CN119804354B - Method for detecting protein in water body based on smart phone - Google Patents

Abstract

This invention discloses a method for detecting proteins in water using a smartphone, belonging to the field of protein detection technology. The portable detection device based on a smartphone uses a beam splitter to split a laser emitted from a laser pointer into two beams. Then, using the test solution and a reference solution as comparisons, the smartphone is used to capture and identify the RGB values, thereby obtaining the A ratio of the test solution and the reference solution. A linear relationship between different protein concentrations and the A value is established, achieving highly sensitive protein detection. Compared to traditional detection methods, this method offers higher sensitivity and enables on-site detection of water samples.

Description

Method for detecting protein in water body based on smart phone

Technical Field

The invention relates to the technical field of detection of proteins in water, in particular to a method for detecting proteins in water based on a smart phone.

Background

There are many methods for determining protein content, and common techniques include Kjeldahl method, colorimetric method (such as biuret method, lowry method, brieford method) and ultraviolet absorption method. Each method has its advantages and limitations, and the selection of the appropriate method depends on the specific requirements of the experiment, the sensitivity desired and the nature of the sample. The Kjeldahl method is a classical method for determining protein content, and indirectly estimates protein content by determining nitrogen content in a sample. The method has high precision and good reproducibility, but is complex to operate and has long time.

Colorimetric methods for determining the amount of protein based on the color change produced upon reaction with a specific reagent include the principal methods of biuret methods utilizing peptide bonds in the protein to react with the biuret reagent to form a purple complex with a maximum absorbance peak at 540 nm. The method is simple and rapid, but has low sensitivity to low concentration proteins. The Lowry method combines the biuret reaction and the oxidation-reduction reaction of the Fu Lin Fen reagent, has higher sensitivity, and is suitable for detecting trace protein. However, this method is sensitive to many interfering substances (e.g. reducing agents, sugars). The UV absorption method, proteins have a natural absorption peak at a wavelength of 280nm due to the absorption of aromatic amino acid residues such as tryptophan and tyrosine. The method is fast and lossless, but requires a purer sample and is susceptible to interference from other absorbing substances.

The Brilliant method uses the color change after Coomassie brilliant blue G-250 dye is combined with the protein to determine the protein content. Coomassie brilliant blue dye changed from brownish red to blue upon binding to protein, and protein content was calculated by measuring its absorbance change at 595 nm. The specific steps are to prepare a standard curve by preparing a series of standard solutions using known concentrations of standard proteins (e.g., bovine serum albumin, BSA). Adding dye, namely adding coomassie brilliant blue dye into the standard solution and the sample solution to be measured, uniformly mixing and standing for a few minutes. Absorbance was measured at 595nm for each of the standard solution and the sample solution. And calculating the protein concentration, namely calculating the protein concentration of the sample to be detected according to the standard curve. The method is widely applied to biochemical laboratories due to its simplicity, rapidness and high sensitivity.

Although there are numerous methods for detecting absorbance and accurate measurements, most of the sensors or precision instruments involved can only be used in laboratory environments where conditions are severe, lacking in rapid detection methods in the field.

Disclosure of Invention

In order to solve the technical problem that the on-site detection of the protein content is difficult in the prior art, the invention provides a method for detecting the protein in the water body based on a smart phone.

In order to solve the technical problems, the invention provides the following technical scheme:

In one aspect, the invention provides portable detection equipment based on a smart phone, which comprises a laser pen, a light source reflector, a beam splitter, a reflector, a cuvette, a cover, a laser pen fixing cylinder and a detection box;

The detection box is internally provided with an L-shaped baffle plate for dividing the detection box into a light mirror area and a sample area, wherein the baffle plate is provided with light holes, and the light holes comprise a first light hole and a second light hole;

The light mirror area is used for placing the light source reflector, the beam splitter and the reflector, laser emitted by the laser pen irradiates the light source reflector, and light rays are reflected to the beam splitter through the light source reflector; the sample area is used for placing a cuvette, and the cuvette comprises a first cuvette and a second cuvette;

