Patent Application
20240230542
The present disclosure belongs to the technical field of safety detection for agricultural products, and in particular relates to a method for highly-sensitive and rapid detection of a pesticide residue based on an imprinted metal-organic framework (MOF) probe.
The extensive use of pesticides can effectively control the infestation of pests and diseases during the growth of crops. However, due to difficult degradation, strong toxicity, easy residues, and other disadvantages, pesticides are easy to accumulate in agricultural products, soil, and water sources, causing a great threat to the ecological environment and human health. Therefore, the detection of pesticide residues is very important. The current methods for detecting pesticide residues mainly include traditional methods such as high-performance liquid chromatography (HPLC) and liquid chromatography-mass spectrometry (LC-MS) and rapid detection methods such as electrochemical method, Raman method, and fluorescence method emerging in recent years. However, these methods have high detection sensitivity and high result accuracy, usually need to be conducted under laboratory conditions, involve a large reagent consumption, rely on special equipment, and require operators to have a high technical level, which makes it difficult to meet the needs of on-site and rapid detection of a pesticide residue. Therefore, it is particularly important to develop a portable method for in-situ monitoring and rapid field analysis.
Recently, the existing colorimetric probe detection methods for pesticide residues have the following deficiencies: 1. The existing finished test strips do not allow the timely adjustment of analysis parameters according to implementation conditions. Because the colorimetric analysis method is easily affected by surrounding environment factors such as temperature, humidity, and light, a test strip may have inaccurate signal output. 2. When a sample to be tested has a too-high or too-low concentration, the existing test strips are prone to large errors. 3. A color of an actual sample itself will interfere with a colorimetric signal to varying degrees. Without the use of a special instrument, it is impossible to achieve the accurate quantitative analysis of a target by determining a color change only with naked eyes and a colorimetric card. Due to the above factors, the colorimetric analysis methods are limited to qualitative and semi-quantitative detection, and can hardly be used for low-cost, high-sensitivity, and anti-interference detection of a target in a complex matrix sample.
In summary, it is a key and difficult task to develop a colorimetric analysis method that can be adapted to local conditions to achieve the sensitive and accurate analysis of a pesticide residue in a complex matrix sample without the aid of a special instrument.
In view of the deficiencies in the prior art, the present disclosure constructs a colorimetric test strip for highly-sensitive and rapid detection of a pesticide residue based on an imprinted MOF enzyme-mimic probe. A molecularly imprinted MOF enzyme-mimic probe is used as a colorimetric probe to catalyze the oxidation of a substrate, thereby enabling a color change of a system; and a low-cost filter paper is used as a substrate for supporting the colorimetric probe, including a zone A, a zone B, and a zone C, where the zone A is a quality control zone, the zone B is a standard zone, and the zone C is a detection zone. In the quality control zone, optimal colorimetric analysis parameters can be selected according to the temperature, humidity, and light, etc. of an environment to be tested; the standard zone is a standard colorimetric zone obtained through the dropwise addition of standards with different concentrations under the analysis conditions optimized in the quality control zone and is provided to establish a colorimetric analysis mathematical model; and the detection zone is provided for the detection of an actual sample. It should be noted that, before an actual sample is detected, a color change of the detection zone is observed in contrast to the standard zone, a concentration range of a pesticide residue in a test sample is preliminarily determined, and then a sample with a too-high or low-low pesticide residue concentration is adjusted to meet the requirements of accurate analysis; and then a smartphone is used to stably capture a color signal (RGB value) of a reaction system, and a colorimetric analysis mathematical model is established by calculating a Gray value to eliminate the interference of a color of the test sample itself on an end point color, thereby achieving the sensitive, accurate, real-time, and quantitative analysis of trace pesticide residues in multiple complex matrix samples.
In order to achieve the above objective of the present disclosure, the present disclosure adopts the following technical solutions.
