Study and analytical application of ion-pair formation in the system fluoxetine-pyrocatechol violet and fluvoxamine-pyrocatechol violet.

Pyrocatechol violet (PCV) reacts in aqueous media with fluoxetine (FLX) and fluvoxamine (FLV) forming coloured ion-association complexes, which are insoluble in water but quantitatively extracted into chloroform-n-butanol mixture. The composition of the compounds, studied by spectrophotometric methods showed that the molar ratio PCV : FLX and PCV : FLV is 1 : 1. The compounds were characterized by UV-VIS, IR and NMR spectrometry. Under optimal experimental conditions fluoxetine and fluvoxamine were determined in the range 1.3-18.0 microg/ml and 2.6-39.1 microg/ml, respectively. The proposed methods have been succesfully applied to the determination of these drugs in pharmaceuticals and natural samples.