Quantitative detection method for multi-element heavy metals in tobacco flavor

Abstract

The invention discloses a quantitative detection method for multi-element heavy metals in tobacco flavor. According to the method, to-be-detected heavy metal elements in the essence are calibrated through a multi-element heavy metal standard solvent to obtain a standard curve, and through multiple times of test fitting, the influence of background noise on result accuracy is eliminated, and the detection limit is effectively reduced, so that the test sensitivity is improved; the co-soluble solvent is adopted to effectively eliminate the influence of different substrates in the perfume, and the problem of local abnormality caused by inconsistent dissolution backgrounds is solved. The method has the advantages of simple sample pretreatment, high detection speed, high accuracy and the like, can significantly improve the detection capability and efficiency of heavy metals in the essence and perfume sample, and effectively ensures the quality and safety of the essence and perfume sample.

Description

Technical Field

[0001] The invention belongs to the field of sample processing and detection, and in particular relates to a method for rapid pre-processing and detection of harmful heavy metals in flavors and fragrances. Background Art

[0002] With the improvement of my country's food hygiene regulations, the safety indicators of various food additives have been continuously improved, not only various quality indicators, but also general testing methods. GB29938-2020 "National Food Safety Standard General Rules for Food Flavors" puts forward limit requirements for heavy metals and arsenic for natural flavors used in food, among which heavy metals (in terms of Pb) are 10 mg / kg and total arsenic (in terms of As) is 3 mg / kg. The detection of heavy metals and arsenic in tobacco flavors and fragrances adopts general methods GB5009.74, GB5009.76 and GB5009.11.

[0003] Cigarettes are a special kind of food. They stimulate the olfactory organs and taste organs by burning and smoking to achieve a certain degree of physiological satisfaction for smokers. The use of tobacco flavors and fragrances in cigarettes can give the product a unique style and improve the quality of smoke, so it is one of the main base materials in the cigarette processing process. In recent years, the country has attached great importance to the quality of cigarette products and smoking and health. In terms of the management of tobacco flavors and fragrances, in addition to ensuring their availability and stabilizing product quality, safety indicators are also an important basis for evaluation. However, the amount of tobacco flavors and fragrances is large, and the detection task is arduous. Therefore, the development of rapid detection methods for flavors and fragrances, through the quality control of tobacco flavors and fragrances in terms of availability and safety, can play a positive role in further regulating the market, improving the tobacco industry system, and protecting the health of consumers.

[0004] At present, there are many methods for detecting heavy metals, and the commonly used detection methods are: atomic absorption spectroscopy (AAS), atomic fluorescence spectroscopy (AFS), inductively coupled plasma atomic emission spectroscopy (ICP-AES), inductively coupled plasma mass spectrometry (ICP-MS), etc. These detection methods require expensive equipment, cumbersome pre-treatment, time-consuming and labor-intensive, and require professional personnel to operate and maintain, and cannot be widely promoted. In addition, the content of heavy metals in flavors and fragrances is extremely low, but the number of samples in actual detection is huge, which poses a challenge to the detection efficiency of traditional methods. Therefore, it is urgent to develop a fast, efficient, and high-throughput detection technology for heavy metal elements in flavors and fragrances. Summary of the invention

[0005] In view of the deficiencies in the prior art, the present invention provides a method for quantitatively detecting multiple heavy metals in tobacco flavorings. The method has high precision, good reproducibility, high accuracy, good repeatability, can achieve direct quantification of samples, and has a short analysis time. The method is simple, easy to operate, convenient and reliable.

[0006] In order to achieve the above technical objectives, the present invention provides a method for quantitatively detecting multiple heavy metals in tobacco flavorings, characterized in that it comprises:

[0007] S1: Add the standard solution of each heavy metal to be detected in the fragrance to the solvent, mix and fix the volume in a volumetric flask to obtain a multi-component heavy metal standard solution;

[0008] S2: Dilute the multi-metal standard solvents to a fixed volume according to the concentration gradient to obtain a series of multi-metal standard working solutions;

[0009] S3: Perform X-ray fluorescence spectroscopy analysis on each multi-component heavy metal standard solution and draw a standard curve for each heavy metal element;

[0010] S4: dissolving the tobacco flavoring to be tested in a solvent, using a volumetric flask to adjust the volume to obtain a sample to be tested, and performing X-ray fluorescence spectrum analysis on the sample to be tested according to the standard curve obtained in S3, and obtaining the sample to be tested;

[0011] The flavor ingredients in the tobacco flavor include tartaric acid, glucose, vanillin and menthyl ester.

