Method for detecting organic metal compounds in aqueous sample

Abstract

The invention discloses a method for detecting organic metal compounds in an aqueous sample. The invention provides a method for detecting an organic metal compound in a water-based sample, which comprises the following steps: an enrichment step: enriching a metal-containing component in the water-based sample by using a hydrophobic solid-phase extraction column treated by a chelating agent, so that the metal-containing component in the water-based sample is retained in the solid-phase extraction column, the chelating agent comprises a sulfydryl-containing chelating agent; an elution step: eluting the metal-containing components retained in the solid phase extraction column from the solid phase extraction column; a separation step: separating the metal-containing component eluted from the solid-phase extraction column through liquid chromatography to separate out an organic metal compound; and a detection step of detecting the organic metal compound separated by liquid chromatography, the organic metal compound including a lead-containing organic metal compound.

Description

Technical Field

[0001] The invention relates to the field of metal compound detection, and in particular to a method for detecting organic metal compounds 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] Lead pollution is an important pollution in the environment, mainly caused by the discharge of waste gas, waste water, waste residue, etc. generated by lead-using enterprises in the industrial production process into the environment. As a toxic heavy metal element, lead poisoning can cause symptoms such as palpitations, mental disorders, three lows (low blood pressure, body temperature, and pulse rate), heart and respiratory dysfunction, and severe poisoning can even endanger life. In environmental media, the toxicity of lead is closely related to its form. For example, the toxicity of tetraethyl lead is 100 times that of metallic lead. In the mid-twentieth century, tetraethyl lead was commonly used as a gasoline additive to increase the octane number of automobile fuel. At present, tetraethyl lead is a key monitoring project in my country's "Surface Water Environmental Quality Standard" (GB 3838-2002) and "Domestic Water Hygiene Standard" (GB5749-2022), and its limit value is stipulated to be 0.0001 mg / L. In order to protect the environment, the country began to enforce the implementation of lead-free gasoline on January 1, 2000, but tetraethyl lead can still be detected in some environmental water bodies, soil and human blood.

[0004] The main analytical methods for tetraethyl lead in environmental water bodies include liquid phase extraction-dithizone colorimetry, liquid-liquid extraction-liquid chromatography, gas chromatography-mass spectrometry, headspace solid phase microextraction-gas chromatography-mass spectrometry, solid phase extraction-gas chromatography-inductively coupled plasma mass spectrometry, etc. The method recommended by the national standard (GB T5750.6-2023) is the dithizone colorimetry method, but this method has defects such as cumbersome operation, low precision and sensitivity, and the need to use toxic reagents. In addition, its detection limit is equivalent to the evaluation standard and cannot meet the monitoring requirements of tetraethyl lead in environmental water quality. Although other methods have improved the detection sensitivity, they generally require pre-enrichment of the sample, the operation is relatively complicated, and the precision and repeatability of the method have high requirements on the operator. For example, reference 1 discloses a method for detecting tetraethyl lead in water, which uses solid phase extraction technology to enrich tetraethyl lead, requires nitrogen blowing and constant volume, and then needs to be determined by gas chromatography-inductively coupled plasma-mass spectrometry at high temperature and under conditions such as selecting a specific carrier gas, which is harsh and complicated to operate. Reference 2 discloses a method for detecting tetraethyl lead in water, which requires mixing the sample to be tested with methanol and then analyzing it by purge and trap-gas chromatography / mass spectrometry, which also involves complex processes such as high temperature treatment. Reference 3 discloses a method for detecting tetraethyl lead in water by negative pressure headspace gas chromatography-mass spectrometry, and its detection process also involves high temperature treatment, and the detection limit is high.

