Test sticks for the semi-quantitative determination of hydrogen peroxide (H 2 O 2 ) and peroxides in solutionsGradation of scale: 0-50-150-300-500-800-1000 ppmThese test sticks have an additional warning test field, which changes color, when the concentration exceeds 2000 mg/l, because, in such excessive concentration, a color change can occur, which corresponds to a much lower value on the color chart.The following ions interfere in higher concentrations:- 1000 mg/l formaldehyde- 500 mg/l Ca+2- 100 mg/l Ascorbate, free chlorine, bound chlorine, Sulfite- 87.5 degrees e: Total hardnessIn the presence of free and bound chlorine, the warning test field forms a blue coloration.