A method for quantitatively determining triphenylphosphonium compounds and their derived phosphine oxides in water

Abstract

The present invention discloses a method for quantitatively determining triphenylphosphonium compounds and their derived phosphine oxides in water, belonging to the technical field of analytical chemistry. The liquid chromatography-tandem triple quadrupole mass spectrometry technology is adopted, and its single standard is used as the qualitative substance, and methyltriphenylphosphonium iodide labeled with D3 is used as the recovery indicator. Using 13 ethyl p-hydroxybenzoate labeled with 13 C ( C-EtP) as the internal standard substance, the whole step of the quantitative method of the present invention is relatively simple, with high measurement sensitivity and accuracy. The content determination of 9 triphenylphosphonium compounds and their derived phosphine oxides can be completed within 8 minutes, providing reference data for accurately determining the content of triphenylphosphonium compounds and their derived phosphine oxides in water.

Description

Technical Field

[0001] The present invention relates to the technical field of analytical chemistry, and particularly to a method for quantitatively determining quaternary triphenylphosphonium compounds and their derived phosphine oxides in water bodies. Background Art

[0002] Quaternary triphenylphosphonium compounds (R-Ph3P + ) are a type of new pollutant, and their structural general formula is

[0003]

[0004] In the formula, R is an organic group such as Me, Et, Bu, etc., and X - is a halogen, usually chlorine, bromine, etc.

[0005] Quaternary triphenylphosphonium compounds are well-known for being used as intermediates in the Wittig reaction in the chemical industry. This reaction is one of the important reactions for synthesizing olefins and can be used to synthesize drugs such as vitamin A, β-carotene, and prostaglandins through the Wittig reaction. In addition, quaternary triphenylphosphonium compounds have some other special applications, such as: they can be used as phase transfer catalysts and can also be used to recover technetium from radioactive waste streams. With their use in the chemical industry and medicine, quaternary triphenylphosphonium compounds as intermediates have been discovered after entering the environment and have been designated as new pollutants. Research shows that quaternary triphenylphosphonium compounds and their derived phosphine oxides all have cytotoxicity, and some even have genotoxicity. As new pollutants, due to their large consumption as chemical intermediates, it can be expected that they are widely present in industrial wastewater treatment plants or in rivers receiving industrial wastewater, and there have been studies detecting the presence of quaternary triphenylphosphonium compounds and their derived phosphine oxides in rivers.

[0006] The existing analytical methods for qualitatively and quantitatively analyzing quaternary triphenylphosphonium compounds and their derived phosphine oxides in water bodies are to use liquid chromatography tandem quadrupole time-of-flight mass spectrometry (LC-QToF-MS) for determination. This method has high requirements for laboratory instruments and equipment, takes a long time to measure a sample, and has a large sample injection volume. Therefore, it is very necessary to provide a simple, effective, and rapid qualitative and quantitative method for studying this substance, so as to facilitate the accurate and rapid analysis of quaternary triphenylphosphonium compounds and their derived phosphine oxides in water bodies, and further achieve the purpose of analyzing their presence and distribution characteristics in various media. Summary of the Invention

[0007] In order to minimize the measurement errors caused by changes in operating conditions and sample injection volume, the present invention selects the internal standard method with high precision to establish a method for quantitatively determining triphenylphosphonium compounds and their derived phosphine oxides in water. The present invention provides for the first time a method for quantitatively determining triphenylphosphonium compounds and their derived phosphine oxides in water based on liquid chromatography-tandem triple quadrupole mass spectrometry (LC-MS / MS). This method is simple to operate, has a short detection time, requires a small sample injection volume, and has higher measurement sensitivity and precision, effectively solving the deficiencies existing in the prior art.

