A method for detecting lead content in lubricating oil

Abstract

The present invention provides a method for detecting the content of lead in lubricating oil, and relates to the technical field of lead content detection in lubricating oil. The method comprises: using a rotating disk motor emission spectrometer to collect spectra of standard oils with known lead content under preset collection conditions, and collecting each standard oil multiple times; performing first-order differential and smoothing processing on the collected standard oil spectra, and performing multivariate scattering calibration; using a principal component regression method to establish a correlation model between the lead content and the standard oil spectra under specific parameters; using a rotating disk motor emission spectrometer to collect spectra of lubricating oil samples under the same collection conditions as the standard oil; inputting the lubricating oil sample spectra into the correlation model to obtain the content of lead in the lubricating oil sample. In this way, the effective information of many spectral lines of the lead element can be fully utilized, and the detection limit of the lead element of the rotating disk motor emission spectrometer can be effectively improved.

Description

Technical Field

[0001] The invention belongs to the technical field of lubricating oil detection, and in particular relates to a method for detecting the content of lead in lubricating oil. Background Art

[0002] Lead is a common wear element in used engine lubricants. The presence of lead indicates that the main bearing alloy material, seal connecting rod bearings, sliders and other parts of the engine have worn out. By monitoring the lead content, engine failures can be accurately predicted, which is of great significance for improving the service life of the engine.

[0003] Unlike instruments such as inductively coupled plasma emission spectrometer and atomic absorption spectrometer, which need to digest the lubricating oil into an aqueous solution before testing, the rotating disk motor emission spectrometer does not need to digest the lubricating oil and can directly analyze the lead element in the lubricating oil. It has the advantages of fast analysis speed and low personnel requirements.

[0004] The existing technology of analyzing the lead element in lubricating oil by rotating disk motor emission spectrometer is to use the traditional working curve method, that is, to establish a working curve through the signal data of the characteristic spectrum line of the lead element (usually 283.31nm) for testing. However, since the background signal of the lubricating oil matrix is ​​significantly higher than that of the water matrix, and the excitation signal of the lead element itself is very low, the detection limit of the rotating disk motor emission spectrometer when testing the lead element is not ideal, which is very unfavorable for the early diagnosis of lead element engine wear.

[0005] Therefore, finding a method to improve the detection limit of lead in rotating disk motor emission spectrometer has always been one of the urgent problems to be solved in this field. Summary of the invention

[0006] In view of the above technical problems, the present invention provides a method for detecting the lead content in lubricating oil, the purpose of which is to improve the detection limit of lead element of rotating disk electrode emission spectrometer and enhance the detection sensitivity of lead element content in lubricating oil.

[0007] The technical solution adopted by the present invention is as follows:

[0008] Under the preset acquisition conditions, a rotating disk motor emission spectrometer is used to acquire spectra of standard oils with known lead content, and each standard oil is acquired multiple times;

[0009] The collected standard oil spectrum is subjected to first-order differential and smoothing processing, and multivariate scattering calibration is performed;

[0010] Using principal component regression method, a correlation model between lead content and standard oil spectra was established under specific parameters;

[0011] The spectrum of the lubricating oil sample is collected using a rotating disk motor emission spectrometer under the same collection conditions as the standard oil;

[0012] The lubricating oil sample spectrum is input into the correlation model to obtain the content of lead element in the lubricating oil sample.

[0013] In a possible implementation, the acquisition conditions include: a spectrum acquisition range of 200 nm to 400 nm, a pre-combustion of 2 to 4 seconds; and then, continuously acquiring signals 15 to 25 times at an acquisition frequency of 0.8 to 1.2 seconds and taking an average value.

[0014] In a possible implementation manner, the pre-combustion is 3 seconds; or, the acquisition frequency is 1.1 seconds; or, the signal is acquired 20 times continuously and the average value is taken.

[0015] In a possible implementation, the concentrations of standard oils with known lead content are 1 mg / kg, 2 mg / kg, 3 mg / kg, 4 mg / kg, and 5 mg / kg, respectively, and each standard oil is collected 10 to 20 times.

[0016] In a possible implementation, the smoothing process includes 7-13 point Savitzky Golay smoothing.

[0017] In a possible implementation, principal component regression is used in the wavelength range of 200 nm to 400 nm, with the number of principal factors being 5 to 7, to establish a correlation model between the lead content and the spectrometer spectrum.

[0018] In a possible implementation, the wavelength range is 210 nm to 290 nm.

[0019] In a possible implementation, the wavelength range is between 210 nm to 230 nm and 260 nm to 290 nm.

[0020] In a possible implementation manner, the number of main factors is preferably 6.

