CN113281287B - Method for pre-treatment of paper surface and method for determination of saccharin sodium content in paper surface - Google Patents

Abstract

The invention belongs to the field of detection and analysis, and specifically relates to a method for pre-treatment of paper surface, which includes the following steps: using 2 to 10 mL of water-methanol mixture to immerse the surface of 500 to 1300 mm2 ^paper for 5 to 60 seconds to separate the liquid; Among them, the volume ratio of water to methanol in the water-methanol mixture is 1:3 to 10:3; the liquid is centrifuged at a speed of 500 to 3000 rpm for 1 to 10 minutes, and the supernatant is collected; the supernatant is mixed with methyl bromide Phenol green solution reaction; wherein, the ratio of supernatant to bromocresol green is 100L: (0.01~0.3) mol. The invention also relates to a method for determining the saccharin sodium content in the surface layer of paper. The method of the present invention can quickly and accurately measure the saccharin sodium content in the surface layer of paper to quickly evaluate the impact of paper (such as cigarette tipping paper) on the sweet taste, and is easy to operate.

Description

Method for pre-treatment of paper surface and method for determination of saccharin sodium content in paper surface

Technical field

The invention belongs to the field of detection and analysis, and specifically relates to a method for pre-treating the surface layer of paper, and also relates to a method for measuring the saccharin sodium content in the surface layer of paper.

Background technique

In recent years, with the changes in cigarette consumer groups, consumers' consumption outlook has become more and more diverse, and the demand for personalization and customization has gradually become stronger. Among them, cigarette products with sweeteners added to cigarette tipping papers have suddenly emerged and are widely accepted by consumers.

In order to evaluate the impact of sweeteners in cigarette tipping papers on the smoking taste of cigarettes, it is usually necessary to measure the saccharin sodium content in cigarette tipping papers. At present, publicly reported literature mainly uses solvents to extract the sweetener contained in the entire cigarette tipping paper, and then detects it using high-performance liquid chromatography with an evaporative light scattering detector or high-performance liquid chromatography-tandem mass spectrometry. However, the existing methods require long detection times and complex operation steps, and cannot meet the requirements for rapid on-site analysis.

Contents of the invention

The inventor surprisingly found that the sweetener that can give consumers a sweet taste when smoking cigarettes is mainly distributed on the surface of the cigarette tipping paper (that is, the outermost layer of the cigarette tipping paper after being rolled into a cigarette) ), the sweetener inside the cigarette tipping paper is not easy to penetrate and affect the smoking taste. Therefore, one of the objects of the present invention is to provide a method for pre-treatment of the paper surface, which uses a certain proportion of water-methanol mixture to impregnate the paper surface, and the impregnating liquid is centrifuged to collect the supernatant, and the supernatant is mixed with bromocresol The green solution is used for measurement after reaction; on this basis, another object of the present invention is to provide a method for measuring the saccharin sodium content in the surface layer of paper. The reaction product obtained by the pre-treatment method can be detected quickly and accurately by a UV spectrophotometer. The saccharin sodium content in the surface layer of paper can be measured to quickly evaluate the impact of paper (such as cigarette tipping paper) on the sweet taste, and the operation is simple.

In order to achieve the above object, the first aspect of the present invention relates to a method for pre-treating the surface of paper, including the following steps:

Use 2 to 10 mL (e.g. 4 mL, 5 mL, 7 mL) of water-methanol mixture to soak the surface of the paper with an area of 500 to 1300 mm ² (e.g. 700 mm ² , 800 mm ² , 900 mm ² , 1000 mm ² , 1100 mm ² ) for 5 to 60 seconds (e.g. 10 , 20, 40, 50, 60 seconds) to separate the liquid; wherein the volume ratio of water to methanol in the water-methanol mixture is 1:3~10:3 (preferably 1:1~3:1, for example 2 :3, 3:1, 8:3, 7:3, 3:2, 1:1, 1:1.3);

Centrifuge the liquid at a speed of 500 to 3000 rpm (for example, 1000 rpm, 2000 rpm, 2500 rpm) for 1 to 10 minutes (for example, 2, 3, 4, 5, 6, 8 minutes), and collect the supernatant;

React the supernatant with bromocresol green solution; wherein, the ratio of supernatant to bromocresol green is 100L: (0.01~0.3)mol, for example, 100L:0.2mol, 100L:0.1mol, 100L:0.02mol, 100L:0.04mol.

