Preparation method of standard mixed gas

Abstract

The invention provides a preparation method of standard mixed gas. The invention develops a 1, 1-difluoro-2-chloroethylene and 1-chloro-1-fluoroethylene mixed gas reference substance, and provides a basis for quality control of aerosol propellants. The method comprises the following steps: filling nitrogen with 1, 1-difluoro-2-chloroethylene and 1-chloro-1-fluoroethylene to prepare a mixed gas reference substance, carrying out structure confirmation by adopting IR, MS and MR, determining moisture by adopting a coulometric method, testing the packaging tightness by adopting a closed water method, determining the content of each component by adopting a standard curve method, analyzing and investigating the uniformity by adopting a single factor variance, and determining the quality of the product. And the short-term stability and the pressure stability are respectively investigated through linear fitting and pressure release experiments, and the uncertainty introduced in the valuing process is evaluated. According to the research, the 1, 1-difluoro-2-chloroethylene and 1-chloro-1-fluoroethylene mixed gas reference substance is prepared for the first time, and the reference substance can be used as a reference substance for checking aerosol propellant related substances.

Description

Technical Field

[0001] The invention belongs to the technical field of quality control of medicinal aerosol auxiliary materials and propellants, and in particular relates to a method for preparing a standard mixed gas. Background Art

[0002] 1,1,1,2-tetrafluoroethane (HFA-134a) is a low-boiling, low-toxic, non-flammable hydrofluoroalkane. It is gaseous at room temperature and liquid under pressure. It is currently the most widely used propellant in pharmaceutical aerosols, especially pharmaceutical inhalation aerosols [Chen Kefeng, Ma Xiaohong. Development of 1,1,1,2-tetrafluoroethane [J]. Organic Fluorine Industry, 2005, 3: 16-20]. As an important auxiliary propellant for pharmaceutical aerosols, the quality of HFA-134a directly affects the safety and effectiveness of drugs. Especially when used in inhalation aerosols, it will enter the body with the drug and directly affect people's life and health [SELLERS WFS. Asthma pressurised metered dose inhaler performance: propellant effect studies in delivery systems [J]. Allergy Asthma Clin Immunol, 2017, 13 (30): 1-7].

[0003] The synthetic route of HFA-134a is complicated, and many impurities of varying toxicity are produced during the production process [Zhang Danni, Mao Ligan. Research Progress on the Synthesis Process of Refrigerant 1,1,1,2-Tetrafluoroethane HFC-134a [J]. Shandong Chemical Industry, 2016, 45(5): 40-41, 44], so the composition and content of impurities are the focus of HFA-134a quality control. However, since the impurities of HFA-134a are all gaseous at room temperature and some impurities are difficult to obtain, there were no reference materials available for HFA-134a impurity inspection at home and abroad before 2019. The 2020 edition of the Chinese Pharmacopoeia, Part IV, included tetrafluoroethane (for external aerosols) for the first time [Chinese Pharmacopoeia Committee. Pharmacopoeia of the People's Republic of China [S]. Part IV. Beijing: China Medical Science and Technology Press, 2020: 649-651, 550-551, 480-483], stipulating that its content must not be less than 99.95%, and lists 12 related substances that need to be controlled. The China Food and Drug Inspection Institute also released for the first time 1,1,2,2-tetrafluoroethane (HFC-134), pentafluoroethane (HFC 125), pentafluorochloroethane (CFC 115), 1,1,1-trifluoroethane (HFC 143a) and other five impurity reference substances [Zhao Yanjun, Yi Zhongxun, Xie Langgui, et al. Development of national reference substances for pharmaceutical aerosol excipients 1,1,1,2-tetrafluoroethane and its main impurities [J]. Chinese Journal of New Drugs, 2023, 32(16): 1677-1683.], but in the actual testing process, it was found that most tetrafluoroethane products contained impurities 1,1-difluoro-2-chloroethylene (HCFC-1122) and 1-chloro-1-fluoroethylene (HCFC-1131a) [Zhao Yanjun, Yi Zhongxun, Xie Langgui, et al. National drug sampling quality analysis of propellant 1,1,1,2-tetrafluoroethane for external aerosol [J]. Chinese Pharmacist, 2022, 25(12): 2210-2216]. It is reported that HCFC-1122 can cause dose-related hepatotoxicity [SPRACKLIN DK, THUMMEL KE, KHARASCH ED. Human reductive halothane metabolism in vitro is catalyzed by cytochrome P4502A6 and 3A4 [J]. Drug Metab Dispos, 1996, 24 (9): 976-83; GOURLAY GK, ADAMS JF, COUSINS MJ, et al. Genetic differences in reductive metabolism and hepatotoxicity of halothane in three rat strains [J].Anesthesiology, 1981, 55(2): 96-103; LUMAM CA, COUSINS MJ, Hall PD. Guinea-pigmodel of halothane-associated hepatotoxicity in the absence of enzymeinduction and hypoxia[J]. J PharmacolExpTher, 1985, 232(3): 802-809; BAKER MT, BATESJN. Metabolic activation of the halothane metabolite,[14C]2-chloro-1,1-difluoroethene,in hepatic microsomes[J].DrugMetabDispos, 1988, 16(2):169-172;BAKER MT,VASQUEZ MT,BATES JN,et al.Metabolism of 2-chloro-1,1-difluoroetheneto glyoxylic and glycolic acid in rat hepatic microsomes[J].Drug Metab Dispos, 1990, 18 (5): 753-738], HCFC-1131a is mutagenic [TURNBULL D, MACHADO RJ, BOBERGRE. Safety assessment of HCFC-141b: use as a blowing agent for insulation in building construction and refrigeration [J]. Regul Toxicol Pharmacol, 1994, 19 (3): 282-296.], therefore, in order to ensure the accuracy of the content detection of impurities HCFC-1122 and HCFC-1131a in HFA-134a detection, it is urgent to establish a mixed gas reference substance of 1,1-difluoro-2-chloroethylene and 1-chloro-1-fluoroethylene. . Summary of the invention

[0004] The purpose of the present invention is to provide a method for preparing a standard mixed gas of 1,1-difluoro-2-chloroethylene and 1-chloro-1-fluoroethylene.

