Analysis of amphetamine derivatives in plasma using capillary zone electrophoresis coupled with laser-induced fluorescence after derivatization on solid-phase extraction support

Capillary electrophoresis (CE) is a very powerful analytical technique, consuming very small quantities of samples and solvents. Generally, a UV detector is coupled with CE but for the analysis of drugs in biological fluids, it is necessary to use a more sensitive and selective detector such as laser induced fluorescence (LIF). This detector was used to analyze various. amphetamine derivatives which do not present native fluorescence and therefore a derivatization tag was employed to produce a fluorescent adduct. Fluorescamine, a fluorogene agent, was selected because it reacts with primary amines of amphetamines to give a fluorescent compound negatively charged, which can be analyzed by CZE-LIF. Taking into account the presence of many interfering compounds in biological fluids, analysis of these compounds requires a sample preparation prior to the analysis. Solid phase extraction (SPE) was selected and the derivatization step included. Analysis of independent plasma samples (n = 6) exhibited a relative standard deviation (RSD) of 8%. A relative recovery of 99% was observed for amphetamine, used as a model compound.