A method for verifying the value of a gaseous organic component solution standard substance

Abstract

This invention discloses a method for verifying the quantitative values ​​of gaseous organic component solution standard substances. The method includes preparing the solution standard substance using a syringe absorption method; using the solution standard substance as a liquid raw material, preparing a verification gas sample using a weighing method; establishing a gas chromatography analysis method; using a gas standard substance with a national certified reference material certificate as a reference standard, comparing the verification gas sample with the certified reference material, and determining the accuracy of the solution standard substance's quantitative value by comparing the relative deviation between the measured value and the nominal value; and tracing the quantitative value of the solution standard substance back to the national standard through the verification gas sample and the certified reference material. This invention solves the technical problem that existing gaseous organic component solution standard substance quantitative values ​​cannot establish a complete traceability chain, and can be used for the quantitative verification of solution standard substances such as vinyl chloride, bromomethane, chloromethane, chloroethane, trichlorofluoromethane, and dichlorodifluoromethane.

Description

Technical Field

[0001] This invention relates to the field of metrological traceability technology for standard substances, and in particular to a method for verifying the quantitative value of a gaseous organic component solution standard substance. Background Technology

[0002] Currently, the preparation of gaseous organic component solution standards (such as vinyl chloride solution standards in methanol) mainly employs methods such as syringe sampling, gas bag collection, solvent closed absorption, and solid adsorption-solvent desorption. For example, the syringe sampling method involves using an airtight syringe to collect a certain volume of gaseous vinyl chloride from a cylinder, then inserting the syringe into a collection bottle filled with methanol solvent, injecting the gas into the solvent to dissolve it, and finally converting the gas volume into mass concentration using the gas state equation pV=nRT. While this method can achieve the preparation of solution standards, its traceability chain has fundamental flaws: the metrological value depends entirely on the accurate measurement of the gas volume collected by the syringe and the precise determination of temperature and pressure parameters. However, the syringe volume measurement, temperature measurement, and pressure measurement all introduce cumulative errors, and the measurement uncertainties at each stage are difficult to systematically assess and effectively control, resulting in the inability to establish a complete traceability chain to national standards for the final metrological value. Furthermore, the accuracy of measurement values ​​can be affected by factors such as adsorption of gaseous vinyl chloride on the syringe inner wall, diffusion loss at the needle tip and collection bottle opening, operator skill level, and environmental conditions (temperature, air pressure, etc.). These factors further exacerbate the uncertainty in the traceability of solution standard substance quality values.

[0003] Research on gaseous organic component solution standard materials in my country is relatively weak, and similarly, there are no mature methods for preparing and verifying such standard materials abroad. Surveys have found that several foreign gaseous organic component solution standard materials available on the market have inaccurate metrological values, are expensive, and have long delivery cycles. Therefore, establishing a metrological verification method for gaseous organic component solution standard materials to ensure their accuracy, reliability, and traceability has become an urgent need in the fields of environmental monitoring and occupational health.

[0004] To address the aforementioned issues, this invention provides a method for verifying the metrological values ​​of gaseous organic component solution reference materials. By using a gaseous reference material that has obtained a national certified reference material certificate as a reference standard, the solution reference material to be verified is re-prepared into a gaseous sample by weighing, and then compared with the certified reference material by chromatography to establish a complete metrological traceability chain. Summary of the Invention

[0005] The purpose of this invention is to provide a method for verifying the quantitative value of a gaseous organic component solution standard.

