Perfluoroalkyl Compound, Method for Measuring Concentration of Polyfluoroalkyl Compound, and Liquid Chromatograph / 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. Specifically, it is a method for measuring the concentration of perfluoro and polyfluoroalkyl compounds and a liquid chromatograph / tandem mass spectrometry system.

Background Art

[0002] Perfluoroalkyl compounds and polyfluoroalkyl compounds (PFASs) have characteristics such as high surface activity, thermal stability, hydrophobicity, and oleophobicity, and thus are widely used in industry and the industrial sector. PFASs, especially perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA), have attracted wide attention because of their 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] At present, regarding perfluoroalkylcarboxylic acids (PFCAs), perfluoroalkyl sulfonic acids (PFSAs), perfluoroalkane sulfonamides (FASAs), etc., their detection methods have been described in many literatures, standards and regulations. However, for perfluoroalkylphosphonic acids (PFPAs) compounds, perfluoroalkyl phosphinic acids (PFPis) compounds and polyfluoroalkyl phosphate esters (PAPs) compounds, there are few reports in the related literature and the detection methods are limited.

[0004] In the "Determination of Perfluoro and Polyfluorinated Compounds in Surface Water by Ultra-High Performance Liquid Chromatography-Mass Spectrometry" published by Liu Xiaolei et al. in the Chinese serial publication "Research Report on Analytical Chemistry", 2018, vol9, p1400, an analytical method for measuring 23 types of PFASs such as perfluoroalkylcarboxylic acid compounds, perfluoroalkyl sulfonic acid compounds, perfluoroalkylphosphonic acid compounds, perfluoroalkyl phosphinic acid compounds, and polyfluoroalkyl phosphate diesters in water by solid-phase extraction ultra-high performance liquid chromatography-mass spectrometry was disclosed. By the way, in this analytical method, a plurality of different types of mobile phases are used in multiple parts to elute the sample multiple times.

[0005] In short, the prior art lacks a measurement method capable of simultaneously and rapidly measuring the concentrations of more types of perfluoroalkyl compounds and polyfluoroalkyl compounds, especially a rapid measurement method for samples containing perfluoroalkylphosphonic acids or perfluoroalkyl phosphinic acid-based compounds or polyfluoroalkyl phosphate esters.

Summary of the Invention

Means for Solving the Problems

[0006] As a result of the inventors' intensive research on conventional PFASs analysis techniques, by replacing the mobile phase with an alkaline mobile phase, more types of perfluoroalkyl compounds and polyfluoroalkyl compounds can be effectively separated on the retention time scale. Furthermore, more types of perfluoroalkyl compounds and polyfluoroalkyl compounds can be ionized better, have better response characteristics for the mass spectrometry detector, and higher detection sensitivity can be obtained. In particular, samples containing perfluoroalkylphosphonic acid-based compounds, perfluoroalkylphosphinic acid-based compounds, and polyfluoroalkyl phosphate ester-based compounds can be efficiently separated and detected. By adopting liquid chromatography / tandem mass spectrometry, accurate measurement of 93 types of PFASs target substances can be realized in one injection.

[0007] Based on the above, a first aspect of the present invention is a method for measuring the concentration of perfluoroalkyl compounds and polyfluoroalkyl compounds, which measures the concentration of perfluoroalkyl compounds and polyfluoroalkyl compounds in a sample containing a plurality of types, at least one type or more of perfluoroalkylphosphonic acid / phosphinic acid-based compounds or polyfluoroalkyl phosphate ester-based compounds in one measurement by eluting the sample with an alkaline mobile phase by liquid chromatography / tandem mass spectrometry.

[0008] Since there are limitations on the pH range of use for columns, alkaline mobile phases are rarely adopted in common liquid chromatography / tandem mass spectrometry (LC-MS / MS) systems. Through research, the inventors found that by using an alkaline mobile phase for sample elution, 93 PFAS target compounds including perfluoroalkylphosphonic acid / phosphinic acid compounds and polyfluoroalkyl phosphate ester compounds can be sequentially eluted at different retention times with a single injection. Furthermore, by measuring different ion pairs through tandem mass spectrometry, these eluted PFASs can be clearly distinguished, and it was discovered that it is possible to achieve rapid and highly sensitive analysis of 93 PFASs with huge differences in physicochemical properties with 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, the perfluoroalkyl compound and the polyfluoroalkyl compound are a combination of multiple types 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), perfluoroalkyl phosphonic acids, perfluoroalkyl phosphinic 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 switches between the positive ion scanning mode and the negative ion scanning mode depending on the types of the perfluoroalkyl compound and the polyfluoroalkyl compound to be measured. By the above method, accurate measurement of amphoteric substances such as fluorotelemerbetaine is also possible with the optional technical solution.