The second aspect of the present invention relates to a method for pre-treating the surface of paper, which uses a device for extracting saccharin sodium from the surface of paper. The device includes a base, a cup, a positioning pin, a cover and a connecting unit; wherein,

The base is provided with a cavity with an upper part open;

The upper part of the cup body is open and located in the cavity of the base. The inner cross-sectional area of the cup body is 500-1300mm ² (for example, 700mm ² , 800mm ² , 900mm ² , 1000mm ² , 1100mm ² );

The positioning pin is arranged on the upper end of the base, and the upper end of the positioning pin is flush with the upper end of the cup body;

The cover body is suitable for covering the open upper part of the cup body and the upper end of the positioning pin, and a sealing gasket is provided on the inside of the cover body;

The connection unit includes a fixed part provided on the outer wall of the base, a snap ring and a protruding part provided on the edge of the cover. One end of the snap ring is rotationally connected to the fixed part and the other end is a free end. The snap ring The free end matches the size of the protrusion and is suitable for snap locking;

The method for pre-treating the paper surface layer includes the following steps:

Fill the cup with 2 to 10 mL (such as 3 mL, 4 mL, 5 mL, 7 mL) of water-methanol mixture, cover the open upper part of the cup with paper (the surface of the paper faces the cup), position the paper with positioning pins, and cover The upper cover body is sealed and locked through the connecting unit;

Turn the device upside down for 5 to 60 seconds (for example, 10, 20, 40, 50, 60 seconds), then return it to the upright position, open the cover, and remove the paper;

Centrifuge the liquid in the cup at a speed of 500 to 3000rpm (such as 1000rpm, 2000rpm, 2500rpm) for 1 to 10 minutes (such as 2, 3, 4, 5, 6, 8 minutes), and collect the supernatant;

React the supernatant with bromocresol green solution; wherein, the ratio of supernatant to bromocresol green is 100L: (0.01~0.3)mol, for example, 100L:0.2mol, 100L:0.1mol, 100L:0.02mol, 100L:0.04mol.

In some embodiments of the first or second aspect of the present invention, the concentration of the bromocresol green solution is 10 to 200 μM, such as 20 μM, 30 μM, 50 μM, 70 μM, 80 μM, 100 μM, 120 μM, 150 μM, and 170 μM.

In some embodiments of the first aspect or the second aspect of the present invention, the solvent used for the bromocresol green solution is water, preferably ultrapure water.

In some embodiments of the first aspect or the second aspect of the present invention, the paper is cigarette paper, preferably cigarette tipping paper.

In some embodiments of the second aspect of the present invention, in the device, the depth of the cup is at least 55mm, such as 55mm, 60mm, 70mm, 80mm, or 100mm.

In some embodiments of the second aspect of the present invention, in the device, at least two cavities are provided in the base, and there are at least two cups.

In some embodiments of the second aspect of the present invention, in the device, the two cavities are evenly arranged along the length direction of the base.

In some embodiments of the second aspect of the present invention, in the device, there is a gap between the bottom of the cup and the bottom of the cavity.

In some embodiments of the second aspect of the present invention, in the device, the upper end of the cup is higher than the upper end of the cavity.

In some embodiments of the second aspect of the present invention, in the device, a pair of connecting units is provided corresponding to each cup body, and is provided on opposite sides of the cup body for locking.

In some embodiments of the second aspect of the present invention, in the device, the positioning pins are arranged in pairs and are located between adjacent cavities.

In some embodiments of the second aspect of the present invention, in the device, there are two positioning pins, which are located between two adjacent cavities and are respectively located close to the opposite sides of the base. The distance between the axes of two adjacent cavities is equal.