[0021] The present invention has at least the following beneficial effects:

[0022] There are many spectral lines of lead in lubricating oil, but many of these spectral peaks have very low characteristic signal intensity or are interfered by other signals and cannot be used directly. Existing technologies often extract effective information and establish working curves through specific strong signal spectral peaks of lead elements, such as 283.31nm. This method can only extract limited effective information, so the detection limit that can be achieved for lead elements is limited.

[0023] The present invention proposes a method for detecting the content of lead in lubricating oil. By using the spectrum of a rotating disk motor emission spectrometer collected under specific collection conditions, principal component regression is used, and then combined with specific differentiation, smoothing, and multivariate scattering calibration algorithms, all data of the full band or the preferred rear band in the lubricating oil spectrum are involved in the calculation, so that the effective information of many spectral peaks of the lead element can be fully utilized, thereby effectively improving the detection limit of the lead element of the rotating disk motor emission spectrometer. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0025] Figure 1 The present invention provides a flow chart of a method for detecting the content of lead in lubricating oil. DETAILED DESCRIPTION

[0026] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0027] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0028] Since the background signal of the lubricating oil matrix is ​​significantly higher than that of the water matrix, and the excitation signal of the lead element itself is very low, the detection limit of the rotating disk motor emission spectrometer is not ideal when testing the lead element. Based on this, the embodiment of the present invention proposes a detection method for the lead content in lubricating oil, which is used to fully participate in the calculation of the data of the full band or the preferred rear band in the lubricating oil spectrum, and make full use of the effective information of many spectral peaks of the lead element, thereby improving the detection limit of the lead element of the rotating disk motor emission spectrometer. Figure 1 As shown, the method specifically comprises the following steps:

[0029] S101: Under preset collection conditions, using a rotating disk motor emission spectrometer to collect spectra of standard oils with known lead content, and collecting each standard oil multiple times;

[0030] S102: performing first-order differential and smoothing processing on the collected standard oil spectrum, and performing multivariate scattering calibration;

[0031] S103: using the principal component regression method, establishing a correlation model between the lead content and the standard oil spectrum under specific parameters;

[0032] S104: using a rotating disk motor emission spectrometer to collect a spectrum of the lubricating oil sample under the same collection conditions as the standard oil;

[0033] S105: Inputting the lubricating oil sample spectrum into the correlation model to obtain the content of lead element in the lubricating oil sample.

[0034] In order to enable those skilled in the art to more clearly understand the technical solution provided by the present invention, it will be described in detail below in conjunction with specific embodiments.

[0035] Example 1

[0036] (1) using a rotating disk electro-optical emission spectrometer to collect spectra of standard oils with known lead content of 1 mg / kg, 2 mg / kg, 3 mg / kg, 4 mg / kg, and 5 mg / kg;

[0037] The acquisition conditions were as follows: the spectrum acquisition range was 200 nm to 400 nm, pre-combustion was performed for 2 seconds, and then the signal was continuously acquired 25 times at an acquisition frequency of 0.9 seconds and averaged, and each sample was acquired 10 times.

[0038] (2) The collected spectra were subjected to first-order differentiation, 8-point Savitzky Golay smoothing, and multivariate scattering calibration (MSC);

[0039] (3) Using chemometric software, principal component regression (PCR) was used in the wavelength range of 200 nm to 400 nm, with 5 principal factors, to establish a correlation model between the lead content and the spectrum of the rotating disk motor emission spectrometer;

[0040] (4) using a rotating disk motor emission spectrometer to collect a spectrum of the sample to be tested under the same conditions;

[0041] (5) Substitute the spectrum of the sample to be tested into the above-mentioned correlation model, and the correlation model can quickly calculate the content of lead in the sample to be tested.

[0042] Example 2

[0043] (1) using a rotating disk electro-optical emission spectrometer to collect spectra of standard oils with known lead content of 1 mg / kg, 2 mg / kg, 3 mg / kg, 4 mg / kg, and 5 mg / kg;

[0044] The acquisition conditions were as follows: the spectrum acquisition range was 200 nm to 400 nm, pre-combustion was performed for 3 seconds, and then the signal was continuously acquired 20 times at an acquisition frequency of 0.8 seconds and averaged, and each sample was acquired 15 times.

[0045] (2) The collected spectra were subjected to first-order differentiation, 7-point Savitzky Golay smoothing, and multivariate scattering calibration (MSC);

[0046] (3) Using chemometric software, principal component regression (PCR) was used in the wavelength range of 210 nm to 290 nm, with the number of principal factors being 7, to establish a correlation model between the lead content and the spectrum of the rotating disk motor emission spectrometer;

[0047] (4) using a rotating disk motor emission spectrometer to collect a spectrum of the sample to be tested under the same conditions;

[0048] (5) Substitute the spectrum of the sample to be tested into the above-mentioned correlation model, and the correlation model can quickly calculate the content of lead in the sample to be tested.

