Studies on the quantitative autoradiography. IV. Quantitative reliability of TLC-autoradioluminography.

Phosphor Imaging plates (IPs) with high sensitivity to both low- and high-energy radiation have been on the market since 1988. The TLC-autoradioluminography (ARLG) method was developed utilizing such IPs. The conventional TLC method was suited for discrimination of microradioactive components; however, the method could only present semi-quantitative values. Conversely, the TLC-ARLG method showed completely quantitative values. That is, the TLC-ARLG method could be used to measure the radioactivity ratio between 14C-radiolabeled spots A and B, which were spotted 1 mm apart on a TLC plate, after development with chromatogram, not only when the radioactivity ratio between spots A and B was 1:1, but even when it was 16:1, within the measurement error of +/- 10%. The ARLG method showed sensitivity, resolution, and quantitative reliability far superior to those of the scraping-liquid scintillation counter (LSC) method or radiochromatoscanner method. In the future, the ARLG method will be widely used as a quantitative microanalytical method for unknown radioactive metabolites existing as microcomponents in organisms, especially for quantitative analysis considering mass balance to dose in biological samples, which is considered to be an important point in pharmacokinetic research.