Method for detecting heavy metals in aqueous sample

Abstract

The invention discloses a method for detecting heavy metals in an aqueous sample. The invention provides a method for detecting heavy metals in a water-based sample, which comprises the following steps: enriching the heavy metals in the water-based sample by using a hydrophobic solid-phase extraction membrane treated by a chelating agent, so that the heavy metals in the water-based sample are retained in the solid-phase extraction membrane; and detecting the heavy metals retained in the solid-phase extraction membrane by adopting X-ray fluorescence spectrum analysis.

Description

Technical Field

[0001] The invention relates to the field of heavy metal detection, and in particular to a method for detecting heavy metals in aqueous samples. Background Art

[0002] In recent years, my country's ecological environment has suffered very serious damage, especially water pollution has become increasingly serious, which not only affects people's normal life and production activities, but also causes damage to the ecological environment and threatens people's health and life safety. Therefore, the monitoring of environmental water quality has received more and more attention, especially the detection of heavy metal elements in water quality. The key data obtained through monitoring can provide an important basis for environmental pollution control and promote the sustainable development of my country's ecological environment protection.

[0003] At present, the main methods for monitoring heavy metal elements in water quality include atomic absorption method, fluorescence method, electrochemical method, inductively coupled plasma mass spectrometry (ICP-MS), etc. Among them, atomic absorption method and ICP-MS are the most widely used due to their advantages of high detection sensitivity, high accuracy, and simple operation. However, these detection methods generally require operators to perform on-site operations, and the measuring equipment must use inert working gas, which is not conducive to unattended operation. In addition, methods such as ICP-MS will have spectral interference and non-spectral interference, and Na, Ca, Mg, etc. contained in environmental water (such as seawater, etc.) will also affect the detection. Therefore, in the existing methods, in addition to solvent extraction, chelating agents are also required to pre-treat the samples. The existing ICP-MS methods require a long time from pre-treatment to completion of detection.

[0004] For example, cited document 1 discloses a method for online enrichment and determination of ultra-trace methylmercury and / or divalent mercury, which uses an enrichment column for enrichment and elution, and uses ICP-MS for detection after passing through a separation column. It has many steps and a complicated procedure.

[0005] In recent years, with the development of science and technology, the detection capabilities of instruments have been significantly improved. Among them, the detection limit of energy dispersive X-ray fluorescence spectrometer for metal elements can reach the microgram / gram level, making it promising for use in monitoring heavy metal elements in water quality.

[0006] Reference 2 discloses a method for determining trace mercury using an energy dispersive X-ray fluorescence spectrometer. However, the cation selective impregnation film used in the method has complex components and requires an enrichment time of at least 16 hours. It can also only detect one heavy metal element.

[0007] Citations

[0008] Reference 1: CN 111257463A

[0009] Cited document 2: Hatzistavros VS, Kallithrakas-Kontos NG. X-ray fluorescence mercury determination using cation selective membranes at sub-ppb levels. AnalChim Acta. 2014 Jan 27;809:25-9. Summary of the invention

[0010] Problem that the invention aims to solve

[0011] Although the prior art such as References 1 and 2 has attempted to detect heavy metals in aqueous samples, Reference 1, for example, requires a complex enrichment column enrichment, elution, and separation column separation process before detection, and is applicable to a single heavy metal, which can only detect mercury. Reference 2 also requires a long (16 hours) enrichment process and is also only suitable for the detection of a single heavy metal element.

[0012] Therefore, there is still a need for a method that can more quickly perform multiple heavy metal detection and analysis while ensuring analytical accuracy.

[0013] Solutions for solving problems

[0014] The object of the present invention is to provide a method for rapidly detecting various heavy metal elements in an aqueous sample, such as a water sample in an aquatic environment.

[0015] In order to solve the above problems, the inventors conducted in-depth research and explored a method of using solid phase extraction membrane to enrich heavy metal elements in water and using X-ray spectrometer to perform quantitative analysis of heavy metal elements.

[0016] Specifically, the present invention includes the following technical solutions.

[0017] [1]. A method for detecting heavy metals in an aqueous sample, the method comprising:

[0018] Enriching heavy metals in an aqueous sample using a hydrophobic solid phase extraction membrane treated with a chelating agent, so that the heavy metals in the aqueous sample are retained in the solid phase extraction membrane;

[0019] The heavy metals retained in the solid phase extraction membrane are detected by X-ray fluorescence spectroscopy.

[0020] Wherein, the chelating agent is an organic chelating agent.

