CN105675585B - A kind of Portable element analyzer and its detection method available for field exploration - Google Patents

Abstract

The invention discloses a portable elemental analyzer that can be used for field investigation, comprising: a sample introduction system, an electrolyte discharge plasma generation system, an optical path collection and filter sorting system, a data processing system and a control system; The system introduces the sample into the electrolyte discharge plasma generation system for glow discharge to emit element spectrum, which is collected by the optical path collection and filter sorting system and transmitted to the data processing system, and finally displayed and collected by the control system. The above-mentioned control system controls the sampling system, the electrolyte discharge plasma generation system, the light path collection and filter sorting system and the data processing system. The invention provides a metal element analysis device that does not need to acidify samples in advance, does not need carrier gas, has more stable discharge, is easy to operate, has cheap equipment and is small in volume. The detection method of the invention has automatic detection, simple operation, strong field adaptability, and greatly improves field detection speed and precision.

Description

A portable element analyzer and its detection method that can be used for field survey

technical field

The invention relates to a metal element analysis device, in particular to a small-volume, low-cost, and easy-to-operate portable element analyzer and a detection method for on-line detection of liquid samples.

Background technique

In the detection of metal elements in water, traditional detection methods such as complexometric titration, electrochemical method, inductively coupled atomic emission spectrometry, etc. often have one or another defect and deficiency. The operation is complicated and it is difficult to realize the real-time and continuous detection of metal elements in water. The electrolyte glow discharge technology that has emerged in recent years can just make up for these shortcomings. Its basic structure is as follows: the electrolyte solution is led out through one end of a vertical conduit through the sampling device to form a fountain, and a certain positive voltage is applied near the lead-out end with a metal electrode to generate a discharge plasma. Webb et al. improved the discharge system from the aspects of reducing the surface area of the cathode and reducing the volume of the plasma. By adopting the "J" type diversion structure, the volume of the sample required for the discharge of the constructed system was reduced, and the power of the external circuit was reduced. The detection ability of the system for metal elements is greatly improved, which can reach μg/L and below.

However, for the current research on electrolyte glow discharge technology, the spectral detection part is collected and processed by spectrometers, such as a combined spectrometer using a monochromatic spectrometer and a photomultiplier tube as a detector or a portable spectrometer. The large volume and high cost reduce the portability of metal ion detection instruments based on the principle of electrolyte glow discharge, thus limiting the widespread application of electrolyte discharge photoelectric detection technology.

Contents of the invention

The object of the present invention is to provide a portable metal element detection device and a detection method thereof for the technical defects existing in the prior art.

The technical scheme adopted for realizing the purpose of the present invention is:

A portable elemental analyzer that can be used for field surveys, including: a sample introduction system, an electrolyte discharge plasma generation system, an optical path collection and filter sorting system, a data processing system and a control system; the sample introduction system introduces a sample The electrolytic solution discharge plasma generation system performs glow discharge to emit element spectra, which are collected by the optical path collection and filter sorting system and transmitted to the data processing system, and finally displayed and collected by the control system, and the control system controls Sample introduction system, electrolyte discharge plasma generation system, optical path collection and filter sorting system and data processing system, the electrolyte discharge plasma generation system includes a power supply composed of a lithium battery and a transformer, a transformer and a glow discharge atom carburetor.

The sampling system includes two single-channel peristaltic pumps for pumping the unacidified sample and the standard acid solution into the buffer chamber respectively, one end communicates with the buffer chamber and the other end is connected to the electrolyte discharge plasma generation system. The conduit of the capillary glass tube, a plurality of buffer balls contained in the conduit, and the plasma auxiliary generating device, the plasma assist generating device includes an air bag connected in series between the conduit and the capillary glass tube, and is arranged on The electric control injection valve on the air bag is controllably connected with the control system, and the speed of the single-channel peristaltic pump is controlled by the control system respectively.

