69. Solving a chemistry problem

4. For the photometric determination of zinc ions in solution, the following organic reagents are used: zinc (E = 2 x 104), xylenol orange (E = 1.2 x 104), dithizone (E = 9.5 x 104). Justify the choice of a reagent that makes it possible to determine zinc ions in wastewater at the level of the maximum allowable concentration of 0.01 mg/l without preliminary concentration of the solution, if the minimum optical density measured by the device is 0.01 when using a cuvette with a layer thickness of 1.00 cm.