CN105842044A - Method for determining content of elemental mercury in metavanadate, and preparation method for sample solution - Google Patents

Abstract

The invention relates to a method for measuring mercury element content in metavanadate and a sample solution preparation method, belonging to the technical field of element detection. The technical problem solved by the invention is to provide a sample solution preparation method for measuring the content of mercury in metavanadate. The method consists of the following steps in sequence: dissolving the metavanadate sample in water; adding nitric acid and hydrogen peroxide, heating to 60-65°C for digestion; after digestion, cooling to room temperature, and diluting to volume with water, namely Obtain a sample detection solution. The present invention researches and establishes ICP-MS to measure the trace impurity element mercury in the content range of 0.0001-0.1000% in metavanadate, the performance index reaches the quantitative detection lower limit of 0.0001%, the precision is less than 10%, and the recovery rate is 80-120%. The method of the invention has the characteristics of simple and fast operation, short analysis time, less reagent consumption, lower blank, less influencing factors, low detection limit, high precision and accuracy, and the like.

Description

Method for determining mercury element content in metavanadate and sample solution preparation method

technical field

The invention relates to a method for measuring mercury element content in metavanadate and a sample solution preparation method, belonging to the technical field of element detection.

Background technique

Ammonium metavanadate, potassium metavanadate, sodium metavanadate and other metavanadate products with alkali metals, alkaline earth metals or ammonium ions as cationic components are not only intermediate products in the vanadium extraction process, but also mainly used in It is used to prepare vanadium pentoxide or metal vanadium, and then produce vanadium-iron, vanadium-aluminum, vanadium-titanium-aluminum, vanadium-nitrogen and other vanadium-based alloy materials; at the same time, metavanadate is also a chemical reagent, catalyst, and drier , mordant and ceramic industry glaze and other widely used vanadium fine chemicals. Since the content of impurity elements not only affects the grade of the product, but also seriously affects the activity, life and use of the product, especially with the continuous expansion of the application field of metavanadate, many emerging uses of metavanadate gradually increase the traces in the product. The quality inspection requirements for the amount of impurity element mercury.

At present, the detection methods and technical methods for determining the content of mercury in samples mainly include the following: hydride generation atomic fluorescence spectrometry (HG-AFS), graphite furnace atomic absorption spectrometry (GF-AAS), cold mercury vapor atomic absorption Spectrometry (HG-AAS), Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-OES), Inductively Coupled Plasma Mass Spectrometry (ICP-MS), etc. The key technical difficulty of its mercury measurement analysis method is that it is specific to the detection objects of various types of samples, and it is necessary to solve the following three technical problems: ①Sample digestion preparation technology: it is necessary to target the matrix components in the sample and the impurities to be measured. Chemical reaction characteristics, develop appropriate sample digestion preparation methods, especially the type, composition, proportion, dosage and reaction temperature of the chemical reagents used in the digestion, so as to ensure that the sample matrix and the element mercury to be measured can be quickly and completely digested into the solution, while avoiding the volatilization loss of mercury elements with volatile characteristics, which will affect the accuracy of the measurement results; ② Eliminate the influence of the matrix effect caused by the sample matrix and coexisting components on the measurement; ③ Avoid salts caused by digestion reagents Concentration, acidity and other matrix effects, mass spectrometry interference, etc. affect the determination.

At present, there is no literature report on the detection and analysis method of trace mercury in metavanadate such as ammonium metavanadate, potassium ^metavanadate and sodium metavanadate by ICP-MS.

Contents of the invention

According to the chemical properties of metavanadate such as ammonium metavanadate, potassium metavanadate and sodium metavanadate, the present invention develops a matching sample detection solution preparation method and detection method, which simply and effectively solve the above three aspects technical problems.

The first technical problem solved by the invention is to provide a method for preparing a sample solution for measuring the content of mercury in metavanadate.

The present invention measures the sample solution preparation method of mercury element content in the metavanadate, and its steps are as follows:

a, the metavanadate sample is dissolved in water;

b. Add nitric acid and hydrogen peroxide, heat to 60-65°C, and carry out digestion to completely digest the sample and coexisting impurities;

c. After digestion, cool to room temperature and dilute with water to obtain the sample solution.

