Three pretreatment methods for determination of total phosphorus by platinum salt

There are three pretreatment methods for the determination of total phosphorus in this substance, namely, potassium persulfate digestion, nitric acid-perchloric acid digestion and microwave digestion.

1, potassium persulfate digestion method: this is the national standard analysis method and the most widely used method at present. Its principle is that potassium persulfate oxidizes phosphorus-containing compounds in water samples at high temperature and high pressure to convert them into orthophosphate. Under acidic conditions, orthophosphate reacts with ammonium molybdate and antimony potassium tartrate to form phosphomolybdate heteropoly acid, which is reduced by reducing agent ascorbic acid to form blue complex. The absorbance was measured at the wavelength of 700nm to determine the total phosphorus content.

2. Nitric acid-perchloric acid digestion method: This method is suitable for water samples containing organophosphorus. The principle is that under acidic conditions, nitric acid and perchloric acid can oxidize phosphorus-containing compounds in water samples into orthophosphate. Then orthophosphate reacts with ammonium molybdate and antimony potassium tartrate to generate phosphomolybdate heteropoly acid, and then it is reduced by reducing agent ascorbic acid to generate blue complex. The absorbance was measured at the wavelength of 700nm to determine the total phosphorus content.

3. Microwave digestion method: This method uses microwave energy to heat and digest water samples. Its principle is that potassium persulfate oxidizes phosphorus-containing compounds in water samples at high temperature and high pressure to convert them into orthophosphate. Then orthophosphate reacts with ammonium molybdate and antimony potassium tartrate to generate phosphomolybdate heteropoly acid, and then it is reduced by reducing agent ascorbic acid to generate blue complex. The absorbance was measured at the wavelength of 700nm to determine the total phosphorus content.