Method and kit for rapidly detecting sulfur dioxide in food

Abstract

The invention aims to provide a method and a kit for rapidly detecting sulfur dioxide in food, and the method and the kit have the advantages of simple operation, rapid detection and stable and reliable result, and specifically comprise the following steps: grinding or cutting a sample to be detected into pieces, adding the pieces into a centrifugal tube, adding water, soaking for 10 minutes, adding a sulfite rapid detection reagent B, and rapidly detecting sulfur dioxide in food. Adding a sulfite rapid detection reagent C, adding an iodine standard solution which is diluted by 15.5-126 times, observing a chromogenic reaction, and measuring absorbance; the sulfite rapid detection reagent B is a hydrochloric acid solution, and the sulfite rapid detection reagent C is a starch indicating solution.

Description

Technical Field

[0001] The invention belongs to the field of food additive detection, and particularly relates to a method and a kit for rapidly detecting sulfur dioxide in food. Background Art

[0002] Sulfur dioxide (SO2), also known as sulfurous anhydride, is the most common sulfur oxide and the main component of sulfuric acid raw gas. It is colorless and toxic gas with a pungent odor at room temperature. It has a higher density than air, is easily liquefied, and is easily soluble in water (about 1:40). The density is 2.551g / L (gas, at 20 degrees Celsius). Sulfur dioxide has a bleaching effect on food (principle: it combines with colored substances to form colorless unstable substances) and an antiseptic effect. Sulfur dioxide can make the product look bright and white (characteristic: incomplete bleaching). It is usually used for bleaching and antiseptic of food. At the same time, it is an important way to synthesize sulfur in industry and as an insecticide, fungicide, bleaching agent and reducing agent. In the atmosphere, sulfur dioxide will oxidize to form sulfuric acid mist or sulfate aerosol, and it is also an important precursor of environmental acidification. It is a very common bleaching agent, preservative, and antioxidant on the market. It can be used not only in food, but also in Chinese medicinal materials. However, due to different market standards and too many types of food, there are many unscrupulous businesses that use sulfur dioxide excessively or unreasonably in order to beautify food. Sulfur dioxide food is toxic to the human body. As we all know, sulfur dioxide is an acidic oxide that has a strong irritating effect on the respiratory and digestive tracts of the human body. In addition, sulfur dioxide will enter the human body with food to generate sulfites. The human body has the function of decomposing sulfates and can oxidize them into sulfates. The human body will then detoxify them through the liver. After detoxification, they will eventually be excreted from the body through urine. It does not cause much harm to the human body, but if it is excessive, it will cause harm to the human body. The human body will ingest sulfur dioxide, which is composed of substances such as sulfites, for a long time, which will destroy vitamin B1 in the human body. This will affect the normal growth and development of children, and will also cause intestinal disorders, leading to symptoms such as diarrhea and headaches. If it is acute sulfur dioxide poisoning, it may cause irritation of the eyes and nasal mucosa, and in severe cases, it may cause throat spasms. If you accidentally eat food containing sulfur dioxide, it may cause nausea and vomiting, and it will also affect the body's absorption of calcium. If an asthmatic patient eats food containing sulfur dioxide, he may be allergic and cause asthma. Sulfite is a very strong carcinogen. Currently, the commonly used sulfur dioxide detection methods mainly include iodine titration, chromatography, distillation, and hydrochloric acid pararosaniline colorimetry. The hydrochloric acid pararosaniline method uses a large amount of sodium tetrachloromercuric solution during the operation. The sodium tetrachloromercuric solution is harmful to the human body and will also cause great pollution to the environment. Although the distillation method has a wide range of applications, its operation process is complicated and time-consuming. Chromatography mainly includes gas chromatography, ion chromatography, liquid chromatography, etc. Although the results are accurate and simpler and faster than distillation, it relies too much on instruments and cannot be used as a rapid detection method and is put into the market for a large number of uses. Summary of the invention

[0003] The object of the present invention is to provide a method for rapidly detecting sulfur dioxide in food, which has the advantages of simple operation, rapid detection and stable and reliable results.

[0004] The purpose of the present invention is achieved through the following technical solutions:

[0005] A method for rapidly detecting sulfur dioxide in food, specifically comprising grinding or chopping a sample to be detected and adding it to a centrifuge tube, then adding water to soak for 10 minutes, then adding a sulfite rapid test reagent B, then adding a sulfite rapid test reagent C, and then adding an iodine standard solution diluted 15.5-126 times, observing a color reaction and measuring absorbance; the sulfite rapid test reagent B is a hydrochloric acid solution, and the sulfite rapid test reagent C is a starch indicator solution.