[0006] To achieve the above objectives, the present invention is implemented according to the following technical solution: This invention includes the following steps: S1. Prepare solution standards for gaseous organic components using a gravimetric-volume method, and measure the transfer mass of the liquid components. Component purity and constant volume ,according to The mass concentration is calculated so that the mass value of the solution standard is directly traceable to the mass reference; the gaseous organic component includes at least one of vinyl chloride, bromomethane, chloromethane, chloroethane, trichlorofluoromethane, and dichlorodifluoromethane; S2. Using the solution standard substance from step S1 as the liquid raw material, prepare the gas sample for verification by weighing method, including: S2.1 Gas Cylinder Pretreatment: After heating and evacuating the aluminum alloy gas cylinder, fill it with high-purity nitrogen. Repeat the evacuation-nitrogen filling process at least 7 times, then purge it with a molecular turbopump for at least 12 hours until the vacuum level is below 1.0 × 10⁻⁶. -5 Pa; S2.2 Liquid Transfer and Weighing: The liquid raw material is transferred using an airtight syringe with a lock, and the mass difference before and after the transfer is measured using a mass comparator to obtain the mass of the liquid injected into the gas cylinder; S2.3 Gas filling and mixing: High-purity methane or high-purity nitrogen is filled into the gas cylinder as a balance gas, and the mixture is rolled and mixed for more than 4 hours to obtain the gas sample for verification. S3. Establish a gas chromatography analysis method; S4. Using nationally certified gas standard materials as reference standards, measure the gas sample used for verification and the certified gas standard materials under the same conditions, compare the relative deviations between the measured values ​​and the nominal values, and verify the accuracy of the quantitative values ​​of the solution standard materials. S5. The quantitative values ​​of the solution standard substances are verified and traced back to the national standard for gas samples and certified gas standard substances to form a traceability chain.

[0007] Preferably, the weight-volume method in step S1 includes: The sealed ampoule containing high-purity liquid organic components was weighed on a mass comparator with an accuracy of 0.01 mg to obtain m1; In a fume hood or glove box, use a microsyringe to transfer a certain amount of liquid organic component from the ampoule and inject it into a volumetric flask containing solvent that has already been weighed. Weigh the ampoule again to obtain... ; In a fume hood or glove box, use a microsyringe to transfer a certain amount of liquid organic component from an ampoule and inject it into a volumetric flask containing solvent that has already been weighed. Weigh the ampoule again and record the mass as m2. Calculate the mass of the transferred component. ; Dilute to the mark with solvent, shake well, and dispense according to... Calculate the mass concentration, where P is the purity of the component and V is the constant volume.

[0008] Preferably, when the boiling point of the liquid component is below 0°C, the transfer operation is performed in a low-temperature glove box at -10°C to -5°C, and the syringe needle is inserted below the solvent surface for slow injection.

[0009] Preferably, the passivation pretreatment of the gas cylinder in step S2.1 further includes: wrapping a constant temperature heating belt around the cylinder body, with the heating belt temperature being 60°C, while simultaneously performing rinsing with a molecular turbine pump.

[0010] Preferably, the mass comparison instrument in step S2.2 has a sensitivity of 0.01 mg or higher; and the equilibrium gas in step S2.3 has a purity ≥ 99.999%.

[0011] Preferably, the gas chromatography conditions in step S3 are as follows: a polar capillary column is used, the injection port temperature is 200-250℃, the column flow rate is 1.0-2.0 mL / min, the split ratio is 10:1-30:1, the detector temperature is 250℃, and the column oven temperature is programmed.

[0012] Preferably, the nationally certified gas standard material mentioned in step S4 includes GBW(E)082654 nitrogen-vinyl chloride gas standard material.

[0013] Preferably, the criterion for determining the accuracy of the measurement value in step S4 is: the relative deviation of the measured value of the gas sample used for verification from the nominal value of the certified reference material is within ±5%, and the quality value of the solution reference material is determined to be accurate and reliable.

[0014] Preferably, the uncertainty of the traceability chain in step S5 is expressed as:

[0015] in To verify the standard uncertainty introduced by the gas sample preparation process, The standard uncertainty introduced for gas chromatography analysis The standard uncertainty introduced for the measurement comparison and verification process.

[0016] Secondly, the method is used for the quantitative verification of standard substances of vinyl chloride, bromomethane, chloromethane, chloroethane, trichlorofluoromethane, and dichlorodifluoromethane solutions.

