阅读说明：本技术 一种天然水中硫代钨酸盐的定量测试方法 (Quantitative test method for thiotungstate in natural water ) 是由 郭清海 赵倩 于 2020-12-29 设计创作，主要内容包括：本发明公开了一种天然水中硫代钨酸盐的定量测试方法,步骤为：将采集到的天然水样品快速冷冻保存,备用；将冷冻保存的天然水样品在即将检测前快速解冻,获得天然水溶液；将天然水溶液注入梯度淋洗反相离子对色谱仪中进行钨形态分离,利用联用的电感耦合等离子体质谱仪测定溶液中不同钨形态(包括钨酸盐、一硫代钨酸盐、二硫代钨酸盐、三硫代钨酸盐、四硫代钨酸盐)的含量。本发明提供的测试方法可以有效分离天然水中的钨酸盐和不同类型的硫代钨酸盐并可实现其定量测试,该方法检出限低于常见富硫化物天然水中钨的含量水平,且可屏蔽天然水中存在的其他组分对目标组分检测的干扰,具有快速、有效、高精度等优点。(The invention discloses a quantitative test method of thiotungstate in natural water, which comprises the following steps: rapidly freezing and storing the collected natural water sample for later use; quickly thawing the frozen and stored natural water sample before detection to obtain a natural water solution; injecting the natural water solution into a gradient leaching reversed-phase ion pair chromatograph to separate tungsten forms, and measuring the content of different tungsten forms (comprising tungstate, mono-thiotungstate, dithiotungstate, tri-thiotungstate and tetra-thiotungstate) in the solution by using a coupled inductively coupled plasma mass spectrometer. The test method provided by the invention can effectively separate tungstate and different types of thiotungstate in natural water and realize quantitative test of the tungstate and the thiotungstate, the detection limit of the method is lower than the content level of tungsten in common sulfide-rich natural water, the interference of other components existing in the natural water on the detection of target components can be shielded, and the method has the advantages of rapidness, effectiveness, high precision and the like.)

1. A quantitative test method for thiotungstate in natural water is characterized by comprising the following steps:

s1: rapidly freezing and storing the collected natural water sample for later use;

s2: quickly thawing the frozen and stored natural water sample before detection to obtain a natural water solution;

s3: carrying out tungsten form separation on a natural aqueous solution in a gradient leaching reversed-phase ion pair chromatograph;

s4: and (3) determining the contents of different tungsten forms in the natural water solution by using a coupled inductively coupled plasma mass spectrometer.

2. The method for quantitatively measuring thiotungstate in natural water as set forth in claim 1, wherein in step S1, the natural water sample is stored at a temperature of not more than-20 ℃ from the time of collection.

3. The method for quantitative determination of thiotungstate in natural water, as claimed in claim 1, wherein in step S3, the gradient elution reversed-phase ion-pair chromatograph uses a Dionex ion pac NS1 analytical column and a Dionex ion pac NG1 protective column.

4. The method for quantitatively testing thiotungstate in natural water as set forth in claim 1, wherein in step S3, the gradient elution reversed-phase ion-pair chromatograph uses an elution liquid that is: with Na₂CO₃And (CH)₃CH₂CH₂CH₂)₄The mixed solution of N (OH) is used as a mobile phase A; ethanol is used as a mobile phase B; wherein Na is contained in the mixed solution₂CO₃Is 1mM, (CH)₃CH₂CH₂CH₂)₄The concentration of N (OH) was 2 mM.

5. The method for quantitatively testing thiotungstate in natural water as set forth in claim 4, wherein the ethanol has a concentration gradient of: the concentration of the ethanol is linearly increased from 12 percent to 23.5 percent along with time within 0 to 15 minutes; 15-23 minutes, the concentration of the ethanol is linearly increased to 35 percent from 23.5 percent along with the time; the concentration of the ethanol is linearly reduced from 35 percent to 12 percent along with the time within 23 to 24 minutes; the concentration of the ethanol is kept unchanged for 24-28 minutes.

6. The method for quantitative determination of thiotungstate in natural water, as claimed in claim 1, wherein the quantitative ring used in the gradient elution reversed-phase ion-pair chromatograph has a size of 200 μ L or 500 μ L.

