Method for detecting tributyl phosphate in phosphogypsum

Abstract

The invention discloses a method for detecting tributyl phosphate in ardealite. The method comprises the following steps: during sample pretreatment, treating an ardealite raw material or the ardealite subjected to innocent treatment to obtain an ardealite leachate; measuring the content of soluble non-orthophosphate in the ardealite leaching solution; selecting a dilution ratio according to the content of soluble non-orthophosphate to obtain a diluted sample solution; adding a substitute tripropyl phosphate-D21 into the diluted sample solution, extracting by using an n-hexane-acetone mixed solvent as an extracting agent, collecting an upper organic phase, concentrating, redissolving by using n-hexane, loading the sample to an activated HLB small column, eluting by using the n-hexane-acetone mixed solvent, and fixing the volume to obtain a sample to be detected; then, a GC / MS method is adopted for determination, an internal standard method is adopted for constructing a quantitative calibration curve, and the quantitative internal standard is tributyl phosphate-D27. According to the method, the solid phase extraction-gas phase mass spectrometry is used for detecting the content of the tributyl phosphate in the phosphogypsum system for the first time, and the detection sensitivity and accuracy are improved.

Description

Technical Field

[0001] This invention belongs to the field of environmental chemical analysis and detection technology of organophosphates in solid waste leachate, specifically a method for detecting tributyl phosphate in phosphogypsum leachate. Background Technology

[0002] Phosphogypsum is an industrial byproduct of the wet-process phosphoric acid production. Impurities in phosphogypsum (mainly phosphorus and fluorine) are a significant factor restricting its comprehensive utilization. Tributyl phosphate may be introduced as a phosphoric acid extraction agent in the upstream production process, becoming an organic phosphorus impurity in the phosphogypsum and thus affecting its resource utilization. The composition of phosphogypsum leachate is complex, strongly interfering with the target compounds. Current technology lacks a precise quantitative method for tributyl phosphate in phosphogypsum leachate. Chinese patent application CN 119178829 A discloses a method for detecting tributyl phosphate content in salt lake brine using GC / MS. However, the pretreatment method used in this patent for detecting tributyl phosphate in brine is not applicable to the detection of tributyl phosphate in phosphogypsum systems, and the measurement conditions also vary considerably. Therefore, it is necessary to explore new detection conditions and develop a new detection method. Summary of the Invention

[0003] The purpose of this invention is to establish a highly sensitive, accurate, and efficient method for determining tributyl phosphate in phosphogypsum systems. This method will be applied to the monitoring of tributyl phosphate content in phosphogypsum systems to promote the comprehensive utilization of phosphogypsum. This objective is achieved through the following technical solution: A method for detecting tributyl phosphate in phosphogypsum includes two parts: sample pretreatment and GC / MS determination. The sample pretreatment includes the following steps: Preparation of S1 leachate and determination of soluble non-orthophosphate content: Phosphogypsum raw material or harmlessly treated phosphogypsum was treated according to the "Solid Waste Leaching Toxicity Leaching Method Horizontal Oscillation Method" (HJ 557-2010) to obtain phosphogypsum leachate; and the soluble non-orthophosphate content in the phosphogypsum leachate was determined. Dilution of S2 leachate: The dilution ratio is selected according to the soluble non-orthophosphate content to obtain a diluted sample solution; specifically, the dilution ratio is selected according to the soluble non-orthophosphate content as follows: for soluble non-orthophosphate content > 0 and < 1 mg / L, the dilution factor is 1; for soluble non-orthophosphate content ≥ 1 mg / L and ≤ 10 mg / L, the dilution factor is 5 to 10; for soluble non-orthophosphate content > 10 mg / L, the dilution factor is 50 to 100. Preparation of S3 test sample: Tripropyl phosphate-D, a substitute, was added to the diluted sample solution obtained in S2. 21Extraction was then performed using a hexane-acetone mixed solvent as the extractant, wherein the volume ratio of hexane to acetone was 1:1; the upper organic phase was collected, concentrated, redissolved in hexane, loaded onto an activated HLB column, eluted with the hexane-acetone mixed solvent, the eluent was collected, and the volume was adjusted to obtain the sample to be tested. The GC / MS method was used to determine the following: a quantitative calibration curve was constructed using the internal standard method, with tributyl phosphate-D as the internal standard. 27 .

