Method for detecting ethanol content of vehicle gasoline

Abstract

The invention discloses a method for detecting the ethanol content of gasoline for vehicles, and belongs to the technical field of ethanol content detection of gasoline for vehicles. The detection method comprises the following steps: testing an ethanol gasoline standard substance to obtain first initial infrared spectrum data; performing baseline correction to obtain infrared spectrum data after first correction, and obtaining a standard substance minimum intensity value of an absorption peak of 6800cm <-1 >-6200cm <-1 > and a standard substance maximum intensity value of an absorption peak of 7085cm <-1 >-7115cm <-1 >; calculating the average value of the standard substance minimum intensity values and the average value of the standard substance maximum intensity values of the plurality of ethanol gasoline standard substances, and the deviation range of the minimum intensity value of the ethanol gasoline sample to be detected in the average value of the standard substance minimum intensity values; the highest intensity value of the to-be-detected ethanol gasoline sample is within the deviation range of the average value of the highest intensity values of the standard substances, and the to-be-detected ethanol gasoline sample is a qualified sample. The method is simple and convenient to operate and can be used for detecting samples in real time.

Description

Technical Field

[0001] The invention relates to the technical field of ethanol content detection of vehicle gasoline, and more specifically to a method for detecting the ethanol content of vehicle gasoline. Background Art

[0002] Ethanol gasoline for vehicles is a kind of automobile fuel formed by mixing denatured fuel ethanol and gasoline in a certain proportion. Adding a small amount of ethanol to gasoline can reduce exhaust emissions and improve the anti-knock performance of gasoline. However, due to the relatively low cost of ethanol, some manufacturers will illegally add excessive ethanol to gasoline. Due to the low calorific value, poor low-temperature performance and strong corrosiveness of ethanol, excessive addition of ethanol will lead to a decrease in the overall calorific value of gasoline, a decrease in low-temperature performance and corrosion of engine parts. Since ethanol has a certain volatility and the current detection method cannot achieve real-time sampling and real-time monitoring, a large number of samples with excessive ethanol content are circulated in the market, seriously damaging the interests of consumers.

[0003] At present, the conventional detection technology for ethanol content in gasoline is gas chromatography, which is a reliable method for analyzing ethanol content in oil. However, this method relies on professional equipment, has the disadvantages of long analysis time, large instrument size and difficulty in carrying, and cannot meet the needs of real-time detection.

[0004] Near infrared spectroscopy is a fast, non-destructive analytical technique. The main energy level transition types within the near infrared spectrum are the double frequency absorption of OH, NH and CH bonds. The main components of gasoline are C5~C 12 Aliphatic hydrocarbons and cycloalkanes, as well as a certain amount of aromatic hydrocarbons, can be analyzed by near-infrared spectrometer. Although the energy of near-infrared spectrum is relatively weak, only about 1 ml of sample is needed to complete near-infrared spectrum data sampling, and the sampling speed is extremely fast and will not damage the sample, so real-time sampling and real-time analysis data can be obtained. Near-infrared spectroscopy can measure the approximate range of ethanol content in ethanol gasoline samples and quickly screen out samples with excessive ethanol content.

[0005] When the prior art uses near-infrared spectroscopy to analyze ethanol content, such as Chinese invention patents CN114166792A and CN115236030A, when determining ethanol content, it is necessary to establish a correlation model by using the partial least squares method, which has a high computational complexity. Summary of the invention

[0006] In view of the above problems, the present invention provides a method for detecting the ethanol content of gasoline for automobiles. The present invention is easy to operate and can perform real-time detection on samples.

[0007] The object of the present invention is to provide a method for detecting the ethanol content of gasoline for automobiles, comprising the following steps: A near infrared test is performed on the ethanol gasoline standard to obtain the first initial infrared spectrum data.

[0008] A baseline correction is performed on the first initial infrared spectrum data to obtain first corrected infrared spectrum data.

