Method for simultaneously determining seven anions in ammonium molybdate based on ion chromatography

Abstract

The invention belongs to an ammonium molybdate detection technology in the field of hydrometallurgy, and particularly relates to a method for simultaneously determining seven anions in ammonium molybdate based on an ion chromatography, the seven anions are F <->, Cl <->, NO2 <->, Br <->, NO3 <->, PO4 < 3-> and SO4 < 2->, and the method comprises the following steps: preparing a mixed standard stock solution of the seven anions, and determining the content of the seven anions in the mixed standard stock solution by adopting the ion chromatography; obtaining retention time-conductance chromatograms of a series of standard solutions of seven anions, and drawing a standard working curve according to the relationship between the anion concentration and the peak area in the mixed standard stock solution; the method comprises the following steps: pretreating an ammonium molybdate sample, and filtering to obtain a treated ammonium molybdate sample; and obtaining a retention time-conductance chromatogram of the ammonium molybdate sample solution by using ion chromatography, and comparing the retention time-conductance chromatogram with the standard working curve to obtain the concentration of each anion in the ammonium molybdate sample. The method can be used for simultaneously determining multiple components, and is simple in pretreatment, high in detection speed, good in stability, good in precision, high in accuracy, high in sensitivity, free of secondary pollution and wide in application range.

Description

Technical Field

[0001] The invention belongs to the ammonium molybdate detection technology in the field of hydrometallurgy, and specifically relates to a method for simultaneously determining seven anions in ammonium molybdate based on ion chromatography. Background Art

[0002] Molybdenum products are one of the important raw materials for the development of modern high-tech. Due to their unique physical and chemical properties, they are widely used in electronics, chemical industry, high temperature and other emerging high-tech fields such as nuclear energy, military materials, photovoltaics, aerospace, and sensors. High-purity molybdenum and its compounds are increasingly used in field emission displays and sensors, plasma displays, and thin-film semiconductor liquid crystal displays. However, the performance of electronic components is reduced due to the influence of impurity ions. Ammonium molybdate is an important intermediate product for the deep processing of molybdenum. It is crucial to strictly control these impurity elements and minimize their content in molybdenum-based products. In addition, in recent years, other fields have also put forward higher requirements on the impurity content of molybdenum-based products.

[0003] At present, the traditional methods for determining miscellaneous anions in ammonium molybdate are mainly spectrophotometry, electrode method, gravimetric method, potentiometric titration and gas phase molecular absorption spectroscopy. Fluoride ions use ion selective electrode method, which is sensitive to electrode contamination and has low measurement accuracy. The processing process of spectrophotometry, gravimetric method and potentiometric titration is complicated, time-consuming, and susceptible to interference, requiring highly skilled personnel to operate. At the same time, these methods consume a large amount of drugs and reagents, and are prone to secondary pollution to the environment.

[0004] Therefore, it is necessary to establish and promote an effective and environmentally friendly method for detecting ammonium molybdate anions. Summary of the invention

[0005] The object of the present invention is to provide a method for simultaneously determining seven anions in ammonium molybdate based on ion chromatography, which can simultaneously determine multiple components, has simple pretreatment, fast detection speed, good stability, good precision, high accuracy, high sensitivity, no secondary pollution, and a wide range of applications.

[0006] The technical solution to achieve the purpose of the present invention is:

[0007] A method for simultaneously determining 7 anions in ammonium molybdate based on ion chromatography, wherein the 7 anions are F - , Cl - 、NO2 - Br - 、NO3 - PO4 3- 、SO4 2- , the method comprising:

[0008] Step (1) preparing 7 kinds of anion mixed standard stock solutions, using ion chromatography to obtain retention time-conductivity chromatograms of a series of standard solutions of the 7 kinds of anions, and drawing a standard working curve based on the relationship between the anion concentration and the peak area in the mixed standard stock solution;

[0009] Step (2) pre-treating and filtering the ammonium molybdate sample before sampling to remove heavy metal ions, uranium and organic compounds in the ammonium molybdate sample to obtain a treated ammonium molybdate sample;

[0010] Step (3) uses ion chromatography to measure the treated ammonium molybdate sample, detects the retention time-conductivity chromatogram of the ammonium molybdate sample solution, and compares it with the concentration-peak area standard working curve of 7 anion contents to obtain the concentration of each anion in the ammonium molybdate sample.

