CN111505097A - Electrochemical method for measuring nicotine content in tobacco and tobacco related products - Google Patents
Electrochemical method for measuring nicotine content in tobacco and tobacco related products Download PDFInfo
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- 241000208125 Nicotiana Species 0.000 title claims abstract description 102
- 235000002637 Nicotiana tabacum Nutrition 0.000 title claims abstract description 102
- SNICXCGAKADSCV-JTQLQIEISA-N (-)-Nicotine Chemical compound CN1CCC[C@H]1C1=CC=CN=C1 SNICXCGAKADSCV-JTQLQIEISA-N 0.000 title claims abstract description 68
- SNICXCGAKADSCV-UHFFFAOYSA-N nicotine Natural products CN1CCCC1C1=CC=CN=C1 SNICXCGAKADSCV-UHFFFAOYSA-N 0.000 title claims abstract description 68
- 229960002715 nicotine Drugs 0.000 title claims abstract description 68
- 238000002848 electrochemical method Methods 0.000 title claims abstract description 24
- 239000000047 product Substances 0.000 claims abstract description 37
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- 238000004365 square wave voltammetry Methods 0.000 claims abstract description 16
- 238000002484 cyclic voltammetry Methods 0.000 claims abstract description 15
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- 238000005259 measurement Methods 0.000 claims description 14
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 12
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- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 claims description 10
- 239000010931 gold Substances 0.000 claims description 10
- 229910052737 gold Inorganic materials 0.000 claims description 10
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- 238000005903 acid hydrolysis reaction Methods 0.000 claims description 6
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- 238000005070 sampling Methods 0.000 claims description 4
- 238000010438 heat treatment Methods 0.000 claims description 3
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- 238000004458 analytical method Methods 0.000 description 6
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- WCUXLLCKKVVCTQ-UHFFFAOYSA-M Potassium chloride Chemical compound [Cl-].[K+] WCUXLLCKKVVCTQ-UHFFFAOYSA-M 0.000 description 4
- BNIILDVGGAEEIG-UHFFFAOYSA-L disodium hydrogen phosphate Chemical compound [Na+].[Na+].OP([O-])([O-])=O BNIILDVGGAEEIG-UHFFFAOYSA-L 0.000 description 4
- 229910000397 disodium phosphate Inorganic materials 0.000 description 4
- 239000012528 membrane Substances 0.000 description 4
- 239000001103 potassium chloride Substances 0.000 description 4
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- 230000000052 comparative effect Effects 0.000 description 3
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- GNSKLFRGEWLPPA-UHFFFAOYSA-M potassium dihydrogen phosphate Chemical compound [K+].OP(O)([O-])=O GNSKLFRGEWLPPA-UHFFFAOYSA-M 0.000 description 3
- 238000007650 screen-printing Methods 0.000 description 3
- 239000011550 stock solution Substances 0.000 description 3
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- 238000001069 Raman spectroscopy Methods 0.000 description 2
- 229910021607 Silver chloride Inorganic materials 0.000 description 2
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- 238000007865 diluting Methods 0.000 description 2
- 238000000840 electrochemical analysis Methods 0.000 description 2
- 238000000835 electrochemical detection Methods 0.000 description 2
- DCAYPVUWAIABOU-UHFFFAOYSA-N hexadecane Chemical compound CCCCCCCCCCCCCCCC DCAYPVUWAIABOU-UHFFFAOYSA-N 0.000 description 2
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- HKZLPVFGJNLROG-UHFFFAOYSA-M silver monochloride Chemical compound [Cl-].[Ag+] HKZLPVFGJNLROG-UHFFFAOYSA-M 0.000 description 2
- 230000000391 smoking effect Effects 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- IRJNJBIOUYJBHG-UHFFFAOYSA-N 3-(1-methylpyrrolidin-2-yl)pyridine Chemical compound CN1CCCC1C1=CC=CN=C1.CN1CCCC1C1=CC=CN=C1 IRJNJBIOUYJBHG-UHFFFAOYSA-N 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
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- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
- G01N27/416—Systems
- G01N27/48—Systems using polarography, i.e. measuring changes in current under a slowly-varying voltage
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- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N1/00—Sampling; Preparing specimens for investigation
- G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
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- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N1/00—Sampling; Preparing specimens for investigation
- G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
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Abstract
The invention provides an electrochemical method for measuring nicotine content in tobacco and tobacco related products, which comprises the following steps: 1) carrying out acidolysis on tobacco and tobacco related products, filtering, and adding an electrolyte into a filtrate to obtain a sample solution; 2) adding the nicotine standard sample into electrolyte to dilute and fix the volume to obtain standard solution; 3) dropwise adding acid into the selected electrode, and performing electrochemical treatment by adopting a cyclic voltammetry method to obtain a pretreated working electrode; 4) and dropwise adding the sample solution and the standard solution onto a working electrode for square wave voltammetry determination, and calculating the content of nicotine in the sample solution by a standard curve method. The electrochemical method for measuring the nicotine content in the tobacco and the tobacco related products, provided by the invention, has the advantages of simple preparation process, stable electrode performance, good reproducibility, low detection cost, high detection speed and high detection accuracy.
