Method for testing available boron in soil by ultrasonic extraction plasma emission spectrometry

Abstract

The invention discloses a method for testing available boron in soil by ultrasonic extraction plasma emission spectrometry, which comprises the following steps: weighing 10.0 g of air-dried soil sample passing through a 60-mesh sieve, adding 20.0 mL of first-grade water (conforming to the GB / T 6682 regulation) into a 100 mL polyethylene centrifuge tube, slightly shaking the polyethylene centrifuge tube to disperse the soil, preferably performing ultrasonic extraction for 20-25 minutes under the conditions of 40 kHz and 70-80 DEG C, and performing ultrasonic extraction for 20-25 minutes under the conditions of 40 kHz and 70-80 DEG C; more preferably, after 22 minutes of extraction is finished, centrifuging for 5 minutes at the speed of 4000 r / min, collecting supernate, putting the supernate into a colorimetric tube to be detected, putting the supernate on a machine, selecting boron of 249.773 nm as an analysis spectral line, and detecting the soil available boron by an inductively coupled plasma emission spectrometry (ICP-OES) method, the mass concentration of the soil available boron is in a range of 0-2.0 mg / L and has a good linear relationship with spectral intensity, the correlation coefficient is 0.9999, the detection limit of the method is 0.003 mg / kg, and the lower measurement limit is 0.012 mg / kg. The relative standard deviation RSD is 2.17%-4.73% (n is equal to 8), the relative error RE is 0.54%-2.10% (n is equal to 8), and detection values are all in an uncertainty range.

Description

Technical Field

[0001] The present invention relates to the technical field of determination of available boron content in soil, and specifically relates to a method for testing available boron in soil by ultrasonic extraction inductively coupled plasma emission spectrometry. Background Art

[0002] Boron element in soil is an essential nutrient element for the normal growth and development of plants. The content of boron in soil varies greatly with different soil types. The total boron content is about 2 - 100 mg / kg. Most of the boron in soil is wrapped in mineral lattices or adsorbed on the surface of soil particles, and it is difficult for plants to directly absorb it, which is ineffective boron for plants. Only a very small amount of boron (water-soluble boron) exists in the soil solution in the form of boric acid or borate ions can be directly absorbed and utilized by plants, which belongs to available boron for plants. Lack of available boron in soil will cause crop yield reduction. Therefore, it is crucial to accurately test the available boron content in soil.

[0003] There are mainly two existing methods for detecting available boron in soil. The first method is ultrasonic heating extraction - methylimine-H - colorimetric method. In the experimental process, acidic potassium permanganate solution must be prepared immediately before use; the dosage of methylimine, the acidity of the color-developing buffer solution, and the ambient temperature during color development must be strictly controlled, and the experimental process is relatively cumbersome. The second method is ultrasonic heating extraction - curcumin - colorimetric method. The standing time of the filtrate is relatively short (less than 3 h). During batch experiments, the interval time is not easy to control; the temperature, speed, etc. during the evaporation process must be kept consistent, the experimental process is more cumbersome, and the color-developing conditions need to be strictly controlled; the stability and accuracy of repeated tests are not easy to control and vary greatly.

[0004] Therefore, it is necessary to provide a detection method for available boron content in soil with simple operation, high sensitivity and accuracy, good stability in repeated tests, high efficiency, and suitable for batch detection. Summary of the Invention

[0005] Aiming at the problems existing in the above-mentioned prior art, the present invention provides a method for testing available boron in soil by ultrasonic extraction inductively coupled plasma emission spectrometry. This method can realize the pretreatment of ultrasonic heating extraction of soil samples in batches, and has simple operation, high sensitivity and accuracy, good stability in repeated tests, high efficiency, and at the same time ensures accurate determination results.

[0006] In order to achieve the above purpose, the present invention is realized through the following technical solutions: A method for testing available boron in soil by ultrasonic extraction inductively coupled plasma emission spectrometry, including the pretreatment step of ultrasonic extraction of soil samples and the detection step of inductively coupled plasma emission spectrometry (ICP - OES) for available boron, where:

[0007] In the pretreatment step of ultrasonic heating extraction of soil samples: 10.00 g of air-dried soil samples passing through a 2 mm sieve pore size and 20.0 mL of primary water (meeting the requirements of GB / T 6682) are placed in a 100 mL centrifuge tube and mixed. The centrifuge tube sealing cap is tightened, and the soil samples are heated and extracted by ultrasonic waves, and the soil particles remain suspended during the extraction process. Then, centrifugation is carried out, and the supernatant is collected as the test solution, and the content of available boron is determined by inductively coupled plasma optical emission spectrometry (ICP-OES).

