Non-target screening solid-phase extraction system and screening method

Abstract

The invention discloses a non-target screening solid-phase extraction system and a screening method, and belongs to the technical field of pollutant treatment, the system comprises a plurality of solid-phase extraction columns which are arranged in a cross series connection manner and a pH adjusting device; the pH adjusting device is used for adjusting the pH value of the inflowing water sample; the pH values adjusted by the plurality of pH adjusting devices are different; the types of the plurality of solid-phase extraction columns are different or the same. The method can meet the requirement of non-target detection and has the advantages of being good in enrichment effect, high in enrichment efficiency, efficient in activation and elution and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of pollutant treatment, relates to a new pollutant enrichment device, and in particular to a non-target screening solid phase extraction system and a screening method. Background Art

[0002] New pollutants mainly include persistent organic pollutants, endocrine disruptors, antibiotics, etc. that are controlled by international conventions. The production and use of toxic and harmful chemical substances are the main sources of new pollutants. The reason why new pollutants are called "new" is that, on the one hand, they are relative to conventional pollutants such as ammonia nitrogen and chemical oxygen demand; on the other hand, there are many types of new pollutants, and the number of new pollutants that can be identified will continue to increase. New pollutants refer to toxic and harmful chemical substances that are discharged into the environment, have characteristics such as biological toxicity, environmental persistence, and bioaccumulation, and pose a great risk to the ecological environment or human health, but have not yet been included in the management or the existing management measures are insufficient. There are many types of new pollutants. At present, my country divides them into four categories: persistent organic pollutants, endocrine disruptors, antibiotics, and microplastics. There are also many (even large) substances in each major category, and even the substances in each major category have very different properties. In terms of nature, the most concerned new pollutants in water are mainly semi-volatile and difficult-to-volatile organic compounds.

[0003] Regarding the monitoring of new pollutants and the development of methods, although there are various methods, in general, a considerable number of new pollutants need to be enriched because of their very low concentrations (ng / L level). Generally, solid phase extraction enrichment or liquid-liquid extraction is used. Among them, solid phase extraction enrichment is the main method. However, solid phase extraction is also selective, and each solid phase extraction column is suitable for a certain type of substance; under different pH conditions, the substance may have different forms in water, and the enrichment efficiency on the solid phase extraction column varies significantly. In summary, when faced with non-target screening (uncertainty about what the new pollutant is, "sea selection" testing), how to try not to "lose" new pollutants during sampling or enrichment is a difficult problem. Summary of the invention

[0004] The present invention provides a non-target screening solid phase extraction system and a screening method to overcome the defects of the prior art.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A non-target screening solid phase extraction system comprises a plurality of cross-connected solid phase extraction columns and a pH adjusting device, with the end being a solid phase extraction column; the pH adjusting device is used to adjust the pH value of an influent water sample; the pH values ​​adjusted by the plurality of pH adjusting devices are different; and the types of the plurality of solid phase extraction columns are different or the same.

[0007] To optimize the above technical solutions, the specific measures taken also include:

[0008] Furthermore, the number of the solid phase extraction columns is three, and the number of the pH adjusting devices is two; the three solid phase extraction columns are of different types, and according to the direction of water sample flow, they are solid phase extraction columns for extracting neutral, acidic and alkaline water samples respectively; the pH adjusting devices are pH adjusting devices for adjusting the water samples to acidic and alkaline respectively according to the direction of water sample flow.

[0009] Furthermore, the solid phase extraction column for neutral water sample extraction is a solid phase extraction column with an enrichment rate of more than 85% for non-polar and weakly polar new pollutants in water samples under neutral conditions, preferably an HLB solid phase extraction column; the solid phase extraction columns for acidic and alkaline water sample extraction are cation exchange solid phase extraction columns and anion exchange solid phase extraction columns, respectively, the cation exchange solid phase extraction column is preferably a WCX or PCX solid phase extraction column, and the anion exchange solid phase extraction column is preferably a WAX or PAX solid phase extraction column.

[0010] Furthermore, the number of the solid phase extraction columns is three, and the number of the pH adjusting devices is two; the three solid phase extraction columns are of the same type, all of which are HLB solid phase extraction columns; the pH adjusting devices are used to adjust the water sample to acidic and alkaline respectively according to the flow direction of the water sample.

