You have to select the proper to prepare dye solution. If you want to prepare the solution in ppm , use ethanol as a solvent in which most of the dyes are soluble.
Firstly, the dye must have a high solubility in a given solvent .secondly, You must to prepare the right concentration of dye solution to avoid deviations from Beer's Law . Also you must to adjust temperature and pH. For preparing of dye stock solution of 500 ppm,0.5 gm of dye is dissolve in suitable volume of solvent ,then the volume is complete to 1000 mL. You can make a set of dye solutions from this dye stock solution by dilution process
Use the formular Co * Vo = Cr * Vr (where C= concentration, V= volume, o = original and r = required) to dilute down to required concentration in ppm from the stock solution of 1g in 1000ml.
i thing take the molecular weight of dyes and dissolve in suitable solvent in 1L give the solution concentration is 1000ppm and after that can dilution by law of that .