Method for measuring content of volatile organic solvent in cleaning agent by headspace gas chromatography

Abstract

The invention belongs to the technical field of chemical detection, and provides a method for determining the content of volatile organic solvents in a cleaning agent by headspace gas chromatography. The method comprises the following steps: feeding a to-be-detected sample solution and a to-be-detected series of reference substance solutions by a headspace method, respectively passing through an Rxi-5Sil MS chromatographic column and a DB-624 chromatographic column, carrying out temperature programming separation, then entering a mass spectrometry detector for detection, and qualitatively judging the volatile organic solvent in the to-be-detected sample solution according to a chromatographic peak, and substituting the qualitatively judged area of the chromatographic peak into the standard working curve to obtain the concentration of the volatile organic solvent. The reference substance solution is prepared by adopting a simulation sample standard adding mode, so that on one hand, a measured matrix is closer to a real sample, and on the other hand, a reference substance can be better dissolved in a water-based matrix; the sample liquid is detected by adopting static headspace sampling in combination with the gas chromatography-mass spectrometry, pretreatment is not needed, the operation process is simplified, and the working efficiency is improved.

Description

Technical Field

[0001] The invention relates to the technical field of chemical detection, and in particular to a method for determining the content of volatile organic solvents in a cleaning agent by using a headspace gas chromatography method. Background Art

[0002] Volatile organic compounds (VOCs) refer to organic compounds that have a boiling point of 50 to 250°C at normal pressure (101.32 kPa) and exist in the air in the form of vapor at room temperature. Benzene series (BTEX) and volatile halogenated hydrocarbons (VHC) are two typical VOCs. As intermediates for pesticides, detergents, solvents and other compounds, they are widely used in laboratories, medicine, chemicals and people's daily lives. Compared with other VOCs (such as alkanes and alkenes), exposure to BTEX and VHCs poses a greater risk of cancer.

[0003] BTEX and VHC may be used as organic solvents in household cleaners, especially in strong decontamination products such as household cleaners. The addition of organic solvents can achieve multiple functions such as solubilization and decontamination at a low cost, but ignoring the toxicity of solvents and excessive use will pose a serious threat to the health of ordinary consumers, so they must be strictly controlled. At present, my country does not have a testing standard for volatile organic solvents in detergents. Relevant literature reports are mostly concentrated in the field of cosmetics, and their applicability to detergents has yet to be verified.

[0004] Gas chromatography-mass spectrometry (GC-MS) is a commonly used analytical method for detecting BTEX and VHC in liquid samples. However, the method is currently mainly used to study a single type of compound (such as BTEX and halogenated hydrocarbons such as dichloromethane, trichloroethylene, perchloroethylene, tetrachloroethylene and dichloromethane), and there are few studies on methods for the simultaneous detection of multiple types of VOCs. Due to the wide variety of VOCs, large differences in water solubility, complex chemical structures, and different pretreatment conditions for different types of VOCs, the determination method can meet the analysis requirements of a single type of compound, but it is difficult to simultaneously meet the detection requirements of trace residual concentrations of different compounds in detergents.

[0005] Therefore, in order to meet the needs of sensitive and rapid detection of different types of VOCs, it is urgent to establish a method suitable for the simultaneous determination of different types of trace VOCs. Summary of the invention

[0006] The purpose of the present invention is to provide a method for determining the content of volatile organic solvents in a cleaning agent by headspace gas chromatography in order to overcome the deficiencies of the prior art, and to solve the problems of low working efficiency, lack of specificity and complicated pre-treatment process of the existing detection methods.

[0007] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0008] The present invention provides a method for determining the content of volatile organic solvents in a cleaning agent by headspace gas chromatography, comprising the following steps:

[0009] 1) mixing a detergent sample and water to obtain a sample solution, and adding the sample solution to a headspace bottle containing sodium chloride to obtain a sample solution to be tested;

[0010] 2) mixing an alkylbenzene sulfonic acid active substance, a fatty alcohol polyoxyethylene ether, an ethylated alkyl sodium sulfate active substance, triethanolamine, trisodium citrate dihydrate, a preservative and water to obtain a simulated sample;

[0011] The volatile organic solvent and methanol are mixed to obtain a mixed reference substance stock solution;

[0012] The mixed reference substance stock solution is dropped into the simulated sample to obtain a series of reference substance solutions;

[0013] Add the series of reference substance solutions into the headspace bottle containing sodium chloride to obtain the series of reference substance solutions to be tested;

[0014] 3) Using headspace gas chromatography-mass spectrometry to detect the sample solution and the series of reference solution to be tested, the sample solution and the series of reference solution to be tested are injected by headspace method, respectively passed through Rxi-5Sil MS chromatographic column and DB-624 chromatographic column, and then enter into mass spectrometry detector for detection after programmed temperature separation, and characteristic chromatograms of the sample solution and the series of reference solution to be tested on the two chromatographic columns are obtained, and the volatile organic solvent in the sample solution to be tested is qualitatively determined according to the chromatographic peaks;

[0015] 4) Using headspace gas chromatography-mass spectrometry to detect the series of reference solution to be tested, the series of reference solution to be tested is sampled in the headspace, passed through a DB-624 chromatographic column, separated by programmed temperature, and then entered into a mass spectrometer for detection, to obtain a standard working curve with the chromatographic peak area as the ordinate and the concentration as the abscissa;

[0016] Substituting the area of ​​the chromatographic peak that is qualitatively determined to contain a certain volatile organic solvent in step 3) into the standard working curve to obtain the concentration of the volatile organic solvent, and calculating the content of the volatile organic solvent in the detergent sample; when it is qualitatively determined to contain multiple volatile organic solvents, repeat the above operation to calculate the content of each volatile organic solvent respectively;

[0017] There are 15 kinds of volatile organic solvents, including chloroform, carbon tetrachloride, 1,1,2-trichloroethane, 1,1,2,2-tetrachloroethane, 1,1,1,2-tetrachloroethane, 1-chloropentane, 1,1-dichloroethylene, tetrachloroethylene, benzene, toluene, ethylbenzene, chlorobenzene, o-xylene, m-xylene and p-xylene.

