A water quality heavy metal detection device and method based on an SPR sensor

Abstract

A water quality heavy metal detection equipment based on an SPR sensor includes a heavy metal detection end and a data analysis end, the data analysis end is connected with the heavy metal detection end; the heavy metal detection end includes a shooting assembly, a light supply assembly, a slide and a sulfide montmorillonite modified optical fiber, the shooting assembly is connected with a first optical fiber probe, the light supply assembly is connected with a second optical fiber probe, one end of the optical fiber is connected with the first optical fiber probe, the other end of the optical fiber is connected with the second optical fiber probe; the optical fiber includes a third optical fiber section with deposited coating material, the third optical fiber section is fixed on the slide, the surface of the third optical fiber section is coated with a gold film and sulfide montmorillonite, and the sulfide montmorillonite is located outside the gold film. A water quality heavy metal detection method based on an SPR sensor uses the above equipment. The present application can overcome the difficulty that the refractive index of low concentration heavy metal water sample is small compared with pure water, realize the detection of trace heavy metal water sample, and belongs to the field of water quality heavy metal detection.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of water quality heavy metal detection, and particularly relates to a water quality heavy metal detection device and method based on an SPR sensor. BACKGROUND

[0002] Mercury mainly exists in the form of elemental mercury, organic mercury and inorganic mercury in the environment such as water, air, soil and food, and is a global environmental pollutant. Mercury is widely used in medical and industrial fields. Mercury has various toxic effects on animals and humans, can accumulate in kidney cells, skin, heart, reproductive system and other tissues and organs, can also penetrate the blood-brain barrier into the central nervous system to cause damage, and has been listed as a priority control pollutant by the World Health Organization. In the national standard "Environmental Quality Standard for Surface Water", the mercury concentration limits of the first and fifth categories are 0.00005 mg / L and 0.001 mg / L, respectively.

[0003] At present, the commonly used methods for detecting mercury ions in water include gas chromatography, cold atomic spectrophotometry and atomic fluorescence method. However, these methods have the disadvantages of large and expensive instruments and equipment, complicated pretreatment process, need for professional operation, long detection time and the like. For example, Chinese patent application (publication number CN109959635A, entitled "Optical fiber SPR sensor based on electric field coupling") discloses an optical fiber SPR sensor, Chinese patent application (publication number CN112255199A, entitled "Pb 2+ concentration detection sensor, device, preparation method and use method" discloses a Pb 2+ concentration detection sensor, and Chinese patent (publication number CN212379356U, entitled "Heavy metal detector based on 3D printing technology and convenient to carry") discloses a heavy metal detector. However, the above-mentioned technologies are mostly suitable for biological sensing rather than heavy metal detection, and have the problems of needing to pretreat samples, long detection time, difficulty in on-site rapid detection, low detection precision and great influence of environmental interference factors. SUMMARY

[0004] In view of the technical problems in the prior art, the purpose of the present application is to provide a water quality heavy metal detection device and method based on an SPR sensor, which has small volume, is easy to carry and has high precision.

[0005] In order to achieve the above object, the present application adopts the following technical scheme: a water quality heavy metal detection equipment based on an SPR sensor, comprising a heavy metal detection end and a data analysis end, wherein the data analysis end is connected with the heavy metal detection end; the heavy metal detection end comprises a shooting assembly, a light supply assembly, a glass sheet and a sulfur-montmorillonite modified optical fiber, the shooting assembly is connected with a first optical fiber probe, the light supply assembly is connected with a second optical fiber probe, one end of the optical fiber is connected with the first optical fiber probe, and the other end of the optical fiber is connected with the second optical fiber probe; the optical fiber comprises a first optical fiber segment connected with the first optical fiber probe, a second optical fiber segment connected with the second optical fiber probe and a third optical fiber segment on which a coating material is deposited, the third optical fiber segment is fixed on the glass sheet, the surface of the third optical fiber segment is coated with a gold film and sulfur-montmorillonite, and the sulfur-montmorillonite is located outside the gold film; and a multimode optical fiber is connected between the shooting assembly and the light supply assembly. After adopting this structure, the gold film has excellent properties of good chemical stability and not easy to be oxidized. The sulfur-montmorillonite layer contains a large number of mercapto groups and can be self-assembled on the metal film, the optical fiber modified by the sulfur-montmorillonite can specifically adsorb mercury ions, the refractive index of the sensing layer medium is changed, the resonance angle is deviated, the difficulty that the refractive index of a low-concentration heavy metal water sample is small compared with pure water can be overcome, and the detection of trace heavy metal water samples can be realized.

