Heavy metal detection device and detection method thereof

Abstract

The invention belongs to the technical field of heavy metal detection, and particularly relates to a heavy metal detection device and a detection method thereof.The device comprises a solution storage unit, an enrichment and pH adjustment unit, a liquid sample injection control unit and a liquid cathode glow discharge detection unit; the liquid sample injection control unit is communicated with the solution storage unit and is configured to convey liquid in the solution storage unit to the enrichment and pH regulation unit for enrichment and pH regulation; and the liquid sample injection control unit conveys the enriched sample to the liquid cathode glow discharge detection unit for detection.

Description

Technical Field

[0001] The present invention belongs to the technical field of heavy metal detection, and particularly relates to a heavy metal detection device and a detection method thereof. Background Art

[0002] With the development of technology and industry, in recent decades, heavy metal pollution has become a global environmental problem and the primary focus of environmental safety. Since heavy metals are difficult to degrade, they will migrate into the food chain along with air, soil, and water bodies, and accumulate in organisms due to biomagnification, and finally enter the human body and produce toxic effects. Therefore, real-time monitoring of heavy metals in the environment is very important.

[0003] At present, the technique of sequential cathodic glow discharge-atomic emission spectrometry (SCGD) has been applied to the analysis of heavy metal elements such as Pb, Cd, and Cu. However, due to its low power and limited excitation ability, the sensitivity of some elements still fails to meet the detection requirements. At the same time, the SCGD signal intensity is affected by the matrix salts in the water body, further reducing the application scenarios of the SCGD technique.

[0004] To address the problems of insufficient sensitivity for the analysis of certain elements and weak anti-matrix ability in SCGD, the solutions mainly include: 1. Improving the excitation ability of SCGD: The main methods include adding organic small molecules, increasing the discharge voltage, using electrode refrigeration, introducing inert gas, etc. However, these methods have relatively limited improvement in the excitation ability of SCGD. 2. Adopting pre-concentration: Chinese Patent Application No. CN112461814A discloses a thallium detection device and a detection method in water, which uses solid-phase extraction technology to enrich low-content thallium in water. However, the prior art (such as CN112461814A) can only enrich single elements, and the separation effect of matrix salts is insufficient, resulting in limited detection sensitivity.

[0005] Therefore, how to avoid the low sensitivity and detection accuracy of sequential cathodic glow discharge-atomic emission spectrometry in the detection of actual samples is a technical problem that those skilled in the art need to solve urgently.

[0006] It should be noted that the above information disclosed in this background art section is only used to understand the background art of the concept of this application. Therefore, the above description is not considered as information of the prior art. Summary of the Invention

[0007] The embodiments of the present disclosure at least provide a heavy metal detection device and a detection method thereof.

[0008] In a first aspect, the embodiments of the present disclosure provide a heavy metal detection device, including: a solution storage unit, an enrichment and pH adjustment unit, a liquid injection control unit, and a sequential cathodic glow discharge detection unit; The liquid injection control unit is communicated with the solution storage unit and is configured to transport the liquid in the solution storage unit to the enrichment and pH adjustment unit for enrichment and pH adjustment, and then the liquid injection control unit transports the enriched sample to the liquid cathode glow discharge detection unit for detection.

[0009] In an alternative embodiment, the solution storage unit includes a water sample container, a deionized water container, an acid solution container, an alkali solution container, a first waste liquid bucket and a second waste liquid bucket. The water sample container, the deionized water container, the acid solution container and the alkali solution container are respectively communicated with the liquid injection control unit. The first waste liquid bucket is communicated with the enrichment and pH adjustment unit, and the second waste liquid bucket is communicated with the liquid cathode glow discharge detection unit.

[0010] In an alternative embodiment, the liquid injection control unit includes a first peristaltic pump, a three-way valve, a storage bottle and a second peristaltic pump. The inlets of the first peristaltic pump are respectively communicated with the water sample container, the deionized water container, the acid solution container and the alkali solution container. The outlet of the first peristaltic pump is successively communicated with the enrichment and pH adjustment unit, the three-way valve, the storage bottle, the second peristaltic pump and the liquid cathode glow discharge detection unit. The other valve port of the three-way valve is communicated with the first waste liquid bucket.

