Method for detecting content of tributyl phosphate

Abstract

The invention belongs to the technical field of detection, and particularly relates to a method for detecting the content of tributyl phosphate. The method for detecting the content of tributyl phosphate comprises the following steps: extracting a liquid to be detected by using water, and layering to obtain an upper oil phase; and mixing the upper oil phase with isooctane, performing gas chromatography detection, and obtaining the content of tributyl phosphate according to the obtained peak area and a preset standard curve. According to the method, water is adopted as an extraction solvent, interfering substances such as phosphoric acid can be removed, TBP can be concentrated, and corrosion to a chromatographic column can be reduced due to acidity reduction. An upper-layer oil phase obtained after water extraction and isooctane are mixed and diluted, so that the viscosity of a sample can be reduced, and the separation effect on a chromatographic column can be improved; meanwhile, the blockage of a chromatographic column can be reduced, and the resolution ratio of a chromatographic peak is improved, so that the content of tributyl phosphate can be more accurately measured.

Description

Technical Field

[0001] The invention belongs to the field of detection technology, and particularly relates to a method for detecting the content of tributyl phosphate. Background Art

[0002] Tributyl phosphate, abbreviated as TBP, is a colorless liquid with a pungent odor. It is an organic compound with a chemical formula of C 12 H 27 O4P or (C4H9)3PO4. TBP has low surface tension and is insoluble in water. It is often used as an industrial defoamer. It can effectively make the foam film unstable and quickly defoam. It cannot be used in food / cosmetics.

[0003] In the production process of refined phosphoric acid products, tributyl phosphate (TBP) is often used as a complexing agent and kerosene as a diluent. The complexing extraction method is used to separate concentrated phosphoric acid or a dilute phosphoric acid solution to obtain refined phosphoric acid and a phosphoric acid extract containing kerosene. The mass content of tributyl phosphate in the phosphoric acid extract containing kerosene is generally around 55%.

[0004] TBP is used in industrial phosphoric acid purification process with high efficiency and selectivity. In order to monitor and evaluate the effect of tributyl phosphate complex extraction method, that is, to monitor the extraction efficiency, purity and possible side reactions of phosphoric acid in real time, it is necessary to determine the content of tributyl phosphate in the phosphoric acid extract containing kerosene; through accurate detection, the extraction conditions can be optimized, the purification quality of refined phosphoric acid can be improved, and the production cost and environmental risks can be reduced. The intermediate product kerosene-containing phosphoric acid extract contains phosphoric acid, kerosene, tributyl phosphate (TBP) and solid impurities. Due to the different boiling points of kerosene and phosphoric acid, the kerosene is removed by distillation. The phosphoric acid and solid impurities in the remaining phosphoric acid extract will interfere with the detection of TBP, and the detection accuracy is poor. Summary of the invention

[0005] In view of this, the object of the present invention is to provide a method for detecting the content of tributyl phosphate. The detection method of the present invention can remove interfering substances, TBP detection has no interference, has good accuracy, and is suitable for detecting the content of TBP in phosphoric acid extract.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] The present invention provides a method for detecting the content of tributyl phosphate, wherein the liquid to be tested is a phosphoric acid extract, and the detection method comprises the following steps:

[0008] The test liquid is extracted with water, and the upper oil phase is obtained by separation;

[0009] The upper oil phase and isooctane are mixed and then subjected to gas chromatography detection, and the tributyl phosphate content is obtained according to the peak area of ​​the obtained target peak and a predetermined standard curve;

[0010] The conditions for the gas chromatography detection include: the chromatographic column is a CATAL chromatographic column; programmed temperature: the initial column temperature is 50-60°C, maintained for 1 minute, then increased to 230-250°C at a rate of 15°C / min, and maintained for 4 minutes; the carrier gas is nitrogen with a flow rate of 1.0 mL / min; the injection port temperature is 245-255°C; the detector is FID, and the detector temperature is 245-255°C.

[0011] Preferably, the phosphoric acid extract contains phosphoric acid and tributyl phosphate, and the mass content of tributyl phosphate in the phosphoric acid extract is 40% to 70%.

[0012] Preferably, the programmed temperature increase is as follows: the initial column temperature is 50°C, maintained for 1 min, then increased to 230°C at a rate of 15°C / min, and maintained for 4 min.

[0013] Preferably, the mass ratio of water to the test liquid is 1-2:2, the number of extractions is 1-3 times, and the time for each extraction is 15-30 minutes.