[0006] As a more optimal technical solution of the present invention, the concentration of the starch indicator is 5-25g / L

[0007] As a more optimal technical solution of the present invention, the addition ratio of the sample to be tested and water is

[0008] As a more optimal technical solution of the present invention, 0.5-2.5 ml of sulfite rapid test reagent B is added to each gram of the sample to be tested.

[0009] As a more optimal technical solution of the present invention, 0.5 ml of sulfite rapid test reagent C is added to each gram of the sample to be tested.

[0010] As a more optimal technical solution of the present invention, 1-4 ml of iodine standard solution diluted 126 times is added to each gram of the sample to be tested.

[0011] Another object of the present invention is to provide a kit for rapid detection of sulfur dioxide in food, comprising a colorimetric card, a sulfite rapid test reagent B, a sulfite rapid test reagent C and an iodine standard solution, wherein the sulfite rapid test reagent B is a hydrochloric acid solution, and the sulfite rapid test reagent C is a starch indicator solution.

[0012] Beneficial effects:

[0013] The method provided by the present invention can effectively save detection time and detection cost, has a fast analysis speed, and produces stable and reliable results. It can be applied to the rapid determination of sulfur dioxide in food and has obvious advantages in the determination of samples with substrate interference. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is the phenomenon of different dilution multiples in the iodine concentration optimization verification in Example 1;

[0015] Figure 2 This is a picture of the sample pretreatment method in Example 1;

[0016] Figure 3 is the standard curve for quantitative analysis of the detector in Example 1;

[0017] Figure 4 The diluted iodine standard solution in Example 1 is added and the number of milliliters added is recorded until the color changes;

[0018] Figure 5 is the stability test result of sulfite rapid test reagent B in Example 1;

[0019] Figure 6 is the stability test result of sulfite rapid test reagent C in Example 1;

[0020] Figure 7 The results of the stability test of the rapid test reagent color development time optimization in Example 1;

[0021] Figure 8 This is a comparison chart of the commercial rapid test reagent and the self-prepared reagent in Example 1;

[0022] Fig. 9 The example 1 is respectively a 50mg / kg limit sample of nuts, a 100mg / kg limit sample of pickled vegetables, a 200mg / kg limit sample of yuba, a 200mg / kg limit sample of day lily, a 50mg / kg limit sample of fresh fruit, a 100mg / kg limit sample of white sugar rapid test reagent colorimetric card, and a rapid test reagent colorimetric card diagram;

[0023] Fig.10 This is a diagram of the precision experiment phenomenon in Example 1. DETAILED DESCRIPTION

[0024] The present invention will be further described below in conjunction with specific embodiments, and the advantages and features of the present invention will become clearer as the description proceeds. However, these embodiments are exemplary only and do not constitute any limitation to the scope of the present invention. It should be understood by those skilled in the art that the details and forms of the present invention may be modified or replaced without departing from the spirit and scope of the present invention, but these modifications and replacements all fall within the scope of protection of the present invention.

[0025] The embodiments described below are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention. Where specific techniques or conditions are not specified in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. The reagents or instruments used are conventional products that can be obtained commercially without specifying the manufacturer. If not otherwise specified, the embodiments are all based on conventional experimental conditions.

[0026] Example 1

[0027] Calculate the concentration of iodine standard solution according to national standard limit

[0028] According to the national standard 2760-2014, this method can determine the main limits of sulfur dioxide to be 50mg / kg, 100mg / kg, and 200mg / kg. According to the reaction equation of sulfur dioxide and iodine, I2+SO2+2H2O=2HI+H2SO4, the standard sulfite solution A corresponding to 0.2mg is 0.320ml. Because the national standard limit is multiple, it can be theoretically concluded that the standard sulfite solution A corresponding to 0.05mg sulfur dioxide is 0.080ml, and the standard sulfite solution A corresponding to 0.1mg sulfur dioxide is 0.160m.

[0029] According to the equation, the dilution factor of 0.1 mol / ml iodine standard solution is 126 times.