[0012] As a preferred solution, the volume ratio of the heavy metal standard solution to the solvent is 1:2 to 100. More preferably, the volume ratio of the heavy metal standard solution to the solvent is 1:2.5 to 80.

[0013] As a preferred solution, the heavy metals are at least two of Pb, Cr, Cd, As, Se and Hg. More preferably, the heavy metals are Pb and As.

[0014] As a preferred solution, the concentration range of the multi-metal standard working solution is 0.1-25 mg / L, the gradient value range of the concentration gradient is 0.1-5 mg / L, and the number of point values ​​in the concentration gradient is 5-8.

[0015] As a preferred solution, during the X-ray fluorescence spectrometry analysis, a sample cup and a support membrane are used to hold the liquid to be tested, the volume of the liquid in the sample cup is 2 to 5 mL, and the thickness of the liquid is ≥1 mm.

[0016] As a preferred solution, the support film is one of Mylar film, polycarbonate film, polypropylene film and polyimide film.

[0017] As a preferred solution, the standard curve of the heavy metal elements is obtained by the least squares method.

[0018] As a preferred solution, the standard curve of the heavy metal element takes the heavy metal concentration as the horizontal coordinate x and the net peak intensity as the vertical coordinate y. Each concentration sample is tested 3 to 5 times and the obtained data are fitted.

[0019] As a preferred solution, the fitting method is at least one of an interpolation method, an iteration method and a least squares method.

[0020] As a preferred solution, the fitting method is the least squares method, and the process is: the net peak intensity obtained by multiple tests at the same concentration of heavy metal elements is arithmetic averaged to obtain a concentration-average peak intensity discrete lattice, and the least squares method is used for fitting, that is, the calculation process is:

[0021] Formula 1:

[0022] Formula 2:

[0023] Formula 3:

[0024] In formulas 1 to 3: y ij The concentration is x i When , the net peak intensity value obtained from the jth test; The concentration is x i The average net peak intensity at ; k and b are the parameters to be measured for the fitting curve.

[0025] As a preferred solution, the solvent of the flavor in the tobacco flavor is at least one of propylene glycol, alcohol, 3-methoxy-3-methylbutanol and water.

[0026] As a preferred solution, the solvent is an inorganic solvent that is miscible with the solvent of the flavor in the fragrance in any proportion.

[0027] As a preferred solution, the inorganic solvent is ultrapure water.

[0028] The present invention also provides a detailed process of a quantitative detection method for multiple heavy metals in tobacco flavorings:

[0029] 1) Preparation of multi-component heavy metal standard solution: accurately pipette 1.5 mL of arsenic standard solution and 5.0 mL of lead standard solution, dissolve them in a 50 mL volumetric flask with water to make up to volume, and prepare a multi-component heavy metal standard solution with an arsenic concentration of 30 mg / L and a lead concentration of 100 mg / L, wherein the concentration of the arsenic standard solution and the lead standard solution is 1000 mg / L, and the medium is 2-5% nitric acid solution;

[0030] 2) Preparation of multi-metal standard working solutions: Accurately measure 0.125mL, 0.250mL, 0.500mL, 1.000mL, 1.500mL, and 2.000mL of multi-metal standard solutions into 10mL volumetric flasks, dilute to volume with ultrapure water, and prepare for immediate use. The concentrations of arsenic in the prepared series of standard working solutions are 0.375mg / L, 0.750mg / L, 1.50mg / L, 3.00mg / L, 4.50mg / L, and 6.00mg / L; the concentrations of lead are 1.25mg / L, 2.50mg / L, 5.00mg / L, 10.0mg / L, 15.0mg / L, and 20.0mg / L;

