CN103399111B - Method for selectively measuring ethylene glycol monoethyl ether acetate in dry food packaging paper based on headspace-gas chromatography/mass spectrometry - Google Patents

Abstract

The invention discloses a method for selectively measuring ethylene glycol ethyl ether acetate in dry food packaging paper based on headspace-gas chromatography, and belongs to the technical field of physical and chemical index detection of packaging materials. After the dry food wrapping paper was treated with headspace at 140°C for 30 minutes, naphthalene was used as internal standard, HP-VOC column was used, GC was detected by selected ion scanning mode, and internal standard method was used for quantification. The quantitative detection limit of the target ethylene glycol ether acetate was 0.031 μg/mL, the standard addition recovery was 87.5%-96.0%, and the relative standard deviation was 1.97-3.91%. The determination method avoids the cumbersome steps of solvent extraction, greatly improves the detection sensitivity through selective ion detection and quantification, has few interference factors, simple operation, high recovery rate and good repeatability.

Description

A method for the selective determination of ethylene glycol ether acetate in dry food packaging paper based on headspace-mass chromatography

technical field

The invention belongs to the technical field of detection of physical and chemical indicators of packaging materials, and specifically relates to a selective determination of ethylene glycol in dry food packaging paper (mainly including instant food packaging paper, candy paper, pasta paper, etc.) based on headspace-mass spectrometry. Alcohol ether acetate method.

Background technique

Ethylene glycol ether acetate, also known as 2-ethoxyethyl acetate, ethyl acetate cellosolve, ethylene glycol ether acetate, is a colorless liquid with a faint odor similar to aromatic resin, slightly soluble In water, miscible in most organic solvents such as aromatic hydrocarbons. Ethylene glycol ether acetate is often used as a solvent and paint remover for nitrocellulose, resins, and oils. It is widely used in high-grade paints and has good compatibility and pigment dispersion. On July 1, 1998, the National Environmental Protection Agency, the Economic and Trade Commission, the Ministry of Foreign Trade and Economic Cooperation, and the Ministry of Public Security issued a document ([1998] No. 089) to provide the "National Hazardous Waste List", which includes ethylene glycol ether and its esters and other substances. In 2001, the No. 255 document of the Ministry of Health stipulated that the use of ethylene glycol ethyl ether acetate and other substances in indoor coatings is prohibited. In June 2011, ethylene glycol ether acetate was included in the fifth batch of SVHC list by REACH regulations, and it was classified as a type 2 reproductive system toxic substance.

Dry food packaging paper is an indispensable and important part of food packaging, and its safety is a very important aspect of the overall safety of food, and the source of safety control of food packaging materials is basically the production raw materials. In view of the fact that ethylene glycol ether acetate is very likely to be used as a raw material in the production process of paper. Therefore, it is important to explore a fast and accurate detection method for ethylene glycol ether acetate phenol to effectively control ethylene glycol ether acetate in dry food packaging paper and ensure the safety of dry food packaging paper. very urgent and necessary.