In the light mirror area, an incident hole is formed in the side wall of the detection box, the laser pen fixing cylinder is used for fixing a laser pen on the side wall of the detection box, laser emitted by the laser pen irradiates onto the light source reflector through the incident hole and then is reflected onto the beam splitter, the beam splitter splits the laser into two beams of laser with the same power and parallel to each other, one beam of laser irradiates onto the first cuvette through the first light hole, the other beam of laser irradiates onto the reflector, and the other beam of laser irradiates onto the second cuvette through the second light hole after being reflected by the reflector;

the cover is arranged at the top of the detection box to enable the detection box to form a darkroom, a mobile phone camera shooting hole is formed in the side wall of the detection box corresponding to the middle position of the first cuvette and the second cuvette, a smart phone fixing groove for placing a smart phone is further formed in the side wall of the detection box where the mobile phone camera shooting hole is formed, the smart phone is placed in the smart phone fixing groove, and the camera shoots a sample area in alignment with the mobile phone camera shooting hole.

Preferably, a supporting frame is arranged below the laser pen fixing cylinder and used for supporting the laser pen fixing cylinder;

the bottom of the detection box is provided with two sample grooves, namely a first sample groove and a second sample groove, wherein the first sample groove is used for fixing a first cuvette, and the second sample groove is used for fixing a second cuvette;

the beam splitter is fixed through the beam splitter optical adjustment mirror frame, the reflector is fixed through the reflector optical adjustment mirror frame, the light source reflector is fixed through the light source reflector frame, the beam splitter optical adjustment mirror frame, the reflector optical adjustment mirror frame and the light source reflector frame are provided with internal threads at the bottoms, and the internal threads are matched with the threads at the tops of the positioning columns to fix the beam splitter optical adjustment mirror frame, the reflector optical adjustment mirror frame and the light source reflector frame on the first positioning column, the second positioning column and the third positioning column respectively.

On the other hand, the invention also provides a method for detecting the protein in the water body based on the smart phone, which comprises the following steps of 1, preparing a protein standard solution;

step 2, mixing the protein standard solution with the dye, and reacting at room temperature until the color is stable;

Step 3, adding the protein solution dyed in the step 2 into the portable detection equipment as a sample solution, taking distilled water as a reference, opening a laser pen of the portable detection equipment, and taking a related photo by using a smart phone;

step 4, intercepting the shot photo in an effective area, respectively obtaining R, G, B values of the corresponding areas of the sample solution and the reference solution, and then calculating an A value according to a formula (I);

A=-log(G _{Sample of} /G _{Reference(s) )}(I);

Step 5, taking mixed liquid pictures containing protein standard solutions with different concentrations and dye solutions in sequence, intercepting R, G, B values corresponding to the identification of each effective area, calculating an A value in each picture, and establishing a standard working curve by taking the protein concentration as an abscissa and taking A as an ordinate;

and 6, after the water sample to be detected is preprocessed, determining the corresponding A according to the analogy of the steps 2-4, and converting the protein concentration of the water sample to be detected by combining a standard working curve.

Preferably, in the step 1, the protein is Bovine Serum Albumin (BSA), and the step 1 is specifically to prepare protein standard solutions with the concentration of 128ug/L, 144ug/L, 160ug/L, 176ug/L, 192ug/L, 208ug/L, 224ug/L and 240 ug/L.

Further, the step 2 is specifically that 2mL of protein standard solution is taken and mixed with 2mL of 100mg/L coomassie brilliant blue dye, and the mixture is reacted for 5 to 30 minutes at room temperature, so that the color is stable.

Further, the step 3 specifically comprises the steps of adding 3mL of dyed protein solution into a 5mL centrifuge tube, placing into portable detection equipment, taking distilled water as a reference, opening a laser pen of the equipment, and then photographing for 3 times in each group.

Further, the laser pen emits laser with the wavelength of 500-550nm.

In the step 4, the picture is processed by Matlab software, and the effective area is a light beam area formed by passing laser beams through the solution in the cuvette.

In step 6, a water sample to be tested is collected and filtered by a filter membrane syringe with the aperture of 0.45 μm, and then the pH value of the solution to be tested is adjusted to be neutral by using hydrochloric acid or sodium hydroxide solution to test.

According to the invention, the detection box is taken as a device shell, so that on one hand, the positions of all devices are fixed, and on the other hand, a dark environment for detection is created, and the interference of external environment is avoided.

