CN113567529B - Gas-phase nicotine electrochemical determination method based on passive sampling method - Google Patents
Gas-phase nicotine electrochemical determination method based on passive sampling method Download PDFInfo
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Abstract
The invention provides a gas-phase nicotine electrochemical determination method based on a passive sampling method, which comprises the steps of selecting a screen printing gold electrode, adopting a sulfuric acid solution to electrochemically pretreat the electrode, selecting a handheld portable electrochemical workstation to construct a portable nicotine electrochemical sensor, and connecting the gas-phase passive sampler with an electrochemical detection device; the device is placed in a closed box and exposed to smoke environments with different concentrations, square wave voltammetry is adopted to detect in a voltage range of 0.5V-0.9V, and a characteristic response current value of nicotine is obtained; detecting an actual tobacco sample according to the method to obtain a nicotine response current value, and substituting the response current value into a standard curve and a corresponding linear regression equation to obtain the concentration of nicotine in the sample. The method is simple and convenient to operate, low in detection cost, and free of complicated sample pretreatment separation, and realizes direct detection of nicotine. The abstract drawing is a schematic drawing for detecting nicotine.
Description
Technical Field
The invention relates to the technical field of electrochemical analysis and detection, in particular to an electrochemical method for measuring nicotine concentration in smoke.
Background
Tobacco is a special cash crop with a long history and is widely planted in the united states, china, india, brazil, copa, etc. The total yield and total area of tobacco planting in China and the production of cigarettes are the first place in the world, and become an important consumer product and tax source in China. Smoking is a major concern worldwide, minimizing the harm caused by smoking, and retaining the unique aroma and taste of tobacco is two directions of current development of the tobacco industry.
Nicotine (also called as Nicotine (1-methyl-2 (3-pyridyl) pyrrolidine), abbreviated as NCT, the content of the Nicotine in tobacco is about 1% -2%, the Nicotine is a main alkaloid in tobacco, the Nicotine is an unpleasant, bitter and light yellow oily liquid at normal temperature, the Nicotine is easily oxidized into dark gray after long-term placement under light, and the Nicotine can be rapidly dissolved in organic solvents such as ethanol, diethyl ether, chloroform and the like, and can be dissolved in water.
The nicotine can make the autonomic nerve and central nervous system of smoker feel the excitation effect, so that the nicotine is related to smoking addiction, and the content of the nicotine is directly related to the use experience and satisfaction of smoker, and is also related to human health and environmental hazard. With increasing attention to smoking harm to human health, quantitative detection of nicotine content is also a focus of attention. Therefore, the research and concentration control of the nicotine in the tobacco are of great significance for tobacco quality, economic value of the tobacco and tar and harm reduction.
The national tobacco country is one of major causes of indoor environmental pollution, and the number of people suffering from second-hand smoke is more than 5.4 hundred million at present, which attracts great attention. After the tobacco control framework convention in 1 month 2006 takes effect in China, a large amount of tobacco control work is developed successively, and the second-hand tobacco exposure condition is improved, but the smoke is still quite far away from all indoor workplaces and indoor public places specified in the convention, and the lack of a sampling and detecting method of tobacco smoke in the ambient air is an important reason.
Because of the complex composition of ETS, it is generally necessary to determine the pollution of ETS to indoor environment by measuring nicotine, which is a specific marker, and a high-efficiency sampling method and a high-sensitivity detection method are required, and the research work in this respect is still not perfected.
In the last twenty years, researchers have developed a number of methods for measuring NCT, such as raman spectroscopy, liquid chromatography, high performance liquid chromatography electrochemical (HPLC-EC), gas chromatography-mass spectrometry (GC-MS), titration, gravimetric, chemiluminescent, and the like.