[0031] 3) Standard working solution loading and X-ray fluorescence spectrometry analysis test: Cut a polyimide film of appropriate length and clip the polyimide film onto the sample cup with a buckle. Transfer the standard sample prepared in step (1), place 5 mL of the solution into the sample cup, tighten the sample cover, and wait for testing; set the instrument parameters as follows: the qualitative and quantitative characteristic peak position of arsenic is As: Kα = 10.543 KeV; the qualitative and quantitative characteristic peak position of lead is Pb: Lβ1 = 12.614 KeV. Excitation voltage: 40 kV; excitation current: 1000 μA, scanning time: 360 s;

[0032] 4) Drawing of standard curves for each heavy metal element: The standard curves for arsenic and lead content were drawn using the external standard method; the reagent concentration of the target element was taken as the abscissa x, and the net peak intensity was taken as the ordinate y. Each sample was measured three times, and the standard curves for arsenic and lead were obtained using linear fitting;

[0033] 5) Sample preparation and testing: Accurately weigh 5 g of tobacco flavoring and place it in a 10 mL volumetric flask with a mass accurate to 0.1 mg. Make up to volume with ultrapure water. The sample preparation process is the same as in step 3). Use an X-ray fluorescence spectrometer to inject and analyze the sample. Call up the corresponding standard curve and directly run the test program to record the results.

[0034] The ultrapure water used in the present invention meets the requirements of GB / T 6682 "Specifications and Test Methods for Water Used in Analytical Laboratories".

[0035] Compared with the prior art, the beneficial technical effects of the present invention are:

[0036] 1) The detection method provided by the present invention accurately reflects the standard curve of multi-component heavy metals in X-ray fluorescence spectrometry analysis through a multi-component mixed heavy metal standard solution, and eliminates the influence of background noise on the accuracy of the results through multiple test fitting, effectively reduces the detection limit, and thus improves the sensitivity of the test.

[0037] 2) In the technical solution provided by the present invention, a co-solvent is used to effectively eliminate the influence of different substrates in the flavors and spices, and solves the problem of local anomalies caused by inconsistent dissolution background. This method has the advantages of simple sample pretreatment, fast detection speed, and high accuracy. It can significantly improve the detection ability and efficiency of heavy metals in flavors and spices samples, and effectively ensure the quality and safety of flavors and spices samples. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the technical solutions in the implementation of the present invention, the following briefly introduces the drawings required in the implementation cases of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the contents of the embodiments of the present invention and these drawings without paying any creative work.

[0039] Figure 1 It is a flow chart of a method for detecting heavy metal content in flavors and fragrances based on energy dispersive X-ray fluorescence spectroscopy provided by the present invention;

[0040] Figure 2 It is a schematic diagram of the structure of the energy dispersive X-ray fluorescence spectrometer used in the present invention;

[0041] Figure 3 This is a schematic diagram of sample cup loading;

[0042] Figure 4 is a curve diagram showing the relationship between the intensity of the characteristic spectrum line of the heavy metal element arsenic and its concentration in Example 1 of the present invention;

[0043] Figure 5 is a curve diagram showing the relationship between the intensity of the characteristic spectrum line of the heavy metal element lead and the concentration in Example 1 of the present invention;

[0044] Figure 6 It is the spectrum diagram of arsenic and lead elements in Example 1 of the present invention. DETAILED DESCRIPTION

[0045] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific examples.

[0046] The instrument used in the present invention is a NX-100S heavy metal detector (produced by Gangyan NAK Testing Technology Co., Ltd.), equipped with a 65kV, 1mA silver target X-ray tube and an Amptek Fast silicon drift detector.

[0047] Example 1

[0048] There is a flavor sample with unknown arsenic and lead concentrations, and the content in the flavor sample needs to be determined.

[0049] The XRF conditions used are: the qualitative and quantitative characteristic peak position of arsenic is As: Kα = 10.543 KeV; the qualitative and quantitative characteristic peak position of lead is Pb: Lβ1 = 12.614 KeV. Excitation voltage: 40 kV; excitation current: 1000 μA, scanning time: 360 s.

