AATCC 149:2018 pdf download.Chelation Value of Aminopolycarboxylic Acids and Their Salts: Calcium Oxalate Method
1.1 The active content of ethylenediam i netetraacetic acid (EDTA), N-bydroxyethylethylenediaminetriacetic acid (HEDTA) and diethylenetriaminepentaacetic acid (DTPA) and their salts is usually expressed by the calcium chelation value (CaCV). This value indicates the amount of calcium (as calcium carbonate) which will be chelated by a known weight of chelating agent.
2. Principle
2.1 The chelation value is determined experimentally by titrating a weighed sample of chelating agent with a calcium ion solution of known concentration. A precipitating anion (oxalate) is present during the titration. As the calcium solution is added, the ions arc chelated by the chelating agent and no permanent precipitate is formed as long as there is free chelating agent present. Beyond this point, any excess calcium ion that is added reacts with oxalate anion to form a cloudy precipitate which is the endpoint.
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 (CaCO) per gram of chelating agent (mg calcium carbonate/g chelating agent).
4. Safety Precautions
NOTE: These safety precautions are for information purposes only. The precautions arc ancillary to the testing procedures and are 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 MIJST be consulted for specific details such as material safety data sheets and other manufacturer’s recommendations. All OSHA 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 hydrochloric acid and sodium hydroxide use chemical goggles or face shield, impervious gloves and an impervious apron. Concentrated acids should be handled only in an adequately ventilated laboratory hood. CAUTION: Always add acid to water.
4.4 Dicthylaminc hydrochloride is an eye, skin and respiratory irritant. It should be handled only in an adequately ventilated hood.AATCC 149 pdf download.