Method for rapidly determining iron content in dichloroethane and application

Abstract

The invention discloses a method for rapidly determining the content of iron in dichloroethane and application. The method comprises the following steps: uniformly mixing an extraction agent with a dichloroethane solution to be detected, carrying out an extraction reaction, and taking a supernatant to obtain a sample solution to be detected, the extraction agent having an extraction effect on ferrous ions and ferric ions; preparing an iron standard solution, determining the content of the iron element by adopting inductively coupled plasma atomic emission spectrometry, and drawing a standard curve; and determining the concentration of the iron element in the to-be-detected sample solution by adopting an inductively coupled plasma atomic emission spectrometry, and calculating the iron content in the to-be-detected dichloroethane solution by combining the standard curve. The method can accurately determine the iron content in the dichloroethane sample, has the characteristics of high efficiency, simplicity and convenience, omits the tedious sample pretreatment step, saves the time and experiment cost, reduces the drug use cost and the generation of waste liquid, and greatly improves the analysis efficiency.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical analysis, and particularly relates to a method for quickly determining the iron content in dichloroethane and an application thereof. Background Art

[0002] In the ethylene-based production of ethylene dichloride, iron content is a critical indicator, directly reflecting the health of the production process. In actual production, precise iron content data often requires timely adjustment of process parameters to ensure that ethylene dichloride products meet quality standards.

[0003] Currently, the most common method for determining the iron content in ethylene dichloride is the visible spectrophotometric method specified in the Q / QHX 001-2021 standard. However, this method has some significant limitations. During the sample processing stage, Fe 3+ Converted to Fe 2 + This process involves multiple complex steps, which is not only tedious but also time-consuming. Furthermore, due to the numerous steps, the probability of introducing human error is high. Furthermore, the use of multiple chemicals during the treatment process not only increases experimental costs but also generates a large amount of waste liquid, which puts a certain pressure on the environment.

[0004] Therefore, how to provide an analytical determination method that is simpler, more efficient, more stable, and has a smaller error range of the measurement results compared to spectrophotometry is an urgent problem to be solved. Summary of the Invention

[0005] The main purpose of the present invention is to provide a method for quickly determining the iron content in ethylene dichloride and its application, so as to overcome the shortcomings of the prior art.

[0006] To achieve the aforementioned object of the invention, the technical solutions adopted by the present invention include:

[0007] One aspect of the present invention provides a method for rapidly determining the iron content in ethylene dichloride, comprising:

[0008] The extractant is mixed evenly with the dichloroethane solution to be tested, and an extraction reaction is carried out. The upper layer liquid is taken to obtain the sample liquid to be tested. The extractant has an extraction effect on both divalent iron ions and trivalent iron ions;

[0009] Prepare iron standard solution, determine the iron content by inductively coupled plasma atomic emission spectrometry, and draw a standard curve;

[0010] The concentration of the iron element in the sample solution to be tested is determined by inductively coupled plasma atomic emission spectrometry, and the iron content in the dichloroethane solution to be tested is calculated based on the standard curve.

[0011] Another aspect of the present invention also provides application of the method in the field of preparing ethylene dichloride.

[0012] Compared with the prior art, the present invention has at least the following beneficial effects:

[0013] 1) High analysis efficiency: The present invention can not only accurately determine the iron content in dichloroethane samples, but also has the characteristics of high efficiency and simplicity; compared with the traditional spectrophotometric method, the present invention saves the tedious process of Fe 3+ Converted to Fe 2+ The sample pretreatment step is simplified, which greatly shortens the analysis time and improves the analysis efficiency.

[0014] 2) High accuracy of the test results: The present invention has been optimized in terms of experimental stability. By reasonably adjusting the experimental conditions, such as the concentration, dosage, shaking time of the extractant and the working parameters of the instrument, the stability and reliability of the data are ensured. 3+ 、Fe 2+ ), the spectral intensity of iron is determined by the standard curve method, which can effectively eliminate interference and achieve the accuracy of the test results.