[0009] The first corrected infrared spectrum data obtained at 6800 cm -1 ~6200cm -1 The standard minimum intensity value of the absorption peak and 7085cm -1 ~7115cm -1 The maximum intensity value of the standard absorbance peak.

[0010] Calculate the concentration of ethanol gasoline standards with different volume fractions at 6800 cm -1 ~6200cm -1 The average value of the minimum intensity of the standard absorption peak and 7085cm -1 ~7115cm -1 The average value of the maximum intensity value of the standard absorption peak is taken, and the minimum intensity value offset and the maximum intensity value offset of the ethanol gasoline standard are recorded.

[0011] The ethanol gasoline sample to be tested is subjected to near infrared testing to obtain the second initial infrared spectrum data. In the second initial infrared spectrum data, the wavelength at 6800cm -1 ~6200cm -1 The minimum intensity value of the absorption peak of the ethanol gasoline sample to be tested, and the absorption peak at 7085cm -1 ~7115cm -1 The maximum intensity value of the absorption peak of the ethanol gasoline sample to be tested.

[0012] If the lowest strength value of the ethanol gasoline sample to be tested is within the deviation range of the average value of the lowest strength value of the standard, and the highest strength value of the ethanol gasoline sample to be tested is within the deviation range of the average value of the highest strength value of the standard, the ethanol gasoline sample to be tested is a qualified sample.

[0013] On the contrary, if the lowest strength value of the ethanol gasoline sample to be tested is not within the deviation range of the average value of the lowest strength value of the standard, or the highest strength value of the ethanol gasoline sample to be tested is not within the deviation range of the average value of the highest strength value of the standard, the ethanol gasoline sample to be tested is an unqualified sample.

[0014] Near infrared spectroscopy is a very effective analytical method that can determine the composition of a sample by measuring the absorption spectrum of a substance in the near infrared band. Compared with other traditional chemical analysis methods, near infrared spectroscopy has the advantages of being fast, accurate, and non-destructive.

[0015] In practical applications, the ethanol in ethanol gasoline can produce an obvious and sharp absorption peak in the near-infrared spectrum and a valley absorption peak change between the two absorption peaks that is not easily noticed. Based on this, the present invention can estimate the range of ethanol content in ethanol gasoline by recording the performance of these two characteristic values ​​in the compliance range, making full use of the advantages of near-infrared spectrometers that are easy to carry and have extremely high detection efficiency, and quickly distinguish whether the ethanol content in the sample is in the compliance range.

[0016] In a preferred embodiment of the present invention, the offset range of the average value of the standard minimum intensity value is between the difference between the average value of the standard minimum intensity value and the minimum intensity value offset and the sum of the average value of the standard minimum intensity value and the minimum intensity value offset.

[0017] In a preferred embodiment of the present invention, the calculation formula of the minimum intensity value offset is: minimum intensity value offset=first difference / first average value.

[0018] Among them, the first difference is the difference between the maximum and minimum values ​​of the minimum strength values ​​of ethanol gasoline standards with different volume fractions; the first average value is the average value of the minimum strength values ​​of ethanol gasoline standards with different volume fractions.

[0019] In a preferred embodiment of the present invention, the offset range of the average value of the standard maximum intensity value is between the difference between the average value of the standard maximum intensity value and the maximum intensity value offset and the sum of the average value of the standard maximum intensity value and the maximum intensity value offset.

[0020] In a preferred embodiment of the present invention, the maximum intensity value offset=second difference value / second average value.

[0021] Among them, the second difference is the difference between the maximum and minimum values ​​of the maximum strength values ​​of ethanol gasoline standards with different volume fractions; the second average value is the average value of the maximum strength values ​​of ethanol gasoline standards with different volume fractions.

[0022] The ethanol content requirement in automotive ethanol gasoline is that the volume fraction of ethanol is 10% ± 2%. That is, samples with a volume fraction of ethanol in the range of 8% to 12% are qualified products. In a preferred embodiment of the present invention, the volume of ethanol in the ethanol gasoline standard is 8% to 12%.

