Boric Acid Detection in Water by Gallacetophenone

The detection of boron down to ppt order in ultrapure water is required to ensure high-quality and stable semiconductor manufacturing. To realize a simple yet sensitive method for the detection of boron (boric acid), we designed a ruthenium complex possessing a stable ligand with boric acid sensing function. Gallacetophenone (2’,3’,4’-trihydroxyacetophenone) ligand has a b -diketone moiety that can coordinate to a metal and a cis -diol moiety that shows reactivity with boric acid. Comparison of UV-vis absorption spectra measured in the presence and absence of boric acid at various pH revealed that gallacetophenone showed the greatest response to boric acid at pH 8.58. From the spectral changes in the absorbance of gallacetophenone aqueous solution in various concentrations of boric acid at pH 8.58, decreases in the absorbance at the wavelength of 330 nm were observed with increasing boric acid concentration. On the basis of the relationship between the absorption spectra and the boric acid concentration, the binding constant (assuming a 1:1 binding model) for the interaction between gallacetophenone and boric acid was estimated to be 420.7 ± 28.0 mol -1 dm 3 . The electrochemical detection of boric acid was also conducted.