A non-target screening solid phase extraction system and screening method

Abstract

The application 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 and pH adjusting devices which are cross-connected. The pH adjusting devices are used for adjusting the pH value of the flowing 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 application can meet the needs of non-target detection, and has the advantages of good enrichment effect, high enrichment efficiency, high activation and elution efficiency and the like.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of pollution control, and relates to a new pollutant enrichment device, in particular to a non-target screening solid-phase extraction system and a screening method. BACKGROUND

[0002] New pollutants mainly include persistent organic pollutants, endocrine disruptors, antibiotics and the like controlled by international conventions. The production and use of toxic and harmful chemical substances are the main sources of new pollutants. The new pollutants are called "new" on the one hand in relation to conventional pollutants such as ammonia nitrogen and chemical oxygen demand; on the other hand, the new pollutants are various, and the identifiable new pollutants will continue to increase. New pollutants refer to toxic and harmful chemical substances discharged into the environment, which have biological toxicity, environmental persistence, biological accumulation and the like, and have great risks to the ecological environment or human health, but have not been included in the management or the existing management measures are insufficient. New pollutants are various, and at present, they are divided into four categories in China: persistent organic pollutants, endocrine disruptors, antibiotics and microplastics, and there are many (even a large number) of substances in each category, and even the substances in each category have great differences in properties. In terms of properties, the most concerned new pollutants in water at present are mainly semi-volatile and non-volatile organic substances.

[0003] As for the monitoring and method research of new pollutants, although there are various methods, in general, a considerable part of new pollutants needs to be enriched because of very low concentration (ng / L level). Generally, solid-phase extraction enrichment or liquid-liquid extraction is adopted. Among them, solid-phase extraction enrichment is the most important way. However, solid-phase extraction also has selectivity, and each solid-phase extraction column is suitable for a certain type of substance; under different acidities, the form of the substance in water may be different, and the enrichment efficiency on the solid-phase extraction column is significantly different. In summary, in the face of non-target screening (not sure what new pollutants are, "open" detection), how to minimize the "loss" of new pollutants in the sampling or enrichment process is a difficult problem. SUMMARY

[0004] The application 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 application adopts the following technical scheme:

[0006] A non-target screening solid-phase extraction system comprises a plurality of solid-phase extraction columns and pH adjusting devices arranged in cross connection, and the last end is a solid-phase extraction column; the pH adjusting device is used for adjusting the pH value of the flowing water sample; the pH adjusting devices adjust different pH values; and the types of the solid-phase extraction columns are different or the same.

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

[0008] Further, 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 are sequentially arranged in the direction of water sample flow and used for extracting neutral, acidic and alkaline water samples; the pH adjusting devices are sequentially arranged in the direction of water sample flow and used for adjusting the water sample to be acidic and alkaline.

[0009] Further, the solid phase extraction column used for extracting neutral water sample is a solid phase extraction column with enrichment rate of non-polar and weakly polar new pollutants in water sample exceeding 85% under neutral conditions, and is preferably an HLB solid phase extraction column; the solid phase extraction columns used for extracting acidic and alkaline water samples are a cation exchange solid phase extraction column and an anion exchange solid phase extraction column, 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] Further, 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, and are all HLB solid phase extraction columns; the pH adjusting devices are sequentially arranged in the direction of water sample flow and used for adjusting the water sample to be acidic and alkaline.

[0011] Further, the pH adjusting device comprises a mixing ball, a flow injection tube and a pH adjusting liquid filler; the mixing ball is a spherical container, the upper end of which is connected with the outlet of the previous solid phase extraction column, and the lower end of which is connected with the inlet of the subsequent solid phase extraction column; the material of the mixing ball is preferably polypropylene (PP); the upper end of the flow injection tube is connected with the pH adjusting liquid filler, and the lower end thereof is tapered and connected with the upper end of the mixing ball; the pH adjusting liquid filler contains the pH adjusting liquid and provides a pressure difference, and the pH adjusting liquid is injected into the mixing ball in a flow injection manner through the flow injection tube; the pH adjusting liquid is an acid solution such as sulfuric acid or hydrochloric acid, or an alkali solution such as sodium hydroxide, and is used for adjusting the pH of the water sample in the mixing ball; the top end of the mixing ball is provided with a one-way valve.

