A method for determining titanium dioxide nanoparticles in mainstream cigarette smoke

Abstract

The application provides a method for determining titanium dioxide nanoparticles in mainstream cigarette smoke, comprising the following steps: 1) repeatedly extracting and washing particulate matter in mainstream cigarette smoke collected under a specific environment to obtain an extraction solution and a washing solution, combining and constant volume to prepare a sample solution to be determined; 2) using an inductively coupled plasma mass spectrometer to determine the sample solution to be determined and a standard sample solution containing titanium dioxide nanoparticles with a known concentration to obtain the concentration of titanium dioxide nanoparticles in the sample solution to be determined; 3) determining the atomization efficiency through the standard sample solution, and calculating the particle size and quantity of titanium dioxide nanoparticles in the sample solution to be determined by using a standard curve method according to the pulse intensity, pulse area of nanoparticles in the sample solution to be determined and the mass of the measured nanoparticles in the nanoparticles. The method provides strong technical support for the quality and safety evaluation of cigarettes.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of reconstituted tobacco by papermaking method, and particularly relates to a method for determining titanium dioxide nanoparticles in mainstream cigarette smoke. BACKGROUND

[0002] Titanium dioxide, also known as titanium white powder, has unique whiteness, high opacity, good brightness and durability, and is widely used in materials and products such as coatings, plastics, papermaking, printing ink, chemical fiber, rubber and cosmetics. It is also a permitted additive for tobacco materials in the domestic tobacco industry. On February 18, 2020, according to the 14th revised document of the EU CLP regulation (Regulation on Classification, Labeling and Packaging of Substances and Mixtures in the European Union) (EC) 1272 / 2008, the European Commission decided to classify titanium dioxide as Category 2 of inhalation carcinogens (suspected carcinogens). Subsequently, according to Article 7 of the EU Tobacco Products Directive (Directive 2014 / 40 / EU, TPD), it was decided that tobacco products containing titanium dioxide would not be sold on the EU market from September 9, 2021. It needs to be particularly noted that the formulation of the relevant regulations of the European Union takes into account that the main way of human harm caused by titanium dioxide is inhalation risk, and only when the particle size (diameter) of titanium dioxide particles is ≤10 μm, it is recognized as a carcinogenic substance, and in the mainstream smoke of cigarettes, titanium dioxide mainly exists in the form of nanoparticles. Therefore, in order to respond to the global trend of promoting titanium dioxide-free cigarette products and meet the actual development needs of domestic tobacco enterprises, it is urgent to conduct in-depth analysis and research on the actual situation of titanium dioxide in the mainstream smoke of cigarettes.

[0003] At present, there is no analysis method or detection standard for titanium dioxide nanoparticles in the mainstream smoke of cigarettes. The detection of titanium dioxide content in food, cosmetics and pigments mainly uses inductively coupled plasma mass spectrometry, X-ray fluorescence spectrophotometry and aluminum reduction method, etc., and establishes national standards such as GB 5009.246-2016 "National Food Safety Standard Determination of Titanium Dioxide in Food", GB 27599-2011 "Titanium Dioxide for Cosmetics" and GB / T 1706-2006 "Titanium Dioxide Pigment". The main principle is to detect titanium elements after sample pretreatment, and then calculate the content of titanium dioxide in the sample by formula, but titanium exists in various compounds such as titanium trichloride, titanium tetrachloride and titanium-aluminum metal complex. These methods cannot completely objectively reflect the actual content level and existing form of titanium dioxide, and cannot meet the actual needs of the tobacco industry. SUMMARY

[0004] In view of the above-mentioned disadvantages of the prior art, the purpose of the present application is to provide a method for determining titanium dioxide nanoparticles in mainstream cigarette smoke, so as to overcome the problems that the determination method in the prior art cannot objectively reflect the actual content level or form of titanium dioxide.

