Determination of zeolite-a in detergent powders as acid-soluble aluminum by high-performance liquid chromatography with post-column derivatization

A high-performance liquid chromatographic method is described for the rapid determination of zeolite-A in detergents as acid-soluble aluminum. Detergent samples are dissolved by digestion with nitric acid. Chromatographic separation on a strong cation exchanger in acidic ammonium sulfate media is combined with the highly selective color reaction of acid-soluble aluminum with pyrocatechol violet. Interferences of the chelating agents in detergents are thus eliminated. After the digestion, determinations take 8 min per sample. The relative standard deviation is less than 1% and quantitative recoveries are obtained. Several commercial detergents were analyzed successfully. The results obtained by the proposed method and by compleximetric titration agreed very closely for zeolite-A contents in the range 2–22%.