[0018] Preferably, in the headspace bottle of step 1), the volume of the sample solution is 2-3 mL, and the mass of sodium chloride is 0.5-0.7 g; in the headspace bottle of step 2), the volume of the series of reference solutions is 2-3 mL, and the mass of sodium chloride is 0.5-0.7 g.

[0019] Preferably, in the simulated sample of step 2), the mass content of alkylbenzene sulfonic acid active ingredient is 7-9%, the mass content of fatty alcohol polyoxyethylene ether is 3-5%, the mass content of ethylated alkyl sodium sulfate active ingredient is 1.5-2.5%, the mass content of triethanolamine is 0.3-0.8%, the mass content of trisodium citrate dihydrate is 0.4-0.8%, and the mass content of preservative is 0.08-0.12%; the pH value of the simulated sample is 8.5-9.0.

[0020] Preferably, in the mixed reference stock solution, the mass content of each organic solvent is 10 mg / mL; in the series of reference solutions, the concentration of each volatile organic solvent is independently 10 μg / mL, 20 μg / mL, 50 μg / mL, 100 μg / mL, and 500 μg / mL.

[0021] As a preferred embodiment, the chromatogram of the sample solution on the Rxi-5Sil MS chromatographic column is P 样1 The chromatogram of the sample solution on the DB-624 column is P 样2 The chromatogram of the reference solution to be tested on the Rxi-5Sil MS column is P 标1 The chromatogram of the reference solution to be tested on the DB-624 column is P 标2 ;

[0022] P 样1 and P 标1 For comparison, when P 样1 and P 标1 When chromatographic peaks with similar retention times appear in the 样2 and P 标2 For comparison, if P 样2 and P 标2 There is also a chromatographic peak with a close retention time in P 标1 and P 标2 If the same volatile organic solvent is found in the sample, it is determined that the sample solution contains the above volatile organic solvent.

[0023] Preferably, the headspace conditions are: equilibrium temperature 75-85°C, equilibrium time 25-35 min, quantitative loop temperature 95-105°C, and transfer line temperature 105-115°C.

[0024] Preferably, the conditions for chromatographic detection are: Rxi-5SilMS chromatographic column specifications are 30m×0.25mm×0.25μm, the carrier gas is helium with a purity of>99.99%, the flow rate is 35-50mL / min, the injection port temperature is 230-250°C, the detector temperature is 240-260°C, the injection method is split injection, the split ratio is 20:1, the injection volume is 1μL, the initial temperature of the chromatographic column is 35-45°C, maintained for 4-6min, heated to 170°C at a rate of 10°C / min, and then heated to 240°C at a rate of 40°C / min, and maintained for 5-7min;

[0025] The specifications of the DB-624 chromatographic column are 30m×0.25mm×1.40μm, the carrier gas is helium with a purity of >99.99%, the flow rate is 35-50mL / min, the injection port temperature is 230-250℃, the detector temperature is 240-260℃, the split injection, the split ratio is 20:1, the injection volume is 1μL, the initial temperature of the chromatographic column is 50℃, maintained for 2-3min, heated to 200℃ at a rate of 20℃ / min, and then heated to 240℃ at a rate of 40℃ / min, and maintained for 5-7min.

[0026] Preferably, the conditions for mass spectrometry detection are: the ionization mode is electron bombardment source, the ion source temperature is 200° C., the interface temperature is 240° C., the ionization energy is 70 eV, the solvent delay time is 0.2 min, and the scanning mode is full scan.

[0027] The beneficial effects of the present invention include the following:

[0028] 1) The present invention uses headspace gas chromatography-mass spectrometry dual chromatographic column qualitative comparison to determine whether chloroform, carbon tetrachloride, 1,1,2-trichloroethane, 1,1,2,2-tetrachloroethane, 1,1,1,2-tetrachloroethane, 1-chloropentane, 1,1-dichloroethylene, tetrachloroethylene, benzene, toluene, ethylbenzene, chlorobenzene, o-xylene, m-xylene and p-xylene are present in household cleaning agents, and external standard quantitative analysis is used to accurately determine the content of each component.

[0029] 2) The present invention adopts a method of spiking simulated samples to prepare reference solution, which makes the determination matrix closer to the real sample on the one hand, and makes the reference substance better dissolved in the aqueous matrix on the other hand; static headspace injection combined with gas chromatography-mass spectrometry is used to detect the sample solution, without the need for pretreatment, simplifying the operation process and improving work efficiency.