The present disclosure provides a colorimetric test strip for high-sensitive and rapid detection of a pesticide residue based on an imprinted MOF probe. The colorimetric test strip is constructed by directly adding the imprinted MOF probe dropwise, and is divided into a quality control zone, a standard zone, and a detection zone. A zone A is the quality control zone configured to optimize the colorimetric analysis parameters in an on-site test environment; a zone B is the standard zone configured to detect a standard, where an RGB value is acquired through a camera function of a smartphone and a Gray value is calculated to establish a colorimetric analysis mathematical model; and a zone C is the detection zone, where a color change of the detection zone is observed in contrast to the standard zone, a concentration range of a pesticide residue in a test sample is preliminarily determined, and then a too-high or low-low pesticide residue concentration is adjusted to meet the requirements of accurate detection. The Gray value of the test sample is substituted into the colorimetric analysis mathematical model of the standard zone, thereby achieving the sensitive, accurate, and quantitative detection of a pesticide residue in a complex matrix sample.
The method specifically includes the following steps:
Further, in the step 1.1, the MOF, the APTES, the ammonia water, the pesticide standard, and the TEOS are used in a ratio of (400-700) mg:(10-30) μL:(2-10) mL:(10-20) mg:(5-15) mL; the ammonia water has a volume fraction of 5% to 15%; and the first stirring and the second stirring are each performed for 5 min to 15 min.
Further, in the step 1.1, the pesticide standard includes an insecticide, a miticide, a bactericide, and an herbicide, and is specifically any one selected from the group consisting of thiacloprid, omethoate, abamectin, pyridaben, folpet, captan, alachlor, and atrazine.
Further, in the step 1.2, the zone A, the zone B, and the zone C are in an area ratio of 2:1:2.
Further, in the step 2.1.1, the NY solution has a concentration of 2 μM, and NY is any one selected from the group consisting of thiacloprid, omethoate, abamectin, pyridaben, folpet, captan, alachlor, and atrazine; the reaction is carried out for 5 min to 10 min; the imprinted MOF enzyme-mimic probe solution has a concentration of 1 mg/mL to 3 mg/mL; the chromogenic reagent is a mixed solution of TMB, H2O2, and NaAc-HAC with a pH of 4.0; and in the chromogenic reagent, the TMB, the H2O2, and the NaAc-HAC with a pH of 4.0 are mixed in a ratio of (0.4 mL-0.8 mL):(0.4 mL-0.8 mL):(0.1 mL-0.8 mL), and a concentration ratio of the TMB to the H2O2 is 1:20 to 5:1.
Further, in the step 2.1.1, the volume V1, the volume V2, and the volume V3 are in a ratio of 1:1:1, and are each 10 μL to 20 μL.
Further, in the step 2.1.2, the imprinted MOF enzyme-mimic probe solution has a concentration of 1 mg/mL to 3 mg/mL; the reaction is carried out for 5 min to 15 min; the NY solution has a concentration of 2 μM, and the NY is any one selected from the group consisting of thiacloprid, omethoate, abamectin, pyridaben, folpet, captan, alachlor, and atrazine; the chromogenic reagent is a mixed solution of TMB, H2O2, and NaAc-HAC with a pH of 4.0; in the chromogenic reagent, the TMB, the H2O2, and the NaAc-HAC with a pH of 4.0 are mixed in a ratio of (0.4 mL-0.8 mL):(0.4 mL-0.8 mL):(0.1 mL-0.8 mL), and a concentration ratio of the TMB to the H2O2 is 1:20 to 5:1; and the volume V4, the volume V5, and the volume V6 are in a ratio of 1:1:1, and are each 10 μL to 20 μL.
Further, in the step 2.1, a calculation equation of the gray value is as follows:
Further, in the step 2.2, the NY solutions with different concentrations are in a concentration range of 0 μM to 20 μM; and the NY is any one selected from the group consisting of thiacloprid, omethoate, abamectin, pyridaben, folpet, captan, alachlor, and atrazine.
Further, in the step 2.2, the first reaction and the second reaction are each carried out for 5 min to 10 min.
