Methods are proposed for the determination of113Sn in the eluate of an113mIn generator as well as for the analysis of its chemical and radionuclidic purity. Two generators of different origin have been studied. The presence of the radioisotopes113Sn,125Sb,125mTe and the elements Zr, Si and Fe have been found in the eluate. Recommendations are given for the use of such generators.