7. The method for quantitatively testing thiotungstate in natural water as set forth in claim 4, wherein the flow rates of the mobile phase A and the mobile phase B of the gradient elution reversed-phase ion-pair chromatograph are 1.0 mL/min.

8. The method for quantitatively testing thiotungstate in natural water as set forth in claim 1, wherein the temperature of the chromatographic column of the gradient elution reversed-phase ion-pair chromatograph is 30 ℃.

9. The quantitative test method of thiotungstate in natural water as set forth in claim 1, wherein the gas conditions of the inductively coupled plasma mass spectrometer are as follows: the flow rate of the atomizer is 0.705L/min, the flow rate of the cooling gas is 14L/min, the flow rate of the auxiliary gas is 0.8L/min, the flow rate of oxygen in CCT mode is 0.438mL/min, and the addition amount of oxygen for removing carbon element in ethanol is 15.09%.

10. The quantitative test method of thiotungstate in natural water as set forth in claim 1, wherein the mass-to-charge ratio of the test ions of the inductively coupled plasma mass spectrometer is 184w.16o and 32 s.16o.

Technical Field

The invention relates to the field of analytical geochemistry, in particular to a quantitative test method for thiotungstate in natural water.

Background

The toxicity and even carcinogenicity of tungsten have attracted considerable attention in recent years from researchers concerned. The natural water is an important environmental medium for the existence of tungsten, so the content range, the morphological distribution and the environmental and health effects of the tungsten in the natural water haveHas important significance. In natural water, tungsten is generally present as an oxygen-containing complex anion (WO)₄ ^2-) Exists in the form of (1); however, in sulfide-rich natural waters, thiotungstates can become a significant and non-negligible presence form of tungsten. However, there is currently a lack of effective quantitative test methods for thiotungstates in natural water; under the influence of the thiotungstate, systematic research aiming at the geochemical behavior, the toxicological effect and the environmental health influence of the thiotungstate in a natural water system is correspondingly lacked.

In prior studies, Mohajerin et al determined the concentration of thiotungstate in the laboratory-formulated solution using ultraviolet-visible absorption spectroscopy (UV-Vis) and thereby determined the chemical equilibrium constant for interconversion between tungstate and the four thiotungstate species in water, and Johannesson et al calculated the thiotungstate content in groundwater in Carrizo aquifers and aquifers of maryland, texas, usa using geochemical simulation. However, in Mohajerin et al, the test object of the UV-Vis method is a laboratory-prepared aqueous solution containing only tungstate and thiotungstate, and the obtained absorbance can be regarded as direct reflection of different concentrations of thiotungstate in water because no other components interfere with the test process; when the method is transplanted to the determination of thiotungstate in natural water, the influence of the interference component will make the test result (i.e. absorbance) meaningless. In addition to uv-vis absorption spectroscopy, X-ray absorption spectroscopy (XAS) has also been used for the identification of thio-compounds in water, including thioarsenate/thioarsenate and thioantimonate, but this method only qualitatively identifies the presence of thio-compounds in different forms in water, and does not yield quantitative results.

So far, an anion exchange chromatography-inductively coupled plasma mass spectrometry (AEC-ICP-MS) is the best choice for quantitatively testing the thio-compounds in the natural water, and has been successfully applied to the determination of the thio-arsenate and the thio-antimonate in the natural water. However, when used for thio compounds formed from metal elements having a large atomic weight (typified by thiotungstate, thiomolybdate, thioperrhenate, and the like), anion exchange chromatography tends to be unfeasible. For example, Weiss et al found that when using anion exchange chromatography to separate different forms of molybdenum in water, the thiomolybdate was retained on the column for too long a time, making quantitative testing based on this separation method virtually infeasible due to too low efficiency. For example, when the anion exchange chromatography (Dionex IonPac AS-16/AG-16 chromatographic column and 100mmol/L KOH eluent are used for isocratic elution) is used for separating the thioperrhenate in water by Vorlicek and the like, although the previous UV-Vis test indicates that the solution to be tested contains high concentrations of the perrhenate, the monothioperrhenate and the tetrathioperrhenate (which are both more than 50 mu mol/L), only the chromatographic peak of the perrhenate appears in the elution process of more than 150 minutes, which shows that the thioperrhenate cannot be separated by the anion exchange chromatographic column in the effective time. The preliminary work of this group indicated that the anion exchange chromatography-inductively coupled plasma mass spectrometry combined system (AEC-ICP-MS) was also not suitable for quantitative testing of thiotungstate.

