UHPLC with electrochemical detection for in vivo monoamine measurements - The quest for selectivity, sensitivity and throughput.

Monitoring of changes in neurotransmitter concentrations in the brain using in vivo microdialysis sampling is an important tool in neuropharmacological research in the quest for new drug candidates. Quantitative determination of these neurotransmitters in the collected samples requires sufficient selectivity, high sensitivity and fast sample throughput. In order to deal with the latest neuropharmacological innovations, such as a multi-target strategy and examination of small challenging brain regions in freely moving laboratory animals, it is necessary to stay up to date with current and promising advances in analytical chemistry. For the fast and sensitive, simultaneous quantification of the extracellular dopamine, noradrenaline and serotonin levels under basal conditions and in response to a pharmacological manipulation, microbore ultra-high performance liquid chromatography (UHPLC) coupled to electrochemical detection (ECD) is shown to be a convenient and successful analysis technique. Different problems are encountered during method development, for instance stability of the analytes, peak-splitting during fast analyses, extra-column band broadening and sample overloading. By means of smart strategies such as the kinetic plot approach and design of experiments, an optimized and validated UHPLC-ECD method is described for simultaneous monoamine monitoring, next to an application in neuropharmacological research targeting the monoaminergic system. Along with other upcoming developments in bioanalysis, this work is of particular interest for future contributions to in vivo neuropharmacological research.