Method for detecting content of residual monomers in synthetic resin emulsion

Abstract

The invention relates to the technical field of detection, and discloses a method for detecting the content of residual monomers in synthetic resin emulsion. The method comprises the following steps: carrying out gas chromatographic analysis I on a standard solution containing at least 10 residual monomer standard substances to respectively obtain the chromatographic peak area yi of each residual monomer standard substance in the standard solution; defining the mass concentration of each residual monomer standard substance in the standard solution as xi, and establishing a curvilinear equation of yi and xi as an equation I: yi = ki * xi + bi; performing gas chromatographic analysis II on the synthetic resin emulsion to-be-detected solution to respectively obtain the chromatographic peak area Ai of each residual monomer in the to-be-detected solution; and calculating the content of each residual monomer in the synthetic resin emulsion according to an equation II: X% = (Ai-bi) / ki * V / (Mx106) * 100%. The method provided by the invention is high in accuracy, good in recovery rate and low in detection limit.

Description

Technical Field

[0001] The invention relates to the field of detection technology, and in particular to a method for detecting the residual monomer content in a synthetic resin emulsion. Background Art

[0002] Synthetic resin emulsion refers to a resin emulsion in which monomers are dispersed in water with the help of emulsifiers and mechanical stirring to form an emulsion, and then an initiator is added to initiate the polymerization of monomers into a stable system. The monomers commonly used in synthetic emulsions are generally compounds containing unsaturated double bonds (C=C), such as vinyl chloride, styrene, vinyl acetate, acrylic acid and its ester compounds. Most of these monomers have strong irritating odors and varying degrees of toxicity.

[0003] Due to the influence of cage effect, glass transition effect and reactivity ratio in the emulsion polymerization process, the monomers in the synthetic emulsion cannot be 100% converted. Therefore, unreacted monomers are inevitably present in the finished product. These unreacted monomers are residual monomers.

[0004] The presence of residual monomers can have a significant impact on product quality and even human health and the environment, so appropriate testing technology is needed to monitor whether the content of residual monomers in synthetic resin emulsions meets the requirements.

[0005] The current method for detecting the residual monomer content in synthetic resin emulsions is to use gas phase-headspace sampling technology, which requires the use of a headspace sampler in conjunction with a gas chromatograph, using a FID detector and an internal standard method to quantify monomers such as acrylonitrile, vinyl acetate, ethyl acrylate, methyl methacrylate, styrene, butyl acrylate, and isooctyl acrylate.

[0006] The principle of gas phase-headspace technology is to place the sample to be tested in a closed container, heat it to make the volatile components evaporate from the sample matrix, and directly extract the top gas for chromatographic analysis after reaching equilibrium between the gas and liquid phases, so as to detect the composition and content of the residual monomers.

[0007] Yu et al. (Yu Bin, Ji Junhong, Zhou Xiangling, et al. Determination of unreacted residual monomer content in emulsion by headspace gas chromatography (HSGC) [C] / / The First Coating Resin Technology Seminar and Acrylic Resin Application Forum. "Coating Industry" Magazine; National Coating Industry Information Center, 2007.) used headspace injection to combine the headspace injector with the gas chromatograph to determine the content of residual monomers in the synthetic resin emulsion. However, this method is extremely dependent on the volatility of the analyte, which will affect the reproducibility of the analysis results of low volatility or high boiling point analytes to varying degrees, increase the error, and ultimately may cause the tester to misjudge the results; and this method requires the mass ratio of the internal standard solution and the storage solution B to be as close to 1:1 as possible, the pretreatment process is relatively cumbersome and time-consuming, and the calculation process is complicated and lengthy due to the large number of target compounds involved when calculating the results, and it is also prone to calculation errors, all of which greatly waste manpower and time costs. Summary of the invention

[0008] The purpose of the present invention is to provide a method for detecting the residual monomer content in a synthetic resin emulsion, which has the advantages of high accuracy, good recovery rate and low detection limit.

