An Improved Internal Surface Reversed Phase

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Abstract
Invented by Dr. Thomas C. Pinkerton, the Internal Surface Reversed Phase (ISRP) allows the direct analysis of serum and body fluids without requiring the prior removal of protein. The first ISRP, based on glycine - phenylalanine - phenylalanine (GFF) bonded to 80A spherical silica, proved to have excellent column life, phenomenal selectivity, and further capabilities not originally perceived. However, its original synthesis yields a material that, being partially polymeric, is difficult to reproduce. Moreover, chromatographically the original ISRP shows poor efficiency and retentivity. Each is lower than either expectable or desirable. A revised synthesis has yielded an inherently monomeric GFF much easier to reproduce. Although the carbon load of the new ISRP is lower than that of its predecessor, its efficiency and retentivity are now adequate. For carbamazepine, the efficiency is now 60,000 plates per meter (up from 25,000 to 35,000); and the retention has more than doubled. These characteristics suggest that the molecular elements of the new stationary phase are used more efficiently than those of the old.