[0008] To achieve the above object, the present invention provides the following solutions:

[0009] The present invention provides a method for quantitatively determining triphenylphosphonium compounds and their derived phosphine oxides in water. Using liquid chromatography-tandem triple quadrupole mass spectrometry, with the respective standard products of 9 triphenylphosphonium compounds and their derived phosphine oxides as qualitative substances, + using methyltriphenylphosphonium iodide labeled with D3 (CD3-Ph3P 13 ) as the recovery indicator, and 13 ethyl p-hydroxybenzoate labeled with

[0010] C ([[]] 13 [[]]C-EtP) as the internal standard substance, the internal standard method is used to quantitatively determine triphenylphosphonium compounds and their derived phosphine oxides in water. The liquid chromatography-tandem triple quadrupole mass spectrometry is a method for realizing quantitative detection by using a liquid chromatography-tandem triple quadrupole mass spectrometry system. + )、methyltrimethoxyphenylphosphonium chloride (MeOMe-Ph3P + )、benzyltriphenylphosphonium chloride (Ph-CH2-Ph3P + )、methyltriphenylphosphonium bromide (Me-Ph3P + )、ethyltriphenylphosphonium bromide (Et-Ph3P + )、propyltriphenylphosphonium bromide (Propyl-Ph3P + ) or tetraphenylphosphonium chloride (Ph4P + ).

[0011] Further, the derived phosphine oxides include triphenylphosphine oxide (TPPO) or diphenylphosphine oxide (DPPO).

[0012] When the method of the present invention is used for pretreatment of water samples, a recovery indicator is first added to the water sample to be measured. After mixing, it undergoes a solid-phase extraction process to achieve the purpose of purification and concentration. The recovery indicator is generally added before pretreatment and goes through the entire processes of pretreatment and instrumental analysis along with the sample. It is measured in the same way as other components in the sample and is used to characterize the loss or recovery rate of the entire pretreatment process. Generally, if its recovery rate is within a certain range, it is considered that the extraction result can be quantified as the inspection result.

[0013] Further, the mass spectrometry conditions include: selecting the electrospray ionization source mode as the positive ion mode, with a capillary voltage of 1 kV, a cone gas flow rate of 100 L / hr, an ion source temperature of 150 °C, a desolvation gas temperature of 500 °C, a flow rate of 1000 L / hr, and the scan mode using the multiple reaction monitoring (MRM) mode.

[0014] Further, the liquid chromatography conditions: the chromatographic column is BHE Phenyl (2.1×100 mm, 1.7 μm), the injection volume is 1 μL, the mobile phase A is acetonitrile, the mobile phase B is an aqueous solution of 5 mM ammonium formate, and gradient elution is adopted.

[0015] Further, the gradient elution conditions are as follows:

[0016]

[0017] Further, the liquid chromatography - mass spectrometry instrument is an ultra-high performance liquid chromatography - triple quadrupole mass spectrometry instrument (Waters, USA).

[0018] Further, before injection, the extraction column is activated.

[0019] Further, the activation process includes: before use, the extraction column is activated successively with dichloromethane, acetonitrile, and water.

[0020] Further, the extraction column is an HLB solid-phase extraction column.

[0021] The present invention discloses the following technical effects:

[0022] The quantitative method of the present invention is relatively simple in the whole process and shortens the measurement time of the sample to be measured to 8 min, with higher sensitivity, providing a reference basis for the determination of the content of triphenylphosphonium compounds and their derivative phosphine oxides in water bodies.

[0023] The detection limit range of the quantitative method of the present invention is 20 - 200 ng / L, the quantitative limit range is 50 - 500 ng / L, the recovery rate range is 70.57% - 113.67%, and the RSD of the recovery rate < 15%. Description of the Drawings

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0025] Figure 1 It is the standard chromatogram of triphenylphosphonium compounds and their derivative phosphine oxides;

[0026] Figure 2 It is a comparison diagram under the phenyl column conditions of triphenylphosphonium compounds and their derivative phosphine oxides (taking the C18 column as the reference); Detailed Embodiments

[0027] Now, various exemplary embodiments of the present invention will be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, characteristics, and implementation schemes of the present invention.