[0030] 3) The present invention adopts two chromatographic columns, the non-polar column Rxi-5SilMS and the neutral column DB-624, to examine the retention time of 15 volatile organic solvents for qualitative analysis, thereby solving the problem of not being able to separate all components and co-flow of multiple components, and is suitable for qualitative analysis of complex samples; and then uses the characteristic ion quantification method of DB-624 column separation and detection for quantitative analysis to remove interference from miscellaneous peaks and improve accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 The gas chromatograms of 15 volatile organic solvents of the reference substance solutions to be tested in the examples on the neutral column DB-624;

[0032] Figure 2 The gas chromatograms of 15 volatile organic solvents of the reference substance solutions to be tested in the examples on the non-polar column Rxi-5SilMS;

[0033] Figure 3 The gas chromatogram of the sample liquid to be tested in Example 1;

[0034] Figure 4 The gas chromatogram of the sample liquid to be tested in Example 2;

[0035] Figure 5 The gas chromatogram of the sample liquid to be tested in Example 3;

[0036] Figure 6 The gas chromatogram of the sample liquid to be tested in Example 4;

[0037] Figure 7 This is the gas chromatogram of the sample liquid to be tested in Example 5. DETAILED DESCRIPTION

[0038] The present invention provides a method for determining the content of volatile organic solvents in a cleaning agent by headspace gas chromatography, comprising the following steps:

[0039] 1) mixing a detergent sample and water to obtain a sample solution, and adding the sample solution to a headspace bottle containing sodium chloride to obtain a sample solution to be tested;

[0040] 2) mixing an alkylbenzene sulfonic acid active substance, a fatty alcohol polyoxyethylene ether, an ethylated alkyl sodium sulfate active substance, triethanolamine, trisodium citrate dihydrate, a preservative and water to obtain a simulated sample;

[0041] The volatile organic solvent and methanol are mixed to obtain a mixed reference substance stock solution;

[0042] The mixed reference substance stock solution is dropped into the simulated sample to obtain a series of reference substance solutions;

[0043] Add the series of reference substance solutions into the headspace bottle containing sodium chloride to obtain the series of reference substance solutions to be tested;

[0044] 3) Using headspace gas chromatography-mass spectrometry to detect the sample solution and the series of reference solution to be tested, the sample solution and the series of reference solution to be tested are injected by headspace method, respectively passed through Rxi-5Sil MS chromatographic column and DB-624 chromatographic column, and then enter into mass spectrometry detector for detection after programmed temperature separation, and characteristic chromatograms of the sample solution and the series of reference solution to be tested on the two chromatographic columns are obtained, and the volatile organic solvent in the sample solution to be tested is qualitatively determined according to the chromatographic peaks;

[0045] 4) Using headspace gas chromatography-mass spectrometry to detect the series of reference solution to be tested, the series of reference solution to be tested is sampled in the headspace, passed through a DB-624 chromatographic column, separated by programmed temperature, and then entered into a mass spectrometer for detection, to obtain a standard working curve with the chromatographic peak area as the ordinate and the concentration as the abscissa;

[0046] Substituting the area of ​​the chromatographic peak that is qualitatively determined to contain a certain volatile organic solvent in step 3) into the standard working curve to obtain the concentration of the volatile organic solvent, and calculating the content of the volatile organic solvent in the detergent sample; when it is qualitatively determined to contain multiple volatile organic solvents, repeat the above operation to calculate the content of each volatile organic solvent respectively;

[0047] There are 15 kinds of volatile organic solvents, including chloroform, carbon tetrachloride, 1,1,2-trichloroethane, 1,1,2,2-tetrachloroethane, 1,1,1,2-tetrachloroethane, 1-chloropentane, 1,1-dichloroethylene, tetrachloroethylene, benzene, toluene, ethylbenzene, chlorobenzene, o-xylene, m-xylene and p-xylene.

[0048] In the headspace bottle described in step 1) of the present invention, the volume of the sample solution is preferably 2-3 mL, more preferably 2-2.5 mL, and the mass of sodium chloride is preferably 0.5-0.7 g, more preferably 0.6 g; in the headspace bottle described in step 2), the volume of the series of reference solutions is preferably 2-3 mL, more preferably 2-2.5 mL, and the mass of sodium chloride is preferably 0.5-0.7 g, more preferably 0.6 g.

[0049] In the present invention, for detergent samples that are poorly soluble in water, an appropriate amount of methanol is added to aid dissolution.

[0050] In the simulated sample of step 2) of the present invention, the mass content of alkylbenzene sulfonic acid active matter is preferably 7-9%, more preferably 8%, the mass content of fatty alcohol polyoxyethylene ether is preferably 3-5%, more preferably 4%, fatty alcohol polyoxyethylene ether is preferably fatty alcohol polyoxyethylene ether AEO9, the mass content of ethylated alkyl sodium sulfate active matter is preferably 1.5-2.5%, more preferably 2%, the mass content of triethanolamine is preferably 0.3-0.8%, more preferably 0.5-0.6%, the mass content of trisodium citrate dihydrate is preferably 0.4-0.8%, more preferably 0.6%, the mass content of preservative is preferably 0.08-0.12%, more preferably 0.1%, and the pH value of the simulated sample is preferably 8.5-9.0, more preferably 8.7-8.8.

[0051] In the present invention, the mass content of the active matter of alkylbenzene sulfonic acid in the alkylbenzene sulfonic acid is preferably 97-99%, more preferably 98%; the mass content of the active matter of ethylated sodium alkyl sulfate in the ethylated sodium alkyl sulfate is preferably 69-71%, more preferably 70%.

[0052] In the present invention, in the mixed reference substance stock solution, the mass content of each organic solvent is preferably 10 mg / mL; in the series of reference substance solutions, the concentration of each volatile organic solvent is independently preferably 10 μg / mL, 20 μg / mL, 50 μg / mL, 100 μg / mL, 500 μg / mL.