[0005] To achieve the above-mentioned purpose and other related purposes, the present application provides a method for determining titanium dioxide nanoparticles in mainstream cigarette smoke, comprising the following steps:

[0006] 1) repeatedly extracting and washing the particulate matter of mainstream cigarette smoke collected under a specific environment to obtain an extraction solution and a washing solution, combining and constant volume to prepare a sample solution to be determined;

[0007] 2) determining the sample solution to be determined and a standard sample solution containing titanium dioxide nanoparticles with a known concentration by using an inductively coupled plasma mass spectrometer to obtain the concentration of titanium dioxide nanoparticles in the sample solution to be determined;

[0008] 3) determining the atomization efficiency by using the standard sample solution, calculating the particle size and quantity of titanium dioxide nanoparticles in the sample solution to be determined by using a standard curve method according to the pulse intensity, pulse area of nanoparticles in the sample solution to be determined and the mass of the measured nanoparticles in the nanoparticles.

[0009] The standard curve method draws a standard curve according to the linear relationship between the known concentration of titanium dioxide nanoparticles in the standard sample solution and the analysis line intensity determined by using the inductively coupled plasma mass spectrometer, and then obtains the concentration of titanium dioxide nanoparticles in the sample solution to be determined by determining the analysis line intensity of the sample solution to be determined.

[0010] In the embodiment of the present application, in step 1), the particulate matter of mainstream cigarette smoke is collected by using an electrostatic trapping device of a smoking machine.

[0011] In the embodiment of the present application, in step 1), the specific environment is: temperature 20-24℃, relative humidity 55-65%.

[0012] In the embodiment of the present application, in step 1), the solvent used for extraction and washing is one or more of ethanol, methanol or isopropyl alcohol.

[0013] In the embodiment of the present application, in step 1), the extraction frequency is 1-2 times.

[0014] In the embodiment of the present application, in step 1), the washing frequency is 3-5 times.

[0015] In the embodiment of the present application, in step 2), the standard sample solution is prepared by diluting the titanium dioxide nanoparticles with ethanol / water in a certain ratio to obtain a standard sample solution containing titanium dioxide nanoparticles with a known concentration.

[0016] Further, the ratio of the ethanol / water is 1:45-1:55.

[0017] Further, the standard sample solution is a titanium dioxide nanoparticle solution with a concentration gradient of 0, 1 ng / L, 3 ng / L, 5 ng / L, and 10 ng / L.

[0018] In the embodiment of the present application, in step 2), the inductively coupled plasma mass spectrometer is further configured with an organic oxygenated sample introduction system.

[0019] In the embodiment of the present application, in step 2), the determination conditions of the inductively coupled plasma mass spectrometer are as follows:

[0020] Ion source: ICP source; radio frequency power: 1400-1800 W;

[0021] Cooling gas: argon, flow rate: 14.0-18.0 L / min;

[0022] Auxiliary gas: argon, flow rate: 1.0-1.4 L / min;

[0023] Atomizing gas: argon, flow rate: 1.0-1.2 L / min;

[0024] Full-matrix sample introduction gas: oxygen, flow rate: 0.02-0.08 L / min;

[0025] Collision / reaction cell: ammonia, flow rate: 0.5-1.5 mL / min;

[0026] Rpq 0.4-0.5; analysis mode: mass shift, Q1 48 m / z, Q3 131 m / z; IGM voltage: hyperskimmer 5.0-6.0 V, OmniRing-200--250 V; residence time: 100 microseconds; scan time: 100 seconds; AFT voltage: 230-280 V; sample rate: 0.05-0.10 ml / min.

[0027] In the embodiment of the present application, in step 3), the standard sample solution determines the atomization efficiency according to formula (3).

