Digestion device and digestion method for measuring content of slow-acting potassium in soil
Through the slow-acting potassium digestion tube and programmable logic controller combined with the gas flow rate measurement probe, the problem of large sample volume and difficult to judge in the slow-acting potassium determination of soil slow-acting potassium is solved, and the batch rapid and accurate determination of soil slow-acting potassium is achieved, protecting the health of experimental personnel and meeting the requirements of high efficiency, accuracy and green environmental protection.
Patent Information
- Application Number
- CN202510827008.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-19
- Publication Date
- 2025-08-15
AI Technical Summary
In the determination of soil slow potassium content, the problem of excessive sample volume, difficult to judge the phenomenon of false boiling, inaccurate digestion time, great harm to the health of the experimenter and strong dependence on experience, it is difficult to achieve efficient, accurate and green and environmentally friendly determination.
The slow-acting potassium digestion tube and programmable logic controller are used to combine the gas flow rate measurement probe to judge the sample boiling state by real-time monitoring of the gas flow rate difference, automatically control the digestion time, and combine it with the buzzer to prompt the digestion to be completed, reducing the harm to the experimenter and the sample volume.
It realizes batch, rapid and accurate determination of soil slow-effect potassium content, reduces the frequency of sample measurement rework, reduces the amount of reagents, protects the health of experimental personnel, and meets the requirements of high efficiency, accuracy and green environmental protection.
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Figure CN120489708A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of soil testing and analysis, and relates to a digestion device and a digestion method, in particular to a digestion device and a digestion method for measuring the slow-release potassium content in soil. Background Art
[0002] Potassium is an essential nutrient for plant growth and development. It is one of the three elements of fertilizer (nitrogen, phosphorus, and potassium). Its content in plants is second only to nitrogen. It plays a significant role in increasing crop yields and improving quality, and plays an irreplaceable role in agricultural production. Potassium in the soil coexists in three forms: fast-acting potassium, slow-acting potassium, and insoluble potassium. Fast-acting potassium can be directly absorbed by plants, and slow-acting potassium serves as a reserve of fast-acting potassium. When fast-acting potassium in the soil decreases due to crop absorption, slow-acting potassium will be released to make up for the loss of fast-acting potassium. A dynamic equilibrium exists between the two. Slow-acting potassium in the soil is mainly present between the layers of phyllosilicate minerals. It can effectively supplement the consumption of fast-acting potassium and is an important indicator for assessing the soil's ability to continuously supply potassium. The dynamic balance between slow-acting potassium and fast-acting potassium directly affects the continuous absorption efficiency of crops for potassium. Especially in long-term farming, its content has important guiding significance for scientific fertilization and soil potassium reservoir management.
[0003] The current standard in my country, "Determination of soil fast-acting potassium and slow-acting potassium content" (NY / T 889-2004), uses 1.0 mol·L -1The nitric acid boiling method is used to determine the slow-release potassium. Its principle is to selectively extract the water-soluble and exchangeable potassium from secondary minerals in the soil (such as decomposition intermediates of hydrous mica and potassium fixed in the clay mineral lattice) using hot nitric acid. The total potassium content is determined using a flame photometer or inductively coupled plasma emission spectrometer, and the fast-release potassium content is deducted to finally obtain the slow-release potassium value. This method can effectively determine the content of slow-release potassium, but there are significant deficiencies in its operation. First, the sampling volume (2.50 g) is too large, which wastes samples and reagents. Second, carbonates are present in most soil samples, and the CO2 bubbles generated by the reaction during digestion will cause false boiling during the slow-release potassium determination process, making it difficult to accurately judge the boiling time and accurate timing. Third, for batch determination of samples, due to the large number of samples, it is impossible to take into account the boiling and digestion times of all samples. The digestion time can only be controlled according to the boiling time of most samples, which will cause some samples to have digestion timeouts and some samples to have insufficient digestion time, which will have a great impact on the determination results. Fourth, digestion needs to be carried out under high temperature conditions, and the digestion reagent contains substances such as acid. The experimenter needs to observe the boiling phenomenon closely, which will cause the risk of inhaling overflowing boiling gas, which will harm the health of the experimental testers, especially for those who are responsible for this determination for a long time, which will cause cumulative harm. Fifth, the judgment of the boiling phenomenon of slow-release potassium digestion is highly dependent on the experience of the analytical testers. The existence of the above problems does not meet the requirements of high efficiency, high accuracy and green environmental protection in experimental determination. Especially in large-scale production, it will cause a large number of sample measurements to be reworked, wasting manpower and material resources and causing certain harm to the experimenters. Therefore, there is an urgent need for a new method to quickly, simply and batch determine the content of slow-release potassium in soil. Summary of the Invention
[0004] In order to solve the above technical problems existing in the background technology, the present invention provides a digestion device and a digestion method for measuring the content of slow-release potassium in soil with high detection accuracy and high detection efficiency.
