Method for measuring content of hydroxymethyl phosphoric acid by ion chromatography

Abstract

The invention provides a method for determining the content of hydroxymethyl phosphoric acid by ion chromatography, which comprises the following steps: carrying out ion chromatography detection on a hydroxymethyl phosphoric acid standard sample, and fitting a chromatogram curve of the hydroxymethyl phosphoric acid standard sample; adding a hydroxymethyl phosphoric acid standard solution into the synthesized glyphosate sample, fixing the volume with water, carrying out ultrasonic dissolution to obtain a detection solution, carrying out ion chromatography detection, establishing a chromatogram of hydroxymethyl phosphoric acid, and obtaining the chromatographic peak retention time of hydroxymethyl phosphoric acid; and calculating the content of hydroxymethyl phosphoric acid in the sample according to the fitted chromatogram curve of the standard sample. The conditions for carrying out the ion chromatography detection are as follows: the chromatographic column is Metrosep A Supp 5-250 / 0.4; leacheate is a mixed solution of sodium carbonate and sodium hydroxide, and isocratic elution is carried out. The method has the advantages that the separation peak is fast through anion column isocratic elution, the peak pattern is neat, the detection limit is low, and the content of hydroxymethyl phosphoric acid can be fast and accurately measured in a short time.

Description

Technical Field

[0001] The present invention belongs to the field of chemical detection and analysis, and specifically relates to a method for quickly determining the content of hydroxymethyl phosphate in glyphosate by ion chromatography. A glyphosate sample containing hydroxymethyl phosphate is injected into an ion chromatograph, and the content of hydroxymethyl phosphate is measured by ion exchange isocratic elution and separation using an eluent and an anion exchange column. Through the present invention, the content of hydroxymethyl phosphate can be safely, quickly and accurately measured by ion chromatography, providing timely and accurate data guidance for the adjustment of glyphosate production process parameters and product quality control. Background Art

[0002] Hydroxymethyl phosphoric acid is an impurity generated by the reaction of hemiacetal and dimethyl phosphite during the synthesis of glyphosate. Determining the content of hydroxymethyl phosphoric acid in glyphosate is of great significance to the synthesis of glyphosate, and also helps to guide the adjustment of glyphosate production process parameters. Therefore, it is very important to invent a method for efficiently, quickly and accurately determining the content of hydroxymethyl phosphoric acid in glyphosate.

[0003] At present, the determination of glyphosate is carried out by the national standard method of liquid chromatography or ultraviolet spectrophotometry, but the liquid chromatography method can only detect glyphosate after derivatization, while hydroxymethyl phosphoric acid and other impurities fail to peak, and their content cannot be effectively determined. Therefore, providing a method for quickly and accurately determining hydroxymethyl phosphoric acid is beneficial to monitoring the progress of glyphosate synthesis, understanding product quality and improving the economic benefits of glyphosate production. Summary of the invention

[0004] The invention provides a method for detecting hydroxymethyl phosphate in glyphosate by using ion chromatography, which can accurately and quickly detect the content of hydroxymethyl phosphate.

[0005] The technical solution adopted by the present invention is: A method for rapidly detecting hydroxymethyl phosphonic acid in glyphosate using ion chromatography comprises the following steps: (1) Performing ion chromatography on a hydroxymethyl phosphoric acid standard sample and fitting the chromatogram curve of the hydroxymethyl phosphoric acid standard sample; In some embodiments, a hydroxymethyl phosphoric acid standard sample is weighed, dissolved in water to make a stock solution A, and the stock solutions A with gradient concentrations are respectively pipetted, and then respectively made up to volume with water, and then ion chromatography is performed to establish an ion chromatogram of hydroxymethyl phosphoric acid, and the peak area unit (us / cm) min is used to obtain the chromatographic peak retention time range of hydroxymethyl phosphoric acid, and a fitting curve is performed; (2) adding the stock solution to the synthesized glyphosate sample, making up the volume with water, dissolving by ultrasonication to obtain the test solution, performing ion chromatography detection, establishing a chromatogram of hydroxymethyl phosphoric acid, and obtaining the chromatographic peak retention time of hydroxymethyl phosphoric acid; (3) The hydroxymethyl phosphoric acid content in the sample is calculated based on the retention time range of the chromatographic peak of hydroxymethyl phosphoric acid obtained in step (2) and the curve fitted in step (1).