[0005] Citations

[0006] Reference 1: CN104360003A

[0007] Reference 2: CN111060632A

[0008] Reference 3: CN112630329A Summary of the invention

[0009] Problem that the invention aims to solve

[0010] Although prior art such as References 1 to 3 have attempted to detect organometallic compounds in aqueous samples, they all require relatively strict separation conditions such as high temperature, and the process is relatively complicated. Moreover, under the complicated process, a more ideal detection limit has not been obtained. For example, the detection limit of the method of Reference 3 is 0.003 μg / L, and the detection limit of the method of Reference 1 is also above 5 pg / mL.

[0011] Based on this, it is necessary to establish a rapid and sensitive determination method for organometallic compounds, such as tetraethyl lead, in environmental water.

[0012] Solutions for solving problems

[0013] In order to solve the above problems, the inventors conducted in-depth research and found that the use of online solid phase extraction-liquid chromatography-inductively coupled plasma mass spectrometry (SPE-LC-ICPMS) can achieve a simple and rapid analysis method for organometallic compounds in aqueous samples, such as tetraethyl lead, with better linear range (limit of quantification LOQ) and limit of detection (LOD).

[0014] Specifically, the present invention includes the following technical solutions.

[0015] [1]. A method for detecting an organometallic compound in an aqueous sample, the method comprising:

[0016] an enrichment step, using a hydrophobic solid phase extraction column treated with a chelating agent to enrich the metal-containing components in the aqueous sample, so that the metal-containing components in the aqueous sample are retained in the solid phase extraction column, wherein the chelating agent includes a thiol-containing chelating agent;

[0017] an elution step, eluting the metal-containing components retained in the solid phase extraction column from the solid phase extraction column;

[0018] A separation step of separating the metal-containing components eluted from the solid phase extraction column by liquid chromatography to separate the organometallic compound;

[0019] The detection step is to detect the organic metal compound separated by liquid chromatography.

[0020] The organometallic compound includes a lead-containing organometallic compound.

[0021] [2] According to the method described in [1], the adsorption filler in the hydrophobic solid phase extraction column 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 thiol-containing chelating agent is dithizone.

[0024] [5] According to any one of the methods [1] to [4], in the elution step, the metal-containing components retained in the hydrophobic solid phase extraction column are eluted from the hydrophobic solid phase extraction column using a mobile phase; the mobile phase is selected from a polar organic solvent or an aqueous solution thereof.

[0025] [6]. According to the method described in any one of [1] to [5], the stationary phase of the liquid chromatography comprises silica gel modified with a hydrophobic group, preferably, the hydrophobic group is a hydrocarbon group, more preferably a C18 group.

[0026] [7]. The method according to any one of [1] to [6], wherein the mobile phase of the liquid chromatography is selected from a polar organic solvent or an aqueous solution thereof.

[0027] [8] The method according to any one of [1] to [7], wherein the mobile phase used in the elution step is the same as the mobile phase of the liquid chromatography.

[0028] [9]. According to the method described in any one of [1] to [8], in the detection step, the organic metal compound separated by liquid chromatography is detected using a detector, and the detector is selected from the group consisting of an ultraviolet-visible light detector, an ultraviolet detector, a fluorescence detector and a mass spectrometer detector; preferably, the detector is a mass spectrometer detector.

[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] In some embodiments, the method for detecting organic metal compounds in aqueous samples provided by the present invention provides an analytical method for organic metal compounds such as tetraethyl lead in aqueous samples using online solid phase extraction-liquid chromatography-inductively coupled plasma mass spectrometry. After testing, the detection limit of the organic metal compounds in the sample provided by the method of the present invention can reach 0.3×10 -12 g / mL, which is better than the detection limit of the method in the prior art. It has the advantages of simplicity, rapidity and sensitivity, and can be used to monitor organometallic compounds such as tetraethyl lead in environmental water. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 The effect of different L-cysteine ​​concentrations on tetraethyl lead analysis.

[0034] Figure 2 The effect of different methanol ratios in the mobile phase on the retention time of tetraethyl lead.

[0035] Figure 3 This is the concentration curve of tetraethyl lead in water.