Raman spectroscopy is simple and rapid for measuring nicotine, but is influenced by the limitations of sensitivity and accuracy of the method, the bandwidth, the wavelength selectivity, the range, impurities and the like, and is easy to cause the deviation of measurement results, and research work in the late 80 s uk shows that the measurement results when the nicotine is measured by using a spectrometer are lower than actual values (Itoh et al, high dilution surface-enhanced Raman spectroscopy for rapid determination of nicotine in e-liquids for electronic cigarettes.analysis, 2017,142 (6): 994-998);
liquid chromatography and gas chromatography-mass spectrometry are commonly used in the industry at present, and have the advantage of high detection precision, but the required instrument is expensive, the operation is complex, derivatization treatment of reagents is required before analysis, the required test time is long, and the on-site rapid detection of a sample is not facilitated (Nagarnaik et al, A study of validation and uncertainty in real samples of nicotine polacrilex gum by reverse phase HPLC.Asian J.Pharmiceut Anal.2014, 4:156-161);
the electrochemical method has been increasingly used for qualitative and quantitative detection of nicotine by virtue of the remarkable characteristics of high sensitivity, quick response, simple operation, small sample requirement, microminiaturization, low price, on-site online detection and analysis and the like.
For example, suffretini et al (Electrochemical behavior of nicotine studied by voltammetric techniques at boron-doped diamond electrodes. Anal. Lett.2005,38 (10): 1587-1599) originally proposed the use of boron doped diamond electrodes for the detection of nicotine at a detection potential of +1.30V (vs. Ag/AgCl) and achieved a good linear range;
stoces et al
Nicotine was detected using a carbon paste electrode, electrochemical behavior of nicotine at unmodified carbon paste electrode and its determination in a set of refilling liquids for electronic cigarettes.electrotechnical.2014, 26:2655-2663, further lowering the detection potential to +0.95V (vs. ag/AgCl).
However, the method of modifying the electrode has high cost, and the common laboratory is difficult to prepare or purchase the electrode, so that an electrochemical method for testing the nicotine concentration of tobacco leaves with low price, strong operability and accurate results needs to be developed.
Disclosure of Invention
Aiming at the problems in the prior art, the application provides a gas-phase nicotine electrochemical determination method based on a passive sampling method, which has the advantages of simple operation, low price, high selectivity, high analysis speed and the like, and the detection result has good accuracy compared with the traditional method.
The technical scheme of the invention is as follows:
the electrochemical gas-phase nicotine measuring method based on the passive sampling method comprises the following specific steps:
(1) Pretreatment of a working electrode:
selecting screen printing gold electrode, dripping 120 mu L H of 0.5mol/L 2 SO 4 Carrying out cyclic voltammetry electrochemical treatment on the solution at-0.3V-1.5V until a stable cyclic voltammogram is obtained;
(2) Drawing a standard curve:
preparing solutions containing nicotine with different concentrations in 0.01mol/L PBS buffer solution, and respectively dripping 120 mu L of standard solution on the electrode pretreated in the step (1) as nicotine standard solution;
detecting a series of nicotine standard solutions with different concentrations in a voltage range of 0.5V-0.9V by adopting square wave voltammetry to obtain a characteristic response current value of nicotine;
under the same test condition, sequentially recording characteristic response current values corresponding to the concentration of each standard solution, drawing a standard curve, and obtaining a corresponding linear regression equation through fitting the curve;
(3) Determination of tobacco samples:
and (3) placing the gas phase passive sampler and the connection in a closed box, exposing the gas phase passive sampler and the connection to smoke environments with different concentrations, and detecting the gas phase passive sampler and the connection in a voltage range of 0.5V-0.9V by adopting a square wave voltammetry method to obtain a characteristic response current value of nicotine.
Preferably, the screen-printed gold electrode in step (1) is SPE standard size, and has a diameter of 5 mm to 1 cm.
Preferably, the preparation method of the 0.01mol/L PBS buffer solution in the step (2) comprises the following steps: weighing 0.135g KH 2 PO 4 、0.71g Na 2 HPO 4 ·12H 2 Adding 400mL of deionized water into 0.1g of KCl, fully stirring and dissolving, adding concentrated hydrochloric acid to adjust the pH to 7.4, and using deionized water to fix the volume to 500mL to obtain 0.01mol/L PBS buffer solution;
preferably, the concentration of the nicotine standard solution in step (2) is 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, 200. Mu.g/g, respectively.
