Comparative Study of PBS Treated Directly With Plasma or Indirectly via Plasma‐Treated Water Using in‐Liquid and Above‐Liquid Jet Configurations

ABSTRACT Interactions between cold atmospheric pressure plasmas and liquids are gaining attention for plasma‐treated liquids (PTLs). This study evaluates how atmospheric pressure plasma jet configuration—plasma above (PA) or submerged (PS)—and liquid preparation (direct PBS treatment or PBS powder added to plasma‐treated DI water, PTW) govern reactive oxygen and nitrogen species (RONS) production. PS generated higher H₂O₂ and 2.6× greater energy‐normalized efficiency than PA. Adding PBS powder to PTW further increased H₂O₂ by limiting scavenging. Nitrogen species showed strong configuration selectivity: PA produced more NO₂⁻ and was the exclusive source of NO₃⁻, slightly higher in PBS‐added PTW. All RONS remained stable for 15 days at 4°C–37°C. PS favors efficient ROS generation, while PA enables nitrogen‐rich PTLs for application‐specific design.