[0006] As a kind of preferred, the light supply component includes LED lamp, lens and optical filter, lens and optical filter are located in front of LED lamp in turn, second optical fiber probe is located in front of optical filter, and the other end of optical fiber is connected with second optical fiber probe;Shooting assembly includes camera, first optical fiber probe is located in front of camera, and one end of optical fiber is connected with second optical fiber probe. After adopting this structure, the light supply component can provide suitable light source for detection, and the shooting component is used to read the photoelectric signal conducted to here by the optical fiber.

[0007] As a kind of preferred, the heavy metal detection end further comprises a test box, and the glass sheet is located at the bottom of the test box. After adopting this structure, the test box is located in the determination area, and the water sample can be dropped on the glass sheet to immerse the third optical fiber segment during testing, so that the operation is convenient.

[0008] As a kind of preferred, two opposite through holes are opened on the test box, the aperture of the through hole is larger than the outer diameter of the optical fiber, the optical fiber passes through the two through holes, and the third optical fiber segment is located in the region between the two through holes.

[0009] As a kind of preferred, the test box has an opening, the heavy metal detection end further comprises a top cover which can cover the opening, and the top cover is hinged to the test box. After adopting this structure, the top cover can be rotated by 90°, and the determination area can be prevented from being polluted by external environment when the top cover is closed.

[0010] As a preferred, the device shell is further included, the material of the device shell includes aluminum magnesium alloy or titanium alloy, the shooting component and the light supply component are located inside the device shell and are fixed by the partition plate, and the test box is fixed to the outer surface of the device shell. After adopting the structure, the shooting component, the light supply component, the determination area and the two sensing components are concentrated in one device, and the device has the characteristics of small volume and convenient carrying, and the device has the abilities of anti-deformation, anti-fracture, high temperature resistance, corrosion resistance and impact resistance.

[0011] As a preferred, the modification method of the optical fiber includes the following steps:

[0012] A, cleaning: the optical fiber is soaked in acetone for 10-20 minutes, and then washed with deionized water for 3-5 times;

[0013] B, coating: a layer of gold film is coated on the surface of the optical fiber;

[0014] C, modification: the thiomontmorillonite powder is added into a mixed solution of ethanol and water, the volume ratio of ethanol and water is 1:1, a thiomontmorillonite dispersion solution with a concentration of 0.02-0.05 mg / mL is obtained, then the optical fiber is immersed in the thiomontmorillonite dispersion solution, after the immersion is completed, the optical fiber is taken out and washed with anhydrous ethanol and deionized water for 3-5 times respectively, and then dried with N2.

[0015] A water quality heavy metal detection method based on an SPR sensor, the water quality heavy metal detection method based on the SPR sensor is adopted, and includes the following steps:

[0016] S1, detecting the water sample by using the heavy metal detection end, obtaining detection information, and then analyzing the detection information by using the data analysis end;

[0017] S2, cleaning the heavy metal detection end.

[0018] By using the above method, the data analysis end can use artificial intelligence algorithm, combine with existing image recognition analysis technology: image acquisition→image preprocessing→feature extraction→image recognition, perform linear analysis on the data of the optical feedback of the front-end SPR sensor, and combine with the water quality heavy metal detection preprocessing technology and environmental interference factor algorithm, so that the detection precision of the water quality heavy metal concentration can be improved. In addition, through the cleaning and drying process of the heavy metal detection end, the purpose of repeated use can be achieved.

[0019] Due to various factors caused by camera characteristics (such as unknown built-in automatic color control mechanism), the measured color will change, so color calibration is needed.

[0020] Before using a water quality heavy metal detection device based on an SPR sensor for detection, a calibration step is performed, and the calibration step is as follows:

[0021] First, mark the color information of the reference area as C. P Rij The color marker for the target area is C. P Tk , (u s ,v s ) and (u d ,v d ) represent C respectively P Rij and C P Tk The color information of the region is adapted using the fourth-order polynomial model in equations (1) and (2).

[0022]

[0023]

[0024] Based on equations (1) and (2), the color information of all reference color indices is represented in the form of a single matrix as y = Xa, and the optimal solution a is represented by equation (3).

[0025]

[0026] The solution a is obtained by iterative weighted least squares method, as shown in equation (4).