[0011] Furthermore, the pH adjusting device includes a mixing ball, a jet tube and a pH adjusting liquid injector; the mixing ball is a spherical container, the upper end of which is connected to the outlet of the previous solid phase extraction column, and the lower end is connected to the inlet of the next solid phase extraction column; the material of the mixing ball is preferably polypropylene (PP); the upper end of the jet tube is connected to the pH adjusting liquid injector, and the lower end is conical and connected to the upper end of the mixing ball; the pH adjusting liquid injector contains pH adjusting liquid and provides a pressure difference, and injects the pH adjusting liquid into the mixing ball in a jet manner through the jet tube; the pH adjusting liquid is an acid solution such as sulfuric acid and hydrochloric acid or an alkaline solution such as sodium hydroxide, which is used to adjust the pH of the water sample in the mixing ball; a one-way valve is provided at the top of the mixing ball.

[0012] Furthermore, the pH regulating liquid filler is a filling chamber; the height of the filling chamber is smaller than its width, and the position is higher than the mixing ball; and a switch valve is provided on the jet tube.

[0013] Furthermore, the pH adjusting liquid injector includes a liquid reservoir and a liquid injection pump; the liquid reservoir is used to contain the pH adjusting liquid; the liquid reservoir is connected to the liquid injection pump through a pipeline, and the liquid injection pump is connected to the upper end of the mixing ball through a pipeline.

[0014] Furthermore, a flow controller and a pump are provided at the outlet of the solid phase extraction column at the end.

[0015] The present invention also provides a non-target screening method, which utilizes the non-target screening solid phase extraction system as described above to screen new pollutants in water samples.

[0016] Furthermore, each solid phase extraction column is activated separately, and then multiple solid phase extraction columns and pH adjustment devices are cross-connected in series; then water samples are added for enrichment; after the enrichment is completed, each solid phase extraction column is disassembled and eluted separately, and multiple final samples are obtained through subsequent treatment (generally concentration and volume adjustment); finally, the multiple final samples are qualitatively and quantitatively analyzed respectively, and finally the types of new pollutants in the water samples and the content of each substance are obtained.

[0017] The beneficial effects of the present invention are:

[0018] 1. Ability to meet non-target detection needs. Traditional methods are generally targeted for targeted detection, so the solid phase extraction method applicable to the target is basically determined, that is, using a certain solid phase extraction column, enriching under certain fixed pH and other conditions, with obvious "selectivity", while the present invention can meet the detection needs under non-target conditions.

[0019] Specifically, the present invention adjusts the pH value in an enrichment process to change the form of new pollutants, so that new pollutants of different categories are in a form that is relatively easy to enrich, thereby greatly improving the effect and efficiency; at the same time, the solid phase extraction column of the present invention can be disassembled for activation and elution respectively, which can ensure efficient activation and efficient elution, so that the solid phase extraction method has a high comprehensive recovery rate (enrichment efficiency×elution efficiency); and, since each solid phase extraction column is eluted according to its optimal conditions and concentrated as appropriate, its final solvent is also conducive to the dissolution, uniformity and preservation of the target object, so as to ensure the reliability of the on-machine analysis results;

[0020] Second, the enrichment of new pollutants can be completed in one operation, rather than in multiple or multiple ways. The concentration of new pollutants is low, so the enrichment multiple is very large. Sometimes it is necessary to enrich more than 10L of water sample. In this case, the single enrichment time may even exceed 10 hours. The present invention can achieve the best effect in terms of efficiency and cost.

[0021] 3. The present invention can enrich the collected water samples in the laboratory, and can also enrich the water samples in situ on site. When a large volume (>5L) is required for enrichment, it is troublesome to collect water samples with a large container that meets the requirements. In this case, in situ enrichment has a greater advantage, and the present invention can achieve in situ enrichment of water samples. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the structure of the non-target screening solid phase extraction system;

[0023] Figure 2 It is a schematic diagram of the structure of a portion of the pH adjusting liquid injector;

[0024] Figure 3 It is a schematic diagram of the structure of a non-target screening solid phase extraction system (another pH adjustment liquid injector). DETAILED DESCRIPTION

[0025] The specific implementation of the present invention is described below with reference to the accompanying drawings.

[0026] like Figure 1 As shown, the present invention provides a non-target screening solid phase extraction system, comprising a plurality of cross-connected solid phase extraction columns 1 and pH adjustment devices 2, and the end is a solid phase extraction column 1. The pH adjustment device 2 is used to adjust the pH value of the inflowing water sample, and the pH adjusted by the multiple pH adjustment devices 2 is different. The types of the multiple solid phase extraction columns 1 are different or the same.

