Application of a probe in detection of content of polar components in edible oil
By designing a novel polar-responsive fluorescent probe IND-2 and a portable detection device, the problem of cumbersome and time-consuming detection of polar components in edible oils in existing technologies has been solved, achieving rapid and accurate detection of polar component content in edible oils, which is suitable for the field of food safety monitoring.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- ZHENGZHOU UNIV
- Filing Date
- 2026-06-08
- Publication Date
- 2026-07-24
Smart Images
Figure CN122448836A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of rapid detection of polar component content in edible oils, and particularly relates to a colorimetric probe based on polar response. Background Technology
[0002] Edible oils, as an important part of daily life, are prone to a series of complex chemical reactions during storage and repeated frying, including the hydrolysis, oxidation, and condensation of triglycerides, generating various polar components. The accumulation of these polar substances not only reduces the quality and nutritional value of the oils but also poses potential risks to human health. The national standard method (GB5009.202–2016 Column Chromatography) is the legal basis for testing the safety of edible oils, possessing authority and enforceability, providing unified and reliable technical support for food safety supervision and enterprise quality control. However, the method relies on professional operators, involves cumbersome and time-consuming procedures, and requires large-scale specialized equipment, making it difficult to conduct rapid screening in daily life.
[0003] Currently, many fluorescent probes are based on tetraphenylethylene (TPE), coumarin, naphthimide, rhodamine, botryline dipyrrole (BODIPY), and cyanine (Cy). While each has its own characteristics, they all suffer from unavoidable limitations: TPE's aggregation-induced emission properties cause background interference and result in a short emission wavelength; coumarin suffers from severe photobleaching and has an emission wavelength <500 nm, making it susceptible to autofluorescence; naphthimide has poor solubility and a very small Stokes shift (often <30 nm), leading to severe self-quenching; rhodamine's dark-to-fluorescent switching is strongly dependent on an acidic environment, resulting in insufficient sensitivity at physiological pH; BODIPY's rigid planar structure is prone to aggregation-induced quenching, and its synthesis conditions are demanding; cyanine probes have extremely poor photostability, easily fading and generating reactive oxygen species under prolonged irradiation, leading to phototoxicity. Therefore, it is crucial to develop a probe for detecting the content of polar components in edible oils to address these issues. Summary of the Invention
[0004] To address the aforementioned technical problems, this invention proposes an application of a probe in the detection of polar component content in edible oils.
[0005] To achieve the above objectives, the technical solution of the present invention is implemented as follows:
[0006] An application of a probe in the detection of polar component content in edible oils, wherein the structural formula of the probe (also known as probe IND-2) is as follows:
[0007] .
[0008] Furthermore, the preparation method of the above probe is as follows: 1,3-indanedione (1.00 g, 6.85 mmol) and 3 mL of pyridine are weighed into a dry round-bottom flask. The mixture is heated to 120°C and refluxed for 15 minutes, while the reaction process is monitored by thin-layer chromatography. After the reaction is completed, the mixture is cooled to room temperature, 25 mL of methanol is added to the reactants and filtered. Hydrochloric acid is added to the resulting dark green filtrate for acidification. A yellowish-brown precipitate appears in the reaction solution. These precipitates are filtered and purified by column chromatography (petroleum ether PE: ethyl acetate EA = 100:0-20:1) to obtain the target product, namely probe IND-2.
[0009] The application of this probe in the detection of polar component content in edible oils, specifically, involves the following detection steps:
[0010] (1) The probe prepared in this invention is added to chromatographically pure 1,4-dioxane and sonicated to completely dissolve it, thus obtaining a probe stock solution; the probe stock solution is added to edible oils with different polar component contents (polarity range of 13.9%-29.3%, such as TPM%=13.9%, 21.5%, 26.9%, 29.3%) and mixed thoroughly to obtain a concentration gradient of standard solutions; the absorption intensity A of the standard solutions at 778 nm is measured. 778 nm And establish the polar component content and absorption intensity A 778 nm The standard curve;
[0011] (2) Add the probe stock solution to the edible oil to be tested to obtain the detection solution; measure the absorption intensity A of the detection solution at 778 nm. 778 nm and A 778 nm Substitute this information into the standard curve of step (1) to achieve quantitative detection of the polar component content of edible oil.
