CN115060830A

CN115060830A - Method for detecting VOCs solvent residues of paper

Info

Publication number: CN115060830A
Application number: CN202210785486.9A
Authority: CN
Inventors: 周家宝; 李建云; 杨耿慧; 张义光
Original assignee: Yunnan Dali Tianxin Packaging Material Co ltd
Current assignee: Yunnan Dali Tianxin Packaging Material Co ltd
Priority date: 2022-07-05
Filing date: 2022-07-05
Publication date: 2022-09-16

Abstract

The invention relates to a method for detecting VOCs solvent residues of paper, and belongs to the technical field of paper detection. The method comprises the steps of preparing and processing a standard sample matrix, preparing a series of standard solutions, preparing a series of standard solution sample bottles, editing a static headspace sample injector sequence, establishing a standard curve, detecting a sample to be detected and the like. The invention solves the problem of systematic superposition and rise of detection results in the headspace sampling process, solves the problem of mutual interference between samples and reduces the difference between the detection value and the actual value of the samples. The application of the invention strengthens the stability control force of the VOCs detection equipment, improves the refined detection level of the VOCs sample, reduces the influence of the attached pollution of the detection instrument, prolongs the service life of the instrument, saves the maintenance cost and is easy to popularize and apply.

Description

Method for detecting VOCs solvent residues of paper

Technical Field

The invention belongs to the technical field of paper detection, and particularly relates to a method for detecting VOCs solvent residues of paper.

Background

With the continuous and deep understanding of the industry and consumers on the environmental protection concept, the detection requirements on paper are more and more strict. At present, the existing related method for detecting the residual solvent of the paper VOCs in the industry strictly and uniformly regulates the sample preparation method, the sample introduction condition, the sample introduction amount and the like of a single sample, but does not relate to the problems of whether the samples and the samples mutually influence or not, and the detection result has deviation after continuous sample introduction. In actual detection work, due to various reasons such as production cycle, sample injection cycle and the like, continuous sample injection is often carried out for 24 hours in the detection of the VOCs solvent residue of the paper, and the condition of front influence and back influence is formed between two adjacent samples, so that the detection results of the following samples are accumulated and increased gradually, the detection results are deviated, the difference between the detection values and the actual values is obviously increased, and even wrong detection results are generated; especially when a system method standard curve is established, the influence is more obvious. After the standard sample detection is continuously carried out, the detection concentration of the standard sample can have positive deviation, the VOCs standard curve can be systematically increased, the detection value of the sample can be lower under the environment of a higher curve system, the risk that the product detection content is qualified but the actual content exceeds the standard finally occurs, and when the detection concentration of the standard sample has positive deviation, the correlation coefficient of the VOCs standard curve can be reduced, even the correlation coefficient is possibly below 0.995, and the standard requirement cannot be met. In the aspect of safety and sanitation indexes of products, serious risks can occur, the monitoring capability of the quality stability of the products cannot be guaranteed, and the quality control level of various products is seriously hindered. Therefore, how to overcome the defects of the prior art is a problem which needs to be solved in the technical field of paper detection at present.

Disclosure of Invention

The invention aims to solve the defects of the prior art and provides a method for detecting the residual of the VOCs in paper, which effectively reduces the negative effects of blank samples by inserting the blank samples, thereby solving the practical problem of deviation of detection results caused by the gradual increase of systematic accumulation in the detection process.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

a method for detecting VOCs solvent residues of paper comprises the following steps:

step (1), taking a certain area of base paper as a standard sample substrate, wherein the area of the standard sample substrate is the same as that of a sample to be detected, and baking the standard sample substrate at the temperature of 80 +/-5 ℃ for 2-2.5 hours for standby;

step (2), preparing a series of standard solutions of VOCs solvents;

step (3), adding the standard sample matrix processed in the step (1) into a headspace bottle, then adding a standard solution, preparing a series of standard solution sample bottles to be tested, and taking a clean headspace bottle as a blank sample;

step (4), editing a static headspace sample injector sequence, setting sample bottles at odd stations as samples to be actually detected, namely series of standard solution sample bottles, and setting sample bottles at even stations as blank samples;

step (5), detecting the sample injection sequence of the static headspace sample injector edited in the step (4) by adopting HS-GC or HS-GC/MS; establishing a standard curve by an external standard method, and establishing the standard curve by taking the peak-out time as a horizontal coordinate and the abundance as a vertical coordinate;

step (6), taking a sample to be detected with the same area as the matrix of the standard sample, placing the sample in a headspace bottle, and adding glyceryl triacetate to prepare a sample bottle of the sample to be detected; the adding volume of the glyceryl triacetate is the same as that of the standard solution in the step (3);

