Tracing method for tobacco leaf producing areas of different countries based on strontium-lead isotope ratio and mineral element fingerprints

Abstract

The invention provides a method for tracing tobacco producing areas of different countries based on a strontium-lead isotope ratio and mineral element fingerprints, which comprises the following steps of: firstly, pretreating tobacco leaves to obtain tobacco powder, and then detecting mineral element content and metal element isotope content of a tobacco powder sample; and finally, determining the producing areas of the tobacco leaves in different countries based on the discrimination function and the discrimination method. Through verification, the method has the advantages that the prediction accuracy of the tobacco leaf producing areas of the countries such as Argentina, Brazil, Zimbabwe, America and Sapabia is 100%, and the tobacco leaf producing areas of different countries can be effectively traced. The method for tracing the tobacco leaf producing areas of different countries based on the strontium-lead isotope ratio and the mineral element fingerprints is reliable in result and can be widely applied to actual life.

Description

Technical Field

[0001] The invention relates to a tobacco leaf component analysis method, and in particular to a tobacco leaf origin tracing method in different countries based on strontium-lead isotope ratios and mineral element fingerprints. Background Art

[0002] Tobacco is an important economic crop in the world. Its quality is closely related to genetic factors, cultivation measures, curing technology, soil and climate conditions of the origin, among which the origin effect of soil and climate conditions has a significant impact on the quality of tobacco. The false origin of tobacco is one of the main forms of cigarette counterfeiting.

[0003] Isotope ratio characteristics generally do not change due to chemical and physical changes, and are an effective indicator for determining the origin of animal and plant products. In view of this, the present invention achieves the traceability of different tobacco production areas at home and abroad by finding metal isotopes and mineral element fingerprints that characterize regional characteristics.

[0004] In order to solve the above problems, the present invention is proposed. Summary of the invention

[0005] In view of the above shortcomings, the present invention provides a method for tracing the origin of tobacco leaves in different countries based on strontium-lead isotope ratios and mineral element fingerprints. First, the tobacco leaves are pre-treated to obtain tobacco dust, and then the tobacco dust samples are tested for mineral element content and metal element isotope content. Finally, the origin of tobacco leaves in different countries is determined based on the discriminant function and the discriminant method of the present invention. It has been verified that the method of the present invention has a 100% prediction accuracy for the origin of tobacco leaves in Argentina, Brazil, Zimbabwe, the United States, Zambia and China, and can effectively trace the origin of tobacco leaves in different countries. The method of tracing the origin of tobacco leaves in different countries based on strontium-lead isotope ratios and mineral element fingerprints of the present invention is reliable and can be widely used in real life.

[0006] The purpose of the present invention is achieved through the following technical solutions.

[0007] The present invention provides a method for tracing the origin of tobacco leaves in different countries based on strontium-lead isotope ratios and mineral element fingerprints, which comprises the following steps:

[0008] Step (1): pre-treating the tobacco leaves, grinding the sample tobacco leaves by using a cyclone mill until the powder particle size is less than 40 meshes, and obtaining tobacco powder;

[0009] Step (2): Detection of mineral element content: the tobacco powder obtained in step (1) is analyzed for mineral element content using standard method YC / T 380-2010 "Determination of chromium, nickel, arsenic, selenium, cadmium and lead in tobacco and tobacco products - Inductively coupled plasma mass spectrometry";

[0010] Step (3): Detection of metal element isotope content: the smoke dust obtained in step (1) is analyzed for strontium and lead isotope content using the standard method GB / T 17672-1999 "Determination of lead, strontium and neodymium isotopes in rocks";

[0011] Step (4): determine the origin of tobacco leaves from different countries based on the following discriminant function:

[0012] Oarg=28.288X1-3.708X2+87.133X3+33.708X4+170.098X5-144.816X6+57461.043X7+21926.29X8-3880.732X9-156198.966;

[0013] Obr=28.227X1-3.597X2+81.982X3+33.702X4+170.21X5-145.781X6+57441.36X7+21864.961X8-3868.292X9-155454.98;

[0014] Ozw=29.283X1-3.637X2+87.466X3+34.24X4+172.58X5-147.953X6+59063.574X7+22157.672X8-3908.523X9-160517.669;

[0015] Ous=28.364X1-3.411X2+85.833X3+32.896X4+169.258X5-145.185X6+57222.249X7+21854.72X8-3865.97X9-155189.094;

[0016] Oza=27.952X1-3.795X2+79.718X3+34.519X4+171.664X5-147.478X6+58924.132X7+21950.363X8-3884.012X9-157574.881;

