On-chip product purification for complete microfluidic radiotracer synthesis

Solid phase extraction was incorporated into an electrowetting-on-dielectric chip for radiochemical purification of a positron emission tomography tracer that was radiolabeled on the same chip. The radiotracer droplet was mixed with alumina particles, and the alumina particles were filtered out from the droplet through a line of pillars, all by electrowetting droplet movement. Fluorination reaction and on-chip purification were analyzed with both Cerenkov imaging and off-chip radio-thin layer chromatography measurements. The measurements were compared to test the validity of the combined use of filtration on-chip and Cerenkov imaging as an alternative approach for monitoring reaction yield without the need to extract sample from the chip.