CN111208115B - Detection method for directly measuring trace halogen - Google Patents
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Abstract
The invention discloses a detection method for directly measuring trace halogen. The detection method comprises the following steps: mixing a reaction reagent with a solution to be detected to oxidize halogen ions in the solution to be detected to form a volatile simple substance of halogen, and introducing the simple substance of halogen into a detection device for detection, thereby realizing the detection of trace halogen. The detection method provided by the invention greatly improves the analysis sensitivity of a detection device (such as an inductively coupled plasma atomic emission spectrometer) to the halogen, simultaneously reduces the interference of a coexisting matrix to the halogen to be detected, can be successfully applied to the detection of trace halogen in a water sample, and has very wide application value in the test industry.
Description
Technical Field
The invention relates to a sample introduction device, in particular to a detection method for directly measuring trace halogen, and belongs to the technical field of detection systems.
Background
The existing analytical methods for measuring trace halogen mainly comprise photometry, ion chromatography, ICP-MS and the like, wherein the photometry is complex to operate, low in analysis speed and narrow in linear range of elements to be measured; ion chromatography takes a minimum of more than ten minutes for analyzing a sample, trace amounts of chlorine, bromine and iodine with higher concentration can be simultaneously measured, but for trace amounts of iodine, an electrochemical detector (such as an amperometric detector) and a corresponding chromatographic column are used for separately measuring, so that the analysis efficiency is further reduced. ICP-MS has polyatomic ion mass spectrometry interference when measuring bromine, and in addition, ICP-MS can tolerate a sample with low salinity, so an analysis method which is simple and convenient to operate, wide in linear range, high in salinity tolerance and capable of rapidly and simultaneously measuring halogen is urgently needed to be established. The inductively coupled plasma atomic emission spectrometry (ICP-OES) has the characteristics, and if the ICP-OES can be applied to analyzing trace halogen in a sample, the analysis efficiency can be greatly improved, and the application range of the emission spectrometry can be enlarged.
ICP-OES is one of the multi-element analytical instruments widely used at present, but the ICP-OES is less applied to the aspect of measuring nonmetal, particularly halogen, and the halogen belongs to high ionization energy elements, and the energy of plasma is limited, so that only a few atoms and ions in a sample can be excited, the sensitivity for measuring the halogen is low, the detection limit is high, and the detection limit is not enough for measuring trace halogen in the sample, and the environmental monitoring, the medicine quality safety and the chemical product analysis all require the used analytical instrument to have low detection limit on the halogen, and in addition, the accurate measurement of the trace halogen in a high-salt solution requires that the used analytical method simultaneously has the advantages of low detection limit and high salinity tolerance, thereby providing a challenge for the conventional analytical method.
The sample introduction system is an important component of ICP-OES, and the detection limit and sensitivity of the instrument are directly related to the performance of the sample introduction system. The conventional sampling system comprises an atomizing chamber, an atomizer, a peristaltic pump and a pump pipe, wherein the concentric atomizer is a core part of the sampling system, and the concentric atomizer has the advantages of simple structure, convenient operation and the like, but the concentric atomizer exists like: low sample injection (generally, only about 3% of aerosol enters ICP, most of solution flows off as waste liquid), easy blockage, strict requirements on test solution (high-salt solution is easy to deposit at a nozzle), and the like.
The liquid sample introduction is the most common and mature method of ICP-OES at present, the atomization efficiency is only about 1-5% when the conventional liquid sample introduction is adopted, most of the solution flows off as waste liquid, the atomization efficiency is low and is not more than 1%, so that the detection performance of the ICP-OES can not meet the test requirement when the ICP-OES analyzes elements (such as halogen) with low sensitivity, and a sample introduction system becomes a weak link of an instrument. The above aspects result in ICP-OES not being useful for determining trace amounts of halogen in a sample.
Disclosure of Invention
The invention mainly aims to provide a detection method for directly measuring trace halogen so as to overcome the defects in the prior art.
In order to achieve the purpose, the technical scheme adopted by the invention comprises the following steps:
the embodiment of the invention provides a detection method for directly measuring trace halogen, which comprises the following steps: mixing a reaction reagent with a solution to be detected to oxidize halogen ions in the solution to be detected to form a volatile halogen simple substance, and introducing the halogen simple substance into a detection device for detection, thereby realizing the detection of trace halogen.