[0011] The concentrations of the seven anion mixed standard stock solutions prepared in step (1) are 0.01 μg / mL, 0.05 μg / mL, 0.10 μg / mL, 0.20 μg / mL, and 0.50 μg / mL, respectively.

[0012] The ammonium molybdate sample is pretreated in step (2) by dissolving the ammonium molybdate sample in a NaOH solution, shaking and ultrasonicating until the sample is completely dissolved into a colorless and transparent state, thereby obtaining a pretreated ammonium molybdate sample solution.

[0013] The concentration of the NaOH solution in step (2) is 20-25 mmol / L, and the ultrasonic temperature is 45-50°C.

[0014] The ammonium molybdate sample is treated in step (2) by activating the RP column and the H column with deionized water, filtering the pretreated ammonium molybdate sample solution once with the RP column and the H column, and then filtering it twice with a syringe filter to obtain the treated ammonium molybdate sample.

[0015] In the step (2), when the pretreated ammonium molybdate sample solution is first filtered using the RP column and the H column, the flow rate of the pretreated ammonium molybdate sample solution pushed into the RP column and the H column is 2 mL / min.

[0016] In the step (2), when the pretreated ammonium molybdate sample solution is subjected to secondary filtration using a syringe filter, the thickness of the filter membrane of the syringe filter used is 0.22 μm or 0.25 μm.

[0017] The ion chromatography method used in the steps (1) and (3) selected a PAS-19 anion chromatography column, a PAG-4 anion protection column, and an IC-0015 anion suppressor; the working conditions of the ion chromatograph were: an injection volume of 25 μL, a flow rate of 1.0 mL / min, a column temperature of 30° C., a cell temperature of 35° C., and a suppressor current of 200 mA.

[0018] The ion chromatography method used in the step (1) and the step (3) uses potassium hydroxide solution for gradient elution, and the elution process is as follows: the initial concentration is 22mmol / L, the final concentration is 55mmol / L, 22mmol / L is maintained from 0 to 17min, the gradient start time is 17min, the end time is 30min, the mobile phase elution concentration increases from 22mmol / L to 55mmol / L, and 22mmol / L is maintained from 30min to 40min, and one gradient cycle is 40min.

[0019] The beneficial technical effects of the present invention are:

[0020] 1. The present invention provides a method for simultaneously determining seven anions in ammonium molybdate based on ion chromatography, which can simultaneously determine the F in ammonium molybdate samples. - , Cl - 、NO2 - Br - 、NO3 - PO4 3- 、SO4 2- .

[0021] 2. The present invention provides a method for simultaneously determining seven anions in ammonium molybdate based on ion chromatography. Before the ammonium molybdate sample is injected, it is filtered once through an RP column and an H column. After purification by an extraction column, heavy metal ions, uranium and organic compounds are removed. A secondary filtration is performed in combination with a syringe filter to eliminate interference with the target ions.

[0022] 3. The present invention provides a method for simultaneously determining 7 anions in ammonium molybdate based on ion chromatography, wherein a standard curve is established with the concentration of 7 anions ranging from 0.01 mg / L to 0.5 mg / L. - , Cl - 、NO2 - Br - 、NO3 - PO4 3- 、SO4 2- The linearity is better than 0.999 and the baseline noise is less than 0.2μS / cm.

[0023] 4. The present invention provides a method for simultaneously determining 7 anions in ammonium molybdate based on ion chromatography. The anion peak shape in the ammonium molybdate sample is good, the separation of each detection item is good, and the sensitivity is high.

[0024] 5. The present invention provides a method for simultaneously determining seven anions in ammonium molybdate based on ion chromatography, which has high accuracy, good stability and good precision.