[0017] The beneficial effects of this invention are: This invention provides a method for verifying the quantitative value of a gaseous organic component solution standard. Compared with the prior art, this invention has the following technical advantages: This invention is the first to propose a method for comparison and verification using nationally certified gaseous reference materials as reference standards, by re-preparing solutions into gaseous samples. This solves the technical problem of the inability to establish a complete traceability chain for the mass values ​​of existing gaseous organic component solution reference materials. The gaseous samples used for verification are prepared by weighing, and their mass values ​​are traceable to the weighing results of a mass comparator. The mass difference before and after syringe transfer is accurately measured using a high-precision mass comparator, ensuring the accuracy of the sample preparation process. A gaseous reference material with a nationally certified reference material certificate (such as GBW(E)082654 nitrogen-containing vinyl chloride gas) is used. Using a gaseous reference material as a reference standard, the value of the solution reference material is traced back to the national certified gas reference material through the prepared gas sample, and finally to the national metrological standard, forming a complete and closed metrological traceability chain. It is applicable to the verification of the values ​​of various gaseous organic components (including vinyl chloride, bromomethane, chloromethane, chloroethane, trichlorofluoromethane, dichlorodifluoromethane, etc.) solution reference materials, and has good versatility and scalability. The method is stable, reliable, and highly repeatable, and can provide a reliable metrological traceability basis for quality control and method validation in fields such as environmental monitoring, occupational health, and natural gas analysis. Attached Figure Description

[0018] Figure 1 This is a flowchart illustrating the steps of a method for verifying the quantitative value of a gaseous organic component solution standard substance according to the present invention. Figure 2 This is a schematic diagram of a traceability chain in one of the embodiments of this specification. Detailed Implementation

[0019] The present invention will be further described below through specific embodiments. The illustrative embodiments and descriptions herein are used to explain the present invention, but are not intended to limit the present invention.

[0020] The present invention provides a method for verifying the quantitative value of a gaseous organic component solution standard substance, comprising the following steps: like Figure 1 As shown, this embodiment includes the following steps: Example 1: Quantitative verification of vinyl chloride solution standard in methanol S1. Preparation of standard reference material for vinyl chloride solution in methanol The laboratory temperature is kept constant at 20℃±0.5℃, and the relative humidity is ≤50%. Take an ampoule with a safety puncture valve containing high-purity liquefied vinyl chloride (purity ≥99.9%, verified by gas chromatography area normalization method) and pre-cool it to -10℃ in a low-temperature refrigerator before use. Remove the pre-cooled ampoule, quickly wipe off any water droplets on the outer wall, and weigh it using an XP205 mass comparator (sensitivity 0.01 mg). After the reading stabilizes, record the mass as m1 = 15.6789 g. In a fume hood, connect the ampoule mouth to a micropipette with a PTFE sealing ring. Insert the pipette tip below the liquid level in a 200 mL stoppered volumetric flask pre-filled with approximately 150 mL of chromatographic grade methanol. Slowly open the ampoule valve and transfer approximately 0.5 mL of liquid vinyl chloride (approximately 0.45 g) into the volumetric flask. Immediately stopper the flask and seal the mouth with methanol to prevent evaporation. Weigh the ampoule and remaining contents back onto the balance and record the mass as m2 = 15.2289 g. Calculate the mass of the transferred liquid vinyl chloride Δm = m1 - m2 = 0.4500 g. Dilute to the 200 mL mark with chromatographic grade methanol, shake thoroughly for 10 min, allow to stand for equilibration for 2 h, and then dispense into 2 mL brown ampoules using a filling machine. Store at -18 °C for later use. Calculate the initial concentration value according to the mass concentration formula. ,in For constant volume, For the mass of liquid vinyl chloride transferred, For component purity; This step uses the gravimetric-volume method, whose values ​​are directly traceable to the national mass standard (kilogram) and the weighing results of the mass comparator. This completely avoids the uncertainties caused by syringe volume readings, environmental temperature and pressure fluctuations, and adsorption on the inner wall, providing an accurate and reliable initial concentration standard for subsequent value verification.

