Detection reagent and detection kit for lactose intolerance judgment and qualitative judgment method for lactose content in excrement sample

Abstract

The invention discloses a detection reagent and a detection kit for lactose intolerance judgment and a qualitative judgment method for the lactose content in an excrement sample. The detection reagent is used for detecting an excrement sample to judge whether the excrement sample is a lactose-intolerant sample or not, comprises organic dye and strong-alkali weak-acid salt, presents different colors before and after reacting with lactose, and judges whether the excrement sample is the lactose-intolerant sample or not by reacting the excrement sample with the detection reagent. The detection reagent provided by the invention can be used for directly qualitatively detecting the content of reducing sugar in an excrement sample extracting solution according to different colors presented by a reaction system before and after the reaction of organic dye and lactose, so that whether a sample is a lactose intolerant sample or not can be quickly judged; meanwhile, heavy metal ions and the like are prevented from being used, the experiment safety is improved, and the method is friendly to experimenters.

Description

Technical Field

[0001] This invention relates to the field of biological detection technology, specifically to a detection reagent, a detection kit, and a qualitative method for determining lactose content in fecal samples for assessing lactose intolerance. Background Technology

[0002] Lactose is the only disaccharide found in human milk and is also the main carbohydrate found in milk and other dairy products. It is the main energy source for infants and young children. The lactose content in breast milk is 7.2g / 100mL, while the lactose content in cow's milk is 4.7g / 100mL.

[0003] After lactose enters the body, it is broken down into glucose and galactose by lactase in the small intestine. Galactose is a component of glycolipids in brain and nerve tissue and is essential for infant brain development. Due to congenital lactase deficiency or other reasons causing reduced lactase activity, lactose cannot be broken down into glucose and galactose. Undigested lactose descends the digestive tract into the colon, where it is fermented by bacteria to produce short-chain fatty acids such as acetic acid, propionic acid, and butyric acid, as well as gases such as methane, H2, and CO2. The unfermented lactose continues to be excreted in feces. Because the fermentation process produces acid and gas, increasing the osmotic pressure in the intestines, clinical symptoms such as borborygmus, abdominal pain, rectal gas, and osmotic diarrhea may occur. The presence of these clinical symptoms is called lactose intolerance (LI), while the absence of clinical symptoms is called lactase deficiency or lactose malabsorption (LM). Chinese people are a high-risk group for LM and LI. LM and LI are not just unpleasant symptoms after drinking milk. Because changes in the biochemical state in the intestines can affect the absorption of some nutrients, if not intervened in time, they can cause nutritional diseases of varying degrees.

[0004] Common diagnostic methods for lactose intolerance include duodenal mucosal biopsy, H2 breath test, lactose tolerance test (LTT), and genetic testing. Currently, for neonatal clinical applications, the main method is a non-invasive, rapid screening approach combining fecal reducing sugar detection with fecal pH. The specific technical principle of reducing sugar detection involves qualitative determination using the lead acetate-ammonium hydroxide method or a modified Benedict's reagent method; alternatively, pH test strips can be used. When undigested lactose enters the colon, intestinal flora breaks it down into lactic acid, fatty acids, and other organic acids, making the stool acidic. Stools of lactose-intolerant individuals are typically acidic (<5.5), while stools of lactose-tolerant individuals are typically neutral or weakly acidic. Therefore, measuring reducing sugars and pH in stool can be used to determine the degree of lactose breakdown.

[0005] The detection steps of the lead acetate-ammonium hydroxide method are as follows: Take fresh feces, add distilled water, stir, let stand, remove residue, take the supernatant, add lead acetate, heat to boiling over an alcohol lamp, then add ferric hydroxide solution, heat to boiling, and perform semi-quantitative lactose determination based on the amount of precipitate: no precipitate, lactose content is 0% (-); trace dark pink precipitate, lactose content is 0.1%~0.5% (±); small amount of precipitate, lactose content is 0.5%~0.75% (+); large amount of precipitate, lactose content is 0.75%~1% (2+); large amount of precipitate, lactose content is 1%~2% (3+); large amount of precipitate, lactose content is >2% (4+). Result interpretation criteria: > (+) for reducing sugars indicates a positive result for fecal reducing sugar detection; a positive result indicates malabsorption of reducing sugars.