[0012] Further, the pH adjusting liquid filler is a filling cavity; the height of the filling cavity is less than the width thereof, and the position of the filling cavity is higher than that of the mixing ball; a switch valve is arranged on the flow injection tube.

[0013] Further, the pH adjusting liquid filler comprises a liquid storage device and a liquid injection pump; the liquid storage device is used for containing the pH adjusting liquid; the liquid storage device is connected with the liquid injection pump through a pipeline, and the liquid injection pump is connected with the upper end of the mixing ball through a pipeline.

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

[0015] The application also provides a non-target screening method, which screens new pollutants in a water sample by using the non-target screening solid-phase extraction system.

[0016] Further, each solid-phase extraction column is activated respectively, and then the plurality of solid-phase extraction columns and the pH adjusting device are cross-connected in series; then the water sample is added for enrichment; after the enrichment is completed, each solid-phase extraction column is disassembled and eluted respectively, and after subsequent treatment (generally concentration and constant volume), a plurality of final samples are obtained; finally, qualitative and quantitative analysis is performed on the plurality of final samples respectively, and finally the types of new pollutants and the contents of each substance in the water sample are obtained.

[0017] The application has the following beneficial effects:

[0018] I. It can meet the needs of non-target detection. The traditional method is generally targeted detection, so the solid-phase extraction method for the target substance is basically determined, that is, a certain solid-phase extraction column is used to enrich under certain fixed pH and other conditions, which has obvious "selectivity", and the application can meet the detection needs under non-target conditions.

[0019] Specifically, the application adjusts the pH value in one enrichment process, changes the form of new pollutants, and makes different types of new pollutants in a relatively easy-to-enrich form, thereby greatly improving the effect and efficiency; at the same time, the solid-phase extraction column of the application can be disassembled for activation and elution respectively, which can ensure high-efficiency activation and high-efficiency elution, thereby making the solid-phase extraction method have high comprehensive recovery rate (enrichment efficiency x elution efficiency); and since each solid-phase extraction column is eluted according to its optimal conditions and is appropriately concentrated, the final solvent is also beneficial to the dissolution, uniformity and preservation of the target substance, so as to ensure the reliability of the analysis result.

[0020] II. The enrichment of new pollutants can be completed in one operation, rather than in multiple times or multiple ways. The concentration of new pollutants is low, so the enrichment multiple is large, and sometimes more than 10L of water sample needs to be enriched, which may take more than 10h for single enrichment, while the application can achieve the best effect in efficiency and cost.

[0021] III. The application can enrich the collected water sample in the laboratory, or enrich the water sample in situ. When a large volume (>5L) needs to be enriched, it is more troublesome to collect the water sample in a large and required container, and in this case, in-situ enrichment has great advantages, and the application can realize in-situ enrichment of the water sample. BRIEF DESCRIPTION OF DRAWINGS

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

[0023] Figure 2 is a structural schematic diagram of a part of a pH adjusting liquid filler;

[0024] Figure 3 is a structural diagram of a non-target screening solid phase extraction system (another pH adjusting liquid injector). DETAILED DESCRIPTION

[0025] The specific embodiments of the present application are described below in conjunction with the accompanying drawings.

[0026] As shown in Figure 1 , the present application provides a non-target screening solid phase extraction system, which comprises a plurality of solid phase extraction columns 1 and pH adjusting devices 2 arranged in cross connection, and the end is a solid phase extraction column 1. The pH adjusting devices 2 are used to adjust the pH of the flowing water sample, and the pH adjusted by the plurality of pH adjusting devices 2 is different. The types of the plurality of solid phase extraction columns 1 are different or the same.