[0011] In an alternative embodiment, the enrichment and pH adjustment unit is filled with a polyamine-type ion exchange resin having heavy metal adsorption and pH adjustment functions.

[0012] In an alternative embodiment, the polyamine-type ion exchange resin is polyamine-type resin DIAION™ CR20.

[0013] In an alternative embodiment, the liquid cathode glow discharge detection unit includes: A DC high-voltage power supply; An anode tungsten rod, which is connected to the positive output terminal of the DC high-voltage power supply; A cathode graphite rod, which is connected to the negative output terminal of the DC high-voltage power supply; An injection alumina capillary tube, which penetrates through the cathode graphite rod and is perpendicular to the cathode graphite rod, and is communicated with the second peristaltic pump; A waste liquid pool, which is communicated with the second waste water bucket.

[0014] In a second aspect, the embodiments of the present disclosure further provide a method for using a heavy metal detection device, including the following steps: Step S1: The water sample in the water sample container is controlled by the first peristaltic pump and enters the enrichment and pH adjustment unit. The enrichment and pH adjustment unit enriches the heavy metal elements in the water sample and filters out the matrix salts in the water sample. The water sample flowing through the enrichment and pH adjustment unit flows into the first waste liquid bucket through a three-way valve. Step S2: The deionized water in the deionized water container is controlled by the first peristaltic pump and enters the enrichment and pH adjustment unit to rinse the residual water sample and then flows into the first waste liquid bucket. Step S3: The acid solution in the acid solution container is controlled by the first peristaltic pump and enters the enrichment and pH adjustment unit to elute the heavy metals adsorbed on the enrichment and pH adjustment unit, and after adjusting the pH to 1, it flows into the storage bottle. Step S4: The solution in the storage bottle is controlled by the second peristaltic pump and enters the liquid cathode glow discharge detection unit, and multiple heavy metals are detected and analyzed by liquid cathode glow discharge-atomic emission spectrometry.

[0015] In an optional implementation manner, in step S1, the flow rate of the water sample in the water sample container controlled by the first peristaltic pump is 5-10 mL / min.

[0016] In an optional implementation manner, in step S2, the flow rate of the deionized water in the deionized water container controlled by the first peristaltic pump is 1-10 mL / min.

[0017] In an optional implementation manner, in step S3, the acid solution is dilute nitric acid with a concentration of 1-3 mol / L, and the flow rate of the acid solution in the acid solution container controlled by the first peristaltic pump is 1-5 mL / min; In an optional implementation manner, in step S4, the flow rate of the mixed solution controlled by the second peristaltic pump is 1-3 mL / min, the voltage of the liquid cathode glow discharge detection unit is set to 900-1100 V, the current is set to 30-100 mA, and the electrode spacing between the anode and the cathode is set to 1-5 mm.

[0018] The beneficial effects of the present invention are that this heavy metal detection device is provided with a solution storage unit, an enrichment and pH adjustment unit, a liquid injection control unit, and a liquid cathode glow discharge detection unit. The liquid injection control unit transports the liquid in the solution storage unit to the enrichment and pH adjustment unit. The enrichment and pH adjustment unit can selectively enrich the heavy metals in the liquid and remove the matrix salts at the same time. Subsequently, the liquid injection control unit transports the enriched sample to the liquid cathode glow discharge detection unit for detection; through the cooperation of the above-mentioned various units, the problems of the traditional liquid cathode glow discharge-atomic emission spectrometry technology, such as the inability to detect due to too low concentration of heavy metal elements, low sensitivity and low detection accuracy of heavy element analysis caused by matrix salt interference, are solved.

[0019] Other features and advantages of the present invention will be described in the following specification, and in part will be obvious from the specification, or will be understood by implementing the present invention. The objectives and other advantages of the present invention are achieved and obtained by the structures specifically pointed out in the specification, claims, and drawings.

