CN205826395U - A kind of dielectric barrier discharge preenrichment device surveying arsenic for atomic fluorescence method - Google Patents

Abstract

The utility model provides a dielectric barrier discharge pre-enrichment device for measuring arsenic by atomic fluorescence method, comprising a hydride generator, a dielectric barrier discharge reactor, a power supply, a gas circuit and an atomic fluorescence spectrometer. The atomic fluorescence spectrometry method for pre-enrichment of arsenic, including the production of arsenic hydride, in the argon-oxygen mixed gas atmosphere, the discharge reaction occurs in a dielectric barrier discharge reactor, and the capture of arsenic is completed; in the argon-hydrogen mixed gas atmosphere, the dielectric A discharge reaction occurs in the barrier discharge reactor, and the release of arsenic is completed, and the content of the released arsenic is analyzed by an atomic fluorescence spectrometer. The device solves the difficulty of controlling the capture and release of arsenic by a dielectric barrier discharge device, and its advantage is that it can be directly connected in series with a spectrometer to achieve online high-efficiency enrichment of trace arsenic in the sample and accurate and stable analysis.

Description

A dielectric barrier discharge pre-concentration device for measuring arsenic by atomic fluorescence method

technical field

The utility model relates to the field of chemical analysis, in particular to a dielectric barrier discharge pre-enrichment device for measuring arsenic by atomic fluorescence method.

Background technique:

Arsenic is a harmful element, and inorganic arsenic has been identified as a primary carcinogen by the International Cancer Research Center (IARC). At present, the problem of arsenic pollution in the environment has become very prominent due to excessive mining of mineral deposits, discharge of three wastes, and use of agricultural inputs containing arsenic. In 2014, the Ministry of Environmental Protection and the Ministry of Land and Resources released the National Soil Pollution Survey Bulletin. The results showed that the overall national soil environment situation is not optimistic, and some areas have serious soil pollution. The total point exceeding the standard rate reached 16.1%. Arsenic is the third largest pollutant. Studies have shown that drinking water has always been the main source of exposure to arsenic ingestion by the general public, followed by food. Therefore, arsenic in water is an indicator of pollutants routinely detected in the fields of environment, agriculture, and sanitation. At present, the standard methods used for the detection of arsenic in water mainly include GB/T7485-1987 "Determination of total arsenic in water quality, silver diethyldithiocarbamate spectrophotometric method", GB/T 11900-1989 "Determination of trace arsenic in water quality Potassium borohydride-silver nitrate spectrophotometry", SL 327.1-2005 "Determination of arsenic in water quality. Atomic fluorescence spectrometry", HY/T152-2013 "Atomic fluorescence spectrometry for the speciation analysis of trivalent arsenic and pentavalent arsenic in seawater", HJ 694-2014 "Atomic Fluorescence Method for Determination of Mercury, Arsenic, Selenium, Bismuth and Antimony in Water Quality", etc. Among these standards, atomic fluorescence spectroscopy (AFS) is the most commonly used method, and AFS is also one of the few large-scale instruments and equipment with independent intellectual property rights in my country. However, since the arsenic in water is mostly trace or ultra-trace, at the μg/L level or sub-μg/L level, if the trace arsenic can be effectively pre-enriched before entering the detector, it can effectively reduce The limit of detection (LOD) of the instrument method, thereby improving the sensitivity of the spectroscopic instrument for the analysis of trace arsenic in water. At present, some studies use methods such as solid phase extraction (SPE) and solid phase adsorption of nanomaterials to pre-enrich trace arsenic in water, but all of them require separate treatment of samples before detection. The process is relatively complicated and cannot be reused. The cost is high, so the actual usage rate is not high.