[0023] In a preferred embodiment of the present invention, when performing near infrared testing, the scanning wave number range is 8000cm -1 ~4500cm -1 , resolution 0.5cm -1 , the sampling interval is 1cm -1 .

[0024] In a preferred embodiment of the present invention, when performing near infrared testing, the amount of the ethanol gasoline standard or the ethanol gasoline sample to be tested is less than 2 ml.

[0025] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention utilizes the 6800~6200cm in the near infrared spectrum -1 The absorption peak intensity of the interval and 7100cm -1 The absorption peak intensity near 6800cm is a combination of these two parameters to determine the ethanol content in the sample. During the test, it is only necessary to test the sample to be tested and obtain the absorption peak intensity at 6800cm -1 ~6200cm -1 The minimum intensity of the absorption peak is 7085cm -1 ~7115cm -1 The maximum intensity value of the absorption peak can be compared with the data of the standard product to determine whether the sample to be tested is qualified, and the calculation is simple. The detection method of the present invention has a short detection cycle and can perform instant detection on the sample to determine whether the controversial sample is a qualified product.

[0026] (2) The detection method of the present invention is highly flexible. The absorption peak data obtained by a single modeling can be reused, and the upper or lower limit can be changed without modifying the unchanged data.

[0027] (3) Near-infrared detection is fast, and samples can be randomly sampled and tested at any time during the test, avoiding problems caused by sending samples for testing and long waiting times.

[0028] (4) The detection method of the present invention is easy to operate. Operators only need simple training to complete the detection. When temporary or sudden large-scale detection needs arise, personnel can be flexibly deployed.

[0029] (5) The present invention uses less sample volume during testing, thus saving waste liquid treatment costs. Generally, the sample volume used for a single test is less than 2 ml, and the amount of waste liquid generated is extremely small compared to traditional testing methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is the test result diagram in Example 2, where illustration a is 6800 cm -1 ~6200cm -1 A local enlarged view of the absorption peak position, inset b is 7085 cm -1 ~7115cm -1 A local magnified view of the absorption peak position.

[0031] Figure 2 This is the infrared spectrum data diagram of ethanol volume fraction of 9.3%.

[0032] Figure 3 This is the infrared spectrum data diagram of ethanol volume fraction of 10.32%.

[0033] Figure 4 This is the infrared spectrum data diagram of ethanol volume fraction of 2.1%. DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] The near infrared spectrometer has a fast acquisition speed. -1 And the sampling wave number range is not less than 8000cm -1 ~4500cm -1 It only takes about 5 minutes to collect a single sample. This means that the present invention can quickly obtain a large number of oil samples, and the technology can be used to quickly distinguish between compliant samples and non-compliant samples. Therefore, in application scenarios where it is necessary to distinguish between compliant ethanol gasoline samples and non-compliant samples, the application of near-infrared spectroscopy technology will be able to efficiently achieve rapid sampling, rapid analysis and rapid judgment. The present invention provides a convenient and reliable detection method for the petroleum industry, helping relevant personnel to better control product quality and quickly determine whether samples meet national standards and legal requirements.

[0036] It should be noted that the infrared spectrometer used for testing should comply with GB / T21186 standard. The effective wave number range of the spectrum should be no less than 8000cm -1 ~4500cm -1 , spectral resolution better than 4cm -1 , signal-to-noise ratio is better than 10000:1, wavelength accuracy is better than 0.1cm -1 , data sampling interval is better than 0.5cm -1 .

[0037] Example 1 (1) Select ethanol gasoline standard with an ethanol volume fraction between 8% and 12%. Allow the sample to stand at room temperature and shake well.

[0038] (2) Use an infrared spectrometer that complies with GB / T21186 standard with a scanning wavenumber range of 8000cm -1 ~4500cm -1 , resolution 0.5cm -1 , the sampling interval is 1cm-1 , use 8mm quartz cuvette for sampling.