At present, the detection of ethylene glycol ether acetate is mainly concentrated on paint and coating samples, and gas chromatography is mostly used. Guo Dengfeng and others established a gas chromatographic analysis method for the content of ethylene glycol ethyl ether acetate in automotive paint. Using a PEG-20M large-bore capillary column, the automotive paint sample was extracted with n-hexane, shaken and extracted for 20 minutes, then stood still, and the supernatant was taken liquid detection. The recovery rate of ethylene glycol ethyl ether acetate is between 98.5% and 101.4%, with a relative standard deviation of 0.65%. Nie Weian and others chose dimethyl polysiloxane column capillary separation column AT.SE-30, using dimethyl carbonate-butyl acetate (volume ratio 2:1) mixed solvent as the extraction solvent, internal standard method for quantification, and established A gas chromatographic method for the simultaneous determination of xylene and ethylene glycol ether acetate in paint solvents. Using this method, the recovery rate of ethylene glycol ether acetate is 101.4% to 102.5%, and the relative standard deviation is not more than 2.0%. Chen Huiming and others used the HP-5 chromatographic column to extract the paint sample with a mixed solvent of petroleum ether-acetone (volume ratio 1:1), ultrasonically extracted for 15 minutes, centrifuged, added anhydrous sodium sulfate for dehydration, and filtered through an organic membrane to detect the paint samples. ethylene glycol ether acetate and ethylene glycol butyl ether acetate, wherein the detection limit of ethylene glycol ether acetate is 0.1ng, the recovery rate is 91.20%-102.58%, and the relative standard deviation is 0.69%-2.1 %. Zhu Huaiyuan and others used GC/MS method to simultaneously and rapidly determine 5 kinds of harmful substances such as ethylene glycol ethyl ether acetate in food packaging paper. The sample uses methanol as a solvent. After ultrasonic extraction and filtration, the sample is analyzed by GC/MS selected ion detection. %.

The above detection methods all use a certain amount of organic solvents in the treatment of samples, and some solvents will cause certain harm to the human body and the environment; at the same time, the sensitivity of some analytical methods is not ideal, and for samples with complex matrices, the qualitative confirmation results are not enough ideal.

Contents of the invention

Purpose of the invention: for the deficiencies in the prior art, the purpose of the invention is to provide a method based on headspace-mass chromatography for selective determination of ethylene glycol ether acetate in dry food packaging paper, which can quickly and Accurately detect the content of ethylene glycol ether acetate in dry food packaging paper, with the characteristics of accurate measurement results and less measurement interference.

Technical solution: In order to realize the above-mentioned purpose of the invention, the technical solution adopted in the present invention is as follows:

A method for selective determination of ethylene glycol ether acetate in dry food wrapping paper based on headspace-gas chromatography, comprising the steps:

(1) Take the standard substance ethylene glycol ether acetate, and use glycerol triacetate to make a standard stock solution;

(2) Take the internal standard naphthalene, and use glycerol triacetate to form a glycerol triacetate solution of naphthalene, which is used as a matrix solvent for standby;

(3) Take multiple parts of the standard stock solution, add different amounts of matrix solvent, and use glycerol triacetate to constant volume to obtain a series of standard working solutions with different concentration gradients. GC/MS-SIM detection was carried out after the sample; the concentration (μg/mL) ratio X of ethylene glycol ether acetate and internal standard naphthalene was taken as the abscissa, and the peak area of ethylene glycol ether acetate and internal standard naphthalene Ratio Y is the ordinate, perform linear regression, draw the standard curve of the target object, and calculate the regression equation of the standard curve of the target object;

(4) Cut the dry food packaging paper and put it in the headspace bottle, add matrix solvent, seal it quickly, and perform headspace treatment. After the sampling is balanced, enter the GC/MS-SIM through the transmission line, and perform GC/MS-SIM For detection and analysis, the ratio of the peak area of the obtained ethylene glycol ether acetate to the peak area of the internal standard naphthalene is respectively substituted into the backhaul equation, and the corresponding content of the ethylene glycol ether acetate in the dry food packaging can be obtained by calculation.

In step (1), the concentration of the standard stock solution is 5-15 μg/mL.

In step (2), the concentration of the matrix solvent is 0.3-0.7 μg/mL.

In step (3), a series of standard working solutions with different concentration gradients were 5 parts, the concentrations of ethylene glycol ether acetate in the solution were 0.05, 0.1, 0.5, 1 and 5 μg/mL, and the concentrations of the internal standard naphthalene were 0.5 μg/mL.

In step (3) and step (4), the headspace analysis conditions are the same, both: sample equilibration temperature: 140°C; sample loop temperature: 150°C; transfer line temperature: 160°C; sample equilibration time: 30min; Compression pressure: 15psi; carrier gas pressure: 20psi; pressurization time: 0.2min; aeration time: 0.2min; sample loop equilibrium time: 0.05min; sampling time: 0.5min.

