1 Theme content and scope of application This standard specifies the sulfuric acid-hydrogen peroxide digestion and flame photometric determination of total potassium in organic fertilizers. This standard applies to the determination of total potassium in non-mud organic fertilizers. 2 Reference standards GB/T 6682 Analysis Laboratory Water Specifications and Test Methods 3 Methodology Samples of organic fertilizers were digested with sulfuric acid-hydrogen peroxide, diluted and determined by flame photometry. In a certain concentration range, the concentration of potassium in the solution is in direct proportion to the luminescence intensity. 4 Reagents All reagents used were of analytical grade except those indicated. Analytical water should meet the specification of the third-grade water in Chapter 5 of GB/T 6682. 4.1 Sulfuric acid (GB/T 625). 4.2 Hydrogen peroxide (GB/T 6684). 4.3 Phosphorus standard stock solution: 1mg/mL Weigh 1.907 g of potassium chloride (GB 646) that has been dried at 110 °C for 2 hours and dissolved in water to a volume of 1 L. 1 mL of this solution contained potassium (K) 1 mg and was stored in a plastic bottle. 4.4 Potassium standard solution: 100μg/mL Pipette 10.0mL of potassium (K) standard stock solution (4.3) into a 100mL volumetric flask and add water to volume. This solution contains 1mL potassium (K) 100μg. 5 Instruments and Equipment Usually laboratory equipment and 5.1 analytical balance; the amount of sense is 0.1mg. 5.2 adjustable electric furnace: 1000W. 5.3 Flame photometer. 5.4 Kelvin flask: 50 or 100 mL. 5.5 Volumetric flasks: 50, 100, 1000 mL. 5.6 pipette: 5,10 mL. 5.7 Curved neck small funnel: Φ2cm. 5.8 bottle with a stopper: 150mL. 6 Preparation of Samples After the air-dried laboratory sample was thoroughly mixed, it was reduced to about 100 g by quartering method, crushed, all passed through a 1 mm aperture sieve, and placed in a sample bottle for use. 7 Analysis steps 7.1 Sample Solution Preparation Weigh the sample 0.5g (liquid manure such as urine or feces, etc. directly weighed 1 ~ 2g liquid), accurate to 0.001g, carefully placed in the bottom of the Kelvin flask (5.4), rinse with a small amount of water attached to the bottle wall On the sample, add 5.0 mL of sulfuric acid (4.1) and 1.5 mL of hydrogen peroxide (4.2). Carefully shake and place a small neck funnel (5, 7) over the bottle and let it stand overnight. 7.2 Blank test The reagents and procedures used were the same as in 7.1 except that no sample was added. 7.3 Calibration Curve Drawing Pipette the potassium standard solution (4.4) 0, 2.50, 5.00, 7.50, 10.00mL into 5 50mL volumetric flasks, add and draw a sample solution of the same volume of blank solution, and dilute with water, the solution is 1mL potassium ( K) 0, 5.00, 10.00, 15.00, 20.00 μg standard solution series. On the flame photometer, adjust the instrument zero point with a blank solution and adjust the full scale to 80 degrees with the highest concentration standard solution in the standard solution series. The other standard solutions were measured from low concentration to high concentration in turn and the instrument indications were recorded. According to the potassium concentration and instrument indications, draw a calibration curve or find a linear regression equation. Pipette 5.00mL sample solution (7.1) into a 50mL volumetric flask and add water to the chamber. The same conditions as the standard solution series were measured on a flame photometer and the instrument was recorded. Calibrate the instrument with potassium standard solution after measuring 5 samples. The total potassium (K) content is expressed in g/kg and is calculated as follows: Total potassium (K) Where: c - obtained from the calibration curve or by the regression equation to determine the color phosphor concentration, μg/mL; V-coloring volume, 50mL; D-Distribution multiple, volume volume / volume, 100/50; m-Weigh the sample mass, g; 10-3- Convert μg/g to a factor of g/kg. The result should be expressed to two decimal places. 9 Allowable difference 9.1 The arithmetic average of the results of two parallel measurements is taken as the result of the determination. 9.2 The absolute difference allowed by the results of two parallel measurements shall meet the following requirements: K,g/kg allowable difference,g/kg <5.0 < 0.5 5.1 to 10.0 <0.7 10.1 to 15.0 <0.9 >15.1 <1.2 Plastic Wash Basin,Outdoor Washbowl Molds,Indoor Washbowl Mold,Wash Basin Molds Yuyao Hongzhou Plastic Technology Co., Ltd. , https://www.hongzhoumould.com
Heat on the adjustable electric furnace (5.2), slowly warm up to smoke sulfuric acid, remove, add 15 drops of hydrogen peroxide (4.3) after slightly cold, gently shake the Kaiser flask, heat for about 10min, remove, after a little cold Add 5 to 10 drops of hydrogen peroxide (4.2) in several portions and retort in several portions until the solution is a colorless or pale yellow serum. Continue heating for 10 minutes and remove the remaining hydrogen peroxide. Remove slightly cold, carefully add water to 20 ~ 30mL, heated to boiling. Remove the cooling and rinse the small necked funnel with a small amount of water. The lotion is collected in the original Kaiser flask. The cooking liquid into 100mL volumetric flask, add water to volume, stand still to clarify or use non-phosphorus filter paper in a stoppered flask (5.8) in the spare.
The same experiment was done in two parallel assays.
7.4 Measurement
8 Expression of analysis results