[0008] Preferably, in the pretreatment step of ultrasonic heating extraction of the above method: Weigh 10 g of the soil sample to be tested, place it in a 100 mL polyethylene centrifuge tube, add 20.0 mL of primary water (meeting the requirements of GB / T 6682), and gently shake the polyethylene centrifuge tube to disperse the soil.

[0009] Preferably, in the determination step of available boron of the above method: Use an inductively coupled plasma optical emission spectrometer (ICP-OES) to draw a working curve. Specifically, respectively pipette a certain volume of boron standard use solution into a 100 mL volumetric flask, and configure the standard curve concentrations to be: 0.00 mg / L, 0.05 mg / L, 0.10 mg / L, 0.20 mg / L, 0.40 mg / L, 0.50 mg / L, 0.80 mg / L, 1.00 mg / L, 1.50 mg / L, 2.00 mg / L. Inject the standard solutions with different mass concentrations into the inductively coupled plasma optical emission spectrometer in sequence, and detect and draw a standard curve with the mass concentration of the element to be measured as the abscissa and the signal value of the element to be measured as the ordinate.

[0010] Preferably, the available boron described in the above method is water-soluble available boron and does not include non-available boron components.

[0011] Preferably, the soil samples described in the above method include cultivated land soil, garden soil, forest and grassland soil, air-dried soil samples, and fresh soil samples.

[0012] Preferably, the preparation requirement of the soil sample in the above method: Prepare an air-dried sample passing through a 2 mm sieve pore size, and this sample is the soil sample to be tested.

[0013] Preferably, the ultrasonic extraction frequency is 40 kHz, the ultrasonic extraction temperature is 70 - 80 °C, and the ultrasonic extraction time is 20 - 25 min.

[0014] Preferably, the ultrasonic extraction time is preferably 22 min. After the extraction is completed, centrifuge at 4000 r / min for 5 min, and collect the supernatant into a colorimetric tube for testing and analysis on the machine.

[0015] Preferably, the containers for holding soil samples or liquids in the above method should be made of polyethylene, boron-free glass, or quartz.

[0016] In summary, the present invention provides a method for testing available boron in soil by ultrasonic extraction - inductively coupled plasma optical emission spectrometry. Compared with the prior art, the beneficial effects of the present invention are as follows:

[0017] (1) The present invention uses ultrasonic extraction - inductively coupled plasma optical emission spectrometry (ICP - OES) to detect available boron in soil. After mixing the soil sample to be tested with primary water (meeting the requirements of GB / T 6682), it is pretreated by heating in an ultrasonic device. Multiple samples can be processed simultaneously, enabling large - batch pretreatment. Moreover, the operation is simple. Combined with the subsequent inductively coupled plasma optical emission spectrometer (ICP - OES) equipped with an automatic sampling device, sampling and testing can be carried out without supervision, improving the work flow and practicality, and further enhancing the detection efficiency. On the other hand, combined with the subsequent inductively coupled plasma optical emission spectrometry, the method has a low detection limit, high precision and accuracy.

[0018] (2) Verified by three soil reference materials and three soil samples, the linear relationship between the mass concentration of available boron in soil and the spectral intensity is good in the range of 0 - 2.0 mg / L, with a correlation coefficient of 0.9999. The method detection limit is 0.003 mg / kg, the lower limit of quantification is 0.012 mg / kg, the relative standard deviation RSD is 2.17% - 4.73% (n = 8), and the relative error RE is 0.54% - 2.10% (n = 8). The measured values are all within the uncertainty range. This method has a low detection limit, high precision and accuracy, and strong operability, and is suitable for the detection of available boron in batch soil samples. Specific embodiments

[0019] The accuracy and precision of the method described in the present invention are specifically experimentally implemented below in combination with experimental conditions and experimental methods.

