Method for detecting fluorine content in food

Abstract

The application provides a detection method for fluorine content in food, and belongs to the technical field of analysis and detection. The detection method for fluorine content in food comprises the following steps: microwave digestion of a sample containing fluorine to prepare a sample solution; online mixing of the sample solution with a Sr standard working solution by using a tandem quadrupole inductively coupled plasma mass spectrometer, separation of a first intermediate product containing 88 Sr 19 F + after ionization by a first quadrupole analyzer; reaction of the first intermediate product in a reaction cell containing ammonia to remove interfering ions, and then separation of a second intermediate product containing 88 Sr 19 F + by a second quadrupole analyzer; detection of 88 Sr 19 F + as target ions, and calculation of the fluorine content in the sample by an external standard method. The detection method established in the application has high accuracy, excellent detection sensitivity and good repeatability, and can realize accurate quantitative analysis of the fluorine content in the sample.

Description

Technical Field

[0001] This application relates to the field of analytical testing technology, and in particular to a method for detecting the fluorine content in food. Background Technology

[0002] Fluorine is an essential trace element for the human body. Adequate intake helps prevent tooth decay and maintain bone health; however, its safe threshold is narrow, and excessive intake can lead to dental fluorosis, skeletal fluorosis, and even damage to the nervous system. Therefore, accurately determining the fluorine content in food is crucial for nutritional assessment and risk management.

[0003] Tea, seafood, processed meat products, and certain groundwater-irrigated crops (such as rice) naturally accumulate fluoride, often to levels close to or exceeding regulatory thresholds. Furthermore, the widespread use of fluoride-containing pesticides (such as fipronil and flonicamid) and fluoride-containing veterinary drugs (such as florfenicol and fluoroquinolones) in agriculture and animal husbandry may leave residues or additives in food, posing potential safety risks.

[0004] Ion chromatography (IC) and fluoride ion-selective electrode (ISE) methods are commonly used for the determination of fluorine. However, the conventional IC method is susceptible to high concentrations of Cl. - SO4 2- Interference from coexisting ions makes it suitable for determining inorganic fluoride ions, but it cannot directly reflect the levels of organic fluoride ions or total fluoride. Conventional ISE methods are simple to operate, but their resistance to interference is insufficient and they are easily affected by OH groups. - Al 3+ Fe 3+ Interferences such as these can cause unstable responses and poor reproducibility in turbid or high-salt food extracts. Furthermore, the IC and ISE methods are incompatible with modern high-throughput elemental analysis platforms, making simultaneous multi-element screening difficult.

[0005] Inductively coupled plasma mass spectrometry (ICP-MS) is widely used in elemental content detection due to its advantages of high sensitivity, wide linear range, and multi-element compatibility. However, because the first ionization energy of fluorine is extremely high (approximately 17.4 eV), far exceeding the energy provided by the argon plasma temperature in the inductively coupled rectangular tube (approximately 15.8 eV), the ionization energy of fluorine (…) is significantly higher. 19 F + Barium fluoride (BF₂) cannot be effectively ionized in conventional inductively coupled plasma mass spectrometry (ICP-MS). Therefore, in the traditional ICP-MS / MS method for determining fluorine content, the detection of barium fluoride adduct ions (BaF₂) is often performed. + The signal indirectly reflects the fluorine content, while ammonia is used via mass transfer modes (such as BaF). + →BaF(NH3) 3+ To eliminate 18 O1 H + , 17 O 2 H + as well as 16 O 3 H + Equivalent Isotope Ion Pairs 19 F + Mass spectrometry interference. However, this method has serious drawbacks when applied to food matrices rich in sulfur amino acids, such as meat, seafood, dairy products, and processed foods (e.g., braised products, cheese): barium ions readily react with sulfate, carbonate, and phosphate anions released after food matrix digestion to form insoluble precipitates (e.g., BaSO4, Ksp=1.1×10⁻⁶). -10 ), leading to free Ba 2+ The concentration dropped sharply, BaF + The signal is significantly suppressed or even completely disappeared, which seriously affects the reliability of the detection method.

[0006] Therefore, improving the detection methods for fluoride content in food to enhance their accuracy has become an urgent technical problem to be solved. Summary of the Invention

[0007] Therefore, the main purpose of this application is to provide a method for detecting the fluoride content in food, so as to improve the accuracy of the detection of fluoride content in food.

[0008] This application provides a method for detecting the fluoride content in food, comprising the following steps:

[0009] Samples containing fluorine are digested by microwave to prepare sample solutions;

[0010] A tandem quadrupole inductively coupled plasma mass spectrometer was used to mix the sample solution with the Sr standard working solution online. After ionization, the solution was separated by the first quadrupole analyzer. 88 Sr 19 F + The first intermediate product; the first intermediate product is passed into a reaction cell containing ammonia to remove interfering ions, and then separated by a second quadrupole analyzer. 88 Sr 19 F + The second intermediate product, with 88 Sr 19 F + The target ion was detected, and the fluorine content in the sample was calculated using the external standard method.

[0011] In some implementations, the step of calculating the fluorine content in a sample using the external standard method specifically includes:

[0012] Determination of the formation of a series of F standard working solutions 88 Sr 19 F + To determine the signal intensity, a standard curve of F concentration-signal intensity was established, and the sample solution was analyzed. 88 Sr 19 F + The signal intensity was substituted into the standard curve to calculate the fluorine content in the sample.

[0013] In some embodiments, the fluorine-containing sample also includes sulfur.

[0014] In some embodiments, the sample solution includes fluoride ions and sulfate ions.

[0015] In some embodiments, the conditions for the tandem quadrupole inductively coupled plasma mass spectrometer include:

[0016] In MS / MS mode, using the same mass mode, the mass-to-charge ratio of both the first and second quadrupole analyzers is set to 107.

[0017] In some embodiments, the interfering ions include 88 Sr 18 O 1 H + , 88 Sr 1 H3 16 O + , 88 Sr 17 O 1 H2 + and 107 Ag + At least one of them.

[0018] In some implementations, the conditions for the ICP-MS / MS further include:

[0019] It adopts a quartz inner diameter central tube and a semiconductor cooling atomization chamber;

[0020] The temperature of the semiconductor cooling atomization chamber is -2 to 25 °C;

[0021] RF power is 1000~1600 W;

[0022] The atomizer flow rate is 0.8~1.2 L / min;

[0023] The plasma flow rate is 12~16 L / min;

[0024] The auxiliary gas flow rate is 0.8~1.2 L / min;

[0025] The reaction gas flow rate is 0.8~1.2 mL / min;

[0026] The acquisition parameters are: residence time per atomic mass unit is 100~600 ms, and integration time is 3000~6000 ms;

[0027] The resistance parameter q of the dynamic reaction cell is 0.2~0.4.

