Method for detecting moisture content of buccal cigarette content

Abstract

The invention provides a method for detecting the moisture content of buccal cigarette contents, and belongs to the technical field of smokeless tobacco product analysis and detection. The method comprises the following steps: step 1, taking a proper amount of a buccal cigarette content sample; 2, preparing a detection solution; step 3, mixing and extracting the buccal cigarette content sample and the detection liquid to obtain extract liquor, calibrating a Karl-Fischer moisture titrator, adding the extract liquor into a titration cup containing methanol, and carrying out titration detection by using a Karl-Fischer reagent; or adding the detection liquid into a titration cup containing methanol, calibrating a Karl-Fischer moisture titrator, adding the buccal cigarette content sample into the titration cup, stirring and dissolving, and carrying out titration detection by using a Karl-Fischer reagent. The detection method provided by the invention is suitable for various buccal cigarette products, broadens a detection way for quality detection of the buccal cigarette and improvement of smoking quality, and has a very good practical application value.

Description

Technical Field

[0001] The present invention relates to the technical field of smokeless tobacco product analysis and detection, and in particular to a method for detecting the moisture content of buccal tobacco content. Background Art

[0002] Snus is also known as nicotine pouches and lip cigarettes. Snus does not contain tobacco, but uses synthetic nicotine salts and flavors as the main ingredients, thus avoiding the harmful substances produced by tobacco combustion, which makes snus more harmless in nature. The nicotine released by snus through the oral mucosa can stimulate and excite the consumer's autonomic nerves and central nervous system, thus leading to addiction. Literature shows that free nicotine is the form of nicotine that is most easily absorbed into the blood circulation through the oral mucosa, and the water content in snus can affect the content of free nicotine and thus affect the consumer's smoking experience. Since the water content in snus can be adjusted over a wide range, it is also a simple and effective way to adjust the content of free nicotine in snus by adjusting the water content of snus.

[0003] At present, the method CRM76 recommended by the International Tobacco Scientific Research Cooperation Center CORESTA supplemented the scope of application of this method in December 2021. It is suitable for moisture testing of oral tobacco products. The moisture content of the sample is calculated by the weight of the sample before and after drying by the oven method. However, the oven method will cause part of the volatile substances in the sample to be lost, resulting in significant differences in the moisture content test results.

[0004] The Karl Fischer method is a volumetric analysis method for determining water content proposed by Karl Fischer in 1935. This method is the most specific and accurate method for determining the water content of substances among various chemical methods. However, since the Karl Fischer method is an analytical method that requires titration, the samples to be tested are mostly liquid. For example, patent CN107505429A and Li Haiyan et al. (Reference: Li Haiyan, Tang Danyu, Xiao Yan, et al. Rapid determination of moisture content in tobacco flavors by Karl Fischer method [J]. Anhui Agricultural Science, 2009, 37.) provide Karl Fischer detection methods for moisture in liquid electronic cigarette oil and tobacco flavors respectively; and for moisture detection of solid samples, the method is mostly to dissolve them and then test them. For example, Zhu Liang et al. (Reference: Zhu Liang, Chen Yi, Gao Yiying, et al. Determination of water content in tobramycin crystals by Karl Fischer volumetric method [J]. Chinese Journal of Antibiotics, 2008, 33(12):4.) used Karl Fischer volumetric method to determine the moisture in solid particles of tobramycin crystals. However, the crystalline solid is a pure substance of a single component. The complex composition of the mixed solid particles in the oral tobacco content and the differences in the preparation process make it difficult to accurately detect their moisture content, which limits the ways to improve the free nicotine in the oral tobacco and the smoking experience. Summary of the invention

[0005] In order to solve the above problems, the present invention aims to provide a fast, effective and high-precision moisture content detection method suitable for using the Karl Fischer principle for solid content particles with complex components in oral smoke.

[0006] On the one hand, the present application provides a method for detecting the moisture content of oral cigarette contents, comprising the following steps:

[0007] Step 1: Take an appropriate amount of oral tobacco content sample;

[0008] Step 2: preparing a detection solution, wherein the detection solution is a mixed solution of methanol, formamide and salicylic acid;

[0009] Step 3: extracting the oral smoke content sample and the test solution to obtain an extract, calibrating the Karl Fischer titrator, adding the extract into a titration cup containing methanol, and performing titration detection with Karl Fischer reagent;

[0010] Alternatively, the test solution is added to a titration cup containing methanol, and after the Karl Fischer titrator is calibrated, the snus sample is added to the titration cup, stirred to dissolve, and then titrated with Karl Fischer reagent.

