A method for rapid simultaneous determination of chlorine, bromine, and iodine using high-temperature hydrolysis and ICP-MS

Abstract

The method for simultaneously and rapidly determining chlorine, bromine and iodine by combining high-temperature hydrolysis and ICP-MS includes the following steps: put the object to be measured into a sample container, lay asbestos on the surface of the object to be measured, and perform high-temperature hydrolysis treatment, i.e., first selectively preheat at 500-600℃ for 3-10min, further heat at 700-800℃ for 3-10min, and then burn at 1000-1100℃ for 10-30min; obtain calibration curves of the concentration and net strength values ​​corresponding to each element; and use ICP-MS to combine the online internal standard method to test the net strength of the liquid in step (1), and combine the calibration curves to obtain the chlorine, bromine and iodine contents in the object to be measured;

Description

[Technical field]

[0001] The present invention belongs to the technical field of Cl, Br, and I detection, and specifically relates to a method for simultaneously and rapidly measuring chlorine, bromine, and iodine by combining high-temperature hydrolysis and ICP-MS. [Background technology]

[0002] Chlorine, bromine and iodine are closely related to human health and are also of great significance in environmental research. For example, chlorine is a nutrient necessary for the growth of animals and plants, and excessive or insufficient intake will cause poor growth of animals and plants. The content of bromine in the body can affect the metabolism of iodine, thereby affecting the health of the body, and a large amount of bromine intake will reduce the accumulation of iodine in the thyroid gland and mammary gland, and aggravate the loss of iodine in the kidneys. Iodine is involved in the synthesis of thyroxine in the human body and plays an important role in the development of the human body and brain. Bromine and iodine are also important indicators of the evolutionary process of the earth, and are often used in the reconstruction of paleoenvironments and the exploration of the alteration history of rocks. Chlorine, bromine and iodine in the atmospheric environment can also destroy the ozone layer and affect global climate change. Due to the low content of halogens in the environment, their easy volatility and large interference, it is of great significance to accurately measure the content of halogens in different substrates to evaluate the halogen environmental effects.

[0003] Currently, the commonly used methods for measuring chlorine, bromine and iodine include spectrophotometry, ion chromatography, ion selective electrode and ICP-MS. Among them, spectrophotometry requires manual operation, complicated steps, high professional requirements for experimenters, and cannot measure two or more elements simultaneously, while ion chromatography and ion selective electrode methods have problems of high detection limit and low sensitivity in measuring chlorine, bromine and iodine. However, ICP-MS, as a commonly used method for measuring inorganic ions in solution, has high sensitivity, low detection limit, good stability, and can detect various elements simultaneously, and is widely used in the field of chemical detection.

[0004] The conventional pretreatment methods for separating and collecting chlorine, bromine and iodine from complex substrates include acid fusion, alkali fusion, microwave dissolution and high-temperature hydrolysis. The acid fusion and alkali fusion methods use the difference between acid and alkali of each component to be measured in complex substrates to separate them, which requires manual operation by the experimenter, which is time-consuming, and a large amount of acid and alkali reagents are used during detection, which will cause a certain degree of pollution to the environment. The microwave dissolution technology uses microwaves to heat the reagent and sample in a sealed container and quickly dissolve the sample under high-temperature and pressurized conditions. The addition of the dissolution liquid is easy to introduce interference elements, and the microwave dissolution device is expensive, so the experimental conditions are relatively high. High-temperature hydrolysis is a hydrolysis reaction that occurs between the sample and water vapor under high-temperature conditions, in which the halides are converted into hydrohalic acid and dissolved in the absorption liquid. High-temperature hydrolysis can process inorganic and organic samples without introducing interference components, and is widely used in halogen detection.

[0005] CN108802156B discloses a method for determining the iodine content in coal. The specific treatment process is to heat at 300, 600, 800℃ for 5 min, and then heat at 1400-1500℃ for 10-20 min, with oxygen gas flow rate of 0.15-0.2L / min and water vapor flow rate of 0.5-1L / min, and use 0.1mol% NaOH for absorption, and then detection.

[0006] CN105675698A discloses a method for determining Br in coal. The specific treatment process is to heat and keep at 1050-1150℃ for 20-30min, with oxygen gas at 0.18-0.22L / min and water vapor at 0.8-1.2mL / min, and use 10g / L NaOH for absorption, and then detection.