[0028] In the embodiment of the present application, in step 3), the particle size and quantity of the titanium dioxide nanoparticles in the sample solution to be measured are calculated according to formulas (1), (2), and (3),

[0029] The formula (1) is:

[0030] The formula (2) is:

[0031] The formula (3) is: p = l p / (V x η p );

[0032] In the formula, m p : particle mass (fg);ρ p : particle density (i.e. the concentration of titanium dioxide nanoparticles of the sample solution to be measured, g / cm 3 );η n : atomization efficiency;V: sample inlet flow rate (ml / min);l p : particle signal (cps);s: response time (cps / ppb);t d : integration time (sec);f d : mass fraction (molar mass of ion / molar mass of element to be measured);Np: particle number.

[0033] As described above, the method for determining titanium dioxide nanoparticles in mainstream cigarette smoke of the present application has the following beneficial effects:

[0034] The method for determining titanium dioxide nanoparticles in mainstream cigarette smoke of the present application has good accuracy and stability, and can be effectively applied to the research of smoke-related components and the evaluation of cigarette quality and safety.

[0035] The method for determining titanium dioxide nanoparticles in mainstream cigarette smoke of the present application uses ammonia gas as a reaction gas and effectively eliminates the interference of multi-atom on titanium dioxide nanoparticles through two-stage mass spectrometry screening, thereby realizing accurate quantification of titanium dioxide nanoparticles with a particle size greater than 50 nm. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 The figure shows the titanium dioxide nanoparticle profile in sample 4 of Example 2 of the present application.

[0037] Figure 2 The figure shows the nanoparticle time scan in sample 4 of Example 2 of the present application, showing the real-time signal of the particles.

[0038] Figure 3 The figure shows the nanoparticle particle size normalized frequency distribution of sample 4 of Example 2 of the present application. DETAILED DESCRIPTION

[0039] The present application is described in greater detail by the specific examples below, and other advantages and effects of the present application can be easily understood by those skilled in the art from the disclosure herein. The present application can also be implemented or applied by different specific embodiments, and various modifications or changes can be made to the details herein based on different views and applications without departing from the spirit of the present application.

[0040] The present application provides a method for determining titanium dioxide nanoparticles in mainstream cigarette smoke, comprising the following steps:

[0041] 1) Collecting mainstream cigarette smoke particulate matter under a specific environment, repeatedly extracting and washing the mainstream cigarette smoke particulate matter to obtain an extraction solution and a washing solution, combining and setting the volume, and preparing a sample solution to be tested;

[0042] 2) Determining the sample solution to be tested and the standard sample solution by inductively coupled plasma mass spectrometry to obtain the particle size and concentration of titanium dioxide nanoparticles in the sample solution to be tested;

[0043] 3) Determining the atomization efficiency by the standard sample solution, and calculating the number of titanium dioxide nanoparticles in the sample solution to be tested according to the pulse intensity, pulse area of the nanoparticles in the sample solution to be tested, and the mass of the measured nanoparticles in the nanoparticles.

[0044] The method for determining titanium dioxide nanoparticles in mainstream cigarette smoke provided by the present application captures mainstream cigarette smoke by using an electrostatic trapping device of a smoking machine, then uses ethanol to dissolve and extract the captured mainstream cigarette smoke, and determines by inductively coupled plasma mass spectrometry, thereby establishing a method for determining titanium dioxide nanoparticles in mainstream cigarette smoke.

[0045] In step 1) of the method for determining titanium dioxide nanoparticles in mainstream cigarette smoke of the present application, the mainstream cigarette smoke particulate matter is collected by using an electrostatic trapping device of a smoking machine. For example, a rotary disc smoking machine equipped with an electrostatic trapping system is used.

[0046] The parameters of the electrostatic trapping device of the smoking machine are set as follows: the suction capacity is 34.7-35.3 mL; the suction time is 1-4 s; and the suction curve is a bell-shaped curve. The suction capacity can be 34.7-34.8 mL, 34.8-34.9 mL, 34.9-35.0 mL, 35.0-35.1 mL, 35.1-35.2 mL, or 35.2-35.3 mL. In a preferred embodiment of the present application, the suction capacity is 35.0 mL. The suction time is 1-2 s, 2-3 s, or 3-4 s. In a preferred embodiment of the present application, the suction time is 2 s.