[0027] a (t+1) =(X T W (t) X) -1 X T W (t) y (4)

[0028] in,

[0029] W i (0) =1 (5)

[0030]

[0031] To obtain a better estimation resolution, thin-plate spline interpolation is applied by finding the f that minimizes the energy function of equation (7). k (x) is used to perform interpolation.

[0032]

[0033] During measurement, the reference color and target color obtained in the measurement steps will be represented as M respectively. Rij and M Tk Through equation (8) and C P Tk Find the best fit for M TkThe final pH estimate is given by equation (8) as follows:

[0034]

[0035] The aforementioned equipment and methods are superior to existing equipment and methods in terms of efficiency and portability, significantly reducing manpower and material resources, shortening detection time, and enabling real-time and rapid detection and data uploading of heavy metal concentrations. This is beneficial for establishing a nationwide real-time heavy metal concentration distribution map. While ensuring high accuracy of the detection results, it makes it possible for small laboratories and untrained personnel to conduct heavy metal concentration testing in water quality.

[0036] The detection limit of the heavy metal mercury ions detected by the above-mentioned equipment and methods can reach 0.0010 to 0.0030 ng / mL, which is lower than the detection limit of standard methods and some large instruments such as ICP-MS. It is more accurate for the determination of environmental water samples and is also lower than that of some conventional coating materials, such as 1,6-hexanedithiol and plant protein probes.

[0037] In summary, the present invention has the following advantages:

[0038] Compared with existing technologies, the coating material used in this invention enables the sensor to specifically bind heavy metal ions, exhibiting high specificity, strong anti-interference ability, simple operation, and lightweight device that is easy to carry and perform rapid on-site detection. Furthermore, it utilizes existing intelligent image recognition and analysis capabilities, eliminating the need for sample pretreatment and filling the technological gap in existing technologies where water heavy metal detection is time-consuming and difficult to perform rapid on-site detection. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of a water quality heavy metal detection device based on an SPR sensor.

[0040] Figure 2 This is a schematic diagram of the third fiber segment.

[0041] Figure 3 This is a schematic diagram of the internal structure of the third fiber segment.

[0042] Among them, 1 is the imaging component, 2 is the light supply component, 3 is the first fiber segment, 4 is the third fiber segment, 5 is the second fiber segment, 6 is the multimode fiber, 7 is the first fiber probe, 8 is the partition, 9 is the battery box, 10 is the top cover, 11 is the through hole, 12 is the measurement area, 13 is the glass slide, 14 is the equipment shell, 15 is the LED light, 16 is the lens, 17 is the filter, 18 is the matrix, 19 is the sensing area, 20 is the fiber, 21 is the second fiber probe, 22 is the gold film, and 23 is thiomontmorillonite. Detailed Implementation

[0043] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0044] Example 1

[0045] like Figures 1-3 As shown, a water quality heavy metal detection device based on an SPR sensor includes a heavy metal detection end and a data analysis end, with the data analysis end connected to the heavy metal detection end. The heavy metal detection end includes an imaging component, a light supply component, a glass slide, and an optical fiber modified with thiomontmorillonite. The imaging component is connected to a first optical fiber probe, and the light supply component is connected to a second optical fiber probe. One end of the optical fiber is connected to the first optical fiber probe, and the other end of the optical fiber is connected to the second optical fiber probe. The optical fiber includes a first optical fiber segment connected to the first optical fiber probe, a second optical fiber segment connected to the second optical fiber probe, and a third optical fiber segment deposited with a coating material. The third optical fiber segment is fixed on the glass slide, and its surface is coated with a gold film and thiomontmorillonite, with the thiomontmorillonite located on the outside of the gold film. A multimode optical fiber is connected between the imaging component and the light supply component.

[0046] The light supply component includes an LED light, a lens, and a filter. The lens and filter are located in front of the LED light, and the second fiber optic probe is located in front of the filter. The other end of the fiber optic cable is connected to the second fiber optic probe. The imaging component includes a camera. The first fiber optic probe is located in front of the camera, and one end of the fiber optic cable is connected to the second fiber optic probe.

[0047] The heavy metal detection unit also includes a test box, with a glass slide located at the bottom of the test box.

[0048] The test box has two opposing through holes, the diameter of which is larger than the outer diameter of the optical fiber. The optical fiber passes through the two through holes, and the third optical fiber segment is located in the area between the two through holes.

[0049] The two ends of the third fiber segment are wrapped with a substrate, and the area between the substrates is the sensing zone.