Further, in the step 2.2, the volume V7, the volume V8, and the volume V9 are in a ratio of 1:1:1, and are each 10 μL to 20 μL.
Further, in the step 2.4, the volume V10, the volume V11, and the volume V12 are in a ratio of 1:1:1, and are each 10 μL to 20 μL.
Further, in the step 2.4, the reaction is carried out for 5 min to 10 min.
Further, in the step 2.4, the sample is pretreated as follows: crushing the sample first, conducting extraction with acetonitrile and rotary evaporation, and then dissolving a residue in water to obtain the test sample solution.
Further, in the step 2.5, the reaction is carried out for 5 min to 10 min.
The present disclosure also provides use of a standard colorimetric card prepared by the above method in the detection of a pesticide residue in an actual sample.
Compared with the Prior Art, the Present Disclosure has the Following Beneficial Effects.
(1) The imprinted MOF enzyme-mimic probe of the present disclosure has a pesticide-specific recognition site, which effectively overcomes the interference of other components in a complex matrix sample.
(2) The colorimetric test paper of the present disclosure can be prepared by directly adding an imprinted MOF enzyme-mimic probe solution dropwise to an ordinary filter paper without the technical assistance such as specific printing and etching, which has advantages such as low cost, simple operations, and strong practicability.
(3) In the present disclosure, a low-coat filter paper is used as a substrate, an MOF is used to catalyze the oxidation of the substrate for color development, and a color signal is acquired through a camera function of a smartphone, which does not require special instruments such as a fluorescence excitation light source and a signal acquisition device and thus can achieve the convenient, on-site, and visual colorimetric detection of a pesticide residue in a field environment where resources are scarce.
(4) The color development of the MOF-catalyzed substrate designed in the present disclosure can be realized within 5 min, and the color developed can be maintained for 20 min, which can meet the requirements of rapid color development and stable color acquisition.
(5) In the present disclosure, the colorimetric test paper is divided into a quality control zone, a standard zone, and a detection zone. The quality control zone is configured to screen the optimal colorimetric analysis parameters on site, thereby effectively overcoming the measurement errors caused by differences of analysis environments. A color of the detection zone can be compared with a color of the standard zone to preliminarily determine a concentration range of a pesticide residue in a test sample, and then a too-high or too-low concentration is adjusted to meet the needs of accurate determination, which improves the detection accuracy to a large extent. An RGB value can be extracted by a smartphone and a Gray value thereof can be calculated to overcome the influence of a color of a test sample itself on a colorimetric signal, which further improves the reliability of sensor analysis.
In
The present disclosure will be further described below in conjunction with the accompanying drawings and specific examples, but the protection scope of the present disclosure is not limited thereto.
With the detection of thiacloprid as an example, a colorimetric test paper for rapid detection of thiacloprid was prepared.
Step 1: Preparation of a colorimetric test paper, mainly including: synthesis of an imprinted MOF enzyme-mimic probe, preparation of a blank filter paper, and construction of a colorimetric sensing interface.
Step 1.1: Preparation of an imprinted MOF enzyme-mimic probe (an imprinted MOF enzyme-mimic probe capable of specifically recognizing thiacloprid): 500 mg of an MOF and 20 μL of APTES were dissolved in 2 mL of 10% ammonia water to obtain a mixed solution, then 10 mg of thiacloprid was added to the mixed solution, and the resulting mixture was stirred for 5 min; and 5 mL of TEOS was added, the resulting mixture was stirred and centrifuged, and the resulting precipitate was washed and dried to obtain the imprinted MOF enzyme-mimic probe.
Step 1.2: Preparation of a blank filter paper: A cheap ordinary filter paper was divided into a zone A, a zone B, and a zone C, where the zone A was a quality control zone, the zone B was a standard zone, and the zone C was a detection zone; and the zone A, the zone B, and the zone C were in an area ratio of 2:1:2.
