Two weekends ago, Sciencemadness member (and good friend) Amos happened to be in Austin for vacation, so we met up and though we didn’t have much time, we were still able to do some chemistry together.
Anthocyanin Extraction from Mealy Sage
During the spring in the Texas Hill Country, the landscape is filled with wildflowers, and my front yard becomes covered with a plant called mealy sage, which grows three to four feet tall and has beautiful purple flowers. I had trimmed a lot of it back from the sidewalk, and as a result had a substantial amount of extra flowers laying around.
We extracted the flowers with methanol, acidified with a couple mL of HCl. I had done an extraction of the same flowers a few years ago using neutral methanol and it didn’t work very well. Amos said that when he had done extractions of anthocyanin based plant pigments in the past, he found that extracting with acid would stabilize the pigment and give it a much longer shelf life.
The flowers were filtered out, leaving a reddish bronze colored solution. Guessing that the murky color was due to chlorophyll, the solution was transferred to a separatory funnel. 50 ml of water was added, and the solution was extracted with 3 mL of heptanes three times. The heptane layer became olive green on the first wash due to chlorophyll, pale yellow on the second wash, and nearly colorless on the third. The methanol layer was now a brilliant red wine color, and crystal clear. When neutralized, the color of the extract changes from red to pale purple, and then to green as it becomes mildly basic. In strongly basic conditions, the color changes to pale yellow, and the pigment degrades. In a later post, a picture of the extract at various pH values will be posted.
Exploration of an Interesting Patent
Our main experiment of the weekend was testing an interesting and potentially very useful patent that I unearthed recently in an old book. We weren’t successful, but I feel like I could still get it to work, so I’m going to hold off on saying any more about it until I’ve explored it further. For now, I’ll only post this picture as a preview: