CN102680561A - Method for measuring boric acid content in water-based adhesive for cigarettes - Google Patents

Abstract

The invention discloses a method for measuring boric acid content in water-based adhesive for cigarettes. Accurately weighing a certain amount of water-based adhesive sample for tobacco, placing the sample in a microwave digestion tank, and adding nitric acid (HNO)₃) And hydrogen peroxide (H)₂O₂) After pre-digestion, screwing and sealing the mixture, placing the mixture into a microwave digestion instrument for digestion to obtain a water-based adhesive sample solution for cigarettes, and introducing the sample solution into an inductively coupled plasma emission spectrum mass spectrometer for detection: detecting the characteristic ionic strength of boron (B) element and online internal standard germanium (Ge) element in the sample solution, quantitatively determining by adopting an internal standard calibration curve method, calculating the content of the B element in the water-based adhesive for cigarettes, and obtaining HBO (hydrogen bromide oxide) through the conversion coefficient₃The content of (a). The method has the advantages of accurate test, simple operation, high sensitivity and good repeatability. Is suitable for technical personnel in tobacco industry and tobacco adhesive production enterprises to carry out HBO treatment on water-based adhesive for tobacco₃The quantitative determination is carried out, and the blank of the technical field is filled.

Description

A kind of determination method of boric acid content in water-based glue for tobacco

technical field

The invention belongs to the technical field of physical and chemical testing of cigarette materials, and in particular relates to a method for measuring boric acid content in water-based glue for cigarettes.

Background technique

With the widespread concern on "smoking and health" worldwide and the official signing of the FCTC agreement, the control of elements harmful to human health in cigarette products has become the focus of the tobacco industry. Tobacco water-based glue is an indispensable substance in the cigarette production process, and it is also a key material that reflects the characteristics of cigarette technology. Therefore, the quality control of water-based glue has always been a matter of great concern to tobacco companies. At present, most of the adhesives used in domestic cigarette production are chemically synthesized water-based adhesives. According to the relevant testing standards for tobacco water-based adhesives, viscosity measurement is an important indicator. When the value reaches the corresponding technical standard, boric acid will be added to adjust its viscosity, thereby improving the adhesive performance of the water-based adhesive. However, in the process of cigarette production, excessive boric acid will produce strong irritation, causing skin irritation, conjunctivitis, bronchial Inflammation, and at the same time, if the human body ingests excessive boric acid, it will pose a certain threat to human life. Therefore, the analysis and monitoring of boric acid residues in tobacco water-based adhesives are of great significance, both in terms of the sensory quality of cigarette products and the safety of cigarette smoking.

At present, domestic and foreign methods for the determination of boric acid mainly include methylimine-H method, 3-methoxymethylimine-H method and curcumin method. Its application is limited; the determination objects of these methods are mostly the detection of boric acid in environmental samples and food. It is also reported to use thin layer chromatography and monopolar scanning polarography to determine boric acid in grain and mineral water, but the operation is troublesome, there are many interferences, and the number of detectable samples is small. There is no report on the determination method and patent of boric acid in the tobacco water-based glue. Therefore, it is of great significance to develop an assay method with good stability, high selectivity, fast accuracy, and no need for organic reagents to improve the quality and safety of cigarette products and further explore the harm reduction of cigarettes.

Contents of the invention

The purpose of the present invention is to provide a method for determining the content of boric acid in tobacco water-based adhesives for the technical deficiencies of existing methods such as cumbersome sample pretreatment, low sensitivity, and poor reproducibility. Production enterprises provide data support for the selection and monitoring of tobacco water-based adhesives, and then provide technical support for a more scientific assessment of the health hazards of smoking, as well as for the selection of auxiliary materials and harm reduction and coke reduction in cigarette product research and development.

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

Unless otherwise stated, the percentages used in the present invention are all percentages by weight.

A method for assaying boric acid content in water-based glue for tobacco, comprising the following steps:

(1) Weigh 0.2g~0.6g sample, accurate to 0.1mg, put it in a microwave digestion tank, add 5mLHNO ₃ and 2mLH ₂ O ₂ to digest for 12~16h;

(2) Tighten and seal the microwave digestion tank described in step (1) and place it in a microwave digestion instrument for digestion, while making a blank solution without adding a sample;

(3) After the digestion is completed, take out the digestion tank after the temperature drops to room temperature, transfer the sample solution directly to a 50mL PET volumetric flask, rinse the digestion tank with pure water, transfer the cleaning solution to the volumetric flask, and then set the solution with pure water. volume, shake well to get the sample solution;

