcohol and sodium chloride, and the sodium chloride reacts quantitatively with excess silver nitrate to form a silver chloride precipitate, and then the amount of remaining silver nitrate is determined using an ammonium thiocyanate standard solution with ammonium ferric sulfate as an indicator, thereby calculating the content of total chlorine. The content of 2-ethylhexyl chloroformate is calculated based on the difference between total chlorine and free chlorine.

[0003] The above method takes a long time to analyze, consumes many types of reagents, produces laboratory waste, and has low accuracy and precision in the results. In addition, this method cannot measure the amount of residual raw materials and by-products in the reaction. Summary of the invention

[0004] The main purpose of the present invention is to provide a method for determining the content of 2-ethylhexyl chloroformate, so as to solve the problem that the accuracy and precision of the measurement results of the method for determining the content of 2-ethylhexyl chloroformate in the prior art are not high.

[0005] In order to achieve the above-mentioned object, according to one aspect of the present invention, a method for determining the content of 2-ethylhexyl chloroformate is provided, and the method comprises the following steps: step S1, setting the working conditions of a gas chromatograph: the pressure of the carrier gas is 5.2676-6.0577 psi, the temperature of the vaporization chamber is 200-230°C, the column temperature is 50-280°C, and the temperature of the detector is 250-280°C; step S2, using a gas chromatograph to detect a 2-ethylhexyl chloroformate sample and collect data; step S3, calculating the content of 2-ethylhexyl chloroformate.

[0006] Furthermore, in the above step S1, the column temperature is programmed, and the programmed temperature increase process includes: the initial temperature is 50-70°C, after maintaining for 0-2 min, the temperature is increased to 70-90°C at a heating rate of 10-15°C / min; after maintaining at 70-90°C for 0-3 min, the temperature is increased to 250-280°C at a heating rate of 15-20°C / min, and maintained for 2-4 min.

[0007] Furthermore, in the above step S1, the split ratio of the gas chromatograph is set to 20-40:1.

[0008] Furthermore, in the above step S1, the working conditions of the gas chromatograph also include: the flow rate of the tail gas is 25-35 mL / min, the flow rate of the fuel gas is 30-40 mL / min, and the flow rate of the supporting gas is 300-400 mL / min; preferably, the carrier gas is nitrogen; and / or, the tail gas is nitrogen; and / or, the fuel gas is hydrogen; and / or, the supporting gas is air.

[0009] Furthermore, in the above step S1, the chromatographic column of the gas chromatograph is an HP-5 capillary chromatographic column, the length of the HP-5 capillary chromatographic column is 30m; and / or the inner diameter of the HP-5 capillary chromatographic column is 0.32mm; and / or the film thickness of the HP-5 capillary chromatographic column is 0.25-0.50μm.

[0010] Furthermore, in the above step S1, the detector is a hydrogen flame ionization detector.

[0011] Furthermore, in the above step S3, the content of 2-ethylhexyl chloroformate is calculated by area normalization method.

[0012] Furthermore, in the above step S2, the injection method of the 2-ethylhexyl chloroformate sample is automatic injection; and / or the injection rate of the 2-ethylhexyl chloroformate sample is 300 to 500 μL / min.

[0013] Furthermore, in the above step S2, the injection volume of the 2-ethylhexyl chloroformate sample is 0.2 to 0.4 μL.

[0014] Further, in the above step S2, the 2-ethylhexyl chloroformate sample includes, by mass percentage, 0-0.020wt% of isooctane chloride, 0-0.500wt% of isooctyl alcohol, 0-0.500wt% of diisooctyl carbonate, 0-0.050wt% of dioctyl sulfite and the remainder of 2-ethylhexyl chloroformate; and / or, the retention time of isooctane chloride is 8.04-8.14min; and / or, the retention time of isooctyl alcohol is 8.20-8.50min; and / or, the retention time of 2-ethylhexyl chloroformate is 10.07-10.98min; and / or, the retention time of diisooctyl carbonate is 16.48-16.88min; and / or, the retention time of dioctyl sulfite is 17.89-18.10min.

