AATCC 168:2018 pdf download.Chelation Value of Polyaminopolycarboxylic Acids and Their Salts: Copper PAN Method
1. Purpose and Scope
1.1 The active ingredient content of ethylenediaminetetraacctic acid (EDTA). N-hydroxycthylcthylencdiaminetriaccticacid (I-I E DTA) and dicihylenetriarnincpcntaacctic acid (DTPA) and their salts is usually expressed by the calcium chelation value (CaCV). This value indicatcs the amount of calcium (as calcium carbonate) which will be chelated by a known weight of chelating agent. This method excludes the effect of partially- substituted products.
2. Principle
2.1 Calcium chelation value is determined experimentally by titrating a weighed specimen of chelating agent with a copper nitrate solution of known concentration in the presence of PAN (1 - (2-pyridyla7o)-2-naphthol). Initially, the color of the solution is yellow-green due to free indicator. When all of the chelating agent has reacted with copper nitrate, the color of the solution changes to a permanent purple which is the end point.
2.2 The CaCV indicates the amount of calcium (as calcium carbonate) that will be sequestered by a known weight of chelating agent and is expressed as milligrams of calcium carbonate (CaCO3) per grain of chelating agent (mg calcium carbonateg chelating agent).
4. Safety Precautions
NOTE: These safety precautions arc for information purposes only. The precautions arc ancillary to the testing procedures and arc not intended to be all inclusive. It is the user’s responsibility to use safe and proper techniques in handling materials in this test method. Manufacturers MUST be consulted for specific details such as material safety data sheets and other manufacturer’s recommendations. All OSI-IA standards and rules must also be consulted and followed.
4.1 Good laboratory practices should be followed. Wear safety glasses in all laboratory areas.
4.2 All chemicals should be handled with care.
4.3 In preparing, dispensing and handling glacial acetic acid and sodium hydroxide use chemical goggles or face shield, impervious gloves and an impervious apron. Concentratcd acids and bases should be handled only in an adequately ventilated laboratory hood.
CAUTION: Always add acid to water.
4.4 cupric nitrate 2.5 hydrate is corrosive to the eye and skin and is harmful if inhaled. It is an oxidi7ing material and may react with organic materials. It should be handled only in an adequately ventilated hood.AATCC 168 pdf download.