[0006] The detection steps of the modified Benedict's reagent method are as follows: Prepare lactose solutions with concentrations of 0%, 0.1%, 0.2%, 0.4%, 0.5%, 0.75%, 1%, 1.5%, and 2%, respectively. Add the modified Benedict's reagent, mix well, and place in a boiling water bath. Observe the formation of a red precipitate. Remove the reaction tube from the boiling water bath, cool, and centrifuge. The degree of positivity can be determined based on the color of the liquid and the amount of red precipitate. The approximate content is expressed as a percentage. No precipitate (blue) indicates 0% lactose content (-); trace amounts of green precipitate indicate 0.1%–0.5% lactose content (±); a small amount of slightly red precipitate indicates 0.5%–0.75% lactose content (+); a relatively large amount of light yellow precipitate indicates 0.75%–1% lactose content (2+); a large amount of dark yellow precipitate indicates 1%–2% lactose content (3+); a large amount of yellowish-brown precipitate indicates >2% lactose content (4+). To determine the reducing sugar content of a sample, take fresh feces, add distilled water, mix thoroughly, centrifuge, collect the supernatant, add modified Benedict's reagent, mix well, and compare with the above reaction.

[0007] Therefore, both the commonly used lead acetate method and the modified Benedict's reagent method involve the use of heavy metal salts, posing inherent safety hazards. Lead acetate in the lead acetate method is particularly harmful to laboratory personnel, especially as it easily decomposes under heating conditions, causing serious consequences and requiring careful handling. Furthermore, the detection and interpretation processes described above are quite complex, hindering clinical application due to their inconvenience. Additionally, improving accuracy requires combining reducing sugar detection results with pH detection results, which is also cumbersome. Summary of the Invention

[0008] To overcome the above-mentioned shortcomings, the present invention aims to provide a method for detecting lactose intolerance through fecal samples.

[0009] One of the objectives of this invention is to provide a detection reagent for determining lactose intolerance, which is used to detect fecal samples to determine whether the sample is lactose intolerant. The reagent includes an organic dye and a strong base-weak acid salt, and exhibits different colors before and after reacting with lactose. The determination of whether a fecal sample is lactose intolerant is made by reacting the fecal sample with the detection reagent.

[0010] The detection reagent of the present invention has the following beneficial effects: ① Using the detection reagent of the present invention, the level of reducing sugar content in fecal sample extract can be qualitatively detected directly based on the different colors of the reaction system before and after the organic dye reacts with lactose. This allows for rapid determination of whether a sample is lactose intolerant, while avoiding the use of heavy metal ions, thus improving the safety of the experiment and making it more user-friendly for laboratory personnel. ② This invention utilizes a strong base-weak acid salt to ensure that the detection reagent itself is slightly alkaline. This is because the short-chain fatty acids in the fecal samples of lactose-intolerant patients are usually up to 100mM. Even after diluting the fecal sample (taking a fecal sample diluted 10 times for testing as an example, the short-chain fatty acids are still about 10mM), the alkalinity of the detection reagent is still slightly lower than the acidity of the sample, thus better identifying a sufficiently acidic sample environment. Therefore, it can sensitively identify lactose-intolerant samples. ③ This invention can detect reducing sugars and pH factors in a one-step colorimetric reaction, which greatly improves the convenience and operability of lactose intolerance detection and has high value in the clinical application of reducing sugar detection in fecal samples.

[0011] Furthermore, the organic dye is selected from at least one of the following: methylene blue, 2,6-dichloroindophenol, methylene blue analogue, methylene blue, methyl orange, or triphenylmethane dyes (such as crystal violet).

[0012] The strong base weak acid salt is selected from at least one of the following: sodium bicarbonate, sodium fluoride, sodium acetate, or sodium hypochlorite.

[0013] Furthermore, the detection reagents include methylene blue and sodium bicarbonate.

[0014] Furthermore, the methylene blue content in the detection reagent is 0.3% - 0.9%, and the sodium bicarbonate concentration is 5 - 10 mM. The lower the concentration of methylene blue in the chromogenic solution, the higher the detection sensitivity; however, when the concentration reaches 1.2%, the detection sensitivity decreases significantly. Conversely, the lower the concentration, the paler the color, and the less noticeable the color change.

[0015] Furthermore, the fecal sample is pretreated before reacting with the detection reagent. This pretreatment is achieved by loading the fecal sample into a fecal collection tube pre-filled with activated carbon and then shaking it. Therefore, by using activated carbon for pretreatment, reducing agents and substances that interfere with color reactions, such as pigments, vitamin C, and bilirubin, can be removed from the sample, and lumps or particulate matter in the feces can be filtered out through the fecal collection tube. The present invention also provides a test kit comprising the aforementioned test reagents.

