Benzene series solid standard substance as well as preparation method and application thereof

Abstract

The invention discloses a benzene series solid standard substance as well as a preparation method and application thereof, and relates to the technical field of chemical standard samples. The invention provides a benzene series solid standard substance. The benzene series solid standard substance comprises 75-98 parts of gel and 2-25 parts of a benzene series target object, the melting point of the gel is 60-100 DEG C. According to the invention, the specific type of gel is selected to adsorb the benzene series, so that the preparation of the solid standard substance capable of slowly releasing the benzene series is realized, the solid standard substance not only accords with the actual volatilization process in a use scene, but also exists in a solid form, and the transportation convenience, safety and stability are realized.

Description

Technical Field

[0001] The present invention relates to the technical field of chemical standard samples, in particular to a benzene series solid standard substance and a preparation method and application thereof. Background Art

[0002] In recent years, with the rapid development of the automotive industry, the requirements for in-vehicle air quality control have become increasingly stringent. Volatile organic compounds (VOCs), particularly benzene series (including benzene, toluene, xylene, ethylbenzene, and styrene), released when heated from automotive interior materials (such as plastics, leather, PVC, and foam), have become a key factor affecting in-vehicle environmental safety. Benzene series not only cause acute symptoms such as headaches and nausea, but long-term exposure can also cause cancer. Therefore, accurately measuring their concentration is crucial for assessing in-vehicle air quality.

[0003] At present, the main technical bottlenecks of standard substances for the detection of benzene series at home and abroad are as follows: (1) Physical form mismatch: Most existing standard substances are liquid (such as benzene series dissolved in organic solvents) or compressed gases, which are significantly different from the solid-state slow-release characteristics of benzene series in actual interior materials. Liquid standards are easily affected by factors such as temperature and shock during transportation, and there is a risk of leakage; gas standards require high-pressure sealing, which is costly and complicated to operate. (2) Release mechanism deviation: The mainstream detection method relies on Tenax adsorption tube thermal desorption technology to quickly release benzene series at high temperature, but this process cannot simulate the slow release behavior of materials in actual scenarios, resulting in errors between the test results and the real environment. (3) Low production efficiency: Traditional preparation processes, such as patent CN106248839A, disclose a method for preparing a standard substance for detecting aromatic hydrocarbon compounds in workplace air. This method dissolves benzene series compounds in a carbon disulfide solution, and uses a dynamic gas distribution system or a syringe to inject the carbon disulfide solution into activated carbon sealed in a cylindrical hard glass. The content of benzene series compounds is controlled by the injection time. This method requires precise control of time and flow rate, requires a lot of manual intervention, and has a long production cycle, making it difficult to meet the needs of large-scale industrialization.

[0004] Therefore, developing a solid-state BTEX standard substance that is consistent with the actual material release behavior, has high stability, and is easy to transport and produce has become a technical problem that the industry urgently needs to solve. Summary of the Invention

[0005] Based on this, the purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and provide a solid standard substance of benzene series, a preparation method and application thereof, which can achieve slow and controllable release of benzene series and meet the high-precision requirements of automobile interior material testing.

[0006] To achieve the above object, the technical solution adopted by the present invention is: a solid standard substance of benzene series, including 75-98 parts of gel and 2-25 parts of benzene series target substance; the melting point of the gel is 60-100°C.

[0007] The present invention provides a solid reference material for benzene series compounds. This product uses gels with different melting points as a base material to construct a solid reference material containing benzene series compounds. This product not only utilizes the slow release technology of the gel to simulate the volatilization process in actual scenarios, but also can achieve a wide range of benzene series loading while ensuring uniformity. It has high stability and strong safety, making it very suitable for the detection of benzene series compounds and instrument calibration in the automotive industry.

[0008] Preferably, in the benzene series solid standard substance, the total mass content of the gel and the benzene series target substance is ≥90wt%.

[0009] Preferably, in the benzene series solid standard substance, the weight proportion of the gel is one of or any two of 75 parts, 80 parts, 82 parts, 85 parts, 88 parts, 90 parts, 92 parts, 95 parts, and 98 parts, the weight proportion of the benzene series target substance is one of or any two of 2 parts, 5 parts, 8 parts, 10 parts, 12 parts, 15 parts, 18 parts, 20 parts, and 25 parts, and the melting point of the gel is one of or any two of 60°C, 65°C, 78°C, 80°C, 82°C, 85°C, 90°C, 95°C, and 100°C.