Preferably, the volume ratio of water, nitric acid and hydrogen peroxide is 1.5-2.5:1:0.8-1.2, preferably the volume ratio of water, nitric acid and hydrogen peroxide is 2:1:1.

Preferably, the mass percentage concentration of the nitric acid is 65%-68%, and the mass percentage concentration of the hydrogen peroxide is ≥30%.

Preferably, the reagent dosage is added according to the ratio of sample mass: nitric acid volume of 0.1-0.2g: 3-6ml.

Further, the digestion time of step b is 2-3 minutes.

Preferably, 0.10-0.20 g of the metavanadate sample is diluted with water and fixed in a 50-100 mL volumetric flask.

Further, the metavanadate is preferably a metavanadate with an alkali metal, alkaline earth metal or ammonium ion as a cation, preferably ammonium metavanadate, sodium metavanadate or potassium metavanadate.

In the metavanadate, the mercury content is preferably 0.0001-0.1000%.

The method for preparing the sample solution for measuring the mercury element content in metavanadate of the present invention uses ammonium metavanadate, sodium metavanadate, potassium metavanadate, etc., which use alkali metals, alkaline earth metals, or ammonium ions as cationic components. The matrix composition of vanadate samples is easy to dissolve in water. First, the sample matrix and water-soluble impurities in the sample are directly dissolved with water at room temperature, thereby shortening the reaction time in the heating stage and reducing the time required for sample solution preparation. The risk of volatile mercury elements being heated and evaporated during the process; then according to the volume ratio of water, concentrated nitric acid and hydrogen peroxide is 2:1:1, and the relationship between 3 mL of nitric acid and hydrogen peroxide is required for every 0.1 gram of sample , add concentrated nitric acid and hydrogen peroxide, which have both the dual functions of sample digestion reagent and mercury oxidation medium protection agent, and heat the metavanadate solution to 60-65°C and keep it in this temperature range for 2-3min. This technical step effectively ensures that the water-insoluble impurities in the sample are quickly and completely digested under the temperature condition of 60-65°C and under the action of nitric acid. At the same time, controlling the reaction temperature and time range is also to avoid volatile mercury elements. Evaporation by heating affects the accuracy of the test results; especially, the strong oxidizing nitric acid, the hydrogen peroxide reagent itself, and the active oxygen generated by the reaction of nitric acid and hydrogen peroxide all effectively ensure that the sample solution is in a strong oxidizing medium. Further ensure that the mercury element digested into the sample solution can maintain the ion form and be stable in the solution, avoiding the reduction of mercury ions to volatile atomic mercury to form mercury vapor that volatilizes from the solution and affects the detection Result accuracy.

The second technical problem solved by the present invention is to provide a method for measuring the content of mercury in metavanadate.

The method for determining the content of mercury element in metavanadate in the present invention adopts ICP-MS as the detection means, and through the connection mode of the online internal standard mixer, the sample solution and the series of calibration curve mercury are mixed by the peristaltic pump of the ICP-MS instrument The standard solution is mixed with the rhodium element standard solution with a concentration of 1-5ng/mL according to the volume ratio of 1:1, and then imported into the ICP-MS instrument for measurement by internal standard calibration, a calibration curve is drawn, and the sample is calculated from the calibration curve. Mercury content in the solution; Wherein, the sample solution is the sample solution prepared by the preparation method of the present invention, and the mercury standard solution of the series calibration curve is respectively 0, 1, 2, 5, 10, 20, 50, 100ng/mL, and the content of nitric acid and hydrogen peroxide is the same as that of the sample solution.

Preferably, the instrument detection parameter of ICP-MS mainly comprises: analysis isotope is ^201.971 Hg (29.86%), ^199.968 Hg (23.10%), ^198.968 Hg (16.87%); Radio frequency transmission power 1000W, cooling gas velocity (Ar) 15L/ min, auxiliary gas flow rate (Ar) 1L/min, nebulizing gas flow rate 0.76L/min, test solution lifting volume 0.98mL/min; resolution 0.7amu, measuring point/peak 25, scan times 3, dwell time For 100ms, double detector voltage (pulse 900V, analog -1850V). Avoid the formation of acid ions or molecules produced by the dissociation of digestion reagents, vanadium or vanadate anions and potassium sodium or ammonium cations in metavanadate, and ionized gas components in ICP such as argon, oxygen, and hydrogen. Mass spectrometry interference caused by polyatomic ions or molecular ions improves the precision and accuracy of detection results.