[0006] The gradient concentration in step (1) is achieved within the range of 0.05-0.5 g / L.

[0007] The gradient in step (1) is 0.05, 0.1, 0.2, 0.4, and 0.5 g / L.

[0008] With respect to the technical solution of step (1), in some embodiments, 0.05 g of a hydroxymethyl phosphoric acid standard sample is weighed into a 50 ml volumetric flask, and the volume is adjusted to 50 ml with ultrapure water to prepare a stock solution A, and the parameters of the ion chromatography are adjusted, and 2.5 ml, 5 ml, 10 ml, 12.5 ml, and 25 ml of the stock solution A are respectively transferred to a 50 ml volumetric flask, and then the volume is adjusted to 50 ml with water, and ion chromatography detection is performed by an anion column to establish a chromatogram of hydroxymethyl phosphoric acid, and the peak area unit (us / cm) min is used to obtain the chromatographic peak retention time range of hydroxymethyl phosphoric acid, and a fitting curve is performed; In the step (2), the mass of the glyphosate sample weighed is 0.2 g, the added concentration range of the stock solution (hydroxymethylphosphonic acid standard solution) is 0.1-0.4 g / L, and three different addition amounts are added to obtain three different concentrations of spiked recovery test samples of low, medium and high.

[0009] The ion chromatography detection conditions in step (1) or step (2) are the same, and the ion chromatography conditions are: Chromatographic column: Metrosep A Supp 5-250 / 4.0 Eluent: Sodium carbonate and sodium hydroxide mixed solution, isocratic elution Suppressor regeneration fluid: 0.2-0.5% H 2 SO 4 Aqueous solution; Flow rate: 0.5-1.0ml / min; Detector: conductivity detector; Column temperature: 25-30℃; Injection volume: 10-20µl.

[0010] In some preferred cases, the suppressor regeneration solution: 0.5% H 2 SO 4 Aqueous solution; Flow rate: 0.7ml / min; Detector: conductivity detector; column temperature: 25°C; injection volume: 10µl.

[0011] In the mixed solution of sodium carbonate and sodium hydroxide, the concentration of sodium carbonate is 2.5-4.0 mM, and the concentration of sodium hydroxide is 1-3 mM.

[0012] In some preferred cases, in the mixed solution of sodium carbonate and sodium hydroxide, the concentration of sodium carbonate is 3.2 mM and the concentration of sodium hydroxide is 2 mM.

[0013] Beneficial effects of the present invention: 1. The present invention uses a mixed solution of sodium carbonate and sodium hydroxide, which is simple to operate and easy to prepare, thus saving preparation time for testing.

[0014] 2. This method uses isocratic elution to improve separation, simplify the operation process, reduce equipment costs and avoid baseline drift.

[0015] 3. The present invention selects sodium carbonate with strong elution ability to match sodium hydroxide eluent with slightly weaker elution ability. The use of a sodium carbonate / sodium bicarbonate buffer system can take into account the relationship between strength and weakness. Generally, better elution can be achieved without using a gradient, and the baseline is flat.

[0016] 4. The present invention selects a mixed eluent of sodium carbonate and sodium hydroxide and selects a suitable eluent concentration, which can smoothly separate the impurities in glyphosate and the target peak of hydroxymethyl phosphate, and accurately measure the content of hydroxymethyl phosphate in glyphosate.

[0017] 5. The peak separation is fast through isocratic elution of anion column, and the peak shape is sharp, the detection limit is low, and the content of hydroxymethyl phosphate can be measured quickly and accurately in a short time. This detection method can complete the test within 20 minutes, greatly shortening the detection time and improving work efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 .Ion chromatogram of the mixed solution of sodium carbonate and sodium hydroxide as the eluent.

[0019] Figure 2 .Ion chromatogram of the mixed solution of sodium carbonate and sodium bicarbonate as the eluent.

[0020] Figure 3 .Ion chromatogram when the eluent is sodium borate.

[0021] Figure 4 .Ion chromatogram when the eluent is sodium acetate.

[0022] Figure 5 .Ion chromatogram when the eluent is sodium carbonate solution.