[0020] The present invention is a method for testing available boron in soil by ultrasonic extraction - inductively coupled plasma optical emission spectrometry. The experimental method is as follows: Place the soil sample to be tested in a 100 mL polyethylene centrifuge tube, add primary water (meeting the requirements of GB / T 6682), and gently shake the polyethylene centrifuge tube to disperse the soil. After heating and ultrasonic extraction, centrifuge and separate, collect the supernatant, and measure the available boron content on an inductively coupled plasma optical emission spectrometer (ICP - OES). Specifically, it includes experimental conditions such as instruments, reagents, pretreatment of soil samples, drawing of standard curves, detection limit, precision and accuracy verification. Among them:

[0021] (1) Experimental conditions

[0022] ① Instrument conditions

[0023] Inductively coupled plasma optical emission spectrometer (ICP-OES) (model iCAP-PRO-X, vertical torch tube, bidirectional observation, full-spectrum test, shortest exposure time 15 s, Thermo Fisher Scientific). Ultrasonic cleaner (model KQ-500B, operating frequency: 40 kHz, numerically controlled constant temperature: room temperature to 80 °C, numerically controlled timing: 1 - 480 min, Zhengzhou Baojing Electronic Technology Co., Ltd.). Desktop low-speed multi-tube centrifuge (model TD-5Z, maximum speed 4000 r / min, Sichuan Shuke Instrument Co., Ltd.). Electronic balance (model FA2004N, weighing range 0 - 200 g, reading accuracy 0.0001 g, Shanghai Precision Instrument Technology Co., Ltd.).

[0024] Table 1 Operating parameters of inductively coupled plasma optical emission spectrometer (ICP-OES)

[0025]

[0026] ② Reagents used in the experiment

[0027] Standard samples for analysis of soil available components: Huadu grey alluvial soil in Guangdong, Yingtan red soil in Jiangxi, Qing'an black soil in Heilongjiang, Luochuan loessial soil in Shaanxi, Tonghua brown soil in Jilin, Anyang alluvial soil in Henan, Jianyang purple soil in Sichuan, with numbers ASA-6b-CZ, ASA-5b-CZ, ASA-7a-CZ, ASA-9a-CZ, ASA-1b-CZ, ASA-2b-CZ, ASA-3b-CZ respectively, all developed by the Institute of Geophysical and Geochemical Exploration, Chinese Academy of Geological Sciences. Among them, ASA-6b-CZ, ASA-5b-CZ, ASA-1b-CZ are acidic soils, and ASA-7a-CZ, ASA-9a-CZ, ASA-2b-CZ, ASA-3b-CZ are alkaline soils. At the same time, three actual soil samples were selected, numbered TR1, TR2, and TR3 respectively.

[0028] Boron standard stock solution, 1000 mg / L, numbered 223049-2, National Nonferrous Metals and Electronic Materials Analysis and Testing Center and Guobiao (Beijing) Inspection and Certification Co., Ltd.

[0029] Magnesium sulfate, anhydrous sodium carbonate, analytical pure, Sinopharm Chemical Reagent Co., Ltd.

[0030] Sulfuric acid, nitric acid, extra pure, Sinopharm Chemical Reagent Co., Ltd.

[0031] ③ Pretreatment of soil samples

[0032] Weigh 10 g of the soil sample to be tested and place it in a 100 mL polyethylene centrifuge tube. Add 20.0 mL of primary water (meeting the requirements of GB / T 6682), and gently shake the polyethylene centrifuge tube to disperse the soil. Further, the ultrasonic extraction is preferably carried out at 40 kHz and 70 - 80 °C for 25 - 30 min, more preferably for 30 min. After the extraction, centrifuge at 4000 r / min for 5 min, and collect the supernatant in a colorimetric tube for testing on the machine.

[0033] (2) Standard curve drawing

[0034] Before analysis, rinse the system with nitric acid solution. The blank intensity value of the instrument decreases until it reaches the lowest value. At this time, the analysis signal of the instrument is stable, and the sample is analyzed under the same conditions as when establishing the calibration curve. During the sample detection process, if the boron element concentration in the test solution exceeds the maximum value of the calibration curve, it can be diluted with primary water (meeting the requirements of GB / T 6682), and after determining the additional amount of magnesium sulfate solution according to the dilution factor, re-detection is carried out.

