CN114778503A - Method for measuring selenium by non-dispersive atomic fluorescence spectrometry - Google Patents
Method for measuring selenium by non-dispersive atomic fluorescence spectrometry Download PDFInfo
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Abstract
The invention provides a method for measuring selenium by using a non-dispersive atomic fluorescence spectrometry, which comprises the following steps: mixing a sample to be detected with a potassium borohydride solution, then carrying out a reduction reaction under an acidic condition, mixing a gaseous product of the reduction reaction with hydrogen through carrier gas during the reduction reaction, and then igniting to obtain an atom to be detected; the concentration of the potassium borohydride solution is 0.5-1 g/L; and measuring the atoms to be measured by adopting a non-dispersive atomic fluorescence spectrometry to obtain the selenium content in the sample to be measured. Experimental results show that Pb only generates 13.5% of interference on selenium when 1g/L of potassium borohydride solution is adopted in the method, and 58.5% of interference is generated when 10g/L of potassium borohydride solution is adopted.
Description
Technical Field
The invention belongs to the technical field of atomic fluorescence spectrometry, and particularly relates to a method for measuring selenium by using a non-dispersive atomic fluorescence spectrometry.
Background
In recent years, selenium (Se) element is beneficial to human health and rapidly turns red, so that a strong 'selenium supplement heat' is developed in various places, and geological environment investigation of selenium-rich ores and selenium-rich water samples of soil and water quality is promoted nationwide. At present, the detection method of selenium mainly comprises a colorimetric method, an atomic absorption spectrometry, an inductively coupled plasma mass spectrometry and the like, and the hydride generation-atomic fluorescence spectrometry is widely applied to the determination of selenium by the advantages of high sensitivity, simultaneous detection of multiple elements and the like.
At present, a non-dispersive system is generally adopted by a hydride generation-atomic fluorescence spectrometer, and the advantage is that a plurality of fluorescence lines can be detected, wherein lines with wavelengths of selenium (Se)196.0, 203.9, 206.3 and 207.5nm can be excited to generate fluorescence lines which are detected by the non-dispersive atomic fluorescence spectrometer. Because the melting point of the Se element hollow cathode lamp is lower, the intensity and the service life of a light source are influenced, and the melting point of a cathode is generally increased by adding lead (Pb) into the Se element hollow cathode lamp at present. In this case, when the sample contains both Se and Pb, Pb reacts simultaneously to generate fluorescence, which is detected by the non-dispersive atomic fluorescence spectrometer, and all Se fluorescence is erroneously considered to be the fluorescence, resulting in a higher Se detection result. Therefore, how to inhibit interference of Pb so as to accurately measure the content of selenium becomes a difficult problem to be solved in the field.
Disclosure of Invention
The invention aims to provide a method for measuring selenium by using non-dispersive atomic fluorescence spectrometry. The method provided by the invention can obviously reduce the interference of Pb on the determination and improve the accuracy of the selenium content.
In order to achieve the above object, the present invention provides the following technical solutions:
the invention provides a method for measuring selenium by using a non-dispersive atomic fluorescence spectrometry, which comprises the following steps:
(1) mixing a sample to be detected with a potassium borohydride solution, then carrying out a reduction reaction under an acidic condition, mixing a gaseous product of the reduction reaction with hydrogen through carrier gas during the reduction reaction, and then igniting to obtain an atom to be detected; the concentration of the potassium borohydride solution is 0.5-1 g/L;
(2) and (2) determining the atoms to be detected obtained in the step (1) by using a non-dispersive atomic fluorescence spectrometry method to obtain the selenium content in the sample to be detected.
Preferably, the selenium element in the sample to be tested in the step (1) exists in the form of tetravalent selenium.
Preferably, the concentration of the potassium borohydride solution in the step (1) is 0.8-1 g/L.
Preferably, when the sample to be detected in the step (1) is a liquid, the volume ratio of the sample to be detected to the potassium borohydride solution is (1-4): (4-6).
Preferably, the volume ratio of the sample to be detected to the potassium borohydride solution is 4: 5.
preferably, the carrier gas in step (1) is argon.
Preferably, the flow rate of the carrier gas in the step (1) is 600-1400 mL/min.
Preferably, the flow rate of the hydrogen in the step (1) is 60-120 mL/min.
Preferably, the flow rate of the hydrogen is 80-100 mL/min.
Preferably, the ignition in step (1) is performed in an atomizer of a non-dispersive atomic fluorescence spectrometer.