[0009] In order to achieve the above object, the present invention provides a method for detecting the residual monomer content in a synthetic resin emulsion, the method comprising:

[0010] (1) Without using a headspace sampler, a standard solution containing at least 10 residual monomer standards is subjected to gas chromatography analysis I to obtain the chromatographic peak area y of each residual monomer in the standard solution. i ;

[0011] The residual monomers include: acrylamide, methyl acrylate, tert-butyl acrylate, acrylonitrile, vinyl acetate, ethyl acrylate, methyl methacrylate, butyl acrylate, styrene and isooctyl acrylate;

[0012] The gas chromatography analysis I is carried out in a programmed temperature rise method I, the chromatographic column of the gas chromatography analysis I is a DB-624 chromatographic column, and the conditions of the programmed temperature rise I include: first, keeping the temperature at T1 for 3-5 minutes, then heating to T2 at a rate of 4-6°C / min, then heating to T3 at a rate of 15-25°C / min, and keeping the temperature at T3 for 3-8 minutes; wherein, T1≤50°C, T2=150-180°C, T3=220-250°C;

[0013] Define the mass concentration of each residual monomer standard in the standard solution as x i , establish y i With x i The curve equation is Equation I:

[0014] Equation I y i =k i × i +b i ; and the correlation coefficient R of equation I 2 ≮0.995;

[0015] (2) Without using a headspace injector, the synthetic resin emulsion test solution is subjected to gas chromatography analysis II to obtain the chromatographic peak area A of each residual monomer in the test solution. i ;

[0016] (3) Calculate the content of each residual monomer in the synthetic resin emulsion according to equation II:

[0017] Equation II X% = (A i -b i ) / k i ×V / (M×10 6 )×100%;

[0018] X% is the mass percentage of each residual monomer in the solution to be tested;

[0019] M is the mass of the synthetic resin emulsion in the solution to be tested, in g;

[0020] V is the volume of the solution to be tested, in mL.

[0021] Compared with the methods in the prior art, the method provided by the present invention has at least the following advantages:

[0022] (1) The method provided by the present invention does not require the additional configuration of a headspace sampler, thus saving instrument costs.

[0023] (2) The method provided by the present invention has high accuracy, good recovery rate and low detection limit (2.0 mg / kg). DETAILED DESCRIPTION

[0024] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0025] As mentioned above, the present invention provides a method for detecting the residual monomer content in a synthetic resin emulsion, the method comprising:

[0026] (1) Without using a headspace sampler, a standard solution containing at least 10 residual monomer standards is subjected to gas chromatography analysis I to obtain the chromatographic peak area y of each residual monomer in the standard solution. i ;

[0027] The residual monomers include: acrylamide, methyl acrylate, tert-butyl acrylate, acrylonitrile, vinyl acetate, ethyl acrylate, methyl methacrylate, butyl acrylate, styrene and isooctyl acrylate;

[0028] The gas chromatography analysis I is carried out in a programmed temperature rise method I, the chromatographic column of the gas chromatography analysis I is a DB-624 chromatographic column, and the conditions of the programmed temperature rise I include: first, keeping the temperature at T1 for 3-5 minutes, then heating to T2 at a rate of 4-6°C / min, then heating to T3 at a rate of 15-25°C / min, and keeping the temperature at T3 for 3-8 minutes; wherein, T1≤50°C, T2=150-180°C, T3=220-250°C;

[0029] Define the mass concentration of each residual monomer standard in the standard solution as x i , establish y i With x i The curve equation is Equation I:

[0030] Equation I y i =k i × i +b i ; and the correlation coefficient R of equation I 2 ≮0.995;

[0031] (2) Without using a headspace injector, the synthetic resin emulsion test solution is subjected to gas chromatography analysis II to obtain the chromatographic peak area A of each residual monomer in the test solution. i ;

[0032] (3) Calculate the content of each residual monomer in the synthetic resin emulsion according to equation II:

[0033] Equation II X% = (A i -b i ) / k i ×V / (M×10 6 )×100%;

[0034] X% is the mass percentage of each residual monomer in the solution to be tested;

[0035] M is the mass of the synthetic resin emulsion in the solution to be tested, in g;

[0036] V is the volume of the solution to be tested, in mL.

[0037] In a particularly preferred case, the chromatographic columns used in the gas chromatography analysis I and the gas chromatography analysis II are both DB-624 chromatographic columns.