step (7), editing a static headspace sample injector sequence, setting sample bottles at odd stations as samples to be actually detected, namely sample bottles to be detected, and setting sample bottles at even stations as blank samples;

step (8), detecting the sample injection sequence of the static headspace sample injector edited in the step (7) by adopting the same detection method as the step (5), and obtaining the residual detection value of the VOCs solvent of the sample to be detected by utilizing the standard curve obtained in the step (5);

the residual components of the VOCs solvent comprise methanol, ethanol, isopropanol, acetone, n-propanol, butanone, ethyl acetate, isopropyl acetate, n-butanol, benzene, 1-methoxy-2-propanol, n-propyl acetate, 2-ethoxyethanol, 4-methyl-2-pentanone, 1-ethoxy-2-propanol, toluene, n-butyl acetate, ethylbenzene, m, p-xylene, o-xylene, styrene, 2-ethoxyethyl acetate, cyclohexanone, dimethyl succinate, dimethyl glutarate and dimethyl adipate.

Further, it is preferable that the temperature of the detection environment is 23 ± 1 ℃; the humidity was 50.0. + -. 2%.

Further, in the step (1), preferably, if the sample to be measured is hard paper, the area of the standard sample matrix is 22.0cm by 5.5 cm; if the sample to be detected is soft paper, the area of the matrix of the standard sample is 15.5cm x 10 cm.

Further, it is preferable that, in the step (2), the size of the headspace bottle is 20mL, and the amount of the standard solution added to each headspace bottle is 1000. mu.L; each stage of standard solution two standard solution vials were prepared for parallel sample determination.

Further, it is preferable that in the step (5), the HS conditions are: the equilibrium temperature of the sample is 80 ℃; the sample ring temperature is 160 ℃; the temperature of the transmission line is 180 ℃; the sample bottle pressurization pressure was 138 kPa; the sample equilibration time is 45.0 min; pressurizing for 0.20 min; the aeration time is 0.20 min; the sample ring equilibration time is 0.05 min; the sample injection time is 1.0 min.

Further, it is preferable that, in the step (5), the GC conditions are: the chromatographic column is a capillary column, VOCOL column or equivalent column special for VOC, and the specification length multiplied by the inner diameter multiplied by the film thickness is 60m multiplied by 0.32mm multiplied by 1.8 mu m;

carrier gas: helium, constant flow mode, flow 2.0 mL/min; the split ratio is as follows: 20: 1; sample inlet temperature: 180 ℃; the sample injection amount is 3.0 mL; temperature rising procedure: keeping at 40 deg.C for 2min, heating to 200 deg.C at 4 deg.C/min, and keeping for 10 min.

Further, it is preferable that, in the step (5), the MS condition is that the auxiliary interface temperature is 220 ℃; the ion source temperature is 230 ℃; the temperature of the four-level bar is 150 ℃; an ionization mode: an electron impact source (EI); ionization energy: 70 eV; transmission line temperature: 180 ℃; solvent retardation: 3-5 min; full scan monitor mode scan range: 29amu to 350 amu; an ion monitoring mode is selected.

The series of standard solutions of the VOCs solvent can also adopt commercial products; the VOCs solvent in the series of standard solutions of VOCs solvent includes 26 volatile organic compounds of methanol, ethanol, isopropanol, acetone, n-propanol, methyl ethyl ketone, ethyl acetate, isopropyl acetate, n-butanol, benzene, 1-methoxy-2-propanol, n-propyl acetate, 2-ethoxyethanol, 4-methyl-2-pentanone, 1-ethoxy-2-propanol, toluene, n-butyl acetate, ethylbenzene, m, p-xylene, o-xylene, styrene, 2-ethoxyethyl acetate, cyclohexanone, dimethyl succinate, dimethyl glutarate, and dimethyl adipate; and respectively weighing the corresponding solvent residue standard samples, dissolving the solvent residue standard samples into glyceryl triacetate to a constant volume, and preparing mixed standard stock solutions with corresponding concentrations according to actual requirements. In general, the concentration of ethanol, n-propyl acetate, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, dimethyl succinate, dimethyl glutarate and dimethyl adipate was 10mg/mL, the concentration of benzene, toluene, ethylbenzene, o-xylene, m-xylene, p-xylene and styrene was 0.15mg/mL, and the concentration of other substances was 1.5 mg/mL. Preparing the prepared mixed standard stock solution into a standard solution with proper concentration according to the actual content in the sample, and preparing the standard solution by adopting a step-by-step dilution method, wherein the standard solution is prepared at least for 5 steps; when the standard curve is established, the Time of arrival (Time) is used as the abscissa, and the abundance (Abunda nce) is used as the ordinate to establish the standard curve.

