RPRD | A COMPARISON of THIN LAYER CHROMATOGRAPHY RESULTS between THE ROUTINE …

Ki-Young Hwang*, Yong-Hyun Cho, Jun-Hyung Park, Hyung-woo Kim, Hong-Jae Lee, Hyun-Ju Kim

Pet center, Nuclear Medicine, Seoul National University Hospital, Seoul, Korea

Purpose

The aim of this study was to find out a ideal Thin Layer Chromatography (TLC) solvent for routine 18F-FDG Quality Control (Q.C) by comparing Rf value and total elapsed time between 95% acetonitrile and the others.

Materials and Methods

18F-FDG was spotted on a TLC strip that are made of aluminum sheet impregnated with silica gel and then chromatography was carried out by dipping the spotted strip into an appropriate solvent contained in a tube. Used solvents were butanon, methanol, acetone, ethanol, acetonitrile, which were stepwise diluted from 100% to 60% by D.W. and saline. When the solvent front moves to a desired distance, the strip is removed from the tube, dried. it measured on the TLC scanner (BIOSCAN, model AR-2000, USA).

Results

The total elapsed time was measured until each solvent was moved up to the solvent front of strip. Then two fragments (free 18F , 18F-FDG) were acquired by TLC scanner. The average elapesd time both 95% methanol and ethanol is 36 minutes and 1 hour, but acetone and acetonitrile is 17 and 15 minutes. The distance of free Rf value of methanol, ethanol and acetone was 0.05 whereas acetonitrile was 0.07. Bound Rf value of methanol and ethanol was 0.43 and 0.38, but acetone and acetonitrile was 0.24 and 0.26.

Conclusion

TLC is a simple and fast method to determine the radiochemical purity for radiopharmaceuticals. The Rf value of each fragment both methanol and ethanol is a ideal, but it takes over 30 minutes. Although the elapsed time of acetone is ideal, 16 minutes, the Rf value of free appears earlier front distance. The acetonitrile we have been using, has shown the ideal Rf and time. Also It is helpful to confirm the Rf distance clearly between free and bound form. Lastly, we have recommended that 90% acetonitrile-saline solution is better than 95% acetonitrile-D.W., because we can distinguish the Rf value more clearly.

Key words: Thin Layer Chromatography, Rf,value, quality control