In some more specific embodiments, the detection method specifically includes: firstly, a reaction reagent and a solution to be detected are respectively input into a reaction pipeline through a sample inlet pipe, so that the reaction reagent and the solution to be detected react in the reaction pipeline to form a mixed system, the mixed system is conveyed to a gas-liquid separation unit through the reaction pipeline, and then gas-phase substances in the mixed system are separated and led out to a detection device in the gas-liquid separation unit.
In some more specific embodiments, the detection method specifically includes: and introducing inert gas into the reaction pipeline to drive the mixed system in the reaction pipeline into a gas-liquid separation unit.
Preferably, the inert gas comprises high purity argon having a purity greater than 99.99%.
In some specific embodiments, the gas-liquid separation unit of the detection method includes a first cavity and a second cavity that are communicated with each other, the first cavity is located above the second cavity, and a gas-liquid separation membrane is disposed at an opening of the first cavity; the reaction pipeline is directly communicated with the first cavity, gas-phase substances in the mixing system can be led out from the opening of the first cavity, and liquid-phase substances in the mixing system can be led into the second cavity.
In some specific embodiments, in the detection method, an inner diameter of the first cavity is larger than an inner diameter of the second cavity, and the first cavity is smoothly connected to the second cavity.
In some specific embodiments, in the detection method, the first cavity is further communicated with a third cavity for collecting gas-phase substances, and the gas-phase substances in the first cavity can enter the third cavity after being filtered by the gas-liquid separation membrane and are introduced into the detection device through the third cavity.
Further, the reaction reagent comprises an oxidizing agent and an acid, and the solution to be detected contains halogen ions.
Further, the oxidant comprises any one or the combination of more than two of potassium dichromate, hydrogen peroxide, sodium nitrite, potassium permanganate and potassium persulfate.
Further, the acid comprises any one or a combination of more than two of nitric acid, hydrochloric acid and sulfuric acid.
The standard redox potential of the selected oxidizing agent and the halide ion to be oxidized should be considered when specifically selecting the oxidizing agent, wherein the type and concentration of the oxidizing agent and the acid can be optimized by specific experiments, and it should be noted that the maximum tolerance of the sample tube to the acid should be considered when selecting the acid concentration.
In some more specific embodiments, the halide ion is iodide and the reagent comprises NaNO 2 And nitric acid, said NaNO 2 The concentration of the solution is 1-100 mmol/L, and the concentration of the nitric acid is 0.2-2 mol/L.
In some more specific embodiments, the halide ions are iodide and bromide and the reagent comprises KMnO 4 And HNO 3 Said KMnO 4 The concentration of the solution is 1-50 mmol/L, and the concentration of the nitric acid is 1-4 mol/L.
Specifically, on the premise of satisfying the test effect, the lower the concentration of the same oxidant and the acid, the better.
Specifically, when the iodine is measured, the reaction reagent is preferably 10mmol/LNaNO 2 And 1M nitric acid; when bromine and iodine are simultaneously measured, the reaction reagent is preferably KMnO with the concentration of 2mmol/L 4 And 4mol/L of HNO 3 。
The embodiment of the invention provides a detection system for measuring trace halogen, which comprises a sample introduction device and a detection device, wherein the detection device is connected with the sample introduction device, and the sample introduction device comprises: a reaction unit and a gas-liquid separation unit;
the reaction unit comprises a reaction container, a reaction pipeline, a first sample introduction pipe and a second sample introduction pipe, wherein the reaction pipeline is respectively communicated with the reaction container, the first sample introduction pipe and the second sample introduction pipe, the first sample introduction pipe is used for inputting a reaction reagent into the reaction pipeline, the second sample introduction pipe is used for inputting a solution to be detected into the reaction pipeline, the reaction pipeline can be used for mixing and reacting the reaction reagent and the solution to be detected and can input a reacted mixed solution into the reaction container, the reaction container is provided with a reaction cavity which can be used for further reacting the reaction reagent in the mixed solution and the solution to be detected and separating a gaseous substance and a liquid substance in the reacted mixed solution, and a reaction cavity cover can be opened at an opening of the reaction cavity, wherein the reaction reagent can oxidize halogen ions into volatile simple halogen substances;
the gas-liquid separation unit comprises a gas-liquid separation membrane, the gas-liquid separation membrane is arranged at an opening of the reaction cavity and completely covers the opening of the reaction cavity, a third cavity formed by enclosing the gas-liquid separation membrane and the reaction cavity cover is arranged between the gas-liquid separation membrane and the reaction cavity cover, a gas leading-out port is arranged on the reaction cavity cover, and the detection device is connected with the gas leading-out port.