The optical collection and filtering sorting system is integrated on the cage coaxial system, including a biconvex lens (2), a spatial filter (3), a front plano-convex lens, a narrow-band filter and a rear plano-convex lens arranged along the optical path in sequence. Convex lens, the emission spectrum emitted by the electrolyte discharge plasma is collected by the biconvex lens behind the plasma and converged and imaged to the spatial filter (3) behind the biconvex lens (2), and the spatial filter (3) selects The main discharge luminous area of the metal element in the plasma is the negative glow area, and then the front plano-convex lens (4) located at f2 behind the spatial filter (3) converges the parallel light spectrum of the negative glow area to the narrow-band filter (5), the selected metal element characteristic spectrum is collected and converged on the photosensitive surface of the photomultiplier tube behind the back plano-convex lens (6) by the back plano-convex lens (6), wherein the focal length of the bi-convex lens is 3cm～10cm, f2 is the focal length of the front plano-convex lens, f2 is 3cm-10cm, the structure of the back plano-convex lens is exactly the same as that of the front plano-convex lens, and the biconvex and plano-convex lenses are all made of fused silica material.

The data processing system includes a photomultiplier tube, a current amplifier and a data collector.

The buffer ball is made of glass or acid-resistant material, the buffer ball is placed in the horizontal conduit, and the diameter of the buffer ball is 3/4-4/3 of the diameter of the conduit.

The narrow band filter is a narrow band pass interference filter installed on the motorized filter wheel, the bandwidth is 5-30nm, and the central wavelength of the narrow band filter is the emission wavelength of the resonance line of the metal element. The motorized filter wheel is controllably connected to the control system so that by controlling the motorized filter wheel to select a narrow-band filter corresponding to the measured metal element to filter out stray light in other bands and select the characteristic spectrum of the metal element .

The spatial filter is an optical slit with a length of 1-5 mm and a width of 50 μm-100 μm, and the upper and lower spatial positions of the spatial filter are adjustable.

The data collector in the analyzer also has a WiFi and/or Bluetooth transmission function, and the data collector stores measurement results and transmits data wirelessly.

A kind of detection method that can be used for the portable elemental analyzer of field investigation, comprises the following steps,

1) According to the pH value measured in the buffer chamber or the experimental calibration value of the unacidified sample and the standard acid solution, the speed of the two single-channel peristaltic pumps is controlled to adjust the mixing ratio of the sample to be tested and the standard acid solution, so that the pH of the solution after mixing value is 1;

2) After mixing, the solution enters the catheter from the buffer cavity under the pressure of the single-channel peristaltic pump, and the buffer ball in the catheter further weakens the pulsation of the solution;

3) The control system controls the power supply composed of lithium batteries and transformers to provide working voltage to the glow discharge atomizer and controls the electric injection valve to push down to compress the air bag, speed up the flow rate of the solution, and make the solution spray out from the glass capillary to automatically ignite;

4) The control system controls the rotation of the electric filter wheel to select the narrow-band filter corresponding to the measured metal element to filter out stray light in other bands, and select the characteristic spectrum of the metal element;

5) The control system controls the installation of a three-dimensional adjustment device for the excitation light source of the electrolyte discharge plasma to realize the relative displacement of the electrolyte discharge plasma excitation light source and the optical path collection and filter sorting system, and obtain the best signal of the characteristic spectrum of the metal element;

6) The photomultiplier tube in the data processing system collects the light transmitted through the optical collection and filter sorting system and converts it into an electrical signal. After being amplified by the current amplifier, the data is stored by the data collector, and the stored data is transmitted to the computer through the Bluetooth function. or other terminal equipment and analyze and process the data;

7) Repeat steps 4, 5 and 6 until the data of the predetermined elements are measured.

Compared with prior art, the beneficial effect of the present invention is:

The invention provides a metal element analysis device which does not need to acidify samples in advance, does not need carrier gas, has more stable discharge, is easy to operate, has cheap equipment and is small in volume.

