Recently it occurred to me that there might be another use of PSU, to manage my collections of images of thin-layer chromatography plates. Lichens have complex secondary metabolites that can be extracted with acetone. These extracts then can be placed on a silica coated glass plate, a solvent migrating through the silica will drag along the secondary metabolites. Some have a stronger affinity to a particular solvent, these secondary metabolites travel faster than others. The metabolites also have different colors in visible and UV light of different wavelengths, and these colors differ before and after treating them with sulfuric acid and heat.
The image below is one single plate with 13 lichen extracts (the lines numbered 13-25). The image is a composite of four, at the top the plate before it was treated with sulfuric acid, at two different wavelengths of UV light. The upper right image of the plate shows a bright green fluorescence because of a fluorescent indicator embedded into the silica plate, which facilitates viewing how the substances traveled on the plate. The image on the upper left show distinctive colors. After treatment with sulfuric acid the substances develop a distinct color that can also be seen in visible light (on the lower left), and these colors now show a distinctly different color reaction.
All these aspects are useful in determining what secondary metabolites are present in a lichen. And which particular substances are present in turn helps to distinguish/identify the different species. I have a small database program that can be fed with all that information, filtering out possible results. Once the plates have been analyzed I use Photoshop to place small captions on these images, which spots represent what particular substance. Thus, the first two lichens on this particular plate (row #13 and #14) for example contain usnic acid and zeorin:
- PSU_example-TLC.jpg (210.83 KiB) Viewed 12357 times
I have been thinking of tagging the plates with:
- Date when the plate was run
- person who ran the plate
- plate number
- solvent
But here is where things get complicated:
Each row represents one particular lichen specimen. I could use area-tags for marking these rows.
But on each of the four images in the composite figure there are 13 separate rows. In the example above four times row number row #13, four times row #14, etc. drawing and tagging all those can take quite some time...
Worse: each row contains colorful spots, each spot a different metabolite. Again as an example: usnic acid in rows #13 and #14 is dark (black) in UV light (both before and after treatment with sulfuric acid), but dark green in visible light. Zeorin cannot be seen before applying sulfuric acid, but is pale pinkish violet afterwards, both in visible and UV light (the lower two images of the plate).
Area-tagging all rows on all plates and all the different spots these images might become really cluttered. So, I thought I should just use labels for the 13 specimens analyzed on a plate, not using area tags, and use area tags only for the spots (i.e., the secondary metabolites).
Or perhaps not use area tags at all, but simply continue labeling the spots in Photoshop?
I know this might seem like a rather unusual request, but I thought I still explain this here and perhaps someone has some better ideas...
Thank you!!!