[0015] The technical scheme of the present invention is applied, and the application uses gas chromatography to determine the content of 2-ethylhexyl chloroformate in 2-ethylhexyl chloroformate sample. Compared with the 2-ethylhexyl chloroformate content determination method in the prior art, the 2-ethylhexyl chloroformate sample of the present application does not need pretreatment, can be directly sampled, and has no loss in sample preparation. The pressure of the carrier gas, the temperature of the vaporization chamber, the column temperature and the temperature of the detector are set in the above range, which helps to separate the components in the 2-ethylhexyl chloroformate sample better, thereby helping to improve the precision and accuracy of the test result. And the determination method of the present application is safe and pollution-free. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The drawings constituting a part of the present application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0017] Figure 1 The gas chromatogram of the first detection of the 2-ethylhexyl chloroformate sample in Example 1 of the present application is shown. DETAILED DESCRIPTION

[0018] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0019] As analyzed in the background technology of this application, the method for determining the content of 2-ethylhexyl chloroformate in the prior art has the problem of low accuracy and precision of the measurement results. In order to solve the above problems, this application provides a method for determining the content of 2-ethylhexyl chloroformate.

[0020] In a typical embodiment of the present application, a method for determining the content of 2-ethylhexyl chloroformate is provided, and the method comprises the following steps: Step S1, setting the working conditions of the gas chromatograph: the pressure of the carrier gas is 5.2676-6.0577 psi, the temperature of the vaporization chamber is 200-230°C, the column temperature is 50-280°C, and the temperature of the detector is 250-280°C; Step S2, using the gas chromatograph to detect the 2-ethylhexyl chloroformate sample and collect data; Step S3, calculating the content of 2-ethylhexyl chloroformate.

[0021] The application uses gas chromatography to determine the content of 2-ethylhexyl chloroformate in 2-ethylhexyl chloroformate sample. Compared with the 2-ethylhexyl chloroformate content determination method in the prior art, the 2-ethylhexyl chloroformate sample of the application does not need pretreatment, can be directly sampled, and has no loss in sample preparation. The application sets the pressure of the carrier gas, the temperature of the vaporization chamber, the column temperature and the temperature of the detector within the above range, which helps to better separate the components in the 2-ethylhexyl chloroformate sample, thereby helping to improve the precision and accuracy of the test results. And the assay method of the application is safe and pollution-free.

[0022] In one embodiment of the present application, in the above step S1, the column temperature is programmed, and the programmed temperature increase process includes: the initial temperature is 50-70°C, after maintaining for 0-2 minutes, the temperature is increased to 70-90°C at a heating rate of 10-15°C / min; after maintaining at 70-90°C for 0-3 minutes, the temperature is increased to 250-280°C at a heating rate of 15-20°C / min, and maintained for 2-4 minutes.

[0023] The programmed temperature can gradually optimize the separation conditions according to the boiling point characteristics of the compounds, so that both low-boiling point and high-boiling point compounds can be separated under the best conditions. The conditions for controlling the programmed temperature to be preferably within the above range are helpful for separating 2-ethylhexyl chloroformate and its related low-boiling point byproducts and high-boiling point residues, thereby helping to improve the precision and accuracy of the test results.

[0024] In one embodiment of the present application, in the above step S1, the split ratio of the gas chromatograph is set to 20-40:1.

[0025] The setting of the split ratio helps to keep the sample amount entering the detector at a relatively stable level. It is preferred to control the split ratio of the gas chromatograph within the above range, which helps to reduce the nonlinearity or saturation of the detector response caused by sample overload, thereby helping to improve the accuracy and repeatability of the detection results.

