CN117825304A - Method for rapidly and quantitatively determining content of aluminum element in food - Google Patents
Method for rapidly and quantitatively determining content of aluminum element in food Download PDFInfo
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- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 title claims abstract description 69
- 238000000034 method Methods 0.000 title claims abstract description 53
- 235000013305 food Nutrition 0.000 title claims abstract description 35
- 229910052782 aluminium Inorganic materials 0.000 claims abstract description 49
- 238000000120 microwave digestion Methods 0.000 claims abstract description 18
- ZPIRTVJRHUMMOI-UHFFFAOYSA-N octoxybenzene Chemical compound CCCCCCCCOC1=CC=CC=C1 ZPIRTVJRHUMMOI-UHFFFAOYSA-N 0.000 claims abstract description 17
- VEXZGXHMUGYJMC-UHFFFAOYSA-N hydrochloric acid Substances Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims abstract description 16
- 238000002835 absorbance Methods 0.000 claims abstract description 15
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 claims abstract description 14
- 239000002202 Polyethylene glycol Substances 0.000 claims abstract description 14
- -1 aluminum ions Chemical class 0.000 claims abstract description 14
- 229920001223 polyethylene glycol Polymers 0.000 claims abstract description 14
- 238000001514 detection method Methods 0.000 claims abstract description 11
- 238000002798 spectrophotometry method Methods 0.000 claims abstract description 9
- 239000000693 micelle Substances 0.000 claims abstract description 8
- 239000007853 buffer solution Substances 0.000 claims abstract description 7
- 239000000243 solution Substances 0.000 claims description 51
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 33
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims description 26
- 229910017604 nitric acid Inorganic materials 0.000 claims description 26
- 230000029087 digestion Effects 0.000 claims description 24
- 238000002156 mixing Methods 0.000 claims description 18
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 claims description 16
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 16
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 13
- 238000005259 measurement Methods 0.000 claims description 13
- 239000003153 chemical reaction reagent Substances 0.000 claims description 11
- 239000011259 mixed solution Substances 0.000 claims description 11
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 claims description 10
- 235000011114 ammonium hydroxide Nutrition 0.000 claims description 10
- 238000012360 testing method Methods 0.000 claims description 10
- RCKIJBHIJDHARI-UHFFFAOYSA-N 3-bromo-2-hexadecylpyridine Chemical compound CCCCCCCCCCCCCCCCC1=NC=CC=C1Br RCKIJBHIJDHARI-UHFFFAOYSA-N 0.000 claims description 9
- YPXDSSGRBXVFNZ-UHFFFAOYSA-N ethanol;4-nitrophenol Chemical compound CCO.OC1=CC=C([N+]([O-])=O)C=C1 YPXDSSGRBXVFNZ-UHFFFAOYSA-N 0.000 claims description 8
- 238000002133 sample digestion Methods 0.000 claims description 8
- 239000012490 blank solution Substances 0.000 claims description 7
- 238000005303 weighing Methods 0.000 claims description 7
- 229920004890 Triton X-100 Polymers 0.000 claims description 6
- 239000013504 Triton X-100 Substances 0.000 claims description 6
- 230000001079 digestive effect Effects 0.000 claims description 6
- 235000013312 flour Nutrition 0.000 claims description 6
- 238000001035 drying Methods 0.000 claims description 5
- 238000010438 heat treatment Methods 0.000 claims description 5
- 239000007788 liquid Substances 0.000 claims description 5
- 230000008569 process Effects 0.000 claims description 5
- 150000002009 diols Chemical class 0.000 claims description 4
- 238000005485 electric heating Methods 0.000 claims description 4
- 229920001343 polytetrafluoroethylene Polymers 0.000 claims description 4
- 239000004810 polytetrafluoroethylene Substances 0.000 claims description 4
- 239000012086 standard solution Substances 0.000 claims description 4
- NLXLAEXVIDQMFP-UHFFFAOYSA-N Ammonium chloride Substances [NH4+].[Cl-] NLXLAEXVIDQMFP-UHFFFAOYSA-N 0.000 claims description 3
- 239000000872 buffer Substances 0.000 claims description 3
- 235000011389 fruit/vegetable juice Nutrition 0.000 claims description 3
- 238000011002 quantification Methods 0.000 claims description 3
- IMRWILPUOVGIMU-UHFFFAOYSA-N 2-bromopyridine Chemical compound BrC1=CC=CC=N1 IMRWILPUOVGIMU-UHFFFAOYSA-N 0.000 claims 1
- 239000011159 matrix material Substances 0.000 abstract description 4
- 238000002360 preparation method Methods 0.000 abstract description 4