[0035] Respectively pipette a certain volume of boron standard working solution into 100 mL volumetric flasks. Configure the standard curve concentrations as: 0.00 mg / L, 0.05 mg / L, 0.10 mg / L, 0.20 mg / L, 0.40 mg / L, 0.50 mg / L, 0.80 mg / L, 1.00 mg / L, 1.50 mg / L, 2.00 mg / L. Inject the standard solutions with different mass concentrations into the inductively coupled plasma emission spectrometer in sequence. Using the mass concentration of the element to be measured as the abscissa and the signal value of the element to be measured as the ordinate, draw the standard curve, referring to the available boron working curve (figure).

[0036]

[0037] (3) Method detection limit

[0038] According to the requirements for calculating the detection limit in the "Technical Guidelines for the Revision of Environmental Monitoring Analytical Method Standards" (HJ 168 - 2020), the detection limit calculation formula is determined as follows:

[0039] MDL = t(n - 1, 0.99) × S, t(n - 1, 0.99) = 3.143

[0040] Without weighing the sample, perform continuous 8 - time detections under the conditions specified in the above - mentioned optimal analysis method, calculate the standard deviation (S) of the 8 - time detections, calculate the detection limit as (3S), and the lower limit of detection is the detection limit * 4.

[0041] Table 2 Data table of method detection limit and lower limit of detection

[0042]

[0043] As shown in Table 2, after experimental tests, the detection limit of the sample measurement of the method is 0.003 mg / kg, and the lower limit of detection is 0.012, which is better than the requirements in the "Sample Detection and Quality Control Guidelines" of the Third National Soil Census: when the sample weighing is 10.00 g and the extractant is 20 mL of primary water (meeting the requirements of GB / T 6682), the method detection limit is: 0.003 mg / kg, and the lower limit of detection is: 0.012 mg / kg.

[0044] (4) Method precision, method trueness

[0045] As shown in Table 3, standard substances with different contents (ASA-1b-CZ, ASA-2b-CZ, ASA-3b-CZ) of low, medium and high levels were selected. According to the provisions of HJ 168-2020 "Technical Guidelines for the Formulation of Environmental Monitoring Analytical Method Standards", the average value, standard deviation (S) and relative standard deviation (RSD) of the detection results were calculated respectively.

[0046] Table 3 Data table of method precision

[0047]

[0048] (2) Optimization of ultrasonic temperature and ultrasonic time

[0049] (1) Optimization of ultrasonic temperature

[0050] The standard substances (ASA-6b-CZ, ASA-5b-CZ, ASA-9a-CZ, ASA-7a-CZ) were ultrasonically treated for 30 min at 40 kHz by an ultrasonic cleaner and leached at 30 °C, 40 °C, 50 °C, 60 °C, 70 °C, and 80 °C respectively. The results are shown in Table 4.

[0051] Table 4 Influence of ultrasonic temperature on detection results

[0052]

[0053] As can be seen from Table 4, when the ultrasonic leaching temperature is in the lower range (≤50 °C), the available boron in the sample cannot be fully leached; when the temperature is raised to 60 °C, the leaching rate of available boron in the soil increases significantly, reaching a high level of more than 90%; especially when the temperature further rises to 70 °C and above, the leaching of available boron reaches a complete state. At this time, the obtained measurement data is consistent with the standard method, and within the temperature range set in the experiment, the leaching rate of available boron will remain stable and will not fluctuate with the continuous increase of temperature. In view of this, to ensure the full leaching of available boron and the accuracy of measurement data, the appropriate range of ultrasonic leaching temperature can be determined as 70-80 °C.

[0054] (2) Optimization of ultrasonic time

[0055] The reference materials (ASA-6b-CZ, ASA-5b-CZ, ASA-9a-CZ, ASA-7a-CZ) were extracted by an ultrasonic cleaner under the conditions of an ultrasonic extraction frequency of 40 kHz and an ultrasonic extraction temperature of 75 °C, and were extracted for 5 min, 10 min, 15 min, 20 min, 25 min, and 30 min respectively. The results are shown in Table 5.

[0056] Table 5 Influence of ultrasonic time on the detection results

[0057]

[0058] It can be seen from Table 5 that when the extraction time is 5 - 15 min, the measurement results are on the low side, and the effective boron component in the sample has not been completely extracted; when the extraction time is 30 min, the measurement results are on the high side, and the non-effective state components of boron (chelated boron, acid-soluble boron, etc.) may also be extracted; when the extraction time is 20 - 25 min, the measured value is closest to the certified value. In view of this, to ensure the full leaching of effective boron and the accuracy of the measurement data, we can determine the appropriate range of ultrasonic extraction time as 20 - 25 min.