[0021] S2. Preparation of gas samples for verification Aluminum alloy gas cylinders with specially passivated inner walls are selected. Cylinder pretreatment involves wrapping a constant-temperature heating belt around the cylinder body, setting the heating belt temperature to 60℃, and then filling the heated, dried, and vacuumed cylinder with high-purity nitrogen at a certain pressure, followed by vacuuming (vacuum degree 1.0 × 10⁻⁶). -2 (Pa), repeated 7 times; then purged with a molecular turbopump for more than 12 hours (vacuum degree <1.0×10). -5 (Pa) ready for use; The gas sample for verification was prepared by weighing: In a nitrogen glove box, based on the saturated vapor pressure of vinyl chloride in the solution standard, approximately 0.5 mL of the vinyl chloride solution standard prepared in step S1 was drawn using a syringe with a lock and good airtightness. The mass difference before and after the transfer was quickly and accurately weighed using an XP205 mass comparator (sensitivity 0.01 mg), and the mass of the liquid sample injected into the gas cylinder was calculated. The liquid sample was injected into the pretreated gas cylinder, and then high-purity methane (5N) was added as a balance gas to a pressure of 5 MPa. The gas cylinder was placed on a mixing device and rolled for more than 4 hours to obtain the vinyl chloride gas sample for verification. S3. Establishment of chromatographic analysis methods Analysis was performed using gas chromatography-mass spectrometry (GC-MS). The chromatographic conditions were as follows: VF-624MS capillary column (60m × 0.25mm × 1.4μm); injection port temperature 200℃; carrier gas: helium; constant column flow rate 1.0 mL / min. -1 Split ratio 30:1; injection volume 1 μL; column temperature program: initial column temperature 45℃, hold for 1 min, then increase at 10℃·min. -1 Heat to 100℃ and hold for 3 min; use 1,2-dichloroethylene as internal standard; mass spectrometry conditions: electron impact ion source, ion source temperature 230℃; quadrupole temperature 150℃; selected ions (m / z) 62, 61, 27, 96; Under these conditions, the target peak of vinyl chloride is well separated without interference; S4. Measurement Comparison Verification The national certified reference material GBW(E)082654, vinyl chloride gas in nitrogen (nominal concentration 100 μmol / mol, relative expanded uncertainty 2%, k=2), was used as the reference standard. Under the same chromatographic analysis conditions, the peak areas of the certified reference material and the verification gas sample prepared in step S2 were measured and recorded. A standard curve was plotted using certified reference materials, and the concentration of vinyl chloride in the gas sample used for verification was calculated. In this embodiment, the measured value of the gas sample used for verification was 98.7 μmol / mol, and the relative deviation from the nominal value of 100 μmol / mol of the certified reference material was -1.3%, which is within the judgment standard of ±5%. Therefore, the mass value of the vinyl chloride solution standard material in methanol prepared in step S1 is accurate and reliable. S5. Establishment of a traceability chain This embodiment successfully established a link between the value of the vinyl chloride solution standard in methanol and the national certified standard material GBW(E)082654 through the verification gas sample. The traceability chain is as follows: National Quality Standard → GBW(E)082654 Vinyl Chloride Gas Standard Material in Nitrogen → Vinyl Chloride Gas Sample for Verification → Vinyl Chloride Solution Standard Material in Methanol, thus achieving complete metrological traceability.

