Development of a standardized analysis strategy for basic drugs using ion-pair extraction and high-performance liquid chromatography - I. Philosophy and selection of extraction technique.
The first of a series of papers on the development of a standardized analysis strategy for basic drugs explains the possible advantages and philosophy of the strategy. The scheme uses ion-pair extraction with direct injection of the extracts into an HPLC system emanating, from two previously-selected systems. The extraction efficiency of sodium-n-octylsulphate as the ion-pairing reagent is compared with that of di(2-ethylhexyl) phosphoric acid (previously shown to be generally applicable to the extraction of basic drugs). Direct injection of the ion-pair extracts into an HPLC system is possible because retention behaviour is independent of whether the basic drugs are injected as an ion-pair or as a base.
Hoogewijs
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Farmaceutisch Instituut, Vrije Universiteit Brussel, Laarbeeklaan 103, B-1090 Brussel, Belgium.
Massart
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DL