[0014] Preferably, the extraction temperature is 65-75°C.

[0015] Preferably, the extraction is carried out under shaking conditions, and the shaking rate is 150-180 rpm.

[0016] Preferably, the mass ratio of the upper oil phase to isooctane is 1:8-12.

[0017] Preferably, the stationary phase of the CATAL chromatographic column is (5% diphenyl) diphenyl polysiloxane.

[0018] Preferably, the conditions for the gas chromatography detection also include: a hydrogen flow rate of 40 mL / min, a compressed air flow rate of 400 mL / min; and an injection volume of 1.0 μL.

[0019] Preferably, the predetermined standard curve takes the mass concentration of the tributyl phosphate standard solution as the abscissa and the corresponding peak area as the ordinate; the linear range of the standard curve is 2-10%.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The present invention provides a method for detecting the content of tributyl phosphate, wherein the liquid to be tested is a phosphoric acid extract, and the detection method comprises the following steps:

[0022] The test liquid is extracted with water, and the upper oil phase is obtained by separation;

[0023] The upper oil phase and isooctane are mixed and then subjected to gas chromatography detection, and the tributyl phosphate content is obtained according to the peak area of ​​the obtained target peak and a predetermined standard curve;

[0024] The conditions for the gas chromatography detection include: the chromatographic column is a CATAL chromatographic column; programmed temperature: the initial column temperature is 50-60°C, maintained for 1 minute, then increased to 230-250°C at a rate of 15°C / min, and maintained for 4 minutes; the carrier gas is nitrogen with a flow rate of 1.0 mL / min; the injection port temperature is 245-255°C; the detector is FID, and the detector temperature is 245-255°C.

[0025] The composition of phosphoric acid extract is complex, and there are many interfering substances, such as phosphoric acid, a small amount of kerosene, solid impurities, etc. The present invention uses water as the extraction solvent, which can remove interfering substances such as phosphoric acid and concentrate TBP, thereby improving the accuracy of analysis; and after removing phosphoric acid, the acidity of the sample solution is reduced, reducing the corrosion to the chromatographic column. The upper oil phase after water extraction is mixed with isooctane for dilution, which can reduce the viscosity of the sample and improve the separation effect on the chromatographic column; and through dilution, the blockage of the chromatographic column can be reduced, and the resolution of the chromatographic peak can be improved, thereby more accurately determining the content of tributyl phosphate. At the same time, the present invention uses a specific type of chromatographic column and a fixed heating program, and the separation effect of TBP and other substances is good, and the detection result is accurate.

[0026] The data of the examples show that the accuracy, precision and reliability of the determination method of the present invention meet the requirements. The pretreatment method of the present invention is simple and does not require a cumbersome pretreatment process. The chromatographic analysis conditions of the present invention are free of impurity interference, and the detection results are accurate and reliable. The examples use automated sampling equipment to improve analysis efficiency, reduce human operation errors, and provide reliable experimental data; batch analysis and testing can be achieved, which can not only improve the accuracy of the analysis, but also optimize the separation effect, speed up the analysis, improve repeatability and stability, and at the same time has the advantages of being environmentally friendly and having a wide range of applications. The detection method of the present invention has broad application prospects in the fields of chemical industry and environmental monitoring. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0028] Figure 1 Is the standard curve of tributyl phosphate in the embodiment;

[0029] Figure 2 Is the chromatogram of isooctane solvent in the embodiment;

[0030] Figure 3 It is the chromatogram of tributyl phosphate standard sample in the embodiment;

[0031] Figure 4 This is a chromatogram of the content of tributyl phosphate tested by isooctane dilution in the examples;

[0032] Figure 5 It is the chromatogram of GR (super pure) 99.5% tributyl phosphate in the example. DETAILED DESCRIPTION

[0033] The present invention provides a method for detecting the content of tributyl phosphate, wherein the liquid to be tested is a phosphoric acid extract, and the detection method comprises the following steps:

[0034] The test liquid is extracted with water, and the upper oil phase is obtained by separation;

[0035] The upper oil phase and isooctane are mixed and then subjected to gas chromatography detection, and the tributyl phosphate content is obtained according to the peak area of ​​the obtained target peak and a predetermined standard curve;

[0036] The conditions for the gas chromatography detection include: the chromatographic column is a CATAL chromatographic column; programmed temperature: the initial column temperature is 50-60°C, maintained for 1 minute, then increased to 230-250°C at a rate of 15°C / min, and maintained for 4 minutes; the carrier gas is nitrogen with a flow rate of 1.0 mL / min; the injection port temperature is 245-255°C; the detector is FID, and the detector temperature is 245-255°C.

