Tributylammonium pyrophosphate (TbAPP) is a quaternary ammonium salt that is often used as a phase-transfer catalyst or a surfactant.

 It can also be used as a solvent for the extraction of various compounds, as a reagent in chemical synthesis, and as a complexing agent in analytical chemistry. 

TbAPP has been shown to have antimicrobial activity and has been used in some disinfectant and sanitizer formulations.

 It can also be used as a corrosion inhibitor for steel and other metals in oilfield and industrial applications.