At present, no description about a quantitative test method of thiotungstate in natural water is found in published documents, and no patent about a quantitative test method of thiotungstate in natural water is found.

Disclosure of Invention

The invention aims to establish a method for quantitatively testing thiotungstate in natural water quickly, effectively and accurately by reversed-phase ion pair chromatography-inductively coupled plasma mass spectrometry (RP-IPC-ICP-MS) aiming at the current situation that a quantitative testing method for thiotungstate in natural water is lacked.

The invention provides a quantitative test method of thiotungstate in natural water, which comprises the following steps:

s1: rapidly freezing and storing the collected natural water sample for later use;

s2: quickly thawing the frozen and preserved natural water sample by using a high-frequency quick thawing device just before testing to obtain a natural water solution;

s3: injecting the natural aqueous solution into a gradient leaching reversed-phase ion pair chromatograph (RP-IPC) to carry out tungsten form separation;

s4: the contents of different tungsten forms (including tungstate, mono-thiotungstate, dithiotungstate, tri-thiotungstate and tetra-thiotungstate) in the natural water solution are measured by using a coupled inductively coupled plasma mass spectrometer.

Further, preserving the collected natural water sample at a temperature not higher than-20 ℃ from collection, and quickly thawing the sample before quantitative testing; after the natural water sample is collected, if the natural water sample is placed under the condition of normal temperature air, the thiotungstate (particularly trithiotungstate) can be subjected to desulfurization reaction and quickly converted into tungstate, so that the sample can be quickly frozen after being collected, and the thio compounds in the natural water sample can be better preserved.

Further, the natural water sample is stored in a frozen manner by using liquid nitrogen or dry ice at a sampling site and during transportation to a laboratory, and is stored in a frozen manner by using a low-temperature refrigerator during a sample to be tested such as a laboratory.

Further, in step S3, the chromatography column of the gradient elution reverse-phase ion-pair chromatograph adopts a Dionex ion pac NS1(10 μm, 250 × 4mm) analytical column and a Dionex ion pac NG1(10 μm, 35 × 4mm) protective column; the NS1 analytical column was a polymeric reverse phase chromatographic column packed with a vinyl ethylbenzene polymer of neutral, macroporous, high surface area, crosslinked 55% divinylbenzene, which made the NS1 analytical column resistant to solvents, acids, and bases, and was well suited for the separation of hydrophobic, ionizable compounds using eluents having a pH of 0 to 14.

Further, in step S3, the eluent added to the gradient elution reversed-phase ion pair chromatograph is: with Na₂CO₃And (CH)₃CH₂CH₂CH₂)₄The mixed solution of N (OH) is used as a mobile phase A, and ethanol is used as a mobile phase B; wherein Na is contained in the mixed solution₂CO₃Is 1mM, (CH)₃CH₂CH₂CH₂)₄The concentration of N (OH) was 2 mM. The elution capacity of ethanol is between that of acetonitrile and isopropanol, and WO can be realized₄ ^2-And WO₃S^2-、WO₂S₂ ^2-、WOS₃ ^2-、WS₄ ^2-The complete baseline separation of the tungsten is not suitable for the tungsten sulfide, and the elution capacity of the organic solvent methanol is weakSeparating acid salt; ion pairing reagent tetrabutylammonium hydroxide (TBA)⁺) Charge of and ion to be detected WO_nS_4-n ^2-(n is 0-4) and the two can form a hydrophobic ion pair compound TBA⁺-WO_nS_4-n ^2-Thereby increasing the sample ion WO_nS_4-n ^2-Solubility in stationary phase, simultaneous ion-pairing of TBA in stationary phase⁺-WO_nS_4-n ^2-Reversible reaction to produce TBA⁺、WO_nS_4-n ^2-，TBA⁺、WO_nS_4-n ^2-Redissolved in a mobile phase, WO_nS_n-4 ^2-Moves forward with the mobile phase; then, WO in the sample_nS_4-n ^2-With TBA in the mobile phase⁺Combining to regenerate TBA⁺-WO_nS_4-n ^2-.., the process is repeated. WO_nS_4-n ^2-Multiple partition occurs in the stationary phase and the mobile phase, the forms of the tungsten thioate are separated due to different partition capacities, the form with weak hydrophobicity is washed out firstly, and the form with strong hydrophobicity can be retained on the chromatographic column for a longer time. The retention time of thio compounds increases with the number of sulfur atoms replaced by oxygen atoms, so that the retention time sequence of tungstate and thiotungstate is WO₄ ^2-<WO₃S^2-<WO₂S₂ ^2-<WOS₃ ^2-<WS₄ ^2-(ii) a WO reduction by addition of sodium carbonate_nS_4-n ^2-And improved peak shape.

