Device and method for rapid determination of selenium

Abstract

The invention discloses a device and method for rapid determination of selenium, and relates to the technical field of determination of selenium, wherein the device for rapid determination of selenium comprises an electrothermal evaporation mechanism, a gas phase secondary decomposition mechanism, a detection pipeline, a high temperature area, a temperature control area, a gas phase enrichment mechanism and an ignition mechanism, and an atomization mechanism formed by the ignition mechanism and the gas phase enrichment mechanism. During implementation, the selenium in the sample can be directly electrothermally evaporated through the cooperation of the electrothermal evaporation mechanism and the gas phase secondary decomposition mechanism, thereby eliminating the need for complex sample pretreatment processes, and directly analyzing solid samples or liquid samples. The set atomization mechanism utilizes the characteristics of gold capturing selenium oxides and selenium atoms to effectively separate the complex matrix of the sample product in the electrothermal evaporation process, thereby ensuring the precision of sample testing.

Description

Technical Field

[0001] The invention relates to the technical field of determining selenium, and in particular to a device and a method for rapidly determining selenium. Background Art

[0002] Taking most dietary foods as an example, their selenium content is often less than 0.03 mg / kg, but accurately determining the selenium content level below this concentration is very important for a reasonable nutritional diet. In order to improve the sensitivity of selenium detection, Reference 1 (Journal of Analytical Atomic Spectrometry., 2001, 16, 1414–1419) and Reference 2 (Spectrochimica Acta Part B., 2009, 63, 956–960) successively reported the low-temperature capture and high-temperature release of selenium hydride (hydrogen selenide) with gold, thallium or gold-plated tungsten wire, thereby achieving high-sensitivity detection of ng / L level selenium content in solution through gas phase enrichment of hydrogen selenide. Unfortunately, the above methods can still only detect selenium in solution, and the cumbersome sample pretreatment work such as "sample becomes solution" or "selenium in the sample is evenly dispersed in the solution" has not been reduced. And the above analysis methods all require high-pressure rare gases such as argon. Summary of the invention

[0003] In order to solve the above technical problems, the present invention provides a device and method for rapidly determining selenium.

[0004] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0005] Provided is a device for rapid determination of selenium, comprising a vertical tube and a horizontal tube made of quartz, wherein the horizontal tube is provided with a first electric heater and a second electric heater in sequence along the direction from the sample injection end to the sample discharge end, the first electric heater and the horizontal tube form an electric evaporation mechanism, an auxiliary decomposition component is provided in the horizontal tube and at a position corresponding to the second electric heater, and the auxiliary decomposition component, the second electric heater and the horizontal tube jointly form a gas phase secondary decomposition mechanism, and the selenium in the sample can be directly evaporated out by the electric evaporation mechanism and the gas phase secondary decomposition mechanism cooperating with each other;

[0006] The sample row end of the horizontal tube is connected with the vertical tube to form a "T"-shaped detection pipeline. The two ends of the vertical tube serve as the detection end and the air inlet end of the detection pipeline from top to bottom, and the vertical tube is provided with a third electric heater at the position corresponding to the sample row end of the horizontal tube to form a high-temperature area. A fourth electric heater is provided on the outer peripheral side of the vertical tube and above the high-temperature area to form a temperature control area. A gold capture body is filled in the vertical tube and located in the temperature control area to form a gas phase enrichment mechanism. The vertical tube and the detection end of the detection pipeline are provided with an ignition mechanism, which forms an atomization mechanism together with the gas phase enrichment mechanism. The characteristics of gold capturing selenium oxides and selenium atoms are used to effectively separate the complex matrix of the sample product in the electrothermal evaporation process, thereby ensuring the precision of the sample test.

[0007] Based on the above-mentioned device for rapid determination of selenium, the present invention also discloses a method for rapid determination of selenium, comprising the following steps:

[0008] S1: The sample is placed in the electric evaporation mechanism of the detection pipeline through the sample injection mechanism to heat the sample so that the selenium is released by thermal decomposition, and the undecomposed organic matter is heated again by the gas phase secondary decomposition mechanism so that the selenium is released by thermal decomposition;

[0009] S2: injecting carrier gas into the detection pipeline from the injection end and the injection end through the gas injection mechanism respectively, and the carrier gas carrying the pyrolyzed selenium is atomized by the atomization mechanism and then discharged from the detection end of the detection pipeline;

[0010] S3: Use a detection mechanism to measure the concentration of selenium atoms at the detection end of the detection pipeline. This concentration is the concentration of selenium atoms in the sample.

[0011] The steps of atomizing selenium by the above-mentioned atomization mechanism are as follows:

[0012] S2.1: The carrier gas carries the pyrolytic selenium through the high temperature area for flame atomization;

[0013] S2.2: The carrier gas carries the atomized selenium into the temperature control area and is captured by the gold capture body to achieve gas phase enrichment;

[0014] S2.3: The temperature-controlled area heats the gold capture body to release selenium again and carry it to the ignition mechanism by hydrogen to ignite and realize re-atomization.

