Method for measuring nitrogen content in agricultural ammonium bicarbonate fertilizer based on edxrf method

Abstract

This invention discloses a method for measuring the nitrogen content in agricultural ammonium bicarbonate fertilizer based on EDXRF. First, the agricultural ammonium bicarbonate fertilizer sample to be measured is pretreated and prepared. The sample is a precipitate containing barium, and the barium in the precipitate has a stoichiometric relationship with the nitrogen in the agricultural ammonium bicarbonate fertilizer powder sample. Then, the barium in the sample is measured using an energy-dispersive X-ray fluorescence spectrometer to obtain the net area of ​​the characteristic peak of barium. This area is then substituted into a calibration curve to obtain the percentage content of barium in the sample. Finally, based on the stoichiometric relationship between nitrogen and barium in the chemical reaction that prepared the sample, the nitrogen content in the agricultural ammonium bicarbonate fertilizer can be calculated. This method achieves the measurement of nitrogen content in agricultural ammonium bicarbonate fertilizer through indirect measurement, and is characterized by its speed and ease of operation.

Description

Technical Field

[0001] This invention relates to the field of analytical testing technology, and in particular provides a method for measuring the nitrogen content in agricultural ammonium bicarbonate fertilizer based on the EDXRF method. Background Technology

[0002] Currently, methods for detecting the content of light elements in substances mainly fall into two categories: chemical analysis and instrumental analysis. Chemical analysis methods can be further divided into specific measurement methods such as electrolysis, tube furnace chromatography, gravimetric analysis, neutralization titration, colorimetry, and conductivity methods, depending on the element and sample type. While conventional chemical methods can accurately quantify light elements, they are cumbersome, time-consuming, and require operators with extensive chemical knowledge and high experimental skills. This has led to instrumental analysis methods becoming increasingly popular among analytical users. Currently, instrumental research methods include emission spectroscopy, atomic absorption spectroscopy (AAS), X-ray fluorescence analysis (XRF), and inductively coupled plasma atomic emission spectrometry (ICP-AES). Among these, energy-dispersive X-ray fluorescence analysis (EDXRF) utilizes an X-ray tube as the primary spectral excitation device. The primary X-rays emitted by the tube irradiate the sample, exciting the target element and producing X-ray fluorescence. This fluorescence is received by a detector, which detects the energy value of the target element. By comparing this value with a calibration curve plotted based on standard sample measurement data, the content of the target element in the sample can be calculated, thus completing the quantitative analysis of the element. Energy-dispersive X-ray fluorescence analysis is widely used in many fields due to its advantages such as accuracy and a wide range of analytical elements. However, when analyzing nitrogen, the low fluorescence yield and excitation efficiency of the element itself lead to unsatisfactory results when directly performing analytical detection. Summary of the Invention

[0003] Therefore, the purpose of this invention is to provide a method for measuring nitrogen content in agricultural ammonium bicarbonate fertilizer based on EDXRF method, so as to solve the problem of low sensitivity of nitrogen element detection by energy dispersive X-ray fluorescence spectroscopy in the prior art.

[0004] The technical solution provided by this invention is: a method for measuring the nitrogen content in agricultural ammonium bicarbonate fertilizer based on the EDXRF method, comprising the following steps:

[0005] Step 1: Take an agricultural ammonium bicarbonate fertilizer sample and pre-treat the sample to obtain an agricultural ammonium bicarbonate fertilizer powder sample.

[0006] Step 2: Prepare a test sample using the agricultural ammonium bicarbonate fertilizer powder sample, wherein the test sample is a precipitate containing barium, and the barium in the precipitate has a stoichiometric relationship with the nitrogen in the agricultural ammonium bicarbonate fertilizer powder sample.

[0007] Step 3: Measure the barium element in the sample to be tested using an energy dispersive X-ray fluorescence analyzer to obtain the net area of ​​the characteristic peak of barium element, and obtain the percentage content of barium element in the sample to be tested according to the calibration curve obtained in advance to reflect the relationship between the net area of ​​the characteristic peak of barium element and the percentage content of barium element.

[0008] Step 4: Calculate the nitrogen content in the agricultural ammonium bicarbonate fertilizer based on the stoichiometric relationship between nitrogen and barium in the chemical reaction that prepares the sample to be tested.

[0009] Preferably, in step 1, the pretreatment involves uniformly grinding the agricultural ammonium bicarbonate fertilizer sample.