The detection method of the invention has the advantages of automatic detection, simple operation, strong field adaptability, and greatly improves field detection speed and accuracy.

Description of drawings

Fig. 1 shows the structural representation of a kind of portable element analyzer of the present invention;

Figure 2 is a schematic diagram of the structure of the sampling system.

Detailed ways

The present invention will be described in further detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention.

As shown in Figure 1-2, a kind of portable elemental analyzer of the present invention comprises: sampling system, electrolyte discharge plasma generation system, optical path collection and filter sorting system, data processing system and control system; The electrolyte discharge plasma generation system includes a power supply composed of a lithium battery and a transformer, a transformer 16, and a glow discharge atomizer 1. The optical path collection and filtering and sorting system includes a double-convex lens 2, a spatial filter 3, and plano-convex lenses 4 and 6. , and narrow-band optical filter 5, described light path collection and filter light sorting system comprise photomultiplier tube 7 and current amplifier 8, and transformer 17, data processing system is the data collector 9 with bluetooth function, described control The line is a controller, such as a computer 10, and the sampling system includes single-channel peristaltic pumps 11, 12, 15, sample buffer chamber 13, sample injection buffer and plasma auxiliary generation device 14, that is, single-channel peristaltic pumps 11, 12 , 15, sample buffer cavity 13, and sample injection buffer and plasma auxiliary generation device 14 form the sampling system of the analyzer, the action of single channel peristaltic pump 11,12,15 and plasma auxiliary generation device in the sampling system is determined by A control system, such as a computer 10 controls.

The electrolyte discharge plasma generation system of the analyzer is composed of an electrolyte glow discharge atomizer 1 and a transformer 16, an additional 12V lithium battery provides an input voltage, and the high voltage output by the transformer 16 provides a working voltage for the discharge system. The output voltage is controlled by computer 10 . That is, the entire elemental analyzer is powered by a 12V lithium battery. Lithium batteries and transformers provide working voltage for the glow discharge atomizer, and perform glow discharge on the samples entered by the sample introduction system to generate discharge plasma and emit characteristic spectra of elements.

The optical collection and filter sorting system composed of biconvex lens 2, spatial filter 3, plano-convex lenses 4 and 6, and narrow-band filter 5 collects the characteristic spectral lines of elements, and is composed of photomultiplier tube 7, current amplifier 8, and The data processing system composed of the Bluetooth-enabled data collector 9 converts the spectral signals collected by the optical system into electrical signals for collection and storage.

The data collector 9 and the computer 10 are the data storage, transmission and calculation and analysis centers of the entire analyzer. The computer controls the sampling system, the electrolyte discharge plasma generation system, and simultaneously controls the electric filter in the optical collection and filter sorting system. The rotation of the film wheel selects the narrow-band filter corresponding to the metal element to be measured and the output voltage of the control transformer 17 provides the working voltage for the photomultiplier tube 7 . The data collected and stored by the data collector is transmitted to a computer or other terminal equipment through Bluetooth for data analysis and processing, so as to obtain the concentration of metal elements in the sample to be tested.

In this scheme, the electrolyte glow discharge with low power consumption, no auxiliary gas and working under atmospheric pressure is used as the excitation source, which has greater portability advantages than other plasma excitation sources such as ICP, MIP and DBD, and is especially suitable for portable instrument. According to this portable instrument, a portable metal element analyzer for field survey can be realized, and it can provide on-site rapid measurement equipment for field survey of metal ore sources such as potassium ore and lithium ore in salt lakes, which has great application value.