The invention provides a method for measuring selenium by using a non-dispersive atomic fluorescence spectrometry, which comprises the following steps: mixing a sample to be detected with a potassium borohydride solution, then carrying out a reduction reaction under an acidic condition, mixing a gaseous product of the reduction reaction with hydrogen through carrier gas during the reduction reaction, and then igniting to obtain an atom to be detected; the concentration of the potassium borohydride solution is 0.5-1 g/L; and measuring the atoms to be measured by adopting a non-dispersive atomic fluorescence spectrometry to obtain the selenium content in the sample to be measured. According to the method, the ultra-low concentration potassium borohydride solution is adopted, so that the generation efficiency of lead is obviously reduced, the fluorescence intensity signal generated by the same lead content is obviously reduced, the interference of Pb on selenium determination of an intermittent hydride generation-atomic fluorescence spectrometer can be obviously reduced, the hydrogen produced by reduction reaction is insufficient due to the ultra-low concentration of potassium borohydride, the concentration of the hydrogen is increased by using the added hydrogen, the hydrogen flame is ignited, the atom to be determined is obtained, the accurate determination of selenium in the sample to be determined is further realized, and the accuracy of selenium determination is improved. Experimental results show that Pb only generates 13.5% of interference on selenium when 1g/L of potassium borohydride solution is adopted in the method, and 58.5% of interference is generated when 10g/L of potassium borohydride solution is adopted.
Drawings
FIG. 1 is a graph showing the relationship between potassium borohydride concentration and lead and selenium fluorescence intensity when non-dispersive atomic fluorescence spectrometry is used to measure selenium content in the same sample to be measured.
Detailed Description
The invention provides a method for measuring selenium by using a non-dispersive atomic fluorescence spectrometry, which comprises the following steps:
(1) mixing a sample to be detected with a potassium borohydride solution, then carrying out a reduction reaction under an acidic condition, mixing a gaseous product of the reduction reaction with hydrogen through carrier gas during the reduction reaction, and then igniting to obtain an atom to be detected; the concentration of the potassium borohydride solution is 0.5-1 g/L;
(2) and (2) measuring the atoms to be measured obtained in the step (1) by adopting a non-dispersive atomic fluorescence spectrometry method to obtain the selenium content in the sample to be measured.
The method provided by the invention is applicable to any liquid substance containing selenium, preferably to a liquid substance in which the elemental selenium exists in the form of tetravalent selenium.
The method comprises the steps of mixing a sample to be detected with a potassium borohydride solution, carrying out reduction reaction under an acidic condition, mixing a gaseous product of the reduction reaction with hydrogen through carrier gas during the reduction reaction, and igniting to obtain atoms to be detected. In the present invention, the selenium element in the sample to be tested is preferably tetravalent selenium. The method mixes a sample to be detected with a potassium borohydride solution, the potassium borohydride solution is used as a reducing agent, and can perform a reduction reaction with tetravalent selenium in the sample to be detected under an acidic condition to obtain gaseous hydride hydrogen selenide and hydrogen, the carrier gas is mixed with the added hydrogen, hydrogen flame is ignited, molecular selenium is atomized to obtain selenium atoms, and the method is favorable for subsequent determination of the selenium.
In the invention, the concentration of the potassium borohydride solution is 0.5-1 g/L, preferably 0.8-1 g/L; the potassium borohydride solution is preferably an aqueous solution of potassium borohydride. The source of the potassium borohydride solution is not particularly limited in the present invention, and the potassium borohydride solution can be prepared by a commercially available product or a well-known preparation method well known to those skilled in the art. In the invention, the potassium borohydride solution is used as a reducing agent, and can reduce tetravalent selenium in a sample to be detected to obtain gaseous hydrogen selenide; the concentration of the potassium borohydride solution is controlled to obviously reduce the generation efficiency of lead, and the fluorescence intensity signal generated by the same lead content is obviously reduced, so that the interference of Pb on the determination of selenium by the intermittent hydride generation-atomic fluorescence spectrometer can be obviously reduced.
In the present invention, the sample to be tested is preferably a liquid; the volume ratio of the sample to be detected to the potassium borohydride solution is preferably (1-4): (4-6), more preferably 4: 5. the invention can further ensure the complete reduction reaction by controlling the volume ratio of the sample to be detected and the potassium borohydride solution.
The operation of mixing the sample to be detected and the potassium borohydride solution is not particularly limited, and the technical scheme for preparing the mixed material, which is well known by the technical personnel in the field, is adopted.