[0021] [2] According to the method described in [1], the adsorption filler in the solid phase extraction membrane is silica gel modified with hydrophobic groups.

[0022] [3] According to the method described in [2], the hydrophobic group is a hydrocarbon group, preferably a C18 group.

[0023] [4] The method according to any one of [1] to [3], wherein the chelating agent is a thiol-containing chelating agent.

[0024] [5] According to the method described in [4], the thiol-containing chelating agent is dithizone.

[0025] [6]. The method according to any one of [1] to [5], wherein the heavy metal includes at least one of Pb, Cd, Cr, Hg, As, Fe, Cu and Zn.

[0026] [7] The method according to any one of [1] to [6], wherein the method simultaneously detects at least two of Pb, Cd, Cr, Hg, As, Fe, Cu and Zn.

[0027] [8] According to the method described in any one of [1] to [7], the aqueous sample is passed through the hydrophobic solid phase extraction membrane treated with a chelating agent by pressurization, vacuum or centrifugation, so that the heavy metals in the aqueous sample are retained in the solid phase extraction membrane.

[0028] [9] According to any one of the methods [1] to [8], the X-ray fluorescence spectrometry is selected from wavelength dispersive X-ray fluorescence spectrometry or energy dispersive X-ray fluorescence spectrometry, preferably energy dispersive X-ray fluorescence spectrometry.

[0029]

[10] . According to the method described in any one of [1] to [9], the aqueous sample is a water sample.

[0030]

[11] . According to the method described in

[10] , the water sample is selected from at least one of a water sample from a water environment, industrial wastewater, domestic water, solid digestion solution and eluent.

[0031] Effects of the Invention

[0032] The present invention can achieve the following technical effects through the implementation of the above technical solution:

[0033] The solid phase extraction membrane treated with a chelating agent provided by the present invention can effectively enrich heavy metal elements in water samples, and the adsorption efficiency of various metal elements is greater than 90%. Combined with the energy dispersive X-ray spectrometer measurement technology, it can realize the quantitative analysis of heavy metal elements in aqueous samples, especially water samples. The analysis method is simple and rapid, and has application prospects in the monitoring of heavy metal elements in water environment and industrial wastewater. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 The adsorption efficiency of different metal elements on C18 solid phase extraction membrane is shown in Figure 1.25μg, 2.5μg, 5μg, 10μg, and 20μg from left to right for each element.

[0035] Figure 2 The spectrum was measured by EDX-7000.

[0036] Figure 3A to Figure 3C is the metal element concentration curve ( Figure 3A :Ni; Figure 3B :Cd; Figure 3C :Pb). DETAILED DESCRIPTION

[0037] Various exemplary embodiments, features and aspects of the present invention will be described in detail below. The word "exemplary" used here means "used as an example, embodiment or illustrative". Any embodiment described here as "exemplary" is not necessarily interpreted as being superior or better than other embodiments.

[0038] In addition, in order to better illustrate the present invention, numerous specific details are provided in the following specific embodiments. It should be understood by those skilled in the art that the present invention can be implemented without certain specific details. In other examples, methods, means, equipment and steps well known to those skilled in the art are not described in detail in order to highlight the subject matter of the present invention.

[0039] Unless otherwise stated, the units used in this specification are all international standard units, and the numerical values ​​and numerical ranges appearing in the present invention should be understood to include the inevitable systematic errors in industrial production.

[0040] In this specification, the word "may" means both performing a certain process and not performing a certain process.

[0041] In this specification, the references to "some specific / preferred embodiments", "other specific / preferred embodiments", "embodiments", etc., mean that the specific elements (e.g., features, structures, properties and / or characteristics) described in connection with the embodiments are included in at least one embodiment described herein, and may or may not exist in other embodiments. In addition, it should be understood that the elements may be combined in various embodiments in any suitable manner.

[0042] In this specification, the numerical range expressed using "a numerical value A to a numerical value B" means a range including the endpoints A and B.

[0043] In this specification, metal atoms or ions react with ligands containing two or more coordinating atoms to form a complex having a ring structure, which is called a chelate. Such a ligand substance that can form a chelate is called a chelating agent, also known as a complexing agent.

[0044] <Method for detecting heavy metal elements in aqueous samples>

[0045] The present invention provides a method for detecting heavy metals in an aqueous sample, which comprises: using a hydrophobic solid phase extraction membrane treated with a chelating agent to enrich the heavy metals in the aqueous sample so that the heavy metals in the aqueous sample are retained in the solid phase extraction membrane; and using X-ray fluorescence spectroscopy to detect the heavy metals retained in the solid phase extraction membrane.