[0023] Figure 6 .Ion chromatogram when the eluent is sodium hydroxide solution. DETAILED DESCRIPTION

[0024] Example 1 Instrument manufacturer: Metrohm, Switzerland A method for detecting ultra-low content hydroxymethylphosphonic acid by ion chromatography, comprising the following steps: (1) Weigh 0.05g of hydroxymethyl phosphoric acid standard sample into a 50mL volumetric flask, dilute to 50ml with water, prepare to a quasi-stock solution of hydroxymethyl phosphoric acid, adjust the parameters of liquid chromatography, and obtain a 1mg / mL stock solution of hydroxymethyl phosphoric acid. Transfer 2.5ml, 5ml, 10ml, 12.5ml, and 25ml of the stock solution to a 50ml volumetric flask, and then dilute to 50ml with water. Perform ion chromatography detection, establish the chromatogram of hydroxymethyl phosphoric acid, and obtain the peak area unit (us / cm)min. The retention time range of the chromatographic peak of hydroxymethyl phosphoric acid is obtained, and the curve is fitted; (2) Add 5 ml of the stock solution to the synthesized 0.2 g glyphosate sample, dilute to 50 ml with water, and dissolve the glyphosate sample by ultrasonication to obtain three different concentrations of spiked recovery test samples: low, medium, and high. Use the liquid chromatography parameters of step (1) to perform liquid phase analysis and detection, establish a chromatogram of hydroxymethyl phosphoric acid, and obtain the chromatographic peak retention time range of hydroxymethyl phosphoric acid; (3) The content of hydroxymethyl phosphoric acid in the sample is calculated based on the retention time range of the chromatographic peak of hydroxymethyl phosphoric acid obtained in step (2) and the curve fitted in step (1).

[0025] The parameters of liquid chromatography in the step are: Eluent: Sodium carbonate and sodium hydroxide mixed solution, isocratic elution Suppressor regeneration fluid: 0.5% H 2 SO 4 Aqueous solution Flow rate: 0.7ml / min Detector: Conductivity detector Column temperature: 25°C Injection volume: 10µl The analysis results of hydroxymethyl phosphate content in glyphosate are shown in the chromatogram of hydroxymethyl phosphate. Figure 1 , the peak can be achieved in 16 minutes, and the detection result of the hydroxymethyl phosphate standard sample is fast and accurate, and the peak shape is neat, time-saving and efficient, and the ion chromatography can quickly and accurately detect the hydroxymethyl phosphate content in glyphosate, and the detection result is accurate. The method of the present invention can provide timely and accurate guidance for the workshop production process.

[0026] Example 2 Instrument manufacturer: Metrohm, Switzerland A method for detecting ultra-low content hydroxymethylphosphonic acid by ion chromatography, comprising the following steps: (1) Weigh 0.05g of hydroxymethyl phosphoric acid standard sample into a 50mL volumetric flask, dilute to 50ml with water, prepare to a quasi-stock solution of hydroxymethyl phosphoric acid, adjust the parameters of liquid chromatography, and obtain a 1mg / mL stock solution of hydroxymethyl phosphoric acid. Transfer 2.5ml, 5ml, 10ml, 12.5ml, and 25ml of the stock solution to a 50ml volumetric flask, and then dilute to 50ml with water. Perform ion chromatography detection, establish the chromatogram of hydroxymethyl phosphoric acid, and obtain the peak area unit (us / cm)min. The retention time range of the chromatographic peak of hydroxymethyl phosphoric acid is obtained, and the curve is fitted; (2) Add 5 ml of the stock solution to the synthesized 0.2 g glyphosate sample, dilute to 50 ml with water, and dissolve the glyphosate sample by ultrasonication to obtain three different concentrations of spiked recovery test samples: low, medium, and high. Use the liquid chromatography parameters of step (1) to perform liquid phase analysis and detection, establish a chromatogram of hydroxymethyl phosphoric acid, and obtain the chromatographic peak retention time range of hydroxymethyl phosphoric acid; (3) The content of hydroxymethyl phosphoric acid in the sample is calculated based on the retention time range of the chromatographic peak of hydroxymethyl phosphoric acid obtained in step (2) and the curve fitted in step (1).