The invention takes a commercial laser pen as a light source, for example, the commercial laser pen can emit light beams with the wavelength of 532nm, and the light beams are divided into two light beams which are parallel to each other and are perpendicular to the light beams before the laser pen irradiates the light lenses through the light source reflector, the beam splitter and the reflector, and the light beams irradiate into corresponding cuvettes through the light holes. The side wall of the detection box is provided with a mobile phone camera shooting hole, and a smart phone fixing groove is fixed on the outer wall and used for shooting a sample area. The device has simple internal components, no complicated operation and simple assembly and can be used on site.

Compared with the prior art, the invention has the following beneficial effects:

The invention discloses portable equipment based on a smart phone, which is used for detecting proteins in a water body, wherein the portable equipment is used as a detection device to construct a standard linear curve of the proteins, and the smart phone is used for shooting and identifying RGB values, so that the linear relation between the proteins with different concentrations and A is obtained. The water sample to be detected is detected by the portable device, so that the protein concentration of the water sample can be rapidly and accurately measured. The invention reduces the requirement on the detection condition of the actual water sample, takes the actual water sample to be detected as an analysis basis, and realizes the protein determination of the actual water sample, thereby being convenient and quick.

Drawings

Fig. 1 is a perspective view of a portable detection device based on a smart phone according to embodiment 1 of the present invention;

FIG. 2 is a first structural diagram of the inside of the cartridge according to embodiment 1 of the present invention;

FIG. 3 is a second internal structure of the cartridge according to embodiment 1 of the present invention;

FIG. 4 is a third internal structure of the cartridge according to embodiment 1 of the present invention;

FIG. 5 is a diagram showing the construction of the interior of a cartridge according to embodiment 1 of the present invention;

The device comprises a beam splitter, a 2-reflecting mirror, a 3-cuvette, a 3-1 first cuvette, a 3-2 second cuvette, a 4-cover, a 5-light source reflecting mirror, a 6-light source reflecting mirror frame, a 7-smart phone fixing groove, an 8-smart phone camera shooting hole, a 9-laser pen fixing cylinder, a 10 detection box, a 11 partition plate, a 12-light hole, a 12-1 first light hole, a 12-2 second light hole, a 13-entrance hole, a 14-laser pen, a 15 support frame, a 16 positioning column, a 16-1 first positioning column, a 16-2 second positioning column, a 17-1 sample groove, a 17-2 second sample groove, an 18-beam splitter optical adjustment mirror frame and a 19-reflecting mirror optical adjustment mirror frame, wherein the first light hole is formed in the first direction of the beam splitter;

FIG. 6 is a picture of the sample area taken in step 3 of example 2 of the present invention, the right side being the reference and the left side being the sample;

FIG. 7 is a standard working graph of protein concentration versus A value for example 2;

FIG. 8 is an active area division diagram;

FIG. 9 is a graph showing the distribution of the A value of the peripheral region at different protein concentrations;

FIG. 10 is a standard operating curve of example 2 protein concentration versus A ₂＝-log(B _{Sample of} /B _Reference(s) ) value;

FIG. 11 is a graph comparing the results of measuring protein content of water samples by using a standard spectrophotometer and SPSD.

Detailed Description

In order to make the technical problems, technical solutions and advantages to be solved by the present invention more apparent, the following detailed description will be given with reference to the accompanying drawings and specific embodiments.

The materials and reagents used in the present invention are not specifically described and are commercially available. The optical lenses in the portable detection device based on the smart phone in the invention are shown in the following table 1.

TABLE 1

The invention provides a method for detecting protein in a water body based on a smart phone, and the specific embodiment is as follows.