Step 1.3: Construction of a colorimetric sensing interface: 10 μL of an ultrasonically-homogenized imprinted MOF enzyme-mimic probe solution was directly added dropwise to the quality control zone on the blank filter paper, and the quality control zone was allowed to be dried, which were simple operations without procedures such as printing. The quality control zone was equally divided into a quality control subzone 1 and a quality control subzone 2. The quality control subzone 1 was equally divided into 3 zones from left to right (namely, 3 columns) that were denoted as H1, H2, and H3, respectively; and the quality control subzone 2 was also equally divided into 3 zones from left to right (namely, 3 columns) that were denoted as I1, I2, I3, respectively.
Step 2.1: Establishment of the quality control zone:
Step 2.1.1: Determination of the optimal concentration of an imprinted MOF enzyme-mimic probe solution
Imprinted MOF enzyme-mimic probe solutions with concentrations of 1 mg/mL, 2 mg/mL, and 3 mg/mL were taken, numbered as 1, 2, and 3, and added each in a volume of 10 μL dropwise to the zones H1, H2, and H3 of the quality control subzone 1, and the zones were allowed to be dried; then thiacloprid was added to water to obtain a thiacloprid standard solution; 10 μL of a 2 μM thiacloprid standard solution was added dropwise to each of H1, H2, and Ha of the quality control subzone 1, a reaction was carried out for 10 min, and then 10 μL of a chromogenic reagent (including TMB, hydrogen peroxide (H2O2), and NaAc-HAC with a pH of 4.0) was then added dropwise; an image of each zone was acquired, and a gray value was further calculated according to a corresponding RGB value; and a concentration of the imprinted MOF enzyme-mimic probe solution corresponding to a zone with the largest gray value was determined as the optimal concentration of the imprinted MOF enzyme-mimic probe solution. In this case, the optimal concentration of the imprinted MOF enzyme-mimic probe solution was 3 mg/mL.
Step 2.1.2: Determination of an optimal chromogenic reagent concentration:
10 μL of a 3 mg/mL imprinted MOF enzyme-mimic probe solution was added dropwise to each of I1, I2, and I3 of the quality control subzone 2, and the zones were allowed to be dried; 10 μL of a 2 μM thiacloprid standard solution was added dropwise to each of I1, I2, and I3 of the quality control subzone 2, a reaction was carried out for 10 min, and chromogenic reagents with different concentrations were added each in a volume of 10 μL dropwise (with a concentration ratio of TMB to H2O2 as a basis for determination, the following specific 3 groups were set: 1:20, 1:2, and 5:1); an image of each zone was acquired, and a gray value was further calculated according to a corresponding RGB value; and a chromogenic reagent concentration corresponding to a zone with the largest gray value was determined as the optimal chromogenic reagent concentration, where a chromogenic reagent with the optimal concentration was a mixed solution including 0.4 mL of TMB (0.05 M), 0.1 mL of H2O2 (10 M), and 0.5 mL of NaAc-HAC with a pH of 4.0 (0.1 M).
Step 2.2: Establishment of the standard zone:
According to the optimization results in the step 2.1, the standard zone was divided into 6 zones from top to bottom that were denoted as E1, E2, E3, E4, E5, and E6, respectively; with the optimal concentration of the imprinted MOF enzyme-mimic probe solution determined in the step 2.1.1, 10 μL of a 3 mg/mL imprinted MOF enzyme-mimic probe solution was added dropwise to a surface of each of E1, E2, E3, E4, E5, and E6 of the standard zone, and the zones were allowed to be dried; thiacloprid standard solutions with concentrations of 0 μM, 0.3 μM, 0.5 μM, 1.2 μM, 2 μM, and 8 μM were prepared, denoted as C1, C2, C3, C4, C5, and C6, and added each in a volume of 10 μL dropwise to E1, E2, E3, E4, E5, and E6, respectively, and a reaction was carried out for 10 min; and then with the optimal chromogenic reagent concentration obtained in the step 2.1.2 (the chromogenic reagent was a mixed solution including 0.4 mL of TMB (0.05 M), 0.1 mL of H2O2 (10 M), and 0.5 mL of NaAc-HAC with a pH of 4.0 (0.1 M)), 10 μL of the chromogenic reagent was added dropwise to each of E1, E2, E3, E4, E5, and E6, and a reaction was carried out for 10 min to establish a standard colorimetric card for the standard zone. A color of the standard colorimetric card for the standard zone remained unchanged for 20 min or more, which reserved enough time for the subsequent preliminary determination of a concentration of a pesticide residue in the detection zone.