[0010] Preferably, the BTEX target includes a BTEX compound and a solvent.

[0011] Preferably, the concentration of the benzene series compounds in the benzene series solid standard substance is ≥5 μg / mL; more preferably, the concentration of the benzene series compounds in the benzene series solid standard substance is 10-1000 μg / mL.

[0012] Based on the unique design of the contents of the solid standard substance of benzene series compounds described in the present invention, the loading amount of benzene series compounds in this product can be controlled within a wide range, making it very suitable for real-time calibration of instruments such as those used for detecting benzene series content.

[0013] It should be noted that the test method for the concentration of benzene series compounds in the benzene series solid standard substance of the present invention is:

[0014] (1) Establishment of standard curve: Different gels were heated at different temperatures and times to release benzene series compounds. The standard compounds were drawn into the TENAX tube using a sampling pump at a flow rate of 200 ml / min. The gas was collected for 5 minutes, i.e., 1 L of gas. The gas was then tested on a TD-GCMS.

[0015] (2) Concentration test: The volume of the solid standard substance of the benzene series is V1 (ml) when tested using the drainage method, and the test method of ISO12219-2:2012 is referred to. The heating temperature is set or selected according to the melting point of the gel. The reading of the test instrument is C (μg / L) when using a 10L bag. The volume of the bag is 1L, and it is assumed that the gas is evenly mixed. The concentration C2 of the benzene series compound is obtained by calculation. The calculation formula is C2 = 10C / (V1) (μg / mL).

[0016] Preferably, the melting point of the gel is 60-70°C.

[0017] Preferably, the melting point test method of the gel is the glass tube method, which is as follows: fill a glass tube with an inner diameter of 1 mm with a gel sample, place it in a water bath and heat it from 25°C, record the temperature every 1°C, and when the gel sample is completely melted, mark the temperature at this time as the melting point of the gel.

[0018] Preferably, the gel is at least one of agar gel, carrageenan, chitosan gel and agarose gel.

[0019] Specifically, the agar impression gel is a network structure formed by agar, water, soluble additives, etc.; the soluble additives include at least one of fillers, plasticizers, preservatives, and regulators; the filler includes at least one of diatomaceous earth and talc, the plasticizer includes glycerol, and the regulator includes buffer salt.

[0020] Preferably, the gel is a mixture of agar impression gel and carrageenan; preferably, the weight ratio of the agar impression gel to carrageenan is 1:(0.3-0.8); further preferably, the weight ratio of the agar impression gel to carrageenan is 1:(0.5-0.7).

[0021] Preferably, the benzene series compound includes at least one of benzene, toluene, xylene, ethylbenzene and styrene, and the solvent is methanol.

[0022] Preferably, the BTEX compounds are mixed with methanol solvent to form the BTEX target product.

[0023] To facilitate processing, those skilled in the art can prepare the benzene series compound into a benzene series target compound in the form of a solution and then prepare a solid standard substance, or they can introduce the benzene series compound by direct addition, as long as it does not affect the uniformity and stability of the obtained product.

[0024] Preferably, the components of the benzene series solid standard substance further include 1-2 parts of functional additives.

[0025] More preferably, the functional additive includes at least one of an antioxidant, an antistatic agent, an antibacterial agent, and an anti-ultraviolet agent.

[0026] According to actual needs, those skilled in the art may add various functional additives without affecting the homogeneity and stability of the standard substance described in the present invention. For example, in order to prevent the product from being affected by static electricity during transportation and storage, those skilled in the art may add antistatic agents to the product; in order to make the product have a better antioxidant effect during storage, those skilled in the art may add antioxidants to the product.

[0027] In addition, the present invention provides a preparation method of the benzene series solid standard substance, which is as follows: heating and melting the gel and the benzene series target substance and mixing them evenly, cooling them to 25°C or below, and solidifying the gel to obtain the benzene series solid standard substance.

[0028] Preferably, the gel and the target benzene series product are heated to melt, and the temperature is heated to 5-10° C. higher than the melting point of the gel.

[0029] Furthermore, the present invention provides an application of the BTEX solid reference material in the automotive field. Specifically, the present invention provides an application of the BTEX solid reference material in detecting BTEX content in automobiles and in evaluating and calibrating BTEX content testing equipment for samples.