[0053] In the present invention, the chromatogram of the sample solution on the Rxi-5Sil MS chromatographic column is P 样1 The chromatogram of the sample solution on the DB-624 column is P 样2 The chromatogram of the reference solution to be tested on the Rxi-5Sil MS column is P 标1 The chromatogram of the reference solution to be tested on the DB-624 column is P 标2 ;

[0054] P 样1 and P 标1 For comparison, when P 样1 and P 标1 When chromatographic peaks with similar retention times appear in the 样2 and P 标2 For comparison, if P 样2 and P 标2 There is also a chromatographic peak with a close retention time in P 标1 and P 标2 If the same volatile organic solvent is found in the sample, it is determined that the sample solution contains the above volatile organic solvent.

[0055] In the present invention, the Rxi-5Sil MS chromatographic column is a non-polar column, and the DB-624 chromatographic column is a neutral column.

[0056] In the present invention, the headspace conditions are: the equilibrium temperature is preferably 75-85°C, more preferably 80°C, the equilibrium time is preferably 25-35 min, more preferably 30 min, the quantitative loop temperature is preferably 95-105°C, more preferably 100°C, and the transfer line temperature is preferably 105-115°C, more preferably 110°C.

[0057] In the present invention, the conditions for chromatographic detection are: the specifications of the Rxi-5Sil MS chromatographic column are 30m×0.25mm×0.25μm, the carrier gas is preferably helium with a purity of>99.99%, the flow rate is preferably 35-50mL / min, more preferably 40-45mL / min, the injection port temperature is preferably 230-250°C, more preferably 240°C, the detector temperature is preferably 240-260°C, more preferably 250°C, the injection method is preferably split injection, the split ratio is preferably 20:1, the injection volume is preferably 1μL, the initial temperature of the chromatographic column is preferably 35-45°C, more preferably 40°C, preferably maintained for 4-6min, more preferably maintained for 5min, heated to 170°C at a rate of 10°C / min, and then heated to 240°C at a rate of 40°C / min, and maintained for 5-7min;

[0058] The specifications of the DB-624 chromatographic column are 30m×0.25mm×1.40μm. The carrier gas is preferably helium with a purity of >99.99%. The flow rate is preferably 35-50mL / min, more preferably 40-45mL / min. The injection port temperature is preferably 230-250°C, more preferably 240°C, the detector temperature is preferably 240-260°C, more preferably 250°C, split injection, the split ratio is preferably 20:1, the injection volume is preferably 1μL, the initial temperature of the chromatographic column is preferably 50°C, maintained for 2-3min, heated to 200°C at a rate of 20°C / min, and then heated to 240°C at a rate of 40°C / min, and maintained for 5-7min.

[0059] In the present invention, the conditions for mass spectrometry detection are: the ionization mode is preferably an electron bombardment source, the ion source temperature is preferably 200° C., the interface temperature is preferably 240° C., the ionization energy is preferably 70 eV, the solvent delay time is preferably 0.2 min, and the scanning mode is preferably full scan.

[0060] In the present invention, characteristic qualitative ions and characteristic quantitative ions of 15 volatile organic solvents are shown in Table 1.

[0061] Table 1 Characteristic qualitative ions and characteristic quantitative ions of 15 volatile organic solvents

[0062]

[0063]

[0064] Quantitative analysis:

[0065] A series of reference solutions with concentrations of 10.0 μg / mL, 20.0 μg / mL, 50.0 μg / mL, 100.0 μg / mL, and 500.0 μg / mL were taken for gas chromatography-mass spectrometry detection, and the retention time and the area of ​​the chromatographic peak were recorded. The standard working curve equations of 15 volatile organic solvents were obtained with the area of ​​the chromatographic peak as the ordinate and the concentration as the abscissa, as shown in Table 2.

[0066] Table 2 Standard working curve equations for volatile organic solvents

[0067]

[0068]

[0069] In the present invention, the areas of the target chromatographic peaks detected in the detergent sample are respectively substituted into the standard working curve to calculate the concentrations of chloroform, carbon tetrachloride, 1,1,2-trichloroethane, 1,1,2,2-tetrachloroethane, 1,1,1,2-tetrachloroethane, 1-chloropentane, 1,1-dichloroethylene, tetrachloroethylene, benzene, toluene, ethylbenzene, chlorobenzene, o-xylene, m-xylene and p-xylene in the sample solution to be tested, and the content of each volatile organic solvent in the detergent sample is further calculated.

[0070] The contents of the 15 volatile organic solvents in the sample solution to be tested are calculated according to the concentrations of the 15 volatile organic solvents. The calculation formula is shown in Formula 1.

[0071] X=(c×V) / m Formula 1

[0072] In formula 1, X is the content of each component in the household cleaning solution, mg / kg; c is the concentration of each component in the sample solution to be tested, μg / mL; m is the mass of the household cleaning solution, g; and V is the constant volume of the household cleaning solution, mL.

[0073] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0074] In the embodiments, methanol: chromatographically pure;

[0075] 15 kinds of volatile organic solvents: chloroform purity ≥ 99.5% (GC); carbon tetrachloride purity ≥ 99.6% (GC); 1,1,2-trichloroethane purity ≥ 99.8% (GC); 1,1,2,2-tetrachloroethane purity ≥ 99.8% (GC); 1,1,1,2-tetrachloroethane purity ≥ 99%; 1-chloropentane purity ≥ 99.5% (GC); 1,1-dichloroethane purity ≥ 99.6% (GC); 1,1-dichloroethane purity ≥ 99.8% (GC); 1,1,2,2-tetrachloroethane purity ≥ 99.8% (GC); 1,1,1,2-tetrachloroethane purity ≥ 99% (GC); 1-chloropentane purity ≥ 99.5% (GC); 1,1-dichloroethane purity ≥ 99.6 ...,2-dichloroethane purity ≥ 99.8% (GC); 1,1,2,2-tetrachloroethane purity ≥ 99.8% (GC); 1,1,1,2-te Olefin purity ≥99.9% (GC); tetrachloroethylene purity ≥99.5% (GC); benzene purity ≥99.9% (GC); toluene purity ≥99.5% (GC); ethylbenzene purity ≥99.5% (GC); chlorobenzene purity ≥99.9% (GC); o-xylene purity ≥99% (GC); m-xylene purity ≥99.5% (GC); p-xylene purity ≥99.8% (GC).

