Method for measuring the concentrations of perfluoroalkyl and polyfluoroalkyl compounds, and liquid chromatography / tandem mass spectrometry system.

Abstract

The present invention provides a perfluoroalkyl compound and a method for measuring the concentration of a polyfluoroalkyl compound, as well as a liquid chromatograph / tandem mass spectrometry system. The measurement method measures, by liquid chromatograph / tandem mass spectrometry, in a single measurement of eluting a sample with an alkaline mobile phase, the concentrations of a plurality of types of perfluoroalkyl compounds and polyfluoroalkyl compounds in the sample, including at least one or more perfluoroalkyl phosphonic acid / phosphinic acid-based compounds or polyfluoroalkyl phosphate ester-based compounds. By using an alkaline mobile phase for eluting the sample, the measurement method can complete a rapid analysis of 93 types of PFASs including perfluoroalkyl phosphonic acid / phosphinic acid-based compounds and polyfluoroalkyl phosphate ester-based compounds with a single injection.

Description

Technical Field

[0001] The present invention relates to the field of analytical chemistry technology, and specifically, to a method for measuring the concentration of perfluoro and polyfluoroalkyl compounds and a liquid chromatography / tandem mass spectrometry system.

Background Art

[0002] Perfluoroalkyl compounds and polyfluoroalkyl compounds (PFASs) have properties such as high surface activity, thermal stability, hydrophobicity, and oleophobicity, and thus are widely used in the industrial and industrial sectors. PFASs, especially perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA), have attracted wide attention because they have persistence, long-range mobility, bioaccumulation, and potential toxicity. PFOS and PFOA belong to persistent organic pollutants under the Stockholm Convention, and their production and use are restricted. In addition, as alternatives to PFOS and PFOA, more types of PFASs have been developed and produced. Detection methods for these new alternatives with potential risks in different matrices have also been reported in many research documents.

[0003] Currently, many publications, standards, and regulations describe detection methods for perfluoroalkyl carboxylic acid compounds (PFCAs), perfluoroalkyl sulfonic acid compounds (PFSAs), and perfluoroalkane sulfonamide compounds (FASAs). However, there are few relevant publications and limited detection methods for perfluoroalkylphosphonic acid compounds (PFPAs), perfluoroalkyl phosphinic acid compounds (PFPs), and polyfluoroalkyl phosphate esters (PAPs).

[0004] In their paper "Measurement of Perfluoro and Polyfluorinated Compounds in Surface Water by Ultrahigh Performance Liquid Chromatography Mass Spectrometry," published in the Chinese serial journal "Research Reports on Analytical Chemistry," 2018, vol. 9, p. 1400, Liu Xiaolei et al. disclosed an analytical method for measuring 23 types of PFASs, including perfluoroalkyl carboxylic acid compounds, perfluoroalkyl sulfonic acid compounds, perfluoroalkyl phosphonic acid compounds, perfluoroalkyl phosphinic acid compounds, and polyfluoroalkyl phosphate diesters, in water using solid-phase extraction ultrahigh performance liquid chromatography mass spectrometry. This analytical method involves using multiple parts of different mobile phases to elute the sample multiple times.

[0005] In short, prior art lacks a method for simultaneously and rapidly measuring the concentrations of a wider variety of perfluoroalkyl and polyfluoroalkyl compounds, particularly a rapid method for measuring samples containing perfluoroalkylphosphonic acids, perfluoroalkylphosphinic acid compounds, or polyfluoroalkyl phosphate esters. [Overview of the Initiative] [Means for solving the problem]

[0006] As a result of the inventor's diligent research into conventional PFASs analysis techniques, it was discovered that by replacing the mobile phase with an alkaline mobile phase, a wider variety of perfluoroalkyl and polyfluoroalkyl compounds can be effectively separated on a retention time scale. Furthermore, a wider variety of perfluoroalkyl and polyfluoroalkyl compounds can be ionized more effectively, resulting in better response characteristics for the mass spectrometer and higher detection sensitivity. In particular, samples containing perfluoroalkylphosphonic acid compounds, perfluoroalkylphosphinic acid compounds, and polyfluoroalkyl phosphate ester compounds can be efficiently separated and detected. By employing liquid chromatography / tandem mass spectrometry, accurate measurement of 93 different PFASs targets can be achieved with a single injection.