[0015] Preferably, the temperature of the temperature control area during the gas phase enrichment process is 200°C to 500°C, and the temperature at which the gold capture body releases selenium is 900°C to 1000°C.

[0016] Preferably, the carrier gas is air, oxygen, nitrogen, argon, helium, hydrogen or a mixture thereof.

[0017] Preferably, the outer diameter of the horizontal tube is 16 mm, the inner diameter is 15 mm, the injected carrier gas flow rate is 500 mL / min, and the outer diameter of the vertical tube is 5 mm, the inner diameter is 1 mm, and the injected carrier gas flow rate is 300 mL / min.

[0018] Preferably, the detection mechanism is a dispersive atomic fluorescence detector or a dual-light source adjacent line corrected atomic absorption detector or an atomic emission spectrometer or an atomic emission spectrometer.

[0019] Preferably, the sample introduction mechanism comprises a sample crucible and a manipulator for placing the sample crucible on the electrothermal evaporation mechanism.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. Through the cooperation of the electrothermal evaporation mechanism and the gas phase secondary decomposition mechanism, the selenium in the sample can be directly electrothermally evaporated, thereby eliminating the complicated sample pretreatment process and directly analyzing solid samples or liquid samples;

[0022] 2. The atomization mechanism uses the characteristics of gold capturing selenium oxide and selenium atoms to effectively separate the complex matrix of the sample product in the electrothermal evaporation process, ensuring the precision of sample testing. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0024] Figure 2 It is a schematic diagram of the sample analysis process;

[0025] Figure 3 This is a schematic diagram of the analysis process for samples with high organic content such as grains and meat;

[0026] Figure 4 It is a standard curve diagram of selenium concentration range 1-40ng and instrument response value.

[0027] Figure symbols: 1. vertical tube, 2. horizontal tube, 3. first electric heater, 4. second electric heater, 5. auxiliary decomposition component, 6. third electric heater, 8. gold capture body, 9. ignition mechanism, 10. sample crucible. DETAILED DESCRIPTION

[0028] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments and drawings. The exemplary embodiments of the present invention and their description are only used to explain the present invention and are not intended to limit the present invention.

[0029] Example 1

[0030] A device for rapid determination of selenium, such as Figure 1As shown, it comprises a vertical tube 1 and a horizontal tube 2 made of quartz, the horizontal tube 2 is provided with a first electric heater 3 and a second electric heater 4 in sequence along the direction from the sample feeding end to the sample discharging end, the first electric heater 3 and the horizontal tube 2 form an electric heating evaporation mechanism, an auxiliary decomposition member 5 is provided in the horizontal tube 2 and at a position corresponding to the second electric heater 4, and the auxiliary decomposition member 5, the second electric heater 4 and the horizontal tube 2 together form a gas phase secondary decomposition mechanism, and the auxiliary decomposition member 5 is porous quartz, quartz sand or quartz wool;

[0031] The sample row end of the horizontal tube 2 is connected with the vertical tube 1 to form a "T"-shaped detection pipeline. The two ends of the vertical tube 1 serve as the detection end and the air inlet end of the detection pipeline from top to bottom, and the vertical tube 1 is provided with a third electric heater 6 at the position corresponding to the sample row end of the horizontal tube 2 to form a high-temperature area. A fourth electric heater 7 is provided on the outer peripheral side of the vertical tube 1 and above the high-temperature area to form a temperature control area. A gold capture body 8 is filled in the vertical tube 1 and located in the temperature control area to form a gas phase enrichment mechanism. The vertical tube 1 is provided with an ignition mechanism 9 at the detection end of the detection pipeline, which forms an atomization mechanism together with the gas phase enrichment mechanism. The above-mentioned gold capture body 8 is a gold-plated quartz sand layer or a gold wire mesh.

[0032] like Figure 2 As shown, the steps for determining selenium by the above-mentioned rapid selenium determination device are as follows:

[0033] S1: The sample is placed in the electric evaporation mechanism of the detection pipeline through the sample injection mechanism to heat the sample so that the selenium is released by thermal decomposition. The undecomposed organic matter is heated again by the gas phase secondary decomposition mechanism to release the selenium by thermal decomposition. The selenium in the sample can be directly evaporated by electric heating, thereby eliminating the complicated sample pretreatment process and directly analyzing solid samples or liquid samples;

[0034] S2: injecting carrier gas into the detection pipeline from the injection end and the injection end through the gas injection mechanism respectively, and the carrier gas carrying the pyrolyzed selenium is atomized by the atomization mechanism and then discharged from the detection end of the detection pipeline;

[0035] S3: Use a detection mechanism to measure the concentration of selenium atoms at the detection end of the detection pipeline. This concentration is the concentration of selenium atoms in the sample.