[0049] Example 3

[0050] (1) using a rotating disk electro-optical emission spectrometer to collect spectra of standard oils with known lead content of 1 mg / kg, 2 mg / kg, 3 mg / kg, 4 mg / kg, and 5 mg / kg;

[0051] The acquisition conditions were as follows: the spectrum acquisition range was 200 nm to 400 nm, pre-combustion was 4 seconds, and then the signal was continuously acquired 20 times at an acquisition frequency of 1.1 seconds and averaged, and each sample was acquired 10 times.

[0052] (2) The collected spectra were subjected to first-order differentiation, 9-point Savitzky Golay smoothing, and multivariate scattering calibration (MSC);

[0053] (3) Using chemometric software, principal component regression (PCR) was used in the wavelength range of 210 nm to 230 nm plus 260 nm to 290 nm, with 5 principal factors, to establish a correlation model between the lead content and the spectrum of the rotating disk motor emission spectrometer;

[0054] (4) using a rotating disk motor emission spectrometer to collect a spectrum of the sample to be tested under the same conditions;

[0055] (5) Substituting the spectrum of the sample to be tested into the above-mentioned correlation model, the correlation model can quickly calculate the content of lead in the sample to be tested.

[0056] Example 4

[0057] (1) using a rotating disk electro-optical emission spectrometer to collect spectra of standard oils with known lead content of 1 mg / kg, 2 mg / kg, 3 mg / kg, 4 mg / kg, and 5 mg / kg;

[0058] The acquisition conditions were as follows: the spectrum acquisition range was 200 nm to 400 nm, pre-combustion was performed for 3 seconds, and then the signal was continuously acquired 15 times at an acquisition frequency of 1 second and averaged, and each sample was acquired 20 times.

[0059] (2) The collected spectra were subjected to first-order differentiation, 13-point Savitzky Golay smoothing, and multivariate scattering calibration (MSC);

[0060] (3) Using chemometric software, principal component regression (PCR) was used in the wavelength range of 210 nm to 290 nm, with the number of principal factors being 7, to establish a correlation model between the lead content and the spectrum of the rotating disk motor emission spectrometer;

[0061] (4) using a rotating disk motor emission spectrometer to collect a spectrum of the sample to be tested under the same conditions;

[0062] (5) Substituting the spectrum of the sample to be tested into the above-mentioned correlation model, the correlation model can quickly calculate the content of lead in the sample to be tested.

[0063] Example 5

[0064] (1) using a rotating disk electro-optical emission spectrometer to collect spectra of standard oils with known lead content of 1 mg / kg, 2 mg / kg, 3 mg / kg, 4 mg / kg, and 5 mg / kg;

[0065] The acquisition conditions were as follows: the spectrum acquisition range was 200 nm to 400 nm, pre-combustion was performed for 2 seconds, and then the signal was continuously acquired 15 times at an acquisition frequency of 1.2 seconds and averaged, and each sample was acquired 15 times.

[0066] (2) The collected spectra were subjected to first-order differentiation, 11-point Savitzky Golay smoothing, and multivariate scattering calibration (MSC);

[0067] (3) Using chemometric software, principal component regression (PCR) was used in the wavelength range of 210 nm to 230 nm plus 260 nm to 290 nm, with 6 principal factors, to establish a correlation model between the lead content and the spectrum of the rotating disk motor emission spectrometer;

[0068] (4) using a rotating disk motor emission spectrometer to collect a spectrum of the sample to be tested under the same conditions;

[0069] (5) Substituting the spectrum of the sample to be tested into the above-mentioned correlation model, the correlation model can quickly calculate the content of lead in the sample to be tested.

[0070] Comparative Example 1

[0071] (1) using a rotating disk electro-optical emission spectrometer to collect spectra of standard oils with known lead content of 1 mg / kg, 2 mg / kg, 3 mg / kg, 4 mg / kg, and 5 mg / kg;

[0072] The acquisition conditions were as follows: the spectrum acquisition range was 200 nm to 400 nm, pre-combustion was performed for 2 seconds, and then the signal was continuously acquired 15 times at an acquisition frequency of 0.8 seconds and averaged, and each sample was acquired 10 times.

[0073] (2) Establishing a working curve based on the signal data corresponding to the characteristic spectrum line 283.31 nm of the lead element;

[0074] (3) using a rotating disk motor emission spectrometer to collect signal data of the sample to be tested under the same conditions;

[0075] (4) Substituting the signal data of the sample to be tested into the above working curve, the content of Cu element in the sample to be tested can be quickly calculated.