In some embodiments of the second aspect of the present invention, in the device, the upper part (upper end) of the cup protrudes outward to form an annular hanging platform, and the upper part (upper end) of the inner cavity of the base expands outward. An annular depression is formed, and the annular hanging platform matches the size of the annular depression.

In some embodiments of the second aspect of the present invention, in the device, the upper part (upper end) of the base protrudes to both sides to form a handle.

In some embodiments of the second aspect of the present invention, in the device, the size of the base and the cover match.

In some embodiments of the second aspect of the present invention, in the device, the cup body is in the shape of a rectangular parallelepiped, and the cross section of the cup body is square.

The third aspect of the present invention relates to a method for determining the saccharin sodium content in the surface layer of paper, including:

Pre-treat the paper surface layer according to the method described in the first or second aspect of the present invention to obtain a reaction product;

Use an ultraviolet spectrophotometer to detect the reaction product to obtain an ultraviolet spectrophotometer; wherein, the gap width of the ultraviolet spectrophotometer is 1 to 2 nm (for example, 1 nm), and the detection range of the absorption wavelength is 300 to 800 nm (preferably 340 to 700 nm);

Calculate the saccharin sodium content in the surface layer of the paper based on the absorbance data at 441nm or 616nm absorption wavelength in the UV spectrogram.

In some embodiments of the third aspect of the present invention, the paper is cigarette paper, preferably cigarette tipping paper.

In some embodiments of the third aspect of the present invention, an external standard method is used to calculate the saccharin sodium content in the surface layer of the paper.

In some embodiments of the third aspect of the present invention, the series of standard solutions used in the external standard method are prepared through the following steps: taking sodium saccharin standard solutions of different concentrations and reacting with bromocresol green solution respectively; the bromocresol green solution is as follows described in the first or second aspect of the present invention.

In some embodiments of the third aspect of the present invention, in the preparation step of the series of standard solutions used in the external standard method, the ratio of saccharin sodium standard solution and bromocresol green is 100L: (0.01~0.3) mol, for example, 100L: 0.1mol, 100L: 0.02mol, 100L: 0.05mol.

In some embodiments of the third aspect of the present invention, the external standard method includes:

Use a UV spectrophotometer to detect a series of standard solutions (the operating conditions are the same as when detecting reaction products). Use the content of saccharin sodium and bromocresol green associates in the series of standard solutions (measured as saccharin sodium content) as the independent variable. The absorbance data at 441nm or 616nm absorption wavelength is used as the dependent variable for regression analysis to obtain a standard working curve;

Correspondingly, the absorbance data at 441nm or 616nm in the UV spectrogram of the reaction product is substituted into the standard working curve calculation to obtain the content of the saccharin sodium and bromocresol green associate in the reaction product (based on the saccharin sodium content), and further calculate Saccharin sodium content in the surface layer of paper.

In some embodiments of the third aspect of the present invention, the UV spectrophotometer uses a 1.0 cm quartz cuvette.

In the present invention, the cigarette tipping paper is a cigarette paper commonly used in this field and complies with the regulations of the industry standard YC 171-2014 "Cigarette Tipping Paper".

In the present invention, the surface layer of the cigarette tipping paper refers to the outermost layer of the cigarette tipping paper after being rolled into a cigarette.

The present invention has achieved one or more of the following beneficial effects:

The method of the present invention can quickly and accurately measure the saccharin sodium content in the surface layer of paper to quickly evaluate the impact of paper (such as cigarette tipping paper) on the sweet taste. It is easy to operate and can meet the requirements of rapid on-site analysis.

Description of the drawings

In order to make the content of the present invention easier to understand clearly, the present invention will be further described in detail below based on specific embodiments of the present invention and in conjunction with the accompanying drawings, wherein

Figure 1 is a schematic diagram of an embodiment of a device for extracting saccharin sodium from the surface layer of paper according to the present invention;

Figure 2 is a standard working curve diagram in Example 1;

Figure 3 is an ultraviolet spectrogram of the test solution of cigarette tipping paper samples 1 to 3 in Example 1;

Figure 4 is a standard working curve diagram in Example 3;

1-base, 2-cup body, 3-positioning pin, 4-cover body, 5-1-fixed part, 5-2-circlip, 5-3 protruding part, 6-cavity, 7-sealing gasket , 8-annular hanging platform, 9-annular depression, 10-handle.