The principle of the invention is to insert a blank sample between samples to be continuously injected and detected, and to keep two continuous adjacent injection periods, wherein the front sample is an actual detection sample, and the rear sample is a blank sample. In the process of detecting VOCs by adopting instruments such as a headspace-gas chromatograph, a gas chromatograph-mass spectrometer and the like, a headspace sample injector is provided with a plurality of sample injection stations, when two or more continuous headspace sample injection programs are edited, sample bottles at odd stations are set as samples to be actually detected, sample bottles at even stations are set as blank samples, and the state that one blank sample is inserted behind each actual sample is always kept. The method aims to enable a rear sample influenced by a front sample to be a blank sample, and the blank sample is followed by a next sample needing to be detected actually to form an interval type cyclic detection mode of 'actual sample → blank sample → actual sample → blank sample', and the method is called as interpolation detection.

In the headspace sample injection process, part of residual solvent of VOCs in a front sample bottle cannot be timely removed from detection system components such as an inspector, a transmission pipe, a chromatographic column and the like after sample injection and is superposed in a next sample (a rear sample bottle), so that the detection content of VOCs in the next sample is accumulated and increased, a superposition effect is generated, the detection result is higher, and the accuracy of the detection result is influenced. The blank sample also plays a role of blocking the operation of the next actual sample, the blank sample is generally selected to be an empty bottle, theoretically, the residual content of a solvent in the empty bottle is zero, the superposition influence on the next actual detection sample bottle is close to zero, when the sample is operated in the next sampling period, the interference of residual components in a system on the sample bottle can be reduced to the minimum level, the detection value is close to the actual value to the maximum extent, and the operation blank sample plays a role of blocking and reducing the interference on the actual detection sample.

The implementation of the invention should be particularly noted that:

1. the temperature and humidity conditions of the detection environment are sufficiently stable, and the ideal conditions are as follows: the temperature is 23 +/-1 ℃; humidity is 50.0 +/-2%, and the laboratory should keep ventilation.

2. The VOCs detection instrument mainly comprises a gas chromatograph/mass spectrometer, a headspace sample injector and the like, and the components such as the sample injector, a column incubator, a detector, a transmission pipe and the like are ensured to have better temperature-sensitive stability.

3. The sample preparation method of a single sample is required to be uniform and is strictly executed according to relevant standards.

4. The method is characterized in that sample bottles at odd stations of the headspace sample injector are set as actual detection samples, and sample bottles at even stations are blank samples, namely, the state that a blank sample is inserted behind each actual detection sample is always kept.

5. The detection value of the blank sample can be used for observing the stability and the cleanliness of the system, and the detection value of the actual sample is used as the main basis of quality control.

The method is mainly applied to the determination of the residual VOCs solvent in the paper, and is based on the determination of the residual VOCs solvent in the paper: the method for further carrying out standard and accurate control on the accuracy of the detection result by combining a headspace-gas chromatography/mass spectrometry combined method and the actual quantitative effect condition of a detection instrument specifically comprises the following steps:

step 1: instrument condition setting

The applicable instruments of the method are a headspace-gas chromatography/mass spectrometry combination instrument and a headspace-gas chromatograph;

1 static headspace sampler, instrument conditions set:

1.1 the equilibrium temperature of the sample is 80 ℃; the sample ring temperature is 160 ℃; the temperature of the transmission line is 180 ℃;

1.2 the sample bottle pressurization pressure was 138 kPa;

1.3 the sample equilibration time is 45.0 min; pressurizing for 0.20 min; the aeration time is 0.20 min; the sample ring equilibration time is 0.05 min; the sample introduction time is 1.0 min;

2, gas chromatograph, instrument condition setting:

2.1 column specification 60m (length) 0.32mm (internal diameter) 1.8 μm (thickness) (VOC special column);

2.2 carrier gas: helium (He), constant flow mode, flow 2.0 mL/min;

2.3 split ratio: 20: 1;

3, mass spectrometer, instrument condition setting:

3.1 the temperature of the auxiliary interface is 220 ℃; the ion source temperature is 230 ℃; the temperature of the four-level bar is 150 ℃;

step 2: establishment of a Standard Curve

4 preparation of Standard samples

4.1 taking base paper with a certain area as a standard sample substrate, wherein the standard sample substrate is required to correspond to the samples to be detected of soft paper and hard paper, and baking the standard sample substrate at 80 ℃ for 2h for standby; the area of the hard paper substrate was 22.0cm 5.5cm and the area of the soft paper substrate was 15.5cm 10cm (the area of the sample was recognized by industry as a uniform sample for comparison between laboratories).