Description
Technical Field
The invention belongs to the technical field of electrochemical analysis and detection, relates to an electrochemical method for measuring nicotine content in tobacco and tobacco-related products, and particularly relates to an electrochemical method for directly, simply, quickly and accurately measuring nicotine content in tobacco and tobacco-related products (tobacco leaves, cut stems, sheets, finished cigarettes, electronic cigarettes, buccal cigarettes, heated non-burning cigarettes and the like).
Background
Tobacco is a special commercial crop of long history and is widely cultivated in the united states, china, india, brazil and cuba. The total yield and total area of tobacco planting and the production of cigarettes in China are at the top of the world at present, and become an important consumer product and tax source in China. Smoking harmfulness and health are major concerns all over the world, and the two directions of development of the tobacco industry at present are to reduce the harm caused by smoking to the maximum extent and to retain the special aroma and taste of tobacco.
Nicotine (also called Nicotine (1-methyl-2 (3-pyridyl) pyrrolidine), NCT for short, with the content of about 1% -2% in tobacco is a main alkaloid in tobacco, is an unpleasant, bitter and light yellow oily liquid at normal temperature, can be easily oxidized into dark gray after being placed under light for a long time, can be quickly dissolved in organic solvents such as ethanol, ether, chloroform and the like and can be dissolved in water The economic value and tar and harm reduction of tobacco have important significance.
In the last two decades, researchers developed many methods for measuring NCT, such as Raman spectroscopy, liquid chromatography, high performance liquid chromatography-electrochemical method (HP L C-EC), gas chromatography-mass spectrometry (GC-MS), titration method, gravimetric method, chemiluminescence method and the like, Raman spectroscopy is simple and rapid for measuring nicotine, but is easily affected by the sensitivity and accuracy of the method, and the bandwidth, wavelength selectivity, range, impurities and the like, so that the deviation of the measurement result is easily caused, and British research work in the later 80 s shows that the measurement result when the nicotine is measured by using a spectrometer is lower than the actual value, and liquid chromatography and gas chromatography-mass spectrometry are analysis methods commonly adopted in the industry at present, have the advantages of high detection precision, but the required instruments are expensive and complicated to operate, and need derivatization treatment of reagents before analysis, the required test time is long, and are not favorable for on-site rapid detection of samples.
Electrochemical methods have been increasingly used for qualitative and quantitative detection of nicotine due to their remarkable characteristics of high sensitivity, fast response, simple operation, small sample requirement, portability, low price, capability of on-site on-line detection and analysis, and the like, such as Suffredidi et al, Electrochemical biosensor of nicotine clinical analysis at boron-lateral differential electrons, Anal L et al, 38(10) 1587-]The method firstly proposes that a boron-doped diamond electrode is adopted to detect nicotine, the detection potential is +1.30V (vs. Ag/AgCl), and a good linear range is obtained; stoces, etc. [ 2 ]et al.,Electrochemicalbehavior of nicotine at unmodified carbon paste electrode and itsdetermination in a set of refilling liquids for electroniccigarettes.Electroanal.2014,26:2655-2663]And (3) detecting nicotine by using a carbon paste electrode, and further reducing the detection potential to +0.95V (vs. Ag/AgCl). However, such methods for modifying electrodes are costly and it is difficult for ordinary laboratories to prepare or purchase such electrodes.
