ABSTRACT
With the advent of gas chromatography, high-performance chromatographic techniques became available to clinical laboratories. Gas chromatography provided the speed, resolution, and sensitivity that was necessary in many analyses. The slower rate of growth in high-performance liquid chromatographic (HPLC) has been due primarily to the need for more extensive developments in columns and instrumentation than was necessary in gas chromatography. The selection of a column for HPLC is dependent upon the physical properties of the substance to be analyzed and the medium in which it is found. A variety of methods of separation are available which selectively retain molecules on the basis of charge, polarity, hydrophobicity, size, or solubility. Reversed-phase chromatography is the separation of compounds according to their hydrophobic character and their relative solubilities in aqueous and organic solvents. Reversed-phase supports are prepared by binding an aliphatic organosilane to the surface of silica particles.