[0012] A second aspect of the present application is a liquid chromatography / tandem mass spectrometry system having a measurement mode for the concentrations of perfluoroalkyl compounds and polyfluoroalkyl compounds, and when the liquid chromatography / tandem mass spectrometry system in the measurement mode for the concentrations of the perfluoroalkyl compounds and polyfluoroalkyl compounds is operated, 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 including at least one or more types of perfluoroalkylphosphonic acid / phosphinic acid compounds or polyfluoroalkyl phosphate ester compounds in the sample are measured.

[0013] Optionally, the liquid chromatography / tandem mass spectrometry system has a perfluoroalkyl compound and polyfluoroalkyl compound concentration measurement pipeline, and the pipe material used for the perfluoroalkyl compound and polyfluoroalkyl compound measurement pipeline does not contain fluorine. By not using a pipe material containing fluorine impurities, this optional technical solution can avoid fluorine being eluted into the solvent and affecting the measurement results.

[0014] Optionally, the liquid chromatography / tandem mass spectrometry system has a delay column installed between the liquid pump and the analytical column. By using the delay column, for example, fluorine impurities can be delayed so as to prevent the fluorine impurities from interfering with the sample analysis due to the fluorine impurities present in the mobile phase of the system.

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

[0016] Optionally, the liquid chromatography / tandem mass spectrometry system uses an electrospray ionization source as the ion source for tandem mass spectrometry. The desolvation tube temperature of the electrospray ionization source is 100-150°C, the heating module temperature is 200-250°C, and the interface temperature is 300-350°C. In this optional technical solution, by reducing the desolvation tube, heating module, and interface temperatures, in-source pyrolysis of the ion source can be reduced, and the detection sensitivity can be improved.

Brief Description of the Drawings

[0017]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Modes for Carrying Out the Invention

[0018] The technical solution in the present embodiment will be clearly and completely described below in conjunction with the drawings in the present embodiment. However, it is obvious that the described embodiments are only a part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, those skilled in the art will obtain all other embodiments without creative labor, and all of them belong to 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 a plurality of 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 (for example, 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. <Device Composition of the System> 2.1 Device Composition of the 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. To avoid fluorine eluting into the solvent and affecting the measurement results, all the pipelines in the flow path are made of stainless steel pipelines, PE pipes, or PP pipes, without using 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 reverse-phase column is used as the delay column 2, specifically, a column with model number Shim-pack XR-ODS, 3 mm ID × 50 mm, and a particle size of 2.2 μm may also be used. It is used to delay fluorine impurities to prevent them from interfering with sample analysis due to the fluorine impurities present in the mobile phase of the system.

[0023] The analytical column 4 is a phenylhexyl column, specifically, a column with model number Shim-pack GIST Phenyl-Hexyl, 2.1 mm ID × 100 mm, and a particle size of 3 μm may also be used. It is a column that preferably uses an alkaline mobile phase and is used for 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 Gas Chromatograph / Tandem Mass Spectrometry System (GC-MS / MS) Instrument Composition The GC-MS / MS analysis system consists of one liquid autosampler, one liquid sample tray, one 2 gas chromatograph-triple quadrupole rod tandem mass spectrometer, and a gas chromatograph analysis column (not shown). The GC-MS / MS system vaporizes and then injects the liquid sample for analysis. The gas chromatograph / tandem mass spectrometry system in this example is mainly used for the analysis of fluorotelomer alcohol substances in the sample.

[0026] The model number of the analysis column used in the gas chromatograph is InertCap Pure-WAX 30m×0.25mm I.D. df = 0.25μm (GL Sciences).

[0027] 3. <Reagents and Materials> 3.1 Standard Solutions a) Perfluoroalkyl and polyfluoroalkyl compound standard stock solution: ρ = 2000 μg / L For the standard solution, a certified standard solution can be purchased directly or prepared with a standard substance and methanol. The stock solution should be stored sealed using a brown sample bottle, stored at -20°C, or stored according to the manufacturer's manual. It should be returned to room temperature, shaken well, and then used.

