Rapid detection system for screening atrazine in food sample

Abstract

The invention relates to the technical field of substance detection, in particular to a rapid detection system for screening atrazine in a food sample. The method comprises the following steps: at each sampling moment, respectively removing a background gray value of a test paper background region image from gray values in a detection band region image and a water absorption pad region image, sequentially obtaining the color development intensity of a detection band and the color development intensity of a water absorption pad, and obtaining the throughput of the detection band according to the color development intensity of the detection band and the color development intensity of the water absorption pad; dividing the detection zone into an upstream zone and a downstream zone, obtaining the color development intensity difference of the upstream zone and the downstream zone, and obtaining the blocking increase degree according to the change trend distribution of the color development intensity difference along with the throughput of the detection zone; and performing blocking detection according to the detection band throughput, the detection band color development intensity and the blocking increase degree at the final moment in sequence. According to the method, false positive caused by physical blockage and true positive caused by chemical inhibition can be effectively distinguished, and the detection accuracy is improved.

Description

Technical Field

[0001] This invention relates to the field of substance detection technology, and more specifically to a rapid detection system for screening atrazine in food samples. Background Technology

[0002] Agricultural food ingredients such as corn steep liquor and sugarcane juice often contain herbicide residues such as atrazine. Rapid on-site screening of these samples primarily relies on competitive lateral flow immunochromatography. In competitive detection mode, the target small molecule in the sample competes with the gold-labeled antibody to bind to the antigen on the detection band; the lighter the T-line (detection band), the higher the concentration of the target analyte in the sample. However, actual food matrices are typically highly viscous and contain a large number of suspended particles. These tiny particles, as they flow through the porous chromatographic membrane, create a deep filtration effect, gradually clogging the membrane pores. This non-specific physical blockage hinders fluid transport, reducing the total amount of gold-labeled complex reaching the detection band, also causing the T-line to lighten. Existing optical detection equipment typically only reads a single grayscale value at the reaction endpoint, unable to distinguish whether weak color development is caused by chemical competitive inhibition by atrazine or by physical blockage of matrix particles. This limitation leads to the misinterpretation of signal reduction caused by physical blockage as excessive atrazine in the detection of high-viscosity food samples, resulting in false positives and affecting screening accuracy. Summary of the Invention

[0003] To address the technical problem that existing technologies cannot analyze the impact of particulate physical blockage on atrazine detection results, leading to inaccurate detection, the present invention aims to provide a rapid detection system for screening atrazine in food samples. The specific technical solution adopted is as follows: This invention proposes a rapid detection system for screening atrazine in food samples, the system comprising: An optical data acquisition module is used to continuously acquire multiple frames of test strip images at the moment of liquid contact. The test strip images include images of the detection zone area, images of the test strip background area, and images of the absorbent pad area. The flow data quantization module is used to remove the background gray value of the test strip background area image from the gray values ​​of the detection strip area image and the absorbent pad area image at each sampling time, thereby obtaining the color intensity of the detection strip and the color intensity of the absorbent pad; and to obtain the flow rate of the detection strip at each sampling time based on the color intensity of the detection strip and the color intensity of the absorbent pad. The detection zone material change analysis module is used to divide the detection zone into upstream and downstream regions and obtain the color intensity difference between the upstream and downstream regions; based on the distribution of the color intensity difference with the change trend of the detection zone throughput at continuous sampling time, the degree of blockage growth is obtained. The color development detection module is used to perform blockage detection sequentially based on the detection band throughput, color development intensity, and blockage growth at the final moment.

[0004] Furthermore, the method for obtaining the background grayscale value includes: For each sampling time, the average gray value in the background area image of the test strip is taken as the background gray value at the corresponding sampling time.

[0005] Furthermore, the method for obtaining the colorimetric intensity of the detection band includes: For each sampling time, a first difference is obtained between the background gray value and the average gray value in the detection zone region image. If the first difference is greater than 0, the first difference is used as the color intensity of the detection zone; if the first difference is less than or equal to 0, the color intensity of the detection zone at the corresponding sampling time is set to 0.

