[0027] In order to enable those skilled in the art to understand the method of the present invention more clearly, the applicant has further described it experimentally in specific embodiments.
[0028] A plasma emission spectrometer method for determining potassium oxide in compound fertilizers includes the following steps:
[0029] 1) Sample processing
[0030] Divide the sample to 40-60g with a shrinking device or quartering method, crush it with a universal crusher, and pass through a 0.4mm test sieve for analysis; the sample is made of monoammonium phosphate (diammonium phosphate), nitric acid Analytical sample prepared from chlorine-based compound fertilizer produced with ammonium and potassium chloride as raw materials, named as sample A; sulfur-based compound fertilizer produced with monoammonium phosphate (diammonium phosphate), ammonium nitrate, and potassium sulfate as raw materials The prepared analysis sample is named sample B; the analysis sample prepared from the compound fertilizer produced from monoammonium phosphate (diammonium phosphate), potassium chloride, ammonium nitrate, urea, and potassium dihydrogen phosphate is named test Sample C; an analysis sample prepared from a compound fertilizer produced from monoammonium phosphate (diammonium phosphate), ammonium chloride, ammonium nitrate, urea, potassium dihydrogen phosphate, and potassium sulfate, named sample D; potassium sulfate, The analysis samples prepared by potassium nitrate, potassium chloride, and potassium dihydrogen phosphate are named samples E, F, G, and H;
[0031] 2) Preparation of sample solution to be tested
[0032] Weigh 1.0-2.5g of sample A that has been crushed and sieved into a 400ml beaker, add 150ml of water, heat and boil for 20-30 minutes, transfer to a 500ml volumetric flask after cooling, shake up to a constant volume, filter dry, discard the original Filtrate, pipette 5-10ml of filtrate into a 250ml volumetric flask, and shake it evenly; operate sample BH in the same way;
[0033] 3) Configuration of potassium oxide standard solution
[0034] Weigh the premium grade pure potassium oxide and dissolve it in water, prepare it into a standard solution of 0.1 mg/mL, and set aside;
[0035] 4) Standard curve drawing
[0036] Pipette 0.00mL, 5.00mL, 10.00mL, 20.00mL, 30.00mL, 40.00mL of potassium oxide standard solution into 6 100mL volumetric flasks, dilute to the mark with water, shake well to make 1mL containing 0.00μg of potassium oxide 5.00μg, 10.00μg, 20.00μg, 30.00μg, 40.00μg standard solutions, adjust the zero point with a blank solution on the plasma emission spectrometer, measure the standard solution from low concentration to high concentration, record the corresponding intensity value, according to the potassium oxide concentration Draw a standard curve or calculate a linear regression equation with the corresponding intensity value;
[0037] 5) Measurement of sample solution
[0038] Put the sample solution prepared in step 2) on the plasma emission spectrometer for measurement. Simultaneously carry out a blank experiment, operate samples B-H in the same way; adjust the zero point of the sample blank solution on the plasma emission spectrometer with the sample blank solution under the same conditions as the standard solution series, measure the strength value of the sample solution, and check the concentration value on the working curve. Standard solution should be used to calibrate the instrument after every 2 samples.
[0039] Comparative test 1: Using the potassium tetraphenylborate method specified in GB8574-1988 "Determination of Potassium Content in Compound Fertilizers", the detection of samples A-H in step 1) of Example 1 was performed.
[0040] Comparative experiment 2: Using the method for detecting potassium content in the literature "Determination of potassium oxide and sulfur content in compound fertilizers by plasma emission spectrometer" (Phosphorus and sulfur design and powder engineering, 2010 fourth issue, Zhang Jinju, etc.), carry out Example 1 Step 1) Test the sample AH.
[0041] Test results: The test results of Example 1, Comparative Experiments 1 and 2 are summarized, see Table 1.
[0042] Table 1 Summary and comparison table of test results
[0043]
[0044]
[0045] Remarks: In the accuracy test, the measured value is within the standard deviation range, and the recovery rate is between 95.1% and 103.4%, that is, the accuracy rate is high.
[0046] From the above test results, in the detection of sample AD, when the potassium oxide concentration is ≤5.00%, the absolute difference of parallel determination is ≤0.30%, and the accuracy rate is ≥99%; when the potassium oxide concentration is 5.00% to 10.00%, parallel The absolute difference of the determination is ≤0.40%, the accuracy rate is ≥99%; when the potassium oxide concentration is 10.00%~20.00%, the absolute difference of the parallel determination is ≤0.30%, and the accuracy rate is ≥97%; when the potassium oxide concentration is ≥20.00%, the parallel The absolute difference of the determination is ≤0.40%, and the accuracy is ≥96%; in the high-concentration fertilizer sample EH, the potassium oxide concentration is ≤40.00%, and the absolute difference of the parallel determination is ≤0.40%, and the accuracy is ≥99%; When potassium concentration is 40.00%-45.00%, the absolute difference of parallel determination is ≤0.50%, and the accuracy is ≥98%; when potassium oxide concentration is 45.00%-50.00%, the absolute difference of parallel determination is ≤0.50%, and the accuracy is ≥97 %; when the potassium oxide concentration is greater than or equal to 50.00%, the absolute difference of the parallel determination is less than or equal to 0.50%, and the accuracy rate is greater than or equal to 96%; it can be seen that the parallel determination of the detection result of the present invention has a small absolute difference, high accuracy, and accurate detection Calculate the concentration of potassium oxide in various compound fertilizers with different concentrations.