[0025] 6. The method provided by the present invention for simultaneously determining seven anions in ammonium molybdate based on ion chromatography has simple and rapid pretreatment and short analysis time compared with traditional detection and analysis methods. It can be used for rapid analysis of large quantities of samples and is suitable for promotion in industrial and mining enterprises. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a chromatogram of a blank solution (ultrapure water) in an embodiment of the present invention;

[0027] Figure 2 7 kinds of anion standard curve chromatograms in the embodiment of the present invention;

[0028] Figure 3 This is a chromatogram of repeatability determination of ammonium molybdate sample in an embodiment of the present invention;

[0029] Figure 4 The ammonium molybdate sample and the sample spiked chromatogram in the embodiment of the present invention;

[0030] Figure 5 The chromatograms are of the ammonium molybdate sample and the sample-spiked amplified chromatogram in the embodiment of the present invention. DETAILED DESCRIPTION

[0031] The present invention is further described in detail below with reference to the accompanying drawings and embodiments.

[0032] In a method for simultaneously determining 7 anions in ammonium molybdate based on ion chromatography provided by the present invention, the 7 anions are F - , Cl - 、NO2 - Br - 、NO3 - PO4 3- 、SO4 2- .

[0033] Specifically, the present invention provides a method for simultaneously determining 7 anions in ammonium molybdate based on ion chromatography, comprising the following steps:

[0034] Step (1) preparing 7 kinds of anion mixed standard stock solutions, using ion chromatography to obtain retention time-conductivity chromatograms of a series of standard solutions of the 7 kinds of anions, and drawing a standard working curve based on the relationship between the anion concentration and the peak area in the mixed standard stock solution;

[0035] Use anion mixed standard solution to prepare series F - , Cl - 、NO2 - Br - 、NO3 - PO4 3- 、SO4 2- Mixed standard stock solution. Under the working conditions of the ion chromatograph, the anion mixed standard solution was sampled and tested to obtain the retention time-conductivity chromatograms of the series of standard solutions, respectively. - , Cl - 、NO2 - Br - 、NO3 - PO4 3- 、SO4 2- The ion mass concentration (x) is the abscissa and the peak area (y) is the ordinate, and the standard working curve is drawn.

[0036] Step (2) pre-treating and filtering the ammonium molybdate sample before sampling to remove heavy metal ions, uranium and organic compounds in the ammonium molybdate sample to obtain a treated ammonium molybdate sample;

[0037] Step (2.1) preparing NaOH solution;

[0038] Step (2.2) ammonium molybdate sample pretreatment: weigh an ammonium molybdate sample into a beaker or centrifuge tube, add the prepared NaOH solution, shake well, and sonicate until the sample is completely dissolved into a colorless and transparent state, thereby obtaining a pretreated ammonium molybdate sample solution;

[0039] Step (2.3) ammonium molybdate sample filtration: activating the RP column and the H column with deionized water, filtering the pretreated ammonium molybdate sample solution once with the RP column and the H column, and then filtering it twice with a syringe filter to obtain a treated ammonium molybdate sample;

[0040] Step (3) uses ion chromatography to measure the treated ammonium molybdate sample, obtains a retention time-conductivity chromatogram of the ammonium molybdate sample solution, and compares it with the concentration-peak area standard working curve of 7 anion contents to obtain the concentration of each anion in the ammonium molybdate sample.

[0041] In the following examples, the main instruments, main reagents, and ammonium molybdate samples used are as follows:

[0042] Main instruments: IC-10 ion chromatograph (Guangzhou Pulinsheng Technology Co., Ltd.), PAS-19 (4×250mm) anion chromatography column (Guangzhou Pulinsheng Technology Co., Ltd.), IC-0015 anion suppressor (Guangzhou Pulinsheng Technology Co., Ltd.), PAG-4 (4×50mm) anion guard column (Guangzhou Pulinsheng Technology Co., Ltd.), EAS-002 automatic sampler, IC-0048 syringe (Guangzhou Pulinsheng Technology Co., Ltd.), 0.22μm, 0.25μm filter membrane (Tianjin Jinteng Experimental Equipment Co., Ltd.).

