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What parts and analysis steps are included in the total phosphorus test?

by:BOQU     2022-02-20

When we play by the sea or lake, we are likely to see the color of the water is red and we may also see a lot of algae in the water. This is because the total phosphorus content in the water is relatively high. If the monitoring personnel want to know the total phosphorus content in the water, they need to use professional instruments to monitor. Next, we will learn more about the parts of total phosphorus detection and the detection steps! What are the parts of the total phosphorus test?

1. Phosphorus in water can exist in the form of elemental phosphorus. Orthophosphate. Shrinkage phosphate. Pyrophosphate. Metaphosphate. Organic unity phosphate. Its main sources are domestic sewage, chemical fertilizers, organophosphorus pesticides, and phosphate cleaners used in modern detergents. Phosphate can interfere with the coagulation process in water plants. Phosphorus in water is a key element required for algae growth. Excess phosphorus is a major cause of dirt and odors in water, making lakes nutrient-rich and red tides in bays.

2. Total Phosphorus is the measurement result of converting various forms of Phosphorus into orthophosphate after digestion of the water sample, measured in milligrams of Phosphorus per liter of the water sample. The measurement of total phosphorus in water can be carried out according to the specified method of water quality analysis. The phosphorus compounds in the water are converted into orthophosphate under the action of potassium persulfate. What are the analytical steps for total phosphorus detection?

3. Potassium persulfate digestion: Add 4 mL of potassium persulfate to the sample, plug the cap of the stoppered graduated tube tightly, use a small piece of cloth and thread to close the glass tightly, put it into a large beaker, put it in Heating in a high-pressure steam sterilizer, when the pressure reaches 1.1kg/cm2, the corresponding temperature is 120 ℃, and the heating is stopped after 30min. After the pressure gauge reading drops to zero, take it out to cool. Then dilute to mark with water. Note: If storing water samples with sulfuric acid. When digesting with potassium sulfate, first adjust the sample to neutrality.

4. Nitric acid-perchloric acid digestion: take 25 ml of sample into a conical flask, add several glass beads, add 2 ml of nitric acid, heat on an electric heating plate, and concentrate to 10 ml. After cooling, 5 ml of nitric acid was added, then heated and concentrated to 10 ml, and cooled. Add 3 ml of perchloric acid and heat until the perchloric acid emits white smoke. At this time, a small funnel can be added to the conical flask or the temperature of the electric heating plate can be adjusted to keep the digestion solution in a reflux state on the inner wall of the conical flask until the remaining 3-4 ml is cooled. Add 10 ml of water and add 1 drop of phenolphthalein indicator. Add sodium hydroxide solution dropwise until it turns reddish, then add sulfuric acid solution dropwise until the reddishness just subsides, and mix well. Move into stopper graduated tube and dilute to mark with water.

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