[0028] In some embodiments, the inner diameter of the quartz inner diameter center tube is 0.6~2.0 mm; the semiconductor cooling atomization chamber includes PC3X.

[0029] In some embodiments, the Sr standard working solution is prepared by the following method:

[0030] A Sr standard working solution is prepared by mixing a Sr standard solution with a chloride ion-containing solution.

[0031] In some embodiments, the chloride-containing solution includes at least one of hydrochloric acid solution, perchloric acid solution, ammonium chloride solution, and a mixed solution of ammonium chloride and nitric acid.

[0032] In some embodiments, the step of microwave digestion of the fluorine-containing sample specifically includes:

[0033] The sample containing fluorine was mixed with an aqueous solution of nitric acid and then placed in a microwave digester for microwave digestion.

[0034] In some implementations, the conditions for microwave digestion include:

[0035] At a power of 800~1000 W, the temperature is raised from 20~30 ℃ to 120~150 ℃ within 5~10 min, and held for 5~10 min; then at a power of 1400~1600 W, the temperature is raised to 180~200 ℃ within 5~10 min, and held for 15~25 min.

[0036] In some embodiments, after microwave digestion of the fluorine-containing sample, the method further includes the step of diluting the microwave digestion product with water to form the sample solution.

[0037] Compared with traditional technologies, this application has at least the following beneficial effects:

[0038] This application first processes samples containing fluorine using microwave digestion to prepare a sample solution. Then, using a tandem quadrupole inductively coupled plasma mass spectrometer, the sample solution is mixed online with an Sr standard working solution. After ionization, the solution is separated by a first quadrupole analyzer. 88 Sr 19 F +The first intermediate product; the first intermediate product is passed into a reaction cell containing ammonia to remove interfering ions, and then separated by a second quadrupole analyzer. 88 Sr 19 F + The second intermediate product, with 88 Sr 19 F + By detecting the target ion and calculating the fluorine content in the sample using the external standard method, accurate quantitative analysis of the fluorine content in the sample can be achieved. At the same time, the detection method has excellent sensitivity and repeatability, and high reliability. Attached Figure Description

[0039] To better describe and illustrate the embodiments or examples provided in this application, reference may be made to one or more accompanying drawings. Additional details or examples used to describe the drawings should not be considered as limiting the scope of any of the disclosed applications, the currently described embodiments or examples, or the best mode of conduct of these applications as currently understood. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0040] Figure 1 This is a schematic diagram of the ICP-MS / MS instrument configuration and analysis method of this application;

[0041] Figure 2 A schematic diagram showing the recovery rate of fluorine addition;

[0042] Figure 3 The detection spectra for Example 2 are shown below, where a)-e) are detection spectra of the test solutions using water, 4% nitric acid, 4% hydrochloric acid, 4% perchloric acid and 4% ammonium chloride as solvents, respectively.

[0043] Figure 4 The detection spectrum for Example 3 is shown below, where a) is the detection spectrum of the test solution being a 0.0 F standard working solution (i.e., a Sr (4% hydrochloric acid) system). Figure 4 b) is the detection spectrum of the test solution being 50 mg / L F standard working solution (i.e., SrF (4% hydrochloric acid) system);

[0044] Figure 5 For different concentrations of sulfate ion pairs 88 Sr 19 F + and 138 Ba 19 F(NH3)3 + A schematic diagram illustrating the impact of signal strength. Detailed Implementation

[0045] The present application will be further described in detail below with reference to the embodiments and examples. These embodiments and examples are for illustrative purposes only and are not intended to limit the scope of the present application. The purpose of providing these embodiments and examples is to enable a more thorough and comprehensive understanding of the disclosure of the present application. It should also be understood that the present application can be implemented in many different forms and is not limited to the embodiments and examples described herein. Those skilled in the art can make various modifications or alterations without departing from the spirit of the present application, and the equivalent forms obtained also fall within the protection scope of the present application. Furthermore, numerous specific details are set forth in the following description to provide a fuller understanding of the present application. It should be understood that the present application can be implemented without one or more of these details.

[0046] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0047] To address the issue of insufficient accuracy in traditional methods for detecting fluorine content in food, this application first utilizes microwave digestion to process fluorine-containing samples, preparing a sample solution. Then, a tandem quadrupole inductively coupled plasma mass spectrometer (QCPMS) is employed to online mix the sample solution with an Sr standard working solution. After ionization, the solution is separated by a first quadrupole analyzer. 88 Sr 19 F + The first intermediate product; the first intermediate product is passed into a reaction cell containing ammonia to remove interfering ions, and then separated by a second quadrupole analyzer. 88 Sr 19 F + The second intermediate product, with 88 Sr 19 F + By detecting the target ion and calculating the fluorine content in the sample using the external standard method, accurate quantitative analysis of the fluorine content in the sample can be achieved. At the same time, the detection method has excellent sensitivity and repeatability, and high reliability.

[0048] This application provides a method for detecting the fluoride content in food, comprising the following steps:

[0049] Samples containing fluorine are digested by microwave to prepare sample solutions;

[0050] A tandem quadrupole inductively coupled plasma mass spectrometer was used to mix the sample solution with the Sr standard working solution online. After ionization, the solution was separated by the first quadrupole analyzer.88 Sr 19 F + The first intermediate product; the first intermediate product is passed into a reaction cell containing ammonia to remove interfering ions, and then separated by a second quadrupole analyzer. 88 Sr 19 F + The second intermediate product, with 88 Sr 19 F + The target ion was detected, and the fluorine content in the sample was calculated using the external standard method.

[0051] The method for detecting fluoride content in food described in this application can accurately calculate the fluoride content in a sample, and the method has excellent detection sensitivity and good repeatability, enabling precise and reliable quantitative analysis of the fluoride content in a sample.

[0052] The fluorine-containing samples described in this application are food samples containing fluorine.

[0053] In some embodiments, the concentration of the Sr standard working solution is 50~400 mg / L, and can be 50 mg / L, 100 mg / L, 150 mg / L, 200 mg / L, 250 mg / L, 300 mg / L, 350 mg / L, or 400 mg / L.

[0054] In some embodiments, the volumetric flow rate ratio of the sample solution to the Sr standard working solution mixed online is (1:1) to (1:4), which can be 1:1, 1:2, 1:3 or 1:4.

[0055] In some implementations, the step of calculating the fluorine content in a sample using the external standard method specifically includes:

[0056] Determination of the formation of a series of F standard working solutions 88 Sr 19 F + To determine the signal intensity, a standard curve of F concentration-signal intensity was established, and the sample solution was analyzed. 88 Sr 19 F + The signal intensity was substituted into the standard curve to calculate the fluorine content in the sample.

