Method for rapidly detecting content of aluminum ions in raw wine

Abstract

The invention discloses a method for rapidly detecting the content of aluminum ions in raw wine. Kaempferol is used as a probe, the detection response is rapid, fluorescence signal reading is completed within 2 min, the method is far better than a traditional method, and the method is suitable for on-site rapid detection; the method is high in selectivity, free of interference of common metal ions in raw wine and good in linear relation.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metal ion fluorescence detection, and specifically provides a method for rapidly detecting aluminum ion content in raw liquor. BACKGROUND

[0002] As a traditional distilled liquor in China, baijiu (liquor) has various types and different flavors, and different brewing processes. The main components of baijiu are alcohol and water, accounting for 98%-99% of the total amount. However, the quality and style of baijiu are mainly determined by about 2% of trace components in baijiu, including organic acids, esters, alcohols, aldehydes, pyrazines, terpenes, nucleosides, lipopeptides, metal ions and other substances. These substances have their own characteristics, forming a complex composition and variable taste. Among the numerous trace components, metal ions, although in very small amounts, play a key role in the flavor presentation, stability maintenance and health effects of baijiu. In recent years, with the progress of analytical techniques, researchers have gradually revealed the complex interactions between metal ions and organic components in baijiu. These interactions not only affect the sensory quality of baijiu, but also relate to the safety and stability of the product. The source of metal ions in the liquor is diverse, forming a complete migration path from raw materials to consumption. Raw material crops (such as sorghum, rice, etc.) absorb minerals from the soil through the root system during the growth process, becoming the initial source of metal ions. Brewing equipment is another important source, and stainless steel containers may dissolve iron, chromium, nickel and other elements, while traditional pottery jars contribute aluminum, silicon and trace lead. It is particularly noteworthy that the continuous ion migration during the storage process of pottery jars significantly affects the aging quality of baijiu. The quality of the added water is also crucial, and the metal components contained in the added water treated by different methods (ion exchange, reverse osmosis, microfiltration) differ significantly, directly affecting the quality of the finished liquor. In addition, clarifying agents (such as bentonite, gelatin, activated carbon, diatomaceous earth, etc.) may introduce aluminum, calcium and other elements, and the pipeline delivery system may also be a source of contamination of iron, aluminum and other metals. Therefore, based on the production and process of raw liquor, the content of various types of metal ions in the liquor body is quite different, and aluminum ions are one of the higher components of metal elements in the liquor. The influence of aluminum ions on the quality of the liquor body exhibits a dual effect. On the one hand, the presence of aluminum ions makes the liquor quality worse, which is manifested in the presence of single, astringent feeling in the liquor body with the increase of aluminum ions. Al 3+ With the increase of the concentration of Al 3+ , a small amount of Al(OH)3 may be generated, thereby causing the liquor quality to deteriorate. On the other hand, Al 3+ can form complexes with alcohols, promoting the release of aroma substances, which is one of the key factors for the formation of “aged aroma”. Therefore, too high or too low content of aluminum ions in the liquor will have a serious impact on the quality of the liquor.

[0003] The determination of aluminum in food in the national food safety standards of China (GB 5009.182-2017) provides that the spectrophotometry is suitable for detecting aluminum in food, and the inductively coupled plasma mass spectrometry and the graphite furnace atomic absorption spectrometry are suitable for detecting aluminum in food. In addition to this, the commonly used aluminum ion detection methods include high performance liquid chromatography, electrochemical method, complexometric titration and the like. These methods have high precision and reliability, but are limited by high cost, complex operation, long time consumption and the like, and are difficult to realize convenient and rapid detection of aluminum ions. SUMMARY

[0004] In view of this, the present application provides a method for rapidly detecting the content of aluminum ions in raw wine, which is simple to operate, low in cost, strong in anti-interference and suitable for complex raw wine system, and meets the rapid detection demand of production site.

[0005] The technical scheme of the present application is realized as follows: the present application provides a method for rapidly detecting the content of aluminum ions in raw wine, which is realized through the following scheme: (1) taking 3 mL of raw wine sample, adding NaOH solution to adjust pH to 6.0-7.0; (2) adding kaempferol ethanol solution to the above sample to make the final concentration of kaempferol in the raw wine be 1×10 -5 -5×10 -5 mol / L (equivalent to 2.7-13.5 mg / L); (3) after mixing uniformly, detecting the fluorescence intensity of the system at 515 nm (excitation wavelength 390 nm, emission slit 15 nm) within 2 min by using a fluorescence spectrophotometer; (4) calculating the content according to the linear relationship between the aluminum ion concentration and the fluorescence intensity, the linear relationship being Y=1277+2912X (Y is the fluorescence intensity, X is the aluminum ion concentration, unit mg / L), the correlation coefficient R 2 ≥0.99, and the detection limit ≤0.008 mg / L.