[0017] Ocn=29.015X1-3.657X2+80.827X3+35.149X4+173.317X5-144.015X6+57584.022X7+21983.502X8-3890.509X9-157015.224;

[0018] Wherein: X1 is the Cu content mg / kg, X2 is the Zn content mg / kg, X3 is the Cr content mg / kg, X4 is the Ni content mg / kg, X5 is the Cd content mg / kg, X6 is the Pb content mg / kg, X7 is the ratio of 87Sr / 86Sr, X8 is the ratio of 207Pb / 204Pb, and X9 is the ratio of 206Pb / 204Pb;

[0019] The discrimination method is to treat the element content and isotope ratio measured corresponding to step (2) and step (3) with the above-mentioned six discrimination functions, and compare the numerical values ​​of the six functions. If Oarg is the largest, the tobacco leaves are produced in Argentina; if Obr is the largest, the tobacco leaves are produced in Brazil; if Ozw is the largest, the tobacco leaves are produced in Zimbabwe; if Ous is the largest, the tobacco leaves are produced in the United States; if Oza is the largest, the tobacco leaves are produced in Zambia; and if Ocn is the largest, the tobacco leaves are produced in China.

[0020] Preferably, the specific analysis conditions in step (3) are as follows: weigh 0.5g of tobacco powder into a quartz beaker, add 2mL of concentrated nitric acid to dissolve overnight, evaporate to dryness, place in a muffle furnace and burn at 250°C for 2h, 550°C for 4h, add 1mL of concentrated nitric acid three times to dissolve, transfer to a Teflon sample dissolving tank, evaporate to dryness for testing. The separation and purification of strontium and lead are completed by means of AG50W-X8 cation exchange resin and AG1-X8 anion exchange resin, respectively, and the background of the whole process is 50-100pg and 100-200pg, respectively.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1. The present invention realizes the accurate identification of tobacco leaves from different origins at home and abroad for the first time through isotope and mineral element fingerprints.

[0023] 2. The present invention is the first to construct fingerprints of mineral elements and isotopes of tobacco leaves from different origins at home and abroad. It only needs to substitute the values ​​of X1 (Cu content mg / kg), X2 (Zn content mg / kg, X3 (Cr content mg / kg), X4 (Ni content mg / kg), X5 (Cd content mg / kg), X6 (Pb content mg / kg), X7 (87Sr / 86Sr ratio), X8 (207Pb / 204Pb ratio), and X9 (206Pb / 204Pb ratio) into the six discriminant equations of step (4). The origin corresponding to the largest value is the origin of the tobacco leaves. The traceability method of the present invention is simple and the results are reliable, and can be widely used in real life. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Example 1 Three-dimensional score graph of the discriminant function of tobacco leaf samples. DETAILED DESCRIPTION

[0025] The present invention is described below in conjunction with specific examples, but the embodiments of the present invention are not limited thereto. Experimental methods without specific conditions in the examples are usually carried out under conventional conditions and conditions described in the manual, or under conditions recommended by the manufacturer. The general equipment, materials, reagents, etc. used can be obtained from commercial channels unless otherwise specified.

[0026] Example 1

[0027] The 81 tobacco leaf samples were first-cured tobacco and re-cured strip tobacco collected from home and abroad, including 12 from Argentina, 10 from Brazil, 17 from Zimbabwe, 6 from the United States, 8 from Zambia and 28 from China. The sample tobacco leaves were pulverized with a cyclone mill until the powder particle size was less than 40 mesh.

[0028] The mineral element content of tobacco dust was analyzed using the standard method YC / T 380-2010 “Determination of chromium, nickel, arsenic, selenium, cadmium and lead in tobacco and tobacco products by inductively coupled plasma mass spectrometry”.

[0029] The standard method GB / T 17672-1999 “Determination of lead, strontium and neodymium isotopes in rocks” was used to analyze the strontium and lead isotope contents in cigarette smoke.

[0030] The nine mineral elements, including Cu, Zn, Co, Cr, Ni, As, Se, Cd and Pb, and four strontium and lead isotopes, including 87Sr / 86Sr, 208Pb / 204Pb, 207Pb / 204Pb, and 206Pb / 204Pb, in tobacco leaves were imported into the software. Fisher stepwise discriminant analysis was performed through the equality test of group means, covariance matrix, step statistics, eigenvalues ​​and their tests, and finally the discriminant function of tobacco origin in six countries was constructed:

[0031] Oarg=28.288X1-3.708X2+87.133X3+33.708X4+170.098X5-144.816X6+57461.043X7+21926.29X8-3880.732X9-156198.966;