[0038] It should be noted that, in the present invention, the peak area of ​​the chromatographic peak of each residual monomer is the highest peak area among the chromatographic peaks of each residual monomer. Exemplarily, when the residual monomer is acrylamide, the peak area of ​​the chromatographic peak of acrylamide is the peak area at a retention time of 22.3-22.4 min; when the residual monomer is methyl acrylate, the peak area of ​​the chromatographic peak of methyl acrylate is the peak area at a retention time of 9.1-9.2 min; when the residual monomer is tert-butyl acrylate, the peak area of ​​the chromatographic peak of tert-butyl acrylate is the peak area at a retention time of 15.3-15.4 min; when the residual monomer is acrylonitrile, the peak area of ​​the chromatographic peak of acrylonitrile is the peak area at a retention time of 7.1-7.2 min; when the residual monomer is vinyl acetate, the peak area of ​​the chromatographic peak of vinyl acetate is the peak area at a retention time of 7.9-8.0 ... When the monomer is ethyl acrylate, the peak area of ​​the chromatographic peak of ethyl acrylate is the peak area at a retention time of 12.2-12.3 min; when the residual monomer is methyl methacrylate, the peak area of ​​the chromatographic peak of methyl methacrylate is the peak area at a retention time of 12.7-12.8 min; when the residual monomer is butyl acrylate, the peak area of ​​the chromatographic peak of butyl acrylate is the peak area at a retention time of 20.0-20.1 min; when the residual monomer is styrene, the peak area of ​​the chromatographic peak of styrene is the peak area at a retention time of 20.2-20.3 min; when the residual monomer is isooctyl acrylate, the peak area of ​​the chromatographic peak of isooctyl acrylate is the peak area at a retention time of 29.5-29.6 min.

[0039] It should be noted that, in the present invention, different residual monomers correspond to different k i and b i , k in Equation II i and b i and k in Equation I i and b i For example, when the residual monomer is acrylonitrile, k i is the chromatographic peak area y of the acrylonitrile standard in the standard solution i The mass concentration of acrylonitrile standard in the standard solution is x i The slope of the established equation I, b i is the chromatographic peak area y of the acrylonitrile standard in the standard solution i The mass concentration of acrylonitrile standard in the standard solution is xi The intercept of equation I is established.

[0040] Preferably, in step (1), T1 = 45-50° C., T2 = 155-165° C., and T3 = 235-245° C. The inventors of the present invention have found that in this preferred embodiment, the accuracy of analyzing the residual monomer content in the synthetic resin emulsion can be improved.

[0041] Preferably, in step (1), the mass concentration of each residual monomer standard in the standard solution is independently 10-100 mg / L.

[0042] Preferably, the solvent in the standard solution and the solution to be tested is acetone.

[0043] Preferably, the conditions of the gas chromatography analysis I include: column flow rate of 2.0-3.0 mL / min, split ratio of 5-10:1, and injection port temperature of 250-280° C. The inventors of the present invention have found that in this preferred case, the separation degree of each residual monomer chromatographic peak in the synthetic resin emulsion is better.

[0044] Preferably, the conditions of the gas chromatography analysis I also include: the detector temperature is 280-300°C, the hydrogen flow rate is 30-50mL / min, the air flow rate is 380-420mL / min, and the tail gas flow rate is 25-35mL / min.

[0045] Preferably, the tail gas is an inert gas. Exemplarily, the inert gas is selected from at least one of He, Ar, and N2.

[0046] Preferably, the gas chromatography analysis II is performed by programmed temperature rise II, and the conditions of the programmed temperature rise II are the same as the conditions of the programmed temperature rise I in the gas chromatography analysis I.

[0047] Preferably, the DB-624 chromatographic column has a length of 60 m, an inner diameter of 0.32 mm, and a film thickness of 1.8 μm.

[0048] Preferably, the method further comprises, before performing the gas chromatography analysis I and the gas chromatography analysis II, filtering the standard solution and the test solution through organic nylon filter membranes respectively.