4.2 respectively placing the prepared soft and hard paper matrixes into a 20mL headspace bottle, adding 1000 microliter of standard solution to prepare standard solution sample bottles to be tested, preparing two parts of standard solution at each stage for parallel sample determination, and arranging the prepared standard solution sample bottles into a new sample bottle sequence from low concentration to high concentration.

4.3 sealing a clean 20mL headspace bottle completely without adding any substance to prepare a blank sample; the blank should be free of any residual components.

4.4 inserting a blank sample prepared in advance into the standard solution sample bottle sequence in 4.2, and keeping inserting the blank sample between every two adjacent sample bottles to form an intermittent cyclic sample injection mode of 'actual sample → blank sample → actual sample → blank sample'.

5 editing static headspace sampler sequences

When the static headspace sample injector sequence is edited, odd-numbered stations such as 1, 3, 5, 7, 9 and 11 are set as blank samples, even-numbered stations such as 2, 4, 6, 8 and 10 are set as samples to be detected, namely, the sample bottles at the odd-numbered stations are set as samples which need to be detected actually, and the sample bottles at the even-numbered stations are set as blank samples.

And 6, after sample introduction is finished, using the blank sample detection value to observe the stability and cleanliness of the system, and using the actual chromatogram information of each level of standard solution sample bottles as the basis for establishing a standard curve. And (3) establishing a standard curve by using an external standard method, wherein the correlation coefficient of the curve is required to be more than or equal to 0.99 and is qualified. The chromatograms of the standard solution are shown in FIGS. 1 and 2.

And step 3: quantitative detection and analysis of samples

1, setting the instrument condition to be the same as that of the step 1;

2 preparation of samples to be tested

2.1 the area of the sample to be measured is treated to be consistent with the area of the matrix, the area of the sample is 22.0cm x 5.5cm, the area of the sample is 15.5cm x 10cm, and the sample is not dried.

(the sample cannot be dried here, VOCs components volatilize in the heating process, the method is different from the standard curve manufacturing process, the standard curve requires zero residue after baking, so the drying is required, and the sample does not need to be dried to carry out GC detection, so the significance is achieved)

2.2 each processed sample is placed into a 20mL headspace bottle, and 1000 μ L of glyceryl triacetate is injected to seal and test, and each sample is used as a group of parallel samples.

2.3 prepare blank by sealing a clean 20mL headspace bottle without adding any substance.

And 2.4, orderly arranging the samples to be tested and the blank samples which are prepared, and keeping the blank sample inserted between every two adjacent sample bottles.

3 editing static headspace sampler sequences

And when the static headspace sample injector sequence is edited, setting the sample bottles at the odd stations as samples actually needing to be detected, setting the sample bottles at the even stations as blank samples, and keeping the blank samples synchronous with 2.4 in the step 3.

4 quantitative analysis of samples

And (3) processing the sample map after operation under a corresponding standard curve (using a corresponding matrix), wherein the areas of the sample and the matrix are required to be consistent, keeping and observing the detection value of the obtained blank sample, and averaging the detection values of the actually measured sample to obtain a report value, which becomes the basis for reporting. The chromatogram is shown in FIG. 3.

When the paper is baked, if the heating temperature of the paper is too high, the paper can be damaged to form fibers, and if the heating temperature is too low, residues cannot be volatilized; with too short a baking time, the residue cannot be volatilized out of the substrate sample, and too long a paper fiber change.

In the MS of the present invention, the principle of ion selection parameters: in mass spectrum ion fragments of each solvent residue, ions with high specificity and response are selected as quantitative ions, and other 1-2 fragment ions are selected as auxiliary qualitative ions. When a standard curve is made, the ion monitoring mode can be selected after full scanning (under the condition that instrument hardware is not changed, full scanning is performed for the first time, and when the standard curve is made later, only ion monitoring needs to be performed).

Compared with the prior art, the invention has the beneficial effects that:

1. the problem of in the headspace sampling process, the systematic stack of testing result risees is solved.

2. The problem of in the headspace sampling process, mutual interference between sample and the sample has been solved, the difference between sample detected value and the actual value has been reduced.

3. Effectively reducing the problem of the attached pollution of the parts of each system caused by the long-term operation of the sample introduction system.

In conclusion, the application of the invention strengthens the stability control force of VOCs detection equipment, improves the fine detection level of VOCs samples, reduces the influence of attached pollution of detection instruments, prolongs the service life of the instruments and saves the maintenance cost.