Further, the concentration gradient of ethanol in the leacheate was: the volume concentration of the ethanol is linearly increased from 12 percent to 23.5 percent along with time within 0 to 15 minutes; the volume concentration of the ethanol is linearly increased to 35 percent from 23.5 percent along with time within 15 to 23 minutes; the volume concentration of the ethanol is linearly reduced from 35 percent to 12 percent along with the time within 23 to 24 minutes; the volume concentration of the ethanol is kept unchanged for 24-28 minutes. The gradient elution can improve the separation effect between forms difficult to separate and shorten the elution time of the strongly retained formsAnd meanwhile, the detection sensitivity is improved. Gradient elution time t_GThe gradient elution effect is influenced by the concentration change range delta psi of the component of the strong elution solvent, gradient T and other factors, wherein the relation of the three factors is that T is delta psi/T_G. For the detection of thiotungstates, a low strength mobile phase (i.e., low concentration ethanol) and a small gradient (T) gradient were first used₁) Start elution for WO with a smaller retention time₄ ^2-And WO₃S^2-After separation with good separation degree, the elution strength of the mobile phase is gradually increased (namely, the ethanol concentration is increased) and the gradient T is gradually increased₂WO allowing better resolution but stronger retention₂S₂ ^2-、WOS₃ ^2-、WS₄ ^2-Elution was rapid, giving satisfactory analytical results.

Further, the specification of a quantitative ring of the gradient elution reversed-phase ion pair chromatograph is 200 mu L or 500 mu L, and when the content of W is less than or equal to 10 mu mol/L, the quantitative ring with the specification of 200 mu L is used; when the W content is > 10. mu. mol/L, a quantitative loop with a specification of 500. mu.L is used.

Further, the flow rate of the mobile phase A and the mobile phase B of the gradient elution reversed-phase ion-pair chromatograph is 1.0 mL/min.

Further, the temperature of the chromatographic column of the gradient elution reversed-phase ion pair chromatograph was 30 ℃.

Further, an ICP-MS sample injection system comprises a PFA atomizer, a 1.0mm central tube, a Pt sampling cone and a Pt intercepting cone; the realization of the RP-IPC-ICP-MS combination comprises the following steps: connecting the outlet of the chromatographic column with a PFA atomizer, connecting two instruments by a communication cable to establish signal triggering, and continuously acquiring signals by using a tQuant mode of Thermo Scientific Qtegra software.

Further, the gas conditions of ICP-MS are: the flow rate of an atomizer (argon) is 0.705L/min, the flow rate of cooling gas (argon) is 14L/min, the flow rate of auxiliary gas (argon) is 0.8L/min, the flow rate of oxygen in a CCT mode is 0.438mL/min, and the addition amount of oxygen for removing carbon elements in ethanol is 15.09%; after high-concentration ethanol in the mobile phase enters ICP-MS, the flame is green, and the amount of oxygen is most suitable when a proper amount of oxygen is added for combustion to remove carbon elements in the ethanol and make the flame white (the oxygen content is not too high, otherwise flameout can be caused).

Further, the test ion mass-to-charge ratios (m/z) of ICP-MS were 184w.16o and 32 s.16o.

Furthermore, Dionex is selected for the gradient elution reversed-phase ion-pair chromatograph^TMThe ICS-6000 type and the inductively coupled plasma mass spectrometer adopt a Thermo Scientific iCAP RQ type.