[0028] It should be understood that the terms described in the present invention are only for describing specific embodiments and are not used to limit the present invention. Additionally, for the numerical ranges in the present invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any intermediate value within any stated value or stated range, as well as each smaller range between any other stated value or intermediate value within the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded from the range.

[0029] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention pertains. Although the present invention only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein can also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the documents. In case of conflict with any incorporated document, the content of this specification shall prevail.

[0030] Without departing from the scope or spirit of the present invention, various improvements and changes can be made to the specific embodiments of the present invention specification, which are obvious to those skilled in the art. Other embodiments obtained from the specification of the present invention are obvious to those skilled in the art. The specification and embodiments of the present invention are only exemplary.

[0031] Regarding the terms "comprising", "including", "having", "containing", etc. used herein, they are all open-ended terms, meaning including but not limited to.

[0032] In the present invention, the mixed standard stock solution refers to a high-concentration mixed standard solution of 1 g / L (which can be used for a long time); the mixed standard solution refers to a mixed standard solution with a lower concentration obtained by diluting the mixed standard stock solution (prepared as needed).

[0033] The method for quantitatively determining triphenylphosphonium compounds and their derived phosphine oxides in water bodies of the present invention uses liquid chromatography-tandem triple quadrupole mass spectrometry. Nine respective standard substances of triphenylphosphonium compounds and their derived phosphine oxides are used as qualitative substances, and methyltriphenylphosphonium iodide labeled with D3 (CD3-Ph3P + ) is used as a recovery indicator, and 13 ethyl p-hydroxybenzoate labeled with 13

[0034] The triphenylphosphonium compounds of the present invention include n-butyltriphenylphosphonium bromide (Bu-Ph3P + ), methoxymethyltriphenylphosphonium chloride (MeOMe-Ph3P + ), benzyltriphenylphosphonium chloride (Ph-CH2-Ph3P + ), methyltriphenylphosphonium bromide (Me-Ph3P + ), ethyltriphenylphosphonium bromide (Et-Ph3P + ), propyltriphenylphosphonium bromide (Propyl-Ph3P + ) or tetraphenylphosphonium chloride (Ph4P + ).

[0035] The derived phosphine oxides of the present invention include triphenylphosphine oxide (TPPO) or diphenylphosphine oxide (DPPO).

[0036] Before the pretreatment, a recovery indicator is added to the water sample to be tested. After mixing, it undergoes solid-phase extraction treatment to achieve the purpose of purification and concentration.

[0037] The mass spectrometry conditions for the method for quantitatively determining triphenylphosphonium compounds and their derived phosphine oxides in water bodies of the present invention include: selecting the electrospray ionization source mode as the positive ion mode, the capillary voltage as 1 kV, the cone gas flow rate as 100 L / hr, the ion source temperature as 150 °C, the desolvent gas temperature as 500 °C, the flow rate as 1000 L / hr, and the scanning mode using the multiple reaction monitoring (MRM) mode.

[0038] The liquid chromatography conditions for the method for quantitatively determining triphenylphosphonium compounds and their derived phosphine oxides in water bodies of the present invention: the chromatographic column is ​BHE Phenyl (2.1×100 mm, 1.7 μm), injection volume is 1 μL, mobile phase A is acetonitrile, mobile phase B is 5 mM ammonium formate aqueous solution, and gradient elution is adopted.

[0039] The gradient elution conditions of the present invention are as follows:

[0040]

[0041] For the method of quantitatively determining triphenylphosphonium compounds and their derived phosphine oxides in water of the present invention, the process of drawing the standard curve is as follows: The prepared mixed standard solution with known concentration is sequentially injected into the liquid chromatography-mass spectrometry for determination from low to high concentration gradient. The standard curve is drawn with the relative response peak area of the target component and the corresponding relative mass concentration. Under this condition, the linear correlation coefficient reaches above 0.99.

[0042] The liquid chromatography-mass spectrometry in the present invention is an ultra-high performance liquid chromatography-triple quadrupole mass spectrometry (Waters, USA).

