阅读说明：本技术 一种应用能量色散x射线荧光光谱分析含磷饲料中磷元素含量的方法 (Method for analyzing content of phosphorus element in phosphorus-containing feed by using energy dispersion X-ray fluorescence spectrum ) 是由 邓玉福 刘伊初 李继 赵婷伟 于 2019-11-12 设计创作，主要内容包括：本发明公开了一种应用能量色散X射线荧光光谱分析测定含磷饲料中的磷元素含量的方法,本方法先对含磷饲料样品进行化学预处理,分别制备标准样品及待测样品。用能量色散X射线荧光分析仪对标准样品中的钼元素进行测量,绘制定标曲线,再对待测样品中的钼元素在相同条件下进行检测,探测出钼元素的特征峰面积,代入定标曲线,得到待测样品中钼元素的含量。最后根据磷钼酸喹啉中磷元素与钼元素的化学数量关系计算得到磷的含量。本发明通过间接的方法能够实现对含磷饲料中总的磷元素的测量。与传统方法相比较,本方法制样操作简单,缩短检测时间,精确度高。(The invention discloses a method for determining the content of phosphorus element in a phosphorus-containing feed by using energy dispersion X-ray fluorescence spectrum analysis. Measuring the molybdenum element in the standard sample by using an energy dispersion X-ray fluorescence analyzer, drawing a calibration curve, detecting the molybdenum element in the sample to be detected under the same condition, detecting the characteristic peak area of the molybdenum element, substituting the characteristic peak area into the calibration curve, and obtaining the content of the molybdenum element in the sample to be detected. And finally, calculating the content of the phosphorus according to the chemical quantitative relation of the phosphorus element and the molybdenum element in the phosphomolybdic acid quinoline. The invention can realize the measurement of the total phosphorus element in the phosphorus-containing feed by an indirect method. Compared with the traditional method, the method has the advantages of simple sample preparation operation, shortened detection time and high accuracy.)

1. A method for determining the content of phosphorus element in phosphorus-containing feed by applying energy dispersion X-ray fluorescence spectrum analysis is characterized by comprising the following steps: the method comprises the following steps:

step one, preparing a quinomolybdenyl citraconic ketone precipitator;

step two, preparing a sample to be detected;

step three, preparing a standard sample;

step four, drawing a calibration curve by taking the measured net area of the characteristic peak of the molybdenum element in each standard sample as a vertical coordinate and taking the percentage content of the added molybdenum element as a horizontal coordinate;

and fifthly, measuring the molybdenum element in the sample to be measured by the energy dispersion X-ray fluorescence spectrum analyzer again.

2. The method for determining the content of phosphorus in the phosphorus-containing feed by using energy dispersive X-ray fluorescence spectrometry as claimed in claim 1, wherein the method comprises the following steps: the method specifically comprises the following steps:

step one, preparing a quinomolybdenyl citraconic ketone precipitator:

solution A-70 g of sodium molybdate is weighed in a 400ml beaker and dissolved by 100ml of water;

solution B-weigh 60g of citric acid into a 1000ml beaker, dissolve with 100ml of water, add 85ml of nitric acid (1+ 1);

solution C-adding solution A to solution B, and mixing;

solution D-mix 35ml nitric acid and 100ml water in a 400ml beaker, add 5ml quinoline;

solution E-add solution D to solution C and mix well. Standing overnight, filtering with glass crucible or filter paper, adding 280ml acetone into the filtrate, and diluting with water to 1000 ml;

storing the precipitant in a polyethylene bottle, and keeping out the sun and avoiding heat;

step two, preparing a sample to be detected:

a. weighing about 0.8g of sample, accurately measuring to 0.2mg, placing in a 100ml beaker, adding 10ml of hydrochloric acid and a small amount of water, covering a watch glass, and boiling for 10 min; cooling, transferring into a 250ml volumetric flask, diluting with water to a scale, and shaking up; the solution is a test solution A and is used for measuring the total phosphorus content;

b. transferring 20ml of the test solution A into a 250ml beaker by using a pipette, adding water until the total volume is about 100ml, adding 50ml of a quinomolybdenyl citrazone solution, heating in a water bath until the temperature of the content in the beaker reaches 75 +/-5 ℃, keeping the temperature for 30s, cooling to room temperature, and stirring for 3-4 times in the cooling process;

c. filtering the supernatant with a glass sand crucible with constant weight at 180 +/-5 ℃ or 250 +/-10 ℃, washing the precipitate for 5-6 times by decantation, wherein about 20ml of water is used for each time, transferring the precipitate into the glass sand crucible, and continuously washing the precipitate for 3-4 times by water, wherein the precipitate in the solution is acid insoluble substances and quinoline phosphomolybdate precipitate.

