Comparison of recovery and delivery in vitro for calibration of microdialysis probes

One approach to calibrating a microdialysis probe in vivo is to determine the amount of a test compound that diffuses out of the membrane relative to the amount in the perfusate (i.e., the probes delivery) and assume that the same relation exists for the amount of analyte that will diffuse into the probe relative to the concentration in the sample (i.e., the probes recovery). This concept was systematically tested in vitro with a wide range of compounds, microdialysis probe configurations, dialysis membrane types, and solution conditions. Recovery was found to depend on the identity of the analyte, the type of dialysis membrane, the membrane length, the perfusion flow rate, and the perfusate pH. Recovery was independent of the analyte concentration. No statistically significant difference was found between the recovery and delivery of a given compound with a given probe under any of the conditions tested.