[0047] Each electrostatic collection tube in the electrostatic collection device of the cigarette smoking machine collects 20 cigarettes of mainstream smoke particulate matter.

[0048] In the method for determining the titanium dioxide nanoparticles in the mainstream smoke of the cigarette according to the present application, in step 1), the collection environment is at a temperature of 20-24℃ and a relative humidity of 55-65%.

[0049] In the method for determining the titanium dioxide nanoparticles in the mainstream smoke of the cigarette according to the present application, in step 1), the solvent used for extraction and washing is one or more of ethanol, methanol or isopropyl alcohol.

[0050] The extraction is performed once or twice. In a preferred embodiment of the present application, the extraction is performed once.

[0051] The washing is performed 3-5 times. In a preferred embodiment of the present application, the washing is performed 3 times.

[0052] In the method for determining the titanium dioxide nanoparticles in the mainstream smoke of the cigarette according to the present application, in step 2), the standard sample solution is prepared by gradually diluting the titanium dioxide nanoparticles with ethanol / water in a certain ratio.

[0053] The ratio of ethanol / water is 1:45-1:55, for example, 1:45-1:47, 1:47-1:49, 1:49-1:51, 1:51-1:53 or 1:53-1:55. In a preferred embodiment of the present application, the ratio of ethanol / water is 1:49. When the ratio of ethanol / water is 1:49, the nanoparticles can be dispersed better.

[0054] The standard sample solution is a titanium dioxide nanoparticle solution with a concentration gradient of 0, 1 ng / L, 3 ng / L, 5 ng / L and 10 ng / L.

[0055] In the specific implementation process, in order to uniformly disperse the nanoparticles, ultrasonic treatment is required for 5 minutes after each dilution, and the ultrasonic treatment process needs to be strictly controlled

[0056] In step 2), the inductively coupled plasma mass spectrometer is a multiple quadrupole inductively coupled plasma mass spectrometer. The multiple quadrupole inductively coupled plasma mass spectrometer has a single particle material analysis function. After the sample is injected and the sample solution is atomized, the titanium dioxide nanoparticles enter the plasma and are atomized and ionized, and each ionized nanoparticle generates a corresponding pulse signal. The number of pulses detected per unit time is proportional to the number of nanoparticles in the sample solution.

[0057] In step 2), the inductively coupled plasma mass spectrometer is further configured with an organic oxygenated sample injection system. The prepared organic oxygenated sample injection system can directly inject and analyze the organic system solution. Without the injection system, the operation cannot be realized.

[0058] In step 2), the determination conditions are as follows:

[0059] Ion source: ICP source; radio frequency power: 1400-1800 W, 1400-1500 W, 1500-1600 W, 1600-1700 W or 1700-1800 W; in a preferred embodiment of the present application, the radio frequency power is 1600 W;

[0060] Cooling gas: argon, flow rate: 14.0-18.0 L / min, 14.0-15.0 L / min, 15.0-16.0 L / min, 16.0-17.0 L / min or 17.0-18.0 L / min; in a preferred embodiment of the present application, the cooling gas flow rate is 16.0 L / min;

[0061] Auxiliary gas: argon, flow rate: 1.0-1.4 L / min, 1.0-1.1 L / min, 1.1-1.2 L / min, 1.2-1.3 L / min or 1.3-1.4 L / min; in a preferred embodiment of the present application, the auxiliary gas flow rate is 1.225 L / min;

[0062] Atomizing gas: argon, flow rate: 1.0-1.2 L / min, 1.0-1.05 L / min, 1.05-1.10 L / min, 1.10-1.15 L / min or 1.15-1.20 L / min; in a preferred embodiment of the present application, the atomizing gas flow rate is 1.05 L / min;

