To determine the concentration of organic materials in aqueous solution , fis remove the solvent using lipoliser . Then Check whether it sepatates out on TLC.Make preparative TLC & isolate compd.Measure con. by measuring UV absorbance(O.D.) on the standard plot of O.D.vs concentration with known sample.
Chemical oxygen demand (COD) test is commonly used in environmental chemistry to quantify the contamination of water by organic matter. Just Google and find how to measure COD.