[0005] To achieve the above object, the present invention adopts the following technical solutions:
[0006] A slow-acting potassium digestion tube is characterized in that: the slow-acting potassium digestion tube comprises a test tube, a test tube plug and a gas flow rate measurement probe; the test tube plug is inserted into the test tube; the gas flow rate measurement probe is placed in the test tube plug; and the test tube is connected to the gas flow rate measurement probe through the test tube plug.
[0007] The test tube plug is a special-shaped tube, and the gas flow rate measuring probe extends from the outside of the test tube plug into the middle of the test tube plug.
[0008] The above-mentioned test tube plug includes a plug body, a probe accommodating cavity and an exhaust pipe which are connected in sequence from front to back; the plug body, the probe accommodating cavity and the exhaust pipe are N-shaped as a whole; the plug body is inserted into the test tube and is connected to the test tube; the gas flow rate measuring probe extends from the outside of the test tube plug into the probe accommodating cavity.
[0009] The probe accommodating cavity is shaped like a hot air balloon as a whole; the narrow mouth of the probe accommodating cavity is connected to the plug body; the sphere of the probe accommodating cavity is connected to the exhaust pipe; the gas flow rate measuring probe extends from the outside of the test tube plug into the probe accommodating cavity.
[0010] The inner diameter of the narrow opening of the probe accommodating cavity is smaller than the inner diameter of the test tube; and the inner diameter of the sphere of the probe accommodating cavity is not larger than the inner diameter of the test tube.
[0011] The above-mentioned test tube mouth and test tube plug mouth are both frosted mouths; preferably, the measurement accuracy of the gas flow rate measurement probe is 0-30m / s, and the applicable temperature range is 20-140℃.
[0012] A digestion device for measuring the slow-release potassium content in soil, characterized in that: the digestion device for measuring the slow-release potassium content in soil comprises a programmable logic controller, a display, a buzzer, and the slow-release potassium digestion tube as described above; there are at least two slow-release potassium digestion tubes; the display and the buzzer are both connected to the programmable logic controller; and the gas flow rate measurement probes in the slow-release potassium digestion tubes are both connected to the programmable logic controller via signal lines.
[0013] The above-mentioned digestion device for measuring the slow-release potassium content in soil also includes a working box; a signal line through-hole is opened on the working box; the programmable logic controller is placed inside the working box; the signal line passes through the signal line through-hole; the display and the buzzer are both arranged on the working box body.
[0014] The working box further comprises a flow rate display window, a flow rate switch, a time setting button and a power cord; the display is embedded in the flow rate display window; the flow rate switch, the time setting button and the power cord are all connected to a programmable logic controller.
[0015] A digestion method based on the digestion device for measuring the slow-release potassium content in soil as described above, characterized in that the digestion method comprises the following steps:
[0016] 1) Prepare an oil bath heating device; the temperature of the oil bath heating device is 110°C-130°C; preferably, the heating medium used by the oil bath heating device is dimethyl silicone oil or paraffin oil;
[0017] 2) preparing slow-acting potassium digestion tubes as described above; at the same time, dividing the slow-acting potassium digestion tubes into test tubes for detection and test tubes for blank controls; preferably, there are multiple test tubes;
[0018] 3) The soil sample to be tested was placed in a test tube. Nitric acid was added to the test tube at a ratio of 10:1 between the volume (mL) of nitric acid and the mass (g) of the soil sample to be tested. The test tube stopper described above was inserted into the test tube. A volume of nitric acid equal to that in the test tube was added to a blank control test tube. The test tube stopper described above was inserted into the test tube. The concentration of the nitric acid was 1 mol / L.