[0030] Compared to existing technologies, the present invention offers the following advantages: It provides a solid reference material for BTEX compounds, constructed using gels with different melting points as a substrate. This product not only utilizes the slow release technology of the gel to simulate the volatilization process in real-world scenarios, but also enables a wide range of BTEX loadings while ensuring uniformity. Its high stability and safety make it ideally suited for BTEX compound detection and instrument calibration in the automotive industry. DETAILED DESCRIPTION

[0031] In order to better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below with reference to specific embodiments. Its purpose is to understand the content of the present invention in detail, rather than to limit the present invention. All other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. Unless otherwise specified, the experimental reagents and instruments designed for the implementation and comparative examples of the present invention are all commonly used ordinary reagents and instruments, which can be obtained from commercial channels. In the implementation and comparative examples, the experimental methods used are all conventional methods unless otherwise specified; and unless otherwise specified, the raw materials used in parallel experiments are the same batch of raw materials.

[0032] The raw materials used in the present invention are now further described, but are not limited to the following raw materials. Unless otherwise specified, the component raw materials used in the embodiments and comparative examples of the present invention are all commercially available raw materials, and the component raw materials used in each parallel experiment are all the same.

[0033] Benzene series target compound 1 was a homemade product. Commercially available analytical grade toluene and commercially available analytical grade methanol were mixed and stirred at room temperature for 10 minutes. By adjusting the mass ratio of Benzene series to methanol, different concentrations of Benzene series target compounds were obtained.

[0034] Benzene series target compound 2 is a homemade product. Commercially available analytical grade styrene and commercially available analytical grade methanol were mixed and stirred at room temperature for 10 minutes. By adjusting the mass ratio of Benzene series to methanol, different concentrations of Benzene series target compounds were obtained.

[0035] Benzene series target 3 is a homemade product. Commercially available analytical grade toluene, xylene, and commercially available analytical grade methanol were mixed and stirred at room temperature for 10 minutes. By adjusting the mass ratio of benzene series to methanol, different concentrations of benzene series target were obtained. The weight ratio of the commercially available analytical grade toluene to xylene was 1:1.

[0036] Benzene series target compound 4, commercial analytical grade toluene;

[0037] Gel 1: gelatin, melting point 35°C, purchased from Sangon Biotechnology;

[0038] Gel 2: agar impression gel, melting point 65 °C, purchased from Baixing Biotechnology;

[0039] Gel 2′: agar impression gel, melting point 65°C, purchased from Huanhai Biotechnology;

[0040] Gel 3: carrageenan, melting point 65 °C, purchased from Sangon Biotechnology;

[0041] Gel 4: Chitosan gel, melting point 78 °C, purchased from Sangon Biotechnology;

[0042] Gel 5: agarose gel, melting point 95 °C, purchased from Baixing Biotechnology;

[0043] Gel 6: Homemade, Gel 2 and Gel 3 are compounded, the weight ratio of Gel 2 to Gel 3 is 1:0.6; Gel 2 is agar impression gel with a melting point of 65°C, purchased from Baixing Biotechnology; Gel 3 is carrageenan with a melting point of 65°C, purchased from Shenggong Biotechnology;

[0044] Gel 7: Homemade, gel 2' and gel 3 were compounded, the weight ratio of gel 2' to gel 3 was 1:0.5; gel 2' was agar impression gel with a melting point of 65°C, purchased from Huanhai Biotechnology; gel 3 was carrageenan with a melting point of 65°C, purchased from Shenggong Biotechnology.

[0045] Examples and Comparative Examples

[0046] The present invention provides an embodiment of a benzene series solid standard substance and a preparation method thereof. The components of the benzene series solid standard substance are shown in Table 1. The difference between each comparative example and the embodiment is only the type and ratio of the components, as shown in Table 1.

[0047] The preparation method of the benzene series solid standard substance is as follows: heating and melting the gel and the benzene series target substance and then mixing them evenly, cooling them to 25° C. or below, and solidifying the gel to obtain the benzene series solid standard substance.