[0006] Furthermore, the method for obtaining the color development intensity of the absorbent pad includes: For each sampling time, a second difference is obtained between the background gray value and the average gray value in the absorbent pad area image. If the second difference is greater than 0, the first difference is used as the color rendering intensity of the absorbent pad. If the first difference is less than or equal to 0, the color rendering intensity of the absorbent pad at the corresponding sampling time is set to 0.

[0007] Furthermore, the method for obtaining the detection band throughput includes: At each sampling moment, the sum of the color intensity of the detection strip and the color intensity of the absorbent pad is taken as the throughput of the detection strip.

[0008] Furthermore, the method for obtaining the degree of blockage growth includes: A two-dimensional coordinate system is constructed with the detection band throughput as the horizontal axis and the color intensity difference as the vertical axis. The data points in the two-dimensional coordinate system are divided into a first set of points and a second set of points according to the horizontal axis coordinates. On the horizontal axis, the second set of points is after the first set of points. The difference in the changing trend of data points between the second set of points and the first set of points is analyzed to obtain the degree of blockage growth.

[0009] Furthermore, the blockage detection is performed sequentially based on the detection band throughput, detection band color intensity, and blockage growth degree at the final time, including a three-level detection process. The three-level detection process includes: Level 1 detection process: If the throughput of the detection band at the final moment is less than the preset throughput threshold, the detection is invalid; otherwise, proceed to the Level 2 detection process. Secondary detection process: If the color intensity of the detection band at the final moment is not less than the preset color intensity threshold, a negative detection result is returned; otherwise, the tertiary detection process is initiated. The three-level detection process is as follows: if the degree of blockage growth is not less than the preset blockage threshold, a false positive detection result is reported; otherwise, a positive detection result is reported.

[0010] Furthermore, dividing the detection zone into an upstream region and a downstream region includes: The position of the C-line on the detection zone is determined, and the position of the T-line is determined according to a preset size based on the position of the C-line. The region to be analyzed is constructed with the T-line position as the center according to a preset analysis size, and the T-line position divides the region to be analyzed into the upstream region and the downstream region.

[0011] Furthermore, the method for obtaining the color intensity difference includes: The color intensity difference is obtained by subtracting the color intensity of the downstream region from the color intensity of the upstream region.

[0012] Furthermore, the step of analyzing the difference in the changing trends of data points between the second set of points and the first set of points to obtain the degree of congestion growth includes: A linear fit is performed on the data points in the first set of points to obtain a first fitting slope; a linear fit is performed on the data points in the second set of points to obtain a second fitting slope; the difference between the second fitting slope and the first fitting slope is taken as the degree of blockage growth.

[0013] The present invention has the following beneficial effects: This invention utilizes a flow data quantification module to acquire the color intensity of the detection strip and the absorbent pad in real time at each sampling moment, and combines the two to calculate the flow rate of the detection strip. Compared to traditional methods that rely solely on time or single-point intensity, this approach uses the sum of the detection strip's retention and the absorbent pad's cumulative amount as a measurement benchmark for material transport, eliminating the impact of flow rate fluctuations caused by differences in sample viscosity on the detection results, and providing a normalized physical scale for subsequent kinetic analysis.

[0014] Further, through the material change analysis module in the detection zone, the detection zone is subdivided into upstream and downstream regions, and the distribution of the color intensity difference between the two regions is continuously monitored as the throughput of the detection zone changes. This module can capture the deep filtration and pore blockage effect of particulate matter on the upstream side of the detection zone and quantify this microscale accumulation acceleration characteristic as the degree of blockage growth. Since chemical inhibition is usually uniformly distributed, while physical blockage has a front-end accumulation characteristic, this indicator effectively distinguishes the two different causes of weak color development.

[0015] Finally, the colorimetric detection module comprehensively utilizes the final detection band throughput, color intensity, and degree of obstruction growth to determine the stratification level. In suspected samples with weak color development, the system can specifically identify and eliminate false positive results caused by physical obstruction, thereby significantly improving the accuracy and anti-interference capability of rapid on-site screening with atrazine. Attached Figure Description

[0016] To more clearly illustrate the technical solutions and advantages 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.

