Maximising microdialysis sampling by optimising the internal probe geometry

An in-house microdialysis probe equipped with 3 different inner cannulae exhibiting different inner and outer radii was used to sample glucose, maltotriose, maltopentaose and maltoheptaose as model analytes in order to evaluate its performance by means of optimised internal probe geometry. The results were correlated to the inner cannula ratio (Rir), defined as the inner cannula’s inner radius divided by the inner cannula’s outer radius. Extraction fraction (EF) or relative recovery (RR) showed a dependency on Rir for all the investigated analytes at all the perfusion rates. The EF for glucose improved up to 10% for a nominal increase of 0.27 in Rir. The sensitivity of the EF of saccharides to Rir decreased with the size of molecule. Therefore the Rir represents a parameter that should be further investigated in order to maximise the performances of concentric type microdialysis probes.