[0006] In some embodiments, the following auxiliary agents are added in step (1) of the basic method to further improve the anti-interference: (1) copper ion masking agent: adding penicillamine with a final concentration of 0.1-1 mM, which preferentially forms a stable complex with copper ions in the raw wine to avoid coordination with kaempferol; (2) organic acid competitor: adding triethanolamine with a volume fraction of 0.5-5%, which competes with aluminum ion coordination sites by organic acid to reduce the interference of organic acid on detection; (3) Anti-precipitation agent: polyvinylpyrrolidone K30 (PVP-K30) is added with a mass fraction of 0.05-0.5%, which inhibits the formation of colloidal precipitate of aluminum ions and improves the contact efficiency of the probe and aluminum ions.

[0007] In some embodiments, the present application also provides a fluorescent probe composition for detecting aluminum ions in raw liquor, comprising: Kaempferol: final concentration 1×10 -5 -5×10 -5 mol / L; Penicillamine: 0.1-1 mM (molar ratio to kaempferol is 1:1-5:1); Triethanolamine: volume fraction 0.5-5% (mass-volume ratio to PVP-K30 is 3:1-10:1); Polyvinylpyrrolidone K30: mass fraction 0.05-0.5%; The pH of the composition system is 6.0-7.0, which is suitable for raw liquor matrix.

[0008] The above method and composition can be applied to the mass control of aluminum ions in raw liquor of different types of Baijiu, including raw material acceptance, brewing equipment monitoring, and storage period tracking in the production process.

[0009] The present application has the following beneficial effects compared with the prior art: Kaempferol is a natural tetrahydroxy flavonoid compound that can be extracted from tea leaves, broccoli and other plants. The raw material is easy to obtain and has low cost. It does not need complex organic synthesis and has low biological toxicity. It is friendly to the human body and the environment. The detection response is fast, and the fluorescence signal reading is completed within 2 minutes, which is much faster than traditional methods and is suitable for on-site rapid detection. It has strong selectivity and is not affected by common metal ions in raw liquor. It has good linear relationship and low detection limit of 0.008 mg / L, which meets the detection requirements of aluminum ions in raw liquor.

[0010] By masking copper ions with penicillamine, blocking organic acid interference with triethanolamine, and inhibiting precipitation with PVP-K30, the detection deviation is ≤5% in high interference scenarios with copper ion concentration ≤1 mg / L and organic acid concentration ≤100 mg / L. It is suitable for different types of raw liquor (Luzhou-flavor, Qingxiang-flavor, etc.), and solves the influence of alcohols and esters in raw liquor on the detection system. The synergistic effect of each component does not affect the coordination reaction of kaempferol and aluminum ions, and the fluorescence response intensity remains above 90%. BRIEF DESCRIPTION OF DRAWINGS

[0011] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description only represent some of the embodiments of the present application, and for those skilled in the art, other drawings can also be obtained from these drawings without creative effort.

[0012] Figure 1 The figure of selective intensity of the fluorescent probe in the embodiment 1 of the present application to different metal ions; Figure 2 The figure of linear relationship between the metal ion concentration and the fluorescent intensity in the embodiment 2 of the present application; Figure 3 The fluorescent response value of different base liquor in the embodiment 3 of the present application. DETAILED DESCRIPTION

[0013] The technical solutions in the embodiments of the present application will be described clearly and completely in combination with the embodiments of the present application. Obviously, the described embodiments only represent some of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments of the present application, all the other embodiments obtained by those skilled in the art without creative effort fall within the scope of the present application.

[0014] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the embodiments of the present application belong. If the definitions stated in this section are contrary to or otherwise inconsistent with the definitions stated in the patents, patent applications, published patent applications, and other publications that are herein incorporated by reference, the definitions stated in this section are preferred.

[0015] The methods used in the following examples are all conventional methods unless otherwise specified. The materials, reagents and instruments used are all conventional materials, reagents and instruments in the art unless otherwise specified, and can be obtained by commercial channels by those skilled in the art.