[0057] In some embodiments, the series of F standard working solutions includes F standard working solutions with concentrations of 0.0, 5.0 mg / L, 10 mg / L, 15 mg / L, and 20 mg / L.

[0058] In some embodiments, the fluorine-containing sample also includes sulfur.

[0059] In some embodiments, the sulfur in the fluorine-containing sample is provided by sulfates and / or sulfur-containing amino acids.

[0060] In some embodiments, the fluorine-containing sample includes pork, beef, fish, dried shrimp, or cheese. The pork, beef, fish, dried shrimp, or cheese are rich in sulfur-containing amino acids, which, upon microwave digestion, release a large amount of sulfate ions.

[0061] In some embodiments, the sample solution includes fluoride ions and sulfate ions.

[0062] In some embodiments, the conditions for the tandem quadrupole inductively coupled plasma mass spectrometer include:

[0063] In MS / MS mode, using the same mass mode, the mass-to-charge ratio of both the first and second quadrupole analyzers is set to 107.

[0064] In some embodiments, the interfering ions include 88 Sr 18 O 1 H + , 88 Sr 1 H3 16 O + , 88 Sr 17 O 1 H2 + and 107 Ag + At least one of them.

[0065] In some embodiments, the conditions for the tandem quadrupole inductively coupled plasma mass spectrometer further include:

[0066] It adopts a quartz inner diameter central tube and a semiconductor cooling atomization chamber;

[0067] The temperature of the semiconductor cooling atomization chamber is -2 to 25 ℃, and can be -2 ℃, 0 ℃, 2 ℃, 5 ℃, 10 ℃, 15 ℃, 20 ℃ or 25 ℃;

[0068] The radio frequency power is 1000~1600 W, and can be 1000W, 1100W, 1200W, 1300W, 1400W, 1500W or 1600W;

[0069] The atomizer flow rate is 0.8~1.2 L / min, and can be 0.8 L / min, 0.9 L / min, 1.0 L / min, 1.1 L / min or 1.2 L / min;

[0070] The plasma flow rate is 12~16 L / min, which can be 12 L / min, 13 L / min, 14 L / min, 15 L / min or 16 L / min;

[0071] The auxiliary gas flow rate is 0.8~1.2 L / min, and can be 0.8 L / min, 0.9 L / min, 1.0 L / min, 1.1 L / min or 1.2 L / min;

[0072] The reaction gas flow rate is 0.8~1.2 mL / min, and can be 0.8 mL / min, 0.85 mL / min, 0.9 mL / min, 0.95 mL / min or 1.0 mL / min;

[0073] The acquisition parameters are as follows: the residence time per atomic mass unit is 100~600 ms, which can be 100 ms, 200 ms, 300 ms, 400 ms, 500 ms or 600 ms; the integration time is 3000~6000 ms, which can be 3000 ms, 4000 ms, 5000 ms or 6000 ms.

[0074] The resistance parameter q of the dynamic reaction cell is 0.2~0.4, and can be 0.2, 0.25, 0.3, 0.35 or 0.4.

[0075] In some embodiments, the auxiliary gas in the tandem quadrupole inductively coupled plasma mass spectrometer is argon.

[0076] In some embodiments, the inner diameter of the quartz inner diameter center tube is 0.6~2.0 mm, and can be 0.6 mm, 0.8 mm, 1.0 mm, 1.2 mm, 1.5 mm or 2.0 mm; the semiconductor cooling atomization chamber includes PC3X.

[0077] In some embodiments, the step of mixing the sample solution with the Sr standard working solution online specifically includes:

[0078] The sample solution is introduced through the first pipeline, and the Sr standard working solution is introduced through the second pipeline. The solution is then carried by a carrier gas into the semiconductor cooling atomization chamber for online mixing and atomization. The carrier gas can be argon.

[0079] In some implementations, the ionization step is performed in an ICP plasma torch.

[0080] In some embodiments, the ammonia-containing reaction tank is a dynamic reaction tank using ammonia as the reactant gas.

[0081] In some embodiments, the Sr standard working solution is prepared by the following method:

[0082] A Sr standard working solution is prepared by mixing a Sr standard solution with a chloride ion-containing solution.

[0083] In some embodiments, the chloride-containing solution includes at least one of hydrochloric acid solution, perchloric acid solution, ammonium chloride solution, and a mixed solution of ammonium chloride and nitric acid.

[0084] In some embodiments, the step of microwave digestion of the fluorine-containing sample specifically includes:

[0085] The sample containing fluorine was mixed with an aqueous solution of nitric acid and then placed in a microwave digester for microwave digestion.

[0086] In some embodiments, in the step of microwave digestion of the sample containing fluorine, the volume ratio of nitric acid to water in the nitric acid aqueous solution is (1:1) to (1:3), which can be 1:1, 1:1.25, 1:1.5, 1:1.75, 1:2, 1:2.5 or 1:3.

[0087] In some embodiments, the fluorine-containing sample is a solid sample, and in the step of microwave digestion of the fluorine-containing sample, the mass-to-volume ratio of the fluorine-containing sample to the nitric acid aqueous solution is (0.025~0.125) g:1 mL, which can be 0.025 g:1 mL, 0.03 g:1 mL, 0.04 g:1 mL, 0.05 g:1 mL, 0.06 g:1 mL, 0.08 g:1 mL, 0.1 g:1 mL, or 0.125 g:1 mL.

[0088] In some embodiments, the fluorine-containing sample is a liquid sample, and in the step of microwave digestion of the fluorine-containing sample, the volume ratio of the fluorine-containing sample to the nitric acid aqueous solution is (0.0625~0.1875):1, which can be 0.0625:1, 0.08:1, 0.1:1, 0.12:1, 0.15:1 or 0.1875:1.

[0089] In some implementations, the conditions for microwave digestion include:

[0090] At a power of 800~1000W, the temperature is raised from 20~30℃ to 120~150℃ within 5~10 minutes, and held for 5~10 minutes; then at a power of 1400~1600W, the temperature is raised to 180~200℃ within 5~10 minutes, and held for 15~25 minutes.

[0091] In some implementations, the conditions for microwave digestion include:

[0092] At 800W power, the temperature was raised from 25℃ to 150℃ in 10 minutes and held for 10 minutes; then at 1600W power, the temperature was raised to 200℃ in 10 minutes and held for 20 minutes.

[0093] In some embodiments, after microwave digestion of the fluorine-containing sample, the method further includes the step of diluting the microwave digestion product with water to form the sample solution.