[0022] Example 2: Quantitative verification of the standard substance of bromomethane solution in methanol S1. Preparation of standard reference material of bromomethane solution in methanol The laboratory temperature is kept constant at 20℃±0.5℃. Take a pressure-resistant sealed bottle containing high-purity liquefied bromomethane (purity ≥99.5%, purity certificate provided by the supplier) and place it in a -5℃ low-temperature circulating water bath to cool it for 30 minutes to reduce the vapor pressure inside the bottle and reduce flash evaporation loss during transfer. After cooling, the sealed bromomethane vial was quickly transferred to the balance room. The entire apparatus was weighed using an XP205 mass comparator, and the mass was recorded as m1 = 20.1234 g. Inside the fume hood, the outlet of the sealed vial was connected to a calibrated, airtight microsyringe with a Luer lock tip. The septum at the vial opening was punctured, and approximately 0.4 mL of liquid bromomethane was quickly drawn. The syringe needle was then quickly inserted below the liquid level in a 200 mL volumetric flask pre-filled with approximately 180 mL of chromatographic grade methanol. The liquid was slowly pushed in, and the outer wall of the syringe needle was immediately rinsed with methanol. Weigh the remaining contents of the sealed bromomethane vial again and record the mass as m2 = 19.7234 g. Calculate the transferred bromomethane mass Δm = m1 - m2 = 0.4000 g; dilute to the 200 mL mark with chromatographic grade methanol, mix thoroughly by inverting 30 times, let stand for 1 hour, and then dispense into 2 mL brown ampoules. Store at -18 °C for later use.

[0023] Calculate the initial concentration value (volume V = 0.200 L) according to the mass concentration formula: ; This step uses the gravimetric-volume method, whose values ​​are directly traceable to the national mass standard (kilogram) and the weighing results of the mass comparator. This completely avoids the uncertainties caused by syringe volume readings, environmental temperature and pressure fluctuations, and adsorption on the inner wall, providing an accurate and reliable initial concentration standard for subsequent value verification. S2. Preparation of gas samples for verification An aluminum alloy gas cylinder with a specially passivated inner wall was selected, and the cylinder was pretreated according to the method in step S2 of Example 1. In a nitrogen glove box, a syringe with a lock and good airtightness was used to draw the standard substance of bromomethane solution in methanol prepared in step S1. The mass difference before and after the transfer of the syringe was accurately weighed using a high-precision mass comparator, and the mass of the liquid sample injected into the gas cylinder was calculated. The liquid sample was injected into the pretreated gas cylinder, and then high-purity methane (5N) was added as a balance gas. The gas cylinder was placed on a mixing device and rolled for more than 4 hours to obtain the bromomethane gas sample for verification. S3. Establishment of chromatographic analysis methods Analysis was performed using gas chromatography-mass spectrometry (GC-MS). The chromatographic conditions were as follows: VF-624MS capillary column (60m × 0.25mm × 1.4μm); injection port temperature 200℃; carrier gas: helium; constant column flow rate 1.0 mL / min. -1 Split ratio 30:1; injection volume 1 μL; column temperature program: initial column temperature 40℃, hold for 2 min, then increase at 8℃·min. -1 Heat to 120℃ and hold for 5 minutes; S4. Measurement Comparison Verification Using a nationally certified bromomethane gas reference material as a reference standard, the certified reference material and the verification gas sample prepared in step S2 were measured under the same chromatographic analysis conditions. In this embodiment, the relative deviation of the measured value of the verification gas sample from the nominal value of the certified reference material was +2.3%, which is within the ±5% judgment standard. Therefore, the quality value of the bromomethane solution reference material in methanol prepared in step S1 is accurate and reliable. S5. Establishment of a traceability chain This embodiment successfully established a link between the value of the bromomethane solution standard in methanol and the nationally certified gas standard through a verification gas sample, thus achieving complete metrological traceability.