Further, the reaction cavity comprises a first cavity and a second cavity which are communicated with each other, and the first cavity is positioned above the second cavity; the reaction pipeline is directly communicated with the first cavity.
Furthermore, the inner diameter of the first cavity is larger than that of the second cavity, and the first cavity is smoothly connected with the second cavity.
Furthermore, the first cavity and the second cavity are both cylindrical cavities, the inner diameter of the first cavity is 8mm, the height of the first cavity is 30mm, and the inner diameter of the second cavity is 4mm, and the height of the second cavity is 15mm.
Furthermore, the reaction vessel is also connected with a waste liquid pipe, and the waste liquid pipe is directly communicated with the second cavity.
Furthermore, the waste liquid pipe, the first sample feeding pipe and the second sample feeding pipe are also connected with peristaltic pumps.
Further, the reaction pipeline is still connected with the air supply unit through the air duct, the air supply unit is used for the warp at least the air duct to leading-in inert gas in the reaction pipeline, and order about mixed liquid in the reaction pipeline gets into in the reaction cavity.
Furthermore, first advance appearance pipe and second advance appearance pipe still with the pump line connection, and the warp the pump line with reaction pipeline intercommunication, wherein, the air duct passes through the conversion head and is connected with pump line, reaction pipeline.
Further, the inner diameter of the reaction pipeline is smaller than the inner diameter of any one of the pump pipe, the first sampling pipe and the second sampling pipe, and the length of the reaction pipeline is 29mm.
Further, the separation membrane is embedded in the reaction cavity cover.
Furthermore, the sample feeding device further comprises a fixed support, and the reaction unit of the sample feeding device is fixedly arranged on the fixed support.
Further, the detection device comprises an inductively coupled plasma atomic emission spectrometer.
Compared with the prior art, the detection method for directly measuring the trace halogen provided by the embodiment of the invention can oxidize halogen ions in a solution to be measured into a volatile simple substance of halogen in advance, thereby realizing the detection of the trace halogen; the detection method greatly improves the measurement sensitivity of trace halogen, improves the detection limit of the trace halogen, and reduces the influence of a coexisting matrix on the measurement of the halogen; in addition, the detection system effectively improves the analysis sensitivity of the halogen, has very wide application value in the test industry, and simultaneously provides higher reference value for the analysis of other elements and element valence states.
Drawings
In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments described in the present application, and other drawings can be obtained by those skilled in the art without creative efforts.
FIG. 1 is a schematic diagram of a detection system for detecting trace amounts of halogen in accordance with an exemplary embodiment of the present invention.
Detailed Description
In view of the deficiencies in the prior art, the inventors of the present invention have made extensive studies and extensive practices to provide technical solutions of the present invention. The technical solution, its implementation and principles, etc. will be further explained as follows.
The detection system for detecting the trace halogen provided by the embodiment of the invention can be used for analyzing the trace bromine and iodine in the water body, and comprises a sample introduction device and a detection device, wherein the sample introduction device can simultaneously input a reaction reagent and a solution to be detected, and enables the reaction reagent and the solution to be detected to be mixed and react in advance in the sample introduction device, the reaction reagent can generate an oxidation-reduction reaction with halogen ions in the solution to be detected to oxidize the halogen ions in the solution to be detected into a volatile simple halogen substance, and the simple halogen substance is screened by a gas-liquid separation membrane and then is introduced into the detection device for detection, so that the detection of the trace halogen is realized.
One way to increase sensitivity in the emission spectrum is to improve the atomization of the sample and the atomization efficiency of the analyte by optimizing the sample injection system. Aiming at the problems of low sensitivity and high detection limit of the existing ICP-OES halogen determination, the invention uses a sample introduction device of trace halogen, the sample introduction device integrates three functions of sample introduction, reaction and gas-liquid separation, replaces an atomizer and an atomizing chamber in an ICP-OES conventional sample introduction system, and utilizes chemical reaction to oxidize halogen ions into volatile halogen simple substances for sample introduction when determining halogen, the efficiency of transmitting the volatile halogen simple substances to plasma is close to 100%, and the atomization efficiency are greatly improved, thereby greatly improving the sensitivity of the ICP-OES halogen determination. The chemical reaction is to react halogen ions with an oxidant under an acidic condition to generate a halogen elementary substance, and the standard redox potential of the selected oxidant and the halogen ions to be oxidized should be considered when the oxidant is specifically selected, wherein the types and concentrations of the oxidant and the acid can be optimized through specific experiments. In addition, the generated halogen simple substance can be separated from the sample solution through the gas-liquid separation unit of the sample introduction device, so that the interference of a sample matrix on the halogen determination is reduced while the effective sample introduction amount of the element to be detected is greatly improved. The invention specifically researches an analysis method for directly measuring trace halogen by ICP-OES, which comprises reaction conditions, test conditions and the like.