[0020] To make the above objectives, features, and advantages of the present invention more obvious and understandable, specific preferred embodiments are hereby given, and in conjunction with the accompanying drawings, the detailed description is as follows. Description of the Drawings

[0021] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0022] Figure 1 Structural schematic diagram of a heavy metal detection device provided by an embodiment of the present disclosure; Figure 2 Removal rate diagram of matrix salts of a heavy metal detection device provided by an embodiment of the present disclosure; Figure 3 Influence diagram of liquid flow rate and pH on signal value of the liquid cathode glow discharge device in Comparative Example 1; Figure 4 Recovery rate diagram of heavy elements to be measured in Embodiment 1 of a heavy metal detection device provided by an embodiment of the present disclosure; Figure 5 Signal sensitivity comparison diagram between the existing SCGD technology and the detection technology proposed in this embodiment;

[0023] In the figure: 1. Solution storage unit; 11. Water sample container; 12. Acid solution container; 13. Deionized water container; 14. Alkaline solution container; 15. First waste liquid bucket; 16. Second waste liquid bucket; 2. Enrichment and pH adjustment unit; 3. Liquid injection control unit; 31. First peristaltic pump; 32. Three-way valve; 33. Temporary storage bottle; 34. Second peristaltic pump; 4. Liquid cathode glow discharge detection unit; 41. DC high voltage power supply; 42. Anode tungsten rod; 43. Cathode graphite rod; 44. Injection alumina capillary; 45. Waste liquid pool. Specific Embodiments

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Apparently, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0025] In this document, when it is mentioned that a first component is located on a second component, this may mean that the first component can be directly formed on the second component, or a third component can be interposed between the first component and the second component. In addition, in the drawings, for the effective description of the technical content, the thickness of the components may be exaggerated or reduced.

[0026] In this document, when an element or layer is referred to as being "located on", "joined to", "connected to", "attached to", or "coupled to" another element or layer, it can be directly located on, joined, connected, attached, or coupled to the other element or layer, or there may be an intermediate element or layer. In contrast, when an element is referred to as being "directly on another element or layer", "directly joined to", "directly connected to", "directly attached to", or "directly coupled to" another element or layer, there may be no intermediate element or layer. Other words used to describe the relationship between elements should be interpreted in a similar manner (e.g., "between" versus "directly between", "adjacent" versus "directly adjacent", etc.). As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0027] In this document, example embodiments of the present disclosure will be described in more detail with reference to the accompanying drawings. As used herein, expressions such as "at least one of..." modify the entire list of elements when following a list of elements, rather than modifying individual elements in the list. For example, the expression "at least one of a, b, and c" should be understood to include only a, only b, only c, both a and b, both a and c, both b and c, or all of a, b, and c.

[0028] The terms used herein are only for describing specific exemplary configurations and are not intended to be limiting. As used herein, the singular articles "a", "an", and "the" may also be intended to include the plural forms, unless it is clearly stated otherwise in the context. The terms "comprising", "including", and "having" are inclusive and thus specify the presence of the stated features, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or their combinations. The method steps, processes, and operations described herein should not be construed as necessarily requiring them to be performed in the particular order discussed or shown, unless specifically identified as an order of performance. Additional or alternative steps may be employed.

[0029] As used herein, phrases such as "in one embodiment", "according to one embodiment", "in some embodiments", etc. generally refer to the fact that the specific feature, structure, or characteristic after the phrase can be included in at least one embodiment of the present disclosure. Therefore, a specific feature, structure, or characteristic can be included in more than one embodiment of the present disclosure, such that these phrases do not necessarily refer to the same embodiment. As used herein, terms such as "example", "exemplary", etc. are used "as an example, instance, or illustration. Any embodiment, aspect, or design described herein as "example" or "exemplary" is not necessarily to be construed as preferred or superior to other embodiments, aspects, or designs. Instead, the use of terms such as "example", "exemplary", etc. is intended to present concepts in a specific manner.

[0030] It has been found through research that the disadvantages of the prior art are as follows: The technique of solution cathode glow discharge - atomic emission spectrometry (SCGD) has been applied to the analysis of heavy metal elements such as Pb, Cd, Cu, etc. However, due to its low power and limited excitation ability, the sensitivity of some elements still fails to meet the detection requirements. At the same time, the SCGD signal intensity is affected by the matrix salts in the water body, further reducing the application scenarios of the SCGD technique.

[0031] The patent with the patent number CN112461814A discloses a device and technique for on - line enrichment and detection of thallium elements in water. However, in this technique, multiple elements cannot be enriched and detected simultaneously, and the separation effect of the matrix impurities in the water body by this method is unknown; the pH adjustment method in the present invention can be traced back to the column suppressor technique in ion chromatography (Mou Shifen, Zhu Yan, Liu Kena. Ion Chromatography Methods and Applications [M]. Chemical Industry Press: 201803.428). The main purpose of using a column suppressor in ion chromatography is to reduce the solution background conductivity, while in this patent, this technique is used to adjust the solution pH.