- DVBJBNKEBPCGSY-UHFFFAOYSA-M cetylpyridinium bromide Chemical compound [Br-].CCCCCCCCCCCCCCCC[N+]1=CC=CC=C1 DVBJBNKEBPCGSY-UHFFFAOYSA-M 0.000 abstract 1
- 238000011084 recovery Methods 0.000 description 5
- PIICEJLVQHRZGT-UHFFFAOYSA-N Ethylenediamine Chemical compound NCCN PIICEJLVQHRZGT-UHFFFAOYSA-N 0.000 description 4
- 239000004411 aluminium Substances 0.000 description 4
- QAQSNXHKHKONNS-UHFFFAOYSA-N 1-ethyl-2-hydroxy-4-methyl-6-oxopyridine-3-carboxamide Chemical compound CCN1C(O)=C(C(N)=O)C(C)=CC1=O QAQSNXHKHKONNS-UHFFFAOYSA-N 0.000 description 3
- 108010007337 Azurin Proteins 0.000 description 3
- 229910052804 chromium Inorganic materials 0.000 description 3
- 239000011651 chromium Substances 0.000 description 3
- 210000002682 neurofibrillary tangle Anatomy 0.000 description 3
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 2
- 208000037259 Amyloid Plaque Diseases 0.000 description 2
- 241000196324 Embryophyta Species 0.000 description 2
- 208000036626 Mental retardation Diseases 0.000 description 2
- 235000021152 breakfast Nutrition 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000011521 glass Substances 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 239000000843 powder Substances 0.000 description 2
- 230000035945 sensitivity Effects 0.000 description 2
- 239000011573 trace mineral Substances 0.000 description 2
- 235000013619 trace mineral Nutrition 0.000 description 2
- BTJIUGUIPKRLHP-UHFFFAOYSA-N 4-nitrophenol Chemical compound OC1=CC=C([N+]([O-])=O)C=C1 BTJIUGUIPKRLHP-UHFFFAOYSA-N 0.000 description 1
- 208000024827 Alzheimer disease Diseases 0.000 description 1
- 241000209140 Triticum Species 0.000 description 1
- 235000021307 Triticum Nutrition 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 229940037003 alum Drugs 0.000 description 1
- DIZPMCHEQGEION-UHFFFAOYSA-H aluminium sulfate (anhydrous) Chemical compound [Al+3].[Al+3].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O DIZPMCHEQGEION-UHFFFAOYSA-H 0.000 description 1
- 229910021529 ammonia Inorganic materials 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 235000015895 biscuits Nutrition 0.000 description 1
- 210000000988 bone and bone Anatomy 0.000 description 1
- 210000005013 brain tissue Anatomy 0.000 description 1
- 235000008429 bread Nutrition 0.000 description 1
- 235000012970 cakes Nutrition 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 235000005911 diet Nutrition 0.000 description 1
- 230000037213 diet Effects 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 230000036541 health Effects 0.000 description 1
- 238000012417 linear regression Methods 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 210000000653 nervous system Anatomy 0.000 description 1
- 230000008520 organization Effects 0.000 description 1
- 231100000572 poisoning Toxicity 0.000 description 1
- 230000000607 poisoning effect Effects 0.000 description 1
- GNHOJBNSNUXZQA-UHFFFAOYSA-J potassium aluminium sulfate dodecahydrate Chemical compound O.O.O.O.O.O.O.O.O.O.O.O.[Al+3].[K+].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O GNHOJBNSNUXZQA-UHFFFAOYSA-J 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 210000004994 reproductive system Anatomy 0.000 description 1
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- 230000002195 synergetic effect Effects 0.000 description 1
- 231100000027 toxicology Toxicity 0.000 description 1
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- Investigating Or Analyzing Non-Biological Materials By The Use Of Chemical Means (AREA)
Abstract
The application relates to the technical field of food safety detection, in particular to a method for rapidly and quantitatively determining the content of aluminum element in food. A method for rapidly and quantitatively determining the content of aluminum element in food, which comprises the following steps: s1, sample preparation, S2, microwave digestion, S3, standard curve equation and sample determination: and (3) measuring by a spectrophotometry, wherein in the condition that polyethylene glycol octyl phenyl ether and cetyl pyridine bromide are simultaneously present in an ethylenediamine-hydrochloric acid buffer solution, trivalent aluminum ions react with chrome azure S to generate blue-green quaternary micelles, measuring the absorbance of the quaternary micelles at the wavelength of 620nm, comparing the absorbance with a standard curve, and measuring the content of aluminum element. The method provided by the application has the advantages of low detection limit, high accuracy, rapid analysis speed, high working efficiency, no influence on a sample matrix, wide linear range and the like, and is suitable for quantitative determination of the content of the aluminum element in the food.