[0017] Figure 1 This is a block diagram of a rapid detection system for screening atrazine in food samples, provided as an embodiment of the present invention. Detailed Implementation

[0018] To further illustrate the technical means and effects adopted by the present invention to achieve its intended purpose, the following, in conjunction with the accompanying drawings and preferred embodiments, details the specific implementation, structure, features, and effects of a rapid detection system for screening atrazine in food samples according to the present invention. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0019] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0020] The following description, in conjunction with the accompanying drawings, details a specific scheme for a rapid detection system for screening atrazine in food samples provided by the present invention.

[0021] Please see Figure 1 The diagram illustrates a block diagram of a rapid detection system for screening atrazine in food samples according to an embodiment of the present invention. The system includes an optical data acquisition module 101, a flow data quantification module 102, a substance change analysis module 103 in the detection zone, and a colorimetric detection module 104.

[0022] The optical data acquisition module 101 is used to continuously acquire multiple frames of test strip images at the moment of liquid contact. The test strip images include images of the detection zone area, the test strip background area, and the absorbent pad area. In this embodiment of the invention, the color depth presented on the optical image is used to characterize the substance quality; therefore, it is necessary to acquire images of each area on the test strip image to achieve accurate quantification.

[0023] It should be noted that the detection band area, test strip background area, and absorbent pad area can all be pre-marked in the test strip image during the image acquisition stage. Because the camera can be set to a fixed position during acquisition, meaning the image field of view remains fixed, and the test strip position also remains stationary, the detection band area, test strip background area, absorbent pad area, or other areas such as the escape zone can be directly delineated in the test strip image using preset positions. The test strip background area is a pre-sized blank membrane area upstream or to the side of the T-line of the detection band. This area will never produce a specific binding reaction, meaning there will never be gold accumulation; therefore, this area can serve as a standard for analyzing dynamic background information at each moment.

[0024] In one specific implementation of this invention, the optical data acquisition module acquires test strip images continuously over a long period because the kinetic starting point of the chromatographic reaction is defined as the instant the liquid front just wets the upstream edge of the detection band. However, at this moment, the detection band has not yet undergone a color reaction, and its optical characteristics are extremely indistinct, making it difficult to use as a real-time trigger signal. If recording is started only after the color development is clear, the most discriminative wetting stage data in the early stages of the reaction will be lost. Therefore, in this specific implementation, a ring buffer is set up to record the acquired test strip images, and the upstream liquid contact moment is deduced by monitoring the downstream signal, specifically including: The optical acquisition unit is activated to continuously capture test strip images at a fixed frame rate. In this specific implementation, the frame rate is set to 30 frames per second. The image frames are written to a circular buffer in the system memory in the acquisition order. This circular buffer is configured to store a fixed-length (e.g., 300 frames) image sequence. During the writing process, the system monitors the location of the escape zone at a preset distance (e.g., 2 mm) downstream of the detection zone in real time. When the average gray value of the escape zone drops abruptly and exceeds a preset trigger threshold, it indicates that the liquid has flowed through the detection zone and reached the downstream. At this point, the system stops the buffer overwriting operation. Subsequently, the system performs time-axis backward tracing in the image sequence stored in the buffer. The system analyzes the gray value change rate of the upstream edge region of the detection zone frame by frame, finds the frame where the gray value first deviates from the baseline noise, and takes this frame as the liquid contact moment. The circular buffer writing process ends, and the frame images of each sampling moment after the liquid contact moment are used for analysis by subsequent modules.

[0025] It should be noted that the determination of a step descent can be made using the second derivative of the average grayscale value of the escape region. If the second derivative is greater than a preset trigger threshold, a step descent is considered to have occurred. The grayscale change rate of the upstream edge region can be quantified using the first derivative of the average grayscale value of the upstream edge region. If the first derivative is greater than a preset change rate threshold for the first time, it is considered that the grayscale value in that frame has deviated from the baseline noise for the first time. Both the trigger threshold and the change rate threshold can be statistically derived from historical data or manually set according to actual conditions, and will not be elaborated or limited here. The sampling times mentioned thereafter all represent sampling times after the liquid contact time.

[0026] In the system proposed in this embodiment of the invention, the flow data quantization module 102 is used to remove the background gray value of the background region image from the gray values ​​of the detection zone area image and the absorbent pad area image at each sampling time, thereby obtaining the color intensity of the detection zone and the color intensity of the absorbent pad in sequence; and to obtain the throughput of the detection zone at each sampling time based on the color intensity of the detection zone and the color intensity of the absorbent pad.

