Integrated sample introduction detection device and heavy metal rapid detection method

Abstract

The application discloses an integrated sample introduction detection device and a heavy metal rapid detection method, and relates to the field of analytical chemistry. The device comprises a dielectric barrier discharge device and a spectrometer. A heat-assisted evaporation component for containing a to-be-detected sample is arranged in the cavity of the dielectric barrier discharge device. The cavity of the dielectric barrier discharge device is wrapped with a metal foil / wire. An inlet for introducing air, inert gas or reducing gas is arranged on the cavity wall of the dielectric barrier discharge device. The heat-assisted evaporation component serves as an inner electrode of the dielectric barrier discharge device, and the metal foil / wire serves as an outer electrode of the dielectric barrier discharge device, thereby forming an integrated coaxial dielectric barrier discharge structure. The spectrometer is arranged at the outlet of the dielectric barrier discharge device and is used for characteristic spectrum detection. The application utilizes heat assistance to perform sample charring, and utilizes discharge to directly excite the to-be-detected elements. Therefore, the device can detect most liquid samples and can also directly sample and detect solid suspension liquid samples.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of analytical chemistry, and particularly relates to an integrated sample introduction and detection device and a rapid heavy metal detection method. BACKGROUND

[0002] With the rapid development of the current industrial and chemical industries in China, the heavy metals in the environment caused by human activities are also increasing, such as electroplating, mining, papermaking, etc., which diffuse into the soil and water, and further pollute food such as grains and vegetables. Excessive intake of heavy metals directly threatens human health and can even cause cancer. In order to understand the pollution situation and determine the effect of heavy metal pollution control, it is necessary to detect the heavy metal content in these samples in a timely manner. However, the current heavy metal detection mainly uses liquid sample introduction instrument technology, which needs time-consuming and complex sample digestion treatment in the laboratory to convert the sample to be tested into a uniform liquid medium before being measured on the machine. It usually takes 8 hours to 2 days to complete a detection cycle, which cannot realize the on-site and rapid detection of heavy metals.

[0003] Currently, the sample introduction methods commonly used for heavy metal detection include peristaltic pump liquid sample introduction, pneumatic atomization sample introduction, chemical vapor generation sample introduction, and electric heating evaporation sample introduction technology. However, the first three sample introduction methods require sample digestion and conversion into a liquid medium before sample introduction, and cannot directly detect solid samples. Although the electric heating evaporation sample introduction technology can directly introduce solid samples, the commonly used evaporation devices such as graphite furnace, metal ceramic, and quartz tube have high power consumption, large size, and complex structure, which makes it difficult to realize miniaturization, portability, and on-site detection. Moreover, the anti-matrix interference effect of these devices is not good for complex matrices. For example, a study has disclosed the use of dielectric barrier discharge to enrich tungsten wire electric heating evaporation of As, and then release the captured As through DBD discharge, and finally detect it by atomic spectrum. However, in this technology, the tungsten wire is used as an independent electric heating evaporator, and the heavy metal elements need a certain transmission distance to reach the dielectric barrier discharge device after evaporation, which will cause transmission loss and affect the recovery rate and precision of detection. This also causes the overall structure to be very complex, requiring multiple discharges, resulting in a long analysis time, and the instrument is not easy to maintain, and it is also difficult to miniaturize and portable. Therefore, if a technology can integrate the sample carrier, electric heating evaporation device, and discharge device into one, it can further reduce the size and power consumption of the instrument, reduce transmission loss, improve analysis speed and detection sensitivity, and is more conducive to the miniaturization of the instrument device. SUMMARY

[0004] In view of the above deficiencies in the prior art, the present application provides an integrated sample introduction and detection device and a rapid heavy metal detection method. The present application can not only detect most liquid samples, but also directly introduce and detect solid suspension samples.

[0005] To achieve the above-mentioned purpose of the application, the technical scheme adopted by the application is as follows:

[0006] In a first aspect, an integrated sample introduction and detection device is provided, comprising a dielectric barrier discharge device and a spectrometer, a heat-assisted evaporation component for containing a sample to be measured is arranged in a cavity of the dielectric barrier discharge device, a metal foil / wire is wrapped outside the cavity of the dielectric barrier discharge device, and an inlet for air, inert or reducing gas is arranged on the cavity wall of the dielectric barrier discharge device; the heat-assisted evaporation component serves as an inner electrode of the dielectric barrier discharge device, the metal foil / wire serves as an outer electrode of the dielectric barrier discharge device, forming an integrated coaxial dielectric barrier discharge structure, and the spectrometer is arranged at an outlet of the dielectric barrier discharge device for characteristic spectrum detection.