Description
Technical Field
The application relates to the technical field of food safety detection, in particular to a method for rapidly and quantitatively determining the content of aluminum element in food.
Background
Aluminum is not a trace element required by a human body, and aluminum poisoning can be generated by long-term contact of the human body or large-scale intake of the human body in diet. The potential harm of aluminum element to bones, nervous systems and reproductive systems is acknowledged by international authorities such as world health organization. It is mentioned in the paper aluminium and alzheimer's disease, published in the netherlands journal, food and chemical toxicology, that aluminium can cause neurofibrillary tangles (NFT) and amyloid Senile Plaques (SP) in brain tissue, and it was found that the NFT density of patients suffering from alzheimer's mental retardation is 6-40 times that of normal aged people, the more aluminium element content, the more severe the mental retardation.
Aluminum is a well-known metal element, has very close relation with people in daily life, such as alum (aluminum potassium sulfate dodecahydrate) added in the process of making oil cakes and deep-fried dough sticks, baking powder (aluminum sulfate) used in the process of baking cakes, biscuits, bread and the like, and exists in the aluminum element. Although aluminum is neither a trace element necessary for the human body nor an element harmful to the human body, when taken excessively, the human body develops a series of adverse symptoms, so that monitoring of aluminum in foods is very necessary. Because the currently adopted aluminum element determination method (national standard method) has the problems of low sensitivity, poor method reproducibility and the like, a method for rapidly and quantitatively determining the aluminum element content in food needs to be developed.
Disclosure of Invention
The method for rapidly and quantitatively determining the content of the aluminum element in the food has the characteristics of accuracy and precision, accuracy, reliability, good determination effect and the like.
The technical scheme is as follows:
a method for rapidly and quantitatively determining the content of aluminum element in food, which comprises the following steps:
s1, preparing a sample: after the sample to be detected is crushed uniformly, 30g of the crushed sample is taken and placed in a constant temperature drying oven at 85 ℃ to be dried for 4 hours, so as to obtain a sample A;
s2, microwave digestion: heating a sample A in a closed container by utilizing microwaves, and rapidly dissolving the sample A under the condition of high temperature and pressure boost to obtain a sample digestive juice;
s3, standard curve equation and sample measurement: and (3) determining by adopting a spectrophotometry, firstly, in the sample digestion liquid obtained in the step (S2), under the condition that polyethylene glycol octyl phenyl ether (Triton X-100) and bromocetyl pyridine are simultaneously present in an ethylenediamine-hydrochloric acid buffer solution, trivalent aluminum ions react with chrome azure S to generate blue-green quaternary micelle, the absorbance of the quaternary micelle is determined at the wavelength of 620nm, and the absorbance is compared with a standard curve to determine the content of aluminum element.
By adopting the technical scheme, the method for rapidly and quantitatively determining the content of the aluminum element in the food provided by the application comprises the following steps of: s1, preparing a sample: after the sample to be detected is crushed uniformly, 30g of the sample is taken and put into a constant temperature drying oven at 85 ℃ to be dried for 4 hours, thus obtaining a sample A. The function of this step is to remove moisture from the sample, making the sample suitable for subsequent microwave digestion. S2, microwave digestion: and placing the sample A in a closed container by utilizing microwave heating, and rapidly dissolving the sample A under the conditions of high temperature and pressure to obtain a sample digestive juice. The microwave heating can enable the sample to reach a high temperature state rapidly, so that aluminum element in the sample is promoted to be dissolved out, and aluminum ions in the digestion solution can be further used for subsequent quantitative determination. The function of this step is to dissolve out the aluminium element in the sample so that it can be conveniently measured. S3, standard curve equation and sample measurement: and measuring the content of aluminum element by spectrophotometry. First, the sample digest obtained in step S2 was present with ethylenediamine-hydrochloric acid buffer, while polyethylene glycol octylphenyl ether (Triton X-100) and cetylpyridinium bromide were added. Under this condition, trivalent aluminum ions react with chrome azure S to form blue-green quaternary micelles. Then, the absorbance thereof was measured at a wavelength of 620nm using spectrophotometry, and the measurement result was compared with a standard curve, thereby quantitatively determining the content of aluminum element. The function of the step is to quantitatively determine a color product generated by the reaction of the chrome azure S and aluminum ions, establish a standard curve equation and determine a sample according to the standard curve equation. The synergistic effect among the steps is that after the sample is prepared, digested and measured, the content of aluminum element in the food can be measured rapidly and accurately. The sample preparation and microwave digestion steps can dissolve out aluminum element in the sample as much as possible, and the sensitivity and accuracy of the measurement are improved. Meanwhile, proper reagents and reaction conditions are introduced in the determination step, and the rapid quantitative determination of the content of aluminum element is realized by forming a quantifiable color product.