[0005] The method for preparing a standard mixed gas of 1,1-difluoro-2-chloroethylene and 1-chloro-1-fluoroethylene provided by the present invention comprises the following steps:

[0006] 1) Prepare the standard substance of 1,1-difluoro-2-chloroethylene and 1-chloro-1-fluoroethylene mixed gas in high-pressure gas cylinders;

[0007] 2) Use IR, MS, and MR for structural confirmation;

[0008] 3) Determine the water content by coulometric method;

[0009] 4) Test the sealing of the package using the closed water method;

[0010] 5) Determine the content of each component using the standard curve method;

[0011] 6) One-way ANOVA was used to examine uniformity;

[0012] 7) Linear fitting and pressure release experiments were used to examine short-term stability and pressure stability respectively;

[0013] 8) Evaluate the uncertainty introduced by the valuation process.

[0014] In step 1) of the above method, the high-pressure gas cylinder contains a mixed gas standard substance of 1,1-difluoro-2-chloroethylene and 1-chloro-1-fluoroethylene, the concentration of 1,1-difluoro-2-chloroethylene is about 0.3 μg / ml (0.3±0.03 μg / ml), the concentration of 1-chloro-1-fluoroethylene is about 0.1 μg / ml (0.1±0.01 μg / ml), and the balance is nitrogen; the pressure is 9.5 MPa.

[0015] In step 2), the MR test is carried out using the raw materials 1,1-difluoro-2-chloroethylene, 1-chloro-1-fluoroethylene pure product and the mixed gas standard substance. The high-pressure gas cylinder containing the sample is connected to the pressure reducer, and after adjusting the pressure appropriately, it is connected to the stainless steel injection needle. An appropriate amount of sample is passed into deuterated chloroform and collected on the nuclear magnetic resonance spectrometer. 1 H spectrum, 13 C spectrum, 19 F spectrum;

[0016] IR test was carried out with raw materials 1,1-difluoro-2-chloroethylene, 1-chloro-1-fluoroethylene pure products and the mixed gas standard substances, that is, take a proper amount of sample, inject it into the infrared gas cell, and scan the range of 4000~500cm -1 , resolution 4cm -1 , first perform a background scan on the blank infrared gas cell under the same parameters, then scan the sample and record the infrared spectrum of the sample;

[0017] Gas chromatography-mass spectrometry was used to randomly take samples and inject them into the gas sampling bag. The injection needle was repeatedly rinsed with the sample and 1.0 ml was injected into the gas chromatograph. The gas chromatography conditions were as follows: chromatographic column: DB-1301 (120 m × 0.25 mm × 1.0 μm), column temperature: -15 °C for 20 min, at 10.0 °C min -1 Raise to 120℃, then at 20.0℃·min -1 Heat to 220℃ and hold for 10min, injection port temperature: 230℃, flow rate: 1.5ml·min -1 , split ratio: 30:1, ion source temperature: 200°C; quadrupole temperature: 250°C; m / z is 10-120Da.

[0018] In step 5), the content of 1,1-difluoro-2-chloroethylene and 1-chloro-1-fluoroethylene in the sample is determined by the standard curve method, and the specific operation is as follows:

[0019] The raw materials 1,1-difluoro-2-chloroethylene and 1-chloro-1-fluoroethylene were accurately weighed into the vacuum gas sampling bag, and the volumes of 1,1-difluoro-2-chloroethylene and 1-chloro-1-fluoroethylene were calculated according to the ideal gas state equation PV = nRT, where T is the sampling environment temperature (20 °C), P is the ambient pressure (1 standard atmospheric pressure 1.01325 × 10 5 Pa), n is the amount of substance (n = m / M, where m is the sample mass, M is the molar mass of the substance, the molar mass of 1-chloro-1-fluoroethylene is 80.49 g / mol, the molar mass of 1,1-difluoro-2-chloroethylene is 98.48 g / mol), R is the ideal gas constant, about 8.314 J / mol·K; then accurately measure 1,1-difluoro-2-chloroethylene and 1-chloro-1-fluoroethylene, respectively, and inject them into the vacuum gas sampling bag, and dilute them with nitrogen to make a vacuum gas sampling bag containing 1,1-difluoro-2- Mixed reference gas of vinyl chloride 2.045μg / ml and 1-chloro-1-fluoroethylene 1.671μg / ml; continued to dilute with nitrogen step by step to make a series of mixed reference gases for gas chromatography analysis; chromatographic conditions: chromatographic column: DB-1301 (120m×0.25mm, 1.00μm); detector: flame ionization detector (FID), 230℃; injection port temperature: 200℃, split ratio 30:1; column temperature: initial temperature -15℃, maintained for 20min, at 10℃·min -1 The rate was raised to 120℃, and then at 20℃·min -1 The temperature was raised to 220°C and maintained for 10 min; carrier gas flow rate: nitrogen 1.5 ml min -1; Injection volume: 1.0 ml; injection environment temperature 20 ° C, record the chromatographic peak area of ​​the series of concentrations of the mixed reference gas, and use the peak area to perform linear regression on the concentration to obtain the standard curve of the two components. The sample concentration with a signal-to-noise ratio S / N value of 3 is used as the detection limit, and the sample concentration with a signal-to-noise ratio S / N value of 10 is used as the quantification limit;

[0020] Randomly take appropriate amounts of two samples and inject them into the vacuum gas sampling bag, then inject them into the gas chromatograph according to the above chromatographic conditions, record the peak areas of the two components in the samples, and substitute them into the standard curve to calculate the contents of the two components.

[0021] In step 6), a plurality of samples are randomly selected and injected into a vacuum gas sampling bag as test samples, and injected into a gas chromatograph according to the chromatographic conditions under the content determination, and the chromatogram is recorded. The peak areas of 1,1-difluoro-2-chloroethylene and 1-chloro-1-fluoroethylene are substituted into the standard curve to calculate the contents of the two components, and the contents of 1,1-difluoro-2-chloroethylene and 1-chloro-1-fluoroethylene are respectively counted and analyzed by one-way variance, and the uniformity is determined by the test level p value and the comparison of the F test value and the F critical value.