[0063] Total matrix gas: oxygen, flow rate: 0.02-0.08 L / min, 0.02-0.03 L / min, 0.03-0.04 L / min, 0.04-0.05 L / min, 0.05-0.06 L / min, 0.06-0.07 L / min or 0.07-0.08 L / min; in a preferred embodiment of the present application, the total matrix gas flow rate is 0.05 L / min;

[0064] Collision / reaction cell: ammonia, flow rate: 0.5-1.5 mL / min, 0.5-0.7 mL / min, 0.7-0.9 mL / min, 0.9-1.1 mL / min, 1.1-1.3 mL / min or 1.3-1.5 mL / min; in a preferred embodiment of the present application, the ammonia flow rate in the collision / reaction cell is 0.9 mL / min;

[0065] Rpq (low mass intercept) 0.4-0.5, 0.4-0.45 or 0.45-0.5; Analysis mode: mass shift, Q148 m / z, Q313 1 m / z; IGM voltage: hyperskimmer 5.0-6.0 V, 5.0-5.5 V or 5.5-6.0 V, OmniRing -200 to -250 V, -200 to -210 V, -210 to -220 V, -220 to -230 V, -230 to -240 V or -240 to -250 V; dwell time: 100 microseconds; scan time: 100 seconds; AFT voltage: 230-280 V, 230-240 V, 240-250 V, 250-260 V, 260-270 V or 270-280 V; sample rate: 0.05-0.10 ml / min, 0.05-0.06 ml / min, 0.06-0.07 ml / min, 0.07-0.08 ml / min, 0.08-0.09 ml / min or 0.09-0.10 ml / min.

[0066] In the method for determining the titanium dioxide nanoparticles in the mainstream smoke of cigarettes according to the present application, in step 3), the particle size and quantity of the titanium dioxide nanoparticles in the sample solution to be determined are calculated according to the pulse number of the nanoparticles in the sample solution to be determined, the particle signal and the mass of the nanoparticles to be determined.

[0067] The atomization efficiency is obtained by calculating the particle quantity, concentration and mass of the nanoparticle standard sample solution.

[0068] The method for determining the titanium dioxide nanoparticles in the mainstream smoke of cigarettes according to the present application can effectively determine the particle size and quantity of the titanium dioxide nanoparticles in the mainstream smoke of cigarettes, so as to facilitate the tobacco industry related technical personnel to effectively monitor the actual situation of the titanium dioxide in the mainstream smoke of cigarettes and provide strong technical support for the quality and safety evaluation of cigarettes in the tobacco industry.

[0069] Example 1

[0070] Selection of extraction solution

[0071] The main stream smoke of the cigarette sample was drawn in the experimental test environment with temperature of 20-22℃ and relative humidity of 60%-65%. The static electricity collection device of the smoking machine was set to have a suction capacity of 35.0 mL, a suction time of 2 s, and a suction curve of a bell-shaped curve. After the suction, the collected particle phase sample was divided into three parts, and the three parts were extracted by ethanol, methanol and isopropyl alcohol respectively. The extraction liquid and the washing liquid were transferred to a 25 mL polypropylene volumetric flask, and the sample solution was obtained by using ethanol, methanol and isopropyl alcohol for constant volume and shaking.

[0072] Preparation of the standard sample solution: titanium dioxide nanoparticles (particle size 60 nm) were diluted by ethanol / water, methanol / water and isopropyl alcohol / water respectively, and the concentration gradient of the titanium dioxide nanoparticle standard sample solution was 0, 1 ng / L, 3 ng / L, 5 ng / L and 10 ng / L.