[0019] 4) Place the test tube and the blank control test tube in the oil bath heating device prepared in step 1) at the same time, and use the gas flow rate measurement probe to collect the gas flow rate V of the test tube in real time. 检测 and the gas flow rate V of the blank control test tube 对照 ;
[0020] 5) The gas flow rate V of the test tube is controlled by the programmable logic controller. 检测 and the gas flow rate V of the blank control test tube 对照 The difference is judged, when |V 检测 -V 对照 | / V 对照 When the concentration is ≤10%, the digestion start time is recorded by the programmable logic controller. After the digestion experiment is completed, the programmable logic controller controls the buzzer to work and removes the test tube from the oil bath heating device;
[0021] 6) Determine the concentration of slow-acting potassium in the test tube using conventional techniques.
[0022] Advantages of the present invention:
[0023] The present invention provides a digestion device and a digestion method for measuring the content of slow-release potassium in soil. The digestion device for measuring the content of slow-release potassium in soil is based on the slow-release potassium digestion tube uniquely designed by the present invention, and thus forms a device that can effectively improve detection accuracy and detection efficiency. The present invention can effectively solve the false boiling phenomenon and the actual boiling time judgment problem in the slow-release potassium digestion process, strictly control the digestion time of each sample, solve the defect of the traditional method that a batch of samples adopts the same digestion time, reduce the problem of high frequency of rework of sample measurement, avoid the damage caused by close observation of boiling phenomenon by observers, reduce the amount of experimental samples and the amount of digestion reagents, help to achieve green environmental protection requirements, and rely less on the experience of analysis and measurement personnel. The present invention can realize batch, rapid and accurate determination of slow-release potassium in soil. BRIEF DESCRIPTION OF THE DRAWINGS
[0024] Figure 1 It is a schematic structural diagram of the digestion test tube provided by the present invention;
[0025] Figure 2 Schematic diagram of the structure of the pipe plug used in the present invention;
[0026] Figure 3 This is a schematic diagram of the overall structure of the slow-release potassium digestion device provided by the present invention;
[0027] Figure 4 This is a diagram of the internal working principle of the working box used in the present invention;
[0028] in:
[0029] 1-test tube; 2-test tube plug; 21-plug body; 22-probe accommodating chamber; 23-exhaust pipe; 3-gas flow rate measurement probe; 4-working box; 41-signal line through-hole; 42-flow rate display window; 43-flow rate switch; 44-time setting button; 45-power cord; 5-programmable logic controller; 6-display; 7-buzzer. DETAILED DESCRIPTION
[0030] See also Figure 1 as well as Figure 2 The present invention provides a slow-release potassium digestion tube, comprising a test tube 1, a test tube plug 2, and a gas flow rate measurement probe 3. The test tube plug 2 is inserted into the test tube 1; the gas flow rate measurement probe 3 is placed in the test tube plug 2, and the test tube 1 is connected to the gas flow rate measurement probe 3 through the test tube plug 2. For example, the inner diameter of the test tube 1 is 1.4 cm to 1.8 cm, and the height is 25 cm to 28 cm.
[0031] See also Figure 2 The test tube plug 2 used in the present invention is a special-shaped tube, and the gas flow rate measurement probe 3 extends from the outside of the test tube plug 2 into the middle of the test tube plug 2. Exemplarily, the test tube plug 2 includes a plug body 21, a probe accommodating cavity 22, and an exhaust pipe 23, which are connected in sequence from front to back; the plug body 21, the probe accommodating cavity 22, and the exhaust pipe 23 are generally N-shaped; the plug body 21 is inserted into the test tube 1; the gas flow rate measurement probe 3 extends from the outside of the test tube plug 2 into the probe accommodating cavity 22. Exemplarily, the probe accommodating cavity 22 is generally shaped like a hot air balloon; the narrow opening of the probe accommodating cavity 22 is connected to the plug body 21; the sphere of the probe accommodating cavity 22 is connected to the exhaust pipe 23; the gas flow rate measurement probe 3 extends from the outside of the test tube plug 2 into the probe accommodating cavity 22. The inner diameter of the narrow opening of the probe accommodating cavity 22 is smaller than the inner diameter of the test tube 1, and exemplarily, the inner diameter can be 0.8 cm to 1.2 cm; the inner diameter of the sphere of the probe accommodating cavity 22 is no larger than the inner diameter of the test tube 1. The plug 21 is inserted into the test tube 1 to ensure the sealing of the slow-release potassium digestion test tube and the slow-release potassium digestion gas flow rate measuring device;
[0032] See also Figure 1 as well as Figure 2The mouth of the test tube 1 and the mouth of the test tube plug 2 used in the present invention are both frosted. Preferably, the measurement accuracy of the gas flow rate measuring probe 3 is 0-30m / s, and the applicable temperature range is 20-140℃.