Example 1

A portable detection device (SPSD) based on a smart phone, as shown in fig. 1-5, comprises a laser pen 14, a beam splitter 1, a reflecting mirror 2, a cuvette 3, a cover 4, a light source reflecting mirror 5, a smart phone fixing groove 7, a mobile phone camera shooting hole 8, a laser pen fixing barrel 9 and a detection box 10;

the detection box 10 is provided with an L-shaped baffle plate 11 for dividing the detection box 10 into a light mirror area and a sample area, wherein the baffle plate 11 is provided with a light hole 12, and the light hole 12 comprises a first light hole 12-1 and a second light hole 12-2;

The light mirror area is used for placing the light source reflector 5, the beam splitter 1 and the reflector 2, laser emitted by the laser pen 14 irradiates the light source reflector 5, and light is reflected to the beam splitter 1 through the light source reflector 5; the sample area is used for placing a cuvette 3, and the cuvette 3 comprises a first cuvette 3-1 and a second cuvette 3-2;

In the light mirror area, the side wall of the detection box 10 is provided with an entrance hole 13, the laser pen fixing cylinder 9 is used for fixing the laser pen 14 on the side wall of the detection box 10, laser emitted by the laser pen 14 irradiates onto the light source reflector 5 through the entrance hole 13 and then is reflected onto the beam splitter 1, the beam splitter 1 is used for splitting two laser beams with little difference in success rate and mutually perpendicular, one laser beam irradiates onto the first cuvette 3-1 through the first light hole 12-1, the other laser beam irradiates onto the reflector 2, and the other laser beam irradiates onto the second cuvette 3-2 through the second light hole 12-2 after being reflected by the reflector 2;

The cover 4 is arranged at the top of the detection box 10 to enable the detection box to be a darkroom, a mobile phone camera shooting hole 8 is formed in the side wall of the detection box 10 corresponding to the middle position of the first cuvette 3-1 and the second cuvette 3-2, a smart phone fixing groove 7 for placing a smart phone is further formed in the side wall of the detection box 10 where the mobile phone camera shooting hole 8 is located, the smart phone is placed in the smart phone fixing groove 7, and the camera aims at the mobile phone camera shooting hole 8 to shoot a sample area.

The detection box is a cassette, the position of a light source is fixed by a laser pen fixing cylinder, then a light source reflector, a beam splitter and a reflector are arranged to split laser into two beams with little power difference, the two beams are respectively irradiated in a first cuvette and a second cuvette to enable the two to emit light synchronously, and then the two are shot on the same photo through a mobile phone, so that subsequent analysis is facilitated. The device has simple internal devices, no complicated operation and convenient assembly.

Preferably, a supporting frame 15 is arranged below the laser pen fixing barrel 9 and used for supporting the laser pen fixing barrel 9, in the using process, the laser pen 14 is inserted into the laser pen fixing barrel 9, and laser emitted by the laser pen 14 irradiates onto the light source reflector 5 through the incidence hole 13.

Further, two sample grooves 17 are formed in the bottom of the detection box 10, namely a first sample groove 17-1 and a second sample groove 17-2, wherein the first sample groove 17-1 is used for fixing the first cuvette 3-1, the second sample groove 17-2 is used for fixing the second cuvette 3-2, the position of the cuvette is convenient to fix, the liquid height in the cuvette 3 is higher than that of the light hole 12, and the accuracy of a test result is guaranteed.

Further, three positioning columns 16 are fixed at the bottom of the detection box 10, namely a first positioning column 16-1, a second positioning column 16-2 and a third positioning column 16-3, threads are arranged at the tops of the positioning columns 16, the beam splitter 1 is fixed through a beam splitter optical adjusting lens frame 18, the reflecting mirror 2 is fixed through a reflecting mirror optical adjusting lens frame 19, the light source reflecting mirror 5 is fixed through a light source reflecting lens frame 6, internal threads are arranged at the bottoms of the beam splitter optical adjusting lens frame 18, the reflecting mirror optical adjusting lens frame 19 and the light source reflecting lens frame 6 and are matched with the threads at the tops of the positioning columns 16, the beam splitter optical adjusting lens frame 18, the reflecting mirror optical adjusting lens frame 19 and the light source reflecting lens frame 6 are respectively fixed on the first positioning column 16-1, the second positioning column 16-2 and the third positioning column 16-3, the fixed positions of optical lenses are conveniently determined during field installation, and after the light source reflecting mirrors, the focal positions of the beam splitter and the reflecting mirrors are installed, the focal positions of the lenses are consistent with the laser pen incidence heights, and the accuracy of test results is ensured.