[0007] Based on the above, a first aspect of the present invention is a method for measuring the concentrations of perfluoroalkyl compounds and polyfluoroalkyl compounds, wherein the concentrations of perfluoroalkyl compounds and polyfluoroalkyl compounds, including at least one perfluoroalkylphosphonic acid / phosphinic acid compound or polyfluoroalkyl phosphate ester compound, are measured in a single measurement by liquid chromatography / tandem mass spectrometry, in which the sample is eluted with an alkaline mobile phase.

[0008] Due to limitations in the pH range of the column, alkaline mobile phases are rarely used in typical liquid chromatography / tandem mass spectrometry (LC-MS / MS) systems. Through their research, the inventors discovered that by using an alkaline mobile phase for sample elution, 93 types of PFASs target compounds, including perfluoroalkylphosphonic acid / phosphinic acid compounds and polyfluoroalkyl phosphate ester compounds, can be sequentially eluted with different retention times in a single injection. Furthermore, by performing measurements on different ion pairs using tandem mass spectrometry, these eluted PFASs can be clearly distinguished, enabling rapid and highly sensitive analysis of 93 types of PFASs with vastly different physicochemical properties in a single injection.

[0009] Optionally, the alkaline mobile phase is an alkaline mobile phase with a pH of 8 to 10. Preferably, the alkaline mobile phase is an alkaline mobile phase with a pH of approximately 9.

[0010] Optionally, perfluoroalkyl and polyfluoroalkyl compounds are combinations of multiple compounds selected from perfluoroalkyl carboxylic acids, perfluoroalkane sulfonic acids, perfluoroalkyl sulfonamides, perfluoroalkyl ether sulfonic acids (PFESA), perfluoroalkyl ether carboxylic acids (PFECA), perfluoroalkane sulfonaimido acetic acids (FASAA), perfluoroalkylphosphonic acids, perfluoroalkylphosphinic acids, polyfluoroalkyl phosphate esters, fluorotelomer alcohols (FTOHs), fluorotelomer sulfonic acids (FTSA), fluorotelomer carboxylic acids (FTCA), and fluorotelemerbetaine (FTB).

[0011] Optionally, in a single measurement, tandem mass spectrometry can switch between positive ion scanning mode and negative ion scanning mode depending on the type of perfluoroalkyl and polyfluoroalkyl compound being measured. Through this method, accurate measurement of amphoteric substances such as fluorotelemerbetaine is also possible using this optional technique.

[0012] A second aspect of the present invention is a liquid chromatograph / tandem mass spectrometry system having a mode for measuring the concentrations of perfluoroalkyl compounds and polyfluoroalkyl compounds, wherein when the liquid chromatograph / tandem mass spectrometry system is operated in the mode for measuring the concentrations of perfluoroalkyl compounds and polyfluoroalkyl compounds, it is configured to measure the concentrations of multiple types of perfluoroalkyl compounds and polyfluoroalkyl compounds in a sample, including at least one type of perfluoroalkylphosphonic acid / phosphinic acid compound or polyfluoroalkyl phosphate ester compound, in a single measurement in which the sample is eluted with an alkaline mobile phase.

[0013] Optionally, the liquid chromatograph / tandem mass spectrometry system includes perfluoroalkyl and polyfluoroalkyl compound concentration measuring tubes, and the tube material used for these measuring tubes is fluorine-free. This optional technical approach avoids the elution of fluorine into the solvent and its impact on the measurement results by not using tube material containing fluorine impurities.

[0014] Optionally, the liquid chromatography / tandem mass spectrometry system may have a delay column placed between the liquid pump and the analytical column. The delay column allows for the delay of fluorine impurities, for example, to prevent them from interfering with sample analysis due to their presence in the system's mobile phase.

[0015] Optionally, the delay column is a C18 reversed-phase column, and the analytical column is a phenylhexyl column.

[0016] Optionally, the liquid chromatography / tandem mass spectrometry system uses an electrospray ion source as the ion source for tandem mass spectrometry, with a desolvation tube temperature of 100-150°C, a heating module temperature of 200-250°C, and an interface temperature of 300-350°C. This optional technique reduces in-source pyrolysis of the ion source and improves detection sensitivity by lowering the temperatures of the desolvation tube, heating module, and interface. [Brief explanation of the drawing]