[0027] In this embodiment of the invention, it is considered that after liquid flows through the pores of the test strip membrane, the refractive index and transmittance of the membrane will change due to the liquid filling the pores, for example, becoming grayer or darker, resulting in changes in background information. Therefore, static background information should not be analyzed. Instead, at each sampling moment, the background grayscale value is dynamically analyzed based on the background area image of the test strip at the current moment. This dynamic background grayscale value can change synchronously with the flow of liquid on the test strip according to the wetting process, thereby obtaining a pure and effective gold standard signal when the detection zone area image and the absorbent pad area image are processed for background removal. Therefore, at each sampling moment, the grayscale value of the detection zone area image and the absorbent pad area image can be separated from the background grayscale value of the test strip background area image to obtain the color development intensity of the detection zone and the absorbent pad respectively.

[0028] At each sampling moment, the color intensity of the test strip and the absorbent pad can be obtained. Taking the color intensity of the test strip as an example, because the gold label develops color, the gray value of the test strip area will decrease. Therefore, the gray value of the test strip area relative to the background value can characterize the color intensity produced by the reaction of the substance under the test strip area, and thus characterize the substance content flowing through the test strip area. Similarly, because the absorbent pad has physical adsorption properties, the flowing gold label complex will be captured and accumulated by the absorbent pad fibers. Therefore, the color intensity of the absorbent pad characterizes the substance content that falls into the absorbent pad after the liquid flows through the entire area of ​​the test strip, that is, it characterizes the total amount of substance flowing out of the chromatography film up to each moment. Therefore, at each moment, the test strip throughput can be obtained by combining the color intensity of the test strip and the color intensity of the absorbent pad. That is, the test strip throughput characterizes the total optical density equivalent of the gold label complex actually transported through the test strip area from the moment of liquid contact to the current moment. This physical quantity is independent of flow rate and time, and is only related to the amount of substance supplied. By quantifying optical features, the total amount of material flowing through the detection zone at each moment can be characterized indirectly.

[0029] Preferably, in this embodiment of the invention, the method for obtaining the background grayscale value includes: For each sampling time, the average gray value in the background area image of the test strip is taken as the background gray value at the corresponding sampling time.

[0030] In other implementations of this invention, statistical data representing the overall grayscale value, such as the median of grayscale values ​​in the background area image of the test strip, can also be selected as the background grayscale value.

[0031] Preferably, in this embodiment of the invention, the method for obtaining the colorimetric intensity of the detection band includes: For each sampling time, the detection band region will exhibit darker optical characteristics due to the influence of the gold standard's color rendering. Therefore, the first difference between the background grayscale value and the average grayscale value in the detection band region image is obtained. The larger the first difference, the darker the detection band region is relative to the background region, indicating a higher concentration of matter and a more pronounced color rendering. Furthermore, to avoid the obtained color rendering intensity being less than 0, which does not conform to real physical conditions, the following constraints are set: if the first difference is greater than 0, then the first difference is used as the color rendering intensity of the detection band; if the first difference is less than or equal to 0, then the color rendering intensity of the detection band at the corresponding sampling time is set to 0.

[0032] Similarly, in another preferred embodiment of the present invention, the method for obtaining the color intensity of the absorbent pad includes: For each sampling time, a second difference is obtained between the background grayscale value and the average grayscale value in the absorbent pad area image. If the second difference is greater than 0, the first difference is used as the color rendering intensity of the absorbent pad; if the first difference is less than or equal to 0, the color rendering intensity of the absorbent pad at the corresponding sampling time is set to 0. Further details are omitted.

[0033] Preferably, in this embodiment of the invention, the method for obtaining the throughput of the detection band includes: At each sampling moment, the sum of the color intensity of the detection strip and the color intensity of the absorbent pad is taken as the throughput of the detection strip.