[0037] In the present invention, unless otherwise specified, the materials and equipment used are commercially available products in the art.

[0038] In the present invention, the phosphoric acid extract preferably contains phosphoric acid and tributyl phosphate, and the mass content of tributyl phosphate in the phosphoric acid extract is preferably 40% to 70%, more preferably 50% to 60%.

[0039] The present invention uses water to extract the liquid to be tested, and separates the layers to obtain an upper oil phase.

[0040] In the present invention, the mass ratio of water to the liquid to be tested is preferably 1 to 2:2, the number of extractions is preferably 1 to 3 times, more preferably 2 times; the time for each extraction is preferably 15 to 30 minutes, more preferably 20 minutes. The temperature of the extraction is preferably 65 to 75°C, more preferably 70°C. The extraction is preferably carried out under oscillation conditions, and the oscillation rate is preferably 150 to 180 rpm, more preferably 165 rpm; the extraction is preferably carried out in a constant temperature oscillator. The solvent and temperature of the extraction of the present invention can remove interfering substances and concentrate TBP. The present invention uses water as the extraction solvent, which has a better impurity removal effect than sodium hydroxide solution.

[0041] In the present invention, the stratification is preferably static stratification, the lower layer after the stratification is the water phase, and the upper layer is the oil phase, and the oil phase contains TBP. The stratification is preferably carried out in a separatory funnel.

[0042] After obtaining the upper oil phase, the present invention mixes the upper oil phase with isooctane and performs gas chromatography detection, and obtains the tributyl phosphate content according to the peak area of ​​the obtained target peak and a predetermined standard curve;

[0043] The conditions for the gas chromatography detection include: the chromatographic column is a CATAL chromatographic column; programmed temperature: the initial column temperature is 50-60°C, maintained for 1 minute, then increased to 230-250°C at a rate of 15°C / min, and maintained for 4 minutes; the carrier gas is nitrogen with a flow rate of 1.0 mL / min; the injection port temperature is 245-255°C; the detector is FID, and the detector temperature is 245-255°C.

[0044] In the present invention, the mass ratio of the upper oil phase to isooctane is preferably 1:8-12, more preferably 1:9. The present invention uses isooctane and the upper oil phase to mix, which can reduce the sample viscosity and improve the separation effect on the chromatographic column; and through dilution, the blockage of the chromatographic column can be reduced, and the resolution of the chromatographic peak can be improved, so as to more accurately determine the content of tributyl phosphate. Moreover, isooctane is less toxic than acetone and is inexpensive.

[0045] In the present invention, the CATAL chromatographic column is preferably purchased from PerkinElmer, model Elite-5, 30m*0.25mm*0.25μm.

[0046] In the present invention, the injection port temperature is preferably 250°C, and the detector temperature is preferably 250°C.

[0047] In the present invention, the conditions for gas chromatography detection preferably also include: a hydrogen flow rate of 40 mL / min, a compressed air flow rate of 400 mL / min, and an injection volume of 1.0 μL.

[0048] In the present invention, the predetermined standard curve preferably uses the mass concentration of the tributyl phosphate standard solution as the abscissa and the corresponding peak area as the ordinate; the linear range of the standard curve is preferably 2-10%, and specifically preferably 2.00%, 4.93% and 8.39%. The standard substance used to prepare the tributyl phosphate standard solution is preferably tributyl phosphate provided by Qinghai Jufeng Co., Ltd.

[0049] The invention dilutes the upper oil phase with isooctane and then injects the sample, separates tributyl phosphate through a CATAL chromatographic column, and burns each component in an FID detector. The generated ion flow signal is detected by a hydrogen flame ionization detector, and the signal size is proportional to the component content. The peak area external standard method is used for quantitative analysis.

[0050] In order to further illustrate the present invention, the detection method of tributyl phosphate content provided by the present invention is described in detail below in conjunction with the accompanying drawings and examples, but they should not be construed as limiting the scope of protection of the present invention.