[0015] 3) Reduced drug costs and waste generation: The present invention utilizes inductively coupled plasma optical emission spectrometry (ICP-AES) for specific sample analysis, simplifying the process. Compared to traditional spectrophotometry, it eliminates the need for five reagents and, consequently, significantly reduces waste generation. In today's increasingly stringent environmental regulations, this not only reduces experimental costs but also minimizes environmental pollution. DETAILED DESCRIPTION

[0016] In view of the problems existing in the above-mentioned prior art, the inventors of the present invention have conducted extensive and in-depth research and have provided a method and application for rapidly determining the iron content in dichloroethane. The method mainly uses an inductively coupled plasma atomic emission spectrometer to ionize and heat the sample to form a plasma, which collides with high-energy electrons to generate excited states of elements and excited ion states, and emit specific element excitation spectral lines; then, optical elements are used to collect spectral information, which is converted into electrical signals via photoelectric sensors, and finally, data processing is performed by circuits and computers to calculate the iron content.

[0017] The inductively coupled plasma atomic emission spectrometry (ICP-AES) mentioned in the present invention has obvious advantages over the traditional visible spectrophotometry. Its basic principle is to use hydrochloric acid to extract iron ions (Fe 3+ 、Fe 2+) by measuring the sample's spectral signal intensity, thereby determining the presence and concentration of iron in the sample. This method is time-efficient and easy to use, effectively saving experimental costs while also reducing human error.

[0018] The technical solution, its implementation process and principles are further explained below.

[0019] As one aspect of the technical solution of the present invention, a method for rapidly determining the iron content in dichloroethane is provided, comprising:

[0020] The extractant is mixed evenly with the dichloroethane solution to be tested, and an extraction reaction is carried out. The upper layer liquid is taken to obtain the sample liquid to be tested, wherein the extractant has an extraction effect on both divalent iron ions and trivalent iron ions;

[0021] Prepare iron standard solution, determine the iron content by inductively coupled plasma atomic emission spectrometry, and draw a standard curve;

[0022] The concentration of the iron element in the sample solution to be tested is determined by inductively coupled plasma atomic emission spectrometry, and the iron content in the dichloroethane solution to be tested is calculated based on the standard curve.

[0023] In some embodiments, the dichloroethane solution to be tested is a sample obtained during dichloroethane production or experiment, and the dichloroethane solution to be tested contains Fe 3+ and Fe 2+ , and the Fe in the dichloroethane solution to be tested during the extraction reaction 3+ Not restored.

[0024] The dichloroethane solution to be tested in the present invention is derived from an actual production process or prepared in a laboratory, ensuring that it is fully representative. When sampling in actual production, relevant sampling standards and specifications should be followed to ensure that the sample can accurately reflect the actual iron content of the dichloroethane on the production line.

[0025] Specific sampling methods of the dichloroethane solution to be tested may include:

[0026] Furthermore, in a continuously produced pipeline, the dichloroethane solution to be tested is prepared by adopting a method of timed multi-point sampling followed by mixing.

[0027] Furthermore, in batch products produced intermittently, the dichloroethane solution to be tested is prepared by sampling from multiple points at different locations.

[0028] Furthermore, in preparing the dichloroethane solution to be tested in the laboratory, the dichloroethane solution to be tested is prepared in a manner simulating production conditions.

[0029] In some embodiments, the method for rapidly determining the iron content in dichloroethane specifically comprises: adding the extractant to the dichloroethane solution to be tested, shaking it sufficiently, performing the extraction reaction, then allowing it to stand, and taking the upper layer liquid to a fixed volume to obtain the sample solution to be tested.

[0030] Furthermore, the extractant includes a hydrochloric acid solution.

[0031] Regarding specific measurement conditions, the volume ratio of hydrochloric acid to solvent in the hydrochloric acid solution is 1:1 to 9. The preparation of the hydrochloric acid solution refers to the national standard GB / T 603-2023. In the present invention, if the volume ratio of the hydrochloric acid solution exceeds 1:1, the concentration of the hydrochloric acid solution is too high, which is not conducive to the analytical conditions of the instrument. In addition, the hydrochloric acid solution is highly volatile and has a significant harm to the human body. If the volume ratio is less than 1:9, the concentration of the hydrochloric acid solution is too low, and the reaction during dichloroethane extraction is incomplete.

[0032] Furthermore, the volume ratio of the extractant to the dichloroethane solution to be tested is 1 to 2: 1 to 2. In the present invention, when the extraction ratio is exceeded, the reaction is incomplete, resulting in a smaller result.