[0016] When equivalent, concentration, or other value or parameter is expressed in a range, a preferred range or a series of upper preferred values and lower preferred values, it is to be understood that all ranges formed by any pair of any upper range limit or preferred value and any lower range limit or preferred value, even if the range is not explicitly disclosed, are to be specifically disclosed. For example, when a range "1 to 5" is disclosed, the described range is to be interpreted to include the range "1 to 4", "1 to 3", "1 to 2", "1 to 2 and 4 to 5", "1 to 3 and 5", etc. When a numerical range is expressed in this document, unless otherwise stated, the range is intended to include its end values and all integers and fractions within the range. In the specification and claims of this application, range definitions can be combined and / or interchanged, unless otherwise stated, and these ranges include all sub-ranges contained therein.

[0017] Example 1 Selective detection: Accurately weigh 2 mg of kaempferol, add 1 mL of ethanol to dissolve it completely for use. Prepare different metal ion stock solutions with a concentration of 100 mg / L (iron, potassium, calcium, sodium, magnesium, zinc, aluminum, copper, mercury). Take 30 μL of the above metal ion stock solution and add it to 3 mL of the original liquor without metal ions (the original liquor has almost no metal ions after ion exchange resin treatment), then detect the sample pH value and add NaOH solution to make the pH value 6.5. Add the probe solution (50 μL) to obtain the sample solution to be tested, and after the response is complete, use a fluorescence spectrophotometer to measure the fluorescence intensity of the sample solution to be tested at 515 nm, and the results are shown in Figure 1 .

[0018] Example 2 Linear relationship between metal ion concentration and fluorescence intensity: Based on Example 1: Filter the Luzhou-flavor original liquor, and add aluminum ion solution to the sample according to the target aluminum ion concentration, i.e. obtain original liquor sample solutions with different aluminum concentrations, then detect the sample pH value and add NaOH solution to make the pH value 6.5, i.e. obtain original liquor sample solutions with different aluminum ion concentrations. Take the above original liquor sample (3 mL) and add the probe solution (50 μL) to obtain the sample solution to be tested, and after the response is complete, use a fluorescence spectrophotometer to measure the fluorescence intensity of the sample solution to be tested at 515 nm, and the linear equation Y = 1277 + 2912 * X (X is the aluminum ion concentration, Y is the fluorescence emission peak intensity value) is obtained by fitting the linear relationship between the metal ion concentration and the fluorescence intensity, as shown in Figure 2 .

[0019] Example 3 Detection of different original liquors by fluorescence probe: Based on Example 1: The unknown liquor sample with unknown aluminum ion content is detected by the same detection method. The to-be-detected liquor is taken and an alkaline solution is added to make the pH value 6.5. The probe solution is added to obtain a to-be-detected sample solution. After the response is complete, the fluorescence intensity of the to-be-detected sample solution at 515 nm is measured by using a fluorescence spectrometer. According to the linear equation of the fitting curve, the aluminum ion content in the to-be-detected sample solution can be obtained. The results are shown in Figure 3 .

[0020] Example 4 Accurately take 0.57 mg of kaempferol, add 1 mL of ethanol to dissolve to obtain a kaempferol ethanol solution, and reserve it; and take 7.46 mg of penicillamine, dissolve it in 1 mL of deionized water to obtain a penicillamine aqueous solution, and reserve it.

[0021] Experimental group: take 3 mL of Luzhou-flavor base liquor (background Al 3+ 0.50 mg / L, Cu 2+ 0.05 mg / L), and sequentially add: 50 μL of kaempferol ethanol solution (final concentration 3.3 × 10 -5 mol / L); 30 μL of penicillamine aqueous solution (final concentration 0.5 mM); Adjust the pH to 6.5 with NaOH, mix well, and measure the fluorescence intensity at 515 nm after 2 min.

[0022] Control group: take 3 mL of Luzhou-flavor base liquor (background Al 3+ 0.50 mg / L, Cu 2+ 0.05 mg / L), and sequentially add: 50 μL of kaempferol ethanol solution (final concentration 3.3 × 10 -5 mol / L); Adjust the pH to 6.5 with NaOH, mix well, and measure the fluorescence intensity at 515 nm after 2 min.

[0023] The results are as follows:

[0024] Example 5 Accurately take 0.57 mg of kaempferol, add 1 mL of ethanol to dissolve to obtain a kaempferol ethanol solution, and reserve it; and take 7.46 mg of penicillamine, dissolve it in 1 mL of deionized water to obtain a penicillamine aqueous solution, and reserve it.

