CN112964685B - Detection kit and detection method for content of aluminum additive in food - Google Patents
Detection kit and detection method for content of aluminum additive in food Download PDFInfo
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- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
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Abstract
The invention discloses a kit for detecting the content of an aluminum additive in food, which comprises: an aluminum additive extracting reagent, a pH regulator, a fluorescence generating agent and an ultraviolet generator. The kit also comprises an observation cassette and a standard colorimetric card. Preferably, the kit further comprises one or a combination of more than two of a graduated tube, a pipette, a cuvette and scissors. Preferably, the aluminum additive extraction reagent is a sodium hydroxide solution with the concentration of 2g/L, the pH regulator is glacial acetic acid, the fluorescence generator is a morin ethanol solution with the concentration of 2g/L, and the ultraviolet generator is a device capable of generating ultraviolet light with the wavelength of 420-440 nm. The detection kit provided by the invention has the advantages of convenient and easily obtained reagents, simple and convenient operation, capability of carrying out rapid qualitative or semi-quantitative detection on the residual quantity of the aluminum additive in food, and suitability for field law enforcement and screening of primary inspectors.
Description
Technical Field
The invention belongs to the technical field of food detection, and particularly relates to a kit for detecting the content of an aluminum additive in food and a detection method thereof.
Background
The aluminum additives (alum, ammonium alum and potassium alum) have a long use history in China, and the written records can be traced back to the north-south orientation period of Wei and jin at the earliest. The aluminum additives such as alum and the like can make food fluffy, good in taste, tough, and capable of retaining water and moisture, and are widely used in fried flour products, starch products, fermented flour products and aquatic products. However, with the continuous improvement of the living quality level of people, the attention on food safety is more clear, and the harm of aluminum element is gradually paid attention to the masses.
Aluminum is a low-toxicity and non-essential metal element for human body, and as early as 1989, the world health organization determined and managed aluminum as a food pollutant. The long-term accumulation of aluminum in human body can interfere the thinking and memory of human body, accelerate the aging of human body cells, cause mental retardation and anemia, and even lead to serious consequences such as osteoporosis, senile dementia and the like. At present, although commercial products such as aluminum-free deep-fried dough sticks and aluminum-free baking powder are proposed by merchants, aluminum-containing foods still widely exist due to benefit driving, thinking concept solidification and the like.
Although the limit of the residual amount of aluminum in each food is strictly specified in the standard of GB 2760-. The method has the characteristics of wide region range, high unqualified rate, large exceeding amount and high maximum reaching about 10 times of the limit value. 2016, the special inspection of the standard execution condition of the aluminum-containing food additive is carried out in Sichuan province; in 2018, the State general administration of market supervision develops the special treatment work of vermicelli, noodles and flour products; in 2019, aiming at the problem of excessive aluminum content, a special organization in Shanghai City develops special treatment work of vermicelli and noodle products; in 2020, the Qinghai province carries out special treatment work of flour products; the other special treatment works at the city and county level are countless. The concern of the nation and the concern of the masses, the serious problems, the wide coverage and the obvious spots.
At present, the laboratory detection of the aluminum residue adopts a spectrophotometry method in GB 5009.182-2017, the detection period is long, the pollution is large, the equipment requirement is high, more reagents are added, and the steps are complicated. Although the aluminum content in the sample to be detected can be accurately measured, technical support cannot be provided at the first site of law enforcement and screening, and the method cannot be directly put into security and special law enforcement, particularly in areas with deficient laboratory resources, such as counties, towns and the like. At present, the rapid detection technology in China is developed rapidly, but a rapid detection method or a kit for an aluminum-containing additive in food is still reported, and a chemical colorimetric method is still mainly used at present and is insufficientThe method mainly comprises the following steps: the method is simplified based on the national standard, namely, the chromium azure S color development method, although the method has strong specificity, the added reagents have various types and are fussy to operate, are not easy to master by primary law enforcement personnel, are not easy to store, have high toxicity and are not suitable for field law enforcement and rapid screening; ② a rose-red developing method based on tricarboxyauric acid ammonium salt (aromine), which is easy to be subjected to Cr although the operation is simple3+、Fe3+、Cu2+、Ca2+And interference of various ions is easy to cause false positive, the specificity is not strong, and an aluminum-containing substance (aluminum chloride) is required to be added in the process, so that the method can only be qualitative and cannot be preliminarily quantitative.