[0007] The above-mentioned conventional techniques all use high-temperature hydrolysis to treat the samples. CN108802156B grinds the experimental sample to 100 mesh and mixes it with quartz sand before combustion. However, the quartz sand particles are easily blown up by the carrier gas flow during the experiment or some samples are burned violently and scattered, remaining in the combustion tube, which affects the smooth progress of the sample in the sample boat. CN105675698A crushes the sample to 200 mesh and directly combusts it, but the detection accuracy of these two methods needs to be further improved. In addition, in CN105675698A, the knocking phenomenon occurs in the coal sample during combustion, and the detection method is the method of selecting an ion selective electrode, which requires the pH value of the absorption liquid after high-temperature hydrolysis to be adjusted, which is complicated to operate, and the detection limit is high, making it impossible to detect low contents of iodine. And both of them only detect the content of one ion. Summary of the Invention

[0008] The objective of the present invention is to provide a method for simultaneously and rapidly determining chlorine, bromine and iodine by combining high temperature hydrolysis and ICP-MS in order to overcome the drawbacks of the prior art, such as the occurrence of knocking during combustion and the need to further improve the detection accuracy, the complicated operation and the high detection limit. This method can avoid the knocking phenomenon, is simple, rapid and environmentally friendly in operation, has high detection accuracy, and can simultaneously and rapidly detect the contents of trace amounts of chlorine, bromine and iodine in the measured material, and the detection limit of the method is much lower than that of detection methods such as ion selective electrode method, ion chromatography method and colorimetric method.

[0009] In order to achieve the above object, the present invention provides a method for simultaneously and rapidly measuring chlorine, bromine and iodine by combining high-temperature hydrolysis and ICP-MS, the method comprising: A step (1) of placing an object to be measured in a sample container, laying asbestos on the surface of the object to be measured, and then performing a high-temperature hydrolysis treatment, The process of high-temperature hydrolysis treatment includes step (1) of selectively preheating at 500-600°C for 3-10 minutes, further heating at 700-800°C for 3-10 minutes to burn organic matter in the test object, and then burning at 1000-1100°C for 10-30 minutes; (2) preparing a series of concentration calibration curve solutions and internal standard solutions, and testing their net intensities respectively by coupling an online internal standard method using an ICP-MS instrument to obtain calibration curves of concentration values ​​and net intensity values ​​corresponding to each element; and (3) using an ICP-MS instrument to couple an online internal standard method to test the net strength of the liquid obtained in step (1), couple the calibration curve to obtain the concentrations of chlorine, bromine and iodine in the liquid, and further obtain the contents of chlorine, bromine and iodine in the measured object.

[0010] In some preferred embodiments of the invention, the method further comprises, prior to step (1), subjecting the sample container and the asbestos to a high-temperature hydrolysis pretreatment.

[0011] More preferably, the process of high temperature hydrolysis pretreatment includes firing at 1000-1100°C for 5-10 min.

[0012] In some preferred embodiments of the present invention, the conditions of the high-temperature hydrolysis treatment or the high-temperature hydrolysis pretreatment are: The oxygen gas flow rate of the inner tube of the combustion tube is 50-100mL / min, the oxygen gas flow rate of the outer tube of the combustion tube is 50-200mL / min, the blow decomposition water oxygen gas flow rate is 50-200mL / min, the final constant volume is 10-50mL, including 3-10mL of absorption liquid, 4-30mL of decomposition water, and 3-10mL of cleaning liquid.

[0013] Preferably, both the absorbing liquid and the washing liquid are aqueous ammonia having a mass concentration of 0.1-1%.

[0014] Preferably, the decomposition water is primary laboratory water.

[0015] In some preferred embodiments of the present invention, the workstation tuning parameters of the ICP-MS instrument in steps (2) and (3) are: Re>2000, In>40000, U>30000, CeO / Ce≦0.025, The Ce++ / Ce≦0.04 is set.

[0016] In some preferred embodiments of the invention, the experimental parameters of the ICP-MS instrument in steps (2) and (3) include: Device mode: Standard mode, Radio frequency power: 1500W, Plasma gas flow rate: 18 L / min, Auxiliary gas flow rate: 1.2L / min, Atomizer gas flow rate: 0.96L / min, Number of test points: 3, Sampling cone: platinum cone, Detection method: Peak jump, Internal standard: rhodium, Internal standard addition method: Online addition of internal standard solution, Spray chamber rubber ring: Fluorine rubber.

[0017] In some preferred embodiments of the present invention, the specific process of step (2) comprises: A step (201) of preparing a series of calibration curve solutions containing chlorine, bromine, and iodine by taking a single element standard solution of chlorine, bromine, and iodine, respectively; Taking an internal standard element standard solution and preparing an internal standard solution (202); The method includes the step of injecting the calibration curve solutions of the series of concentrations into an ICP-MS instrument, respectively, measuring the contents of chlorine, bromine and iodine using the internal standard solutions by an online internal standard method, and obtaining calibration curves of the concentration values ​​and net intensity values ​​corresponding to each element (203).

[0018] In some preferred embodiments of the present invention, the internal standard element in the internal standard solution is rhodium, and / or the concentration of the internal standard element in the internal standard solution is 30-80 μg / L.

[0019] In some preferred embodiments of the present invention, the concentration of chloride in the calibration solution is 500 μg / L-3000 μg / L, the concentration of bromide is 0.5 μg / L-100 μg / L, and the concentration of iodine is 0.1 μg / L-100 μg / L.