[0076] Example 1

[0077] Mixed reference stock solution: Weigh 1 g (accurate to 0.1 mg) of each volatile organic solvent standard sample into a 100 mL volumetric flask, dissolve it with methanol and make up to the mark. The content of each volatile organic solvent in the mixed reference stock solution is 10 mg / mL.

[0078] The series of reference solutions to be tested were prepared by spiking simulated samples. The specific process is as follows:

[0079] S1: Prepare a simulated sample by sequentially adding 16.3 g of alkylbenzene sulfonic acid (98% active matter), 8.0 g of fatty alcohol polyoxyethylene ether AEO9, 5.7 g of ethylated alkyl sodium sulfate (70% active matter), 1 g of triethanolamine, 1.2 g of trisodium citrate dihydrate, and 0.2 g of a preservative into a certain amount of water, stirring to dissolve, adjusting the pH value of the solution to 8.8 with sodium hydroxide, and supplementing the amount of water to 200 g to obtain a simulated sample;

[0080] S2: Pipette the mixed reference stock solution and drop it into the simulated sample to obtain a mixed reference solution with 15 kinds of volatile organic solvents each having a concentration of 500 μg / mL. Perform the same operation to obtain a series of reference solutions with concentrations of 10 μg / mL, 20 μg / mL, 50 μg / mL, and 100 μg / mL, respectively.

[0081] S3: Pipette 2 mL of the series of reference substance solutions respectively, add them into the headspace bottle with 0.6 g of sodium chloride added, seal and shake well to obtain the series of reference substance solutions to be tested.

[0082] Qualitative analysis: headspace gas chromatography-mass spectrometry was used to detect the sample solution and the series of reference solution. The sample solution and the series of reference solution were injected by headspace method, passed through Rxi-5Sil MS column and DB-624 column respectively, and then entered into mass spectrometer for detection after programmed temperature separation. Characteristic chromatograms of the sample solution and the series of reference solution on the two chromatographic columns were obtained, and the volatile organic solvent in the sample solution was qualitatively determined according to the chromatographic peaks.

[0083] The chromatogram of the sample solution on the Rxi-5Sil MS column is P 样1 The chromatogram of the sample solution on the DB-624 column is P 样2 The chromatogram of the reference solution to be tested on the Rxi-5SilMS column is P 标1 The chromatogram of the reference solution to be tested on the DB-624 column is P 标2 ;

[0084] P 样1 and P 标1 For comparison, when P 样1 and P 标1 When chromatographic peaks with similar retention times appear in the 样2 and P 标2 For comparison, if P 样2 and P 标2 There is also a chromatographic peak with a close retention time in P 标1 and P 标2 If the same volatile organic solvent is found in the sample, it is determined that the sample solution contains the above volatile organic solvent.

[0085] The headspace injection conditions were as follows: equilibrium temperature 80°C, equilibrium time 30 min, quantitative loop temperature 100°C, and transfer line temperature 110°C.

[0086] The conditions for gas chromatography detection are as follows: the carrier gas is helium with a purity of >99.99%, the flow rate is 45mL / min, the injection port temperature is 240℃, the detector temperature is 250℃, the injection method is split injection, the split ratio is 20:1, and the injection volume is 1μL; the program heating conditions for gas chromatography detection using a 30m×0.25mm×0.25μm Rxi-5SilMS chromatographic column are as follows: the initial temperature of the chromatographic column is 40℃, maintained for 5min, and then increased to 1 The temperature was raised from 0℃ / min to 170℃, then raised to 240℃ at 40℃ / min, and maintained for 5min. The programmed temperature conditions for gas chromatography detection using a 30m×0.25mm×1.40μm DB-624 chromatographic column were as follows: initial column temperature 50℃, maintained for 2min, raised to 200℃ at 20℃ / min, then raised to 240℃ at 40℃ / min, and maintained for 5min.

[0087] The conditions for mass spectrometry detection are as follows: the ionization mode is electron bombardment source, the ion source temperature is 200°C, the interface temperature is 240°C, the ionization energy is 70 eV, the solvent delay time is 0.2 min, the scanning mode is full scan, and the characteristic qualitative ions are shown in Table 1.

[0088] In the quantitative detection, the headspace gas chromatography-mass spectrometry method was used to detect the series of reference solution to be tested. The series of reference solution to be tested was headspace injected, passed through a DB-624 chromatographic column, and entered into a mass spectrometer detector for detection after temperature program separation, and a standard working curve with the chromatographic peak area as the ordinate and the concentration as the abscissa was obtained, as shown in Table 2;

[0089] The conditions for gas chromatography detection were as follows: the chromatographic column was a DB-624 column of 30 m × 0.25 mm × 1.40 μm, the carrier gas was helium with a purity of > 99.99%, the flow rate was 45 mL / min, the injection port temperature was 240 °C, the detector temperature was 250 °C, the split injection was performed, the split ratio was 20:1, and the injection volume was 1 μL;

[0090] The programmed temperature conditions were as follows: the initial temperature of the column was 50 °C, maintained for 2 min, then increased to 200 °C at a rate of 20 °C / min, then increased to 240 °C at a rate of 40 °C / min, and maintained for 5 min;

[0091] The conditions for mass spectrometry detection are as follows: the ionization mode is electron bombardment source, the ion source temperature is 200°C, the interface temperature is 240°C, the ionization energy is 70 eV, the solvent delay time is 0.2 min, the scanning mode is full scan, and the characteristic quantitative ions are shown in Table 1.