[0017] [Figure 1] This is a schematic diagram of the structure of an LC-MS / MS system according to an embodiment of the present invention. [Figure 2] This is a chromatogram obtained by analyzing 93 types of PFASs in a single injection using the LC-MS / MS system of the embodiment of the present invention. [Figure 3] This calibration curve was prepared using standard solutions with PFOA, PFOS, ADONA, and PFODA as the target substances, using the LC-MS / MS system of the embodiment of the present invention. [Figure 4] This calibration curve was prepared using standard solutions with PFOA, PFOS, ADONA, and PFODA as the target substances, using the LC-MS / MS system of the embodiment of the present invention. [Figure 5] This calibration curve was prepared using standard solutions with PFOA, PFOS, ADONA, and PFODA as the target substances, using the LC-MS / MS system of the embodiment of the present invention. [Figure 6] This calibration curve was prepared using standard solutions with PFOA, PFOS, ADONA, and PFODA as the target substances, using the LC-MS / MS system of the embodiment of the present invention. [Figure 7] This is a chromatogram obtained by analyzing 10 types of fluoritelomeric alcohol-based PFASs in a single injection using the GC-MS / MS system of the embodiment of the present invention. [Modes for carrying out the invention]

[0018] The following will clearly and completely describe the technical solution in this embodiment in accordance with the drawings in this embodiment. It is clear that the described embodiments are only a part of the embodiments of the present invention and not all of them. Based on the embodiments of the present invention, those skilled in the art will understand that all other embodiments obtained without creative labor fall within the protection scope of the present invention.

[0019] 1. <Terms and Their Definitions> Perfluoroalkyl compounds and polyfluoroalkyl compounds are alkyl compounds in which all or a plurality of hydrogen atoms are substituted by fluorine atoms, including multiple types of compounds such as perfluoroalkyl carboxylic acids, perfluoroalkyl sulfonic acids, perfluoroalkyl sulfonamides, perfluoroalkyl ether sulfonates, perfluoroalkyl ether carboxylic acids, perfluoroalkyl sulfonamide acetic acids, perfluoroalkyl phosphonic acids, perfluoroalkyl phosphinic acids, polyfluoroalkyl phosphates, fluorotelomers (e.g., fluorotelomer alcohols, fluorotelomer sulfonic acids, fluorotelomer carboxylic acids, fluorotelomer betaines), etc.

[0020] The term "perfluorophosphonic acid / phosphinic acid-based compound" refers to one selected from perfluorophosphonic acid-based compounds and perfluorophosphinic acid-based compounds.

[0021] 2. <System Device Composition> 2.1 Device Composition of Liquid Chromatograph / Tandem Mass Spectrometry System (LC-MS / MS) Referring to FIG. 1, in this embodiment, the measurement of PFASs is carried out using a liquid chromatograph / tandem mass spectrometry system. This LC-MS / MS analysis system includes one dual pump (with a pressure resistance of 70 MPa or more, consisting of two parallel liquid pumps 1), one autosampler 3 (with a pressure resistance of 70 MPa or more), one column oven 5, one triple quadrupole mass spectrometer 6 (tandem mass spectrometry), one delay column 2, and one analytical column 4. In order to avoid fluorine eluting into the solvent and affecting the measurement results, all pipelines in the flow path use stainless steel pipelines, PE pipes, or PP pipes instead of fluororesin pipelines.

[0022] The delay column 2 is provided between the liquid pump 1 and the analytical column 4, and further between the liquid pump 1 and the autosampler 3. In this embodiment, a C18 reversed-phase column is used as the delay column 2. Specifically, it may also be a column with model number Shim-pack XR-ODS, 3 mm ID × 50 mm, and a particle size of 2.2 μm. It is used to delay fluorine impurities so as to prevent the sample analysis from being disturbed by the fluorine impurities present in the mobile phase of the system.

[0023] The analytical column 4 is a phenylhexyl column. Specifically, it may also be a column with model number Shim-pack GIST Phenyl-Hexyl, 2.1 mm ID × 100 mm, and a particle size of 3 μm. It is a column that preferably uses an alkaline mobile phase and is used for the chromatographic separation of PFASs in the sample.

[0024] An electrospray ion source is used as the ion source of the triple quadrupole mass spectrometer 6. The operating mode of the triple quadrupole mass spectrometer 6 may be the multiple reaction monitoring (MRM) mode or the selected reaction monitoring (SRM) mode, but the MRM mode is preferred.

[0025] 2.2 Instrumental composition of a gas chromatograph / tandem mass spectrometry system (GC-MS / MS) The GC-MS / MS analysis system consists of one liquid autosampler, one liquid sample tray, one two-gas chromatograph-triple quadrupole rod tandem mass spectrometer, and a gas chromatograph analysis column (not shown). The GC-MS / MS system vaporizes the liquid sample before injection and analysis. In this example, the gas chromatograph / tandem mass spectrometer system is mainly used for the analysis of fluorine telomer alcohol-based substances in the sample.