[0030] Iodine concentration optimization verification

[0031] 1) After diluting 0.1mol / ml iodine standard solution 126 times, extract 0.080ml, 0.160ml, 0.240ml, 0.320ml, 0.640ml of sulfite standard solution A respectively, add 1.020ml, 0.940ml, 0.860ml, 0.780ml, 0.560ml of pure water, add two drops of sulfite rapid test reagent B (about 0.5ml), two drops of sulfite rapid test reagent C (about 0.5ml), add the diluted iodine standard solution to observe the reaction phenomenon.

[0032] 2) Add 0.080ml, 0.160ml, 0.240ml, 0.320ml, 0.640ml of sulfite standard solution A to 1.020ml, 0.940ml, 0.860ml, 0.780ml, 0.560ml of pure water, add two drops of sulfite rapid test reagent B (about 0.5ml), two drops of sulfite rapid test reagent C (about 0.5ml), and determine the dilution multiple according to the sulfur dioxide concentration, which are 126 times, 63 times, 42 times, 31 times, and 15.5 times respectively. After dilution, add 1ml respectively. Observe the reaction phenomenon.

[0033] Optimal concentration of iodine standard solution

[0034] Stability analysis of sulfite rapid test reagent B

[0035] Use a pipette to extract 3.40ml of sulfite standard solution A, add 7.60ml of pure water, add 0.5ml, 1ml, 1.5ml, 2ml, 2.5ml of hydrochloric acid, two drops of starch indicator solution (0.5mL) in a 20mL centrifuge tube, shake well, add 4mL of iodine standard solution diluted 126 times, let stand for 5 minutes, observe the color development and measure the absorbance, repeat three times. The absorbance is used as background interference, and the color development is mainly observed.

[0036] Stability analysis of sulfite rapid test reagent C

[0037] Use a pipette to extract 3.40ml of sulfite standard solution A, add 7.60ml of pure water to a 20mL centrifuge tube, add 1ml of hydrochloric acid, and add 1mL of starch indicator solution in sequence. The concentrations of starch indicator are 5g / L, 10g / L, 15g / L, 20g / L, and 25g / L in sequence. Then add 4mL of iodine standard solution diluted 126 times. After 5 minutes, observe the color development and measure the absorbance. Repeat three times. The absorbance is used as background interference, and the color development is mainly observed.

[0038] Analysis of color development time stability

[0039] Use a pipette to extract 3.40ml of sulfite standard solution A, add 7.60ml of pure water to a 20ml centrifuge tube, add 1ml of hydrochloric acid, add 1ml of starch indicator solution (10g / L), and then add 4ml of iodine standard solution diluted 126 times. After 5 minutes, observe the color development and measure the absorbance. Repeat three times. The absorbance is used as background interference, and the color development is mainly observed.

[0040] Sample preparation

[0041] 1) Accurately weigh 1.000g of daylily sample, cut it into pieces and put it into the sample cup, then add 10ml of sodium hydroxide rapid test reagent and soak for ten minutes, label it as group 1;

[0042] 2) Accurately weigh 1.000g of daylily sample, cut it into pieces, add 10ml of pure water into the sample cup and soak for ten minutes, labeling it as the second group;

[0043] 3) Accurately weigh 1.000g of daylily sample, cut it into pieces, add 10ml of 60℃ pure water into the sample cup and soak for ten minutes, labeling it as the third group;

[0044] 4) Add 10 ml of pure water into the sample cup, and group 4 is used as the blank control group.

[0045] Reagent test comparison

[0046] Self-prepared reagent detection

[0047] 1) Use a pipette to accurately extract 1 ml of the first, second, third and fourth group solutions, add two drops of sulfite rapid test reagent B (about 0.5 ml), two drops of sulfite rapid test reagent C (about 0.5 ml), and add 1 ml of diluted iodine standard solution to observe the reaction phenomenon.

[0048] 2) Detection with commercially available rapid test kits

[0049] Use a pipette to accurately extract 1 ml of the first, second, third and fourth group of solutions respectively, add two drops of reagent A and one drop of reagent B in the rapid test kit, and observe the reaction phenomenon.

[0050] 3) Results comparison

[0051] Compare the test results of the self-prepared reagent with the results of the rapid test kit on the market through colorimetric card comparison.