Disclosure of Invention
In view of the above-mentioned shortcomings of the prior art, the present invention provides an electrochemical method for determining nicotine content in tobacco and tobacco-related products, which can directly, simply, rapidly and accurately determine nicotine content in tobacco and tobacco-related products (tobacco leaves, cut stems, sheets, finished cigarettes, electronic cigarettes, buccal cigarettes, non-burning cigarettes and the like).
To achieve the above and other related objects, the present invention provides an electrochemical method for determining nicotine content in tobacco and tobacco-related products, comprising the steps of:
1) carrying out acidolysis on tobacco and tobacco related products, filtering, and adding an electrolyte into a filtrate to obtain a sample solution;
2) adding the nicotine standard sample into electrolyte to dilute and fix the volume to obtain standard solution;
3) dropwise adding acid into the selected electrode, and performing electrochemical treatment by adopting a cyclic voltammetry method to obtain a pretreated working electrode;
4) dropwise adding the sample solution obtained in the step 1) and the standard solution obtained in the step 2) onto the working electrode obtained in the step 3) for square wave voltammetry determination, and calculating the nicotine content in the sample solution by a standard curve method.
Preferably, in step 1), the tobacco and tobacco-related products are selected from one or more of tobacco leaves, cut stems, tobacco sheets, cigarettes, electronic cigarettes, buccal cigarettes or non-burning cigarettes by heating.
Preferably, in step 1), the tobacco and tobacco-related products are pulverized to a powder form.
Preferably, in the step 1), the acid solution used for acid hydrolysis is 0.5-1.5 v/v% acetic acid aqueous solution. The v/v% is the volume percentage concentration. More preferably, the acid solution used for the acid hydrolysis is a 1.0 v/v% aqueous acetic acid solution.
Preferably, in the step 1), the acidolysis time is 0.1-2 min. More preferably, the time for the acid hydrolysis is 0.5-1 min.
Preferably, in the step 1), the ratio of the mass mg added to the tobacco and the tobacco-related products to the volume m L added to the acid solution used for acid hydrolysis is 40-50: 4-5.
Preferably, in step 1), the filtration mode is membrane filtration. More preferably, the filter membrane used for the filter membrane filtration is a 0.45 μm filter membrane.
Preferably, in the step 1), the volume ratio of the filtrate to the electrolyte is 1: 0.5-1.5. More preferably, the volume ratio of the filtrate to electrolyte added is 1: 1.
Preferably, in the step 1) or 2), the electrolyte is 0.005-0.015 mol/L PBS buffer solution, and more preferably, the electrolyte is 0.01 mol/L PBS buffer solution.
The PBS buffer solution is KH2PO4、Na2HPO4·12H2Dissolving O, NaCl and KCl in water, and regulating pH to 7.4 with acid.
Preferably, in step 2), the nicotine standard sample is a nicotine standard stock solution with a concentration of 1000 μ g/g.
Preferably, in step 2), the concentration of nicotine in the standard solution is 10-200 μ g/g.
Preferably, in step 3), the selective electrode is a screen-printed gold electrode.
Preferably, in the step 3), the acid dripped by the optional electrode is 0.1-1.0 mol/L aqueous sulfuric acid solution, and more preferably, the acid dripped by the optional electrode is 0.1-1.0 mol/L aqueous sulfuric acid solution.
Preferably, in the step 3), the volume of the acid dropped by the selective electrode is 100-150 μ L, and more preferably, the volume of the acid dropped by the selective electrode is 120 μ L.
Preferably, in step 3), the measurement conditions of cyclic voltammetry are: the measuring voltage is-0.5-2.0V; the scanning speed is 40-60 mV/s; the scanning interval is 0.0005-0.0015V.