Detailed ways

The embodiments of the present invention will be clearly and completely described below with reference to examples. Obviously, the described embodiments are only some of the embodiments of the present invention, rather than all the embodiments. The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application or uses. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts fall within the scope of protection of the present invention.

Figure 1 is a schematic diagram of an embodiment of a device for extracting saccharin sodium from the surface layer of paper according to the present invention;

The device for extracting saccharin sodium from the surface of paper includes a base 1, a cup 2, a positioning pin 3, a cover 4 and a connection unit;

The base 1 is provided with a cavity 6 with an open upper part;

The upper part of the cup body 2 is open and located in the cavity 6 of the base 1. The inner cross-sectional area of the cup body 2 is 900mm ² ;

The positioning pin 3 is arranged on the upper end of the base 1, and the upper end of the positioning pin 3 is flush with the upper end of the cup body 2;

The cover 4 is suitable for covering the open upper part of the cup 2 and the upper end of the positioning pin 3, and a sealing gasket 7 is provided on the inside of the cover 4;

The connection unit includes a fixed part 5-1 provided on the outer wall of the base 1, a snap ring 5-2 and a protruding part 5-3 provided on the edge of the cover 4. One end of the snap ring 5-2 is connected to the fixed part. The part 5-1 is rotatably connected, and the other end is a free end. The free end of the snap ring 5-2 matches the size of the protruding part 5-3 and is suitable for buckling and locking;

In this embodiment, two cavities 6 are provided in the base 1, and there are two cups 2;

In this embodiment, the two cavities 6 are evenly arranged along the length direction of the base 1;

In this embodiment, the depth of the cup body 2 is 55mm;

In this embodiment, there is a gap between the bottom of the cup 2 and the bottom of the cavity 6;

In this embodiment, the upper end of the cup body 2 is higher than the upper end of the cavity 6;

In this embodiment, a pair (two) connecting units are provided corresponding to each cup body 2, and are provided on opposite sides of the cup body 2 for locking;

In this embodiment, the positioning pins 3 are arranged in pairs, the number of which is two, and are located between two adjacent cavities 6 and respectively close to the opposite sides of the base 1. The positioning pins 3 are in contact with the two adjacent cavities. The distances between the 6 axes of the body are equal;

In this embodiment, the upper part (or upper end) of the cup body 2 protrudes outward to form an annular hanging platform 8, and the upper part (or upper end) of the inner cavity 6 of the base 1 expands outward to form an annular depression 9. The size of the annular hanging platform 8 matches the annular depression 9;

In this embodiment, the upper part (or upper end) of the base 1 protrudes to both sides to form a handle 10 , and the base 1 matches the size of the cover 4 .

In this embodiment, the cup body 2 is in the shape of a rectangular parallelepiped, and the cross section of the cup body 2 is square.

In this embodiment, the height of the positioning pin 3 is 10 mm.

Example 1

(1) Preparation of series of standard solutions:

Accurately weigh 0.1g (accurate to 0.1mg) saccharin sodium, dissolve it in a small amount of pure water, transfer it to a 100ml brown volumetric flask, and dilute it with pure water to a 1mg/mL saccharin sodium stock solution. Accurately transfer 2 ml of saccharin sodium stock solution into a 100 ml brown volumetric flask, and adjust the pure water volume to 200 μg/mL standard solution mother liquor. Pipette 0.1 mL, 0.2 mL, 0.5 mL, 1.0 mL, 4.0 mL, 5.0 mL, and 10.0 mL standard solution mother liquor into different 100 mL brown volumetric flasks respectively, and dilute to volume with pure water to obtain concentrations of 0.2 μg/mL and 0.4 respectively. A series of solutions of μg/mL, 1.0 μg/mL, 2.0 μg/mL, 8.0 μg/mL, 10.0 μg/mL, and 20.0 μg/mL; accurately pipette 100 μL of each solution and add it to 2.0 mL of 50 μM bromocresol green ( BCG) indicator (bromocresol green aqueous solution), shake well to obtain a series of standard solutions.