[0043] For the method of quantitatively determining triphenylphosphonium compounds and their derived phosphine oxides in water of the present invention, before loading the sample, the extraction column is activated.

[0044] For the method of quantitatively determining triphenylphosphonium compounds and their derived phosphine oxides in water of the present invention, the activation process includes: Before use, the extraction column is sequentially activated with dichloromethane, acetonitrile and water.

[0045] For the method of quantitatively determining triphenylphosphonium compounds and their derived phosphine oxides in water of the present invention, the extraction column is an HLB solid phase extraction column.

[0046] For the method of quantitatively determining triphenylphosphonium compounds and their derived phosphine oxides in water of the present invention, the specific process of pretreatment and content determination of the sample to be tested can be: Add a recovery indicator to 100 mL of the water sample to be tested and mix well. Before use, the HLB solid phase extraction column (6 mL, 500 mg) is sequentially activated with 5 mL of dichloromethane, 5 mL of acetonitrile and 5 mL of water. Transfer the water sample to the activated HLB solid phase extraction column. After the sample loading is completed, wash with 5 mL of washing solution (acetonitrile: water = 2:8 (v / v)), and elute with 6 mL of elution solution (acetonitrile: water = 9:1 (v / v)). The eluate is collected in a centrifuge tube, add internal standard 13 C-EtP is fixed to 6 mL. Take 1 mL of the test solution, filter it through a 0.2 μm polytetrafluoroethylene filter membrane, and then load it into a chromatographic vial and inject it into the liquid chromatography-mass spectrometry for determination. Substitute the relative response peak area of the measured target component into the standard curve to calculate the content of the target component in the sample to be tested.

[0047] Example 1

[0048] The instrument used in the experiment of this example is an ultra-high performance liquid chromatography-triple quadrupole mass spectrometry (Waters, USA).

[0049] 1. Establish and optimize the mass spectrometry conditions

[0050] Preparation of single-standard stock solutions of target components: The nine triphenylphosphonium compounds and their derived phosphine oxides include Bu-Ph3P + , MeOMe-Ph3P + , Ph-CH2-Ph3P + , Me-Ph3P + , Et-Ph3P + , Propyl-Ph3P + , Ph4P + , DPPO, and TPPO. Weigh accurately the solid standard substances of the nine target substances respectively, use acetonitrile as the solvent, and prepare single-standard stock solutions with a concentration of 1 g / L for the nine target substances respectively.

[0051] Dilute the single-standard stock solution of the target component to 10 μg / L and inject it into the machine. The selected electrospray ionization source mode is the positive ion mode, the capillary voltage is 1 KV, the cone gas flow rate is 100 L / hr, the ion source temperature is 150 °C, the desolvent gas temperature is 500 °C, the flow rate is 1000 L / hr, and the scanning mode adopts the multiple reaction monitoring MRM mode.

[0052] 2. Determine the chromatographic conditions

[0053] The chromatographic column is BHE Phenyl (2.1×100 mm, 1.7 μm), the injection volume is 1 μL, the mobile phase A is acetonitrile, the mobile phase B is an aqueous solution of 5 mM ammonium formate, and gradient elution is used. Ammonium formate is added to the mobile phase B for better ionization to facilitate the formation of the ions required for determination.

[0054] After determining the mass spectrometry conditions for a single substance, select to inject a 10 μg / L mixed standard solution, and optimize the resolution of the sample by adjusting the initial proportion of the mobile phase and the gradient slope to achieve the best separation effect of the mixture. The elution conditions are shown in Table 1.

[0055] The preparation process of the mixed standard stock solution is as follows: Pipette a certain amount of the 1 g / L single-standard stock solutions of the nine triphenylphosphonium compounds and their derived phosphine oxides respectively, and make up the volume to 2 mL in a brown chromatographic vial with acetonitrile to prepare a 100 mg / L mixed standard solution. The low-concentration mixed standard solution is obtained by diluting downward from the mixed standard stock solution.