In step (3) and step (4), the analysis conditions of GC/MS are the same, both are:

Gas chromatography conditions: HP-VOC (60m×0.32mm×1.80μm) capillary chromatographic column is used, the carrier gas is helium, the flow rate is 1.5mL/min, the injection volume is 1μL, and the temperature of the injection port is 220℃. Split sampling method, the temperature rise program is that the initial temperature is 50°C, keep for 5min, increase to 200°C at a rate of 8°C/min, and keep for 5min;

Mass spectrometry conditions: transfer line temperature is 240°C, ionization mode is EI, ion source temperature is 230°C;

The quadrupole temperature is 150°C, the solvent delay time is 15min, and the scanning mode is selected ion scanning mode (SIM). are 43, 59, 72, and the monitoring time for each ion is 50ms.

In step (3), the regression equation of ethylene glycol ether acetate is Y=0.1875X-0.000442, the correlation coefficient is 0.9999, the linear range is 0.05-5 μg/mL and the detection limit is 0.031 μg/mL.

In step (4), 1-5 mL of matrix solvent is added to each sample to be tested with a clipped area of 80 cm ² .

Beneficial effect: Compared with the prior art, the method of the present invention based on headspace-mass spectrometry selective determination of ethylene glycol ethyl ether acetate in dry food wrapping paper can be extracted from dry food wrapping paper Ethylene glycol ethyl ether acetate, so that it can be qualitatively confirmed and quantitatively detected by GC/MS method, which has the following significant advantages:

(1) For the determination of ethylene glycol ethyl ether acetate, the prior art mostly uses external standard method for quantification. For the complex background system brought by different papers, the quantitative determination of the target object will inevitably interfere; and the method of the present invention utilizes the internal standard method Quantitative, without constant volume, and can reduce the error caused by the reproducibility of the pre-treatment method and the precision of the instrument;

(2) The method of the present invention is simple in pretreatment, avoids the cumbersome steps of solvent treatment, and the sensitivity is greatly improved by SIM detection and quantification. The experimental results show that the method has the characteristics of simple sample pretreatment, good repeatability, high accuracy, rapid sensitivity, etc., and is suitable for the determination of the content of ethylene glycol ethyl ether acetate in dry food packaging paper.

Description of drawings

Figure 1 is a graph showing the effect of headspace equilibration time on peak area;

Fig. 2 is the impact result diagram of headspace equilibrium temperature on peak area;

Fig. 3 is the chromatogram of the selected ion of standard working solution; Among the figure, peak 1 is ethylene glycol ethyl ether acetate, and peak 2 is naphthalene;

Figure 4 is a chromatogram of selected ions of a typical spiked sample; in the figure, peak 1 is ethylene glycol ether acetate, and peak 2 is naphthalene.

Detailed ways

The present invention will be further described below in conjunction with specific examples.

Materials, reagents and instruments used in the following examples are as follows:

20 dry food wrapping papers such as instant food wrapping paper, candy paper, and pasta paper; glycerol triacetate (analytical grade, Sinopharm Chemical Reagent Co., Ltd.); ethylene glycol ethyl ether acetate, naphthalene (chromatographic pure , Dr Ehrenstorfer); 6890N/5975 gas chromatography-mass spectrometry (Agilent, USA), equipped with G1888 automatic headspace instrument; HP-VOC capillary column (60m×0.32mm×1.80μm); electronic balance (METTLER TOLEDO company, sense amount 0.1mg).

Embodiment 1 Sample processing and analysis

Accurately weigh 0.1 g of ethylene glycol ethyl ether acetate into a 100 mL volumetric flask, and dilute to volume with glycerol triacetate to obtain a primary standard stock solution with a concentration of 1000 μg/mL. Pipette 1mL of the primary standard stock solution and dilute to a 100mL volumetric flask to obtain a secondary standard stock solution with a concentration of 10μg/mL.