[0050] An instrumental analysis method for determining the arsenic and lead content in a flavor sample using an X-ray fluorescence spectrometer, the specific steps comprising:

[0051] 1) Preparation of multi-component heavy metal standard solution: accurately pipette 1.5 mL of arsenic standard solution and 5.0 mL of lead standard solution, dissolve them in a 50 mL volumetric flask with water to make up to volume, and prepare a multi-component heavy metal standard solution with an arsenic concentration of 30 mg / L and a lead concentration of 100 mg / L, wherein the concentration of the arsenic standard solution and the lead standard solution is 1000 mg / L, and the medium is 2-5% nitric acid solution;

[0052] 2) Preparation of multi-metal standard working solutions: Accurately measure 0.125mL, 0.250mL, 0.500mL, 1.000mL, 1.500mL, and 2.000mL of multi-metal standard solutions into 10mL volumetric flasks, dilute to volume with ultrapure water, and prepare for immediate use. The concentrations of arsenic in the prepared series of standard working solutions are 0.375mg / L, 0.750mg / L, 1.50mg / L, 3.00mg / L, 4.50mg / L, and 6.00mg / L; the concentrations of lead are 1.25mg / L, 2.50mg / L, 5.00mg / L, 10.0mg / L, 15.0mg / L, and 20.0mg / L;

[0053] 3) Standard working solution loading and X-ray fluorescence spectrometry analysis test: Cut a polyimide film of appropriate length and clip the polyimide film onto the sample cup with a snap. Transfer the standard sample prepared in step (1), place 5 mL of the solution into the sample cup, tighten the sample cover, and wait for testing; set the instrument parameters as follows: the qualitative and quantitative characteristic peak position of arsenic is: As: Kα = 10.543 KeV; the qualitative and quantitative characteristic peak position of lead is: Pb: Lβ1 = 12.614 KeV. Excitation voltage: 40 kV; excitation current: 1000 μA, scanning time: 360 s;

[0054] 4) Standard curves of heavy metal elements and drawing of standard curves: The standard curves of arsenic and lead content were drawn by external standard method; the reagent concentration of the target element was taken as the abscissa x and the net peak intensity was taken as the ordinate y. Each sample was measured 3 times and the standard curves of arsenic and lead were obtained by linear fitting;

[0055] 5) Sample preparation and testing: Accurately weigh 5 g of tobacco flavoring and place it in a 10 mL volumetric flask with a mass accurate to 0.1 mg. Make up to volume with ultrapure water. The sample preparation process is the same as in step 3). Use an XRF fluorescence spectrometer to inject and analyze the sample, call out the corresponding standard curve and directly run the test program, and record the results.

[0056] Two parallel samples were made: the arsenic content of parallel sample 1 was 0.512 mg / kg, and the lead content was 1.23 mg / kg; the arsenic content of parallel sample 2 was 0527 mg / kg, and the lead content was 1.10 mg / kg.

[0057] Example 2

[0058] There is a flavor sample with known arsenic and lead concentrations, and the content in the flavor sample needs to be determined.

[0059] The XRF conditions used are: the qualitative and quantitative characteristic peak position of arsenic is: As: Kα = 10.543 KeV; the qualitative and quantitative characteristic peak position of lead is: Pb: Lβ1 = 12.614 KeV. Excitation voltage: 40 kV; excitation current: 1000 μA, scanning time: 360 s.

[0060] An instrumental analysis method for determining the arsenic and lead content in a flavor sample using an X-ray fluorescence spectrometer, the specific steps comprising:

[0061] 1) Preparation of multi-component heavy metal standard solution: accurately pipette 1.5 mL of arsenic standard solution and 5.0 mL of lead standard solution, dissolve them in a 50 mL volumetric flask with water to make up to volume, and prepare a multi-component heavy metal standard solution with an arsenic concentration of 30 mg / L and a lead concentration of 100 mg / L, wherein the concentration of the arsenic standard solution and the lead standard solution is 1000 mg / L, and the medium is 2-5% nitric acid solution;

[0062] 2) Preparation of multi-metal standard working solutions: Accurately measure 0.125mL, 0.250mL, 0.500mL, 1.000mL, 1.500mL, and 2.000mL of multi-metal standard solutions into 10mL volumetric flasks, dilute to volume with ultrapure water, and prepare for immediate use. The concentrations of arsenic in the prepared series of standard working solutions are 0.375mg / L, 0.750mg / L, 1.50mg / L, 3.00mg / L, 4.50mg / L, and 6.00mg / L; the concentrations of lead are 1.25mg / L, 2.50mg / L, 5.00mg / L, 10.0mg / L, 15.0mg / L, and 20.0mg / L;