[0011] In one embodiment, in the detection solution of step 2, the ratio of methanol (mL), formamide (mL) and salicylic acid (mg) is V 甲醇 :V 甲酰胺 :m 水杨酸 =(1.5~2.5):(0.9~1.1):(3~5).

[0012] In one embodiment, in the detection solution of step 2, the ratio of methanol (mL), formamide (mL) and salicylic acid (mg) is V 甲醇 :V 甲酰胺 :m 水杨酸 =2:1:4.

[0013] In one embodiment, in step 1, the sampling amount of the buccal smoke content sample is 0.01-0.50 g.

[0014] In one embodiment, in step three, 0.1-0.5 g of the oral smoke content sample is mixed with 25-35 mL of the test solution, and 1-8 mL of the extract is added to a titration cup for testing.

[0015] In one embodiment, 5 to 15 mL of the test solution is added to a titration cup, and 0.05 to 0.2 g of the oral smoke content sample is taken for testing.

[0016] In one embodiment, in step three, the extraction is performed by oscillation extraction under the following conditions: extraction is performed on an oscillator at a speed of 1000 to 2000 r / min for 30 to 40 minutes.

[0017] In one embodiment, in step three, the stirring and dissolving time is 2 to 3 minutes.

[0018] In one embodiment, the oral smoke content is a granular material made of 50-80% cellulose filler, 1-10% nicotine or nicotine salt, 10-30% flavor, and 1-10% propylene glycol, and the particle size is 40-60 meshes.

[0019] Optionally, the content of the oral smoke is a granular material made of 75% cellulose filler, 5% nicotine salt, 10% flavor, and 10% propylene glycol, and the particle size is 40 meshes.

[0020] Optionally, the buccal smoke content is prepared by the following method:

[0021] The cellulose filler, nicotine or nicotine salt, flavor and propylene glycol are weighed according to mass percentage, mixed evenly and then put into a granulator to form powdery particles.

[0022] In one embodiment, the organic base in the Karl Fischer reagent is pyridine.

[0023] In one embodiment, the rotor speed in the titration cup is 800-1200 r / min, preferably 800 r / min.

[0024] In one embodiment, the titration cup contains 30-100 mL of methanol, preferably 50 mL.

[0025] In one embodiment, the titration endpoint is confirmed by potentiometric method.

[0026] In one embodiment, all reagents used in the present application are anhydrous reagents, for example, anhydrous methanol, anhydrous formamide, anhydrous salicylic acid.

[0027] Optionally, all anhydrous reagents may be treated with a desiccant to ensure an anhydrous state, such as a molecular sieve, a desiccant, and the like.

[0028] In one embodiment, the detection method provided by the present application further comprises:

[0029] In step three, the sample to be tested is tested for moisture by both the extraction method (method one) and the dissolution method (method two), and the values ​​obtained by the two methods are compared. After multiple measurements (for example, 2 to 10 times), the difference in the average values ​​of the moisture detection data of the two methods is compared. When the difference in the detection data of the two methods is less than or equal to 5%, it is confirmed that the detection method or the detection result is valid or can be mutually verified.

[0030] On the other hand, the present application also provides the use of the method in detecting the quality of a snus product and / or regulating the nicotine content in a snus product.

[0031] It is understood that the detection method described in this application uses the principle of Karl Fischer volumetric method: iodine can react chemically with water and sulfur dioxide. When pyridine and methanol coexist, 1 mol of iodine only reacts with 1 mol of water. The entire reaction process continues until all the water is consumed and free iodine is detected in the titration solution. The titration solution needs to be calibrated with water before use. The reaction formula is as follows:

[0032] C5H5N·I2+C5H5N·SO2+C5H5N+H2O+CH3OH→2C5H5N·HI+C5H6N[SO4CH3].