[0027] The parameters of liquid chromatography in the step are: Eluent: Sodium carbonate and sodium bicarbonate mixed solution, isocratic elution Suppressor regeneration fluid: 0.5% H 2 SO 4 Aqueous solution Flow rate: 0.7ml / min Detector: Conductivity detector Column temperature: 25°C Injection volume: 10µl The analysis results of hydroxymethyl phosphate content in glyphosate are shown in the chromatogram of hydroxymethyl phosphate. Figure 2 The peak of hydroxymethylphosphonic acid appearing at 15.66min and the impurity peak appearing at 17.80min cannot be well separated, the measured results are inaccurate, and the eluent is not suitable and needs to be replaced.

[0028] Example 3 Instrument manufacturer: Metrohm, Switzerland A method for detecting ultra-low content hydroxymethylphosphonic acid by ion chromatography, comprising the following steps: (1) Weigh 0.05g of hydroxymethyl phosphoric acid standard sample into a 50mL volumetric flask, dilute to 50ml with water, prepare to a quasi-stock solution of hydroxymethyl phosphoric acid, adjust the parameters of liquid chromatography, and obtain a 1mg / mL stock solution of hydroxymethyl phosphoric acid. Transfer 2.5ml, 5ml, 10ml, 12.5ml, and 25ml of the stock solution to a 50ml volumetric flask, and then dilute to 50ml with water. Perform ion chromatography detection, establish the chromatogram of hydroxymethyl phosphoric acid, and obtain the peak area unit (us / cm)min. The retention time range of the chromatographic peak of hydroxymethyl phosphoric acid is obtained, and the curve is fitted; (2) Add 5 ml of the stock solution to the synthesized 0.2 g glyphosate sample, dilute to 50 ml with water, and dissolve the glyphosate sample by ultrasonication to obtain three different concentrations of spiked recovery test samples: low, medium, and high. Use the liquid chromatography parameters of step (1) to perform liquid phase analysis and detection, establish a chromatogram of hydroxymethyl phosphoric acid, and obtain the chromatographic peak retention time range of hydroxymethyl phosphoric acid; (3) The content of hydroxymethyl phosphoric acid in the sample is calculated based on the retention time range of the chromatographic peak of hydroxymethyl phosphoric acid obtained in step (2) and the curve fitted in step (1).

[0029] The parameters of liquid chromatography in the step are: Eluent: sodium borate, isocratic elution Suppressor regeneration fluid: 0.5% H 2 SO 4 Aqueous solution Flow rate: 0.7ml / min Detector: Conductivity detector Column temperature: 25°C Injection volume: 10µl The analysis results of hydroxymethyl phosphate content in glyphosate are shown in the chromatogram of hydroxymethyl phosphate. Figure 3 As shown in the figure, no target peak appeared within 40 minutes, indicating that the eluent did not match and needed to be replaced.

[0030] Example 4 Instrument manufacturer: Metrohm, Switzerland A method for detecting ultra-low content hydroxymethylphosphonic acid by ion chromatography, comprising the following steps: (1) Weigh 0.05g of hydroxymethyl phosphoric acid standard sample into a 50mL volumetric flask, dilute to 50ml with water, prepare to a quasi-stock solution of hydroxymethyl phosphoric acid, adjust the parameters of liquid chromatography, and obtain a 1mg / mL stock solution of hydroxymethyl phosphoric acid. Transfer 2.5ml, 5ml, 10ml, 12.5ml, and 25ml of the stock solution to a 50ml volumetric flask, and then dilute to 50ml with water. Perform ion chromatography detection, establish the chromatogram of hydroxymethyl phosphoric acid, and obtain the peak area unit (us / cm)min. The retention time range of the chromatographic peak of hydroxymethyl phosphoric acid is obtained, and the curve is fitted; (2) Add 5 ml of the stock solution to the synthesized 0.2 g glyphosate sample, dilute to 50 ml with water, and dissolve the glyphosate sample by ultrasonication to obtain three different concentrations of spiked recovery test samples: low, medium, and high. Use the liquid chromatography parameters of step (1) to perform liquid phase analysis and detection, establish a chromatogram of hydroxymethyl phosphoric acid, and obtain the chromatographic peak retention time range of hydroxymethyl phosphoric acid; (3) The content of hydroxymethyl phosphoric acid in the sample is calculated based on the retention time range of the chromatographic peak of hydroxymethyl phosphoric acid obtained in step (2) and the curve fitted in step (1).

