You get a spectre of test compound. Determine the wavelength of maximum absorption of the solution. Gradually dissolve the suspended portion of your compound. Build the intensity of maximum - the concentration of compound Find the concentration when the solubility is no longer moving. This is solubility constant.

Best regards.

You get a spectre of test compound. Determine the wavelength of maximum absorption of the solution. Gradually dissolve the suspended portion of your compound. Build the intensity of maximum - the concentration of compound Find the concentration when the solubility is no longer moving. This is solubility constant.

Best regards.

Thank you dr.Yuri Mirgorod 

Greeting

You must to prepare a calibration curve by plotting of substance concentrations versus absorbency  of substance at  λmax. A linear relationship is obtained and the slope is calculated  from the graph. Depending on its absorbance , the unknown solubility of your substance is determined as following:

dissolve a large portion of your substance into  solvent ,mix and stir until it will not dissolve further amount and  a saturated solution is approaches, filtration or centrifugation is necessary to remove non-dissolved material. Determine the absorbance of clear solution at same  λmax. Now you can calculate the concentration(solubility) by applying following relationship:

[substance]=absorbance at λmax/slope

Then it is easy to calculate Solubility Product Constant, Ksp

Regards

 Thank you dr.Hassan Alshamsi