Preferably, in step S2, the microwave digestion process is as follows: accurately weighing 0.5g of sample A (flour food without sandwich and stuffed part), putting the sample A into a polytetrafluoroethylene sample dissolving cup, adding 6mL of nitric acid, pretreating at 140 ℃ by an electric heating furnace, adding 2mL of nitric acid and 1mL of hydrogen peroxide into the cup, carrying out digestion according to the operation procedure of a microwave digestion instrument, transferring the digested product into a 50mL volumetric flask, fixing the volume by water, uniformly mixing for later use, and simultaneously digesting a reagent blank test.
Preferably, the microwave digestion instrument has the following operation procedures: 1min of digestion is carried out at the first gear of 0.5MPa, 2min of digestion is carried out at the second gear of 1.0MPa, 2min of digestion is carried out at the third gear of 15MPa, and 5min of digestion is carried out at the fourth gear of 20 MPa.
Preferably, the nitric acid is analytically pure nitric acid, the hydrogen peroxide is analytically pure hydrogen peroxide, and the water is tertiary water as specified in GB/T6682.
Preferably, in step S3, the ethylenediamine-hydrochloric acid buffer has a pH of 6.7 to 7.0; the diol octyl phenyl ether (TritonX-100) is analytically pure diol octyl phenyl ether (TritonX-100), the bromo-cetyl pyridine is analytically pure bromo-cetyl pyridine, and the chrome azure S is analytically pure chrome azure S.
Preferably, in step S3, the standard curve equation and the sample are determined as follows: respectively sucking 1.00mL of digested sample digestion solution and blank solution, respectively placing the digested sample digestion solution and the blank solution in 25mL of colorimetric tubes with plugs, and adding water to a 10mL scale; another 25mL colorimetric tube with plug was taken and added with 0.0mL, 0.5mL, 1.0mL, 2.0mL, 3.0mL, 4.0mL and 5.0mL of the standard use solution for aluminum (equivalent to 0.0 μg, 0.5 μg, 1.0 μg, 2.0 μg, 3.0 μg, 4.0 μg and 50 μg of aluminum, respectively), and 1mL of 1% sulfuric acid solution was added to each tube in sequence, followed by water to a 10mL scale; dripping 1 drop of p-nitrophenol ethanol solution with the concentration of 1g/L into a standard tube, a sample tube and a reagent blank tube, uniformly mixing, dripping an ammonia water solution until the mixed solution becomes light yellow, and adding 0.5mol/L nitric acid until the yellow is disappeared (at the moment, adding 2 drops of nitric acid); adding 3.0mL of 1g/L chromium azurin S solution (1+1 ethanol solution) into the mixed solution, adding 1.0mL of 3g/L polyethylene glycol octyl phenyl ether solution, 2.0mL of 3g/L bromocetyl pyridine and 3.0mL of ethylenediamine-hydrochloric acid buffer solution after uniformly mixing, adding water to 25mL, uniformly mixing, and standing for 30 min; at 620nm wavelength, using 1cm cuvette as reference to determine absorbance value, placing on spectrophotometer, zeroing with standard sample zero tube, measuring absorbance at 620nm wavelength, drawing standard curve for comparison and quantification, and carrying out regression statistics to the result to obtain standard curve equation.
Preferably, the mass concentration of the aluminum standard solution is 1000mg/L, the sulfuric acid is analytically pure concentrated sulfuric acid, the p-nitrophenol ethanol is analytically pure p-nitrophenol ethanol, the nitric acid is analytically pure nitric acid, the polyethylene glycol octyl phenyl ether is analytically pure polyethylene glycol octyl phenyl ether, the ammonia water solution is 10mL of analytically pure ammonia water, and the ammonia water solution is added into 10mL of water and uniformly mixed to obtain the aluminum standard solution.
Preferably, in step S3, the standard curve equation is: y=0.1610x+000173, r=0.9994, r is a correlation coefficient.