[0033] In a typical implementation case, the volume ratio of hydrochloric acid to solvent in the hydrochloric acid solution is 1:9, that is, the molar concentration of the hydrochloric acid solution is 1.2 mol / L, and the volume ratio of the hydrochloric acid solution to the dichloroethane solution to be tested is 1:1. This experimental condition has been verified through multiple experiments and can ensure that the extraction efficiency of iron ions reaches a high level while reducing the interference of impurities.

[0034] Furthermore, the shaking time is 3 to 5 minutes, and the standing time is 2 to 3 minutes. Within this standing time range, the organic phase and the aqueous phase of the sample solution can be separated into separate layers.

[0035] In a typical implementation case, the shaking time is 5 minutes, and the standing time is 2 minutes.

[0036] Furthermore, the extraction reaction time is 3 to 5 minutes.

[0037] In a typical implementation case, the extraction reaction time is 5 minutes.

[0038] Furthermore, the upper layer liquid is diluted to 1 to 2 times the volume to obtain the sample liquid to be tested.

[0039] In a typical embodiment, 50 mL of the upper layer solution is transferred to a 100 mL volumetric flask and diluted to 2 times to obtain the sample solution to be tested. 3+ 、Fe 2+After the extraction reaction is completed, since dichloroethane and water are immiscible, the sample solution will be divided into an aqueous phase and an organic phase, wherein the upper liquid is the aqueous phase and the lower liquid is the organic phase.

[0040] In some embodiments, the method for rapidly determining the iron content in dichloroethane specifically includes: selecting an iron standard solution with a concentration of 100 ug / mL, diluting and preparing low-concentration iron standard solutions of different concentrations, and then using inductively coupled plasma atomic emission spectrometry to determine the iron content of the low-concentration iron standard solutions, and drawing a standard curve.

[0041] Furthermore, the iron content in the low-concentration iron standard solution ranges from 0 to 50 ug / mL.

[0042] Furthermore, the concentration determination window range of the iron content in the dichloroethane solution to be measured is 0 to 4 ug / mL.

[0043] In a typical implementation case, the original iron standard solution concentration is 1000ug / mL. Accurately pipette 10.00ml of original iron standard solution and place it in a 100ml capacity, add water and be diluted to the scale, shake up, and now the iron standard solution concentration is 100ug / mL. When preparing low-concentration iron standard solutions of different concentrations, accurately pipette 0.00ml, 1.00ml, 2.00ml, 4.00ml of 100ug / mL iron standard solution and place it in a 100ml volumetric flask, add water and be diluted to the scale. During the pipetting process, a pipette with precision that meets the requirements must be used to ensure the accuracy of the pipetting volume. Water should be slowly added to the scale mark during dilution, and then water is added dropwise to the scale using a dropper to ensure the accuracy of the solution concentration. By preparing a series of standard solutions with different iron contents, calibration curves are subsequently drawn for subsequent drawing, providing a reference basis for accurately measuring iron content in the sample solution.

[0044] In some embodiments, the method for rapidly determining the iron content in ethylene dichloride further comprises: preheating and calibrating the inductively coupled plasma atomic emission spectrometer during the determination process to ensure that the instrument is in optimal working condition and to improve the accuracy of the determination results.

[0045] In some embodiments, the method measures the iron content in ethylene dichloride within an error of ±5%.

[0046] As one aspect of the technical solution of the present invention, it also provides the application of the method in the field of preparing dichloroethane.

[0047] In summary, the present application can accurately determine the iron content in dichloroethane under a wider range of conditions within an acceptable range of analytical result errors, and provides a more reliable and simple analytical method for timely adjusting production process parameters according to iron content data during the production process to ensure the production of qualified dichloroethane. It can also reduce production costs and the generation of waste liquid to a certain extent.

[0048] In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with embodiment. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. Those skilled in the art will make modifications or equivalent substitutions based on understanding the technical solution of the present invention, without departing from the spirit and scope of the technical solution of the present invention, and all should be encompassed within the protection scope of the present invention.

[0049] Where specific experimental procedures or conditions are not specified in the examples, the experiments were carried out according to conventional experimental procedures or conditions described in literature in the field. Reagents or instruments used without manufacturer specified are commercially available. Commercially available options for other raw materials and instruments not mentioned are conventional and do not relate to the core technical means of the present invention.