The elements determination process of the elemental analyzer based on the above scheme is as follows:

The computer 10 controls the rotational speed of the single-channel peristaltic pumps 11 and 12 in the sampling system, respectively pumps the sample to be tested and the standard acid solution into the sample buffer chamber 13 and forms a sample to be tested with a pH value of 1 in the sample buffer chamber 13. The test sample enters the electrolyte discharge atomizer 1 through the plasma auxiliary generating device 14, and the computer 10 controls the power supply composed of a lithium battery and a transformer 16 to provide an operating voltage for the electrolyte discharge plasma generation system and controls the electric control on the air bag 20. The injection valve 21 is pushed downwards, so that the sample to be tested is ejected from the upper end of the capillary glass tube to automatically ignite and generate discharge plasma without pre-conditioning the sample to be tested, which simplifies the detection steps, and the automatic ignition further improves the convenience of field operation sex.

The characteristic spectral lines of the elements emitted by the plasma pass through the optical path collection and filter sorting system composed of biconvex lens 2, spatial filter 3, plano-convex lenses 4 and 6, and narrow-band filter 5, and enter the photomultiplier tube 7 to convert into electrical signals After being amplified by the current amplifier 8, the data is collected and stored by the data collector 9, and the data is transmitted to the computer 10 or other terminal equipment through its Bluetooth function to calculate the concentration of the metal element to be measured.

The sampling system in the elemental analyzer uses two single-channel peristaltic pumps to pump the sample to be tested and the acid solution into the catheter, and the acid solution and the sample to be tested are collected in the sample buffer chamber by controlling the speed of the two peristaltic pumps to form a pH of 1 standard sample solution, the standard sample enters the glow discharge atomizer after being stabilized in a catheter with a buffer ball. The present invention uses the sampling structure of two single-channel peristaltic pumps to introduce the unacidified sample to be tested and the standard acid solution into the conduit, so that the sample does not need to be pre-acidified, and then passes through the conduit with the buffer ball, so that the sample is more stable in the conduit Flow, and finally enter the electrolyte discharge plasma generation system, making the discharge more stable.

At the same time, the elemental analyzer uses a plasma-assisted generating device composed of an air bag with an electronically controlled injection valve, and realizes automatic ignition through a computer-controlled valve.

The optical path system of the element analyzer uses a spatial filter to extract the spectral signal of the spectral emission region of the metal element in the discharge plasma, which improves the signal-to-background ratio of signal reception, thereby improving the detection sensitivity of the analyzer.

Since the glow discharge plasma emission spectrum of the electrolyte is less, and the spectral line separation of different metal elements is wider, the elemental analyzer uses a narrow-band filter to replace the traditional monochromatic spectrometer, making its structure simpler and smaller. Smaller, more convenient to operate, and the product price is lower.

The elemental analyzer uses a quartz lens to collect optical signals, supplemented by narrow-band filters and photomultiplier tubes to select characteristic spectral signals and convert them into electrical signals, which are collected and processed by the subsequent data processing system to ensure detection accuracy. The optical path system and the data processing system are smaller in size, easy to integrate, and reduce the cost of the detection device at the same time.

The specific internal structure of the elemental analyzer is as follows: the single-channel peristaltic pumps 11 and 12 in the sampling system communicate with the buffer chamber 13, and are connected to the electrolyte discharge plasma through a conduit 19 in which a plurality of buffer balls 18 are placed. The capillary glass tube of the system, the plasma-assisted generating device includes the air bag 20 connected in series between the catheter and the capillary glass tube, and the air bag 20 is provided with a controllable connection with the control system The electronically controlled injection valve 21; the optical path collection and filtering and sorting system includes a biconvex lens 2 arranged along the optical path, a spatial filter 3, a front plano-convex lens 4, a narrow-band filter 5 and a rear plano-convex lens 6. The emission spectrum emitted by the plasma is collected by the lenticular lens 1 located in the plasma and converged and imaged to the spatial filter 3 located behind the lenticular lens 1, such as the plasma is at 2f1 in front of the lenticular lens 1, and the spatial filter is located behind the lenticular lens 2f1 to form an image of equal size, the negative glow region of the main discharge area of the plasma is selected by the spatial filter, and then the parallel light spectrum of the negative glow region is converged by the front plano-convex lens 4 located at f2 behind the spatial filter 3 to the narrow-band filter, and then the characteristic spectrum of the selected metal element is collected and converged by the rear plano-convex lens 6 to the photosensitive surface of the photomultiplier tube 7 behind the rear plano-convex lens 6 . The focal length f1 of the biconvex lens is 3cm-10cm, the front plano-convex lens and the rear plano-convex lens are exactly the same, the focal length f2 is 3cm-10cm, and the biconvex and plano-convex lenses are made of fused silica. The data processing system includes a photomultiplier tube 7, a current amplifier 8 and a data collector 9 with WiFi and Bluetooth functions, which are used to obtain and store the current intensity of each element, and transmit the stored data to a computer 10 or Other terminal equipment, so as to quantitatively analyze the content of metal elements in it. At the same time, the waste liquid is discharged into the waste liquid pool through the single-channel peristaltic pump 15 .