Patent document 201611132477.0 discloses a kit for detecting the content of aluminum in food, which comprises a box body, a box cover, a gasket which can be placed in the box body; the pad is provided with a small hole, and a reagent tube filled with nitric acid, a reagent tube filled with hydrogen peroxide, a reagent tube filled with pure water, a reagent tube filled with acetic acid-sodium acetate buffer solution, a reagent tube filled with aluminum standard solution and a reagent tube filled with chromium azure S solution are arranged in the small hole. The essence of the kit is also a chromium azure S color development method, the required reagents are various, and the disadvantages of complicated operation steps are still not improved.
In order to solve the defects of the prior art, the invention provides the kit for detecting the content of the aluminum additive in the food, the reagents in the kit are convenient and easy to obtain, the operation is simple and convenient, the qualitative or semi-quantitative detection can be rapidly carried out on the residual quantity of the aluminum additive in the food, and the kit is very suitable for primary inspectors to carry out on-site law enforcement and screening.
Disclosure of Invention
The invention aims to provide a detection kit which is simple to operate, strong in specificity, rapid, simple and capable of preliminary quantification, aiming at the current situation that aluminum additives in foods such as fried flour products, fermented flour products, starch products, puffed foods and baked foods in the market exceed the standard and accurate, rapid, convenient and semi-quantitative screening cannot be carried out in the first time. Another object of the present invention is to provide a detection method for the kit.
The purpose of the invention is realized by the following technical scheme.
In a first aspect, the present invention provides a kit for detecting the content of an aluminum additive in food, wherein the kit comprises: an aluminum additive extracting reagent, a pH regulator, a fluorescence generating agent and an ultraviolet generator.
Preferably, the kit further comprises an observation cassette, the observation cassette is of a box structure, a cuvette groove is formed in the box, and two adjacent side faces of the box are respectively provided with an irradiation hole and an observation hole.
Preferably, the kit further comprises a standard color comparison card or a modified standard color comparison card.
More preferably, for convenient application, the kit further comprises one or a combination of more than two of a graduated tube, a pipette, a cuvette and scissors.
The aluminum additive extracting reagent is sodium hydroxide with the mass concentration of 2-4g/L, and in the most preferred embodiment of the invention, the aluminum additive extracting reagent is 2g/L sodium hydroxide solution.
The pH regulator is selected from glacial acetic acid.
The fluorescence generating agent is morin ethanol solution with the concentration selected from 2-5g/L, and in the most preferred embodiment of the invention, the morin ethanol solution with the concentration of 2 g/L.
The ultraviolet generator is a device capable of generating ultraviolet light with the wavelength of 420-440nm, and in a preferred embodiment of the invention, the ultraviolet generator is a flashlight capable of emitting ultraviolet light with the wavelength of 430 nm.
In a second aspect, the invention provides a method for detecting the content of an aluminum additive in food, which comprises the following steps:
(1) cutting a sample to be detected, weighing m g, placing in a graduated tube, adding an aluminum additive extraction reagent, shaking, uniformly mixing, standing, and taking supernatant to obtain a sample extracting solution V mL;
(2) adding a sample extract v mL serving as a determination solution into a cuvette, adding a pH regulator to enable the pH value to be 3.0-3.5, shaking up, adding a fluorescence generating agent, placing the cuvette in an observation cassette, irradiating the cuvette by using an ultraviolet generator, and observing the fluorescence color and intensity;
(3) comparing with a standard colorimetric card, and estimating and reading the concentration of aluminum in the determination solution to be c mu g/mL;
(4) calculating in a sample to be tested
Wherein, omega represents the recommended coefficient of sample moisture, and the calculation formula is as follows:
a represents the water content of the sample in percent.
The content value of the aluminum additive in the sample to be detected obtained by calculation in the application represents the content value of the aluminum additive in the dry sample, because the technical personnel in the field use GB 2760-. In the actual spot check and rapid detection, a lot of time is consumed for drying the sample and then detecting the sample, and the detection cannot be realized basically, so that technicians creatively multiply the moisture recommendation coefficient of the sample on the basis of the value obtained by the actual detection to obtain the content value of the aluminum additive in the corresponding dry sample.