(2) Preparation of test solution:

Using the device shown in Figure 1, fill the cup with 5.0 mL of water-methanol mixture (the volume ratio of water to methanol is 7:3), cover the open upper part of the cup with paper (the surface of the paper faces the cup) and Position the paper with the positioning pin, cover the cover, seal and snap the locking device through the connecting unit; then turn the device upside down for 20 seconds, then return to the upright position, open the cover, remove the paper, take 4.0mL of the liquid in the cup and put it into a centrifuge tube, centrifuge for 2 minutes at 2000 r/min, accurately pipette 100 μL of the supernatant and add it to 2.0 mL of 50 μM bromocresol green (BCG) indicator (bromocresol green aqueous solution), shake well, and obtain the test product solution.

(3)Detection:

Put a series of standard solutions and test solutions into 1.0cm quartz cuvettes, and measure using a UV spectrophotometer (PerkinElmer Lambda 35). The operating conditions are: slit width 1nm, wavelength detection range 340-700nm, blank control is ultrapure water.

Using the content of the saccharin sodium and bromocresol green associate in the series of standard solutions (based on the saccharin sodium content) as the independent variable and the absorbance at 616nm wavelength as the dependent variable, a regression analysis was performed, as shown in Figure 2. The resulting standard working curve It is: y=0.0711x+0.4237.

Substitute the absorbance of the test solution at a wavelength of 616 nm into the standard working curve to calculate, and obtain the content of the saccharin sodium and bromocresol green associate in the test solution (based on the saccharin sodium content), and further calculate the cigarette interface Saccharin sodium content on the surface of the paper.

The saccharin sodium content in the surface layers of three types of cigarette tipping papers was measured according to the above method, and the results are shown in Table 1. The UV spectroscopic spectra of the test solutions corresponding to the three types of cigarette tipping papers are shown in Figure 3.

Table 1 Determination results of saccharin sodium content in surface layers 1-3 of cigarette tipping paper

Example 2

(1) Preparation of series of standard solutions:

Accurately weigh 0.1g (accurate to 0.1mg) saccharin sodium, dissolve it in a small amount of pure water, transfer it to a 100ml brown volumetric flask, and dilute it with pure water to a 1mg/mL saccharin sodium stock solution. Accurately transfer 2 ml of saccharin sodium stock solution into a 100 ml brown volumetric flask, and adjust the pure water volume to 200 μg/mL standard solution mother liquor. Pipette 0.1 mL, 0.2 mL, 0.5 mL, 1.0 mL, 4.0 mL, 5.0 mL, and 10.0 mL standard solution mother liquor into different 100 mL brown volumetric flasks respectively, and dilute to volume with pure water to obtain concentrations of 0.2 μg/mL and 0.4 respectively. A series of solutions of μg/mL, 1.0 μg/mL, 2.0 μg/mL, 8.0 μg/mL, 10.0 μg/mL, and 20.0 μg/mL, accurately pipette 200 μL of each solution and add it to 2.0 mL of 50 μM bromocresol green ( BCG) indicator (bromocresol green aqueous solution), shake well to obtain a series of standard solutions.

(2) Preparation of test solution:

Using the device shown in Figure 1, fill the cup with 5 mL of water-methanol mixture (the volume ratio of water to methanol is 6:4), cover the open upper part of the cup with paper (the surface of the paper faces the cup) and pass through Position the paper with the positioning pin, cover the cover, seal and engage the locking device through the connecting unit; then turn the device upside down for 20 seconds, then return to the upright position, open the cover, remove the paper, take 4 mL of the liquid in the cup and put it into the centrifuge tube, centrifuge at 2000 r/min for 2 minutes, accurately pipette 200 μL of the supernatant and add it to 2 mL of 20 μM bromocresol green (BCG) indicator (bromocresol green aqueous solution), shake well, and obtain the test solution.