[0027] Different types of solid phase extraction columns 1 are connected in series, and a pH adjustment device is added between each solid phase extraction column 1, so that the semi-volatile and non-volatile organic compounds in the water can be enriched as "non-destructively" as possible in one enrichment (or sampling). Alternatively, multiple solid phase extraction columns 1 can also be of the same type, because some substances present different forms (such as ionic state and molecular state) at different pH values, and the adsorption efficiency of different forms under the same solid phase extraction filler is different, that is, the recovery rate of certain substances using the same solid phase extraction column 1 at different pH values ​​is different, so such substances can be enriched by multiple solid phase extraction columns 1 of the same type.

[0028] Specifically, Figure 1 and Figure 2 As shown, the pH adjusting device 2 includes a mixing ball 21, a jet tube 22 and a pH adjusting liquid injector. The mixing ball 21 is a spherical container, the upper end of which is connected to the outlet of the previous solid phase extraction column 1, and the lower end is connected to the inlet of the next solid phase extraction column 1. The material of the mixing ball 21 is preferably polypropylene (PP). The upper end of the jet tube 22 is connected to the pH adjusting liquid injector, and the lower end is conical and connected to the upper end of the mixing ball 21. Preferably, the inner diameter of the jet tube 22 gradually shrinks from 2mm to 0.5mm. The pH adjusting liquid injector contains pH adjusting liquid and provides a pressure difference, and injects the pH adjusting liquid into the mixing ball 21 in a jet manner through the jet tube 22. The pH adjusting liquid is an acid solution such as sulfuric acid and hydrochloric acid or an alkaline solution such as sodium hydroxide, which is used to adjust the pH of the water sample in the mixing ball 21. The mixing ball 21 can fully mix the water sample with the ejected pH adjusting liquid.

[0029] A one-way valve 211 is provided at the top of the mixing ball 21 to discharge the gas that may be generated during the acid-base adjustment process. The salts generated after the acid-base combination are generally water-soluble and will enter the next solid phase extraction column 1 along with the water sample, without adversely affecting the enrichment (more likely to be beneficial to the enrichment). Even if a small amount of crystals are precipitated, they will be above the upper sieve plate of the solid phase extraction column 1 and will not cause blockage.

[0030] like Figure 1 As shown, more specifically, the pH adjusting liquid filler is a filling chamber 23. The height of the filling chamber 23 is less than its width, and is used to hold the pH adjusting liquid, and the position of the filling chamber 23 is higher than the mixing ball 21. The filling chamber 23 is designed with a wide liquid surface, and the size of the vertical direction 211 is small, which makes the liquid level of the pH adjusting liquid and the height of the mixing ball 21 change very little during the filling process. At the same time, its horizontal position is higher than the corresponding mixing ball 21, and the height difference is fixed, so that there is a relatively fixed pressure difference during a long enrichment time, so that the pH adjusting liquid can flow into the mixing ball 21 at a fixed flow rate, especially when the water sample collection flow rate is constant. At the same time, the jet tube 22 adopts a reduced diameter jet design, so that the pH adjusting liquid can "rush" into the mixing ball 21 at a higher linear velocity, which is conducive to rapid mixing. A switch valve 221 is provided on the jet tube 22.

[0031] Of course, the pH adjusting liquid injector can also be composed of a liquid reservoir and an injection pump. The liquid reservoir is used to hold the pH adjusting liquid. The liquid reservoir is connected to the injection pump through a pipeline, and the injection pump is connected to the upper end of the mixing ball through a pipeline. The injection pump can be a peristaltic pump, etc. Alternatively, the pH adjusting liquid injector can also be directly a syringe pump 24, such as Figure 3 As shown. At this time, there is no switch valve on the jet tube. However, compared with adding pH adjusting liquid by a pump, the pH adjusting liquid injector composed of the injection chamber 23 and the jet tube 22 has low cost, simpler structure, and does not require power (electricity) supply.

[0032] A flow controller and a pump 3 are provided at the outlet of the solid phase extraction column 1 at the end for controlling the flow rate so that the water sample passes through the system at a constant flow rate. Preferably, the flow rate control range is 2 to 20 mL / min.