[0032] Based on the above research, the embodiments of the present disclosure provide a heavy metal detection device and its working method, which solve the above problems by selectively enriching heavy metals in water and removing matrix salts simultaneously.

[0033] Regarding the defects existing in the above - mentioned solutions, they are all the results obtained by the inventors through practice and careful research. Therefore, the discovery process of the above - mentioned problems and the solutions proposed by the present disclosure in this article for the above - mentioned problems should both be the contributions made by the inventors during the process of the present disclosure.

[0034] It should be noted that: Similar reference numerals and letters represent similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0035] The following will describe in detail some embodiments of the present invention with reference to the accompanying drawings. Without conflict, the following embodiments and the features in the embodiments can be combined with each other.

[0036] Referring to Figure 1 , an embodiment of the present disclosure provides a heavy metal detection device, including: a solution storage unit 1, an enrichment and pH adjustment unit 2, a liquid sample injection control unit 3, and a liquid cathode glow discharge detection unit 4; the liquid sample injection control unit 3 is connected to the solution storage unit 1 and is configured to transport the liquid in the solution storage unit 1 to the enrichment and pH adjustment unit 2 for enrichment and pH adjustment, and then the liquid sample injection control unit 3 transports the enriched sample to the liquid cathode glow discharge detection unit 4 for detection.

[0037] Continuing to refer to Figure 1 , in some embodiments, the solution storage unit 1 includes a water sample container 11, a deionized water container 13, an acid solution container 12, an alkali solution container 14, a first waste liquid bucket 15, and a second waste liquid bucket 16. The water sample container 11, the deionized water container 13, the acid solution container 12, and the alkali solution container 14 are respectively connected to the liquid sample injection control unit 3. The first waste liquid bucket 15 is connected to the enrichment and pH adjustment unit 2, and the second waste liquid bucket 16 is connected to the liquid cathode glow discharge detection unit 4.

[0038] Continuing to refer to Figure 1 , in some embodiments, the liquid sample injection control unit 3 includes a first peristaltic pump 31, a three-way valve 32, a temporary storage bottle 33, and a second peristaltic pump 34. The inlets of the first peristaltic pump 31 are respectively connected to the water sample container 11, the deionized water container 13, the acid solution container 12, and the alkali solution container 14. The outlet of the first peristaltic pump 31 is successively connected to the enrichment and pH adjustment unit 2, the three-way valve 32, the temporary storage bottle 33, the second peristaltic pump 34, and the liquid cathode glow discharge detection unit 4. The other valve port of the three-way valve 32 is connected to the first waste liquid bucket 15.

[0039] Specifically, the first peristaltic pump 31 is adapted to control the flow rate of the solutions in the water sample container 11, the deionized water container 13, the acid solution container 12, and the alkali solution container 14, and the second peristaltic pump 34 is adapted to control the flow rate of the solution in the temporary storage bottle 33.

[0040] Furthermore, the solution processed by the enrichment and pH adjustment unit 2 is suitable for being stored in the temporary storage bottle 33. The temporary storage bottle 33 can achieve the homogenization of the solution concentration and independently control the injection flow rate of the detection unit.

[0041] Further, after the enrichment and pH adjustment in the enrichment and pH adjustment unit 2 are completed, the first peristaltic pump 31 is adapted to control the lye in the lye container 14 to enter the enrichment and pH adjustment unit 2 for pH adjustment function regeneration; subsequently, the first peristaltic pump 31 controls the deionized water in the deionized water container 13 to enter the enrichment and pH adjustment unit 2 for cleaning, and the liquid after cleaning finally flows into the first waste liquid bucket 15.

[0042] Continue to refer to Figure 1 , in some embodiments, the enrichment and pH adjustment unit 2 is filled with a polyamine-type ion exchange resin having heavy metal adsorption and pH adjustment functions.

[0043] Further, the polyamine-type ion exchange resin may be polyamine-type resin DIAION™ CR20.