(3)Detection:

Put a series of standard solutions and test solutions into 1.0cm quartz cuvettes, and measure using a UV spectrophotometer (PerkinElmer Lambda 35). The operating conditions are: slit width 1nm, wavelength detection range 340-700nm, blank control is ultrapure water.

Using the content of the saccharin sodium and bromocresol green associate in the series of standard solutions (based on the saccharin sodium content) as the independent variable and the absorbance at 616nm wavelength as the dependent variable, a regression analysis was performed to obtain a standard working curve.

Substitute the absorbance of the test solution at a wavelength of 616 nm into the standard working curve to calculate, and obtain the content of the saccharin sodium and bromocresol green associate in the test solution (based on the saccharin sodium content), and further calculate the cigarette interface Saccharin sodium content on the surface of the paper.

Determine the saccharin sodium content in the 4 to 6 surface layers of cigarette tipping paper according to the above method. The results are shown in Table 2.

Table 2 Determination results of saccharin sodium content in the 4-6 surface layers of cigarette tipping paper

Example 3

(1) Preparation of series of standard solutions:

Accurately weigh 0.1g (accurate to 0.1mg) saccharin sodium, dissolve it in a small amount of pure water, transfer it to a 100ml brown volumetric flask, and dilute it with pure water to a 1mg/mL saccharin sodium stock solution. Accurately transfer 2 ml of saccharin sodium stock solution into a 100 ml brown volumetric flask, and adjust the pure water volume to 200 μg/mL standard solution mother liquor. Pipette 0.1 mL, 0.2 mL, 0.5 mL, 1.0 mL, 4.0 mL, 5.0 mL, and 10.0 mL standard solution mother liquor into different 100 mL brown volumetric flasks respectively, and dilute to volume with pure water to obtain concentrations of 0.2 μg/mL and 0.4 respectively. A series of solutions of μg/mL, 1.0 μg/mL, 2.0 μg/mL, 8.0 μg/mL, 10.0 μg/mL, and 20.0 μg/mL, accurately pipette 500 μL of each solution and add it to 2.0 mL of 50 μM bromocresol green ( BCG) indicator (bromocresol green aqueous solution), shake well to obtain a series of standard solutions.

(2) Preparation of test solution:

Using the device shown in Figure 1, fill the cup with 5 mL of water-methanol mixture (the volume ratio of water to methanol is 5:5), cover the open upper part of the cup with paper (the surface of the paper faces the cup) and pass through Position the paper with the positioning pin, cover the cover, seal and engage the locking device through the connecting unit; then turn the device upside down for 20 seconds, then return to the upright position, open the cover, remove the paper, take 4 mL of the liquid in the cup and put it into the centrifuge tube, centrifuge at 2000r/min for 2 minutes, accurately pipette 500μL of the supernatant and add it to 2.0mL of 100μM bromocresol green (BCG) indicator (bromocresol green aqueous solution), shake well to obtain the test solution .

(3)Detection:

Put a series of standard solutions and test solutions into 1.0cm quartz cuvettes, and measure using a UV spectrophotometer (PerkinElmer Lambda 35). The operating conditions are: slit width 1nm, wavelength detection range 340-700nm, blank control is ultrapure water.

Using the content of the saccharin sodium and bromocresol green associate in the series of standard solutions (based on the saccharin sodium content) as the independent variable, and the absorbance at 441nm wavelength as the dependent variable, regression analysis was performed, and the standard working curve was obtained as y=-0.0266x +0.7563, as shown in Figure 4.

Substitute the absorbance of the test solution at 441nm wavelength into the standard working curve to calculate, and obtain the content of the saccharin sodium and bromocresol green associate in the test solution (based on the saccharin sodium content), and further calculate the cigarette interface Saccharin sodium content on the surface of the paper.

Determine the saccharin sodium content in the surface layers of cigarette tipping paper 7 to 9 according to the above method. The results are shown in Table 3.