[0049] The present invention has no special requirements on the pore size of the organic nylon filter membrane, and those skilled in the art can select it as needed. For example, an organic nylon filter membrane with a pore size of 0.45 μm is used for filtration.

[0050] Preferably, the injection volumes in the gas chromatography analysis I and the gas chromatography analysis II are each independently 1-2 μL.

[0051] Preferably, the chromatographic separation degree of any two adjacent residual monomer chromatographic peaks is 1.5-1.8. The inventors of the present invention have found that in this preferred embodiment, the accuracy of analyzing the residual monomer content in the synthetic resin emulsion can be improved.

[0052] According to a preferred embodiment, when the residual monomer is acrylamide, k i =0.72316, b i =-0.04415.

[0053] Preferably, when the residual monomer is methyl acrylate, k i =0.59687, b i =-0.00696.

[0054] Preferably, when the residual monomer is tert-butyl acrylate, k i =0.94403, b i =-0.01092.

[0055] Preferably, when the residual monomer is acrylonitrile, k i =0.85659, b i =-0.01067.

[0056] Preferably, when the residual monomer is vinyl acetate, k i =0.55345, b i =-0.00726.

[0057] Preferably, when the residual monomer is ethyl acrylate, k i =0.70517, b i =-0.01079.

[0058] Preferably, when the residual monomer is methyl methacrylate, k i =0.73348, b i =-0.01096.

[0059] Preferably, when the residual monomer is butyl acrylate, k i =0.90831, b i =-0.01664.

[0060] Preferably, when the residual monomer is styrene, k i =1.55352, b i =-0.02532.

[0061] Preferably, when the residual monomer is isooctyl acrylate, k i =0.80492, b i =0.02496.

[0062] The present invention will be described in detail below by way of examples. In the following examples, unless otherwise specified, all the instruments and raw materials used are commercially available.

[0063] The residual monomers in the following examples of the present invention include: acrylamide, methyl acrylate, tert-butyl acrylate, acrylonitrile, vinyl acetate, ethyl acrylate, methyl methacrylate, butyl acrylate, styrene and isooctyl acrylate.

[0064] Blank matrix sample: synthetic resin emulsion, not containing any residual monomer detected by the method of the present invention, purchased from Keshun Waterproof Technology Co., Ltd., brand KS-988AⅡ.

[0065] Residual monomer standard: purity>99%.

[0066] Acetone: chromatographic grade.

[0067] Gas chromatograph: Model is Agilent 7890B.

[0068] Column I: DB-624 column, length 60m, inner diameter 0.32mm, film thickness 1.8μm.

[0069] Column II: HP-5 column, length 30m, inner diameter 0.25mm, film thickness 0.25um.

[0070] Detector: Hydrogen flame ionization detector.

[0071] The conditions of the gas chromatography analysis I and the gas chromatography analysis II in the following Examples 1 to 3 and Comparative Examples 1 to 2 of the present invention include: a column flow rate of 2.8 mL / min; a split ratio of 5:1; an inlet temperature of 260°C; a detector temperature of 300°C, a hydrogen flow rate of 40 mL / min, an air flow rate of 400 mL / min, a tail gas (N2) flow rate of 30 mL / min, and an injection volume of 1 μL.

[0072] The following preparation examples of series A of the present invention are used to illustrate the preparation of a series of standard solutions of various residual monomer standards of different mass concentrations.

[0073] Preparation Example A

[0074] (i) Weighing 0.1 g (the actual weighing value is between 0.0900 and 0.1100) of each residual monomer standard, adding acetone for ultrasonic dissolution, and diluting the volume to 50 mL with acetone to obtain a standard stock solution containing each residual monomer with a mass concentration of about 2000 mg / L (the mass concentration of each residual monomer in the standard stock solution is subject to the actual calculated value);

[0075] (ii) respectively taking the standard stock solutions and diluting the volume to 10 mL with acetone to obtain a series of standard solutions of each residual monomer standard with a mass concentration of approximately 10 mg / L, 25 mg / L, 50 mg / L, 75 mg / L, and 100 mg / L, respectively (the mass concentration of each residual monomer in the series of standard solutions is subject to the actual calculated value);

[0076] (iii) filtering the series of standard solutions using a 0.45 μm organic nylon filter membrane to obtain filtered series of standard solutions.