[0094] In some embodiments, the step of preparing a sample solution by microwave digestion of a fluorine-containing sample specifically includes:

[0095] Take 0.2~1.0 g of solid sample containing fluorine (0.2 g, 0.3 g, 0.4 g, 0.5 g, 0.6 g, 0.7 g, 0.8 g, 0.9 g, or 1.0 g of solid sample containing fluorine) and place it in a polytetrafluoroethylene digestion tube. Add 8 mL of nitric acid aqueous solution (nitric acid to water volume ratio of 1:1.25) and perform microwave digestion in a microwave digester. The microwave digestion conditions are as follows: at 800 W power, raise the temperature from room temperature (25℃) to 150℃ within 10 min and hold for 10 min; then at 1600 W power, raise the temperature to 200℃ within 10 min and hold for 20 min. After microwave digestion, cool and dilute the product with pure water to 50 mL to prepare the sample solution.

[0096] In some embodiments, the step of preparing a sample solution by microwave digestion of a fluorine-containing sample specifically includes:

[0097] Take 0.5–1.5 mL of liquid sample containing fluorine (or 0.5 mL, 0.6 mL, 0.7 mL, 0.8 mL, 0.9 mL, 1.0 mL, 1.1 mL, 1.2 mL, 1.3 mL, 1.4 mL, or 1.5 g of solid sample containing fluorine) and place it in a polytetrafluoroethylene (PTFE) digestion tube. Add 8 mL of nitric acid aqueous solution (nitric acid to water volume ratio of 1:1.25) and perform microwave digestion in a microwave digester. The microwave digestion conditions are as follows: at 800 W power, raise the temperature from room temperature (25 °C) to 150 °C within 10 min and hold for 10 min; then at 1600 W power, raise the temperature to 200 °C within 10 min and hold for 20 min. After microwave digestion, cool and dilute the product with pure water to 50 mL to prepare the sample solution.

[0098] In some embodiments, the method for detecting the fluoride content in the food includes the following steps:

[0099] Samples containing fluorine are digested by microwave to prepare sample solutions;

[0100] A tandem quadrupole inductively coupled plasma mass spectrometer was used, employing a T-tube injection system to mix the sample solution with the Sr standard working solution online, followed by ionization via an ICP plasma torch to prepare... 88 Sr 19 F + The mass-to-charge ratio (m / z) of the first quadrupole analyzer (Q1) is set to 107. Q1 is used to separate components containing... 88 Sr 19 F + The first intermediate product, with m / z = 107, is passed through Q1 and enters the dynamic reaction tank for reaction. NH3 reaction gas is introduced into the dynamic reaction tank, causing interfering ions in the first intermediate product to combine with NH3, thus removing the interfering ions. The second quadrupole analyzer (Q3) is set to a mass-to-charge ratio (m / z) of 107, and the components containing [unspecified ions] are separated by Q3. 88 Sr 19 F + The second intermediate product, making m / z=107 88 Sr 19 F + Ions pass through Q3 and enter the detector; 88 Sr 19 F + To detect the target ion, the target ion in the sample solution is obtained. 88 Sr 19 F + The signal strength;

[0101] The external standard method was used to determine the formation of a series of F standard working solutions. 88 Sr 19 F + To determine the signal intensity, a standard curve of F concentration-signal intensity was established, and the sample solution was analyzed. 88 Sr 19 F + The signal intensity was substituted into the standard curve to calculate the fluorine content in the sample.

[0102] The embodiments of this application will be described in detail below with reference to examples. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of this application. For experimental methods in the following embodiments where specific conditions are not specified, please refer to the guidelines given in this application, or follow experimental manuals or conventional conditions in the art, or follow the conditions recommended by the manufacturer, or refer to experimental methods known in the art.

[0103] Example 1

[0104] The specific methods for detecting the fluoride content in food are as follows:

[0105] (1) Preparation of sample solution and blank solution:

[0106] The following quality control samples, each with a certificate, were used: corn (purchased from Henan Putian Tongchuang Metrology Co., Ltd., product number GBW08507, batch number 244620), poplar leaves (purchased from Henan Detong Environmental Protection Technology Co., Ltd., product number GBW07604, batch number 230510), kelp (purchased from Northern Weiye Metrology Group Co., Ltd., product number GBW08517, batch number 252220), spinach (purchased from Northern Weiye Metrology Group Co., Ltd., product number GBW10015, batch number 251210), and tea (purchased from Northern Weiye Metrology Group Co., Ltd., product number...). The following products were identified as containing fluorine: GBW10016, batch number 250100-1; citrus leaves (purchased from Northern Weiye Metrology Group Co., Ltd., product number GBW10020, batch number 251120); garlic powder (purchased from Northern Weiye Metrology Group Co., Ltd., product number GBW10022, batch number 251012); scallops (purchased from Northern Weiye Metrology Group Co., Ltd., product number GBW10024, batch number 250200); and spirulina (purchased from Northern Weiye Metrology Group Co., Ltd., product number GBW10025, batch number 250204).

[0107] Accurately weigh 0.5 g of samples containing different amounts of fluorine and place them in polytetrafluoroethylene (PTFE) digestion tubes. Add 8 mL of nitric acid aqueous solution (nitric acid to water volume ratio of 1:1.25) and perform microwave digestion in a microwave digester. The microwave digestion conditions are as follows: at 800 W power, raise the temperature from room temperature (25 ℃) to 150 ℃ within 10 min and hold for 10 min; then at 1600 W power, raise the temperature to 200 ℃ within 10 min and hold for 20 min. After microwave digestion, cool the samples and dilute them with pure water to 50 mL to prepare different sample solutions.

[0108] Prepare a blank solution without adding any sample, following the sample solution preparation method.

[0109] (2) Preparation of standard solutions:

[0110] Purchase 1000 mg / L Sr standard solution (with standard certificate, purchased from the National Nonferrous Metals and Electronic Materials Analysis and Testing Center, batch number 258021-1) and 100 mg / L F standard solution (with standard certificate, purchased from the National Nonferrous Metals and Electronic Materials Analysis and Testing Center, batch number 258019) directly and store them at 4℃ for later use.

[0111] Prepare Sr standard working solutions and a series of F standard working solutions: using 4% hydrochloric acid (4% mass fraction of hydrogen chloride aqueous solution) as solvent, dilute the Sr standard solution to a concentration of 100 mg / L, and dilute the F standard solution to concentrations of 0.0, 5.0 mg / L, 10 mg / L, 15 mg / L and 20 mg / L respectively. Prepare and use immediately.