[0056] Table 1 Elution conditions of liquid chromatography

[0057]

[0058] 3. Recovery rate of the method

[0059] The concentration gradients of the prepared mixed standard solution are 0.05 μg / L, 0.1 μg / L, 0.5 μg / L, 1 μg / L, 5 μg / L, 10 μg / L, and 50 μg / L. The prepared mixed standard samples are sequentially injected into the liquid chromatography - mass spectrometry (LC - MS) instrument for determination according to the increasing concentration. The standard curve is plotted with the relative response peak area Y of the target component and the corresponding relative mass concentration X (μg / L). The linear correlation coefficients all reach above 0.99. The results are shown in Table 2, meeting the analysis requirements of the laboratory. As can be seen from Table 2, the linear correlation coefficients of the method of the present invention all reach above 0.99, and the response values and concentrations of each target compound show good linear relationships.

[0060] Table 2 Linear experiment results of the method

[0061]

[0062]

[0063] Add the mixed standard sample and the recovery rate indicator to 100 mL of blank water sample and mix well. The HLB solid - phase extraction column (6 mL, 500 mg) is activated successively with 5 mL of dichloromethane, 5 mL of acetonitrile, and 5 mL of water before use. Transfer the water sample to the activated HLB solid - phase extraction column. After the sample loading is completed, wash it with 5 mL of eluent (acetonitrile: water = 2:8 (v / v)), and elute with 6 mL of elution solution (acetonitrile: water = 9:1 (v / v)). The eluate is collected in a centrifuge tube, and the internal standard 13 C - EtP is made up to 6 mL. Take 1 mL of the test solution, filter it through a 0.2 - μm polytetrafluoroethylene filter membrane, and then load it into a chromatographic vial and inject it into the liquid chromatography - mass spectrometry instrument for determination. The recovery rate and its relative standard deviation results are shown in Table 3, ensuring the accuracy of the method. As can be seen from Table 3, the recovery rate range of the method of the present invention is between 70.57% - 113.67%, and the relative standard deviation of the recovery rate is less than 15%, indicating that the recovery rate of this pretreatment method is good and within an acceptable range.

[0064] Table 3 Recovery rate results at three concentration levels

[0065]

[0066]

[0067] 4. Pretreatment and determination of the sample to be tested

[0068] Take 100 mL of the water sample to be tested and add 100 μL of 60 μg / L recovery indicator (CD3-Ph3P + ), and mix well. The HLB solid-phase extraction column (6 mL, 500 mg) is activated successively with 5 mL of dichloromethane, 5 mL of acetonitrile, and 5 mL of water before use. Transfer the water sample to the activated HLB solid-phase extraction column. After the loading is completed, wash it with 5 mL of eluent (acetonitrile: water = 2:8 (v / v)), and elute with 6 mL of eluent (acetonitrile: water = 9:1 (v / v)). Collect the eluate in a centrifuge tube, add the internal standard 13 C-EtP and make up the volume to 6 mL. Take 1 mL of the test solution, filter it through a 0.2 μm polytetrafluoroethylene filter membrane, and then load it into a chromatographic vial for determination by liquid chromatography-mass spectrometry. Substitute the relative response peak area of the target component measured into the standard curve to calculate the corresponding concentration of the target component in the test sample.

[0069] Comparative Example 1

[0070] In this comparative example, a liquid chromatography-mass spectrometry system was used, and the same parameter conditions as in Example 1 were adopted. The C18 column was used to analyze triphenylphosphonium compounds and their derived phosphine oxides in the same way. Figure 2 It shows the percentage increase or decrease in the peak area, signal-to-noise ratio, and standard curve slope of each substance under the phenyl column condition based on the C18 column in a 10 μg / L mixed standard solution. It can be clearly seen that compared with the C18 column, for most triphenylphosphonium compounds and their derived phosphine oxides, the peak area, signal-to-noise ratio, and the slope of the standard curve of the phenyl column have increased significantly to varying degrees.