[0050] The test box has an opening, and the heavy metal detection end also includes a top cover that can be placed over the opening, and the top cover is hinged to the test box.

[0051] It also includes a device housing made of aluminum-magnesium alloy or titanium alloy. The imaging and light-supplying components are located inside the housing and secured by partitions. The test box is fixed to the outer surface of the housing. The light-supplying components are powered by a battery compartment, and the battery can be easily removed and replaced.

[0052] The optical fiber modification method includes the following steps:

[0053] A. Cleaning: Soak the optical fiber in acetone for 10-20 minutes, then rinse with deionized water 3-5 times.

[0054] B. Coating: A layer of gold film is deposited on the surface of the optical fiber;

[0055] C, modification: add thiomontmorillonite powder to a mixed solution of ethanol and water with a volume ratio of 1:1, obtain a thiomontmorillonite dispersion solution with a concentration of 0.02-0.05 mg / mL, then immerse the optical fiber in the thiomontmorillonite dispersion solution, after immersion, take out the optical fiber and rinse with anhydrous ethanol and deionized water for 3-5 times, and then blow dry with N2.

[0056] The gold film optical fiber is prepared by a dopamine-accelerated wet chemical plating film method based on a solution competition method using an optical fiber SPR sensor.

[0057] The specific operation of the modification is as follows: ① 30-50 mg of thiomontmorillonite powder is weighed by an electronic analytical balance and added to 1000-1500 mL of a mixed solution of ethanol and water (volume ratio of 1:1), and the thiomontmorillonite powder is fully dispersed in the solution by treating in an ultrasonic cleaning machine for 30-45 minutes to obtain a thiomontmorillonite dispersion solution with a concentration of 0.02-0.05 mg / mL. ② The cleaned gold film optical fiber is placed in the thiomontmorillonite dispersion solution and immersed for 6-10 hours. After immersion, the optical fiber is taken out and rinsed with anhydrous ethanol and deionized water for 3-5 times, and then completely dried with N2.

[0058] In order to ensure the accuracy and precision of the heavy metal detection results, the gold film thickness is 35-65 nm; the thiomontmorillonite coating thickness is 10-40 nm, the coating width is 2-3 cm, and the coating area is half of the lateral surface area of the optical fiber within the coating width range.

[0059] A water quality heavy metal detection method based on an SPR sensor, using the above-mentioned water quality heavy metal detection method based on an SPR sensor, comprising the following steps:

[0060] S1, using a heavy metal detection end to detect the water sample, obtaining detection information, and then analyzing the detection information through a data analysis end;

[0061] S2, cleaning the heavy metal detection end.

[0062] During detection, the cleaning process should be performed before and after each measurement. Sufficient cleaning can avoid the interference of other substances (such as organic matter) and ensure the accuracy of each detection.

[0063] Before detection using a water quality heavy metal detection device based on an SPR sensor, a calibration step is performed, and the calibration step is as follows:

[0064] First, the color information of the reference area is marked as C P Rij , and the color mark of the calibration target area is marked as C P Tk, (u s ,v s ) and (u d ,v d ) represent C respectively P Rij and C P Tk The color information of the region is adapted using the fourth-order polynomial model in equations (1) and (2).

[0065]

[0066]

[0067] Based on equations (1) and (2), the color information of all reference color indices is represented in the form of a single matrix as y = Xa, and the optimal solution a is represented by equation (3).

[0068]

[0069] The solution a is obtained by iterative weighted least squares method, as shown in equation (4).

[0070] a (t+1) =(X T W (t )X -1 X T W (t) y (4)

[0071] in,

[0072] W i (0) =1 (5)

[0073]

[0074] To obtain a better estimation resolution, thin-plate spline interpolation is applied by finding the f that minimizes the energy function of equation (7). k (x) is used to perform interpolation.

[0075]

[0076] During measurement, the reference color and target color obtained in the measurement steps will be represented as M respectively. Rij and M Tk Through equation (8) and C P Tk Find the best fit for M Tk The final pH estimate is given by equation (8) as follows:

[0077]

[0078] During detection, the collected image is preprocessed by the following methods: 1. noise reduction and simplification processing of the input image signal; 2. edge detection of the simplified image; 3. initial contour extraction by using initial constraints; and 4. classification marking, final contour determination of the reference area and the target area.