[0004] Further optimization involves S1, where phosphogypsum raw material is processed according to the "Solid Waste Leaching Toxicity Leaching Method - Horizontal Oscillation Method" (HJ 557-2010) to obtain phosphogypsum leachate. The content of soluble total phosphate and soluble orthophosphate in the leachate is determined according to the "Water and Wastewater Monitoring and Analysis Methods (Fourth Edition)". The difference between the two is the content of soluble non-orthophosphate. Alternatively, after harmless treatment, phosphogypsum is processed according to the HJ 557-2010 method to obtain leachate. The content of soluble total phosphate and soluble orthophosphate is determined according to the "Water and Wastewater Monitoring and Analysis Methods (Fourth Edition)". The difference between the two is the content of soluble non-orthophosphate.

[0005] Furthermore, in S3, 20 μL of the 100 μg / mL substitute tripropyl phosphate-D was added to the diluted sample obtained in S2. 21 The sample was then extracted three times with 20 mL of a hexane-acetone mixed solvent as the extractant, with a volume ratio of 1:1. The upper organic phase was collected, concentrated by rotary evaporation, and redissolved in hexane to 2 mL. The solution was loaded onto an activated HLB column, soaked for 5 min, and eluted with 5 mL of the hexane-acetone mixed solvent. The eluent was collected and diluted to 10 mL to obtain the sample to be tested.

[0006] Furthermore, in S3, an internal standard method was used to construct a quantitative calibration curve for tributyl phosphate and its substitute tripropyl phosphate-D. 21 The concentrations are between 0 and 1000 μg / L, for tributyl phosphate and its substitute tripropyl phosphate-D. 21 A 1:1 volume ratio of n-hexane to acetone mixture was used as the solvent to prepare the calibration curve.

[0007] Furthermore, in S3, a quantitative calibration curve was constructed using the internal standard method, with the internal standard being tributyl phosphate-D. 27 The concentration is 300~500 μg / L.

[0008] Furthermore, in S3, concentration is achieved using rotary evaporation or nitrogen blowing.

[0009] Furthermore, during GC / MS determination, Chromatographic conditions: Column: HP-5ms capillary column, 30 m × 0.25 mm × 0.25 μm; carrier gas: helium, flow rate: 1 mL / min; inlet temperature: 280℃; transfer line temperature: 280℃; splitless injection mode; injection volume: 1.0 μL; temperature program: initial temperature 90℃, hold for 1 min; increase to 280℃ at 20℃ / min, hold for 1 min; then increase to 300℃ at 40℃ / min, hold for 2 min. Mass spectrometry conditions: Ionization method: electron impact ionization source; ionization energy: 70 eV; measurement mode: selected ion monitoring mode; ion source temperature: 230℃.

[0010] This invention targets phosphogypsum (solid waste) systems; it involves comparative screening of extractants and purification columns; pretreatment minimizes interference and improves the extraction efficiency of target compounds; and the addition of tributyl phosphate-D as an internal standard. 27 Quantification was performed using gas chromatography-mass spectrometry with internal standard method; substitutes with similar physicochemical properties to the target compound were added, and the losses during the treatment process were assessed.

[0011] Comparative experiments demonstrated that the optimal eluent for quantitative extraction of tributyl phosphate in the phosphogypsum leaching system was n-hexane:acetone (volume ratio 1:1), the purification column was an HLB column, and the internal standard was tributyl phosphate-D. 27 The substitute is tripropyl phosphate-D. 21 First, the correlation coefficient R of the calibration curve. 2 >0.999; secondly, the response of the target compound is close to that of the internal standard and the substitute, as seen from the spectrum; and thirdly, the recovery rate of the example is about 80%.