[0044] Continue to refer to Figure 1 , in some embodiments, the liquid cathode glow discharge detection unit 4 includes: A DC high-voltage power supply 41; an anode tungsten rod 42, the anode tungsten rod 42 is connected to the positive output terminal of the DC high-voltage power supply 41; a cathode graphite rod 43, the cathode graphite rod 43 is connected to the negative output terminal of the DC high-voltage power supply 41; a sample injection alumina capillary 44, the sample injection alumina capillary 44 penetrates through the cathode graphite rod 43 and is perpendicular to the cathode graphite rod 43, and is communicated with the second peristaltic pump 34; a waste liquid pool 45, the waste liquid pool 45 is arranged below the sample injection alumina capillary 44 and is communicated with the second waste liquid bucket 16, and the second waste liquid bucket 16 is used for temporarily recovering the discharge waste liquid.

[0045] Specifically, the second peristaltic pump 34 is adapted to input the solution in the storage bottle 33 into the sample injection alumina capillary 44, so that the solution overflows from the top of the sample injection alumina capillary 44 along its outer wall to the cathode graphite rod 43 to form a liquid cathode. The DC high-voltage power supply 41 applies a high voltage to the anode tungsten rod 42 and the cathode graphite rod 43, and a liquid cathode glow discharge plasma is formed between the anode tungsten rod 42 and the liquid cathode. Atoms or ions of different heavy metal elements can emit characteristic spectra after being excited. The obtained characteristic spectra are introduced into the optical fiber probe and coupled to the incident slit of the spectrometer. The charge-coupled detector of the spectrometer detects and amplifies the characteristic spectra to realize the detection and analysis of different heavy metal elements.

[0046] As Example 1, at least one embodiment also discloses a heavy metal detection method, and the specific steps are as follows: Step S1, 100 mL of the water sample in the water sample container 11 enters the enrichment and pH adjustment unit 2 under the control of the first peristaltic pump 31 at a flow rate of 10 mL / min. The enrichment and pH adjustment unit enriches the heavy metal elements in the water sample and filters out the matrix salts in the water sample; the concentrations of Cd, Cu, Pb, Zn, and Ni elements in the water sample are all 0.01 mg / L, and the contents of K, Na, Mg, and Ca are all 100 mg / L. Step S2, 5 mL of deionized water in the deionized water container 12 enters the enrichment unit under the control of the first peristaltic pump 31 at a flow rate of 10 mL / min to rinse the water sample solution remaining in the enrichment unit. Step S3, 5 mL of the eluent (dilute nitric acid with a concentration of 1 mol / L) in the acid solution container 13 enters the enrichment and pH adjustment unit under the control of the first peristaltic pump 31 at a flow rate of 5 mL / min to elute the heavy metals adsorbed on the enrichment column, and after adjusting the pH to 1.2, it flows into the temporary storage bottle 33, and this liquid is denoted as solution 1. Step S4, the sample solution to be measured enters the liquid cathode glow discharge detection unit 4 under the control of the second peristaltic pump 34 at a flow rate of 3 mL / min, and a liquid cathode glow discharge-atomic emission spectrometry is used to detect and analyze various heavy metals. The voltage of the liquid cathode glow discharge detection unit is set to 1100 V, the current is set to 100 mA, and the electrode distance between the anode and the cathode is set to 5 mm; at the same time, the first peristaltic pump 31 controls 5 mL of the alkali solution (NaOH solution with a concentration of 1 mol / L) in the alkali solution container to enter the enrichment and pH adjustment unit at a flow rate of 3 mL / min for regeneration; then the first peristaltic pump 31 controls 10 mL of deionized water in the deionized water container to rinse the enrichment and pH adjustment unit at a flow rate of 10 mL / min.

