Xerogels doped with 1-(2-pyridylazo)-2-naphthol and xylenol orange: Indicator tubes and indicator powders for determining copper(II) and iron(III) insolution

Silica-based xerogels doped with 1 -(2-pyrilylazo)-2-naphthol and Xylenol O range were prepared. The xerogels differ in the specific surface and the re agent concentration. Modified xerogels were used as indicator powders for d etermining copper(II) and iron(III) using indicator tubes. The effects of t he reagent concentration in the indicator powder and its specific surface o n the length of the colored zone were studied. Indicator tubes were develop ed for determining 0.3-300.0 mg/L copper(II) and 1.0-120.0 mg/L iron(III) i n solutions. The results of determining copper(II) in plant mineral food an d iron(III) in natural waters and ashed milk powder are presented.