[0012] The advantages and beneficial effects of this invention are: This invention is the first to utilize solid-phase extraction-gas chromatography-mass spectrometry (SPE-GC-MS) to detect the tributyl phosphate content in a phosphogypsum system, improving both the sensitivity and accuracy of the detection. By selecting a suitable SPE column for purification, interference from impurities in the phosphogypsum system is effectively resolved, increasing detection sensitivity and achieving precise quantification of tributyl phosphate, while significantly shortening the analysis and detection time. The detection method exhibits good linearity, stability, and repeatability, making it suitable for the accurate determination of tributyl phosphate in phosphogypsum systems. The correlation coefficient R of the calibration curve in this embodiment is shown in the figure. 2 >0.999, high recovery rate. Attached Figure Description

[0014] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0015] Figure 1 The linear equation and correlation coefficient of tributyl phosphate are shown in the examples. Figure 2 Example: Tripropyl phosphate-D 21 The linear equation and correlation coefficient; Figure 3 For the examples, tributyl phosphate and internal standard (tributyl phosphate-D) 27 ), substitutes (tripropyl phosphate-D) 21 ) Spectrum; Figure 4 Comparative Example 4: Tributyl phosphate, Internal Standard (acenaphthene-D) 10 ), and the spectrum of the substitute (2-fluorobiphenyl); Figure 5 The linear equation and correlation coefficient for comparative example 4, tributyl phosphate. Detailed Implementation

[0016] Example 1: A method for detecting tributyl phosphate in phosphogypsum: The preparation of the working fluid includes: Standard stock solution: Tributyl phosphate (target analyte, 1000 μg / mL), Tributyl phosphate-D 27 (Internal standard, 1000 μg / mL), Tripropyl phosphate-D 21 (Substitute, 1000 μg / mL); Preparation of working solutions: Using n-hexane:acetone (volume ratio 1:1) as solvent, first prepare intermediate solutions of 100 μg / mL for each standard, then add tributyl phosphate and tripropyl phosphate-D... 21 Both working solutions were diluted to two concentrations (10 μg / mL and 1 μg / mL), tributyl phosphate-D 27 Dilute to 5 μg / mL before use.

[0017] The sample pretreatment includes the following steps: Preparation of S1 leachate and determination of soluble non-orthophosphate content: Phosphogypsum raw material was used to obtain phosphogypsum leachate according to the "Solid Waste Leaching Toxicity Leaching Method - Horizontal Oscillation Method" (HJ 557-2010). The content of soluble total phosphate and soluble orthophosphate in the leachate was determined according to the "Water and Wastewater Monitoring and Analysis Methods (Fourth Edition)". The difference between the two is the soluble non-orthophosphate content. Alternatively, phosphogypsum after harmless treatment was used to obtain leachate according to the method of HJ 557-2010. The content of soluble total phosphate and soluble orthophosphate was determined according to the "Water and Wastewater Monitoring and Analysis Methods (Fourth Edition)". The difference between the two is the soluble non-orthophosphate content.

[0018] The method for obtaining phosphogypsum leachate according to HJ 557-2010, "Horizontal Oscillation Method for Leaching Toxicity of Solid Waste," includes the following main steps: Weigh a 100g sample (dry basis) into a 2L extraction bottle. Calculate the required volume of extractant based on the sample's moisture content and a liquid-to-solid ratio of 10:1 (L / kg). Add the extractant, tighten the cap, and vertically fix the bottle on a horizontal oscillation device. Adjust the oscillation frequency to 110 times / min and the amplitude to 40 mm. Shake at room temperature for 8 hours, then remove the extraction bottle and let it stand for 16 hours. Install a filter membrane on a pressure filter, filter, and collect the leachate. The extractant is water.

[0019] S2: Dilution of the leachate: The dilution ratio is selected according to the soluble non-orthophosphate content to obtain a diluted sample solution. Specifically, the dilution ratio is selected according to the soluble non-orthophosphate content as follows: for soluble non-orthophosphate content > 0 and < 1 mg / L, the dilution factor is 1; for soluble non-orthophosphate content ≥ 1 mg / L and ≤ 10 mg / L, the dilution factor is 5~10; for soluble non-orthophosphate content > 10 mg / L, the dilution factor is 50~100. In this embodiment, a final 25 mL diluted sample solution is obtained.