[0024] Example 3: Quantitative Verification of Standard Material for Chloroethane Solution in Methanol S1. Preparation of standard reference material for chloroethane solution in methanol The laboratory temperature is kept constant at 20℃±0.5℃. Take a steel cylinder with a sampling valve containing high-purity liquefied chloroethane (purity ≥99.9%) and connect the cylinder to a section of stainless steel capillary tube. Insert the end of the capillary tube below the liquid surface of a 200mL volumetric flask containing approximately 150mL of chromatographic grade methanol. Open the sampling valve of the steel cylinder and slowly release approximately 0.6mL of liquid chloroethane (relying on the self-generated pressure inside the cylinder). After the liquid flows into the volumetric flask, immediately close the valve and quickly rinse the outer wall of the capillary tube with methanol. The differential weighing method was used: Before sampling, the entire cylinder and connecting device were weighed on an XP205 mass comparator, and the mass was recorded as m1 = 35.5678 g. After sampling, the entire cylinder and connecting device were weighed again, and the mass was recorded as m2 = 35.1178 g. The mass of chloroethane transferred was calculated as Δm = m1 - m2 = 0.4500 g. Dilute to 200 mL with chromatographic grade methanol, shake well and let stand for 30 min, then dispense into 2 mL brown ampoules and store at -18 °C for later use. Calculate the initial concentration value (volume V = 0.200 L) according to the mass concentration formula: ; This step uses the gravimetric-volume method, whose values ​​are directly traceable to the national mass standard (kilogram) and the weighing results of the mass comparator. This completely avoids the uncertainties caused by syringe volume readings, environmental temperature and pressure fluctuations, and adsorption on the inner wall, providing an accurate and reliable initial concentration standard for subsequent value verification. S2. Preparation of gas samples for verification The method for pretreatment of gas cylinders and preparation of gas samples for verification is the same as step S2 in Example 1; using the standard substance of methanol-chloroethane solution prepared in step S1 as liquid raw material, the mass of the transferred liquid sample is accurately weighed by a high-precision mass comparator, injected into the pretreated gas cylinder, and high-purity methane is introduced as a balance gas. After mixing, the chloroethane gas sample for verification is obtained. S3. Establishment of chromatographic analysis methods Analysis was performed using gas chromatography with flame ionization detector (GC-FID). Chromatographic conditions: RTX-Stabilwax column (60 m × 320 μm × 1.0 μm), injection port temperature 250 °C, column flow rate 2.0 mL / min, split ratio 10:1. Column oven temperature program: 40 °C for 5 min, then increased to 180 °C at 8 °C / min and held for 6 min. FID detector temperature 250 °C, air 400 mL / min, hydrogen 35 mL / min, and make-up gas 20 mL / min. S4. Measurement Comparison Verification Using a nationally certified chloroethane gas standard as a reference standard, the certified standard and the verification gas sample prepared in step S2 were measured under the same chromatographic analysis conditions. In this embodiment, the relative deviation of the measured value of the verification gas sample from the nominal value of the certified standard was -2.8%, which is within the ±5% judgment standard. Therefore, the mass value of the methanol chloroethane solution standard prepared in step S1 is accurate and reliable. S5. Establishment of a traceability chain This embodiment successfully established a link between the value of the standard reference material for chloroethane solution in methanol and the nationally certified gas standard reference material through the verification gas sample, thus achieving complete metrological traceability.

[0025] The following experiments illustrate the beneficial effects of this invention: The procedure for the following experiment is as follows: Figure 1 As shown: Experiment Example 1: Investigation of the impact of gas cylinder pretreatment methods on verification results The experiment investigated the effect of different gas cylinder pretreatment methods on the preparation of gas samples for verification. Three pretreatment methods were set up: gas cylinder #1 was used directly without pretreatment; gas cylinder #2 underwent only simple nitrogen replacement (vacuuming and nitrogen filling repeated 3 times); gas cylinder #3 was pretreated according to the method of step S2.1 of this invention (heating and vacuuming and nitrogen filling repeated 7 times, and molecular turbopump purging at 60°C for more than 12 hours). Gas cylinders using three different pretreatment methods were used to prepare vinyl chloride gas samples for verification according to the method in Example 1. The samples were then compared and verified with the standard reference material for vinyl chloride gas in nitrogen (GBW(E)082654). The results are shown in Table 1. Table 1. Impact of different gas cylinder pretreatment methods on verification results

[0026] Experimental results show that the pretreatment method of the gas cylinder has a significant impact on the quantitative value of the gas sample used for verification. Impurities and moisture remaining on the inner wall of the gas cylinder without sufficient pretreatment can adsorb the target components, leading to lower measured values. The fine pretreatment method in step S2.1 of this invention, which uses a heating band at a constant temperature of 60°C combined with a molecular turbopump for long-term rinsing, can effectively remove impurities from the inner wall of the gas cylinder, ensuring the accurate and reliable quantitative value of the gas sample used for verification.