The invention firstly determines and optimizes the working conditions of reversed-phase ion-pair chromatography (RP-IPC) for separating various tungsten forms (including tungstate and mono-, di-, tri-and tetrathiotungstate), including chromatographic column model, eluent formula, gradient elution program, quantitative ring size, mobile phase flow rate and column temperature; and then determining and optimizing working conditions for measuring various tungsten form contents separated by RP-ICP (inductively coupled plasma mass spectrometry), including a sample injection system, gas flow and test ions m/z, establishing a method for quantitatively testing thiotungstate in natural water, quantitatively analyzing the contents of thiotungstate in a laboratory preparation solution and a representative natural water sample by taking a tungsten standard solution as an analysis standard and based on an RP-IPC-ICP-MS combined system, and determining the effectiveness and universality of the established method.

The method provided by the invention is based on a reversed-phase ion pair chromatography-inductively coupled plasma mass spectrometry combined system (RP-IPC-ICP-MS), is formed by performing a series of optimization on the operation parameters of the chromatography-mass spectrometry, and can accurately and quantitatively analyze trace thiotungstate and tungstate existing in natural water.

Compared with ultraviolet-visible absorption spectrometry (UV-Vis) which has poor anti-interference component capability and high detection limit and can only be used for quantitative analysis of high-content thiotungstate solution prepared indoors, the method provided by the invention can effectively shield the interference of other components coexisting with tungsten in natural water, and has the detection limit of 0.965 mu g/L, the linear range of 0.001-20 mg/L and the linear correlation coefficient R²The product is 0.999, so the method can be used for simultaneously quantitatively analyzing trace thiotungstate and tungstate in natural water.

Compared with X-ray absorption spectroscopy (XAS) and electrospray ionization mass spectrometry (ESI-HRMS) which can only carry out qualitative analysis on thiotungstate in water, the method provided by the invention realizes breakthrough in the aspect of quantitative analysis of thiotungstate.

Compared with an anion exchange chromatography-inductively coupled plasma mass spectrometry (AEC-ICP-MS) analysis method capable of quantitatively analyzing thio-compounds such as thioarsenate, thioantimonate and the like in natural water, the method provided by the invention solves the key problem that AEC cannot effectively separate thiotungstate in water.

Drawings

FIG. 1 is a schematic flow chart of a quantitative test method of thiotungstate in natural water according to example 1 of the present invention;

FIG. 2 is a chart of the tungsten form chromatogram separation and the quantitative analysis result of the sulfide-rich hot spring sample obtained in example 1 of the present invention;

FIG. 3 is a diagram of the chromatographic separation of tungsten form of a thiotungstate standard solution obtained in example 2 of the present invention and its quantitative analysis results;

fig. 4 is a tungsten form chromatographic separation chart of the tungstate-sulfide mixed solution obtained in example 3 of the present invention and a quantitative analysis result thereof.

Detailed Description

The following are specific examples of the present invention. The technical solutions of the present invention will be further described with reference to the accompanying drawings, but the present invention is not limited to these embodiments.

Example 1:

referring to fig. 1, this example 1 provides a quantitative test method for thiotungstate in natural water, which includes the following steps:

step S1, storing the collected sulfide-rich hot spring sample by using a 5mL freezing storage tube, immediately storing the sulfide-rich hot spring sample by using dry ice, transporting the sulfide-rich hot spring sample back to a laboratory, and freezing and storing the sulfide-rich hot spring sample by using a low-temperature refrigerator in the laboratory at the temperature of-20 ℃ until testing; wherein, the sulfide-rich hot spring sample is collected from the Laver palm geothermal area of Longling county of Yunnan province, and the hot spring site index test result is as follows: pH, 9.38; sulfide, 8.2 mg/L;

step S2, quickly thawing the sulfide-rich hot spring sample stored in a frozen mode immediately before testing to obtain sulfide-rich hot spring sample solution;

step S3, the sulfide-rich hot spring sample is processedInjecting the product solution into Dionex^TMCarrying out tungsten morphological separation in an ICS-6000 gradient elution reversed-phase ion pair chromatograph;

wherein, Dionex^TMThe chromatographic conditions of the ICS-6000 gradient elution reversed-phase ion pair chromatograph are as follows:

a chromatographic column: a Dionex IonPac NS1(10 μm, 250X 4mm) analytical column and a Dionex IonPac NG1(10 μm, 35X 4mm) guard column;