[0033] See also Figure 3 as well as Figure 4 While providing a slow-release potassium digestion tube, the present invention also provides a digestion device for measuring the slow-release potassium content in soil based on the slow-release potassium digestion tube, comprising a programmable logic controller 5, a display 6, a buzzer 7, and the slow-release potassium digestion tube as described above, wherein there are at least two slow-release potassium digestion tubes, and control tests or batch tests can be carried out; the display 6 and the buzzer 7 are both connected to the programmable logic controller 5; the gas flow rate measurement probes 3 in the slow-release potassium digestion tube are both connected to the programmable logic controller 5 via signal lines.
[0034] See also Figure 3 Exemplarily, the digestion device for measuring the slow-release potassium content in soil also includes a working box 4; a signal line through-hole 41 is opened on the working box 4; a programmable logic controller 5 is placed inside the working box 4; the signal line passes through the signal line through-hole 41; the display 6 and the buzzer 7 are both arranged on the working box 4.
[0035] The working box 4 also includes a flow rate display window 42, a flow rate switch 43, a time setting button 44 and a power cord 45; the display 6 is embedded in the flow rate display window 42; the flow rate switch 43, the time setting button 44 and the power cord 45 are all connected to the programmable logic controller 5.
[0036] The present invention provides a digestion method of a digestion device for measuring the content of slow-release potassium in soil, the digestion method comprising the following steps:
[0037] 1) Prepare an oil bath heating device; the temperature of the oil bath heating device is 110°C-130°C. After the temperature stabilizes, the digestion time can be set on the programmable logic controller; illustratively, the heating medium used in the oil bath heating device is dimethyl silicone oil or paraffin oil;
[0038] 2) preparing slow-acting potassium digestion tubes; at the same time, dividing the slow-acting potassium digestion tubes into test tubes and blank control test tubes; preferably, there are multiple test tubes, and the parameters of the test tubes in the same batch should be consistent;
[0039] 3) Place the soil sample to be tested in a test tube, add nitric acid to the test tube with a volume (mL) to soil mass (g) ratio of 10:1, and Figure 2 Insert the stopper of the test tube into the test tube; add nitric acid of the same volume as the test tube to the blank control test tube, and at the same time Figure 2The test tube stopper is inserted into the test tube for detection; nitric acid is the extraction solvent for slow-release potassium, and its concentration is 1 mol / L; illustratively, the weight of the soil sample to be tested can be 1.00 g-2.50 g.
[0040] 4) Place the test tube for detection and the blank control test tube in the oil bath heating device prepared in step 1 at the same time, and use the gas flow rate measuring probe 3 to collect the gas flow rate V of the test tube in real time. 检测 and the gas flow rate V of the blank control test tube 对照 ; For example, the test tubes for detection and the test tubes for blank controls can be placed in a wire cage at the same time, and the wire cage can be quickly placed in an oil bath heating device.
[0041] 5) The gas flow rate V of the test tube is controlled by the programmable logic controller 5. 检测 and the gas flow rate V of the blank control test tube 对照 The difference is judged, when |V 检测 -V 对照 | / V 对照 When the temperature is less than or equal to 10%, the digestion start time is recorded by the programmable logic controller 5. After the digestion experiment is completed, the programmable logic controller 5 controls the buzzer 7 to work and removes the test tube from the oil bath heating device.
[0042] 6) Determine the concentration of slow-acting potassium in the test tube according to conventional technical means. Exemplary, during the determination, quickly remove the digestion sample test tube, dry filter while hot in a 100mL volumetric flask, and rinse the digestion test tube with 0.10mol / L nitric acid 4 times, 15mL each time; After all samples are digested, the volumetric flask is fixed to 100mL to determine the concentration of slow-acting potassium. Finally, an inductively coupled plasma emission spectrometer or a flame photometer can be used to determine the fast-acting potassium.