[0073] Detection of the sample: the standard sample solution and the sample solution to be detected were determined by using a multiple quadrupole inductively coupled plasma mass spectrometer, and the parameters were set as follows:

[0074] Ion source: ICP source; radio frequency power: 1600 W;

[0075] Cooling gas: argon, flow rate: 16.0 L / min;

[0076] Auxiliary gas: argon, flow rate: 1.225 L / min;

[0077] Atomizing gas: argon, 1.05 L / min;

[0078] Full matrix sampling gas: oxygen, flow rate: 0.05 L / min;

[0079] Collision / reaction cell: ammonia, flow rate: 0.9 mL / min;

[0080] Rq 0.45; analysis mode: mass shift, Q1 48 m / z, Q3 131 m / z; IGM voltage: hyperskimmer 5.5 V, OmniRing-2 15 V; residence time: 100 microseconds; scanning time: 100 seconds; AFT voltage: 250 V; sample rate: 0.07 ml / min;

[0081] After the detection is completed, the concentration of the titanium dioxide nanoparticles in the sample solution to be detected is obtained. The atomization efficiency is determined by the standard sample solution, and the particle size (equivalent spherical diameter) of the titanium dioxide nanoparticles is calculated according to the pulse number of the sample solution to be detected, the particle signal, and the mass of the measured element in the nanoparticles of the sample solution to be detected. The specific calculation method is as follows:

[0082] Particle size (d p ) calculation method:

[0083]

[0084]

[0085] Wherein, m p : particle mass (fg); p p : particle density (i.e. the concentration of titanium dioxide nanoparticles in the sample solution to be detected, g / cm 3 ); η n : atomization efficiency; V: sample inlet flow rate (ml / min); l p : particle signal (cps); s: response time (cps / ppb); t d : integration time (sec); f d : mass fraction (molar mass of ion / molar mass of measured element); Np: particle number.

[0086] Specifically, see Table 1:

[0087] Table 1 Comparison of detection results of different extraction solutions

[0088] Analytical Indicators Ethanol Methanol Isopropanol Titanium dioxide nanoparticle average size (nm) 55.2 71.8 88.9 Titanium dioxide nanoparticle average size RSD (n=6) 6.6％ 8.3％ 23.7％

[0089] As can be seen from the data in Table 1, the titanium dioxide nanoparticles have large differences in different solvent systems, because the titanium dioxide nanoparticles are prone to agglomeration effect. The actual application effect of ethanol in the three extraction solutions is the best, and the average size RSD of titanium dioxide nanoparticles in ethanol is only 6.6%, which indicates that the titanium dioxide nanoparticles are uniformly dispersed in ethanol and do not have obvious agglomeration effect, which can meet the detection needs.

[0090] Example 2

[0091] Sample processing: The main stream smoke of cigarette samples 1-5 was drawn in the temperature of 20-22℃ and relative humidity of 60%-65% of the experimental test environment, and the static electricity collection device of the smoking machine was set to have a suction capacity of 35.0 mL, a suction time of 2 s, and a bell-shaped curve. After the suction was completed, the collected particle phase was extracted once and washed three times with ethanol, and the extraction liquid and washing liquid were transferred to a 25 mL polypropylene volumetric flask, which was then diluted with ethanol, shaken, and then the sample solution was obtained. At the same time, a blank control experiment was carried out (the blank control group only contained solvent ethanol)

[0092] Preparation of standard sample solution: TiO2 nanoparticles (particle size of 60 nm) were diluted with ethanol / water (volume ratio of 1:49) in stages, and each stage of dilution was ultrasonicated for 5 minutes, and the temperature during ultrasonication was controlled to be less than 25℃, to obtain TiO2 nanoparticle standard sample solutions with concentration gradients of 0, 1 ng / L, 3 ng / L, 5 ng / L, and 10 ng / L.