Moreover, after the 0.10～0.20g sample of the invention is digested, it is diluted with water and fixed at 50～100mL, which is the direct dilution of the first step carried out according to a specific proportional relationship; The rhodium (Rh) standard solution of 5ng/mL is mixed according to the proportional relationship of (1+1), which is the indirect dilution of the second step carried out according to a specific proportional relationship; through the dilution of two steps, the metavanadic acid is effectively reduced The effect of salt matrix effect on the determination of trace and trace impurity element mercury; at the same time, the actual concentration of nitric acid, which has been optimized and its dosage is already small, is less than 3% after two dilutions, which further reduces its blank background and The effect of acidity on the determination.

The technical features of the present invention are as follows: 1. With specific composition, concentration, ratio, and dosage of strong oxidizing reagents, the rapid digestion reaction is carried out under specific temperature conditions, ensuring that the sample matrix of metavanadate and coexisting elements such as mercury are homogeneous. Rapid reaction dissolves into the solution, and by optimizing and controlling the digestion reagent, reaction medium, temperature and time, etc., the volatile mercury element is avoided from volatilizing and escaping from the solution, resulting in low measurement results and misjudgment of product quality; ②Test optimization The key parameters such as sample quality and dilution ratio in the sample preparation method are determined, and in order to seek the best balance between reducing the concentration of the matrix and salt in the test solution and increasing the concentration of the element to be measured for the contradictory requirements in the determination of trace elements, And combined with the online internal standard calibration method, through the calibration of the internal standard elements and the dilution of the internal standard solution to the test solution, the influence of the matrix effect and background interference caused by the metavanadate matrix and coexisting components on the measurement is eliminated;③ Through the optimization of the sample dilution ratio, digestion reagent and its dosage, not only the influence of the salinity and acidity of the test solution on the measurement is reduced, but also the acid ion or molecule produced by the dissociation of the digestion reagent and the vanadium in the metavanadate are avoided. Or vanadate anions and potassium sodium or ammonium cations, and ionized gas components in ICP such as argon, oxygen, hydrogen, etc. combine with each other to form polyatomic ions or molecular ions.

The present invention researches and establishes ICP-MS to measure trace impurity element mercury in the content range of 0.0001-0.1000% in metavanadate, the performance index reaches the quantitative detection lower limit of 0.0001%, the precision is less than 10%, and the recovery rate is 80-120%. The method of the invention has the characteristics of simple and fast operation, short analysis time, less reagent consumption, lower blank, less influencing factors, low detection limit, high precision and accuracy, and the like.

detailed description

The present invention measures the sample solution preparation method of mercury element content in the metavanadate, and its steps are as follows:

a, the metavanadate sample is dissolved in water;

b. Add nitric acid and hydrogen peroxide, heat to 60-65°C, and carry out digestion to completely digest the sample and coexisting impurities;

c. After digestion, cool to room temperature and dilute with water to obtain the sample solution.

In the invention, the metavanadate is firstly dissolved in an appropriate amount of water under greenhouse conditions, then concentrated nitric acid and concentrated hydrogen peroxide are added, and then heated to a temperature range of 60-65 DEG C for reaction. The volume ratio of water, nitric acid and hydrogen peroxide is 1.5-2.5:1:0.8-1.2, preferably the volume ratio of water, nitric acid and hydrogen peroxide is 2:1:1. The nitric acid and hydrogen peroxide used in the present invention are preferably the most concentrated reagents sold in the market without dilution. Preferably, the mass percentage concentration of the nitric acid is 65%-68%, and the mass percentage concentration of the hydrogen peroxide is ≥30%.

The amount of reagent is added according to the ratio of sample mass: nitric acid volume: 0.1-0.2g: 3-6mL.

Further, the digestion time of step b is 2-3 minutes.

