On-line microdialysis offers the unique possibility to obtain real time feedback on neurochemical changes. A method was developed to measure a number of biogenic amines in an online microdialysis setup. An accurate pre-injection micro flow splitter is connected to a dual loop injection valve and analyzed on two parallel LC systems. Both systems are optimized for different components under different LC/EC conditions resulting in the best detection limits.

Chromatograms of rat brain microdialysate recorded with the ALEXYS OMD Monoamines analyzer. The blue traces show the basal levels and the red traces were recorded after stimulation of the brain with L-DOPA and K+ in the microdialysate solution.
For the analysis of microdialysates we selected the VT03 electrochemical cell. This cell not only has an excellent reproducibility but also the best possible detection sensitivity. A 14-port valve is used in combination with a pre-injection micro splitter. An additional valve can be switched in line for analysis of standards for calibration purposes.
The ALEXYS systems comprise the following parts:

No autosampler is required in an on-line setup. See product catalogue for more details.
| Part no | Description |
| 180.0081C | ALEXYS OMD Monoamines Analyzer |