[0077] The following preparation examples of series B are used to illustrate the preparation of synthetic resin emulsion test solutions containing various residual monomers.

[0078] Preparation Example B

[0079] 1 gram of blank matrix sample was mixed with the standard stock solution (prepared in the above Preparation Example A) with a mass concentration of each residual monomer of 2000 mg / L, and the volume was fixed to 10 mL with acetone to obtain synthetic resin emulsion test solutions containing each residual monomer with different mass percentages;

[0080] The mass percentage of each residual monomer in the test solution obtained in this preparation example is shown in Table 1.

[0081] Table 1

[0082]

[0083]

[0084] The following example of the present invention is used to illustrate the determination of the residual monomer content in the test solution prepared in Preparation Example B. Six parallel samples are prepared for each test solution. Before performing gas chromatography analysis II, each test solution is first filtered using a 0.45 μm organic nylon filter membrane to obtain a filtered test solution.

[0085] Example 1

[0086] (1) Without using a headspace sampler, the filtered series of standard solutions are subjected to gas chromatography analysis I (the gas chromatography analysis I is performed using a programmed temperature I as shown in Table 2) to obtain the chromatographic peak area y of each residual monomer in the standard solution.i ;

[0087] Define the mass concentration of each residual monomer standard in the standard solution as x i , establish y i With x i The curve equation is equation I;

[0088] Equation I y i =k i × i +b i ; and the correlation coefficient R of equation I 2 ≮0.995;

[0089] (2) Without using a headspace sampler, the filtered test solution I is subjected to gas chromatography analysis II (same conditions as gas chromatography analysis I) to obtain the chromatographic peak area A of each residual monomer in the test solution I. i ;

[0090] (3) Calculate the content of each residual monomer in the test solution I according to equation II:

[0091] Equation II X% = (A i -b i ) / k i ×V / (M×10 6 )×100%;

[0092] X% is the mass percentage of each residual monomer in the test solution I;

[0093] M is the mass of the blank matrix sample in the test solution I, in g;

[0094] V is the volume of the solution I to be tested, where V = 10 mL;

[0095] In this embodiment, chromatographic column I is used for gas chromatography analysis.

[0096] Example 2

[0097] This embodiment adopts a method similar to that of Embodiment 1, except that in step (2) and step (3), the filtered test solution II is used to replace the filtered test solution I in Embodiment 1, and the rest is the same as that of Embodiment 1.

[0098] Example 3

[0099] This embodiment adopts a method similar to that of Embodiment 1, except that in step (2) and step (3), the filtered test solution III is used to replace the filtered test solution I in Embodiment 1, and the rest is the same as that of Embodiment 1.

[0100] Comparative Example 1

[0101] This comparative example adopts a method similar to that of Example 1 to carry out step (1), except that the parameters of the programmed temperature I in step (1) are different, see Table 2 for details.

[0102] In this comparative example, when performing step (1), it was found that the chromatographic peaks of ethyl acrylate and methyl methacrylate could not be completely separated, so the experiment was terminated without performing the next step.

[0103] Comparative Example 2

[0104] This comparative example adopts a method similar to that of Example 1 to carry out step (1), except that in step (1), chromatographic column II is used to replace chromatographic column I in Example 1.

[0105] During step (1) of this comparative example, it was found that, compared with Example 1, within the same test time, isooctyl acrylate failed to successfully peak, and the peak time of acrylonitrile was very close to the peak time of acetone, so the experiment was terminated without proceeding to the next step.

[0106] Comparative Example 3

[0107] This comparative example is used to illustrate the use of headspace sampling to detect the content of residual monomers in the test solution III.

[0108] For specific methods, please refer to the literature "Yu Bin, Ji Junhong, Zhou Xiangling, et al. Determination of unreacted residual monomer content in emulsion by headspace gas chromatography (HSGC) [C] / / The First Coating Resin Technology Seminar and Acrylic Resin Application Forum. "Coating Industry" Magazine; National Coating Industry Information Center, 2007."