[0012] Furthermore, in steps (1) and (2) above, the concentration of the probe stock solution is 0.5 mmol / L, and the final concentration of the probe in the standard solution and the detection solution is 100 µM.
[0013] An application of a probe in the colorimetric detection of polarity content in edible oils. The probe's structural formula is as follows: .
[0014] Specifically, the process in the above detection is as follows: after the probe prepared in this invention is introduced into edible oil, the system exhibits a significant color change. The "Colorimetric Titration" application is then used to automatically analyze the solution color and generate a polarity-ΔRGB standard curve, thereby achieving colorimetric detection of the polarity content of the edible oil.
[0015] A device for detecting polar components in edible oil includes a housing, a sample cell, an Arduino UNO R3 controller, a TCS 34725 color sensor, an LCD 12864 display, and a lithium battery, all housed within the housing. The TCS 34725 color sensor is mounted directly above the sample cell, with a built-in white LED illuminating the reaction solution within the sample cell. Its photosensitive surface faces the reaction solution (containing probe IND-2 and the edible oil to be tested), and it is used to acquire RGB color data. The lithium battery is connected to the Arduino UNO R3 controller, which is connected to both the LCD 12864 display and the TCS 34725 color sensor.
[0016] The device works as follows: When probe IND-2 is added to edible oil, the solution color changes systematically with the TPM content. The TCS 34725 sensor, with its built-in white LED light source, simulates standard lighting conditions and directly reads the RGB color values of the solution, ensuring stable and repeatable color signals under different environments, greatly improving the applicability and reliability of on-site testing. The device automatically performs color recognition and data processing, and makes a judgment based on a preset threshold (the safe upper limit for TPM in edible oil in my country is 27%): if TPM ≤ 27%, the screen displays "Oil Quality: good"; if TPM > 27%, it displays "Oil Quality: bad".
[0017] The beneficial effects of this invention are:
[0018] (1) This invention designs and synthesizes a novel polar-responsive fluorescent probe, IND-2. The optical properties of this probe are highly correlated with the polarity of the microenvironment: in low-polarity solutions, its central carbon atom exhibits sp2 polarity. 3 Hybridization, with maximum absorption at 388 nm, results in an overall yellow solution color; however, in highly polar environments, the central carbon atom transforms into sp... 2 Hybridization causes the molecules to form an extended π-conjugated system, resulting in a red shift of the maximum absorption peak to 778 nm, and the overall solution color turning green. This absorption at this wavelength effectively avoids interference from the self-absorption of edible oils in the shorter wavelength region.
[0019] (2) This invention utilizes the relationship between the absorption intensity of the probe at 778 nm and the TPM content in edible oil to plot a working curve, enabling quantitative detection of TPM (13.9%-29.3%) in edible oil. Based on its obvious solution color change, a colorimetric detection method was established using the Colorimetric Titration mobile application. This software can automatically fit the working curve and directly calculate the TPM value of unknown samples by analyzing their color parameters, achieving rapid quantitative detection.
[0020] (3) This invention also developed a portable edible oil safety tester. When in use, simply place the sample cuvette into the test chamber, and the instrument will automatically complete color recognition and judgment, displaying the result as "good" or "bad" on the screen. This integrated system is simple to operate and provides intuitive results, offering a reliable technical solution for rapid on-site screening of edible oils. Attached Figure Description
[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0022] Figure 1 The nuclear magnetic resonance H-spectrum of the probe IND-2 prepared for this invention 1 H NMR (600 MHz, CDCl3).
[0023] Figure 2 The nuclear magnetic resonance H-spectrum of the probe IND-2 prepared for this invention 1 H NMR (600 MHz, DMSO-d6).
[0024] Figure 3 The image shows the nuclear magnetic resonance mass spectrum of the probe IND-2 prepared in this invention.
[0025] Figure 4 The UV-Vis absorption spectra of probe IND-2 (5 μM) in DIOX-DMSO with different proportions are shown in (A), the color changes in DIOX-DMSO with different proportions are shown in (B), and the absorbance at 778 nm as a function of Δf is shown in (C).
[0026] Figure 5 The stability of probe IND-2 in DMSO over time (0–1000 s) is shown in (A), and the absorption intensity at 778 nm in the interference system is shown in (B).
[0027] Figure 6 The presence of probe IND-2 in soybean oil with different TPMs is shown in (A), the absorption spectrum (B), and the linear relationship between absorbance at 778 nm and TPM content (C).
[0028] Figure 7 A schematic diagram of the mobile phone colorimetric testing process (A) and a TPM working curve generated based on the mobile phone software (B).
[0029] Figure 8This is a schematic diagram of the structure for digitally detecting the safety and quality of edible oils according to the present invention. Detailed Implementation
[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0031] Example 1
[0032] The probe synthesis route in this embodiment is as follows:
[0033]
[0034] The specific preparation method and steps are as follows:
[0035] Accurately weigh 1,3-indanedione (1.00 g, 6.85 mmol / L) and 3 mL of pyridine into a dry round-bottom flask. Heat the mixture to 120 °C and reflux for 15 minutes, while monitoring the reaction process using thin-layer chromatography. After the reaction is complete, cool to room temperature, add 25 mL of methanol to the reactants and filter. Acidify the resulting dark green filtrate with hydrochloric acid. A yellowish-brown precipitate appears in the reaction solution. Filter the precipitate and separate and purify it by column chromatography (PE:EA = 100:0→20:1) to obtain the target product, probe IND-2. 1 ¹H NMR (600 MHz, CDCl₃) δ 9.83 (dd, J = 6.0, 3.3 Hz, 2H), 8.03–8.00 (m, 4H), 7.83–7.79 (m, 6H), 5.23 (s, 2H). High-resolution mass spectrometry: HR-MS (TOF, m / z): calcd. for C 27 H 14 O4: 402.41 [MH]-, found 401.083 ( Figure 1-3 ).
[0036] like Figure 1 and 2 As can be seen from this, in a highly polar environment (highly polar solvent (DMSO-d6)), the probe undergoes a deprotonation transformation, and its central carbon atom of the five-membered ring contains only one H atom, causing this carbon atom to change from sp... 3 Hybridization transforms into sp 2Hybridization leads to the formation of a more extended conjugated system. This solvent polarity-driven reversible structural transition explains, at the molecular level, the spectral and color responses of probe IND-2 to the polarity of the medium. Furthermore, density functional theory (DFT) calculations were performed on probe IND-2, revealing a HOMO-LUMO band gap of 3.39 eV.
[0037] Implementation Results Example
[0038] Accurately weigh the solid IND-2 probe and place it in a 20 mL sample vial. Add 10,000 mL of chromatographically pure 1,4-dioxane and sonicate until completely dissolved to prepare a probe stock solution with a concentration of 0.5 mmol / L. Store the stock solution in a cool, dark place.
[0039] 1. Probe polarity response test
[0040] Different ratios of DIOX and DMSO were prepared using chromatographically pure organic solvents to create a series of mixed solutions containing varying DMSO concentrations: 0%, 5%, 10%, 12.5%, 15%, 17.5%, 20%, 40%, 60%, 80%, 90%, and 100% DMSO. Then, 10 μL of IND-2 probe stock solution (0.5 mmol / L) was accurately pipetted into each mixed solution to obtain a 5 µmol / L test solution. These solutions were then placed in quartz cuvettes for subsequent spectral analysis. The absorbance at 778 nm was recorded as a function of polarity. The results are shown below. Figure 4 As shown, it can be seen that with the increase of solvent polarity, the maximum absorption peak of probe IND-2 redshifts from 388 nm to 778 nm. Figure 4 A), its color changed from light yellow to light green. Figure 4 B), and its polar response range (Δf) is a relatively low range of 0.19 to 0.22. Figure 4 C).
[0041] 2. Probe photostability and anti-interference performance
[0042] Accurately transfer 10 μL of probe stock solution (concentration 0.5 mmol / L) into a 2 mL DMSO cuvette and mix thoroughly. Then, under constant temperature conditions, perform continuous kinetic scans of the mixture using a UV-Vis spectrophotometer for 15 minutes. During the experiment, the instrument automatically acquires the full-wavelength spectrum and records the absorbance of the probe at its characteristic absorption wavelength of 778 nm over time to analyze its stability behavior in this highly polar solvent. The results are as follows: Figure 5As shown in Figure A, it can be seen that the probe IND-2 exhibits high stability in DMSO within the range of 0-1000 s.
[0043] To assess the potential interference of common coexisting substances in edible oils on probe detection performance, different additives were incorporated into edible oil with a TPM of 1.1%, according to the upper limit of the national standard method. These additives were butylated hydroxyanisole (0.2 g / kg), butylated hydroquinone (0.2 g / kg), butylated hydroxytoluene (0.2 g / kg), lutein (0.05 g / kg), chlorophyll (0.002 g / kg), oleic acid (300 g / kg), palmitic acid (135 g / kg), glycerol (2.5 g / kg), and propyl gallate (0.1 g / kg). 200 μL of the stock solution was added to the above oil-additive mixture, and the absorption spectrum was measured. By measuring the absorbance of the probe at 778 nm in this system, it was found that its signal was basically consistent with that of the blank oil sample (TPM=1.1%), and significantly lower than that of the deteriorated oil sample (TPM=29.3%). This indicates that the optical response of the probe mainly comes from the change in TPM and is almost unaffected by common coexisting substances, demonstrating good selectivity and practical application potential. Figure 5 B).
[0044] 3. Detection of TPM content in edible oils using probes
[0045] 400 μL of probe stock solution (0.5 mmol / L) was added to soybean oil with different polar component contents (TPM% = 13.9%, 21.5%, 26.9%, 29.3%) and mixed thoroughly to prepare a 2,000 mL mixed solution. The final 100 µM test solution was then placed in a quartz cuvette for subsequent spectral analysis. The results are as follows: Figure 7 As shown. The probe IND-2 exists in the keto form at low TPM, and in the enol form at high TPM. Figure 6 A). The absorption peak at 778 nm significantly increased with increasing TPM (13.9%-29.3%) in the edible oil. Figure 6 B). Based on the above linear relationship, the quantitative working curve is obtained by fitting: y = 0.01824x - 0.21315 ( Figure 6 C). The corresponding polarity response range is 0.19 to 0.22, which also indicates that although the TPM of edible oil varies over a wide range, the corresponding medium polarity parameter Δf varies over a relatively narrow range and usually does not exceed 0.22.
[0046] To test the accuracy of the probe IND-2 working curve method, edible oil samples with different TPMs were used, and the TPM values of the three edible oil samples were determined using both the national standard method and the working curve method.
[0047] Table 1. TPM detection results of edible oils based on probe IND-2
[0048]
[0049] a According to the test results of GB 5009.202-2016 (column chromatography)
[0050] b Determination was performed using the absorbance method.
[0051] Table 1 shows that the recovery rate of the working curve method is 89.84%-102.07%. These results indicate that the IND-2 probe is an efficient and reliable TPM detection tool for edible oils, with good application potential in the field of food safety monitoring.
[0052] 4. Probe-based digital TPM detection device for edible oils
[0053] ①. Mobile phone colorimetric testing
[0054] 1) Add 400 μL of probe stock solution (0.5 mmol / L) to soybean oil with different polar component contents (TPM% = 1.1%, 6.1%, 13.9%, 21.5%, 26.9% and 29.3%) and mix thoroughly to prepare a 2.000 mL mixed solution, and finally obtain a 100 µM test solution to obtain solutions with different colors;
[0055] 2) Use the "Colorimetric Titration" application to automatically analyze the solution color and generate calibration curves.
[0056] To verify the accuracy of this method, known standard oil samples of TPM (1.1%, 6.1%, 13.9%, 21.5%, 26.9%, and 29.3%) were selected as known samples. The working curve obtained by software analysis was y = 0.223x - 36.88. Figure 7 The working curve showed good accuracy when used in actual sample testing; for example, when testing an oil sample with a TPM of 26.9%, the result was 25.994%.