[0026] In one embodiment of the present application, in the above step S1, the working conditions of the gas chromatograph also include: the flow rate of the tail gas is 25-35 mL / min, the flow rate of the fuel gas is 30-40 mL / min, and the flow rate of the supporting gas is 300-400 mL / min; preferably, the carrier gas is nitrogen; and / or, the tail gas is nitrogen; and / or, the fuel gas is hydrogen; and / or, the supporting gas is air.

[0027] Controlling the flow rate of the tail gas within the above range helps to increase the stability of the detector, reduce noise, and improve detection sensitivity. Nitrogen is selected as the tail gas to help reduce the cost of detection. Controlling the flow rate of the fuel gas within the above range helps to produce a stable flame, improve ionization efficiency, and thus improve detection sensitivity. Controlling the flow rate of the auxiliary gas within the above range improves the signal strength of the detector.

[0028] In one embodiment of the present application, the above-mentioned programmed temperature rise process includes: an initial temperature of 50°C, maintained for 0 min, and then heated to 70°C at a heating rate of 10°C / min; maintained at 70°C for 0 min, and then heated to 250°C at a heating rate of 15°C / min, and maintained for 2 min; the flow rate of the tail gas is 25 mL / min, the flow rate of the fuel gas is 30 mL / min, and the flow rate of the supporting gas is 300 mL / min.

[0029] In one embodiment of the present application, in the above step S1, the chromatographic column of the gas chromatograph is an HP-5 capillary chromatographic column, the length of the HP-5 capillary chromatographic column is 30m; and / or, the inner diameter of the HP-5 capillary chromatographic column is 0.32mm; and / or, the film thickness of the HP-5 capillary chromatographic column is 0.25-0.50μm.

[0030] It is preferred to control the parameters of the chromatographic column within the above range, which helps to improve the separation efficiency, resolution, and sensitivity of the analysis, while reducing sample loss and analysis costs, shortening analysis time, and enhancing the versatility and adaptability of the method.

[0031] In one embodiment of the present application, in the above step S1, the detector is a hydrogen flame ionization detector.

[0032] The use of hydrogen flame ionization detector helps to improve the sensitivity, stability, accuracy and efficiency of the determination of 2-ethylhexyl chloroformate content, and reduce the sample pretreatment and analysis costs.

[0033] In one embodiment of the present application, in the above step S3, the content of 2-ethylhexyl chloroformate is calculated using the area normalization method.

[0034] Preferably, the area normalization method is used to calculate the content of 2-ethylhexyl chloroformate, which helps to quickly calculate the content of 2-ethylhexyl chloroformate, thereby helping to improve the efficiency of measurement. The mass content of 2-ethylhexyl chloroformate in the 2-ethylhexyl chloroformate sample=(peak area of ​​2-ethylhexyl chloroformate / sum of peak areas of 2-ethylhexyl chloroformate and impurities)×100%.

[0035] In one embodiment of the present application, in the above step S2, the injection method of the 2-ethylhexyl chloroformate sample is automatic injection; and / or the injection rate of the 2-ethylhexyl chloroformate sample is 300-500 μL / min.

[0036] The automatic sampler can accurately control the injection volume, which helps to avoid the volume error and operation variation that may be caused by manual injection, thereby helping to improve the accuracy and repeatability of the analysis. Controlling the injection rate of 2-ethylhexyl chloroformate sample within the above range helps to improve the precision and accuracy of the test results.

[0037] In order to remove the residual water in the 2-ethylhexyl chloroformate sample, thereby improving the precision and accuracy of the test results, in one embodiment of the present application, in the above step S2, the 2-ethylhexyl chloroformate sample is placed in a sample injection bottle containing anhydrous sodium carbonate, and the sample injection bottle is placed in the sample injection tray of the automatic sampler for automatic injection. Preferably, the mass ratio of the 2-ethylhexyl chloroformate sample to the anhydrous sodium carbonate is 1:0.2-0.3.

[0038] In one embodiment of the present application, in the above step S2, the injection volume of the 2-ethylhexyl chloroformate sample is 0.2-0.4 μL.