[0034] This application has at least the following beneficial effects:

[0035] 1. The present application provides a method for detecting the moisture content of the solid particles of the complex composition of oral smoke, which is suitable for using the Karl Fischer principle and is fast, effective and highly accurate. Among them, the present application optimizes the method for pre-treatment of oral smoke content samples, especially adopts a detection liquid of a specific composition. Compared with a single methanol solution, the formamide and salicylic acid in the detection liquid can increase the solubility of the sample, especially the addition of an appropriate amount of salicylic acid, which can not only help increase the solubility of the sample for the solid particles of the oral smoke content, adjust the pH of the sample after dissolution, but also improve the uniformity of the sample after dissolution, and reduce the side effects of formamide. In addition, it can also be applied to both extraction and dissolution methods during detection, avoiding the inability to verify the detection of a single method. The above advantages have significantly improved the accuracy of the present detection method.

[0036] 2. The method for detecting the moisture content of the buccal cigarette provided in this application is safe, rapid, and highly accurate, and is applicable to a variety of buccal cigarette products. It broadens the detection path for the quality inspection of buccal cigarettes and the improvement of smoking quality, and has great practical application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0038] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the prior art descriptions. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. In the drawings:

[0039] Figure 1 This is the linear relationship graph between sample weight and sample moisture content. DETAILED DESCRIPTION

[0040] In order to more clearly explain the overall concept of the application, the following is described in detail by way of embodiment. In the following description, a large amount of specific details are provided so as to provide a more thorough understanding of the application. However, it is obvious to those skilled in the art that the application can be implemented without one or more of these details. In other examples, in order to avoid confusion with the application, some technical features well known in the art are not described.

[0041] Unless otherwise specified, in the following embodiments, the reagents or instruments used without indicating the manufacturer are all conventional products that can be purchased commercially.

[0042] If no specific conditions are specified in the examples, the experiments were carried out according to conventional conditions or conditions recommended by the manufacturer.

[0043] The main instruments and reagents involved in the following examples are as follows:

[0044] Karl Fischer volumetric moisture titrator: MKV-710, KEM. Motor speed 200-1600r / min, 4th gear 800r / min, 5th gear 1000r / min, 6th gear 1200r / min, 7th gear 1400r / min.

[0045] Electronic balance: BSA224S, Sartorius Scientific Instruments (Beijing) Co., Ltd.

[0046] Ultrasonic cleaning machine: JP-120S, Shenzhen Jiemeng Cleaning Equipment Co., Ltd.

[0047] Ultrapure water machine: Master-S51UV, Shanghai Hetai Instruments.

[0048] Ultrapure water, the water is first-class water specified in GB / T 6682.

[0049] Karl Fischer rapid titration of methanol (CH4O): special reagents for titration, Honeywell Trading (Shanghai) Co., Ltd.

[0050] In a preferred embodiment, the method for detecting the moisture content of the buccal smoke content of the following embodiment comprises the following steps:

[0051] Step 1, taking an appropriate amount of a sample of the content of the buccal cigarette, wherein the content of the buccal cigarette is a granular material made of 75% cellulose filler, 5% nicotine salt, 20% flavor, and 10% propylene glycol, and the particle size is 40 mesh;

[0052] Step 2: preparing a test solution;

[0053] Step 3: Select extraction method or dissolution method to test the sample, where:

[0054] The steps of the extraction method are:

[0055] Accurately weigh 0.3g (accurate to 0.1mg) of oral smoke sample into a 250mL conical flask; add 30mL of test solution into the conical flask and immediately seal it with a stopper, and oscillate and extract on an oscillator at 1500r / min for 30min, then let it stand for testing; after the Karl Fischer titrator is calibrated, use a pipette to transfer 5mL of the extract into a titration cup containing 50mL of anhydrous fast methanol for testing, record the water content in the 5mL extract, and use the same method to perform a blank test;

[0056] The steps of the dissolution method are:

[0057] The test solution was added into a titration cup containing 50 mL of anhydrous fast methanol. After the Karl Fischer titrator was calibrated, about 0.1 g of sample was weighed and added into the titration cup. The magnetic stirring gear was turned on to level 4, and the test was started after stirring for 2 minutes.

