Ammonium polyphosphate (APP), also known as ammonium polyphosphate or ammonium condensed polyphosphate, is a polyphosphate containing nitrogen and phosphorus. Ammonium polyphosphate can be divided into water-soluble ammonium and water-insoluble ammonium. In recent years, water-soluble ammonium polyphosphate with low polymer has gradually entered the field of chemical fertilizer. Ammonium polyphosphate is a high concentration nitrogen and phosphorus fertilizer.

The application of ammonium polyphosphate to crops is usually not directly absorbed by crops, but gradually hydrolyzed into orthophosphate in the soil and then absorbed and utilized by crops, so it is a slow soluble long-term phosphate fertilizer. At the same time, ammonium polyphosphate has chelating effect on metal ions. It can be used as inorganic chelating agent in base fertilizer, adding some microelements to improve fertilizer efficiency. In the application of ammonium polyphosphate in the field of fertilizer, we should not only know the total phosphorus content and polymerization degree, but also analyze the content of orthophosphate and polymerized phosphorus.

In order to accurately determine the content of orthophosphate and polyphosphate in fertilizer grade ammonium polyphosphate, the method of ion chromatography was used to detect the content of various polyphosphate.

Take 0.5g of commercially available ammonium polyphosphate sample and put it into a 100ml volumetric flask, add pure water to constant volume, conduct ultrasound for 30min, dilute it 100 times, and pass through 0.22 μ m needle filter membrane.

Chromatographic conditions

Instrument: CIC-D150 

Column: SH-AC-16

Eluent: 0-16min 18mM KOH

           16-30min 38mM KOH

            30.1-35min 18mM KOH

Flow rate: 1.0mL / min 

Column pressure: 4.7Mpa 

Detection method: suppressed conductivity method

Injection volume: 25uL 

Suppression current: 120 mA

APP spectrum