In the present invention, the metavanadate can be placed in a small-mouthed container such as an Erlenmeyer flask, water can be added to the container to wash the wall of the bottle, the sample can be dispersed, and the sample can be dissolved rapidly by shaking or vibrating at room temperature.

In the present invention, the metavanadate solution can be heated to 60-65° C. by means of direct heating on a low-temperature electric heating plate or indirect heating in a hot water bath, and kept within the temperature range for 2-3 minutes.

Further, the metavanadate is metavanadate with alkali metal, alkaline earth metal or ammonium ion as cation, preferably ammonium metavanadate, sodium metavanadate or potassium metavanadate. In the metavanadate, the mercury content is 0.0001-0.1000%.

Dilute 0.10-0.20g metavanadate sample with water to a volume of 50-100mL volumetric flask.

Specifically, the present invention can adopt the following steps: usually, weigh 0.10-0.20 g of the sample into a small-mouthed container such as an Erlenmeyer flask, add 6-12 mL of water to rinse the wall of the bottle, disperse the sample, and accelerate the sample by shaking or oscillating at room temperature. Dissolve the sample; then add 3 to 6 mL of nitric acid and 3 to 6 mL of hydrogen peroxide to the metavanadate solution, and heat the metavanadate solution to 60-65°C, and keep in this temperature range for 2-3 minutes. After the digestion test solution is cooled to room temperature, dilute it with water to a constant volume in a 50-100mL volumetric flask and mix well.

The method for preparing the sample solution for measuring the mercury element content in metavanadate of the present invention uses ammonium metavanadate, sodium metavanadate, potassium metavanadate, etc., which use alkali metals, alkaline earth metals, or ammonium ions as cationic components. The matrix composition of vanadate samples is easy to dissolve in water. First, the sample matrix and water-soluble impurities in the sample are directly dissolved with water at room temperature, thereby shortening the reaction time in the heating stage and reducing the time required for sample solution preparation. The risk of volatile mercury elements being heated and evaporated during the process; then according to the volume ratio of water, concentrated nitric acid and hydrogen peroxide is 2:1:1, and the relationship between 3 mL of nitric acid and hydrogen peroxide is required for every 0.1 gram of sample , add concentrated nitric acid and hydrogen peroxide, which have both the dual functions of sample digestion reagent and mercury oxidation medium protection agent, and heat the metavanadate solution to 60-65°C and keep it in this temperature range for 2-3min. This technical step effectively ensures that the water-insoluble impurities in the sample are quickly and completely digested under the temperature condition of 60-65°C and under the action of nitric acid. At the same time, controlling the reaction temperature and time range is also to avoid volatile mercury elements. Evaporation by heating affects the accuracy of the test results; especially, the strong oxidizing nitric acid, the hydrogen peroxide reagent itself, and the active oxygen generated by the reaction of nitric acid and hydrogen peroxide all effectively ensure that the sample solution is in a strong oxidizing medium. Further ensure that the mercury element digested into the sample solution can maintain the ion form and be stable in the solution, avoiding the reduction of mercury ions to volatile atomic mercury to form mercury vapor that volatilizes from the solution and affects the detection Result accuracy.

The method for determining the content of mercury in metavanadate in the present invention adopts inductively coupled plasma mass spectrometry (ICP-MS) as a detection means, and through the connection mode of an online internal standard mixer, the peristaltic pump of the ICP-MS instrument Mix and dilute the sample solution, the serial calibration curve mercury standard solution and the rhodium element (Rh) standard solution with a concentration of 1-5 ng/mL according to the ratio of (1+1), and then introduce it into the ICP-MS instrument for internal standard calibration Measure in a manner, draw a calibration curve, and calculate the mercury content in the sample solution by the calibration curve; wherein, the sample solution is the sample solution prepared by the preparation method of the present invention, and the series of calibration curve mercury standard solutions It consists of pure mercury solutions with concentrations of 0, 1, 2, 5, 10, 20, 50, and 100ng/mL, and the contents of nitric acid and hydrogen peroxide are consistent with the sample solution.

