ENERGY-TRANSFER BY LUMINESCENCE USE OF LA NTHANIDES IN THE DETECTION OF PHARMACEUTICAL AND BIOLOGICAL COMPONENTS IN LIQUID-CHROMATOGRAPHY AND CAPILLARY ELECTROPHORESIS

Energy transfer by luminescence: use of lanthanides in the detection o f pharmaceutical and biological components in liquid chromatography an d capillary electrophoresis. Lanthanide sensitized luminescence is a v ery attractive alternative to UV detection and other luminescence tech niques, ie, fluorescence and phosphorescence in separation sciences re garding the detection of drugs and xenobiotics because of the large St okes shift, narrow emission band and long lifetime. After reporting th eoretical luminescence properties of lanthanides in solution, we have reviewed some published applications of HPLC determination with Ln(3+) sensitized luminescence detection. Advantages and limitations of this technique are discussed. Normal phase (NP) HPLC is very attractive du e to the lack of quenching effect of water whilst reversed-phase (RP) HPLC is applicable to more compounds than NP-HPLC. However, pH adjustm ent and quenching effect of water on Ln(3+) luminescence are the main drawbacks of RP HPLC. Elution properties and pH adjustment are two arg uments to select the mode of addition of Ln(3+), ie, pre- or post-colu mn in the HPLC system. Sensitized Ln(3+) luminescence detection is a m uch more specific method of detection than UV or fluorescence after HP LC separation but nevertheless does not always exhibit a significant i ncrease in analytical performance when the donor itself is a strong fl uorophore. Development of more powerful excitation sources could impro ve the limit of detection of the Ln(3+) sensitized detection technique . First determinations by capillary electrophoresis using Ln(3+) sensi tized luminescence seem limited by not fully adapted apparatus. This r eview suggests that it would be useful to obtain predicting factors ab out the drug to know whether it is suitable to be measured by an HPLC/ Ln(3+) approach.