Dielectric barrier discharge (DBD), also known as silent discharge, is a typical non-equilibrium AC gas discharge technology, which can generate non-equilibrium micro-plasma at normal temperature and pressure, and is also a low-temperature plasma (Non-thermal plasma , NTP). DBD devices are generally divided into flat plate type and coaxial type, with simple structure, usually only need to place barrier media such as glass, quartz, ceramics or polymers between the two electrodes, and the discharge area is filled with argon, helium, nitrogen, oxygen, etc. Or mix the working gas. When the high-voltage alternating current applied across the electrodes exceeds the breakdown voltage of Paschen, the working gas is broken down to generate electrons, which excite or dissociate gas molecules, and generate ultraviolet radiation and a large number of free radicals, ions, and excited states. NTP of chemically active substances such as atoms and molecular fragments. The radiation and active substances produced by DBD can provide enough energy for the required chemical reaction, which is also the basis of DBD application. At present, DBD has become a hot spot in the research of discharge technology because of its simplicity, low cost, easy control, low energy consumption, and wide application. In terms of atomic spectroscopic analysis, DBD is mostly used as an atomizer for atomic absorption spectrometer (AAS), atomic emission spectrometer (AES), AFS, etc. At present, there is no report on the use of DBD as an arsenic capture device for spectral analysis.

Invention content:

The purpose of this utility model is to address the above problems and provide a dielectric barrier discharge pre-concentration device for measuring arsenic by atomic fluorescence method. It can be directly connected in series with the spectrometer to realize the online high-efficiency enrichment and accurate and stable analysis of trace arsenic in the sample.

The dielectric barrier discharge pre-enrichment device for measuring arsenic by atomic fluorescence method provided by the utility model includes a hydride generator, a dielectric barrier discharge reactor, a power supply, a gas circuit and an atomic fluorescence spectrometer. The dielectric barrier discharge reactor consists of two It is composed of a coaxial quartz tube, copper coil (ground wire), and copper rod electrode (high voltage electrode). On the outer surface of the tube, the copper rod electrode is overhead and placed in the center of the inner quartz tube cavity; the gas path includes argon source, oxygen source, hydrogen source, argon source three-way connection four-way mixer and dielectric barrier discharge reaction The reactor, the oxygen source and the hydrogen source are all connected to the dielectric barrier discharge reactor, and the gas outlet of the dielectric barrier discharge reactor is connected to the atomic fluorescence spectrometer.

The hydride generator includes a peristaltic pump 1 , a peristaltic pump 2 , a four-way mixer 3 , a reaction ring 5 and a gas-liquid separator 6 .

The air velocity of the argon 4, oxygen 11 and hydrogen 12 is all controlled by a mass flow meter.

The copper coil is connected to the ground wire 9 of the power supply 7 , and the copper rod electrode is connected to the high voltage electrode 8 of the power supply 7 .

The gas path is connected by a polytetrafluoroethylene hose.

Beneficial effects of the invention:

The device has a simple structure, which solves the difficult problem that the dielectric barrier discharge device captures and releases the arsenic element that is difficult to control, and can be directly connected in series with the spectrometer; the remarkable advantage of the utility model is that it solves the difficult problem that the dielectric barrier discharge device captures and releases the arsenic element that is difficult to control , which can be directly connected in series with spectrometers to achieve online high-efficiency enrichment and accurate and stable analysis of trace arsenic in samples.

Description of drawings:

Figure 1: Structural diagram of the enrichment device for measuring arsenic by atomic fluorescence method.

Among them, 1 is a sample peristaltic pump, 2 is a reagent peristaltic pump, 3 is a four-way mixer, 4 is an argon gas source, 5 is a reaction ring, 6 is a gas-liquid separator, 7 is a power supply, and 8 is a copper rod electrode (high voltage electrode), 9 is a copper coil (ground wire), 10 is a dielectric barrier discharge reactor, 11 is an oxygen source, 12 is a hydrogen source, and 13 is an atomic fluorescence spectrometer.

detailed description:

The utility model provides an enrichment device for measuring arsenic by atomic fluorescence method, which includes a hydride generator, a dielectric barrier discharge reactor 10, a power supply 7, a gas circuit and an atomic fluorescence spectrometer 13. The dielectric barrier discharge reaction Device 10 is made up of two coaxial quartz tubes, copper coil (ground wire) 9, copper rod electrode (high voltage electrode) 8, and described coaxial quartz tube is placed in the center of outer layer quartz tube overhead by inner layer quartz tube, and described The copper coil 9 is wound on the outer surface of the outer quartz tube, and the copper rod electrode 8 is placed overhead in the center of the inner quartz tube cavity; the hydride generating device includes a sample peristaltic pump 1, a reaction reagent peristaltic pump 2, and a four-way mixer 3. Reaction ring 5, gas-liquid separator 6; said gas path includes argon source 4, oxygen source 11, hydrogen source 12, argon source 4 three-way connection four-way mixer 3 and dielectric barrier discharge reactor 10, Both the oxygen source 11 and the hydrogen source 12 are connected to the dielectric barrier discharge reactor 10 , and the gas outlet of the dielectric barrier discharge reactor 10 is connected to the atomic fluorescence spectrometer 13 .

Embodiment one

When the standard solution containing arsenic is passed into the sample peristaltic pump 1, it is mixed with the potassium borohydride solution in the reaction reagent peristaltic pump 2 in the four-way mixer 3, and the 600mL/min argon gas introduced by the three-way connection of the argon source 4 is brought in The reaction ring 5 produces arsenic hydride, and enters the gas-liquid separator 6 to complete the gas-liquid separation. Under the condition that 40 mL/min oxygen is fed into the oxygen source 11 and the voltage of the power supply 7 is set at 9.2 kV, the dielectric barrier discharge reactor 10 The capture of arsenic is completed; then the argon source 4 is connected to the argon gas to purge for 180s, and then the hydrogen gas source 12 is supplied with 200mL/min hydrogen gas. At this time, the voltage of the power supply 7 is 9.5kV, and the release of arsenic is completed; The gas enters the atomic fluorescence spectrometer 13 along with the carrier gas. Under optimal conditions, the linear range of measuring arsenic is 0.05μg/L to 5μg/L, the regression coefficient of the standard curve is above 0.995, and the detection limit of arsenic can reach 1.0ng/L when the sample volume is 20mL, and it can be measured many times. The relative standard deviation is within 5%, and an enrichment efficiency of more than 8 times can be achieved.

Embodiment two

Taking the arsenic-containing water sample (national standard GBW08605) as an example, the dielectric barrier discharge pre-concentration device of the present invention is connected in series with the atomic fluorescence spectrometer, and other conditions are the same as in the first embodiment. The content of arsenic in the measured sample was 499±4 micrograms/liter, the average value was within the standard value of 500±8 micrograms/liter of the standard substance, and the relative standard deviation of three determinations was 0.8%.

The above embodiments only describe preferred implementations of the present utility model, and are not intended to limit the scope of the present utility model. All modifications and improvements should fall within the scope of protection determined by the claims of the present invention.

Claims (4)

1. atomic fluorescence method surveys a dielectric barrier discharge preenrichment device for arsenic, including hydride generation system, dielectric barrier discharge reaction Device, power supply, gas circuit and atomic fluorescence spectrometer, described dielectric barrier discharge reactor is by two coaxial quartz tubes, copper coil, copper rod electricity Pole forms, and described coaxial quartz tube is placed in outer layer quartz ampoule central authorities by layered quartz tube is built on stilts, and described copper coil is wrapped in outside outer layer quartz ampoule Surface, described copper rod is built on stilts is placed in layered quartz tube cavity central authorities；Described gas circuit includes argon gas source, source of oxygen, hydrogen source, argon Source threeway connects four-way blender and dielectric barrier discharge reactor, source of oxygen and hydrogen source equal access medium barrier discharge reactor, medium The gas outlet of barrier discharge reactor connects atomic fluorescence spectrometer.

A kind of atomic fluorescence method the most as claimed in claim 1 surveys the dielectric barrier discharge preenrichment device of arsenic, it is characterised in that: described hydrogen Compound generating means includes peristaltic pump, four-way blender, reaction ring, gas-liquid separator.

A kind of atomic fluorescence method the most as claimed in claim 1 surveys the dielectric barrier discharge preenrichment device of arsenic, it is characterised in that: described copper Coil accesses the ground wire of power supply, and copper rod accesses the high-field electrode of power supply.

A kind of atomic fluorescence method the most as claimed in claim 1 surveys the dielectric barrier discharge preenrichment device of arsenic, it is characterised in that: described gas Road uses teflon hose to connect.