Accurately weigh 0.1 g of naphthalene in a 100 mL volumetric flask, and dilute to volume with glycerol triacetate to obtain a primary internal standard stock solution with a concentration of 1000 μg/mL. Pipette 1mL of the primary internal standard stock solution to a 100mL volumetric flask to obtain a secondary internal standard stock solution with a concentration of 10μg/mL. Take 0.5mL secondary internal standard stock solution in a 10mL volumetric flask, dilute to volume with glycerol triacetate, and use it as matrix solvent for later use. The internal standard concentration is 0.5μg/mL.

Accurately cut 80 cm ² samples, put them in a headspace bottle, add 1 mL of matrix solvent with an internal standard concentration of 0.5 μg/mL, quickly press the bottle cap tightly, and put it into a headspace sampler for GC/MS detection and analysis. The detection and analysis conditions are:

Headspace conditions: sample equilibration temperature: 140°C; sample loop temperature: 150°C; transfer line temperature: 160°C; sample equilibration time: 30min; sample bottle pressurization pressure: 15psi; carrier gas pressure: 20psi; pressurization time: 0.2min ; Insufflation time: 0.2min; Sample loop equilibrium time: 0.05min; Injection time: 0.5min.

GC/MS conditions: HP-VOC (60m×0.32mm×1.80μm) capillary chromatographic column, the carrier gas is helium, the flow rate is 1.5mL/min, the injection volume is 1μL, the injection port temperature is 220°C, using different Split injection method, the heating program is the initial temperature of 50°C (5min), 8°C/min, 200°C (5min); mass spectrometry conditions: transfer line temperature is 240°C, ionization mode is EI, ion source temperature is 230°C, The quadrupole temperature is 150°C, the solvent delay time is 15min, and the scanning mode is selected ion scanning mode (SIM). are 43, 59, 72, and the monitoring time for each ion is 50ms.

The comparative retention time and characteristic ion abundance ratio were used for qualitative analysis, and the internal standard method was used for quantitative analysis in SIM mode. The retention times and characteristic ions of the target and internal standard are shown in Table 1 below.

Table 1 Retention time and characteristic ions of target and internal standard

Example 2

Accurately pipette 50 μL of 6 copies of the secondary standard stock solution with a concentration of 10 μg/mL, then add 50 μL of the secondary internal standard stock solution with a concentration of 10 μg/mL, and dilute to 1 mL with triacetin to obtain a concentration of 0.5 μg/mL standard solution and internal standard solution with a concentration of 0.5 μg/mL. Referring to the method of Example 1, the headspace gas at different equilibrium temperatures (60, 80, 100, 120, 140 and 160°C) was analyzed under the same equilibrium time (30min), and the influence of the equilibrium temperature on the response value was investigated ( see picture 1). It can be seen from the results that as the equilibrium temperature increases, the peak area response value of the target substance and internal standard increases gradually, and the growth rate is slow between 60 and 100 °C, and the growth rate is fast between 100 and 140 °C. Then it slowed down. Considering the physical and chemical properties of different dry food packaging papers and the boiling point of the target substance, 140°C was selected as the sample equilibrium temperature.

Example 3

According to the method of Example 2, a standard solution with a concentration of 0.5 μg/mL and an internal standard solution with a concentration of 0.5 μg/mL were prepared. Under the same temperature and time (140°C), the headspace gas with different equilibration times (5, 10, 15, 20, 30 and 40min) was analyzed to investigate the effect of equilibration time on the response value (see Figure 2). After 5-30 minutes, the response value of the peak area of the target substance and the internal standard gradually increases, and after 30 minutes, the growth rate tends to be flat. Considering the detection efficiency comprehensively, 30 minutes is preferred as the equilibrium time of the sample.