[0059] (3) Optimization of separation method

[0060] To determine the influence of the separation method on the content of available boron in soil, the reference materials ASA-6b-CZ, ASA-5b-CZ, ASA-9a-CZ, and ASA-7a-CZ were selected to explore the influence of two different separation methods, filtration separation and centrifugation separation, on the results.

[0061] Table 6 Influence of separation method on the detection results

[0062]

[0063] It can be seen from Table 6 that the detected values by centrifugation separation are basically consistent with the certified values and are within the error range. The detection results by the method of filtering with filter paper are on the low side or on the high side, and the result stability is relatively poor. At the same time, when choosing filtration separation and filtering a turbid liquid containing a large number of fine soil particles, these particles may block the filter paper, thereby significantly prolonging the filtration time. If the filter paper is replaced midway due to blockage, it is more likely to cause loss of effective boron in the components to be measured, resulting in a lower final detection result. Using a centrifuge to separate the samples to be measured can reduce the time required for the experiment and has higher efficiency. Therefore, it is better to select the centrifugation separation method.

[0064] (4) Influence of spectral line interference

[0065] Spectral interferences mainly include continuous background and spectral line overlap interferences. The spectral lines of Fe at 249.783 nm and B at 249.773 nm are close. To investigate the influence of Fe concentration on the test results, extraction was carried out according to the steps in 1.3. Standard substances ASA-6b-CZ, ASA-5b-CZ, ASA-9a-CZ, and ASA-7a-CZ were selected. Different concentrations of Fe standard solution were added to the prepared solution to be extracted, and the Fe concentrations were controlled to be 5 mg / L, 8 mg / L, 10 mg / L, 15 mg / L, and 20 mg / L respectively. The effective boron content was tested to investigate the influence of spectral line interference.

[0066] Table 7 Influence of Fe content (mg / L) in matrix medium on test results

[0067]

[0068] As can be seen from Table 7, when the Fe concentration in the extraction solution is 5 - 10 mg / L, the test values are close to the certificate values and within the error range of the standard substances, and the interference influence of Fe concentration is small; when the Fe concentration in the extraction solution is greater than 10 mg / L, the test results are on the low side. With the increase of Fe concentration, the interference influence increases and the test results decrease. Therefore, when the Fe concentration in the extraction solution is greater than 10 mg / L, it has a greater influence on the test results of effective boron. During the experiment, it is necessary to reduce or eliminate the interference influence of Fe. The experiment can consider replacing the less sensitive line of boron for re-detection or using chemical separation methods to reduce the Fe concentration to achieve the accurate purpose of the experiment.

[0069] The present invention will be further described in detail below with specific embodiments to better understand the content of the present invention, but the present invention is not limited to the following embodiments.

[0070] Example 1

[0071] Two fresh samples of cultivated soil from a certain place in Xuzhou, Jiangsu (avoiding fertilization points) were weighed respectively, and the sampling depth was 0 - 20 cm of the effective soil layer thickness. In a well-ventilated and sunless air-drying room, they were spread into a thin layer of 2 - 3 cm and naturally air-dried. 10.0 g of air-dried soil sample passing through 60 meshes was weighed and placed in a 100 mL polyethylene centrifuge tube. 20.0 mL of primary water (meeting the requirements of GB / T 6682) was added, and the polyethylene centrifuge tube was gently shaken to disperse the soil. Further, the ultrasonic extraction frequency was preferably 40 kHz, the ultrasonic extraction temperature was 70 - 80 °C, and the ultrasonic extraction time was 22 min. After the extraction was completed, it was centrifuged at 4000 r / min for 5 min, and the supernatant was collected in a colorimetric tube for testing on the machine. The spectral line of B at 249.773 nm was selected as the analysis spectral line, and the content of available boron in the soil was detected by inductively coupled plasma optical emission spectrometry (ICP-OES). The measured values were 0.22 mg / kg and 0.17 mg / kg respectively.