[0043] The digestion method provided by the present invention is based on the principle that a gas flow rate measuring probe is connected to a programmable logic controller for measuring the gas flow rate. The programmable logic controller determines the boiling state of the sample based on the difference in information between a blank sample and a sample to be tested. When the sample reaches the boiling state, timing begins. The corresponding sample display window displays the digestion flow rate and time status. When the predetermined time is reached, the window displays the sample number and emits a buzzer, thereby achieving precise control of the digestion process.
[0044] The technical solution provided by the present invention is described in detail below with reference to specific embodiments:
[0045] Example 1
[0046] (1) 1 mol / L nitric acid was used as the extraction solvent for slow-release potassium, and dimethyl silicone oil was used as the oil bath heating source;
[0047] (2) Adjust the heating temperature to 130°C. After the temperature stabilizes, plug in the programmable logic controller and set the digestion time to 10 minutes.
[0048] (3) Weigh 2.5 g of soil standard materials (ASA-1b, ASA-5b, and ASA-16) and place them in slow-release potassium digestion test tubes. Add 25.0 mL of 1 mol / L nitric acid. Prepare a test tube with only 25.0 mL of 1 mol / L nitric acid (blank sample). Place all digestion test tubes in a wire cage, insert a slow-release potassium digestion gas flow rate measurement probe, and place the wire cage in the prepared oil bath.
[0049] (4) Turn on the programmable logic controller switch, turn on the probe switch corresponding to the sample, and observe the programmable logic controller information display window, which displays the gas flow rate status in the test tube;
[0050] (5) When the difference between the gas flow rate measurement value and the reference sample is within ±10%, the programmable logic controller automatically starts recording the digestion time. When the digestion time reaches the set time, the programmable logic controller emits a buzzer, and the corresponding display window flashes the window number. The set time window displays the number of samples that have been digested, which means that the sample with the corresponding number has completed digestion;
[0051] (6) Quickly remove the digestion sample tube, dry filter it while hot into a 100 mL volumetric flask, and rinse the digestion tube with 0.1 mol / L nitric acid four times, 15 mL each time;
[0052] (7) After all samples have been digested, the volumetric flask is adjusted to 100 mL to determine the concentration of slow-release potassium.
[0053] (8) Determination method: Flame photometer method was used for determination. The results are shown in Table 1.
[0054] Example 2
[0055] (1) 1 mol / L nitric acid was used as the extraction solvent for slow-release potassium, and dimethyl silicone oil was used as the oil bath heating source;
[0056] (2) Adjust the heating temperature to 120°C. After the temperature stabilizes, plug in the programmable logic controller and set the digestion time to 14 minutes.
[0057] (3) Weigh 2.5 g of soil standard materials (ASA-1b, ASA-5b, and ASA-16) and place them in slow-release potassium digestion test tubes. Add 25.0 mL of 1 mol / L nitric acid. Prepare a test tube with only 25.0 mL of 1 mol / L nitric acid (blank sample). Place all digestion test tubes in a wire cage, insert a slow-release potassium digestion gas flow rate measurement probe, and place the wire cage in the prepared oil bath.
[0058] (4) Turn on the programmable logic controller switch, turn on the probe switch corresponding to the sample, and observe the programmable logic controller information display window, which displays the gas flow rate status in the test tube;
[0059] (5) When the difference between the gas flow rate measurement value and the reference sample is within ±10%, the programmable logic controller automatically starts recording the digestion time. When the digestion time reaches the set time, the programmable logic controller emits a buzzer, and the corresponding display window flashes the window number. The set time window displays the number of samples that have been digested, which means that the sample with the corresponding number has completed digestion;
[0060] (6) Quickly remove the digestion sample tube, dry filter it while hot into a 100 mL volumetric flask, and rinse the digestion tube with 0.1 mol / L nitric acid four times, 15 mL each time;
[0061] (7) After all samples have been digested, the volumetric flask is filled to 100 mL to determine the concentration of slow-release potassium;
[0062] (8) Determination method: Flame photometer method was used for determination. The results are shown in Table 1.
[0063] Example 3
[0064] (1) 1 mol / L nitric acid was used as the extraction solvent for slow-release potassium, and dimethyl silicone oil was used as the oil bath heating source;
[0065] (2) Adjust the heating temperature to 110°C. After the temperature stabilizes, plug in the programmable logic controller and set the digestion time to 23 minutes.