[0043] Main reagents: sodium hydroxide (Tianjin Komeiou Chemical Reagent Co., Ltd.), potassium hydroxide (Tianjin Komeiou Chemical Reagent Co., Ltd.), anion mixed standard solution 1000 μg / mL (National Nonferrous Metals and Electronic Materials Analysis and Testing Center), anion mixed working standard solution 100 μg / mL (mixed standard solution 1000 μg / mL was diluted 10 times), anion mixed working standard solution 10 μg / mL (mixed standard solution 1000 μg / mL was diluted 100 times), the water used in the experiment was ultrapure water (18.2 MΩ·cm) made by PNK-30 ultrapure water machine.

[0044] The ammonium molybdate samples were obtained from actual production.

[0045] Example 1

[0046] The present invention provides a method for simultaneously determining seven anions in ammonium molybdate based on ion chromatography, which specifically comprises the following steps:

[0047] Step (1) preparing 7 kinds of anion mixed standard stock solutions, using ion chromatography to obtain retention time-conductivity chromatograms of a series of standard solutions of the 7 kinds of anions, and drawing a standard working curve based on the relationship between the anion concentration and the peak area in the mixed standard stock solution;

[0048] In step (1.1), a series of anion mixed standard solutions are prepared by gravimetric method.

[0049] Pipette 5mL F - , Cl - 、NO2 - Br - 、NO3 - PO4 3- 、SO4 2- Place the anion mixed standard solution in a 50mL volumetric flask, dilute to volume with ultrapure water to prepare a 100μg / mL anion mixed working standard solution; draw 5.0mL of 100μg / mL anion mixed standard solution into a 50mL volumetric flask, dilute to volume with ultrapure water to prepare a 10μg / mL anion mixed working standard solution.

[0050] Pipette 0.05mL, 0.25mL, 0.5mL of anion mixed working standard solution (10μg / mL) into a 50mL volumetric flask, dilute to volume with ultrapure water; Pipette 0.10mL, 0.25mL of mixed element standard solution (100μg / mL) into a 50mL volumetric flask, dilute to volume with ultrapure water, and mix well. The concentrations of this series of anion mixed standard solutions are 0.01μg / mL, 0.05μg / mL, 0.10μg / mL, 0.20μg / mL, 0.50μg / mL, respectively.

[0051] The blank solution used in this method is ultrapure water. Figure 1 is the chromatogram of the blank solution. Figure 1 It can be seen that ultrapure water does not interfere with the detection of target ions in ammonium molybdate.

[0052] Step (1.2) draws a standard working curve based on the relationship between the anion concentration and the peak area in the mixed standard stock solution;

[0053] Under the optimal working condition parameters of the ion chromatograph, the concentration of the series of anion mixed standard solutions was determined. Using the ion chromatograph, the injection volume of the anion mixed standard solution was 25 μL, and the retention time-conductivity chromatograms of the series of standard solutions of 7 anions were obtained.

[0054] F - , Cl - 、NO2 - Br - 、NO3 - PO4 3- 、SO4 2- The retention times were 4.188min, 7.525min, 9.613min, 12.255min, 14.095min, 25.664min and 16.956min respectively. The peak area of ​​each anion in the mixed standard stock solution was obtained by the retention time-conductivity chromatogram.

[0055] F - , Cl - 、NO2 - Br - 、NO3 - PO4 3- 、SO4 2- The ion mass concentration (x) is the horizontal axis, the peak area (y) is the vertical axis, and the standard working curve is drawn based on the relationship between the mass concentration and the peak area.

[0056] The chromatograms of the standard curves of 7 anions are as follows: Figure 2 The standard working curve data of 7 kinds of anions are shown in Table 1.

[0057] Table 1 Working curves of 7 anions

[0058]

[0059]

[0060] When the correlation coefficient of the standard working curve is >0.999, it can be used for analysis and determination. Figure 2 As shown, the peak shapes of the target ions to be measured are good, the separation effect is ideal, and a good linear relationship is presented.

