CN117949551A - Method for measuring content of organic fluoride in oilfield chemical - Google Patents

Abstract

The invention relates to a method for measuring the content of organic fluoride in oilfield chemical agents, which comprises the following steps: carrying out ultrasonic auxiliary extraction treatment on the oilfield chemical reagent sample to obtain a sample to be detected; detecting a sample to be detected by adopting an ultrahigh pressure liquid chromatography-tandem mass spectrometer; preparing mixed standard solutions with different mass concentrations, and drawing a standard curve according to peak areas corresponding to the mixed standard solutions with different mass concentrations; carrying out qualitative monitoring analysis on the sample to be detected in an ion extraction mode, and carrying out quantitative analysis on the sample to be detected by an external standard method to obtain the chromatographic peak area of the sample to be detected; and calculating the content of the organic fluoride in the sample to be measured. The method provided by the invention has the advantages of simple and efficient pretreatment, high sensitivity, high analysis speed, good precision and repeatability, unifies pretreatment flows, establishes a method for simultaneously determining key management and control pollutants in oilfield chemicals, and provides a high-efficiency and reliable basis for quality control and environmental risk management and control of oilfield chemicals.

Description

Method for measuring content of organic fluoride in oilfield chemical

Technical Field

The invention belongs to the technical field of safety and environmental protection of oilfield chemicals, and particularly relates to a method for measuring the content of organic fluoride in oilfield chemicals.

Background

Organic fluorine compounds are an important class of organic compounds in industrial production, and are widely used in various industrial fields due to their unique physicochemical properties. As fluorine is the element with the largest electronegativity, the polyfluoro organic compound has the characteristics of chemical stability, surface activity, excellent temperature resistance and the like. The fluorine surfactant has very excellent performance due to the special property of fluorine atoms, is widely applied as an oilfield chemical agent, and has wide application in the fields of cleanup additives, foaming agents, oil-driving additives and the like. At the same time, environmental concerns with fluoride are becoming more and more of an issue. The superior performance of fluorochemical agents results from fluorocarbon bonds having a high degree of thermal and chemical stability within the molecule, however, this high stability also imparts the typical characteristics of Persistent Organic Pollutants (POPs). In order to eliminate and reduce persistent organic pollutants, international social endorsements have been limited by the "Stockholm convention on persistent organic pollutants" on 9 substances including perfluorooctyl sulfonic acid and its salts and perfluorooctyl sulfonyl fluoride. The China also puts perfluorooctyl sulfonic acid and its salts, perfluorooctyl sulfonyl fluoride, perfluorooctanoic acid (PFOA) and its salts and related compounds into a key management and control new pollutant list, so that the production and use of related fluorides are reduced to the maximum extent, and great influence on human health and environment is reduced. Therefore, detection of perfluorooctyl sulfonic acid and salts thereof, perfluorooctyl sulfonyl fluoride, perfluorooctanoic acid (PFOA) and salts thereof and related compounds is of great importance for development of oilfield chemical safety and environmental protection technologies.

The detection method of the organic fluorine-containing compound in the oilfield chemical agent is less in research at present, and the detection of the organic fluorine-containing compound in the oilfield chemical agent is related to the detection standards of chemical products such as food, paint and the like, and has the following problems in specific detection practice: ① The oilfield chemical agents are various in types, complex in components, non-uniform in pretreatment methods and detection concentrations of the oilfield chemical agents of different types, large in influence on detection results, poor in comparability, complex in flow and long in time consumption; ② The existing detection standard is only aimed at single type of fluorine-containing compound component, the detection efficiency is low, and the standard of the integrated detection method for different types of fluorine-containing compound components still belongs to the blank.

Disclosure of Invention

In view of the above problems, the method for determining the content of organic fluoride in oilfield chemicals comprises the following steps:

carrying out ultrasonic auxiliary extraction treatment on the oilfield chemical reagent sample to obtain a sample to be detected;

detecting a sample to be detected by adopting an ultrahigh pressure liquid chromatography-tandem mass spectrometer;

Preparing mixed standard solutions with different mass concentrations, and drawing a standard curve according to peak areas corresponding to the mixed standard solutions with different mass concentrations;

Carrying out qualitative monitoring analysis on the sample to be detected in an ion extraction mode, and carrying out quantitative analysis on the sample to be detected by an external standard method to obtain the chromatographic peak area of the sample to be detected;

and calculating the content of the organic fluoride in the sample to be measured.