Drawings

FIG. 1 is a chromatogram of a three-level standard solution of soft paper;

FIG. 2 is a chromatogram of a three-stage hard paper standard solution;

FIG. 3 is a graphical illustration of a chromatogram of a hard paper test sample;

FIG. 4 is a standard ethanol working curve;

FIG. 5 is a standard working curve for n-propyl acetate;

figure 6 is a methanol standard operating curve.

Detailed Description

The present invention will be described in further detail with reference to examples.

It will be appreciated by those skilled in the art that the following examples are illustrative of the invention only and should not be taken as limiting the scope of the invention. The examples do not specify particular techniques or conditions, and are performed according to the techniques or conditions described in the literature in the art or according to the product specifications. The materials or equipment used are not indicated by manufacturers, and all are conventional products available by purchase.

Example 1

step (1), taking base paper with a certain area as a standard sample substrate, wherein the area of the standard sample substrate is the same as that of a sample to be detected, and baking the standard sample substrate at 80 ℃ for 2h for standby;

preparing a series of standard solutions of VOCs solvents;

step (3), adding the standard sample matrix treated in the step (1) into a headspace bottle, then adding a standard solution, preparing a series of standard solution sample bottles to be tested, and taking a clean headspace bottle as a blank sample;

step (6), taking a sample to be detected with the same area as the standard sample substrate, placing the sample to be detected in a headspace bottle, and adding glyceryl triacetate to prepare a sample bottle of the sample to be detected; the adding volume of the glyceryl triacetate is the same as that of the standard solution in the step (3);

Example 2

step (1), taking base paper with a certain area as a standard sample substrate, wherein the area of the standard sample substrate is the same as that of a sample to be detected, and baking the standard sample substrate at 85 ℃ for 2.2h for standby;

preparing a series of standard solutions of VOCs solvents;

step (5), detecting the sample injection sequence of the static headspace sample injector edited in the step (4) by adopting HS-GC or HS-GC/MS; establishing a standard curve by an external standard method, and establishing the standard curve by taking the peak-off time as an abscissa and the abundance as an ordinate;

The temperature of the detection environment is 23 +/-1 ℃; the humidity was 50.0. + -. 2%.

In the step (1), if the sample to be detected is hard paper, the area of the standard sample matrix is 22.0cm by 5.5 cm; if the sample to be detected is soft paper, the area of the matrix of the standard sample is 15.5cm x 10 cm.

In the step (2), the specification of the headspace bottle is 20mL, and the amount of the standard solution added into each headspace bottle is 1000 muL; each stage of standard solution two standard solution vials were prepared for parallel sample determination.

Example 3

step (1), taking base paper with a certain area as a standard sample substrate, wherein the area of the standard sample substrate is the same as that of a sample to be detected, and baking the standard sample substrate at 75 ℃ for at least 2.5 hours for standby;

preparing a series of standard solutions of VOCs solvents;

step (4), editing a static headspace sample injector sequence, setting sample bottles at odd stations as samples to be actually detected, namely series standard solution sample bottles, and setting sample bottles at even stations as blank samples;

In the step (2), the specification of the headspace bottle is 20mL, and the amount of the standard solution added into each headspace bottle is 1000 muL; each stage of standard solution two standard solution sample bottles were prepared for parallel sample determination.

In the step (5), the HS conditions are as follows: the equilibrium temperature of the sample is 80 ℃; the sample ring temperature is 160 ℃; the temperature of the transmission line is 180 ℃; the sample bottle pressurization pressure was 138 kPa; the sample equilibration time is 45.0 min; pressurizing for 0.20 min; the aeration time is 0.20 min; the sample ring equilibration time is 0.05 min; the sample injection time is 1.0 min.

In the step (5), the GC conditions are as follows: the chromatographic column is a capillary column, VOCOL column or equivalent column special for VOC, and the specification length multiplied by the inner diameter multiplied by the film thickness is 60m multiplied by 0.32mm multiplied by 1.8 mu m;

In the step (5), the MS condition is that the temperature of the auxiliary interface is 220 ℃; the ion source temperature is 230 ℃; the temperature of the four-level bar is 150 ℃; an ionization mode: an electron impact source (EI); ionization energy: 70 eV; transmission line temperature: 180 ℃; solvent retardation: 3-5 min; full scan monitor mode scan range: 29amu to 350 amu; an ion monitoring mode is selected.