[0027] The different types of solid phase extraction columns 1 are connected in series, and the device for adjusting the pH is added between each solid phase extraction column 1, so that the once enrichment (or sampling) can as much as possible "non-destructive" enrich the semi-volatile and difficult volatile organic matters in the water. Alternatively, the plurality of solid phase extraction columns 1 can also be of the same type, because some substances exhibit different forms (such as ionic state, molecular state) at different pH, and the adsorption efficiency of different forms under the same solid phase extraction filler is different, that is, the recovery rate of some substances is different at different pH using the same solid phase extraction column 1, so the plurality of solid phase extraction columns 1 of the same type can be used to enrich such substances.

[0028] Specifically, as shown in Figure 1 and Figure 2 , the pH adjusting device 2 comprises a mixing ball 21, a flow injection tube 22 and a pH adjusting liquid injector. The mixing ball 21 is a spherical container, the upper end of which is connected with the outlet of the previous solid phase extraction column 1, and the lower end of which is connected with 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 flow injection tube 22 is connected with the pH adjusting liquid injector, and the lower end thereof is tapered and connected with the upper end of the mixing ball 21. Preferably, the inner diameter of the flow injection tube 22 gradually decreases from 2 mm to 0.5 mm. The pH adjusting liquid injector contains a pH adjusting liquid and provides a pressure difference, and the pH adjusting liquid is injected into the mixing ball 21 in a flow injection manner through the flow injection tube 22. The pH adjusting liquid is an acid solution such as sulfuric acid or hydrochloric acid, or an alkali 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 make the water sample fully mixed with the flow-injected pH adjusting liquid.

[0029] The top end of the mixing ball 21 is provided with a one-way valve 211 for discharging the gas that may be generated during the acid-base adjustment process. The salt generated after the combination of acid and base generally has good water solubility, and will enter the next solid phase extraction column 1 with the water sample, which will not adversely affect the enrichment (more likely to be beneficial to the enrichment), and even if a small amount of crystals are precipitated, they will be above the sieve plate of the solid phase extraction column 1, which will not cause blockage.

[0030] As shown in Figure 1 , further specifically, the pH adjusting liquid filler is a filling cavity 23. The height of the filling cavity 23 is less than its width, which is used for containing the pH adjusting liquid, and the position of the filling cavity 23 is higher than the mixing ball 21. The filling cavity 23 is designed as a wide liquid surface, and the vertical direction 211 is small in size, which makes the liquid surface of the pH adjusting liquid change little in height during the filling process, and the horizontal position is higher than the corresponding mixing ball 21, and the height difference is fixed, so that the pressure difference is relatively fixed in a long enrichment time, so that the pH adjusting liquid can flow into the mixing ball 21 at a fixed flow rate, especially in the case of constant water sample collection flow rate. At the same time, the flow injection tube 22 adopts a reduced diameter flow injection design, so that the pH adjusting liquid can "rush" into the mixing ball 21 at a high linear velocity, which is beneficial to rapid mixing. The flow injection tube 22 is provided with an on-off valve 221.

[0031] Of course, the pH adjusting liquid filler can also be composed of a liquid reservoir and a liquid injection pump. The liquid reservoir is used for containing the pH adjusting liquid. The liquid reservoir is connected with the liquid injection pump through a pipeline, and the liquid injection pump is connected with the upper end of the mixing ball through a pipeline. The liquid injection pump can be a peristaltic pump or the like. Alternatively, the pH adjusting liquid filler can also be a syringe pump 24 directly, as shown in Figure 3 . At this time, no on-off valve is provided on the flow injection tube. However, compared with the pump adding the pH adjusting liquid, the pH adjusting liquid filler composed of the filling cavity 23 and the flow injection tube 22 has low cost, simple structure and no power (electricity) supply.