[0034] Considering that the interference of matrix particles in the sample on the detection band mainly manifests as a "deep filtration effect," meaning that particles preferentially fill the micropores on the water-facing side of the detection band, this filling effect accelerates non-linearly with the increase of the total amount of flowing material, causing the color development to gradually accumulate towards the front. In contrast, the chemical inhibition effect of atrazine is based on site competition at the molecular level; its color reduction is spatially uniform and does not undergo abrupt changes in distribution with increasing flow rate. Therefore, based on the above differences, the material change analysis module 103 in the detection band region can analyze the dynamic evolution characteristics of the color distribution in the detection band region as the flow rate increases, thereby extracting the degree of blockage growth that is only related to particle accumulation and characterizes abnormal changes.

[0035] The detection zone material change analysis module 103 first divides the detection zone into upstream and downstream regions. This is to capture the non-uniformity of the microscopic distribution within the detection zone. The detection zone needs to be spatially segmented along the fluid flow direction, resulting in the upstream and downstream regions. The upstream region is the area that first comes into contact with the liquid, and the downstream region is the area the liquid flows through after passing through the upstream region. The difference in color intensity between the upstream and downstream regions at each moment is then obtained. This difference in color intensity directly reflects the degree of non-uniformity of the chromogenic substance distribution along the liquid flow direction within the detection zone at the current moment. If the color intensity in the upstream region is significantly higher, it indicates that the substance is preferentially accumulating at the front end; if the color intensities in the upstream and downstream regions are similar, it indicates that the color is spatially uniformly distributed. In other words, the difference in color intensity characterizes the microscopic distribution characteristics of the substance on the detection zone.

[0036] To correlate the microscopic distribution characteristics of the substance on the detection band with the fluid transport process, the substance change analysis module 103 in the detection band region analyzes the distribution trend of color intensity differences with the change trend of the detection band flow rate at continuous sampling times, based on the flow rate of the detection band, and thus obtains the degree of blockage growth. That is, the more uniform the distribution trend, the more stable the microscopic distribution of the substance is with the change of flow rate, which is consistent with the atrazine uniform inhibition or interference-free chromatography characteristics; conversely, if the distribution trend is more chaotic, it indicates that particulate matter may have blocked the pores of the detection band, thus leading to false positives in the detection results.

[0037] Therefore, the colorimetric detection module 104 can sequentially perform blockage detection based on the throughput of the detection band at the final moment, the color intensity of the detection band, and the degree of blockage growth. That is, the throughput of the detection band at the final moment is the most macroscopic and significant feature that can assess the blockage of the substance on the detection band. Then, combined with the color intensity of the detection band, the fluid state in the specific detection process is judged from the optical characteristics. Finally, the detection result is accurately judged based on the microscopic feature of the degree of blockage growth.

[0038] Preferably, in this embodiment of the invention, based on the competitive method principle of atrazine detection, when the sample does not contain the drug (i.e., negative), the T-line of the detection band shows a stronger color and appears darker; when the sample contains the drug (i.e., positive), the T-line shows a weaker color or is even invisible, appearing brighter or lighter; when the detection band is blocked, the liquid flow slows down or stops, and the gold-labeled antibody cannot flow through and bind to the T-line of the detection band, thus showing a brighter weak signal intensity and a false positive. Therefore, when segmenting the detection band, it is not possible to directly use the T-line as a reference. However, regardless of whether the sample contains the drug, the control line, i.e., the C-line, will always bind to the gold-labeled antibody and show color. Therefore, when dividing the detection band region, the T-line position can be determined by identifying the C-line as a reference point for segmentation, specifically including: First, the position of the C-line on the detection zone is determined, as the C-line will bind to the gold-labeled antibody and develop color. Therefore, in the specific implementation of this invention, the last frame of the detection zone image can be selected as a reference. A C-line search area is set at a fixed distance downstream of the theoretical T-line position in the detection zone image. For the C-line search area, the average gray value of each row is calculated, and a vertical gray-level distribution curve is constructed. Each value in the vertical gray-level distribution area is processed to remove the background according to the detection zone color intensity acquisition method to obtain the optical density distribution curve corresponding to the gray-level distribution curve. The vertical coordinate corresponding to the maximum peak point on the optical density distribution curve is selected as the C-line position. If the C-line position cannot be found in the current frame, the previous frame is selected for searching. It should be noted that the specific implementation process of the above process, such as the maximum peak point selection and curve fitting, are all superposition techniques well known to those skilled in the art, and will not be elaborated or limited here.