Application example 1 detection and comparative analysis of three-stage Soft paper Standard solution (FIG. 1 is response chromatogram of three-stage Soft paper Standard solution)

Equipment and sample condition setting:

the GC conditions were: type of column: a VOC dedicated capillary column (VOCOL column or equivalent column) with a specification of 60m (length) 0.32mm (inner diameter) 1.8 μm (thickness of the membrane); carrier gas: helium, constant flow mode, flow 2.0 mL/min; the split ratio is as follows: 20: 1; sample inlet temperature: 180 ℃; the sample injection amount is 3.0 mL; temperature rising procedure: keeping at 40 deg.C for 2min, heating to 200 deg.C at 4 deg.C/min, and keeping for 10 min;

the MS condition is that the temperature of the auxiliary interface is 220 ℃; the ion source temperature is 230 ℃; the temperature of the four-level bar is 150 ℃; an ionization mode: an electron impact source (EI); ionization energy: 70 eV; transmission line temperature: 180 ℃; solvent retardation: 3.60 min; a selective ion monitoring scan mode is performed.

The control factors of the samples tested are shown in table 1;

TABLE 1 description of the apparatus, sample conditions

Control factor	Equipment and sample Condition description
		1	Sample injection period of 70min
2	Equilibration time 45min
		3	The equilibrium temperature was 80 deg.C
4	The temperature of the sample ring is 160 DEG C
		5	The temperature of the transmission line is 180 DEG C
6	Pressurizing for 0.20min
		7	The aeration time is 0.20min
8	The sample ring balance time was 0.05min
		9	Sample introduction time is 1.0min
10	The area of the sample is consistent with that of the standard curve matrix
		11	The volume of the added standard solution was 1000. mu.L

The inventor explains the difference between the blank insertion detection and the continuous sample injection detection by adding a three-level standard solution into the soft paper for detection and analysis, and the detection is mainly realized by the following six steps:

1. taking at least 12 layers of soft paper base paper samples, uniformly cutting the area of the soft paper base paper samples into 15.5cm x 10cm, taking the single-layer unit area of the paper samples as one sample, baking each sample at 80 ℃ for two hours, and cooling to room temperature for later use.

2. Abandoning the surface layer, the bottom layer and possibly polluted samples, filling the single-layer sample into a 20mL headspace bottle, injecting 1000 mu L of three-level standard solution, and sealing to be detected.

3. 10 identical parallel samples to be tested are prepared by the same method and are divided into two groups, namely a group A and a group B, and each group comprises 5 samples.

4. Blanks were made with 5 clean empty bottles without any material added.

5. Inserting the prepared blank sample into the A group of sample bottle sequences to be detected, inserting a blank sample into each two adjacent samples, and compiling into a new sequence.

6. The 5 samples of group B were injected continuously (no blank was inserted).

After the sample introduction is finished, the detection result is the response concentration (unit: mg/square meter) of the system after 1000 mu L of three-level standard solution is added into the soft paper base paper of unit area. The control factors for the apparatus and samples are shown in table 1. Followed by ethanol (C) in the sample ₂ H ₅ OH) content as an example the differences between the plug-in process and the current process (other component contents also apply) are shown in table 2:

table 2 detection results of ethanol after adding third-level standard liquid into soft paper base paper

Exp	Parallel sample 1	Parallel sample 2	Parallel sample 3	Parallel sample 4	Parallel sample 5	Arithmetic mean value	Standard deviation of	Extreme difference
									Group A	7.6777	7.7328	7.7544	7.7675	7.7181	7.7301	0.0350	0.0898
Group B	7.6891	7.7315	7.8019	7.8015	7.9241	7.7896	0.0892	0.2350
									Blank sample	0.0180	0.0215	0.0175	0.0198	0.0235	0.0201	0.0025	0.0060

According to the experimental data, compared with the group B samples without blank samples (continuous sample injection), the group A samples with the blank samples inserted therein tend to be more stable in detection value, the standard deviation after the blank samples are inserted therein is relatively small, and the group B data shows that the continuous sample injection detection value tends to rise in small amplitude. Table 3 shows the standard curve function corresponding to the standard curve used in the application example 1 to add the third-level standard solution to the base paper of the soft paper for detection. FIG. 4 is a standard ethanol working curve of a standard soft paper curve corresponding to application example 1.

TABLE 3 Soft paper Standard Curve function and related coefficient Table

The invention is not only suitable for the detection of soft paper samples, but also suitable for the detection of hard paper samples.

Application example 2 hard paper four-stage standard solution detection comparative analysis (FIG. 2 is a response chromatogram of a hard paper four-stage standard solution)

In this example, a headspace-gas chromatography method was used to analyze a cardboard sample by adding four standard solutions, and the method of the present invention is further described, which mainly comprises the following six steps:

1. taking at least 12 layers of a sample of hard paper base paper, uniformly cutting the area of the sample into 22.0cm by 5.5cm, separating the single layer of the sample, baking the single layer of the sample for two hours at 80 ℃, and cooling the single layer of the sample to room temperature for later use.