[0016] This invention also provides a qualitative method for determining the lactose content in fecal samples, which utilizes the aforementioned detection reagents and includes the following steps: Fecal sample pretreatment steps; Reaction steps with the test reagent: Add the pretreated fecal sample to the aforementioned test reagent solution and react at room temperature; the volume of the test reagent solution should be larger than the volume of the fecal sample. During the reaction, only 1-2 drops or a few drops of the pretreated fecal sample need to be added to the test reagent solution to make the pH of the entire reaction system more similar to the acidity or alkalinity of the fecal sample.

[0017] The color comparison step with the colorimetric standard is as follows: Compare the color of the reaction solution obtained after the fecal sample reacts with the test reagent with the set colorimetric standard to determine the level of lactose in the fecal sample.

[0018] The color development standard includes a first color state exhibited by the organic dye in the system at a first concentration, and a second color state exhibited by the organic dye in the system at a second concentration, wherein the first concentration is less than the second concentration.

[0019] When the color of the reaction system obtained after the fecal sample reacts with the test reagent is in the first color state, it is determined that the fecal sample has a high lactose content; when the color of the reaction system obtained is in the second color state, it is determined that the fecal sample has a low lactose content.

[0020] The "qualitative determination of lactose content" in this invention refers to the determination of the lactose content in fecal samples. Since the detection of lactose-intolerant samples does not require the detection of absolute lactose content, and even healthy samples contain small amounts of lactose, this application provides a very quick and convenient method for determining whether a sample is lactose intolerant by qualitatively determining the lactose content in the fecal sample and applying it to the detection process. Therefore, the color change of the reaction system is used to determine whether a fecal sample is lactose intolerant.

[0021] Furthermore, the step of comparing the color with the colorimetric standard includes: Colorimetric standard setting steps: Prepare standard test reagents of different concentrations. The concentration of organic dyes in each standard test reagent is set in a gradient. Record the color state of the test reagent at different organic dye concentrations (color state can refer to the depth of color or different colors at different concentrations or pH) and match it with the concentration range of different organic dyes to set the color depth level. The color of the fecal sample reaction solution after reacting with the test reagent is compared with the color of the reagent obtained from the color development standard setting step, and the corresponding color depth level is matched.

[0022] The lowest concentration of organic dye in each standard test reagent is considered the "organic dye at the first concentration" of the aforementioned colorimetric standard; the highest concentration of organic dye in each standard test reagent is considered the "organic dye at the second concentration" of the colorimetric standard. Color depth grades include the color state corresponding to the first concentration and the color state corresponding to the second concentration, and may also include the color state corresponding to the concentration range between the first and second concentrations.

[0023] The reaction solution of the fecal sample after reacting with the test reagent is compared with the color of the reagent obtained from the colorimetric standard setting step, and the corresponding color depth level is matched. Taking methylene blue as an organic dye as an example, if the sample is lactose intolerant, the reaction solution after reacting with the test reagent will be colorless (i.e., the first color state); conversely, if the sample is healthy, because the fecal sample does not contain lactose or has a very low lactose content, the reaction solution will still be a deeper blue (i.e., the second color state).

[0024] Furthermore, the detection reagent is prepared from 7.5 mM sodium bicarbonate and 0.3%-0.9% methylene blue.

[0025] Furthermore, the fecal sample pretreatment step includes: Fecal samples were added to a fecal collection tube pre-loaded with activated carbon, and purified water was added to dilute and disperse the sample. The mass ratio of activated carbon to fecal sample was 1:1. The sample was shaken violently for a period of time and then left to stand. The processed sample was then dripped from the sample outlet of the fecal collection tube. Attached Figure Description

[0026] Figure 1 This figure shows a color comparison of methylene blue at different concentrations in a colorimetric standard according to an embodiment of the present invention. In the figure, the more "+" signs there are, the deeper the color. Detailed Implementation

[0027] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby providing a clearer and more explicit definition of the scope of protection of the present invention.

[0028] Example 1: This embodiment presents a novel method for detecting lactose intolerance using fecal samples. The specific steps are as follows: ① Stool sample pretreatment: a) Add the fecal sample to a fecal collection tube pre-filled with activated carbon, and add purified water to dilute and disperse the sample.