The technicians of the invention can contact a large number of food samples to be detected in actual work, and the technicians find that after a plurality of samples are collected for the same food unexpectedly, the moisture recommendation coefficients calculated by the sample moisture recommendation coefficient calculation formula have no significant difference, such as the following conditions: randomly inspecting four batches of potato powder (wet) produced by four manufacturers, drying by using a first direct drying method of GB 5009.3-2016 to obtain the water content of a sample, and calculating the recommended water content coefficient by using the formula, wherein the recommended water content coefficient is shown in the following table:
TABLE 1 recommended moisture coefficient calculation procedure for potato flour (Wet)
The recommended moisture coefficient of the potato flour (wet) produced by four batches of four manufacturers shown in the table is between 1.6 and 1.8, and after actually expanding the detection sample, the recommended moisture coefficient of the potato flour (wet) obtained by detection is still between 1.6 and 1.8, and the recommended moisture coefficient of the potato flour (wet) is 1.7 by taking an intermediate value. According to the example shown above, the technician detects and calculates the moisture recommendation coefficients of common food samples on the market, and finally obtains the following table of moisture recommendation coefficients of common food samples, which is convenient for use in daily work.
Table 2 part moisture recommended coefficient table for common food sample
| Name (R) | Water content (%) | Coefficient of recommendation |
| Steamed bread | 40 | 1.7 |
| Steamed stuffed bun (trap removal) | 40 | 1.7 |
| Steamed twisted roll | 40 | 1.7 |
| |
25 | 1.3 |
| Dried potato powder (Wet) | 40 | 1.7 |
| Bread | 30 | 1.4 |
| Cake | 20 | 1.2 |
| Biscuit | 30 | 1.4 |
| Vermicelli (dried) | 10 | 1.1 |
| Bean curd jelly | 90 | 10 |
The standard colorimetric card is prepared by the following method:
(1) taking 5 25mL graduated plastic tubes, and respectively preparing aluminum standard solutions with the volume of 20mL and the concentrations of 0, 1.25, 2.5, 5.0 and 10.0 mu g/mL;
(2) taking 2.0mL of the aluminum standard solution prepared in the step (1) by using a disposable pipette, adding four drops of glacial acetic acid dropwise into a quartz cuvette, shaking uniformly, adding two drops of 2g/L morin ethanol solution, placing the cuvette in an observation cassette, irradiating the quartz cuvette by using a 420-plus 440nm ultraviolet flashlight, and drawing a standard colorimetric card by using fluorescence colors and intensities corresponding to different aluminum concentrations, wherein the specific figure is shown in FIG. 2.
The concentration gradient range of the aluminum standard solution in the step (1) can be increased by the skilled person according to the needs, and the concentration range of the aluminum standard solution is preferably 0-10.0 mug/mL in the invention, because, firstly, the aluminum concentration range of 0-10.0 mug/mL is a range with better identification degree of the fluorescence color and intensity by naked eyes; secondly, the linearity of the aluminum concentration with the fluorescence intensity is relatively good in the range of 0-10.0. mu.g/mL.
In a most preferred embodiment of the present invention, the detection method is:
(1) shearing a sample to be detected, weighing 1.0g of the sample, placing the sample in a graduated plastic tube, adding 2g/L of sodium hydroxide solution, shaking, soaking for 10 minutes, shaking vigorously for several times during the process, standing, and taking supernate as a sample extracting solution V mL;
(2) sampling 2.0mL of sample extracting solution into a quartz cuvette by using a disposable pipette, dripping four drops of glacial acetic acid into the quartz cuvette, shaking uniformly, adding two drops of 2g/L morin ethanol solution into the cuvette, placing the cuvette into an observation cassette, irradiating the quartz cuvette by using an ultraviolet flashlight with the wavelength of 420-440nm, and observing the fluorescence color and intensity;
(3) comparing with a standard colorimetric card, and estimating and reading the concentration of aluminum in the determination solution to be c mu g/mL;
(4) and (3) calculating the content (mg/kg) of the aluminum additive in the sample to be detected as c multiplied by V multiplied by omega according to a formula.
And (4) judging a final result: and judging whether the aluminum content in the sample to be detected exceeds the standard or not according to the limit of the aluminum residue of each food in GB 2760-2014 and the aluminum content of the sample obtained by detection.