Specifically, the detection device may be a detection instrument such as an inductively coupled plasma atomic emission spectrometer (ICP-OES); the efficiency of transmitting the volatile halogen simple substance to the plasma of the detection instrument is close to 100%, and the atomization efficiency are greatly improved, so that the sensitivity of measuring trace halogen by ICP-OES can be greatly improved.
The sample introduction device of the detection system provided by the invention integrates three functions of sample introduction, reaction and gas-liquid separation, the halogen element ions are oxidized into volatile halogen element simple substances by using oxidation reaction, and the halogen element simple substances are introduced into the detection device for detection, so that the interference of a sample matrix on the detection of the halogen element is reduced while the analysis sensitivity of the element to be detected is greatly improved, and the detection system can be used for accurately and quickly analyzing trace halogen elements in a water body.
Specifically, a gas-liquid separation membrane in the sample introduction device separates the formed volatile simple halogen substance from the liquid mixed liquid, so that the analysis sensitivity of the element to be detected is greatly improved, and meanwhile, the interference factor on the determination of trace halogen is reduced.
Specifically, referring to fig. 1, a detection system for detecting trace halogen according to an exemplary embodiment of the present invention includes a sample injection device, the sample injection device mainly includes a reaction unit and a gas-liquid separation unit, the reaction unit is mainly used for inputting a reaction reagent and a solution to be detected, and mixing and reacting the reaction reagent and the solution to be detected, the reaction reagent includes an oxidant capable of oxidizing halogen ions into elemental halogen.
For example, the oxidizing agent may be any one or a combination of two or more of potassium dichromate, hydrogen peroxide, sodium nitrite, potassium permanganate, and potassium persulfate, and the acid may be any one or a combination of two or more of nitric acid, hydrochloric acid, and sulfuric acid. When the oxidant is specifically selected, the standard redox potential of the selected oxidant and the halogen ion to be oxidized (such as bromine and iodine ion) should be considered, wherein the types and concentrations of the oxidant and the acid can be optimized through specific experiments, and on the premise of meeting the test effect, the lower the concentration of the same oxidant and the acid is, the better the concentration is.
Specifically, the detection method specifically comprises the following steps:
firstly, assembling a sample introduction device for measuring trace halogen, which comprises a reaction unit and a gas-liquid separation unit, in place according to requirements;
secondly, connecting the first sample injection tube and the second sample injection tube of the reaction unit with a container for containing a reaction reagent and a solution to be detected respectively;
thirdly, connecting a gas outlet of the gas-liquid separator with a detection device (such as ICP-OES) through a pipeline;
fourthly, mixing the reaction reagent and the solution to be detected for reaction, then feeding the mixture into a pump pipe, continuously reacting the mixture through a reaction pipeline under the pushing of high-purity argon in a gas guide pipe, and then feeding the mixture into a reaction container;
and fifthly, introducing the halogen simple substance generated by the reaction into a detection device through a gas-liquid separation membrane for measurement to obtain a test result.
Specifically, the operating conditions of the ICP-OES also need to be optimized experimentally, and mainly include instrument conditions such as atomization gas flow, pump speed, radio frequency power, cooling gas flow, and the like, and when the ICP-OES is used for measurement, the radio frequency power should be as high as possible within the allowable range of the radio frequency power of the instrument (for example, the radio frequency power range of ICAP 6500DUO of seimeishiel corporation is 750-1350W, and the radio frequency power during iodine measurement can be 1300W), and because the ICP-OES has low measurement sensitivity on halogen, each spectral line should be selected in a horizontal or axial observation mode during analysis.