[0039] Controlling the injection volume of the 2-ethylhexyl chloroformate sample within the above range can help reduce the overload of the sample on the chromatographic column, help improve the uniformity of the distribution of the sample in the chromatographic column, and reduce the probability of peak broadening and peak overlap, thereby helping to improve the sensitivity and accuracy of detection.

[0040] In one embodiment of the present application, in the above step S2, the 2-ethylhexyl chloroformate sample includes, by mass percentage, 0-0.020wt% of isooctane chloride, 0-0.500wt% of isooctyl alcohol, 0-0.500wt% of diisooctyl carbonate, 0-0.050wt% of dioctyl sulfite and the remainder of 2-ethylhexyl chloroformate; and / or, the retention time of isooctane chloride is 8.04-8.14min; and / or, the retention time of isooctyl alcohol is 8.20-8.50min; and / or, the retention time of 2-ethylhexyl chloroformate is 10.07-10.98min; and / or, the retention time of diisooctyl carbonate is 16.48-16.88min; and / or, the retention time of dioctyl sulfite is 17.89-18.10min.

[0041] The measurement method of the present application can accurately and quickly detect 2-ethylhexyl chloroformate samples within the above content range.

[0042] The beneficial effects of the present application will be further illustrated below in conjunction with embodiments.

[0043] Example 1

[0044] 1. Reagents and instruments

[0045] Reagent: Industrially produced 2-ethylhexyl chloroformate.

[0046] Carrier gas: nitrogen.

[0047] Make-up gas: nitrogen.

[0048] Gas: Hydrogen.

[0049] Supporting gas: air.

[0050] Gas chromatograph: Instrument sensitivity and stability shall comply with the requirements of 6.3 and 6.4 of GB / T9722-2006.

[0051] Detector: Hydrogen flame ionization detector.

[0052] Chromatography workstation; Agilent workstation.

[0053] Capillary column: HP-5 capillary column, 30 m × 0.32 mm (id), film thickness 0.25 μm.

[0054] 2. Detection steps

[0055] Step S1, setting the working conditions of the gas chromatograph: using an HP-5 capillary column, setting the pressure of the carrier gas to 5.2676 psi, the tail gas flow rate to 25 mL / min, the fuel gas flow rate to 30 mL / min, the auxiliary gas flow rate to 300 mL / min, the temperature of the vaporization chamber to 200°C, the column temperature to program temperature increase, and the program temperature increase conditions: initial temperature 50°C, hold for 0 min, increase the temperature to 70°C at a heating rate of 10°C / min, hold for 0 min, then increase the temperature to 250°C at a heating rate of 15°C / min, hold for 2 min, the detector temperature is 250°C, and the split ratio is 20:1;

[0056] Step S2, putting the 2-ethylhexyl chloroformate sample into a sampling bottle containing anhydrous sodium carbonate, placing the sampling bottle in the sampling tray of the automatic sampler for automatic injection, the mass ratio of the 2-ethylhexyl chloroformate sample to the anhydrous sodium carbonate is 1:0.2, the injection volume is 0.2 μL, and the injection rate is 300 μL / min;

[0057] Step S3, using the integration function of the Agilent workstation and the area normalization method to calculate the content of each component in the 2-ethylhexyl chloroformate sample.

[0058] Four batches of 2-ethylhexyl chloroformate samples, batch numbers 1#, 2#, 3# and 4#, were measured three times in parallel by gas chromatography to obtain the gas chromatogram of 2-ethylhexyl chloroformate. The gas chromatogram obtained by the first measurement is shown in FIG. Figure 1 .

[0059] from Figure 1 It can be seen that the main peak appears at the retention time of 10.58min, indicating that the peak with a retention time of 10.58min is 2-ethylhexyl chloroformate, the peak with a retention time of 8.12min is isooctane chloride, the peak with a retention time of 8.24min is isooctyl alcohol, the peak with a retention time of 16.68min is diisooctyl carbonate, and the peak with a retention time of 17.89min is dioctyl thionyl ester.

