The Accuracy and Reproducibility of Radio-Thin Layer Chromatography Measurements of Drugs in Biological Fluids

Summary

The accuracy and reproducibility of radio-thin layer chromatography (RTLC) of radiochemicals in biological fluids was investigated using a RITA 6800 analyzer. When applications were made in a simple matrix (water) with no elution of the plate the accuracy of RTLC was comparable with liquid scintillation counting (LSC). However at low loadings (92 dpm) the standard deviations were more than ten times greater with RTLC than LSC. With spots of approximately 2mm in diameter the position of the detector wire was not critical (± 3mm). Increasing concentrations of biological fluids decreased the number of counts obtained. This was probably caused by a change in the spatial distribution of the radiochemical in the silica. Absorption of the radioactivity by constituents of the biological fluid was not an important factor.