[0010] Further optimization, step 2, the preparation of the sample to be tested, includes the following steps:

[0011] Step 21: Take the agricultural ammonium bicarbonate fertilizer powder sample, pour it into a distillation flask, add distilled water to dissolve it, then add sodium hydroxide solution to the distillation flask to start distillation, so that the ammonium ions in the agricultural ammonium bicarbonate fertilizer powder sample react completely to generate ammonia gas.

[0012] Step 22: Condense the ammonia gas and allow it to be completely absorbed by sulfuric acid to obtain a mixed solution of ammonium sulfate and sulfuric acid;

[0013] Step 23: Add sodium hydroxide standard titration solution to the mixed solution of ammonium sulfate and sulfuric acid until the sulfuric acid is completely consumed. At this point, a mixed solution of ammonium sulfate and sodium sulfate is obtained.

[0014] Step 24: Add barium hydroxide solution to the ammonium sulfate and sodium sulfate mixed solution until no more precipitate is formed;

[0015] Step 25: Filter and dry the mixed solution obtained in step 24 to obtain barium sulfate precipitate. After grinding, take an appropriate amount of barium sulfate powder and compress it into tablets to obtain the sample to be tested.

[0016] Further preferred, steps 21 to 24 are performed in a distillation apparatus.

[0017] Further optimization involves using dense, ashless quantitative filter paper and a vacuum funnel for filtration in step 25.

[0018] Further optimization involves using an oven in step 25 to dry the food at a temperature of 100°C for 2 hours.

[0019] Further, in step 3, the method for obtaining the calibration curve showing the relationship between the net area of ​​the characteristic peak of barium and the percentage content of barium includes the following steps:

[0020] Pretreated agricultural ammonium bicarbonate fertilizer powder samples were mixed with barium sulfate analytical grade powder in different gradient ratios and carefully ground. Then, multiple standard samples were prepared by powder compression method.

[0021] The multiple standard samples were measured using an energy-dispersive X-ray fluorescence analyzer. The net area of ​​the characteristic peak of barium in each standard sample was measured, and the calibration curve was plotted with the percentage content of barium as the abscissa and the net area of ​​the characteristic peak of barium as the ordinate.

[0022] Further preferred, the main component of the agricultural ammonium bicarbonate fertilizer sample is ammonium bicarbonate, with other minor components being heavy metal impurities and fluorine.

[0023] Further optimization involves preparing multiple test samples using multiple samples of agricultural ammonium bicarbonate fertilizer powder, calculating the nitrogen content in the agricultural ammonium bicarbonate fertilizer powder samples corresponding to the test samples, and taking the average value as the nitrogen content in the agricultural ammonium bicarbonate fertilizer.

[0024] The method for measuring nitrogen content in agricultural ammonium bicarbonate fertilizer based on EDXRF provided by this invention can achieve rapid measurement of nitrogen content, is easy to operate, and has low measurement cost. It overcomes the disadvantages of traditional chemical methods, which are time-consuming and require professional personnel to operate. It can effectively realize the quantitative analysis of nitrogen element in agricultural ammonium bicarbonate fertilizer using energy dispersive X-ray fluorescence analyzer.

[0025] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit the disclosure of the present invention. Attached Figure Description

[0026] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a flowchart illustrating the preparation of the sample to be tested, as provided in the examples. Detailed Implementation

[0029] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numerals in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Rather, they are merely examples of systems consistent with some aspects of the invention as detailed in the appended claims.

[0030] To address the low sensitivity and efficiency of direct analysis of nitrogen in agricultural ammonium bicarbonate fertilizer using energy-dispersive X-ray fluorescence (EDXRF), this invention provides a method for measuring nitrogen content in agricultural ammonium bicarbonate fertilizer based on EDXRF. This method transforms the inability to directly and accurately measure nitrogen using EDXRF into the analysis and measurement of barium. The nitrogen content is then calculated based on the quantitative relationship between barium and nitrogen in the chemical reaction. Ultimately, quantitative analysis of nitrogen in agricultural ammonium bicarbonate fertilizer using EDXRF can be achieved. The specific steps include:

[0031] Step 1: Take an agricultural ammonium bicarbonate fertilizer sample and pre-treat the sample to obtain an agricultural ammonium bicarbonate fertilizer powder sample.

[0032] Step 2: Prepare a test sample using the agricultural ammonium bicarbonate fertilizer powder sample, wherein the test sample is a precipitate containing barium, and the barium in the precipitate has a stoichiometric relationship with the nitrogen in the agricultural ammonium bicarbonate fertilizer powder sample.

[0033] Step 3: Measure the barium element in the sample to be tested using an energy dispersive X-ray fluorescence analyzer to obtain the net area of ​​the characteristic peak of barium element, and obtain the percentage content of barium element in the sample to be tested according to the calibration curve obtained in advance to reflect the relationship between the net area of ​​the characteristic peak of barium element and the percentage content of barium element.