Step 2.3: Chromogenic images of different pesticide concentrations corresponding to the standard colorimetric card for the standard zone prepared in the step 2.2 were acquired through a camera function of a smartphone, and then the RGB values for different thiacloprid standard solution concentrations were analyzed through mobile phone software. RGB values for 0 μM, 0.3 μM, 0.5 μM, 1.2 μM, 2 μM, and 8 μM were {169, 192, 187}, {163, 181, 177}, {154, 173, 169}, {156, 171, 166}, {152, 168, 163}, and {149, 166, 159}, respectively.
corresponding Gray values G1=186.06, G2=167.91, G3=163.98, G4=161.83, G5=147.51, and G6=138.11 were obtained through calculation, a median M for the Gray values of the quality control zone was calculated as follows: (G3+G4)/2=162.9, and based on this, the optimal gray value for sample analysis was determined, that is, a discriminant value P was 162.9×(1±10%). In addition, according to a correlation between the Gray values of the standard zone and the thiacloprid standard solution concentrations, a colorimetric analysis mathematical model was established to be Y=−5.87 m+169.4 (m was in a range of 0.3 μM to 2 μM), with a detection limit of 0.134 μM.
Step 1.1: Green tea, dark tea, soil, apple, Romaine lettuce, and Indian lettuce were denoted as a test sample 1, a test sample 2, a test sample 3, a test sample 4, a test sample 5, and a test sample 6, pretreated, and subjected to extraction with acetonitrile and rotary evaporation, and resulting residues were each dissolved in water to obtain corresponding test sample solutions.
Step 1.2: Establishment of the detection zone:
The detection zone was evenly divided into 6 sample zones from left to right (namely, 6 columns) that were denoted as a sample zone 1, a sample zone 2, a sample zone 3, a sample zone 4, a sample zone 5, and a sample zone 6; the sample zone 1 was divided into 5 subzones that were denoted as 11, 12, 13, 14, and 15, respectively, the sample zone 2 was divided into 5 subzones that were denoted as 21, 22, 23, 24, and 25, respectively, the sample zone 3 was divided into 5 subzones that were denoted as 31, 32, 33, 34, and 35, respectively, the sample zone 4 was divided into 5 subzones that were denoted as 41, 42, 43, 44, and 45, respectively, the sample zone 5 was divided into 5 subzones that were denoted as 51, 52, 53, 54, and 55, respectively, and the sample zone 6 was divided into 5 subzones that were denoted as 61, 62, 63, 64, and 65, respectively; and with the optimal imprinted MOF probe concentration 3 mg/mL obtained in the step 2.1.1, 10 μL of a 3 mg/mL imprinted MOF enzyme-mimic probe solution was added dropwise to each of 5 subzones of each of the 6 sample zones of the detection zone, and the subzones were allowed to be dried, such that the detection zone was established.