[0060] The area normalization method was used to calculate the content of 2-ethylhexyl chloroformate in the gas chromatogram obtained above. The calculation results are shown in Table 1.

[0061] Table 1

[0062]

[0063]

[0064] Example 2

[0065] The difference from Example 1 is that the pressure of the carrier gas is set to 6.0577 psi, the temperature of the vaporization chamber is set to 230° C., and the temperature of the detector is set to 280° C. The test results are shown in Table 2.

[0066] Table 2

[0067]

[0068] Example 3

[0069] The difference from Example 1 is that the programmed temperature conditions are: initial temperature 70°C, hold for 2 min, heat to 90°C at a heating rate of 15°C / min, hold for 3 min, heat to 280°C at a heating rate of 20°C / min, hold for 4 min. The test results are shown in Table 3.

[0070] Table 3

[0071]

[0072] Example 4

[0073] The difference from Example 1 is that the programmed temperature rising conditions are: initial temperature 40°C, hold for 0 min, heat to 60°C at a heating rate of 5°C / min, hold for 0 min, heat to 220°C at a heating rate of 10°C / min, hold for 0 min. The test results are shown in Table 4.

[0074] Table 4

[0075]

[0076]

[0077] Example 5

[0078] The difference from Example 1 is that the split ratio is 40:1. The test results are shown in Table 5.

[0079] Table 5

[0080]

[0081] Example 6

[0082] The difference from Example 1 is that the split ratio is 10:1. The test results are shown in Table 6.

[0083] Table 6

[0084]

[0085]

[0086] Example 7

[0087] The difference from Example 1 is that the flow rate of the tail gas is 35 mL / min, the flow rate of the fuel gas is 40 mL / min, and the flow rate of the supporting gas is 400 mL / min. The test results are shown in Table 7.

[0088] Table 7

[0089]

[0090] Example 8

[0091] The difference from Example 1 is that the flow rate of the tail gas is 40 mL / min, the flow rate of the fuel gas is 50 mL / min, and the flow rate of the supporting gas is 450 mL / min. The test results are shown in Table 8.

[0092] Table 8

[0093]

[0094] Example 9

[0095] The difference from Example 1 is that the film thickness of the HP-5 capillary chromatographic column is 0.50 μm. The test results are shown in Table 9.

[0096] Table 9

[0097]

[0098] Example 10

[0099] The difference from Example 1 is that the film thickness of the HP-5 capillary chromatographic column is 1.0 μm. The test results are shown in Table 10.

[0100] Table 10

[0101]

[0102] Comparative Example 1

[0103] The difference from Example 1 is that the pressure of the carrier gas is set to 4.4775 psi, the temperature of the vaporization chamber is set to 170° C., and the temperature of the detector is set to 220° C. The test results are shown in Table 11.

[0104] Table 11

[0105]

[0106]

[0107] Comparative Example 2

[0108] The difference from Example 1 is that the measurement is performed using the measurement method of standard number: Q / 12HG6890-2018, and the measurement results are shown in Table 12.

[0109] Table 12

[0110]

[0111] It can be seen from the results of the embodiments and comparative examples in Tables 1 to 12 that the determination method of the present application has high repeatability, stability and accuracy, and can also detect the type and content of impurities in the 2-ethylhexyl chloroformate sample. However, it can be seen from the results of Comparative Example 2 that the result data of the detection method using the prior art are quite different, the stability, consistency and accuracy of the detection are poor, and it is difficult to detect the specific type and content of the impurities.