[0048] Table 1

[0049]

[0050]

[0051]

[0052] In order to verify the performance of the products of the present invention, the products prepared in each embodiment and comparative example were subjected to the following performance tests. The specific steps are as follows:

[0053] Homogeneity test: According to CNAS-GL003-2018 "Guidelines for the Evaluation of Homogeneity and Stability of Proficiency Testing Samples", one-way ANOVA is used to test the homogeneity between samples. The specific implementation plan is as follows: 15 prepared standards are randomly selected, and each standard is tested twice in parallel under repeated conditions. The F variance test value is calculated. If F < F with degrees of freedom (f1, f2) and a given significance level α (usually α = 0.05), the F variance test value is calculated. α (f1, f2), it indicates that there is no significant difference within and between samples, and the samples are uniform.

[0054] Stability test: According to CNAS-GL003-2018 "Guidelines for the Evaluation of Uniformity and Stability of Proficiency Testing Samples", the stability of the sample is tested by the consistency between the two average values ​​in the t-test method. The uniformity test data is used as one of the average values. After an interval of 3 months, 10 samples are randomly selected from the samples that have completed the uniformity test. The test is carried out in the same way as the uniformity test conditions. Each sample is measured twice in parallel under repeated conditions, and the average value of the measurement is calculated. The t value is calculated by the average value and standard deviation of the two test measurement data. If t is less than the significance level α (usually α = 0.05) and the degrees of freedom are n1+n2-2, the critical value t α(n1+n2-2) , there is no significant difference between the two mean values.

[0055] Part of the uniformity and stability test data of the benzene series solid standard substances of Example 1, Example 7, and Example 13 is presented in Table 2-7.

[0056] Specifically, taking the 50 μg / mL solid standard substance of benzene series prepared in Example 1 as an example, the mouth of the container of the solid standard substance of benzene series prepared in Example 1 was opened, and the gel network structure was completely destroyed by heating until it melted, so that the benzene series was completely released. At the same time, the test was carried out with reference to the ISO 12219-2:2012 method. The test results are shown in Table 2-3.

[0057] Taking the 100 μg / mL solid standard substance of benzene series prepared in Example 7 as an example, the mouth of the container of the solid standard substance of benzene series prepared in Example 7 was opened, and the gel network structure was completely destroyed by heating until it melted, so that the benzene series was completely released. At the same time, the test was carried out with reference to the ISO 12219-2:2012 method. The test results are shown in Tables 4-5.

[0058] Taking the 20 μg / mL solid standard substance of benzene series prepared in Example 13 as an example, the mouth of the container of the solid standard substance of benzene series prepared in Example 13 was opened, and the gel network structure was completely destroyed by heating until it melted, so that the benzene series was completely released. At the same time, the test was carried out with reference to the ISO 12219-2:2012 method. The test results are shown in Tables 6-7.

[0059] Table 2 Uniformity test data of benzene series solid standard in Example 1

[0060]

[0061]

[0062] Table 3 Stability test data of benzene series solid standard in Example 1

[0063]

[0064] From Table 2, we can see that F<F 0.05 (14,15), indicating that there is no significant difference between samples and samples, and the samples are uniform. 0.05 (30+20-2), indicating that there is no significant difference between the two average values ​​and the sample stability is good.

[0065] Table 4: Uniformity test data of benzene series solid standard of Example 7

[0066]

[0067]

[0068] Table 5 Stability test data of benzene series solid standard substance in Example 7

[0069]

[0070]

[0071] From Table 4, we can see that F<F 0.05 (14,15), indicating that there is no significant difference between samples and samples, and the samples are uniform. It can be seen from Table 5 that t<t 0.05 (30+20-2), indicating that there is no significant difference between the two average values ​​and the sample stability is good.

[0072] Table 6 Uniformity test data of benzene series solid standard of Example 13

[0073]

[0074]

[0075] Table 7 Stability test data of benzene series solid standard substances in Example 13

[0076]

[0077] From Table 6, we can see that F<F 0.05 (14,15), indicating that there is no significant difference between samples and samples, and the samples are uniform. It can be seen from Table 7 that t<t 0.05 (30+20-2), indicating that there is no significant difference between the two average values ​​and the sample stability is good.

[0078] In each example and comparative example experiment, five different concentrations of benzene series solid standard substances with theoretical loading concentrations of 10, 20, 50, 100, and 200 μg / mL were added. The test results of the examples and comparative examples are summarized in Table 8. At the same time, for the convenience of comparison, only the F value and t value are recorded.