Preferably, for practical convenience, the step (1) is performed in a 25mL graduated plastic tube, V is 20mL, and the final aluminum additive content (mg/kg) ═ c × 20 × ω, which can be adapted to most food sample tests. Since c in the standard colorimetric card is 0-10 μ g/mL, when the content of the aluminum additive in the food sample is greater than 200mg/kg, such as 900mg/kg, the aluminum concentration in the extract obtained by extracting 1g of the aluminum in the sample with 20mL of sodium hydroxide solution is obviously too high to be compared with the colorimetric card, at this time, 20mL of the sample extract obtained in step (1) can be diluted by X times, or the sample mass in step (1) is reduced to 1/X and then prepared into 20mL of the sample extract, and steps 2-4 are not changed, so that the final aluminum additive content (mg/kg) is c × 20 × X × ω.
In order to reduce the calculation steps of the inspector in the actual work, the invention improves the standard colorimetric card, and draws the improved standard colorimetric card by using the fluorescence color and intensity corresponding to the aluminum content in 20mL of sample extracting solution, specifically as shown in fig. 3, so that the final aluminum additive content (mg/kg) is the colorimetric card reading × ω or the colorimetric card reading × X × ω.
The 20mL sample extract in the "drawing the fluorescence color and intensity corresponding to the aluminum content in the 20mL sample extract solution" includes two cases: if the sample extracting solution does not need to be diluted, 20mL of the sample extracting solution is a solution obtained by extracting 2g/L of sodium hydroxide solution in the conventional sense; when the sample extract is diluted X-fold, 20mL of the sample extract means 20mL of the diluted solution.
The working principle of the kit for detecting the content of the aluminum additive in the food provided by the invention is as follows: the aluminium additive in the food is extracted by sodium hydroxide solution, and the pH value is adjusted by glacial acetic acid, so that the stability of the system is high, and the fluorescence intensity of a compound generated by the reaction of aluminium in the system and morin is strongest. The fluorescence intensity of the compound generated by the reaction of the aluminum and the morin is in direct proportion to the aluminum content, so the aluminum content in the sample to be detected can be judged according to the fluorescence intensity.
In the prior art, the detection of the aluminum content in food adopts a chromium azure S spectrophotometry in GB 5009.182-2017. The principle of the spectrophotometry is as follows: after a sample to be detected is processed, in ethylenediamine-hydrochloric acid buffer solution (pH 6.7-7.0) and in the presence of polyethylene glycol octylphenyl ether and bromohexadecyl pyridine (CPB), trivalent aluminum ions and chromium azure S react to generate blue-green quaternary micelles, and the absorbance value is measured at the wavelength of 620nm and is compared and quantified with a standard series.
Compared with the prior art, the kit for detecting the content of the aluminum additive in the food has the following advantages:
the detection speed is high, the kit can be used for quickly carrying out qualitative or semi-quantitative detection on the residual quantity of the aluminum additive in the food, the result is obtained within 20 minutes, the types of required reagents are few, and the detection can be completed by the national standard chromium azure S spectrophotometry within at least 2 days.
Secondly, the accuracy is good, the negative sample has no fluorescence characteristic, and the error range of the quick detection result of the positive sample kit and the detection result of the standard chromium azure S spectrophotometry can be controlled to be +/-20%.
③ high specificity, and the skilled person can be used for common anions and cations which are possibly existed in a large amount in the food, including but not limited to Na+、Cl-、Fe2+、Fe3+、Cu2+、NH4 +、SO4 2-、K+、Ca2+Interference tests are carried out, and the results show that the common ions have no influence on the test results of the kit.
The kit is suitable for semi-quantitative detection of the aluminum content of common foods such as deep-fried dough sticks, potato powder, vermicelli, steamed stuffed buns, steamed bread, steamed rolls, biscuits, cakes, bread, bean products and the like.