[0029] In some implementations, the mass ratio of activated carbon to fecal sample is 1:1. For example, if the mass of the fecal sample is 0.2g, the activated carbon pre-filled in the fecal collection tube is also 0.2g, and 1mL of purified water is added accordingly to dilute and disperse the sample.

[0030] b) Vigorously shake the sample from step a) for a period of time, and then let it stand. Drip the processed sample from the sample outlet of the fecal collection tube.

[0031] In some implementations, the shaking time can be 30 seconds, 40 seconds or 60 seconds, and after standing for 2 minutes, 2 drops (about 80 μL) of the processed sample are dripped from the sample outlet of the fecal collection tube.

[0032] The present invention uses step ① to utilize the strong adsorption properties of activated carbon to remove reducing and color-interfering substances such as pigments, vitamin C, and bilirubin from the sample, and filters out lumps or particles in the feces through the fecal collection tube.

[0033] ② Reaction with the detection reagent: Add the sample treated in step ① to the detection reagent (approximately 320 μl) and react at room temperature for 5 minutes. In some embodiments, the detection reagent is a solution containing methylene blue and sodium bicarbonate at different concentrations. The concentration of sodium bicarbonate is 5-10 mM, for example, 5 mM, 6 mM, 7.5 mM, 8.5 mM, or 10 mM.

[0034] In some implementations, the volume ratio of the chromogenic solution to the sample is 8:1 to 8:3. For example, the fecal sample is 80 μl, and the chromogenic solution is 320 μl; or the chromogenic solution is 260 μl; or the chromogenic solution is 210 μl, or other volumes. Choosing this volume ratio ensures sensitive detection of the sample and a clear chromogenic effect.

[0035] ③ Steps for comparing colors with color development standards: By comparing the color of the reaction solution obtained after the fecal sample reacts with the test reagent with the set colorimetric standard, the lactose content in the fecal sample can be qualitatively determined. The colorimetric standard includes the first color state exhibited by the organic dye in the system at a first concentration and the second color state exhibited by the organic dye in the system at a second concentration. The first concentration is less than the second concentration. When the color of the reaction system obtained after the fecal sample reacts with the test reagent is in the first color state, it is determined that the lactose content in the fecal sample is high; when the color of the reaction system obtained is in the second color state, it is determined that the lactose content in the fecal sample is low.

[0036] Because the stool of lactose-intolerant individuals is typically acidic (<5.5), the lactose content in their stool is elevated. Under these conditions, methylene blue is oxidized to methylene white, resulting in a colorless solution. The stool of lactose-tolerant individuals is typically neutral or weakly acidic, with lower glucose and lactose content; therefore, methylene blue is not oxidized and remains blue.

[0037] If the solution remains blue after the reaction, it indicates that the reducing sugar in the sample is negative; if the solution is colorless after the reaction, it indicates that the reducing sugar in the sample is positive; the lighter the color, the higher the concentration of reducing sugar.

[0038] Judging the color rendering effect by the depth of color is based on the color intensity corresponding to different concentrations of methylene blue.

[0039] In some implementations, the color development standard is set as follows: Standard test reagents of different concentrations are prepared, with the concentrations of organic dyes in each reagent set in a gradient. The color state of the test reagents at different organic dye concentrations is recorded and matched with different organic dye concentration ranges to determine the color depth level. For example, the color is defined as "-" when the weight content of methylene blue is 0-0.15%; "+" when the weight content is 0.15% to 0.3%; "++" when the weight content is 0.3% to 0.6%; "+++" when the weight content is 0.6% to 0.9%; and "++++" when the weight content is >0.9%. The color comparison for different methylene blue contents is as follows: Figure 1 As shown.

[0040] Therefore, when the lactose content in a fecal sample is high, the organic dye is reduced by the lactose, and the reaction system is colorless, exhibiting the first color state (i.e., [color not specified]). Figure 1The color indicated by the "-" sign in the sample indicates lactose intolerance. When lactose levels are low in the fecal sample, the organic dye is hardly reduced by lactose, resulting in a deep blue color and a secondary color (e.g., if it reaches a certain level). Figure 1 The color indicated by "++++" indicates that the lactose content in the fecal sample is lower than the set standard value, and thus the sample can be judged as a healthy sample.

[0041] The color of the fecal sample reaction solution after reacting with the test reagent is compared with the color of the reagent obtained from the color development standard setting step, and the corresponding color depth level is matched.