2. Discarding the possibly contaminated sample, filling the single-layer sample into a 20mL headspace bottle, injecting 1000 μ L of tertiary standard solution, and sealing to be tested.

3. Simultaneously preparing 10 same parallel samples to be tested, and dividing the samples into two groups, namely a group A and a group B, wherein each group comprises 5 samples.

4. Blanks were prepared from 5 clean empty bottles.

5. Inserting the prepared blank samples into the group A of sample bottles to be detected, inserting one blank sample into each two adjacent samples, and compiling into a new sequence.

And 5 samples in the group B are continuously injected (no blank is inserted).

After the sample introduction is finished, the detection result is the response concentration (unit: mg/square meter) of the system after 1000 mu L of four-stage standard solution is added into the raw hard paper of the unit area.

Equipment and sample condition setting:

the GC conditions were: type of column: a VOC dedicated capillary column (VOCOL column or equivalent column) with a specification of 60m (length) 0.32mm (inner diameter) 1.8 μm (thickness of the membrane); carrier gas: helium gas, constant flow mode, flow 2.0 mL/min; the split ratio is as follows: 20: 1; sample inlet temperature: 180 ℃; the sample injection amount is 3.0 mL; temperature rising procedure: keeping at 40 deg.C for 2min, heating to 200 deg.C at 4 deg.C/min, and keeping for 10 min;

The control factors of the tested samples were consistent with the settings of the soft paper test samples (as shown in table 1);

the following is the n-propyl acetate (C) in the sample ₅ H ₁₀ O ₂ ) The response test values of the contents are taken as examples, and the difference between the interpolation method and the current method is compared, as shown in table 4:

TABLE 4 addition of four-stage standard solution to the base paper of hard paper with n-propyl acetate (C) ₅ H ₁₀ O ₂ ) Result of detection of

Exp	Parallel sample 1	Parallel sample 2	Parallel sample 3	Parallel sample 4	Parallel sample 5	Arithmetic mean value	Standard deviation of	Extreme difference
									Group A	19.2931	19.3732	19.3963	19.3810	19.4308	19.3749	0.0508	0.1377
Group B	19.2849	19.3998	19.4060	19.4989	19.5423	19.4264	0.0998	0.2574
									Blank sample	0.0210	0.0219	0.0221	0.0273	0.0245	0.0234	0.0026	0.0054

From the above experimental data, it can be seen that the group a samples with the blank inserted therein are very poor and have relatively small standard deviation compared to the group B samples without the blank (continuous injection). Table 5 shows a standard curve function corresponding to a standard curve used for the detection of the application example 2 by adding the fourth-order standard solution to the base paper of the hard paper; FIG. 5 is a standard working curve of n-propyl acetate in a standard curve of hard paper corresponding to application example 2.

TABLE 5 hard paper Standard Curve function and related coefficient Table

Next, we performed comparative analysis of the cardboard products actually used in production by the same sample preparation test method as in example 3.

Application example 3 laser cardboard (hard paper) detection comparative analysis (FIG. 3 is a graphic illustration of response chromatogram of hard paper detection sample)

In this embodiment, a laser paperboard (cardboard) sample is analyzed by headspace-gas chromatography, and two main steps are performed as follows:

the first step is as follows: apparatus, sample condition setting

The control factors of the tested samples were consistent with the set conditions of the soft and hard paper test samples (as shown in Table 1)

The second step is that: preparation of Standard Curve

2. Discarding possibly polluted samples, filling a single-layer sample into a 20mL headspace bottle, injecting 1000 mu L of one-grade to five-grade standard solutions respectively, and sealing two parallel samples of each grade to be detected.

3. And arranging the prepared sample bottles in sequence according to the concentration from low to high.

4. Then 10 clean empty bottles were used to make blanks.

5. Inserting the prepared blank sample into a sample bottle sequence to be detected, inserting one blank sample between every two adjacent samples to form a complete sample injection sequence, carrying out automatic static headspace-gas chromatography sample injection on the sample injection sequence, and drawing a corresponding standard curve by an external standard method.

Third step sample preparation

1. A sample of the laser card paper (hard paper) is taken, the area is cut to 22.0cm by 5.5cm, and the area is kept consistent with the standard curve matrix for standby.

2. Discarding the sample which may be contaminated, filling the single-layer laser paperboard (hard paper) sample into a 20mL headspace bottle, injecting 1000 μ L of glyceryl triacetate, and sealing to be tested.