[0039] (3) A pipette with a maximum range of 100 ml and a fixed range of 1.5 ml was used to perform near-infrared tests on all ethanol gasoline standards to obtain spectral curves. The ethanol gasoline standards with different volume fractions were scanned three times repeatedly, and the obtained spectral curves were averaged to minimize the error, thus obtaining the first initial infrared spectral data of ethanol gasoline standards with different volume fractions.

[0040] (4) Baseline correction is performed on the first initial infrared spectrum data of the ethanol gasoline standard with different volume fractions to obtain the first corrected infrared spectrum data of the ethanol gasoline standard with different volume fractions.

[0041] The infrared spectrum data of the first correction of ethanol gasoline standards with different volume fractions is located at 6800cm -1 ~6200cm -1 The minimum intensity value of the absorption peak and 7085cm -1 ~7115cm -1 The highest intensity value of the absorption peak was recorded.

[0042] The infrared spectrum data of the first correction of ethanol gasoline standards with different volume fractions is located at 6800cm -1 ~6200cm -1 The minimum intensity value at the absorption peak position is recorded, and the first difference between the maximum and minimum values ​​of the minimum intensity value of the standard and the average value of the minimum intensity value of the standard are calculated. The average value of the minimum intensity value of the standard is recorded as the first average value.

[0043] The minimum intensity value offset is calculated by the first difference and the first average value. The calculation formula is as follows.

[0044] Minimum intensity value offset = first difference value / first average value.

[0045] The infrared spectrum data of the first correction of ethanol gasoline standards with different volume fractions is located at 7085cm -1 ~7115cm -1 The highest intensity value at the absorption peak position is recorded, and the second difference between the maximum and minimum values ​​of the highest intensity values ​​of the standard and the average value of the highest intensity values ​​of the standard are calculated. The average value of the highest intensity values ​​of the standard is recorded as the second average value.

[0046] The minimum intensity value offset is calculated by the second difference and the second average value. The calculation formula is as follows.

[0047] Maximum intensity value offset = second difference value / second average value.

[0048] Using the 6800cm -1 ~6200cm -1 The average value of the absorption peak position and the minimum intensity value of the standard ± the minimum intensity value offset and 7085cm -1 ~7115cm -1 The absorption peak position and the average value of the maximum intensity value of the standard ± the offset of the maximum intensity value are used to detect whether the ethanol content in the unknown sample is within the compliance range.

[0049] Example 2 (1) Select ethanol gasoline standards with ethanol volume fractions ranging from 8.33% to 10.32%, with specific ethanol volume fractions of 8.33%, 8.78%, 9.45%, 9.54%, 9.73%, 9.77%, 10.18%, 10.24% and 10.32%, respectively. Allow the samples to stand at room temperature and shake well.

[0050] (2) Use an infrared spectrometer that complies with GB / T21186 standard with a scanning wavenumber range of 8000cm -1 ~4500cm -1 , resolution 0.5cm -1 , the sampling interval is 1cm -1 , use 8mm quartz cuvette for sampling.

[0051] (3) A pipette with a maximum range of 100 ml and a fixed range of 1.5 ml was used to perform near-infrared tests on all ethanol gasoline standards to obtain spectral curves. The ethanol gasoline standards with different volume fractions were scanned three times repeatedly, and the obtained spectral curves were averaged to minimize the error, thus obtaining the first initial infrared spectral data of ethanol gasoline standards with different volume fractions.

[0052] (4) Baseline correction is performed on the first initial infrared spectrum data of the ethanol gasoline standard with different volume fractions to obtain the first corrected infrared spectrum data of the ethanol gasoline standard with different volume fractions.

[0053] The infrared spectrum data of the first correction of ethanol gasoline standards with different volume fractions is located at 6800cm -1 ~6200cm -1 The maximum value and the minimum value among the minimum intensity values ​​of the standard at the absorption peak position are recorded, and the first difference value and the first average value among the maximum value and the minimum value among the minimum intensity values ​​of the standard are calculated.