[0058] Selection of methods for testing the moisture content of snus:

[0059] At present, the main methods for determining the moisture content of solid samples include direct drying, vacuum drying, Karl Fischer method, distillation, infrared absorption spectroscopy, microwave method, etc. Among them, Karl Fischer method is divided into volumetric method and coulometric method, and anhydrous methanol is often used as solvent. Nicotine bags, as a new type of oral tobacco products, have developed rapidly in the market in recent years, but there are few standards or relevant literature on the testing of its physical and chemical indicators. Among them, the method CRM76 recommended by CORESTA, the International Center for Cooperation in Tobacco Scientific Research, supplemented the scope of application of this method in December 2021. It is suitable for the moisture test of oral tobacco content products. The sample moisture content is calculated by the weight before and after the sample is dried by the oven method. The oven method will cause the loss of part of the volatile substances in the sample, resulting in a significant difference in the moisture content test results. Karl Fischer method is a relatively efficient and accurate method for testing moisture content, so Karl Fischer volumetric method is selected as the method for determining the moisture content of oral tobacco content, and fast methanol, which is specially suitable for Karl Fischer volumetric method, is used as the solvent, and the pretreatment conditions of Karl Fischer volumetric method are further optimized.

[0060] Effect of extraction method on extraction efficiency in embodiment 1 extraction method

[0061] At present, ultrasonic extraction and oscillation extraction are relatively common, simple and fast extraction methods. Therefore, ultrasonic extraction and oscillation extraction were selected to extract water from the contents of oral cigarettes. The same oral cigarette content sample was spiked and extracted for 30 minutes under the same conditions. The extraction efficiency of the two extraction methods was evaluated by the spike recovery rate. The results are shown in Table 1.

[0062] Table 1

[0063]

[0064] From the results in Table 1, it can be seen that under the same extraction time, the efficiency of the two extraction methods is not much different. Considering that during ultrasonic extraction, the sample container needs to be placed in water for ultrasonication, there may be a risk of contamination. Therefore, this method recommends that oscillation extraction is more appropriate.

[0065] Effect of extraction time on extraction efficiency in Example 2 extraction method

[0066] In order to compare the effect of oscillation extraction time on the test results of moisture content of snus, the same snus sample was spiked and oscillated for 10 min, 20 min, 30 min, and 40 min, respectively. Parallel experiments were performed and tested after the same treatment. The extraction efficiency was evaluated by the spike recovery rate. The results are shown in Table 2.

[0067] Table 2 Effect of different extraction time on extraction efficiency

[0068]

[0069] From the results in Table 2, it can be seen that the longer the oscillation time, the higher the extraction efficiency, but after the extraction time reaches 30 minutes, the extraction efficiency does not increase much. Therefore, the extraction time of 30 minutes is more suitable.

[0070] Optimization of the dissolution method for testing the moisture content of snus:

[0071] This dissolution method is to directly put the sample into the methanol in the titration cup of the Karl Fischer instrument for testing. This method can effectively avoid the influence of moisture in the environment and the utensils in contact with the test results, and can also greatly improve the test efficiency. In order to verify whether the dissolution efficiency has an effect on the moisture content in the test oral smoke, the sample mass, dissolution time, and Karl Fischer titrator rotor speed are further optimized.

[0072] Example 3 Effect of sample weight on test results in dissolution method

[0073] In order to compare the effects of different sample weights on the test results of moisture content of oral tobacco samples, the same sample was selected and the test results of different sample weights were compared under the conditions of certain dissolution time and rotor speed. The results are shown in Table 3.

[0074] Table 3 Effect of different sample weights on test results

[0075] Sample weight (g) 0.0364 0.0631 0.1002 0.1315 0.1619 Sample moisture content (%) 5.94 6.32 6.16 6.07 6.04 Sample moisture content (mg) 2.16 3.99 6.18 7.98 9.78

[0076] The data in Table 3 were plotted with the sample weight (g) as the horizontal axis and the measured absolute water content of the sample (mg) as the vertical axis to draw a linear regression curve and calculate the linear correlation coefficient. The results are as follows: Figure 1 shown.

[0077] like Figure 1 As shown, the results show that the linear equation is y = 60.149x + 0.0861, R2 = 0.9992. It can be seen that when the sample weight is between 0.03 and 0.16g, the linear relationship is good; the moisture content of the sample is between 5.9 and 6.3%, and the RSD of the 5 test results is 2.34%, which is less than 5%. Therefore, this method recommends that the sample weight is between 0.03 and 0.16g.