In the present invention, the acidic condition is preferably adjusted with a hydrochloric acid solution. The source of the hydrochloric acid solution is not particularly limited in the present invention, and the hydrochloric acid solution may be prepared by a commercially available product or a known preparation method known to those skilled in the art. The addition mode of the hydrochloric acid solution is not particularly limited, and the addition mode known by the person skilled in the art can be adopted. The concentration and the dosage of the hydrochloric acid solution are not specially limited, as long as the concentration of the hydrochloric acid in the reaction solution is ensured to be within the range of 1.2-2.4 mol/L.
The temperature of the reduction reaction in the present invention is not particularly limited, and a reduction reaction temperature known to those skilled in the art may be used. In the present invention, the time of the reduction reaction is not particularly limited until no gas is generated in the reaction.
In the present invention, the carrier gas is preferably argon; the flow rate of the carrier gas is preferably 600-1400 mL/min, and more preferably 800-1200 mL/min. In the invention, the carrier gas is used for introducing gaseous products (gaseous hydrogen selenide, hydrogen and gaseous lead hydride) produced by the reduction reaction into an atomizer of the non-dispersive atomic fluorescence spectrometer and realizing the mixing with the externally added hydrogen.
In the invention, the flow rate of the hydrogen is preferably 60-120 mL/min, and more preferably 80-100 mL/min. In the present invention, the hydrogen gas is preferably supplied using a hydrogen generator or experimental compressed hydrogen gas. The method adopts hydrogen to provide enough hydrogen for realizing the atomization of the substance to be detected, realizes the ignition of hydrogen flame, and makes up the problem that the hydrogen flame is difficult to ignite due to the over-low hydrogen yield caused by adopting the potassium borohydride solution with ultra-low concentration; meanwhile, the sensitivity of the selenium can be improved.
The operation of mixing the gaseous product with hydrogen in the present invention is not particularly limited, and a mixing operation known to those skilled in the art may be employed.
In the present invention, the ignition is preferably performed in an atomizer of a non-dispersive atomic fluorescence spectrometer. The invention has no special limitation on the model of the non-dispersive atomic fluorescence spectrometer, and instruments and equipment which are well known to those skilled in the art can be adopted.
The ignition operation is not particularly limited in the present invention, and an ignition operation known to those skilled in the art may be employed.
After the atoms to be detected are obtained, the atoms to be detected are detected by adopting a non-dispersive atomic fluorescence spectrometry method, and the content of selenium in the sample to be detected is obtained. The invention adopts the non-dispersive atomic fluorescence spectrometry to measure the atoms to be measured, thereby realizing the measurement of the selenium in the sample to be measured.
The operation of measuring the atoms to be measured by the non-dispersive atomic fluorescence spectrometry is not particularly limited in the present invention, and may be performed by an operation known to those skilled in the art.
According to the method, the ultralow-concentration potassium borohydride solution is adopted, so that the generation efficiency of the reaction of lead and potassium borohydride in the sample to be detected is obviously reduced, the fluorescence intensity signal generated by the same lead content is obviously reduced, the interference of Pb on selenium determination by an intermittent hydride generation-atomic fluorescence spectrometer can be obviously reduced, the hydrogen produced by the reduction reaction is insufficient due to the ultralow concentration of potassium borohydride, the hydrogen concentration is increased by using the added hydrogen, the hydrogen flame is ignited, the atom to be detected is obtained, the accurate determination of selenium in the sample to be detected is realized, and the sensitivity of selenium determination is further improved.
According to the invention, in the experiment, the interference of Pb on the determination of selenium by an intermittent hydride generation-atomic fluorescence spectrometer can be obviously reduced by the ultralow potassium borohydride concentration (0.5-1.0 g/L), and hydrogen generated by the reaction of the ultralow potassium borohydride concentration is not enough to ignite hydrogen flame.
FIG. 1 is a curve showing the relationship between the concentration of potassium borohydride and the fluorescence intensity of lead and selenium when non-dispersive atomic fluorescence spectrometry is used to measure the selenium content in the same sample to be measured. As can be seen from FIG. 1, when the concentration of potassium borohydride is reduced to 1g/L, the generation efficiency of lead is remarkably reduced, and the fluorescence intensity signal generated by the same lead content is remarkably reduced.
The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be obtained by a person skilled in the art without making any creative effort based on the embodiments in the present invention, belong to the protection scope of the present invention.