[0031] The parameters of liquid chromatography in the step are: Eluent: Sodium acetate, isocratic elution Suppressor regeneration fluid: 0.5% H 2 SO 4 Aqueous solution Flow rate: 0.7ml / min Detector: Conductivity detector Column temperature: 25°C Injection volume: 10µl The analysis results of hydroxymethyl phosphate content in glyphosate are shown in the chromatogram of hydroxymethyl phosphate. Figure 4 As shown in the figure, no target peak appeared within 28 minutes, indicating that the eluent did not match and needed to be replaced.

[0032] Example 5 Instrument manufacturer: Metrohm, Switzerland A method for detecting ultra-low content hydroxymethylphosphonic acid by ion chromatography, comprising the following steps: (1) Weigh 0.05g of hydroxymethyl phosphoric acid standard sample into a 50mL volumetric flask, dilute to 50ml with water, prepare to a quasi-stock solution of hydroxymethyl phosphoric acid, adjust the parameters of liquid chromatography, and obtain a 1mg / mL stock solution of hydroxymethyl phosphoric acid. Transfer 2.5ml, 5ml, 10ml, 12.5ml, and 25ml of the stock solution to a 50ml volumetric flask, and then dilute to 50ml with water. Perform ion chromatography detection, establish the chromatogram of hydroxymethyl phosphoric acid, and obtain the peak area unit (us / cm)min. The retention time range of the chromatographic peak of hydroxymethyl phosphoric acid is obtained, and the curve is fitted; (2) Add 10 ml of the stock solution to the synthesized 0.2 g glyphosate sample, dilute to 50 ml with water, and dissolve the glyphosate sample by ultrasonication to obtain three different concentrations of spiked recovery test samples: low, medium, and high. Use the liquid chromatography parameters of step (1) to perform liquid phase analysis and detection, establish a chromatogram of hydroxymethyl phosphoric acid, and obtain the chromatographic peak retention time range of hydroxymethyl phosphoric acid; (3) The content of hydroxymethyl phosphoric acid in the sample is calculated based on the retention time range of the chromatographic peak of hydroxymethyl phosphoric acid obtained in step (2) and the curve fitted in step (1).

[0033] The parameters of liquid chromatography in the step are: Eluent: Sodium carbonate and sodium hydroxide mixed solution, isocratic elution Suppressor regeneration fluid: 0.5% H 2 SO 4 Aqueous solution Flow rate: 0.7ml / min Detector: Conductivity detector Column temperature: 25°C Injection volume: 10µl Analysis results of hydroxymethyl phosphate content in glyphosate Chromatogram of hydroxymethyl phosphate and Figure 1 Similar, the peak time is 14min, and the ion chromatography can quickly and accurately determine the hydroxymethyl phosphate content in glyphosate, and the detection result is accurate, time-saving and efficient. The method of the present invention can provide timely and accurate guidance for the workshop production process.

[0034] Example 6 Instrument manufacturer: Metrohm, Switzerland A method for detecting ultra-low content hydroxymethylphosphonic acid by ion chromatography, comprising the following steps: (1) Weigh 0.05g of hydroxymethyl phosphoric acid standard sample into a 50mL volumetric flask, dilute to 50ml with water, prepare to a quasi-stock solution of hydroxymethyl phosphoric acid, adjust the parameters of liquid chromatography, and obtain a 1mg / mL stock solution of hydroxymethyl phosphoric acid. Transfer 2.5ml, 5ml, 10ml, 12.5ml, and 25ml of the stock solution to a 50ml volumetric flask, and then dilute to 50ml with water. Perform ion chromatography detection, establish the chromatogram of hydroxymethyl phosphoric acid, and obtain the peak area unit (us / cm)min. The retention time range of the chromatographic peak of hydroxymethyl phosphoric acid is obtained, and the curve is fitted; (2) Add 12.5 ml of the stock solution to the synthesized 0.2 g glyphosate sample, dilute to 50 ml with water, and dissolve the glyphosate sample by ultrasonication to obtain three different concentrations of spiked recovery test samples: low, medium, and high. Use the liquid chromatography parameters of step (1) to perform liquid phase analysis and detection, establish a chromatogram of hydroxymethyl phosphoric acid, and obtain the chromatographic peak retention time range of hydroxymethyl phosphoric acid; (3) The content of hydroxymethyl phosphoric acid in the sample is calculated based on the retention time range of the chromatographic peak of hydroxymethyl phosphoric acid obtained in step (2) and the curve fitted in step (1).