Preferably, the limit of detection of the sample is 0.2mg/kg.
By adopting the technical scheme, the aluminum ions have good linear relationship in the concentration range of 0-2000 mug/L, and the correlation coefficient is 0.9994; the detection limit of the sample is 0.2mg/kg; the standard recovery rate is between 90.2 and 103.4 percent, and the relative standard deviation is between 2.2 and 3.1 percent. The method has the characteristics of low detection limit, high accuracy, high precision, high analysis speed, high working efficiency, small influence by a sample matrix, wide linear range and the like, and can be completely used for measuring food aluminum.
In summary, the beneficial technical effects of the present application are:
1. the detection limit is low: the method can realize the detection limit of the content of the aluminum element in the food of 0.2mg/kg. This means that even if a very small amount of aluminum element is present in the food, it can be accurately detected by this method.
2. The accuracy is high: in the method, the aluminum ions have good linear relation in the concentration range of 0-2000 mug/L, and the correlation coefficient is 0.9994. This demonstrates that the method can provide accurate measurement results with high reliability.
3. The precision is high: the standard recovery rate of the method is between 90.2 and 103.4 percent, and the relative standard deviation is between 2.2 and 3.1 percent. The close 100% of the standard recovery rate shows that the measurement result of the method has higher precision and can give stable and repeatable results.
4. The analysis speed is high: the method can rapidly determine the content of aluminum element in food samples by utilizing microwave heating and spectrophotometry. Compared with the traditional method, the method saves a great deal of time and labor cost.
5. The working efficiency is high: the method has the advantages of relatively simple steps of sample preparation, microwave digestion, spectrophotometry and the like, and is convenient to operate. The working efficiency can be improved, and the method is suitable for rapid measurement of a large number of samples.
6. The influence by the sample matrix is small: the method utilizes spectrophotometry to measure the absorbance of aluminum at the wavelength of 620nm, and can reduce the influence of the interference of a sample matrix on a measurement result. Therefore, the method has better applicability to different types of food matrixes.
7. The linear range is wide: the linear range of aluminum ions in the method is 0-50 mug/L. The wide linear range can adapt to the variation range of the aluminum element content in different samples.
Detailed Description
Embodiments of the present application will be described in detail below with reference to examples, but it will be understood by those skilled in the art that the following examples are only for illustration of the present application and should not be construed as limiting the scope of the present application. The specific conditions are not noted in the examples and are carried out according to conventional conditions or conditions recommended by the manufacturer. The reagents or apparatus used were not manufacturer's noted, were all commercially available and commercially available, all reagents were analytically pure unless otherwise indicated, and the test water or water was the tertiary water specified in GB/T6682.
1. Solution preparation
1. The ethylenediamine-hydrochloric acid buffer solution (pH 6.7-7.0) is prepared by measuring 100mL ethylenediamine along a glass rod, slowly adding into 200mL water, cooling, slowly adding 190mL hydrochloric acid along the glass rod, mixing, and adjusting pH with hydrochloric acid solution (1+1) or ethylenediamine solution (1+2) if pH is greater than 7.0 or pH is less than 6.7.
2. Ethylenediamine solution (1+2) 10mL ethylenediamine was measured and slowly added to 20mL water, and mixed well.
3. Solution of cetylpyridinium bromide (3 g/L) 0.3g cetylpyridinium bromide was weighed and dissolved in 15mL absolute ethanol, diluted to 100mL with water, and mixed well.
4. The Triton X-100 solution (3%) is prepared by sucking 3mL of Triton X-100, placing in a 100mL volumetric flask, adding water to scale, and mixing.
5. 0.1g of the chrome azurin S solution (1 g/L) is weighed and dissolved in 100mL of ethanol solution (1+1), and evenly mixed.
6. The ethanol solution (1+1) is prepared by weighing 50mL of absolute ethanol, dissolving in 50mL of water, and mixing.
7. The nitric acid solution (0.5 mol/L) is prepared by taking 31.5g of nitric acid, adding water to 1000mL scale, and uniformly mixing.
8. The ammonia solution (1+1) is prepared by weighing 10mL of ammonia, adding into 10mL of water, and mixing.
9. The sulfuric acid solution (1 percent) is that 1mL of sulfuric acid is absorbed and slowly added into 80mL of water, and the mixture is cooled and diluted to 100mL of water and evenly mixed.
10. The p-nitrophenol ethanol solution (1 g/L) is prepared by weighing 0.1g of p-nitrophenol, dissolving in 100mL of absolute ethanol, and mixing.