Table 3 Determination results of saccharin sodium content in surface layers 7 to 9 of cigarette tipping paper

Test Example 1 Accuracy Verification

It is known that the surface and interior of the cigarette tipping paper 10-12 contain saccharin sodium. The design values of the saccharin sodium content in the surface layer (ink layer) of the cigarette tipping paper 10-12 are 25.0mg/m ² and 22.0mg/ respectively. m ² , 30.0 mg/m ² .

The method of Example 1 was used to measure the saccharin sodium content of the surface layer of cigarette tipping paper 10-12, and the results are shown in Table 4.

Table 4 Comparison between actual measurement results and design value of saccharin sodium content in the surface layer of cigarette tipping paper 10-12

It can be seen from Table 4 that the saccharin sodium content in the surface layer of cigarette tipping paper measured by the method of the present invention is relatively close to the design value of the saccharin sodium content in the surface layer, indicating that the method of the invention can accurately determine the saccharin sodium content in the surface layer of cigarette tipping paper.

Spiked recovery and repeatability of test example 2 method

1) Example 1 method:

In item (2) of Example 1, 5.0 mL of water-methanol mixture (the volume ratio of water to methanol is 7:3) was filled into multiple cups, and then the mixture was filled with 0.4 μg/mL, 2.0 μg/mL, Add saccharin sodium standard to multiple cup bodies at a standard addition amount of 10.0 μg/mL and mix well. Then, cover the surface of the cigarette tipping paper 3 in Example 1 toward the cup body on the open upper part of the cup body and align it with positioning pins. Position the paper, cover the cover, seal through the connecting unit and snap the locking device; then turn the device upside down for 20 seconds, then return to the upright position, open the cover, remove the paper, take 4mL of the liquid in the cup and put it into a centrifuge tube. Centrifuge at 2000 r/min for 2 minutes, accurately pipette 100 μL of the supernatant and add it to 2.0 mL of 50 μM bromocresol green (BCG) indicator (bromocresol green aqueous solution), shake well, and obtain multiple spiked test samples. solution; and then measure the content of the saccharin sodium and bromocresol green associate in the spiked test solution according to item (3) of Example 1 (based on the saccharin sodium content), and further calculate the spike recovery rate. Each concentration was measured three times in parallel, and the results are shown in Table 5. The background value represents the content of the association of saccharin sodium and bromocresol green in the test solution obtained during the process of measuring saccharin sodium on the surface layer of cigarette tipping paper 3 using the method of Example 1 (measured as saccharin sodium content).

Table 5 Spiked recovery and repeatability of the method

As can be seen from Table 5, the standard recovery rate of the method of the present invention is between 85.7-91.3%, and the relative standard deviation (RSD) of parallel samples is <5.6%, indicating that the determination method of the present invention has high accuracy, good repeatability, and stable results. reliable.

2) Method of Example 3:

In item (2) of Example 3, 5 mL of water-methanol mixture (the volume ratio of water to methanol is 5:5) was filled into multiple cups, and then the mixture was filled with 0.4 μg/mL, 2.0 μg/mL, 10.0 Add the saccharin sodium standard to multiple cups at a μg/mL standard addition amount and mix well. Then, cover the surface of the cigarette tipping paper 9 in Example 3 toward the cup body on the open upper part of the cup body, and align the paper with the positioning pin. Position, cover the lid, seal and engage the locking device through the connecting unit; then turn the device upside down for 20 seconds, then return to the upright position, open the lid, remove the paper, take 4mL of the liquid in the cup and put it into a centrifuge tube. Centrifuge at 2000 r/min for 2 minutes, accurately pipette 500 μL of the supernatant and add it to 2.0 mL of 100 μM bromocresol green (BCG) indicator (bromocresol green aqueous solution), shake well, and obtain multiple spiked test solutions. ; Then measure the content of the saccharin sodium and bromocresol green associate in the spiked test solution according to item (3) of Example 3 (based on the saccharin sodium content), and further calculate the spike recovery rate, each The concentration was measured three times in parallel, and the results are shown in Table 6. The background value represents the content of the association of saccharin sodium and bromocresol green in the test solution obtained during the process of measuring saccharin sodium on the surface layer of cigarette tipping paper 9 using the method of Example 3 (measured as saccharin sodium content).