The further preferable technical scheme is as follows:

the drawing method of the standard curve comprises the following steps:

taking perfluorooctanoic acid and perfluorooctyl sulfonic acid to prepare a series of mixed standard solutions with different mass concentrations;

mixing standards for different mass concentrations by adopting ultra-high pressure liquid chromatography tandem mass spectrometer

Measuring the solution to obtain chromatographic peak areas Y corresponding to the mixed standard solution with each mass concentration;

Linearly returning the chromatographic peak area Y and the mass concentration X of the corresponding mixed standard solution

Returning to obtain a corresponding regression equation;

The chromatographic peak area Y is taken as an ordinate, the mass concentration X of the mixed standard solution is taken as an abscissa,

And drawing a standard working curve.

The further preferable technical scheme is as follows: the calculation formula of the method for calculating the content of the organic fluoride in the sample to be measured is as follows:

wherein omega is the mass fraction of perfluorooctanoic acid or perfluorooctane sulfonate in the sample, and the mass fraction is expressed in percentage;

c is the mass concentration of perfluoro caprylic acid or perfluoro octane sulfonic acid calculated by a standard curve, and the unit is micrograms per milliliter;

V is total volume after test treatment, and the unit is milliliter;

m is the mass of the sample in grams.

The further preferable technical scheme is as follows: the purity of the perfluorooctanoic acid and the perfluorooctyl sulfonic acid is 96-100% in terms of mass fraction.

The further preferable technical scheme is as follows: the oilfield chemical samples include water-soluble oilfield chemicals Yang Pin, oil-soluble oilfield chemical samples, and poorly-soluble oilfield chemical samples;

extracting and treating a water-soluble oil field chemical agent sample: accurately weighing 1-2 g of chemical agent, adding water, diluting with ultrasound, then fixing the volume to a fixed volume with acetonitrile, and passing through a microporous filter membrane to obtain a sample to be detected;

Extracting and treating oil-soluble oilfield chemical agents: accurately weighing 1-2 g of chemical agent, adding 10-20 mL of n-hexane for ultrasonic dissolution uniformly, extracting for 1-2 times by using acetonitrile, wherein the dosage of acetonitrile is 10-20 mL each time; combining the acetonitrile phases and fixing the volume to a fixed volume by acetonitrile; after passing through the microporous filter membrane, obtaining a sample to be detected;

extracting and treating the indissoluble oilfield chemical agent: crushing the solid sample into powder, accurately weighing 1-2 g of chemical agent, adding 10-20 mL of acetonitrile, performing ultrasonic extraction for 5-15 min, repeating for 1-2 times, combining acetonitrile phases, and using acetonitrile to fix volume; and (5) passing through a microporous filter membrane to obtain a sample to be tested.

The further preferable technical scheme is as follows: the organic fluoride comprises one or a combination of several of the following: perfluorooctyl sulfonic acid and salts thereof, perfluorooctanoic acid and salts thereof.

The further preferable technical scheme is as follows: the monitoring ions of the extracted ion mode comprise 413m/z and 369m/z, 499m/z and 399m/z, and for perfluorooctanoic acid and salts thereof, the monitoring ions comprise 413m/z and 369m/z, wherein the ion 369m/z is taken as quantitative ion; for perfluorooctyl sulfonic acid and its salts, the monitor ions included 469m/z, 499m/z, and 399m/z, with 499m/z as the quantifying ion.

The further preferable technical scheme is as follows: detecting the sample to be tested further comprises chromatographic conditions:

chromatographic column: c18,2.1 mm. Times.150 mm,1.9 μm;

column temperature: 25 ℃;

mobile phase: acetonitrile, 5mmol/L ammonium acetate solution, wherein the volume percentage content of acetonitrile is 40%;

sample injection amount: 5. Mu.L;

Flow rate: 0.1mL/min.