More preferably, the measurement conditions of the cyclic voltammetry are: the measuring voltage is-0.3-1.5V; the scanning speed is 50 mV/s; the scanning interval was 0.001V.
The pretreatment of the working electrode is completed when the measurement shows that a stable cyclic voltammogram can be obtained.
The Cyclic Voltammetry (Cyclic Voltammetry) is a common electrochemical research method, the method controls the potential of an electrode to be scanned repeatedly at different rates and in a triangular waveform once or for multiple times along with time, so that different reduction and oxidation reactions can alternately occur on the electrode, and a recorded current-potential curve is a Cyclic voltammogram, so that the micro-reaction process on the surface of the electrode can be effectively judged.
Preferably, in the step 4), the volumes of the sample solution and/or the standard solution dripped to the working electrode are both 100 and 150 mu L, and more preferably, the volumes of the sample solution and/or the standard solution dripped to the working electrode are both 120 mu L.
Preferably, in step 4), the measurement conditions of the square wave voltammetry are as follows: the measuring voltage is 0.4-1.0V; the amplitude is 20-30 mV; the frequency is 5-15 Hz; the sampling interval is 0.03-0.05V.
More preferably, the measurement conditions of the square wave voltammetry are: the measuring voltage is 0.5-0.9V; amplitude of 25 mV; the frequency is 10 Hz; the sampling interval was 0.04V.
The Square Wave Voltammetry (SWV) is a commonly used electroanalytical method, which can be applied to quantitative analysis of substances.
Preferably, in step 4), the standard curve method is: the method comprises the steps of respectively measuring a series of standard solutions containing nicotine with different concentrations by square wave voltammetry to obtain a linear relation between the nicotine concentration and a characteristic response current value in the standard solutions, drawing corresponding standard working curves by using the characteristic response current values of different nicotine corresponding to the corresponding concentrations, using the concentration of each standard solution as an abscissa and the corresponding characteristic response current value as an ordinate, and calculating to obtain a regression equation of the standard working curves. And then measuring the sample solution by square wave voltammetry to obtain the characteristic response current value of the nicotine in the sample solution, and substituting the characteristic response current value into the regression equation of the standard working curve to obtain the concentration of the nicotine in the sample solution.
As described above, the electrochemical method for determining nicotine content in tobacco and tobacco-related products provided by the present invention comprises the following steps: after the silk-screen printing gold electrode is pretreated, the sample solution and the standard solution are respectively measured by adopting a square wave voltammetry method, and the content of nicotine in the sample solution is calculated and obtained by a standard curve method according to the corresponding relation between the concentration and the characteristic response current value. Has the following beneficial effects:
(1) according to the electrochemical method for measuring the nicotine content in the tobacco and the tobacco related products, provided by the invention, the portable screen-printed gold electrode is selected as the working electrode, and the portable and quick nicotine electrochemical sensor is constructed by performing simple electrochemical pretreatment on the working electrode, so that the preparation process is simple, the electrode performance is stable, and the good reproducibility is realized.
(2) According to the electrochemical method for determining the nicotine content in the tobacco and the tobacco-related products, provided by the invention, the tobacco and the tobacco-related products are pretreated, so that the electrochemical detection can be directly performed on the nicotine content in the tobacco sample, the detection cost is low, the detection speed is high, and the detection accuracy is high.
Drawings
Fig. 1 shows the stable cyclic voltammogram obtained after pretreatment of the screen printed gold electrode in the present invention.
Fig. 2 shows the square wave voltammogram of the screen-printed gold electrode in the invention for detecting nicotine standard solutions with different concentrations.
Fig. 3 is a linear fitting graph showing the detection of nicotine standard solutions with different concentrations by the screen-printed gold electrode in the present invention.
Detailed Description
The present invention is further illustrated below with reference to specific examples, which are intended to be illustrative only and not to limit the scope of the invention.
The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention.
It should be understood that the processing equipment or devices not specifically mentioned in the following examples are conventional in the art; all pressure values and ranges refer to relative pressures.