[0028] b) Perfluoroalkyl and polyfluoroalkyl compound standard working solution: ρ = 200 μg / L Dilute the perfluoroalkyl and polyfluoroalkyl compound standard stock solution with methanol as needed. The standard working solution should be stored at -20°C in a place not exposed to sunlight. It should be returned to room temperature, shaken well, and then used. 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, M10:2 FTOH isotope internal standards. For the internal standard stock solution, a certified standard solution can be directly purchased or prepared with a standard substance and methanol. The stock solution should be stored sealed using a brown sample bottle, stored at -20 °C or stored according to the manufacturer's manual. It should be returned to room temperature, shaken well, and then used.

[0030] d) Internal standard working solution: ρ = 200 μg / L Dilute the internal standard stock solution with methanol as needed. The internal standard working solution should be stored at -20 °C in a place not exposed to sunlight. It should be returned to room temperature, shaken well, and then used. The storage period is 30 days.

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

[0032] 4. <Sample Pretreatment> a. Environmental water sample The environmental water sample may be collected, transported, and stored in accordance with the relevant requirements described in HJ / T 91 (Technical Standards for Surface Water and Wastewater Monitoring in China) and HJ 494 (Water Quality Sampling Manual in China). When collecting the environmental water sample, use a 1L polypropylene plastic wide-mouth bottle to seal and store the water sample. When collecting the sample, record information such as the sample number, source, and situation at the time of collection. The sample should be transported to the laboratory as soon as possible, stored at 4°C, and the sample analysis work should be completed within 7 days. Before inspection, add a certain amount of internal standard reference substance or internal standard working solution to the sample, purify it with a solid-phase extraction column, and then use it as the measurement target.

[0033] b. Soil sample Weigh 1g of the soil sample and put it into a polypropylene centrifuge tube, and then add the internal standard reference substance or internal standard working solution. Add 10 mL of methanol and perform ultrasonic extraction for 20 min, and repeat the operation of centrifuging to obtain the supernatant twice. After combining the supernatants, concentrate it to 1 mL by nitrogen blowing, dilute it with water, purify it with a solid-phase extraction column, and then use it as the measurement target.

[0034] c. Dust sample Put 0.1g of the sample into a 15 mL centrifuge tube, add the internal standard reference substance or internal standard working solution, and further add 5 mL of methanol as the extraction solvent. After shaking extraction three times, concentrate it to 1 mL by nitrogen blowing, dilute it with water, purify it with a solid-phase extraction column, and then use it as the measurement target.

[0035] d. Textile sample Cut the sample into a size of 2mm x 2mm, put 1g of the sample into a reagent bottle, and add the internal standard reference substance or internal standard working solution. Add 10 mL of ethyl acetate solution, cover it, and perform a water bath at 60°C for 120 minutes. Then, pass the extraction solution through a 0.22μm microporous filtration membrane, concentrate it 10 times by nitrogen blowing, put it into a 1.5 mL brown sample bottle, and use it as the measurement target.

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

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

[0038] g. Blood Taking bovine fetal serum, a biological sample, as an example. Put 0.5 mL of bovine fetal serum (FBS) into a 15 mL centrifuge tube, add the internal standard substance or internal standard working solution, gently shake for 30 seconds, and then age in a 4 °C refrigerator for 4 hours. Next, add 1 mL of 0.5 mol / L TBA dispersant and 2 mL of 0.25 mol / L Na2CO3 buffer solution to the centrifuge tube respectively, 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 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 operation 3 times, and collect 12 mL of the extract. Then, add 1 mL of methanol to the combined extract, concentrate to 0.5 by nitrogen blowing (set the temperature at 45 °C), add 12 mL of ultrapure water for dilution, purify with a solid phase extraction column, and then use for measurement.

[0039] h. Urine After adding the standard substance of the internal standard or the internal standard working solution to 1 mL of urine, add 13 mL of ultrapure water for dilution. After purification with a solid-phase extraction column, it is used for measurement.

[0040] For the type of solid-phase extraction column used for sample purification, according to the type of PFASs target, a WAX solid-phase extraction column or an HLB solid-phase extraction column can be selected. In Table 2, samples for which LC-MS / MS analysis is to be continued can be purified using a WAX solid-phase extraction column, for example, a SHIMSEN Styra WAX 60 mg / 3 mL solid-phase extraction column. In Table 4, samples for which GC-MS / MS analysis is to be continued can be purified using an HLB solid-phase extraction column. Also, the operation method of the WAX solid-phase extraction column for blood samples may be distinguished from that of normal samples.

