Microdialysis analyte recovery, determination

Diameter and length of the microdialysis probe are determined by the site of sampling (see below). In general, the larger the area of the membrane, the higher the recovery of the analyte. 

Microdialysis has also a number of disadvantages the probe could elicit tissue trauma after implantation, the determination of in vivo recovery is time-consuming and sensitive analytical methods are needed due to the diluting effect (De Lange). 

In ultrafiltration, analyte molecules are basically carried along with the flow of water and electrolytes. The factors determining recovery in ultrafiltration are membrane characteristics, temperatme, and chemistry of the analyte. Unlike microdialysis, recovery is not dependent on flow rate, membrane surface area, or probe size. Recovery tends to be higher than for dialysis, since there is no perfusion medium to dilute the collected analyte. Ultrafiltration recovery rates are typically in the 90-100% range. This high recovery rate simplifies determination of in vivo analyte concentrations. Table I illustrates some in vitro recoveries obtainable with ultrafiltration probes. 

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