[0034] Step 4: Calculate the nitrogen content in the agricultural ammonium bicarbonate fertilizer based on the stoichiometric relationship between nitrogen and barium in the chemical reaction that prepares the sample to be tested.

[0035] This method for measuring nitrogen content in agricultural ammonium bicarbonate fertilizer based on EDXRF involves first pretreatment and preparation of the sample, wherein the sample is a precipitate containing barium, and the barium in the precipitate has a stoichiometric relationship with the nitrogen in the agricultural ammonium bicarbonate fertilizer powder sample. Then, the barium in the sample is measured using an energy-dispersive X-ray fluorescence spectrometer to obtain the net area of ​​the characteristic peak of barium, which is then calibrated to obtain the percentage content of barium in the sample. Finally, based on the stoichiometric relationship between nitrogen and barium in the chemical reaction during sample preparation, the nitrogen content in the agricultural ammonium bicarbonate fertilizer can be calculated.

[0036] In step 1, the pretreatment involves uniformly grinding the agricultural ammonium bicarbonate fertilizer sample.

[0037] Step 2, preparing the sample to be tested, includes the following steps:

[0038] Step 21: Take the agricultural ammonium bicarbonate fertilizer powder sample, pour it into a distillation flask, add distilled water to dissolve it, then add sodium hydroxide solution to the distillation flask to start distillation, so that the ammonium ions in the agricultural ammonium bicarbonate fertilizer powder sample react completely to generate ammonia gas.

[0039] Step 22: Condense the ammonia gas and allow it to be completely absorbed by sulfuric acid to obtain a mixed solution of ammonium sulfate and sulfuric acid;

[0040] Step 23: Add sodium hydroxide standard titration solution to the mixed solution of ammonium sulfate and sulfuric acid until the sulfuric acid is completely consumed. At this point, a mixed solution of ammonium sulfate and sodium sulfate is obtained.

[0041] Step 24: Add barium hydroxide solution to the ammonium sulfate and sodium sulfate mixed solution until no more precipitate is formed;

[0042] Step 25: Filter and dry the mixed solution obtained in step 24 to obtain barium sulfate precipitate. After grinding, take an appropriate amount of barium sulfate powder and compress it into tablets to obtain the sample to be tested.

[0043] Preferably, steps 21 to 24 are completed in a distillation apparatus, which includes a dropping funnel, a distillation flask, a condenser, an Erlenmeyer flask, and an oil bath. The dropping funnel, distillation flask, condenser, and Erlenmeyer flask are connected in sequence. The oil bath is used to heat the distillation flask. Sodium hydroxide solution is placed in the dropping funnel. The agricultural ammonium bicarbonate fertilizer powder sample is placed in the distillation flask. The distillation process is carried out in the distillation flask, and the generated ammonia gas enters the Erlenmeyer flask containing excess sulfuric acid through the condenser.

[0044] Preferably, in step 25, filtration is performed using dense, ashless quantitative filter paper and a vacuum funnel.

[0045] Preferably, in step 25, drying is carried out using an oven at a temperature of 100°C for 2 hours.

[0046] To ensure that the standard sample and the sample to be tested have similar physical morphology and chemical composition, step 3, which involves obtaining a calibration curve showing the relationship between the net area of ​​the characteristic peak of barium and the percentage content of barium, includes the following steps:

[0047] Pretreated agricultural ammonium bicarbonate fertilizer powder samples were mixed with barium sulfate analytical grade powder in different gradient ratios and carefully ground. Then, multiple standard samples were prepared by powder compression method.

[0048] The multiple standard samples were measured using an energy-dispersive X-ray fluorescence analyzer. The net area of ​​the characteristic peak of barium in each standard sample was measured, and the calibration curve was plotted with the percentage content of barium as the abscissa and the net area of ​​the characteristic peak of barium as the ordinate.

[0049] The main component of the agricultural ammonium bicarbonate fertilizer sample is ammonium bicarbonate, with other minor components being heavy metal impurities and fluorine.

[0050] As an improvement to the technical solution, in step 2, multiple samples to be tested are prepared using multiple samples of agricultural ammonium bicarbonate fertilizer powder, and the nitrogen content in the agricultural ammonium bicarbonate fertilizer powder corresponding to the sample to be tested is calculated, and the average value is taken as the nitrogen content in the agricultural ammonium bicarbonate fertilizer.