d. Placing the glass sand crucible in an electric heating drying oven, drying at 180 +/-5 ℃ for 45min, taking out, placing in a dryer, cooling to room temperature, weighing, and marking as a first precipitate;

step three, preparing a standard sample:

a. weighing 3.6g of sample, dissolving in 200ml of distilled water at the temperature of 30 ℃, and keeping for 10 min; the precipitate in the solution is the impurity precipitate insoluble in water;

b. standing the precipitate, washing, filtering and drying to obtain a precipitate which is marked as a second precipitate;

step four, mixing the second precipitate and phosphomolybdic acid powder according to different content proportion gradients; preparing a standard sample according to a powder tabletting method, and measuring the content of molybdenum element in the standard sample by using an energy dispersion X-ray fluorescence spectrum analyzer; drawing a calibration curve by taking the measured net area of the characteristic peak of the molybdenum element in each standard sample as a vertical coordinate and taking the percentage content of the added molybdenum element as a horizontal coordinate;

measuring the molybdenum element in the sample to be measured by the energy dispersion X-ray fluorescence spectrum analyzer; detecting to obtain the net area of the characteristic peak of the molybdenum element in the sample to be detected, and substituting the net area into the calibration curve to obtain the percentage content of the molybdenum element in the sample to be detected; and finally, calculating the percentage content of the phosphorus element in the phosphorus-containing feed according to the chemical quantity relationship of the phosphorus element and the molybdenum element in the compound.

3. The method for determining the content of phosphorus in the phosphorus-containing feed by using energy dispersive X-ray fluorescence spectrometry as claimed in claim 2, wherein the method comprises the following steps: in step c, in order to avoid mixing water-soluble phosphorus in the filtrate, step b can be repeated in the filtrate until no precipitate is generated.

4. The method for determining the content of phosphorus in the phosphorus-containing feed by using energy dispersive X-ray fluorescence spectrometry as claimed in claim 2, wherein the method comprises the following steps: the phosphorus-containing feed contains Ca (H)₂PO₄)₂And a small amount of heavy metal elements;

in the preparation of the sample to be tested, the reaction after adding hydrochloric acid in step a:

Ca(H₂PO₄)₂+2HCl＝CaCl₂+2H₃PO₄

adding a quinomolybdic citraconic precipitator, and reacting to generate quinoline phosphomolybdate bright yellow precipitate:

H₃PO₄+3C₉H₇N+12Na₂MoO₄+24HCl＝(C₉H₇NH)₃PO₄·12MoO₃·H₂O↓

+24NaCl+11H₂O

5. the method for determining the content of phosphorus in the phosphorus-containing feed by using energy dispersive X-ray fluorescence analysis according to claim 2, wherein the method comprises the following steps: before tabletting a standard sample, carrying out moisture absorption treatment on phosphomolybdic acid analysis pure powder, placing phosphomolybdic acid powder in a dryer with allochroic silica gel for a week, and tabletting.

Technical Field

The invention relates to the technical field of analysis and detection, in particular to a method for analyzing the content of phosphorus element in phosphorus-containing feed by using energy dispersive X-ray fluorescence spectroscopy.

Background

From the current state of research at home and abroad, there are two main types of methods for measuring the content of elements in a substance: chemical analysis and instrumental analysis. Chemical analysis methods mainly comprise gravimetric methods, colorimetric methods, volumetric methods and the like, and have the advantages of higher measurement accuracy, more complicated operation steps, higher requirements on operators and longer analysis time. The instrumental analysis method has the advantages of high analysis speed, simplicity and convenience in operation and the like, and is more and more widely applied to the field of analysis and detection. The instrumental analysis method mainly comprises an X-ray fluorescence spectrometry, a near infrared spectrometry, an atomic absorption spectrometry and the like. Energy dispersive X-ray fluorescence (EDXRF) analysis is one instrument method used for qualitative, quantitative and physical characterization of the elemental composition and content of a substance. The method comprises the steps of directly enabling characteristic X-rays generated by exciting a sample by primary X-rays emitted by an X-ray tube and scattered rays of a primary spectrum to enter a detector to obtain an energy value of a target element, determining the type of the target element, comparing the type of the target element with a calibration curve, calculating the content of the target element in the sample to be detected, and completing quantitative analysis of the target element. Energy dispersive X-ray fluorescence analysis is widely applied to the fields of metallurgy, materials, environment, biomedicine and the like as a method for analyzing constant and trace elements. However, the fluorescence yield and excitation efficiency of light elements (Z ═ 11-20) are low, and the detection effect of the energy dispersion X-ray fluorescence analyzer is not ideal.