[0026] The analytical column used in the gas chromatography was an InertCap Pure-WAX 30m x 0.25mm ID df=0.25μm (GL Sciences).

[0027] 3. Reagents and Materials 3.1 Standard Solutions a) Standard stock solution of perfluoroalkyl and polyfluoroalkyl compounds: ρ = 2000 μg / L Standard solutions can be purchased directly from certified sources or prepared from the standard substance and methanol. Stock solutions should be stored in sealed brown sample bottles at -20°C or according to the manufacturer's instructions. They should be allowed to return to room temperature and shaken well before use.

[0028] b) Standard solution for perfluoroalkyl and polyfluoroalkyl compounds: ρ = 200 μg / L Dilute the perfluoroalkyl and polyfluoroalkyl compound standard stock solutions with methanol as needed. Store the standard solutions in a cool, dark place at -20°C. Allow to return to room temperature and shake well before use. The shelf life is 30 days.

[0029] c) Internal standard stock solution: ρ = 2000 μg / L The internal standards are MPFBA, M2-6:2PAP, M2-4:2FTSA, M3PFBS, MPFHxA, M3HFPO-DA, M6:2 FTUCA, M6:2 FTCA, M2-8:2 PAP, M2-6:2FTSA, MPFOA, MPFHxS, M8:2 FTCA, MPFNA, M2-8:2FTSA, MPFDA, d3-N-MeFOSAA, d5-N-EtFOSAA, d7-N-MeFOSE, d9-N-EtFOSE, M10:2 FTCA, MPFOS, M10:2 FTUCA, MPFUdA, MPFDoA, M4:2 FTOH, M6:2 FTOH, M8:2 FTOH, and M10:2 FTOH isotopic standards. For internal standard stock solutions, certified standard solutions can be purchased directly or prepared with the standard substance and methanol. The stock solution should be stored in a sealed brown sample bottle at -20°C or according to the manufacturer's instructions. It should be allowed to return to room temperature and shaken well before use.

[0030] d) Internal standard working solution: ρ=200μg / L Dilute the internal standard stock solution with methanol as needed. Store the internal standard solution in a cool, dark place at -20°C. It should be returned to room temperature and shaken well before use. The shelf life is 30 days.

[0031] 3.2 Reagents a) Acetonitrile (CH3CN): Purity for chromatography b) Methanol (CH3OH): Purity for chromatography c) Ammonium acetate (CH3COONH4): Purity for chromatography d) Formic acid (HCOOH): Purity for chromatography e) Ammonia solution: w=25%, GR (Guaranteed Reagent) purity f) Water: Milli-Q ultrapure water g) Nitrogen: Purity ≥ 99.99% Solutions such as ammonium acetate and aqueous ammonia / methanol are obtained by preparing the reagents described above. All other reagents not described in this section are of chromatographic purity.

[0032] 4. <Sample Preprocessing> a. Environmental water samples Environmental water samples may be collected, transported, and stored in accordance with the correlation requirements described in HJ / T91 (China "Technical Standards for Surface Water and Wastewater Monitoring") and HJ494 (China "Water Quality Sampling Manual"). When collecting environmental water samples, seal and store the water samples in a 1L wide-mouth polypropylene plastic bottle. When collecting samples, record information such as the sample number, source, and conditions of collection. The samples should be transported to the laboratory as quickly as possible, stored at 4°C, and the sample analysis work should be completed within 7 days. Before testing, a fixed amount of the internal standard substance or internal standard solution should be added to the sample, and it should be purified using a solid-phase extraction column before being measured.

[0033] b. Soil samples Weigh 1 g of soil sample and place it in a polypropylene centrifuge tube. Add the internal standard substance or internal standard solution. Add 10 mL of methanol, perform sonication extraction for 20 mins, and centrifuge to obtain the supernatant. Repeat this process twice. After sealing the supernatant, concentrate it to 1 mL by nitrogen blowing, dilute with water, purify using a solid-phase extraction column, and then use as the sample for analysis.

[0034] c. Dust sample Place 0.1 g of the sample in a 15 mL centrifuge tube, add the internal standard substance or internal standard solution, then add 5 mL of methanol as the extraction solvent, extract by shaking three times, concentrate to 1 mL by nitrogen blowing, dilute with water, purify using a solid-phase extraction column, and then use as the sample for analysis.