[0051] Example 1

[0052] Step 1: Take an agricultural ammonium bicarbonate fertilizer sample and grind it evenly to obtain an agricultural ammonium bicarbonate fertilizer powder sample. The main component of the agricultural ammonium bicarbonate fertilizer sample is ammonium bicarbonate, and other small components are heavy metal impurities and fluorine.

[0053] Step 2: Prepare the test sample using the agricultural ammonium bicarbonate fertilizer powder sample:

[0054] a. Weigh 5 samples of agricultural ammonium bicarbonate fertilizer powder, each weighing 1.0g, and pour them into 5 500mL distillation flasks. Add about 300mL of distilled water, and measure 20mL of sodium hydroxide solution (400g / L) into a dropping funnel. Add 40mL of sulfuric acid solution (0.5mol / L) to a 500mL conical flask receiver. Connect the conical flask and the dropping funnel to the distillation apparatus, and place the distillation flasks on an oil bath.

[0055] b. Turn on the cooling water, open the stopcock of the dropping funnel, and when the sodium hydroxide solution is about to run out, add 20-30 mL of distilled water to rinse the funnel. When a small amount of distilled water remains, close the stopcock and let it stand for ten minutes. Start distillation. After distilling out at least 150 mL of distillate, use pH test paper to test the droplets at the outlet of the condenser. If there is no alkalinity, stop the distillation. At this point, all the nitrogen in the fertilizer has been transferred to the sulfuric acid. Specifically, during distillation, the nitrogen in the fertilizer is converted from the form of ammonium ions to ammonia vapor. After condensation, it forms ammonia hydrate and is absorbed by the sulfuric acid solution in the conical flask to form ammonium ions.

[0056] c. Remove the conical flask (containing a mixed solution of ammonium sulfate and sulfuric acid), and then titrate with a standard sodium hydroxide solution (0.5 mol / L) until the solution turns grayish-green (methyl red-methylene blue mixed indicator has been added to the solution beforehand). At this point, the sulfuric acid has been completely consumed, and the conical flask contains a mixed solution of ammonium sulfate and sodium sulfate.

[0057] d. Add barium hydroxide solution (0.04 mol / L) to the conical flask until no more precipitate is formed. At this point, both ammonium sulfate and sodium sulfate have reacted completely with barium hydroxide and formed barium sulfate precipitate.

[0058] e. After standing for one hour, filter the above mixed solution with dense ashless quantitative filter paper, and then dry it in an oven (temperature 100℃, time 2 hours) to obtain barium sulfate precipitate. Then, weigh the total mass of each group of precipitates with an electronic balance, grind them, weigh 0.3g of each precipitate and compress them into tablets to obtain 5 samples to be tested.

[0059] Step 3: Measure the barium content in the sample using an energy-dispersive X-ray fluorescence analyzer. Detect the net area of ​​the characteristic peak of barium and input it into a pre-obtained calibration curve reflecting the relationship between the net area of ​​the characteristic peak and the percentage content of barium. The percentage content of barium in the sample is then obtained. The calibration curve is obtained as follows:

[0060] Pretreated agricultural ammonium bicarbonate fertilizer powder samples and barium sulfate analytical grade powder were mixed evenly and ground at mass ratios of 5:5, 4:6, 3:7, 2:8, and 1:9 (i.e., barium content of 29.42%, 35.30%, 41.19%, 47.67%, and 52.95%) to obtain 5 samples. Each sample weighed 0.3g and was used to prepare standard samples by powder compression tableting.

[0061] The above five standard samples were measured using an energy-dispersive X-ray fluorescence analyzer. The net area of ​​the characteristic peak of barium in each standard sample was measured, and the calibration curve was plotted with the percentage content of barium as the abscissa and the net area of ​​the characteristic peak of barium as the ordinate.

[0062] Step 4: Based on the stoichiometric relationship between nitrogen and barium in the chemical reaction for preparing the test samples, the nitrogen content in the above 5 agricultural ammonium bicarbonate fertilizer powder samples was calculated.

[0063] The average of the above measurement results was then compared with the TOC (Total Organic Carbon) method. The comparison results are shown in Table 1. Table 1 shows that the measurement results of nitrogen content in agricultural ammonium bicarbonate fertilizer obtained by this method are basically consistent with those obtained by the TOC method, proving that this method can be reliably applied to the measurement of nitrogen content in agricultural ammonium bicarbonate fertilizer.

[0064] Table 1

[0065]

[0066] Other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of the invention are indicated by the claims.

[0067] It should be understood that the present invention is not limited to the precise process described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of the invention is limited only by the appended claims.