[0036] The steps for atomization of selenium by the atomization mechanism are as follows:

[0037] S2.1: The carrier gas carries the pyrolytic selenium through the high temperature area for flame atomization;

[0038] S2.2: The carrier gas carries the atomized selenium into the temperature control area and is captured by the gold capture body 8 to achieve gas phase enrichment;

[0039] S2.3: The temperature-controlled area heats the gold capture body 8 to release selenium again and carry it to the ignition mechanism 9 by hydrogen to ignite and realize re-atomization. This process utilizes the characteristics of gold capturing selenium oxide and selenium atoms to effectively separate the complex matrix of the sample product in the electrothermal evaporation process, thereby ensuring the precision of the sample test.

[0040] The above-mentioned detection mechanism is a dispersive atomic fluorescence detector or a dual-light source adjacent spectral line correction atomic absorption detector. The sampling mechanism includes a sample crucible 10 and a manipulator for placing the sample crucible 10 in an electrothermal evaporation mechanism. The carrier gas is air, oxygen, nitrogen, argon, helium, hydrogen or a mixed gas thereof.

[0041] In the process of gas phase enrichment, the temperature of the temperature control area is 200°C to 500°C, and the temperature at which the gold capture body 8 releases selenium is 900°C to 1000°C.

[0042] As a preferred embodiment of the above embodiment, the outer diameter of the horizontal tube 2 is 16 mm, the inner diameter is 15 mm, the injected carrier gas flow rate is 500 mL / min, the outer diameter of the vertical tube 1 is 5 mm, the inner diameter is 1 mm, and the injected carrier gas flow rate is 300 mL / min.

[0043] When implementing:

[0044] The analysis method flow of samples with high organic content such as grain and meat is as follows Figure 3 As shown, sample S is placed in an electric evaporation mechanism, and the sample S is heated in the electric evaporation mechanism during the continuous injection of carrier gases A1 and A2. Gas A1 is air with an optimal flow rate of 500 mL / min. Selenium in the sample is released by thermal decomposition, and the organic matter that is not fully decomposed is subjected to secondary high-temperature decomposition by a gas phase secondary decomposition mechanism. Gas A2 is hydrogen with an optimal flow rate of 300 mL / min. A mixed gas of gases A1 and A2 burns in a high-temperature area to form a flame F1. At this time, selenium completes an atomization process and is then carried by the gas to a temperature control area with a temperature of 200°C to 500°C. Selenium is captured by a gold capture body 7, and then the temperature control area is heated to 1000°C to 1000°C. Selenium is decomposed from the gold capture body 7 and atomized by the hydrogen in flame F2, and the concentration of selenium is detected by a detection mechanism.

[0045] The analysis method flow of soil, water quality, mineral samples, etc.: the sample is placed in an electric thermal evaporation mechanism, and carrier gas is continuously injected into the vertical tube 1 and the horizontal tube 2. In this process, the sample is heated and decomposed by the electric thermal evaporation mechanism and the gas phase secondary decomposition mechanism. The carrier gas injected into the horizontal tube 2 is hydrogen, and the carrier gas injected into the vertical tube 1 is air. The hydrogen carries the thermally decomposed selenium and mixes with the air and burns in the high temperature area to form flame F1. At this time, the selenium completes an atomization process and is then carried by the gas to the temperature control area with a temperature of 200°C to 500°C. The selenium is captured by the gold capture body 7, and then the temperature control area is heated to 1000°C to 1000°C. The selenium is decomposed from the gold capture body 7 and atomized by the hydrogen carrier in the flame F2, and the concentration of the selenium is obtained by detection through the detection mechanism.

[0046] Capture mechanism: Using air or high-purity oxygen as the carrier gas, the selenium evaporated by electrothermal heating is selenium oxide, which can be captured by gold without the need for hydrogen.

[0047] The air is generated by a membrane air pump, or provided by a compressor, or provided by cylinder gas, and the hydrogen is obtained by electrolyzing water, or supplied by cylinder gas or released by hydrogen storage materials.

[0048] Selenium speciation analysis:

[0049] Analysis of inorganic selenium in food: 1 g of sample is subjected to simple extraction and solid phase extraction column to retain inorganic selenium and separate small molecule organic selenium. The inorganic selenium eluate (0.5 mL from 5 mL) is used to determine inorganic selenium using the method disclosed in this patent.

[0050] Analysis of available selenium in soil:

[0051] Weigh 1 g of soil sample (accurate to 0.001 g) into a 15 mL centrifuge tube, add 10 mL of 0.10 mol / L potassium dihydrogen phosphate solution, oscillate at 30°C and 1500 rpm for 90 min, centrifuge at 3000 rpm for 15 min, take the supernatant and directly determine it using this method, calculate the selenium content in the supernatant, and then convert it into the effective selenium content in the soil sample.