11. Polyethylene glycol octyl phenyl ether solution (3 g/L): 0.3g of polyethylene glycol octyl phenyl ether is weighed, dissolved in 100mL of water and evenly mixed.
12. Accurately sucking 1.00mL of aluminum standard solution (1000 mg/L) into a 10mL volumetric flask, adding nitric acid solution (5%) to a fixed volume to scale, and mixing.
13. Aluminum standard use solution (1.00 mg/L) 1.00mL aluminum standard intermediate solution (100 mg/L) was accurately sucked, placed in a 100mL volumetric flask, diluted to scale with nitric acid solution (5%) and mixed well.
2. Sample processing and digestion
After the sample (excluding the sandwich and the stuffed part) is crushed uniformly, 30g of the sample is taken and placed in a constant temperature drying oven at 85 ℃ to be dried for 4 hours, so as to obtain a sample A for standby; accurately weighing 0.5g of a sample A (flour food without a sandwich and a stuffed part), putting the sample A into a polytetrafluoroethylene sample dissolving cup, adding 6mL of nitric acid, pretreating at 140 ℃ by an electric heating furnace, adding 2mL of nitric acid and 1mL of hydrogen peroxide into the cup, and carrying out digestion according to the operation procedure of a microwave digestion instrument, wherein the operation procedure of the microwave digestion instrument is as follows: 1min of digestion is carried out at the first gear of 0.5MPa, 2min of digestion is carried out at the second gear of 1.0MPa, 2min of digestion is carried out at the third gear of 15MPa, and 5min of digestion is carried out at the fourth gear of 20 MPa. And transferring the digested sample into a 50mL volumetric flask, fixing the volume by using water, uniformly mixing for standby, and simultaneously performing a digestion reagent blank test.
Example 1 method for rapid quantitative determination of aluminum element content in food
A method for rapidly and quantitatively determining the content of aluminum element in food, which comprises the following steps:
s1, preparing a sample: after the sample to be detected is crushed uniformly, 30g of the crushed sample is taken and placed in a constant temperature drying oven at 85 ℃ to be dried for 4 hours, so as to obtain a sample A;
s2, microwave digestion: accurately weighing 0.5g of a sample A (flour food without a sandwich and a stuffed part), putting the sample A into a polytetrafluoroethylene sample dissolving cup, adding 6mL of nitric acid, pretreating at 140 ℃ by an electric heating furnace, adding 2mL of nitric acid and 1mL of hydrogen peroxide into the cup, and carrying out digestion according to the operation procedure of a microwave digestion instrument, wherein the operation procedure of the microwave digestion instrument is as follows: 1min of digestion is carried out at the first gear of 0.5MPa, 2min of digestion is carried out at the second gear of 1.0MPa, 2min of digestion is carried out at the third gear of 15MPa, and 5min of digestion is carried out at the fourth gear of 20 MPa. Transferring the digested sample into a 50mL volumetric flask, metering the volume with water, uniformly mixing for later use, and performing a digestion reagent blank test;
s3, standard curve equation and sample measurement: the spectrophotometry is adopted to determine, firstly, the sample digestive liquid obtained in the step S2 is reacted with chromium azure S to generate blue-green quaternary micelle under the condition that polyethylene glycol octyl phenyl ether (Triton X-100) and bromocetyl pyridine exist in ethylenediamine-hydrochloric acid buffer solution at the same time, the absorbance of the sample digestive liquid is measured at the wavelength of 620nm, and the sample digestive liquid is compared with a standard curve, and the standard curve equation is that: y=0.1610x+000173, r=0.9994, r is a correlation coefficient. The content of aluminum element was quantitatively measured.