[0076] Comparative Example 2

[0077] (1) using a rotating disk electro-optical emission spectrometer to collect spectra of standard oils with known lead content of 1 mg / kg, 2 mg / kg, 3 mg / kg, 4 mg / kg, and 5 mg / kg;

[0078] The acquisition conditions were as follows: the spectrum acquisition range was 200 nm to 400 nm, pre-combustion was performed for 3 seconds, and then the signal was continuously acquired 20 times at an acquisition frequency of 1.1 seconds and averaged, and each sample was acquired 15 times.

[0079] (2) Establishing a working curve based on the signal data corresponding to the characteristic spectrum line 283.31 nm of the lead element;

[0080] (3) using a rotating disk motor emission spectrometer to collect signal data of the sample to be tested under the same conditions;

[0081] (4) Substituting the signal data of the sample to be tested into the above working curve, the content of Cu element in the sample to be tested can be quickly calculated.

[0082] Comparative Example 3

[0083] (1) using a rotating disk electro-optical emission spectrometer to collect spectra of standard oils with known lead content of 1 mg / kg, 2 mg / kg, 3 mg / kg, 4 mg / kg, and 5 mg / kg;

[0084] The acquisition conditions were as follows: the spectrum acquisition range was 200 nm to 400 nm, pre-combustion was performed for 4 seconds, and then the signal was continuously acquired 25 times at an acquisition frequency of 1.2 seconds and averaged, and each sample was acquired 20 times.

[0085] (2) Establishing a working curve based on the signal data corresponding to the characteristic spectrum line 283.31 nm of the lead element;

[0086] (3) using a rotating disk motor emission spectrometer to collect signal data of the sample to be tested under the same conditions;

[0087] (4) Substituting the signal data of the sample to be tested into the above working curve, the content of Cu element in the sample to be tested can be quickly calculated.

[0088] In Examples 1 to 5 and Comparative Examples 1 to 3, the standard oil with a lead content of 1 mg / kg in the lubricating oil was measured repeatedly 11 times, and the detection limit was calculated with 3 times the standard deviation. The results are shown in the table below.

[0089]

[0090] It can be seen from the table that the detection limits of Examples 1 to 5 are between 0.08 and 0.17 mg / kg, which are significantly better than the 0.68 to 0.72 mg / kg of Comparative Examples 1 to 3.

[0091] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for detecting the content of lead in lubricating oil, characterized in that: include: Under the preset acquisition conditions, the spectra of the standard oils with known lead content were collected using a rotating disk electrode emission spectrometer, and each standard oil was collected multiple times; The collected standard oil spectrum is subjected to first-order differential and smoothing processing, and multivariate scattering calibration is performed; Using principal component regression method, a correlation model between lead content and standard oil spectra was established under specific parameters; The spectrum of the lubricating oil sample is collected using a rotating disk electrode emission spectrometer under the same collection conditions as the standard oil; The lubricating oil sample spectrum is input into the correlation model to obtain the content of lead element in the lubricating oil sample.

2. The method for detecting the lead content in lubricating oil according to claim 1, characterized in that: The acquisition conditions include: the spectrum acquisition range is 200nm to 400nm, the pre-combustion is 2 to 4 seconds; then, the signal is continuously acquired 15 to 25 times at an acquisition frequency of 0.8 to 1.2 seconds and the average value is taken.

3. The method for detecting the lead content in lubricating oil according to claim 2, characterized in that: The pre-combustion is 3 seconds; or, the acquisition frequency is 1.1 seconds; or, the signal is acquired 20 times continuously and the average value is taken.

4. The method for detecting the lead content in lubricating oil as claimed in claim 1, wherein the concentrations of standard oils with known lead content are 1 mg / kg, 2 mg / kg, 3 mg / kg, 4 mg / kg, and 5 mg / kg, respectively, and each standard oil is collected 10 to 20 times.

5. The method for detecting the lead content in lubricating oil according to claim 4, characterized in that: Each standard oil was collected 15 times.

6. The method for detecting the lead content in lubricating oil according to claim 1, characterized in that: The smoothing process includes 7-13 point Savitzky-Golay smoothing.

7. The method for detecting the lead content in lubricating oil according to claim 1, characterized in that: Principal component regression was used in the wavelength range of 200nm to 400nm, with the number of principal factors ranging from 5 to 7, to establish a correlation model between lead content and spectrometer spectra.

8. The method for detecting the lead content in lubricating oil according to claim 7, characterized in that: The wavelength range is 210nm~290nm.

9. The method for detecting the lead content in lubricating oil according to claim 7, characterized in that: The wavelength range is between 210nm~230nm and 260nm~290nm.

10. The method for detecting the lead content in lubricating oil according to claim 7, characterized in that: The number of principal factors used is 6.

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