Furthermore, it is to be understood that one or more method steps mentioned in the present invention does not exclude that other method steps may also be present before or after the combined steps or that other method steps may also be inserted between these explicitly mentioned steps, unless otherwise indicated; it is also to be understood that a combined connection between one or more devices/apparatus as referred to in the present application does not exclude that further devices/apparatus may be present before or after the combined device/apparatus or that further devices/apparatus may be interposed between two devices/apparatus explicitly referred to, unless otherwise indicated. Moreover, unless otherwise indicated, the numbering of the various method steps is merely a convenient tool for identifying the various method steps, and is not intended to limit the order in which the method steps are arranged or the scope of the invention in which the invention may be practiced, and changes or modifications in the relative relationship may be made without substantially changing the technical content.
In the examples of the present invention, the reagents and instruments used were as follows:
1. reagent
Tobacco leaves, tobacco stem shreds, tobacco sheets, cigarettes, electronic cigarettes, buccal cigarettes or heating non-burning cigarettes (produced by Shanghai tobacco company); acetic acid, KH2PO4、Na2HPO4·12H2O, NaCl, KCl, sulfuric acid and hydrochloric acid (analytically pure, Shanghai national drug group chemical reagent Co., Ltd.); nicotine standards (1000 μ g/g, Sigma, usa); pure water (made by a water purifier).
2. Instrument for measuring the position of a moving object
DS 220AT screen printed gold electrodes (china ltd, wangton, switzerland); CHI660E square wave voltammetry analysis apparatus (shanghai chenhua instruments ltd); HP6890 type gas chromatography-mass spectrometry GC-MS (Agilent science and technology, China, Inc.).
The analysis process of the electrochemical method for determining the nicotine content in the tobacco and the tobacco related products is as follows.
The method comprises the steps of crushing tobacco and tobacco related products into powder, wherein the tobacco and the tobacco related products are selected from one or more of tobacco leaves, tobacco stem shreds, tobacco sheets, cigarettes, electronic cigarettes, buccal cigarettes or heated non-burning cigarettes, dissolving the tobacco and the tobacco related products in 0.5-1.5 v/v% acetic acid aqueous solution for 0.1-2min, preferably 0.5-1min, wherein the ratio of the mass mg of the tobacco and the tobacco related products to the volume m L of acid liquor used for acidolysis is 40-50: 4-5, filtering the solution by using a 0.45 mu m filter membrane, adding 0.005-0.015 mol/L of PBS buffer solution into the filtrate, and obtaining a sample solution, wherein the volume ratio of the filtrate to the electrolyte is 1: 0.5-1.5.
Taking a nicotine standard stock solution with the concentration of 1000 mug/g as a nicotine standard sample, adding 0.005-0.015 mol/L PBS buffer solution for diluting to a constant volume to obtain a standard solution, wherein the concentration of nicotine in the standard solution is 10-200 mug/g.
The PBS buffer solution is KH2PO4、Na2HPO4·12H2Dissolving O, NaCl and KCl in water, and regulating pH to 7.4 with acid.
Selecting a screen printing gold electrode as an electrode, dripping 0.1-1.0 mol/L of sulfuric acid aqueous solution with the volume of 100-150 mu L, and carrying out electrochemical treatment under the conditions of measuring voltage of-0.5-2.0V, scanning speed of 40-60mV/s and scanning interval of 0.0005-0.0015V by adopting a cyclic voltammetry method, wherein as shown in figure 1, when the measurement finds that a stable cyclic voltammogram can be obtained, the electrochemical treatment is finished, and a pretreated working electrode is obtained.
Respectively dropping 100-150 mu L of the obtained sample solution and standard solution onto a working electrode, carrying out square wave voltammetry measurement under the measurement voltage of 0.4-1.0V, the amplitude of 20-30mV, the frequency of 5-15Hz and the sampling interval of 0.03-0.05V, drawing a corresponding standard working curve by using the characteristic response current values of different nicotine corresponding to the corresponding concentrations thereof through a standard curve method, using the concentration of each standard solution as a horizontal coordinate and the corresponding characteristic response current value as a vertical coordinate, and calculating to obtain a regression equation of the standard working curve.