EXAMPLE 2 Standard Curve equation
Respectively sucking 1.00mL of digested sample digestion solution and blank solution, respectively placing the digested sample digestion solution and the blank solution in 25mL of colorimetric tubes with plugs, and adding water to a 10mL scale; another 25mL colorimetric tube with plug was taken and added with 0.0mL, 0.5mL, 1.0mL, 2.0mL, 3.0mL, 4.0mL and 5.0mL of the standard use solution for aluminum (equivalent to 0.0 μg, 0.5 μg, 1.0 μg, 2.0 μg, 3.0 μg, 4.0 μg and 50 μg of aluminum, respectively), and 1mL of 1% sulfuric acid solution was added to each tube in sequence, followed by water to a 10mL scale; dripping 1 drop of p-nitrophenol ethanol solution with the concentration of 1g/L into a standard tube, a sample tube and a reagent blank tube, uniformly mixing, dripping an ammonia water solution until the mixed solution becomes light yellow, and adding 0.5mol/L nitric acid until the yellow is disappeared (at the moment, adding 2 drops of nitric acid); adding 3.0mL of 1g/L chromium azurin S solution (1+1 ethanol solution) into the mixed solution, adding 1.0mL of 3g/L polyethylene glycol octyl phenyl ether solution, 2.0mL of 3g/L bromocetyl pyridine and 3.0mL of ethylenediamine-hydrochloric acid buffer solution after uniformly mixing, adding water to 25mL, uniformly mixing, and standing for 30 min; the absorbance value is measured at the wavelength of 620nm by using a 1cm cuvette and taking a blank solution as a reference, the cuvette is placed on a spectrophotometer, a standard sample is used for zeroing, the absorbance is measured at the wavelength of 620nm, a standard curve is drawn for comparison and quantification, and regression statistics is carried out on the result to obtain the standard curve. The linear parameters are shown in Table 1.
TABLE 1 Standard Curve and Linear parameters
EXAMPLE 3 precision test
Two different aluminum-containing samples were precisely weighed and measured 6 times in succession, with a relative standard deviation RSD of 2.2% -3.1%, respectively, according to the test conditions of example 1. The results are shown in Table 2, where the results are converted to the aluminum content in the sample.
TABLE 2
Example 4 accuracy test
In sample 2, the standard recovery test was performed under the test conditions of example 1, and the recovery rate was 90.2% -103.4%, the results are shown in Table 3, the results in the Table are converted into the aluminum content in the sample, and the background values are respectively the average value of 6 times of measurement.
Example 5 linearity, range, detection Limit
Preparing standard series of solutions of 0.0, 200, 400, 800, 1200, 1600 and 2000 mug/L according to the concentration of the sample, wherein the obtained linear regression equation is Y=0.1610X+000173, the concentration of the solution of x (mug/L) and the intensity of Y spectrum; the correlation coefficient is: r=0.9994. The reagent blank is continuously measured 11 times in the whole process according to the determined sample measuring method, and the detection limit is calculated according to the standard deviation of 3 times of the measuring result: 0.2mg/kg.
Example 6 sample measurement
Several foods with high aluminum-containing risks such as deep-fried dough sticks, puffed foods, frying powder, flour and the like are purchased from the market and are measured by using an established method. The measurement results are shown in Table 4, and the results show that: (1) The aluminum content of the deep-fried dough sticks purchased in the breakfast stall under the non-normal operation and the aluminum content of the deep-fried dough sticks purchased in the supermarket are all beyond the limit (100 mug/g), and the deep-fried dough sticks purchased in the supermarket and sold in the breakfast restaurant under the normal brand are qualified. (2) the aluminum content in the other samples was below the limit. (3) Aluminum is also detected in wheat flour (Xiamen, quanzhou) to which aluminum has not been added, and it is known that environmental factors such as soil and water in plant origin have an influence on the aluminum content of the plant itself.
TABLE 4 Table 4
The above embodiments are only for illustrating the technical solution of the present invention and not for limiting the same, and although the above embodiments specifically illustrate the present invention, it should be understood by those skilled in the art that modifications and equivalents may be made to the specific embodiments of the present invention without departing from the spirit and scope of the present invention, and any modifications and equivalents are intended to be covered by the scope of the claims of the present invention.
Claims (9)
1. A method for rapidly and quantitatively determining the content of aluminum in food, which is characterized by comprising the following steps:
s1, preparing a sample: after the sample to be detected is crushed uniformly, 30g of the crushed sample is taken and placed in a constant temperature drying oven at 85 ℃ to be dried for 4 hours, so as to obtain a sample A;
s2, microwave digestion: heating a sample A in a closed container by utilizing microwaves, and rapidly dissolving the sample A under the condition of high temperature and pressure boost to obtain a sample digestive juice;
s3, standard curve equation and sample measurement: and (3) determining by adopting a spectrophotometry, firstly, in the sample digestion liquid obtained in the step (S2), under the condition that polyethylene glycol octyl phenyl ether (Triton X-100) and bromocetyl pyridine are simultaneously present in an ethylenediamine-hydrochloric acid buffer solution, trivalent aluminum ions react with chrome azure S to generate blue-green quaternary micelle, the absorbance of the quaternary micelle is determined at the wavelength of 620nm, and the absorbance is compared with a standard curve to quantitatively determine the content of aluminum element.