[0039] Because the position between the T-line and the C-line is fixed, the position of the T-line can be determined based on the position of the C-line according to a preset size. In this embodiment of the invention, the fixed distance between the T-line and the C-line on the test strip is 5 mm. The preset size in the image can be obtained through existing technologies such as image resolution mapping, which will not be elaborated further.

[0040] The region to be analyzed is constructed centered on the T-line position according to a preset analysis size. The T-line position divides the region to be analyzed into the upstream region and the downstream region. In this embodiment of the invention, the preset analysis size is the size of 1 millimeter in the real world corresponding to the image. That is, the final region to be analyzed is a region with a width equal to the preset analysis size and a length equal to the width of the test strip, and the T-line position divides this region into two parts.

[0041] It should be noted that the color intensity of the upstream region and the color intensity of the downstream region are obtained using the same method as the color intensity of the detection band, and will not be elaborated here.

[0042] Preferably, in this embodiment of the invention, the method for obtaining the difference in color intensity includes: The color intensity difference is obtained by subtracting the color intensity of the downstream region from the color intensity of the upstream region. If blockage occurs, although the overall color intensity is weaker and appears brighter, upstream blockage causes particles to become trapped in the membrane pores. These trapped particles accumulate the gold-labeled complex, resulting in a noticeably darker color in the upstream region (i.e., a higher color intensity). Therefore, a greater color intensity difference indicates that the color intensity of the upstream region is stronger than that of the downstream region, exhibiting a darker characteristic. This suggests that particles are blocking the upstream region, leading to a relatively lower color intensity in the downstream region. Thus, the color intensity difference can effectively characterize the microscopic material distribution characteristics on the detection band.

[0043] Preferably, in this embodiment of the invention, the method for obtaining the degree of blockage growth includes: Using the detection band throughput as the horizontal axis and the color intensity difference as the vertical axis, a two-dimensional coordinate system is constructed. Then, the detection band throughput and color intensity difference at each moment can form a data point in the two-dimensional coordinate system.

[0044] Since particulate matter blockage typically involves two stages: "initial pore wetting" and "final accumulation intensification," the data points in the two-dimensional coordinate system are divided into a first set of points and a second set of points based on the horizontal axis coordinates; on the horizontal axis, the second set of points follows the first set of points. In a specific implementation of this invention, the horizontal axis range of the first set of points represents the wetting baseline range, corresponding to 0% to 30% on the horizontal axis. At this stage, the fluid has just entered the detection zone, mainly reflecting the initial resistance characteristics of the membrane medium itself. The horizontal axis range of the second set of points represents the blockage response interval, corresponding to 70% to 100% on the horizontal axis. At this stage, the fluid has fully flowed through the detection zone, and if particulate matter is present, the accumulation caused by the deep filtration effect will significantly worsen at this stage.

[0045] The degree of blockage growth is obtained by analyzing the difference in the changing trends of data points between the second and first point sets. Since the two point sets represent data changes in two different regions over time, the difference in changing trends can quantify the curvature of the evolution trajectory, i.e., determine whether the increase in color intensity difference accelerates with the increase in the amount of material passing through the detection band. A larger difference in changing trends indicates that as more material flows through, the upstream accumulation rate is significantly faster than the downstream, and this difference is accelerating, reflecting the typical characteristics of progressive pore blockage caused by particulate matter. Conversely, a smaller difference in changing trends indicates that the color intensity difference between the upstream and downstream is linear or remains constant, consistent with the atrazine uniform suppression or interference-free chromatographic characteristics. Therefore, the obtained degree of blockage growth can effectively determine whether the detection result is a false positive.

[0046] Furthermore, analyzing the differences in the changing trends of data points between the second set of points and the first set of points to obtain the degree of congestion growth includes: A linear fit is performed on the data points in the first set of points to obtain a first fitting slope; a linear fit is then performed on the data points in the second set of points to obtain a second fitting slope; the difference between the second fitting slope and the first fitting slope is taken as the degree of blockage growth. That is, the larger the difference in slopes, the more significantly the upstream accumulation state is enhanced as more material flows through, i.e., the more pronounced the blockage characteristics. In the specific implementation of this embodiment, the least squares method is used for linear fitting; the specific means are well-known to those skilled in the art and will not be elaborated here.

