(The reagent preparation in this reagent box is entirely derived from the national standard "Agrochemical Analysis Method") 01: Phenol Solution: Weigh 13.5 g of sodium hydroxide, 1.5 g of EDTA disodium salt, and 2.5 g of sodium acetate. Dissolve these in approximately 200 ml of distilled water. Add 22.5 g of phenol, dissolve completely, and then dilute to a final volume of 500 ml with distilled water. Store in a brown bottle in a cool, dark place. 02: Sodium Hypochlorite Solution: Take 100 ml of commercial sodium hypochlorite solution (5.25% concentration) and mix it with 400 ml of distilled water. Transfer the mixture into a brown glass bottle and store in a cool, dark location. 03: 4ppm and 8ppm Ammonium Nitrogen Standard Solutions: (1) Weigh 0.4717 g of anhydrous ammonium sulfate and dissolve it in distilled water. Add 2 ml of concentrated sulfuric acid, then dilute to 1000 ml with distilled water. This gives a 100 ppm standard solution. (2) Use a graduated pipette to transfer 2 ml of the 100 ppm solution into a 50 ml volumetric flask, and add 4 ml of distilled water. Dilute to the mark for a 4 ppm solution. Repeat the process with 4 ml of the 100 ppm solution to prepare an 8 ppm solution. 04: Molybdenum Sulfate Solution: Slowly add 126 ml of concentrated sulfuric acid to 400 ml of distilled water while stirring. Allow the solution to cool. In another beaker, dissolve 10 g of ammonium molybdate in 300 ml of distilled water and cool. In a third beaker, dissolve 0.5 g of bismuth potassium tartrate in 100 ml of distilled water. Carefully pour the sulfuric acid solution into the ammonium molybdate solution, then add the potassium antimony tartrate solution. Dilute to 1 litre and store in a brown bottle. 05: 1ppm Effective Phosphorus Standard Solution: (1) Weigh 0.4390 g of high-purity potassium dihydrogen phosphate and dissolve it in distilled water. Add 2 ml of concentrated sulfuric acid and dilute to 1000 ml with distilled water. This gives a 100 ppm standard solution. (2) Use a graduated pipette to transfer 1 ml of the 100 ppm solution into a 100 ml volumetric flask and dilute to the mark with distilled water. This results in a 1 ppm solution. 06: Thymolphthalein Solution: Dissolve 0.05 g of thymolphthalein in 50 ml of 95% ethanol. 07: EDTA Solution: Dissolve 10 g of EDTA disodium salt in 100 ml of distilled water. Add 5 drops of thymolphthalein solution and adjust the pH with sodium hydroxide until a light blue color appears. Store in a brown bottle. 08: Sodium Tetraphenylboron Solution: Weigh 6 g of disodium hydrogen phosphate and 6 g of sodium tetraphenylborate. Dissolve both in 200 ml of distilled water. Let the mixture sit overnight, then filter the solution and store it in a brown bottle. 09: Formaldehyde Solution: Measure 100 ml of 37% formaldehyde solution and add 5 drops of thymolphthalein. Adjust the pH to a light blue color using 8% sodium hydroxide solution. Store in a brown bottle. 10: 20ppm Available Potassium Standard Solution: (1) Weigh 0.1907 g of high-purity potassium chloride and dissolve in distilled water. Add 2 ml of concentrated sulfuric acid, then dilute to 1000 ml with distilled water. This gives a 100 ppm solution. (2) Transfer 20 ml of the 100 ppm solution into a 100 ml volumetric flask and dilute to the mark with distilled water. This yields a 20 ppm solution. 11: Concentrated Sulfuric Acid: 98% (analytical grade). Please bring your own. 12: Potassium Dichromate Solution: Weigh 39.23 g of potassium dichromate (analytical grade), dissolve in 600 ml of water, and dilute to 1 litre with distilled water. 13: 0.5%-C Standard Solution: Weigh 1.376 g of glucose (chemically pure) in a 100 ml volumetric flask. Dissolve in distilled water, add 1 ml of concentrated sulfuric acid, and dilute to the mark with distilled water. The resulting solution contains 5 mg/ml of carbon. 14: Potassium Chloride: 15 g (Analytical Pure). 15: Sodium Bicarbonate: 8.4 g (Analytical Pure). 16: Sodium Nitrate: 17 g (Analytical Pure). 17: Ascorbic Acid: 8 g (Analytical Pure). 18: Citric Acid: 4 g (Analytical Pure). Hangzhou Top Instrument Co., Ltd. Room 806, Songdu Building, No. 69 Wangjiang Road, Hangzhou Phone: +86 062776 Fax: Not Provided Rigging Hardware,Eye Grab Hook,Clevis Slip Hook,Clevis Slip Hook With Latch Yangzhou Jieerte Steel Cable Co., Ltd , https://www.jieertesteelcable.com