[0109] The gas chromatograph and headspace sampler used in this comparative example are the same as those in the reference, except that the instrument parameters are as follows:

[0110] Chromatographic analysis conditions: chromatographic analysis was performed using chromatographic column I, with a column flow rate of 2.6 mL / min; a split ratio of 10:1; an inlet temperature of 225°C; a detector temperature of 250°C, a hydrogen flow rate of 30 mL / min, an air flow rate of 300 mL / min, a tail gas (N2) flow rate of 25 mL / min, and an injection volume of 1.0 μL;

[0111] Program temperature rise: 40℃ for 2 min, then increase the temperature to 100℃ at a rate of 10℃ / min, then increase the temperature to 200℃ at a rate of 6℃ / min, maintain for 5 min, and then run at 230℃ for 0.5 min;

[0112] Headspace sampler conditions: equilibrium temperature of 130 °C, temperature of the quantitative loop of 150 °C, temperature of the transfer line of 170 °C, equilibrium time of 10 min, gas chromatography cycle time of 37 min, sample bottle pressurization time of 0.20 min, time for gas from the quantitative loop to the outlet of 0.11 min, gas equilibrium time in the sample loop of 0.20 min, and gas purge time from the quantitative loop to the gas chromatograph of 1.00 min.

[0113] Table 2

[0114] Temperature Program I Example 1 Comparative Example 1 T1 / ℃ 50 Same as Example 1 Holding time at T1 / min 4 Same as Example 1 Heating rate / (℃ / min) 5 / T2 / ℃ 160 / Heating rate / (℃ / min) 20 10 T3 / ℃ 240 Same as Example 1 Holding time under T3 / min 5 Same as Example 1

[0115] The equation I obtained in step (1) of the above embodiment 1 is shown in Table 3.

[0116] Table 3

[0117] Residual monomer / type Equation I <![CDATA[Coefficient of correlation R 2 > <![CDATA[k i ]]> <![CDATA[b i ]]> Acrylamide y=0.72316x-0.04415 0.99710 0.72316 -0.04415 Methyl acrylate y=0.59687x-0.00696 0.99977 0.59687 -0.00696 Tert-Butyl Acrylate y=0.94403x-0.01092 0.99979 0.94403 -0.01092 Acrylonitrile y=0.85659x-0.01067 0.99973 0.85659 -0.01067 Vinyl acetate y=0.55345x-0.00726 0.99974 0.55345 -0.00726 Ethyl acrylate y=0.70517x-0.01079 0.99973 0.70517 -0.01079 Methyl Methacrylate y=0.73348x-0.01096 0.99975 0.73348 -0.01096 Butyl acrylate y=0.90831x-0.01664 0.99962 0.90831 -0.01664 Styrene y=1.55352x-0.02532 0.99966 1.55352 -0.02532 2-Ethylhexyl acrylate y=0.80492x+0.02496 0.99926 0.80492 0.02496

[0118] The analysis results in the above Examples 1 to 3 and Comparative Example 3 are shown in Table 4, wherein the residual monomer mass percentage and recovery rate are the average values ​​obtained by 6 parallel tests of each residual monomer.

[0119] Table 4

[0120]

[0121]

[0122] Test Case

[0123] The detection limit was evaluated according to the blank standard deviation method in part b of Section 5.4.2.2 of GB / T 27417-2017.

[0124] S1: Weigh 1 g of a blank matrix sample into a 10 mL volumetric flask, add 5 μL of a standard stock solution containing each residual monomer with a mass concentration of about 2000 mg / L (obtained in step (i) of the above-mentioned Preparation Example A), dilute to the mark with acetone, and obtain solution A; filter solution A with a 0.45 μm organic nylon filter membrane to obtain filtered solution A;

[0125] S2: The contents of the residual monomers in solution A were determined by a method similar to that in Example 1, except that in step (2) and step (3), the filtered solution A was used to replace the filtered test solution I in Example 1, and the rest was the same as in Example 1; a total of 10 parallel tests were performed.

[0126] The standard deviation obtained from the results of 10 parallel tests was 0.62;

[0127] According to detection limit = 3 × standard deviation, the actual detection limit of this method is calculated to be 1.86 mg / kg, which is approximately 0.0002% (2.0 mg / kg).