[0035] d. Spinning samples Cut the sample into 2mm x 2mm pieces, place 1g of the sample in a reagent bottle, and add the internal standard or internal standard solution. Add 10mL of ethyl acetate solution, cover, and bathe in water at 60°C for 120 minutes. Afterwards, pass the extracted solution through a 0.22μm micropore filter membrane, concentrate it 10-fold by nitrogen blowing, and place it in a 1.5mL brown sample bottle for measurement.

[0036] e. Food samples Place 0.1 g of food sample in a 15 mL centrifuge tube, add the internal standard substance or internal standard solution, then add 10 mL of 50 mM KOH methanol solution, shake at 250 rpm for 0.5 hours, concentrate the extract to 1 mL, add 0.5 mL of 1 M HCl, dilute with water to 50 mL, purify using a solid-phase extraction column, and then use for measurement.

[0037] f.Food packaging materials Cut the food packaging material sample into 2mm*2mm blocks, pack them into a clean container, seal it, and mark it. Before testing, weigh 1g of the sample, place it in a 50mL centrifuge tube, add the internal standard substance or internal standard solution, mix thoroughly, add 10mL of methanol, sonicate extract for 40min, centrifuge at 10,000r / min for 5min, take 5mL of the supernatant, place it in a 15mL centrifuge tube, concentrate to 0.5 by nitrogen blowing at 40°C, dilute with 12mL of water, purify using a solid-phase extraction column, and then use as the sample for measurement.

[0038] g.Blood Let's take fetal bovine serum, a biological sample, as an example. Place 0.5 mL of fetal bovine serum (FBS) in a 15 mL centrifuge tube, add the internal standard or internal standard solution, shake gently for 30 seconds, and then age in a 4°C refrigerator for 4 hours. Next, add 1 mL of 0.5 mol / LTBA dispersant and 2 mL of 0.25 mol / LNa2CO3 buffer to the centrifuge tube, vortex for 10 seconds, then add 4 mL of methyl tert-butyl ether (MTBE), shake in a shaker at 270 rpm for 20 minutes, and then centrifuge for another 10 minutes (temperature 15°C, rotation speed 4000 rpm), and take the supernatant. Add 4 mL of MTBE to the centrifuge tube, repeat the above procedure three times, and collect 12 mL of extract. Subsequently, 1 mL of methanol is added to the above combined valve extract, and it is concentrated to 0.5 by nitrogen blasting (at a temperature of 45°C). Then, 12 mL of ultrapure water is added for dilution, and after purification using a solid-phase extraction column, it is used for measurement.

[0039] h. Urine fluid After adding the internal standard substance or internal standard solution to 1 mL of urine, dilute with 13 mL of ultrapure water, purify using a solid-phase extraction column, and then use as the sample for analysis.

[0040] The type of solid-phase extraction column used for sample purification can be selected from either a wax solid-phase extraction column or an HLB solid-phase extraction column, depending on the type of PFASs target substance. In Table 2, samples for which LC-MS / MS analysis will be continued can be purified using a wax solid-phase extraction column, such as a SHIMSEN Styra WAX 60 mg / 3 mL solid-phase extraction column. In Table 4, samples for which GC-MS / MS analysis will be continued can be purified using an HLB solid-phase extraction column. Furthermore, the procedure for using a wax solid-phase extraction column with blood samples may be treated separately from that for normal samples.

[0041] <Procedure for using a WAX / HLB solid-phase extraction column with typical samples> In the wax solid-phase extraction column, the column is activated with 4 mL of 0.1% ammonia-methanol solution, 4 mL of methanol, and 4 mL of water. After setting the sample, impurities are removed with 4 mL of pH=4 ammonium acetate solution, and the water is removed from the solid-phase extraction column using a pump. Elution is then performed with 4 mL of methanol and 4 mL of 0.1% ammonia-methanol solution. The eluate is concentrated to 1 mL and transferred to a sample bottle for analysis.

[0042] The HLB solid-phase extraction column is activated with 7 mL of methanol and 7 mL of water. After setting the diluted extract, impurities are removed by washing with 5 mL of 20% methanol / aqueous solution. Then, water is removed from the solid-phase extraction column using a pump, and finally, the target compound is eluted with 10 mL of methanol. The eluate is concentrated to 1 mL and transferred to a sample bottle for analysis.

[0043] <Detailed Chromatography Procedure Using a Wax Solid-Phase Extraction Column for Blood Samples> Rinse: Pass 4 mL of 0.1% ammonia methanol, 4 mL of chromatographic-grade methanol, and 4 mL of ultrapure water through the column in sequence.