[0052] Positive spiked samples

[0053] Sample name National standard limit (mg / Kg) White sugar 100 Daylily (dried) 200 Pickled bamboo shoots 100 Fresh Fruit 50 Melon seeds 50 Bean curd sticks 200

[0054] Since it is impossible to obtain positive samples directly, all samples used are prepared in the laboratory. Since it is impossible to specifically measure the specific content of sulfur dioxide in the samples, positive samples are made by adding sodium sulfite. After preparation, the samples contain more than 0.25 mg of sodium sulfite.

[0055] 1) Weigh 1.000g of spiked melon seed kernel sample, grind it in a mortar and transfer it to a sample cup, add 10ml of pure water, soak for ten minutes, extract 1ml of extract into a 10ml centrifuge tube, add two drops of sulfite rapid test reagent B (about 0.5ml), two drops of sulfite rapid test reagent C (about 0.5ml), add 1ml of diluted iodine standard solution, and observe the experimental phenomenon

[11] .

[0056] Weigh 1.000g of unspiked melon seeds, grind them in a mortar and transfer them to a sample cup, add 10ml of pure water, soak for ten minutes, extract 1ml of extract in a 10ml centrifuge tube, add two drops of reagent A and one drop of reagent B of the rapid test kit, and observe the reaction phenomenon. Compare the rapid test kits and self-prepared reagents on the market with spiked and unspiked samples for mutual verification.

[0057] 2) Weigh 1.000g of the spiked pickled vegetable sample, cut it into pieces and transfer it to a sample cup. Add 10ml of pure water and soak it for ten minutes. Draw 1ml of the extract into a 10ml centrifuge tube, add two drops of sulfite rapid test reagent B (about 0.5ml), two drops of sulfite rapid test reagent C (about 0.5ml), add 2ml of the diluted iodine standard solution, and observe the experimental phenomenon.

[0058] Weigh 1.000g of the unspiked pickled vegetable sample, cut it into pieces and transfer it to a sample cup. Add 10ml of pure water and soak for ten minutes. Draw 1ml of the extract into a 10ml centrifuge tube and add two drops of reagent A and one drop of reagent B of the rapid test kit to observe the reaction phenomenon. Compare the rapid test kits and self-prepared reagents on the market with spiked and unspiked samples for mutual verification.

[0059] 3) Weigh 1.000g of the spiked yuba sample, cut it into pieces and transfer it to a sample cup, add 10ml of pure water, soak it for ten minutes, extract 1ml of the extract into a 10ml centrifuge tube, add two drops of sulfite rapid test reagent B (about 0.5ml), two drops of sulfite rapid test reagent C (about 0.5ml), add 4ml of the diluted iodine standard solution, and observe the experimental phenomenon.

[0060] Weigh 1.000g of unspiked yuba sample, cut it into pieces and transfer it to a sample cup, add 10ml of pure water, soak for ten minutes, extract 1ml of extract and add two drops of reagent A and one drop of reagent B in a 10ml centrifuge tube, and observe the reaction phenomenon. Compare the rapid test kits and self-prepared reagents on the market with spiked and unspiked samples for mutual verification.

[0061] 4) Weigh 1.000g of the spiked daylily sample, cut it into pieces and transfer it to a sample cup. Add 10ml of pure water and soak it for ten minutes. Draw 1ml of the extract into a 10ml centrifuge tube, add two drops of sulfite rapid test reagent B (about 0.5ml), two drops of sulfite rapid test reagent C (about 0.5ml), add 4ml of the diluted iodine standard solution, and observe the experimental phenomenon.

[0062] Weigh 1.000g of the unspiked daylily sample, cut it into pieces and transfer it to a sample cup. Add 10ml of pure water and soak it for ten minutes. Draw 1ml of the extract into a 10ml centrifuge tube and add two drops of reagent A and one drop of reagent B of the rapid test kit to observe the reaction phenomenon. Compare the rapid test kits and self-prepared reagents on the market with spiked and unspiked samples for mutual verification.

[0063] 5) Weigh 1.000g of the spiked fresh fruit sample, cut it into pieces and transfer it to a sample cup. Add 10ml of pure water and soak it for ten minutes. Draw 1ml of the extract into a 10ml centrifuge tube, add two drops of sulfite rapid test reagent B (about 0.5ml), two drops of sulfite rapid test reagent C (about 0.5ml), add 1ml of the diluted iodine standard solution, and observe the experimental phenomenon.