Example 1
The method for measuring selenium by using the non-dispersive atomic fluorescence spectrometry comprises the following steps:
(1) mixing 4mL of sample to be detected with 5mL of 1g/L potassium borohydride solution, adding concentrated hydrochloric acid to carry out reduction reaction, introducing a gaseous product obtained by the reduction reaction into an atomizer of a non-dispersive atomic fluorescence spectrometer through argon gas during the reduction reaction, mixing the gaseous product with hydrogen provided by a hydrogen generator, and igniting the mixture to obtain atoms to be detected; wherein the standard concentration of lead in the sample solution to be detected is 8mg/L, and the selenium content is 2 ng/mL; the flow rate of the carrier gas is 800mL/min, the flow rate of the hydrogen is 100mL/min, and the concentration of the hydrochloric acid in the reduction reaction solution is 1.2 mol/L;
(2) and (2) determining the atoms to be detected obtained in the step (1) by using a non-dispersive atomic fluorescence spectrometry method to obtain the selenium content in the sample to be detected.
Comparative example 1
The method for measuring selenium by using the nondispersive atomic fluorescence spectrometry comprises the following steps of:
(1) mixing 4mL of a sample to be detected with 5mL of 1g/L potassium borohydride solution, adding concentrated hydrochloric acid to carry out reduction reaction, introducing a gaseous product obtained by the reduction reaction into an atomizer of a non-dispersive atomic fluorescence spectrometer through argon while carrying out the reduction reaction, mixing the gaseous product with hydrogen provided by a hydrogen generator, and then igniting the gaseous product to obtain an atom to be detected; wherein the standard concentration of lead in the sample solution to be detected is 0mg/L, and the selenium content is 2 ng/mL; the flow rate of the carrier gas is 800mL/min, the flow rate of the hydrogen is 100mL/min, and the concentration of the hydrochloric acid in the reduction reaction solution is 1.2 mol/L;
(2) and (2) determining the atoms to be detected obtained in the step (1) by using a non-dispersive atomic fluorescence spectrometry method to obtain the selenium content in the sample to be detected.
Comparative example 2
The method for measuring selenium by using the nondispersive atomic fluorescence spectrometry comprises the following steps of:
(1) mixing 4mL of sample to be detected with 5mL of 10g/L potassium borohydride solution, adding concentrated hydrochloric acid to carry out reduction reaction, introducing a gaseous product obtained by the reduction reaction into an atomizer of a non-dispersive atomic fluorescence spectrometer through argon gas during the reduction reaction, mixing the gaseous product with hydrogen provided by a hydrogen generator, and igniting the mixture to obtain atoms to be detected; wherein the standard concentration of lead in the sample solution to be detected is 0mg/L, and the selenium content is 2 ng/mL; the flow rate of the carrier gas is 800mL/min, the flow rate of the hydrogen is 100mL/min, and the concentration of the hydrochloric acid in the reduction reaction solution is 1.2 mol/L;
(2) and (2) determining the atoms to be detected obtained in the step (1) by using a non-dispersive atomic fluorescence spectrometry method to obtain the selenium content in the sample to be detected.
Comparative example 3
The method for measuring selenium by using the nondispersive atomic fluorescence spectrometry comprises the following steps of:
(1) mixing 4mL of a sample to be detected with 5mL of 10g/L potassium borohydride solution, adding concentrated hydrochloric acid to carry out reduction reaction, introducing a gaseous product obtained by the reduction reaction into an atomizer of a non-dispersive atomic fluorescence spectrometer through argon while carrying out the reduction reaction, mixing the gaseous product with hydrogen provided by a hydrogen generator, and then igniting the gaseous product to obtain an atom to be detected; wherein the standard concentration of lead in the sample solution to be detected is 8mg/L, and the selenium content is 2 ng/mL; the flow rate of the carrier gas is 800mL/min, the flow rate of the hydrogen is 100mL/min, and the concentration of the hydrochloric acid in the reduction reaction solution is 1.2 mol/L;
(2) and (2) measuring the atoms to be measured obtained in the step (1) by adopting a non-dispersive atomic fluorescence spectrometry method to obtain the selenium content in the sample to be measured.
The measurement results of example 1 and comparative examples 1 to 3 are shown in table 1.
