Anions in etching baths

Determination of fluoride, acetate, nitrate, sulfate, silicate, and hexafluorosilicate (calculated) in an etching bath using anion chromatography with conductivity detection after sequential suppression and subsequent UV/VIS detection with post-column reaction (see AN U-50). Hexafluorosilicate is hydrolyzed into fluoride and silicate. The measured fluoride concentration is the sum of free and released fluoride.