[0022] In step 7), the changes in temperature and relative humidity during transportation are simulated, and the samples are placed in a constant temperature and humidity chamber at a temperature of 40°C and a relative humidity of 60%. Gas chromatography is performed on days 0, 5 and 10, respectively, and the peak area percentages of the two components are recorded. The classical linear model is used for judgment, that is, the monitoring time is used as the horizontal coordinate and the peak area percentage measurement result is used as the vertical coordinate for linear fitting to obtain the straight line slope b1. The t test (degree of freedom is n-2) is used for judgment. If This indicates that the slope is not significant and the stability is good;

[0023] A sample was randomly selected and connected to a pressure reducing gauge with an initial pressure of 10 MPa. The gas in the bottle was slowly released and injected into the gas chromatograph at 8, 6, 4, and 2 MPa according to the chromatographic conditions for content determination. The contents and peak area percentages of 1,1-difluoro-2-chloroethylene and 1-chloro-1-fluoroethylene in the mixed reference substance at the corresponding pressures were determined. The pressure stability of the sample was investigated using the relative standard deviations (RSDs) of the contents and peak area percentages of the two components at different pressures.

[0024] In step 8), according to "Guidelines for Standard Sample Work Part 3: Value determination and uniformity and stability assessment of standard samples (GB / T 15000.3-2023)", the uncertainty of the content determination of the mixed gas standard substance of 1,1-difluoro-2-chloroethylene and 1-chloro-1-fluoroethylene is introduced by three parts: uniformity, long-term stability and value determination process. The uncertainty introduced by the value determination process is divided into two parts: one is the uncertainty calculated by statistical methods, that is, Type A assessment of uncertainty, which is mainly the uncertainty introduced by standard curve fitting and measurement repeatability; the other is the uncertainty assessed by non-statistical analysis methods through analysis of measurement influencing factors, that is, Type B assessment of uncertainty, which is mainly the uncertainty of gas chromatography measurement.

[0025] The uncertainty introduced by uniformity is calculated according to formula (1):

[0026]

[0027] Where u bb is the uncertainty caused by the uniformity between units, S bb is the standard deviation between units, M brtween is the mean square between groups, M within is the within-group mean square, n0 is the number of repeated measurements for each unit;

[0028] The uncertainty introduced by long-term stability is not calculated;

[0029] The uncertainty introduced by the setting process is calculated according to formula (2-4):

[0030]

[0031] In the formula, is the uncertainty introduced by fitting the standard working curve to obtain the content of each component in the component to be measured; S is the residual standard deviation of the peak area in the standard working curve; S xx is the residual sum of squares of mass concentration; a is the intercept of the standard working curve; b is the slope of the standard working curve; C i is the mass concentration point of the standard curve; A i is the peak area value measured at each mass concentration point; n is the number of the prepared series of standard solutions; is the average mass concentration of the standard solution; P is the number of parallel measurements of the sample; x0 is the average mass concentration of each substance in the sample solution.

[0032] The uncertainty introduced by measurement repeatability is calculated according to formula (5):

[0033]

[0034] In the formula, is the uncertainty introduced by measurement repeatability; S is the standard deviation of the content obtained by n measurements; n is the number of repeated measurements.

[0035] The uncertainty of gas chromatography measurement is calculated according to formula (6):

[0036]

[0037] In the formula, u B is the uncertainty of gas chromatography; x is the content of the measured component; u GC The uncertainty of gas chromatography detection of gas substances is given by the instrument measurement certificate.

[0038] According to formula (7), the sources of each uncertainty component are combined to obtain the combined standard uncertainty u CRM , the expanded uncertainty is obtained by expanding the combined uncertainty, and the coverage factor is 2;

[0039]

[0040] The standard mixed gas of 1,1-difluoro-2-chloroethylene and 1-chloro-1-fluoroethylene prepared by the above method also belongs to the protection scope of the present invention.

[0041] In the standard mixed gas of 1,1-difluoro-2-chloroethylene and 1-chloro-1-fluoroethylene, the concentration of 1,1-difluoro-2-chloroethylene is 0.329±0.018 μg / ml (expansion factor k=2), and the concentration of 1-chloro-1-fluoroethylene is 0.111±0.004 μg / ml (expansion factor k=2) (20°C, under standard atmospheric pressure).

[0042] The use of the above-mentioned standard mixed gas of 1,1-difluoro-2-chloroethylene and 1-chloro-1-fluoroethylene as a reference substance for the inspection of tetrafluoroethane-related substances also falls within the protection scope of the present invention.

[0043] The content of 1,1-difluoro-2-chloroethylene in the mixed gas reference substance is 0.329±0.018μg / ml (expansion factor k=2), and the content of 1-chloro-1-fluoroethylene is 0.111±0.004μg / ml (expansion factor k=2) (20℃, standard atmospheric pressure), with good uniformity and stability.

[0044] At present, the European Pharmacopoeia and the United States Pharmacopoeia have not published tetrafluoroethane related impurity reference substances. The China National Institute of Metrology has published reference substances for tetrafluoroethane and its related impurities, such as GBW06321 (tetrafluoroethane gas standard substance in nitrogen), GBW08188 (1,1,1,2-tetrafluoroethane gas standard substance in nitrogen), GBW08189 (1,1,2,2-tetrafluoroethane gas standard substance in nitrogen), etc., which are reference substances with known trace amounts of target substances filled into nitrogen. They are mainly used by environmental protection departments to monitor the emission of tetrafluoroethane greenhouse gas or volatile organic compound mixed gas in the atmosphere. The target content of such standard substances is much lower than that of pharmaceutical propellants, and the composition is quite different from the related substances in pharmaceutical propellants. They cannot be used for the qualitative and quantitative determination of related substances in 1,1,1,2-tetrafluoroethane, an excipient for pharmaceutical aerosols. In addition, there are some commercially available reference materials that are made by dissolving a trace amount of tetrafluoroethane or its related substances in a suitable solvent such as methanol and then sealing them in ampoules. However, since tetrafluoroethane and its related substances are gases at room temperature, they are easily vaporized when the ampoule is opened, resulting in inaccurate quantification. In addition, due to the influence of the solvent, the relative retention time in the gas chromatography will be different, and it cannot be used for infrared identification. The four impurity reference materials HFC-134, HFC 125, CFC 115, and HFC 143a that have been released by the China Food and Drug Inspection Institute are directly packaged into aluminum cans in liquid form due to their low toxicity and large supply of raw materials. However, since both 1,1-difluoro-2-chloroethylene and 1-chloro-1-fluoroethylene have certain toxicity and their raw materials are difficult to obtain, the two components are filled into nitrogen according to their limit requirements to prepare a mixed gas reference material, which not only reduces the risk of use, but also facilitates actual testing.