Drawings
FIG. 1 is a schematic view of the structure of an observation cassette
2420 figure 440nm wavelength ultraviolet flashlight
FIG. 3 is a photograph of a standard colorimetric card
FIG. 4 is a photograph of an improved standard colorimetric card
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
EXAMPLE 1 detection kit for aluminum additive content in food
The detection kit comprises the following reagents and tools shown in the table:
TABLE 3 detection kit composition for aluminum additive content in food
| Name of article | Unit of | Number of |
| 2g/L sodium hydroxide (500mL) | Bottle (Ref. TM. bottle) | 1 |
| Glacial acetic acid (10mL) | Bottle (Ref. TM. bottle) | 1 |
| 2g/L morin ethanol solution (10mL) | Bottle (Ref. TM. bottle) | 1 |
| 420-440nm wavelength ultraviolet flashlight | An | 1 |
| Cassette | An | 1 |
| Standard colorimetric card | Sheet of paper | 1 |
| Scissors | Handle | 1 |
| 25mL graduated plastic pipe (with cover) | An | 10 |
| Disposable suction tube | An | 50 |
| 3.0mL large straw | An | 5 |
| 10mm quartz cuvette (four sides transparent) | An | 2 |
Preparation and manufacturing method of reagent and detection tool in kit
Aluminum additive extraction reagent: weighing 2g of sodium hydroxide, adding water to a constant volume of 1L, washing 500mL of bottles, and subpackaging to prepare a sodium hydroxide solution with the concentration of 2 g/L.
pH regulator: glacial acetic acid, 10mL plastic dropping bottle.
A fluorescence generating agent: weighing 0.2g of morin, dissolving with ethanol, diluting to 100mL of constant volume, and subpackaging in 10mL plastic dropping bottles to obtain a morin ethanol solution with the concentration of 2 g/L.
420-440nm wavelength ultraviolet flashlight: the factory is customized and is provided with a charger, and the charger can be recycled.
Observation of the cassette: and customizing according to proper size and materials, and avoiding light.
Standard colorimetric card: a standard colorimetric card was prepared according to the method provided in the present specification, and the modified standard colorimetric card shown in fig. 3 was actually attached to the kit. The standard colorimetric card in the kit only needs to be prepared once before leaving a factory, is universal, and does not need to be drawn before detection.
Example 2 method for detecting content of aluminum additive in food
In the first case: when the content of the aluminum additive in the sample to be detected is less than or equal to 200mg/kg
S1: cutting a sample to be detected into small pieces, weighing 1.0g of the small pieces, placing the small pieces in a 25mL graduated plastic tube, adding 2g/L of sodium hydroxide, soaking for 10 minutes, violently shaking for several times during the soaking, standing, and taking supernate as a sample extracting solution with the volume of 20 mL;
s2: taking 2.0mL to 10mm of liquid to be detected by using a disposable straw, dripping four drops of glacial acetic acid into the quartz cuvette, shaking uniformly, adding two drops of 2g/L morin ethanol solution, placing the solution into a cuvette groove of a cassette, irradiating the quartz cuvette by using a 420-plus-440 nm ultraviolet flashlight through a radiation hole of the cassette, and observing the fluorescence color intensity through a observation hole of the cassette;
s3: if the cuvette is bluish purple, the sample to be detected does not contain aluminum, and the sample is regarded as a negative sample; and if the cuvette shows fluorescent green, the cuvette is a positive sample, the content of aluminum in the sample extracting solution is estimated and read by comparing the cuvette with the improved standard colorimetric card, and finally the content (mg/kg) of the aluminum additive in the sample to be detected is equal to the reading multiplied by omega of the colorimetric card.
In the second case: when the content of the aluminum additive in the sample to be detected is more than 200mg/kg
S1: cutting a sample to be detected into small pieces, weighing 1.0g of the small pieces, placing the small pieces in a 25mL graduated plastic tube, adding 2g/L of sodium hydroxide, soaking for 10 minutes, violently shaking for several times during the soaking, standing, taking supernate as a sample extracting solution, wherein the volume of the sample extracting solution is 20mL, and diluting the 20mL sample extracting solution by X times;
s2: taking 2.0mL to 10mm of liquid to be detected by using a disposable straw, dripping four drops of glacial acetic acid into the quartz cuvette, shaking uniformly, adding two drops of 2g/L morin ethanol solution, placing the solution into a cuvette groove of a cassette, irradiating the quartz cuvette by using a 420-plus-440 nm ultraviolet flashlight through a radiation hole of the cassette, and observing the fluorescence color intensity through a observation hole of the cassette;
s3: the cuvette presents fluorescent green, the content of aluminum in the sample extracting solution is estimated and read by comparing with the improved standard colorimetric card, and finally the content (mg/kg) of the aluminum additive in the sample to be detected is multiplied by the reading of the colorimetric card multiplied by X omega.
