The Iodometric Determination of P(III) in Flame Retardants for Cotton

An iodometric method was developed for the determination of P(III) in cotton fabrics finished with Thpc/amide flame retardants. The method is applicable to a wide range of Thpc/amide resins, including those of urea, melamine, the cyclic ureas, and the carbamates, but not those of iodine-sensitive compounds such as thiourea, dihydroxyethyleneurea, or the triazones. The validity of the method was corroborated by experiments with the phosphorus-free resins and their precursors. The phosphorus in the Thpc/amide resins was found to be predominantly trivalent, surviving both the heat cure and the soap-soda boil largely intact.