[0079] Mercury ions exist in a river in Shanxi, and the mercury ion concentration of the river is tested by using the above water quality heavy metal detection equipment and method based on the SPR sensor, the deposition thickness of the sulfur montmorillonite on the optical fiber is 25nm, and the deposition thickness of the gold film is 40nm. The river water surface width is greater than 50m, so two sampling vertical lines are arranged at the left and right coasts of the river 10m away from the river, and one sampling point is arranged at 0.5m below the water surface of each vertical line, and the sampling points are sample one and sample two. Each sample is determined in parallel for three times. A polytetrafluoroethylene plastic bottle is used as the sampling container, and the sampling amount of each sample is not less than 1L.

[0080] Meanwhile, the determination results of the conventional standard method "Determination of total mercury in water - Cold atomic absorption spectrophotometry" (HJ597-2011) and the ICP-MS method are used as a control. The water sample determination results of the present application and the above two methods are shown in Table 2. As can be seen from the table, the detection precision of the present application is the highest.

[0081] Finally, the optical fiber in the heavy metal detection end is cleaned. First, soak in acetone for 15 minutes, then wash with deionized water for 3 times, then soak in alcohol for 10 minutes, wash with deionized water for 3 times, dry with N2, and use for next detection.

[0082] Table 1 ICP-MS determination condition parameters

[0083] Radio frequency power 1250W Outside air flow rate 15 L / min -1 ]] Carrier gas flow rate 0.7 L min -1 ]] Scanning mode Peak jumping Dwell time 10 ms Integrated mode Peak area

[0084] Table 2 Comparison of determination results of three methods

[0085] Unit: ng / ml

[0086]

[0087] Example 2

[0088] Mercury ions exist in a river in Guangzhou, and the mercury ion concentration of the river is tested by using a water quality heavy metal detection equipment and method based on the SPR sensor, the deposition thickness of the sulfur montmorillonite on the optical fiber is 20nm, and the deposition thickness of the gold film is 45nm. The river water surface width is less than 50m, so one sampling vertical line is arranged at the center of the river, and one sampling point is arranged at 0.5m below the water surface. Each sample is determined in parallel for three times. A polytetrafluoroethylene plastic bottle is used as the sampling container, and the sampling amount of each sample is not less than 1L.

[0089] At the same time, the determination results of the conventional standard method 'Determination of Total Mercury in Water - Cold Atomic Absorption Spectrophotometric Method' (HJ597-2011) and ICP-MS method are used as a control. The water sample determination results of the present application and the above two methods are shown in Table Three. As shown in the table, the detection precision of the present application method is the highest.

[0090] Finally, the optical fiber in the heavy metal detection end is cleaned. First, soak in acetone for 10 minutes, then clean with deionized water for 4 times, then soak in alcohol for 15 minutes, clean with deionized water for 5 times, and dry with N2 for next detection.

[0091] Table Three Comparison of Determination Results of Three Methods for Guangzhou River

[0092] Unit: ng / ml

[0093]

[0094] The part not mentioned in this embodiment is the same as that in Embodiment One.

[0095] Example Three

[0096] Mercury ions exist in the water of a river in Zhejiang. A water quality heavy metal detection device and method based on an SPR sensor are used to test the mercury ion concentration of the river. The deposition thickness of the sulfur-montmorillonite on the optical fiber is 15 nm, and the deposition thickness of the gold film is 35 nm. The width of the river surface is less than 50 meters, so a sampling vertical line is set in the center of the river, and a sampling point is set at 0.5 meters below the water surface. Each sample is determined in triplicate. The sampling container uses a polytetrafluoroethylene plastic bottle, and the sampling amount of each sample is not less than 1L.

[0097] At the same time, the determination results of the conventional standard method 'Determination of Total Mercury in Water - Cold Atomic Absorption Spectrophotometric Method' (HJ597-2011) and ICP-MS method are used as a control. The water sample determination results of the present application and the above two methods are shown in Table Four. As shown in the table, the detection precision of the present application method is the highest.

[0098] Finally, the optical fiber in the heavy metal detection end is cleaned. First, soak in acetone for 10 minutes, then clean with deionized water for 4 times, then soak in alcohol for 15 minutes, clean with deionized water for 5 times, and dry with N2 for next detection.

[0099] Table Four Comparison of Determination Results of Three Methods for Zhejiang River

[0100] Unit: ng / ml

[0101]

[0102] The part not mentioned in this embodiment is the same as that in Embodiment One.

[0103] The above embodiments are the preferred embodiments of the present application, but the embodiments of the present application are not limited to the above embodiments, and any changes, modifications, substitutions, combinations, simplifications, etc. made without departing from the spirit and principles of the present application should be equivalent replacement manners and should be included in the protection scope of the present application.