3. Simultaneously preparing 10 same parallel samples to be tested, and dividing the samples into two groups, namely a group A and a group B, wherein each group comprises 5 samples. (Note: in actual production work, only two parallel samples need to be prepared to meet production requirements in general)

4. Blanks were prepared from 5 clean empty bottles.

5. And inserting the prepared blank sample into the A groups of sample bottle columns to be detected.

And 6, continuously injecting 5 samples of the group B without inserting blank samples.

And analyzing the chromatogram of the detection sample under the standard curve established in the second step to obtain the final detection result. Now with the methanol (CH) in the laser card paper (hard paper) sample ₃ OH) as an example, to compare the difference between the interpolation method and the current method, as shown in table 6:

TABLE 6 methanol (CH) in laser cardboard (hard paper) ₃ OH) detection results

Exp	Parallel sample 1	Parallel sample 2	Parallel sample 3	Parallel sample 4	Parallel sample 5	Arithmetic mean value	Standard deviation of	Extreme difference
									Group A sample	1.5601	1.5776	1.4992	1.5279	1.6084	1.5546	0.0425	0.1092
Group B sample	1.4610	1.4697	1.6114	1.6199	1.6272	1.5578	0.0847	0.1662
									Blank sample	0.0195	0.0231	0.0229	0.0213	0.0225	0.0219	0.0015	0.0036

According to the experimental data, the group A samples inserted into the blank samples have relatively small range and standard deviation relative to the group B samples, a small amount of system residues exist in numerical analysis of the blank samples, and if the value is large, the chromatographic column should be aged in time, so that the system is prevented from being attached and polluted. Table 7 shows a standard curve function corresponding to a standard curve used for detecting an actually produced hard paper pattern in application example 3; fig. 6 is a methanol standard working curve of a hard paper standard curve corresponding to the application example 3.

TABLE 7 hard paper standard curve function and correlation coefficient table

The three examples above show that: the method is suitable for detecting the standard substance with relatively stable volatile components, is also suitable for detecting a detection sample with relatively unstable volatile components, and has a relatively obvious effect of inserting a blank sample.

The foregoing shows and describes the general principles, essential features, and advantages of the invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are described in the specification and illustrated only to illustrate the principle of the present invention, but that various changes and modifications may be made therein without departing from the spirit and scope of the present invention, which fall within the scope of the invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.

Claims

1. A method for detecting VOCs solvent residues of paper is characterized by comprising the following steps:

preparing a series of standard solutions of VOCs solvents;

2. The method for detecting VOCs solvent residues in paper according to claim 1, wherein the temperature of the detection environment is 23 ± 1 ℃; the humidity was 50.0. + -. 2%.

3. The method for detecting the residual solvent in the VOCs in the paper sheet according to claim 1, wherein in the step (1), if the sample to be detected is hard paper, the area of the standard sample substrate is 22.0cm by 5.5 cm; if the sample to be detected is soft paper, the area of the matrix of the standard sample is 15.5cm x 10 cm.

4. The method for detecting the residual of the VOCs in the paper sheet according to claim 1, wherein in the step (2), the specification of the headspace bottle is 20mL, and the amount of the standard solution added to each headspace bottle is 1000 μ L; each stage of standard solution two standard solution vials were prepared for parallel sample determination.

5. The method for detecting the residual amount of the VOCs in the paper according to claim 1, wherein in the step (5), the HS conditions are as follows: the equilibrium temperature of the sample is 80 ℃; the sample ring temperature is 160 ℃; the temperature of the transmission line is 180 ℃; the sample bottle pressurization pressure is 138 kPa; the sample equilibration time is 45.0 min; pressurizing for 0.20 min; the aeration time is 0.20 min; the sample ring equilibration time is 0.05 min; the sample injection time is 1.0 min.

6. The method for detecting the residual amount of the VOCs in the paper according to claim 1, wherein in the step (5), the GC conditions are as follows: the chromatographic column is a capillary column, VOCOL column or equivalent column special for VOC, and the specification length multiplied by the inner diameter multiplied by the film thickness is 60m multiplied by 0.32mm multiplied by 1.8 mu m;

7. The method for detecting VOCs solvent residues in paper according to claim 1, wherein in step (5), the MS condition is that the secondary interface temperature is 220 ℃; the ion source temperature is 230 ℃; the temperature of the four-level bar is 150 ℃; an ionization mode: an electron impact source (EI); ionization energy: 70 eV; transmission line temperature: 180 ℃; solvent retardation: 3-5 min; full scan monitor mode scan range: 29amu to 350 amu; an ion monitoring mode is selected.