AATCC 168-2018 is an alternate to AATCC Method 149, Chelating Agents: Chelation Value of Aminopolycarboxylic Acids and Their Salts; Calcium Oxalate Method.

The active content of ethylenefiaminetetraacetic acid (EDTA), N-hydroxyethylenediaminetriacetic acid (HEDTA) and diethylenetriaminepentaacetic acid (DTPA) and their salts is usually expressed by the calcium chelation value (CaCV). Titration with calcium salt using either oxalate or a dye indicator, as done in AATCC Method 149, yields a value which includes partially substituted EDTA, HEDTA, DTPA, nitrilotriacetic acid (NTA), iminodiacteic acid (IDA), glycolate and other weak chelating agents found in some commercial products. This alternative procedure excludes the effect of partially substituted products, providing a more stringent value.