[0020] According to the research of the inventors of the present invention, experimental samples, especially biological samples, contain a large amount of organic matter, so if they are directly burned at 1000-1100℃, knocking will occur, accompanied by the generation of fine black carbon powder, which will contaminate the inside of the combustion tube, the absorption bottle, the collection pipe and the sample solution to be measured. The above CN108802156B and CN105675698A are both high-temperature hydrolysis, but when the sample is injected during combustion, it is blown up by oxygen gas, which affects the experimental results and the detection accuracy.

[0021] The present invention combines high-temperature hydrolysis with ICP-MS, and combines asbestos coating, heating and selective preheating to prevent the phenomena of sample knocking, scattering, and blowing up, and can rapidly, accurately and stably measure the content of chlorine, bromine and iodine in different samples, and can detect various halogens with lower contents while being simple, rapid and environmentally friendly. The method of the present invention has the characteristics of simple operation, fast measurement speed, high sensitivity and low detection limit. Here, by using heating and selective preheating during high-temperature hydrolysis treatment, the phenomenon of sample knocking can be eliminated, and by coating the sample surface with a layer of asbestos, it is possible to effectively prevent the fine powder sample from being blown up by oxygen gas when it is injected, and also avoid the pipe pollution caused by solid particles generated during sample combustion.

[0022] The method of the present invention can simultaneously detect trace amounts of chlorine, bromine and iodine in soil, water sediments, rocks and biological samples, and the detection limit of the method is much lower than that of detection methods such as ion selective electrode method, ion chromatography method and colorimetric method. In the method of the present invention, the detection range of Br is 0.5μg / L-100μg / L, the detection limit is 0.12μg / L, and the quantification limit is 0.082μg / g. The detection range of I is 0.1μg / L-100μg / L, the detection limit is 0.03μg / L, and the quantification limit is 0.022μg / g. The detection range of Cl is 500μg / L-3000μg / L, the detection limit is 24.93μg / L, and the quantification limit is 16.26μg / g, which is applicable to trace and ultratrace analysis.

[0023] According to further research by the inventors of the present invention, sample containers and asbestos contain different amounts of Cl, Br, and I, which affects the accuracy of detection. In contrast, in the preferred method of the present invention, sample containers (such as new sample boats) and asbestos are first subjected to high-temperature hydrolysis pretreatment, and the Cl, Br, and I contents thereon are obviously reduced, and the background values ​​are almost the same. Impurities are then removed, and samples are then loaded for detection, thereby eliminating the interference factors between the impurities in the sample containers and asbestos themselves, making the background values ​​consistent, and making the results more accurate. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] The endpoints of any ranges and any values ​​disclosed herein are not limited to the exact ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, and the endpoints of each range and any single point value, and the single point values ​​can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be considered to be specifically disclosed herein.

[0025] The present invention provides a method for simultaneously and rapidly determining chlorine, bromine and iodine by combining high temperature hydrolysis and ICP-MS, which includes the following steps:

[0026] (1) Place the object to be measured in a sample container, lay asbestos on the surface of the object, and then perform high-temperature hydrolysis treatment. Here, the process of high-temperature hydrolysis treatment includes selectively preheating at 500-600°C for 3-10 minutes, further heating at 700-800°C for 3-10 minutes to combust the organic matter in the test object, and then burning at 1000-1100°C for 10-30 minutes, that is, after heating and burning, preheating may or may not be performed; (2) Prepare a series of concentration calibration curve solutions and internal standard solutions, and test their net intensities respectively using an ICP-MS instrument (i.e., inductively coupled plasma mass spectrometer) in conjunction with the online internal standard method to obtain calibration curves of the concentration values ​​and net intensity values ​​corresponding to each element; (3) Using an ICP-MS instrument, combine online internal standard method to test the net strength of the liquid obtained in step (1), and combine the calibration curve to obtain the concentrations of chlorine, bromine and iodine in the liquid, and further obtain the contents of chlorine, bromine and iodine in the measured object.

[0027] It should be understood that the sample container of the present invention is a container capable of carrying a sample applied to the high-temperature hydrolysis treatment, and may be, for example, a sample boat.

[0028] According to the inventor's research, experimental samples (i.e., objects to be measured), especially biological samples, contain a large amount of organic matter, so if they are directly combusted at 1000-1100°C, knocking occurs, accompanied by the generation of fine black carbon powder, which contaminates the inside of the combustion tube, the absorption bottle, the collection pipe, and the sample solution to be measured. On the other hand, the present invention heats the sample at 700-800°C before combustion, which can fully burn almost all organic matter in the sample and eliminate the phenomenon of knocking during the sample combustion. However, if the sample is heated above 800°C, the knocking phenomenon is likely to occur and the combustion tube is polluted. On the other hand, the present invention lays asbestos on the surface of the object to be measured, which can effectively prevent the fine powder sample from being blown up by oxygen gas when it is injected, and can also avoid the pipe contamination caused by solid particles generated during the sample combustion. Asbestos is a silicate mineral product that has high tensile strength, high flexibility, is resistant to chemical and thermal erosion, and is electrically insulated, and does not contain substances such as chlorine, bromine, and iodine to be detected, so it does not affect the detection results.