Claims

1. A water quality heavy metal detection device based on an SPR sensor, characterized in that: The heavy metal detection end and the data analysis end are connected. The heavy metal detection end comprises a shooting assembly, a light supply assembly, a slide and a thiomontmorillonite modified optical fiber. The optical fiber comprises a first optical fiber segment connected with the first optical fiber probe, a second optical fiber segment connected with the second optical fiber probe and a third optical fiber segment on which a coating material is deposited. The third optical fiber segment is fixed on the slide, and the surface of the third optical fiber segment is coated with a gold film and thiomontmorillonite. The shooting assembly and the light supply assembly are connected with a multimode optical fiber. The modification method of the optical fiber comprises the following steps: A. cleaning: the optical fiber is soaked in acetone for 10-20 minutes, and then cleaned with deionized water for 3-5 times; B. coating: a layer of gold film is coated on the surface of the optical fiber; 2. The water quality heavy metal detection device based on the SPR sensor according to claim 1, characterized in that: C. modification: thiomontmorillonite powder is added into a mixed solution of ethanol and water with a volume ratio of 1:1 to obtain a thiomontmorillonite dispersion solution with a concentration of 0.02-0.05 mg / mL, and then the optical fiber is soaked in the thiomontmorillonite dispersion solution, after soaking, the optical fiber is taken out and washed with anhydrous ethanol and deionized water for 3-5 times respectively, and then dried with N2. The light supply component comprises an LED lamp, a lens and a filter, the lens and the filter are located in front of the LED lamp in sequence, the second optical fiber probe is located in front of the filter, and the other end of the optical fiber is connected with the second optical fiber probe.

3. The water quality heavy metal detection device based on the SPR sensor according to claim 1, characterized in that: The shooting assembly comprises a camera, and the first optical fiber probe is located in front of the camera.

4. The water quality heavy metal detection device based on the SPR sensor according to claim 3, characterized in that: The heavy metal detection end further comprises a test box, and the slide is located at the bottom of the test box.

5. The water quality heavy metal detection device based on SPR sensor according to claim 3, characterized in that: Two opposite through holes are formed on the test box, the aperture of the through hole is larger than the outer diameter of the optical fiber, the optical fiber passes through the two through holes, and the third optical fiber segment is located between the two through holes.

6. The water quality heavy metal detection device based on SPR sensor according to claim 3, characterized in that: The test box has an opening, and the heavy metal detection end further comprises a top cover which can cover the opening, and the top cover is hinged to the test box.

7. A method for detecting heavy metal in water based on SPR sensor, using the heavy metal detection device for water quality based on SPR sensor according to any one of claims 1-6, characterized in that: The device shell is made of aluminum magnesium alloy or titanium alloy, the shooting assembly and the light supply assembly are located in the interior of the device shell and fixed by a partition, and the test box is fixed on the outer surface of the device shell. The steps comprise: S1, detecting the water sample by using the heavy metal detection end to obtain detection information, and then analyzing the detection information by using the data analysis end; 8. The method for detecting heavy metal in water based on SPR sensor according to claim 7, characterized in that: S2, cleaning the heavy metal detection end. First, color information of the reference region is labeled as C P Rij , color of the target region is labeled as C P Tk , (u s ,v s ) and (u d ,v d ) represent color information of C P Rij and C P Tk region respectively, color adaptation is performed using the fourth order polynomial model in equation (1) and equation (2), Before using a water quality heavy metal detection device based on a SPR sensor to detect, a calibration step is performed, and the calibration step is as follows: Based on formula (1) and formula (2), the color information of all reference color indexes is expressed as y=Xa in the form of a single matrix, and the optimal solution a is expressed as formula (3), a (t+1) = (X T W (t) X) -1 X T W (t) y (4) The solution a is obtained by iterative weighted least squares method, as shown in formula (4), wherein, W i (0) ＝1 (5) To obtain a better estimation resolution, thin plate spline interpolation is applied to achieve the interpolation by finding the f k (x) that minimizes the energy function of equation (7) 9. The method for detecting heavy metals in water based on SPR sensor according to claim 8, characterized in that: During measurement, the reference color and target color obtained in the measurement steps will be represented as M respectively. Rij and M Tk Through equation (8) and C P Tk Find the best fit for M Tk The final pH estimate is given by equation (8) as follows:

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