[0057] ②. Detection device
[0058] To achieve rapid, portable on-site testing of edible oil safety and quality, this invention designs a device for detecting polar components in edible oil based on microcontroller embedded development and 3D printing technology. Figure 8 As shown.
[0059] A device for detecting polar components in edible oil includes a housing, a sample cell, an Arduino UNO R3 controller, a TCS 34725 color sensor, an LCD 12864 display, and a lithium battery, all housed within the housing. The TCS 34725 color sensor is mounted directly above the sample cell, with its built-in white LED illuminating the reaction solution within the cell. The photosensitive surface faces the reaction solution (containing probe IND-2 and the edible oil to be tested), and is used to acquire RGB color data. The lithium battery is connected to the Arduino UNO R3 controller, which is connected to both the LCD 12864 display and the TCS 34725 color sensor. The device operates as follows: when probe IND-2 is added to the edible oil, the solution color changes systematically with the TPM content. The TCS34725 sensor's built-in white LED light source simulates standard lighting conditions and directly reads the RGB color values of the solution, ensuring stable and repeatable color signals under different environments, greatly improving the applicability and reliability of on-site testing.
[0060] Specifically, the housing of the detection device is made of polylactic acid (PLA) and formed using 3D printing technology. As a bio-based biodegradable material, PLA not only has good mechanical strength and dimensional stability, but also excellent chemical corrosion resistance, and can withstand contact with edible oils and common solvents. This ensures that the housing is not easily deformed, aged, or damaged during long-term repeated use, thus guaranteeing the durability and reliability of the instrument.
[0061] In terms of control and data processing, the system is based on an open-source hardware platform for embedded development. The main control unit uses an Arduino microcontroller and the program is written through the Arduino IDE.
[0062] The program written using Anduino-IDE is shown below:
[0063] void setup() {
[0064] / / Initialize serial communication
[0065] Serial.begin(9600);
[0066] / / Initialize LCD
[0067] u8g2.begin();
[0068] u8g2.setFont(u8g2_font_ncenB08_tr); / / Sets the font; other fonts can be selected as needed.
[0069] u8g2.clearBuffer(); / / Clear the buffer
[0070] u8g2.drawStr(0, 60, "1");
[0071] / / Set the gain and integration time (adjustable as needed)
[0072] colorSensor.setGain(TCS34725_GAIN_4X); / / Gain, select a higher gain to improve the sensor's sensitivity.
[0073] colorSensor.setIntegrationTime(TCS34725_INTEGRATIONTIME_50MS); / / Integration time, 50ms for faster response time
[0074] }
[0075] void loop() {
[0076] / / Get the values of the RGB color channels
[0077] uint16_t clear, red, green, blue;
[0078] colorSensor.getRawData(&red, &green, &blue, &clear);
[0079] / / Print raw data to serial monitor
[0080] Serial.print("R: ");
[0081] Serial.print(red);
[0082] Serial.print("\tG: ");
[0083] Serial.print(green);
[0084] Serial.print("\tB: ");
[0085] Serial.print(blue);
[0086] Serial.print("\tC: ");
[0087] Serial.println(clear);
[0088] / / Use the value of the red channel to determine the light intensity
[0089] / / At 660nm, red light is mainly concentrated in the red channel, so the red value can be used directly.
[0090] u8g2.clearBuffer(); / / Clear the display buffer
[0091] u8g2.begin(); / / Move the cursor to the first line
[0092] u8g2.drawStr(0, 20, "Soybean oil inspection.");
[0093] u8g2.drawStr(50, 50, "Soybean oil quality.");
[0094] if (red > 100) {
[0095] / / Displays "good"
[0096] u8g2.drawStr(100, 50, "good");
[0097] }
[0098] else {
[0099] / / Displays "bad"
[0100] u8g2.drawStr(80, 50, "bad");
[0101] }
[0102] u8g2.sendBuffer(); / / Refresh screen display
[0103] delay(500); / / Update the display every 500ms
[0104] }
[0105] This programming method is flexible and efficient, realizing a fully automated process from color signal acquisition and data processing to result output. Repeated testing of normal soybean oil and soybean oil with TPM > 27% revealed that the system software primarily identifies the R-value of the solution color in the cuvette. When the test sample was normal soybean oil, the R-value was less than 100. When the test sample was soybean oil with TPM > 27%, the R-value was greater than 100.