[0029] The temperature of the combustion is 1000-1100°C, which can sufficiently promote the hydrolysis reaction of various halogens and ensure the recovery rate.

[0030] The 3-10 min preheating may be, for example, 3, 4, 5, 6, 7, 8, 9, 10 min, etc. The 3-10 min heating may be, for example, 3, 4, 5, 6, 7, 8, 9, 10 min, etc. The 10-30 min burning may be, for example, 10, 12, 15, 17, 19, 20, 24, 26, 28, 30 min, etc.

[0031] In some preferred embodiments of the present invention, the conditions of the high-temperature hydrolysis treatment include: oxygen gas flow rate of the inner tube of the combustion tube is 50-100mL / min, oxygen gas flow rate of the outer tube of the combustion tube is 50-200mL / min, and blow decomposition water oxygen gas flow rate is 50-200mL / min. In this preferred method, the oxygen gas flow rate is appropriate, which promotes the complete absorption of the measured substance and is favorable for more accurate detection. On the other hand, under the same conditions, if the oxygen gas flow rate is too small, the gas product of hydrolysis cannot be blown into the absorption bottle to be absorbed, resulting in incomplete absorption, and if the oxygen gas is too small, the sample oxidation will be incomplete, the measured substance will remain in the combustion tube, and the test value will be low; if the oxygen gas flow rate is too large, the absorption will be incomplete, and some of the measured substance will not be completely absorbed by the absorption liquid and will be discharged together with the gas, resulting in a low recovery rate and a low test value; if the gas flow rate is too large, the solution in the collection bottle will be splashed.

[0032] In some preferred embodiments of the present invention, the high temperature hydrolysis conditions further include a final constant volume of 10-50 mL, including 3-10 mL of absorption solution, 4-30 mL of decomposition water, and 3-10 mL of wash solution.

[0033] Preferably, the absorption liquid and the cleaning liquid are both ammonia water with a mass concentration of 0.1-1%. In this preferred method, the effect of dilute ammonia water is more stable, the absorption effect is maximized (both can reach about 100%), and the recovery rates of chlorine, bromine, and iodine can be maximized, which is favorable for more accurate detection, and the ammonia water can avoid corrosion of the spray chamber (glass material) of the ICP-MS instrument. Meanwhile, under the same conditions, when the concentration of ammonia water is lower than 0.1%, the absorption effect is poor and the test value is low, and when the concentration of ammonia water is higher than 1%, the butyronitrile rubber ring in the spray chamber will have the effect of corrosion and expansion, which will affect the service life of the instrument. However, the commonly adopted NaOH solution is corrosive to the spray chamber of the ICP-MS instrument.

[0034] Preferably, the decomposition water is primary laboratory water.

[0035] In some preferred embodiments of the present invention, the method further includes a step of subjecting the sample container and asbestos to high-temperature hydrolysis pretreatment before step (1). In this preferred method, the halogen-based impurities on the sample container and asbestos can be removed, and the contents of Cl, Br, and I are obviously reduced, and the background values ​​are almost the same, thus eliminating the interference factors between the impurities in the sample container and the asbestos itself, making the background values ​​consistent, and further improving the detection accuracy of chlorine, bromine, and iodine in the measured object. This is because a new boat, or a long-term storage of the sample boat, or a long-term storage of asbestos in air may adsorb certain halogen-based impurities, which will affect the detection accuracy. In some specific embodiments, a new sample boat is taken as an example, and the specific detection results before and after one high-temperature hydrolysis pretreatment (burning at 1100°C for 5 minutes) are shown in Table 1 below. As can be seen from Table 1, after high-temperature hydrolysis pretreatment, the contents of Cl, Br, and I are obviously reduced, eliminating the interference factors of the impurities in the sample container itself, and improving the detection accuracy.

[0036] [Table 1]

[0037] More preferably, the process of high-temperature hydrolysis pretreatment includes burning at 1000-1100°C for 5-10min. After the high-temperature hydrolysis pretreatment is completed, the collected pretreatment solution may be directly discharged into a waste bottle without detection.

[0038] In some specific embodiments, the high-temperature hydrolysis pretreatment process includes: using tweezers to pick up a new sample boat, placing it on the sample tray of the automatic injection system after laying a layer of asbestos on the bottom, using an electric hand to pick up the sample boat and put it into the sample chamber, and using a pusher to push the sample boat into a combustion tube at 1000-1100°C for 5-10 minutes to perform high-temperature hydrolysis treatment.

