Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Phosphorus Types, Analyses, and Terminology Phosphorus as an element makes up about 0.1% of the elements in the earth’s crust so in terms of abundance, it is minor compared to oxygen, sodium, or aluminum, but in terms of importance to life, it is a critical element. Phosphorus is an important component of ATP (energy), DNA (genes), RNA (protein synthesis), NADP (energy transfer), phospholipids (cell membrane), and many more. Phosphorus is critical for growth and survival of all life forms and there is no exception. In the analyses of phosphorus, there are many terms in print and different regulations are in place to monitor levels of phosphate in water since excess phosphate can lead to excessive algal blooms. Generally, phosphorus does not exist by itself (elemental phosphorus) and instead is usually bound to oxygen or other elements. The most common form is as phosphate (PO4) and many times phosphorus and phosphate are used interchangeably, but they are not the same chemical. Phosphate types are also subdivided into organic phosphate and inorganic phosphate. Organic phosphate is the type of phosphate attached to and part of molecular essential life. These would include ATP, DNA, RNA, phospholipids, and others. Inorganic phosphate, on the other hand, is defined as a salt of phosphoric acid. Phosphoric acid has the molecular formula of H3PO4, but the hydrogen atoms can be replaced by other cations such as sodium, potassium, calcium, and others and form molecules such as sodium phosphate, potassium phosphate, or calcium phosphate. Other terms for phosphate include orthophosphate and polyphosphate. Orthophosphate is the PO4-3 molecule composed of four (4) oxygen atoms and one phosphorus atom. A polyphosphate is when more than three (3) orthophosphate molecules are linked together. In other words, the orthophosphate is the building block of the polyphosphate molecule. Other terms utilized include soluble phosphate and insoluble phosphate. Soluble phosphate is the form of phosphorus that is soluble in water, while insoluble phosphates are not soluble. From a chemical standpoint, a soluble phosphate is a molecule that can pass through a 0.45 µ filter. Many of the terms can be used interchangeably because they refer to the same chemical molecule. For example, inorganic phosphate, inorganic phosphorus, soluble phosphate, and orthophosphate all refer to the same chemical, namely PO 4-3 or phosphate. It is this form of phosphate that can be taken up by the plants and other living organisms. The cells use this form of phosphate (orthophosphate) to build ATP, DNA, NADP, phospholipids, and other biological chemicals. Page 1 of 2 E620 For all intensive purposes, orthophosphorus and soluble phosphorus are the same chemical. In the same manner, organic phosphate, insoluble phosphate, and polyphosphates are also terms used interchangeably, since they are made up of larger molecules. The basic analytical process is to analyze orthophosphate. Thus, when a test is requested for soluble phosphate, the laboratory prepares samples just to determine the level of orthophosphate; however, different procedures may term it as inorganic phosphorus, soluble phosphate, or orthophosphate. They are all the same. When total phosphate is required, the sample is treated with acid and heat to break the organic, insoluble and polyphosphates down to orthophosphate and then the total orthophosphate determined. Having knowledge of the total phosphate and orthophosphorus, it is possible to calculate the organic phosphate. For example: Total P – Ortho P = Organic P Neither the equation nor the methods can provide which category (ATP, DNA, etc.) for the organic phosphate. Additional separation of the fats or nucleic acids would be necessary to determine the chemical form the phosphate is in. Page 2 of 2 E620