Table 6 Spiked recovery and repeatability of the method

As can be seen from Table 6, the standard recovery rate of the method of the present invention is between 88.1-94.8%, and the relative standard deviation (RSD) of parallel samples is <5.1%, indicating that the determination method of the present invention has high accuracy, good repeatability, and stable results. reliable.

Obviously, the above-mentioned embodiments are only examples for clear explanation and are not intended to limit the implementation. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. An exhaustive list of all implementations is neither necessary nor possible. The obvious changes or modifications derived therefrom are still within the protection scope of the present invention.

Claims (13)

1. A method for pretreatment of a surface layer of paper, which adopts a device for extracting saccharin sodium from the surface layer of paper, wherein the device comprises a base, a cup body, a locating pin, a cover body and a connecting unit; wherein,,

a cavity with an open upper part is arranged in the base;

the upper part of the cup bodyThe cup body is opened and positioned in the cavity of the base, and the inner cross section area of the cup body is 500-1300 mm ² ；

The locating pin is arranged at the upper end of the base, and the upper end of the locating pin is flush with the upper end of the cup body;

the cover body is suitable for covering the open upper part of the cup body and the upper end of the positioning pin, and a sealing gasket is arranged at the inner side of the cover body;

the connecting unit comprises a fixing part arranged on the outer side wall of the base, a clamping ring and a protruding part arranged at the edge of the cover body, one end of the clamping ring is rotationally connected with the fixing part, the other end of the clamping ring is a free end, and the free end of the clamping ring is matched with the protruding part in size and is suitable for buckling and locking;

the method for preprocessing the surface layer of the paper comprises the following steps:

2-10 mL of water-methanol mixed solution is filled in the cup body, paper is covered on the open upper part of the cup body and positioned by a positioning pin, the cover body is covered, and the cup body is sealed and locked by the connecting unit; wherein the volume ratio of water to methanol in the water-methanol mixed solution is 1:3-10:3;

inverting the device for 5-60 seconds, then restoring to be placed in the forward direction, opening the cover body, and removing paper;

taking liquid in the cup body, centrifuging at a rotating speed of 500-3000 rpm for 1-10 minutes, and collecting supernatant;

reacting the supernatant with bromocresol green solution; wherein the ratio of the supernatant to bromocresol green is 100L (0.01-0.3) mol.

2. The method according to claim 1, wherein the concentration of bromocresol green solution is 10 to 200 μm.

3. The method of claim 1, wherein the solvent used for the bromocresol green solution is water.

4. The method according to claim 1, wherein the solvent used for the bromocresol green solution is ultrapure water.

5. The method of claim 1, wherein the paper is a cigarette paper.

6. The method of claim 1, wherein the paper is tipping paper for cigarettes.

7. The method of claim 1, wherein at least two cavities are provided in the base and at least two cups are provided in the device.

8. The method of claim 1, wherein a pair of connection units is provided for each cup in the device.

9. The method of claim 1, wherein the alignment pins are provided in pairs and between adjacent cavities in the device.

10. The method of claim 1, wherein in the device, the upper portion of the cup body protrudes outward to form an annular hanging table, the upper portion of the inner cavity in the base expands outward to form an annular recess, and the annular hanging table is matched with the size of the annular recess.

11. A method for determining the sodium saccharin content of a paper surface layer comprising:

pretreatment of the surface layer of paper according to the method of any one of claims 1 to 10 to obtain a reaction product;

detecting the reaction product by an ultraviolet spectrophotometer to obtain an ultraviolet spectrophotometry chart; wherein the width of the crack of the ultraviolet spectrophotometer is 1-2 nm, and the detection range of the absorption wavelength is 300-800 nm;

and calculating the saccharin sodium content in the surface layer of the paper according to absorbance data of the absorption wavelength of 441nm or 616nm in the ultraviolet spectroscope.

12. The method of claim 11, wherein the sodium saccharin content in the paper surface layer is calculated using an external standard method.

13. The method of claim 11 or 12, wherein the ultraviolet spectrophotometer employs a 1.0cm quartz cuvette.