[0046] Aqueous samples

[0047] The aqueous sample applicable to the present invention is not particularly limited, and can be an aqueous sample of any source and type. In some specific embodiments, the aqueous sample can be a water sample. In some more specific embodiments, the water sample can be a water sample from a water environment. The water environment refers to the environment of the formation, distribution and transformation of water in nature, which will have a great impact on human life. The water environment is mainly composed of the surface water environment and the groundwater environment, wherein the surface water environment includes rivers, lakes, oceans, glaciers, etc., and the groundwater environment includes shallow and deep groundwater and spring water.

[0048] In some specific embodiments, the water sample can also be industrial wastewater, domestic water (such as tap water, drinking water, drinking water, etc.), various solid digestion solutions, eluents, etc.

[0049] For the above-mentioned aqueous sample, before using the hydrophobic solid phase extraction membrane treated with a chelating agent to enrich the heavy metals in the aqueous sample, in some embodiments, optional pretreatment may or may not be performed. In some embodiments, before using the hydrophobic solid phase extraction membrane treated with a chelating agent to enrich the heavy metals in the aqueous sample, the aqueous sample is also pretreated to remove impurities in the aqueous sample. Specifically, in the case where the aqueous sample is a water sample from an aquatic environment (such as seawater, lake water, etc.), industrial wastewater, etc., from the perspective of extending the service life of the solid phase extraction membrane, avoiding the blockage of the solid phase extraction membrane to affect adsorption, and detection efficiency (it should be noted that the use of a solid phase extraction membrane instead of a solid phase extraction column has significantly reduced this risk), it is preferred to perform pretreatment for the purpose of removing particulate matter (such as mud, etc.) in the aqueous sample. In some specific embodiments, the pretreatment may be filtration. In some exemplary embodiments, the aqueous sample can be filtered using a 0.22μm or 0.45μm filter membrane.

[0050] heavy metal

[0051] Heavy metals refer to those with a density greater than 4.5 g / cm 3 Metals mainly include gold (Au), silver (Ag), mercury (Hg), copper (Cu), iron (Fe), lead (Pb), cadmium (Cd), chromium (Cr), arsenic (As), zinc (Zn), etc. Among them, heavy metals such as Hg, Pb, and Cr will cause environmental pollution.

[0052] In some embodiments, the method for analyzing heavy metal elements in aqueous samples of the present invention can detect heavy metals including at least Pb, Cd, Cr, Hg, As, Fe, Cu, and Zn.

[0053] In some preferred embodiments, the method for analyzing heavy metal elements in aqueous samples of the present invention can detect heavy metals including at least Pb, Cd, Cr, Hg, Fe, Cu, and Zn.

[0054] For the heavy metals of the present invention, by using the method of the present invention described below, one or more heavy metals can be detected in one detection. In some preferred embodiments, the detection method of the present invention can detect 2 or more heavy metals at the same time.

[0055] It should be noted that, in this specification, "simultaneous detection" means detecting multiple heavy metals at one time for one injection, rather than detecting at strictly the same time.

[0056] Chelating agents

[0057] In the present invention, chelating agents include inorganic chelating agents (polyphosphate chelating agents), organic chelating agents and natural modified polymer capture agents (starch, cellulose, plant gum and polysaccharide, etc.). In some embodiments, organic chelating agents include carboxylic acid chelating agents (aminocarboxylic acids, hydroxycarboxylic acids, hydroxyaminocarboxylic acids), organic polyphosphonic acid chelating agents, polycarboxylic acid chelating agents, thiol (-SH)-containing chelating agents, Schiff bases, etc.

[0058] Considering the heavy metal adsorption efficiency of the solid phase extraction membrane in the enrichment step, especially the solid phase extraction membrane with C18 modified silica gel (e.g., C18 modified silica gel particles) as the adsorption filler, in some preferred embodiments, the chelating agent can be a chelating agent containing a thiol group. In some more preferred embodiments, the chelating agent containing a thiol group can be dithizone.

[0059] Dithizone, also known as diphenylthioazocarbonyl hydrazide, diphenylthiocarbazone, diphenylhydrazone, diphenylthiozone, has a molecular formula of C 13 H 12 N4S, its structural formula is as follows:

[0060]

[0061] In the present invention, the method of treating the solid phase extraction membrane with a chelating agent is not particularly limited. For example, the solid phase extraction membrane may be infiltrated with a solution containing a chelating agent.