[0041] <Operation method of normal samples on WAX / HLB solid-phase extraction columns> For the WAX solid-phase extraction column, activate it with 4 mL of 0.1% ammonia methanol solution, 4 mL of methanol, and 4 mL of water. After setting the sample, remove impurities using 4 mL of ammonium acetate solution with pH = 4, remove the moisture in the solid-phase extraction column with a pump, and elute with 4 mL of methanol and 4 mL of 0.1% ammonia methanol solution. Concentrate the eluate to 1 mL, transfer it to a sample bottle, and use it for measurement.

[0042] The HLB solid-phase extraction column is activated with 7 mL of methanol and 7 mL of water. After setting the diluted extract, wash it with 5 mL of 20% methanol / aqueous solution to remove impurities, remove the moisture in the solid-phase extraction column with a pump, and finally elute the target compound with 10 mL of methanol. Concentrate the eluate to 1 mL, transfer it to a sample bottle, and use it for measurement.

[0043] <Detailed chromatographic operation procedure of blood samples on WAX solid-phase extraction columns> Rinse: Pass 4 mL of 0.1% ammonia methanol, 4 mL of chromatographic-grade pure methanol, and 4 mL of ultrapure water through the column in sequence.

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

[0045] Removal of impurities: After the above set of samples is completed, add NH4Ac (25 mmol / L).

[0046] Removal of moisture: Operate the vacuum pump for 30 minutes to suck and remove the moisture in the column. Turn off the pump at regular intervals.

[0047] Receiving: Place it in a new 15 mL centrifuge tube and elute successively with 4 mL of methanol and 0.1% ammonia methanol solution.

[0048] The received liquid is almost completely dried by nitrogen blowing at 50 °C, and then redissolved with 0.2 mL of pure methanol. After standing for 10 minutes, transfer it to a 2 mL micro centrifuge tube and place it in a refrigerator at -20 °C for overnight freezing. On the second day, after taking it out, perform high-speed centrifugation at low temperature for 10 minutes (speed: 12000 rpm, temperature: 4 °C). Then, take 100 uL and put it into a sample vial to proceed with the measurement.

[0049] Note that the above sample pretreatment method is exemplary. In other embodiments of the present invention, for other samples, different pretreatment methods may be adopted even for analysis.

[0050] 5. <Analysis step> 5.1 Instrument conditions 5.1.1 Reference conditions for liquid chromatography / tandem mass spectrometry (LC-MS / MS)

Example

[0051] <Example> Column temperature: 40 °C Injection volume: 5 μL Flow rate: 0.4 mL / min Mobile phase A: Contains 20 mM ammonium acetate and 0.1% (v / v) aqueous NH4OH solution, pH ≒ 9, and this pH does not exceed the pH operating range of 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 Nebulizing gas flow rate: 3.0 L / min Drying gas flow rate: 10.0 L / min Heating gas flow rate: 10.0 L / min Desolvation line temperature: 100 °C Heating module temperature: 200 °C Interface temperature: 300 °C Also, for the ESI ion source, in the prior art, the desolvation line temperature usually selected for PFASs analysis is about 250 °C, the heating module temperature is about 300 °C, and the interface temperature is about 350 °C. In this example, by lowering the desolvation line temperature, heating module temperature, and interface temperature, in-source dissociation can be effectively reduced and the detection sensitivity can be improved.

[0055] Scan mode: MRM multiple reaction ion monitoring. Parent-daughter ion pairs for quantification or qualitative analysis were preset and stored in the tandem mass spectrometry system in advance. Refer to Table 2 and Table 3 for specific detection parameters.

[0056] In this embodiment, tandem mass spectrometry mainly performs negative ion scanning, but some channels can be switched to positive ion scanning during a predetermined time period. Specifically, in one measurement, tandem mass spectrometry switches between the positive ion scanning mode and the negative ion scanning mode depending on the types of perfluoroalkyl compounds and polyfluoroalkyl compounds to be measured. In this embodiment, for the 5:3 FTB and 5:1:2 FTB fluorotelomer betaine samples, the positive ion scanning mode is executed or switched, and the negative ion scanning mode is adopted in other time periods or other channels.