[0044] Sample setup: Pour the sample (0.5 mL concentrate + 12 mL water) into the column. Specifically, add 10 mL of ultrapure water to a 15 mL centrifuge tube, vortex for 10 seconds, and then pour into the column. Next, add a dilute methanol aqueous solution (5 mL water + 0.5 mL methanol) to the centrifuge tube, vortex, and then pour into the column.

[0045] Impurity removal: After the above sample setup is complete, add NH4Ac (25 mmol / L).

[0046] Moisture removal: Operate the vacuum pump for 30 minutes to aspirate and remove moisture from the column. Turn the pump off at a set time.

[0047] Received: Place the sample in a new 15 mL centrifuge tube and sequentially elute with 4 mL of methanol and 0.1% ammonia-methanol solution.

[0048] After almost completely drying the received solution by nitrogen blowing at 50°C, it is redissolved in 0.2 mL of pure methanol. After standing for 10 minutes, it is transferred to a 2 mL microvolume centrifuge tube and frozen overnight in a refrigerator at -20°C. On the second day, after removal, it is subjected to high-speed centrifugation at low temperature for 10 minutes (speed: 12000 rpm, temperature: 4°C). Then, 100 μL is taken and placed in a sample vial, and the measurement is performed.

[0049] The above sample pretreatment method is illustrative, and in other embodiments of the present invention, other samples may be analyzed, or different pretreatment methods may be employed.

[0050] 5. <Analysis Steps> 5.1 Equipment conditions 5.1.1 Reference Conditions for Liquid Chromatography / Tandem Mass Spectrometry (LC-MS / MS) [Examples]

[0051] <Examples> Column temperature: 40℃ Injection volume: 5 μL Flow rate: 0.4mL / min Mobile phase A contains a 20 mM ammonium acetate and a 0.1% (v / v) NH4OH aqueous solution, with a pH of approximately 9. This pH does not exceed the pH range used by the Shim-pack GIST Phenyl-Hexyl analytical column.

[0052] Mobile phase B: Acetonitrile Gradient Program:

[0053] [Table 1]

[0054] Mass spectrometry (MS) reference conditions: Ion source: ESI Atomization gas flow rate: 3.0 L / min Dry gas flow rate: 10.0 L / min Heating gas flow rate: 10.0 L / min Desolvation tube temperature: 100℃ Heating module temperature: 200℃ Interface temperature: 300℃ Furthermore, regarding the ESI ion source, in conventional technology, the desolvation tube temperature is typically around 250°C, the heating module temperature around 300°C, and the interface temperature around 350°C, which are commonly selected for PFASs analysis. In this example, by lowering the desolvation tube temperature, heating module temperature, and interface temperature, in-source dissociation can be effectively reduced, and detection sensitivity can be improved.

[0055] Scan Mode: MRM multiple reaction ion monitoring. Parent-daughter ion pairs for quantitative or qualitative analysis were pre-configured and stored in the tandem mass spectrometer. See Tables 2 and 3 for specific detection parameters.

[0056] In this embodiment, tandem mass spectrometry primarily performs negative ion scanning, but some channels can be switched to positive ion scanning during predetermined time periods. Specifically, in a single measurement, tandem mass spectrometry switches between positive ion scanning mode and negative ion scanning mode depending on the type of perfluoroalkyl and polyfluoroalkyl compound being measured. In this embodiment, for 5:3 FTB and 5:1:2 FTB fluorotelemer betaine samples, the system is executed or switched to positive ion scanning mode, while other time periods or channels employ negative ion scanning mode.

[0057] [Table 2-1]

[0058] [Table 2-2]

[0059] [Table 3-1]

[0060] [Table 3-2]

[0061] [Table 3-3]

[0062] [Table 3-4]

[0063] [Table 3-5]

[0064] The concentration of the target substance is measured according to the internal standard method. In this embodiment, as shown in Figure 3, 93 types of PFASs target substances are used with 25 types of intra-isotopic standards. Accordingly, the 93 types of PFASs are divided into 25 groups, and one type of intra-isotopic standard is used for each group.

[0065] Taking the group that uses MPFBA as the intra-isotope standard as an example, this group includes a total of nine types of PFASs: PFBA, PFHxPA, PF4OPeA, Cl-PFHxPA, 3:3 FTCA, 5:3 FTCA, PH50HxA, FHxSA, and MPFBA. Each of PFBA, PFHxPA, PF4OPeA, Cl-PFHxPA, 3:3 FTCA, 5:3 FTCA, PH5OHxA, and FHxSA has its concentration ratio with MPFBA determined based on a calibration curve using the peak area / peak height ratio with MPFBA, and then its mass concentration is determined according to equation (1).