[0062] In the present invention, the amount of the chelating agent can be determined according to the diameter and thickness of the solid phase extraction membrane, the type of sample to be tested, etc. In some exemplary embodiments, for a solid phase extraction membrane with a diameter of 25 mm, 80 to 120 μg, preferably 90 to 110 μg, more preferably 95 to 105 μg, for example 95 μg, 96 μg, 97 μg, 98 μg, 99 μg, 100 μg of the chelating agent dithizone can be used.

[0063] Solid Phase Extraction Membrane

[0064] The solid phase extraction membrane only needs to be able to adsorb and enrich the heavy metals to be detected, and a commercially available solid phase extraction membrane can be selected and used according to the sample to be detected and the heavy metals to be detected.

[0065] As an example of a solid phase extraction membrane, the adsorption filler in the solid phase extraction membrane can be silica gel particles modified with hydrophobic groups, and the hydrophobic groups can be various hydrocarbon groups, such as C8 groups, C18 groups or phenyl groups, etc. In some embodiments of the present invention, C18-modified silica gel particles are used as adsorption fillers.

[0066] The thickness of the solid phase extraction membrane of the present invention is not particularly limited, and a solid phase extraction membrane of suitable thickness can be selected according to the properties and volume of the aqueous sample to be tested, and the loading method of solid phase extraction, etc. Considering factors such as the efficiency of solid phase extraction and the adsorption efficiency of heavy metals, the thickness of the solid phase extraction membrane can be 0.05 to 5 mm, for example, 0.1 mm, 0.3 mm, 0.5 mm, 0.7 mm, 1 mm, 1.5 mm, 2 mm, 3 mm, etc.

[0067] The solid phase extraction membrane of the present invention preferably has a circular or approximately circular shape. There is no particular limitation on the diameter of the membrane. The solid phase extraction membrane of a suitable diameter can be selected according to the properties and volume of the aqueous sample to be tested, the loading method for solid phase extraction, and the amount of heavy metals detected in combination with X-ray fluorescence spectroscopy. In some embodiments, the diameter of the solid phase extraction membrane is above 5 mm, for example, above 10 mm, above 15 mm, but not limited thereto. In some specific embodiments, the diameter of the solid phase extraction membrane is 25 mm, 47 mm, or 90 mm.

[0068] In the present invention, there is no particular limitation on the method for enriching heavy metals in aqueous samples using a hydrophobic solid phase extraction membrane treated with a chelating agent. For example, pressurization, vacuumization or centrifugation can be used to make the aqueous sample pass through the hydrophobic solid phase extraction membrane treated with a chelating agent, so that the heavy metals in the aqueous sample are retained in the solid phase extraction membrane.

[0069] In some embodiments, the heavy metals in the aqueous sample are retained in the solid phase extraction membrane and can be directly detected by X-ray fluorescence spectroscopy without the need for an elution step, thereby simplifying the detection step and improving efficiency, as well as the effect of the elution step on detection accuracy and sensitivity.

[0070] In some exemplary embodiments, the aqueous sample is passed through the hydrophobic solid phase extraction membrane treated with a chelating agent at an appropriate flow rate by positive pressure pushing or negative pressure suction (eg, vacuum filtration) manually or by a pump.

[0071] Compared with the solid phase extraction column, the solid phase extraction membrane used in the present invention has the advantages of large diameter and large area. The solid phase extraction membrane is suitable for processing large volume aqueous samples, the sample loading time can be greatly shortened, and the risk of clogging is reduced.

[0072] X-ray fluorescence spectroscopy

[0073] X-ray fluorescence spectrometry refers to a method of using primary X-ray photons or other microscopic particles to excite atoms in the substance to be tested, causing them to produce fluorescence (secondary X-rays) to analyze the composition of the substance and study its chemical state. X-ray fluorescence spectrometry can be divided into wavelength dispersive X-ray fluorescence (Wavelength Dispersive X-Ray Fluorescence, WDXRF) spectrometry and energy dispersive X-ray fluorescence (Energy Dispersive X-Ray Fluorescence, EDXRF) spectrometry according to differences in excitation, dispersion and detection methods. As a comprehensive analysis method, EDXRF spectrometry has the advantages of in-situ, rapid, accurate, simple, non-destructive and multi-element analysis.