[0061] Step (2) pre-treating and filtering the ammonium molybdate sample before sampling to remove heavy metal ions, uranium and organic compounds in the ammonium molybdate sample to obtain a treated ammonium molybdate sample;

[0062] Step (2.1) Prepare NaOH solution: weigh 0.8-1 g NaOH into a 1000 mL volumetric flask, dilute to volume with ultrapure water and shake well to obtain a NaOH solution with a concentration of 20-25 mmol / L, and transfer to a plastic bottle for storage;

[0063] Step (2.2) ammonium molybdate sample pretreatment: weigh an ammonium molybdate sample into a beaker or centrifuge tube, add the NaOH solution prepared in step (2.1), shake well, and then perform ultrasound until the sample is completely dissolved into a colorless and transparent state, thereby obtaining a pretreated ammonium molybdate sample solution;

[0064] Accurately weigh 0.1g of ammonium molybdate sample into a beaker or centrifuge tube, add 20mL 25mmol / LNaOH, shake well, and then put it into an ultrasonic cleaner for ultrasonication at a temperature of 45-50°C until the sample is completely dissolved and becomes colorless and transparent. The sample is diluted 200 times with 25mmol / L NaOH to obtain a pretreated ammonium molybdate sample solution.

[0065] Step (2.3) ammonium molybdate sample filtration: activating the RP column and the H column with deionized water, filtering the pretreated ammonium molybdate sample solution once with the RP column and the H column, and then filtering it twice with a syringe filter to obtain a treated ammonium molybdate sample;

[0066] Use a disposable syringe to extract deionized water for activation of the RP column and H column, and place them flat for 20 minutes to ensure that the small columns are fully activated. The ammonium molybdate sample solution pretreated in step (2.2) is slowly pushed into the RP column and H column at a flow rate of 2mL / min for a single filtration, and the first third of the solution is discarded. The subsequent sample solution is filtered twice by a syringe syringe, and the thickness of the syringe filter membrane is 0.22 and 0.25μm, and the treated ammonium molybdate sample is obtained for on-machine detection.

[0067] Since the ammonium molybdate sample contains a small amount of heavy metal ions and residual organic compounds, it needs to be purified by a small column before testing. The purpose of selecting the H column is to remove the metal ions such as potassium, sodium, calcium, magnesium, copper, and nickel contained in the ammonium molybdate sample, and the RP column is selected to remove the uranium metal and residual organic matter that may exist in the sample. At the same time, the RP column and the H column will reduce the interference peaks near the detection ions.

[0068] Step (3) uses ion chromatography to measure the treated ammonium molybdate sample to obtain a retention time-conductivity chromatogram of the ammonium molybdate sample solution, and compares it with the concentration-peak area standard working curve of 7 anions to obtain the concentration of each anion in the ammonium molybdate sample.

[0069] In the ion chromatography method used in the above examples, a PAS-19 anion chromatography column was selected and a potassium hydroxide solution was used for gradient elution.

[0070] The gradient elution process with KOH mobile phase as eluent was as follows: initial concentration was 22mmol / L, final concentration was 55mmol / L, 22mmol / L was maintained from 0 to 17min, gradient start time was 17min, end time was 30min, mobile phase elution concentration increased from 22mmol / L to 55mmol / L, maintained at 22mmol / L from 30min to 40min, and one gradient cycle was 40min.

[0071] The instrument operating parameters used in the above examples are: IC-10 ion chromatograph, PAS-19 (4×250 mm) anion chromatographic column, IC-0015 anion suppressor, PAG-4 (4×50 mm) anion guard column, and EAS-002 autosampler.

[0072] The working conditions of the ion chromatograph are: injection volume 25 μL, flow rate 1.0 mL / min, column temperature 30 °C, cell temperature 35 °C, suppressor current 200 mA. The sample was injected once for separation and detection, and the overall analysis and determination time was 44 min. The specific instrument working condition parameters are shown in Table 2.