[0093] Detection of samples: The standard sample solution and the sample solution to be tested were determined by a multiple quadrupole inductively coupled plasma mass spectrometer, and the parameters were set as follows:

[0094] Ion source: ICP source; radio frequency power: 1600 W;

[0095] Cooling gas: argon, flow rate: 16.0 L / min;

[0096] Auxiliary gas: argon, flow rate: 1.225 L / min;

[0097] Atomizing gas: argon, 1.05 L / min;

[0098] Full-matrix sampling gas: oxygen, flow rate: 0.05 L / min;

[0099] Collision / reaction cell: ammonia, flow rate: 0.9 mL / min;

[0100] Rq 0.45; analysis mode: mass shift, Q1 48 m / z, Q3 131 m / z; IGM voltage: hyperskimmer 5.5 V, OmniRing-2 15 V; residence time: 100 microseconds; scan time: 100 seconds; AFT voltage: 250 V; sample rate: 0.07 ml / min;

[0101] After the detection was completed, the concentration of TiO2 nanoparticles in the sample solution to be tested was obtained. The atomization efficiency was determined by the standard sample solution, and the particle size (equivalent spherical diameter) and the number of TiO2 nanoparticles were calculated according to the pulse number, particle signal, and mass of the measured element in the nanoparticles of the sample solution to be tested. The results are shown in the following table:Figures 1-3 and Table 2 below. The calculation is as follows:

[0102]

[0103]

[0104] N p = l p / (V x η n );

[0105] Table 2: Test results of samples to be tested

[0106]

[0107] From the data of Example 2 and Table 2, it can be seen that the determination of titanium dioxide nanoparticles in the mainstream smoke of cigarettes by the method of the present application is accurate and reliable and has good applicability.

[0108] Figure 3 is the normalized frequency distribution of the nanoparticle size of Sample No. 4, and Figure 3 The median size of the nanoparticles calculated by the above method is basically equal to the value calculated by the above method.

[0109] Example 3

[0110] Repeatability test of determination method

[0111] The same method as in Example 2 was used to test the repeatability of the method by selecting cigarette samples, and the specific results are shown in Table 3.

[0112] Table 3: Results of repeatability test of method

[0113] Analytical Indicators 1# 2# 3# 4# 5# 6# RSD Titanium dioxide nanoparticle average size (nm) 55.0 56.2 58.9 51.5 60.3 53.2 6.0％ Titanium dioxide nanoparticle number (particles / mL) 61886 59243 57836 64751 55279 62514 5.3％

[0114] From the data in Table 3, it can be seen that the RSD of the number and average size of titanium dioxide nanoparticles by the method of the present application is less than 10%, which indicates that the determination method of the present application has good repeatability and can meet the detection needs.

[0115] In summary, the determination method of titanium dioxide nanoparticles in the mainstream smoke of cigarettes of the present application can effectively determine the size and number of titanium dioxide nanoparticles in the mainstream smoke of cigarettes, which provides convenience for tobacco industry technical personnel to effectively monitor the actual situation of titanium dioxide in the mainstream smoke of cigarettes and provides strong technical support for the quality and safety evaluation of cigarettes in the tobacco industry. Therefore, the present application effectively overcomes the shortcomings of the prior art and has high industrial utilization value.

[0116] The above embodiments are only illustrative of the principles of the present application and its efficacy, and are not intended to limit the present application. Any modification or change made by any person skilled in the art without departing from the spirit and scope of the present application shall be covered by the claims of the present application.