[0074] In the present invention, considering factors such as the number of types of heavy metal elements to be detected, the convenience of detection, and the effective coordination with the solid phase extraction membrane, in some preferred embodiments, energy dispersive X-ray fluorescence spectroscopy analysis is used.

[0075] Energy dispersive X-ray fluorescence spectrometry analysis can be performed using a commercially available energy dispersive X-ray spectrometer, such as the energy dispersive X-ray spectrometer EDX-7000 produced by Shimadzu used in the examples below. During the detection, the parameters of the energy dispersive X-ray spectrometer (such as voltage, current, filter selection, beam spot size, time, etc.) can be set according to the instruction manual of the energy dispersive X-ray spectrometer.

[0076] Example

[0077] The embodiments of the present invention will be described in detail below in conjunction with the examples, but those skilled in the art will appreciate that the following examples are only used to illustrate the present invention and should not be considered to limit the scope of the present invention. If no specific conditions are specified in the examples, they are carried out according to normal conditions or the conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they are all conventional products that can be obtained commercially.

[0078] Measuring materials and instruments

[0079] C18 solid phase enrichment membrane (Empore, 2115-C18, 25mm)

[0080] Dithizone (Sigma-Aldrich)

[0081] Cation + anion exchange resin membrane (Empore, 2151, 2152, 25mm)

[0082] Chelating resin membrane (Empore, 2171, 25mm)

[0083] Filtration device (Tianjin Jinteng)

[0084] The content of heavy metal elements in water samples was determined using Shimadzu ICPMS-2030.

[0085] The heavy metal elements in C18 solid phase extraction membrane (i.e., solid phase extraction membrane with C18 modified silica gel particles as adsorption filler) were determined using an energy dispersive X-ray spectrometer (Shimadzu, EDX-7000), referred to as EDX.

[0086] Enrichment of heavy metal elements in water samples

[0087] The enrichment of heavy metal elements in water samples uses C18 modified silica gel particles as a solid phase extraction membrane with adsorption filler, referred to as C18 solid phase enrichment membrane (diameter ф25mm). Before enrichment, the C18 solid phase enrichment membrane needs to be pretreated with a chelating agent dithizone (100μg). Then, the sample solution containing heavy metal elements is added to the filtration device for vacuum filtration. By measuring the content of metal elements in the solution before and after filtration, the adsorption efficiency of the metal elements is calculated, and the content of heavy metal elements in the solid phase extraction membrane with C18 modified silica gel particles as adsorption filler is determined by EDX.

[0088] Test Results

[0089] 1. Adsorption efficiency of heavy metal elements

[0090] After element enrichment of 10 mL sample solution containing Ag, Cu, Fe, and Zn (1.25 μg-20 μg), the content of metal elements in the solution before and after adsorption was determined by ICP-MS. The results are as follows: Figure 1 As shown. Figure 1 It can be seen that the four elements Ag, Cu, Fe and Zn can be quantitatively adsorbed on the solid phase extraction membrane with C18 modified silica gel particles as adsorption filler, and the adsorption efficiency is greater than 90%.

[0091] 2. Determination of heavy metal elements in solid phase extraction membrane

[0092] After enriching 10 mL of sample solution containing Ni, Cd, and Pb (1 μg-8 μg) using C18 modified silica gel particles as the solid phase extraction membrane adsorption filler, the metal element content was determined using EDX. The instrument measurement conditions are shown in Table 1. The test results are shown in Figure 2 shown.

[0093] Table 1 EDX measurement conditions

[0094] parameter Numeric Instrument Model EDX-7000 Voltage 50KV Current 113-Auto Filter #1 Size (beam spot) 10mm time Live-100

[0095] From the EDX analysis results, it can be seen that after the heavy metal elements in the water are enriched by the solid phase extraction membrane with C18 modified silica gel particles as adsorption filler, the three metal elements Ni, Cd, and Pb show good linearity in the content range of 1μg-8μg (such as Figure 3A to Figure 3C This indicates that solid phase extraction membrane enrichment-EDX determination technology can accurately and quickly analyze metal elements and has application prospects in the detection of heavy metal elements in water quality.

[0096] It can be seen that the C18 modified silica gel particles are used as solid phase extraction membranes and chelating agents for adsorption fillers to enrich heavy metal elements in water samples, and the method of element quantitative analysis is carried out with the help of energy dispersive X-ray spectrometer. Using a 25mm C18 solid phase extraction membrane and 100μg of chelating agent, heavy metal elements such as Ni, Cd, and Pb can be effectively enriched from 10mL of aqueous solution samples, providing technical support for the monitoring of heavy metal elements in industrial wastewater.