[0073] Table 2 Instrument working condition parameters

[0074]

[0075]

[0076] Example 2

[0077] Detection limit determination

[0078] The blank solution was measured 11 times continuously under the working conditions of the ion chromatograph, and the noise was calculated as F. - , Cl- 、NO2 - Br - 、NO3 - PO4 3- 、SO4 2- The peak height of each component at the lowest concentration point (0.01 mg / L) was divided by the signal-to-noise ratio, and the concentration corresponding to 3 times the signal-to-noise ratio was taken as the detection limit. The detection limits of the seven anions were calculated to be 0.048 mg / L, 0.011 mg / L, 0.017 mg / L, 0.015 mg / L, 0.022 mg / L, 1.283 mg / L, and 0.025 mg / L, respectively. Taking 4 times the detection limit as the lower limit of determination, the lower limits of determination of the seven anions were 0.192 mg / L, 0.044 mg / L, 0.068 mg / L, 0.060 mg / L, 0.088 mg / L, 5.132 mg / L, and 0.100 mg / L, respectively. The results are shown in Table 3.

[0079] Table 3 Detection limits and determination limits of 7 anions

[0080] Test items <![CDATA[F - ]]> <![CDATA[Cl - ]]> <![CDATA[NO2 - ]]> <![CDATA[Br - ]]> <![CDATA[NO3 - ]]> <![CDATA[PO4 3- ]]> <![CDATA[SO4 2- ]]> Peak height (μS / cm) 0.0505 0.0244 0.0134 0.0065 0.0119 0.0211 0.0080 Noise(μS / cm) 0.0815 0.0088 0.0077 0.0033 0.0088 0.1806 0.0067 Signal-to-Noise Ratio 0.6199 2.7552 1.7400 1.9743 1.3563 0.1169 1.1921 Detection limit (mg / L) 0.048 0.011 0.017 0.015 0.022 1.283 0.025 Determination limit (mg / L) 0.192 0.044 0.068 0.060 0.088 5.132 0.100

[0081] Example 3

[0082] Precision determination

[0083] According to the above research method, the ammonium molybdate samples were spiked with 0.1 mg / LF under the working conditions of the ion chromatograph. - , Cl - 、NO2 - Br - 、NO3 - PO4 3- 、SO4 2- The anion was determined 6 times independently to investigate the precision of the method. Figure 3 As shown, RSD was calculated based on the peak area, and the results are shown in Table 4. Figure 3 It can be seen that the overall stability is good, the RSD of the peak area is less than 1.2%, and the precision of the seven anions is good.

[0084] Table 4 Results of precision tests for 7 anions

[0085]

[0086] Example 4

[0087] Accuracy determination

[0088] Add 0.1mg / LF to the ammonium molybdate sample - , Cl - 、NO2 - Br- 、NO3 - 、SO4 2- The ions were subjected to low concentration spike recovery test, and the test results are shown in Table 5. After spike addition, F - , Cl - 、NO2 - Br - 、NO3 - 、SO4 2- The recovery rate of ions was 91% to 112%, indicating that the method had good accuracy. Figure 4 This is the chromatogram of ammonium molybdate sample and sample spike. Figure 5 These are the chromatograms of ammonium molybdate sample and sample spike enlargement.

[0089] Table 5 Accuracy of the determination results of 7 anions

[0090]

[0091] The method of the present invention establishes a method for simultaneously determining F in ammonium molybdate samples by ion chromatography. - , Cl - 、NO2 - Br - 、NO3 - PO4 3- 、SO4 2- The anion method removes heavy metal ions, uranium ions and complex samples containing interfering substances in ammonium molybdate samples by filtering them once with RP columns and H columns to eliminate interference. The anion peak shape detected by this method in ammonium molybdate samples is good, the separation of each test item is good, and the sensitivity is high. From the perspective of result accuracy, precision verification and efficiency, ion chromatography can meet the requirements and is superior to traditional chemical analysis methods.

[0092] The present invention is described in detail above with reference to the accompanying drawings and embodiments, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge of ordinary technicians in the field without departing from the purpose of the present invention. The contents not described in detail in the present invention can adopt the existing technology.