Specifically, the reaction unit comprises a first sample injection pipe 1, a second sample injection pipe 2, a pump pipe 3, a gas guide pipe 4, a reaction pipeline 5, a reaction container 6 and a waste liquid pipe 7, wherein the first sample injection pipe 1 and the second sample injection pipe 2 are communicated with the pump pipe 3 and are communicated with the reaction pipeline 5 through the pump pipe 3, the gas guide pipe 4 is communicated with the pump pipe 3 and the reaction pipeline 5 through a conversion head (or called as a conversion valve and comprises four conversion heads and a thin pump pipe), and the reaction pipeline 5 and the waste liquid pipe 7 are also communicated with the reaction container 6 respectively; the gas guide tube 4 is further connected to a gas supply unit 12, and the gas supply unit 12 can introduce an inert gas (which may be high purity argon gas with a purity higher than 99.99%) into the reaction tube 5 through the gas guide tube 4, so as to drive a mixed solution formed by mixing the reaction reagent and the solution to be tested in the reaction tube 5 into the reaction container 6.
Specifically, the first sample injection pipe 1 may be connected to a container in which a reaction reagent is pre-stored, and may introduce the reaction reagent into the pump pipe 3, the second sample injection pipe 2 may be connected to a container in which a solution to be measured is pre-stored, and may introduce the solution to be measured into the pump pipe 3, and the reaction reagent and the solution to be measured enter the reaction pipeline 5 through the pump pipe 3, and are mixed and reacted in the reaction pipeline 5.
Specifically, the reaction container 6 has a reaction cavity for further reaction of the reaction reagent in the mixed solution and the solution to be detected and separation of gaseous substances and liquid substances in the mixed solution after reaction, and a reaction cavity cover 9 can be opened at an opening of the reaction cavity, wherein the reaction cavity comprises a first cavity and a second cavity which are coaxially arranged and communicated with each other, and the first cavity is positioned above the second cavity.
Specifically, this first cavity and second cavity are cylindrical cavity, the internal diameter of first cavity is greater than the internal diameter of second cavity, well upper portion at first cavity is provided with the inlet that is used for with 5 intercommunications of reaction line, be provided with the leakage fluid dram that is used for with waste liquid pipe 7 intercommunication in the lower part of second cavity, this reaction vessel 6 can guarantee to be input the mixed liquid full reaction in the reaction vessel, and can make the inside reaction cavity of reaction vessel 6 wash more easily, and can reduce the memory effect among the testing process.
Specifically, the inner diameter of the first cavity is 8mm, the height of the first cavity is 30mm, the inner diameter of the second cavity is 4mm, and the height of the second cavity is 15mm.
Specifically, the inner diameter of the pump tube 3 may be the same as the inner diameters of the first sample introduction tube 1 and the second sample introduction tube 2, the inner diameter of the reaction tube 5 is smaller than the inner diameter of any one of the first sample introduction tube 1, the second sample introduction tube 2 and the pump tube 3, the length of the reaction tube 5 is 29mm, the reaction tube may be helical, and the like, and the inner diameter of the reaction tube 5 is small, so that a small amount of a mixed solution formed by a reaction reagent and a solution to be measured can pass through the reaction tube and be sufficiently mixed and reacted; the length of the reaction channel 5 must not be too long, which would increase the memory effect during the detection.
Specifically, the first sampling tube 1 may be one tube or a plurality of tubes, and when the reaction reagents are a plurality of types, a plurality of tubes may be used, or a multi-way valve may be added to one end of the first sampling tube 1.
Specifically, the first sample injection tube 1, the second sample injection tube 2 and the waste liquid tube 7 may be connected to a peristaltic pump 11, and liquid feeding and liquid discharging may be achieved by the peristaltic pump 11, and the peristaltic pump 11 may be a three-channel or four-channel pump.
Specifically, the reaction unit in the sample injection device may be fixedly mounted on the fixing support 10, the structure of the fixing support 10 is not particularly limited, and the form of the reaction unit may be specifically adjusted according to the size of the instrument, the number of pipelines, and the like.
Specifically, the gas-liquid separation unit of the sample injection device may include a gas-liquid separation membrane 8, which is disposed at an opening of the reaction vessel 6 (i.e., an opening of the reaction chamber) and completely covers the opening of the reaction vessel 6.