[0047] As Example 2, as another specific implementation manner of the heavy metal detection method, the steps include: Step S1, 100 mL of the water sample in the water sample container 11 enters the enrichment and pH adjustment unit 2 under the control of the first peristaltic pump 31 at a flow rate of 5 mL / min. The enrichment and pH adjustment unit enriches the heavy metal elements in the water sample and filters out the matrix salts in the water sample; the concentrations of Cd, Cu, Pb, Zn, and Ni elements in the water sample are all 0.01 mg / L, and the contents of K, Na, Mg, and Ca are all 100 mg / L. Step S2, 5 mL of deionized water in the deionized water container 12 enters the enrichment unit under the control of the first peristaltic pump 31 at a flow rate of 1 mL / min to rinse the water sample solution remaining in the enrichment unit. Step S3, 5 mL of the eluent (dilute nitric acid with a concentration of 3 mol / L) in the acid solution container 13 enters the enrichment and pH adjustment unit under the control of the first peristaltic pump 31 at a flow rate of 1 mL / min, elutes the heavy metals adsorbed on the enrichment column, and flows into the temporary storage bottle 33 after adjusting the pH to 0.8; Step S4, the test sample solution enters the liquid cathode glow discharge detection unit 4 under the control of the second peristaltic pump 34 at a flow rate of 1 mL / min, and a liquid cathode glow discharge - atomic emission spectrometry is used to detect and analyze multiple heavy metals. The voltage of the liquid cathode glow discharge detection unit is set to 900 V, the current is set to 30 mA, and the electrode distance between the anode and the cathode is set to 1 mm; at the same time, the first peristaltic pump 31 controls 5 mL of the alkali solution (NaOH solution with a concentration of 1 mol / L) in the alkali solution container to enter the enrichment and pH adjustment unit for regeneration at a flow rate of 3 mL / min; then the first peristaltic pump 31 controls 10 mL of deionized water in the deionized water container to flush the enrichment and pH adjustment unit at a flow rate of 10 mL / min.

[0048] As Example 3, in some implementations, the specific steps of the heavy metal detection method may further include: Step S1, 100 mL of the water sample in the water sample container 11 enters the enrichment and pH adjustment unit 2 under the control of the first peristaltic pump 31 at a flow rate of 8 mL / min. The enrichment and pH adjustment unit enriches the heavy metal elements in the water sample and filters out the matrix salts in the water sample; the concentrations of Cd, Cu, Pb, Zn, and Ni elements in the water sample are all 0.01 mg / L, and the contents of K, Na, Mg, and Ca are all 100 mg / L; Step S2, 5 mL of deionized water in the deionized water container 12 enters the enrichment unit under the control of the first peristaltic pump 31 at a flow rate of 5 mL / min to flush the water sample solution remaining in the enrichment unit; Step S3, 5 mL of the eluent (dilute nitric acid with a concentration of 2 mol / L) in the acid solution container 13 enters the enrichment and pH adjustment unit under the control of the first peristaltic pump 31 at a flow rate of 3 mL / min, elutes the heavy metals adsorbed on the enrichment column, and flows into the temporary storage bottle 33 after adjusting the pH to 1; Step S4, the solution of the sample to be tested enters the liquid cathode glow discharge detection unit 4 under the control of the second peristaltic pump 34 at a flow rate of 2 mL / min, and multi-heavy metals are detected and analyzed by liquid cathode glow discharge-atomic emission spectrometry. The voltage of the liquid cathode glow discharge detection unit is set to 1000 V, the current is set to 80 mA, and the electrode spacing between the anode and the cathode is set to 3 mm. At the same time, the first peristaltic pump 31 controls 5 mL of lye (NaOH solution with a concentration of 1 mol / L) in the lye container to enter the enrichment and pH adjustment unit for regeneration at a flow rate of 3 mL / min. Then, the first peristaltic pump 31 controls 10 mL of deionized water in the deionized water container to flush the enrichment and pH adjustment unit at a flow rate of 10 mL / min.

[0049] Comparative Example 1 After the water sample in the water sample container 11 is acidified to pH = 1 with 65% concentrated nitric acid, the second peristaltic pump 34 controls it to enter the liquid cathode glow discharge detection unit 4 at a flow rate of 3 mL / min, and multi-heavy metals are detected and analyzed by liquid cathode glow discharge-atomic emission spectrometry.

[0050] Effect verification The detection effects of the multi-heavy metal simultaneous detection device and detection method in Example 1 were tested. The test method is as follows: Removal rate of matrix salts: Measure the content of matrix salts by ICP-OES. The calculation method of the removal rate of matrix salts is: (concentration of matrix salts in the above solution 1 / concentration of matrix salts in the above water sample) × 100%.