[0036] Figure 4 This is a spike recovery experiment of tetraethyl lead in tap water and seawater samples; SW-1 represents seawater sample 1; SW-2 represents seawater sample 2; tap water represents tap water. 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" includes 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] Unless otherwise stated, “%” refers to volume percentage, i.e. “V%”.

[0044] The present invention provides a method for detecting an organometallic compound in an aqueous sample, comprising:

[0045] an enrichment step, using a hydrophobic solid phase extraction column treated with a chelating agent to enrich the metal-containing components in the aqueous sample, so that the metal-containing components in the aqueous sample are retained in the solid phase extraction column, wherein the chelating agent includes a thiol-containing chelating agent;

[0046] an elution step, eluting the metal-containing components retained in the solid phase extraction column from the solid phase extraction column;

[0047] A separation step of separating the metal-containing components eluted from the solid phase extraction column by liquid chromatography to separate the organometallic compound;

[0048] The detection step is to detect the organic metal compound separated by liquid chromatography.

[0049] The organometallic compound includes a lead-containing organometallic compound.

[0050] The method for detecting organometallic compounds in aqueous samples provided by the present invention is also referred to as SPE-LC-ICPMS analysis method in this specification.

[0051] <Enrichment Steps>

[0052] Aqueous samples

[0053] 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 (also referred to as an environmental water sample). 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 a surface water environment and a groundwater environment, wherein the surface water environment includes rivers, lakes, oceans, glaciers, etc., and the groundwater environment includes shallow and deep groundwater and springs. 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.

[0054] Preprocessing

[0055] For the above-mentioned aqueous sample, before using a hydrophobic solid phase extraction column treated with a chelating agent to enrich the metal-containing components in the aqueous sample, in some embodiments, an optional pretreatment may or may not be performed. In some embodiments, before using a hydrophobic solid phase extraction column treated with a chelating agent to enrich the metal-containing components 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 viewpoint of extending the service life of the solid phase extraction column and avoiding blockage of the solid phase extraction column affecting the detection efficiency, it is preferred to perform a pretreatment for the purpose of removing particulate matter (such as mud, etc.) in the aqueous sample.

[0056] In some specific embodiments, the pretreatment can be filtration. In some more specific embodiments, the aqueous sample can be filtered using a 0.22 μm filter membrane.

[0057] Metal-containing components

[0058] In the present invention, the metal-containing component refers to any physical-chemical form of metal elements existing in the environment (eg, water environment, aqueous sample) in the form of ions, molecules or other combinations thereof.

[0059] In some embodiments, the metal-containing component comprises an organometallic compound. An organometallic compound refers to an organic compound formed by a metal atom directly bonded to a carbon atom; or, refers to a class of compounds in which a carbon atom of an organic group is directly bonded to a metal.

[0060] In some embodiments, the organometallic compound is an organometallic compound formed by direct bonding between a heavy metal atom and a carbon atom.

[0061] 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 mercury, lead and cadmium can cause environmental pollution.

[0062] In some embodiments, the method of analyzing an organometallic compound in an aqueous sample of the present invention can detect an organometallic compound containing heavy metals Pb, Cd, Cr, Hg, As, Fe, Cu and / or Zn.

[0063] In some embodiments, the method of analyzing an organometallic compound in an aqueous sample of the present invention can detect an organometallic compound containing a methyl group, an ethyl group, a propyl group, a butyl group, and the like.

[0064] In some more preferred embodiments, the organometallic compound detectable by the method of analyzing the organometallic compound in an aqueous sample of the present invention includes a lead-containing organometallic compound, for example, tetraethyl lead.

[0065] Chelating agents

[0066] 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.

[0067] Considering the adsorption efficiency of metal-containing components in the enrichment step in cooperation with the solid phase extraction column, especially the solid phase extraction column with C18 modified silica gel particles as 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.