[0092] Sample preparation: Dissolve 10.3811 g of house cleaning detergent A (specification: 500 mL) in pure water, transfer to a 50 mL volumetric flask, and dilute to the mark. Take 2 mL of the sample solution, add it to a 20 mL headspace bottle, add 0.7 g of sodium chloride, seal and shake well to obtain the sample solution to be tested.

[0093] Qualitative analysis of samples: The sample solution was subjected to headspace gas chromatography-mass spectrometry detection using two chromatographic columns, the non-polar column Rxi-5SilMS column and the neutral column DB-624 column, respectively. Chromatograms of 15 volatile organic solvents of the sample solution on the two chromatographic columns were obtained. The P 样1 and P 标1 Compare and P 样2 and P 标2 After comparison, 1,1-dichloroethylene, carbon tetrachloride and 1,1,2-trichloroethane were not identified, so 1,1-dichloroethylene, carbon tetrachloride and 1,1,2-trichloroethane were not measured; the chromatographic peaks of trichloromethane, 1,1,2,2-tetrachloroethane, 1,1,1,2-tetrachloroethane, 1-chloropentane, tetrachloroethylene, benzene, toluene, ethylbenzene, chlorobenzene, o-xylene, m-xylene and p-xylene were identified.

[0094] Sample quantitative analysis: Record the retention time and chromatographic peak area of ​​chloroform, 1,1,2,2-tetrachloroethane, 1,1,1,2-tetrachloroethane, 1-chloropentane, tetrachloroethylene, benzene, toluene, ethylbenzene, chlorobenzene, o-xylene, m-xylene and p-xylene on the DB-624 chromatographic column, as shown in Table 3.

[0095] Table 3 Retention time and chromatographic peak area of ​​volatile organic solvents

[0096] Compound Retention time Peak area Chloroform 4.428 995 benzene 5.018 84 1-Chloropentane 6.909 253 Toluene 7.268 357 Tetrachloroethylene 7.98 178 chlorobenzene 9.181 275 1,1,1,2-Tetrachloroethane 9.3 364 m / p-xylene 9.501 919 o-Xylene 10.083 343 1,1,2,2-Tetrachloroethane 11.113 272 Ethylbenzene 9.332 484

[0097] Combining the standard working curve equations of the above 12 volatile organic solvents in Table 2, it can be seen that only the peak area of ​​chloroform is within the linear range. The area of ​​the obtained chloroform chromatographic peak is substituted into the standard working curve of chloroform, and the chloroform concentration is calculated to be c (μg / mL) = 0.11; the content of chloroform in the cleaning agent A is calculated according to the concentration of chloroform: X = (c×V) / m = (0.11×50) / 10.3811 = 0.53 mg / kg.

[0098] Example 2

[0099] The difference from Example 1 is:

[0100] Sample preparation: Dissolve 10.0420 g of clothing penetrant B (specification: 300 mL) in pure water, transfer to a 50 mL volumetric flask, and dilute to the mark. Take 2 mL of the sample solution, add it to a 20 mL headspace bottle, add 0.7 g of sodium chloride, seal and shake well to obtain the sample solution to be tested.

[0101] Qualitative analysis of samples: The sample solution was subjected to headspace gas chromatography-mass spectrometry detection using two chromatographic columns, the non-polar column Rxi-5SilMS column and the neutral column DB-624 column, respectively. Chromatograms of 15 volatile organic solvents of the sample solution on the two chromatographic columns were obtained. The P 样1 and P 标1 Compare and P 样2 and P 标2 By comparison, the chromatographic peaks of chloroform, toluene, tetrachloroethylene, m-xylene and p-xylene were identified.

[0102] Sample quantitative analysis: Record the retention time and chromatographic peak area of ​​chloroform, toluene, tetrachloroethylene, m-xylene and p-xylene of the sample solution on the DB-624 chromatographic column, as shown in Table 4.

[0103] Table 4 Retention time and chromatographic peak area of ​​volatile organic solvents

[0104] Compound Retention time Peak area Chloroform 4.428 240 Toluene 7.271 207 Tetrachloroethylene 7.98 118 m / p-xylene 9.506 84

[0105] Combining the standard working curve equations of the above five volatile organic solvents in Table 2, it can be seen that the peak areas of chloroform, toluene, tetrachloroethylene, m-xylene and p-xylene are not within the linear range and cannot be substituted into the standard working curve for calculation. Therefore, the concentrations of chloroform, toluene, tetrachloroethylene, m-xylene and p-xylene were not measured.

[0106] Example 3

[0107] The difference from Example 1 is:

[0108] Sample preparation: Dissolve 10.1680 g of glass cleaner C (specification: 500 mL) in pure water, transfer to a 50 mL volumetric flask, and dilute to the mark. Take 2 mL of the sample solution, add it to a 20 mL headspace bottle, add 0.7 g of sodium chloride, seal and shake well to obtain the sample solution to be tested.

[0109] Qualitative analysis of samples: The sample solution was subjected to headspace gas chromatography-mass spectrometry detection using two chromatographic columns, the non-polar column Rxi-5SilMS column and the neutral column DB-624 column, respectively. Chromatograms of 15 volatile organic solvents of the sample solution on the two chromatographic columns were obtained. The P 样1 and P 标1 Compare and P 样2 and P标2 Comparison was made and the chromatographic peaks of chloroform, toluene, m-xylene and p-xylene were identified.