The further preferable technical scheme is as follows: detecting the sample to be detected further comprises mass spectrometry conditions:

Ionization mode: anion scanning, wherein the scanning range is 200-600;

Mass spectrometry parameters: capillary voltage 2.5KV, gas and sheath temperature 350 ℃, drying gas flow rate 8L/min and atomization pressure 35psi;

ion source: an electrospray ion source.

The further preferable technical scheme is as follows: the concentration range of the mixed standard solution is as follows: 1. Mu.g/mL-0.002. Mu.g/mL.

The invention has the beneficial effects that:

The invention comprehensively considers pretreatment methods of different types of oilfield chemicals, introduces an ultrasonic extraction method, unifies pretreatment flows, adopts an ultra-high pressure liquid chromatography-tandem mass spectrometry at the same time, establishes a method for simultaneously measuring the contents of key management pollutants of perfluorooctanoic acid and salts thereof, perfluorooctylsulfonic acid and salts thereof organic fluorides in the oilfield chemicals, and provides a high-efficiency and reliable basis for quality control and environmental risk management of the oilfield chemicals.

Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions of the prior art, the following description will briefly explain the drawings used in the embodiments or the description of the prior art, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 shows liquid chromatography-tandem mass spectrometry chromatograms of perfluorooctanoic acid and perfluorooctylsulfonic acid standards;

Fig. 2 shows a liquid chromatography-tandem mass spectrometry chromatogram of perfluoro octanoic acid standard selection ion (m/z=369);

Fig. 3 shows a liquid chromatography-tandem mass spectrometry chromatogram of perfluorooctyl sulfonic acid standard selection ion (m/z=499).

FIG. 4 shows the total mass spectrum of liquid chromatography-tandem mass spectrometry of perfluorooctanoic acid and perfluorooctylsulfonic acid standard substances;

FIG. 5 shows a perfluorooctanoic acid mass spectrum;

fig. 6 shows a mass spectrum of perfluorooctyl sulfonic acid.

Detailed Description

For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments of the present invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

Example 1: perfluoro caprylic acid and salts thereof, perfluoro octyl sulfonic acid and salts thereof integrated detection method

1. The apparatus and reagents used in the method:

The instrument used: ultra-high pressure liquid chromatography-time-of-flight mass spectrometer, agilent G6500 series, USA; reversed phase C18 column (1.9 μm, 2.1X1150 mm), agilent company, USA.

Reagent: acetonitrile, chromatographic purity, beijing meruida technologies limited; the purity of the perfluorooctanoic acid and the perfluorooctylsulfonic acid is not less than 96% in terms of mass fraction, and the purity of the perfluorooctylsulfonic acid and the perfluorooctylsulfonic acid is Aba Ding Gongsi.

The high-purity perfluorooctanoic acid and perfluorooctyl sulfonic acid are used as standard solution preparation raw materials, so that a more remarkable chromatographic-mass spectrometry analysis effect can be brought, and a tester can be helped to more obviously observe whether the perfluorooctanoic acid and salts thereof, and the perfluorooctyl sulfonic acid and salts thereof appear in a sample to be tested.

2. Preparing a standard solution: precisely weighing two standard reference substances (with error of 1 mg) and respectively placing into a 100mL volumetric flask, dissolving with acetonitrile, and fixing volume to scale; accurately transferring the solution into a volumetric flask with 2.0mL to 100mL, and fixing the volume of acetonitrile to obtain the mixed standard solution with the concentration of 2 mug/mL. The mixture was gradually diluted with acetonitrile to give mixed standard working solutions having concentrations of 1. Mu.g/mL, 0.2. Mu.g/mL, 0.1. Mu.g/mL, 0.05. Mu.g/mL, 0.02. Mu.g/mL, 0.01. Mu.g/mL, 0.005. Mu.g/mL, and 0.002. Mu.g/mL, respectively.