[0050] Example 1

[0051] 1. Sample Preparation and Extraction: Use a calibrated graduated cylinder to measure 100 mL of dichloroethane sample and place it in a clean separatory funnel. Add 100 mL of hydrochloric acid solution with a volume ratio of 1:9. To ensure adequate extraction, shake the separatory funnel vigorously for 5 minutes to allow the hydrochloric acid to fully react with the iron ions in the dichloroethane. Then, let the sample stand for 2 minutes to allow the aqueous and organic phases of the sample solution to separate completely.

[0052] 2. Solution transfer and volume adjustment: Use a pipette to accurately transfer 50 mL of the upper layer solution into a 100 mL volumetric flask. Then, adjust the volume to the mark with distilled water. During the adjustment process, follow the principle of "small amounts, multiple times" to ensure the accurate volume of the solution. After adjusting the volume, shake the volumetric flask upside down to mix the solution evenly.

[0053] 3. Calibration Curve: Using a 100 μg / mL iron standard solution, measure the iron standard solution according to Table 1 and place it into four 100 mL volumetric flasks. During pipetting, strictly follow the pipette operating instructions to ensure accurate volume transfer. After adding the iron standard solution, dilute to the mark with water and shake again.

[0054] 4. Iron ion content determination: The iron ion content of the sample solution and the standard solution was determined using inductively coupled plasma atomic emission spectrometry. Before the determination, the instrument was preheated and instrument parameters (such as power and carrier gas flow) were optimized to ensure optimal operating conditions and improve measurement accuracy.

[0055] 5. Result Expression and Calculation: Based on the instrument reading, use the formula Fe (ug / mL) = 2A. Where A is the instrument reading in ug / mL. This formula, derived through multiple experiments based on experimental conditions and instrument response characteristics, accurately calculates the iron content in the sample.

[0056] Table 1

[0057] Volume of iron standard solution / mL Corresponding iron concentration ug / mL 0 0 1.0 1 2.0 2 4.0 4

[0058] Example 2-10

[0059] The implementation process is the same as that of Example 1, except that: in Examples 2-10, dichloroethane samples with different iron contents are taken to perform the above-mentioned iron content determination, and the production dates of the dichloroethane samples are different.

[0060] During the experiment, ethylene dichloride samples from different production sources were numbered and recorded to ensure the traceability of the experimental data. The accuracy and stability of the method of the present invention were further verified through multiple sets of parallel experiments.

[0061] Example 11

[0062] The implementation process is the same as that of Example 1, except that the volume ratio of hydrochloric acid to solvent in the hydrochloric acid solution is 1:1.

[0063] Example 1

[0064] The implementation process is the same as that of Example 1, except that the volume ratio of hydrochloric acid to solvent in the hydrochloric acid solution is 1:5.

[0065] Comparative Example 1

[0066] 1. Sample Preparation and Extraction: Take a 100 mL sample of the same dichloroethane as in Example 1 and place it in a separatory funnel. Add 100 mL of 1.2 mol / L hydrochloric acid solution and shake thoroughly for 5 minutes to extract the iron ions into the aqueous phase. After the aqueous and organic phases have fully separated, open the bottom stopper of the separatory funnel, allow the organic phase to flow into another separatory funnel, and close the bottom stopper.

[0067] 2. Further processing and solution preparation: Pipette 50mL of the upper layer solution into a 250mL beaker, add 0.5mL of ammonia solution to a molar concentration of 6.65mol / L (reference national standard GB / T 603-2023), and heat on an electric stove and boil for 5 minutes. Stir continuously during heating to prevent the solution from boiling violently. After cooling, transfer to a 100mL volumetric flask. At the same time, prepare a blank solution in another 250mL beaker, add 50mL of hydrochloric acid solution to a molar concentration of 1.2mol / L, and add 0.5mL of ammonia solution to a molar concentration of 6.65mol / L. Heat on an electric stove and boil for 5 minutes. After cooling, transfer to a 100mL volumetric flask.