[0068] The amount of the chelating agent used can be determined according to the parameters of the solid phase extraction column used (e.g., inner diameter, column length, etc.). In some exemplary embodiments, for a solid phase extraction column with an inner diameter × column length of 4.6 × 10 mm, the loading amount of the chelating agent in the solid phase extraction column can be about 12.5 μg.

[0069] In the present invention, the method of treating the solid phase extraction column with a chelating agent is not particularly limited. For example, the chelating agent can be loaded into the solid phase extraction column using a carrier liquid.

[0070] Preferably, the carrier fluid is water.

[0071] Solid Phase Extraction Column

[0072] The metal-containing components in the aqueous sample are enriched using a hydrophobic solid phase extraction column treated with a chelating agent. The specific operation includes: using a carrier liquid to load the aqueous sample into the hydrophobic solid phase extraction column treated with a chelating agent.

[0073] Preferably, the carrier fluid is water.

[0074] Preferably, the flow rate of the carrier liquid is 0.1 to 15 mL / min, preferably 1 to 15 mL / min, 3 to 15 mL / min, 5 to 15 mL / min, 5 to 13 mL / min, 5 to 10 mL / min, for example 5, 6, 7, 8, 9 or 10 mL / min;

[0075] Preferably, the flow rate of the carrier liquid is 9 mL / min.

[0076] The metal-containing components in the aqueous sample are captured using a solid phase extraction column, while other substances contained in the aqueous sample, such as inorganic non-metallic substances, non-metallic organic substances, etc., are eluted and removed along with the carrier liquid.

[0077] In some specific embodiments, the aqueous sample loading volume is 0.05-20 mL, preferably 1-20 mL, 1-18 mL, 1-15 mL, 1-10 mL, 3-10 mL, such as 3, 4, 5, 6, 7, 8, 9 or 10 mL. More preferably, the loading volume is 5 mL.

[0078] In the present invention, the solid phase extraction column can be used as long as it can remove other substances and enrich the metal-containing components as the detection target. Commercially available solid phase extraction columns can be selected and used according to the aqueous sample as the detection object and the metal-containing components as the detection target. Other substances here include inorganic non-metallic substances, non-metallic organic substances, etc. that cannot be completely removed by pretreatment.

[0079] As an example of a solid phase extraction column, the adsorption filler (stationary phase) in the solid phase extraction column can be silica gel particles modified with hydrophobic groups, and the hydrophobic groups can be various hydrocarbon groups, such as C4 groups, 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.

[0080] The particle size of the adsorption filler can be 2 μm to 100 μm. If the particle size of the filler is too small, the pores in the solid phase extraction column are easily clogged, and the solid phase extraction column needs to be frequently rinsed or replaced, thereby reducing the analysis efficiency and increasing the analysis cost. On the other hand, if the particle size of the adsorption filler is too large, the efficiency of the solid phase extraction column is reduced, it is difficult to fully capture the metal-containing components, and sometimes the accuracy of the detection results cannot be ensured. From the perspective of cost-effectiveness, it is preferably 5 μm to 20 μm, more preferably 5 μm to 10 μm, for example 5, 6, 7, 8, 9 or 10 μm.

[0081] The model and size of the solid phase extraction column used in the step of enriching the metal-containing components in the aqueous sample using a hydrophobic solid phase extraction column treated with a chelating agent, the temperature of the column oven, the flow rate and circulation time of the carrier liquid, etc., can be appropriately selected and set to ensure stable working conditions of the solid phase extraction used within a range that does not significantly hinder the capture of the metal-containing components and the removal of other substances such as inorganic non-metals and non-metallic organic matter.

[0082] The flow rate of the carrier liquid in the solid phase extraction column can be, for example, 0.1 to 15 mL / min. As described in the above description of the particle size of the filler, in some preferred embodiments, from the perspective of extending the service life of the solid phase extraction column to reduce the cleaning and replacement frequency of the solid phase extraction column, and effectively cooperating with a chelating agent to improve the adsorption efficiency of metal-containing components, a solid phase extraction column with a filler particle size of 5 μm to 10 μm can be particularly preferably used. When such a solid phase extraction column is used, the flow rate of the carrier liquid is preferably set to 5 to 10 mL / min from the perspective of increasing the speed of the pretreatment and preventing the column pressure from being too high, and improving the adsorption efficiency of the metal-containing components in combination with the chelating agent.