[0039] In some preferred embodiments of the present invention, the high-temperature hydrolysis pretreatment conditions are: The oxygen gas flow rate of the inner tube of the combustion tube is 50-100mL / min, the oxygen gas flow rate of the outer tube of the combustion tube is 50-200mL / min, the blow decomposition water oxygen gas flow rate is 50-200mL / min, and the final constant volume is 10-50mL, including 3-10mL of absorption liquid, 4-30mL of decomposition water, and 3-10mL of cleaning liquid.

[0040] Preferably, both the absorbing liquid and the washing liquid are aqueous ammonia having a mass concentration of 0.1-1%.

[0041] Preferably, the decomposition water is primary laboratory water.

[0042] In the present invention, samples such as rocks, soils, water-based sediments, biological samples, petroleum, coal, plastics, semiconductor materials, etc. may all be used in the present invention.

[0043] The preheating and heating according to the present invention are both used to burn organic matter in the object to be measured. Those skilled in the art can choose whether to perform the preheating or not depending on the content of organic matter in the object to be measured. In the present invention, the preheating is performed for objects with a high content of organic matter, and not otherwise. The preheating of the present invention allows the organic matter in the object to be burned before the chlorine, bromine, and iodine substances, further reducing the possibility of knocking. On the other hand, under the same conditions, when the preheating temperature is lower than 500°C, the combustion of the organic matter is incomplete and the combustion time is long, and when the preheating temperature is higher than 600°C, the knocking phenomenon is likely to occur, which contaminates the combustion tube.

[0044] In some preferred embodiments of the present invention, the workstation tuning parameters of the ICP-MS instrument in steps (2) and (3) are: Re>2000, In>40000, U>30000, CeO / Ce≦0.025, The Ce++ / Ce≦0.04 is set.

[0045] In some preferred embodiments of the invention, the experimental parameters of the ICP-MS instrument in steps (2) and (3) include: Device mode: Standard mode, Radio frequency power: 1500W, Plasma gas flow rate: 18 L / min, Auxiliary gas flow rate: 1.2L / min, Atomizer gas flow rate: 0.96L / min, Number of test points: 3, Sampling cone: platinum cone, Detection method: Peak jump, Internal standard: rhodium, Internal standard addition method: Online addition of internal standard solution, Spray chamber rubber ring: Fluorine rubber.

[0046] According to the research of the inventors of the present invention, in the above-mentioned preferred experimental parameter scheme, the ICP-MS instrument mode is the standard mode, i.e., no gas is passed through the collision reaction cell. Compared with the collision mode of kinetic energy discrimination mode (KED) (i.e., helium gas is introduced into the collision cell of the ICP-MS to collide He with polyatomic interference ions), not only are the linearity of the Cl, Br, and I calibration curve solutions all better, the accuracy of the correlation coefficients of the calibration curve is higher, the measurement results are basically consistent, the operation is simple, and there is no need to use other gases such as helium gas and ammonia gas, so the cost is low.

[0047] In some preferred embodiments of the present invention, the specific process of step (2) comprises: A step (201) of preparing a series of calibration curve solutions containing chlorine, bromine, and iodine by taking a single element standard solution of chlorine, bromine, and iodine, respectively; Taking an internal standard element standard solution and preparing an internal standard solution (202); The method includes the step of injecting the calibration curve solutions of the series of concentrations into an ICP-MS instrument, respectively, measuring the contents of chlorine, bromine and iodine using the internal standard solutions by an online internal standard method, and obtaining calibration curves of the concentration values ​​and net intensity values ​​corresponding to each element (203).

[0048] Those skilled in the art can select a series of concentrations of the calibration solution according to needs, as long as the calibration curve obtained is advantageous to facilitate the subsequent accurate detection of the chlorine, bromine and iodine contents.

[0049] It should be understood that the calibration solution series of concentrations contains the same material as the absorption solution, for example aqueous ammonia.

[0050] In some preferred embodiments of the present invention, the internal standard element in said internal standard solution is rhodium.The present invention uses internal standard to eliminate instrument drift and matrix effect, and can further ensure that the content of internal standard in calibration curve and measurement sample is consistent by adding internal standard online, avoiding the error caused by artificial addition.The present inventor considers the effect of three kinds of internal standards, In, Te and Rh, and finds that the effect of using Rh as internal standard is the highest, and its recovery rate is always stable at 92%-116%, and the result of 12 consecutive sample measurements is also very stable, which can significantly eliminate the signal drift of ICP-MS.

[0051] In some preferred embodiments of the present invention, the concentration of the internal standard element in the internal standard solution is 30-80 μg / L.

[0052] In some preferred embodiments of the present invention, the concentration of chloride in the calibration solution is 500 μg / L-3000 μg / L, the concentration of bromide is 0.5 μg / L-100 μg / L, and the concentration of iodine is 0.1 μg / L-100 μg / L.