Example 4

Accurately pipette 5, 10, 50, 100 and 500 μL of the secondary standard stock solution with a concentration of 10 μg/mL into five 20 mL headspace vials, and then add 50 μL of the secondary internal standard stock solution with a concentration of 10 μg/mL respectively, Dilute to 1 mL with glycerol triacetate to obtain standard working solutions with concentrations of 0.05, 0.1, 0.5, 1 and 5 μg/mL, and the concentration of the internal standard is 0.5 μg/mL. With reference to the method of Example 1, the series of standard working solutions were subjected to headspace balance respectively, and then GC/MS analysis (the chromatogram of a typical standard working solution is shown in Figure 3), and the mixture of ethylene glycol ethyl ether acetate and internal standard naphthalene Concentration (μg/mL) ratio X is the abscissa, and the peak area ratio Y of ethylene glycol ethyl ether acetate and internal standard naphthalene is the ordinate, perform linear regression, draw the standard curve of the target substance, and calculate the standard curve of the target substance The regression equation was used to calculate the quantitative limit of the method with 10 times the signal-to-noise ratio (S/N=10). The results are: the regression equation of ethylene glycol ether acetate Y=0.1875X-0.000442, the correlation coefficient is 0.9999, the linear range is 0.05～5μg/mL and the detection limit is 0.031μg/mL.

Taking a fast food packaging paper (the actual detection value was not detected) as the research object, three different concentrations (0.1, 0.5 and 2 μg/mL) of standard solutions (0.1, 0.5 and 2 μg/mL) were added respectively, and headspace-GC The selectivity method was used to determine the corresponding target substance content (the average value of 6 measurements), and the standard addition recovery rate of the method was calculated according to the measurement results and the amount of standard substance added (see Table 2 below). The results showed that the standard recovery of the method was between 87.5% and 96.0%, indicating that the accuracy of the method was high; the relative standard deviation (RSD) was 3.91%, less than 5%, indicating that the repeatability of the method was good.

Table 2 The spike recovery and precision of the method (n=6)

Spike level Recovery rate(%) RSD (%) Low 87.5 3.91 middle 92.3 2.25 high 96.0 1.97

According to the above method, 20 samples of dry food packaging paper (including instant food packaging paper, candy paper, pasta paper, etc.) were tested, and no ethylene glycol ether acetate was detected. In addition, a candy paper was used as the measurement object (the measured value was not detected), and a standard sample with a concentration of 2 μg/mL was added to it, and the measured value was 1.93 mg/kg, with a relative deviation of 1.78%. As shown in Figure 4, it can be seen that the accuracy of the measurement results is better.

Therefore, the method for the selective determination of ethylene glycol ether acetate in dry food wrapping paper based on headspace-mass chromatography provided by the present invention can effectively avoid the cumbersome steps of solvent extraction in the sample pretreatment process, and can be detected by SIM Quantification can greatly improve the detection sensitivity and qualitative accuracy. The experimental results show that the method has the characteristics of simple sample pretreatment, good repeatability, high accuracy, rapid sensitivity, etc., and is suitable for the determination of the content of ethylene glycol ethyl ether acetate in dry food packaging paper.

The internal standard solution and standard solution used in this embodiment are only described with one concentration as an example. The internal standard solution and standard solution configured with other concentration values are analyzed by chromatography and mass spectrometry. The standard curve and regression equation are the same as the above-mentioned The embodiments are the same and will not be listed one by one here. The examples given are only for better understanding of the method of the present invention, and do not have any limiting effect, that is, the above-mentioned methods or methods equivalent to the above-mentioned situations are all included in the protection scope of the technical solution of the present invention.