[0078] Influence of dissolution time on test results in Example 4 dissolution method

[0079] In order to compare the effect of dissolution time on the test results of moisture content of snus content samples, the test results of different dissolution times of the same sample were compared under the conditions of constant sample weight and rotor speed. The results are shown in Table 4.

[0080] Table 4 Effect of different dissolution time on test results

[0081]

[0082] From the data in Table 4, it can be seen that under the same conditions, the moisture content of samples with a dissolution time of 0.5-2 min tends to gradually increase, which may be due to the fact that the water in the sample is not completely dissolved; while the moisture content of the sample after 2 min has almost no change. Therefore, in order to improve the test efficiency, this method recommends that it is more appropriate to test the sample after a dissolution time of 2 min.

[0083] Example 5 Effect of rotor speed on test results

[0084] In order to compare the effect of rotor speed on the test results of moisture content of snus content samples, the same sample was selected and the results of different rotor speed tests were compared under the conditions of certain sample weight and dissolution time. The results are shown in Table 5.

[0085] Table 5 Effect of different speeds on test results

[0086]

[0087] It can be seen from Table 5 that under the same conditions, the gear of the rotor speed has no effect on the sample test results. However, considering that the faster the rotor speed, the greater the risk of hitting the glass electrode and causing damage, this method recommends selecting gear 4 for sample testing.

[0088] Example 6 Effect of the test solution on the test results

[0089] The solvent used in the Karl Fischer volumetric method is mainly fast methanol, but the solubility of oral smoke content samples in methanol is poor, which will affect the test results. In addition, the pH value of most oral smoke content particles is mainly in the range of 8-11, while the optimal pH of the titration reaction is between 5-8, which leads to a longer titration reaction time. Too long a reaction time will increase the probability of a small amount of air in the titration cup dissolving in the solution, affecting the test results.

[0090] Different reagents were selected for compounding, and moisture detection was performed under the conditions of the above-mentioned preferred parameters. The test results of each test solution were averaged after 5 tests using two methods, and the relative standard deviation and the difference between the average values ​​of the two methods were calculated. The results are shown in Table 8.

[0091] Table 8 Effects of different test solutions on test results

[0092]

[0093] From the results in Table 8, it can be seen that compared with a single methanol solvent (Example 1#), when a small amount of formamide is added to the solvent, the solubility of the sample can be significantly increased, so that more bound water in the solid sample is released and detected, but when the proportion of formamide is too high (see Example 2#), the side effect of formamide accelerating iodination makes the result significantly larger, so the preferred ratio of methanol to formamide is 2: 1. However, due to the high pH of the sample, the titration time is long, and the solution system after the sample is dissolved with this ratio of mixed organic solvent is uneven, the difference in the test results is too large during multiple tests, reducing the accuracy, so an appropriate amount of anhydrous solid or liquid acidic substance is added for adjustment. Referring to Examples 6# to 11#, when a specific ratio of methanol, formamide and salicylic acid is used as the detection liquid, appropriate test results, faster titration time, a relative standard deviation of less than 5%, and smaller and closer results between the two detection methods can be achieved. It is speculated that the acidity of salicylic acid can further increase the solubility of the sample, and can adjust the pH of the mixed system, and as an organic acid it can have better compatibility with the system. At the same time, the hydroxyl groups it contains can make a large amount of cellulose filler in the sample more evenly distributed in the system, reduce the difference between multiple test results, weaken the side effects of formamide, and do not affect the test results in different dissolution methods. Therefore, Example 9# is a more preferred detection liquid.

[0094] Example 7 Method Precision

[0095] The same sample was tested 7 times in parallel according to the detection method under the above-mentioned optimal parameters, and the precision of the method was calculated. The results are shown in Table 9:

[0096] Table 9 Precision of the method

[0097]

[0098] From the results in Table 9, it can be seen that the precision of the optimized detection method in the embodiment is less than 5%, indicating that the precision of this method is good.

[0099] Example 8 Sample spike recovery test

[0100] The same snus sample was selected for spike recovery test, with the spike amounts of 10 mg, 20 mg and 30 mg at low, medium and high levels. Two parallel tests were conducted for each spike level, and the calculated recovery results are shown in Table 10. The recovery rates were all between 80% and 120%, indicating that the recovery rate of this method was good.