[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 was measured according to the internal standard method. In this embodiment, as shown in FIG. 3, 93 types of PFASs target substances were divided into 25 groups using 25 types of isotope internal standards. Accordingly, 93 types of PFASs were divided into 25 groups, and for each group, one type of isotope internal standard was used.

[0065] Taking the group with MPFBA as the isotope internal standard as an example, this group includes 9 types of PFASs, namely PFBA, PFHxPA, PF4OPeA, Cl - PFHxPA, 3:3 FTCA, 5:3 FTCA, PH50HxA, FHxSA, and MPFBA. For each of PFBA, PFHxPA, PF4OPeA, Cl - PFHxPA, 3:3 FTCA, 5:3 FTCA, PH5OHxA, and FHxSA, the concentration ratio with MPFBA is determined based on the calibration curve according to the ratio of the peak area / peak height to MPFBA, and then the mass concentration of each is obtained according to formula (1).

[0066]

Equation

[0067] The calibration curve is generated with the concentration ratio of the target substance to the corresponding internal standard on the abscissa and the ratio value of the peak area / peak height of the target substance to the peak area / peak height of the internal standard on the ordinate, based on the measurement (with internal standard addition) of the standard solutions of the target substances with different prepared concentrations.

[0068] Note that the correspondence and grouping method between different PFASs and isotope internal standards in Table 3 are exemplary and not particularly limited. Those skilled in the art can adjust the corresponding grouping method for each target substance according to the actual situation.

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

[0070] Sampling volume: 1 μL Carrier gas control method: Constant linear velocity Linear velocity: 43.5 cm / sec Injection method: Splitless injection Mass spectrometry reference conditions: Ion source temperature: 200 °C Interface temperature: 300 °C Detector voltage: +0.1 kV (relative voltage value) Scanning mode: Multiple reaction monitoring (MRM). Refer to Table 4 and Table 5 for specific detection parameters.

[0071]

Table 4

[0072]

Table 5

[0073] 6. <Inspection results> 6.1 LC-MS / MS inspection results Based on the LC-MS / MS conditions in <Examples>, analyze the PFASs mixture. Specifically, during the process of eluting the sample with an alkaline mobile phase (containing 20 mM ammonium acetate, 0.1% (v / v) aqueous solution of NH4OH, pH ≈ 9) once (i.e., one injection), 93 types of PFASs in the sample can be sequentially eluted at different retention times. Also, record the signal intensities of different ion pairs for quantification / qualification in multiple channels of tandem mass spectrometry, and clearly distinguish these eluted PFASs in the MRM scanning pattern of tandem mass spectrometry to obtain a chromatogram as shown in Figure 2. In Figure 2, the horizontal axis is the retention time, and the vertical axis is the signal intensity of the scanning of the signal intensity of a specific ion pair by tandem mass spectrometry.

[0074] Referring to FIG. 2, with an alkaline mobile phase, for 93 types of PFASs which are the measurement targets, peaks appear sequentially at different retention times. Therefore, the working parameters of tandem mass spectrometry are rationally designed. For example, by designing a time series combination of target ion pairs for multiple channels, even without a large number of channels, all these many types of PFASs can be measured in one elution. Furthermore, even more types of perfluoro and polyfluoro compounds can be ionized better, the detector of tandem mass spectrometry has better response characteristics, and higher detection sensitivity can be obtained. Also, these 93 types of PFASs include different types of PFASs. Specifically, they are perfluoroalkyl carboxylic acids, perfluoroalkyl sulfonic acids, perfluoroalkyl sulfonamides, perfluoroalkyl ether sulfonates, perfluoroalkyl ether carboxylic acids, perfluoroalkyl sulfonamido acetic acids, perfluoroalkyl phosphonic acids, perfluoroalkyl phosphinic acids, polyfluoroalkyl phosphates, fluorotelomers (for example, fluorotelomer alcohols, fluorotelomer sulfonic acids, fluorotelomer carboxylic acids, fluorotelomer betaines), and any other suitable types of PFASs.

[0075] FIGS. 3 to 6 respectively show calibration curves prepared using a standard solution with PFOA, PFOS, ADONA, and PFODA as the targets by the LC-MS / MS system of the embodiment of the present invention. In FIGS. 3 to 6, the horizontal axis is the concentration ratio of the internal standard solution corresponding to the target, and the vertical axis is the area ratio of the corresponding peak.

[0076] Referring to FIGS. 3 to 6, it can be seen that the method provided by this embodiment has good linearity for any of various types of perfluoroalkyl compounds and polyfluoroalkyl compounds.