[0032] The outlet of the solid phase extraction column 1 at the end is provided with a flow controller and a pump 3 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 2-20 mL / min.

[0033] In a 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 different types, and are sequentially a solid phase extraction column 1 for neutral water sample extraction, a solid phase extraction column 1 for acidic water sample extraction and a solid phase extraction column 1 for alkaline water sample extraction. The pH adjusting devices 2 are sequentially a pH adjusting device 2 for adjusting the water sample to be acidic and a pH adjusting device 2 for adjusting the water sample to be alkaline. That is, the solid phase extraction column 1 for neutral water sample extraction, the pH adjusting device 2 for adjusting the water sample to be acidic, the solid phase extraction column 1 for acidic water sample extraction, the pH adjusting device 2 for adjusting the water sample to be alkaline and the solid phase extraction column 1 for alkaline water sample extraction are sequentially connected.

[0034] The solid phase extraction column 1 for neutral water sample extraction is a solid phase extraction column 1 with enrichment rate of more than 85% for non-polar and weakly polar new pollutants in water sample under neutral conditions, which is preferably an HLB solid phase extraction column. The solid phase extraction column 1 for acidic and alkaline water sample extraction is a cation exchange solid phase extraction column 1 and an anion exchange solid phase extraction column 1, respectively, and 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, and the adjustment of the acidity and alkalinity can make the water sample efficiently enriched with weakly basic and weakly acidic new pollutants. The pH adjusting devices 2 are, in order of water sample flow direction, pH adjusting devices 2 for adjusting the water sample to be acidic and alkaline. That is, the HLB solid phase extraction column, the pH adjusting device 2 for adjusting the water sample to be acidic, the HLB solid phase extraction column, the pH adjusting device 2 for adjusting the water sample to be alkaline, and the HLB solid phase extraction column are connected in sequence.

[0036] The present application also provides a method for non-target screening of new pollutants in water sample by using the above-mentioned non-target screening solid phase extraction system: first, activate each solid phase extraction column respectively, then cross-connect a plurality of solid phase extraction columns and pH adjusting devices in series; then add water sample for enrichment; after the enrichment is completed, disassemble each solid phase extraction column 1 and elute respectively to obtain a plurality of final samples; finally, qualitatively and quantitatively analyze the plurality of final samples respectively, and finally obtain the types and contents of new pollutants in the water sample.

[0037] In a specific embodiment, the system comprises an HLB solid phase extraction column, an acidic pH adjusting device, a PCX solid phase extraction column, an alkaline pH adjusting device and a PAX solid phase extraction column connected in sequence in the direction of water sample flow. After being activated respectively, the system is installed for enrichment. The acid solution and the base solution in the pH adjusting device are both 5 mol / L, the flow rate of the flow meter is set to 5 mL / min, the acid solution is added at a speed of 0.1 mL / min, and the base solution is added at a speed of 0.2 mL / min. The flow rate of the water sample through the HLB solid phase extraction column is 4.7 mL / min, the flow rate of the water sample with pH = 1 through the PCX solid phase extraction column is 4.8 mL / min, and the flow rate of the water sample with pH = 14 through the PAX solid phase extraction column is 5 mL / min. The pH can be adjusted by changing the concentration of the acid solution and the base solution, or by changing the relative height of the addition cavity 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 organophosphate esters and neonicotinoid pesticides. The enrichment efficiency of ion-type pollutants may not be good. Then the water sample flows into the PCX solid phase extraction column, and alkaline organic matter (including those not completely 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 not completely enriched by the HLB solid phase extraction column) is enriched, such as long-chain perfluorocarboxylic acids and olaquindox metabolites. The HLB can be directly eluted with methanol; the PCX can be eluted with 5% ammoniated methanol; and the 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 liquid chromatography-triple quadrupole mass spectrometry (or high-resolution mass spectrometry), gas chromatography-triple quadrupole mass spectrometry (or high-resolution mass spectrometry), etc. Qualitative and quantitative analysis is performed. When quantifying, the results of each sample of the same substance are added together for processing.