Disclosure of Invention

Aiming at the problems of low sensitivity and the like when the energy dispersion X-ray fluorescence spectrum is applied to analyzing light elements, the invention provides a novel method for effectively applying the energy dispersion X-ray fluorescence spectrum to analyzing phosphorus elements.

Step one, preparing a quinomolybdenyl citraconic ketone precipitator:

solution A-70 g of sodium molybdate is weighed in a 400ml beaker and dissolved by 100ml of water;

solution B-weigh 60g of citric acid into a 1000ml beaker, dissolve with 100ml of water, add 85ml of nitric acid (1+ 1);

solution C-adding solution A to solution B, and mixing;

solution D-mix 35ml nitric acid and 100ml water in a 400ml beaker, add 5ml quinoline;

solution E-add solution D to solution C and mix well. After standing overnight, the mixture was filtered through a glass crucible or filter paper, 280ml of acetone was added to the filtrate, and the mixture was diluted with water to 1000 ml.

The precipitant is stored in a polyethylene bottle and placed in a dark place to avoid light and heat.

Step two, preparing a sample to be detected:

A. about 0.8g of sample is weighed to an accuracy of 0.2mg, placed in a 100ml beaker, 10ml of hydrochloric acid and a small amount of water are added, the petri dish is covered and boiled for 10 min. After cooling, the mixture was transferred into a 250ml volumetric flask, diluted to the mark with water and shaken up. This solution was test solution a and was used for the determination of the total phosphorus content.

b. Transferring 20ml of the test solution A into a 250ml beaker by using a pipette, adding water until the total volume is about 100ml, adding 50ml of the quinomolybdenyl citranone solution, heating the mixture in a water bath until the temperature of the content in the beaker reaches 75 +/-5 ℃, keeping the temperature for 30s, cooling the mixture to room temperature, and stirring the mixture for 3 to 4 times in the cooling process.

c. The supernatant was filtered by suction filtration using a glass sand crucible having a constant weight at 180 ℃. + -. 5 ℃ or 250 ℃. + -. 10 ℃ in advance, the precipitate was washed 5 to 6 times by decantation, about 20ml of water was used each time, the precipitate was transferred to a glass sand crucible, and washing with water was continued 3 to 4 times (in order to avoid mixing of water-soluble phosphorus in the filtrate, the step b may be repeated in the filtrate until no precipitate was produced), at which time the precipitate in the solution was an acid-insoluble substance and quinoline phosphomolybdate precipitate.

d. And (3) placing the glass sand crucible in an electric heating drying oven, drying for 45min at 180 +/-5 ℃, taking out, placing in a dryer, cooling to room temperature, weighing, and recording as a first precipitate.

Step three, preparing a standard sample:

a. a3.6 g sample was weighed, dissolved in 200ml distilled water at 30 ℃ and kept for 10 min. The precipitate in the solution is now a precipitate of water insoluble impurities.

b. And standing the precipitate, washing, filtering and drying to obtain a precipitate which is marked as a second precipitate.

And step four, mixing the second precipitate and phosphomolybdic acid powder according to different content proportion gradients. A standard sample is prepared according to the powder tabletting method, and the content of molybdenum element in the sample is measured by an energy dispersion X-ray fluorescence spectrum analyzer. Drawing a calibration curve by taking the measured net area of the characteristic peak of the molybdenum element in each standard sample as a vertical coordinate and taking the percentage content of the added molybdenum element as a horizontal coordinate;

and fifthly, measuring the molybdenum element in the sample to be measured by the energy dispersion X-ray fluorescence spectrum analyzer again. And detecting to obtain the net area of the characteristic peak of the molybdenum element in the sample to be detected, and substituting the net area into the calibration curve to obtain the percentage content of the molybdenum element in the sample to be detected. And finally, calculating the percentage content of the phosphorus element in the feed-grade monocalcium phosphate according to the chemical quantity relationship between the phosphorus element and the molybdenum element in the compound.

Further optimization: the phosphorus-containing feed mainly contains Ca (H)₂PO₄)₂And a small amount of heavy metal elements.

In the preparation of the sample to be tested, the reaction after adding hydrochloric acid in step a:

Ca(H₂PO₄)₂+2HCl＝CaCl₂+2H₃PO₄

adding a quinomolybdic citraconic precipitator, and reacting to generate quinoline phosphomolybdate bright yellow precipitate:

H₃PO₄+3C₉H₇N+12Na₂MoO₄+24HCl＝(C₉H₇NH)₃PO₄·12MoO₃·H₂O↓+24NaCl+11H₂O

further optimization: before tabletting a standard sample, carrying out moisture absorption treatment on phosphomolybdic acid analysis pure powder, placing phosphomolybdic acid powder in a dryer with allochroic silica gel for a week, and tabletting.