3. Chromatographic-mass spectrometry analysis condition optimization: in the mobile phase, the aqueous phase is a 5mmol/L ammonium acetate solution, the organic phase is pure acetonitrile, the elution gradient is acetonitrile and ammonium acetate according to 40:60, the column temperature is 25 ℃, the flow rate is 0.1mL/min, and the sample injection volume is 5 mu L; the gas temperature in the mass spectrum parameter is 350 ℃, the drying gas flow rate is 8L/min, the atomization gas pressure is 35psi, the scanning range is 200-600 Dr, and the detection mode is a negative ion mode.

As shown in figure 1, the peak value at the position 5.6/9.0 of the standard solution mass liquid chromatography-tandem mass spectrometry chromatogram obtained by preparing perfluorooctanoic acid and perfluorooctyl sulfonic acid is obvious, and the observation is simple and clear. While there was an impurity peak at 8.0/8.5, the samples selected in this example were perfluorooctanoic acid, which were from Allatin corporation with a purity of 95% or more, and perfluorooctanoic acid, which had the same molecular weight as perfluorooctanoic acid at 9.0 minutes, but different octyl structures, and possibly branched structures. In order to avoid the influence of branched structure, the marker peak is selected and tracked during quantitative analysis, and the concentration of the sample of the prepared standard solution is more than 95%, so that the measurement is not influenced.

The total mass spectra of perfluorooctanoic acid and perfluorooctyl sulfonic acid are shown in fig. 4, and it can be seen that perfluorooctyl sulfonate (molecular weight 499) is more ionized and signals are stronger than perfluorooctanoic acid (molecular weight 369, 413), so that 499 signals are stronger and 369, 413 signals are weaker in the total spectra. And by combining the chromatograms, more remarkable detection results can be obtained.

4. Drawing a quantitative working curve: and sequentially detecting the mixed standard working solution from thin to thick according to the mass concentration, taking the chromatographic peak area Y of the quantitative ions corresponding to the target object detected by the standard solution as an ordinate, and taking the mass concentration X of the mixed standard solution as an abscissa to draw a standard working curve. Wherein, for perfluorooctanoic acid, ion m/z=369 is taken as quantitative ion; for perfluorooctanesulfonic acid, the ion m/z=499 is used as a quantitative ion.

As shown in fig. 2, the perfluorooctanoic acid was measured with m/z=369 as a quantitative ion, and a more remarkable test effect was obtained. When the quantitative ion is m/z=369, the peak value of the perfluorooctanoate ion is obvious, and no interference data exists. The perfluoro octoic acid and its salts exist in the state of perfluoro octoate ion in the standard solution prepared by the method provided by the invention. As shown in fig. 5, the molecular weight of perfluorooctanoic acid is 414, 1H is removed, m/z=413, a signal is visible in 413 in the spectrum, and quantitative analysis can be performed according to the ion, but the signal of the ion is weaker than that of m/z=369, and the quantitative sensitivity is not as good as that of m/z=369, so quantitative analysis is performed according to m/z=369. m/z=369 corresponds to removal of carboxyl groups from perfluorooctanoic acid, and in combination with fig. 2, it can be seen that the quantitative test effect on perfluorooctanoic acid radical ion is excellent when the quantitative ion is m/z=369.

As shown in fig. 3, the perfluorooctane sulfonate was measured with m/z=499 as a quantitative ion, and a more remarkable test effect was obtained. When the quantitative ion is m/z=499, the perfluorooctane sulfonate has obvious peak value, no interference data and simpler and more convenient observation. In the standard solution prepared by the method provided by the invention, the perfluorooctane sulfonate and salts thereof exist in a perfluorooctane sulfonate ion state, and an impurity peak is found at 8/8.5.

The perfluorooctyl sulfonic acid mass spectrum is shown in fig. 6, and the molecular ion peak m/z=499 shows only one peak in the mass spectrum, so that it is known from fig. 3 that the impurity peak at 8/8.5 in fig. 3 is perfluorooctyl sulfonic acid isomer, and not impurity. Similarly, the impurity peaks in FIG. 1 are also perfluorooctyl sulfonic acid isomers. Therefore, the quantitative test effect on perfluorooctane sulfonate ion was excellent when the quantitative ion was m/z=499.

From this, it can be seen that a more accurate detection result can be obtained by testing mass spectrum in series with chromatography.