[0047] Preferably, in this embodiment of the invention, blockage detection is performed sequentially based on the detection band throughput, detection band color intensity, and blockage growth degree at the final time, including a three-level detection process, wherein the three-level detection process includes: Level 1 Detection Process: If the throughput of the detection band at the final moment is less than the preset throughput threshold, it indicates that the sample is too viscous, resulting in an inability to effectively flow through the detection band, representing an extreme blockage. This indicates an invalid detection and prompts the user to dilute the sample. Otherwise, proceed to Level 2 Detection Process. It should be noted that the throughput threshold can be determined based on the minimum crawling distance of the standard buffer solution within a specified time, which will not be elaborated upon here.

[0048] Secondary detection process: If the color intensity of the detection band at the final moment is not less than the preset color intensity threshold, it indicates that the detection band is clearly colored, and the gold-labeled antibody is not competitively inhibited by atrazine, nor is it significantly physically blocked. At this time, regardless of the microscopic distribution, the system directly reports a negative detection result; otherwise, it proceeds to the tertiary detection process. It should be noted that the color intensity threshold can be obtained by testing a series of blank negative samples without atrazine, and in the specific implementation of this embodiment, it can be taken as 80% of the mean of the negative samples.

[0049] The three-stage detection process: If the degree of blockage growth is not less than the preset blockage threshold, it indicates that during fluid transport, the difference in color intensity between the upstream and downstream of the detection band increases significantly and non-linearly with the increase of the detection band throughput. This corresponds to the deep filtration and pore closure effect of particulate matter on the upstream side of the detection band. Although the color development of the detection band is weak, this weakness is caused by the obstruction of fluid supply due to physical blockage. Therefore, a false positive result is reported, and operational suggestions can be output: if sample particle blockage is detected, it is recommended to retest after centrifugation of the original sample. Otherwise, it indicates that the color distribution inside the detection band remains relatively stable throughout the chromatography process, and there is no accelerated accumulation phenomenon. The weak color development is not due to physical blockage, but rather to the uniform chemical competition of atrazine molecules for the binding site of the gold-labeled antibody. Therefore, a positive result is reported, indicating a food safety risk. It should be noted that the blockage threshold can be calculated by testing a series of matrix samples containing high concentrations of particulate matter but without atrazine (such as untreated corn steep liquor) to obtain the statistical lower limit of the degree of blockage growth as the blockage threshold.

[0050] In summary, the system proposed in this embodiment of the invention includes: an optical data acquisition module for continuously acquiring multiple frames of test strip images at the moment of liquid contact, the test strip images including a detection zone area image, a test strip background area image, and an absorbent pad area image; a flow data quantification module for removing the background gray value of the test strip background area image from the gray values ​​of the detection zone area image and the absorbent pad area image at each sampling moment, thereby obtaining the color intensity of the detection zone and the color intensity of the absorbent pad, and thus obtaining the throughput of the detection zone; a substance change analysis module for dividing the detection zone area into an upstream region and a downstream region, obtaining the difference in color intensity between the two, and obtaining the degree of blockage growth based on the distribution of the color intensity difference with the throughput of the detection zone; and a color detection module for performing blockage detection based on the throughput of the detection zone, the color intensity of the detection zone, and the degree of blockage growth at the final moment. This invention can effectively distinguish between false positives caused by physical blockage and true positives caused by chemical inhibition, improving detection accuracy.

[0051] It should be noted that the order of the above embodiments of the present invention is merely for descriptive purposes and does not represent the superiority or inferiority of the embodiments. The processes depicted in the accompanying drawings do not necessarily require a specific or sequential order to achieve the desired result. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0052] The various embodiments in this specification are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

Claims

1. A rapid detection system for screening atrazine in food samples, characterized in that, The system includes: An optical data acquisition module is used to continuously acquire multiple frames of test strip images at the moment of liquid contact. The test strip images include images of the detection zone area, images of the test strip background area, and images of the absorbent pad area. The flow data quantization module is used to remove the background gray value of the test strip background area image from the gray values ​​of the detection strip area image and the absorbent pad area image at each sampling time, thereby obtaining the color intensity of the detection strip and the color intensity of the absorbent pad; and to obtain the flow rate of the detection strip at each sampling time based on the color intensity of the detection strip and the color intensity of the absorbent pad. The detection zone material change analysis module is used to divide the detection zone into upstream and downstream regions and obtain the color intensity difference between the upstream and downstream regions; based on the distribution of the color intensity difference with the change trend of the detection zone throughput at continuous sampling time, the degree of blockage growth is obtained. The color development detection module is used to perform blockage detection sequentially based on the detection band throughput, color development intensity, and blockage growth at the final moment.