[0066] (3) Weigh 2.5 g of soil standard materials (ASA-1b, ASA-5b, and ASA-16) and place them in slow-release potassium digestion test tubes. Add 25.0 mL of 1 mol / L nitric acid. Prepare a test tube with only 25.0 mL of 1 mol / L nitric acid (blank sample). Place all digestion test tubes in a wire cage, insert a slow-release potassium digestion gas flow rate measurement probe, and place the wire cage in the prepared oil bath.
[0067] (4) Turn on the programmable logic controller switch, turn on the probe switch corresponding to the sample, and observe the programmable logic controller information display window, which displays the gas flow rate status in the test tube;
[0068] (5) When the difference between the gas flow rate measurement value and the reference sample is within ±10%, the programmable logic controller automatically starts recording the digestion time. When the digestion time reaches the set time, the programmable logic controller emits a buzzer, and the corresponding display window flashes the window number. The set time window displays the number of samples that have been digested, which means that the sample with the corresponding number has completed digestion;
[0069] (6) Quickly remove the digestion sample tube, dry filter it while hot into a 100 mL volumetric flask, and rinse the digestion tube with 0.1 mol / L nitric acid four times, 15 mL each time;
[0070] (7) After all samples have been digested, the volumetric flask is filled to 100 mL to determine the concentration of slow-release potassium;
[0071] (8) Determination method: Flame photometer method was used for determination. The results are shown in Table 1.
[0072] Example 4
[0073] (1) 1 mol / L nitric acid was used as the extraction solvent for slow-release potassium, and dimethyl silicone oil was used as the oil bath heating source;
[0074] (2) Adjust the heating temperature to 130°C. After the temperature stabilizes, plug in the programmable logic controller and set the digestion time to 10 minutes.
[0075] (3) Weigh 1.5 g of soil standard materials (ASA-1b, ASA-5b, and ASA-16) and place them in slow-release potassium digestion tubes. Add 15.0 mL of 1 mol / L nitric acid. Prepare a test tube with only 15.0 mL of 1 mol / L nitric acid (blank sample). Place all digestion tubes in a wire cage, insert a slow-release potassium digestion gas flow rate measurement probe, and place the wire cage in the prepared oil bath.
[0076] (4) Turn on the programmable logic controller switch, turn on the probe switch corresponding to the sample, and observe the programmable logic controller information display window, which displays the gas flow rate status in the test tube;
[0077] (5) When the difference between the gas flow rate measurement value and the reference sample is within ±10%, the programmable logic controller automatically starts recording the digestion time. When the digestion time reaches the set time, the programmable logic controller emits a buzzer, and the corresponding display window flashes the window number. The set time window displays the number of samples that have been digested, which means that the sample with the corresponding number has completed digestion;
[0078] (6) Quickly remove the digestion sample tube, dry filter it while hot into a 100 mL volumetric flask, and rinse the digestion tube with 0.1 mol / L nitric acid four times, 15 mL each time;
[0079] (7) After all samples have been digested, the volumetric flask is filled to 100 mL to determine the concentration of slow-release potassium;
[0080] (8) Determination method: Flame photometer method was used for determination. The results are shown in Table 1.
[0081] Example 5:
[0082] (1) 1 mol / L nitric acid was used as the extraction solvent for slow-release potassium, and dimethyl silicone oil was used as the oil bath heating source;
[0083] (2) Adjust the heating temperature to 130°C. After the temperature stabilizes, plug in the programmable logic controller and set the digestion time to 10 minutes.
[0084] (3) Weigh 1.0 g of soil standard materials (ASA-1b, ASA-5b, and ASA-16) and place them in slow-release potassium digestion tubes. Add 10.0 mL of 1 mol / L nitric acid. Prepare a test tube with only 10.0 mL of 1 mol / L nitric acid (blank sample). Place all digestion tubes in a wire cage, insert a slow-release potassium digestion gas flow rate measurement probe, and place the wire cage in the prepared oil bath.