[0106] The specific detection procedure is designed as follows: Accurately measure 2 mL of the edible oil sample to be tested using a pipette, add 400 μL of probe IND-2 stock solution (0.5 mmol / L), and gently shake to ensure thorough mixing and reaction. Then, place the cuvette stably into the designated sample slot of the instrument. The device will automatically trigger the detection program. The built-in high-sensitivity color sensor (TCS34725) captures the solution color information under the illumination of the integrated light source. After real-time processing and analysis by the microcontroller, the results are directly displayed on the integrated screen. The device automatically performs color recognition and data processing, and makes a judgment based on a preset threshold (the safe upper limit of TPM for edible oil in my country is 27%): if TPM ≤ 27%, the screen displays "Oil Quality: good"; if TPM > 27%, it displays "Oil Quality: bad".
[0107] To verify the repeatability and practicality of the device, qualified soybean oil from several commercially available brands (such as Jinlongyu and Luhua) was tested, and all results correctly displayed "good". Further verification was performed using oil samples with a TPM exceeding the standard of 29.3%, and the device consistently output a "bad" message. This indicates that the device has good accuracy and stability.
[0108] 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. The application of a probe in the detection of polar component content in edible oils, characterized in that, The structural formula of the probe is as follows: 。 2. The application according to claim 1, characterized in that, The probe was prepared by adding 1,3-indanedione to pyridine, heating to 120°C and refluxing for 15 min, while monitoring the reaction process using thin-layer chromatography; after the reaction was completed, cooling to room temperature, adding methanol for filtration, adding acid to the filtrate to generate a yellow-brown precipitate, and obtaining the probe by separation and purification.
3. The application according to claim 2, characterized in that, Each L of pyridine requires 2.28 mol of 1,3-indanedione.
4. The application according to claim 1, characterized in that, The testing steps are as follows: (1) Add the probe stock solution to edible oils with different polar component contents and mix thoroughly to obtain a concentration gradient of standard solutions to be tested; measure the absorption intensity A of the standard solutions to be tested at 778 nm. 778 nm And establish the polar component content and absorption intensity A 778 nm The standard curve; (2) Add the probe stock solution to the edible oil to be tested to obtain the detection solution; measure the absorption intensity A of the detection solution at 778 nm. 778 nm and A 778 nm Substitute this information into the standard curve of step (1) to achieve quantitative detection of the polar component content of edible oil.
5. The application according to claim 4, characterized in that, In steps (1) and (2), the concentration of the probe stock solution is 0.5 mmol / L.
6. The application according to claim 4, characterized in that, In steps (1) and (2), the final concentration of the probe in the standard solution and the detection solution is 100 µM.
7. The application according to claim 4, characterized in that, The polarity range of the edible oil is 13.9%-29.3%.
8. The application of a probe in the colorimetric detection of polarity content in edible oils, characterized in that, The structural formula of the probe is as follows: 。 9. A device for detecting polar components in edible oils, characterized in that, The device includes a housing, and within the housing are a sample chamber, an Arduino UNO R3 controller, a TCS 34725 color sensor, an LCD 12864 display, and a lithium battery. The TCS34725 color sensor is mounted directly above the sample chamber, with a built-in white LED illuminating the reaction solution inside. Its photosensitive surface faces the reaction solution to acquire RGB color data. The lithium battery is connected to the Arduino UNO R3 controller, which in turn is connected to both the LCD 12864 display and the TCS 34725 color sensor. The reaction solution contains a probe and the edible oil to be tested. The probe's structure is as follows: 。 10. The edible oil polar component detection device according to claim 9, characterized in that, The reaction solution was obtained by mixing 2 mL of the oil sample to be tested with 0.5 mmol / L, 400 μL of probe stock solution.