[0033] In a preferred embodiment, the number of solid phase extraction columns 1 is three, and the number of pH adjustment devices 2 is two. The three solid phase extraction columns 1 are of different types, and are solid phase extraction columns 1 for neutral, acidic, and alkaline water sample extraction, respectively, according to the direction of water sample flow. The pH adjustment devices 2 are pH adjustment devices 2 for adjusting water samples to acidic and alkaline, respectively, according to the direction of water sample flow. That is, the solid phase extraction column 1 for neutral water sample extraction, the pH adjustment device 2 for adjusting water samples to acidic, the solid phase extraction column 1 for acidic water sample extraction, the pH adjustment device 2 for adjusting water samples to alkaline, and the solid phase extraction column 1 for alkaline water sample extraction are connected in sequence.

[0034] The solid phase extraction column 1 for neutral water sample extraction is a solid phase extraction column 1 with an enrichment rate of more than 85% for non-polar and weakly polar new pollutants in water samples under neutral conditions, preferably an HLB solid phase extraction column. The solid phase extraction columns 1 for acidic and alkaline water sample extraction are respectively a cation exchange solid phase extraction column 1 and an anion exchange solid phase extraction column 1, the cation exchange solid phase extraction column 1 is preferably a WCX or PCX solid phase extraction column, and the anion exchange solid phase extraction column 1 is preferably a WAX or PAX solid phase extraction column.

[0035] In another preferred embodiment, the number of solid phase extraction columns 1 is three, and the number of pH adjusting devices 2 is two. The three solid phase extraction columns 1 are of the same type, all of which are HLB solid phase extraction columns. Adjusting the pH value can efficiently enrich weakly alkaline and weakly acidic new pollutants in the water sample. The pH adjusting devices 2 are pH adjusting devices 2 for adjusting the water sample to acidity and alkalinity in the direction of the water sample flow. That is, the HLB solid phase extraction column, the pH adjusting device 2 for adjusting the water sample to acidity, the HLB solid phase extraction column, the pH adjusting device 2 for adjusting the water sample to alkalinity, and the HLB solid phase extraction column are connected in sequence.

[0036] The present invention also provides a method for non-target screening of new pollutants in water samples using the above-mentioned non-target screening solid phase extraction system: first, activate each solid phase extraction column separately, and then cross-connect multiple solid phase extraction columns and pH adjustment devices in series; then add water samples for enrichment; after the enrichment is completed, disassemble each solid phase extraction column 1 and elute them separately to obtain multiple final samples; finally, perform qualitative and quantitative analysis on the multiple final samples, and finally obtain the type and content of the new pollutants in the water sample.

[0037] In a specific embodiment, the system includes an HLB solid phase extraction column, an acidic pH adjustment device, a PCX solid phase extraction column, an alkaline pH adjustment device and a PAX solid phase extraction column connected in sequence according to the flow direction of the water sample. After being activated separately, they are installed for enrichment. The acid solution and the alkaline solution in the pH adjustment device are both 5 mol / L, the flow meter sets the flow rate to 5 mL / min, the acid solution filling rate is 0.1 mL / min, and the alkaline solution is 0.2 mL / min. The neutral water sample passes through the HLB solid phase extraction column at 4.7 mL / min, the water sample with pH = 1 passes through the PCX solid phase extraction column at 4.8 mL / min, and the water sample with pH = 14 passes through the PAX solid phase extraction column at 5 mL / min. The pH is adjusted by changing the concentration of the acid solution and the alkaline solution, and of course, it can also be adjusted by changing the relative height between the filling chamber and the mixing ball. Through the HLB solid phase extraction column, non-polar and weakly polar new pollutants in the water sample are enriched, such as organophosphates and neonicotinoid pesticides, among which the enrichment efficiency of ionic types may not be good enough; then the water sample flows into the PCX solid phase extraction column, and alkaline organic matter (including those that are not fully enriched by the HLB solid phase extraction column) is enriched, such as diazepam and its metabolites; the water sample flows into the PAX solid phase extraction column, and acidic organic matter (including those that are not fully enriched by the HLB solid phase extraction column) is enriched, such as long-chain perfluorocarboxylic acids and quinolone metabolites. HLB can be directly eluted with methanol; PCX can be eluted with 5% ammonia methanol; PAX can be eluted with 2% formic acid in ethyl acetate solution. After elution (or further concentration), the final sample is prepared and analyzed by instruments such as liquid chromatography-triple quadrupole mass spectrometry (or high-resolution mass spectrometry), gas chromatography-triple quadrupole mass spectrometry (or high-resolution mass spectrometry), qualitative and quantitative. When quantifying, the results of each sample of the same substance need to be summed.