[0083] <Elution Step>

[0084] In the present invention, the metal-containing component retained in the solid phase extraction column may be eluted from the solid phase extraction column using a mobile phase.

[0085] In some embodiments of the present invention, a polar organic solvent or an aqueous solution thereof, such as an alcohol and / or an amino acid, may be used as a mobile phase. For alcohols, methanol and the like may be used; for amino acids, L-cysteine ​​and the like may be used. In some embodiments, the mobile phase may be used in the form of an aqueous solution, for example, an aqueous solution of methanol and / or L-cysteine ​​may be used.

[0086] When a methanol aqueous solution is used as the mobile phase, the content of methanol in the mobile phase should be 1% or more, preferably 3% or more, more preferably 5% or more, for example 5% or 10%.

[0087] When an aqueous solution of L-cysteine ​​is used as the mobile phase, the content of L-cysteine ​​in the mobile phase should be 0.50% or less, preferably 0.30% or less, more preferably 0.2% or less, for example 0.15% or 0.10%.

[0088] In some preferred embodiments of the present invention, the mobile phase contains more than 1% methanol and less than 0.50% L-cysteine. In some more preferred embodiments, the mobile phase contains more than 5% methanol and less than 0.20% L-cysteine. In some specific embodiments, the mobile phase contains 10% methanol and 0.10% L-cysteine.

[0089] <Separation steps>

[0090] In the separation step, the metal-containing components eluted from the solid phase extraction column are introduced into a liquid chromatography column along with a mobile phase and separated by liquid chromatography to separate the organic metal compound. As an example of a liquid chromatography column used in liquid chromatography, the stationary phase is selected from silica gel modified with a hydrophobic group, wherein the hydrophobic group is selected from a hydrocarbon group, preferably a C4 group, a C8 group, a C18 group or a phenyl group, and more preferably a C18 group, and the modified silica gel is preferably a C18-modified silica gel (e.g., silica gel particles).

[0091] In some embodiments of the present invention, a polar organic solvent or an aqueous solution thereof, such as an alcohol and / or an amino acid, may be used as a mobile phase. For alcohols, methanol and the like may be used; for amino acids, L-cysteine ​​and the like may be used. In some embodiments, the mobile phase may be used in the form of an aqueous solution, for example, an aqueous solution of methanol and / or L-cysteine ​​may be used.

[0092] When a methanol aqueous solution is used as the mobile phase, the methanol content in the mobile phase should be 1% or more, preferably 3% or more, more preferably 5% or more, for example 5% or 10%, in view of peak shape and shortening retention time.

[0093] When an aqueous solution of L-cysteine ​​is used as the mobile phase, the content of L-cysteine ​​in the mobile phase should be 0.50% or less, preferably 0.30% or less, more preferably 0.2% or less, for example 0.15% or 0.10%, in view of peak shape, shortening retention time and cost.

[0094] In some preferred embodiments of the present invention, the mobile phase contains more than 1% methanol and less than 0.50% L-cysteine. In some more preferred embodiments, the mobile phase contains more than 5% methanol and less than 0.20% L-cysteine. In some specific embodiments, the mobile phase contains 10% methanol and 0.10% L-cysteine.

[0095] In some preferred embodiments, the mobile phase used in the elution step is the same as the mobile phase used in the separation step, which avoids interference caused by switching reagents and ensures accuracy, while also shortening the detection time and simplifying the detection steps.

[0096] The type and size of the liquid chromatography column used in the separation step, the temperature of the column oven, the flow rate of each mobile phase and the gradient program and other conditions can be appropriately selected to set the conditions under which the liquid chromatography system used works stably and the organic metal compound as the detection target, such as tetraethyl lead, can be effectively separated.