Claims

1. A method for determining titanium dioxide nanoparticles in mainstream cigarette smoke, characterized in that: The following steps are involved: 1) Repeatedly extract and clean the particulate matter in mainstream cigarette smoke collected under specific conditions to obtain the extract and cleaning solution, which are combined and fixed to volume to prepare the sample solution to be tested; 2) measuring the concentration of titanium dioxide nanoparticles in the sample solution to be tested using an inductively coupled plasma mass spectrometer (ICP-MS) to determine the concentration of titanium dioxide nanoparticles in the sample solution to be tested; the standard sample solution containing titanium dioxide nanoparticles of known concentration is prepared by gradually diluting the titanium dioxide nanoparticles with a certain ratio of ethanol to water, wherein the ratio of ethanol to water is 1:45 to 1:55; 3) Determine the atomization efficiency using a standard sample solution. Calculate the particle size and quantity of the titanium dioxide nanoparticles in the sample solution using the standard curve method based on the pulse intensity and pulse area of ​​the nanoparticles in the sample solution and the mass of the nanoparticles to be measured. The atomization efficiency is determined by using a standard sample solution, and the particle size and quantity of the titanium dioxide nanoparticles in the sample solution to be tested are calculated according to formulas (1), (2), and (3); The formula (1) is: ; The formula (2) is: ; The formula (3) is: ; Where m p : particle mass fg; ρ p : Particle density g / cm 3 ; η n : atomization efficiency; V: sample inlet flow rate ml / min; l p : particle signal cps; s: response time cps / ppb; t d : integration time sec; f d : mass fraction, molar mass of ion / molar mass of element to be measured; Np: number of particles; d p : Particle size.

2. The method for determining titanium dioxide nanoparticles in mainstream cigarette smoke according to claim 1, characterized in that: In step 1), the particulate matter in the mainstream smoke of the cigarette is collected by using an electrostatic collection device of a smoking machine.

3. The method for determining titanium dioxide nanoparticles in mainstream cigarette smoke according to claim 2, characterized in that: The parameters of the electrostatic capture device of the smoking machine are set as follows: a suction capacity of 34.7 to 35.3 mL; a suction time of 1 to 4 seconds; and a bell-shaped suction curve.

4. The method for determining titanium dioxide nanoparticles in mainstream cigarette smoke according to claim 2, characterized in that: Each electrostatic collection tube in the electrostatic collection device of the smoking machine collects particulate matter in the mainstream smoke of 20 cigarettes.

5. The method for determining titanium dioxide nanoparticles in mainstream cigarette smoke according to claim 1, characterized in that: The specific environment is: temperature 20°C~24°C, relative humidity 55%~65%.

6. The method for determining titanium dioxide nanoparticles in mainstream cigarette smoke according to claim 1, characterized in that: In step 1), the solvent used for extraction and washing is one or more of ethanol, methanol or isopropanol; And / or, in step 1), the extraction times are 1 to 2 times; And / or, in step 1), the cleaning frequency is 3 to 5 times.

7. The method for determining titanium dioxide nanoparticles in mainstream cigarette smoke according to claim 1, characterized in that: The standard sample solution is a titanium dioxide nanoparticle solution with a concentration gradient of 0, 1 ng / L, 3 ng / L, 5 ng / L, and 10 ng / L.

8. The method for determining titanium dioxide nanoparticles in mainstream cigarette smoke according to claim 1, characterized in that: In step 2), the inductively coupled plasma mass spectrometer is specifically a multi-quadrupole inductively coupled plasma mass spectrometer; And / or, in step 2), the inductively coupled plasma mass spectrometer is further equipped with an organic oxygen injection system.

9. The method for determining titanium dioxide nanoparticles in mainstream cigarette smoke according to claim 1, characterized in that: In step 2), the measurement conditions of the inductively coupled plasma mass spectrometer are: Ion source: ICP source; RF power: 1400~1800W; Cooling gas: argon, flow rate: 14.0~18.0L / min; Auxiliary gas: argon, flow rate: 1.0~1.4L / min; Nebulizer gas: argon, flow rate: 1.0~1.2L / min; Full matrix inlet gas: oxygen, flow rate: 0.02~0.08 L / min; Collision / reaction cell: ammonia, flow rate: 0.5~1.5 mL / min; Rpq 0.4~0.5; analysis mode: mass shift, Q1 48m / z, Q3 131m / z; IGM voltage: hyperskimmer 5.0~6.0V, OmniRing -200~-250V; dwell time: 100 microseconds; scan time: 100 seconds; AFT voltage: 230~280V; sample rate: 0.05~0.10ml / min.

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