[0053] In step (203), preferably, obtaining the calibration curves of the concentration values ​​and net intensity values ​​corresponding to each element specifically includes: taking the concentration values ​​of a series of calibration curve solutions as the abscissa and the corresponding net intensity values ​​as the ordinate, and linearly fitting the detection data to obtain the calibration curves of the concentration values ​​and net intensity values ​​of chlorine, bromine and iodine, respectively.

[0054] In the step (3) of the present invention, preferably, the step of obtaining the contents of chlorine, bromine and iodine in the object to be measured specifically includes substituting the obtained concentrations c of chlorine, bromine and iodine in the liquid into the following formula (1) to calculate the content M of the measurement target element in the object to be measured: M=c*v / m×10 -3 (1) Here, M is the amount of the target element precipitated in the sample, expressed in μg / g. c is the concentration in the liquid to be measured, in μg / L; v is the high temperature hydrolysis constant volume, in mL; m is the mass of the object to be measured, expressed in g.

[0055] The method of the present invention combines high-temperature hydrolysis and ICP-MS, making pretreatment simple and rapid, and environmentally friendly. It can simultaneously and rapidly detect trace amounts of chlorine, bromine and iodine in the sample, and the detection limit of the method is much lower than that of detection methods such as ion selective electrode method, ion chromatography method and colorimetric method.

[0056] The present invention can simultaneously measure ppm-level Cl and ppb-level Br and I. However, the conventional methods all use ion chromatography to measure Cl and I to measure Br and I, which require several operations, complicated steps, and long detection times.

[0057] The present invention will be described in more detail below in conjunction with specific examples.

[0058] Example 1 This method uses high-temperature hydrolysis and ICP-MS in combination to rapidly measure chlorine, bromine and iodine simultaneously, and specifically includes the following steps:

[0059] a. High-temperature hydrolysis pretreatment of samples: (1) Sample boat and asbestos pretreatment: Treatment process: Use tweezers to grab a new sample boat, lay a layer of asbestos on the bottom, and then place it on the sample tray of the automatic injection system. Use an electric hand to grab the sample boat and put it into the sample chamber. Use a pusher to push the sample boat into the combustion tube at 1100°C and burn it for 5 minutes to perform high-temperature hydrolysis treatment. During the whole process, the oxygen gas flow rate of the inner tube of the combustion tube is 50mL / min, the oxygen gas flow rate of the outer tube is 50mL / min, the water oxygen gas flow rate of the blow decomposition water is 50mL / min, the final constant volume is 10mL, containing 3mL of ammonia water with a mass concentration of 0.1% in the absorption liquid, 4mL of the primary test water which is the decomposition water, and 3mL of ammonia water with a mass concentration of 0.1% in the cleaning liquid, and the high-temperature hydrolysis treatment is completed.

[0060] (2) Soil sample (one step heating): Treatment process: Use tweezers to grab a pre-treated sample boat, weigh 0.1g of sample with a balance and pour it evenly into the sample boat, lay a layer of pre-treated asbestos on the sample surface, place the sample boat on the sample tray of the automatic injection system, use the electric hand to grab the sample boat and put it into the sample chamber, use the pusher to push the sample boat into the combustion tube for high-temperature hydrolysis treatment, first heat at 700℃ for 3min, then push to 1100℃ and burn for 20min, during the whole process, the oxygen gas flow rate of the inner tube of the combustion tube is 50mL / min, the oxygen gas flow rate of the outer tube is 50mL / min, the water oxygen gas flow rate of the blow decomposition water is 100mL / min, the final constant volume is 20mL, containing 5mL of ammonia water with a mass concentration of 0.1% as the absorption liquid, 10mL of the primary test water which is the decomposition water, and 5mL of ammonia water with a mass concentration of 0.1% as the cleaning liquid, the high-temperature hydrolysis treatment is completed, and the solution in the collection bottle at this time is the sample solution to be measured by ICP-MS.

[0061] b. Drawing of the calibration curve Standard solution A is transferred to a 100 mL volumetric flask and contains 1000 μg of bromide ion per liter, standard solution B is transferred to a 100 mL volumetric flask and contains 1000 μg of iodide ion per liter, and standard solution C is transferred to a 100 mL volumetric flask and contains 1000 mg of chloride ion per liter. 250, 500, 1500, 2500, 5000μL of standard solution A, 25, 50, 500, 1000, 1500μL of standard solution B, and 40, 50, 100, 125, 150μL of standard solution C were transferred into a series of 50mL measuring flasks, into which 2.5mL of 1wt% ammonia water was added, diluted to scale with water, and mixed uniformly to obtain a series of calibration curve solutions, in which the bromide ion concentrations are 5, 10, 30, 50, 100μg / L, the iodide ion concentrations are 0.5, 1, 10, 20, 30μg / L, and the chloride ion concentrations are 800, 1000, 2000, 2500, 3000μg / L, respectively. Each calibration curve solution contains chloride, bromide, and iodide ions. 5μL of the rhodium single element standard solution (rhodium concentration is 1000mg / L) was taken into a 100mL measuring flask, diluted with water to scale and mixed uniformly to prepare an internal standard solution with a concentration of 50μg / L. The calibration curve solutions of the above concentration series were injected into an inductively coupled plasma mass spectrometer, and the contents of chlorine, bromine and iodine were measured by the online internal standard method.