Step (2)) The linear regression equation is R 2 =0.998, voltage range 0.5V-0.9V, sampling interval 0.04V.
The application also provides a nicotine electrochemical sensor based on the determination method, which comprises a gas phase passive sampler and an electrochemical detection device; wherein the gas phase passive sampler and the electrochemical detection device are conventional test instruments in the field.
Preferably, the electrochemical detection device may use a hand-held portable electrochemical workstation.
Preferably, the gas phase passive sampler is a sealed space with openings at the front end and the rear end, wherein the openings at the front end receive smoke containing nicotine, and the openings at the rear end are inserted into the electrochemical detection device for pretreatment and are used for selecting screen printing gold electrodes;
the gas phase passive sampler is arranged in parallel from the front end opening to the back one time: front cover, osmotic membrane, gasket, hydrogel sheet, collet, hydrogel enriched with nicotine, mechanical arm, and bearing.
The beneficial technical effects of the invention are as follows:
the invention provides an electrochemical method for simply and rapidly determining the concentration of nicotine in tobacco leaves, and in order to achieve the purposes, the inventor selects a portable screen printing electrode, and realizes the specific response to the nicotine and the direct detection of the nicotine in tobacco samples through a simple electrochemical pretreatment method. Up to now, electrochemical methods for rapidly determining nicotine in tobacco have not been reported.
The invention designs and constructs the portable and rapid nicotine electrochemical sensor based on the electrochemical technology, has simple preparation process, stable electrode performance and good reproducibility, can directly carry out electrochemical detection on nicotine in a tobacco sample by preprocessing the tobacco sample, and has high analysis speed and low detection cost.
Drawings
Figure 1 is a schematic diagram of a nicotine electrochemical sensor of the present invention.
FIG. 2 shows the detection of different concentrations by gold electrodes when exposed to different concentrations of ambient smokeSquare wave voltammetric curve of degree nicotine, upper right corner inset is fitted curve of response current and corresponding concentration, R 2 ＝0.998。
Detailed Description
The present invention will be described in detail below with reference to the drawings and examples. It will be apparent that the described embodiments are only some, but not all, embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Example 1: the gas-phase nicotine electrochemical determination method based on the passive sampling method comprises the following specific steps:
(1) Pretreatment of a working electrode:
selecting screen printing gold electrode, dripping 120 mu L H of 0.5mol/L 2 SO 4 Carrying out cyclic voltammetry electrochemical treatment on the solution at-0.3V-1.5V until a stable cyclic voltammogram is obtained; the screen printing gold electrode adopts SPE standard size, and the diameter is 5 mm to 1 cm.
(2) Drawing a standard curve:
0.01mol/L PBS buffer solution is prepared: weighing 0.135g KH 2 PO 4 、0.71g Na 2 HPO 4 ·12H 2 Adding 400mL of deionized water into 0.1g of KCl, fully stirring and dissolving, adding concentrated hydrochloric acid to adjust the pH to 7.4, and using deionized water to fix the volume to 500mL to obtain 0.01mol/L PBS buffer solution;
preparing solutions containing nicotine with different concentrations in 0.01mol/L PBS buffer solution, and respectively dripping 120 mu L of standard solution on the electrode pretreated in the step (1) as nicotine standard solution; the concentration of the nicotine standard solution was 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, 200. Mu.g/g, respectively.
Detecting a series of nicotine standard solutions with different concentrations in a voltage range of 0.5V-0.9V by adopting square wave voltammetry to obtain a characteristic response current value of nicotine;
in the same test stripUnder the condition, characteristic response current values corresponding to the concentration of each standard solution are recorded in sequence, a standard curve is drawn, and a corresponding linear regression equation R is obtained through fitting the curve 2 =0.998, the voltage range is 0.5V-0.9V, the sampling interval is 0.04V, as shown in fig. 2.
(3) Determination of tobacco samples:
and (3) placing the gas phase passive sampler and the connection in a closed box, exposing the gas phase passive sampler and the connection to smoke environments with different concentrations, and detecting the gas phase passive sampler and the connection in a voltage range of 0.5V-0.9V by adopting a square wave voltammetry method to obtain a characteristic response current value of nicotine.