[0051] Example 1

[0052] A commercially available tributyl phosphate sample (Qinghai Jufeng Co., Ltd.) was selected and a PerkinElmer chromatographic column was used to analyze tributyl phosphate in phosphoric acid extract. Isooctane was selected as the dilution solvent, and the experimental steps were as follows:

[0053] 1. Instruments and reagents

[0054] Tributyl phosphate raw material, kerosene, isooctane; gas chromatograph model Clarus 690GC, equipped with FID detector.

[0055] The phosphoric acid extract comprises: phosphoric acid, tributyl phosphate, a small amount of kerosene, solid impurities, etc.; mass content: P2O58%, MgO 2.5%, Al2O30.8%, Fe2O30.1%, F 2.1%, TBP 55%, kerosene 5%, solid impurities 2%, H2O 13%.

[0056] 2. Chromatographic conditions

[0057] A chromatographic column produced by PE Company (CATAL (NO: N931676)) was used with a programmed temperature rise mode: the column temperature was initially set to 50°C, maintained for 1 min, then increased to 230°C at a rate of 15°C / min, and maintained for 4 min; the carrier gas was high-purity nitrogen with a flow rate of 1.0 mL / min; FID detection was used with a hydrogen flow rate of 40.0 mL / min and a compressed air flow rate of 400 mL / min; the injection port temperature was set to 250°C, and the detector temperature was set to 250°C; the injection volume was 1.0 μL.

[0058] 3. Sample pretreatment

[0059] Extraction liquid water extraction steps: weigh 100g of sample (to be tested extract) in a 250ml volumetric flask, accurately record the mass, weigh 50g of ultrapure water (room temperature) in the sample volumetric flask, cover the bottle stopper and put it in a constant temperature oscillator, shake at 70°C and 165rpm for 20 minutes, take out and pour the sample into a 250ml separatory funnel, collect the lower aqueous phase in a 250ml beaker with a pre-weighed mass after phase separation, collect the upper oil phase in the original 250ml sample volumetric flask, weigh 50g of ultrapure water (room temperature) in the volumetric flask, cover the bottle stopper, put it in a constant temperature oscillator and shake for 15 minutes, pour the test solution into the original 250ml separatory funnel, collect the upper oil phase for tributyl phosphate content determination after phase separation, and the stripping process is completed. The lower aqueous phase is mixed and filtered twice and weighed, which can be used to determine related items, such as P, S, F, and Fe.

[0060] Preparation of standard samples: (1) The final content of the commercially available raw material tributyl phosphate sample was measured by the area normalization method. (2) 99.55% tributyl phosphate was diluted 10 times with isooctane to obtain a standard sample. A certain amount of standard sample was weighed and standard solutions with different gradients were prepared: 2.00%, 4.93%, and 8.39%, and the standard curve was drawn by computer analysis. Figure 1 This is the standard curve of tributyl phosphate, and the standard curve r≥0.999, which meets the requirements.

[0061] 4. Determination steps

[0062] Take a 25mL volumetric flask, accurately weigh 2.5000g of the sample (upper oil phase), add 22.5000g of isooctane into the volumetric flask, cover the lid and shake well, pipette 1mL of liquid into the injection vial, and perform gas chromatography analysis. The weighing of tributyl phosphate and isooctane must be accurately recorded, and the dilution multiple is calculated according to the mass ratio.

[0063] Before sample analysis, inject 1 to 2 injections of isooctane solvent, then perform standard sample analysis, and finally wash the needle twice with isooctane.

[0064] Figure 2 This is the chromatogram of isooctane solvent. It can be seen that isooctane solvent does not contain tributyl phosphate component. Figure 3 The chromatogram of the tributyl phosphate standard sample (the raw material provided by the supplier Qinghai Jufeng Co., Ltd.) shows that the peak position of isooctane is far away from tributyl phosphate and does not interfere with the detection of tributyl phosphate; Table 1 is Figure 3 Analysis results of tributyl phosphate standard sample.

[0065] Table 1 Figure 3 Analysis results of tributyl phosphate standard sample

[0066]

[0067] It can be seen that the area normalized content of the commercially available tributyl phosphate sample is 99.55%.

[0068] 5. Experimental results and discussion

[0069] The retention time of tributyl phosphate in the standard solution with a concentration of 4.93% is 11.79 minutes, and the peak area is 40643AU. By calculating the peak area and fitting the standard curve, the content of tributyl phosphate is obtained to be 4.94%.

[0070] Figure 4 This is the chromatogram of the tributyl phosphate content test using isooctane dilution (phosphoric acid extract to be tested), and the tributyl phosphate content is 55.49%. In the intermediate control analysis content, it is necessary to set up solvent washing needle and sample rinsing.