[0007] Further, the heat-assisted evaporation component is a silicon nitride rod, and a base is connected to a lower end of the silicon nitride rod.

[0008] Further, the dielectric barrier discharge device is a cylinder structure made of one or more non-metallic materials.

[0009] Further, the non-metallic materials include quartz, ceramic and graphite.

[0010] Further, the spectrometer includes an atomic emission spectrometer, an atomic absorption spectrometer or an atomic fluorescence spectrometer.

[0011] In a second aspect, a rapid heavy metal detection method is provided, which is based on the integrated sample introduction and detection device described above and comprises the following steps:

[0012] The sample to be measured containing heavy metals is added to the heat-assisted evaporation component, and the sample to be measured is dried and ashed before discharge under external air, and then the heat-assisted evaporation component is inserted into the cavity of the dielectric barrier discharge device; or the heat-assisted evaporation component into which the sample to be measured containing heavy metals is directly inserted into the cavity of the dielectric barrier discharge device, and the sample to be measured is dried and ashed before discharge after air is introduced into the cavity and electricity is applied.

[0013] Inert or reducing gas is introduced into the cavity of the dielectric barrier discharge device through the inlet for purging, heavy metal elements are released by discharge, characteristic spectrum detection is performed by using the spectrometer, and heavy metals are quantified.

[0014] Further, the inert or reducing gas includes nitrogen, argon and argon-hydrogen mixed gas, and the flow rate is 600-1000 mL / min.

[0015] The application has the following beneficial effects:

[0016] 1. Direct excitation by using thermal assisted evaporation component, silicon nitride rod is both sample introduction device and thermal assisted device, and also is inner electrode of dielectric barrier discharge structure, thus forming small integrated direct sample introduction detection device. The present application can detect most liquid samples, and can also directly introduce and detect solid suspension sample.

[0017] 2. When using the integrated sample introduction detection device of the present application, no additional chemical reducing agent is needed, cost is saved, and potential pollution caused by chemical reagent is reduced.

[0018] 3. The silicon nitride rod is both sample introduction device and inner electrode in dielectric barrier discharge structure, thus constructing integrated sample introduction detection device, and further reducing size and power consumption of instrument device.

[0019] 4. Replacing hydride generation sample introduction, peristaltic pump liquid sample introduction or pneumatic atomization sample introduction system in traditional atomic spectrometer, improving sample introduction efficiency and reducing power consumption.

[0020] 5. The structure is simple and the operation is convenient, the direct sample introduction detection method can shorten analysis time, reduce analysis cost and improve analysis efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 Fig. 1 is a schematic diagram of the overall structure of the integrated sample introduction detection device provided in embodiment 1 of the present application;

[0022] Figure 2 Fig. 2 is a schematic diagram of linear equation fitting of urine matrix standard substance provided in embodiment 2 of the present application; wherein the abscissa represents As sample amount, and the ordinate represents peak spectrum area;

[0023] Figure 3 Fig. 3 is a schematic diagram of linear equation fitting of soil matrix standard substance provided in embodiment 3 of the present application; wherein the abscissa represents As sample amount, and the ordinate represents peak spectrum area.

[0024] Wherein: 1, thermal assisted evaporation component; 2, dielectric barrier discharge device; 3, spectrometer; 4, base; 5, inlet; 6, metal foil / wire. DETAILED DESCRIPTION

[0025] The specific embodiments of the present application are described below to facilitate those skilled in the art to understand the present application, but it should be clear that the present application is not limited to the scope of the specific embodiments, and for those skilled in the art, it is obvious that various changes are within the spirit and scope of the present application defined and determined by the appended claims, and all applications utilizing the concept of the present application are within the scope of protection.

