Technical considerations in the use of "high-performance" liquid chromatography in therapeutic drug monitoring.

I review the methodology of "high-performance" liquid chromatography as applied to therapeutic drug monitoring. Aside from direct injection of sample, sample cleanup involves miscible and immiscible organic solvent extractions, solid-phase extraction, and size separations. Column considerations are bonded phases, column dimensions, particle size, guard columns, stability, pH range, and reproducibility. In a section on mobile phase, the reversed-phase mode is discussed along with temperature and degassing. Absorbance and fluorescence detectors are used most commonly. The parameters "capacity factor," "efficiency," and "asymmetry value" are helpful for interpreting chromatograms, as are the aspects of peak tailing, peak quantitation, "complex solutes," and "crowded chromatograms." Finally, automation, competing methodology, and prospects are discussed.