[0020] S3: Sample preparation: Tripropyl phosphate-D is added to the diluted sample solution obtained in S2. 21 The sample was extracted three times with 20 mL of hexane-acetone (1:1 v / v) solvent. The upper organic phase was collected in a distillation flask and concentrated to near dryness by rotary evaporation. It was then redissolved in hexane to approximately 2 mL. The HLB purification column was fixed on a solid-phase extraction apparatus and rinsed with 10 mL of dichloromethane. 5 mL of hexane was added, and the column was allowed to fill completely before the control valve was closed and the column was allowed to incubate for 5 min. The control valve was then slowly opened, and another 5 mL of hexane was added. The control valve was closed again before the liquid level dropped and the column packing was exposed to air. The concentrated and redissolved sample was transferred to the activated column and allowed to incubate for 5 min. The control valve was then slowly opened, and closed again before the solvent flowed out and the column packing was exposed to air. 5 mL of hexane:acetone (1:1 v / v) solvent was added for elution. The eluent was collected in a 10 mL glass colorimetric tube and brought to a final volume of 10 mL to obtain the sample for testing. Before extraction, add 20 μL of 100 μg / mL tributyl phosphate standard to the spiked sample, and keep other operating procedures consistent. For each batch of experiments (5-8 samples), prepare 2 spiked samples, both with a spike concentration of 200 μg / L, and control the concentration of the sample and the corresponding spiked sample on the extract within the mark range.

[0021] The GC / MS method was used to determine: Chromatographic conditions: Column: HP-5ms capillary column, 30 m × 0.25 mm × 0.25 μm; carrier gas: helium, flow rate: 1 mL / min; inlet temperature: 280℃; transfer line temperature: 280℃; splitless injection mode; injection volume: 1.0 μL; temperature program: initial temperature 90℃, hold for 1 min; increase to 280℃ at 20℃ / min, hold for 1 min; then increase to 300℃ at 40℃ / min, hold for 2 min. Mass spectrometry conditions: Ionization method: electron impact ionization source; ionization energy: 70 eV; measurement mode: selected ion monitoring mode; ion source temperature: 230℃; Establishment of calibration curve: A quantitative calibration curve was constructed using the internal standard method, with tributyl phosphate-D as the internal standard. 27 .

[0022] GC / MS determination: Calibration series preparation: using tributyl phosphate and tripropyl phosphate-D 21 Two working solutions at different concentrations (10 μg / mL and 1 μg / mL) and 5 μg / mL tributyl phosphate-D 27 Prepare a standard series of 7 concentration points for tributyl phosphate and tripropyl phosphate-D. 21 The concentrations of the active ingredients were 20 μg / L, 50 μg / L, 100 μg / L, 200 μg / L, 500 μg / L, 800 μg / L, and 1000 μg / L, respectively, and the internal standard concentration was 500 μg / L for all of them.

[0023] Before use: Prepare a 2 mL sample vial containing a glass micro-volume inserter, and take 10 μL of 5 μg / mL tributyl phosphate-D. 27 Add the internal standard and 90 μL of the test sample to the mixture, mix well, and then load the sample onto the instrument; or, without the internal tube, take 900 μL of the test sample and 100 μL of 5 μg / mL tributyl phosphate-D. 27 Add the internal standard to a 2 mL sample vial, mix well, and then load the sample into the instrument.

[0024] In this embodiment, tributyl phosphate and tripropyl phosphate-D 21 The linear equations and correlation coefficients are as follows: Figure 1 , 2 As shown, the spectrum is as follows Figure 3 As shown, the retention time and mass spectrometry parameters are shown in Table 1.

[0025] Table 1 Comparative Example 1 In this comparative example, the hexane-acetone mixed solvent in Example 1 was replaced with dichloromethane, and everything else was the same as in Example 1.

[0026] The results of this comparative example and the embodiment are shown in Table 2. Table 2 In addition, during the research process of this invention, n-hexane (external standard method) was tried, with a blank spike recovery rate of 129.4% and sample spike recoveries of 220.5% and 180.2%, respectively.