[0047] In comparative test 1, in the sample AD, the absolute difference of the parallel determination is ≤0.40%, and the accuracy is ≥94% in the potassium oxide concentration ≤2.00%; the absolute difference of the parallel determination is 5.00% to 10.00% in the potassium oxide concentration Value ≤ 0.60%, accuracy rate ≥ 91%; in potassium oxide concentration 10.00% to 20.00%, the absolute difference of parallel determination is ≤ 1.00%, accuracy rate ≥ 83%; in potassium oxide concentration ≥ 20.00%, the absolute difference of parallel determination Value ≤ 2.00%, accuracy ≥ 72%; in the high-concentration fertilizer sample EH, when the potassium oxide concentration is ≤ 40.00%, the absolute difference of parallel determination is ≤ 2.00%, and the accuracy rate is ≥ 85%; in the potassium oxide concentration 40.00% -45.00%, the absolute difference of the parallel determination is ≤3.00%, and the accuracy is ≥82%; when the potassium oxide concentration is 45.00%-50.00%, the absolute difference of the parallel determination is ≤3.50%, and the accuracy is ≥77%; When the potassium concentration is ≥50.00%, the absolute difference of the parallel determination is ≤4.50%, and the accuracy rate is ≥68%; it can be seen that the absolute difference and accuracy of the parallel determination of the potassium oxide detection result of the present invention under the same concentration are obviously superior When the potassium tetraphenylborate method is used to detect the potassium oxide content in high-concentration compound fertilizers, the absolute difference of parallel determination is large, indicating large fluctuations, instability, and low accuracy. The test results cannot be convincing.
[0048] In comparative test 2, in the sample AD, the absolute difference of the parallel determination is ≤0.30%, and the accuracy is ≥95% in the potassium oxide concentration ≤ 5.00%; the absolute difference of the parallel determination is 5.00% to 10.00% in the potassium oxide concentration Value ≤ 0.40%, accuracy rate ≥ 92%; in potassium oxide concentration 10.00% to 20.00%, the absolute difference of parallel determination is ≤ 0.60%, accuracy rate ≥ 85%; in potassium oxide concentration ≥ 20.00%, the absolute difference of parallel determination Value ≤ 1.00%, accuracy rate ≥ 82%; in the high-concentration fertilizer sample EH, when the potassium oxide concentration is ≤ 40.00%, the absolute difference of parallel determination is ≤ 1.00%, and the accuracy rate is ≥ 90%; in the potassium oxide concentration 40.00% -45.00%, the absolute difference of parallel determination is ≤1.50%, and the accuracy is ≥87%; when the potassium oxide concentration is 45.00%-50.00%, the absolute difference of the parallel determination is ≤2.00%, and the accuracy is ≥84%; When the potassium concentration is ≥50.00%, the absolute difference of the parallel determination is ≤2.00%, and the accuracy rate is ≥79%; it can be seen that as the potassium oxide concentration increases, the absolute difference of the parallel determination is getting larger and more accurate. The rate is decreasing. In the high concentration test EH, when the potassium oxide concentration is greater than or equal to 50.00%, the accuracy rate is greater than or equal to 79%, and the test results are not sufficiently convincing. Therefore, judging from the detection results and detection process of Example 1 and Comparative Experiment 2, the absolute difference and accuracy of the detection of various potassium oxide concentrations in the present invention are significantly better than the detection results of the literature method. The reason is that the present invention Choose a suitable standard curve, better sample preparation and instrument parameter settings for testing.
[0049] In summary, we found that using an optimized plasma emission spectrometer to detect potassium oxide in compound fertilizers, within the same concentration range, the accuracy of the inspection is significantly higher than that of the potassium tetraborate gravimetric method; no masking agent is required (if it contains cyanamide Or organic matter, before adding the EDTA solution, add bromine water and activated carbon treatment), precipitation agent (sodium tetraphenylborate), to reduce the precipitation of the filtration, drying and weighing process, and not interfere with the sample composition, the analysis time is shortened to Within 1.5 hours, it can detect the potassium oxide content in high-concentration and various compound fertilizers, with high detection accuracy, good stability, and high sensitivity; and this method has the characteristics of simple operation and short time-consuming.