The present invention selects the inductively coupled plasma mass spectrometry (ICP-MS) as the instrument detection means and the internal standard method using rhodium Rh as the internal standard correction element to measure the content of trace and trace mercury elements in the sample solution. In particular, the online internal standard mixer is used to connect the sample solution prepared by digestion and the serial calibration curve mercury (Hg) standard solution with a concentration of 1-5 ng/mL through the peristaltic pump in the ICP-MS sampling system. The rhodium element (Rh) standard solution is mixed and diluted according to the ratio of (1+1), and then introduced into the ICP-MS instrument to determine the content of mercury in various solutions by means of internal standard calibration.

The instrument detection parameters of ICP-MS mainly include: the analytical isotopes are ^201.971 Hg (29.86%), ^199.968 Hg (23.10%), and ^198.968 Hg (16.87%); The gas flow rate (Ar) is 1L/min, the atomizing gas flow rate is 0.76L/min, the lifting volume of the test solution is 0.98mL/min; the resolution is 0.7amu, the measurement point/peak is 25, the number of scans is 3, and the dwell time is 100ms. Dual detector voltage (pulse 900V, analog -1850V). Avoid the formation of acid ions or molecules produced by the dissociation of digestion reagents, vanadium or vanadate anions and potassium sodium or ammonium cations in metavanadate, and ionized gas components in ICP such as argon, oxygen, and hydrogen. Mass spectrometry interference caused by polyatomic ions or molecular ions improves the precision and accuracy of detection results.

Moreover, after the 0.10～0.20g sample of the invention is digested, it is diluted with water and fixed at 50～100mL, which is the direct dilution of the first step carried out according to a specific proportional relationship; The rhodium (Rh) standard solution of 5ng/mL is mixed according to the proportional relationship of (1+1), which is the indirect dilution of the second step carried out according to a specific proportional relationship; through the dilution of two steps, the metavanadic acid is effectively reduced The effect of salt matrix effect on the determination of trace and trace impurity element mercury; at the same time, the actual concentration of nitric acid, which has been optimized and its dosage is already small, is less than 3% after two dilutions, which further reduces its blank background and The effect of acidity on the determination.

The specific implementation of the present invention will be further described below in conjunction with the examples, and the present invention is not limited to the scope of the examples. In the following examples, the concentration of concentrated nitric acid and hydrogen peroxide with a concentration of 65% to 68% and hydrogen peroxide with a concentration of ≥ 30% in the mass percent concentration of the superior pure grade are used, and the water is distilled water meeting the requirements of laboratory secondary water. The equipment is: Elan9000 inductively coupled plasma mass spectrometer (ICP-MS) of American PE company.

Example 1

Digestion of ammonium metavanadate samples

Take by weighing sample 0.2000g ammonium metavanadate sample (hereinafter referred to as No. 1 sample) in Erlenmeyer flask, add 12mL water to rinse bottle wall, disperse sample and accelerate dissolving sample by shaking or vibrating action under room temperature environment; Then in Add 6mL nitric acid and 6mL hydrogen peroxide to the solution, heat the metavanadate solution to 65°C by direct heating on a low-temperature electric heating plate or indirect heating in a hot water bath, and keep at this temperature for 3 minutes. After the digestion test solution is cooled to room temperature, dilute with water to volume and mix in a 100mL volumetric flask.

Determination of Mercury Content in Ammonium Metavanadate Sample Solution by ICP-MS

Inductively coupled plasma mass spectrometry (ICP-MS) was used as the detection method, and through the connection mode of the online internal standard mixer, the sample solution prepared by digestion and the serial calibration curve mercury (Hg) were digested by the peristaltic pump of ICP-MS. The standard solution was mixed and diluted with the rhodium element (Rh) standard solution with a concentration of 5ng/mL according to the ratio of (1+1), and then introduced into the ICP-MS instrument to determine the content of Hg element in the solution by means of internal standard calibration.

Among them, the serial calibration curve mercury standard solutions are composed of pure mercury standard solutions with concentrations of 0, 1, 2, 5, 10, 20, 50, and 100 ng/mL, and the content of nitric acid and hydrogen peroxide is consistent with the sample solution.

