Development of a highly conjugated chromophore for precise concentration determination of N(CH3)4OH and N(C4H9)4OH

Tetramethylammonium hydroxide (TMAH) is a highly caustic organic base extensively utilized in semiconductor and display manufacturing processes, including photoresist development, silicon etching, and cleaning procedures. This study introduces a novel spectrophotometric method utilizing a dye with a benzophenone moiety, enabling the detection and quantification of TMAH over a wide concentration range with minimal sample preparation. Traditional concentration measurement methods include titration with standard acid solutions and ICP spectroscopy, yet these approaches can be time-consuming, require expensive equipment, or lack rapid on-site assessment. This research indicates that colorimetric properties of new organic compound depending on the concentration of target molecules, which offers a simple, cost-effective, and accurate alternative for the detection of alkali chemical concentration. • New conjugated system was designed and synthesized for a colorimetric indicator. • The detection condition for the quantification of alkali chemicals was systematically investigated. • Precise determination of alkali concentration was carried out in natural water media. • Hazardous alkali, tetramethylammonium hydroxide, was quantified.