Maximising microdialysis sampling by optimising the internal probe geometry

An in-house microdialysis probe equipped with 3 different inner cannulae ex hibiting different inner and outer radii was used to sample glucose, maltot riose, maltopentaose and maltoheptaose as model analytes in order to evalua te its performance by means of optimised internal probe geometry. The resul ts were correlated to the inner cannula ratio (R-ir), defined as the inner cannula's inner radius divided by the inner cannula's outer radius. Extract ion fraction (EF) or relative recovery (RR) showed a dependency on R-ir for all the investigated analytes at all the perfusion rates. The EF for gluco se improved up to 10% for a nominal increase of 0.27 in R-ir. The sensitivi ty of the EF of saccharides to R-ir decreased with the size of molecule. Th erefore the R-ir represents a parameter that should be further investigated in order to maximise the performances of concentric type microdialysis pro bes.