[0101] Table 10 Spiked recovery of the method

[0102]

[0103] Example 9 Sample Analysis

[0104] This method and a cassette heating furnace were used to determine the moisture content of three commercially available oral tobacco samples of different compositions. The specific operation of the cassette heating furnace to test moisture content is: placing the sample in a cassette furnace for heating, and then introducing the moisture and volatile substances into a Karl Fischer instrument through a carrier gas to test the moisture content. This method is also considered to be a solution that can be used to test oral tobacco samples. The results of the moisture content in the samples determined by this method and the cassette heating furnace are shown in Table 11 below.

[0105] Table 11 Comparison between this method and the cartridge furnace method

[0106]

[0107] The results obtained by the three methods in Table 11 were analyzed for significant differences using Minitab 18 data processing software. The statistical result P was greater than 0.05. The results showed that there was no significant difference among the test methods, indicating that this method can be used as a method for testing the moisture content in oral smoke.

[0108] This experiment studied the test method of Karl Fischer volumetric method for determining the moisture content of oral smoke samples, and further optimized the pretreatment conditions of the dissolution method and extraction method. Through the analysis of extraction method, extraction time, sample weight, dissolution time, and spike recovery, it was proved that the optimized pretreatment conditions of the extraction method and dissolution method can improve the accuracy and test efficiency of the test results of the moisture content of oral smoke contents. At the same time, this method can provide a basis for the test of the moisture content of oral smoke contents.

[0109] The above is only an embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the scope of the claims of the present application.

Claims

1. A method for detecting the moisture content of oral cigarette contents, characterized in that: The steps include: Step 1: Take an appropriate amount of oral tobacco content sample; Step 2: preparing a detection solution, wherein the detection solution is a mixed solution of methanol, formamide and salicylic acid; Step 3: extracting the oral smoke content sample and the test solution to obtain an extract, calibrating the Karl Fischer titrator, adding the extract into a titration cup containing methanol, and performing titration detection with Karl Fischer reagent; Alternatively, the test solution is added to a titration cup containing methanol, and after the Karl Fischer titrator is calibrated, the snus content sample is added to the titration cup, stirred to dissolve, and then titrated with Karl Fischer reagent.

2. The method according to claim 1, characterized in that In the detection solution of step 2, the ratio of methanol, formamide and salicylic acid is V 甲醇 :V 甲酰胺 :m 水杨酸 =(1.5~2.5):(0.9~1.1):(3~5).

3. The method according to claim 2, characterized in that In the detection solution of step 2, the ratio of methanol, formamide and salicylic acid is V 甲醇 :V 甲酰胺 :m 水杨酸 =2:1:

4.

4. The method according to claim 1, characterized in that: In the step 1, the sampling amount of the buccal smoke content sample is 0.01 to 0.50 g.

5. The method according to claim 1, characterized in that: In the step 3, 0.1-0.5 g of the oral smoke content sample is mixed with 25-35 mL of the test solution, and 1-8 mL of the extract is added to the titration cup for testing; And / or, 5 to 15 mL of the test solution is added to a titration cup, and 0.05 to 0.2 g of the oral smoke content sample is taken for testing.

6. The method according to claim 1, characterized in that In the step 3, the extraction is performed by oscillation extraction under the following conditions: extraction is performed on an oscillator at a speed of 1000 to 2000 r / min for 30 to 40 minutes.

7. The method according to claim 1, characterized in that In the step 3, the stirring and dissolving time is 2 to 3 minutes.

8. The method according to claim 1, characterized in that: The content of the oral cigarette is a granular material made of 50-80% cellulose filler, 1-10% nicotine or nicotine salt, 10-30% flavor, and 1-10% propylene glycol, and the particle size is 40-60 meshes.

9. The method according to claim 1, characterized in that: The organic base in the Karl Fischer reagent is pyridine; and / or, the rotor speed in the titration cup is 800 to 1200 r / min; and / or, the titration cup contains 30-100 mL of methanol; And / or, the titration endpoint is confirmed by potentiometric method.

10. Use of the method according to any one of claims 1 to 9 in detecting the quality of a snus product and / or regulating the nicotine content in a snus product.

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