[0064] Weigh 1.000g of unspiked fresh fruit sample, cut it into pieces and transfer it to a sample cup. Add 10ml of pure water and soak for ten minutes. Draw 1ml of extract into a 10ml centrifuge tube and add two drops of reagent A and one drop of reagent B of the rapid test kit to observe the reaction phenomenon. Compare the rapid test kits and self-prepared reagents on the market with spiked and unspiked samples for mutual verification.

[0065] 6) Weigh 1.000g of the spiked sugar sample and transfer it directly into a sample cup. Add 10ml of pure water and soak for ten minutes to dissolve completely. Draw 1ml of the extract into a 10ml centrifuge tube, add two drops of sulfite rapid test reagent B (about 0.5ml), two drops of sulfite rapid test reagent C (about 0.5ml), add 2ml of the diluted iodine standard solution, and observe the experimental phenomenon.

[0066] Weigh 1.000g of unspiked sugar sample, cut it into pieces and transfer it to a sample cup. Add 10ml of pure water and soak for ten minutes to dissolve completely. Draw 1ml of extract into a 10ml centrifuge tube, add two drops of reagent A and one drop of reagent B of the rapid test kit, and observe the reaction phenomenon. Compare the rapid test kits and self-prepared reagents on the market with spiked and unspiked samples for mutual verification.

[0067] According to the national standard limit, select 50mg / kg, 100mg / kg, 150mg / kg, 200mg / kg, and select the limit ±10mg / kg, that is, the limit is 40mg / kg, 50mg / kg, 60mg / kg, 90mg / kg, 100mg / kg, 110mg / kg, 140mg / kg, 150mg / kg, 160mg / kg, 190mg / kg, 200mg / kg , 210mg / kg, weigh the corresponding sodium sulfite standard solution, that is, respectively measure 0.070ml, 0.080ml, 0.090ml, 0.150ml, 0.160ml, 0.170ml, 0.230ml, 0.240ml, 0.250ml, 0.310ml, 0.320ml, 0.330ml sulfite standard solution A in a 10ml centrifuge tube and add 1.030ml, 1.020ml 1.010ml 0.950ml, 0.940ml, 0.930ml, 0.870ml, 0.860ml, 0.850ml, 0.790ml, 0.780ml, 0.760ml, 0.570ml, 0.560ml, 0.550ml pure water, then add two drops of sulfite rapid test reagent B (about 0.5ml), two drops of sulfite rapid test reagent C (about 0.5ml). After diluting the 0.1mol / ml iodine standard solution 126 times, add 1ml, 2ml, 3ml, 4ml of the diluted iodine standard solution in turn according to the limit value and observe the color reaction. Record the experimental phenomenon.

[0068] According to the reaction counter-common sense and the test results, a standard curve was established after quantitative analysis by a rapid detector. The results are shown in Figure 1 , the linear regression equation is y = 0.0203x + 0.06575, R 2 =0.9995. This proves the correctness of this experiment.

[0069] It can be observed that all five groups are colorless solutions. The measurement data are analyzed by anova, and the sig is 0.442, which is greater than 0.005. The measured absorbance is used as background interference. It can be seen that the absorbance difference of the five groups is very small and there is no significant difference in absorbance, which proves that the addition amount of sulfite rapid test reagent B has no effect on the judgment of the experimental results. The amount of hydrochloric acid solution added does not affect the color development of the experimental results. As the main rapid test reagent of the rapid test kit, the rapid test kit is aimed at the mass market. The target group is non-professional people, who may lack professional chemical literacy, so there may be excessive or insufficient addition. This experiment verifies that even if the addition is wrong, it will not affect the appearance of the experimental results, which is conducive to the stability of the experiment and is also conducive to the market as a rapid test product.

[0070] From the experimental phenomena, we know that the solution reaction phenomena are all colorless. Through three parallel tests with five groups of starch concentrations, the absorbance can be obtained. The sig is 0.004 using three parallel absorbance plots, which is a significant correlation. After analysis, it is found that the absorbance is correlated with the starch solution concentration. The absorbance will increase with the increase of starch concentration. This is a normal phenomenon and can be regarded as background interference. This phenomenon proves that the concentration of starch solution does not affect the test results of the reagent. Just like the sulfite rapid test reagent B, there will be no irregular dripping that affects the test results, which is helpful for the stability of the experiment and is also conducive to the market launch of rapid test products.