Example 2: detection of organic fluoride content in oilfield chemicals

Sample 1: 1g (accurate to 1 mg) of the water-soluble oilfield chemical sample is accurately weighed, diluted with a small amount of water by ultrasonic, fixed to 25mL with acetonitrile, filtered through a 0.45 μm microporous filter membrane, and detected, qualitatively and quantitatively analyzed as described in example 1.

Qualitative analysis: determining a sample to-be-detected liquid and a standard working solution according to the determined analysis conditions, and judging that the perfluorooctanoic acid exists in the sample if the retention time of a target chromatographic peak in the sample is consistent with that of the standard working solution of the perfluorooctanoic acid (the variation range is +/-2.5 percent) and the mass-to-charge ratio of the target compound in the sample comprises 413 and 369; if the target chromatographic peak retention time in the sample is consistent with the standard working solution chromatographic peak of perfluorooctane sulfonate (varying between + -2.5%) and the mass-to-charge ratio of the target compound in the sample comprises 499, 449 and 399, then the presence of perfluorooctane sulfonate in the sample can be determined.

Quantitative analysis: and respectively bringing peak areas of target ions 369m/z and 499m/z in the sample to be detected into corresponding quantitative working curves to obtain the fluoride mass concentration, and obtaining the fluoride mass fraction in the sample according to the following formula.

The calculation formula of the mass fraction of fluoride in the sample to be measured is as follows:

wherein the mass fraction of perfluorooctanoic acid or perfluorooctane sulfonate in the omega-sample is expressed as a percentage (%);

c-mass concentration of perfluorooctanoic acid or perfluorooctane sulfonate calculated by a standard curve, wherein the unit is micrograms per milliliter (mg/L);

V-total volume after test treatment in milliliters (mL);

m-mass of sample in grams (g).

The content of perfluorooctanoic acid and its salts, perfluorooctylsulfonic acid and its salts in the sample was calculated, and the results are shown in Table 1.

Sample 2: accurately weighing 1g (accurate to 1 mg) of an oil-soluble oilfield chemical sample, adding 20mL of n-hexane for ultrasonic dissolution uniformly, extracting for 2 times with acetonitrile, wherein the dosage of acetonitrile is 10mL each time; the acetonitrile phases were combined and fixed to 25mL with acetonitrile, and after passing through the microporous filter membrane, the detection was performed as described in example 1, and the perfluorooctanoic acid and its salts, perfluorooctylsulfonic acid and its salts content in the sample were calculated as described in sample 1, and the results are shown in table 1.

Sample 3: the slightly soluble oilfield chemical sample was crushed to powder, 1g (accurate to 1 mg) of the sample was accurately weighed, 10mL of acetonitrile was added to carry out ultrasonic extraction for 10min, the process was repeated 2 times, the acetonitrile phases were combined and the acetonitrile was used to fix the volume to 25mL, after passing through the microporous filter membrane, the test was carried out according to the method described in example 1, and the perfluorooctanoic acid and its salts, perfluorooctylsulfonic acid and its salts contents in the sample were calculated according to the method described in sample 1, and the results are shown in table 1.

Table 1: detection result of organic fluorine-containing compound in oilfield chemical

The mass fraction of perfluorooctanoic acid or perfluorooctane sulfonic acid in the omega-sample is expressed as a percentage (%);

c-mass concentration of perfluorooctanoic acid or perfluorooctane sulfonic acid calculated by standard curve, the unit is micrograms per milliliter (mug/mL);

V-total volume after test treatment in milliliters (mL);

m-mass of sample in grams (g).

The pretreatment method of the oil field chemical agents of different types is comprehensively considered, an ultrasonic extraction method is introduced, the pretreatment flow is unified, and perfluoro caprylic acid and salts thereof, perfluoro octyl sulfonic acid and organic fluorides of the salts thereof, which are important control pollutants in water-soluble oil field chemical agent samples, oil-soluble oil field chemical agent samples and insoluble oil field chemical agent samples, are extracted into ionic states, so that the follow-up detection is facilitated.