[0042] Example 2: Screening for methylene blue concentration The detection performance of different concentrations of methylene blue on lactose / simulated samples was compared to screen samples with varying concentrations, using the ability to distinguish between different lactose concentrations as the criterion. Simulated samples were lactose / fecal matrix samples of known concentrations, specifically 0.125%, 0.25%, 0.5%, 0.75%, 1%, and 1.25%. Three parallel experiments were conducted for each concentration.

[0043] Table 1. Effect of different methylene blue concentrations on detection results

[0044] The above colorimetric reaction shows that the lower the concentration of methylene blue in the developing solution, the higher the detection sensitivity. However, at a concentration as high as 1.2%, the detection sensitivity drops significantly. Furthermore, the lower the concentration, the weaker the color, with minimal color change. Based on the results, the suitable detection sensitivity for methylene blue is 0.3%–0.9%.

[0045] Example 3: Detection performance of sample pH on different concentrations of lactose / simulated samples Following the detection procedure of Example 1, fecal samples containing different concentrations of lactose were set up, and fecal samples with different pH values ​​were used as the matrix to test the color development effect of the colorimetric solution containing 0.6% methylene blue and 7.5 mM sodium bicarbonate.

[0046] Table 2. Comparison of the effects of different sample pH values ​​on detection results

[0047] As can be seen from the colorimetric results in Table 2, the detection sensitivity of the colorimetric solution gradually decreases with increasing fecal matrix pH, and the performance deteriorates significantly at alkaline conditions, becoming virtually undetectable within the tested lactose concentration range. When the fecal matrix pH is <5.8, fecal samples containing lactose concentrations above 0.25% can be effectively detected.

[0048] This application primarily uses qualitative detection to determine the lactose content in fecal samples, typically only accurately identifying cases where the lactose content is greater than 0.25%. Therefore, the method of this invention cleverly utilizes the pH characteristics of actual fecal samples. While the sensitivity of the detection solution decreases when the pH of the fecal sample is >5.8, as mentioned earlier, normal fecal samples naturally contain low levels of lactose, or even none at all. Consequently, the resulting reaction solution is darker in color, thus essentially confirming the sample as healthy. Furthermore, within the pH range where the detection solution of this invention can sensitively perform its detection function (below 5.8), the detection results are both sensitive and easy to observe, ensuring accuracy and preventing misdiagnosis of lactose intolerance simply due to a low pH.

[0049] Therefore, by screening the concentration of methylene blue, this invention determines that the detection sensitivity range of methylene blue is 0.3%-0.9%. Furthermore, it cleverly utilizes the characteristic that the detection solution of this invention has higher detection sensitivity under acidic conditions. Thus, the method of this invention can effectively identify fecal samples from lactose-intolerant patients (pH < 5.5, reducing sugar concentration > 0.25%). The colorimetric solution used in this method is inexpensive, and the colorimetric reaction is intuitive, greatly improving the detection efficiency of lactose content in fecal samples.

[0050] Example 4: Comparison of this method with other sample tests Eight real clinical stool samples were selected, including six diagnosed with lactose intolerance and two healthy samples. Each sample was tested three times. The traditional modified Benedict's reagent method + pH method was compared with the colorimetric method of the present invention in Example 1 (the colorimetric solution contained 0.6% methylene blue and 7.5 mM sodium bicarbonate). The comparison of the test results is shown in Table 3. The modified Benedict's method is as follows: Prepare lactose solutions with concentrations of 0%, 0.1%, 0.2%, 0.4%, 0.5%, 0.75%, 1%, 1.5%, and 2%, respectively. Take 0.5 mL of each solution and add 0.5 mL of the modified Benedict's reagent. Mix well and place in a boiling water bath for 3 min, observing the formation of a red precipitate. Remove the reaction tube from the boiling water bath, cool it, and centrifuge at 3000 r / min for 3 min using a standard centrifuge. The degree of positivity can be determined based on the color of the liquid and the amount of red precipitate. The approximate content is expressed as a percentage. No precipitate (blue) indicates 0% lactose (-); trace amounts of green precipitate indicate 0.1%–0.5% lactose (±); a small amount of slightly red precipitate indicates 0.5%–0.75% lactose (+); a relatively large amount of light yellow precipitate indicates 0.75%–1% lactose (2+); a large amount of dark yellow precipitate indicates 1%–2% lactose (3+); a large amount of yellowish-brown precipitate indicates >2% lactose (4+). Take 1 g of fresh feces, add 2 mL of distilled water, mix thoroughly, and centrifuge at 3000 r / min for 3 min. Then take 0.5 mL of the supernatant, add 0.5 mL of modified Benedict's reagent, mix well, and compare with the above reaction to determine the reducing sugar content of the sample.