[0071] Select sulfur dioxide content of 0.320mg, pure water 0.780ml and 0.5ml starch indicator, 0.5ml hydrochloric acid solution to make five parallel groups, reaction time is 1min, 3min, 5min, 7min, 9min. The results are shown in Table 7. sig greater than 0.005 proves that there is no significant relationship between the colorimetric result and time, and proves that the colorimetric result is not affected by time. As long as the result is interpreted within ten minutes, there will be no error, so the effective test time of this reagent is nine minutes. If the result is interpreted within nine minutes, there will be no error in the result due to time.

[0072] After four groups of comparisons, according to the color development results, it can be known that the self-prepared reagents are all colorless, and the colors of the rapid test reagents in the market are more obvious in treatment methods one and two. Therefore, treatment methods one and two are more efficient in extracting sulfur dioxide from samples, and the extraction efficiency of the rapid test reagent one in the market is the highest, but based on the requirements of rapid testing, it is necessary to meet the requirements of quickness and simplicity, because treatment method two meets the requirements better, and the purpose of this experiment is to detect whether the sulfur dioxide content in food exceeds the limit. The national standard limit of daylily (dry) is 200mg / kg, that is, 1g of daylily corresponds to 4ml of iodine standard solution diluted 126 times. Therefore, the experiment proves that both treatment methods one and two can detect that daylily exceeds the national standard limit. Based on the requirements of rapid testing, the best treatment method is number two, which is simple, fast, and low cost.

[0073]

[0074] 1) According to the color development, the first group of samples has a limit of 50 mg / kg of nut kernels

[16] . From the self-prepared reagent, both the spiked sample and the normal sample exceeded the limit. The spiked sample was tested and the self-prepared test showed that it exceeded the limit. The rapid test reagent test showed that the limit was between 100 mg / kg and 200 mg / kg after comparison with the colorimetric card, which reflects the correctness of the self-prepared reagent test results. The self-prepared reagent test for this sample was accurate.

[0075] 2) According to the color development, the second group of samples has a limit of 100 mg / kg of pickled vegetables. From the self-prepared reagent, the spiked sample exceeds the limit, while the normal sample does not exceed the limit. The spiked sample is detected by the self-prepared test and the actual detection is beyond the limit. The rapid test reagent is detected by the colorimetric card and the limit is close to 200 mg / kg, which reflects the correctness of the self-prepared reagent test results. The self-prepared reagent test of this sample is accurate.

[0076] 3) According to the color development, the limit of the third group of samples is 200mg / kg of yuba. From the self-prepared reagent, the spiked sample exceeds the limit, and the normal sample does not exceed the limit. The spiked sample is detected by self-prepared test and it is found to exceed the limit. The rapid test reagent is tested by colorimetric card and the limit is between 100mg / kg and 200mg / kg, which reflects the correctness of the self-prepared reagent test results. The self-prepared reagent test of this sample is accurate.

[0077] 4) According to the color development, the limit of the fourth group of samples is 200mg / kg of dried daylily. From the self-prepared reagent, the spiked sample exceeds the limit, while the normal sample does not exceed the limit. The spiked sample is tested and the actual self-prepared test shows that it exceeds the limit. The rapid test reagent test shows that the limit is between 100mg / kg and 200mg / kg through the colorimetric card comparison, which reflects the correctness of the self-prepared reagent test results. The self-prepared reagent test of this sample is accurate.

[0078] 5) According to the color development, the limit of the fifth group of samples is 50mg / kg for fresh fruit. From the self-prepared reagent, the spiked samples exceed the limit, while the normal samples do not exceed the limit. The spiked samples are tested and the actual self-prepared test shows that they exceed the limit. The rapid test reagent test shows that the limit is between 100mg / kg and 200mg / kg after comparison with the colorimetric card, which reflects the correctness of the self-prepared reagent test results. The self-prepared reagent test for this sample is accurate.

[0079] 6) According to the color development, the limit of the fifth group of samples is 100 mg / kg of white sugar. From the self-prepared reagent, the spiked sample exceeds the limit, and the normal sample does not exceed the limit. The spiked sample is tested, and the actual self-prepared test shows that it exceeds the limit. The rapid test reagent test shows that the limit is between 100 mg / kg and 200 mg / kg through the colorimetric card comparison, which reflects the correctness of the self-prepared reagent test results. The self-prepared reagent test of this sample is accurate.