[0085] (4) Turn on the programmable logic controller switch, turn on the probe switch corresponding to the sample, and observe the programmable logic controller information display window, which displays the gas flow rate status in the test tube;
[0086] (5) When the difference between the gas flow rate measurement value and the reference sample is within ±10%, the programmable logic controller automatically starts recording the digestion time. When the digestion time reaches the set time, the programmable logic controller emits a buzzer, and the corresponding display window flashes the window number. The set time window displays the number of samples that have been digested, which means that the sample with the corresponding number has completed digestion;
[0087] (6) Quickly remove the digestion sample tube, dry filter it while hot into a 100 mL volumetric flask, and rinse the digestion tube with 0.1 mol / L nitric acid four times, 15 mL each time;
[0088] (7) After all samples have been digested, the volumetric flask is filled to 100 mL to determine the concentration of slow-release potassium;
[0089] (8) Determination method: Flame photometer method was used for determination. The results are shown in Table 1.
[0090] Example 6:
[0091] In order to facilitate the comparison of the parallelism of the slow-release potassium digestion effect of the present invention on soil samples, Example 6 was carried out as a comparison.
[0092] (1) 1 mol / L nitric acid was used as the extraction solvent for slow-release potassium, and dimethyl silicone oil was used as the oil bath heating source;
[0093] (2) Adjust the heating temperature to 130°C. After the temperature stabilizes, plug in the programmable logic controller and set the digestion time to 10 minutes.
[0094] (3) Weigh 2.5 g of soil standard materials (ASA-1b, ASA-5b, and ASA-16) and place them in slow-release potassium digestion test tubes. Add 25.0 mL of 1 mol / L nitric acid. Prepare a test tube with only 25.0 mL of 1 mol / L nitric acid (blank sample). Place all digestion test tubes in a wire cage, insert a slow-release potassium digestion gas flow rate measurement probe, and place the wire cage in the prepared oil bath.
[0095] (4) Turn on the programmable logic controller switch, turn on the probe switch corresponding to the sample, and observe the programmable logic controller information display window, which displays the gas flow rate status in the test tube;
[0096] (5) When the difference between the gas flow rate measurement value and the reference sample is within ±10%, the programmable logic controller automatically starts recording the digestion time. When the digestion time reaches the set time, the programmable logic controller emits a buzzer, and the corresponding display window flashes the window number. The set time window displays the number of samples that have been digested, which means that the sample with the corresponding number has completed digestion;
[0097] (6) Quickly remove the digestion sample tube, dry filter it while hot into a 100 mL volumetric flask, and rinse the digestion tube with 0.1 mol / L nitric acid four times, 15 mL each time;
[0098] (7) After all samples have been digested, the volumetric flask is filled to 100 mL to determine the concentration of slow-release potassium;
[0099] (8) Determination method: Flame photometer method was used for determination. The results are shown in Table 1.
[0100] Digestion performance test
[0101] According to NY / T 889-2004 "Determination of Soil Quick-Acting Potassium and Slow-Acting Potassium Content" (conventional method), a testing technician skilled in operating the measurement parameters used this method to determine the slow-acting potassium content of soil standard materials (ASA-1b, ASA-5b, and ASA-16). The measurement was repeated once to compare the parallelism of the conventional method and the results with those obtained using the digestion device of the present invention. The results are shown in Table 1:
[0102] Table 1 Comparison of the digestion effects of different digestion methods for soil standard substance slow-release potassium
[0103]
[0104] It can be seen from Table 1 that the digestion effect of the method of the present invention is significantly better than that of the conventional method, and reducing the sample amount has little effect on the measurement results, the parallelism is good, and reducing the sample amount has little effect on the measurement results, which can meet the measurement requirements and has little dependence on the experience of the tester.
Claims
1. A slow-release potassium digestion tube, characterized in that: The slow-release potassium digestion tube comprises a test tube (1), a test tube plug (2), and a gas flow rate measuring probe (3); the test tube plug (2) is inserted into the test tube (1); the gas flow rate measuring probe (3) is placed in the test tube plug (2); and the test tube (1) is connected to the gas flow rate measuring probe (3) through the test tube plug (2).
2. The slow-release potassium digestion tube according to claim 1, wherein: The test tube plug (2) is a special-shaped tube, and the gas flow rate measuring probe (3) extends from the outside of the test tube plug (2) into the middle of the test tube plug (2).
3. The slow-acting potassium digestion tube according to claim 2, wherein: The test tube plug (2) comprises a plug body (21), a probe accommodating cavity (22), and an exhaust pipe (23) which are connected in sequence from front to back; the plug body (21), the probe accommodating cavity (22), and the exhaust pipe (23) are N-shaped as a whole; the plug body (21) is inserted into the test tube (1) and is connected to the test tube (1); the gas flow rate measuring probe (3) extends from the outside of the test tube plug (2) into the probe accommodating cavity (22).