TABLE 1 measurement results of example 1 and comparative examples 1 to 3
| Example 1 | Comparative example 1 | Comparative example 2 | Comparative example 3 | |
| Selenium determination (ng/mL) | 2.27 | 2.02 | 2.0 | 3.17 |
| Relative error (%) | 13.5 | 0.9 | 0 | 58.8 |
As can be seen from Table 1, when the concentration of lead in a sample to be detected is 8mg/L and the selenium content is 2ng/mL, the interference of 13.5% is only generated by adopting 1g/L potassium borohydride solution in the embodiment 1, and the interference of 58.5% is generated by adopting 10g/L potassium borohydride solution in the comparative example 3, which indicates that the method provided by the invention can effectively inhibit the interference of lead; it can be seen from comparative example 1 and comparative example 2 that, when the sample to be detected does not contain lead, the results obtained by using 1g/L potassium borohydride solution and 10g/L potassium borohydride solution are similar, which indicates that the generation efficiency of the reaction of the low-concentration potassium borohydride solution and the tetravalent selenium is basically kept unchanged, and the generation efficiency of the selenium is not influenced by the use of the low-concentration potassium borohydride solution.
Example 2
The method for measuring selenium by using the non-dispersive atomic fluorescence spectrometry comprises the following steps:
(1) weighing 0.250g of water system sediment standard substance GBW07304a (the selenium content is 0.43 +/-0.04 mug/g, the lead content is 68 +/-3 mug/g) and placing the standard substance in a polytetrafluoroethylene beaker, adding 10mL of concentrated nitric acid with the mass concentration of 68%, 10mL of hydrofluoric acid solution with the mass concentration of 40% and 2mL of commercially available perchloric acid for digestion, placing the beaker on an electric heating plate for heating until the solution is dried, adding 10mL of 6mol/L concentrated hydrochloric acid while the solution is hot, continuing to heat for 2min, taking down the solution after cooling, transferring the solution into a 25mL test tube, fixing the volume to 25mL by deionized water, shaking up, settling, taking 4mL as a sample to be tested, mixing the sample with 5mL of 1g/L potassium borohydride solution for carrying out a reduction reaction, introducing a gaseous product obtained by the reduction reaction into an atomizer of a non-dispersive atomic fluorescence spectrometer through argon gas during the reduction reaction, mixing the gaseous product with hydrogen provided by a hydrogen generator, and then igniting the gaseous product, obtaining atoms to be detected; wherein the flow rate of the carrier gas is 800mL/min, the flow rate of the hydrogen is 100mL/min, and the concentration of the hydrochloric acid in the reduction reaction solution is 2.4 mol/L;
(2) and (2) measuring the atoms to be measured obtained in the step (1) by adopting a non-dispersive atomic fluorescence spectrometry method to obtain the selenium content in the sample to be measured.
Example 3
The method for measuring selenium by using the non-dispersive atomic fluorescence spectrometry comprises the following steps:
(1) weighing 0.250g of water system sediment standard substance GBW07304a (the selenium content is 0.43 +/-0.04 mu g/g, and the lead content is 68 +/-3 mu g/g), placing the standard substance in a polytetrafluoroethylene beaker, adding 250 mu g of lead standard solution, adding 10mL of concentrated nitric acid with the mass concentration of 68%, 10mL of hydrofluoric acid solution with the mass concentration of 40% and 2mL of commercially available perchloric acid for digestion, placing the mixture on an electric heating plate, heating the mixture to dryness, adding 10mL of concentrated hydrochloric acid with the concentration of 6mol/L while the mixture is hot, continuing to heat for 2min, taking down the mixture, cooling the mixture, transferring the cooled mixture into a 25mL test tube, adding deionized water to the volume of the mixture to 25mL, shaking the mixture evenly, standing and clarifying the mixture, taking 4mL of the sample to be tested, mixing the mixture with 5mL of 1g/L of potassium borohydride solution, carrying out a reduction reaction, introducing a gaseous product obtained by the reduction reaction into a non-dispersion atomic fluorescence atomic spectrometer by argon gas while the reduction reaction, mixing the gaseous product with hydrogen provided by a hydrogen generator, and then igniting the gaseous product, obtaining atoms to be detected; wherein the flow rate of the carrier gas is 800mL/min, the flow rate of the hydrogen is 100mL/min, and the concentration of the hydrochloric acid in the reduction reaction solution is 2.4 mol/L;
(2) and (2) measuring the atoms to be measured obtained in the step (1) by adopting a non-dispersive atomic fluorescence spectrometry method to obtain the selenium content in the sample to be measured.