[0063] 3) Standard working solution loading and X-ray fluorescence spectrometry analysis test: Cut a polyimide film of appropriate length and clip the polyimide film onto the sample cup with a buckle. Transfer the standard sample prepared in step (1), place 5 mL of the solution into the sample cup, tighten the sample cover, and wait for testing; set the instrument parameters as follows: the qualitative and quantitative characteristic peak position of arsenic is As: Kα = 10.543 KeV; the qualitative and quantitative characteristic peak position of lead is Pb: Lβ1 = 12.614 KeV. Excitation voltage: 40 kV; excitation current: 1000 μA, scanning time: 360 s;

[0064] 4) Standard curves of heavy metal elements and drawing of standard curves: The standard curves of arsenic and lead content were drawn by external standard method; the reagent concentration of the target element was taken as the abscissa x and the net peak intensity was taken as the ordinate y. Each sample was measured 3 times and the standard curves of arsenic and lead were obtained by linear fitting;

[0065] 5) Sample preparation and testing: Accurately weigh 5 g of tobacco flavoring and place it in a 10 mL volumetric flask with a mass accurate to 0.1 mg. Make up to volume with ultrapure water. The sample preparation process is the same as in step 3). Use an X-ray fluorescence spectrometer to inject and analyze the sample. Call up the corresponding standard curve and directly run the test program to record the results.

[0066] Two parallel samples were made: the arsenic content of parallel sample 1 was 3.53 mg / kg, and the lead content was 10.1 mg / kg; the arsenic content of parallel sample 2 was 3.49 mg / kg, and the lead content was 9.86 mg / kg.

[0067] The present invention also conducted a precision experiment on flavor samples. The flavor samples in Example 2 were taken as the investigation objects. The samples were accurately weighed to prepare 6 samples. The RSD of the 6 test results was calculated, indicating that the detection method of the present invention has good precision. The test results are shown in Table 1.

[0068] Table 1

[0069]

[0070] The present invention also conducted a repeatability experiment on the stability of the detection process. The experiment adopted the standard solution addition method to prepare positive samples containing arsenic and lead as the investigation object, and performed XRF analysis on the positive samples for 6 days to investigate the stability of the samples during the 6 days. It was shown that the detection method of the present invention has good repeatability. The results are shown in Table 2.

[0071] Table 2

[0072]

[0073] In order to verify the accuracy and stability of the analytical method, the present invention also conducted a spike recovery experiment, and conducted a spike recovery experiment of high, medium and low concentration levels of standard solutions for flavor and fragrance samples known to be free of arsenic and lead. Each sample was measured 3 times, and the results are shown in Tables 3 to 5. Determination of recovery and repeatability. In this test, three flavor samples with different propylene glycol contents were selected as research objects, namely, sample 1: propylene glycol content 20%, sample 2: propylene glycol content 50%, and sample 3: propylene glycol content 70%.

[0074] Table 3 Sample 1 spike recovery test results

[0075]

[0076] Table 4 Sample 2 spike recovery test results

[0077]

[0078] Table 5 Sample 3 spike recovery test results

[0079]

[0080] The experimental results show that the recovery rate of arsenic in sample 1 is between 101.5% and 108.8%, the recovery rate of lead is between 102.0% and 112.2%, and the RSD is between 0.5% and 5.9%; the recovery rate of arsenic in sample 2 is between 108.6% and 112.6%, the recovery rate of lead is between 102.6% and 120.1%, and the RSD is between 0.7% and 3.0%; the recovery rate of arsenic in sample 3 is between 116.8% and 121.1%, the recovery rate of lead is between 114.8% and 121.4%, and the RSD is between 0.7% and 3.9%. It shows that among the three substances with different propylene glycol contents, the recovery rates of arsenic and lead are relatively high, and the recovery rates are all greater than 100%, which can effectively prevent false negative results, and the repeatability of the test results is also relatively good. In addition, the recovery rate experiment shows that as the propylene glycol content increases, the recovery rates of arsenic and lead also increase. This method can meet the requirements of arsenic and lead analysis in three tobacco flavors with different propylene glycol contents, and is accurate and reliable.