[0097] Moreover, based on the above tests, it can be seen that the solid phase extraction membrane using C18 modified silica gel particles treated with chelating agents as adsorption fillers can effectively enrich heavy metal elements in water samples, and the metal element adsorption efficiency is greater than 90%; combined with energy dispersive X-ray spectrometer measurement technology, quantitative analysis of heavy metal elements in water quality can be achieved. This analysis method is simple and rapid, and has application prospects in the monitoring of heavy metal elements in industrial wastewater.

[0098] Comparative testing of enrichment membranes

[0099] In comparative tests, water samples from ambient water were enriched using the following enrichment membranes:

[0100] (1) cation + anion exchange resin membrane (25 mm), hereinafter referred to as cation membrane;

[0101] (2) chelating resin membrane (25 mm), hereinafter referred to as chelating membrane;

[0102] (3) The solid phase extraction membrane (25 mm) of the dithizone-treated C18 modified silica gel particles of the present invention as adsorption filler, hereinafter referred to as C18 membrane.

[0103] The sample volume is 50mL (sea water, lake water), and the test elements include: Pb, Cd, Cr, As, Ni, Cu, Zn, Mn, Fe, Co, Hg, Cs, and Mg.

[0104] Metal element concentration: 200ng / mL

[0105] The performance comparison results of the three enrichment membranes are shown in the table below:

[0106] Table 2 Seawater spike recovery - 10 μg

[0107]

[0108]

[0109] Table 3 Lake water spike recovery - 10 μg

[0110] element Chelating membrane C18 membrane Pb 80％ 85％ Cd 76％ 85％ Cr 97％ 101％ Hg 65％ 116％ As 20％ 33％

[0111] Selectivity of three enrichment membranes for other elements

[0112] Table 4 Recovery of spiked seawater - 10 μg

[0113] element Cationic membrane Chelating membrane C18 membrane Fe 98％ 88％ 97％ Cu 94％ 97％ 99％ Zn 98％ 100％ 97％

[0114] Table 5 Lake water spike recovery - 10 μg

[0115]

[0116]

[0117] It should be noted that, although the technical solution of the present invention is introduced with specific examples, those skilled in the art will appreciate that the present invention should not be limited thereto.

[0118] The embodiments of the present invention have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The selection of terms used herein is intended to best explain the principles of the embodiments, practical applications, or technical improvements in the market, or to enable other persons of ordinary skill in the art to understand the embodiments disclosed herein.

Claims

1. A method for detecting heavy metals in aqueous samples, characterized in that: The method comprises: Enriching heavy metals in an aqueous sample using a hydrophobic solid phase extraction membrane treated with a chelating agent, so that the heavy metals in the aqueous sample are retained in the solid phase extraction membrane; X-ray fluorescence spectroscopy is used to detect the heavy metals retained in the solid phase extraction membrane, wherein the chelating agent is an organic chelating agent.

2. The method according to claim 1, characterized in that The adsorption filler in the solid phase extraction membrane is silica gel modified with hydrophobic groups.

3. The method according to claim 2, characterized in that The hydrophobic group is a hydrocarbon group.

4. The method according to any one of claims 1 to 3, characterized in that The chelating agent is a chelating agent containing a thiol group.

5. The method according to claim 4, characterized in that The thiol-containing chelating agent is dithizone.

6. The method according to any one of claims 1 to 5, characterized in that: The heavy metal includes at least one of Pb, Cd, Cr, Hg, As, Fe, Cu and Zn.

7. The method according to any one of claims 1 to 6, characterized in that: The method simultaneously detects at least two of Pb, Cd, Cr, Hg, As, Fe, Cu and Zn.

8. The method according to any one of claims 1 to 7, characterized in that: The aqueous sample is passed through the hydrophobic solid phase extraction membrane treated with a chelating agent by pressurization, vacuum or centrifugation, so that the heavy metals in the aqueous sample are retained in the solid phase extraction membrane.

9. The method according to any one of claims 1 to 8, characterized in that: The X-ray fluorescence spectrometry is selected from wavelength dispersive X-ray fluorescence spectrometry or energy dispersive X-ray fluorescence spectrometry.

10. The method according to any one of claims 1 to 9, characterized in that: The aqueous sample is a water sample.

11. The method according to claim 10, characterized in that The water sample is selected from at least one of a water sample from a water environment, industrial wastewater, domestic water, a solid digestion solution and an eluent.

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