Comparative example 4
The method for measuring selenium by using the nondispersive atomic fluorescence spectrometry comprises the following steps of:
(1) weighing 0.250g of water system sediment standard substance GBW07304a (the selenium content is 0.43 +/-0.04 mug/g, the lead content is 68 +/-3 mug/g) and placing the standard substance in a polytetrafluoroethylene beaker, adding 10mL of concentrated nitric acid with the mass concentration of 68%, 10mL of hydrofluoric acid solution with the mass concentration of 40% and 2mL of commercially available perchloric acid for digestion, placing the beaker on an electric heating plate for heating until the solution is dried, adding 10mL of 6mol/L concentrated hydrochloric acid while the solution is hot, continuing to heat for 2min, taking down the solution after cooling, transferring the solution into a 25mL test tube, fixing the volume to 25mL by deionized water, shaking up, settling, taking 4mL as a sample to be tested, mixing the sample with 5mL of 10g/L potassium borohydride solution for carrying out a reduction reaction, introducing a gaseous product obtained by the reduction reaction into an atomizer of a non-dispersive atomic fluorescence spectrometer through argon gas during the reduction reaction, mixing the gaseous product with hydrogen provided by a hydrogen generator, and then igniting the gaseous product, obtaining atoms to be detected; wherein the flow rate of the carrier gas is 800mL/min, the flow rate of the hydrogen is 100mL/min, and the concentration of the hydrochloric acid in the reduction reaction solution is 2.4 mol/L;
(2) and (2) determining the atoms to be detected obtained in the step (1) by using a non-dispersive atomic fluorescence spectrometry method to obtain the selenium content in the sample to be detected.
Comparative example 5
The method for measuring selenium by using the non-dispersive atomic fluorescence spectrometry comprises the following steps:
(1) weighing 0.250g of water system sediment standard substance GBW07304a (the selenium content is 0.43 +/-0.04 mu g/g, and the lead content is 68 +/-3 mu g/g), placing the standard substance in a polytetrafluoroethylene beaker, adding 250 mu g of lead standard solution, adding 10mL of concentrated nitric acid with the mass concentration of 68%, 10mL of hydrofluoric acid solution with the mass concentration of 40% and 2mL of commercially available perchloric acid for digestion, placing the mixture on an electric heating plate, heating the mixture to dryness, adding 10mL of concentrated hydrochloric acid with the concentration of 6mol/L while the mixture is hot, continuing to heat for 2min, taking down the mixture, cooling the mixture, transferring the cooled mixture into a 25mL test tube, adding deionized water to the volume of the mixture to 25mL, shaking the mixture evenly, standing and clarifying the mixture, taking 4mL of the sample to be tested, mixing the mixture with 5mL of 10g/L of potassium borohydride solution, carrying out a reduction reaction, introducing a gaseous product obtained by the reduction reaction into a non-dispersion atomic fluorescence atomic spectrometer by argon gas while the reduction reaction, mixing the gaseous product with hydrogen provided by a hydrogen generator, and then igniting the gaseous product, obtaining atoms to be detected; wherein the flow rate of the carrier gas is 800mL/min, the flow rate of the hydrogen is 100mL/min, and the concentration of the hydrochloric acid in the reduction reaction solution is 2.4 mol/L;
(2) and (2) determining the atoms to be detected obtained in the step (1) by using a non-dispersive atomic fluorescence spectrometry method to obtain the selenium content in the sample to be detected.
The results of the measurements of examples 2 and 3 and comparative examples 4 and 5 are shown in Table 2.
Table 2 measurement results of examples 2 and 3 and comparative examples 4 and 5
| Sample to be tested | Example 2 | Example 3 | Comparative example 4 | Comparative example 5 | |
| Selenium determination (μ g/g) | 0.43 | 0.431 | 0.459 | 0.436 | 0.535 |
| Relative error (%) | - | 0.2 | 6.7 | 1.4 | 24.4 |
As can be seen from Table 2, the relative error measured using 1g/L potassium borohydride solution in example 3 is 6.7%, and the relative error measured using 10g/L potassium borohydride solution in comparative example 5 is 24.4%; the relative error measured by adopting 1g/L potassium borohydride solution in the embodiment 2 is 0.2 percent, and the relative error measured by adopting 10g/L potassium borohydride solution in the comparative example 4 is 1.4 percent, which shows that the method provided by the invention can effectively inhibit the interference of lead.