[0071] Comparative Example 2

[0072] Under the optimal conditions of Example 1, the detection method significantly shortens the instrument detection time compared with the existing analytical detection methods for quaternary triphenylphosphonium compounds and their derived phosphine oxides (Simon B., Michael P.S., Ternes, T.A., 2018. Quaternary (triphenyl-)phosphonium compounds: Environmental behavior and toxicity. Water Research. 136, 207-219.; Schlüsener, M.P., Kunkel, U., Ternes, T.A., 2015. Quaternary triphenylphosphonium compounds: a new class of environmental pollutants. Environ. Sci. Technol. 49(24), 14282-14291.), from 27 minutes to 8 minutes, improving the sample detection efficiency. As Figure 1 shown, the method of the present invention can complete the determination of the contents of 9 quaternary triphenylphosphonium compounds and their derived phosphine oxides within 8 minutes.

[0073] Comparative Example 3

[0074] Under the optimal conditions of Example 1, the detection method has higher sensitivity and precision compared with the existing analytical detection methods for quaternary triphenylphosphonium compounds and their derived phosphine oxides (Simon B., Michael P.S., Ternes, T.A., 2018. Quaternary (triphenyl-)phosphonium compounds: Environmental behavior and toxicity. Water Research. 136, 207-219.). The comparison is shown in Table 4 below.

[0075] Table 4

[0076]

[0077] The above-described embodiments are only descriptions of the preferred embodiments of the present invention and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for quantitatively determining triphenylphosphonium compounds and their derived phosphine oxides in water bodies, characterized in that, Using liquid chromatography - tandem triple quadrupole mass spectrometry, with the respective standards of 9 triphenylphosphonium compounds and their derived phosphine oxides as qualitative substances, D3-labeled methyltriphenylphosphonium iodide as the recovery indicator, and 13 13C-labeled ethyl p-hydroxybenzoate as the internal standard substance, the internal standard method was used to quantitatively determine triphenylphosphonium compounds and their derived phosphine oxides in water bodies; The mass spectrometry conditions include: selecting the electrospray ionization source mode as the positive ion mode, with a capillary voltage of 1 kV, a cone gas flow rate of 100 L / hr, an ion source temperature of 150 °C, a desolvation gas temperature of 500 °C, a flow rate of 1000 L / hr, and the scan mode using the multiple reaction monitoring mode; Liquid chromatography conditions: The chromatographic column is Phenyl, 2.1×100 mm, 1.7 μm, the injection volume is 1 μL, mobile phase A is acetonitrile, mobile phase B is an aqueous solution of 5 mM ammonium formate, and gradient elution is used.

2. The method for quantitatively determining triphenylphosphonium compounds and their derived phosphine oxides in water according to claim 1, characterized in that, The triphenylphosphonium compounds include n-butyltriphenylphosphonium bromide, methoxymethyltriphenylphosphonium chloride, benzyltriphenylphosphonium chloride, methyltriphenylphosphonium bromide, ethyltriphenylphosphonium bromide, propyltriphenylphosphonium bromide, or tetraphenylphosphonium chloride.

3. The method for quantitatively determining triphenylphosphonium compounds and their derived phosphine oxides in water according to claim 1, characterized in that, The derived phosphine oxides include triphenylphosphine oxide or diphenylphosphine oxide.

4. The method for quantitatively determining triphenylphosphonium compounds and their derived phosphine oxides in water according to claim 1, wherein During the solid-phase extraction process, before the water sample to be tested is loaded, the extraction column is activated.

5. The method for quantitatively determining triphenylphosphonium compounds and their derived phosphine oxides in water according to claim 4, characterized in that, The activation process includes: activating the extraction column with dichloromethane, acetonitrile, and water in sequence before use.

6. The method for quantitatively determining triphenylphosphonium compounds and their derived phosphine oxides in water according to claim 5, characterized in that, The extraction column is an HLB solid-phase extraction column.

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