[0032] Obr=28.227X1-3.597X2+81.982X3+33.702X4+170.21X5-145.781X6+57441.36X7+21864.961X8-3868.292X9-155454.98;

[0033] Ozw=29.283X1-3.637X2+87.466X3+34.24X4+172.58X5-147.953X6+59063.574X7+22157.672X8-3908.523X9-160517.669;

[0034] Ous=28.364X1-3.411X2+85.833X3+32.896X4+169.258X5-145.185X6+57222.249X7+21854.72X8-3865.97X9-155189.094;

[0035] Oza=27.952X1-3.795X2+79.718X3+34.519X4+171.664X5-147.478X6+58924.132X7+21950.363X8-3884.012X9-157574.881;

[0036] Ocn=29.015X1-3.657X2+80.827X3+35.149X4+173.317X5-144.015X6+57584.022X7+21983.502X8-3890.509X9-157015.224;

[0037] The Cu, Zn, Cr, Ni, Cd, Pb, 87Sr / 86Sr, 207Pb / 204Pb and 206Pb / 204Pb values ​​obtained by sample testing are respectively substituted into the discriminant functions of the six countries, and the origin of tobacco leaf samples from the above six countries can be discriminated, that is, the samples belong to the region with the largest function value.

[0038] The effectiveness of the model in identifying the origin of tobacco leaves was verified by initial validation and leave-one-out cross validation methods, and the results are shown in Table 1. In the initial validation results, tobacco leaves from Argentina, Brazil, Zimbabwe, the United States, and Zambia were all correctly classified, with an initial discrimination accuracy of 100%. One Chinese tobacco leaf was misclassified as Argentine, with an initial discrimination accuracy of 96.4%. In the cross-validation results, tobacco leaves from Argentina, Brazil, Zimbabwe, the United States, and Zambia were also all correctly classified, with a cross-discrimination accuracy of 100%. Four Chinese tobacco leaves were misclassified (three from Argentina and one from the United States), with a cross-discrimination accuracy of 85.7%. In summary, the initial discrimination accuracy of tobacco leaf origin based on Fisher stepwise discriminant analysis is 98.8%, and the cross-discrimination accuracy is 95.1%, which can achieve the identification of the origin of most tobacco leaves. The scores of the first three discriminant functions of the tobacco leaf samples are plotted as scatter plots ( Figure 1), it can be seen intuitively that tobacco leaves from different countries have their own spatial distribution characteristics, and there is some overlap between Argentina and Brazil.

[0039] Table 1 Verification results of origin discriminant function

[0040]

[0041] Note: a. 98.8% of the original grouped cases were correctly classified; b. 95.1% of the cross-validated grouped cases were correctly classified.

[0042] Example 2

[0043] In order to verify the effectiveness of this method, tobacco leaves from Argentina, Brazil, Zimbabwe, the United States, Zambia and China were selected and ground into powder. According to step (2): mineral element content detection, the standard method YC / T 380-2010 "Determination of chromium, nickel, arsenic, selenium, cadmium and lead in tobacco and tobacco products - Inductively coupled plasma mass spectrometry" was used to analyze the mineral element content and determine it; step (3): metal element isotope content detection, the standard method GB / T 17672-1999 "Determination of lead, strontium and neodymium isotopes in rocks" was used to analyze the strontium and lead isotope content. The measured element content and isotope ratio data are shown in Table 2.

[0044] Table 2 Data on mineral elements and isotope ratios from different origins

[0045] Argentina Brazil Zimbabwe USA Zambia China Cu 4.64 6.03 10.52 8.5 0.79 10.25 Zn 10.31 18.84 28.64 40.15 0.00 34.27 Cr 0.83 0.29 0.73 0.69 0.00 0.58 Ni 2.05 0.97 2.14 0.78 0.24 5.27 Cd 0.24 0.39 0.10 0.50 0.00 2.91 Pb 0.84 0.09 0.70 0.30 0.10 2.60 <![CDATA[ 87 Sr / 86 Sr]]> 0.71522 0.71559 0.74148 0.71334 0.73999 0.71573 <![CDATA[ 207 Pb / 204 Pb]]> 15.609 15.639 16.45 15.638 15.699 15.652 <![CDATA[ 206 Pb / 204 Pb]]> 18.322 18.703 22.388 18.737 18.810 18.455

[0046] Substituting the content data into the discriminant function in step (4), the results are shown in Table 3 below:

