The determination of anticonvulsants in biological samples by use of high-pressure liquid chromatography

The procedure for anticonvulsant analysis represent use of a relatively new technology. The procedures compare favorably in accuracy and precision with accepted methodology using gas chromatography [14]. It is possible to determine a greater number of anticonvulsants simultaneously with liquid chromatography than with reported gas-chromatographic procedures. This is because gas chromatography necessitates manipulation of the sample to be analyzed, the various components of which may have completely different manipulation requirements. Liquid chromatography is able to effect the analysis without extensive manipulation of the sample. The columns recommended in Sect. III are currently available standard columns. Column technology is developing at an accelerating rate. It is now anticipated that new developments in microparticulate packings and improvements in packing techniques will give the analyst greater column efficiency. This may be used either to shorten overall analysis time or to include more drugs in a simultaneous analysis. There is not yet available to the analyst a variety of different detectors suitable for routine use. This situation will change. In the case of the successful use of ultraviolet spectrophotometric detectors, the technique is not being fully exploited. Ultraviolet spectrophotometry is firmly established in practice, but as yet it is not routine to apply dual-wavelength spectroscopy to the column effluent. Application of this technique may be expected to improve selectivity and quantitation besides permitting optical resolution of some components that are not separated by the column. In the procedures given in this chapter there was no detailed discussion on gradient elution. This technique is potentially of great utility for simultaneous analyses of many compounds. It should be used only where isocratic elution is out of the question because it calls for somewhat stricter requirements of equipment in control of chromatography conditions. An additional time for equilibration between analyses may be considered too high a price to pay for any advantage gradient elution may give the analyst. The problem of fully automatic operation of liquid chromatographs for the type of analysis discussed here remains to be solved. Automatic operation would advance the use of liquid chromatography in the clinical laboratory probably more than any other single improvement. However, regardless of refinements of this type, liquid chromatography in its modern manifestation has versatility and sensitivity in abundance for analyzing compounds of toxicological and clinical interest. It will therefore assume greater importance in these areas.