(4) Preparation of standard solution: use B standard stock solution, dilute it step by step with 5% _HNO3 to B standard solution;

(5) Draw the calibration curve: adopt Ge standard solution online internal standard to add, internal standard Ge use concentration is 15 μ g/L, draw the standard blank solution and the standard solution of different concentration B respectively, inject in the inductively coupled plasma mass spectrometer, wait for The ratio of the measured element B content to the corresponding internal standard element Ge content is the abscissa, the ratio of the mass-to-charge ratio intensity of the element to be measured to the corresponding internal standard element Ge mass-to-charge ratio is the ordinate, and the calibration curve of B is established; Carry out linear regression to obtain the regression equation of B, and R should not be less than 0.999;

(6) Measure the ionic strength of the B element and the internal standard Ge element in the step (3) sample solution according to the method of step (5), and use the obtained calibration curve to calculate and obtain the B element concentration in the tobacco water-based glue sample solution; the calculation formula is as follows:

The content of boric acid in the tobacco water-based glue is represented by X, and is calculated according to formula (I):

$\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; =</span>\frac{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; C</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; V</span>}}{\mathrm{<span\; class="notranslate">\; 1000</span>}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; I</span>}<span\; class="notranslate">\; )</span>$

In the formula:

X——the content of boric acid in the tobacco water-based adhesive, in micrograms per gram (μg/g);

C—concentration of the measured element in the sample solution of the tobacco water-based adhesive, in micrograms per liter (μg/L);

C ₀ —concentration of the measured element in the blank solution, in micrograms per liter (μg/L);

V——the constant volume in the tobacco water-based adhesive sample solution, in milliliters (mL);

m - the mass of the tobacco water-based adhesive sample, in grams (g);

F——The coefficient of converting boron into boric acid, and the coefficient of boric acid is 5.72.

As a preferred technical solution, the digestion program of the microwave digestion system in the step (2) is composed of the following four steps:

(1) The heating time from room temperature to 100°C is 5 minutes, and the holding time is 5 minutes.

(2) The heating time from 100°C to 135°C is 5 minutes, and the holding time is 5 minutes.

(3) The heating time from 135°C to 165°C is 5 minutes, and the holding time is 5 minutes.

(4) The heating time from 165°C to 185°C is 10 minutes, and the holding time is 25 minutes.

As a preferred technical scheme, the specific steps for preparing the standard solution in the step (4): accurately draw 1mL of the boron standard stock solution into a 100mL volumetric flask, dilute with 1% _HNO3 solution to the mark, and obtain 1 μg/mL standard solution; respectively pipette boron standard solution 0, 0.1, 0.2, 0.5, 1.0, 2.0mL in a 100mL plastic volumetric flask, and use 5% _HNO3 solution to set the volume to the mark, the solution concentration in the volumetric flask is 0 μg/L, 1μg/L, 2μg/L, 5μg/L, 10μg/L, 20μg/L B standard solution.

As a preferred technical solution, the working conditions of the inductively coupled plasma mass spectrometer in the step (5) are: vacuum degree (Torr), atomizer flow rate (L/min), auxiliary gas flow rate (L/min), plasma Bulk gas flow (Ar) (L/min), RF power (W), scan mode, scan times, ion lens voltage (V), pulse voltage (V), repetition times, cleaning time (s), CeO oxide, Double charges (Ba++) are ≤1.2×10 ^-6 , 0.66～0.68, 1.2, 15, 1300, Peak Jumping, 20, 6.0～6.4, 950, 4, 20, ≤0.03, ≤0.03; at the same time, in order to effectively To reduce the influence of signal drift and matrix effect on the determination, Ge was added online as an internal standard.

As a preferred technical solution, the vessels in the measurement method are all plastic containers, and after being soaked in 25% _HNO3 solution for 12-16 hours, they are washed with pure water for later use; since boron pollution is easily introduced into glassware, boron It is easy to accumulate in the atomizer and cone of the instrument, resulting in memory effect. Therefore, after measuring the solution with high boron content, use 5% nitric acid to flush the sampling system to eliminate the memory effect of boron.

The invention overcomes the defects of the existing methods, establishes a method with high efficiency, high sensitivity and high accuracy, and uses ICP-MS detection technology to measure the content of boric acid in the tobacco water-based glue, making the pretreatment simpler, more efficient and more complete , high recovery rate, the elements to be measured are not easily affected by exogenous pollution and loss, and ICP-MS is easy to operate, high precision, good stability, and low detection limit. The recovery rate, relative standard deviation, and detection limit are 105.59 %, 4.52%, 0.12μg/L, suitable for the technical personnel of the tobacco industry and tobacco adhesive manufacturers to quantitatively determine HBO ₃ in the water-based adhesive for tobacco.