[0051] Recovery rate: The calculation method of the recovery rate is: heavy metal content in the above solution 1 / heavy metal content in the water sample × 100%; among them, the heavy metal content in solution 1 is tested by the liquid cathode glow discharge detection unit.

[0052] See Figure 2 , in Example 1, the heavy metal detection device enriches various heavy metal elements in the water sample through the resin column and filters out the matrix salts in the water sample. The removal rates of K, Na, Mg, and Ca matrix salts are above 90%.

[0053] See Figure 3 , when the acidity (pH < 0.5) and the flow rate (> 3 mL / min), it has an adverse effect on the element signal of the element to be tested. Thus, it is proved that for the element signal influence brought by the liquid flow rate and pH, the pH adjustment unit of the present invention can solve the problem of too low solution acidity, and the temporary storage bottle 33 and the second peristaltic pump 34 can solve the problem of independent control of the injection flow rate of the detection unit.

[0054] See Figure 4, in Example 1, a plurality of heavy metal elements in the water sample are enriched through the enrichment and pH adjustment unit, and the matrix salts in the water sample are filtered out, and the acidity of the eluent is regulated. The flow rate of the sample entering the liquid cathode glow discharge detection unit is regulated through the temporary storage bottle 33 and the second peristaltic pump 34, and samples with low heavy metal content and high-salt matrix are successfully detected. The recovery rates of Cd, Cu, Ni, Pb, and Zn are above 90%.

[0055] See Figure 5 , Figure 5 Figure 7 is a comparison chart of the spectrograms of Comparative Example 1 and Example 1. It can be seen from Figure 5 that when detecting samples with low heavy metal content and high-salt matrix in Comparative Example 1, the sensitivity of heavy metals is poor, and the emission signal of matrix salts is strong. However, for the detection technology proposed in Example 1, the heavy metal signal is strong, and there is almost no emission signal of matrix salts.

[0056] In summary, by adding an enrichment and pH adjustment unit to this heavy metal detection device, the enrichment and pH adjustment unit can selectively enrich heavy metals in water while removing matrix salts. The enrichment recovery rate can reach more than 90%, and the matrix salt removal rate can reach more than 90%. This solves the problems of the traditional liquid cathode glow discharge-atomic emission spectroscopy technology, such as the inability to detect due to too low heavy metal element concentration, and the low sensitivity and low detection accuracy of heavy element analysis caused by matrix salt interference.

[0057] In the description of the embodiments of the present invention, unless otherwise clearly specified and limited, the terms "installation", "connection", and "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0058] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. In addition, terms such as "first", "second" and other numerical terms used herein do not imply an order or sequence unless clearly indicated in the text. Therefore, without departing from the teachings of the exemplary embodiments, the first element, component, region, layer or section discussed above can be referred to as the second element, component, region, layer or section.

[0059] Spatial relative terms, such as "inner", "outer", "below", "beneath", "under", "above", "upper", etc., may be used herein to facilitate the description of the relationship of one element or feature to another element or feature as illustrated in the figures. In addition to the orientation depicted in the figures, the spatial relative terms may be intended to cover different orientations of the device in use or operation. For example, if the device in the figures is turned over, an element described as "below" or "beneath" other elements or features will be oriented "above" the other elements or features. Thus, the exemplary term "below" can cover both an above and a below orientation. The device may be otherwise oriented (rotated 90 degrees or in other orientations), and the spatial relative descriptors used herein are to be interpreted accordingly.

[0060] In the foregoing discussion, unless otherwise specified, when used to describe a numerical value, terms such as "about", "approximately", "substantially", etc. mean a variation of + / − 10% of that value.

[0061] Enlightened by the above-mentioned ideal embodiments according to the present invention, through the above description, relevant staff can fully make various changes and modifications without departing from the technical idea of the present invention. The technical scope of the present invention is not limited to the content in the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. A heavy metal detection device, characterized in that: include: A solution storage unit (1), an enrichment and pH adjustment unit (2), a liquid injection control unit (3) and a liquid cathode glow discharge detection unit (4); The liquid injection control unit (3) is connected to the solution storage unit (1) and is configured to transport the liquid in the solution storage unit (1) to the enrichment and pH adjustment unit (2) for enrichment and pH adjustment, and then the liquid injection control unit (3) transports the enriched sample to the liquid cathode glow discharge detection unit (4) for detection.