That is, the unacidified sample to be tested and the acid solution enter the catheter through a single-channel peristaltic pump, and the acid solution and the sample to be tested are collected in the sample buffer chamber by controlling the speed of the two peristaltic pumps to form a standard sample solution with a pH of 1. After the steady flow of the catheter with the buffer ball enters the glow discharge atomizer, the present invention uses the sampling structure of two single-channel peristaltic pumps to introduce the unacidified sample to be tested and the acid solution into the catheter, so that the sample does not need to be pre-acidified. Then through the conduit with buffer balls, the sample flows more smoothly in the conduit, and finally enters the electrolyte discharge plasma generation system, making the discharge more stable.

Preferably, the sampling system includes two single-channel peristaltic pumps, a catheter equipped with a buffer ball, a sample buffer chamber and a plasma-assisted generation device, the plasma-assisted generation device includes an air bag with an automatic valve, the The actions of the peristaltic pump and the plasma auxiliary generating device are controlled by the control system.

Preferably, the narrow-band filter is a narrow-band filter on a motorized filter wheel, and the motorized filter is controllably connected to the control system to select the corresponding filter wheel by computer control. The narrow-band filter for measuring metal elements filters out stray light in other bands, and selects the characteristic spectrum of metal elements.

Wherein, the width of the spatial filter is adjustable within the range of 50 μm to 100 μm, and the function of the spatial filter is to image the plasma at the location of the spatial filter through a biconvex lens, and then to the main discharge area of the discharge plasma. space selectivity. At the same time, the electrolyte discharge plasma generating system is set on a support frame that can be adjusted in height and front and back.

Preferably, the biconvex lens, the spatial filter, the front plano-convex lens, the narrow-band filter, the rear plano-convex lens and the photomultiplier tube are fixedly integrated into a cage coaxial system to ensure that all optical devices are coaxial and fixed in position, facilitating adjust.

Preferably, the elemental analyzer also includes a data collector with bluetooth function, the data collector is connected with the current amplifier, collects and stores data, and transmits data to an external computer or other terminal equipment through the bluetooth function to facilitate data analysis with processing.

The invention combines the electrolyte discharge plasma generation system with a set of three-dimensionally adjustable support frames, and adjusts the relative displacement between the plasma generation system and the optical path collection and filtering and sorting system through the control system, and at the same time adjusts the spatial filter Width, observe the strength of the signal, so that the best discharge position can be selected, and there is no need to adjust the subsequent optical path collection device, which makes the operation of the detection device more convenient. The space filter is used to spatially select the plasma area, and the main discharge area of the plasma, that is, the negative glow area of the plasma, is selected by adjusting the relative displacement between the plasma generation system and the optical path collection and filter sorting system. Let the effective light signal fully enter the photomultiplier tube, thereby improving the signal-to-background ratio of signal reception, and improving the detection sensitivity of the element analyzer. The detection device of the spatial filter and the filter makes the analyzer relatively There are photoelectric detection devices that are smaller and less expensive to equip.