[0038] In the present invention, unless otherwise specified, the scientific and technical terms used herein have the meanings commonly understood by those skilled in the art.

[0039] It should be noted that the terms such as "upper", "lower", "left", "right", "front", "back", etc. cited in the invention are only for the convenience of description and are not used to limit the scope of implementation of the present invention. Changes or adjustments in their relative relationships should be regarded as the scope of implementation of the present invention without substantially changing the technical content.

[0040] Finally, it should be noted that the above are only preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A non-target screening solid phase extraction system, characterized in that: It includes a plurality of cross-connected solid phase extraction columns and a pH adjustment device; The pH adjusting device is used to adjust the pH value of the inflowing water sample; the pH values ​​adjusted by the multiple pH adjusting devices are different; The multiple solid phase extraction columns may be of different or the same type.

2. The non-target screening solid phase extraction system according to claim 1, characterized in that: The number of the solid phase extraction columns is three, and the number of the pH adjustment devices is two; The three solid phase extraction columns are of different types, and are respectively used for neutral, acidic and alkaline water sample extraction according to the direction of water sample flow; The pH adjusting devices are respectively used to adjust the water sample to acidic and alkaline according to the flow direction of the water sample.

3. The non-target screening solid phase extraction system according to claim 2, characterized in that: The solid phase extraction column for neutral water sample extraction is a solid phase extraction column with an enrichment rate of more than 85% for non-polar and weakly polar new pollutants in water samples under neutral conditions; The solid phase extraction columns used for acidic and alkaline water sample extraction are cation exchange solid phase extraction columns and anion exchange solid phase extraction columns, respectively.

4. The non-target screening solid phase extraction system according to claim 1, characterized in that: The number of the solid phase extraction columns is three, and the number of the pH adjustment devices is two; The three solid phase extraction columns are of the same type, all of which are HLB solid phase extraction columns; The pH adjusting devices are respectively used to adjust the water sample to acidic and alkaline according to the flow direction of the water sample.

5. The non-target screening solid phase extraction system according to claim 1, characterized in that: The pH adjusting device comprises a mixing ball, a jet tube and a pH adjusting liquid injector; The mixing ball is a spherical container, the upper end of which is connected to the outlet of the previous solid phase extraction column, and the lower end of which is connected to the inlet of the next solid phase extraction column; The upper end of the jet tube is connected to the pH adjusting liquid injector, and the lower end is conical and connected to the upper end of the mixing ball; The pH adjusting liquid injector contains the pH adjusting liquid and provides a pressure difference, and injects the pH adjusting liquid into the mixing ball in a jetting manner through the jetting tube; The pH adjusting liquid is an acid solution or an alkaline solution, which is used to adjust the pH of the water sample in the mixing ball; A one-way valve is provided at the top of the mixing ball.

6. The non-target screening solid phase extraction system according to claim 5, characterized in that: The pH regulating liquid filler is a filling chamber; The height of the filling cavity is smaller than its width and the position is higher than the mixing ball; The jet pipe is provided with a switch valve.

7. The non-target screening solid phase extraction system according to claim 5, characterized in that: The pH adjusting liquid injector comprises a liquid reservoir and a liquid injection pump; the liquid reservoir is used to contain the pH adjusting liquid; the liquid reservoir is connected to the liquid injection pump through a pipeline, and the liquid injection pump is connected to the upper end of the mixing ball through the pipeline.

8. The non-target screening solid phase extraction system according to claim 1, characterized in that: A flow controller and a pump are provided at the outlet of the solid phase extraction column at the end.

9. A non-target screening method, characterized in that: The non-target screening solid phase extraction system as described in any one of claims 1 to 8 is used to screen new pollutants in water samples.

10. The non-target screening method according to claim 9, characterized in that: First, each solid phase extraction column is activated separately, and then multiple solid phase extraction columns and pH adjustment devices are cross-connected in series; then water samples are added for enrichment; after the enrichment is completed, each solid phase extraction column is disassembled and eluted separately to obtain multiple final samples; finally, the multiple final samples are qualitatively and quantitatively analyzed respectively, and finally the types of new pollutants in the water samples and the content of each substance are obtained.

Images