And measuring perfluorooctanoic acid and its salts using ion m/z=369 as a quantitative ion; for perfluorooctanesulfonic acid and salts thereof, the ion m/z=499 is used as a quantitative ion, and different quantitative ions are utilized to obtain more obvious observation effects, so that whether perfluorooctanoic acid and salts thereof, perfluorooctylsulfonic acid and salts thereof are contained in a sample to be detected can be accurately judged. And by adopting an ultrahigh pressure liquid chromatography-tandem mass spectrometry, the perfluorooctanoic acid and salts thereof, perfluorooctyl sulfonic acid and salts thereof content of a plurality of oilfield chemical samples in different states can be measured at one time, and the wide popularization is facilitated.

Example 3: methodological verification

And (5) performing standard recovery rate and precision measurement by adopting an oilfield chemical negative sample. To the negative samples, perfluorooctanoic acid and perfluorooctylsulfonic acid of different masses were added, respectively, and each group of samples was averaged 3 times in parallel by the method described in example 1, and the recovery rate and precision data are shown in Table 2. In the addition range, the test deviation is within 3%, and the result shows that the method has better precision and accuracy.

Table 2: marking detection result of perfluoro caprylic acid and perfluoro octyl sulfonic acid

As can be seen from the above table, the relative standard deviation of the perfluorooctanoic acid and the perfluorooctyl sulfonic acid detected by the method provided by the invention is within 3%, so that the method provided by the invention has good precision and accuracy.

Compared with the prior art, the invention has the following advantages:

The method provided by the invention has the advantages of simple and efficient pretreatment, high sensitivity, high analysis speed, high precision and good repeatability. Considering pretreatment methods of different types of oilfield chemicals, introducing an ultrasonic extraction method, unifying pretreatment flows, and simultaneously adopting an ultrahigh pressure liquid chromatography-tandem mass spectrometry to establish a method for simultaneously measuring and controlling the contents of the key management pollutants perfluorooctanoic acid and salts thereof, perfluorooctylsulfonic acid and salts thereof and organofluorides in the oilfield chemicals, and providing a high-efficiency and reliable basis for quality control and environmental risk management of the oilfield chemicals.

According to the experimental conditions determined by the determination method, when the mass fraction of the additive is 0.0005% -0.01%, the relative standard deviation is not higher than 5%. The relative standard deviation of the test results of different laboratories on different level samples is not higher than 5%. The method solves the problems of poor integration, high labor intensity, low analysis efficiency and the like of the existing reference standard method, and extracts key management pollutants of perfluorooctanoic acid and salts thereof, perfluorooctyl sulfonic acid and salts thereof in water-soluble oilfield chemical agent samples, oil-soluble oilfield chemical agent samples and insoluble oilfield chemical agent samples into ionic states by utilizing different treatment methods, thereby facilitating subsequent detection, filling the blank of detection of key management pollutants of perfluorooctanoic acid and salts thereof, perfluorooctyl sulfonic acid and salts thereof in oilfield chemical agents, and having important significance for quality and environmental risk management of oilfield chemical agents.

Although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims (10)

1. A method for determining the level of organofluoride in an oilfield chemical comprising the steps of:

carrying out ultrasonic auxiliary extraction treatment on the oilfield chemical reagent sample to obtain a sample to be detected;

detecting a sample to be detected by adopting an ultrahigh pressure liquid chromatography-tandem mass spectrometer;

Preparing mixed standard solutions with different mass concentrations, and drawing a standard curve according to peak areas corresponding to the mixed standard solutions with different mass concentrations;

Carrying out qualitative monitoring analysis on the sample to be detected in an ion extraction mode, and carrying out quantitative analysis on the sample to be detected by an external standard method to obtain the chromatographic peak area of the sample to be detected;

and calculating the content of the organic fluoride in the sample to be measured.

