Purity of Standards and Solvents

Abstract

Owing to the greater sensitivity of the ionization detectors, when compared to general staining techniques in paper chromatography and other procedures, one can demonstrate that virtually none of the steroids available as commercial standards produce single peaks. In most instances this is simply a reflection of the presence of a small amount of impurity, rather than decomposition during chromatography. This can be ascertained readily by trapping the main peak and re-injecting into the gas Chromatograph. In a number of instances we have examined commercially available steroids in this manner and have found that only a single peak is obtained following this procedure. Almost none of the commercial steroids can be considered gas chromatographically pure. In some instances it has been quite easy to detect substances with retention times identical to those expected as by-products of the chemical reaction necessary to prepare the standard, or as biological companions where the steroid was obtained through extraction from natural sources. Indeed, the reader must be very cautious in the interpretation of the notation “chromatographically pure.” This, to our knowledge, never refers to “gas chromatographically pure.”