The remaining ICP-MS measurement steps are carried out in a conventional manner, and the working parameters of the inductively coupled plasma mass spectrometer are set as follows: radio frequency transmission power 1000W, cooling gas flow rate (Ar) 15L/min, auxiliary gas flow rate (Ar) 1L/min, atomization The gas flow rate is 0.76L/min, the lifting volume of the test solution is 0.98mL/min; the resolution is 0.7amu, the measurement point/peak is 25, the number of scans is 3, the dwell time is 100ms, and the double detector voltage (pulse 900V, analog -1850V ). The analysis isotope can be selected from ^201.971 Hg (29.86%), ^199.968 Hg (23.10%), ^198.968 Hg (16.87%) at the same time or any one of them.

Example 2

The sample to be digested is 0.1000g potassium metavanadate sample (hereinafter referred to as No. 2 sample), the consumption of water is 6mL, the consumption of concentrated nitric acid is 3mL, and the consumption of hydrogen peroxide is 3mL, and the temperature and the time of solution heating reaction are respectively 60°C and 2min, the final dilution constant volume is 50mL, and the concentration of rhodium Rh internal standard calibration standard solution used is 1ng/mL.

Besides, the potassium metavanadate sample was digested in the same manner as in Example 1 and the solution was detected by ICP-MS.

Example 3

The sample to be digested is 0.1500g sodium metavanadate sample (hereinafter referred to as No. 3 sample), the consumption of water is 9mL, the consumption of concentrated nitric acid is 4.5mL, the consumption of hydrogen peroxide is 4.5mL, the temperature and time of solution heating reaction 63° C. and 2.5 minutes respectively, the final dilution constant volume is 100 mL, and the concentration of rhodium Rh internal standard calibration standard solution used is 3 ng/mL.

Besides, the sodium metavanadate sample was digested in the same manner as in Example 1 and the solution was detected by ICP-MS.

Example 4

The sample to be digested is a 0.1000g calcium metavanadate sample (hereinafter referred to as No. 4 sample), the consumption of water is 12mL, the consumption of concentrated nitric acid is 6mL, and the consumption of hydrogen peroxide is 6mL, and the temperature and time of solution heating reaction are respectively 65°C and 3min, the final dilution constant volume is 100mL, and the concentration of rhodium Rh internal standard calibration standard solution used is 4ng/mL.

Besides, the calcium metavanadate sample was digested in the same manner as in Example 1 and the solution was detected by ICP-MS.

Example 5

The sample to be digested is 0.1500g potassium metavanadate sample (hereinafter referred to as No. 5 sample), the consumption of water is 6mL, the concentrated nitric acid consumption is 3mL, and the hydrogen peroxide consumption is 3mL, and the temperature and the time of solution heating reaction are respectively 62°C and 2min, the final diluted constant volume is 50mL, and the concentration of rhodium Rh internal standard calibration standard solution used is 2ng/mL.

Besides, the potassium metavanadate sample was digested in the same manner as in Example 1 and the solution was detected by ICP-MS.

Embodiment 6 recovery evaluation

The present invention has carried out recovery rate test to No. 2 sample and No. 4 sample. At first by embodiment 2 and embodiment 4 measured respectively the content of contained mercury element in No. 2 sample and No. 4 sample; Then respectively add 0.0005% and 0.0001% in No. 2 sample and No. 4 sample Mercury standard solution, the whole process repeats the sample preparation and detection operation of embodiment 2 and embodiment 4 respectively. The evaluation of the recovery rate is used to verify the sample solution preparation method and detection method of the present invention, to solve the volatilization loss of the volatile element mercury in the sample preparation stage and to eliminate the matrix effect, acidity effect, mass spectrum interference, etc. in the mercury element detected by ICP-MS The effectiveness of various influencing factors. The test results are shown in Table 1.

Table 1 Recovery test

It can be seen from Table 1 that the recovery rate of the method for the determination of trace element mercury in metavanadate at a content level of 10 ^-6 is 80% to 120%, indicating that the analysis results have high accuracy and reliability.

Embodiment 7 precision evaluation

The present invention carries out 8 independent sample solution digestion preparations and analysis and determination respectively to embodiment 1 and embodiment 3, the result of 8 measurements is carried out statistical processing, according to the detection precision level that relative standard deviation (RSD) represents, with To assess the consistency of repeated tests of the present invention. The measurement results are shown in Table 2.