Example 4
The method for measuring selenium by using the nondispersive atomic fluorescence spectrometry comprises the following steps of:
(1) weighing 0.250g of National Institute of Standards and Technology (NIST) soil standard substance SRM-2586 (with selenium content of 0.6 mug/g and lead content of 432 mug/g), placing the soil standard substance SRM-2586 in a polytetrafluoroethylene beaker, adding 10mL of concentrated nitric acid with the mass concentration of 68%, 10mL of hydrofluoric acid solution with the mass concentration of 40% and 2mL of commercially available perchloric acid for digestion, placing the mixture on an electric heating plate, heating the mixture until the mixture is dried, adding 10mL of 6mol/L concentrated hydrochloric acid while the mixture is hot, continuing to heat for 2min, taking the solution out, cooling the solution, transferring the solution into a 25mL test tube, fixing the volume to 25mL by deionized water, shaking up the solution, standing the solution, taking 4mL as a sample to be tested, mixing the sample with 5mL of 1g/L potassium borohydride solution, carrying out a reduction reaction, introducing a gaseous product obtained by the reduction reaction into an atomizer of a non-dispersive fluorescence spectrometer through argon gas while the reduction reaction, mixing the gaseous product with hydrogen provided by a hydrogen generator, and then igniting the gaseous product, obtaining atoms to be detected; wherein the flow rate of the carrier gas is 800mL/min, the flow rate of the hydrogen is 100mL/min, and the concentration of the hydrochloric acid in the reduction reaction solution is 2.4 mol/L;
(2) and (2) determining the atoms to be detected obtained in the step (1) by using a non-dispersive atomic fluorescence spectrometry method to obtain the selenium content in the sample to be detected.
Example 5
The method for measuring selenium by using the nondispersive atomic fluorescence spectrometry comprises the following steps of:
(1) weighing 0.250g of National Institute of Standards and Technology (NIST) soil standard substance SRM-2706 (with selenium content of 0.3 mug/g and lead content of 653 mug/g), placing the weighed materials in a polytetrafluoroethylene beaker, adding 10mL of concentrated nitric acid with mass concentration of 68%, 10mL of hydrofluoric acid solution with mass concentration of 40% and 2mL of commercially available perchloric acid for digestion, placing the beaker on an electric heating plate, heating the beaker until the solution is dried, adding 10mL of 6mol/L concentrated hydrochloric acid while the solution is hot, continuing to heat for 2min, taking the solution out, transferring the solution into a 25mL test tube after cooling, fixing the volume with deionized water, shaking the solution, standing and clarifying the solution, taking 4mL of the sample to be tested, mixing the sample with 5mL of 1g/L potassium borohydride solution, then carrying out a reduction reaction, introducing a gaseous product obtained by the reduction reaction into a non-dispersive atomic fluorescence spectrometer by argon gas while the reduction reaction, mixing the gaseous product with hydrogen provided by a hydrogen generator, and then igniting the gaseous product, obtaining atoms to be detected; wherein the flow rate of the carrier gas is 800mL/min, the flow rate of the hydrogen is 100mL/min, and the concentration of the hydrochloric acid in the reduction reaction solution is 2.4 mol/L;
(2) and (2) determining the atoms to be detected obtained in the step (1) by using a non-dispersive atomic fluorescence spectrometry method to obtain the selenium content in the sample to be detected.
Comparative example 6
The method for measuring selenium by using the nondispersive atomic fluorescence spectrometry comprises the following steps of:
(1) weighing 0.250g of National Institute of Standards and Technology (NIST) soil standard substance SRM-2586 (with selenium content of 0.6 mug/g and lead content of 432 mug/g), placing in a polytetrafluoroethylene beaker, adding 10mL of concentrated nitric acid with mass concentration of 68%, 10mL of hydrofluoric acid solution with mass concentration of 40% and 2mL of commercially available perchloric acid for digestion, placing on an electric hot plate, heating to dryness, adding 10mL of 6mol/L concentrated hydrochloric acid while hot, continuing to heat for 2min, taking down, cooling, transferring the solution into a 25mL test tube, fixing the volume with deionized water, shaking up, standing for clarification, mixing 4mL of a sample to be tested with 5mL of 10g/L potassium borohydride solution, carrying out a reduction reaction, introducing a gaseous product obtained by the reduction reaction into an atomizer of a non-dispersive atomic fluorescence spectrometer through argon gas while the reduction reaction, mixing with hydrogen provided by a hydrogen generator, and then igniting, obtaining atoms to be detected; wherein the flow rate of the carrier gas is 800mL/min, the flow rate of the hydrogen is 100mL/min, and the concentration of the hydrochloric acid in the reduction reaction solution is 2.4 mol/L;
(2) and (2) measuring the atoms to be measured obtained in the step (1) by adopting a non-dispersive atomic fluorescence spectrometry method to obtain the selenium content in the sample to be measured.