[0027] Experiment Example 2: Method Repeatability Examination Following the method in Example 1, five batches of vinyl chloride solution standard material in methanol were independently prepared, and the values ​​of each batch were verified according to the method of this invention. Each batch of verification was measured in triplicate using gas samples, and the relative standard deviation (RSD) of the measured values ​​was calculated. The results are shown in Table 2. Table 2 Repeatability test data for measurement verification methods

[0028] Experimental results show that the quantitative verification results of the five batches of solution standard substances are all within the ±5% judgment standard, and the relative standard deviation (RSD) between batches is ≤0.30%, indicating that the method of the present invention has excellent repeatability and reliability. Experiment Example 3: Validation of Applicability at Different Concentration Levels Following the method in Example 1, standard substances of vinyl chloride solution in methanol with theoretical concentrations of 100 mg / L, 500 mg / L, and 1000 mg / L were prepared respectively. The values ​​were verified according to the method of the present invention, and the results are shown in Table 3. Table 3 Validation results at different concentration levels

[0029] Experimental results show that the method of the present invention can effectively verify the accuracy of the concentration values ​​of the solution standard substance at different concentration levels, and has a good concentration applicability range.

[0030] Experiment Example 4: Uncertainty Assessment of the Traceability Chain The composite standard uncertainty of the traceability chain of this invention is evaluated according to the following formula:

[0031] in To verify the standard uncertainty introduced in the gas sample preparation process (mainly from the weighing uncertainty of the mass comparator and the purity uncertainty of the equilibrium gas). The standard uncertainty introduced for gas chromatography analysis (mainly from the repeatability of peak area measurement and the uncertainty of standard curve fitting). Standard uncertainty introduced for the measurement comparison and verification process; Taking the vinyl chloride verification results of Example 1 as an example, the uncertainty components and synthesis results are shown in Table 4; Table 4 Uncertainty Assessment Results of the Traceability Chain

[0032] Experimental results show that the relative expansion uncertainty of the traceability chain established in this invention is less than 3%, which can meet the metrological traceability requirements for the verification of the mass value of gaseous organic component solution standard substances.

[0033] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for verifying the quantitative value of a gaseous organic component solution standard, characterized in that, Includes the following steps: S1. Prepare solution standards for gaseous organic components using a gravimetric-volume method, and measure the transfer mass of the liquid components. Component purity and constant volume ,according to The mass concentration is calculated so that the mass value of the solution standard is directly traceable to the mass reference; the gaseous organic component includes at least one of vinyl chloride, bromomethane, chloromethane, chloroethane, trichlorofluoromethane, and dichlorodifluoromethane; S2. Using the solution standard substance from step S1 as the liquid raw material, prepare the gas sample for verification by weighing method, including: S2.1 Gas Cylinder Pretreatment: After heating and evacuating the aluminum alloy gas cylinder, fill it with high-purity nitrogen. Repeat the evacuation-nitrogen filling process at least 7 times, then purge it with a molecular turbopump for at least 12 hours until the vacuum level is below 1.0 × 10⁻⁶. -5 Pa; S2.2 Liquid Transfer and Weighing: The liquid raw material is transferred using an airtight syringe with a lock, and the mass difference before and after the transfer is measured using a mass comparator to obtain the mass of the liquid injected into the gas cylinder; S2.3 Gas filling and mixing: High-purity methane or high-purity nitrogen is filled into the gas cylinder as a balance gas, and the mixture is rolled and mixed for more than 4 hours to obtain the gas sample for verification. S3. Establish a gas chromatography analysis method; S4. Using nationally certified gas standard materials as reference standards, measure the gas sample used for verification and the certified gas standard materials under the same conditions, compare the relative deviations between the measured values ​​and the nominal values, and verify the accuracy of the quantitative values ​​of the solution standard materials. S5. The quantitative values ​​of the solution standard substances are verified and traced back to the national standard for gas samples and certified gas standard substances to form a traceability chain.