[0097] <Testing steps>

[0098] In the step of detection, the organometallic compound as the detection target eluted from the liquid chromatographic column is detected using a detector according to the time of elution. The detector is selected from the group consisting of a UV-visible light detector, a UV detector, a fluorescence detector and a mass spectrometer. For the consideration of improving the accuracy, linear range limit of quantification (LOQ) and limit of detection (LOD) of detection, a mass spectrometer is preferably used. In some more preferred embodiments, the mass spectrometer is a mass spectrometer with an inductively coupled plasma as an ion source. In some more preferred embodiments, the mass spectrometer is a quadrupole mass spectrometer. An exemplary mass spectrometer is an inductively coupled plasma mass spectrometer of ICPMS-2030 produced by Shimadzu.

[0099] Example

[0100] 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.

[0101] Measuring instruments

[0102] Solid phase enrichment column (Shim-pack VP-ODS, 4.6×10mm, 5μm)

[0103] Dithizone (Sigma-Aldrich)

[0104] L-Cysteine ​​(98%, Fisher)

[0105] Methanol (chromatographic grade, DIKMA)

[0106] Inductively coupled plasma mass spectrometer (Shimadzu ICPMS-2030).

[0107] The liquid chromatography system consists of a degassing unit (DGU-20A), a solution delivery unit (LC-20Ai), a column oven (CTO-20AC), and an automatic sampler (SIL-16P).

[0108] Pretreatment of environmental water samples

[0109] Take 5 mL of environmental water sample, filter it using a 0.22 μm filter membrane, and then test it.

[0110] Pretreatment of solid phase extraction columns

[0111] Automatic operation, 2-6mL / min, 1-3 minutes.

[0112] Example: Determination of Tetraethyl Lead in Environmental Water Samples

[0113] Tetraethyl lead is determined using an online SPE-LC-ICPMS analysis method. Environmental water samples are enriched and purified through a first-dimensional solid-phase extraction (SPE) enrichment column (i.e., a solid phase extraction column pretreated with dithizone), and then the lead component (i.e., the component containing metallic lead) is eluted from the first-dimensional SPE column by a mobile phase through valve switching, and then enters the second-dimensional liquid phase analytical column (i.e., liquid chromatography column). Different forms of lead (e.g., tetraethyl lead) are separated in turn on the analytical column according to their different properties, and directly introduced into ICP-MS for detection. Retention time is used for qualitative analysis, and external standard method is used for quantitative analysis.

[0114] Results and Discussion

[0115] 1. Effect of different mobile phase compositions on tetraethyl lead analysis

[0116] The effects of three concentrations (0.10%, 0.15%, 0.20%) of aqueous L-cysteine ​​on the analysis of tetraethyl lead were investigated. Figure 1From the analysis results, it can be seen that the change of L-cysteine ​​concentration in the mobile phase does not affect the retention time of tetraethyl lead. Under the three experimental conditions, the retention time of tetraethyl lead is 16.8min. Therefore, 0.10% L-cysteine ​​is selected as the mobile phase composition.

[0117] The effect of methanol ratio (0%, 5%, 10%) in the mobile phase on the analysis of tetraethyl lead was investigated. Figure 2 As shown. When no methanol is introduced during the analysis, the retention time of tetraethyl lead is 40 minutes; when the proportion of methanol in the mobile phase is 5%, the retention time of tetraethyl lead is reduced to 25 minutes; further increasing the proportion of methanol to 10%, the retention time of tetraethyl lead is reduced to 16.5 minutes. Considering the peak shape and analysis time, 10% methanol is used in the mobile phase for analysis.

[0118] In subsequent experiments, the mobile phase used contained both 0.10% L-cysteine ​​and 10% methanol.