Comparative example chromium azure S spectrophotometry
S1: soaking the glassware used in the experiment in an acid jar for 24h overnight;
s2: uniformly crushing a sample to be detected, and drying about 30g of the crushed sample in a constant-temperature drying oven at 85 ℃ for 4 hours;
s3: weighing m g (accurate to 0.001g) pretreated sample, placing in a hard glass digestion tube or a conical flask, adding 10mL nitric acid and 0.5mL sulfuric acid, heating in an adjustable temperature-controlled electric heating furnace at 100 deg.C for 1 hr, heating to 150 deg.C for 1 hr, heating to 180 deg.C for 2 hr, heating to 200 deg.C, adding nitric acid for digestion until white smoke appears at the tube opening, taking out, cooling, transferring with water to 50mL (V) to desired volume1) And (5) placing the mixture into a bottle, and uniformly mixing the mixture for later use. And simultaneously, carrying out a reagent blank test.
S4: draw 1.00mL (V) separately2) The digestive juice and the blank solution are respectively put into a 25mL colorimetric tube with a plug, and water is added until the scale is 10 mL. Taking 7 additional 25mL colorimetric tubes with plugs, respectively adding 0mL, 0.500mL, 1.00mL, 2.00mL, 3.00mL, 4.00mL and 5.00mL of aluminum standard use solution (the mass of aluminum in the series of standard solutions is 0 mug, 0.500 mug, 1.00 mug, 2.00 mug, 3.00 mug, 4.00 mug and 5.00 mug respectively), sequentially adding 1mL of sulfuric acid solution (1%) into each tube, and adding water to 10mL scale;
dropping 1 drop of p-nitrophenol ethanol solution (1g/L) into a standard tube, a sample tube and a reagent blank tube, uniformly mixing, dropping an ammonia water solution to light yellow, dropping a nitric acid solution (2.5%) until yellow just disappears, adding 1mL more, adding 1mL ascorbic acid solution (10g/L), uniformly mixing, adding 3mL chromium azure S solution (1g/L), adding 1mL polyethylene glycol octyl phenyl ether solution (3%), 3mL LCPB solution (3g/L) and 3mL ethylenediamine-hydrochloric acid buffer solution, adding water to a constant volume of 25.0mL, uniformly mixing, and standing for 40 min.
The absorbance was measured at a wavelength of 620nm using a 1cm cuvette with reference to a blank solution. Drawing a standard curve by taking the mass of the aluminum in the standard series solution as an abscissa and the corresponding absorbance value as an ordinate, and obtaining the mass m of the aluminum in the sample digestive juice by referring to the standard curve1μ g, and mass m of aluminum in blank solution2μ g. Finally, in the sample to be tested
Specific examples of the applications
The content of the aluminum additive in the sample to be detected of the food in actual work is detected according to the detection method provided in the embodiment 2 and the chromium azure S spectrophotometry provided in the comparative embodiment, and the detection result is shown in the following table, and whether the content of the aluminum additive in the sample to be detected exceeds the standard is judged by taking GB 2760-2014 national standard for food safety food additive use as the standard.
TABLE 4 comparison of the results of the detection of aluminum additives in food
As can be seen from the results in the table above, the qualitative result obtained by using the detection method of the kit provided by the invention is completely consistent with the result obtained by the detection of the chromium azure S spectrophotometry. In addition, the detection results obtained by the two methods are compared with the limit value of the aluminum residue amount of the food in the national standard, and the judgment results of judging whether the content of the aluminum additive in the food to be detected exceeds the standard are completely consistent. The detection results obtained by the two methods show that the error range of the detection value obtained by the detection method of the kit and the error range of the aluminum content value obtained by the chromium azure S spectrophotometry can be controlled within +/-20%, and the qualitative result and the judgment result of whether the aluminum content exceeds the standard are not influenced, so that the detection method of the kit provided by the invention is suitable for qualitative and semi-quantitative detection of the aluminum content in food, and the detection time of the detection method of the kit provided by the invention is short, so that the detection method of the kit is more suitable for field law enforcement of primary inspectors.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.
