This method can be used to determine concentrations of quaternary ammonium compounds (quats) and polymeric betaine in wood and ACQ treating solutions. It is intended for routine quality control in wood treating and is not suitable for trace levels of quats in wood or treating solutions.

All cationic species that form sparingly soluble compounds with STPB can be determined quantitatively and therefore can also potentially interfere with the determination of quats. This method is not compound specific, total equivalence of cationic compounds is determined. The molecular weight of the quat being studied must be known for accurate results. Quat compounds to which this method has been validated include alkyldimethylbenzylammonium chloride (ADBAC), didecyldimethylammonium chloride (DDAC) and DDAC equivalents, and Polymeric Betaine (DPAB).