[0062] The concentration values ​​of different standard solutions were taken as the abscissa and the corresponding net intensity values ​​as the ordinate, and the detection data progression was linearly fitted to obtain the calibration curves of the concentration values ​​and net intensity values ​​of chlorine, bromine and iodine, respectively.

[0063] c. Measurement of the content of the substance to be measured in the sample absorption liquid Start the ICP-MS instrument and software and adjust the vacuum to 2.0 x 10. -6After the pressure drops below mbar, the instrument is ignited and the moment tube correction is performed after the instrument has stabilized for 30 min. The following workstation tuning parameters and ICP-MS instrument experimental parameters are used to ensure that the ICP-MS resolution, sensitivity, double charge, oxide, background and other parameters meet the analytical requirements.

[0064] The workstation tuning parameters for the inductively coupled plasma mass spectrometer are: Re>2000, In>40000, U>30000, CeO / Ce≦0.025, The Ce++ / Ce was set at ≦0.04.

[0065] ICP-MS instrument experimental parameters are: Device mode: Standard mode, Radio frequency power: 1500W, Plasma gas flow rate: 18 L / min, Auxiliary gas flow rate (argon gas): 1.2 L / min, Sprayer gas flow rate (argon gas): 0.96 L / min, Number of test points: 3, Sampling cone: platinum cone, Detection method: Peak jump, Internal standard: rhodium Rh, Internal standard addition method: Online addition of internal standard solution, Spray chamber rubber ring: Fluorine rubber.

[0066] First, a series of calibration solutions with different concentrations obtained in step b were measured to determine the calibration curves of chlorine, bromine and iodine using the internal standard method, and the calibration curve equations and related coefficients are shown in Table 2.

[0067] [Table 2]

[0068] Then, the concentration c of the sample solution to be measured obtained after high-temperature hydrolysis of the sample in step a was detected.

[0069] d. Analytical calculation The measured ion concentration value c is substituted into the formula to calculate and analyze the content M of the measured element in the sample. M=c*v / m×10 -3 (1) Here, M is the amount of the target element precipitated in the sample, expressed in μg / g. c is the concentration in the liquid to be measured, in μg / L; v is the high temperature hydrolysis constant volume, in mL; m is the quality of the weighing of the object to be measured, g.

[0070] In this example, there was no knocking phenomenon. Different parallel samples were taken from all the batches of samples in this example to test, and the specific test results of the detection limit, measurement limit and method precision are shown in Table 3.

[0071] Example 2 Referring to the method of Example 1, the difference is that in step a, biological sample rice is used instead of soil, and high-temperature hydrolysis is performed, which is first preheated at 500°C for 5 minutes, then heated to 700°C for 5 minutes, and then fired at 1100°C for 20 minutes. The other conditions are the same as those of Example 1.

[0072] The specific test results are shown in Table 4.

[0073] Example 3 Referring to the method of Example 2, the difference is that in the high-temperature hydrolysis treatment of rice in step a, the preheating time is 10 min, the heating time is 10 min, and the burning time is 20 min.

[0074] The specific test results are shown in Table 4.

[0075] Comparative Example 1 Referring to the method of Example 2, the difference is that no preheating was performed. Specifically, in step a, high-temperature hydrolysis treatment was performed using biological sample rice, which was heated at 700°C for 10 min and combusted at 1100°C for 20 min.

[0076] In this comparative example, without preheating, the large amount of organic matter in the rice could not be burned, causing knocking, and a large amount of black carbon powder was generated and ejected, adhering to the inner wall and outlet of the combustion tube, the condenser tube, and the constant volume pipe, affecting the measurement results. The experimental phenomenon and test results are shown in Table 4.

[0077] Comparative Example 2 Referring to the method of Example 2, the difference is that no asbestos-coated sample is adopted in step a. The specific test results are shown in Table 4.

[0078] [Table 3]

[0079] [Table 4]

[0080] As can be seen from the above results, by adopting the method of the embodiment of the present invention, the sample with high organic content can be incinerated at 500°C and then pushed into the medium and high temperature range to effectively prevent knocking; by adding asbestos, knocking and sample scattering can be prevented to a certain extent; and the detection values ​​of chlorine, bromine and iodine are relatively accurate, with obviously small deviations compared to the comparative example.

[0081] As can be seen from Table 4, in the sample of Comparative Example 2, which did not contain asbestos and was incinerated at 500°C for 5 minutes, then burned at 700°C for 5 minutes, and finally burned at 1100°C for 20 minutes, no carbon powder or the like was visible to the naked eye. However, the Br and I contents were both lower than those of the sample of Example 2, which had asbestos added under similar conditions, and losses also occurred, proving that these may have been carried away by the oxygen gas during the process of sending the sample into the combustion tube.

