AMONG OTHER THINGS, THIS SEAL SAYS
PURITY Users of Nuclear-Chicago radiochemicals have learned that they can depend on the "Research Quality"seal as a reliable measure of unquestioned purity. To establish radiochemical purity, each lot of every labelled compound bearing this seal is subjected to dilu-
tion analysis of multiple derivatives and to paper and thin-layer chromatography in several solvent systems. Chemical purity is established through further analyticaltestswhich determinemelting point, specific gravity, refractive index, ultraviolet and infrared absorption spectra. Additionally, volatile compounds are subjected to gas chromatography. These c o n t i n u o u s s a f e g u a r d s would be of little use, however, if the purity they guarantee did not survive the rigors of storage and shipment. The fact is that highest levels of purity are maintained in the radiochemicals we deliver. C h e m i c a l s are always " p a c k a g e d " in the form (acid, oxide, etc.) most compatible with chem-
ical and radiation stability, and containers are chosen to preserve the purity of the reagent. Rapid stock turnover and careful inventory control avoid degradation of radiocompounds by self-irradiation. We now offer over 700 different compounds of consistently high purity—C 14 , H3, P32, S35, and CI3S. Please write for current data on these or any other radiochemical product you may need. For immediate information, call us collect at 312 827-4456. NUC:G.
