Current techniques for determining the radiochemical purity of 99mTc-labeled radiopharmaceuticals are limited by the variety of compounds that can be tested or the length of time required to complete the test. A chromatographic method, based on the use of 2 solvents (0.9% saline and acetone) and a stationary phase made of silica-coated cellulose strips, solves these problems for H2O-soluble 99mTc-labeled radiopharmaceuticals. With this method, the oxidation state of unbound 99mTc and the labeling yield of 99mTc-labeled radiopharmaceuticals can be quickly determined; the whole procedure takes only a few minutes to run. This system compares favorably with lengthier procedures and with a commercially available kit.