Example 2

A method for detecting protein in a water body based on a smart phone comprises the following steps:

Step 1, preparing bovine serum albumin standard solution with the concentration of 128ug/L, 144ug/L, 160ug/L, 176ug/L, 192ug/L, 208ug/L, 224ug/L and 240ug/L

Step 2, taking 2.5mL of bovine serum albumin standard solution with the concentration of 128ug/L, then adding 500uL of coomassie brilliant blue G250 solution (100 mg/L), and standing for 5 minutes at room temperature to ensure that the color is stable;

Step 3, adding 3mL of dyed protein solution into a 5mL centrifuge tube, putting into the portable detection device of the embodiment 1, taking distilled water as a reference, opening a laser pen of the device, and then photographing, wherein each group is repeated for 3 times as shown in FIG. 6, wherein the wavelength of laser emitted by the laser pen is 532nm in the portable detection device of the embodiment 1;

And 4, intercepting an effective area from a photographed photo (the effective excitation area is a light column area formed by passing laser beams in a cuvette through a solution, and ensuring that the sizes of a reference area and an experimental group area are the same), and respectively obtaining R, G, B values of the corresponding areas of a sample solution and the reference solution, wherein the method comprises the steps of intercepting the effective area picture, storing the effective area picture in a designated folder, and programming the following program by using Matlab software:

i= imread ('file location\picture name. Jpg', 'jpg');

RGB_mean=mean(mean(I));

R_mean=RGB_mean(:,:,1);

G_mean=RGB_mean(:,:,2);

B_mean=RGB_mean(:,:,3);

By running the program, the average RGB value of each effective area picture is calculated, namely the process of converting the optical signal into the electric signal and finally into the number is finished, and the specific data are shown in Table 2;

then calculating the A value according to the formula (I), see Table 3;

A=-log(G _{Sample of} /G _{Reference(s) )}(I);

Step 5, according to the step 2-4, shooting mixed liquid photos of protein standard solutions and dye solutions with different concentrations (144 ug/L, 160ug/L, 176ug/L, 192ug/L, 208ug/L, 224ug/L and 240 ug/L) in sequence, intercepting R, G, B values corresponding to the identification of each effective area, and calculating an A value in each picture, wherein the results are shown in tables 2-3;

TABLE 2

TABLE 3 Table 3

And a standard working curve is established by taking the protein concentration as an abscissa and taking A as an ordinate, as shown in figure 7;

step 6, collecting a water sample to be detected, filtering the water sample by a filter membrane needle cylinder with the aperture of 0.45 mu m, regulating the pH value of the solution to be detected to be neutral by using hydrochloric acid or sodium hydroxide solution, adding 500ul of Coomassie brilliant blue G250 solution into 2.5mL of the solution to be detected, standing for 5min, adding 3mL of the solution after reaction into a cuvette, putting the cuvette into a device sample tank, taking 3mL of distilled water, adding the distilled water into a reference tank, shooting by a smart phone, substituting a photo into a computer program for analysis, extracting RGB value, then calculating corresponding A to be 0.19, and converting the protein concentration of the water sample to be detected to be 152ug/L by combining a standard working curve.

To confirm the beneficial effects of the method of the present invention, the inventors have also conducted the following experiments.

1. Feasibility evaluation

Adding 0.5mL of coomassie brilliant blue G250 solution to 2.5mL of bovine serum albumin standard solution with the concentration of 128ug/L, 144ug/L, 160ug/L, 176ug/L, 192ug/L, 208ug/L, 224ug/L and 240ug/L respectively, fixing the volume to 5mL, standing at room temperature for 5 minutes to ensure that the color is stable, detecting the standard solution by using a standard spectrophotometer and the device of the embodiment 1 of the invention respectively, and establishing a standard working curve according to the detection, wherein R ² = 0.9953 of the standard working curve established by the standard spectrophotometer is shown in figure 7, R ² = 0.9854 of the standard working curve established by the method of the invention is higher in accuracy.

3. Selection of active area

The measurement of the protein was obtained by photographing the cuvette of the apparatus of example 1 indirectly through a smart phone. Therefore, it is important to select the effective area. As shown in fig. 8, the captured image was taken out of the entire position of the cuvette, and then evaluated in two areas, i.e., a light beam area (a light beam area formed by passing the laser beam through the solution in the cuvette) and a peripheral area (an area below the liquid surface in the cuvette other than the light beam area).

