DRUG DETERMINATION IN SERUM BY LIQUID-CHROMATOGRAPHY WITH RESTRICTED ACCESS STATIONARY PHASES

Drug determination in serum with restricted access stationary phases is described. With such phases, large molecules such as proteins are eluted in the void volume without destructive accumulation because they have restricted access to some surfaces, but small molecules such as drugs and their metabolites can reach the hydrophobic sites and be separated. Thus, assay of drugs by direct serum injection can be achieved without a sample preparation step such as deproteinization and/or extraction. The restricted access stationary phases include internal-surface reversed-phases (ISRP), shielded hydrophobic phases (SHP), semi-permeable surfaces (SPS), dual zone (DZ) and mixed functional phases (MFP). The characteristics of these stationary phases and their application to the assay of drugs in serum are discussed.