2. The method for verifying the quantitative value of a gaseous organic component solution standard substance according to claim 1, characterized in that, The weight-volume method described in step S1 includes: The sealed ampoule containing high-purity liquid organic components was weighed on a mass comparator with an accuracy of 0.01 mg to obtain m1; In a fume hood or glove box, use a microsyringe to transfer a certain amount of liquid organic component from the ampoule and inject it into a volumetric flask containing solvent that has already been weighed. Weigh the ampoule again to obtain... ; In a fume hood or glove box, use a microsyringe to transfer a certain amount of liquid organic component from an ampoule and inject it into a volumetric flask containing solvent that has already been weighed. Weigh the ampoule again and record the mass as m2. Calculate the mass of the transferred component. ; Dilute to the mark with solvent, shake well, and dispense according to... Calculate the mass concentration, where P is the purity of the component and V is the constant volume.

3. The method for verifying the quantitative value of a gaseous organic component solution standard substance according to claim 1, characterized in that, When the boiling point of the liquid component is below 0°C, the transfer operation is carried out in a low-temperature glove box at -10°C to -5°C, and the syringe needle is inserted below the solvent surface and injected slowly.

4. The method for verifying the quantitative value of a gaseous organic component solution standard substance according to claim 1, characterized in that, The passivation pretreatment of the gas cylinder in step S2.1 also includes: wrapping a constant temperature heating belt around the cylinder body, with the heating belt temperature at 60°C, while simultaneously performing rinsing with a molecular turbine pump.

5. The method for verifying the quantitative value of a gaseous organic component solution standard substance according to claim 1, characterized in that, The mass comparison instrument in step S2.2 has a sensitivity of 0.01 mg or higher; the equilibrium gas in step S2.3 has a purity ≥ 99.999%.

6. The method for verifying the quantitative value of a gaseous organic component solution standard substance according to claim 1, characterized in that, The gas chromatography conditions described in step S3 are as follows: a polar capillary column is used, the injection port temperature is 200-250℃, the column flow rate is 1.0-2.0 mL / min, the split ratio is 10:1-30:1, the detector temperature is 250℃, and the column oven temperature is programmed.

7. The method for verifying the quantitative value of a gaseous organic component solution standard substance according to claim 1, characterized in that, The nationally certified gas reference material mentioned in step S4 includes GBW(E)082654 nitrogen-containing vinyl chloride gas reference material.

8. The method for verifying the quantitative value of a gaseous organic component solution standard substance according to claim 1, characterized in that, The criterion for determining the accuracy of the measured value in step S4 is: if the relative deviation of the measured value of the gas sample used for verification relative to the nominal value of the certified reference material is within ±5%, the quality value of the solution reference material is determined to be accurate and reliable.

9. The method for verifying the quantitative value of a gaseous organic component solution standard substance according to claim 1, characterized in that, The uncertainty of the traceability chain mentioned in step S5 is expressed as: in To verify the standard uncertainty introduced by the gas sample preparation process, The standard uncertainty introduced for gas chromatography analysis The standard uncertainty introduced for the measurement comparison and verification process.

10. A method for verifying the quantitative value of a gaseous organic component solution standard substance according to any one of claims 1 to 9, characterized in that, The method is used to verify the quantitative values ​​of standard substances of vinyl chloride, bromomethane, chloromethane, chloroethane, trichlorofluoromethane, and dichlorodifluoromethane solutions.

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