Step 1.3: 10 μL of a test sample solution 1 obtained in the step 1.1 was added dropwise to a surface of each of the detection zones 11, 12, 13, 14, and 15 of the test strip in the step 1.2, 10 μL of a test sample solution 2 was added dropwise to a surface of each of the detection zones 21, 22, 23, 24, and 25 of the test strip in the step 1.2, 10 μL of a test sample solution 3 was added dropwise to a surface of each of the detection zones 31, 32, 33, 34, and 35 of the test strip in the step 1.2, 10 μL of a test sample solution 4 was added dropwise to a surface of each of the detection zones 41, 42, 43, 44, and 45 of the test strip in the step 1.2, 10 μL of a test sample solution 5 was added dropwise to a surface of each of the detection zones 51, 52, 53, 54, and 55 of the test strip in the step 1.2, and 10 μL of a test sample solution 6 was added dropwise to a surface of each of the detection zones 61, 62, 63, 64, and 65 of the test strip in the step 1.2; and a reaction was carried out for 10 min, and 10 μL of the chromogenic reagent with the optimal concentration was added to each of the above zones (the chromogenic reagent with the optimal concentration was a mixed solution of 0.5 mL of TMB, 0.4 mL of H2O2, and 0.1 mL of NaAc-HAC with a pH of 4.0, in which a concentration ratio of TMB to H2O2 was 1:20).
Step 1.4: After the chromogenic reagent was added dropwise in the step 1.3, a reaction was carried out for 5 min, then RGB values of different zones were acquired through photographing with a mobile phone, and corresponding Gray values are calculated. If a gray value was not within 162.9×(1±10%), the original sample needed to be adjusted, then the detection zone establishment in the step 2.4 was repeated, and then an RGB value was acquired through photographing with a mobile phone and a Gray value was calculated.
A color for sample 1 was compared with the standard zone, and a concentration range of a pesticide residue was preliminarily determined to be 0.5 μM to 1.2 μM; a picture was taken, and then a gray value of a chromogenic zone of sample 1 was calculated to be 163.5, which was within 162.9×(1±10%); and there was no need to adjust the pesticide residue concentration in sample 1, and thus the gray value 163.5 of sample 1 was directly substituted into the colorimetric analysis mathematical model to obtain a pesticide residue concentration of 0.4 μM.
A color for sample 2 was compared with the standard zone, and a concentration range of a pesticide residue was preliminarily determined to be 2 μM to 4 μM; a picture was taken, and then a gray value of a chromogenic zone of sample 2 was calculated to be 120.8, which was not within 162.9×(1±10%); it was preliminarily determined that the pesticide residue concentration was too high; and in order to ensure the accuracy, sample 2 was diluted 0.5 times, then a gray value thereof was further calculated to be 152.4 and substituted into the colorimetric analysis mathematical model to obtain a pesticide residue concentration of 1.3 μM, and the pesticide residue concentration in sample 2 was calculated as follows: 1.3 μM×2=2.6 μM.
A color for sample 3 was compared with the standard zone, and a concentration range of a pesticide residue was preliminarily determined to be 0 μM to 0.5 μM; a picture was taken, and then a gray value of a chromogenic zone of sample 3 was calculated to be 190.5, which was not within 162.9×(1±10%); it was preliminarily determined that the pesticide residue concentration was too low; and in order to ensure the accuracy, sample 3 was concentrated 5 times, then a gray value thereof was further calculated to be 145.8 and substituted into the colorimetric analysis mathematical model to obtain a pesticide residue concentration of 1.2 μM, and the pesticide residue concentration in sample 3 was calculated as follows: 1.2 μM+5=0.24 μM.
A color for sample 4 was compared with the standard zone, and a concentration range of a pesticide residue was preliminarily determined to be 0.5 μM to 1.2 μM; a picture was taken, and then a gray value of a chromogenic zone of sample 4 was calculated to be 166.5, which was within 162.9×(1±10%); and there was no need to adjust the pesticide residue concentration in sample 4, and thus the gray value 166.5 of sample 4 was directly substituted into the colorimetric analysis mathematical model to obtain a pesticide residue concentration of 0.5 μM.
A color for sample 5 was compared with the standard zone, and a concentration range of a pesticide residue was preliminarily determined to be 0.5 μM to 1.2 μM; a picture was taken, and then a gray value of a chromogenic zone of sample 5 was calculated to be 175.5, which was within 162.9×(1±10%); and there was no need to adjust the pesticide residue concentration in sample 5, and thus the gray value 175.5 of sample 5 was directly substituted into the colorimetric analysis mathematical model to obtain a pesticide residue concentration of 0.63 μM.