In summary, the optical path collection and filtering and sorting system of the element analyzer that can be used for field surveys of the present invention is different from the detection technology that uses a monochromatic spectrometer plus a photomultiplier tube in the prior art. The present invention uses a quartz lens , spatial filter and narrow-band filter to replace the monochromatic spectrometer, which makes the whole detection system cheaper and smaller in the case of the same high spectral resolution, combined with the three-dimensional adjustable electrolyte discharge plasma generation system , making the detection system easier to operate.

The specific detection method includes the following steps,

1) According to the pH value measured in the buffer chamber or the experimental calibration value of the unacidified sample and the standard acid solution, the speed of the two single-channel peristaltic pumps is controlled to adjust the mixing ratio of the sample to be tested and the standard acid solution, so that the pH of the solution after mixing The value is 1; that is, a pH meter that communicates with the control system can be installed in the buffer chamber to automatically adjust the speed coordination of the two single-channel peristaltic pumps;

2) After mixing, the solution enters the catheter from the buffer cavity under the pressure of the single-channel peristaltic pump, and the buffer ball in the catheter further weakens the pulsation of the solution;

3) The control system controls the power supply composed of lithium batteries and transformers to provide working voltage to the glow discharge atomizer and controls the electric injection valve to push down to compress the air bag, speed up the flow rate of the solution, and make the solution spray out from the glass capillary to automatically ignite;

4) The control system controls the rotation of the electric filter wheel to select the narrow-band filter corresponding to the measured metal element to filter out stray light in other bands, and select the characteristic spectrum of the metal element;

5) The control system controls the installation of a three-dimensional adjustment device for the excitation light source of the electrolyte discharge plasma to realize the relative displacement between the excitation light source of the electrolyte discharge plasma and the optical path collection and filter sorting system, and obtain the best signal of the characteristic spectrum of the metal element.

6) The photomultiplier tube in the data processing system collects the light transmitted through the optical collection and filter sorting system and converts it into an electrical signal. After being amplified by the current amplifier, the data is stored by the data collector, and the stored data is transmitted to the computer through the Bluetooth function. or other terminal equipment and analyze and process the data;

7) Repeat steps 4, 5 and 6 until the data of the predetermined elements are measured.

The element analyzer of the present invention realizes automatic adjustment of liquid pH value, automatic ignition and continuous measurement, and at the same time, can automatically adjust optical filters to realize sequential measurement of multiple elements, effectively improving measurement efficiency and reducing use cost.

The above is only a preferred embodiment of the present invention, it should be pointed out that, for those of ordinary skill in the art, without departing from the principle of the present invention, some improvements and modifications can also be made, these improvements and Retouching should also be regarded as the protection scope of the present invention.

Claims (1)

1. a kind of Portable element analyzer available for field exploration, which is characterized in that including：Sampling system, electrolyte are put Electro-plasma generation system, light path is collected and optical filtering separation system, data processing system and control system；The sampling system Introduce the sample into electrolyte discharge plasma generation system carry out glow discharge send out component spectrum, by the light path collect and Optical filtering separation system acquires and reaches data processing system, is finally shown and is acquired by the control system, the control At system control sampling system, electrolyte discharge plasma generation system, light path collection and optical filtering separation system and data Reason system, the sampling system include two not-acidified sample and standard acid to be pumped into the single-pass of cushion chamber respectively Road peristaltic pump, one end connect the capillary glass that the other end is connected to electrolyte discharge plasma generation system with the cushion chamber The conduit of glass pipe, multiple buffering balls being accommodated in the conduit and plasmaassisted generation device, described etc. Gas ions auxiliary generation device includes being serially connected in air bag between conduit and glass capillary, be arranged on the air bag and with institute The automatically controlled introduction valve that the control system stated controllably connects, the rotating speed of the single channel peristaltic pump are controlled by the control system.