Claims

1. A method for simultaneously determining seven anions in ammonium molybdate based on ion chromatography, characterized in that: The seven anions are F - , Cl - 、NO2 - Br - 、NO3 - PO4 3- 、SO4 2- , the method comprising: Step (1) preparing 7 kinds of anion mixed standard stock solutions, using ion chromatography to obtain retention time-conductivity chromatograms of a series of standard solutions of the 7 kinds of anions, and drawing a standard working curve based on the relationship between the anion concentration and the peak area in the mixed standard stock solution; Step (2) pre-treating and filtering the ammonium molybdate sample before sampling to remove heavy metal ions, uranium and organic compounds in the ammonium molybdate sample to obtain a treated ammonium molybdate sample; Step (3) uses ion chromatography to measure the treated ammonium molybdate sample, detects the retention time-conductivity chromatogram of the ammonium molybdate sample solution, and compares it with the concentration-peak area standard working curve of 7 anion contents to obtain the concentration of each anion in the ammonium molybdate sample.

2. The method for simultaneously determining 7 anions in ammonium molybdate based on ion chromatography according to claim 1, characterized in that: The concentrations of the seven anion mixed standard stock solutions prepared in step (1) are 0.01 μg / mL, 0.05 μg / mL, 0.10 μg / mL, 0.20 μg / mL, and 0.50 μg / mL, respectively.

3. The method for simultaneously determining 7 anions in ammonium molybdate based on ion chromatography according to claim 1, characterized in that: The ammonium molybdate sample is pretreated in step (2) by dissolving the ammonium molybdate sample in a NaOH solution, shaking and ultrasonicating until the sample is completely dissolved into a colorless and transparent state, thereby obtaining a pretreated ammonium molybdate sample solution.

4. The method for simultaneously determining 7 anions in ammonium molybdate based on ion chromatography according to claim 3, characterized in that: The concentration of the NaOH solution in step (2) is 20-25 mmol / L, and the ultrasonic temperature is 45-50°C.

5. The method for simultaneously determining 7 anions in ammonium molybdate based on ion chromatography according to claim 1, characterized in that: The ammonium molybdate sample is treated in step (2) by activating the RP column and the H column with deionized water, filtering the pretreated ammonium molybdate sample solution once with the RP column and the H column, and then filtering it twice with a syringe filter to obtain the treated ammonium molybdate sample.

6. The method for simultaneously determining seven anions in ammonium molybdate based on ion chromatography according to claim 5, characterized in that: In the step (2), when the pretreated ammonium molybdate sample solution is first filtered using the RP column and the H column, the flow rate of the pretreated ammonium molybdate sample solution pushed into the RP column and the H column is 2 mL / min.

7. The method for simultaneously determining seven anions in ammonium molybdate based on ion chromatography according to claim 5, characterized in that: In the step (2), when the pretreated ammonium molybdate sample solution is subjected to secondary filtration using a syringe filter, the thickness of the filter membrane of the syringe filter used is 0.22 μm or 0.25 μm.

8. The method for simultaneously determining seven anions in ammonium molybdate based on ion chromatography according to claim 1, characterized in that: The ion chromatography method used in the steps (1) and (3) selected a PAS-19 anion chromatography column, a PAG-4 anion protection column, and an IC-0015 anion suppressor; the working conditions of the ion chromatograph were: an injection volume of 25 μL, a flow rate of 1.0 mL / min, a column temperature of 30° C., a cell temperature of 35° C., and a suppressor current of 200 mA.

9. The method for simultaneously determining seven anions in ammonium molybdate based on ion chromatography according to claim 1, characterized in that: The ion chromatography method used in the step (1) and the step (3) uses potassium hydroxide solution for gradient elution, and the elution process is as follows: the initial concentration is 22mmol / L, the final concentration is 55mmol / L, 22mmol / L is maintained from 0 to 17min, the gradient start time is 17min, the end time is 30min, the mobile phase elution concentration increases from 22mmol / L to 55mmol / L, and 22mmol / L is maintained from 30min to 40min, and one gradient cycle is 40min.

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