[0128] It can be seen from the above results that the method for detecting the residual monomer content in the synthetic resin emulsion provided by the present invention does not require the additional configuration of a headspace sampler, thereby saving instrument costs; the method provided by the present invention has high accuracy, good recovery rate and a detection limit (0.0002% (2.0 mg / kg)) that is lower than the detection limit (0.001% (10 mg / kg)) of the method specified in GBT20623-2006.

[0129] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for detecting the residual monomer content in a synthetic resin emulsion, characterized in that: The method includes: (1) Without using a headspace sampler, a standard solution containing at least 10 residual monomer standards is subjected to gas chromatography analysis I to obtain the chromatographic peak area y of each residual monomer in the standard solution. i ; The residual monomers include: acrylamide, methyl acrylate, tert-butyl acrylate, acrylonitrile, vinyl acetate, ethyl acrylate, methyl methacrylate, butyl acrylate, styrene and isooctyl acrylate; The gas chromatography analysis I is carried out in a programmed temperature rise method I, the chromatographic column of the gas chromatography analysis I is a DB-624 chromatographic column, and the conditions of the programmed temperature rise I include: first, keeping the temperature at T1 for 3-5 minutes, then heating to T2 at a rate of 4-6°C / min, then heating to T3 at a rate of 15-25°C / min, and keeping the temperature at T3 for 3-8 minutes; wherein, T1≤50°C, T2=150-180°C, T3=220-250°C; Define the mass concentration of each residual monomer standard in the standard solution as x i , establish y i With x i The curve equation is Equation I: Equation I y i =k i × i +b i ; and the correlation coefficient R of equation I 2 ≮0.995; (2) Without using a headspace injector, the synthetic resin emulsion test solution is subjected to gas chromatography analysis II to obtain the chromatographic peak area A of each residual monomer in the test solution. i ; (3) Calculate the content of each residual monomer in the synthetic resin emulsion according to equation II: Equation II X% = (A i -b i ) / k i ×V / (M×10 6 )×100%; X% is the mass percentage of each residual monomer in the solution to be tested; M is the mass of the synthetic resin emulsion in the solution to be tested, in g; V is the volume of the solution to be tested, in mL.

2. The method according to claim 1, wherein: In step (1), T1 = 45-50°C, T2 = 155-165°C, and T3 = 235-245°C.

3. The method according to claim 1 or 2, wherein: In step (1), the mass concentration of each residual monomer standard in the standard solution is independently 10-100 mg / L.

4. The method according to any one of claims 1 to 3, wherein: The solvents in the standard solution and the solution to be tested are both acetone.

5. The method according to any one of claims 1 to 4, wherein: The conditions of the gas chromatography analysis I include: column flow rate of 2.0-3.0 mL / min, split ratio of 5-10:1, and injection port temperature of 250-280°C.

6. The method according to any one of claims 1 to 5, wherein: The conditions of the gas chromatography analysis I also include: the temperature of the detector is 280-300° C., the hydrogen flow rate is 30-50 mL / min, the air flow rate is 380-420 mL / min, and the tail gas flow rate is 25-35 mL / min.

7. The method according to any one of claims 1 to 6, wherein: The gas chromatography analysis II is performed by means of programmed temperature rise II, and the conditions of the programmed temperature rise II are the same as the conditions of the programmed temperature rise I in the gas chromatography analysis I.

8. The method according to any one of claims 1 to 7, wherein: The method further comprises, before performing the gas chromatography analysis I and the gas chromatography analysis II, filtering the standard solution and the solution to be tested respectively through an organic nylon filter membrane.

9. The method according to any one of claims 1 to 8, wherein: The chromatographic separation degree of any two adjacent residual monomer chromatographic peaks is 1.5-1.

8.

10. The method according to any one of claims 1 to 9, wherein: When the residual monomer is acrylamide, k i =0.72316, b i =-0.04415; And / or, when the residual monomer is methyl acrylate, k i =0.59687, b i =-0.00696; And / or, when the residual monomer is tert-butyl acrylate, k i =0.94403, b i =-0.01092.

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