[0112] (3) Test method:

[0113] Detection was performed using an inductively coupled plasma tandem mass spectrometer (ICP-MS / MS, PerkinElmer, NexION 5000G). The instrument is equipped with a quartz inner diameter central tube of 1.5 mm and a semiconductor cooled nebulizer PC3X. The first quadrupole analyzer (Q1) and the second quadrupole analyzer (Q3) are connected by a dynamic reaction cell, which uses high-purity ammonia (99.999% purity) as the reaction gas. In MS / MS mode, the on-mass mode was set, with the following acquisition parameters: residence time per atomic mass unit of 300 ms and integration time of 6000 ms. Different sample solutions, a series of F standard working solutions, and blank solutions were used as analytes.

[0114] ICP-MS / MS instrument configuration and analysis methods, such as Figure 1 As shown, a T-tube injection system was used. The test solution entered through the first tube, and the Sr standard working solution entered through the second tube. The volumetric flow rate ratio of the test solution to the Sr standard working solution was 1:3. The solution was fed into the semiconductor-cooled atomization chamber PC3X by a carrier gas (argon) for online mixing and atomization. The temperature of the semiconductor-cooled atomization chamber was set to -2℃, and the atomizer flow rate was 1.2 L / min, forming an aerosol. The aerosol entered the ICP plasma torch, where the RF power was set to 1600 W, the plasma flow rate to 16 L / min, and the auxiliary gas (argon) flow rate to 1.2 L / min, generating… 88 Sr 19 F + (Right now 107 SrF + ), 208 Pb + , 107 Ag+ , 88 Sr 18 O 1 H + , 88 Sr 1 H3 16 O + and 88 Sr 17 O 1 H2 + Plasma. The mass-to-charge ratio (m / z) of the first quadrupole analyzer (Q1) is set to 107. Only ions with m / z = 107 (the first intermediate product) are allowed to pass through Q1 and enter the dynamic reaction cell for reaction. Ions with other mass-to-charge ratios are filtered and discarded. Among them, ions with m / z = 107 include the target ion. 88 Sr 19 F + and interfering ions 88 Sr 18 O 1 H + , 88 Sr 1 H3 16 O + , 88 Sr 17 O 1 H2 + and 107 Ag + NH3 reaction gas is introduced into the dynamic reaction tank. The gas flow rate is set to 1.0 mL / min, and the resistance parameter q (RPq) of the dynamic reaction tank is set to 0.35, so that Q1 is released at m / z = 107. 107 Ag + , 88 Sr 18 O 1 H + , 88 Sr 1 H3 16 O + , 88 Sr 17 O 1 H2 + Ions undergo addition with NH3 to generate product ions with different mass-to-charge ratios (including...) 107 Ag(NH3)4 + , 88 Sr 18 O 1 H(NH3) x + , 88 Sr 1 H3 16 O(NH3)x + , 88 Sr 17 O 1 H2(NH3) x + Ions), removing interfering ions. The mass-to-charge ratio (m / z) of the second quadrupole analyzer (Q3) is set to 107. Ions with m / z = 107 (the second intermediate product, mainly composed of...) are separated by Q3. 88 Sr 19 F + ), allowing ions with m / z=107 to pass through Q3 and enter the detector, in order to 88 Sr 19 F + To detect the target ion, the target ion in the test solution is obtained. 88 Sr 19 F + The signal strength.

[0115] (4) Establish a standard curve and perform methodological validation:

[0116] The target ions in a series of F standard working solutions obtained according to the ICP-MS / MS test method in step (3) 88 Sr 19 F + The signal strength is plotted on the x-axis with the concentration of the F standard working solution, and the signal strength plotted on the y-axis with the concentration of the F standard working solution. 88 Sr 19 F + Using the signal intensity as the ordinate, a standard curve was established to evaluate the sensitivity of the method. The background equivalent concentration (BEC), limit of detection (LOD), and limit of quantitation (LOQ) of fluorine were calculated, and the results are shown in Table 1.

[0117] Table 1. Methodological Validation Results

[0118]

[0119] It can be seen that the detection method used in this application effectively reduces the blank background signal and improves the sensitivity of the method.

[0120] (5) Detect the fluorine content in the sample:

[0121] Based on the standard curve obtained in step (4), the target ions in the sample solution obtained in step (3) are... 88 Sr 19 F + The signal intensity was substituted into the standard curve to calculate the fluorine content in the sample solution. Then, the fluorine content in the sample was calculated based on the concentration of the sample in the sample solution. The experiment was repeated 3 times, and the average value was taken as the measured value of fluorine content.

[0122] Table 2 shows the reference content (i.e., characteristic value) of fluorine, a specific target analyte, in each certified quality control sample, as well as the detection results of fluorine content. According to Table 2, the measured fluorine content is not significantly different from the characteristic value of the certified quality control sample, indicating that this detection method meets the methodological requirements.

[0123] Table 2 Sample test results

[0124]

[0125] (6) Blank matrix spiking experiment:

[0126] Commercially available edible fungi, tea, rice, pork, shrimp, fish, and cheese were used as samples. Different sample solutions were prepared according to the method in step (1), and then the target ions were detected according to the detection method in step (3). 88 Sr 19 F + The signal strength, the results show 88 Sr 19 F + The signal intensity was below the detection limit and was not detected. Therefore, the following commercially available edible fungi, tea, rice, pork, shrimp, fish, and cheese samples that do not contain fluorine were used as blank matrix samples for subsequent blank matrix spiking experiments.

[0127] Fluorine standard solution was added to the blank matrix sample to make the concentration of F in the blank matrix sample 20 mg / kg. These blank matrix samples were used as different blank matrix spiked samples. Different blank matrix spiked solutions were prepared according to the sample solution preparation method in step (1). Specifically: 0.5 g of blank matrix sample was weighed and placed in a polytetrafluoroethylene digestion tube. Fluorine standard solution was added to make the concentration of F in the sample sample 20 mg / kg. 8 mL of nitric acid aqueous solution (the volume ratio of nitric acid to water was 1:1.25) was added. Microwave digestion was performed in a microwave digester. The microwave digestion conditions were: at 800 W power, the temperature was raised from room temperature (25 ℃) to 150 ℃ within 10 min and kept at that temperature for 10 min; then at 1600 W power, the temperature was raised to 200 ℃ within 10 min and kept at that temperature for 20 min; after microwave digestion, the sample was cooled and diluted with pure water to 50 mL to prepare different blank matrix spiked solutions. These solutions were used as test solutions. The target ion in the test solution was obtained according to the method in step (3). 88 Sr 19 F + The signal intensity was then used to calculate the fluorine content in the sample solution according to step (5). The experiment was repeated three times, and the fluorine recovery rate was calculated. The results are as follows: Figure 2As shown, the recovery rate of fluorine addition ranges from 92.5% to 98.8%, which meets the methodological requirements.