Claims (5)
1. A kit for detecting the content of an aluminum additive in food, comprising: an aluminum additive extraction reagent, a pH regulator, a fluorescence generator and an ultraviolet generator; the aluminum additive extraction reagent is a sodium hydroxide solution with the mass concentration of 2-4g/L, the pH regulator is selected from glacial acetic acid, the fluorescence generator is a morin ethanol solution with the mass concentration of 2-5g/L, and the ultraviolet generator is a device capable of generating ultraviolet light with the wavelength of 420-440 nm;
the kit also comprises an observation cassette, wherein the observation cassette is of a box body structure, a cuvette groove is arranged in the box body, and two adjacent side surfaces of the box body are respectively provided with an irradiation hole and an observation hole;
the kit also comprises a standard colorimetric card or an improved standard colorimetric card;
the standard colorimetric card is prepared by the following method: (1) taking 5 25mL graduated plastic tubes, and respectively preparing aluminum standard solutions with the volume of 20mL and the concentrations of 0, 1.25, 2.5, 5.0 and 10.0 mu g/mL; (2) sucking 2.0mL of the aluminum standard solution prepared in the step (1) into a quartz cuvette by using a disposable suction tube, dripping four drops of glacial acetic acid into the quartz cuvette, shaking uniformly, adding two drops of 2g/L morin ethanol solution into the quartz cuvette, placing the cuvette into an observation cassette, irradiating the quartz cuvette by using an ultraviolet flashlight with the wavelength of 420 plus one and 440nm, and drawing according to the fluorescence colors and intensities corresponding to different aluminum concentrations to obtain a standard colorimetric card;
the preparation method of the improved standard colorimetric card is the same as that of a standard colorimetric card, and finally the improved standard colorimetric card is obtained by drawing the fluorescence color and intensity corresponding to the aluminum content in 20mL of sample extracting solution;
the kit also comprises a graduated tube, a straw, a cuvette and scissors;
the detection method for detecting the content of the aluminum additive in the food by using the kit comprises the following steps:
(1) cutting a sample to be detected, weighing m g, placing in a graduated tube, adding an aluminum additive extraction reagent, shaking, uniformly mixing, standing for 5-10 minutes, and taking supernatant to obtain a sample extracting solution V mL;
(2) adding a sample extract v mL serving as a determination solution into a cuvette, adding a pH regulator to enable the pH value to be 3.0-3.5, shaking up, adding a fluorescence generating agent, placing the cuvette in an observation cassette, irradiating the cuvette by using an ultraviolet generator, and observing the fluorescence color and intensity;
(3) comparing with a standard colorimetric card, and estimating and reading the concentration of aluminum in the determination solution to be c mu g/mL;
(4) computing
Wherein, omega represents the recommended coefficient of sample moisture, and the calculation formula is as follows:
a represents the water content of the sample in percent.
2. The kit according to claim 1, wherein the detection method is:
(1) shearing a sample to be detected, weighing 1.0g of the sample, placing the sample in a graduated plastic tube, adding 2g/L of sodium hydroxide solution, shaking, soaking for 10 minutes, shaking vigorously for several times during the process, standing, and taking supernate as a sample extracting solution V mL;
(2) sampling 2.0mL of sample extracting solution into a quartz cuvette by using a disposable pipette, dripping four drops of glacial acetic acid into the quartz cuvette, shaking uniformly, adding two drops of 2g/L morin ethanol solution into the cuvette, placing the cuvette into an observation cassette, irradiating the quartz cuvette by using an ultraviolet flashlight with the wavelength of 420-440nm, and observing the fluorescence color and intensity;
(3) comparing with a standard colorimetric card, and estimating and reading the concentration of aluminum in the determination solution to be c mu g/mL;
(4) and (3) calculating the content (mg/kg) of the aluminum additive in the sample to be detected as c multiplied by V multiplied by omega according to a formula.
3. The kit of claim 2, wherein step (1) is performed in 25mL graduated plastic tubing, V is 20mL, and the final aluminum additive content (mg/kg) is cx20 x ω.
4. The kit according to claim 3, wherein when the content of the aluminum additive in the food sample is more than 200mg/kg, the 20mL of the sample extract obtained in step (1) is diluted by X times, or the sample obtained in step (1) is reduced to 1/X before being prepared into 20mL of the sample extract, and the final content (mg/kg) of the aluminum additive is not changed in steps 2-4.
5. The kit of claim 4, wherein the aluminum additive content (mg/kg) is either a color chart reading X ω or a color chart reading X ω, when compared to a modified standard color chart.
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