[0071] The invention can accurately determine the content of tributyl phosphate. Compared with the traditional TBP content determination method, the method of the invention has higher accuracy and reliability, and is easy to operate and has a fast analysis speed.

[0072] Example 2

[0073] 1. According to the operating steps of Example 1, 5 samples were prepared for measurement. Each sample was measured 5 times in parallel. The results are shown in Table 2. Calculation formula: X TBP (%) = C 仪器测定值 *(m 样品 +m 异辛烷 ) / m 样品 .

[0074] Table 2 TBP parallel determination analysis results

[0075]

[0076] It can be seen that the content of tributyl phosphate in PE chromatography analysis is within the specified relative range (<5%), which meets the requirements of analytical testing.

[0077] 2. Recovery rate experiment

[0078] A known amount of tributyl phosphate was added to 2.5 g of extract (the oil phase after the pretreatment of the 3 samples in Example 1), and then diluted 10 times with isooctane. The accurate weighed masses of the sample and isooctane were recorded in detail, and the TBP content w3 of the mixed solution (mixed spiked sample) was determined. The spiked recovery was calculated according to the recovery rate = (w3-w1) / w2*100%. The results are shown in Table 3.

[0079] Table 3 Recovery test results

[0080]

[0081] It can be seen that the spiked recovery rate is in the range of 95% to 105%, and the analysis results meet the requirements.

[0082] 3. Precision experiment

[0083] About 55% tributyl phosphate standard solution was prepared for precision experiment. The experimental results are shown in Table 4.

[0084] Table 4 TBP precision determination results

[0085]

[0086]

[0087] It can be seen that the detection method of the present invention has good precision.

[0088] Example 3

[0089] 1. Standard products

[0090] Figure 3 Chromatogram of raw material tributyl phosphate provided by supplier (Qinghai Jufeng Co., Ltd.), Figure 5 This is the chromatogram of GR (super pure) 99.5% tributyl phosphate.

[0091] According to the peak effects of the two spectra, the GR tributyl phosphate spectrum has impurity peaks ( Figure 5 ), which affects the content of tributyl phosphate and is not suitable for making a standard curve. Figure 3 A standard curve was prepared using tributyl phosphate.

[0092] 2. Stability of chromatographic column

[0093] The chromatographic column is the most important instrument structure in PE chromatographic analysis. Its performance and parameters directly affect the accuracy and reliability of the analysis results.

[0094] Selecting common short columns (such as 10m×0.25mm×0.25μm) for separation, or using a chromatographic column with a larger inner diameter (0.53mm), both have low column efficiency and unsatisfactory separation effect. Finally, the present invention selects CATAL (NO: N931676) chromatographic column, which has high separation efficiency and sharp peak shape, helps to improve the resolution of the analysis, and has the best separation effect.

[0095] 3. Detector and detector temperature

[0096] In PE chromatographic analysis, the sensitivity and linear range parameters of the detector have a great influence on the analysis results. The FID detector can provide a stable and reliable signal and is particularly sensitive to the detection of low-concentration substances. Moreover, the FID detector is insensitive to temperature changes. Therefore, the present invention selects the FID detector to analyze the TBP content.

[0097] When the detector temperature is set to a relatively low 200°C, the detection sensitivity decreases and the noise increases, which affects the accuracy of the analysis. When the detector temperature is increased to 300°C, the baseline drift is serious and the stability deteriorates. Therefore, the detector temperature of the present invention is set to 245-255°C.

[0098] 4. Inlet temperature

[0099] If the injection port temperature is set to 200°C, it is found that some high-boiling point components are not completely vaporized, affecting the accuracy of quantitative analysis. When the injection port temperature is increased to 300°C, the sample decomposes and produces impurity peaks.

[0100] 5. Column temperature program

[0101] If a single constant column temperature of 230°C is used, TBP and impurity components cannot be completely separated, and the peaks overlap seriously. If the heating rate is adjusted to 30°C / min, the separation degree of TBP and impurity components becomes worse.

[0102] The method for detecting the content of tributyl phosphate of the present invention requires strict control of the instrument injection port, column temperature, detector temperature, and carrier gas pressure to avoid the influence of temperature fluctuation and pressure fluctuation on the analysis result.