Example 2: construction of a portable and rapid nicotine electrochemical sensor
As shown in fig. 1, a hand-held portable electrochemical workstation and a gas phase passive sampler are connected, wherein the gas phase passive sampler is a sealed space with openings at the front end and the rear end, the opening at the front end receives experimental smoke containing nicotine, and a pretreated screen printing gold electrode is inserted into the opening at the rear end of the hand-held portable electrochemical workstation;
the gas phase passive sampler is arranged in parallel from the front end opening to the back one time: front cover, osmotic membrane, gasket, hydrogel sheet, collet, hydrogel enriched with nicotine, mechanical arm, and bearing.
Test example: the sensor prepared in example 2 was subjected to an actual nicotine flue gas concentration test, the test limit was 10.3ppm, and the recovery was 102% -113%.
Although the embodiments of the present invention have been disclosed in the foregoing description and drawings, it is not limited to the details of the embodiments and examples, but is to be applied to all the fields of application of the present invention, it will be apparent to those skilled in the art that various changes, modifications, substitutions and alterations can be made therein without departing from the spirit and scope of the invention as defined by the appended claims and their equivalents.
Claims (5)
1. The gas-phase nicotine electrochemical determination method based on the passive sampling method is characterized by comprising the following specific steps of:
(1) Pretreatment of a working electrode:
selecting screen printing gold electrode, dripping 120 mu L H of 0.5mol/L 2 SO 4 Carrying out cyclic voltammetry electrochemical treatment on the solution at-0.3V-1.5V until a stable cyclic voltammogram is obtained;
(2) Drawing a standard curve:
preparing solutions containing nicotine with different concentrations in 0.01 mol/LPBS buffer solution, and respectively dripping 120 mu L of standard solution on the electrode pretreated in the step (1) as the nicotine standard solution;
detecting a series of nicotine standard solutions with different concentrations in a voltage range of 0.5V-0.9V by adopting square wave voltammetry to obtain a characteristic response current value of nicotine;
under the same test condition, sequentially recording characteristic response current values corresponding to the concentration of each standard solution, drawing a standard curve, and obtaining a corresponding linear regression equation through fitting the curve;
(3) Determination of tobacco samples:
the gas phase passive sampler and the electrochemical detection device are connected, are placed in a closed box and are exposed to smoke environments with different concentrations, and are detected in a voltage range of 0.5V-0.9V by adopting square wave voltammetry to obtain a characteristic response current value of nicotine;
the gas phase passive sampler is a sealed space with openings at the front end and the rear end, wherein the openings at the front end receive smoke containing nicotine, and the openings at the rear end are inserted into a pretreated screen printing gold electrode in the electrochemical detection device;
the gas phase passive sampler is sequentially arranged in parallel from the front end opening to the rear: front cover, osmotic membrane, gasket, hydrogel piece, collet, arm, bearing.
2. The method of claim 1, wherein the screen-printed gold electrode of step (1) is SPE standard size, 5 mm to 1 cm in diameter.
3. The method according to claim 1, wherein the method for preparing the 0.01mol/L PBS buffer solution in the step (2) comprises the steps of: weighing 0.135g KH 2 PO 4 、0.71g Na 2 HPO 4 ·12H 2 O, 4g NaCl and 0.1g KCl are added with 400mL deionized water, fully stirred and dissolved, concentrated hydrochloric acid is added to adjust the pH value to 7.4, deionized water is used for constant volume to 500mL, and a PBS buffer solution of 0.01mol/L is obtained.
4. The assay according to claim 1, wherein the concentration of the nicotine standard solution of step (2) is 10 μg/g, 20 μg/g, 40 μg/g, 60 μg/g, 80 μg/g, 100 μg/g, 120 μg/g, 150 μg/g, 180 μg/g, 200 μg/g, respectively.
5. The method according to claim 1, wherein the linear regression equation in the step (2) is R 2 =0.998, voltage range 0.5V-0.9V, sampling interval 0.04V.
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