Claims (6)

1. A method based on headspace-mass mass spectrometry selective determination of ethylene glycol ether acetate in dry food wrapping paper, is characterized in that, comprises the steps: (1) get standard substance ethylene glycol ethyl ether acetate, make standard stock solution with glycerol triacetate; (2) get internal standard substance naphthalene, be made into triacetin solution of naphthalene with glyceryl triacetate, standby as matrix solvent; (3) Take multiple parts of the standard stock solution, add different amounts of matrix solvents, and use glycerol triacetate to constant volume to obtain a series of standard working solutions with different concentration gradients. Carry out GC/MS-SIM detection after sample; Take the concentration ratio X of ethylene glycol ethyl ether acetate and internal standard naphthalene as abscissa, take the peak area ratio Y of ethylene glycol ethyl ether acetate and internal standard naphthalene as ordinate , perform linear regression, draw the standard curve of the target substance, and calculate the regression equation of the standard curve of the target substance; (4) Cut the dry food packaging paper and place it in the headspace bottle, add matrix solvent, seal it quickly, and perform headspace treatment. After the sampling is balanced, enter the GC/MS-SIM through the transmission line, and perform GC/MS-SIM Detection and analysis, the ratio of the peak area of the obtained ethylene glycol ether acetate to the peak area of the internal standard naphthalene is substituted into the backhaul equation respectively, and the corresponding content of the ethylene glycol ether acetate in the dry food packaging can be obtained by calculation; Among them, in step (3) and step (4), the headspace analysis conditions are the same, both: sample equilibrium temperature: 140°C; sample loop temperature: 150°C; transfer line temperature: 160°C; sample equilibrium time: 30min; Bottle pressurization pressure: 15psi; carrier gas pressure: 20psi; pressurization time: 0.2min; aeration time: 0.2min; sample loop equilibrium time: 0.05min; sample injection time: 0.5min; In step (3) and step (4), the analysis condition of GC/MS is identical, is: Gas chromatographic conditions: HP-VOC capillary column is used, the carrier gas is helium, the flow rate is 1.5mL/min, the injection volume is 1μL, the injection port temperature is 220°C, the splitless injection method is adopted, and the heating program is initial The temperature is 50°C, keep for 5min, increase to 200°C at a rate of 8°C/min, and keep for 5min; Mass spectrometry conditions: transfer line temperature is 240°C, ionization mode is EI, ion source temperature is 230°C; The quadrupole temperature is 150°C, the solvent delay time is 15min, and the scanning mode is selected ion scanning mode, in which the selected ions of the target ethylene glycol ethyl ether acetate are 128, 102, and the selected ions of the internal standard naphthalene are 43, 59, 72, the monitoring time for each ion is 50ms. 2. the method for the selective determination of ethylene glycol ether acetate in dry food wrapping paper based on headspace-mass chromatography according to claim 1, is characterized in that, in step (1), the concentration of standard stock solution It is 5~15μg/mL. 3. according to claim 1 and 2, based on headspace-mass mass spectrometry, the method for selective determination of ethylene glycol ether acetate in dry food wrapping paper, is characterized in that, in step (2), matrix solvent The concentration is 0.3-0.7 μg/mL. 4. according to claim 1 or 2, based on headspace-mass mass spectrometry selective determination of the method for ethylene glycol ether acetate in dry food packaging paper, it is characterized in that, in step (3), a series of different The concentration gradient standard working solution is 5 parts, the concentration of ethylene glycol ether acetate in the solution is 0.05, 0.1, 0.5, 1 and 5 μg/mL, and the concentration of internal standard naphthalene is 0.5 μg/mL. 5. the method for the selective determination of ethylene glycol ether acetate in dry food wrapping paper based on headspace-mass mass spectrometry according to claim 1, is characterized in that, in step (3), ethylene glycol ether ethyl ether The regression equation of the ester is Y=0.1875X-0.000442, the correlation coefficient is 0.9999, the linear range is 0.05-5 μg/mL and the detection limit is 0.031 μg/mL. 6. the method based on headspace-mass mass spectrometry according to claim 1 in the selective determination of ethylene glycol ether acetate in dry food wrapping paper, is characterized in that, in step (4), in every clipping area is Add 1-5mL of matrix solvent to 80cm ² of the sample to be tested.