[0110] Sample quantitative analysis: Record the retention time and chromatographic peak area of ​​chloroform, toluene, m-xylene and p-xylene of the sample solution on the DB-624 chromatographic column, as shown in Table 5.

[0111] Table 5 Retention time and chromatographic peak area of ​​volatile organic solvents

[0112]

[0113]

[0114] Combining the standard working curve equations of the above four volatile organic solvents in Table 2, it can be seen that the peak areas of chloroform, toluene, m-xylene and p-xylene are not within the linear range and cannot be substituted into the standard working curve for calculation. Therefore, the concentrations of chloroform, toluene, m-xylene and p-xylene were not measured.

[0115] Example 4

[0116] The difference from Example 1 is:

[0117] Sample preparation: Dissolve 10.0301 g of multi-purpose cleaner D (specification: 500 mL) in pure water, transfer to a 50 mL volumetric flask, and dilute to the mark. Take 2 mL of the sample solution, add it to a 20 mL headspace bottle, add 0.7 g of sodium chloride, seal and shake well to obtain the sample solution to be tested.

[0118] Qualitative analysis of samples: The sample solution was subjected to headspace gas chromatography-mass spectrometry detection using two chromatographic columns, the non-polar column Rxi-5SilMS column and the neutral column DB-624 column, respectively. Chromatograms of 15 volatile organic solvents of the sample solution on the two chromatographic columns were obtained. The P 样1 and P 标1 Compare and P 样2 and P 标2 By comparison, the chromatographic peaks of 1,1-dichloroethylene, chloroform, toluene, and 1,1,2-trichloroethane were identified.

[0119] Sample quantitative analysis: Record the retention time and chromatographic peak area of ​​1,1-dichloroethylene, chloroform, toluene, and 1,1,2-trichloroethane of the sample solution on the DB-624 chromatographic column, as shown in Table 6.

[0120] Table 6 Retention time and chromatographic peak area of ​​volatile organic solvents

[0121] Compound Retention time Peak area 1,1-Dichloroethylene 2.589 20 Chloroform 4.425 190 Toluene 7.267 154 1,1,2-Trichloroethane 7.9 112

[0122] Combining the standard working curve equations of the above four volatile organic solvents in Table 2, it can be seen that the peak areas of 1,1-dichloroethylene, chloroform, toluene, and 1,1,2-trichloroethane are not within the linear range and cannot be substituted into the standard working curve for calculation. Therefore, the concentrations of 1,1-dichloroethylene, chloroform, toluene, and 1,1,2-trichloroethane were not measured.

[0123] Example 5

[0124] The difference from Example 1 is:

[0125] Sample preparation: Dissolve 10.1516g of strong degreasing agent G (specification: 500mL) in pure water, transfer to a 50mL volumetric flask, and dilute to the mark. Take 2mL of the sample solution, add it to a 20mL headspace bottle, add 0.7g of sodium chloride, seal and shake well to obtain the sample solution to be tested.

[0126] Qualitative analysis of samples: The sample solution was subjected to headspace gas chromatography-mass spectrometry detection using two chromatographic columns, the non-polar column Rxi-5SilMS column and the neutral column DB-624 column, respectively. Chromatograms of 15 volatile organic solvents of the sample solution on the two chromatographic columns were obtained. The P 样1 and P 标1 Compare and P 样2 and P 标2 Comparison was performed and the chromatographic peaks of chloroform, toluene and 1,1,2-trichloroethane were identified.

[0127] Sample quantitative analysis: Record the retention time and chromatographic peak area of ​​chloroform, toluene and 1,1,2-trichloroethane of the sample solution on the DB-624 chromatographic column, as shown in Table 7.

[0128] Table 7 Retention time and chromatographic peak area of ​​volatile organic solvents

[0129] Compound Retention time Peak area Chloroform 4.428 168 Toluene 7.264 105 1,1,2-Trichloroethane 7.79 65

[0130] Combining the standard working curve equations of the above three volatile organic solvents in Table 2, it can be seen that the peak areas of chloroform, toluene and 1,1,2-trichloroethane are not within the linear range and cannot be substituted into the standard working curve for calculation. Therefore, the concentrations of chloroform, toluene and 1,1,2-trichloroethane were not measured.

[0131] The present invention uses two chromatographic columns, a non-polar column Rxi-5SilMS column and a neutral column DB-624 column, for separation and detection, and examines the retention time of 15 volatile organic solvents for qualitative analysis; then the DB-624 column separation and detection results are used for quantitative analysis to obtain the chromatographic peak areas of the 15 volatile organic solvents, which are substituted into the standard working curve equation to obtain the concentrations of the 15 volatile organic solvents, and further calculated to obtain the contents of the 15 volatile organic solvents. The method of the present invention is qualitatively accurate, has high determination efficiency, and can accurately determine the contents of 15 volatile organic solvents. In the present invention, the average recovery rate of 15 volatile organic solvents in household cleaners determined by headspace gas chromatography is 82.8-116%, the relative standard deviation is less than 5%, the detection limit of the method is 0.02-0.14 mg / kg, and the quantitative limit is 0.08-0.50 mg / kg.