2. The rapid detection system for screening atrazine in food samples according to claim 1, characterized in that, The method for obtaining the background grayscale value includes: For each sampling time, the average gray value in the background area image of the test strip is taken as the background gray value at the corresponding sampling time.

3. The rapid detection system for screening atrazine in food samples according to claim 1, characterized in that, The method for obtaining the colorimetric intensity of the detection band includes: For each sampling time, a first difference is obtained between the background gray value and the average gray value in the detection zone region image. If the first difference is greater than 0, the first difference is used as the color intensity of the detection zone; if the first difference is less than or equal to 0, the color intensity of the detection zone at the corresponding sampling time is set to 0.

4. The rapid detection system for screening atrazine in food samples according to claim 1, characterized in that, The method for obtaining the color development intensity of the absorbent pad includes: For each sampling time, a second difference is obtained between the background gray value and the average gray value in the absorbent pad area image. If the second difference is greater than 0, the first difference is used as the color rendering intensity of the absorbent pad. If the first difference is less than or equal to 0, the color rendering intensity of the absorbent pad at the corresponding sampling time is set to 0.

5. A rapid detection system for screening atrazine in food samples according to claim 1, characterized in that, The method for obtaining the throughput of the detection band includes: At each sampling moment, the sum of the color intensity of the detection strip and the color intensity of the absorbent pad is taken as the throughput of the detection strip.

6. A rapid detection system for screening atrazine in food samples according to claim 1, characterized in that, The method for obtaining the degree of blockage growth includes: A two-dimensional coordinate system is constructed with the detection band throughput as the horizontal axis and the color intensity difference as the vertical axis. The data points in the two-dimensional coordinate system are divided into a first set of points and a second set of points according to the horizontal axis coordinates. On the horizontal axis, the second set of points is after the first set of points. The difference in the changing trend of data points between the second set of points and the first set of points is analyzed to obtain the degree of blockage growth.

7. A rapid detection system for screening atrazine in food samples according to claim 1, characterized in that, The blockage detection process is performed sequentially based on the detection band throughput, detection band color intensity, and blockage growth at the final time point. This includes a three-stage detection process, which comprises: Level 1 detection process: If the throughput of the detection band at the final moment is less than the preset throughput threshold, the detection is invalid; otherwise, proceed to the Level 2 detection process. Secondary detection process: If the color intensity of the detection band at the final moment is not less than the preset color intensity threshold, a negative detection result is returned; otherwise, the tertiary detection process is initiated. The three-level detection process is as follows: if the degree of blockage growth is not less than the preset blockage threshold, a false positive detection result is returned; otherwise, a positive detection result is returned.

8. A rapid detection system for screening atrazine in food samples according to claim 1, characterized in that, The process of dividing the detection zone into an upstream region and a downstream region includes: The position of the C-line on the detection zone is determined, and the position of the T-line is determined according to a preset size based on the position of the C-line. The region to be analyzed is constructed with the T-line position as the center according to a preset analysis size, and the T-line position divides the region to be analyzed into the upstream region and the downstream region.

9. A rapid detection system for screening atrazine in food samples according to claim 1, characterized in that, The method for obtaining the color intensity difference includes: The color intensity difference is obtained by subtracting the color intensity of the downstream region from the color intensity of the upstream region.

10. A rapid detection system for screening atrazine in food samples according to claim 6, characterized in that, The analysis of the differences in the changing trends of data points between the second set of points and the first set of points to obtain the degree of congestion growth includes: A linear fit is performed on the data points in the first set of points to obtain a first fitting slope; a linear fit is performed on the data points in the second set of points to obtain a second fitting slope; the difference between the second fitting slope and the first fitting slope is taken as the degree of blockage growth.

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