This Test Guideline describes a method conducted as model studies to predict the degradation pathway of the active ingredient under hydrolytic conditions, to identify the degradation products, and to determine the relative amount of degradation products. Three representative hydrolysis conditions should be investigated. Radiolabelled active test substance are used to elucidate the possible degradation pathway and for quantitation of the extent of degradation. The use of tritium (3H) as a label is not permitted due to the possibility of hydrogen exchange with the water. The proposed value for the concentration of a water soluble active ingredient in the studies required here is 1.0 mg/L. Samples may be analysed directly by chromatography or may be extracted with a series of solvents or solvent mixtures with various polarities and other characteristics depending on the nature of the expected residues. The characterisation and identification of extractable residues is made. Ideally samples should be stored at/or below -18°C. The report should include the routes of degradation observed, the degradation pathway, the composition of total radioactive residues, the limit of quantification for radioactivity determination and chromatographic separation.