[0026] Embodiment 1

[0027] Referring to Figure 1 , an integrated sample introduction detection device is provided, which comprises a dielectric barrier discharge device 2 and a spectrometer 3. The dielectric barrier discharge device 2 is in a wire barrel structure made of one or more non-metallic materials (quartz, ceramic, graphite). A heat-assisted evaporation component 1 for containing the sample to be tested is arranged in the cavity of the dielectric barrier discharge device 2. In this embodiment, the heat-assisted evaporation component 1 is a silicon nitride rod, which is resistant to high temperature and easy to clean. The lower end of the heat-assisted evaporation component 1 is connected to a base 4. The cavity of the dielectric barrier discharge device 2 is wrapped with a metal foil / wire 6. An inlet 5 for air, inert or reducing gas is arranged on the cavity wall of the dielectric barrier discharge device 2. The heat-assisted evaporation component 1 serves as the inner electrode of the dielectric barrier discharge device 2, and the metal foil / wire 6 serves as the outer electrode of the dielectric barrier discharge device 2, forming an integrated coaxial dielectric barrier discharge structure. The spectrometer 3 is arranged at the outlet of the dielectric barrier discharge device 2 for characteristic spectrum detection. The spectrometer 3 includes an atomic emission spectrometer, an atomic absorption spectrometer or an atomic fluorescence spectrometer.

[0028] The inner electrode of the device is designed to be detachable and serves as a sample introduction tool. The sample containing heavy metals is added to the silicon nitride rod, and after drying and ashing for 60 seconds, the inner electrode silicon nitride rod carrying the sample is inserted into the cavity of the dielectric barrier discharge device 2 for discharge release. The sample produces vapor and atomization under the action of plasma generated by discharge, and the finally generated heavy metal aerosol enters the AFS detection system under the sweeping of the carrier gas, is excited by the hollow cathode lamp, and then the optical signal is converted into an electrical signal by the photomultiplier tube. Finally, the signal strength is recorded through the signal processing module and the display.

[0029] Specifically, when the silicon nitride rod is inserted into the cavity of the dielectric barrier discharge device 2, the base 4 connected to the lower end of the silicon nitride rod is clamped with the dielectric barrier discharge device 2.

[0030] Example 2

[0031] A heavy metal rapid detection method based on the integrated sample introduction detection device provided in Example 1, the method comprising the following steps:

[0032] 0.01 mL of urine sample containing arsenic is added to the silicon nitride rod, and after drying and ashing in air, the silicon nitride rod containing arsenic is inserted into the cavity of the dielectric barrier discharge device 2. After 800 mL / min of hydrogen / argon mixed gas containing 10% hydrogen is introduced for 2 minutes, discharge is performed to release arsenic from the dielectric barrier discharge device, and the released arsenic is carried into the atomic fluorescence spectrometer by the carrier gas to realize rapid quantification of arsenic. Referring to Figure 2 , the detection limit of the method can reach 0.07 μg / L, the relative standard deviation of repeated measurements is <10%, the sample addition recovery rate is between 92% and 110%, and the detection results of the standard substance are within the guarantee value interval.

[0033]

[0034] Example 3

[0035] A rapid heavy metal detection method based on the integrated sample introduction and detection device provided in Example 1, the method comprising the following steps:

[0036] 0.2g of soil sample is made into a suspension, the arsenic-containing soil suspension sample is added to the silicon nitride rod, the silicon nitride rod is inserted into the cavity of the dielectric barrier discharge device 2, air is introduced into the cavity, the silicon nitride rod is powered on for heating, drying and ashing; then 800mL / min of hydrogen / argon mixed gas containing 10% hydrogen is introduced into the cavity of the dielectric barrier discharge device 2 for 2min, discharge is carried out, and the silicon nitride rod is assisted to heat, so that arsenic is released from the thermal auxiliary evaporation component 1, and the released arsenic is carried into the atomic fluorescence spectrometer by the carrier gas to realize rapid quantification of arsenic. Referring to Figure 3 The detection limit of the method can reach 0.02μg / L, the relative standard deviation of repeated measurements is <10%, and the recovery rate of the standard substance is between 97% and 120%.

[0037]

[0038] Example 4

[0039] A rapid heavy metal detection method based on the integrated sample introduction and detection device provided in Example 1, the method comprising the following steps:

[0040] 0.1g of rice sample is made into a suspension, the cadmium-containing rice suspension sample is added to the silicon nitride rod, the silicon nitride rod is inserted into the cavity of the dielectric barrier discharge device 2, air is introduced into the cavity, the silicon nitride rod is powered on for heating, drying and ashing; then 800mL / min of hydrogen / argon mixed gas containing 5% hydrogen is introduced into the cavity of the dielectric barrier discharge device 2 for 2min, discharge is carried out to excite and release cadmium from the thermal auxiliary evaporation component 1, and the released cadmium is carried into the atomic absorption spectrometer by the carrier gas to realize rapid quantification of cadmium. The detection results of the standard substance are all within the calibration value interval.