Specifically, the gas-liquid separation membrane 8 is embedded in the reaction cavity cover 9, a third cavity formed by enclosing the gas-liquid separation membrane and the reaction cavity cover is further arranged between the gas-liquid separation membrane 8 and the reaction cavity cover 9, and a gas outlet is formed in the reaction cavity cover 9; specifically, the gas substance in the mixed liquid input into the reaction container 6 from the reaction pipeline 5 can pass through the gas-liquid separation membrane 8 and enter the third cavity, and the gas-liquid separation membrane 8 can prevent the liquid substance from passing through and block the liquid substance in the reaction container 6; for example, the reaction chamber cover 9 has an outer diameter of 400mm and a height of 20mm, the gas-liquid separation membrane 8 is a circular member having a diameter of about 36mm, and the gas-liquid separation membrane 8 may be made of polytetrafluoroethylene.
Specifically, the detection device 14 may be communicated with the gas outlet on the reaction chamber cover 9 through a connection elbow 13, the gas substance filtered by the gas-liquid separation membrane 8 may be introduced into the detection device 14 through the connection elbow 13, and parameters of the detection device 14, such as the atomized gas flow, the pump speed, the radio frequency power, and the cooling gas flow, may be adjusted according to specific conditions.
Specifically, taking the detection of trace bromine and/or iodine as an example, the method for detecting trace halogen by using the detection system for detecting trace halogen provided in an exemplary embodiment of the present invention comprises the following steps:
providing and connecting the detection system of FIG. 1, wherein the detection device can adopt ICP-OES from Saimer Feishier company or Perkin Elmer, and providing solution to be detected containing trace halogen and reaction reagent, and when only iodine needs to be detected, the reaction reagent is NaNO 2 And nitric acid, wherein when bromine and iodine are simultaneously measured, the reaction reagent is KMnO 4 And HNO 3 ；
The reaction reagent and the solution to be detected are respectively input through the first sample inlet pipe 1 and the second sample inlet pipe 2, the reaction reagent and the solution to be detected are respectively mixed into the pump pipe 3 through the first sample inlet pipe 1 and the second sample inlet pipe 2, a mixed solution composed of the reaction reagent and the solution to be detected enters the reaction pipeline 5 under the drive of high-purity argon in the gas guide pipe 4 and is continuously mixed and reacted in the reaction pipeline 5, then the mixed solution enters the first cavity of the reaction cavity from the upper part of the reaction container 6 through the reaction pipeline 5, bromide ions and/or iodide ions in the mixed solution and the reaction reagent undergo an oxidation-reduction reaction and are oxidized into volatile bromide simple substances and/or iodine simple substances, the bromide simple substances and/or the iodine simple substances in the mixed solution are volatilized and are guided into the detection device 14 through the gas-liquid separation membrane 8 for detection, the liquid substances are blocked in the reaction cavity by the gas-liquid separation membrane 8 and are guided into the waste liquid pipe 7 through the second cavity for discharge.
The working conditions of detection instruments such as ICP-OES and the like also need to be optimized experimentally, the working conditions mainly comprise instrument conditions such as atomization gas flow, pump speed, radio frequency power, cooling gas flow and the like, when the ICP-OES is used for measurement, halogen belongs to elements with high ionization energy, the radio frequency power is as high as possible within the allowable range of the radio frequency power of the instruments, and in addition, the ICP-OES has low measurement sensitivity on the halogen, so a horizontal observation mode is selected for spectral lines during analysis.
Comparative example 1
The detection device in the comparison example adopts ICP-OES of platinum Elmer company, the wavelength range of the instrument is 165-900nm, the instrument can only detect bromine and iodine in halogen due to the limitation of the performance of the instrument, and the working conditions of the instrument during the detection are 1450W of radio frequency power, 15L/min of plasma gas, 0.5L/min of atomizing gas, 0.2L/min of auxiliary gas and 1.5mL/min of pump speed.
In the comparative example, a sample introduction system of a detection instrument or a detection device is utilized, the sample introduction system comprises a fog chamber, an atomizer and the like, bromine and iodine in a standard sample are measured by adopting a direct atomization mode, and the test results are shown in table 1. Wherein, S1-S7 are standard samples containing different concentrations of Br and I.