[0128] Example 2

[0129] This embodiment is used to compare the effect of solvent type on the detection of fluorine in Sr standard working solution and F standard working solution.

[0130] Specifically, the method is as follows:

[0131] (1) Using water, 4% nitric acid (4% HNO3 aqueous solution), 4% hydrochloric acid (4% HCl aqueous solution), 4% perchloric acid (4% HClO4 aqueous solution), and 4% ammonium chloride (4% NH4Cl aqueous solution) as solvents, prepare a 100 mg / L Sr standard working solution and a 20 mg / L F standard working solution according to step (2) in Example 1.

[0132] (2) Test method:

[0133] The F standard working solution prepared above was used as the test solution, and the inductively coupled plasma tandem mass spectrometer described in Example 1 was used for detection. In MS / MS mode, a neutral gain scan mode was set, and the acquisition parameters were: residence time per atomic mass unit of 300 ms and integration time of 6000 ms.

[0134] Set the mass-to-charge ratio of both Q1 and Q3 to be 90 to 200, and follow... Figure 1 The analysis was conducted using a T-tube injection method. The test solution entered through the first tube, while the Sr standard working solution (using the same solvent as the test solution) entered through the second tube. The volumetric flow rate ratio of the test solution to the Sr standard working solution was 1:3. The solution was fed into the semiconductor-cooled atomization chamber PC3X by a carrier gas (argon) for online mixing and atomization. The temperature of the semiconductor-cooled atomization chamber was set to -2℃, and the atomizer flow rate was 1.2 L / min, forming an aerosol. The aerosol entered the ICP plasma torch, where the RF power was set to 1600 W, the plasma flow rate to 16 L / min, and the auxiliary gas (argon) flow rate to 1.2 L / min, generating… 88 Sr 19 F + Plasma. The mass-to-charge ratio (m / z) of the first quadrupole analyzer (Q1) is set to 90 to 200. Only ions with m / z = 90 to 200 are allowed to pass through Q1 and enter the dynamic reaction cell for reaction. Ions with other mass-to-charge ratios (such as...) are excluded. 19 F - and 88 Sr 2+The ions were filtered and discarded. NH3 was introduced into the dynamic reaction cell to induce addition. The flow rate of the reaction gas was set to 1.0 mL / min, and the band resistance parameter q (RPq) of the dynamic reaction cell was set to 0.35 to remove interfering ions. The mass-to-charge ratio (m / z) of the second quadrupole analyzer (Q3) was set to 90 to 200, allowing only ions with m / z = 90 to 200 to pass through Q3 and enter the detector, where they were converted into an electrical signal, resulting in the detection spectrum (see [link to spectrum]). Figure 3 ), Figure 3 a)-e) are the detection spectra of the test solutions using water, 4% nitric acid, 4% hydrochloric acid, 4% perchloric acid and 4% ammonium chloride as solvents, respectively.

[0135] Figure 3 The main mass spectrometry peaks are assigned as follows:

[0136] Peak 1: 88 Sr( 14 N 1 H) + Peak 2: 88 Sr( 14 N 1 H2) + Peak 3: 88 Sr( 14 N 1 H3) + Peak 4: 88 Sr 19 F + Peak 5: 35 Cl( 14 N 1 H3)( 14 N 1 H2)4 + Peak 6: 35 Cl( 14 N 1 H3)2( 14 N 1 H2)3 + Peak 7: 88 Sr( 14 N 1 H)2 + Peak 8: 88 Sr( 14 N 1 H2) 14 N 1 H) + Peak 9: 88 Sr( 14 N 1 H2)2 + Peak 10: 88 Sr( 14 N 1 H3)(14 N 1 H2) + Peak 11: 88 Sr( 14 N 1 H3)2 + Peak 12: 88 Sr 35 Cl + Peak 13: 88 Sr 19 F( 14 N 1 H3) + Peak 14: 88 Sr 37 Cl + Peak 15: 86 Sr( 14 N 1 H)3 + Peak 16: 88 Sr( 14 N 1 H2)2( 14 N 1 H) + Peak 17: 88 Sr( 14 N 1 H2)3 + Peak 18: 88 Sr( 14 N 1 H3)2( 14 N 1 H) + Peak 19: 88 Sr( 14 N 1 H3)2( 14 N 1 H2) + .

[0137] It can be seen that, Figure 3 Peak 4 appeared in all five subplots (a)-e). 88 Sr 19 F + This indicates that after the F standard working solution and the Sr standard working solution are mixed online, they ionize in the ICP tube to produce... 88 Sr 19 F + ; Figure 3 Peaks 12 and 14 were observed in all samples c)-e). Peaks 12 and 14 clearly match the natural abundance ratio of Cl, therefore peak 12 is inferred to be Cl. 88 Sr 35 Cl + Peak 14 is 88 Sr37 Cl + This indicates that when hydrochloric acid, perchloric acid, or ammonium chloride is used as a solvent in the Sr and F standard working solutions, Cl... - With Sr + The reaction proceeds in solution to generate strontium chloride, which is then ionized in an ICP-controlled rectangular tube to produce strontium chloride cations. (Comparison) Figure 3 As shown in a)-b) and c)-e), when chloride ions are absent, strontium preferentially forms a series of adducts with higher coordination numbers with ammonia or ammonia fragments, at which point peak 19 dominates. When chloride ions are present, strontium preferentially produces strontium chloride, with higher intensities at peaks 12 and 14. This leads to the transformation of the strontium-ammonia adduct with higher coordination numbers into adducts with lower coordination numbers (unstable state). These unstable strontium-ammonia low-coordination-number adducts, as well as strontium chloride, are more likely to coordinate with fluorine, forming… 88 Sr 19 F + It can be seen that the presence of chloride ions in the solvents of the Sr and F standard working solutions can promote... 88 Sr 19 F + Formation. Contrast. Figure 3 From (c)-e), it can be seen that hydrochloric acid is used as a solvent in both the Sr and F standard working solutions, resulting in... 88 Sr 37 Cl + The mass spectrometry response was the highest, and the quantity was relatively large.

[0138] In summary, using chloride-containing solvents, especially hydrochloric acid, as the solvent in both the Sr and F standard working solutions can significantly promote [the desired effect]. 88 Sr 19 F + form.

[0139] Example 3

[0140] This embodiment is illustrated by... 88 Sr 19 F + Signal enhancement experiments were conducted to verify the selection of target ions.