[0045] The present invention charges 1,1-difluoro-2-chloroethylene and 1-chloro-1-fluoroethylene into nitrogen by weighing method to prepare mixed gas, uses infrared, mass spectrometry, and nuclear magnetic resonance spectroscopy to confirm the structure of the prepared 1,1-difluoro-2-chloroethylene and 1-chloro-1-fluoroethylene mixed gas reference substance or its raw materials, uses the coulometric method to determine the moisture content, uses the closed water method to test the sealing of the package, uses the standard curve method to determine the content of each component, conducts uniformity and stability inspections, and evaluates the uncertainty introduced in the determination process. For the first time, a national-level 1,1-difluoro-2-chloroethylene and 1-chloro-1-fluoroethylene mixed gas reference substance was successfully developed, filling the gap at home and abroad. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 This is the mass spectrum of the mixed gas reference of 1,1-difluoro-2-chloroethylene and 1-chloro-1-fluoroethylene. DETAILED DESCRIPTION

[0047] The present invention is further described in detail below in conjunction with specific embodiments, and the examples provided are only for illustrating the present invention, rather than for limiting the scope of the present invention. The examples provided below can be used as a guide for further improvements by those of ordinary skill in the art, and do not constitute a limitation of the present invention in any way.

[0048] The experimental methods in the following examples, unless otherwise specified, are all conventional methods, and are performed according to the techniques or conditions described in the literature in the field or according to the product instructions. The materials, reagents, etc. used in the following examples, unless otherwise specified, can all be obtained from commercial channels.

[0049] Example

[0050] 1. Samples and reagents

[0051] Reference material raw materials: 1,1-difluoro-2-chloroethylene (APOLLO SCIENTIFIC, UK, batch number: AS506940, purity 99%), 1-chloro-1-fluoroethylene (APOLLO SCIENTIFIC, UK, batch number: AS490646, purity 99%), nitrogen (Datang Technology (Wuhan) Co., Ltd., batch number: 202209291600, purity ≥99.999%).

[0052] Reagents: Coulometric test solution, diaphragm or diaphragm-free universal - shared cathode and anode solutions (FLUKA, Germany, batch number: H0800); deuterated chloroform (Annaiji Chemical, batch number: 0JCERXGR, purity 99.9%).

[0053] 2. Instruments

[0054] GC-2030 / GCMS-TQ2020NX gas chromatograph (Shimadzu, Japan); Avance III nuclear magnetic resonance spectrometer (Bruker, Germany); SPECTRUM 100 Fourier transform infrared spectrometer (PE, USA); GC-2010Plus gas chromatograph (Shimadzu, Japan); chromatographic column DB-1301 (120m×0.25mm×1.00μm); C30D coulometric moisture meter (Mettler-Toledo, Switzerland); XS205DU electronic balance (Mettler-Toledo, Switzerland).

[0055] 3. Methods

[0056] 3.1 Preparation of mixed gas reference

[0057] According to "Preparation of mixed gas for gas analysis calibration Part 1: Preparation of primary mixed gas by weighing method (GB / T5274.1-2018 / ISO 6142-1:2018)", prepare the standard substance of 1,1-difluoro-2-chloroethylene and 1-chloro-1-fluoroethylene mixed gas in high-pressure gas cylinders, where the concentration of 1,1-difluoro-2-chloroethylene is about 0.3μg / ml, the concentration of 1-chloro-1-fluoroethylene is about 0.1μg / ml, and the balance is nitrogen. Prepare a total of 100 tubes, each with a capacity of 700ml and a pressure of 9.5MPa.

[0058] 3.2 Property identification and structure confirmation

[0059] 3.2.1 Appearance

[0060] Take a sample and put it into a vacuum gas sampling bag. Observe it with the naked eye and it is a colorless gas.

[0061] 3.2.2 Nuclear Magnetic Resonance

[0062] In the mixed gas reference substance, 1,1-difluoro-2-chloroethylene and 1-chloro-1-fluoroethylene are both trace substances and volatile gases, so they may be below the detection limit of nuclear magnetic resonance. Considering that the preparation of the mixed gas reference substance is carried out in the gas pipeline after the raw material gas is replaced several times, the possibility of mixing with other substances is very small. Therefore, the test is carried out with its raw materials 1,1-difluoro-2-chloroethylene, 1-chloro-1-fluoroethylene pure product and the mixed gas reference substance: connect the high-pressure gas cylinder containing the sample to the pressure reducer, adjust its pressure appropriately and connect it to the stainless steel injection needle, pass an appropriate amount of sample into deuterated chloroform, and collect on the nuclear magnetic resonance spectrometer. 1 H spectrum, 13 C spectrum, 19 F spectrum. The results are shown in Table 1. The raw materials 1,1-difluoro-2-chloroethylene and 1-chloro-1-fluoroethylene 1 H spectrum, 13 C spectrum, 19The F spectrum is consistent with the literature reports [American Chemical Society.CAS SciFinder.359-10-4.[EB / OL].(2004-11-2)[2023-9-20].https: / / scifinder-n.cas.org / searchDetail / substance / 66a7322bdd70296505ef99cb / substanceDetails; American Chemical Society.CASSciFinder.2317-91-1[EB / OL].(2020-6-15)[2023-9-20].https: / / scifinder-n.cas.org / searchDetail / substance / 66a7330fdd70296505efaaf0 / substanceDetails], and the mixed gas reference 13 C spectrum and 19 F spectrum has no peak due to low concentration. 1 H spectrum at relative chemical shift (5.27~5.29)×10 -6 The relative chemical shift of the 1,1-difluoro-2-chloroethylene structure is (4.77-4.80)×10 -6 and (4.50~4.59)×10 -6 The structure of the mixed control gas is consistent with that of 1-chloro-1-fluoroethylene. It can be comprehensively judged that the mixed control gas is composed of two components: 1,1-difluoro-2-chloroethylene and 1-chloro-1-fluoroethylene.