Example 1
Crushing 40mg of tobacco leaves into powder, dissolving the powder by using 5m L1.0 v/v% acetic acid aqueous solution for 1min, then filtering the powder by using a 0.45 mu m filter membrane, putting 2m L filtrate into a centrifuge tube, adding 0.01 mol/L PBS buffer solution, and uniformly mixing to obtain a sample solution No. 1, wherein the volume ratio of the filtrate to the electrolyte is 1: 1.
Taking a nicotine standard stock solution with the concentration of 1000 mu g/g as a nicotine standard sample, adding 0.01 mol/L PBS buffer solution for diluting and fixing the volume to obtain a series of standard solutions with different concentrations, wherein the concentrations of nicotine in the standard solutions are respectively 10 mu g/g, 20 mu g/g, 40 mu g/g, 60 mu g/g, 80 mu g/g, 100 mu g/g, 120 mu g/g, 150 mu g/g, 180 mu g/g and 200 mu g/g.
The PBS buffer solution is prepared by weighing 0.135g KH2PO4、0.71g Na2HPO4·12H2O, 4g NaCl and 0.1g KCl, adding 400m L deionized water, fully stirring and dissolving, adding concentrated hydrochloric acid to adjust the pH value to 7.4, and adding deionized water to a constant volume of 500m L and shaking up to obtain the product.
Selecting a screen printing gold electrode as an electrode, dripping 0.5 mol/L aqueous solution of sulfuric acid with the volume of 120 mu L, performing electrochemical treatment by adopting cyclic voltammetry at-0.3-1.5V, the scanning speed of 50mV/s and the scanning interval of 0.0001V, and finishing when the measurement finds that a stable cyclic voltammogram can be obtained as shown in figure 1 to obtain a pretreated working electrode.
After a series of standard solutions with different concentrations are tested, as shown in figure 2, a series of square wave voltammetry curves are sequentially obtained by sequentially detecting according to the sequence from low concentration to high concentration, and a corresponding standard working curve is drawn by a standard curve method according to the characteristic response current values of different nicotine corresponding to the corresponding concentrations, taking the concentration of each standard solution as an abscissa and the corresponding characteristic response current value as an ordinate, and a regression equation of the standard working curve is obtained by calculation, wherein the specific data is shown in table 1 and figure 3.
And then the sample solution 1# is subjected to square wave voltammetry measurement to obtain the characteristic response current value of the nicotine in the sample solution 1# and the characteristic response current value is substituted into the regression equation of the standard working curve to obtain the content of the nicotine in the sample solution 1# of 23338.8 mug/g.
Example 2
A series of standard solutions of different concentrations were prepared as in example 1 and measured by square wave voltammetry as described above in example 1,and calculating to obtain a regression equation, a correlation coefficient and a linear range of the standard working curve, wherein specific data are shown in a table 1. As can be seen from Table 1, the regression equation of the standard working curve has a good linear relationship in a certain linear range by taking the concentration of each standard solution as the abscissa x and the corresponding characteristic response current value as the ordinate y, and the correlation coefficient R of the standard regression equation is2Not less than 0.998.
TABLE 1
Compound (I) | Standard curve | R2 | Linear Range (μ g/g) |
Nicotine | y=-1.68+0.41ln(x+91.53) | 0.998 | 10-200 |
ln is a log function based on e
Comparative example 1
Measuring the content of nicotine in tobacco leaves by adopting a GC-MS method, taking a 200mg tobacco leaf powder sample, adding 100 mu L internal standard substance n-hexadecane, adding 2.5M L0.1.1M sodium hydroxide and 5M L methyl tert-butyl ether according to a Coresta recommended method, oscillating for a period of time, standing for 24h, taking supernatant for sample injection, and obtaining the content of nicotine in the tobacco leaf sample of 20305.2 mu g/g according to a working curve of gas chromatography.
Example 3
Comparing the nicotine content in the tobacco samples of example 1 and comparative example 1, it can be found that the nicotine content is relatively close to that of the tobacco samples, which indicates that the accuracy of the determination method of the invention is good. Meanwhile, compared with comparative example 1, the detection time of example 1 is short, and is only 30 s; the method does not need to use expensive GC-MS, and has low detection cost.