[0112] From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects:

[0113] The application uses gas chromatography to determine the content of 2-ethylhexyl chloroformate in 2-ethylhexyl chloroformate sample. Compared with the 2-ethylhexyl chloroformate content determination method in the prior art, the 2-ethylhexyl chloroformate sample of the application does not need pretreatment, can be directly sampled, and has no loss in sample preparation. The application sets the pressure of the carrier gas, the temperature of the vaporization chamber, the column temperature and the temperature of the detector within the above range, which helps to better separate the components in the 2-ethylhexyl chloroformate sample, thereby helping to improve the precision and accuracy of the test results. And the assay method of the application is safe and pollution-free.

[0114] The above are only embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for determining the content of 2-ethylhexyl chloroformate, characterized in that: The determination method comprises the following steps: Step S1, setting the working conditions of the gas chromatograph: the pressure of the carrier gas is 5.2676-6.0577 psi, the temperature of the vaporization chamber is 200-230° C., the column temperature is 50-280° C., and the temperature of the detector is 250-280° C.; Step S2, using the gas chromatograph to detect the 2-ethylhexyl chloroformate sample and collect data; Step S3, calculating the content of 2-ethylhexyl chloroformate.

2. The measuring method according to claim 1, characterized in that In step S1, the column temperature is programmed, and the process of programmed temperature increase includes: Initial temperature is 50-70℃, keep it for 0-2min, then increase the temperature to 70-90℃ at a rate of 10-15℃ / min; After maintaining at 70-90°C for 0-3 min, increase the temperature to 250-280°C at a heating rate of 15-20°C / min and maintain for 2-4 min.

3. The measuring method according to claim 1 or 2, characterized in that In the step S1, the split ratio of the gas chromatograph is set to 20-40:

1.

4. The measuring method according to any one of claims 1 to 3, characterized in that In step S1, the working conditions of the gas chromatograph also include: the flow rate of the tail gas is 25-35 mL / min, the flow rate of the fuel gas is 30-40 mL / min, and the flow rate of the auxiliary gas is 300-400 mL / min; Preferably, the carrier gas is nitrogen; and / or the tail gas is nitrogen; and / or the fuel gas is hydrogen; and / or the supporting gas is air.

5. The measuring method according to any one of claims 1 to 4, characterized in that In step S1, the chromatographic column of the gas chromatograph is a HP-5 capillary chromatographic column, the length of the HP-5 capillary chromatographic column is 30m; and / or the inner diameter of the HP-5 capillary chromatographic column is 0.32mm; and / or the film thickness of the HP-5 capillary chromatographic column is 0.25-0.50μm.

6. The measuring method according to any one of claims 1 to 5, characterized in that In the step S1, the detector is a hydrogen flame ionization detector.

7. The measuring method according to any one of claims 1 to 6, characterized in that In the step S3, the content of 2-ethylhexyl chloroformate is calculated by using the area normalization method.

8. The measuring method according to any one of claims 1 to 7, characterized in that In the step S2, the injection method of the 2-ethylhexyl chloroformate sample is automatic injection; and / or the injection rate of the 2-ethylhexyl chloroformate sample is 300 to 500 μL / min.

9. The measuring method according to any one of claims 1 to 8, characterized in that In the step S2, the injection volume of the 2-ethylhexyl chloroformate sample is 0.2 to 0.4 μL.

10. The measuring method according to any one of claims 1 to 9, characterized in that In the step S2, the 2-ethylhexyl chloroformate sample includes, by mass percentage, 0-0.020 wt% of isooctane chloride, 0-0.500 wt% of isooctyl alcohol, 0-0.500 wt% of diisooctyl carbonate, 0-0.050 wt% of dioctyl sulfite, and the balance of 2-ethylhexyl chloroformate; And / or, the retention time of the chloroisooctane is 8.04 to 8.14 min; and / or, the retention time of the isooctyl alcohol is 8.20 to 8.50 min; and / or, the retention time of the 2-ethylhexyl chloroformate is 10.07 to 10.98 min; and / or, the retention time of the diisooctyl carbonate is 16.48 to 16.88 min; and / or, the retention time of the dioctyl sulfite is 17.89 to 18.10 min.

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