[0027] Ethyl acetate was also considered during the research process. However, due to its low boiling point, ethyl acetate can cause a solvent effect during instrumentation and is prone to condensation and column blockage at the injection port, so it cannot be used directly. Samples using ethyl acetate as a solvent generally need to be concentrated and then the solvent replaced before instrumentation. In the steps of this invention, the sample is directly diluted to 10 mL after elution and then used. Therefore, solvents containing ethyl acetate cannot be selected. At the same time, because the sample is directly diluted to volume and used, there is no need to dry and concentrate for solvent replacement, which saves a step.

[0028] Comparative Example 2 Change the type of the purification column to C18. Other procedures are the same as in Example 1.

[0029] Comparative Example 3 Change the type of purification column to a magnesium silicate column. Other procedures are the same as in Example 1.

[0030] The experimental results of Comparative Example 2 and Comparative Example 3 are shown in Table 3.

[0031] Table 3 serial number Purification column type Spiked recovery rate % Substitute recovery rate % Example HLB 83.6 68.2 Comparative Example 2 C18 207.9 9.9 Comparative Example 3 Magnesium silicate 0 55.6 Comparative Example 4 Compared to Example 1, the internal standard and surrogate were replaced. Tributyl phosphate, internal standard (acenaphthene-D) 10 ), the spectrum of the substitute (2-fluorobiphenyl) is as follows Figure 4 As shown, the linear equation and correlation coefficient are as follows: Figure 5 As shown.

[0032] Comparative experiments have shown that the optimal eluent for quantitative extraction of tributyl phosphate in the phosphogypsum leaching system is hexane:acetone (volume ratio 1:1), the purification column is an HLB column, and the internal standard is tributyl phosphate-D. 27 The substitute is tripropyl phosphate-D. 21 First, the correlation coefficient R of the calibration curve. 2 >0.999; secondly, the response of the target compound is close to that of the internal standard and the substitute, as seen from the spectrum; and thirdly, the recovery rate of the example is about 80%.

[0033] This invention is the first to utilize solid-phase extraction-gas chromatography-mass spectrometry (SPE-GC-MS) to detect the tributyl phosphate content in a phosphogypsum system, improving the sensitivity and accuracy of detection. By selecting a suitable SPE column for purification, the interference of impurities in the phosphogypsum system is effectively resolved, increasing detection sensitivity and achieving precise quantification of tributyl phosphate, while significantly shortening the analysis and detection time. The detection method exhibits good linearity, stability, and repeatability, making it suitable for the accurate determination of tributyl phosphate in phosphogypsum systems.

[0034] Finally, it should be noted that the above description is only used to illustrate the technical solutions of the present invention and is not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention.

Claims

1. A method for detecting tributyl phosphate in phosphogypsum, characterized by, The method comprises two parts of sample pretreatment and GC / MS determination. The sample pretreatment comprises the following steps: S1, preparation of leaching solution and determination of soluble non-orthophosphate content: the raw phosphogypsum or the harmless treated phosphogypsum is treated according to HJ 557-2010 'Solid Waste - Toxicity Characteristic Leaching Procedure - Horizontal Oscillation Method' to obtain a phosphogypsum leaching solution; and the soluble non-orthophosphate content in the phosphogypsum leaching solution is determined; S2, dilution of the leaching solution: the dilution ratio is selected according to the soluble non-orthophosphate content to obtain a diluted sample solution; the dilution ratio is selected according to the soluble non-orthophosphate content in the following manner: when the soluble non-orthophosphate content is greater than 0 and less than 1 mg / L, the dilution ratio is 1; when the soluble non-orthophosphate content is greater than or equal to 1 mg / L and less than or equal to 10 mg / L, the dilution ratio is 5-10; and when the soluble non-orthophosphate content is greater than 10 mg / L, the dilution ratio is 50-100. S3 Preparation of the sample to be tested: Add tripropyl phosphate-D as a substitute to the diluted sample solution obtained in S2 21 Subsequently, the upper organic phase was collected, concentrated, and redissolved in n-hexane, and then loaded onto an activated HLB column, eluted with a mixed solvent of n-hexane and acetone (volume ratio 1:1), and the eluate was collected, made constant in volume, and obtained as the sample to be tested. The GC / MS method determines: the internal standard method is used to construct the quantitative calibration curve, and the quantitative internal standard is tributyl phosphate-D 27 .