[0141] Following the method in Example 1, a 100 mg / L Sr standard working solution and a 50 mg / L F standard working solution were prepared. ICP-MS / MS was performed using the 0.0 mg / L and 50 mg / L F standard working solutions as test solutions, respectively.

[0142] The inductively coupled plasma mass spectrometer (ICP-MS) used in step (3) of Example 1 was employed for detection. The instrument is equipped with a quartz inner diameter center tube (1.5 mm) and a semiconductor cooled atomizing chamber (PC3X). The first quadrupole analyzer (Q1) and the second quadrupole analyzer (Q3) are connected via a dynamic reaction cell, which uses high-purity ammonia (99.999% purity) as the reaction gas. In MS / MS mode, the product ion scanning mode was set, with the following acquisition parameters: residence time per atomic mass unit of 300 ms and integration time of 6000 ms.

[0143] Set the mass-to-charge ratio of Q1 to 107, and the mass-to-charge ratio of Q3 to 80-200, according to... Figure 1 The analysis was conducted using a specific method: a T-tube injection was used, with the test solution entering through the first tube and the Sr standard working solution entering through the second tube. The volumetric flow rate ratio of the test solution to the Sr standard working solution was 1:3. The solution was fed into the semiconductor-cooled atomization chamber PC3X by a carrier gas (argon) for online mixing and atomization. The temperature of the semiconductor-cooled atomization chamber was set to -2℃, and the atomizer flow rate was 1.2 L / min, forming an aerosol. The aerosol entered the ICP plasma torch, with the RF power set to 1600 W, the plasma flow rate set to 16 L / min, and the auxiliary gas (argon) flow rate set to 1.2 L / min, generating… 88 Sr 19 F + Plasma. The mass-to-charge ratio (m / z) of the first quadrupole analyzer (Q1) is set to 107, allowing only ions with m / z = 107 to pass through Q1 and enter the dynamic reaction cell for reaction; ions with other mass-to-charge ratios are filtered and discarded. NH3 reaction gas is introduced into the dynamic reaction cell to induce addition. The reaction gas flow rate is set to 1.0 mL / min, and the band resistance parameter q (RPq) of the dynamic reaction cell is set to 0.35 to remove interfering ions. The mass-to-charge ratio (m / z) of the second quadrupole analyzer (Q3) is set to 80 to 200, allowing only ions with m / z = 80 to 200 to pass through Q3 and enter the detector, where they are converted into electrical signals, resulting in the detection spectrum (see...). Figure 4 ), Figure 4 In Figure a), the detection spectrum of the test solution is 0.0 F standard working solution (i.e., Sr (4% hydrochloric acid) system). Figure 4 b) is the detection spectrum of the test solution being a 50 mg / L F standard working solution (i.e., the SrF (4% hydrochloric acid) system).

[0144] Figure 4 The main mass spectrometry peaks are assigned as follows:

[0145] Peak 1: 88 Sr + Peak 2: 88 Sr 1 H316 O + \ 88 Sr 19 F + ; Peak 3: 88 Sr( 14 N 1 H3)( 1 H3 16 O) + \ 88 Sr 19 F( 14 N 1 H3) + ; Peak 4: 88 Sr( 14 N 1 H3)2( 1 H3 16 O) + \ 88 Sr 19 F( 14 N 1 H3)2 + ; Peak 5: 88 Sr( 14 N 1 H3)4 + ; Peak 6: 88 Sr( 14 N 1 H3)3( 1 H3 16 O) + \ 88 Sr 19 F( 14 N 1 H3)3 + ; Peak 7: 88 Sr( 14 N 1 H3)5 + ; Peak 8: 88 Sr( 14 N 1 H3)4( 1 H3 16 O) + ; Peak 9: 88 Sr( 14 N 1 H3)6 + ; Peak 10: 88 Sr( 14 N 1 H3)5( 1 H2 16 O) + \ 88 Sr 19 F( 14N 1 H3)5 + .

[0146] Figure 4 In a) peak 2 was observed. Considering the isotopic abundance ratio of O and H, it is inferred that peak 2 is... 88 Sr 1 H3 16 O + Peak 10 is 88 Sr( 14 N 1 H3)5( 1 H2 16 O) + . Figure 4 Peak 2 observed in (b) is 8 Sr 19 F + Peak 10 is 88 Sr 19 F( 14 N 1 H3)5 + Compared to the Sr (4% hydrochloric acid) system, SrF + In the (4% hydrochloric acid) system, peak 2 ( 88 Sr 19 F + The signal enhancement factor is approximately 30 times, although the peak 10 ( 88 Sr 19 F( 14 N 1 H3) 5+ There was also a significant enhancement, but only by a factor of 10. Therefore, this method chose m / z=107. 88 Sr 19 F + As the target ion.

[0147] Example 4

[0148] This embodiment is used to test the ability to resist sulfate ion interference.

[0149] Following the method in step (2) of Example 1, 100 mg / L F standard solution (with standard certificate, purchased from the National Nonferrous Metals and Electronic Materials Analysis and Testing Center, batch number 258019) and 1000 μg / mL sulfate ion standard solution (purchased from the National Nonferrous Metals and Electronic Materials Analysis and Testing Center, batch number 248004) were used, and 4% hydrochloric acid (4% mass fraction of hydrogen chloride aqueous solution) was used as solvent to prepare sample solutions with sulfate ion concentrations of 0, 5, 10, 20, 50, 100, 150, 200, and 300 mg / L, respectively. The F ion concentration in each of the sample solutions was 50 mg / L, and these solutions were used as test solutions for subsequent detection.

[0150] The sample solution was tested according to step (3) in Example 1. 88 Sr 19 F + The signal intensity was normalized using the signal intensity of the sample solution with a sulfate ion concentration of 0 as a benchmark, and the effects of different sulfate ion concentrations on the signal were detected. 88 Sr 19 F + The influence of signal strength.

[0151] Meanwhile, a Ba standard solution (with a standard certificate, purchased from the National Nonferrous Metals and Electronic Materials Analysis and Testing Center, batch number 254006-3) was purchased and diluted with 4% hydrochloric acid (4% mass fraction of hydrogen chloride aqueous solution) to a Ba standard working solution with a concentration of 100 mg / L.