4. The slow-release potassium digestion tube according to claim 3, wherein: The probe accommodating chamber (22) is shaped like a hot air balloon as a whole; the narrow opening of the probe accommodating chamber (22) is connected to the plug body (21); the sphere of the probe accommodating chamber (22) is connected to the exhaust pipe (23); and the gas flow rate measuring probe (3) extends from the outside of the test tube plug (2) into the probe accommodating chamber (22).
5. The slow-release potassium digestion tube according to claim 4, wherein: The inner diameter of the narrow opening of the probe accommodating cavity (22) is smaller than the inner diameter of the test tube (1); and the inner diameter of the sphere of the probe accommodating cavity (22) is not larger than the inner diameter of the test tube (1).
6. The slow-release potassium digestion tube according to any one of claims 1 to 5, characterized in that: The mouth of the test tube (1) and the mouth of the test tube plug (2) are both frosted. Preferably, the measurement accuracy of the gas flow rate measuring probe (3) is 0-30m / s, and the applicable temperature range is 20-140°C.
7. A digestion device for measuring the slow-release potassium content in soil, characterized by: The digestion device for measuring the slow-release potassium content in soil comprises a programmable logic controller (5), a display (6), a buzzer (7) and a slow-release potassium digestion tube as described in any one of claims 1 to 6; there are at least two slow-release potassium digestion tubes; the display (6) and the buzzer (7) are both connected to the programmable logic controller (5); and the gas flow rate measurement probes (3) in the slow-release potassium digestion tubes are both connected to the programmable logic controller (5) via signal lines.
8. The digestion device for measuring the slow-release potassium content in soil according to claim 7, characterized in that: The digestion device for measuring the slow-release potassium content in soil further comprises a working box (4); a signal line through-hole (41) is provided on the working box (4); the programmable logic controller (5) is placed inside the working box (4); the signal line passes through the signal line through-hole (41); and the display (6) and the buzzer (7) are both arranged on the working box (4).
9. The digestion device for measuring the slow-release potassium content in soil according to claim 8, characterized in that: The working box (4) further comprises a flow rate display window (42), a flow rate switch (43), a time setting button (44) and a power cord (45); the display (6) is embedded in the flow rate display window (42); the flow rate switch (43), the time setting button (44) and the power cord (45) are all connected to the programmable logic controller (5).
10. A digestion method based on the digestion device for measuring the content of slow-release potassium in soil according to any one of claims 7 to 9, characterized in that: The digestion method comprises the following steps: 1) Prepare an oil bath heating device; the temperature of the oil bath heating device is 110°C-130°C; preferably, the heating medium used by the oil bath heating device is dimethyl silicone oil or paraffin oil; 2) preparing the slow-acting potassium digestion tube according to any one of claims 1 to 6; at the same time, dividing the slow-acting potassium digestion tube into a test tube for detection and a test tube for blank control; preferably, there are multiple test tubes for detection; 3) placing the soil sample to be tested in a test tube, adding nitric acid to the test tube, wherein the volume-to-mass ratio of the nitric acid to the soil sample to be tested is 10:1 in mL:g, and inserting the test tube plug according to any one of claims 1 to 6 into the test tube; adding nitric acid to a blank control test tube with an equal volume as that of the test tube, and inserting the test tube plug according to any one of claims 1 to 6 into the test tube; wherein the concentration of the nitric acid is 1 mol / L; 4) Place the test tube for detection and the test tube for blank control in the oil bath heating device prepared in step 1) at the same time, and collect the gas flow rate V of the test tube in real time through the gas flow rate measuring probe (3). 检测 and the gas flow rate V of the blank control test tube 对照 ; 5) The gas flow rate V of the test tube is controlled by the programmable logic controller (5). 检测 and the gas flow rate V of the blank control test tube 对照 The difference is judged, when |V 检测 -V 对照 | / V 对照 When the digestion temperature is less than or equal to 10%, the digestion start time is recorded by the programmable logic controller (5). After the digestion experiment is completed, the programmable logic controller (5) controls the buzzer (7) to work and removes the test tube from the oil bath heating device. 6) Determine the concentration of slow-acting potassium in the test tube using conventional techniques.