[0082] Although the preferred embodiments of the present invention have been described in detail above, the present application is not limited thereto. Within the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, including combining each technical feature in any other suitable manner, and these simple modifications and combinations are also regarded as the contents disclosed in the present invention, and all of them should fall within the protection scope of the present invention.

Claims

1. A method for simultaneously and rapidly measuring chlorine, bromine and iodine using high-temperature hydrolysis and ICP-MS, A step (1) of placing an object to be measured in a sample container, uniformly spreading fibrous asbestos on the surface of the object to be measured to form a layer to hold the object to be measured, and then performing a high-temperature hydrolysis treatment, The process of high-temperature hydrolysis treatment includes step (1) of selectively preheating at 500-600°C for 3-10 min, further heating at 700-800°C for 3-10 min to burn organic matter in the test object, and then burning at 1000-1100°C for 10-30 min; (2) preparing a series of concentration calibration curve solutions and internal standard solutions, and testing their net intensities respectively by connecting an online internal standard method using an ICP-MS instrument to obtain calibration curves of concentration values ​​and net intensity values ​​corresponding to each element; The method includes the step (3) of using ICP-MS equipment to test the net strength of the solution (hereinafter referred to as "measurement absorption solution") obtained after the high-temperature hydrolysis treatment of step (1) in which the hydrohalic acid derived from the measurement object is dissolved in the absorption solution, and then connecting the calibration curve to obtain the concentration of chlorine, bromine and iodine in the measurement absorption solution, and further obtaining the content of chlorine, bromine and iodine in the measurement object.

2. The method according to claim 1, further comprising, prior to step (1), a pretreatment step of heating the sample container and the asbestos laid on the surface of the object to be measured in the sample container at a high temperature, thereby removing halogen-based impurities on the sample container and the asbestos.

3. The method according to claim 2, wherein the process of high temperature hydrolysis pretreatment includes firing at 1000-1100°C for 5-10 min.

4. The conditions for the high-temperature hydrolysis treatment or the high-temperature hydrolysis pretreatment are as follows: The method according to any one of claims 1 to 3, characterized in that the oxygen gas flow rate of the inner tube of the combustion tube is 50-100 mL / min, the oxygen gas flow rate of the outer tube of the combustion tube is 50-200 mL / min, the oxygen gas flow rate for generating water vapor during sample decomposition and blowing it into the object to be measured (hereinafter referred to as "oxygen gas flow rate for blowing") is 50-200 mL / min, the final constant volume is 10-50 mL, and the method includes containing 3-10 mL of absorption liquid, 4-30 mL of decomposition water, and 3-10 mL of cleaning liquid.

5. The method according to claim 4, wherein the absorption liquid and the washing liquid are both ammonia water with a mass concentration of 0.1-1%, and / or the decomposition water is primary laboratory water.

6. The workstation tuning parameters of the ICP-MS instrument in steps (2) and (3) (sensitivity using standard elements Re, In, U, Ce and index values ​​of CeO / Ce, Ce++ / Ce) are: Re>2000, In>40000, U>30000, CeO / Ce≦0.025, 2. The method of claim 1, wherein Ce++ / Ce is set to 0.

04.

7. The experimental parameters of the ICP-MS instrument in steps (2) and (3) include: Device mode: Standard mode, Radio frequency power: 1500W, Plasma gas flow rate: 18 L / min, Auxiliary gas flow rate: 1.2 L / min, Atomizer gas flow rate: 0.96 L / min, Number of test points: 3, Sampling cone: platinum cone, Detection method: Peak jump, Internal standard: rhodium, Internal standard addition method: Online addition of internal standard solution; 7. The method according to claim 1 or 6, characterized in that the spray chamber rubber ring is fluororubber.

8. The specific process of step (2) is as follows: A step (201) of preparing a series of calibration curve solutions containing chlorine, bromine, and iodine by taking a single element standard solution of chlorine, bromine, and iodine, respectively; Taking an internal standard element standard solution and preparing an internal standard solution (202); The method according to claim 1, further comprising the step (203) of injecting the calibration curve solutions of the series of concentrations into an ICP-MS instrument, and measuring the contents of chlorine, bromine and iodine by an online internal standard method using the internal standard solutions to obtain calibration curves of concentration values ​​and net intensity values ​​corresponding to each element.

9. The method according to claim 1 or 8, characterized in that the internal standard element in the internal standard solution is rhodium, and / or the concentration of the internal standard element in the internal standard solution is 30-80 μg / L.

10. 9. The method of claim 1 or 8, wherein the concentration of chlorine in the calibration curve solution is 500 μg / L-3000 μg / L, the concentration of bromine is 0.5 μg / L-100 μg / L, and the concentration of iodine is 0.1 μg / L-100 μg / L.

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