[0152] The inductively coupled plasma tandem mass spectrometer used in step (3) of Example 1 was employed for the following tests. 138 Ba 19 F(NH3)3 + The signal strength was detected using the following method: In MS / MS mode, mass transfer mode was set, and the acquisition parameters were: residence time per atomic mass unit of 300 ms and integration time of 6000 ms. A T-tube injection was used, with the test solution entering through the first tube and the Ba standard working solution entering through the second tube. The volumetric flow rate ratio of the test solution to the Ba standard working solution was 1:3. The solution was fed into the semiconductor-cooled atomization chamber PC3X by carrier gas (argon) for online mixing and atomization. The temperature of the semiconductor-cooled atomization chamber was set to -2℃, and the atomizer flow rate was 1.2 L / min to form an aerosol. The aerosol entered the ICP plasma torch, with the RF power set to 1400 W, the plasma flow rate to 16 L / min, and the auxiliary gas (argon) flow rate to 1.1 L / min. The mass-to-charge ratio (m / z) of the first quadrupole analyzer (Q1) is set to 157, allowing only ions with m / z = 157 to pass through Q1 and enter the dynamic reaction cell for reaction. Ions with m / z = 157 include... 138 Ba 19 F + and interfering ions 138 Ba 18 O 1 H + , 138 Ba 1 H3 16 O + and 138 Ba 17 O 1 H2 +NH3 reaction gas was introduced into the dynamic reaction cell. The flow rate of the reaction gas was set to 1.3 mL / min, and the band resistance parameter q (RPq) of the dynamic reaction cell was set to 0.38, so that interfering ions with m / z = 107 were released by Q1. 138 Ba 18 O 1 H + , 138 Ba 1 H3 16 O + and 138 Ba 17 O 1 H2 + The ions undergo addition with NH3 to generate product ions with different mass-to-charge ratios, thus removing interfering ions. Simultaneously... 138 Ba 19 F + It undergoes addition with NH3 to form 138 Ba 19 F(NH3)3 + Set the mass-to-charge ratio (m / z) of the second quadrupole analyzer (Q3) to 208, allowing only values ​​of m / z = 208. 138 Ba 19 F(NH3)3 + Ions pass through Q3 and enter the detector, where they are converted into an electrical signal, allowing the determination of the target ion in the test solution. 138 Ba 19 F(NH3)3 + The signal intensity. The target ion in the sample solution with a sulfate ion concentration of 0. 138 Ba 19 F(NH3)3 + Using signal intensity as a baseline, normalization was performed to compare the effects of different concentrations of sulfate ions on the target ion. 138 Ba 19 F(NH3)3 + The influence of signal strength.

[0153] Different concentrations of sulfate ions 88 Sr 19 F + and 138 Ba 19 F(NH3)3 + The effect of signal strength is as follows Figure 5 As shown, with the increase of sulfate ion concentration in the sample, 138 Ba 19 F(NH3)3 + The signal strength reduction was significantly higher than 88 Sr 19 F +The degree of signal intensity reduction indicates that, under conditions of high sulfate ion concentration, the target ion... 88 Sr 19 F + Its ability to resist sulfate ion interference is significantly better.

[0154] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0155] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A method for detecting the fluorine content in food, characterized in that, Includes the following steps: Samples containing fluorine are digested by microwave to prepare sample solutions; A tandem quadrupole inductively coupled plasma mass spectrometer was used to mix the sample solution with the Sr standard working solution online. After ionization, the solution was separated by the first quadrupole analyzer. 88 Sr 19 F + The first intermediate product; the first intermediate product is passed into a reaction cell containing ammonia to remove interfering ions, and then separated by a second quadrupole analyzer. 88 Sr 19 F + The second intermediate product, with 88 Sr 19 F + The target ion was detected, and the fluorine content in the sample was calculated using the external standard method.

2. The method for detecting fluoride content in food according to claim 1, characterized in that, It meets at least one of the following characteristics: (1) The specific steps for calculating the fluorine content in a sample using the external standard method include: Determining the formation of a series of F standard working solutions 88 Sr 19 F + To determine the signal intensity, a standard curve of F concentration-signal intensity was established, and the sample solution was analyzed. 88 Sr 19 F + The signal intensity was substituted into the standard curve to calculate the fluorine content in the sample; (2) The sample containing fluorine also includes sulfur; (3) The sample solution includes fluoride ions and sulfate ions.

3. The method for detecting fluoride content in food according to claim 1 or 2, characterized in that, The conditions for the tandem quadrupole inductively coupled plasma mass spectrometer include: In MS / MS mode, using the same mass mode, the mass-to-charge ratio of both the first and second quadrupole analyzers is set to 107.

4. The method for detecting fluoride content in food according to claim 1, characterized in that, The interfering ions include 88 Sr 18 O 1 H + , 88 Sr 1 H3 16 O + , 88 Sr 17 O 1 H2 + and 107 Ag + At least one of them.

5. The method for detecting fluoride content in food according to claim 3, characterized in that, The conditions for the tandem quadrupole inductively coupled plasma mass spectrometer also include: It adopts a quartz inner diameter central tube and a semiconductor cooling atomization chamber; The temperature of the semiconductor cooling atomization chamber is -2 to 25 °C; RF power is 1000~1600 W; The atomizer flow rate is 0.8~1.2 L / min; The plasma flow rate is 12~16 L / min; The auxiliary gas flow rate is 0.8~1.2 L / min; The reaction gas flow rate is 0.8~1.2 mL / min; The acquisition parameters are: residence time per atomic mass unit is 100~600 ms, and integration time is 3000~6000 ms; The resistance parameter q of the dynamic reaction cell is 0.2~0.

4.

6. The method for detecting fluoride content in food according to claim 5, characterized in that, The inner diameter of the quartz inner diameter center tube is 0.6~2.0 mm; the semiconductor cooling atomization chamber includes PC3X.

7. The method for detecting fluoride content in food according to claim 1, characterized in that, The Sr standard working solution is prepared by the following method: A Sr standard working solution is prepared by mixing a Sr standard solution with a chloride ion-containing solution.

8. The method for detecting fluoride content in food according to claim 7, characterized in that, The chloride-containing solution includes at least one of hydrochloric acid solution, perchloric acid solution, ammonium chloride solution, and a mixed solution of ammonium chloride and nitric acid.

9. The method for detecting fluoride content in food according to claim 7, characterized in that, The specific steps for microwave digestion of samples containing fluorine include: The sample containing fluorine was mixed with an aqueous solution of nitric acid and then placed in a microwave digester for microwave digestion.

10. The method for detecting fluoride content in food according to claim 9, characterized in that, It meets at least one of the following characteristics: (1) The conditions for microwave digestion include: At a power of 800~1000 W, the temperature is raised from 20~30 ℃ to 120~150 ℃ within 5~10 min, and held for 5~10 min; then at a power of 1400~1600 W, the temperature is raised to 180~200 ℃ within 5~10 min, and held for 15~25 min. (2) After microwave digestion of the sample containing fluorine, the method further includes the step of diluting the product after microwave digestion with water to form the sample solution.

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