[0132] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for determining the content of volatile organic solvents in a cleaning agent by headspace gas chromatography, characterized in that: The following steps are included: 1) mixing a detergent sample and water to obtain a sample solution, and adding the sample solution to a headspace bottle containing sodium chloride to obtain a sample solution to be tested; 2) mixing an alkylbenzene sulfonic acid active substance, a fatty alcohol polyoxyethylene ether, an ethylated alkyl sodium sulfate active substance, triethanolamine, trisodium citrate dihydrate, a preservative and water to obtain a simulated sample; The volatile organic solvent and methanol are mixed to obtain a mixed reference substance stock solution; The mixed reference substance stock solution is dripped into the simulated sample to obtain a series of reference substance solutions; Adding the series of reference substance solutions into the headspace bottle containing sodium chloride to obtain the series of reference substance solutions to be tested; 3) Using headspace gas chromatography-mass spectrometry to detect the sample solution and the series of reference solution to be tested, the sample solution and the series of reference solution to be tested are injected by headspace method, respectively passed through Rxi-5SilMS chromatographic column and DB-624 chromatographic column, and then enter into mass spectrometry detector for detection after programmed temperature separation, and characteristic chromatograms of the sample solution and the series of reference solution to be tested on the two chromatographic columns are obtained, and the volatile organic solvent in the sample solution to be tested is qualitatively determined according to the chromatographic peaks; 4) Using headspace gas chromatography-mass spectrometry to detect the series of reference solution to be tested, the series of reference solution to be tested is sampled in the headspace, passed through a DB-624 chromatographic column, separated by programmed temperature, and then entered into a mass spectrometer for detection, to obtain a standard working curve with the chromatographic peak area as the ordinate and the concentration as the abscissa; Substituting the area of ​​the chromatographic peak that is qualitatively determined to contain a certain volatile organic solvent in step 3) into the standard working curve to obtain the concentration of the volatile organic solvent, and calculating the content of the volatile organic solvent in the detergent sample; when it is qualitatively determined to contain multiple volatile organic solvents, repeat the above operation to calculate the content of each volatile organic solvent respectively; There are 15 kinds of volatile organic solvents, including chloroform, carbon tetrachloride, 1,1,2-trichloroethane, 1,1,2,2-tetrachloroethane, 1,1,1,2-tetrachloroethane, 1-chloropentane, 1,1-dichloroethylene, tetrachloroethylene, benzene, toluene, ethylbenzene, chlorobenzene, o-xylene, m-xylene and p-xylene.

2. The method according to claim 1, characterized in that In the headspace bottle of step 1), the volume of the sample solution is 2-3 mL, and the mass of sodium chloride is 0.5-0.7 g; in the headspace bottle of step 2), the volume of the series of reference solutions is 2-3 mL, and the mass of sodium chloride is 0.5-0.7 g.

3. The method according to claim 1 or 2, characterized in that: In step 2), the simulated sample has an alkylbenzene sulfonic acid active substance content of 7-9%, a fatty alcohol polyoxyethylene ether content of 3-5%, an ethylated alkyl sodium sulfate active substance content of 1.5-2.5%, a triethanolamine content of 0.3-0.8%, a trisodium citrate dihydrate content of 0.4-0.8%, and a preservative content of 0.08-0.12%; and a pH value of the simulated sample of 8.5-9.

0.

4. The method according to claim 1, characterized in that In the mixed reference stock solution, the mass content of each organic solvent is 10 mg / mL; in the series of reference solutions, the concentration of each volatile organic solvent is independently 10 μg / mL, 20 μg / mL, 50 μg / mL, 100 μg / mL, and 500 μg / mL.

5. The method according to claim 1 or 4, characterized in that: The chromatogram of the sample solution on the Rxi-5Sil MS column is P 样1 The chromatogram of the sample solution on the DB-624 column is P 样2 The chromatogram of the reference solution to be tested on the Rxi-5SilMS column is P 标1 The chromatogram of the reference solution to be tested on the DB-624 column is P 标2 ; P 样1 and P 标1 For comparison, when P 样1 and P 标1 When chromatographic peaks with similar retention times appear in the 样2 and P 标2 For comparison, if P 样2 and P 标2 There is also a chromatographic peak with a close retention time in P 标1 and P 标2 If the same volatile organic solvent is found in the sample, it is determined that the sample solution contains the above volatile organic solvent.

6. The method according to claim 1, characterized in that The headspace conditions were as follows: equilibrium temperature 75-85°C, equilibrium time 25-35 min, quantitative loop temperature 95-105°C, and transfer line temperature 105-115°C.

7. The method according to claim 6, characterized in that The conditions for chromatographic detection are as follows: Rxi-5Sil MS chromatographic column specifications are 30m×0.25mm×0.25μm, carrier gas is helium with a purity of >99.99%, flow rate is 35-50mL / min, injection port temperature is 230-250°C, detector temperature is 240-260°C, injection mode is split injection, split ratio is 20:1, injection volume is 1μL, initial column temperature is 35-45°C, maintained for 4-6min, heated to 170°C at a rate of 10°C / min, and then heated to 240°C at a rate of 40°C / min, and maintained for 5-7min; The specifications of the DB-624 chromatographic column are 30m×0.25mm×1.40μm, the carrier gas is helium with a purity of >99.99%, the flow rate is 35-50mL / min, the injection port temperature is 230-250℃, the detector temperature is 240-260℃, the split injection, the split ratio is 20:1, the injection volume is 1μL, the initial temperature of the chromatographic column is 50℃, maintained for 2-3min, heated to 200℃ at a rate of 20℃ / min, and then heated to 240℃ at a rate of 40℃ / min, and maintained for 5-7min.

8. The method according to claim 6 or 7, characterized in that: The conditions for mass spectrometry detection were as follows: the ionization mode was electron bombardment source, the ion source temperature was 200°C, the interface temperature was 240°C, the ionization energy was 70 eV, the solvent delay time was 0.2 min, and the scanning mode was full scan.

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