Adding 0.5mL of coomassie brilliant blue G250 solution to 2.5mL of bovine serum albumin standard solutions with the concentration of 128ug/L, 144ug/L, 160ug/L, 176ug/L, 192ug/L, 208ug/L, 224ug/L and 240ug/L respectively, fixing the volume to 5mL, standing at room temperature for 5 minutes to stabilize the color, taking 3mL of dyed protein solution, and performing photographing measurement by the device of the embodiment 1, wherein 3mL of distilled water is used as reference. And calculating the related A values of the two areas, and establishing a relation curve of the concentration and the A value, wherein the working curve of the light beam area is shown in fig. 7, the peripheral area is shown in fig. 9, the light beam area is taken as an effective area, the obtained standard curve has a good linear relation, but the related data of the peripheral area has no obvious linear relation. In summary, it is reasonable to select the light pillar area as the effective area selected for subsequent measurement.

4. RGB channel selection

In example 2, 3mL of a mixed solution of 128, 144, 160, 176, 192, 208, 224, 240ug/L bovine serum albumin solution and coomassie brilliant blue G-250 solution was sequentially poured into a cuvette, and placed into a left sample cell of a portable detection device based on a smart phone, while a right sample cell was selected from 3mL of distilled water as a reference. Each concentration was measured three times and three photographs were taken and the average RGB values were obtained for the intercepted active area, see table 2.

As can be seen from table 2, since the R value of each photo is not substantially changed, the obtained RGB values are one-to-one corresponding to the RGB values of the corresponding reference, a ₁＝-log(G _{Sample of} /G _Reference(s) ) and a ₂＝-log(B _{Sample of} /B _Reference(s) ) are calculated, and then standard operation curves of the concentration and a value are established, and the results are shown in table 4, fig. 7 and fig. 10.

TABLE 4 Table 4

As can be seen from fig. 10, there is a certain linear relationship between the G ratio of protein solutions at different concentrations, but no obvious linear relationship with R, B ratio. Thus, when a smart phone based portable detection device based on a smart phone measures proteins, it is possible to use the G channel as a detection channel and establish linearity. In addition, the linear curve established by the G channel has a linear equation of y= -0.0015x+0.42 and R ² = 0.9854. It is explained that the establishment of a linear curve of RhB through the G channel is more sensitive and accurate.

6. Accuracy evaluation

Water samples of the inner, peripheral and outer waterways of the schools were collected, and 6 water samples were collected in total and measured with a standard spectrophotometer and the apparatus of example 1, respectively, three times per sample. Example 1 device measurements the final results were scaled using the linear fit curve of fig. 7. The method of converting the final turbidity using the linear fitting curve of fig. 7 was referred to as SPSD measurement results, as shown in table 5.

TABLE 5

As can be seen from Table 5, the detection results of the same water sample using the standard spectrophotometer are not significantly different from the detection results of the SPSD of the present invention. The results of measuring the same water sample are compared, as shown in FIG. 11. As can be seen from FIG. 11, the ratio of the turbidity results of the water sample measured by the device of example 1 to the turbidity results measured by the turbidimeter is controlled within 0.93-1.10, and the ratio is about 1.000, which shows that the difference between the measurement results is small, and the results of the measurement of the turbidity of the water body by the portable detection device assisted by the smart phone are reliable.

In conclusion, the portable detection device is used for carrying out simple photographing treatment, the corresponding protein concentration can be obtained by calculating the A value, the portable detection device is simple, the on-site detection of the water sample can be realized, and the detection precision is high.

While the foregoing is directed to the preferred embodiments of the present invention, it will be apparent to those skilled in the art that various modifications and variations can be made without departing from the principles of the invention.