Comparative example 7
The method for measuring selenium by using the non-dispersive atomic fluorescence spectrometry comprises the following steps:
(1) weighing 0.250g of National Institute of Standards and Technology (NIST) soil standard substance SRM-2706 (with selenium content of 0.3 mug/g and lead content of 653 mug/g), placing the weighed materials in a polytetrafluoroethylene beaker, adding 10mL of concentrated nitric acid with mass concentration of 68%, 10mL of hydrofluoric acid solution with mass concentration of 40% and 2mL of commercially available perchloric acid for digestion, placing the beaker on an electric heating plate, heating the beaker until the solution is dried, adding 10mL of 6mol/L concentrated hydrochloric acid while the solution is hot, continuing to heat for 2min, taking the solution out, cooling the solution, transferring the solution into a 25mL test tube, fixing the volume with deionized water, shaking the solution, standing and clarifying the solution, taking 4mL of the sample to be tested, mixing the sample with 5mL of 10g/L potassium borohydride solution, then carrying out a reduction reaction, introducing a gaseous product obtained by the reduction reaction into a non-dispersive atomic fluorescence spectrometer by argon gas while the reduction reaction, mixing the gaseous product with hydrogen provided by a hydrogen atomic generator, and then igniting the gaseous product, obtaining atoms to be detected; wherein the flow rate of the carrier gas is 800mL/min, the flow rate of the hydrogen is 100mL/min, and the concentration of the hydrochloric acid in the reduction reaction solution is 2.4 mol/L;
(2) and (2) measuring the atoms to be measured obtained in the step (1) by adopting a non-dispersive atomic fluorescence spectrometry method to obtain the selenium content in the sample to be measured.
The results of the measurements on examples 4 and 5 and comparative examples 6 and 7 are shown in Table 3.
Table 3 measurement results of examples 4 and 5 and comparative examples 6 and 7
As can be seen from Table 3, the relative errors measured by using 1g/L potassium borohydride solution in examples 4 and 5 are respectively 4.08% and 4.21%, and the relative errors measured by using 10g/L potassium borohydride solution are respectively 24.18% and 43.00%, which indicates that the method provided by the invention can effectively inhibit the interference of lead.
As can be seen from the above examples and comparative examples, the method provided by the invention can significantly reduce the interference of Pb on the determination and improve the accuracy of the selenium content.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and amendments can be made without departing from the principle of the present invention, and these modifications and amendments should also be considered as the protection scope of the present invention.
Claims (10)
1. A method for measuring selenium by non-dispersive atomic fluorescence spectrometry comprises the following steps:
(1) mixing a sample to be detected with a potassium borohydride solution, then carrying out a reduction reaction under an acidic condition, mixing a gaseous product of the reduction reaction with hydrogen through a carrier gas during the reduction reaction, and then igniting to obtain an atom to be detected; the concentration of the potassium borohydride solution is 0.5-1 g/L;
(2) and (2) determining the atoms to be detected obtained in the step (1) by using a non-dispersive atomic fluorescence spectrometry method to obtain the selenium content in the sample to be detected.
2. The method of claim 1, wherein the elemental selenium in the sample to be tested in step (1) is present as tetravalent selenium.
3. The method according to claim 1, wherein the concentration of the potassium borohydride solution in the step (1) is 0.8-1 g/L.
4. The method according to claim 1, wherein the sample to be tested in the step (1) is a liquid, and the volume ratio of the sample to be tested to the potassium borohydride solution is (1-4): (4-6).
5. The method according to claim 4, wherein the volume ratio of the sample to be tested to the potassium borohydride solution is 4: 5.
6. the method according to claim 1, wherein the carrier gas in step (1) is argon.
7. The method according to claim 1 or 6, wherein the flow rate of the carrier gas in the step (1) is 600-1400 mL/min.
8. The method according to claim 1, wherein the flow rate of the hydrogen in the step (1) is 60-120 mL/min.
9. The method according to claim 8, wherein the flow rate of the hydrogen gas is 80 to 100 mL/min.
10. The method according to claim 1, wherein the igniting in step (1) is performed in an atomizer of a non-dispersive atomic fluorescence spectrometer.
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