2. The detection device according to claim 1, characterized in that The solution storage unit (1) comprises a water sample container (11), a deionized water container (13), an acid container (12), an alkali container (14), a first waste liquid barrel (15) and a second waste liquid barrel (16); the water sample container (11), the deionized water container (13), the acid container (12) and the alkali container (14) are respectively connected to a liquid injection control unit (3); the first waste liquid barrel (15) is connected to the enrichment and pH adjustment unit (2); and the second waste liquid barrel (16) is connected to a liquid cathode glow discharge detection unit (4).

3. The detection device according to claim 2, characterized in that: The liquid injection control unit (3) comprises a first peristaltic pump (31), a three-way valve (32), a temporary storage bottle (33) and a second peristaltic pump (34); the inlet of the first peristaltic pump (31) is connected to the water sample container (11), the deionized water container (13), the acid container (12) and the alkali container (14); the outlet of the first peristaltic pump (31) is connected to the enrichment and pH adjustment unit (2), the three-way valve (32), the temporary storage bottle (33), the second peristaltic pump (34) and the liquid cathode glow discharge detection unit (4) in sequence; and the other valve port of the three-way valve (32) is connected to the first waste liquid barrel (15).

4. The detection device according to claim 1, characterized in that: The enrichment and pH adjustment unit (2) is filled with a polyamine ion exchange resin having heavy metal adsorption and pH adjustment functions.

5. The detection device according to claim 3, characterized in that: The liquid cathode glow discharge detection unit (4) comprises: DC high voltage power supply (41); an anode tungsten rod (42), the anode tungsten rod (42) being connected to the positive output end of the DC high voltage power supply (41); A cathode graphite rod (43), wherein the cathode graphite rod (43) is connected to the negative output end of the DC high voltage power supply (41); an inlet alumina capillary (44), the inlet alumina capillary (44) passing through the cathode graphite rod (43) and being perpendicular to the cathode graphite rod (43), and being in communication with the second peristaltic pump (34); A waste liquid pool (45), wherein the waste liquid pool (45) is connected to the second waste water bucket.

6. A heavy metal detection method comprising: Step S1, the water sample in the water sample container (11) is controlled by the first peristaltic pump (31) to enter the enrichment and pH adjustment unit (2), the enrichment and pH adjustment unit (2) enriches the heavy metal elements in the water sample and filters out the matrix salt in the water sample, and the water sample flowing through the enrichment and pH adjustment unit (2) flows into the first waste liquid bucket (15) through the three-way valve (32); Step S2, the deionized water in the deionized water container (13) is controlled by the first peristaltic pump (31), enters the enrichment and pH adjustment unit (2), rinses the residual water sample, and flows into the first waste liquid barrel (15); Step S3, the acid in the acid container (12) is controlled by the first peristaltic pump (31) to enter the enrichment and pH adjustment unit (2), to elute the heavy metals adsorbed on the enrichment and pH adjustment unit (2), and to adjust the pH to 0.8-1.2 before flowing into the temporary storage bottle (33); Step S4, the solution in the temporary storage bottle (33) is controlled by the second peristaltic pump (34) to enter the liquid cathode glow discharge detection unit (4) and detect and analyze multiple heavy metals using liquid cathode glow discharge-atomic emission spectrometry.

7. The detection method according to claim 7, characterized in that: In step S1, the water sample in the water sample container (11) is controlled by a first peristaltic pump (31) to have a flow rate of 5-10 mL / min.

8. The detection method according to claim 7, characterized in that In step S2, the deionized water in the deionized water container is controlled by a first peristaltic pump (31) to have a flow rate of 1-10 mL / min.

9. The detection method according to claim 7, characterized in that: In step S3, the acid solution uses dilute nitric acid with a concentration of 1-3 mol / L, and the acid solution in the acid solution container (12) is controlled by a first peristaltic pump (31) to have a flow rate of 1-5 mL / min.

10. The detection method according to claim 7, characterized in that: In step S4, the mixed solution is controlled to flow at a rate of 1-3 mL / min by a second peristaltic pump (34), the voltage of the liquid cathode glow discharge detection unit (4) is set to 900-1100 V, the current is set to 30-100 mA, and the electrode spacing between the anode and the cathode is set to 1-5 mm.

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