leacheate: mobile phase A: na (Na)₂CO₃And (CH)₃CH₂CH₂CH₂)₄Mixed solution of N (OH) (in the mixed solution, Na)₂CO₃Is 1mM, (CH)₃CH₂CH₂CH₂)₄The concentration of N (OH) was 2 mM); mobile phase B: ethanol; the concentration gradient of ethanol is: the concentration of the ethanol is linearly increased from 12 percent to 23.5 percent along with time within 0 to 15 minutes; 15-23 minutes, the concentration of the ethanol is linearly increased to 35 percent from 23.5 percent along with the time; the concentration of the ethanol is linearly reduced from 35 percent to 12 percent along with the time within 23 to 24 minutes; the concentration of the ethanol is kept unchanged for 24-28 minutes;

and (3) quantitative ring: 500 mu L of the solution;

column temperature: 30 ℃;

flow rate of mobile phase: 1.0 mL/min;

step S4, carrying out quantitative test on tungsten in different forms in the sulfide-rich hot spring sample solution by using a Thermo Scientific iCAP RQ inductively coupled plasma mass spectrometer;

wherein, the sample introduction system of the Thermo Scientific iCAP RQ inductively coupled plasma mass spectrometer comprises a PFA atomizer, a 1.0mm central tube, a Pt sampling cone and a Pt intercepting cone; the gas conditions were: the flow rate of an atomizer (argon) is 0.705L/min, the flow rate of cooling gas (argon) is 14L/min, the flow rate of auxiliary gas (argon) is 0.8L/min, the flow rate of oxygen in a CCT mode is 0.438mL/min, and the addition amount of oxygen for removing carbon elements in ethanol is 15.09%; the test ion mass-to-charge ratios (m/z) were 184w.16o and 32 s.16o.

The obtained chromatogram of tungsten morphology and the quantitative analysis result are shown in figure 2.

As can be seen from FIG. 2, the chromatogram was separated at 140 seconds, 320 seconds, 620 seconds, and 70 secondsThe chromatographic peaks of S (-II) appear at 5 seconds, 860 seconds, 1130 seconds, 1395 seconds and 1580 seconds, the chromatographic peaks of W (VI) appear at 680 seconds, 860 seconds, 1130 seconds, 1395 seconds and 1580 seconds, the peak shapes are sharp, and the baseline separation is completely realized. According to 100 mu mol/L sodium tungstate standard solution (WO)₄ ^2-) The chromatographic peak 0 in the chromatogram separation chart is judged to be tungstate, and chromatographic peaks 1, 2, 3 and 4 are respectively mono-thiotungstate, dithiotungstate, trithiotungstate and tetrathiotungstate. The quantitative test results of the contents of tungstate, monothiotungstate, dithiotungstate, trithiotungstate and tetrathiotungstate in the sulfide-rich hot spring sample are 59.6 mu g/L, 13.1 mu g/L, 26.9 mu g/L, 143.1 mu g/L and 11.5 mu g/L respectively.

Example 2:

example 2 the morphological distribution of tungsten in a thiotungstate standard solution was determined according to the following procedure:

preparing 100 mu mol/L of thiotungstate standard solution: 1mmol of ammonium tetrathiotungstate standard solid ((NH) was weighed₄)₂WS₄) Dissolving in ultrapure water, and using a volumetric flask to perform constant volume on the solution to 1000mL to form 1mmol/L ammonium tetrathiotungstate solution; measuring 10mL of 1mmol/L ammonium tetrathiotungstate solution, diluting by 10 times with ultrapure water to form 100 mu mol/L ammonium tetrathiotungstate solution to be detected, and then transferring the solution into an anaerobic bottle to be detected; all the operations are finished in the glove box; the ultrapure water used for preparing the solution in the experimental process is ultrapure water (18.25m omega/cm) which is deoxidized for more than 1 hour by high-purity nitrogen (the purity is more than or equal to 99.999%).

The morphological distribution of tungsten was measured according to the method of steps S3 to S4 in example 1, and a tungsten morphological chromatogram of a thiotungstate standard solution and the quantitative analysis result thereof were obtained, as shown in FIG. 3. In example 2, a quantification loop with a size of 200. mu.L was used.