[0047] Table 3. Real origin, discriminant function value and predicted origin

[0048] True origin Oarg Obr OzW Ous Oza Ocn Predicted Origin Argentina 156196.6 156193.0 156131.2 156189.2 156174.0 156185.3 Argentina Brazil 155455.5 155459.1 155391.0 155455.8 155437.0 155445.4 Brazil Zimbabwe 160455.7 160452.8 160521.2 160447.9 160475.8 160461.3 Zimbabwe USA 155179.9 155184.0 155114.3 155187.4 155151.8 155169.7 USA Zambia 157561.8 157562.3 157539.3 157548.9 157584.5 157551.9 Zambia China 157008.5 157006.1 156960.2 157002.2 156987.2 157019.9 China

[0049] As shown in Table 3, the prediction accuracy of the method of the present invention for the tobacco origins of Argentina, Brazil, Zimbabwe, the United States, Zambia and China is 100%, and the origin of tobacco leaves in different countries can be effectively traced.

[0050] The present invention is described above by way of example. It should be noted that, without departing from the core of the present invention, any simple deformation, modification or other equivalent replacement that can be made by those skilled in the art without inventive effort falls within the protection scope of the present invention.

Claims

1. A method for tracing tobacco leaf origins in different countries based on strontium-lead isotope ratios and mineral element fingerprints, characterized in that: It includes the following steps: Step (1): pre-treating tobacco leaves to obtain tobacco dust; Step (2): Detection of mineral element content: the tobacco powder obtained in step (1) is analyzed for mineral element content using standard method YC / T 380-2010 "Determination of chromium, nickel, arsenic, selenium, cadmium and lead in tobacco and tobacco products - Inductively coupled plasma mass spectrometry"; Step (3): Detection of metal element isotope content: the smoke dust obtained in step (1) is analyzed for strontium and lead isotope content using the standard method GB / T 17672-1999 "Determination of lead, strontium and neodymium isotopes in rocks"; Step (4): Determine the origin of tobacco leaves from different countries based on the following discriminant function: Oarg=28.288X1-3.708X2+87.133X3+33.708X4+170.098X5-144.816X6+57461.043X7+21926.29X8-3880.732X9-156198.966; Obr=28.227X1-3.597X2+81.982X3+33.702X4+170.21X5-145.781X6+57441.36X7+21864.961X8-3868.292X9-155454.98; Ozw=29.283X1-3.637X2+87.466X3+34.24X4+172.58X5-147.953X6+59063.574X7+22157.672X8-3908.523X9-160517.669; Ous=28.364X1-3.411X2+85.833X3+32.896X4+169.258X5-145.185X6+57222.249X7+21854.72X8-3865.97X9-155189.094; Oza=27.952X1-3.795X2+79.718X3+34.519X4+171.664X5-147.478X6+58924.132X7+21950.363X8-3884.012X9-157574.881; Ocn=29.015X1-3.657X2+80.827X3+35.149X4+173.317X5-144.015X6+57584.022X7+21983.502X8-3890.509X9-157015.224; Wherein: X1 is the Cu content mg / kg, X2 is the Zn content mg / kg, X3 is the Cr content mg / kg, X4 is the Ni content mg / kg, X5 is the Cd content mg / kg, X6 is the Pb content mg / kg, X7 is the ratio of 87Sr / 86Sr, X8 is the ratio of 207Pb / 204Pb, and X9 is the ratio of 206Pb / 204Pb; The discrimination method is to input the element content and isotope ratio determined in step (2) and step (3) into the above six discrimination functions, and compare the numerical values ​​of the six functions. If Oarg is the largest, the tobacco leaves are produced in Argentina; if Obr is the largest, the tobacco leaves are produced in Brazil; if Ozw is the largest, the tobacco leaves are produced in Zimbabwe; if Ous is the largest, the tobacco leaves are produced in the United States; if Oza is the largest, the tobacco leaves are produced in Zambia; and if Ocn is the largest, the tobacco leaves are produced in China.

2. The method according to claim 1, characterized in that In step (1), the tobacco leaf pretreatment is as follows: the sample tobacco leaf is pulverized by a cyclone mill until the powder particle size is less than 40 mesh.

3. The method according to claim 1, characterized in that The specific analysis conditions in step (3) are as follows: weigh 0.5 g of tobacco powder into a quartz beaker, add 2 mL of concentrated nitric acid to dissolve overnight, evaporate to dryness, place in a muffle furnace and heat at 250° C. for 2 h, 550° C. for 4 h, then add 1 mL of concentrated nitric acid three times to dissolve, transfer to a Teflon sample dissolving tank, evaporate to dryness for testing; The separation and purification of strontium and lead were completed with the help of AG50W-X8 cation exchange resin and AG1-X8 anion exchange resin, and the background of the whole process was 50-100pg and 100-200pg respectively.

Images