[0025] Experimental group: take 3 mL of Luzhou-flavor base liquor (background Al 3+ 0.50 mg / L, Cu 2+ 0.05 mg / L), and sequentially add: 50 μL of kaempferol ethanol solution (final concentration 3.3 × 10 -5 mol / L); 30 μL penicillamine aqueous solution (final concentration 0.5 mM); 60 μL triethanolamine (final concentration 2% v / v); Adjust pH to 6.5 with NaOH, mix well, and measure fluorescence intensity at 515 nm after 2 min.

[0026] Control group: take 3 mL of strong-flavor base liquor (background Al 3+ 0.50 mg / L, Cu 2+ 0.05 mg / L), and add sequentially: 50 μL kaempferol ethanol solution (final concentration 3.3 x 10 -5 mol / L); 30 μL penicillamine aqueous solution (final concentration 0.5 mM); Adjust pH to 6.5 with NaOH, mix well, and measure fluorescence intensity at 515 nm after 2 min.

[0027] The results are as follows:

[0028] Example 6 Spiked recovery verification: Accurately weigh 0.57 mg of kaempferol, add 1 mL of ethanol to dissolve to obtain a kaempferol ethanol solution, and reserve; and weigh 7.46 mg of penicillamine, and dissolve with 1 mL of deionized water to obtain a penicillamine aqueous solution for reserve.

[0029] Take 3 mL of Jiang-flavor base liquor (background Al 3+ 0.55 mg / L, Cu 2+ 0.90 mg / L, tartaric acid 80 mg / L), and add sequentially: 50 μL kaempferol ethanol solution (final concentration 3.3 x 10 -5 mol / L); 30 μL penicillamine aqueous solution (final concentration 0.5 mM); 60 μL triethanolamine (final concentration 2% v / v); 15 mg PVP-K30 (final concentration 2 wt%); Adjust pH to 6.5 with NaOH, mix well, and measure fluorescence intensity at 515 nm after 2 min.

[0030] Add aluminum ions 0, 0.25, 0.50, 1.00 mg / L, respectively, and measure by ICP-MS in parallel.

[0031] The results are as follows:

[0032] Comparison with ICP-MS

[0033] Comparative Example 1 The above liquor of Example 3 was detected for aluminum ion content by inductively coupled plasma mass spectrometer, and the comparison results are as follows:

[0034] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for rapidly detecting the aluminum ion content in raw wine, characterized in that , including the following steps: (1) Take a sample of raw liquor and adjust the pH to 6.0-7.0; (2) Kaempferol was added when its concentration in the original wine sample was 1×10 -5 –5×10 -5 mol / L; (3) Measure the fluorescence intensity at 515 nm within 2 minutes; (4) Calculate the aluminum ion content based on the linear relationship between aluminum ion concentration and fluorescence intensity.

2. The method according to claim 1, wherein The linear relationship is Y=1277+2912X, R 2 ≥0.99, detection limit ≤0.008 mg / L.

3. The method according to claim 1, wherein Step (1) further comprises adding a copper ion masking agent, wherein the masking agent is penicillamine at a concentration of 0.1-1 mM.

4. The method according to claim 3, wherein Step (1) also includes adding an organic acid competitor triethanolamine at a volume fraction of 0.5–5%.

5. The method according to claim 3, wherein Step (1) further includes adding an anti-precipitation agent polyvinyl pyrrolidone K30 with a mass fraction of 0.05-0.5%.

6. A fluorescent probe composition for detecting aluminum ions in raw liquor, characterized in that: include: Kaempferol, the concentration of kaempferol in the detection system is 1×10 -5 –5×10 -5 mol / L.

7. The composition according to claim 6, wherein The method further comprises penicillamine, wherein the concentration of the penicillamine in the detection system is 0.1-1 mM, and the molar ratio of penicillamine to kaempferol is 1:1-5:

1.

8. The composition according to claim 6, wherein The method further comprises triethanolamine, wherein the volume fraction of the triethanolamine in the detection system is 0.5-5%, and the mass volume ratio of the triethanolamine to the polyvinyl pyrrolidone is 3:1-10:

1.

9. The composition according to claim 6, wherein Polyvinyl pyrrolidone K30 is also included, and the mass fraction of polyvinyl pyrrolidone K30 in the detection system is 0.05-0.5%.

10. Use of the method according to any one of claims 1 to 5 or the composition according to any one of claims 6 to 9 in the quality control of aluminum ions in base liquor of Luzhou-flavor, Light-flavor, Sauce-flavor, Rice-flavor, Feng-flavor, Mixed-flavor, Dong-flavor, Chi-flavor, Sesame-flavor, Special-flavor, Laobaigan-flavor or Fuyu-flavor liquor.

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