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

[0039] It should be noted that the terms such as "upper", "lower", "left", "right", "front", "back" and the like cited in the application are only for the convenience of clear description, and are not intended to limit the scope of the application. Changes or adjustments of the relative relationship without substantial changes in the technical content are also considered as the scope of the application.

[0040] Finally, it should be noted that the above is only a preferred embodiment of the present application and is not intended to limit the present application. Although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions recorded in the foregoing embodiments or make equivalent replacements of some technical features. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1.A non-target screening solid phase extraction system, characterized in that: it comprises a plurality of solid phase extraction columns and pH adjusting devices arranged in cross connection; the pH adjusting devices are used to adjust the pH of the flowing water sample; the pH adjusting devices are different in adjusting pH; the solid phase extraction columns are different in type; 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 different in type and arranged in the order of solid phase extraction columns for neutral, acidic and alkaline water samples; the two pH adjusting devices are arranged in the order of pH adjusting devices for adjusting the water sample to be acidic and alkaline; the solid phase extraction column for neutral water sample is a solid phase extraction column which enriches non-polar and weak polar new pollutants in the water sample by more than 85% under neutral conditions; the solid phase extraction columns for acidic and alkaline water samples are cation exchange solid phase extraction column and anion exchange solid phase extraction column respectively; alternatively, the three solid phase extraction columns are the same in type and all are HLB solid phase extraction columns; the two pH adjusting devices are arranged in the order of pH adjusting devices for adjusting the water sample to be acidic and alkaline; the pH adjusting device comprises a mixing ball, a flow injection tube and a pH adjusting liquid injector; the mixing ball is a spherical container, the upper end of which is connected with the outlet of the previous solid phase extraction column and the lower end of which is connected with the inlet of the next solid phase extraction column; the upper end of the flow injection tube is connected with the pH adjusting liquid injector and the lower end of the flow injection tube is tapered and connected with the upper end of the mixing ball; the pH adjusting liquid injector contains pH adjusting liquid and provides pressure difference, and the pH adjusting liquid is injected into the mixing ball in the form of flow through the flow injection tube; the pH adjusting liquid is acid solution or alkali solution and used to adjust the pH of the water sample in the mixing ball; the top end of the mixing ball is provided with a one-way valve. 2.The non-target screening solid phase extraction system according to claim 1, characterized in that: the pH adjusting liquid injector is an injection cavity; the height of the injection cavity is less than the width of the injection cavity and the injection cavity is located higher than the mixing ball; and a switch valve is arranged on the flow injection tube. 3.The non-target screening solid phase extraction system according to claim 1, characterized in that: the pH adjusting liquid injector comprises a liquid storage device and a liquid injection pump; the liquid storage device is used to contain the pH adjusting liquid; the liquid storage device is connected with the liquid injection pump through a pipeline and the liquid injection pump is connected with the upper end of the mixing ball through a pipeline. 4.The non-target screening solid phase extraction system according to claim 1, characterized in that: a flow controller and a pump are arranged at the outlet of the solid phase extraction column at the end. The non-target screening solid phase extraction system according to any one of claims 1 to 4 is used to screen new pollutants in a water sample. 6.The non-target screening method according to claim 5, characterized in that: each solid phase extraction column is activated respectively, then the plurality of solid phase extraction columns and the pH adjusting devices are arranged in cross connection, then the water sample is added for enrichment, then the solid phase extraction columns are disassembled and eluted respectively to obtain a plurality of final samples, and finally the plurality of final samples are subjected to qualitative and quantitative analysis respectively to obtain the types of new pollutants and the contents of each substance in the water sample. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 5. A method of non-target screening, characterized by: ​ ​ ​

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