[0072] Using the curcumin colorimetric method for the determination of available boron content in soil as described in the "Technical Specifications for Soil Analysis" (Second Edition), Section 18.2, a comparative experiment was conducted with the present invention:

[0073] Weigh 10.00 g of air-dried soil sample passed through a 2.0 mm sieve into a 250 mL quartz Erlenmeyer flask, add 20.00 mL of water, connect a reflux condenser, boil gently over a low flame for 5 min, immediately remove the heat source, continue reflux condensation for 5 min, remove the quartz Erlenmeyer flask, add 2 drops of 100 g / L magnesium sulfate solution, shake well and filter immediately. Pipette 1.00 mL of the filtrate into a 50 mL evaporating dish, add 4.00 mL of curcumin-oxalic acid solution, evaporate to dryness in a constant temperature water bath at (55 ± 3) °C, continue baking for 15 min, remove the evaporating dish and cool to room temperature, add 20.00 mL of 95% ethanol, stir with a plastic rod until the residue is completely dissolved, filter through a medium-speed filter paper, and use 95% ethanol as the reference solution. Measure the absorbance at a wavelength of 550 nm on a spectrophotometer using a 1 cm light path cuvette. The detected contents are 0.23 mg / kg and 0.17 mg / kg respectively.

[0074] Example 2

[0075] Weigh 2 fresh samples of cultivated soil from a certain place in Jingmen, Hubei (avoiding fertilization points) respectively, and the sampling depth is 0 - 20 cm of the effective soil layer thickness. In a well-ventilated and sunless air-drying room, spread them into a thin layer of 2 - 3 cm and air-dry naturally. Weigh 10.0 g of the air-dried soil sample passed through a 60-mesh sieve into a 100 mL polyethylene centrifuge tube, add 20.0 mL of primary water (meeting the requirements of GB / T 6682), gently shake the polyethylene centrifuge tube to disperse the soil. Further, the ultrasonic extraction frequency is preferably 40 kHz, the ultrasonic extraction temperature is 70 - 80 °C, the ultrasonic extraction time is 22 min. After the extraction is completed, centrifuge at 4000 r / min for 5 min, collect the supernatant in a colorimetric tube for testing on the machine, select 249.773 nm of boron as the analysis spectral line, and use inductively coupled plasma optical emission spectrometry (ICP-OES) method to detect the available boron content in the soil. The measured values are 0.57 mg / kg and 0.66 mg / kg respectively.

[0076] Similarly, using the curcumin colorimetric method for the comparative experiment, the measured results of the available boron content are 0.55 mg / kg and 0.63 mg / kg respectively.

[0077] Example 3

[0078] Two fresh samples of cultivated land soil from a certain place in Jiaxing, Zhejiang (avoiding fertilization points) were weighed separately, and the sampling depth was 0 - 20 cm of the effective soil layer thickness. In a well-ventilated and sunless air-drying room, they were spread into a thin layer of 2 - 3 cm and naturally air-dried. Weigh 10.0 g of air-dried soil sample passing through 60 mesh, put it into a 100 mL polyethylene centrifuge tube, add 20.0 mL of primary water (meeting the requirements of GB / T 6682), and gently shake the polyethylene centrifuge tube to disperse the soil. Further, the preferred ultrasonic extraction frequency is 40 kHz, the ultrasonic extraction temperature is 70 - 80 °C. After 22 min of ultrasonic extraction, centrifuge at 4000 r / min for 5 min, collect the supernatant into a colorimetric tube for determination by machine. Select 249.773 nm of boron as the analysis spectral line, and use inductively coupled plasma optical emission spectrometry (ICP-OES) method to detect the content of available boron in the soil. The measured values are 0.48 mg / kg and 0.36 mg / kg respectively.

[0079] Similarly, a comparative experiment was conducted using the curcumin colorimetric method, and the measured results of the available boron content were 0.47 mg / kg and 0.38 mg / kg respectively.

[0080] Referring to the requirements for the allowable absolute deviation of parallel determination results in the specification of the curcumin colorimetric method for determining available boron in soil in Section 18.2 of the "Technical Specifications for Soil Analysis" (Second Edition):

[0081] Table 7 Allowable Deviation of Parallel Determination Results of Available Boron by Curcumin Colorimetric Method

[0082]

[0083] The results of the above Examples 1 - 3 show that, compared with the curcumin colorimetric method, the relative deviation allowed for the results of the ultrasonic heating extraction - inductively coupled plasma optical emission spectrometry (ICP-OES) method provided by the present invention for determining the content of available boron in soil meets the requirements of Table 7. It can be seen that when the ultrasonic heating extraction - inductively coupled plasma optical emission spectrometry (ICP-OES) method is used to determine the content of available boron in soil, it not only has the advantages of high accuracy and good repeatability, but also shows strong applicability and consistency in dealing with complex soil samples. This method uses automated instrument equipment for determination, which can greatly improve work efficiency and reduce human errors, thus meeting the need for rapid determination of a large number of samples.