Example 4
Tobacco leaf samples were selected for 6 replicates according to the measurement procedure in example 1 to obtain a Relative Standard Deviation (RSD) of 3.11%, and the specific results are shown in table 2. As can be seen from table 2, the Relative Standard Deviation (RSD) of nicotine in the tobacco samples was below 3.77%, indicating that the reproducibility of the method was good.
TABLE 2
Name of Chinese | 1 | 2 | 3 | 4 | 5 | 6 | RSD(%) |
Nicotine | 3.77 | 3.37 | 3.81 | 2.78 | 2.33 | 2.61 | 3.11 |
Therefore, the invention effectively overcomes various defects in the prior art and has high industrial utilization value.
The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.
Claims (10)
1. An electrochemical method for determining nicotine content in tobacco and tobacco-related products, comprising the steps of:
1) carrying out acidolysis on tobacco and tobacco related products, filtering, and adding an electrolyte into a filtrate to obtain a sample solution;
2) adding the nicotine standard sample into electrolyte to dilute and fix the volume to obtain standard solution;
3) dropwise adding acid into the selected electrode, and performing electrochemical treatment by adopting a cyclic voltammetry method to obtain a pretreated working electrode;
4) dropwise adding the sample solution obtained in the step 1) and the standard solution obtained in the step 2) onto the working electrode obtained in the step 3) for square wave voltammetry determination, and calculating the nicotine content in the sample solution by a standard curve method.
2. The electrochemical method for determining the nicotine content in tobacco and tobacco-related products according to claim 1, wherein in step 1), the tobacco and tobacco-related products are selected from one or more of tobacco leaves, cut stems, tobacco sheets, cigarettes, electronic cigarettes, buccal cigarettes or non-burning cigarettes after heating; the tobacco and tobacco-related products are pulverized to a powder form.
3. The electrochemical method for determining nicotine content in tobacco and tobacco-related products as claimed in claim 1, wherein in step 1), the acid hydrolysis comprises any one or more of the following conditions:
A1) the acid solution adopted for acidolysis is 0.5-1.5 v/v% acetic acid aqueous solution;
A2) the acidolysis time is 0.1-2 min;
A3) the ratio of the added mass of the tobacco and the related tobacco products to the added volume of the acid liquor used for acid hydrolysis is 40-50: 4-5, mg/m L.
4. The electrochemical method for determining nicotine content in tobacco and tobacco-related products according to claim 1, wherein in step 1), the volume ratio of the filtrate to the electrolyte is 1: 0.5-1.5.
5. The electrochemical method for determining nicotine content in tobacco and tobacco-related products according to claim 1, wherein in step 1) or 2), the electrolyte is 0.005-0.015 mol/L PBS buffer solution.
6. The electrochemical method for determining nicotine content in tobacco and tobacco-related products according to claim 1, wherein in step 3), the selective electrode is a screen-printed gold electrode.
7. The electrochemical method for determining nicotine content in tobacco and tobacco-related products as claimed in claim 1, wherein in step 3), the acid dropped from the selective electrode is 0.1-1.0 mol/L of sulfuric acid solution, and the volume of the acid dropped from the selective electrode is 100 μ L.
8. The electrochemical method for determining nicotine content in tobacco and tobacco-related products according to claim 1, wherein in step 3), the measurement conditions of cyclic voltammetry are as follows: the measuring voltage is-0.5-2.0V; the scanning speed is 40-60 mV/s; the scanning interval is 0.0005-0.0015V.
9. The electrochemical method for determining nicotine content in tobacco and tobacco-related products as claimed in claim 1, wherein the volume of the sample solution and/or the standard solution added to the working electrode in step 4) is 150 μ L and 100 μ.
10. The electrochemical method for determining nicotine content in tobacco and tobacco-related products according to claim 1, wherein in step 4), the square wave voltammetry is performed under the following conditions: the measuring voltage is 0.4-1.0V; the amplitude is 20-30 mV; the frequency is 5-15 Hz; the sampling interval is 0.03-0.05V.
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