[0068] 3. Color reaction: Add 10 mL of water, 2 mL of hydroxylamine hydrochloride solution, and 5 mL of o-phenanthroline solution to two 100 mL volumetric flasks, respectively. Adjust the pH to 8-9 with aqueous ammonia solution. Use a pH meter to accurately measure the pH value during the adjustment process to ensure that the pH value is within the specified range. Then add 5 mL of acetic acid-ammonium acetate buffer solution. Shake thoroughly after each addition to mix the solution evenly. Finally, dilute with water to the same scale, shake well, and let it stand for 20 minutes to allow the color reaction to fully develop.

[0069] 4. Absorbance measurement: Place the sample solution in a cuvette. At a wavelength of 510 nm, first adjust the spectrophotometer zero point with a blank solution, and then measure the absorbance of the sample solution. During the operation, ensure that the light-transmitting surface of the cuvette is clean and free of stains to ensure the accuracy of the measurement results.

[0070] 5. Draw the standard curve: Use a 10 μg / mL iron standard solution. According to Table 2, measure the iron standard solution and place it in six 50 mL volumetric flasks. Add 10 mL of hydrochloric acid solution to each flask, add water to approximately 20 mL, and adjust the solution pH to 2-3 using a 6.65 mol / L ammonia solution. Also use a pH meter to measure the pH during this adjustment process. Then, add 1 mL of hydroxylamine hydrochloride solution, 5 mL of acetic acid-sodium acetate buffer solution, and 2 mL of 1,10-phenanthroline solution. Dilute to the mark with water and shake well. After standing for 15 minutes, place the cuvette in a spectrophotometer and adjust the spectrophotometer zero point with a blank solution at a wavelength of 510 nm. Measure the absorbance of the solution. Draw the standard curve with the iron content (μg) as the horizontal axis and the corresponding absorbance as the vertical axis.

[0071] 6. Expression and calculation of results: Calculate using the formula Fe (μg) = 2A, where A is the instrument reading in μg.

[0072] Table 2

[0073] Volume of iron standard solution / mL Corresponding iron mass / μg 0 0 2.0 20 4.0 40 6.0 60 8.0 80 10.0 100

[0074] Comparative Example 2

[0075] The implementation process is the same as that of Comparative Example 1, except that: Comparative Example 2 takes the same dichloroethane sample as Example 2 to perform the above-mentioned iron content determination.

[0076] Comparative Example 3

[0077] The implementation process is the same as that of Comparative Example 1, except that: Comparative Example 3 takes the same dichloroethane sample as Example 3 to perform the above-mentioned iron content determination.

[0078] Comparative Example 4

[0079] The implementation process is the same as that of Comparative Example 1, except that: Comparative Example 4 takes the same dichloroethane sample as Example 4 to perform the above-mentioned iron content determination.

[0080] Comparative Example 5

[0081] The implementation process is the same as that of Comparative Example 1, except that: in Comparative Example 5, the same dichloroethane sample as that of Example 5 is used to perform the above-mentioned iron content determination.

[0082] Comparative Example 6

[0083] The implementation process is the same as that of Comparative Example 1, except that: Comparative Example 6 takes the same dichloroethane sample as Example 6 to perform the above-mentioned iron content determination.

[0084] Comparative Example 7

[0085] The implementation process is the same as that of Comparative Example 1, except that: Comparative Example 7 takes the same dichloroethane sample as Example 7 to perform the above-mentioned iron content determination.

[0086] Comparative Example 8

[0087] The implementation process is the same as that of Comparative Example 1, except that: Comparative Example 8 takes the same dichloroethane sample as Example 8 to perform the above-mentioned iron content determination.

[0088] Comparative Example 9

[0089] The implementation process is the same as that of Comparative Example 1, except that: Comparative Example 9 takes the same dichloroethane sample as Example 9 to perform the above-mentioned iron content determination.

[0090] Comparative Example 10

[0091] The implementation process is the same as that of Comparative Example 1, except that: Comparative Example 10 takes the same dichloroethane sample as Example 10 to perform the above-mentioned iron content determination.

[0092] The measurement time and measurement results of Examples 1-10 and Comparative Examples 1-10 in the present invention are shown in Table 3.

[0093] Table 3 Measurement time and measurement results of Examples 1-10 and Comparative Examples 1-10

[0094]

[0095] From the examples and comparative examples, and in combination with Table 3, it can be clearly seen that the method for determining the iron content in dichloroethane provided by the present application significantly reduces the determination time compared to the spectrophotometric method. The traditional spectrophotometric method requires an average of more than 90 minutes to determine one sample, while the method of the present invention only takes about 15 minutes, which significantly improves efficiency. At the same time, compared with the measurement results, the error does not exceed 0.3, which is within the reasonable error range of ±5%.