[0054] The minimum intensity value offset of the standard is calculated by the first difference and the first average value. The calculation formula is as follows.

[0055] The minimum intensity value offset of the standard = first difference / first average value.

[0056] The infrared spectrum data of the first correction of ethanol gasoline standards with different volume fractions is located at 7085cm -1 ~7115cm -1 The maximum value and the minimum value among the highest intensity values ​​of the standard at the absorption peak position are recorded, and the second difference between the maximum value and the minimum value among the highest intensity values ​​of the standard and the second average value are calculated.

[0057] The maximum intensity value offset of the standard is calculated by the second difference and the second average. The calculation formula is as follows.

[0058] The maximum intensity value offset of the standard = the second difference / the second average value.

[0059] The infrared spectrum data of the first correction of ethanol gasoline standards with different volume fractions is located at 6800cm -1 ~6200cm -1 The minimum intensity value of the absorption peak is recorded, such as Figure 1 As shown, 6800cm -1 ~6200cm -1 The minimum intensity value of the absorption peak is between 0.6002 and 0.6232. The first difference between the maximum and minimum values ​​of the minimum intensity value is calculated to be 0.023, and the first average value is 0.6114.

[0060] The minimum intensity value offset calculated by the first difference and the first average value is 0.03.

[0061] The infrared spectrum data of the first correction of ethanol gasoline standards with different volume fractions is located at 7085cm -1 ~7115cm -1 The highest intensity value at the absorption peak position is recorded, such as Figure 1 As shown, 7100cm -1 ±15cm -1 The maximum intensity value of the absorption peak ranges from 0.90 to 0.91. The second difference between the maximum and minimum values ​​of the maximum intensity value is calculated to be 0.01, and the second average value is 0.9056.

[0062] The maximum intensity value offset calculated by the second difference and the second average is 0.01.

[0063] Using the 6800cm -1 ~6200cm -1 The absorption peak position and 7085cm -1 ~7115cm -1The absorption peak position and its offset are used to detect whether the ethanol content in the unknown sample is within the compliance range.

[0064] When the sample to be tested is at 6800cm -1 ~6200cm -1 The minimum intensity value of the absorption peak position is in the range of 0.6114±0.03, 7085cm -1 ~7115cm -1 If the maximum intensity value at the absorption peak position is within the range of 0.9056±0.01, the sample to be tested is a qualified sample.

[0065] Example 3 In this embodiment, an infrared spectrometer conforming to the GB / T21186 standard is used to detect unknown gasoline samples, with a scanning wave number range of 8000 cm -1 ~4500cm -1 , resolution 0.5cm -1 , the sampling interval is 1cm -1 , use 8mm quartz cuvette for sampling.

[0066] A pipette with a maximum range of 100 ml and a fixed range of 1.5 ml is selected to perform near-infrared testing on an unknown ethanol gasoline sample to be tested, and a spectral curve is obtained to obtain second initial infrared spectrum data.

[0067] like Figure 2 As shown, the second initial infrared spectrum data at 6800cm -1 ~6200cm -1 The minimum intensity value of the absorption peak is 0.601, 7085 cm -1 ~7115cm -1 The maximum intensity value of the absorption peak is 0.90.

[0068] By comparison, it can be seen that the 6800 cm -1 ~6200cm -1 The minimum intensity value of the absorption peak and 7085cm -1 ~7115cm -1 The highest intensity values ​​of the absorption peaks are all at 6800 cm-1 for the ethanol gasoline standard in Example 2. -1 ~6200cm -1 The minimum intensity value of the absorption peak position is in the range of 0.6114±0.03 and 7085cm -1 ~7115cm -1 The maximum intensity value of the absorption peak position is within the range of 0.9056±0.01, therefore, the gasoline sample in this embodiment meets the requirements.