Claims

1. A method for measuring nitrogen content in agricultural ammonium bicarbonate fertilizer based on EDXRF, characterized in that, Includes the following steps: Step 1: Take an agricultural ammonium bicarbonate fertilizer sample and pre-treat the sample to obtain an agricultural ammonium bicarbonate fertilizer powder sample. Step 2: Prepare a test sample using the agricultural ammonium bicarbonate fertilizer powder sample, wherein the test sample is a precipitate containing barium, and the barium in the precipitate has a stoichiometric relationship with the nitrogen in the agricultural ammonium bicarbonate fertilizer powder sample; the preparation of the test sample includes the following steps: Step 21: Take the agricultural ammonium bicarbonate fertilizer powder sample, pour it into a distillation flask, add distilled water to dissolve it, then add sodium hydroxide solution to the distillation flask to start distillation, so that the ammonium ions in the agricultural ammonium bicarbonate fertilizer powder sample react completely to generate ammonia gas. Step 22: Condense the ammonia gas and allow it to be completely absorbed by sulfuric acid to obtain a mixed solution of ammonium sulfate and sulfuric acid; Step 23: Add sodium hydroxide standard titration solution to the mixed solution of ammonium sulfate and sulfuric acid until the sulfuric acid is completely consumed. At this point, a mixed solution of ammonium sulfate and sodium sulfate is obtained. Step 24: Add barium hydroxide solution to the ammonium sulfate and sodium sulfate mixed solution until no more precipitate is formed; Step 25: Filter and dry the mixed solution obtained in step 24 to obtain barium sulfate precipitate. After grinding, take an appropriate amount of barium sulfate powder and compress it into a tablet to obtain the sample to be tested. Step 3: Measure the barium element in the sample to be tested using an energy dispersive X-ray fluorescence analyzer to obtain the net area of ​​the characteristic peak of barium element, and obtain the percentage content of barium element in the sample to be tested according to the calibration curve obtained in advance to reflect the relationship between the net area of ​​the characteristic peak of barium element and the percentage content of barium element. Step 4: Calculate the nitrogen content in the agricultural ammonium bicarbonate fertilizer based on the stoichiometric relationship between nitrogen and barium in the chemical reaction that prepares the sample to be tested.

2. The method for measuring nitrogen content in agricultural ammonium bicarbonate fertilizer based on EDXRF method according to claim 1, characterized in that: In step 1, the pretreatment involves uniformly grinding the agricultural ammonium bicarbonate fertilizer sample.

3. The method for measuring nitrogen content in agricultural ammonium bicarbonate fertilizer based on EDXRF method according to claim 1, characterized in that: Steps 21 to 24 are completed in the distillation apparatus.

4. The method for measuring nitrogen content in agricultural ammonium bicarbonate fertilizer based on EDXRF method according to claim 1, characterized in that: In step 25, filtration is performed using dense, ashless quantitative filter paper and a vacuum funnel.

5. The method for measuring nitrogen content in agricultural ammonium bicarbonate fertilizer based on EDXRF method according to claim 1, characterized in that: In step 25, the product is dried in an oven at 100°C for 2 hours.

6. The method for measuring nitrogen content in agricultural ammonium bicarbonate fertilizer based on EDXRF method according to claim 1, characterized in that: Step 3, the method for obtaining the calibration curve showing the relationship between the net area of ​​the characteristic peak of barium and the percentage content of barium, includes the following steps: Pretreated agricultural ammonium bicarbonate fertilizer powder samples were mixed with barium sulfate analytical grade powder in different gradient ratios and carefully ground. Then, multiple standard samples were prepared by powder compression method. The multiple standard samples were measured using an energy-dispersive X-ray fluorescence analyzer. The net area of ​​the characteristic peak of barium in each standard sample was measured, and the calibration curve was plotted with the percentage content of barium as the abscissa and the net area of ​​the characteristic peak of barium as the ordinate.

7. The method for measuring nitrogen content in agricultural ammonium bicarbonate fertilizer based on EDXRF method according to claim 1, characterized in that: The main component of the agricultural ammonium bicarbonate fertilizer sample is ammonium bicarbonate, with other minor components being heavy metal impurities and fluorine.

8. The method for measuring nitrogen content in agricultural ammonium bicarbonate fertilizer based on EDXRF method according to claim 1, characterized in that: In step 2, multiple samples to be tested are prepared using multiple samples of agricultural ammonium bicarbonate fertilizer powder. The nitrogen content in the agricultural ammonium bicarbonate fertilizer powder corresponding to the sample to be tested is calculated, and the average value is taken as the nitrogen content in the agricultural ammonium bicarbonate fertilizer.

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