2. The method for determining the content of organic fluoride in oilfield chemicals according to claim 1, wherein a mixed standard solution with different mass concentrations is prepared, and a standard curve is drawn according to peak areas corresponding to the mixed standard solution with different mass concentrations, comprising the following steps:

Taking perfluorooctanoic acid and perfluorooctyl sulfonic acid to prepare mixed standard solutions with different mass concentrations;

The method comprises the steps of respectively measuring mixed standard solutions with different mass concentrations by adopting an ultrahigh-pressure liquid chromatography-tandem mass spectrometer to obtain a chromatographic peak area Y corresponding to the mixed standard solutions with the mass concentrations;

linearly regressing the chromatographic peak area Y and the mass concentration X of the corresponding mixed standard solution to obtain a corresponding regression equation;

And drawing a standard working curve by taking the chromatographic peak area Y as an ordinate and the mass concentration X of the mixed standard solution as an abscissa.

3. The method for determining the content of organic fluoride in oilfield chemicals of claim 2, wherein the calculation formula for calculating the content of organic fluoride in the sample to be measured is:

wherein omega is the mass fraction of perfluorooctanoic acid or perfluorooctane sulfonate in the sample, and the mass fraction is expressed in percentage;

c is the mass concentration of perfluoro caprylic acid or perfluoro octane sulfonic acid calculated by a standard curve, and the unit is micrograms per milliliter;

V is total volume after test treatment, and the unit is milliliter;

m is the mass of the sample in grams.

4. A method of determining the level of organofluoro compounds in an oilfield chemical according to claim 3, wherein the perfluorooctanoic acid and perfluorooctylsulfonic acid are 96% to 100% pure by mass fraction.

5. The method of determining the level of organofluoride in an oilfield chemical of claim 4, wherein the oilfield chemical sample comprises a water-soluble oilfield chemical sample, an oil-soluble oilfield chemical sample, and a poorly soluble oilfield chemical sample;

extracting and treating a water-soluble oil field chemical agent sample: accurately weighing 1-2 g of chemical agent, adding water, diluting with ultrasound, then fixing the volume to a fixed volume with acetonitrile, and passing through a microporous filter membrane to obtain a sample to be detected;

Extracting and treating oil-soluble oilfield chemical agents: accurately weighing 1-2 g of chemical agent, adding 10-20 mL of n-hexane for ultrasonic dissolution uniformly, extracting for 1-2 times by using acetonitrile, wherein the dosage of acetonitrile is 10-20 mL each time; combining the acetonitrile phases and fixing the volume to a fixed volume by acetonitrile; after passing through the microporous filter membrane, obtaining a sample to be detected;

extracting and treating the indissoluble oilfield chemical agent: crushing the solid sample into powder, accurately weighing 1-2 g of chemical agent, adding 10-20 mL of acetonitrile, performing ultrasonic extraction for 5-15 min, repeating for 1-2 times, combining acetonitrile phases, and using acetonitrile to fix volume; and (5) passing through a microporous filter membrane to obtain a sample to be tested.

6. A method of determining the level of organofluoride in oilfield chemicals of any one of claims 1-5, wherein the organofluoride comprises one or a combination of the following: perfluorooctyl sulfonic acid and salts thereof, perfluorooctanoic acid and salts thereof.

7. The method of determining the organofluoride content of an oilfield chemical of claim 6, wherein the extracted ion mode of monitoring ions comprises 413m/z and 369m/z, 499m/z and 399m/.

8. The method of determining the level of organofluoride in oilfield chemicals of claim 7, wherein detecting the sample to be tested comprises chromatographic conditions:

chromatographic column: c18,2.1 mm. Times.150 mm,1.9 μm;

column temperature: 25 ℃;

mobile phase: acetonitrile, 5mmol/L ammonium acetate solution, wherein the volume percentage content of acetonitrile is 40%;

sample injection amount: 5. Mu.L;

Flow rate: 0.1mL/min.

9. The method of claim 8, wherein detecting the sample further comprises mass spectrometry conditions:

Ionization mode: anion scanning, wherein the scanning range is 200-600;

Mass spectrometry parameters: capillary voltage 2.5KV, gas and sheath temperature 350 ℃, drying gas flow rate 8L/min and atomization pressure 35psi;

ion source: an electrospray ion source.

10. The method of determining the level of organofluoride in oilfield chemicals of claim 9, wherein the mixed standard solution is at a concentration ranging from: 1. Mu.g/mL-0.002. Mu.g/mL.