[0066]

number

[0067] The calibration curve is generated based on the measurement of standard solutions of the target substance at different concentrations (internal standardization). The x-coordinate is the concentration ratio of the target substance to the corresponding internal standard, and the y-coordinate is the ratio of the peak area / peak height of the target substance to the peak area / peak height of the internal standard.

[0068] Note that the correspondence and grouping methods of different PFASs and isotopic standards in Table 3 are illustrative and not particularly limiting, and those skilled in the art can adjust the correspondence and grouping methods for each target substance according to the actual situation.

[0069] 5.1.2 Reference Conditions for Gas Chromatography / Tandem Mass Spectrometry (GC-MS / MS) Inlet temperature: 280℃ Column oven heating program: Hold at 40°C for 1 minute, then heat up to 240°C at a rate of 20°C / min and hold for 3 minutes.

[0070] Sampling volume: 1 μL Carrier gas control method: constant speed Linear speed: 43.5cm / sec Injection method: Splitless injection Mass spectrometry reference conditions: Ion source temperature: 200℃ Interface temperature: 300℃ Detector voltage: +0.1kV (relative voltage value) Scanning mode: Multiple response monitoring (MRM). See Tables 4 and 5 for specific detection parameters.

[0071] [Table 4]

[0072] [Table 5]

[0073] 6. <Test Results> 6.1 LC-MS / MS Test Results Based on the LC-MS / MS conditions in <Examples>, a mixture of PFASs is analyzed. Specifically, during the process of eluting the sample in a single alkaline mobile phase (containing an aqueous solution of 20 mM ammonium acetate and 0.1% (v / v) NH4OH, pH ≈ 9) (i.e., a single injection), 93 types of PFASs in the sample can be sequentially eluted at different retention times. Furthermore, the signal intensities of different ion pairs for quantitative / qualitative analysis are recorded in multiple channels of tandem mass spectrometry, and these eluted PFASs can be clearly distinguished by the MRM scanning pattern of tandem mass spectrometry, obtaining a chromatogram as shown in Figure 2. In Figure 2, the horizontal axis represents retention time, and the vertical axis represents the signal intensity of the scanning of specific ion pairs by tandem mass spectrometry.

[0074] Referring to Figure 2, the alkaline mobile phase causes peaks to appear sequentially at different retention times for the 93 target PFASs. By rationally designing the working parameters of tandem mass spectrometry, for example, by designing a combination of time series of target ion pairs across multiple channels, it is possible to measure all of these many types of PFASs in a single elution without requiring a large number of channels. Furthermore, it is possible to ionize a greater variety of perfluoro and polyfluorinated compounds more effectively, resulting in better response characteristics for the tandem mass spectrometry detector and higher detection sensitivity. Furthermore, these 93 types of PFASs include different types of PFASs, specifically perfluoroalkyl carboxylic acids, perfluoroalkyl sulfonic acids, perfluoroalkyl sulfonamides, perfluoroalkyl ether sulfonates, perfluoroalkyl ether carboxylic acids, perfluoroalkyl sulfonamide vinegars, perfluoroalkyl phosphonic acids, perfluoroalkyl phosphinic acids, polyfluoroalkyl phosphates, fluorotelomers (e.g., fluorotelomer alcohols, fluorotelomer sulfonic acids, fluorotelomer carboxylic acids, fluorotelomer betaines), and any other suitable types of PFASs.

[0075] Figures 3 to 6 show calibration curves prepared using standard solutions for PFOA, PFOS, ADONA, and PFODA, respectively, in the LC-MS / MS system of the embodiment of the present invention. In Figures 3 to 6, the horizontal axis represents the concentration ratio of the target substance to the corresponding internal standard solution, and the vertical axis represents the area ratio of the corresponding peaks.

[0076] Referring to Figures 3 to 6, it can be seen that the method provided by this embodiment exhibits good linearity with respect to various types of perfluoroalkyl compounds and polyfluoroalkyl compounds.

[0077] 6.2 GC-MS / MS test results Figure 7 shows the chromatograms of the 10 fluoritelomeric alcohol compounds obtained in this example, which were also obtained in a single injection analysis. The horizontal axis represents retention time, and the vertical axis represents the signal intensity of the scanning of specific ion pairs by tandem mass spectrometry. As shown in Figure 7, the 10 fluoritelomeric alcohol compounds sequentially appear at different retention times. Furthermore, by recording the signal intensities of different parent-daughter ion pairs for quantitative / qualitative analysis in multiple channels of tandem mass spectrometry, they can be clearly distinguished in the MRM scanning pattern of the tandem mass spectrometry.

