Degradation of dansyl polyamines on high-performance thin-layer chromatographic plates

Using high-performance thin-layer chromatography with in situ quantitation to measure dansylated polyamines in the range of 1-20 pmol, we found that dansylated polyamines apparently react with the silica gel of the plates. The fluorescence of the dansyl polyamines diminished with increase in the time interval between application of a sample to the plate and start of the chromatographic separation. Conversely, the fluorescence at the site of application increased with the length of the time interval, indicating the formation of polar reaction products. If this reaction is not accounted for, considerable errors in quantitation of dansyl polyamines may occur.