[0041] Example 5

[0042] A rapid heavy metal detection method based on the integrated sample introduction and detection device provided in Example 1, the method comprising the following steps:

[0043] 0.2g fish powder sample is made into a suspension, the mercury-containing fish powder suspension sample is added on the silicon nitride rod, the silicon nitride rod is inserted into the cavity of the dielectric barrier discharge device 2, air is introduced into the cavity, and the silicon nitride rod is electrified to heat, dry and ash; then 600mL / min of hydrogen / argon mixed gas containing 10% hydrogen is introduced into the cavity of the dielectric barrier discharge device 2 for 2min, and discharge is performed to excite and release mercury from the thermal auxiliary evaporation component 1, so that the characteristic spectrum of mercury is detected by an atomic emission spectrometer to realize rapid quantification of mercury. The detection results of the standard substance are all within the calibration value interval.

[0044] The present application utilizes thermal assistance to ash the sample, utilizes discharge to directly excite the element to be detected, and the silicon nitride rod is not only a sampling device and a thermal auxiliary device, but also an inner electrode of the dielectric barrier discharge structure, thereby forming a small integrated direct sampling detection device. The present application can not only detect most liquid samples, but also directly sample and detect solid suspension samples.

[0045] It is obvious to those skilled in the art that the present application is not limited to the details of the above exemplary embodiments, and can be implemented in other specific forms without departing from the spirit or essential characteristics of the present application. Therefore, the embodiments should be regarded as exemplary and non-limiting, and the scope of the present application is defined by the appended claims rather than the above description, and all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present application.

[0046] In addition, it should be understood that although the present specification is described in terms of embodiments, not every embodiment contains only one independent technical solution, and the description manner of the specification is only for the sake of clarity, and those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be properly combined to form other embodiments that those skilled in the art can understand.

Claims

1. An integrated sample introduction detection device comprising a dielectric barrier discharge (2), a spectrometer (3), characterized in that, The cavity of the dielectric barrier discharge device (2) is provided with a thermal auxiliary evaporation component (1) for containing the sample to be tested, the cavity of the dielectric barrier discharge device (2) is wrapped with a metal foil / wire (6), and the cavity wall of the dielectric barrier discharge device (2) is provided with an inlet (5) for introducing air, inert or reducing gas; the thermal auxiliary evaporation component (1) serves as the inner electrode of the dielectric barrier discharge device (2), the metal foil / wire (6) serves as the outer electrode of the dielectric barrier discharge device (2), forming an integrated coaxial dielectric barrier discharge structure, and the spectrometer (3) is arranged at the outlet of the dielectric barrier discharge device (2) for characteristic spectrum detection. The thermal auxiliary evaporation component (1) is a silicon nitride rod, and the lower end is connected with a base (4). The dielectric barrier discharge device (2) is a wire barrel structure made of one or more non-metallic materials.

2. The integrated sample introduction detection device of claim 1, wherein The non-metallic materials include quartz, ceramic, and graphite.

3. The integrated sample introduction and detection device of claim 1, wherein The spectrometer (3) includes an atomic emission spectrometer, an atomic absorption spectrometer, or an atomic fluorescence spectrometer.

4. A method for rapid detection of heavy metals based on the integrated sample introduction and detection device according to any one of claims 1-3, characterized in that, The method comprises the following steps: The sample to be tested containing heavy metals is added to the thermal auxiliary evaporation component (1), the sample is heated under external air, and then the thermal auxiliary evaporation component (1) is inserted into the cavity of the dielectric barrier discharge device (2); or the thermal auxiliary evaporation component (1) into which the sample to be tested containing heavy metals is directly inserted into the cavity of the dielectric barrier discharge device (2), and after air is introduced, the sample is dried and ashed before discharge. The cavity of the dielectric barrier discharge device (2) is purged by introducing inert or reducing gas through the inlet (5), heavy metal elements are released by discharge, and characteristic spectrum detection is performed by the spectrometer (3) to quantify the heavy metals.

5. The method for rapid detection of heavy metals according to claim 4, characterized in that, The inert or reducing gas includes nitrogen, argon, and argon-hydrogen mixed gas, and the flow rate is 600-1000 mL / min.

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