[0063] Table 1. Nuclear magnetic resonance test results of 1,1-difluoro-2-chloroethylene and 1-chloro-1-fluoroethylene and their mixed gas reference substances

[0064]

[0065] Note: * is the predicted result, Predicted NMR data calculated using Advanced Chemistry Development, Inc. (ACD / Labs), (1, 2) are the positions corresponding to H, (a) (b) are the positions corresponding to C, (b) (c) are the positions corresponding to F, N / A means not applicable.

[0066] 3.2.3 Infrared spectroscopy

[0067] For the same reasons as in 3.2.2 NMR, the test was conducted using the raw materials 1,1-difluoro-2-chloroethylene, 1-chloro-1-fluoroethylene pure products and the mixed gas reference product: Take an appropriate amount of sample and inject it into the infrared gas cell, scanning the range of 4000~500cm -1 , resolution 4cm -1 Under the same parameters, the blank infrared gas cell was first scanned for background, and then the sample was scanned and the infrared spectrum of the sample was recorded. Due to the low concentration of 1,1-difluoro-2-chloroethylene and 1-chloro-1-fluoroethylene in the mixed gas reference, its absorption value did not correspond to the absorption value of 1,1-difluoro-2-chloroethylene and 1-chloro-1-fluoroethylene pure products one by one, but its infrared absorption value was basically consistent with the characteristic group peaks in 1,1-difluoro-2-chloroethylene and 1-chloro-1-fluoroethylene, among which 1752~1740cm -1 C=C stretching vibration, 1196~1178cm -1 CF vibration, 977~963cm -1 C-Cl vibration, 852~824cm -1 is the out-of-plane bending vibration of CH. The infrared absorption values ​​of each sample are shown in Table 2.

[0068] Table 2. Infrared spectra absorption values ​​of 1,1-difluoro-2-chloroethylene and 1-chloro-1-fluoroethylene and their mixed gas reference substances (cm -1 )

[0069]

[0070] 3.2.4 Gas chromatography-mass spectrometry

[0071] Randomly take samples and inject them into the gas sampling bag, rinse the injection needle repeatedly with the sample, and take 1.0 ml and inject it into the gas chromatograph. Gas chromatography conditions: Chromatographic column: DB-1301 (120m×0.25mm×1.0μm), column temperature: -15℃ for 20min, 10.0℃·min -1 Raise to 120℃, then at 20.0℃·min -1 Heat to 220℃ and hold for 10min, injection port temperature: 230℃, flow rate: 1.5ml·min -1 , split ratio: 30:1, ion source temperature: 200°C; quadrupole temperature: 250°C; m / z is 10-120Da.

[0072] The mass spectrum of the sample was searched through the NIST spectral library, and the two components were 1,1-difluoro-2-chloroethylene and 1-chloro-1-fluoroethylene, among which m / z=98 was the molecular ion peak of 1,1-difluoro-2-chloroethylene, and m / z=80 was the molecular ion peak of 1-chloro-1-fluoroethylene, which were consistent with their respective structures.

[0073] 3.3Physical and chemical properties

[0074] 3.3.1 Moisture

[0075] The water content of the sample was determined by the Karl Coulometry method to be 0.0042%.

[0076] 3.3.2 Packaging sealing

[0077] Through the closed water test, 11 cans of samples were randomly selected and completely placed in water. The interface and the valve were carefully observed for bubbles. If there were no bubbles, it proved that the packaging was well sealed. The test results showed that the packaging of the samples was well sealed.

[0078] 3.4 Content determination

[0079] The content of 1,1-difluoro-2-chloroethylene and 1-chloro-1-fluoroethylene in the samples was determined by the standard curve method.

[0080] Weigh 54.016 mg of raw gas 1,1-difluoro-2-chloroethylene and 71.994 mg of 1-chloro-1-fluoroethylene into the vacuum gas sampling bag. According to the ideal gas state equation PV = nRT, the volume of 1,1-difluoro-2-chloroethylene and 1-chloro-1-fluoroethylene gas is 130.62 ml and 213.01 ml respectively, where T is the sampling environment temperature (20 ° C), P is the ambient pressure (1 standard atmospheric pressure 1.01325 × 10 5 Pa), n is the amount of substance (n = m / M, where m is the sample mass, M is the molar mass of the substance, the molar mass of 1-chloro-1-fluoroethylene is 80.49 g / mol, the molar mass of 1,1-difluoro-2-chloroethylene is 98.48 g / mol), R is the ideal gas constant, about 8.314 J / mol·K. Then accurately measure 0.5 ml of 1,1-difluoro-2-chloroethylene and 1-chloro-1-fluoroethylene and inject them into the vacuum gas sampling bag, and dilute them with nitrogen to make a mixed reference gas containing 2.045 μg / ml of 1,1-difluoro-2-chloroethylene and 1.671 μg / ml of 1-chloro-1-fluoroethylene. Continue to dilute with nitrogen step by step to make a series of mixed reference gases for gas chromatography analysis. Chromatographic conditions: Chromatographic column: DB-1301 (120m×0.25mm, 1.00μm); Detector: Flame ionization detector (FID), 230℃; Inlet temperature: 200℃, split ratio 30:1; Column temperature: initial temperature -15℃, maintained for 20min, at 10℃·min -1 Speed ​​increased to 120 ℃ , and then at 20℃·min -1 The temperature was raised to 220°C and maintained for 10 min; carrier gas flow rate: nitrogen 1.5 ml min -1; Injection volume: 1.0ml; injection environment temperature 20℃. When injecting, first replace the injection system with the sample repeatedly to exhaust the excess air in the system before analyzing the sample. Record the chromatographic peak area of ​​the mixed reference gas of the series concentration respectively. Repeat the measurement twice. Use the peak area to perform linear regression on the concentration to obtain the standard curve of the two components. The sample concentration with a signal-to-noise ratio S / N value of 3 is used as the detection limit, and the sample concentration with a signal-to-noise ratio S / N value of 10 is used as the quantitative limit.