[0069] According to NB / SH / T 0663-2014 “Gas chromatography method for determination of alcohol and ether content in gasoline”, the unknown gasoline sample of Example 3 was tested by gas chromatography, and the measured ethanol volume fraction in the unknown gasoline sample was 9.3%, which was a qualified gasoline sample.

[0070] Example 4 In this embodiment, an infrared spectrometer conforming to the GB / T21186 standard is used to detect unknown gasoline samples, with a scanning wave number range of 8000 cm -1 ~4500cm -1 , resolution 0.5cm -1 , the sampling interval is 1cm -1 , use 8mm quartz cuvette for sampling.

[0071] A pipette with a maximum range of 100 ml and a fixed range of 1.5 ml is selected to perform near-infrared testing on an unknown ethanol gasoline sample to be tested, and a spectral curve is obtained to obtain second initial infrared spectrum data.

[0072] like Figure 3 As shown, the second initial infrared spectrum data at 6800cm -1 ~6200cm -1 The minimum intensity value of the absorption peak is 0.6226, 7085 cm -1 ~7115cm -1 The maximum intensity value of the absorption peak is 0.9023.

[0073] By comparison, it can be seen that the 6800 cm -1 ~6200cm -1 The minimum intensity value of the absorption peak and 7085cm -1 ~7115cm -1 The highest intensity values ​​of the absorption peaks are all at 6800 cm-1 for the ethanol gasoline standard in Example 2. -1 ~6200cm -1 The minimum intensity value of the absorption peak position is in the range of 0.6114±0.03 and 7085cm -1 ~7115cm -1 The maximum intensity value of the absorption peak position is within the range of 0.9056±0.01, therefore, the gasoline sample in this embodiment meets the requirements.

[0074] According to NB / SH / T 0663-2014 “Gas chromatography for determination of alcohol and ether content in gasoline”, the unknown gasoline sample of Example 4 was tested by gas chromatography, and the measured ethanol volume fraction in the unknown gasoline sample was 10.32%, which was a qualified gasoline sample.

[0075] Example 5 In this embodiment, an infrared spectrometer conforming to the GB / T21186 standard is used to detect unknown gasoline samples, with a scanning wave number range of 8000 cm -1 ~4500cm -1 , resolution 0.5cm -1 , the sampling interval is 1cm -1 , use 8mm quartz cuvette for sampling.

[0076] A pipette with a maximum range of 100 ml and a fixed range of 1.5 ml is selected to perform near-infrared testing on an unknown ethanol gasoline sample to be tested, and a spectral curve is obtained to obtain second initial infrared spectrum data.

[0077] like Figure 4 As shown, the second initial infrared spectrum data at 6800cm -1 ~6200cm -1 The minimum intensity of the absorption peak is 0.5022, 7085 cm -1 ~7115cm -1 The maximum intensity value of the absorption peak is 0.8239.

[0078] By comparison, it can be seen that the 6800 cm -1 ~6200cm -1 The minimum intensity value of the absorption peak and 7085cm -1 ~7115cm -1 The highest intensity value of the absorption peak is not in Example 2. The ethanol gasoline standard is located at 6800cm -1 ~6200cm -1 The minimum intensity value of the absorption peak position is in the range of 0.6114±0.03 and 7085cm -1 ~7115cm -1 The maximum intensity value of the absorption peak position is within the range of 0.9056±0.01, therefore, the unknown gasoline sample in this embodiment does not meet the requirements.

[0079] According to NB / SH / T 0663-2014 “Gas chromatography method for determination of alcohol and ether content in gasoline”, the unknown gasoline sample of Example 5 was tested by gas chromatography, and the measured ethanol volume fraction in the unknown gasoline sample was 2.11%, which was an unqualified gasoline sample.

[0080] After testing the unknown gasoline sample by gas chromatography, it was found that the result was the same as the determination result of the present invention, which shows the accuracy and practicality of the present invention. Therefore, by using the test method of the present invention, it is possible to quickly determine whether the ethanol content of the sample is within the compliance range. This method can be used as a rapid classification and early warning scheme for instant determination of whether the ethanol content in ethanol gasoline is within the compliance range.