TABLE 1 results of direct atomization determination of bromine and iodine
Example 1
In this embodiment, based on the detection system shown in fig. 1, the detection method provided in this specification is used to detect bromine and iodine in a sample. In which ICP-OES of platinum Elmer was used as the detection apparatus, the working conditions of the detection apparatus were as in comparative example 1, and the oxidizing agent in the reaction reagent used in this example was 20mM KMnO 4 The kinds and concentrations of the acids used in the solutions can be seen from Table 2, and the bromine concentration and the iodine concentration of the standard samples used were 10mg/L and 1mg/L, respectively. As can be seen from table 2, the test results show that, compared with the method of directly measuring bromine and iodine by using a conventional sample injection system, the emission intensity of bromine and iodine is significantly improved, i.e., the measurement sensitivity is significantly improved.
TABLE 2 determination of bromine and iodine
Example 2
This embodiment is substantially the same as embodiment 1. The difference lies in that: the nitric acid concentration in the reaction reagent used was 4M, and the concentration of the oxidizing agent used can be found in table 3. And the bromine concentration and the iodine concentration of the adopted standard samples are both 1mg/L and 0.5mg/L respectively. As can be seen from Table 3, the oxidant KMnO 4 At a concentration of 1 to 50 mM. Referring to table 3, the test results show that the measurement sensitivity of bromine and iodine is significantly improved compared to the direct measurement mode using the conventional sample injection system.
Table 3 shows the results of the effect of the concentration of the oxidizing agent on the measurement
Example 3
This example is substantially the same as example 1, except forThe method comprises the following steps: the reagent used in this example was KMnO at a concentration of 2mM 4 Solution and 4M HNO 3 Table 4 shows the results of measurement of bromine and iodine using this example. As can be seen from Table 4, the linearity of the bromine and iodine standard solution series at each analysis spectral line is good (R is more than 0.999), and the requirement of ICP-OES quantitative test is met. In addition, as can be seen from tables 1 and 4, the sensitivity of the analysis method of the present invention for bromine and iodine was improved by at least 20 times, and the detection limit of the detection apparatus was also significantly reduced (in which the detection limit of bromine was reduced by 26 times and the detection limit of iodine was reduced by 14 times).
TABLE 4 determination of bromine and iodine
Comparative example 2
The detection device in the comparative example adopts ICP-OES of Saimer Feishell company, the wavelength range of the instrument is 166-847nm, and the instrument can only detect iodine in halogen due to the limitation of the performance of the instrument; the working conditions of the instrument during the measurement were set as follows: the radio frequency power is 1300W, the flow rate of atomizing air is 0.4L/min, the flow rate of auxiliary air is 0.3L/min, the flow rate of cooling air is 16L/min, and the pump speed is 50rpm.
In the comparative example, a sample introduction system of a detection instrument or a detection device is used, the sample introduction system comprises a fog chamber, an atomizer and the like, iodine in a standard sample is measured by adopting a direct atomization mode, and the test result is shown in table 5.
TABLE 5 direct nebulization assay results using the sample introduction system of the instrument (i.e., detection device) itself
Example 4
In this embodiment, iodine in a sample is detected by the detection method provided in the present specification based on the detection system shown in fig. 1. The detection device used was ICP-OES of Seimer Feishale, and the working conditions of the apparatus were as in comparative example 2, which used the reactionThe acid in the reagent was 1M nitric acid, and the kind and concentration of the oxidizing agent used were as shown in Table 6, and the iodine concentration in the sample used was 1mg/L. As can be seen from Table 6, in this example, compared with the method of directly measuring iodine by using the detection device itself sample injection system, in this example, KMnO is used 4 、H 2 O 2 、K 2 Cr 2 O 7 And NaNO 2 The four oxidants have improved measuring sensitivity to iodine.
Table 6 shows the influence of the type of oxidizing agent on the measurement effect
Example 5
This example is substantially the same as example 4, except that: the reaction reagent is NaNO with the concentration of 10mM 2 Solution and nitric acid at a concentration of 1M. Direct measurement is adopted under the standard curve of Table 5, and the detection limit of the instrument at the position of I178.2nm is 11.7 mug/L, and the detection limit at the position of I183.0 nm is 43.6 mug/L; the detection limit of the instrument at I178.2nm is 2.2 mug/L and the detection limit of the instrument at I183.0 nm is 2.76 mug/L measured by adopting the analysis method of the invention under the standard curve of Table 7, and by comparing the two methods, the emission intensity of iodine is improved by 27 times and the detection limit of the instrument is improved by at least 5 times by adopting the analysis method provided by the invention.