[0052] Test data

[0053] 1. Selenium standard curve

[0054] A standard curve was drawn using a selenium standard solution to form a standard curve between the selenium concentration range of 1-40 ng and the instrument response value, such as Figure 4 shown.

[0055] Analysis method and equipment process parameter table

[0056]

[0057] ·Determination data of selenium in grain and food samples

[0058]

[0059] Determination data of inorganic selenium in food

[0060]

[0061] ·Determination data of selenium in soil

[0062]

[0063]

[0064] Of course, the present invention may have many other embodiments. Without departing from the spirit and essence of the present invention, technicians familiar with the field may make various corresponding changes and deformations based on the present invention, but these corresponding changes and deformations should all fall within the scope of protection of the claims attached to the present invention.

Claims

1. A device for rapid determination of selenium, characterized in that: The invention comprises a vertical tube (1) and a horizontal tube (2) made of quartz, wherein the horizontal tube (2) is provided with a first electric heater (3) and a second electric heater (4) in sequence along the direction from the sample feeding end to the sample discharging end, the first electric heater (3) and the horizontal tube (2) form an electric heating evaporation mechanism, an auxiliary decomposition component (5) is provided in the horizontal tube (2) at a position corresponding to the second electric heater (4), and the auxiliary decomposition component (5), the second electric heater (4) and the horizontal tube (2) together form a gas phase secondary decomposition mechanism; The sample row end of the horizontal tube (2) is connected to the vertical tube (1) to form a "T"-shaped detection pipeline. The two ends of the vertical tube (1) serve as the detection end and the air intake end of the detection pipeline from top to bottom, and the vertical tube (1) is provided with a third electric heater (6) at a position corresponding to the sample row end of the horizontal tube (2) to form a high-temperature area. A fourth electric heater (7) is provided on the outer peripheral side of the vertical tube (1) and above the high-temperature area to form a temperature control area. A gold capture body (8) is filled in the vertical tube (1) and at a position located in the temperature control area to form a gas phase enrichment mechanism. The detection end of the vertical tube (1) and the detection pipeline is provided with an ignition mechanism (9), which forms an atomization mechanism together with the gas phase enrichment mechanism.

2. A method for rapid determination of selenium, based on the device for rapid determination of selenium according to claim 1, characterized in that: The steps include: S1: The sample is placed in the electric evaporation mechanism of the detection pipeline through the sample injection mechanism to heat the sample so that the selenium is released by thermal decomposition, and the undecomposed organic matter is heated again by the gas phase secondary decomposition mechanism so that the selenium is released by thermal decomposition; S2: injecting carrier gas into the detection pipeline from the injection end and the gas inlet end through the gas injection mechanism respectively, and the carrier gas carrying the pyrolyzed selenium is atomized by the atomization mechanism and then discharged from the detection end of the detection pipeline; S3: Use a detection mechanism to measure the concentration of selenium atoms at the detection end of the detection pipeline. This concentration is the concentration of selenium atoms in the sample.

3. The method for rapid determination of selenium according to claim 2, characterized in that The steps for atomization of selenium by the atomization mechanism are as follows: S2.1: The carrier gas carries the pyrolytic selenium through the high temperature area for flame atomization; S2.2: The carrier gas carries the atomized selenium into the temperature control area and is captured by the gold capture body (8) to achieve gas phase enrichment; S2.3: The temperature-controlled area heats the gold capture body (8) to release selenium again and carry it to the ignition mechanism (9) by hydrogen to ignite and realize re-atomization.

4. The method for rapid determination of selenium according to claim 3, characterized in that During the gas phase enrichment process, the temperature of the temperature control area is 200°C to 500°C, and the temperature at which the gold capture body (8) releases selenium is 900°C to 1000°C.

5. The method for rapid determination of selenium according to claim 2, characterized in that: The carrier gas is air, oxygen, nitrogen, argon, helium, hydrogen or a mixed gas thereof.

6. The method for rapid determination of selenium according to any one of claims 2 to 5, characterized in that: The outer diameter of the horizontal tube (2) is 16 mm, the inner diameter is 15 mm, and the injected carrier gas flow rate is 500 mL / min. The outer diameter of the vertical tube (1) is 5 mm, the inner diameter is 1 mm, and the injected carrier gas flow rate is 300 mL / min.

7. The method for rapid determination of selenium according to claim 2, characterized in that: The detection mechanism is a dispersion atomic fluorescence detector or a dual-light source adjacent spectral line correction atomic absorption detector or an atomic emission spectrometer.

8. The method for rapid determination of selenium according to claim 2, characterized in that: The sample introduction mechanism comprises a sample crucible (10) and a manipulator for placing the sample crucible (10) on the electrothermal evaporation mechanism.

Images