Claims (8)

1. The method for detecting the protein in the water body based on the smart phone is characterized by comprising the following steps of:

step 1, preparing a protein standard solution;

Step 2, mixing 2mL of protein standard solution with 2mL of coomassie brilliant blue dye, and reacting for 5-30 minutes at room temperature to stabilize the color;

step 3, adding the protein solution dyed in the step 2 into portable detection equipment as a sample solution, opening a laser pen of the portable detection equipment by taking distilled water as a reference, and taking a related photo by using a smart phone, wherein the wavelength of laser emitted by the laser pen is 500-550nm;

step 4, intercepting the shot photo in an effective area, respectively obtaining R, G, B values of the corresponding areas of the sample solution and the reference solution, and then calculating an A value according to a formula (I);

A=-log(G _{Sample of} /G _Reference(s) )(I);

Step 5, taking mixed liquid pictures containing protein standard solutions with different concentrations and dye solutions in sequence, intercepting R, G, B values corresponding to the identification of each effective area, calculating an A value in each picture, and establishing a standard working curve by taking the protein concentration as an abscissa and taking A as an ordinate;

And step 6, after the water sample to be detected is preprocessed, determining the corresponding A according to the analogy of the steps 3-4, and converting the protein concentration of the water sample to be detected by combining a standard working curve.

2. The method according to claim 1, wherein in step 1, the protein is Bovine Serum Albumin (BSA).

3. The method according to claim 2, wherein the step 1 is to prepare a standard protein solution having a concentration of 128ug/L, 144ug/L, 160ug/L, 176ug/L, 192ug/L, 208ug/L, 224ug/L, 240 ug/L.

4. The method according to claim 1, wherein the step 3 is specifically that 3mL of the dyed protein solution is added into a 5mL cuvette, put into a portable detection device, distilled water is used as a reference, a laser pen of the device is turned on, and then photographing is performed, and each group is repeated 3 times.

5. The detection method according to claim 1, wherein in the step 4, the picture is processed by Matlab software, and the effective area is a light beam area formed by passing a laser beam through a solution in a cuvette.

6. The method according to claim 1, wherein in the step 6, the water sample to be tested is collected, filtered through a 0.45 μm pore size filter cartridge, and then the pH of the solution to be tested is adjusted to neutral by using hydrochloric acid or sodium hydroxide solution.

7. The method according to claim 1, wherein in the step 3, the portable detection device includes a laser pen, a light source reflector, a beam splitter, a reflector, a cuvette, a cover, a laser pen holder, and a detection box;

The detection box is internally provided with a baffle plate for dividing the detection box into a light mirror area and a sample area, wherein the baffle plate is provided with light holes, and the light holes comprise a first light hole and a second light hole;

The light mirror area is used for placing the light source reflector, the beam splitter and the reflector, laser emitted by the laser pen irradiates the light source reflector, and light rays are reflected to the beam splitter through the light source reflector; the sample area is used for placing a cuvette, and the cuvette comprises a first cuvette and a second cuvette;

In the light mirror area, an incident hole is formed in the side wall of the detection box, the laser pen fixing cylinder is used for fixing a laser pen on the side wall of the detection box, laser emitted by the laser pen irradiates onto the light source reflector through the incident hole and then is reflected onto the beam splitter, the beam splitter splits the laser into two beams of laser with the same power and parallel to each other, one beam of laser irradiates onto the first cuvette through the first light hole, the other beam of laser irradiates onto the reflector, and the other beam of laser irradiates onto the second cuvette through the second light hole after being reflected by the reflector;

The cover is arranged on the top of the detection box, so that the detection box forms a darkroom;

The intelligent mobile phone fixing groove for placing the intelligent mobile phone is further formed in the side wall of the detection box where the mobile phone camera shooting hole is located, the intelligent mobile phone is placed in the intelligent mobile phone fixing groove, and the mobile phone shooting hole is aligned to the mobile phone camera shooting hole to shoot a sample area.

8. The detection method according to claim 7, wherein a supporting frame is provided below the laser pen fixing barrel for supporting the laser pen fixing barrel;

the bottom of the detection box is provided with two sample grooves, namely a first sample groove and a second sample groove, wherein the first sample groove is used for fixing a first cuvette, and the second sample groove is used for fixing a second cuvette;

the beam splitter is fixed through the beam splitter optical adjustment mirror frame, the reflector is fixed through the reflector optical adjustment mirror frame, the light source reflector is fixed through the light source reflector frame, the beam splitter optical adjustment mirror frame, the reflector optical adjustment mirror frame and the light source reflector frame are provided with internal threads at the bottoms, and the internal threads are matched with the threads at the tops of the positioning columns to fix the beam splitter optical adjustment mirror frame, the reflector optical adjustment mirror frame and the light source reflector frame on the first positioning column, the second positioning column and the third positioning column respectively.