[0084] The examples in the present invention are only used to illustrate the present invention and do not constitute a limitation to the scope of the claims. Other substantially equivalent alternatives that can be thought of by those skilled in the art are all within the protection scope of the present invention.

Claims

1. A method for testing effective boron in soil by ultrasonic extraction plasma emission spectrometry, characterized in that: The method comprises a soil sample ultrasonic heating leaching pretreatment step and an effective boron detection step using an inductively coupled plasma optical emission spectroscopy (ICP-OES) method, wherein: In the pretreatment step of ultrasonic heating extraction of soil samples: 10.00 g of air-dried soil sample passed through a 2 mm aperture sieve and 20.0 mL of first-grade water (in compliance with GB / T 6682) are placed in a 100 mL centrifuge tube and mixed, the centrifuge tube sealing cover is tightened, the soil sample is ultrasonically heated and extracted, and the soil particles are kept in a suspended state during the extraction process, centrifuged, and the supernatant is collected as the test solution, and the content of effective boron is determined by inductively coupled plasma optical emission spectroscopy (ICP-OES).

2. The method for testing effective boron in soil by ultrasonic extraction plasma emission spectrometry according to claim 1, characterized in that: The pre-treatment step of the ultrasonic heating extraction of the above method is as follows: weigh 10 g of the soil sample to be tested, put it in a 100 mL polyethylene centrifuge tube, add 20.0 mL of first-grade water (in compliance with GB / T 6682), and gently shake the polyethylene centrifuge tube to disperse the soil.

3. The method for testing effective boron in soil by ultrasonic extraction plasma emission spectrometry according to claim 2, characterized in that: In the determination step of effective boron in the above method: a working curve is drawn using an inductively coupled plasma optical emission spectrometer (ICP-OES). Specifically, a certain volume of a standard boron solution is taken into a 100 mL volumetric flask, and the standard curve concentration is configured as follows: 0.00 mg / L, 0.05 mg / L, 0.10 mg / L, 0.20 mg / L, 0.40 mg / L, 0.50 mg / L, 0.80 mg / L, 1.00 mg / L, 1.50 mg / L, 2.00 mg / L. Standard solutions of different mass concentrations are sequentially injected into the inductively coupled plasma optical emission spectrometer, and the mass concentration of the element to be measured is used as the abscissa, and the signal value of the element to be measured is used as the ordinate to draw the standard curve.

4. The method for testing effective boron in soil by ultrasonic extraction plasma emission spectrometry according to claim 2, characterized in that: The effective boron described in the above method is water-soluble effective boron, excluding non-effective component boron.

5. The method for testing effective boron in soil by ultrasonic extraction plasma emission spectrometry according to claim 2, characterized in that: The soil samples described in the above method include cultivated land soil, garden soil, forest and grassland soil, air-dried soil samples, and fresh soil samples.

6. The method for testing effective boron in soil by ultrasonic extraction plasma emission spectrometry according to claim 2, characterized in that: The soil sample preparation requirements in the above method are: prepare an air-dried sample that passes through a 2 mm aperture sieve, and the sample is the soil sample to be tested.

7. The method for testing effective boron in soil by ultrasonic extraction plasma emission spectrometry according to claim 2, characterized in that: The ultrasonic extraction frequency is 40 kHz, the ultrasonic extraction temperature is 70-80° C., and the ultrasonic extraction time is 20-25 min.

8. The method for testing effective boron in soil by ultrasonic extraction plasma emission spectrometry according to claim 7, characterized in that: The ultrasonic extraction time is preferably 22 minutes. After the extraction, the mixture is centrifuged at 4000 r / min for 5 minutes, and the supernatant is collected in a colorimetric tube to be tested on the instrument.

9. The method for testing effective boron in soil by ultrasonic extraction plasma emission spectrometry according to claim 8, characterized in that: In the above method, the container for holding soil samples or liquids should be made of polyethylene, boron-free glass or quartz.

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