[0081] It can be seen from the above precision, repeatability and spike recovery tests that the method for analyzing the arsenic and lead contents in flavor and fragrance samples using X-ray fluorescence spectrometer described in the present invention is convenient and feasible. This method has high precision, good reproducibility, high accuracy and good repeatability, and only requires simple pretreatment of the samples, which greatly reduces the analysis time.

Claims

1. A method for quantitatively detecting multiple heavy metals in tobacco flavorings, characterized in that: include: S1: Add the standard solution of each heavy metal to be detected in the fragrance to the solvent, mix and fix the volume in a volumetric flask to obtain a multi-component heavy metal standard solution; S2: Dilute the multi-metal standard solvents to a fixed volume according to the concentration gradient to obtain a series of multi-metal standard working solutions; S3: Perform X-ray fluorescence spectrometry analysis on each multi-component heavy metal standard solution and draw a standard curve for each heavy metal element; S4: dissolving the tobacco flavoring to be tested in a solvent, using a volumetric flask to adjust the volume to obtain a sample to be tested, and performing X-ray fluorescence spectrum analysis on the sample to be tested according to the standard curve obtained in S3, and obtaining the sample to be tested; The flavor ingredients in the tobacco flavor include tartaric acid, glucose, vanillin and menthyl ester.

2. The method for quantitatively detecting multiple heavy metals in tobacco flavoring according to claim 1, characterized in that: The volume ratio of the heavy metal standard solution to the solvent is 1:2-100; the heavy metals are at least two of Pb, Cr, Cd, As, Se and Hg.

3. The method for quantitatively detecting multiple heavy metals in tobacco flavoring according to claim 1, characterized in that: The concentration range of the multi-metal standard working solution is 0.1-25 mg / L, the gradient value range of the concentration gradient is 0.1-5 mg / L, and the number of point values ​​in the concentration gradient is 5-8.

4. The method for quantitatively detecting multiple heavy metals in tobacco flavoring according to claim 1, characterized in that: During the X-ray fluorescence spectrometry analysis, a sample cup and a support film are used to hold the liquid to be tested, the volume of the liquid in the sample cup is 2 to 5 mL, and the thickness of the liquid is ≥1 mm.

5. The method for quantitatively detecting multiple heavy metals in tobacco flavoring according to claim 4, characterized in that: The support film is one of a Mylar film, a polycarbonate film, a polypropylene film and a polyimide film.

6. The method for quantitatively detecting multiple heavy metals in tobacco flavoring according to claim 1, characterized in that: The standard curve of the heavy metal element is obtained by fitting the obtained data with the heavy metal concentration as the horizontal coordinate x and the net peak intensity as the vertical coordinate y, and each concentration sample is tested 3 to 5 times.

7. The method for quantitatively detecting multiple heavy metals in tobacco flavoring according to claim 6, characterized in that: The fitting method is at least one of an interpolation method, an iteration method and a least squares method.

8. The method for quantitatively detecting multiple heavy metals in tobacco flavoring according to claim 6, characterized in that: The fitting method is the least square method, and the process is: the net peak intensity obtained by multiple tests at the same concentration of heavy metal elements is arithmetic averaged to obtain a concentration-average peak intensity discrete point matrix, and the least square method is used for fitting, that is, the calculation process is: Formula 1: Formula 2: Formula 3: In formulas 1 to 3: y ij The concentration is x i When , the net peak intensity value obtained from the jth test; The concentration is x i The average net peak intensity at ; k and b are the parameters to be measured for the fitting curve.

9. The method for quantitatively detecting multiple heavy metals in tobacco flavoring according to claim 1, characterized in that: The solvent of the flavor in the tobacco flavor is at least one of propylene glycol, alcohol, 3-methoxy-3-methylbutanol and water.

10. The method for quantitatively detecting multiple heavy metals in tobacco flavoring according to claim 9, characterized in that: The solvent is an inorganic solvent that is miscible with the solvent of the essence in the spice in any proportion.

11. The method for quantitatively detecting multiple heavy metals in tobacco flavoring according to claim 10, characterized in that: The inorganic solvent is ultrapure water.

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