[0103] 6. Effect of sample pretreatment extraction temperature

[0104] When the extraction temperature is lower than 65°C, the extraction time is prolonged; when the extraction temperature is higher than 75°C, TBP may begin to thermally decompose, affecting the accuracy of the analysis results, and the temperature increase will also increase the safety risk. At the extraction temperature (65-75°C) of the present invention, the extraction efficiency and reproducibility of TBP are good.

[0105] Comparative Example 1

[0106] As a strong base, sodium hydroxide can effectively react with the acidic impurities in phosphoric acid to generate soluble salts, thus achieving a purification effect. Table 5 shows the experimental results of alkali extraction and water extraction:

[0107] Table 5 Experimental results using alkali extraction and water extraction

[0108] method P205％ F％ Fe% <![CDATA[SO4 2- %]]> Alkali Extraction 7.94 0.0486 0.0072 0.1529 Water Extract 8.02 0.0401 0.0079 0.1616 Alkali Extraction 7.80 0.0487 0.0064 0.1534 Water Extract 8.01 0.0439 0.0067 0.1562 Alkali Extraction 7.91 0.0479 0.0073 0.1511 Water Extract 7.88 0.0462 0.0077 0.1528

[0109] It can be seen from Table 5 that the results of alkaline extraction and water extraction are similar, but alkaline extraction is only suitable for removing acidic impurities in phosphoric acid. The amount of sodium hydroxide used needs to be strictly controlled. Excessive use may cause the loss of effective ingredients in phosphoric acid and generate a large amount of waste liquid, which requires subsequent treatment.

[0110] The present invention uses 70°C hot water as a mild extractant, which has little effect on phosphoric acid and can effectively remove organic impurities in phosphoric acid, such as kerosene, etc. The invention is simple to operate, environmentally friendly and low in cost.

[0111] Although the above-mentioned embodiments have made a detailed description of the present invention, they are only some embodiments of the present invention, rather than all embodiments. People can also obtain other embodiments based on the embodiments of the present invention without creative work, and these embodiments all fall within the scope of protection of the present invention.

Claims

1. A method for detecting the content of tributyl phosphate, wherein the test liquid is a phosphoric acid extract, characterized in that: The detection method includes the following steps: The test liquid is extracted with water, and the upper oil phase is obtained by separation; The upper oil phase and isooctane are mixed and then subjected to gas chromatography detection, and the tributyl phosphate content is obtained according to the peak area of ​​the obtained target peak and a predetermined standard curve; The conditions for the gas chromatography detection include: the chromatographic column is a CATAL chromatographic column; programmed temperature: the initial column temperature is 50-60°C, maintained for 1 minute, then increased to 230-250°C at a rate of 15°C / min, and maintained for 4 minutes; the carrier gas is nitrogen with a flow rate of 1.0 mL / min; the injection port temperature is 245-255°C; the detector is FID, and the detector temperature is 245-255°C.

2. The detection method according to claim 1, characterized in that: The phosphoric acid extract contains phosphoric acid and tributyl phosphate, and the mass content of tributyl phosphate in the phosphoric acid extract is 40% to 70%.

3. The detection method according to claim 1, characterized in that: The temperature program was as follows: the initial column temperature was 50°C, maintained for 1 min, then increased to 230°C at a rate of 15°C / min, and maintained for 4 min.

4. The detection method according to claim 1, characterized in that: The mass ratio of water to the liquid to be tested is 1-2:2, the number of extractions is 1-3 times, and the time for each extraction is 15-30 minutes.

5. The detection method according to claim 1 or 4, characterized in that: The extraction temperature is 65-75°C.

6. The detection method according to claim 5, characterized in that: The extraction is carried out under shaking conditions, and the shaking rate is 150-180 rpm.

7. The detection method according to claim 1, characterized in that: The mass ratio of the upper oil phase to isooctane is 1:8-12.

8. The detection method according to claim 1, characterized in that: The stationary phase of the CATAL chromatographic column is (5% diphenyl) diphenyl polysiloxane.

9. The detection method according to claim 1 or 8, characterized in that: The conditions for the gas chromatography detection also include: a hydrogen flow rate of 40 mL / min, a compressed air flow rate of 400 mL / min; and an injection volume of 1.0 μL.

10. The detection method according to claim 1, characterized in that: The predetermined standard curve takes the mass concentration of the tributyl phosphate standard solution as the abscissa and the corresponding peak area as the ordinate; the linear range of the standard curve is 2-10%.

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