[0078] In this embodiment, rapid analysis of 93 types of PFASs was completed with a single injection. However, the embodiments of the present invention are not limited to the analysis of a specified number of PFASs with a single injection. The number may be increased or decreased as long as it does not exceed the spirit of the invention. For example, some types of PFASs may be selected for analysis, or other types of PFASs may be added or substituted.

[0079] The foregoing is not intended to limit the present invention, but rather to describe preferred embodiments of the invention, and any modifications, equivalent substitutions, and improvements made in accordance with the spirit of the invention are included within the scope of protection of the present invention. [Explanation of symbols]

[0080] 1. Liquid pump 2 Delay Column 3 Autosampler 4 Analysis Columns 5-column oven 6. Triple Quadrupole Mass Spectrometer

Claims

1. A method for measuring the concentrations of perfluoroalkyl compounds and polyfluoroalkyl compounds, characterized in that the concentrations of perfluoroalkyl compounds and polyfluoroalkyl compounds, which include at least one perfluoroalkylphosphonic acid / phosphinic acid compound or polyfluoroalkyl phosphate ester compound, are measured in a single measurement by liquid chromatography / tandem mass spectrometry, wherein a phenylhexyl column is used as the analytical column.

2. The method for measuring perfluoroalkyl compounds and polyfluoroalkyl compounds according to claim 1, characterized in that the alkaline mobile phase is an alkaline mobile phase with a pH of 8 to 10.

3. The method for measuring the concentration of perfluoroalkyl compounds and polyfluoroalkyl compounds according to claim 2, characterized in that the alkaline mobile phase has a pH of approximately 9.

4. The method for measuring perfluoroalkyl compounds and polyfluoroalkyl compounds according to claim 1, characterized in that the perfluoroalkyl compound and polyfluoroalkyl compound are a combination of multiple types selected from perfluoroalkyl carboxylic acid, perfluoroalkyl sulfonic acid, perfluoroalkyl sulfonamide, perfluoroalkyl ether sulfonate, perfluoroalkyl ether carboxylic acid, perfluoroalkyl sulfonamide acetate, perfluoroalkylphosphonic acid, perfluoroalkylphosphinic acid, polyfluoroalkyl phosphate, fluorotelomer sulfonic acid, fluorotelomer carboxylic acid, and fluorotelomer betaine.

5. The method for measuring perfluoroalkyl compounds and polyfluoroalkyl compounds according to claim 1, characterized in that, in a single measurement, tandem mass spectrometry is used to switch between a positive ion scanning mode and a negative ion scanning mode depending on the type of perfluoroalkyl compound and polyfluoroalkyl compound to be measured.

6. A liquid chromatograph / tandem mass spectrometry system, wherein the liquid chromatograph / tandem mass spectrometry system has a mode for measuring the concentrations of perfluoroalkyl compounds and polyfluoroalkyl compounds, and when the liquid chromatograph / tandem mass spectrometry system is operated in the mode for measuring the concentrations of perfluoroalkyl compounds and polyfluoroalkyl compounds, the system is configured to measure the concentrations of multiple types of perfluoroalkyl compounds and polyfluoroalkyl compounds in the sample, including at least one type of perfluoroalkylphosphonic acid / phosphinic acid compound or polyfluoroalkyl phosphate ester compound, in a single measurement in which the sample is eluted with an alkaline mobile phase, and the liquid chromatograph / tandem mass spectrometry system includes an analytical column, the analytical column being a phenylhexyl column.

7. The liquid chromatograph / tandem mass spectrometry system according to claim 6, wherein the liquid chromatograph / tandem mass spectrometry system has a perfluoroalkyl compound and polyfluoroalkyl compound concentration measuring conduit, and the tubing material used for the perfluoroalkyl compound and polyfluoroalkyl compound measurement conduit does not contain fluorine.

8. The liquid chromatograph / tandem mass spectrometry system according to claim 6, characterized in that it has a delay column installed between the liquid pump and the analysis column.

9. The liquid chromatograph / tandem mass spectrometry system according to claim 8, characterized in that the delay column is a C18 reversed-phase column.

10. The liquid chromatograph / tandem mass spectrometry system according to claim 6, characterized in that an electrospray ion source is used as the ion source for tandem mass spectrometry, the desolvation tube temperature of the electrospray ion source is 100 to 150°C, the heating module temperature is 200 to 250°C, and the interface temperature is 300 to 350°C.

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