As can be seen from FIG. 3, in the chromatogram, S (-II) peaks appeared at 330 seconds, 640 seconds, 790 seconds, 1045 seconds, 1335 seconds and 1545 seconds, and W (VI) peaks appeared at 620 seconds, 790 seconds, 1045 seconds, 1335 seconds and 1545 seconds, with sharp peak shapes, and baseline separation was completely achieved. According to 100 mu mol/L sodium tungstate standard solution (WO)₄ ^2-) The chromatographic peak 0 in the chromatogram separation chart is judged to be tungstate, and chromatographic peaks 1, 2, 3 and 4 are respectively mono-thiotungstate, dithiotungstate, trithiotungstate and tetrathiotungstate. Quantitative test results of the contents of tungstate, mono-thiotungstate, dithiotungstate, trithiotungstate and tetrathiotungstate in the thiotungstate standard solution are respectively 20.5 mu mol/L, 7.0 mu mol/L, 46.9 mu mol/L, 3.0 mu mol/L and 22.6 mu mol/L.

Example 3:

example 3 the morphological distribution of tungsten in a tungstate-sulfide mixed solution was determined by the following procedure:

preparing a tungstate-sulfide mixed solution in a laboratory: 1mmol of sodium tungstate dihydrate solid (Na) is weighed₂WO₄·2H₂O) and 40mmol sodium sulfide nonahydrate solid (Na)₂S·9H₂O) and dissolving in ultrapure water, and using a volumetric flask to fix the volume of the solution to 1000mL to form tungstate-sulfide mixed solution (the tungsten content of the mixed solution is 1 mmol/L); measuring 10mL of tungstate-sulfide mixed solution, diluting the tungstate-sulfide mixed solution by 10 times with ultrapure water to form tungstate-sulfide mixed solution to be tested (the tungsten content of the tungstate-sulfide mixed solution is 100 mu mol/L), adjusting the pH value to be 5 with HCl, transferring the tungstate-sulfide mixed solution into an anaerobic bottle, sealing the anaerobic bottle, and storing the tungstate-sulfide mixed solution for 45 days to be tested to obtain the tungstate-sulfide mixed solution containing WO simultaneously₄ ^2-、WO₃S^2-、WO₂S₂ ^2-、WOS₃ ^2-、WS₄ ^2-Solutions of five tungsten forms; all the operations are finished in the glove box; to avoid Na₂S·9H₂In O, S (II) oxidation and the morphological conversion from thiotungstate in a tungsten solution to tungstate, and in the experimental process, ultrapure water (18.25m omega/cm) which is deoxidized for more than 1 hour by high-purity nitrogen (the purity is more than or equal to 99.999%) is used for preparing all solutions.

The morphological distribution of tungsten was measured according to the method of steps S3 to S4 in example 1, and a tungsten morphological chromatographic separation chart of the tungstate-sulfide mixed solution and the quantitative analysis result thereof were obtained, as shown in FIG. 4. A quantification loop of 200. mu.L size was used in example 3.

As can be seen from fig. 4, in the chromatogram, peaks of S (-II) appeared at 360 seconds, 640 seconds, 790 seconds, 1045 seconds, 1335 seconds, and 1545 seconds, and peaks of w (vi) appeared at 620 seconds, 790 seconds, 1045 seconds, 1335 seconds, and 1545 seconds, with sharp peaks, and baseline separation was completely achieved. According to 100 mu mol/L sodium tungstate standard solution (WO)₄ ^2-) The chromatographic peak 0 in the chromatogram separation chart is judged to be tungstate, and chromatographic peaks 1, 2, 3 and 4 are respectively mono-thiotungstate, dithiotungstate, trithiotungstate and tetrathiotungstate. The quantitative test results of the contents of tungstate, mono-thiotungstate, dithiotungstate, trithiotungstate and tetrathiotungstate in the tungstate-sulfide mixed solution are respectively 15.4 mu mol/L, 35.8 mu mol/L, 28.3 mu mol/L, 18.2 mu mol/L and 2.3 mu mol/L.

The above is not relevant and is applicable to the prior art.

While certain specific embodiments of the present invention have been described in detail by way of illustration, it will be understood by those skilled in the art that the foregoing is illustrative only and is not limiting of the scope of the invention, as various modifications or additions may be made to the specific embodiments described and substituted in a similar manner by those skilled in the art without departing from the scope of the invention as defined in the appending claims. It should be understood by those skilled in the art that any modifications, equivalents, improvements and the like made to the above embodiments in accordance with the technical spirit of the present invention are included in the scope of the present invention.