[0079] The mass calculation method for the benzene series compound used in the preparation of the benzene series target material is as follows: five different concentrations of benzene series solid standard materials are set up according to the theoretical loading concentrations of 10μg / ml, 20μg / ml, 50μg / ml, 100μg / ml, and 200μg / ml, respectively. Specifically, the volume V2 of the gel added by weight is measured by the displacement method at room temperature, or the volume V2 of the gel added by weight is calculated based on the gel density. According to the theoretical loading concentration C2 = m / V2 (unit: μg / mL), m pure benzene series compounds are calculated and weighed, and then prepared together with the solvent to prepare the added weight of the benzene series target material. Since the volume of the gel of the corresponding weight part before preparation is not much different from the volume of the prepared benzene series solid standard material, it is ignored here.

[0080] Table 8

[0081]

[0082]

[0083] Since the number of tests and sampling methods for uniformity and stability of the examples and comparative examples are the same, the basis for judging the uniformity of the above examples and comparative examples is the same as that of Example 1, and the sample uniformity test data F<F 0.05 (14,15)=2.42 and sample stability test data t<t 0.05 (30+20-2)=1.677, which proves that the sample is both uniform and stable.

[0084] It can be seen from Table 8 that F>F 0.05 (14,15), indicating that there are significant differences within and between the comparative samples; in addition, t>t 0.05 (30 + 20 - 2), indicating a significant difference between the two average values, indicating poor sample stability. The reasons for this result are as follows: the gelatin used in this comparative example has a relatively low formation temperature, requiring lower temperatures for the benzene series to be immobilized, resulting in some loss at room temperature. Furthermore, the linear molecular structure lacks sufficient adsorption sites.

[0085] At the same time, it can be found that the stability of the standards of Examples 13-15 and Examples 16-18 is more outstanding. This may be because carrageenan has good gel stability and a certain strength. After compounding with agar mold gel, it can enhance the stability of the entire gel system, making the gel structure less susceptible to external factors (such as temperature, humidity, mechanical disturbance, etc.) during the adsorption process; the F value and t value of the standards of Examples 10, 11, 12 and 19 are slightly higher. For Examples 10-12, the melting point of agarose gel is 95°C, which is close to the boiling point of benzene series during mixing, resulting in volatilization loss of benzene series; and for Example 19, the gel adsorption sites of 80 parts are relatively few, resulting in poor adsorption effect of benzene series. Although there are certain differences in the uniformity and stability of Examples 10, 11, 12 and 19, the F values ​​of all examples are less than F 0.05 (14,15), the t values ​​are all less than t 0.05 (30+20-2), which meets the basic requirements of standard samples and can be used as a solid standard for slowly releasing benzene series for testing.

[0086] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A solid standard substance of benzene series, characterized in that: The invention comprises 75-98 parts of gel and 2-25 parts of a target benzene series compound; the melting point of the gel is 60-100°C.

2. The benzene series solid standard substance according to claim 1, wherein The benzene series target includes benzene series compounds.

3. The benzene series solid standard substance according to claim 2, wherein The concentration of the benzene series compounds in the benzene series solid standard substance is ≥5 μg / mL; preferably, the concentration of the benzene series compounds in the benzene series solid standard substance is 10-1000 μg / mL.

4. The benzene series solid standard substance according to claim 1, wherein The melting point of the gel is 60-70°C.

5. The benzene series solid standard substance according to claim 1, wherein The gel is at least one of agar impression gel, carrageenan, chitosan gel and agarose gel.

6. The benzene series solid standard substance according to claim 5, wherein The gel is a mixture of agar impression gel and carrageenan; preferably, the weight ratio of the agar impression gel to carrageenan is 1:(0.3-0.8).

7. The benzene series solid standard substance according to claim 2, wherein: The benzene series compound includes at least one of benzene, toluene, xylene, ethylbenzene and styrene.

8. A method for preparing a solid standard substance of benzene series according to any one of claims 1 to 7, characterized in that: The preparation method is as follows: the gel and the benzene series target substance are heated and melted, and then mixed evenly, and then cooled until the gel solidifies to obtain the benzene series solid standard substance.

9. Use of the benzene series solid standard substance according to any one of claims 1 to 7 in the automotive field.

10. Use of the solid standard substance of BTEX as claimed in any one of claims 1 to 7 in detecting BTEX content in automobiles and in evaluating and calibrating BTEX content testing equipment for samples.

Images