Table 2 Analytical method precision (n=8) (%)

It can be seen from Table 2 that the precision RSD of the mercury element content of the 10 ^-5 trace level (on the 10 ^-6 detection lower limit of the present invention, meeting the detection range of the present invention) in the measurement metavanadate is less than 10%, even if the determination is partial The precision RSD of the mercury element content of 10 ^-7 trace level (under the 10 ^-6 detection lower limit of the present invention's setting, beyond the optimum measurement range of the present invention) in the vanadate is also less than 30%, shows that repeatedly measures The results are consistent, the repeatability and reproducibility of the method are good, and the method has a high level of precision.

Claims (10)

1. measure the preparation method of the sample solution of mercury element content in the metavanadate, it is characterized in that, its steps are successively: a, the metavanadate sample is dissolved in water; b. Add nitric acid and hydrogen peroxide, heat to 60-65°C for digestion; c. After digestion, cool to room temperature and dilute with water to obtain the sample solution. 2. the preparation method of the sample solution of mercury element content in the mensuration metavanadate according to claim 1 is characterized in that: the volume ratio of water, nitric acid and hydrogen peroxide is 1.5～2.5:1:0.8～1.2, Preferably, the volume ratio of water, nitric acid and hydrogen peroxide is 2:1:1. 3. according to claim 1 and 2, measure the preparation method of the sample solution of mercury element content in the metavanadate, it is characterized in that: described nitric acid mass percentage concentration is 65%～68%, the mass percentage of hydrogen peroxide Concentration ≥ 30%. 4. according to the preparation method of the sample solution of mercury element content in the measurement described in claim 1～3 any one, it is characterized in that: sample quality: nitric acid volume is 0.1～0.2g:3～6mL. 5. the preparation method of the sample solution of mercury element content in the mensuration metavanadate according to claim 1, is characterized in that: b step digestion time is 2～3min. 6. the preparation method of the sample solution of mercury element content in the mensuration metavanadate according to claim 1 is characterized in that: 0.10～0.20g metavanadate sample is diluted with water and is settled in 50～100mL volumetric flask . 7. according to the preparation method of the sample solution of mercury element content in the measurement described in claim 1～6 any one, it is characterized in that: described metavanadate is with alkali metal, alkaline earth metal or ammonium root The metavanadate as the cation is preferably ammonium metavanadate, sodium metavanadate or potassium metavanadate. 8 . The method for preparing a sample solution for determining mercury element content in metavanadate according to any one of claims 1 to 7 , characterized in that: in the metavanadate, the mercury content is 0.0001 to 0.1000%. 9. measure the method for elemental mercury content in the metavanadate, it is characterized in that: adopt ICP-MS as detection means, and by the connection mode of online type internal standard mixer, by the peristaltic pump of ICP-MS instrument, sample solution, A series of calibration curve mercury standard solutions were mixed with rhodium element standard solutions with a concentration of 1-5ng/mL according to the volume ratio of 1:1, and then imported into the ICP-MS instrument for measurement by means of internal standard calibration, the calibration curve was drawn, and the calibration The curve calculates the mercury content in the sample solution; Wherein, the sample solution is the sample solution prepared by the preparation method described in any one of claims 1 to 8, and the mercury standard solution of the series of calibration curves has a concentration of 0, 1, 2, 5, 10, 20, 50, 100ng/mL, and the composition of mercury solution with the content of nitric acid and hydrogen peroxide consistent with the sample solution. 10. the method for mercury element content in the mensuration metavanadate according to claim 9 is characterized in that: ICP-MS instrument detection parameter mainly comprises: radio frequency transmission power 1000W, cooling gas flow rate 15L/min, auxiliary gas flow rate 1L /min, nebulized gas flow rate 0.76L/min, test solution lifting volume 0.98mL/min; resolution 0.7amu, measurement peak 25, scan times 3, dwell time 100ms, double detector voltage, pulse 900V , simulated at -1850V; the analyzed isotope is: ^201.971 Hg, ^199.968 Hg or ^198.968 Hg.