[0035] The parameters of liquid chromatography in the step are: Eluent: Sodium carbonate and sodium hydroxide mixed solution, isocratic elution Suppressor regeneration fluid: 0.5% H 2 SO 4 Aqueous solution Flow rate: 0.7ml / min Detector: Conductivity detector Column temperature: 25°C Injection volume: 10µl Analysis results of hydroxymethyl phosphate content in glyphosate Chromatogram of hydroxymethyl phosphate and Figure 1 The peak time is 14.5min, and the ion chromatography can quickly and accurately determine the content of hydroxymethyl phosphate in glyphosate, and the detection result is accurate, time-saving and efficient. The method of the present invention can provide timely and accurate guidance for workshop production processes.

[0036] Comparative Example 1 The method and conditions were the same as those in Example 1, except that the eluent was replaced with a single sodium carbonate solution. Even when the running time was extended to 40 min, the hydroxymethyl phosphate standard sample did not produce any peaks. This indicates that the single mobile phase is not suitable for detecting the hydroxymethyl phosphate content in glyphosate (e.g. Figure 5 as shown).

[0037] Comparative Example 2 The method and conditions were the same as those in Example 1, except that the eluent was replaced with sodium hydroxide solution. Even if the running time was extended to 40 min, the hydroxymethyl phosphoric acid standard sample did not produce any peaks. This indicates that the single mobile phase is not suitable for detecting the hydroxymethyl phosphoric acid content in glyphosate. Only by using a mixed mobile phase can the hydroxymethyl phosphoric acid content in glyphosate be detected quickly and accurately (e.g. Figure 6 as shown).

Claims

1. A method for determining the content of hydroxymethylphosphoric acid by ion chromatography, It is characterized in that The following steps are involved: (1) Performing ion chromatography on a hydroxymethyl phosphoric acid standard sample and fitting the chromatogram curve of the hydroxymethyl phosphoric acid standard sample; (2) adding a hydroxymethyl phosphoric acid standard solution to the synthesized glyphosate sample, making up the volume with water, dissolving by ultrasonication to obtain a test solution, performing ion chromatography detection, establishing a chromatogram of hydroxymethyl phosphoric acid, and obtaining the chromatographic peak retention time of hydroxymethyl phosphoric acid; (3) calculating the hydroxymethyl phosphoric acid content in the sample according to the retention time range of the chromatographic peak of hydroxymethyl phosphoric acid obtained in step (2) and comparing it with the chromatogram curve of the standard sample fitted in step (1); The conditions for ion chromatography detection in steps (1) and (2) are: Chromatographic column: Metrosep A Supp 5-250 / 4.0; Eluent: a mixed solution of sodium carbonate and sodium hydroxide for isocratic elution.

2. The method for measuring the content of hydroxymethylphosphoric acid by ion chromatography according to claim 1, It is characterized in that Suppressor regeneration fluid: 0.2-0.5% H 2 SO 4 Aqueous solution; Flow rate: 0.5-1.0ml / min; Detector: conductivity detector; Column temperature: 25-30℃; Injection volume: 10-20µl.

3. The method for measuring the content of hydroxymethylphosphoric acid by ion chromatography according to claim 1, It is characterized in that In the mixed solution of sodium carbonate and sodium hydroxide, the concentration of sodium carbonate is 2.5-4.0 mM, and the concentration of sodium hydroxide is 1-3 mM.

4. The method for measuring the content of hydroxymethylphosphoric acid by ion chromatography according to claim 3, It is characterized in that The sodium carbonate and sodium hydroxide mixed solution has a sodium carbonate concentration of 3.2 mM and a sodium hydroxide concentration of 2 mM.

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