[0096] The various aspects, embodiments, features and examples of the present invention should be considered as illustrative in all respects and are not intended to limit the present invention, the scope of which is defined solely by the claims. Other embodiments, modifications and uses will be apparent to those skilled in the art without departing from the spirit and scope of the invention as claimed.

[0097] In addition, the inventors of this case also referred to the aforementioned embodiments and conducted experiments using other raw materials, process operations, and process conditions described in this specification, and obtained relatively ideal results.

[0098] Although the present invention has been described with reference to illustrative embodiments, it will be understood by those skilled in the art that various other changes, omissions, and / or additions may be made and that substantial equivalents may be substituted for elements of the described embodiments without departing from the spirit and scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the present invention without departing from the scope of the invention. Therefore, it is not intended that the present invention be limited to the specific embodiments disclosed for carrying out the invention, but rather that the invention will encompass all embodiments falling within the scope of the appended claims.

Claims

1. A method for rapidly determining the iron content in ethylene dichloride, characterized in that: include: The extractant is mixed evenly with the dichloroethane solution to be tested, and an extraction reaction is carried out. The upper layer liquid is taken to obtain the sample liquid to be tested, wherein the extractant has an extraction effect on both divalent iron ions and trivalent iron ions; Prepare iron standard solution, determine the iron content by inductively coupled plasma atomic emission spectrometry, and draw a standard curve; The concentration of the iron element in the sample solution to be tested is determined by inductively coupled plasma atomic emission spectrometry, and the iron content in the dichloroethane solution to be tested is calculated based on the standard curve.

2. The method according to claim 1, characterized in that The dichloroethane solution to be tested is a sample obtained during dichloroethane production or experiment. The dichloroethane solution to be tested contains Fe 3+ and Fe 2+ , and the Fe in the dichloroethane solution to be tested during the extraction reaction 3+ Not restored.

3. The method according to claim 2, characterized in that The method for obtaining the dichloroethane solution to be tested specifically includes: preparing the dichloroethane solution to be tested in a continuously produced pipeline by adopting a method of timed multi-point sampling followed by mixing; and / or, in batch production, preparing the dichloroethane solution to be tested by sampling from multiple points at different locations; And / or, in preparing the dichloroethane solution to be tested in a laboratory, the dichloroethane solution to be tested is prepared in a manner simulating production conditions.

4. The method according to claim 1, wherein Specifically include: The extractant is added to the dichloroethane solution to be tested, shaken sufficiently to carry out the extraction reaction, and then allowed to stand, and the upper layer liquid is taken and fixed to volume to obtain the sample solution to be tested.

5. The method according to claim 4, characterized in that: The extractant includes a hydrochloric acid solution; preferably, the volume ratio of hydrochloric acid to solvent in the hydrochloric acid solution is 1:1 to 9; and / or, the volume ratio of the extractant to the dichloroethane solution to be tested is 1-2:1-2; And / or, the shaking time is 3 to 5 minutes, and the standing time is 2 to 3 minutes; And / or, the extraction reaction time is 3 to 5 minutes; And / or, the upper layer liquid is diluted to 1 to 2 times the volume to obtain the sample liquid to be tested.

6. The method according to claim 1, characterized in that Specifically include: An iron standard solution with a concentration of 100 ug / mL was selected and diluted to prepare low-concentration iron standard solutions of different concentrations. The iron content of the low-concentration iron standard solutions was then determined by inductively coupled plasma atomic emission spectrometry to draw the standard curve.

7. The method according to claim 6, characterized in that: The iron content of the low-concentration iron standard solution ranges from 0 to 50 ug / mL; And / or, the concentration measurement window range of the iron content in the dichloroethane solution to be measured is 0 to 4 ug / mL.

8. The method according to claim 1, characterized in that Also includes: During the measurement process, the inductively coupled plasma atomic emission spectrometer is preheated and calibrated.

9. The method according to claim 1, wherein: The error of the method for determining the iron content in ethylene dichloride is within ±5%.

10. Use of the method according to any one of claims 1 to 9 in the field of preparing ethylene dichloride.

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