The invention fills up the gap in the domestic ICP-MS method in the technical field of boric acid detection in tobacco water-based glue, and has important significance for formulating new standards for the detection of harmful and restricted substances in tobacco water-based glue, and at the same time protects human health , to promote the healthy development of cigarette products and tobacco water-based rubber industry in my country's tobacco industry and to promote foreign trade has very practical significance.

Detailed ways

The present invention will be further described in detail through the examples below, but the examples are not intended to limit the technical solution of the present invention. All transformations made based on the teaching of the present invention shall belong to the protection scope of the present invention.

Example 1

1. The use of instruments and instrument working conditions

1.1 Instrument used: Inductively coupled plasma mass spectrometer (ICP-MS), model: PE Elan DRC-e

1.2 Instrument working conditions, see Table 1

Table 1 The working condition parameters of ICP-MS

Working condition parameters Parameters Set value Value Vacuum (Torr) ≤1.2×10 ^-6 Atomizer flow(L·min ^-1 ) 0.68 Auxiliary gas flow(L·min ^-1 ) 1.2 Plasma gas flow(Ar)(L·min ^-1 ) 15 RF power (W) 1300 scan mode Peak Jumping Number of scans 20 Ion lens voltage (volts) 6.3 Pulse voltage (volts) 950 repeat times 4 Cleaning time/s 20 CeO oxide ≤0.03 double charge (Ba++) ≤0.03

2. Using Reagents

2.1 The experimental water is the second-grade water specified in GB6682, and the chemical reagents are all above-grade pure.

2.2 Boron (B) standard stock solution is 100μg/mL (national standard reagent, GBW).

2.3B standard series solution, using 2.2 standard stock solution (GBW), diluted step by step with 5% _HNO3 to form a standard series solution with B element concentrations of 0, 1, 2, 5, 10, 20 μg/L.

2.465% (mass fraction, the same below) HNO ₃ and 30% H ₂ O ₂ .

2.510μg/mL Ge internal standard solution (diluted to 15ng/mL with 5% HNO3 before use).

2.6 Instrument tuning solution (US PE company, containing Be, Ce, Co, In, Pb, Mg, Rh, U 1 μg/L, Ba 10 μg/L medium 0.5% HNO ₃ ).

3. Sample Digestion

Weigh 0.2g sample, accurate to 0.1mg, put it in a microwave digestion tank, add 5mL HNO ₃ and 2mL H ₂ O ₂ to digest for 12h, then screw the microwave digestion tank tightly and place it in a microwave digestion instrument for digestion. The program steps are as follows, and a blank solution without sample solution is made at the same time.

(1) The heating time from room temperature to 100°C is 5 minutes, and the holding time is 5 minutes.

(2) The heating time from 100°C to 135°C is 5 minutes, and the holding time is 5 minutes.

(3) The heating time from 135°C to 165°C is 5 minutes, and the holding time is 5 minutes.

(4) The heating time from 165°C to 185°C is 10 minutes, and the holding time is 25 minutes.

After the digestion is completed, take out the digestion tank after the temperature drops to room temperature, transfer the sample solution directly to a 50mL PET volumetric flask, rinse the digestion tank with pure water, transfer the cleaning solution to the volumetric flask, and then dilute to the mark with pure water , mix well.

4. Calibration Curve and Sample Determination

Under the conditions of Table 1., add the internal standard solution (2.5) online, inject the B standard blank solution, the B standard series solution, the tobacco water-based glue sample solution and the reagent blank solution into the inductively coupled plasma mass spectrometer, and use the analyte B The ratio of the content of B to the content of the internal standard Ge element is the abscissa, the ratio of the mass-to-charge ratio of the element B to be measured to the mass-to-charge ratio of the internal standard Ge element is the ordinate, and the working curve of boron is established. Linear regression was performed on the calibration data to obtain the regression equation of boron: Y=0.054411X+0.000002, the correlation coefficient R and the detection limit were 0.999976 and 0.12 μg/L, respectively.

The measured ionic strength of the B element in the sample solution and the internal standard Ge element is calculated using the obtained calibration curve to obtain the B element concentration in the tobacco water-based glue sample solution, and then the result calculation formula is used to calculate the concentration of boric acid in the tobacco water-based glue. Content, the results are shown in Table 3.