[0080] From the perspective of the six samples, by corresponding to the rapid test kits and spiked samples on the market, the self-prepared reagents can detect whether the samples exceed the limit, which proves the practicality and accuracy of this experiment. The national standard limit of ±0.010mg is used to measure whether the reagent can achieve precise quantification. Through the experiment, it can be observed that the centrifuge tubes with limits of 40mg / kg, 50mg / kg, and 60mg / kg are added with two drops of sulfite rapid test reagent B (about 0.5ml), two drops of sulfite rapid test reagent C (about 0.5ml), and then 1ml of diluted iodine standard solution are added to the color blue, colorless, and colorless. The centrifuge tubes with limits of 90mg / kg, 100mg / kg, and 110mg / kg are added with two drops of sulfite rapid test reagent B (about 0.5ml), two drops of sulfite rapid test reagent C (about 0.5ml), and then 2ml of diluted iodine standard solution are added to the color blue, light blue, and colorless. Add two drops of sulfite rapid test reagent B (about 0.5ml) and two drops of sulfite rapid test reagent C (about 0.5ml) to the centrifuge tubes with limit values ​​of 140mg / kg, 150mg / kg, and 160mg / kg, and then add 31ml of diluted iodine standard solution to develop blue, light blue, and colorless. However, the light blue color of the limit value of 150mg / kg is a little darker than the light blue color of the limit value of 100mg / kg. Add two drops of sulfite rapid test reagent B (about 0.5ml) and two drops of sulfite rapid test reagent C (about 0.5ml) to the centrifuge tubes with limit values ​​of 190mg / kg, 200mg / kg, and 210mg / kg, and then add 4ml of diluted iodine standard solution to develop blue, light blue, and colorless. However, the light blue color of the limit value of 200mg / kg is a little darker than the light blue color of the limit value of 150mg / kg. The experimental hypothesis is that the residual iodine standard solution that does not exceed the limit will react with the starch solution to show blue, and after exceeding the limit, the iodine standard solution reacts completely with sulfur dioxide, and the iodine standard solution without residue reacts with the starch solution to cause the solution to show colorless. The reason why only the first group of limit values ​​50mg / kg is colorless, and the other three groups of limit values ​​100mg / kg, 150mg / kg, and 200mg / kg are light blue between colorless and blue is that the multiples of the diluted iodine standard solution are specifically for 50mg / kg. Since it is added dropwise according to the limit multiples, it is theoretically possible, but the reagent addition process cannot be accurately controlled due to the error between the configured iodine standard solution reagent and the theoretical iodine standard solution. However, this experiment has proved that the detection limit of this method is 0.01mg / g, and it can also be proved that this reagent can detect the limit of ±10mg / kg. According to most of the limit values ​​of Chinese food in the national standard 50009.34, it only needs to meet this detection standard. Proved the precision of this experiment.

[0081]

[0082]

[0083] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A method for rapidly detecting sulfur dioxide in food, characterized in that: Specifically, the sample to be tested is ground or chopped and added to a centrifuge tube, then soaked in water for 10 minutes, then added with sulfite rapid test reagent B, then added with sulfite rapid test reagent C, and then added with iodine standard solution diluted 15.5-126 times, the color reaction is observed and the absorbance is measured; the sulfite rapid test reagent B is a hydrochloric acid solution, and the sulfite rapid test reagent C is a starch indicator solution.

2. The method for rapid detection of sulfur dioxide in food according to claim 1, characterized in that: The concentration of the starch indicator is 5-25 g / L.

3. The method for rapid detection of sulfur dioxide in food according to claim 1, characterized in that: Add 0.5-2.5 ml of sulfite rapid test reagent B to each gram of sample to be tested.

4. The method for rapid detection of sulfur dioxide in food according to claim 1, characterized in that: Add 0.5 ml of sulfite rapid test reagent C to each gram of sample to be tested.

5. The method for rapid detection of sulfur dioxide in food according to claim 1, characterized in that: Add 1-4 ml of iodine standard solution diluted 126 times to each gram of sample to be tested.

6. A kit for rapid detection of sulfur dioxide in food, comprising a colorimetric card, a sulfite rapid test reagent B, a sulfite rapid test reagent C and an iodine standard solution, wherein the sulfite rapid test reagent B is a hydrochloric acid solution, and the sulfite rapid test reagent C is a starch indicator solution.

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