[0081] Randomly take appropriate amounts of two samples and inject them into the vacuum gas sampling bag, inject them into the gas chromatograph according to the above chromatographic conditions, record the peak areas of the two components in the samples, and substitute them into the standard curve to calculate the contents of the two components. The results are shown in Table 3.

[0082] Table 3. Content determination results of 1,1-difluoro-2-chloroethylene and 1-chloro-1-fluoroethylene mixed gas reference substances

[0083]

[0084] 3.5 Uniformity and stability

[0085] 3.5.1 Uniformity

[0086] 11 samples were randomly selected and injected into the vacuum gas sampling bag. The sample was used to repeatedly replace and clean the sampling system to exhaust the excess air in the system and then used as the test sample. Injected into the gas chromatograph according to the chromatographic conditions under the content determination, the chromatogram was recorded, and each sample was measured twice. The peak areas of 1,1-difluoro-2-chloroethylene and 1-chloro-1-fluoroethylene were substituted into the standard curve to calculate the content of the two components. The contents of 1,1-difluoro-2-chloroethylene and 1-chloro-1-fluoroethylene were counted separately and analyzed by one-way analysis of variance. The uniformity was determined by the test level p value and the comparison of the F test value and the F critical value.

[0087] According to one-way ANOVA, the content uniformity of 1,1-difluoro-2-chloroethylene was p=0.46, F=1.06; the content uniformity of 1-chloro-1-fluoroethylene was p=0.22, F=1.61. The p values ​​of the two components were both greater than 0.05, and the F test values ​​were both less than the F critical value (2.85), indicating that the uniformity of 1,1-difluoro-2-chloroethylene and 1-chloro-1-fluoroethylene in the mixed reference substance was good.

[0088] 3.5.2 Short-term stability

[0089] Simulate the changes in temperature and relative humidity during transportation, refer to the Guiding Principles for the Preparation of National Pharmaceutical Standard Materials 9901 in Part IV of the 2020 Edition of the Chinese Pharmacopoeia, take 9 samples and place them in a constant temperature and humidity chamber at a temperature of 40°C and a relative humidity of 60%, take 3 samples each for gas chromatography detection on days 0, 5 and 10, record the peak area percentages of the two components, and use the classical linear model for judgment, that is, use the monitoring time as the horizontal axis and the peak area percentage measurement result as the vertical axis for linear fitting to obtain the straight line slope b1, and use the t-test (with n-2 degrees of freedom) for judgment. If This indicates that the slope is not significant and the stability is good.

[0090] According to the linear fitting analysis, the slope of the standard curve of 1,1-difluoro-2-chloroethylene is |b1|=0.10, The slope of the standard curve of 1-chloro-1-fluoroethylene |b1|=0.10, |b1| of both components is less than The slope is not significant, indicating that the short-term stability is good when placed at a temperature of 40°C and a relative humidity of 60% for 10 days.

[0091] 3.5.3 Pressure stability

[0092] A sample was randomly selected and connected to a pressure reducing gauge with an initial pressure of 10 MPa. The gas in the bottle was released slowly and injected into the gas chromatograph at 8, 6, 4, and 2 MPa according to the chromatographic conditions for content determination. The contents and peak area percentages of 1,1-difluoro-2-chloroethylene and 1-chloro-1-fluoroethylene in the mixed reference substance at corresponding pressures were determined. The pressure stability of the sample was investigated using the relative standard deviations (RSDs) of the contents and peak area percentages of the two components at different pressures.

[0093] The investigation results are shown in Table 4. According to the 2020 edition of the "Chinese Pharmacopoeia" 9101 Analytical Method Verification Guidelines, when the component to be determined in the sample is 1 mg / g, the acceptable range of repeatability RSD is 3%. For this product, as the pressure in the gas cylinder changes, the RSDs of the content and peak area percentages of the two components are less than 3%, which is within the acceptable range. This indicates that as the pressure in the gas cylinder decreases from 10 MPa to 2 MPa, the peak area percentages and contents of 1,1-difluoro-2-chloroethylene and 1-chloro-1-fluoroethylene in the bottle do not change significantly.

[0094] Table 4. Results of the pressure stability test of the mixed gas of 1,1-difluoro-2-chloroethylene and 1-chloro-1-fluoroethylene

[0095]

[0096] 3.6 Evaluation of uncertainty of fixed values

[0097] According to "Guidelines for Standard Sample Work Part 3: Determination of Standard Samples and Assessment of Uniformity and Stability (GB / T15000.3-2023)", the uncertainty of the content determination of the mixed gas reference of 1,1-difluoro-2-chloroethylene and 1-chloro-1-fluoroethylene is introduced by three parts: uniformity, long-term stability and determination process. The uncertainty introduced by the determination process can be divided into two parts: one is the uncertainty calculated by statistical methods, that is, Type A assessment of uncertainty, which is mainly the uncertainty introduced by standard curve fitting and measurement repeatability; the other part is the uncertainty assessed by non-statistical analysis methods through analysis of measurement influencing factors, that is, Type B assessment of uncertainty, which is mainly the uncertainty of gas chromatography measurement.

[0098] 3.6.1 Uncertainty introduced by uniformity

[0099] The uncertainty introduced by uniformity is calculated according to formula (1):

[0100]

[0101] Where u bb is the uncertainty caused by the uniformity between units, S bb is the standard deviation between units, M between is the mean square between groups, M within is the within-group mean square, and n0 is the number of repeated measurements for each unit.

[0102] 3.6.2 Uncertainty introduced by long-term stability

[0103] Since this product is being developed for the first time and long-term stability studies have not yet been conducted, the uncertainty introduced by long-term stability is not calculated for the time being.