[0119] 2. Detection limit of analytical method

[0120] Take 5 mL of pure water and add about 2.5×10 -12 g tetraethyl lead, so that the concentration of tetraethyl lead in the final solution is 0.5×10 -12 g / mL. The tetraethyl lead content in the solution was determined using the SPE-LC-ICPMS analysis method. Six parallel samples were prepared and the detection limit of the analysis method was calculated. Using the external standard method, the detection limit of tetraethyl lead in the sample was 0.3×10 -12 g / mL.

[0121] 3. Linear range of analytical method

[0122] Using this analytical method, the concentration range of tetraethyl lead was 0.5×10 -12 g / mL-1×10 -11 The standard solution of 100 g / mL was analyzed. The results showed that within the lower concentration range, the signal of tetraethyl lead had a good linear relationship with the concentration. The linear correlation coefficient R 2 is 0.9995.

[0123] 4. Actual sample analysis and spike recovery

[0124] The tetraethyl lead content in tap water and seawater samples (SW-1 and SW-2) was analyzed using the established tetraethyl lead analysis method. No tetraethyl lead was detected, indicating that the tetraethyl lead concentration in the measured samples was less than the detection limit of the analysis method (0.3×10 -12g / mL). The above environmental water samples were subjected to spike recovery experiments, and the spike concentration of tetraethyl lead was 1×10 -11 g / mL, the analysis results are as follows Figure 4 The spiked recovery rates of tap water and seawater samples were 95%-105%, indicating that the analytical method for tetraethyl lead in environmental water bodies established in this study is accurate and reliable and can be used for routine monitoring of tetraethyl lead in environmental water bodies.

[0125] in conclusion

[0126] An analytical method for tetraethyl lead in environmental water was established using online solid phase extraction-liquid chromatography-inductively coupled plasma mass spectrometry. Using 5 mL of environmental water sample, the detection limit of tetraethyl lead in the sample was 0.3×10 - 12 g / mL, which is better than the analytical results reported in the literature (1×10 -11 g / mL). It has the advantages of simplicity, rapidity and sensitivity, and can be used for routine monitoring of tetraethyl lead in environmental water.

[0127] 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.

[0128] 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 organometallic compounds in aqueous samples, characterized in that: The method comprises: an enrichment step, using a hydrophobic solid phase extraction column treated with a chelating agent to enrich the metal-containing components in the aqueous sample, so that the metal-containing components in the aqueous sample are retained in the solid phase extraction column, wherein the chelating agent includes a thiol-containing chelating agent; an elution step, eluting the metal-containing components retained in the solid phase extraction column from the solid phase extraction column; A separation step of separating the metal-containing components eluted from the solid phase extraction column by liquid chromatography to separate the organometallic compound; The detection step is to detect the organic metal compound separated by liquid chromatography. The organometallic compound includes a lead-containing organometallic compound.

2. The method according to claim 1, characterized in that The adsorption filler in the hydrophobic solid phase extraction column 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 thiol-containing chelating agent is dithizone.

5. The method according to any one of claims 1 to 4, characterized in that: In the elution step, a mobile phase is used to elute the metal-containing components retained in the hydrophobic solid phase extraction column from the hydrophobic solid phase extraction column; the mobile phase is selected from a polar organic solvent or an aqueous solution thereof.

6. The method according to any one of claims 1 to 5, characterized in that: The stationary phase of the liquid chromatography comprises silica gel modified with hydrophobic groups.

7. The method according to any one of claims 1 to 6, characterized in that: The mobile phase of the liquid chromatography is selected from a polar organic solvent or an aqueous solution thereof.

8. The method according to any one of claims 1 to 7, characterized in that: The mobile phase used in the elution step is the same as the mobile phase of the liquid chromatography.

9. The method according to any one of claims 1 to 8, characterized in that: In the detection step, the organic metal compound separated by liquid chromatography is detected using a detector, and the detector is selected from the group consisting of an ultraviolet-visible light detector, an ultraviolet detector, a fluorescence detector and a mass spectrometry detector.

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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