A special chlorophyll, designated chlorophyll RC I, has been reported by our and other laboratories to be a stable chlorophyll, extractable from organisms with oxygenic photosynthesis. Its structure was revealed as 132-hydroxy-20-chloro-chlorophyll a. We revise the finding that chlorophyll RC I is a naturally occurring chlorophyll, and show that it is an artificial chlorination product created during thin-layer chromatography on silica gel. Simultaneous hydroxylation prevents further chlorination and stabilizes the already chlorinated chlorophylls. Avoiding TLC by applying HPLC we were unable to find chlorinated chlorophylls in pigment extracts and, therefore conclude that chlorophyll RC I is an artefact generated during thin-layer chromatography.