[0077] 6.2 GC-MS / MS Test Results Figure 7 is a chromatogram of 10 types of fluorotelomer alcohol compounds obtained in this example, and this chromatogram is also obtained by a single injection analysis. The horizontal axis is the retention time, and the vertical axis is the signal intensity of the scan of the signal intensity of a specific ion pair by tandem mass spectrometry. As shown in Figure 7, for the 10 types of fluorotelomer alcohol compounds, peaks appear sequentially at different retention times. Also, by recording the signal intensities of different parent-daughter ion pairs for quantification / qualification in multiple channels of tandem mass spectrometry, it can be clearly distinguished by the MRM scan pattern of tandem mass spectrometry.

[0078] In this example, a rapid analysis of 93 types of PFASs was completed with a single injection. However, the examples of the present invention are not limited to a single injection analysis of a specified number of PFASs, and the number can be increased or decreased as long as the gist of the present invention is not exceeded. For example, some types of PFASs can be selected from them for analysis, or other types of PFASs can be added or replaced.

[0079] The above is not intended to limit the present invention, but is only a preferred embodiment of the present invention, and all modifications, equivalent substitutions, and improvements implemented in accordance with the gist of the present invention shall be included in the protection scope of the present invention.

Explanation of Signs

[0080] 1 Liquid pump 2 Delay column 3 Autosampler 4 Analytical column 5 Column oven 6 Triple quadrupole mass spectrometer

Claims

1. A method for measuring a perfluoroalkyl compound and the concentration of a polyfluoroalkyl compound, which measures the concentration of a perfluoroalkyl compound and a polyfluoroalkyl compound containing a plurality of at least one or more perfluoroalkylphosphonic acid / phosphinic acid-based compounds or polyfluoroalkyl phosphate-based compounds in the sample in a single measurement by eluting the sample with an alkaline mobile phase by liquid chromatography / tandem mass spectrometry.

2. The method for measuring a perfluoroalkyl compound and a polyfluoroalkyl compound according to claim 1, wherein the alkaline mobile phase is an alkaline mobile phase having a pH of 8 to 10.

3. The method for measuring the concentration of a perfluoroalkyl compound and a polyfluoroalkyl compound according to claim 2, wherein the alkaline mobile phase is an alkaline mobile phase having a pH of approximately 9.

4. The perfluoroalkyl compound and the polyfluoroalkyl compound are a plurality of combinations selected from perfluoroalkyl carboxylic acid, perfluoroalkyl sulfonic acid, perfluoroalkyl sulfonamide, perfluoroalkyl ether sulfonate, perfluoroalkyl ether carboxylic acid, perfluoroalkyl sulfonamide acetic acid, perfluoroalkyl phosphonic acid, perfluoroalkyl phosphinic acid, polyfluoroalkyl phosphate, fluorotelomer alcohol, fluorotelomer sulfonic acid, fluorotelomer carboxylic acid, and fluorotelomere betaine. The method for measuring a perfluoroalkyl compound and a polyfluoroalkyl compound according to claim 1.

5. The method for measuring a perfluoroalkyl compound and a polyfluoroalkyl compound according to claim 1, wherein the positive ion scanning mode and the negative ion scanning mode are switched according to the types of the perfluoroalkyl compound and the polyfluoroalkyl compound to be measured by tandem mass spectrometry in a single measurement.

6. A liquid chromatography / tandem mass spectrometry system, wherein the liquid chromatography / tandem mass spectrometry system has a measurement mode for the concentrations of perfluoroalkyl compounds and polyfluoroalkyl compounds, and when the liquid chromatography / tandem mass spectrometry system is operated in the measurement mode for the concentrations of perfluoroalkyl compounds and polyfluoroalkyl compounds, 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 including at least one or more perfluoroalkylphosphonic acid / phosphinic acid compounds or polyfluoroalkyl phosphate ester compounds in the sample are measured.

7. The liquid chromatography / tandem mass spectrometry system according to claim 6, characterized in that the liquid chromatography / tandem mass spectrometry system has a pipeline for measuring the concentrations of perfluoroalkyl compounds and polyfluoroalkyl compounds, and the pipe material used in the pipeline for measuring perfluoroalkyl compounds and polyfluoroalkyl compounds does not contain fluorine.

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

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

10. The liquid chromatography / 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, and 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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