[0104] 3.6.3 Uncertainty introduced by the determination process

[0105] The uncertainty introduced by standard curve fitting is calculated according to formula (2-4):

[0106]

[0107] In the formula is the uncertainty introduced by fitting the standard working curve to obtain the content of each component in the component to be measured; S is the residual standard deviation of the peak area in the standard working curve; S xx is the residual sum of squares of mass concentration; a is the intercept of the standard working curve; b is the slope of the standard working curve; C i is the mass concentration point of the standard curve; A i is the peak area value measured at each mass concentration point; n is the number of the prepared series of standard solutions; is the average mass concentration of the standard solution; P is the number of parallel measurements of the sample; x0 is the average mass concentration of each substance in the sample solution.

[0108] The uncertainty introduced by measurement repeatability is calculated according to formula (5):

[0109]

[0110] In the formula, is the uncertainty introduced by measurement repeatability; S is the standard deviation of the content obtained by n measurements; n is the number of repeated measurements.

[0111] The uncertainty of gas chromatography measurement is calculated according to formula (6):

[0112]

[0113] In the formula, u B is the uncertainty of gas chromatography; x is the content of the measured component; u GC The uncertainty of gas chromatography detection of gas substances is given by the instrument measurement certificate.

[0114] 3.6.4 According to formula (7), the combined uncertainty components are combined to obtain the composite standard uncertainty u CRM , the expanded uncertainty is obtained by expanding the combined uncertainty, and the coverage factor is 2.

[0115]

[0116] The uncertainty of the contents of the two components in the reference gas mixture of 1,1-difluoro-2-chloroethylene and 1-chloro-1-fluoroethylene was calculated according to 3.6.1 to 3.6.4 and the results are shown in Table 5.

[0117] Table 5. Uncertainty evaluation results of the reference gas mixture of 1,1-difluoro-2-chloroethylene and 1-chloro-1-fluoroethylene

[0118]

[0119] The present invention has been described in detail above. For those skilled in the art, without departing from the purpose and scope of the present invention, and without the need to carry out unnecessary experimental conditions, the present invention can be implemented in a wide range under equivalent parameters, concentrations and conditions. Although the present invention provides specific embodiments, it should be understood that the present invention can be further improved. In a word, according to the principles of the present invention, the application is intended to include any changes, uses or improvements to the present invention, including departure from the disclosed scope in the application, and changes made with conventional techniques known in the art.

Claims

1. A method for preparing a standard mixed gas of 1,1-difluoro-2-chloroethylene and 1-chloro-1-fluoroethylene, comprising the following steps: 1) Prepare the standard substance of 1,1-difluoro-2-chloroethylene and 1-chloro-1-fluoroethylene mixed gas in high-pressure gas cylinders; 2) Use IR, MS, and MR for structural confirmation; 3) Determine the water content by coulometric method; 4) Test the sealing of the package using the closed water method; 5) Determine the content of each component using the standard curve method; 6) One-way ANOVA was used to examine uniformity; 7) Linear fitting and pressure release experiments were used to examine short-term stability and pressure stability respectively; 8) Evaluate the uncertainty introduced by the valuation process.

2. The method according to claim 1, characterized in that In step 1), the high-pressure gas cylinder contains a mixed gas standard substance of 1,1-difluoro-2-chloroethylene and 1-chloro-1-fluoroethylene, wherein the concentration of 1,1-difluoro-2-chloroethylene is 0.3±0.03 μg / ml, the concentration of 1-chloro-1-fluoroethylene is 0.1±0.01 μg / ml, and the remainder is nitrogen; the pressure is 9.5 MPa.

3. The method according to claim 1, characterized in that In step 2), the MR test is carried out using the raw materials 1,1-difluoro-2-chloroethylene, 1-chloro-1-fluoroethylene pure product and the mixed gas standard substance. The high-pressure gas cylinder containing the sample is connected to the pressure reducer, and after adjusting the pressure appropriately, it is connected to the stainless steel injection needle. An appropriate amount of sample is passed into deuterated chloroform and collected on the nuclear magnetic resonance spectrometer. 1 H spectrum, 13 C spectrum, 19 F spectrum; IR test was carried out with raw materials 1,1-difluoro-2-chloroethylene, 1-chloro-1-fluoroethylene pure products and the mixed gas standard substances, that is, take a proper amount of sample, inject it into the infrared gas cell, and scan the range of 4000~500cm -1 , resolution 4cm -1 , first perform a background scan on the blank infrared gas cell under the same parameters, then scan the sample and record the infrared spectrum of the sample; Gas chromatography-mass spectrometry was used to randomly take samples and inject them into the gas sampling bag. The injection needle was repeatedly rinsed with the sample and 1.0 ml was injected into the gas chromatograph. The gas chromatography conditions were as follows: chromatographic column: DB-1301 (120 m × 0.25 mm × 1.0 μm), column temperature: -15 °C for 20 min, at 10.0 °C min -1 Raise to 120℃, then at 20.0℃·min -1 Heat to 220℃ and hold for 10min, injection port temperature: 230℃, flow rate: 1.5ml·min -1 , split ratio: 30:1, ion source temperature: 200°C; quadrupole temperature: 250°C; m / z is 10-120Da.