A color for sample 6 was compared with the standard zone, and a concentration range of a pesticide residue was preliminarily determined to be 0 μM to 0.5 μM; a picture was taken, and then a gray value of a chromogenic zone of sample 6 was calculated to be 150, which was within 162.9×(1±10%); and there was no need to adjust the pesticide residue concentration in sample 6, and thus the gray value 150 of sample 6 was directly substituted into the colorimetric analysis mathematical model to obtain a pesticide residue concentration of 0.32 μM.
In order to further verify the accuracy and sensitivity of the constructed test strip, the colorimetric sensing system of the present disclosure was compared with standard HPLC. Results were shown in Table 1. A relative standard deviation (RSD) of the detection results of the present disclosure is 3.4% to 5.8%, which is within an acceptable range; and the RSD value of the test strip detection method is slightly smaller than an RSD value of the standard method HPLC, indicating that the test strip detection method of the present disclosure can lead to relatively-stable results with excellent reproducibility.
The colorimetric array method has high sensitivity, excellent stability, and prominent specificity due to the following reasons: (1) The imprinted MOF enzyme-mimic probe of the present disclosure does not require the use of biomolecules such as antibodies and aptamers, and can be used for the specific recognition and in-situ catalysis of a target in a specific environment, thereby improving the detection sensitivity and the anti-interference ability of a sensing system. (2) The colorimetric analysis method of the present disclosure involves simple operation, and does not require special instruments such as a fluorescence excitation light source and a signal acquisition device. (3) The test strip of the present disclosure is divided into a quality control zone, a detection zone, and a standard zone, where the quality control zone is configured to select the optimal colorimetric parameters for on-site analysis, thereby effectively overcoming experimental errors caused by environmental differences; the standard zone is configured to establish a colorimetric analysis mathematical model and preliminarily determine a pesticide residue content in an actual sample, such that a too-high or too-low pesticide residue concentration can be adjusted to ensure the analysis accuracy; and an RGB value of an image can be acquired by a mobile phone, and a Gray value is calculated as a colorimetric signal, which effectively avoids the interference of a color of a sample itself on a detection result.
In summary, in the present disclosure, a molecularly imprinted MOF is used as a colorimetric probe to specifically recognize different pesticide residues and catalyze the oxidization of a substrate to allow a chromogenic reaction; and a colorimetric test strip is constructed with a low-cost filter paper and divided into a quality control zone, a standard zone, and a detection zone, where the quality control zone effectively overcomes the shortcoming that the existing test strip is prone to environmental interference; and the detection zone and the standard zone can be compared to preliminarily determine a pesticide residue content in an actual sample, such that a too-high or too-low pesticide residue concentration can be adjusted to ensure the analysis accuracy. In addition, an RGB color signal of a chromogenic system can be stably captured by a smartphone, and according to a correlation between the Gray values and the pesticide residue concentrations, the highly-sensitive and specific colorimetric analysis of a trace pesticide residue is realized. The colorimetric sensing analysis method has advantages such as high efficiency, high sensitivity, and prominent reliability, and provides a new technical support for field monitoring of a pesticide residue in a complex matrix such as an environment and an agricultural product.
The series of detailed description listed above are only specific illustration of feasible examples of the present disclosure, rather than limitation of the claimed scope of the present disclosure. All equivalent examples or changes made without departing from the technical spirit of the present disclosure should be included in the claimed scope of the present disclosure.
| Number | Date | Country | Kind |
|---|---|---|---|
| 202111494602.3 | Dec 2021 | CN | national |
This application is the national phase entry of International Application No. PCT/CN2021/140485, filed on Dec. 22, 2021, which is based upon and claims priority to Chinese Patent Application No. 202111494602.3, filed on Dec. 8, 2021, the entire contents of which are incorporated herein by reference.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/CN2021/140485 | 12/22/2021 | WO |