2. The method for detecting tributyl phosphate in phosphogypsum according to claim 1, characterized by, In S1, the raw phosphogypsum is treated according to HJ 557-2010 'Solid Waste - Toxicity Characteristic Leaching Procedure - Horizontal Oscillation Method' to obtain a phosphogypsum leaching solution, and the soluble total phosphate content and the soluble orthophosphate content in the leaching solution are determined according to 'Water and Wastewater Monitoring and Analysis Methods (Fourth Edition)', and the difference between the two is the soluble non-orthophosphate content; or the harmless treated phosphogypsum is treated according to HJ 557-2010 'Solid Waste - Toxicity Characteristic Leaching Procedure - Horizontal Oscillation Method' to obtain a leaching solution, and the soluble total phosphate content and the soluble orthophosphate content are determined according to 'Water and Wastewater Monitoring and Analysis Methods (Fourth Edition)', and the difference between the two is the soluble non-orthophosphate content.

3. The method for detecting tributyl phosphate in phosphogypsum according to claim 1, characterized by, In S3, the dilute sample solution obtained in S2 is added with a substitute, tripropyl phosphate-D 21 Afterwards, the extractant is extracted with n-hexane-acetone mixed solvent for 3 times.

4. The method for detecting tributyl phosphate in phosphogypsum according to claim 3, characterized by, S3, 20 μL of 100 μg / mL tripropylphosphate-D was added to the diluted sample solution obtained in S2 21 The upper organic phase was collected, concentrated by rotary evaporation, redissolved in 2 mL of n-hexane, and then applied to the activated HLB column. The column was infiltrated for 5 min and eluted with 5 mL of n-hexane-acetone mixed solvent. The eluate was collected, made up to 10 mL, and then used as the sample to be tested.

5. The method for detecting tributyl phosphate in phosphogypsum according to claim 1, characterized by, In S3, the internal standard method was used to construct the quantitative calibration curve, and the concentration of tributyl phosphate and the substitute tributyl phosphate-D 21 was between 0-1000 μg / L, and the concentration of tributyl phosphate and the substitute tributyl phosphate-D 21 The volume ratio of n-hexane-acetone mixed solution was 1:1, which was used as the solvent to prepare the calibration curve solution.

6. The method for detecting tributyl phosphate in phosphogypsum according to claim 5, characterized by, In S3, the internal standard method was used to construct a quantitative calibration curve, controlling the internal standard tributyl phosphate-D. 27 The concentration range is 400~600 μg / L.

7. The method for detecting tributyl phosphate in phosphogypsum according to claim 1, characterized by, In S3, concentration is performed by rotary evaporation or nitrogen blowing.

8. The method for detecting tributyl phosphate in phosphogypsum according to claim 1, characterized by, In the GC / MS determination, The chromatographic conditions are as follows: the chromatographic column is an HP-5ms capillary column with a length of 30 m, an inner diameter of 0.25 mm and a thickness of 0.25 μm, the carrier gas is helium, the flow rate is 1 mL / min, the front sample port temperature is 280℃, the transfer line temperature is 280℃, the sample is injected in a splitless mode, and the injection amount is 1.0 μL; the temperature rising program is as follows: the initial temperature is 90℃, the temperature is kept for 1 min, then the temperature is raised to 280℃ at a rate of 20℃ / min, the temperature is kept for 1 min, then the temperature is raised to 300℃ at a rate of 40℃ / min, and the temperature is kept for 2 min; The mass spectrometric conditions are as follows: the ionization mode is electron impact ionization source, the ionization energy is 70 eV, and the determination mode is selected ion monitoring mode, and the ion source temperature is 230℃.

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