4. The method according to claim 1, characterized in that: In step 5), the content of 1,1-difluoro-2-chloroethylene and 1-chloro-1-fluoroethylene in the sample is determined by the standard curve method, and the specific operation is as follows: The raw materials 1,1-difluoro-2-chloroethylene and 1-chloro-1-fluoroethylene were accurately weighed into the vacuum gas sampling bag, and the volumes of 1,1-difluoro-2-chloroethylene and 1-chloro-1-fluoroethylene were calculated according to the ideal gas state equation PV=nRT, where T is the sampling environment temperature, 20°C, and P is the ambient pressure, 1 standard atmospheric pressure 1.01325×10 5 Pa, n is the amount of substance, n = m / M, where m is the sample mass, M is the molar mass of the substance, the molar mass of 1-chloro-1-fluoroethylene is 80.49 g / mol, the molar mass of 1,1-difluoro-2-chloroethylene is 98.48 g / mol, R is the ideal gas constant, about 8.314 J / mol·K; then accurately measure 1,1-difluoro-2-chloroethylene and 1-chloro-1-fluoroethylene respectively and inject them into the vacuum gas sampling bag, and dilute them with nitrogen to prepare a mixed reference gas containing 2.045 μg / ml of 1,1-difluoro-2-chloroethylene and 1.671 μg / ml of 1-chloro-1-fluoroethylene; continue to dilute with nitrogen step by step to prepare a series of mixed reference gases for gas chromatography analysis; Chromatographic conditions: Chromatographic column: DB-1301, 120m×0.25mm, 1.00μm; Detector: flame ionization detector FID, 230°C; injection port temperature: 200°C, split ratio 30:1; column temperature: initial temperature -15°C, maintained for 20 min, at 10°C min -1 The rate was raised to 120℃, and then at 20℃·min -1 The temperature was raised to 220°C and maintained for 10 min; carrier gas flow rate: nitrogen 1.5 ml min -1 ; Injection volume: 1.0 ml; injection environment temperature 20 ° C, record the chromatographic peak area of ​​the series of concentrations of the mixed reference gas, and use the peak area to perform linear regression on the concentration to obtain the standard curve of the two components. The sample concentration with a signal-to-noise ratio S / N value of 3 is used as the detection limit, and the sample concentration with a signal-to-noise ratio S / N value of 10 is used as the quantification limit; Randomly take appropriate amounts of two samples and inject them into the vacuum gas sampling bag, then inject them into the gas chromatograph according to the above chromatographic conditions, record the peak areas of the two components in the samples, and substitute them into the standard curve to calculate the contents of the two components.

5. The method according to claim 1, characterized in that In step 6), a plurality of samples are randomly selected and injected into a vacuum gas sampling bag as test samples, and injected into a gas chromatograph according to the chromatographic conditions under the content determination, and the chromatogram is recorded. The peak areas of 1,1-difluoro-2-chloroethylene and 1-chloro-1-fluoroethylene are substituted into the standard curve to calculate the contents of the two components, and the contents of 1,1-difluoro-2-chloroethylene and 1-chloro-1-fluoroethylene are respectively counted and analyzed by one-way variance, and the uniformity is determined by the test level p value and the comparison of the F test value and the F critical value.

6. The method according to claim 1, characterized in that In step 7), the changes in temperature and relative humidity during transportation are simulated, and the samples are placed in a constant temperature and humidity chamber at a temperature of 40°C and a relative humidity of 60%. Gas chromatography detection is performed on days 0, 5 and 10, respectively, and the peak area percentages of the two components are recorded. The classical linear model is used for judgment, that is, the monitoring time is used as the horizontal axis and the peak area percentage measurement result is used as the vertical axis for linear fitting to obtain the straight line slope b1. The t test is used for judgment. If This indicates that the slope is not significant and the stability is good; A sample was randomly selected and connected to a pressure reducing gauge with an initial pressure of 10 MPa. The gas in the bottle was released slowly and injected into the gas chromatograph at 8, 6, 4, and 2 MPa according to the chromatographic conditions for content determination. The contents and peak area percentages of 1,1-difluoro-2-chloroethylene and 1-chloro-1-fluoroethylene in the mixed reference substance at the corresponding pressures were determined. The pressure stability of the sample was investigated using the relative standard deviation (RSD) of the contents and peak area percentages of the two components at different pressures.

7. The method according to claim 1, characterized in that In step 8), the uncertainty of the content determination of the standard substance of the mixed gas of 1,1-difluoro-2-chloroethylene and 1-chloro-1-fluoroethylene is introduced by three parts: uniformity, long-term stability and value determination process. The uncertainty introduced by the value determination process is divided into two parts: one part is the uncertainty calculated by statistical methods, that is, Class A assessment of uncertainty, which is mainly the uncertainty introduced by standard curve fitting and measurement repeatability; the other part is the uncertainty assessed by non-statistical analysis method through analysis of measurement influencing factors, that is, Class B assessment of uncertainty, which is mainly the uncertainty of gas chromatography measurement.

8. The method according to claim 7, characterized in that The uncertainty introduced by uniformity is calculated according to formula (1): Where u bb is the uncertainty caused by the uniformity between units, S bb is the standard deviation between units, M between is the mean square between groups, M within is the within-group mean square, n0 is the number of repeated measurements for each unit; The uncertainty introduced by the setting process is calculated according to formula (2-4): In the formula, is the uncertainty introduced by fitting the standard working curve to obtain the content of each component in the component to be measured; S is the residual standard deviation of the peak area in the standard working curve; S xx is the residual sum of squares of mass concentration; a is the intercept of the standard working curve; b is the slope of the standard working curve; C i is the mass concentration point of the standard curve; A i is the peak area value measured at each mass concentration point; n is the number of the prepared series of standard solutions; is the average mass concentration of the standard solution; P is the number of parallel measurements of the sample; x0 is the average mass concentration of each substance in the sample solution to be tested; The uncertainty introduced by measurement repeatability is calculated according to formula (5): In the formula, is the uncertainty introduced by the measurement repeatability; S is the standard deviation of the content obtained by n measurements; n is the number of repeated measurements; The uncertainty of gas chromatography measurement is calculated according to formula (6): In the formula, u B is the uncertainty of gas chromatography; x is the content of the measured component; u GC The uncertainty of gas chromatography detection of gas substances; According to formula (7), the sources of each uncertainty component are combined to obtain the combined standard uncertainty u CRM , the expanded uncertainty is obtained by expanding the combined uncertainty, and the coverage factor is 2; 9. A standard mixed gas of 1,1-difluoro-2-chloroethylene and 1-chloro-1-fluoroethylene prepared by the method according to any one of claims 1 to 8, wherein the concentration of 1,1-difluoro-2-chloroethylene is 0.329±0.018 μg / ml, with an expansion factor k=2, and the concentration of 1-chloro-1-fluoroethylene is 0.111±0.004 μg / ml, with an expansion factor k=2, at 20°C and standard atmospheric pressure.

10. Use of the standard mixed gas of 1,1-difluoro-2-chloroethylene and 1-chloro-1-fluoroethylene as claimed in claim 9 as a reference substance for the inspection of tetrafluoroethane-related substances.

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