Table 7 example 5 measurement results of iodine
Example 6
This example is substantially the same as example 1, except that: the reagent used was KMnO at a concentration of 2mM 4 Solution and 4M HNO 3 The results are shown in Table 8 below; standard Curve testing using Table 4The determination results in table 8 show that the detection system and the detection method provided by the invention are used for determining bromine and iodine in the actual sample, the analysis is rapid and accurate, and the recovery rate of the spiked sample is 88-111.3%.
TABLE 8 determination of bromine and iodine in samples by the analytical method provided by the present invention
Specifically, the embodiment of the present invention provides a detection system and a detection method for detecting trace halogen to detect bromine and iodine elements, and of course, the detection system and the detection method are also applicable to the detection of other halogen elements, and when the detection system and the detection method are used for detecting other halogen elements, different detection apparatuses and detection conditions are correspondingly used, which are not described herein again.
The detection method greatly improves the analysis sensitivity of a detection device (such as an inductively coupled plasma atomic emission spectrometer) to halogen, reduces the interference of a coexisting substrate to the halogen to be detected, can be successfully applied to the detection of trace halogen in a water sample, and has very wide application value in the test industry.
The invention provides a detection system and a detection method for detecting trace halogen aiming at the problems of low sensitivity and high detection limit of detecting halogen (namely halogen, the same below) of detection instruments such as ICP-OES and the like, wherein the detection system greatly improves the detection sensitivity of the halogen and the detection limit of the halogen, and simultaneously reduces the influence of a coexisting matrix on the determination of the trace halogen; the sample introduction device of the detection system can be directly used with ICP-OES of various models for analyzing trace halogen in water, and can be connected to other analyzers to improve the analysis sensitivity of halogen elements, thereby having very wide application value in the test industry and providing higher reference value for analysis of other elements and element valence states.
It should be understood that the above-mentioned embodiments are merely illustrative of the technical concepts and features of the present invention, which are intended to enable those skilled in the art to understand the contents of the present invention and implement the present invention, and therefore, the protection scope of the present invention is not limited thereby. All equivalent changes and modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.
Claims (7)
1. A detection method for directly measuring trace halogen is characterized by comprising the following steps:
firstly, a reaction reagent and a solution to be detected are respectively input into a reaction pipeline through a sample inlet pipe, so that the reaction reagent and the solution to be detected react in the reaction pipeline to form a mixed system, halogen ions in the solution to be detected are oxidized to form a volatile halogen simple substance,
introducing inert gas into the reaction pipeline to drive a mixed system in the reaction pipeline to be conveyed to a gas-liquid separation unit through the reaction pipeline, wherein the gas-liquid separation unit comprises a first cavity and a second cavity which are communicated with each other, the first cavity is positioned above the second cavity, and a gas-liquid separation membrane is arranged at an opening of the first cavity; the reaction pipeline is directly communicated with the first cavity, and the first cavity is also communicated with a third cavity for collecting gas-phase substances;
gas-phase substances in the mixed system can enter a third cavity after being filtered by the gas-liquid separation membrane from an opening of the first cavity, and are guided into a detection device through the third cavity to be detected, so that the detection of trace halogen is realized, and liquid-phase substances in the mixed system can be guided into the second cavity.
2. The detection method according to claim 1, characterized in that: the inert gas comprises high purity argon having a purity greater than 99.99%.
3. The detection method according to claim 1, characterized in that: the inner diameter of the first cavity is larger than that of the second cavity, and the first cavity is smoothly connected with the second cavity.
4. The detection method according to claim 1, characterized in that: the reaction reagent comprises an oxidizing agent and acid, and the solution to be detected contains halogen ions.
5. The detection method according to claim 4, characterized in that: the oxidant comprises any one or the combination of more than two of potassium dichromate, hydrogen peroxide, sodium nitrite, potassium permanganate and potassium persulfate, and/or the acid comprises any one or the combination of more than two of nitric acid, hydrochloric acid and sulfuric acid.
6. The detection method according to claim 4, characterized in that: the halogen ion is iodide ion, and the reaction reagent comprises NaNO 2 And nitric acid, said NaNO 2 The concentration of the solution is 1-100 mmol/L, and the concentration of the nitric acid is 0.2-2 mol/L.
7. The detection method according to claim 4, characterized in that: the halide ions are iodide ions and bromide ions, and the reaction reagent comprises KMnO 4 Solution and HNO 3 Said KMnO 4 The concentration of the solution is 1-50 mmol/L, and the concentration of the nitric acid is 1-4 mol/L.
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