2. The method for rapidly and quantitatively determining the content of aluminum in food according to claim 1, wherein in step S2, the microwave digestion process comprises: accurately weighing 0.5g of sample A (flour food without sandwich and stuffed part), putting the sample A into a polytetrafluoroethylene sample dissolving cup, adding 6mL of nitric acid, pretreating at 140 ℃ by an electric heating furnace, adding 2mL of nitric acid and 1mL of hydrogen peroxide into the cup, carrying out digestion according to the operation procedure of a microwave digestion instrument, transferring the digested product into a 50mL volumetric flask, fixing the volume by water, uniformly mixing for later use, and simultaneously digesting a reagent blank test.
3. The method for rapidly and quantitatively determining the content of aluminum in food according to claim 2, wherein the microwave digestion instrument is operated according to the following procedures: 1min of digestion is carried out at the first gear of 0.5MPa, 2min of digestion is carried out at the second gear of 1.0MPa, 2min of digestion is carried out at the third gear of 15MPa, and 5min of digestion is carried out at the fourth gear of 20 MPa.
4. The method for rapid quantitative determination of aluminum content in food according to claim 2, wherein the nitric acid is analytically pure nitric acid, the hydrogen peroxide is analytically pure hydrogen peroxide, and the water is tertiary water specified in GB/T6682.
5. The method for rapid quantitative determination of aluminum content in food according to claim 1, wherein in step S3, the ethylenediamine-hydrochloric acid buffer has a pH of 6.7-7.0; the diol octyl phenyl ether (TritonX-100) is analytically pure diol octyl phenyl ether (TritonX-100), the bromo-cetyl pyridine is analytically pure bromo-cetyl pyridine, and the chrome azure S is analytically pure chrome azure S.
6. The method according to claim 1, wherein in step S3, the standard curve equation and the sample are determined as follows: respectively sucking 1.00mL of digested sample digestion solution and blank solution, respectively placing the digested sample digestion solution and the blank solution in 25mL of colorimetric tubes with plugs, and adding water to a 10mL scale; taking 7 tubes of a 25-mL colorimetric tube with a plug, respectively adding 0.0mL, 0.5mL, 1.0mL, 2.0mL, 3.0mL, 4.0mL and 5.0mL (equivalent to 0.0 mug, 0.5 mug, 1.0 mug, 2.0 mug, 3.0 mug, 4.0 mug and 50 mug of aluminum respectively) of standard use solution of aluminum, sequentially adding 1mL sulfuric acid solution with the concentration of 1% into each tube, adding water to a 10mL scale, dripping 1 drop of p-nitrophenol ethanol solution with the concentration of 1g/L into a standard tube, a sample tube and a reagent blank tube, dripping ammonia water solution until the mixed solution becomes light yellow, then adding 0.5mol/L nitric acid until the yellow color disappears (at this moment, adding 2 drops of nitric acid into the mixed solution, adding 3.0mL of 1g/L chrome TianS solution (1+1 ethanol solution) into the mixed solution, adding 1.0mL of 3g/L of polyethylene glycol, 2 g/L of octyl diamine with the concentration of 3g/L, adding 3g/L of 2-bromopyridine into the mixed solution, and mixing the mixed solution until the mixed solution is 3mL of hydrochloric acid solution is mixed with the solution is mixed with water to be 3mL, and then placing the mixed solution for 25-30 min; at 620nm wavelength, using 1cm cuvette as reference to determine absorbance value, placing on spectrophotometer, zeroing with standard sample zero tube, measuring absorbance at 620nm wavelength, drawing standard curve for comparison and quantification, and carrying out regression statistics to the result to obtain standard curve equation.
7. The method for rapidly and quantitatively determining the content of aluminum in food according to claim 6, wherein the mass concentration of the aluminum standard solution is 1000mg/L, the sulfuric acid is analytically pure concentrated sulfuric acid, the p-nitrophenol ethanol is analytically pure p-nitrophenol ethanol, the nitric acid is analytically pure nitric acid, the polyethylene glycol octyl phenyl ether is analytically pure polyethylene glycol octyl phenyl ether, the ammonia solution is 10mL of analytically pure ammonia water, and the ammonia solution is added into 10mL of water and uniformly mixed.
8. The method according to claim 6, wherein in step S3, the standard curve equation is: y=0.1610x+000173, r=0.9994, r is a correlation coefficient.
9. The method for rapid quantitative determination of aluminum content in food according to claim 1, wherein the sample detection limit is 0.2mg/kg.
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