Calculated as follows:

The content of boric acid in the tobacco water-based glue is represented by X, and is calculated according to formula (I):

$\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; =</span>\frac{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; C</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; V</span>}}{\mathrm{<span\; class="notranslate">\; 1000</span>}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; I</span>}<span\; class="notranslate">\; )</span>$

In the formula:

X——the content of boric acid in the tobacco water-based adhesive, in micrograms per gram (μg/g);

C—concentration of the measured element in the sample solution of the tobacco water-based adhesive, in micrograms per liter (μg/L);

C ₀ —concentration of the measured element in the blank solution, in micrograms per liter (μg/L);

V——the constant volume in the tobacco water-based adhesive sample solution, in milliliters (mL);

m - the mass of the tobacco water-based adhesive sample, in grams (g);

F——The coefficient of converting boron into boric acid, and the coefficient of boric acid is 5.72.

The calculation result retains three significant figures.

The results of the measured boric acid in the tobacco water-based adhesive sample 1 are shown in Table 2.

Table 2 Detection results of boric acid content in water-based adhesive for tobacco

Sample serial number compound Content (μg/g) 1 HBO ₃ 2.851

Example 2

The difference with Example 1 is:

1. Measuring method Under the working conditions of the instrument: the nebulizer flow rate is 0.67L/min, and the ion lens voltage is 6.4v.

2. Under the preparation of the sample solution: weigh 0.4g of the tobacco water-based adhesive sample, accurate to 0.1mg, and pre-digest for 14h.

3. Others are the same as in Example 1.

4. Measure the boron standard blank solution, boron standard series solution, blank sample solution, and tobacco water-based glue sample solution according to the instrument working conditions of the "measurement method" item of this embodiment, and obtain the calibration curve regression equation: Y=0.010934X -0.000001, correlation coefficient R: 0.999991 The content of boric acid in the tobacco water-based adhesive was converted by the result calculation formula, and the content of boric acid in the tobacco water-based adhesive of 10 different brands was measured. The results are shown in Table 4.

Analysis results of B and HBO ₃ in table 4 tobacco water-based adhesive samples (μg/g)

Note: N.D. means not detected.

Example 3

The difference with Example 1 is:

1. Measuring method Under the working conditions of the instrument: the nebulizer flow rate is 0.66L/min, and the ion lens voltage is 6.0v.

2. Under the item of sample solution preparation: weigh 0.6g of tobacco water-based glue sample, accurate to 0.1mg, and pre-digest for 16h.

3. Others are the same as in Example 1.

4. Measure the boron standard blank solution, boron standard series solution, blank sample solution, and tobacco water-based glue sample solution according to the instrument working conditions of the "measurement method" item of this embodiment, and obtain the calibration curve regression equation: Y=0.065521X +0.000003, R: 0.999983, the content of boric acid in the tobacco water-based adhesive was converted by the result calculation formula, and the content of boric acid in the tobacco water-based adhesive sample No. 12 was measured to be 1.790 μg/g.

5. Precision test:

Weigh six 0.5g parallel samples of the No. 10 tobacco water-based adhesive sample, accurate to 0.1mg, and test according to this Example 3 "Preparation of sample solution" and the determination method instrument working condition parameters, and the results are shown in Table 5.

The precision test result of table 5 method and the determined value of tea standard substance

6. Stability test

Select No. 12 cigarette water-based glue sample, weigh 0.5g, accurate to 0.1mg, and test according to the "preparation of sample solution" in this example 3 and the parameters of the instrument's working conditions in the determination method, and repeat the test on the same sample within 48 hours , the results are shown in Table 6.

Table 6 Stability test results of boric acid content in water-based adhesive for tobacco

6. Recovery test

The recovery rate experiment of the method adopts the matrix addition method. Take three samples of No. 12 cigarette water-based glue, and add B standard solutions with three different concentrations of high, medium and low respectively. The working condition parameter items are tested, and the results are shown in Table 7.

Table 7 recovery rate test result

The test results of Examples 1, 2, and 3 show that the quantitative determination of the boric acid content in the tobacco water-based glue by the method of the present invention is accurate, sensitive, precise, and easy to operate.