[0081] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0082] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A method for detecting the ethanol content of gasoline for automobiles, characterized in that: The following steps are involved: Performing near infrared testing on the ethanol gasoline standard product to obtain first initial infrared spectrum data; Performing baseline correction on the first initial infrared spectrum data to obtain first corrected infrared spectrum data; The first corrected infrared spectrum data obtained at 6800 cm -1 ~6200cm -1 The standard minimum intensity value of the absorption peak and 7085cm -1 ~7115cm -1 The maximum intensity value of the standard sample of the absorption peak; Calculate the concentration of ethanol gasoline standards with different volume fractions at 6800 cm -1 ~6200cm -1 The average value of the minimum intensity of the standard absorption peak and 7085cm -1 ~7115cm -1 The average value of the highest intensity of the absorption peak of the standard; The ethanol gasoline sample to be tested is subjected to near infrared testing to obtain the second initial infrared spectrum data. In the second initial infrared spectrum data, the wavelength at 6800cm -1 ~6200cm -1 The minimum intensity value of the absorption peak of the ethanol gasoline sample to be tested, and the absorption peak at 7085cm -1 ~7115cm -1 The maximum intensity value of the absorption peak of the ethanol gasoline sample to be tested; If the lowest strength value of the ethanol gasoline sample to be tested is within the deviation range of the average value of the lowest strength value of the standard, and the highest strength value of the ethanol gasoline sample to be tested is within the deviation range of the average value of the highest strength value of the standard, the ethanol gasoline sample to be tested is a qualified sample.

2. The method for detecting the ethanol content of gasoline for automobiles according to claim 1, characterized in that: The deviation range of the average value of the minimum intensity values ​​of the standards is between the difference between the average value of the minimum intensity values ​​of the standards and the deviation of the minimum intensity values ​​and the sum of the average value of the minimum intensity values ​​of the standards and the deviation of the minimum intensity values.

3. The method for detecting the ethanol content of gasoline for automobiles according to claim 2, characterized in that: The calculation formula of the minimum intensity value offset is: minimum intensity value offset = first difference value / first average value; Among them, the first difference is the difference between the maximum and minimum values ​​of the minimum strength values ​​of ethanol gasoline standards with different volume fractions; the first average value is the average value of the minimum strength values ​​of ethanol gasoline standards with different volume fractions.

4. The method for detecting the ethanol content of gasoline for automobiles according to claim 1, characterized in that: The deviation range of the average value of the maximum intensity value of the standard is between the difference between the average value of the maximum intensity value of the standard and the deviation of the maximum intensity value and the sum of the average value of the maximum intensity value of the standard and the deviation of the maximum intensity value.

5. The method for detecting the ethanol content of gasoline for automobiles according to claim 4, characterized in that: The calculation formula of the maximum intensity value offset is: maximum intensity value offset = second difference value / second average value; Among them, the second difference is the difference between the maximum and minimum values ​​of the maximum strength values ​​of ethanol gasoline standards with different volume fractions; the second average value is the average value of the maximum strength values ​​of ethanol gasoline standards with different volume fractions.

6. The method for detecting ethanol content in gasoline for automobiles according to claim 1, characterized in that: In standard ethanol gasoline, the volume fraction of ethanol is 8%~12%.

7. The method for detecting ethanol content in gasoline for automobiles according to claim 1, characterized in that: When performing near-infrared testing, the scanning wavenumber range is 8000cm -1 ~4500cm -1 , resolution 0.5cm -1 , the sampling interval is 1cm -1 .

8. The method for detecting ethanol content in gasoline for automobiles according to claim 1, characterized in that: When conducting near infrared testing, the amount of ethanol gasoline standard or ethanol gasoline sample to be tested is less than 2 ml.

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