[0051] Table 3 Comparison of detection results between the detection method of the present invention and the modified Benedict's reagent method

[0052] As shown in Table 3, the method of the present invention and the modified Benedict's method + pH method have good consistency in the diagnosis of lactose intolerance, indicating that the method of the present invention is a good method for detecting lactose intolerance. It can maintain the same detection results as the traditional detection method, and the reaction time is significantly shortened. Moreover, the reagents used in the reaction process are safe and non-toxic. The above embodiments are only for illustrating the technical concept and features of the present invention. Their purpose is to enable those skilled in the art to understand the content of the present invention and implement it. They should not be used to limit the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A detection reagent for determining lactose intolerance, used to detect fecal samples to determine whether they are lactose intolerant samples, characterized in that, It includes organic dyes and strong base-weak acid salts, and exhibits different colors before and after reacting with lactose. The determination of whether a fecal sample is lactose intolerant is made by reacting the test reagent with the sample.

2. The detection reagent for determining lactose intolerance according to claim 1, characterized in that, The organic dye is selected from at least one of the following: methylene blue, 2,6-dichloroindophenol, methylene blue analog, methylene blue, methyl orange or triphenylmethane dyes; The strong base weak acid salt is selected from at least one of the following: sodium bicarbonate, sodium fluoride, sodium acetate, or sodium hypochlorite.

3. The detection reagent for determining lactose intolerance according to claim 2, characterized in that, The detection reagents include methylene blue and sodium bicarbonate.

4. The detection reagent for determining lactose intolerance according to claim 3, characterized in that, The methylene blue content in the test reagent is 0.3%-0.9%, and the sodium bicarbonate content is 5-10 mM.

5. The detection reagent for determining lactose intolerance according to any one of claims 1-4, characterized in that, The fecal sample is pretreated and then reacted with the detection reagent. The pretreatment is achieved by loading the fecal sample into a fecal collection tube pre-filled with activated carbon and then shaking it.

6. A test kit, characterized in that, It includes the detection reagent according to any one of claims 1-5.

7. A method for qualitatively determining the lactose content in a fecal sample, characterized in that, The detection reagent according to any one of claims 1-5 is used to achieve the following steps: Fecal sample pretreatment steps; Reaction step with the test reagent: Add the pretreated fecal sample to the solution of the test reagent according to any one of claims 1-5, and react at room temperature; The color comparison step with the colorimetric standard is as follows: Compare the color of the reaction solution obtained after the fecal sample reacts with the test reagent with the set colorimetric standard. This allows for a qualitative judgment on the lactose content in the fecal sample. The color development standard includes a first color state exhibited by the organic dye in the system at a first concentration, and a second color state exhibited by the organic dye in the system at a second concentration, wherein the first concentration is less than the second concentration. When the color of the reaction system obtained after the fecal sample reacts with the test reagent is in the first color state, it is determined that the fecal sample has a high lactose content; when the color of the reaction system obtained is in the second color state, it is determined that the fecal sample has a low lactose content.

8. The qualitative determination method for lactose content in fecal samples according to claim 7, characterized in that, The step of comparing the color with the colorimetric standard includes: Colorimetric standard setting steps: Prepare standard test reagents of different concentrations. The concentration of organic dyes in each standard test reagent is set as a gradient. Record the color state of the test reagent at different organic dye concentrations and match it with the concentration range of different organic dyes to set the color depth level. The color of the fecal sample reaction solution after reacting with the test reagent is compared with the color of the reagent obtained from the color development standard setting step, and the corresponding color depth level is matched.

9. The qualitative determination method for lactose content in fecal samples according to claim 8, characterized in that, The detection reagent is prepared from 7.5 mM sodium bicarbonate and 0.3%-0.9% methylene blue.

10. The method for qualitatively determining the lactose content in fecal samples according to any one of claims 7-9, characterized in that, The fecal sample pretreatment steps include: Fecal samples were added to a fecal collection tube pre-loaded with activated carbon, and purified water was added to dilute and disperse the sample. The mass ratio of activated carbon to fecal sample was 1:

1. The sample was shaken violently for a period of time and then left to stand. The processed sample was then dripped from the sample outlet of the fecal collection tube.

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