Claims (5)

1. a method for assaying boric acid content in water-based glue for tobacco, comprising the following steps: (1) Weigh 0.2g~0.6g sample, accurate to 0.1mg, put it in a microwave digestion tank, add 5mLHNO ₃ and 2mLH ₂ O ₂ to digest for 12~16h; (2) Tighten and seal the microwave digestion tank described in step (1) and place it in a microwave digestion instrument for digestion, while making a blank solution without adding a sample; (3) After the digestion is completed, take out the digestion tank after the temperature drops to room temperature, transfer the sample solution directly to a 50mL PET volumetric flask, rinse the digestion tank with pure water, transfer the cleaning solution to the volumetric flask, and then set the solution with pure water. volume, shake well to get the sample solution; (4) Preparation of standard solution: use B standard stock solution, dilute it step by step with 5% _HNO3 to B standard solution; (5) Draw the calibration curve: adopt Ge standard solution online internal standard to add, internal standard Ge use concentration is 15 μ g/L, draw the standard blank solution and the standard solution of different concentration B respectively, inject in the inductively coupled plasma mass spectrometer, wait for The ratio of the measured element B content to the corresponding internal standard element Ge content is the abscissa, the ratio of the mass-to-charge ratio intensity of the element to be measured to the corresponding internal standard element Ge mass-to-charge ratio is the ordinate, and the calibration curve of B is established; Carry out linear regression to obtain the regression equation of B, and R should not be less than 0.999; (6) Measure the ionic strength of the B element and the internal standard Ge element in the step (3) sample solution according to the method of step (5), and use the obtained calibration curve to calculate and obtain the B element concentration in the tobacco water-based glue sample solution; the calculation formula is as follows: The content of boric acid in the tobacco water-based glue is represented by X, and is calculated according to formula (I): $\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; =</span>\frac{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; C</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; V</span>}}{\mathrm{<span\; class="notranslate">\; 1000</span>}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; I</span>}<span\; class="notranslate">\; )</span>$ In the formula: X——the content of boric acid in the tobacco water-based adhesive, in micrograms per gram (μg/g); C—concentration of the measured element in the sample solution of the tobacco water-based adhesive, in micrograms per liter (μg/L); C ₀ —concentration of the measured element in the blank solution, in micrograms per liter (μg/L); V——the constant volume in the tobacco water-based adhesive sample solution, in milliliters (mL); m - the mass of the tobacco water-based adhesive sample, in grams (g); F——The coefficient of converting boron into boric acid, and the coefficient of boric acid is 5.72. 2. the assay method of boric acid content in the tobacco water-based glue according to claim 1, is characterized in that: in described step (2), microwave digestion system digestion procedure is made of following four steps: (1) The heating time from room temperature to 100°C is 5 minutes, and the holding time is 5 minutes; (2) The heating time from 100°C to 135°C is 5 minutes, and the holding time is 5 minutes; (3) The heating time from 135°C to 165°C is 5 minutes, and the holding time is 5 minutes; (4) The heating time from 165°C to 185°C is 10 minutes, and the holding time is 25 minutes. 3. the assay method of boric acid content in the tobacco water-based glue according to claim 1, is characterized in that: the concrete step of preparing standard solution in described step (4): accurately draw 1mL boron standard stock solution to the volumetric flask of 100mL , dilute with 1% HNO ₃ solution to the mark to obtain a standard solution of 1 μg/mL; pipette boron standard solutions 0, 0.1, 0.2, 0.5, 1.0, 2.0mL into 100mL plastic volumetric flasks, and use 5% The HNO ₃ solution was adjusted to the mark, and the solution concentration in the volumetric flask was 0μg/L, 1μg/L, 2μg/L, 5μg/L, 10μg/L, 20μg/L B standard solution. 4. the assay method of boric acid content in the water-based glue for tobacco according to claim 1, is characterized in that: the operating condition of inductively coupled plasma mass spectrometer in described step (5) is: degree of vacuum, atomizer flow rate, Auxiliary gas flow, plasma gas flow, RF power, scan mode, scan times, ion lens voltage, pulse voltage, repetition times, cleaning time, CeO oxide, double charge ≤1.2×10 ^-6 , 0.66～0.68, 1.2, 15, 1300, Peak Jumping, 20, 6.0～6.4, 950, 4, 20, ≤0.03, ≤0.03; at the same time, in order to effectively reduce the influence of signal drift and matrix effect on the determination, Ge was added online as an internal standard. 5. the assay method of boric acid content in the water-based glue for tobacco according to claim 1 is characterized in that: in the described assay method, utensils are all plastic containers, and through 25% _HNO After solution soaking 12～16h, use Wash it with pure water and use it for later use; after measuring the solution with high boron content, use 5% nitric acid to flush the sampling system to eliminate the memory effect of boron.