The invention has the beneficial effects that:

the invention solves the problems of low fluorescence yield and excitation efficiency, low detected efficiency, poor accuracy of measurement results and the like when the energy dispersion X-ray fluorescence analysis method is applied to directly measure the phosphorus element. The method has the advantages of simple sample preparation operation, shortened detection time and high accuracy.

Drawings

FIG. 1 is a flow diagram of a pretreatment process for preparing a standard sample;

FIG. 2 is a flow chart of a pretreatment process for preparing a sample to be tested.

Detailed Description

The invention is described in detail below with reference to the drawings.

Preprocessing a sample to be detected, and preparing the sample to be detected as shown in figure 2:

the phosphorus-containing feed contains Ca (H)₂PO₄)₂And a small amount of heavy metal elements.

a. About 0.8g of sample is weighed to an accuracy of 0.2mg, placed in a 100ml beaker, 10ml of hydrochloric acid and a small amount of water are added, the petri dish is covered and boiled for 10 min. After cooling, the mixture was transferred into a 250ml volumetric flask, diluted to the mark with water and shaken up. This solution was test solution a and was used for the determination of the total phosphorus content. The main reaction formula is as follows:

Ca(H₂PO₄)₂+2HCl＝CaCl₂+2H₃PO₄

b. transferring 20ml of the test solution A into a 250ml beaker by using a pipette, adding water until the total volume is about 100ml, adding 50ml of the quinomolybdenyl citranone solution, heating the mixture in a water bath until the temperature of the content in the beaker reaches 75 +/-5 ℃, keeping the temperature for 30s, cooling the mixture to room temperature, and stirring the mixture for 3 to 4 times in the cooling process. The reaction is as follows:

H₃PO₄+3C₉H₇N+12Na₂MoO₄+24HCl＝(C₉H₇NH)₃PO₄·12MoO₃·H₂O↓+24NaCl+11H₂O

c. the supernatant was filtered by suction filtration using a glass sand crucible having a constant weight at 180 ℃. + -. 5 ℃ or 250 ℃. + -. 10 ℃ in advance, the precipitate was washed 5 to 6 times by decantation, about 20ml of water was used each time, the precipitate was transferred to a glass sand crucible, and washing with water was continued 3 to 4 times (in order to avoid mixing of water-soluble phosphorus in the filtrate, the step b may be repeated in the filtrate until no precipitate was produced), at which time the precipitate in the solution was an acid-insoluble substance and quinoline phosphomolybdate precipitate.

Placing the glass sand crucible in an electric heating drying oven, drying at 180 +/-5 ℃ for 45min, taking out, placing in a dryer, cooling to room temperature, weighing each group of precipitates on an electronic balance, and tabletting a part of the precipitates.

As shown in figure 1, in order to ensure that the chemical and physical properties of a standard sample and a sample to be tested have consistency, a phosphorus-containing feed sample is dissolved in distilled water, the quinoline phosphomolybdate solution is not dropwise added in the step b, the filtration is directly carried out, at the moment, acidic insoluble substances exist in precipitates, the impurity precipitates and phosphomolybdic acid powder are mixed into a plurality of components according to a certain gradient change proportion of molybdenum element content, the mass of each component is 0.3g, and the powder tabletting method is adopted to prepare the sample.

A plurality of parts of phosphorus-containing feed are taken and are subjected to chemical pretreatment according to the method. When the sample is boiled with hydrochloric acid, the soluble acid substance exists in the solution in the form of ions. In the step b of treatment, a quinomolybdenyl citraconic ketone precipitator is added, and orthophosphate radicals can react with the quinomolybdenyl citraconic ketone precipitator at the temperature of 75 +/-5 ℃ to generate a phosphomolybdic acid quinoline precipitate. After the filtering and drying in the step c, sequentially weighing the precipitated powder by using an electronic balance, and recording the mass as m_i. 0.5g of the resulting pellets was taken out and pressed into a tablet, which was then measured by an energy dispersive X-ray fluorescence spectrometer.

In order to verify the accuracy of the method, multiple samples are prepared and measured by the method, the measurement results are averaged and then compared with the X-ray fluorescence analysis by the fuse-link method, and the comparison results are shown in Table 1. As can be seen from Table 1, the measurement result of the method for the phosphorus content in the phosphorus-containing feed is basically consistent with that of the melting piece method, and the method can be reliably applied to the measurement of the phosphorus content in the phosphorus-containing feed.

Table 1 compares the energy dispersive X-ray fluorescence analysis measurements with the fuse-link X-ray fluorescence analysis results.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic methods defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the methods and novel features disclosed herein.